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Sample records for performance carbon beam

  1. Dielectric performance of diamond-like carbon nanofilms deposited by electron-beam-induced deposition

    NASA Astrophysics Data System (ADS)

    Balaur, Eugeniu; Peele, Andrew G.

    2008-12-01

    The effect of electron beam dose and low accelerating voltage on diamond-like-carbon (DLC) deposition rate and the resulting current-voltage characteristics in thin metal/DLC/semiconductor junctions was studied. We show that thicker DLC films can be obtained using lower accelerating voltages (2 kV) than when using higher accelerating voltage (20 kV). However, under the conditions used the insulating performance of the thicker films is worse than the thinner films. We attribute this effect to the variation of tunnelling barrier height in DLC deposited using different accelerating voltages. DLC films with a tunnelling barrier height of up to 3.12 eV were obtained using a 20 kV electron-beam, while only 0.73 eV was achieved for 2 kV DLC films.

  2. Characterization and performance of carbon films deposited by plasma and ion beam based techniques

    SciTech Connect

    Walter, K.C.; Kung, H.; Levine, T.

    1994-12-31

    Plasma and ion beam based techniques have been used to deposit carbon-based films. The ion beam based method, a cathodic arc process, used a magnetically mass analyzed beam and is inherently a line-of-sight process. Two hydrocarbon plasma-based, non-line-of-sight techniques were also used and have the advantage of being capable of coating complicated geometries. The self-bias technique can produce hard carbon films, but is dependent on rf power and the surface area of the target. The pulsed-bias technique can also produce hard carbon films but has the additional advantage of being independent of rf power and target surface area. Tribological results indicated the coefficient of friction is nearly the same for carbon films from each deposition process, but the wear rate of the cathodic arc film was five times less than for the self-bias or pulsed-bias films. Although the cathodic arc film was the hardest, contained the highest fraction of sp{sup 3} bonds and exhibited the lowest wear rate, the cathodic arc film also produced the highest wear on the 440C stainless steel counterface during tribological testing. Thus, for tribological applications requiring low wear rates for both counterfaces, coating one surface with a very hard, wear resistant film may detrimentally affect the tribological behavior of the counterface.

  3. Electron Beam Exposure of Thermal Control Paints on Carbon-Carbon and Carbon-Polyimide Composites

    NASA Astrophysics Data System (ADS)

    Jaworske, Donald A.

    2006-01-01

    Carbon-carbon and carbon-polyimide composites are being considered for use as radiator face sheets or fins for space radiator applications. Several traditional white thermal control paints are being considered for the surface of the composite face sheets or fins. One threat to radiator performance is high energy electrons. The durability of the thermal control paints applied to the carbon-carbon and carbon-polyimide composites was evaluated after extended exposure to 4.5 MeV electrons. Electron exposure was conducted under argon utilizing a Mylar™ bag enclosure. Solar absorptance and infrared emittance was evaluated before and after exposure to identify optical properties degradation. Adhesion of the paints to the carbon-carbon and carbon-polyimide composite substrates was also of interest. Adhesion was evaluated on pristine and electron beam exposed coupons using a variation of the ASTM D-3359 tape test. Results of the optical properties evaluation and the adhesion tape tests are summarized.

  4. Radiotherapy with beams of carbon ions

    NASA Astrophysics Data System (ADS)

    Amaldi, Ugo; Kraft, Gerhard

    2005-08-01

    In cancer treatment, the introduction of MeV bremsstrahlung photons has been instrumental in delivering higher doses to deep-seated tumours, while reducing the doses absorbed by the surrounding healthy tissues. Beams of protons and carbon ions have a much more favourable dose-depth distribution than photons (called 'x-rays' by medical doctors) and are the new frontiers of cancer radiation therapy. Section 2 presents the status of the first form of hadrontherapy which uses beams of 200-250 MeV protons. The central part of this review is devoted to the discussion of the physical, radiobiological and clinical bases of the use of 400 MeV µ-1 carbon ions in the treatment of radio-resistant tumours. These resist irradiation with photon as well as proton beams. The following section describes the carbon ion facilities that are either running or under construction. Finally, the projects recently approved or proposed are reviewed here.

  5. Scanned Carbon Pencil Beams for Tumor Therapy

    SciTech Connect

    Gemmel, A.; Saito, N.; Chaudhri, N.; Luechtenborg, R.; Schardt, D.; Bert, Ch.; Rietzel, E.

    2009-03-10

    At GSI a fully active beam application has been developed for tumor therapy with carbon ions. In this so-called rasterscan system the tumor volume is typically split into {approx}60 slices of iso-energies taken from a list of 252 energies ranging from {approx}90-430 MeV/u(range: 1.8-30.7 cm). The energies can be combined with variable beam diameters and intensities. For each iso-energy slice beam is requested from the synchrotron and delivered as a narrow pencil beam (beam's full width at half maximum 3-10 mm). For lateral target coverage this pencil beam is deflected to several hundreds of grid positions per iso-energy slice by orthogonal dipole magnets. At each grid position an optimized number of particles is deposited intensity-controlled, i.e. ionization chambers monitor the dose deposition and trigger deflection to the next grid position once the required dose level is achieved. This method allows intensity-modulated treatment fields necessary to deposit a uniform biological effective dose. Additionally, it allows for simultaneous optimization of multiple fields that allow better sparing of organs at risk partially or fully surrounded by the tumor. Scanned beam delivery facilitates target conformal and homogeneous dose delivery for stationary targets. For tumors located in the head and neck as well as tumors in the pelvic region very promising results were achieved in the carbon therapy pilot project started at GSI in 1993. A comparable project is conducted at Paul-Scherrer-Institut (PSI) in Switzerland with a scanned proton beam. One of the current research topics is the treatment of moving targets such as lung tumors. Scanned beam delivery requires but also offers possibilities to conformably irradiate moving target sites.

  6. Scanned Carbon Pencil Beams for Tumor Therapy

    NASA Astrophysics Data System (ADS)

    Gemmel, A.; Saito, N.; Chaudhri, N.; Lü; chtenborg, R.; Schardt, D.; Rietzel, E.; Bert, Ch.

    2009-03-01

    At GSI a fully active beam application has been developed for tumor therapy with carbon ions. In this so-called rasterscan system the tumor volume is typically split into ˜60 slices of iso-energies taken from a list of 252 energies ranging from ˜90-430 MeV/u (range: 1.8-30.7 cm). The energies can be combined with variable beam diameters and intensities. For each iso-energy slice beam is requested from the synchrotron and delivered as a narrow pencil beam (beam's full width at half maximum 3-10 mm). For lateral target coverage this pencil beam is deflected to several hundreds of grid positions per iso-energy slice by orthogonal dipole magnets. At each grid position an optimized number of particles is deposited intensity-controlled, i.e. ionization chambers monitor the dose deposition and trigger deflection to the next grid position once the required dose level is achieved. This method allows intensity-modulated treatment fields necessary to deposit a uniform biological effective dose. Additionally, it allows for simultaneous optimization of multiple fields that allow better sparing of organs at risk partially or fully surrounded by the tumor. Scanned beam delivery facilitates target conformal and homogeneous dose delivery for stationary targets. For tumors located in the head & neck as well as tumors in the pelvic region very promising results were achieved in the carbon therapy pilot project started at GSI in 1993. A comparable project is conducted at Paul-Scherrer-Institut (PSI) in Switzerland with a scanned proton beam. One of the current research topics is the treatment of moving targets such as lung tumors. Scanned beam delivery requires but also offers possibilities to conformably irradiate moving target sites.

  7. Electron Beam Exposure of Thermal Control Paints on Carbon-Carbon and Carbon-Polyimide Composites

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.

    2006-01-01

    Carbon-carbon and carbon-polyimide composites are being considered for use as radiator face sheets or fins for space radiator applications. Several traditional white thermal control paints are being considered for the surface of the composite face sheets or fins. One threat to radiator performance is high energy electrons. The durability of the thermal control paints applied to the carbon-carbon and carbon-polyimide composites was evaluated after extended exposure to 4.5 MeV electrons. Electron exposure was conducted under argon utilizing a Mylar(TradeMark) bag enclosure. Solar absorptance and infrared emittance was evaluated before and after exposure to identify optical properties degradation. Adhesion of the paints to the carbon-carbon and carbon-polyimide composite substrates was also of interest. Adhesion was evaluated on pristine and electron beam exposed coupons using a variation of the ASTM D-3359 tape test. Results of the optical properties evaluation and the adhesion tape tests are summarized.

  8. Radiotherapy systems using proton and carbon beams.

    PubMed

    Jongen, Y

    2008-01-01

    Radiotherapy using proton beams (proton therapy) is rapidly taking an important role among the techniques used in cancer therapy. At the end of 2007, 65.000 patients had been treated for cancer by proton beams in one of the 34 proton therapy facilities operating in the world. When compared to the now classical IMRT, and for a similar dose to the tumor, proton therapy provides a lower integral dose to the healthy organs surrounding the tumor. It is generally accepted that any reduction of the dose to healthy organs reduces the probability of radiation induced complications and of secondary malignancies. Proton therapy equipment can be obtained today from well established medical equipment companies such as Varian, Hitachi or Mitsubishi. But it is a Belgian company, Ion Beam Applications of Louvain-la-Neuve that is the undisputed leader in this market, with more than 55% of the world installed base. In addition to the now classical proton therapy equipments, using synchrotrons or cyclotrons as accelerators, new solutions have been proposed, claiming to be more compact and less expensive. A small startup company from Boston (Still Rivers) is proposing a very high magnetic field, gantry mounted superconducting synchrocyclotron. The us Company Tomotherapy is working to develop a new accelerator concept invented at Lawrence Livermore National Laboratory: the Dielectric Wall Accelerator. Besides proton beam therapy, which is progressively becoming an accepted part of radiation therapy, interest is growing for another form of radiotherapy using ions heavier than protons. Carbon ions have, even to a higher degree, the ballistic selectivity of protons. In addition, carbon ions stopping in the body exhibit a very high Linear Energy Transfer (LET). From this high LET results a very high Relative Biological Efficiency (RBE). This high RBE allows carbon ions to treat efficiently tumors who are radio-resistant and which are difficult to treat with photons or protons. The largest

  9. Determining activated carbon performance

    SciTech Connect

    Naylor, W.F.; Rester, D.O.

    1995-07-01

    This article discusses the key elements involved in evaluating a system`s performance. Empty bed contact time (EBCT) is a term used to describe the length of time a liquid stream being treated is in contact with a granular activated carbon bed. The EBCT is the time required for a fluid to pass through the volume equivalent of the media bed, without the media being present. In a bed of granular activated carbon, the void volume or space between particles is usually about 45 percent. Therefore, the EBCT is about twice the true or actual time of contact between the fluid being treated and the GAC particles. The EBCT plays an important role in determining the effectiveness and longevity of granular activated carbon (GAC) used to treat liquids in a fixed-bed adsorber. Factors that influence and are influenced by EBCT, and their relationship to GAC performance in a treatment scheme include: adsorption, mass transfer zone, impurity concentration, adsorption affinity, flow rate and system design considerations.

  10. Joining Carbon-Carbon Composites and High-Temperature Materials with High Energy Electron Beams

    NASA Technical Reports Server (NTRS)

    Goodman, Daniel; Singler, Robert

    1998-01-01

    1. Program goals addressed during this period. Experimental work was directed at formation of a low-stress bond between carbon- carbon and aluminum, with the objective of minimizing the heating of the aluminum substrate, thereby minimizing stresses resulting from the coefficient of thermal expansion (CTE) difference between the aluminum and carbon-carbon. A second objective was to form a bond between carbon-carbon and aluminum with good thermal conductivity for electronic thermal management (SEM-E) application. 2. Substrates and joining materials selected during this period. Carbon-Carbon Composite (CCC) to Aluminum. CCC (Cu coated) to Aluminum. Soldering compounds based on Sn/Pb and Sn/Ag/Cu/Bi compositions. 3. Soldering experiments performed. Conventional techniques. High Energy Electron Beam (HEEB) process.

  11. Treatment of industrial effluents using electron beam accelerator and adsorption with activated carbon: a comparative study

    NASA Astrophysics Data System (ADS)

    de Oliveira Sampa, Maria Helena; Rela, Paulo Roberto; Casas, Alexandre Las; Mori, Manoel Nunes; Duarte, Celina Lopes

    2004-09-01

    This paper presents preliminary results of a study that compares the use of electron beam processing and activated carbon adsorption to clean up a standardized organic aqueous solution and a real industrial effluent. The electron beam treatment was performed in a batch system using the IPEN's Electron Beam Accelerators from Radiation Dynamics Inc., Dynamitron 37.5 kW. The granular activated carbon removal treatment was performed using charcoal made from wood "pinus". If the adequate irradiation dose is delivered to the organic pollutant, it is possible to conclude for the studied compounds that the Electron Beam Process is similar to the activated carbon process in organic removal efficiency.

  12. Beam profile effects on NPB performance

    SciTech Connect

    Leclaire, R.J. Jr.; Bunker, W.J.

    1988-03-01

    A comparison of neutral particle beam (NPB) brightness for various neutral beam profiles indicates that the widely used assumption of a Gaussian profile may be misleading for collisional neutralizers. An analysis of available experimental evidence shows that lower peaks and higher tails, compared to a Gaussian beam profile, are observed out of collisional neutralizers, which implies that peak brightness is over estimated, and for a given NPB platform-to-target range, the beam current (power), dwell time or some combination of such engagement parameters would have to be altered to maintain a fixed dose on the target. Based on the present analysis, this factor is nominally about 2.4 but may actually be as low as 1.8 or as high as 8. This is an important consideration in estimating NPB constellation performance in SDI engagement contexts.

  13. Shunting arc plasma source for pure carbon ion beam.

    PubMed

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse.

  14. Light beam deflector performance: a comparative analysis.

    PubMed

    Zook, J D

    1974-04-01

    The performance of various types of analog light beam deflectors is summarized, and their relative positions in a deflector hierarchy are defined. The three types of deflectors considered are (1) mechanical (galvanometer) mirror deflectors, (2) acoustooptic deflectors, and (3) analog electrooptic deflectors. Material figures of merit are defined and compared, and the theoretical trade-off between speed and resolution is given for each type of deflector. PMID:20126095

  15. Beam commissioning of a superconducting rotating-gantry for carbon-ion radiotherapy

    NASA Astrophysics Data System (ADS)

    Iwata, Y.; Fujimoto, T.; Matsuba, S.; Fujita, T.; Sato, S.; Furukawa, T.; Hara, Y.; Mizushima, K.; Saraya, Y.; Tansho, R.; Saotome, N.; Shirai, T.; Noda, K.

    2016-10-01

    A superconducting rotating-gantry for carbon-ion radiotherapy was developed. This isocentric gantry can transport carbon ions having kinetic energies of between E=430 and 48 MeV/u to an isocenter over an angle of ±180°, and is further capable of performing three-dimensional raster-scanning irradiation. Construction of the entire rotating-gantry system was completed by the end of September 2015. Prior to beam commissioning, phase-space distributions of extracted carbon beams from the synchrotron were deduced by using an empirical method. In this method, phase-space distributions at the extraction channel of the synchrotron were modeled with 8 parameters, and the best parameters were determined so as to minimize a difference between the calculated and measured beam profiles by using a simplex method. Based on the phase-space distributions, beam optics through the beam-transport lines as well as the rotating gantry were designed. Since horizontal and vertical beam emittances, as extracted slowly from the synchrotron, generally differ with each other, a horizontal-vertical beam coupling would occur when the gantry rotates. Thus, the size and shape of beam spots at the isocenter should vary depending on the gantry angle. To compensate for the difference in the emittances, we employed a method to utilize multiple Coulomb scattering of the beam particles by a thin scatterer. Having compensated for the emittances and designed beam optics through the rotating gantry, beam commissioning over various combinations of gantry angles and beam energies was performed. By finely tuning the superconducting quadrupoles of the rotating gantry, we could successfully obtain the designed beam quality, which satisfies the requirements of scanning irradiation.

  16. Focused Ion Beam Microscopy of ALH84001 Carbonate Disks

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Clemett, Simon J.; Bazylinski, Dennis A.; Kirschvink, Joseph L.; McKay, David S.; Vali, Hojatollah; Gibson, Everett K., Jr.; Romanek, Christopher S.

    2005-01-01

    Our aim is to understand the mechanism(s) of formation of carbonate assemblages in ALH84001. A prerequisite is that a detailed characterization of the chemical and physical properties of the carbonate be established. We present here analyses by transmission electron microscopy (TEM) of carbonate thin sections produced by both focused ion beam (FIB) sectioning and ultramicrotomy. Our results suggest that the formation of ALH84001 carbonate assemblages were produced by considerably more complex process(es) than simple aqueous precipitation followed by partial thermal decomposition as proposed by other investigators [e.g., 1-3].

  17. Operational Performance of LCLS Beam Instrumentation

    SciTech Connect

    Loos, Henrik; Akre, R.; Brachmann, A.; Coffee, R.; Decker, F.-J.; Ding, Y.; Dowell, D.; Edstrom, S.; Emma, P.; Fisher, A.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, Ph.; Huang, Z.; Iverson, R.; Messerschmidt, M.; Miahnahri, A.; Moeller, S.; Nuhn, H.-D.; Ratner, D.; /SLAC /LLNL, Livermore

    2010-06-15

    The Linac Coherent Light Source (LCLS) X-ray FEL utilizing the last km of the SLAC linac has been operational since April 2009 and finished its first successful user run last December. The various diagnostics for electron beam properties including beam position monitors, wire scanners, beam profile monitors, and bunch length diagnostics are presented as well as diagnostics for the X-ray beam. The low emittance and ultra-short electron beam required for X-ray FEL operation has implications on the transverse and longitudinal diagnostics. The coherence effects of the beam profile monitors and the challenges of measuring fs long bunches are discussed.

  18. Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation

    NASA Technical Reports Server (NTRS)

    Ziegler, Kirk J. (Inventor); Rauwald, Urs (Inventor); Hauge, Robert H. (Inventor); Schmidt, Howard K. (Inventor); Smalley, Richard E. (Inventor); Kittrell, W. Carter (Inventor); Gu, Zhenning (Inventor)

    2013-01-01

    According to some embodiments, the present invention provides a method for attaining short carbon nanotubes utilizing electron beam irradiation, for example, of a carbon nanotube sample. The sample may be pretreated, for example by oxonation. The pretreatment may introduce defects to the sidewalls of the nanotubes. The method is shown to produces nanotubes with a distribution of lengths, with the majority of lengths shorter than 100 tun. Further, the median length of the nanotubes is between about 20 nm and about 100 nm.

  19. FIDDLING CARBON STRINGS WITH POLARIZED PROTON BEAMS.

    SciTech Connect

    HUANG, H.; KURITA, K.

    2006-05-01

    An innovative polarimeter based on proton carbon elastic scattering in the Coulomb Nuclear Interference (CNI) region was first tested in the Brookhaven AGS successfully. CNI Polarimeters were then installed in the AGS and both RHIC rings. The polarimeter consists of ultra-thin carbon targets and silicon strip detectors. The waveform digitizers are used for signal readout, which allows deadtime-less data processing on the fly. Polarimeters are crucial instrumentation for the RHIC spin physics program. This paper summarizes the polarimeter design issues and operation results.

  20. Hadron Cancer Therapy - relative merits of X-ray, proton and carbon beams

    NASA Astrophysics Data System (ADS)

    Jakel, Oliver

    2014-03-01

    -Heidelberg University has a long experience in radiotherapy with carbon ions, starting with a pilot project at GSI in 1997. This project was jointly run by the Dep. for Radiation Oncology of Heidelberg University, GSI and the German Cancer Research Center (DKFZ). A hospital based heavy ion center at Heidelberg University, the Heidelberg Ion Beam Therapy Center (HIT) was proposed by the same group in 1998 and started clinical operation in late 2009. Since then nearly 2000 patients were treated with beams of carbon ions and protons. Just recently the operation of the world's first and only gantry for heavy ions also started at HIT. Patient treatments are performed in three rooms. Besides that, a lot of research projects are run in the field of Medical Physics and Radiobiology using a dedicated experimental area and the possibility to use beams of protons, carbon, helium and oxygen ions being delivered with the raster scanning technique.

  1. Carbon-nanotube electron-beam (C-beam) crystallization technique for silicon TFTs

    NASA Astrophysics Data System (ADS)

    Lee, Su Woong; Kang, Jung Su; Park, Kyu Chang

    2016-02-01

    We introduced a carbon-nanotube (CNT) electron beam (C-beam) for thin film crystallization and thin film transistor (TFT) applications. As a source of electron emission, a CNT emitter which had been grown on a silicon wafer with a resist-assisted patterning (RAP) process was used. By using the C-beam exposure, we successfully crystallized a silicon thin film that had nano-sized crystalline grains. The distribution of crystalline grain size was about 10 ˜ 30 nm. This nanocrystalline silicon thin film definitely had three crystalline directions which are (111), (220) and (311), respectively. The silicon TFTs crystallized by using a C-beam exposure showed a field effect mobility of 20 cm2/Vs and an on/off ratio of more than 107. The C-beam exposure can modify the bonding network of amorphous silicon with its proper energy.

  2. Ion beam and plasma methods of producing diamondlike carbon films

    NASA Technical Reports Server (NTRS)

    Swec, Diane M.; Mirtich, Michael J.; Banks, Bruce A.

    1988-01-01

    A variety of plasma and ion beam techniques was employed to generate diamondlike carbon films. These methods included the use of RF sputtering, dc glow discharge, vacuum arc, plasma gun, ion beam sputtering, and both single and dual ion beam deposition. Since films were generated using a wide variety of techniques, the physico-chemical properties of these films varied considerably. In general, these films had characteristics that were desirable in a number of applications. For example, the films generated using both single and dual ion beam systems were evaluated for applications including power electronics as insulated gates and protective coatings on transmitting windows. These films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Nuclear reaction and combustion analysis indicated hydrogen to carbon ratios to be 1.00, which allowed the films to have good transmittance not only in the infrared, but also in the visible. Other evaluated properties of these films include band gap, resistivity, adherence, density, microhardness, and intrinsic stress. The results of these studies and those of the other techniques for depositing diamondlike carbon films are presented.

  3. Performance of Advanced Light Source particle beam diagnostics

    SciTech Connect

    Hinkson, J.

    1993-05-01

    The Advanced Light Source (ALS), a third-generation synchrotron radiation facility, is complete. The particle beam diagnostics have been installed and tested. The beam injection systems have been running for two years. We have performance data on beam position monitors, beam intensity monitors, scintillators, beam collimators, a 50 {Omega} Faraday cup, and broad-band striplines and kickers used in the linac, transport lines, and the booster synchrotron. The single-turn monitoring capability of the booster beam position monitoring system has been particularly useful for studying beam dynamics. Beam diagnostics for the storage ring are being commissioned. In this paper we describe each instrument, show its performance, and outline how the instruments are controlled and their output data displayed.

  4. Coherent beam combining performance in harsh environment

    NASA Astrophysics Data System (ADS)

    Lombard, L.; Canat, G.; Durecu, A.; Bourdon, P.

    2014-03-01

    Coherent beam combining (CBC) is a promising solution for high power directed energy weapons. We investigate several particular issues for this application: First, we study the evolution of phase noise spectrum for increasing pump power in 100 W MOPFA. The main variations in the spectrum are located in the low frequency region corresponding to thermal transfer between the fiber core heated by the pump absorption and the fiber environment. The phase noise root mean square evolves linearly with the pump power. Noise spectrum is not shifted to higher frequencies. Second, we investigate the influence of fiber packaging and amplifier packaging on the phase noise and estimate the LOCSET controller bandwidth (BW) requirement in each case. Results show large variation of BW depending on the packaging, and not on the power. Then, we investigate the performances of CBC in harsh environment. For this purpose, we implement CBC of a 20-W fiber amplifier and a passive fiber using the LOCSET technique and simulate harsh environment by applying strong vibrations with a hammering drill on the optical table. The applied vibration spectrum ranges from 1 Hz to ~10 kHz with a standard deviation of 9 m/s2. CBC of the amplifier output and the passive fiber output is performed on a second table, isolated from vibrations. Measurements of the phase difference between both outputs and of the applied vibrations are simultaneously performed. Residual phase error of λ/40 (i.e. > 99 % CBC efficiency) is achieved under strong vibrations at 20 W. The -3 dB bandwidth of the LOCSET controller has been measured to be ~4.5 kHz. Results are in agreement with simulations.

  5. Electron Cloud in Steel Beam Pipe vs Titanium Nitride Coated and Amorphous Carbon Coated Beam Pipes in Fermilab's Main Injector

    SciTech Connect

    Backfish, Michael

    2013-04-01

    This paper documents the use of four retarding field analyzers (RFAs) to measure electron cloud signals created in Fermilab’s Main Injector during 120 GeV operations. The first data set was taken from September 11, 2009 to July 4, 2010. This data set is used to compare two different types of beam pipe that were installed in the accelerator. Two RFAs were installed in a normal steel beam pipe like the rest of the Main Injector while another two were installed in a one meter section of beam pipe that was coated on the inside with titanium nitride (TiN). A second data run started on August 23, 2010 and ended on January 10, 2011 when Main Injector beam intensities were reduced thus eliminating the electron cloud. This second run uses the same RFA setup but the TiN coated beam pipe was replaced by a one meter section coated with amorphous carbon (aC). This section of beam pipe was provided by CERN in an effort to better understand how an aC coating will perform over time in an accelerator. The research consists of three basic parts: (a) continuously monitoring the conditioning of the three different types of beam pipe over both time and absorbed electrons (b) measurement of the characteristics of the surrounding magnetic fields in the Main Injector in order to better relate actual data observed in the Main Injector with that of simulations (c) measurement of the energy spectrum of the electron cloud signals using retarding field analyzers in all three types of beam pipe.

  6. Reinforcing multiwall carbon nanotubes by electron beam irradiation

    SciTech Connect

    Duchamp, Martial; Meunier, Richard; Smajda, Rita; Mionic, Marijana; Forro, Laszlo; Magrez, Arnaud; Seo, Jin Won; Song, Bo; Tomanek, David

    2010-10-15

    We study the effect of electron beam irradiation on the bending modulus of multiwall carbon nanotubes grown by chemical vapor deposition. Atomic force microscopy observations of the nanotube deflection in the suspended-beam geometry suggest an internal, reversible stick-slip motion prior to irradiation, indicating presence of extended defects. Upon electron beam irradiation, nanotubes with an initial bending modulus exceeding 10 GPa initially get stiffer, before softening at high doses. Highly defective nanotubes with smaller initial bending moduli do not exhibit the initial reinforcement. These data are explained by ab initio molecular dynamics calculations suggesting a spontaneous cross-linking of neighboring nanotube walls at extended vacancy defects created by the electron beam, in agreement with electron microscopy observations. At low defect concentration, depending on the edge morphology, the covalent bonds between neighboring nanotube walls cause reinforcement by resisting relative motion of neighboring walls. At high concentration of defects that are present initially or induced by high electron beam dose, the structural integrity of the entire system suffers from increasing electron beam damage.

  7. Beam-induced graphitic carbon cage transformation from sumanene aggregates

    SciTech Connect

    Fujita, Jun-ichi Tachi, Masashi; Murakami, Katsuhisa; Sakurai, Hidehiro; Morita, Yuki; Higashibayashi, Shuhei; Takeguchi, Masaki

    2014-01-27

    We found that electron-beam irradiation of sumanene aggregates strongly enhanced their transformation into a graphitic carbon cage, having a diameter of about 20 nm. The threshold electron dose was about 32 mC/cm{sup 2} at 200 keV, but the transformation is still induced at 20 keV. The transformation sequence suggested that the cage was constructed accompanied by the dynamical movement of the transiently linked sumanene molecules in order to pile up inside the shell. Thus, bond excitation in the sumanene molecules rather than a knock-on of carbon atoms seems to be the main cause of the cage transformation.

  8. Tumor therapy with high-energy carbon ion beams

    NASA Astrophysics Data System (ADS)

    Schardt, D.; Heavy-Ion Therapy Collaboration

    2007-05-01

    Heavy-ion beams offer favourable conditions for the treatment of deep-seated local tumors. The well defined range and the small lateral beam spread make it possible to deliver the dose with millimeter precision by applying advanced beam scanning techniques. In addition, heavy ions have an enhanced biological effectiveness in the Bragg peak region which is caused by the dense ionization and the resulting reduced cellular repair rate. Furthermore, heavy ions offer the unique possibility of in-vivo range monitoring by applying Positron-Emission-Tomography (PET) techniques. Taking advantage of these clinically relevant properties, more than 300 patients have been treated with carbon ions at GSI Darmstadt since December 1997 with very promising results. A dedicated heavy-ion treatment center at the Radiological Clinic Heidelberg with a design capacity of 1000 patients per year is under construction and expected to start operation end of 2007.

  9. Dosimetric characterization of a microDiamond detector in clinical scanned carbon ion beams

    SciTech Connect

    Marinelli, Marco; Prestopino, G. Verona, C.; Verona-Rinati, G.; Ciocca, M.; Mirandola, A.; Mairani, A.; Raffaele, L.; Magro, G.

    2015-04-15

    direction. A strong distortion in Bragg peak measurement was observed, confirming manufacturer recommendation on avoiding such configuration. Very good results were obtained for SOBP measurements, with a difference below 1% between measured and TPS-calculated doses. The stability of detector sensitivity in the observation period was within the experimental uncertainty. Conclusions: Dosimetric characterization of a PTW microDiamond detector in high-energy scanned carbon ion beams was performed. The results of the present study showed that this detector is suitable for dosimetry of clinical carbon ion beams, with a negligible LET and dose-rate dependence.

  10. High performance carbon nanocomposites for ultracapacitors

    DOEpatents

    Lu, Wen

    2012-10-02

    The present invention relates to composite electrodes for electrochemical devices, particularly to carbon nanotube composite electrodes for high performance electrochemical devices, such as ultracapacitors.

  11. Antares beam-alignment-system performance

    SciTech Connect

    Appert, Q.D.; Bender, S.C.

    1983-01-01

    The beam alignment system for the 24-beam-sector Antares CO/sub 2/ fusion laser automatically aligns more than 200 optical elements. A visible-wavelength alignment technique is employed which uses a telescope/TV system to view point-light sources appropriately located down the beamline. The centroids of the light spots are determined by a video tracker, which generates error signals used by the computer control system to move appropriate mirrors in a closed-loop system. Final touch-up alignment is accomplished by projecting a CO/sub 2/ alignment laser beam through the system and sensing its position at the target location. The techniques and control algorithms employed have resulted in alignment accuracies exceeding design requirements. By employing video processing to determine the centroids of diffraction images and by averaging over multiple TV frames, we achieve alignment accuracies better than 0.1 times system diffraction limits in the presence of air turbulence.

  12. Performance and Controllability of Pulsed Ion Beam Ablation Propulsion

    SciTech Connect

    Yazawa, Masaru; Buttapeng, Chainarong; Harada, Nobuhiro; Suematsu, Hisayuki; Jiang Weihua; Yatsui, Kiyoshi

    2006-05-02

    We propose novel propulsion driven by ablation plasma pressures produced by the irradiation of pulsed ion beams onto a propellant. The ion beam ablation propulsion demonstrates by a thin foil (50 {mu}mt), and the flyer velocity of 7.7 km/s at the ion beam energy density of 2 kJ/cm2 adopted by using the Time-of-flight method is observed numerically and experimentally. We estimate the performance of the ion beam ablation propulsion as specific impulse of 3600 s and impulse bit density of 1700 Ns/m2 obtained from the demonstration results. In the numerical analysis, a one-dimensional hydrodynamic model with ion beam energy depositions is used. The control of the ion beam kinetic energy is only improvement of the performance but also propellant consumption. The spacecraft driven by the ion beam ablation provides high performance efficiency with short-pulsed ion beam irradiation. The numerical results of the advanced model explained latent heat and real gas equation of state agreed well with experimental ones over a wide range of the incident ion beam energy density.

  13. Dose response of alanine detectors irradiated with carbon ion beams

    SciTech Connect

    Herrmann, Rochus; Jaekel, Oliver; Palmans, Hugo; Sharpe, Peter; Bassler, Niels

    2011-04-15

    Purpose: The dose response of the alanine detector shows a dependence on particle energy and type when irradiated with ion beams. The purpose of this study is to investigate the response behavior of the alanine detector in clinical carbon ion beams and compare the results to model predictions. Methods: Alanine detectors have been irradiated with carbon ions with an energy range of 89-400 MeV/u. The relative effectiveness of alanine has been measured in this regime. Pristine and spread out Bragg peak depth-dose curves have been measured with alanine dosimeters. The track structure based alanine response model developed by Hansen and Olsen has been implemented in the Monte Carlo code FLUKA and calculations were compared to experimental results. Results: Calculations of the relative effectiveness deviate less than 5% from the measured values for monoenergetic beams. Measured depth-dose curves deviate from predictions in the peak region, most pronounced at the distal edge of the peak. Conclusions: The used model and its implementation show a good overall agreement for quasimonoenergetic measurements. Deviations in depth-dose measurements are mainly attributed to uncertainties of the detector geometry implemented in the Monte Carlo simulations.

  14. Piezoelectric performance of continuous beam and narrow supported beam arrays for artificial basilar membranes

    NASA Astrophysics Data System (ADS)

    Song, Won Joon; Jang, Jongmoon; Kim, Sangwon; Choi, Hongsoo

    2014-09-01

    We report an experimental assessment of the electrical performance of two piezoelectric beam arrays for artificial basilar membranes (ABMs): a continuous beam array (CBA) and a narrow-supports beam array (NSBA). Both arrays consist of piezoelectric beams of sequentially varying lengths that mimic the frequency selectivity of mammalian cochleae. The narrow supports of the NSBA resulted in lateral deformation of the beams, whereas the CBA beams were flat. The displacement and piezoelectric output of each beam were measured at the resonance frequency of each beam using a scanning laser-Doppler vibrometer (SLDV). Both ABM prototypes showed mechanical frequency selectivity that depended on the beam length. The CBA generated a piezoelectric output in the range 6.6-23.2 μV and exhibited electrical frequency separability, whereas the NSBA failed to generate sufficient electrical potential due to the lateral deformation of the piezoelectric beams. The CBA was found to be more effective as an ABM, with potential for use in cochlear implants.

  15. Charge equilibrium of a laser-generated carbon-ion beam in warm dense matter.

    PubMed

    Gauthier, M; Chen, S N; Levy, A; Audebert, P; Blancard, C; Ceccotti, T; Cerchez, M; Doria, D; Floquet, V; Lamour, E; Peth, C; Romagnani, L; Rozet, J-P; Scheinder, M; Shepherd, R; Toncian, T; Vernhet, D; Willi, O; Borghesi, M; Faussurier, G; Fuchs, J

    2013-03-29

    Using ion carbon beams generated by high intensity short pulse lasers we perform measurements of single shot mean charge equilibration in cold or isochorically heated solid density aluminum matter. We demonstrate that plasma effects in such matter heated up to 1 eV do not significantly impact the equilibration of carbon ions with energies 0.045-0.5  MeV/nucleon. Furthermore, these measurements allow for a first evaluation of semiempirical formulas or ab initio models that are being used to predict the mean of the equilibrium charge state distribution for light ions passing through warm dense matter. PMID:23581330

  16. High-Performance Beam Simulator for the LANSCE Linac

    SciTech Connect

    Pang, Xiaoying; Rybarcyk, Lawrence J.; Baily, Scott A.

    2012-05-14

    A high performance multiparticle tracking simulator is currently under development at Los Alamos. The heart of the simulator is based upon the beam dynamics simulation algorithms of the PARMILA code, but implemented in C++ on Graphics Processing Unit (GPU) hardware using NVIDIA's CUDA platform. Linac operating set points are provided to the simulator via the EPICS control system so that changes of the real time linac parameters are tracked and the simulation results updated automatically. This simulator will provide valuable insight into the beam dynamics along a linac in pseudo real-time, especially where direct measurements of the beam properties do not exist. Details regarding the approach, benefits and performance are presented.

  17. Carbon dust particles in a beam-plasma discharge

    NASA Astrophysics Data System (ADS)

    Koval, O. A.; Vizgalov, V.; Shalpegin, A. V.

    2016-09-01

    This paper focuses on dynamics of micro-sized carbon dust grains in beam-plasma discharge (BPD) plasmas. It was demonstrated that injected dust particles can be captured and transported along the discharge. Longitudinal average velocity of the particles in the central area of the plasma column was 17 m/sec, and 2 m/sec in the periphery. Dust injection caused a decrease of emission intensity of metastable nitrogen molecular ion. This effect is suggested for a spectroscopy method for particles’ potential measurements. Five-micron radius carbon dust grains obtained potential above 500 V in the experiments on PR-2 installation, proving the feasibility of BPDs for the charging of fine dust particles up to high potential values, unattainable in similar plasma conditions.

  18. Dual ion beam deposition of carbon films with diamondlike properties

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Swec, D. M.; Angus, J. C.

    1984-01-01

    A single and dual ion beam system was used to generate amorphous carbon films with diamond like properties. A methane/argon mixture at a molar ratio of 0.28 was ionized in the low pressure discharge chamber of a 30-cm-diameter ion source. A second ion source, 8 cm in diameter was used to direct a beam of 600 eV Argon ions on the substrates (fused silica or silicon) while the deposition from the 30-cm ion source was taking place. Nuclear reaction and combustion analysis indicate H/C ratios for the films to be 1.00. This high value of H/C, it is felt, allowed the films to have good transmittance. The films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Although the measured density of the films was approximately 1.8 gm/cu cm, a value lower than diamond, the films exhibited other properties that were relatively close to diamond. These films were compared with diamondlike films generated by sputtering a graphite target.

  19. Space Shuttle Orbiter carbon-carbon oxidation performance

    NASA Technical Reports Server (NTRS)

    Curry, D. M.; Yuen, E. H.; Chao, D. C.; Webster, C. N.

    1991-01-01

    Reusable, oxidation protected reinforced carbon carbon (RCC) has been successfully flown on forty Shuttle Orbiter flights. Thermal testing of the silicon carbide coated, reinforced carbon-carbon to determine its oxidation characteristics has been performed in both radiant and convective (plasma arc jet) heating test facilities. Subsurface oxidation of the RCC substrate as a result of oxygen penetrating micro cracks (fizzures) in the coating was characterized as a function of temperature and pressure for both convective and radiant environments. High temperature testing was performed to establish coating recession for over-temperature flight conditions experienced on abort trajectories. Suggested methods for using these test data to establish multi-mission reuse (i.e., mission life) and single mission limits are presented.

  20. The performance of the MICE muon beam line

    NASA Astrophysics Data System (ADS)

    Rayner, Mark Alastair

    2011-10-01

    The Muon Ionization Cooling Experiment is one lattice cell of a cooling channel suitable for conditioning the muon beam at the front end of a Neutrino Factory or Muon Collider. The beam line designed to transport muons into MICE has been installed, and data was collected in 2010. In this paper the method of reconstructing longitudinal momentum and transverse trace space using two timing detectors is discussed, and a preliminary simulation of the performance of a measured beam in the cooling channel is presented.

  1. Non-invasive monitoring of therapeutic carbon ion beams in a homogeneous phantom by tracking of secondary ions.

    PubMed

    Gwosch, K; Hartmann, B; Jakubek, J; Granja, C; Soukup, P; Jäkel, O; Martišíková, M

    2013-06-01

    Radiotherapy with narrow scanned carbon ion beams enables a highly accurate treatment of tumours while sparing the surrounding healthy tissue. Changes in the patient's geometry can alter the actual ion range in tissue and result in unfavourable changes in the dose distribution. Consequently, it is desired to verify the actual beam delivery within the patient. Real-time and non-invasive measurement methods are preferable. Currently, the only technically feasible method to monitor the delivered dose distribution within the patient is based on tissue activation measurements by means of positron emission tomography (PET). An alternative monitoring method based on tracking of prompt secondary ions leaving a patient irradiated with carbon ion beams has been previously suggested. It is expected to help in overcoming the limitations of the PET-based technique like physiological washout of the beam induced activity, low signal and to allow for real-time measurements. In this paper, measurements of secondary charged particle tracks around a head-sized homogeneous PMMA phantom irradiated with pencil-like carbon ion beams are presented. The investigated energies and beam widths are within the therapeutically used range. The aim of the study is to deduce properties of the primary beam from the distribution of the secondary charged particles. Experiments were performed at the Heidelberg Ion Beam Therapy Center, Germany. The directions of secondary charged particles emerging from the PMMA phantom were measured using an arrangement of two parallel pixelated silicon detectors (Timepix). The distribution of the registered particle tracks was analysed to deduce its dependence on clinically important beam parameters: beam range, width and position. Distinct dependencies of the secondary particle tracks on the properties of the primary carbon ion beam were observed. In the particular experimental set-up used, beam range differences of 1.3 mm were detectable. In addition, variations in

  2. Non-invasive monitoring of therapeutic carbon ion beams in a homogeneous phantom by tracking of secondary ions.

    PubMed

    Gwosch, K; Hartmann, B; Jakubek, J; Granja, C; Soukup, P; Jäkel, O; Martišíková, M

    2013-06-01

    Radiotherapy with narrow scanned carbon ion beams enables a highly accurate treatment of tumours while sparing the surrounding healthy tissue. Changes in the patient's geometry can alter the actual ion range in tissue and result in unfavourable changes in the dose distribution. Consequently, it is desired to verify the actual beam delivery within the patient. Real-time and non-invasive measurement methods are preferable. Currently, the only technically feasible method to monitor the delivered dose distribution within the patient is based on tissue activation measurements by means of positron emission tomography (PET). An alternative monitoring method based on tracking of prompt secondary ions leaving a patient irradiated with carbon ion beams has been previously suggested. It is expected to help in overcoming the limitations of the PET-based technique like physiological washout of the beam induced activity, low signal and to allow for real-time measurements. In this paper, measurements of secondary charged particle tracks around a head-sized homogeneous PMMA phantom irradiated with pencil-like carbon ion beams are presented. The investigated energies and beam widths are within the therapeutically used range. The aim of the study is to deduce properties of the primary beam from the distribution of the secondary charged particles. Experiments were performed at the Heidelberg Ion Beam Therapy Center, Germany. The directions of secondary charged particles emerging from the PMMA phantom were measured using an arrangement of two parallel pixelated silicon detectors (Timepix). The distribution of the registered particle tracks was analysed to deduce its dependence on clinically important beam parameters: beam range, width and position. Distinct dependencies of the secondary particle tracks on the properties of the primary carbon ion beam were observed. In the particular experimental set-up used, beam range differences of 1.3 mm were detectable. In addition, variations in

  3. Dosimetric characterization of the iBEAM evo carbon fiber couch for radiotherapy

    SciTech Connect

    Smith, David W.; Christophides, Damianos; Dean, Christopher; Naisbit, Mitchell; Mason, Joshua; Morgan, Andrew

    2010-07-15

    Purpose: This study characterizes the dosimetric properties of the iBEAM evo carbon fiber couch manufactured by Medical Intelligence and examines the accuracy of the CMS XiO and Nucletron Oncentra Masterplan (OMP) treatment planning systems for calculating beam attenuation due to the presence of the couch. Methods: To assess the homogeneity of the couch, it was CT scanned at isocentric height and a number of signal intensity profiles were generated and analyzed. To simplify experimental procedures, surface dose and central axis depth dose measurements were performed in a solid water slab phantom using Gafchromic film for 6 and 10 MV photon beams at gantry angles of 0 deg. (normal incidence), 30 deg., and 60 deg. with an inverted iBEAM couch placed on top of the phantom. Attenuation measurements were performed in a cylindrical solid water phantom with an ionization chamber positioned at the isocenter. Measurements were taken for gantry angles from 0 deg. to 90 deg. in 10 deg. increments for both 6 and 10 MV photon beams. This setup was replicated in the XiO and OMP treatment planning systems. Dose was calculated using the pencil beam, collapsed cone, convolution, and superposition algorithms. Results: The CT scan of the couch showed that it was uniformly constructed. Surface dose increased by (510{+-}30)% for a 6 MV beam and (600{+-}20)% for a 10 MV beam passing through the couch at normal incidence. Obliquely incident beams resulted in a higher surface dose compared to normally incident beams for both open fields and fields with the couch present. Depth dose curves showed that the presence of the couch resulted in an increase in dose in the build up region. For 6 and 10 MV beams incident at 60 deg., nearly all skin sparing was lost. Attenuation measurements derived using the ionization chamber varied from 2.7% (0 deg.) to a maximum of 4.6% (50 deg.) for a 6 MV beam and from 1.9% (0 deg.) to a maximum of 4.0% (50 deg.) for a 10 MV beam. The pencil beam and

  4. Resolution of a High Performance Cavity Beam Position Monitor System

    SciTech Connect

    Walston, S; Chung, C; Fitsos, P; Gronberg, J; Ross, M; Khainovski, O; Kolomensky, Y; Loscutoff, P; Slater, M; Thomson, M; Ward, D; Boogert, S; Vogel, V; Meller, R; Lyapin, A; Malton, S; Miller, D; Frisch, J; Hinton, S; May, J; McCormick, D; Smith, S; Smith, T; White, G; Orimoto, T; Hayano, H; Honda, Y; Terunuma, N; Urakawa, J

    2005-09-12

    International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved - ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Accelerator Test Facility (ATF) for testing with its ultra-low emittance beam. A metrology system for the three BPMs was recently installed. This system employed optical encoders to measure each BPM's position and orientation relative to a zero-coefficient of thermal expansion carbon fiber frame and has demonstrated that the three BPMs behave as a rigid-body to less than 5 nm. To date, we have demonstrated a BPM resolution of less than 20 nm over a dynamic range of +/- 20 microns.

  5. Molecular beam facility for studying mass spectrometer performance

    NASA Technical Reports Server (NTRS)

    Ballenthin, J. O.; Nier, A. O.

    1981-01-01

    An apparatus which produces neutral gas beams in the velocity range from thermal to 6 km/s makes possible studies simulating the motion of instruments through tenuous atmospheres. Use of the apparatus in studying the response of an open-source mass spectrometer is examined. Experiments performed include responses when the instrument is in a normal mode of operation, when the ion source potentials are adjusted to reject striking gas particles, when the beam is restricted so that portions of the ion source are struck, and when the beam strikes at angles other than normal incidence. Results indicate specular radiation of particles out of the source and stagnation ratios close to unity for normal operation. Retarding potential studies dropped the sensitivity by a factor of about 10, and as angles of attack are varied, the effect was found to depend upon beam velocity and the way the ions are initially accelerated.

  6. Performance predictions of a focused ion beam from a laser cooled and compressed atomic beam

    SciTech Connect

    Haaf, G. ten; Wouters, S. H. W.; Vredenbregt, E. J. D.; Mutsaers, P. H. A.; Geer, S. B. van der

    2014-12-28

    Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here, we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of, amongst others, the flux density of the atomic beam, the temperature of this beam, and the total current. At low currents (I < 10 pA), the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents, this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model was verified with particle tracing simulations of a complete focused ion beam setup. A genetic algorithm was used to find the optimum acceleration electric field as a function of the current. At low currents, the result agrees well with the analytical model, while at higher currents, the spot sizes found are even lower due to effects that are not taken into account in the analytical model.

  7. A simulation study of a C-shaped in-beam PET system for dose verification in carbon ion therapy

    NASA Astrophysics Data System (ADS)

    Jung An, Su; Beak, Cheol-Ha; Lee, Kisung; Hyun Chung, Yong

    2013-01-01

    The application of hadrons such as carbon ions is being developed for the treatment of cancer. The effectiveness of such a technique is due to the eligibility of charged particles in delivering most of their energy near the end of the range, called the Bragg peak. However, accurate verification of dose delivery is required since misalignment of the hadron beam can cause serious damage to normal tissue. PET scanners can be utilized to track the carbon beam to the tumor by imaging the trail of the hadron-induced positron emitters in the irradiated volume. In this study, we designed and evaluated (through Monte Carlo simulations) an in-beam PET scanner for monitoring patient dose in carbon beam therapy. A C-shaped PET and a partial-ring PET were designed to avoid interference between the PET detectors and the therapeutic carbon beam delivery. Their performance was compared with that of a full-ring PET scanner. The C-shaped, partial-ring, and full-ring scanners consisted of 14, 12, and 16 detector modules, respectively, with a 30.2 cm inner diameter for brain imaging. Each detector module was composed of a 13×13 array of 4.0 mm×4.0 mm×20.0 mm LYSO crystals and four round 25.4 mm diameter PMTs. To estimate the production yield of positron emitters such as 10C, 11C, and 15O, a cylindrical PMMA phantom (diameter, 20 cm; thickness, 20 cm) was irradiated with 170, 290, and 350 AMeV 12C beams using the GATE code. Phantom images of the three types of scanner were evaluated by comparing the longitudinal profile of the positron emitters, measured along the carbon beam as it passed a simulated positron emitter distribution. The results demonstrated that the development of a C-shaped PET scanner to characterize carbon dose distribution for therapy planning is feasible.

  8. Dissociation phenomena in electron-beam sustained carbon dioxide lasers

    NASA Technical Reports Server (NTRS)

    Harris, Michael R.; Willetts, David V.

    1990-01-01

    A number of applications are emerging requiring efficient, long pulse, long-life sealed CO2 lasers. Examples include the proposed NASA and ESA wind lidars. Electron-beam sustained discharge devices are strong contenders. Unlike self-sustained discharges, e-beam sustenance readily provides efficient performance from large volume discharges and offers pulse lengths well in excess of the microsecond or so generally associated with self-sustained devices. In the case of the e-beam sustained laser, since the plasma is externally maintained and operated at electric field strengths less than that associated with the glow to arc transition, the discharges can be run even in the presence of strongly attacking species such as O2. Build up of large levels of attacking contaminants is nevertheless undesirable as their presence reduces the current drawn by the plasma and thus the pumping rate to the upper laser level. The impedance rise leads to a mismatch of the pulse forming network with a consequent loss of control over energy deposition, operating E/N, and gain. Clearly CO2 dissociation rates, the influence of dissociation products on the discharge and gain, and tolerance of the discharge to these products need to be determined. This information can then be used to assess co-oxidation catalyst requirements for sealed operation.

  9. Electron beam-induced nanopatterning of multilayer graphene and amorphous carbon films with metal layers

    SciTech Connect

    Rodriguez-Manzo, Julio A.; Banhart, Florian

    2011-05-02

    Thin Co and Ni lamellae grow under electron irradiation of metal crystals supported on multilayer graphene or amorphous carbon films. The lateral growth of a lamella from a source crystal is achieved by directing an electron beam to the periphery of the metal crystal and moving the beam over the surrounding carbon. Patterns of linear, branched, or ringlike metal lamellae can be created. The patterning is carried out in situ in a transmission electron microscope, allowing simultaneous structuring and imaging. The process is driven by the metal-carbon interaction at a beam-activated carbon surface.

  10. Performance of the PDX neutral beam wall armor

    SciTech Connect

    Kugel, H.W.; Eubank, H.P.; Kozub, T.A.; Williams, M.D.

    1985-02-01

    The PDX wall armor was designed to function as an inner wall thermal armor, a neutral beam diagnostic, and a large area inner toroidal plasma limiter. In this paper we discuss its thermal performance as wall armor during two years of PDX neutral beam heating experiments. During this period it provided sufficient inner wall protection to permit perpendicular heating injections into normal and disruptive plasmas as well as injections in the absence of plasma involving special experiments, calibrations, and tests important for the optimization and development of the PDX neutral beam injection system. Many of the design constraints and performance issues encountered in this work are relevant to the design of larger fusion devices.

  11. Assessment of carbon layer growth induced by resists outgassing in multi e-beams lithography

    NASA Astrophysics Data System (ADS)

    Marusic, JC; Pourteau, ML; Cêtre, S.; Pain, L.; Mebiene-Engohang, AP; David, S.; Labau, S.; Boussey, J.

    2014-10-01

    The development of multiple e-beam lithography equipment is seen as an alternative for next generation lithography. However, similarly to EUV lithography, this technology faces important challenges in controlling the contamination of the optics due to deposition of carbon layer induced by the outgassed chemical species from resist under electron bombardment. An experimental setup was designed and built at LETI to study the outgassed species and observe the carbon layer. In this setup, resist coated wafers 100 mm size are exposed under a 5 kV e-beam gun. During exposure, byproducts from outgassed species are monitored with a Residual Gas Analyzer (RGA). The identification of outgassed chemical species is done with an ex-situ TD-GC-MS analysis (ThermoDesorption-Gaz Chromatography-Mass Spectrometry). In a second part of this investigation, we observed the contamination carbon layer growth induced by the outgassing. Thereby, we fabricated a device which consists of a silicon membrane with micro-machined apertures. During e-beam exposure, this device simulates the multiple parallel beams of the optic system of a maskless lithography tool. The deposited contamination layer on device is then observed and thickness measured under SEM. In this paper, we present the results of outgassing and contamination on 3 chemically amplified resists showing that contamination is not directly dependent of the overall outgassing rate but on first order of the outgassing from Photo Acid Generator (PAG). It also reports on the performance in reducing outgassing and contamination of applying a top-coat layer on top of the resist and shows that reduction is more important for contamination than for outgassing.

  12. High performance pitch-based carbon fiber

    SciTech Connect

    Tadokoro, Hiroyuki; Tsuji, Nobuyuki; Shibata, Hirotaka; Furuyama, Masatoshi

    1996-12-31

    The high performance pitch-based carbon fiber with smaller diameter, six micro in developed by Nippon Graphite Fiber Corporation. This fiber possesses high tensile modulus, high tensile strength, excellent yarn handle ability, low thermal expansion coefficient, and high thermal conductivity which make it an ideal material for space applications such as artificial satellites. Performance of this fiber as a reinforcement of composites was sufficient. With these characteristics, this pitch-based carbon fiber is expected to find wide variety of possible applications in space structures, industrial field, sporting goods and civil infrastructures.

  13. Comparison of the TESLA, NLC and CLIC beam collimation performance

    SciTech Connect

    Alexandr I Drozhdin et al.

    2003-03-27

    This note describes studies performed in the framework of the Collimation Task Force organized to support the work of the International Linear Collider Technical Review Committee. The post-linac beam-collimation systems in the TESLA, JLC/NLC and CLIC linear-collider designs are compared using the same computer code under the same assumptions. Their performance is quantified in terms of beam-halo and synchrotron-radiation collimation efficiency. The performance of the current designs varies across projects, and does not always meet the original design goals. But these comparisons suggest that achieving the required performance in a future linear collider is feasible. The post-TRC plans of the Collimation Task Force are briefly outlined in closing.

  14. Test beam performance of CDF plug upgrade EM calorimeter

    SciTech Connect

    Fukui, Y.; CDF Upgrade Group

    1998-01-01

    CDF Plug Upgrade(tile-fiber) EM Calorimeter performed resolution of 15%/{radical}E{circle_plus}0.7% with non-linearity less than 1% in a energy range of 5-180 GeV at Fermilab Test Beam. Transverse uniformity of inside-tower-response of the EM Calorimeter was 2.2% with 56 GeV positron, which was reduced to 1.0% with response map correction. We observed 300 photo electron/GeV in the EM Calorimeter. Ratios of EM Calorimeter response to positron beam to that to {sup 137}Cs Source was stable within 1% in the period of 8 months.

  15. Quantitative carbon ion beam radiography and tomography with a flat-panel detector.

    PubMed

    Telsemeyer, Julia; Jäkel, Oliver; Martišíková, Mária

    2012-12-01

    High dose gradients are inherent to ion beam therapy. This results in high sensitivity to discrepancies between planned and delivered dose distributions. Therefore an accurate knowledge of the ion stopping power of the traversed tissue is critical. One proposed method to ensure high quality dose deposition is to measure the stopping power by ion radiography. Although the idea of imaging with highly energetic ions is more than forty years old, there is a lack of simple detectors suitable for this purpose. In this study the performance of an amorphous silicon flat-panel detector, originally designed for photon imaging, was investigated for quantitative carbon ion radiography and tomography. The flat-panel detector was exploited to measure the water equivalent thickness (WET) and water equivalent path length (WEPL) of a phantom at the Heidelberg Ion-Beam Therapy Center (HIT). To do so, the ambiguous correlation of detector signal to particle energy was overcome by active or passive variation of carbon ion beam energy and measurement of the signal-to-beam energy correlation. The active method enables one to determine the WET of the imaged object with an uncertainty of 0.5 mm WET. For tomographic WEPL measurements the passive method was exploited resulting in an accuracy of 0.01 WEPL. The developed imaging technique presents a method to measure the two-dimensional maps of WET and WEPL of phantoms with a simple and commercially available detector. High spatial resolution of 0.8 × 0.8 mm(2) is given by the detector design. In the future this powerful tool will be used to evaluate the performance of the treatment planning algorithm by studying WET uncertainties.

  16. Influence of electron beam halos on the FEL performance

    NASA Astrophysics Data System (ADS)

    Faatz, B.; Reiche, S.

    1999-06-01

    For single-pass free-electron lasers (FEL), such as amplifiers and SASE devices, saturation of the radiation power has to be reached within the length of the undulator. Therefore, detailed knowledge of electron beam parameters is crucial. So far, simulations have been performed with a given rms emittance and energy spread. At short radiation wavelengths, bunch compressors are used to compress the electron beam to achieve the desired high peak currents. In addition, external focusing along the entire undulator is used to maintain a constant small radius. The rotation of phase space due to compression might lead to a significant part of the bunch in tails that could increase the gain length. Furthermore, it is in general not possible to match both the beam core and the tail to the focusing structure. In this contribution, the influence of these tails, both transverse and in energy, on the FEL performance will be investigated. Simulations will be performed for beam parameters that have been assumed for the TESLA Test Facility FEL at DESY.

  17. Dose-Response Effect of Charged Carbon Beam on Normal Rat Retina Assessed by Electroretinography

    SciTech Connect

    Mizota, Atsushi; Tanaka, Minoru; Kubota, Mariko; Negishi, Hisanari; Watanabe, Emiko; Tsuji, Hiroshi; Miyahara, Nobuyuki; Furusawa, Yoshiya

    2010-12-01

    Purpose: To compare the effects of carbon beam irradiation with those of proton beam irradiation on the physiology of the retina of rats. Methods and Materials: Eight-week-old Wister rats were used. The right eyes were irradiated with carbon beam (1, 2, 4, 8, and 16 Gy) or proton beam (4, 8, 16, and 24 Gy) with the rats under general anesthesia. Electroretinograms were recorded 1, 3, 6, and 12 months after the irradiation, and the amplitudes of the a and b waves were compared with those of control rats. Results: The amplitude of b waves was reduced more than that of a waves at lower irradiation doses with both types of irradiation. With carbon ion irradiation, the amplitudes of the b wave were significantly reduced after radiation doses of 8 and 16 Gy at 6 months and by radiation doses of 4, 8, and 16 Gy at 12 months. With proton beam irradiation, the b-wave amplitudes were significantly reduced after 16 and 24 Gy at 6 months and with doses of 8 Gy or greater at 12 months. For the maximum b-wave amplitude, a significant difference was observed in rats irradiated with carbon beams of 4 Gy or more and with proton beams of 8 Gy or more at 12 months after irradiation. Conclusions: These results indicate that carbon beam irradiation is about two times more damaging than proton beam irradiation on the rat retina at the same dose.

  18. Performance characteristics of a circular multicusp neutral beam source

    NASA Astrophysics Data System (ADS)

    Obiki, T.; Sasaki, A.; Sano, F.; Uo, K.

    1981-10-01

    The performance of the Heliotron-E neutral beam system, composed of intense cylindrical magnetic multipole bucket sources and beam line facilities, has been investigated. The investigation of the influence of the filament shape on the arc discharge stability shows that a wide-hairpin shaped filament results in more stable arc discharge without increasing the arc voltage than does a narrow-hairpin filament. An electrolytic polishing process has been tested for surface treatment of the Molybdenum grid and found to be very effective in reducing the number of conditioning shots. Beam extraction experiments show that a single bucket source can deliver the total beam current of 35 A at the accelerating voltage of 30 kV with the corresponding power transmission efficiency of more than 85% at the focal point of the grid curvature, the minimum beam divergence is less than 1.15° and the proton yield of the source is above 85%. Measurements of the equivalent gas line density in the neutralizer cell suggest the existence of the gas flow process different from a standard vacuum model.

  19. Integration and evaluation of automated Monte Carlo simulations in the clinical practice of scanned proton and carbon ion beam therapy

    NASA Astrophysics Data System (ADS)

    Bauer, J.; Sommerer, F.; Mairani, A.; Unholtz, D.; Farook, R.; Handrack, J.; Frey, K.; Marcelos, T.; Tessonnier, T.; Ecker, S.; Ackermann, B.; Ellerbrock, M.; Debus, J.; Parodi, K.

    2014-08-01

    Monte Carlo (MC) simulations of beam interaction and transport in matter are increasingly considered as essential tools to support several aspects of radiation therapy. Despite the vast application of MC to photon therapy and scattered proton therapy, clinical experience in scanned ion beam therapy is still scarce. This is especially the case for ions heavier than protons, which pose additional issues like nuclear fragmentation and varying biological effectiveness. In this work, we present the evaluation of a dedicated framework which has been developed at the Heidelberg Ion Beam Therapy Center to provide automated FLUKA MC simulations of clinical patient treatments with scanned proton and carbon ion beams. Investigations on the number of transported primaries and the dimension of the geometry and scoring grids have been performed for a representative class of patient cases in order to provide recommendations on the simulation settings, showing that recommendations derived from the experience in proton therapy cannot be directly translated to the case of carbon ion beams. The MC results with the optimized settings have been compared to the calculations of the analytical treatment planning system (TPS), showing that regardless of the consistency of the two systems (in terms of beam model in water and range calculation in different materials) relevant differences can be found in dosimetric quantities and range, especially in the case of heterogeneous and deep seated treatment sites depending on the ion beam species and energies, homogeneity of the traversed tissue and size of the treated volume. The analysis of typical TPS speed-up approximations highlighted effects which deserve accurate treatment, in contrast to adequate beam model simplifications for scanned ion beam therapy. In terms of biological dose calculations, the investigation of the mixed field components in realistic anatomical situations confirmed the findings of previous groups so far reported only in

  20. Parellel beam dynamics calculations on high performance computers

    SciTech Connect

    Ryne, R.; Habib, S.

    1996-12-01

    Faced with a backlog of nuclear waste and weapons plutonium, as well as an ever-increasing public concern about safety and environmental issues associated with conventional nuclear reactors, many countries are studying new, accelerator-driven technologies that hold the promise of providing safe and effective solutions to these problems. Proposed projects include accelerator transmutation of waste (ATW), accelerator-based conversion of plutonium (ABC), accelerator-driven energy production (ADEP), and accelerator production of tritium (APT). Also, next-generation spallation neutron sources based on similar technology will play a major role in materials science and biological science research. The design of accelerators for these projects will require a major advance in numerical modeling capability. For example, beam dynamics simulations with approximately 100 million particles will be needed to ensure that extremely stringent beam loss requirements (less than a nanoampere per meter) can be met. Compared with typical present-day modeling using 10,000-100,000 particles, this represents an increase of 3-4 orders of magnitude. High performance computing (HPC) platforms make it possible to perform such large scale simulations, which require 10`s of GBytes of memory. They also make it possible to perform smaller simulations in a matter of hours that would require months to run on a single processor workstation. This paper will describe how HPC platforms can be used to perform the numerically intensive beam dynamics simulations required for development of these new accelerator-driven technologies.

  1. Parallel beam dynamics calculations on high performance computers

    NASA Astrophysics Data System (ADS)

    Ryne, Robert; Habib, Salman

    1997-02-01

    Faced with a backlog of nuclear waste and weapons plutonium, as well as an ever-increasing public concern about safety and environmental issues associated with conventional nuclear reactors, many countries are studying new, accelerator-driven technologies that hold the promise of providing safe and effective solutions to these problems. Proposed projects include accelerator transmutation of waste (ATW), accelerator-based conversion of plutonium (ABC), accelerator-driven energy production (ADEP), and accelerator production of tritium (APT). Also, next-generation spallation neutron sources based on similar technology will play a major role in materials science and biological science research. The design of accelerators for these projects will require a major advance in numerical modeling capability. For example, beam dynamics simulations with approximately 100 million particles will be needed to ensure that extremely stringent beam loss requirements (less than a nanoampere per meter) can be met. Compared with typical present-day modeling using 10,000-100,000 particles, this represents an increase of 3-4 orders of magnitude. High performance computing (HPC) platforms make it possible to perform such large scale simulations, which require 10's of GBytes of memory. They also make it possible to perform smaller simulations in a matter of hours that would require months to run on a single processor workstation. This paper will describe how HPC platforms can be used to perform the numerically intensive beam dynamics simulations required for development of these new accelerator-driven technologies.

  2. Physical and engineering aspect of carbon beam therapy

    SciTech Connect

    Kanai, Tatsuaki; Kanematsu, Nobuyuki; Minohara, Shinichi; Yusa, Ken; Urakabe, Eriko; Kanazawa, Mitsutaka; Kitagawa, Atsushi; Tomitani, Takehiro; Mizuno, Hideyuki; Iseki, Yasushi

    2003-08-26

    Conformal irradiation system of HIMAC has been up-graded for a clinical trial using a technique of a layer-stacking method. The system has been developed for localizing irradiation dose to target volume more effectively than the present irradiation dose. With dynamic control of the beam modifying devices, a pair of wobbler magnets, and multileaf collimator and range shifter, during the irradiation, more conformal radiotherapy can be achieved. The system, which has to be adequately safe for patient irradiations, was constructed and tested from a viewpoint of safety and the quality of the dose localization realized. A secondary beam line has been constructed for use of radioactive beam in heavy-ion radiotherapy. Spot scanning method has been adapted for the beam delivery system of the radioactive beam. Dose distributions of the spot beam were measured and analyzed taking into account of aberration of the beam optics. Distributions of the stopped positron-emitter beam can be observed by PET. Pencil beam of the positron-emitter, about 1 mm size, can also be used for measurements ranges of the test beam in patients using positron camera. The positron camera, consisting of a pair of Anger-type scintillation detectors, has been developed for this verification before treatment. Wash-out effect of the positron-emitter was examined using the positron camera installed. In this report, present status of the HIMAC irradiation system is described in detail.

  3. High performance Si immersion gratings patterned with electron beam lithography

    NASA Astrophysics Data System (ADS)

    Gully-Santiago, Michael A.; Jaffe, Daniel T.; Brooks, Cynthia B.; Wilson, Daniel W.; Muller, Richard E.

    2014-07-01

    Infrared spectrographs employing silicon immersion gratings can be significantly more compact than spectro- graphs using front-surface gratings. The Si gratings can also offer continuous wavelength coverage at high spectral resolution. The grooves in Si gratings are made with semiconductor lithography techniques, to date almost entirely using contact mask photolithography. Planned near-infrared astronomical spectrographs require either finer groove pitches or higher positional accuracy than standard UV contact mask photolithography can reach. A collaboration between the University of Texas at Austin Silicon Diffractive Optics Group and the Jet Propulsion Laboratory Microdevices Laboratory has experimented with direct writing silicon immersion grating grooves with electron beam lithography. The patterning process involves depositing positive e-beam resist on 1 to 30 mm thick, 100 mm diameter monolithic crystalline silicon substrates. We then use the facility JEOL 9300FS e-beam writer at JPL to produce the linear pattern that defines the gratings. There are three key challenges to produce high-performance e-beam written silicon immersion gratings. (1) E- beam field and subfield stitching boundaries cause periodic cross-hatch structures along the grating grooves. The structures manifest themselves as spectral and spatial dimension ghosts in the diffraction limited point spread function (PSF) of the diffraction grating. In this paper, we show that the effects of e-beam field boundaries must be mitigated. We have significantly reduced ghost power with only minor increases in write time by using four or more field sizes of less than 500 μm. (2) The finite e-beam stage drift and run-out error cause large-scale structure in the wavefront error. We deal with this problem by applying a mark detection loop to check for and correct out minuscule stage drifts. We measure the level and direction of stage drift and show that mark detection reduces peak-to-valley wavefront error

  4. Measurement of large angle fragments induced by 400 MeV n-1 carbon ion beams

    NASA Astrophysics Data System (ADS)

    Aleksandrov, Andrey; Consiglio, Lucia; De Lellis, Giovanni; Di Crescenzo, Antonia; Lauria, Adele; Montesi, Maria Cristina; Patera, Vincenzo; Sirignano, Chiara; Tioukov, Valeri

    2015-09-01

    The use of carbon ion beams in radiotherapy presents significant advantages when compared to traditional x-ray. In fact, carbon ions deposit their energy inside the human body at the end of their range, the Bragg peak. Unlike x-ray beams, where the energy deposition decreases exponentially inside the irradiated volume, the shape of carbon beams is sharp and focused. Advantages are an increased energy released in the cancer volume while minimizing the irradiation to healthy tissues. Currently, the use of carbon beams is limited by the poor knowledge we have about the effects of the secondary fragments on the irradiated tissues. The secondary particles produced and their angular distribution is crucial to determine the global dose deposition. The knowledge of the flux of secondary particles plays a key role in the real time monitoring of the dose profile in hadron therapy. We present a detector based on nuclear emulsions for fragmentation measurements that performs a sub-micrometric tridimensional spatial resolution, excellent multi-particle separation and large angle track recognition. Nuclear emulsions are assembled in order to realize a hybrid detector (emulsion cloud chamber (ECC)) made of 300 μm nuclear emulsion films alternated with lead as passive material. Data reported here have been obtained by exposing two ECC detectors to the fragments produced by a 400 MeV n-1 12C beam on a composite target at the GSI laboratory in Germany. The ECC was exposed inside a more complex detector, named FIRST, in order to collect fragments with a continuous angular distribution in the range 47°-81° with respect to the beam axis. Results on the angular distribution of fragments as well as their momentum estimations are reported here.

  5. Bending of metal-filled carbon nanotube under electron beam irradiation

    SciTech Connect

    Misra, Abha

    2012-03-15

    Electron beam irradiation induced, bending of Iron filled, multiwalled carbon nanotubes is reported. Bending of both the carbon nanotube and the Iron contained within the core was achieved using two approaches with the aid of a high resolution electron microscope (HRTEM). In the first approach, bending of the nanotube structure results in response to the irradiation of a pristine kink defect site, while in the second approach, disordered sites induce bending by focusing the electron beam on the graphite walls. The HRTEM based in situ observations demonstrate the potential for using electron beam irradiation to investigate and manipulate the physical properties of confined nanoscale structures.

  6. Modeling the biophysical effects in a carbon beam delivery line by using Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Cho, Ilsung; Yoo, SeungHoon; Cho, Sungho; Kim, Eun Ho; Song, Yongkeun; Shin, Jae-ik; Jung, Won-Gyun

    2016-09-01

    The Relative biological effectiveness (RBE) plays an important role in designing a uniform dose response for ion-beam therapy. In this study, the biological effectiveness of a carbon-ion beam delivery system was investigated using Monte Carlo simulations. A carbon-ion beam delivery line was designed for the Korea Heavy Ion Medical Accelerator (KHIMA) project. The GEANT4 simulation tool kit was used to simulate carbon-ion beam transport into media. An incident energy carbon-ion beam with energy in the range between 220 MeV/u and 290 MeV/u was chosen to generate secondary particles. The microdosimetric-kinetic (MK) model was applied to describe the RBE of 10% survival in human salivary-gland (HSG) cells. The RBE weighted dose was estimated as a function of the penetration depth in the water phantom along the incident beam's direction. A biologically photon-equivalent Spread Out Bragg Peak (SOBP) was designed using the RBE-weighted absorbed dose. Finally, the RBE of mixed beams was predicted as a function of the depth in the water phantom.

  7. The measurement results of carbon ion beam structure extracted by bent crystal from U-70 accelerator

    NASA Astrophysics Data System (ADS)

    Afonin, A. G.; Barnov, E. V.; Britvich, G. I.; Chesnokov, Yu A.; Chirkov, P. N.; Durum, A. A.; Kostin, M. Yu; Maisheev, V. A.; Pitalev, V. I.; Reshetnikov, S. F.; Yanovich, A. A.; Nazhmudinov, R. M.; Kubankin, A. S.; Shchagin, A. V.

    2016-07-01

    The carbon ion +6C beam with energy 25 GeV/nucleon was extracted by bent crystal from the U-70 ring. The bent angle of silicon crystal was 85 mrad. About 2×105 particles for 109 circulated ions in the ring were observed in beam line 4a after bent crystal. Geometrical parameters, time structure and ion beam structure were measured. The ability of the bent monocrystal to extract and generate ion beam with necessary parameters for regular usage in physical experiments is shown in the first time.

  8. Fast ignition of inertial fusion targets by laser-driven carbon beams

    SciTech Connect

    Honrubia, J. J.; Temporal, M.; Fernandez, J. C.; Hegelich, B. M.; Meyer-ter-Vehn, J.

    2009-10-15

    Two-dimensional simulations of ion beam driven fast ignition are presented. Ignition energies of protons with Maxwellian spectrum and carbon ions with quasimonoenergetic and Maxwellian energy distributions are evaluated. The effect of the coronal plasma surrounding the compressed deuterium-tritium is studied for three different fuel density distributions. It is found that quasimonoenergetic ions have better coupling with the compressed deuterium-tritium and substantially lower ignition energies. Comparison of quasimonoenergetic carbon ions and relativistic electrons as ignitor beams shows similar laser energy requirements, provided that a laser to quasimonoenergetic carbon ion conversion efficiency around 10% can be achieved.

  9. Water equivalent thickness values of materials used in beams of protons, helium, carbon and iron ions.

    PubMed

    Zhang, Rui; Taddei, Phillip J; Fitzek, Markus M; Newhauser, Wayne D

    2010-05-01

    Heavy charged particle beam radiotherapy for cancer is of increasing interest because it delivers a highly conformal radiation dose to the target volume. Accurate knowledge of the range of a heavy charged particle beam after it penetrates a patient's body or other materials in the beam line is very important and is usually stated in terms of the water equivalent thickness (WET). However, methods of calculating WET for heavy charged particle beams are lacking. Our objective was to test several simple analytical formulas previously developed for proton beams for their ability to calculate WET values for materials exposed to beams of protons, helium, carbon and iron ions. Experimentally measured heavy charged particle beam ranges and WET values from an iterative numerical method were compared with the WET values calculated by the analytical formulas. In most cases, the deviations were within 1 mm. We conclude that the analytical formulas originally developed for proton beams can also be used to calculate WET values for helium, carbon and iron ion beams with good accuracy.

  10. Water equivalent thickness values of materials used in beams of protons, helium, carbon and iron ions.

    PubMed

    Zhang, Rui; Taddei, Phillip J; Fitzek, Markus M; Newhauser, Wayne D

    2010-05-01

    Heavy charged particle beam radiotherapy for cancer is of increasing interest because it delivers a highly conformal radiation dose to the target volume. Accurate knowledge of the range of a heavy charged particle beam after it penetrates a patient's body or other materials in the beam line is very important and is usually stated in terms of the water equivalent thickness (WET). However, methods of calculating WET for heavy charged particle beams are lacking. Our objective was to test several simple analytical formulas previously developed for proton beams for their ability to calculate WET values for materials exposed to beams of protons, helium, carbon and iron ions. Experimentally measured heavy charged particle beam ranges and WET values from an iterative numerical method were compared with the WET values calculated by the analytical formulas. In most cases, the deviations were within 1 mm. We conclude that the analytical formulas originally developed for proton beams can also be used to calculate WET values for helium, carbon and iron ion beams with good accuracy. PMID:20371908

  11. Fabrication of high-aspect-ratio carbon nanocone probes by electron beam induced deposition patterning

    NASA Astrophysics Data System (ADS)

    Chen, I.-Chen; Chen, Li-Han; Orme, Christine; Quist, Arjan; Lal, Ratnesh; Jin, Sungho

    2006-09-01

    A high-aspect-ratio cone-shaped carbon nanotube (CNT), which we refer to as a carbon nanocone (CNC), was fabricated for scanning probe microscopy (SPM) by a novel and reliable patterning technique and dc plasma chemical vapour deposition. Carbon dots from electron beam induced deposition (EBID) were utilized as convenient chemical-etch masks to create catalyst patterns for the growth of a single CNC probe on a tipless cantilever and an array of CNC probes on a silicon substrate. This resist-free EBID process is an efficient way of preparing a patterned catalyst and resultant nanoprobe on the specific edge location of the cantilever. The CNC probe produces high-resolution images of specimens in air as well as in liquid. No degradation in imaging performance was observed after a period of continuous scanning. The CNC bed-of-nails array imaged in contact mode by a commercial Si3N4 probe demonstrates the mechanical toughness/sturdiness of the CNC tip. This also indicates the possibility of using the CNC bed-of-nails as a convenient means for the characterization of SPM tips.

  12. Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

    DOE PAGESBeta

    Islam, A. E.; Zakharov, D.; Stach, E. A.; Nikoleav, P.; Amama, P. B.; Sargent, G.; Saber, S.; Huffman, D.; Erford, M.; Semiatin, S. L.; et al

    2015-09-16

    Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only inmore » the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. As a result, with the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.« less

  13. Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

    SciTech Connect

    Islam, A. E.; Zakharov, D.; Stach, E. A.; Nikoleav, P.; Amama, P. B.; Sargent, G.; Saber, S.; Huffman, D.; Erford, M.; Semiatin, S. L.; Maruyama, B.

    2015-09-16

    Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only in the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. As a result, with the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.

  14. Impact of Various Beam Parameters on Lateral Scattering in Proton and Carbon-ion Therapy

    PubMed Central

    Ebrahimi Loushab, M.; Mowlavi, A.A.; Hadizadeh, M.H.; Izadi, R.; Jia, S.B.

    2015-01-01

    Background In radiation therapy with ion beams, lateral distributions of absorbed dose in the tissue are important. Heavy ion therapy, such as carbon-ion therapy, is a novel technique of high-precision external radiotherapy which has advantages over proton therapy in terms of dose locality and biological effectiveness. Methods In this study, we used Monte Carlo method-based Geant4 toolkit to simulate and calculate the effects of energy, shape and type of ion beams incident upon water on multiple scattering processes. Nuclear reactions have been taken into account in our calculation. A verification of this approach by comparing experimental data and Monte Carlo methods will be presented in an upcoming paper. Results Increasing particle energies, the width of the Bragg curve becomes larger but with increasing mass of particles, the width of the Bragg curve decreases. This is one of the advantages of carbon-ion therapy to treat with proton. The transverse scattering of dose distribution is increased with energy at the end of heavy ion beam range. It can also be seen that the amount of the dose scattering for carbon-ion beam is less than that of proton beam, up to about 160mm depth in water. Conclusion The distortion of Bragg peak profiles, due to lateral scattering of carbon-ion, is less than proton. Although carbon-ions are primarily scattered less than protons, the corresponding dose distributions, especially the lateral dose, are not much less. PMID:26688795

  15. Scintillation imaging of air during proton and carbon-ion beam irradiations

    NASA Astrophysics Data System (ADS)

    Yamamoto, Seiichi; Toshito, Toshiyuki; Akagi, Takashi; Yamashita, Tomohiro; Komori, Masataka

    2016-10-01

    We previously reported that the luminescence imaging of water during proton or carbon-ion irradiation is possible using a charge-coupled device (CCD) camera, and these luminescence images can be used for the range estimations for these therapies. In the images during these irradiations to water phantoms, we observed scintillation images in the air parts. We conducted analysis of these images during proton and carbon-ion irradiations to use them for beam width estimations. We set profiles on the air part of the luminescence images of water during 100.2 MeV proton and 241.5 MeV/n carbon-ion irradiations. We estimated the widths of the beams from the scintillation images and compared them with those by simulation results. We also estimated the intensity and light spectrum of the scintillation of air and compared with those of the luminescence of water. The estimated widths of the proton and carbon-ion beams from the scintillation images of air were almost the same as those measured with simulations. The intensities of the scintillation of air were 3% and 5% of those of the luminescence of water for the proton and carbon-ion beams, respectively. The light spectrum of the scintillation of air peaked around 350-450 nm while those of luminescence of water showed wide distribution which peaked 450-550 nm. We confirmed that scintillation imaging of air during proton and carbon-ion beam irradiations were possible. The scintillation imaging of air could be used for the width estimations of proton and carbon-ion beams.

  16. Influence of laser array performance on spectrally combined beam

    NASA Astrophysics Data System (ADS)

    Wu, Zhen; Yang, Lei; Zhong, Zheqiang; Zhang, Bin

    2016-10-01

    Incoherent spectral beam combining (SBC) of multiple laser beams is accomplished along the emitters' arraying direction. Considering that the output beams from a laser array (LA) usually have deflection angles, positional displacements and divergence angles even after being collimated, a propagation model of SBC systems based on multilayer dielectric gratings has been built up. On the basis, properties of the spectrally combined beam affected by parameters of the LA have been discussed in detail. Simulation results show that with the increase in the deflection angle, both the power and the beam quality of the combined beam degrade dramatically. The positional displacement has little impact on the intensity distribution and the beam quality of combined beam but change the wavelength composition of the combined beam. The divergence angle strongly affects the intensity distribution and the beam quality of the combined beam. Additionally, the effect of the deflection angle on the output beam quality is more obvious and may shift the beam spot when comparing with that of the divergence angle.

  17. Graphitic carbon growth on crystalline and amorphous oxide substrates using molecular beam epitaxy

    PubMed Central

    2011-01-01

    We report graphitic carbon growth on crystalline and amorphous oxide substrates by using carbon molecular beam epitaxy. The films are characterized by Raman spectroscopy and X-ray photoelectron spectroscopy. The formations of nanocrystalline graphite are observed on silicon dioxide and glass, while mainly sp2 amorphous carbons are formed on strontium titanate and yttria-stabilized zirconia. Interestingly, flat carbon layers with high degree of graphitization are formed even on amorphous oxides. Our results provide a progress toward direct graphene growth on oxide materials. PACS: 81.05.uf; 81.15.Hi; 78.30.Ly. PMID:22029707

  18. Electron-muon ranger: performance in the MICE muon beam

    NASA Astrophysics Data System (ADS)

    Adams, D.; Alekou, A.; Apollonio, M.; Asfandiyarov, R.; Barber, G.; Barclay, P.; de Bari, A.; Bayes, R.; Bayliss, V.; Bene, P.; Bertoni, R.; Blackmore, V. J.; Blondel, A.; Blot, S.; Bogomilov, M.; Bonesini, M.; Booth, C. N.; Bowring, D.; Boyd, S.; Bradshaw, T. W.; Bravar, U.; Bross, A. D.; Cadoux, F.; Capponi, M.; Carlisle, T.; Cecchet, G.; Charnley, C.; Chignoli, F.; Cline, D.; Cobb, J. H.; Colling, G.; Collomb, N.; Coney, L.; Cooke, P.; Courthold, M.; Cremaldi, L. M.; Debieux, S.; DeMello, A.; Dick, A.; Dobbs, A.; Dornan, P.; Drielsma, F.; Filthaut, F.; Fitzpatrick, T.; Franchini, P.; Francis, V.; Fry, L.; Gallagher, A.; Gamet, R.; Gardener, R.; Gourlay, S.; Grant, A.; Graulich, J. S.; Greis, J.; Griffiths, S.; Hanlet, P.; Hansen, O. M.; Hanson, G. G.; Hart, T. L.; Hartnett, T.; Hayler, T.; Heidt, C.; Hills, M.; Hodgson, P.; Hunt, C.; Husi, C.; Iaciofano, A.; Ishimoto, S.; Kafka, G.; Kaplan, D. M.; Karadzhov, Y.; Kim, Y. K.; Kuno, Y.; Kyberd, P.; Lagrange, J.-B.; Langlands, J.; Lau, W.; Leonova, M.; Li, D.; Lintern, A.; Littlefield, M.; Long, K.; Luo, T.; Macwaters, C.; Martlew, B.; Martyniak, J.; Masciocchi, F.; Mazza, R.; Middleton, S.; Moretti, A.; Moss, A.; Muir, A.; Mullacrane, I.; Nebrensky, J. J.; Neuffer, D.; Nichols, A.; Nicholson, R.; Nicola, L.; Noah Messomo, E.; Nugent, J. C.; Oates, A.; Onel, Y.; Orestano, D.; Overton, E.; Owens, P.; Palladino, V.; Pasternak, J.; Pastore, F.; Pidcott, C.; Popovic, M.; Preece, R.; Prestemon, S.; Rajaram, D.; Ramberger, S.; Rayner, M. A.; Ricciardi, S.; Roberts, T. J.; Robinson, M.; Rogers, C.; Ronald, K.; Rothenfusser, K.; Rubinov, P.; Rucinski, P.; Sakamato, H.; Sanders, D. A.; Sandström, R.; Santos, E.; Savidge, T.; Smith, P. J.; Snopok, P.; Soler, F. J. P.; Speirs, D.; Stanley, T.; Stokes, G.; Summers, D. J.; Tarrant, J.; Taylor, I.; Tortora, L.; Torun, Y.; Tsenov, R.; Tunnell, C. D.; Uchida, M. A.; Vankova-Kirilova, G.; Virostek, S.; Vretenar, M.; Warburton, P.; Watson, S.; White, C.; Whyte, C. G.; Wilson, A.; Wisting, H.; Yang, X.; Young, A.; Zisman, M.

    2015-12-01

    The Muon Ionization Cooling Experiment (MICE) will perform a detailed study of ionization cooling to evaluate the feasibility of the technique. To carry out this program, MICE requires an efficient particle-identification (PID) system to identify muons. The Electron-Muon Ranger (EMR) is a fully-active tracking-calorimeter that forms part of the PID system and tags muons that traverse the cooling channel without decaying. The detector is capable of identifying electrons with an efficiency of 98.6%, providing a purity for the MICE beam that exceeds 99.8%. The EMR also proved to be a powerful tool for the reconstruction of muon momenta in the range 100-280 MeV/c.

  19. Electron-Muon Ranger: Performance in the MICE muon beam

    DOE PAGESBeta

    Adams, D.

    2015-12-16

    The Muon Ionization Cooling Experiment (MICE) will perform a detailed study of ionization cooling to evaluate the feasibility of the technique. To carry out this program, MICE requires an efficient particle-identification (PID) system to identify muons. The Electron-Muon Ranger (EMR) is a fully-active tracking-calorimeter that forms part of the PID system and tags muons that traverse the cooling channel without decaying. The detector is capable of identifying electrons with an efficiency of 98.6%, providing a purity for the MICE beam that exceeds 99.8%. Lastly, the EMR also proved to be a powerful tool for the reconstruction of muon momenta inmore » the range 100–280 MeV/c.« less

  20. Electron-Muon Ranger: Performance in the MICE muon beam

    SciTech Connect

    Adams, D.

    2015-12-16

    The Muon Ionization Cooling Experiment (MICE) will perform a detailed study of ionization cooling to evaluate the feasibility of the technique. To carry out this program, MICE requires an efficient particle-identification (PID) system to identify muons. The Electron-Muon Ranger (EMR) is a fully-active tracking-calorimeter that forms part of the PID system and tags muons that traverse the cooling channel without decaying. The detector is capable of identifying electrons with an efficiency of 98.6%, providing a purity for the MICE beam that exceeds 99.8%. Lastly, the EMR also proved to be a powerful tool for the reconstruction of muon momenta in the range 100–280 MeV/c.

  1. Structural Modification of Single Wall and Multiwalled Carbon Nanotubes under Carbon, Nickel and Gold Ion Beam Irradiation

    SciTech Connect

    Jeet, Kiran; Jindal, V. K.; Dharamvir, Keya; Bharadwaj, L. M.

    2011-12-12

    Thin film samples of carbon nanotubes were irradiated with ion beam of carbon, nickel and gold. The irradiation results were characterized using Raman Spectroscopy. Modifications of the disorder mode (D mode) and the tangential mode (G mode) under different irradiation fluences were studied in detail. Raman results of carbon ion beam indicate the interesting phenomenon of ordering of the system under irradiation. Under the effect of nickel and gold ion irradiation, the structural evolution of CNTs occurs in three different stages. At lower fluences the process of healing occurs; at intermediate fluences damages on the surface of CNTs occurs and finally at very high fluences of the order of 1x10{sup 14} ions/cm{sup 2} the system gets amorphised.

  2. Advanced Electron Beam Ion Sources (EBIS) for 2-nd generation carbon radiotherapy facilities

    NASA Astrophysics Data System (ADS)

    Shornikov, A.; Wenander, F.

    2016-04-01

    In this work we analyze how advanced Electron Beam Ion Sources (EBIS) can facilitate the progress of carbon therapy facilities. We will demonstrate that advanced ion sources enable operation of 2-nd generation ion beam therapy (IBT) accelerators. These new accelerator concepts with designs dedicated to IBT provide beams better suited for therapy and, are more cost efficient than contemporary IBT facilities. We will give a sort overview of the existing new IBT concepts and focus on those where ion source technology is the limiting factor. We will analyse whether this limitation can be overcome in the near future thanks to ongoing EBIS development.

  3. Effect of the transverse parasitic mode on beam performance for the ADS driver linac in China

    NASA Astrophysics Data System (ADS)

    Cheng, Peng; Pei, Shi-Lun; Wang, Jiu-Qing; Li, Zhi-Hui

    2015-05-01

    The ADS (Accelerator Driven subcritical System) driver linac in China is designed to run in CW (Continuous Wave) mode with 10 mA designed beam current. In this scenario, the beam-induced parasitic modes in the ADS driver linac may make the beam unstable or deteriorate the beam performance. To evaluate the parasitic mode effect on the beam dynamics systematically, simulation studies using the ROOT-based numerical code SMD have been conducted. The longitudinal beam instability induced by the HOMs (High Order Modes) and SOMs (Same Order Modes) has little effect on the longitudinal beam performance for the current ADS driver linac design based on the 10 MeV/325 MHz injector I from previous studies. Here the transverse parasitic mode (i.e., dipole HOM) effect on the transverse beam performance at the ADS driver linac exit is investigated. To more reasonably quantify the dipole mode effect, the multi-bunch effective emittance is introduced in this paper.

  4. Rehabilitation of notch damaged steel beam using a carbon fiber reinforced multiphase-matrix composite

    SciTech Connect

    Zhou, HongYu; Attard, Dr. Thomas L.; Wang, Yanli; Wang, Jy-An John; Ren, Fei

    2013-01-01

    The retrofit of notch damaged steel beams is investigated via the experimental testing of nine wide-flange steel beam specimens and finite element simulation. Three notch configurations representing various damage levels were identified, and the beam specimens were retrofitted using CFRP laminates and a recently developed polymeric matrix composite - CarbonFlex - that exhibits superior energy dissipation and ductility properties, where the peak-load deflections were between 49.4% and 65.2% higher using the CarbonFlex-retrofitted beams. The results are attributed to the substantially higher damage tolerance capability of CarbonFlex than conventional CFRP. Finite element models were developed to investigate the damage processes and strain/ stress distributions near the notch tips. The numerical results match closely with the experimentally determined load-deflection curves and the strain fields obtained by the digital imaging correlations (DIC) system. Both experimental and numerical results clearly indicate the effectiveness of CarbonFlex, as a candidate retrofitting material, to retrofit damaged steel structures. Lastly, the micro-mechanisms by which CarbonFlex could sufficiently sustain a significant amount of the peak strength at large displacement ductility values are discussed with the aid of scanning electron microscopy (SEM) pictures.

  5. Nanocrystalline metal/carbon composites produced by supersonic cluster beam deposition.

    PubMed

    Bongiorno, G; Lenardi, C; Ducati, C; Agostino, R G; Caruso, T; Amati, M; Blomqvist, M; Barborini, E; Piseri, P; La Rosa, S; Colavita, E; Milani, P

    2005-07-01

    In this work we show that supersonic cluster beam deposition is a viable method for the synthesis of nanocrystalline metal/carbon composites. By assembling carbon and metallic clusters seeded in a supersonic beam, we have grown films consisting of metal nanoparticles embedded in a nano-structured carbon matrix. Samples containing 3d transition metals (Ti, Ni) and noble metals (Au, Pd, Pt) with different metal abundances, particle size and dilution have been characterized by transmission electron microscopy. The influence of different metals on the structure of the carbon matrix has been investigated. Spatially resolved ultraviolet photoemission electron spectroscopy showed substantial surface oxidation of 3d transition metal clusters. On a micrometric scale, the spatial distribution of the metallic nanoparticles appeared to be homogeneous.

  6. Role of lattice structure and low temperature resistivity in fast-electron-beam filamentation in carbon

    NASA Astrophysics Data System (ADS)

    Dance, R. J.; Butler, N. M. H.; Gray, R. J.; MacLellan, D. A.; Rusby, D. R.; Scott, G. G.; Zielbauer, B.; Bagnoud, V.; Xu, H.; Robinson, A. P. L.; Desjarlais, M. P.; Neely, D.; McKenna, P.

    2016-01-01

    The influence of low temperature (eV to tens-of-eV) electrical resistivity on the onset of the filamentation instability in fast-electron transport is investigated in targets comprising of layers of ordered (diamond) and disordered (vitreous) carbon. It is shown experimentally and numerically that the thickness of the disordered carbon layer influences the degree of filamentation of the fast-electron beam. Strong filamentation is produced if the thickness is of the order of 60 μm or greater, for an electron distribution driven by a sub-picosecond, mid-1020 Wcm-2 laser pulse. It is shown that the position of the vitreous carbon layer relative to the fast-electron source (where the beam current density and background temperature are highest) does not have a strong effect because the resistive filamentation growth rate is high in disordered carbon over a wide range of temperatures up to the Spitzer regime.

  7. Reinforcement of timber beams with carbon fibers reinforced plastics

    NASA Astrophysics Data System (ADS)

    Gugutsidze, G.; Draškovič, F.

    2010-06-01

    Wood is a polymeric material with many valuable features and which also lacks some negative features. In order to keep up with high construction rates and the minimization of negative effects, wood has become one of the most valuable materials in modern engineering. But the use of timber material economically is also an actual problem in order to protect the environment and improve natural surroundings. A panel of scientists is interested in solving these problems and in creating rational structures, where timber can be used efficiently. These constructions are as follows: glue-laminated (gluelam), composed and reinforced wooden constructions. Composed and reinforced wooden constructions are examined less, but according to researches already carried out, it is clear that significant work can be accomplished in creating rational, highly effective and economic timber constructions. The paper deals with research on the formation of composed fiber-reinforced beams (CFRP) made of timber and provide evidence of their effectiveness. The aim of the paper is to investigate cross-bending of CFRP-reinforced gluelaminated timber beams. According to the results we were able to determine the additional effectiveness of reinforcement with CFRP (which depends on the CFRP material's quality, quantity and module of elasticity) on the mechanical features of timber and a whole beam.

  8. SU-E-T-509: Validation of the Use of OSLD for Carbon Beam Remote Dosimetry

    SciTech Connect

    Summers, P; Lowenstein, J; Alvarez, P; Followill, D; Jakel, O; Prokesch, H

    2014-06-01

    Purpose: To describe the commissioning of Aluminum Oxide Optically Stimulated Luminescent Dosimeters (OSLD) for the use in Carbon beam remote dosimetry for centers participating in NCI-funded cooperative group clinical trials. Methods: As Carbon therapy centers express interest in participating in cooperative group clinical trials, the Imaging and Radiation Oncology Core Group (IROC) Houston QA Center (formerly RPC) is developing a way to remotely monitor the machine output of these Carbon facilities. OSLD have been commissioned for photon, electron and proton dosimetry, so an experiment was designed to commission the same dosimeters for Carbon. OSLD were irradiated in a Carbon therapy beam produced by the Siemens synchrotron at the Heidelberg Ion Therapy facility in Heidelberg, Germany. The OSLD were placed in acrylic phantoms, imaged with a CT scanner, and plans were developed using the Siemens treatment planning system. The OSLD were irradiated in uniform fields with maximum energies of 216, 301, and 402 MeV and at dose levels of 50, 100, 200 and 300 cGy. Results: The response of the OSLD in the Carbon beam, as compared to the Cobalt-60 reference condition, required an energy correction of 1.85 to account for the particle correction. OSLD dose calculations typically have a linearity correction to account for the change in response relative to the change in dose delivered. However, the response of the OSLD in the Carbon beam was found to be independent of the dose level; thus the linearity correction is 1.00. Conclusion: IROC Houston has commissioned OSLD for the use of remote output checks for Carbon therapy facilities to help ensure consistency across clinical trial participants. Work supported by grant CA10953 (NCI, DHHS)

  9. Future carbon beams at SPIRAL1 facility: which method is the most efficient?

    PubMed

    Maunoury, L; Delahaye, P; Angot, J; Dubois, M; Dupuis, M; Frigot, R; Grinyer, J; Jardin, P; Leboucher, C; Lamy, T

    2014-02-01

    Compared to in-flight facilities, Isotope Separator On-Line ones can in principle produce significantly higher radioactive ion beam intensities. On the other hand, they have to cope with delays for the release and ionization which make the production of short-lived isotopes ion beams of reactive and refractory elements particularly difficult. Many efforts are focused on extending the capabilities of ISOL facilities to those challenging beams. In this context, the development of carbon beams is triggering interest [H. Frånberg, M. Ammann, H. W. Gäggeler, and U. Köster, Rev. Sci. Instrum. 77, 03A708 (2006); M. Kronberger, A. Gottberg, T. M. Mendonca, J. P. Ramos, C. Seiffert, P. Suominen, and T. Stora, in Proceedings of the EMIS 2012 [Nucl. Instrum. Methods Phys. Res. B Production of molecular sideband radioisotope beams at CERN-ISOLDE using a Helicon-type plasma ion source (to be published)]: despite its refractory nature, radioactive carbon beams can be produced from molecules (CO or CO2), which can subsequently be broken up and multi-ionized to the required charge state in charge breeders or ECR sources. This contribution will present results of experiments conducted at LPSC with the Phoenix charge breeder and at GANIL with the Nanogan ECR ion source for the ionization of carbon beams in the frame of the ENSAR and EMILIE projects. Carbon is to date the lightest condensable element charge bred with an ECR ion source. Charge breeding efficiencies will be compared with those obtained using Nanogan ECRIS and charge breeding times will be presented as well. PMID:24593427

  10. Future carbon beams at SPIRAL1 facility: Which method is the most efficient?

    NASA Astrophysics Data System (ADS)

    Maunoury, L.; Delahaye, P.; Angot, J.; Dubois, M.; Dupuis, M.; Frigot, R.; Grinyer, J.; Jardin, P.; Leboucher, C.; Lamy, T.

    2014-02-01

    Compared to in-flight facilities, Isotope Separator On-Line ones can in principle produce significantly higher radioactive ion beam intensities. On the other hand, they have to cope with delays for the release and ionization which make the production of short-lived isotopes ion beams of reactive and refractory elements particularly difficult. Many efforts are focused on extending the capabilities of ISOL facilities to those challenging beams. In this context, the development of carbon beams is triggering interest [H. Frånberg, M. Ammann, H. W. Gäggeler, and U. Köster, Rev. Sci. Instrum. 77, 03A708 (2006); M. Kronberger, A. Gottberg, T. M. Mendonca, J. P. Ramos, C. Seiffert, P. Suominen, and T. Stora, in Proceedings of the EMIS 2012 [Nucl. Instrum. Methods Phys. Res. B Production of molecular sideband radioisotope beams at CERN-ISOLDE using a Helicon-type plasma ion source (to be published)]: despite its refractory nature, radioactive carbon beams can be produced from molecules (CO or CO2), which can subsequently be broken up and multi-ionized to the required charge state in charge breeders or ECR sources. This contribution will present results of experiments conducted at LPSC with the Phoenix charge breeder and at GANIL with the Nanogan ECR ion source for the ionization of carbon beams in the frame of the ENSAR and EMILIE projects. Carbon is to date the lightest condensable element charge bred with an ECR ion source. Charge breeding efficiencies will be compared with those obtained using Nanogan ECRIS and charge breeding times will be presented as well.

  11. Future carbon beams at SPIRAL1 facility: which method is the most efficient?

    PubMed

    Maunoury, L; Delahaye, P; Angot, J; Dubois, M; Dupuis, M; Frigot, R; Grinyer, J; Jardin, P; Leboucher, C; Lamy, T

    2014-02-01

    Compared to in-flight facilities, Isotope Separator On-Line ones can in principle produce significantly higher radioactive ion beam intensities. On the other hand, they have to cope with delays for the release and ionization which make the production of short-lived isotopes ion beams of reactive and refractory elements particularly difficult. Many efforts are focused on extending the capabilities of ISOL facilities to those challenging beams. In this context, the development of carbon beams is triggering interest [H. Frånberg, M. Ammann, H. W. Gäggeler, and U. Köster, Rev. Sci. Instrum. 77, 03A708 (2006); M. Kronberger, A. Gottberg, T. M. Mendonca, J. P. Ramos, C. Seiffert, P. Suominen, and T. Stora, in Proceedings of the EMIS 2012 [Nucl. Instrum. Methods Phys. Res. B Production of molecular sideband radioisotope beams at CERN-ISOLDE using a Helicon-type plasma ion source (to be published)]: despite its refractory nature, radioactive carbon beams can be produced from molecules (CO or CO2), which can subsequently be broken up and multi-ionized to the required charge state in charge breeders or ECR sources. This contribution will present results of experiments conducted at LPSC with the Phoenix charge breeder and at GANIL with the Nanogan ECR ion source for the ionization of carbon beams in the frame of the ENSAR and EMILIE projects. Carbon is to date the lightest condensable element charge bred with an ECR ion source. Charge breeding efficiencies will be compared with those obtained using Nanogan ECRIS and charge breeding times will be presented as well.

  12. Future carbon beams at SPIRAL1 facility: Which method is the most efficient?

    SciTech Connect

    Maunoury, L. Delahaye, P.; Dubois, M.; Dupuis, M.; Frigot, R.; Grinyer, J.; Jardin, P.; Leboucher, C.

    2014-02-15

    Compared to in-flight facilities, Isotope Separator On-Line ones can in principle produce significantly higher radioactive ion beam intensities. On the other hand, they have to cope with delays for the release and ionization which make the production of short-lived isotopes ion beams of reactive and refractory elements particularly difficult. Many efforts are focused on extending the capabilities of ISOL facilities to those challenging beams. In this context, the development of carbon beams is triggering interest [H. Frånberg, M. Ammann, H. W. Gäggeler, and U. Köster, Rev. Sci. Instrum. 77, 03A708 (2006); M. Kronberger, A. Gottberg, T. M. Mendonca, J. P. Ramos, C. Seiffert, P. Suominen, and T. Stora, in Proceedings of the EMIS 2012 [Nucl. Instrum. Methods Phys. Res. B Production of molecular sideband radioisotope beams at CERN-ISOLDE using a Helicon-type plasma ion source (to be published)]: despite its refractory nature, radioactive carbon beams can be produced from molecules (CO or CO{sub 2}), which can subsequently be broken up and multi-ionized to the required charge state in charge breeders or ECR sources. This contribution will present results of experiments conducted at LPSC with the Phoenix charge breeder and at GANIL with the Nanogan ECR ion source for the ionization of carbon beams in the frame of the ENSAR and EMILIE projects. Carbon is to date the lightest condensable element charge bred with an ECR ion source. Charge breeding efficiencies will be compared with those obtained using Nanogan ECRIS and charge breeding times will be presented as well.

  13. Digital-image-correlation-based experimental stress analysis of reinforced concrete beams strengthened using carbon composites

    NASA Astrophysics Data System (ADS)

    Helm, Jeffrey; Kurtz, Stephen

    2005-01-01

    The strengthening of reinforced concrete beams through the use of epoxy-bonded carbon composites has been widely researched in the United States since 1991. Despite the widespread attention of researchers, however, there are no reliable methods of predicting the failure of the repaired and strengthened beams by peeling of the fiber reinforced polymer (FRP) material from the parent concrete. To better understand peeling failure, several investigators have presented analytical work to predict the distribution of stresses along the interface between the FRP and the concrete. Several closed-form solutions can be found in the literature to predict the levels of shear stress present between the bonded composite plate and the parent concrete beam. However, there has been very little experimental verification of these analytical predictions because few experiments on large-scale beams have had sufficient instrumentation to facilitate the comparison. Some experiments have been presented1 in which electrical resistance strain gages were placed along the length of the carbon plate in order to deduce the interfacial shear stress using first differences. This method, though very crude, demonstrated that there are substantial differences between the distributions of interfacial shear stresses in actual repaired beams versus the analytical predictions. This paper presents a new test program in which large-scale carbon-fiber-strengthened reinforced concrete beams are load-tested to failure, while employing digital image correlation (DIC) to record the strains in the carbon fiber plate. Relying on the linear elasticity of carbon fiber, the interfacial shear can be determined and compared with the analytical predictions of the literature. The focus of this paper is the presentation of the experimental shear stress distributions and comparisons of these distributions with previous results available in the literature.

  14. Digital-image-correlation-based experimental stress analysis of reinforced concrete beams, strengthened using carbon composites

    NASA Astrophysics Data System (ADS)

    Helm, Jeffrey; Kurtz, Stephen

    2004-12-01

    The strengthening of reinforced concrete beams through the use of epoxy-bonded carbon composites has been widely researched in the United States since 1991. Despite the widespread attention of researchers, however, there are no reliable methods of predicting the failure of the repaired and strengthened beams by peeling of the fiber reinforced polymer (FRP) material from the parent concrete. To better understand peeling failure, several investigators have presented analytical work to predict the distribution of stresses along the interface between the FRP and the concrete. Several closed-form solutions can be found in the literature to predict the levels of shear stress present between the bonded composite plate and the parent concrete beam. However, there has been very little experimental verification of these analytical predictions because few experiments on large-scale beams have had sufficient instrumentation to facilitate the comparison. Some experiments have been presented1 in which electrical resistance strain gages were placed along the length of the carbon plate in order to deduce the interfacial shear stress using first differences. This method, though very crude, demonstrated that there are substantial differences between the distributions of interfacial shear stresses in actual repaired beams versus the analytical predictions. This paper presents a new test program in which large-scale carbon-fiber-strengthened reinforced concrete beams are load-tested to failure, while employing digital image correlation (DIC) to record the strains in the carbon fiber plate. Relying on the linear elasticity of carbon fiber, the interfacial shear can be determined and compared with the analytical predictions of the literature. The focus of this paper is the presentation of the experimental shear stress distributions and comparisons of these distributions with previous results available in the literature.

  15. Quasi-steady carbon plasma source for neutral beam injector.

    PubMed

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2014-02-01

    Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

  16. Quasi-steady carbon plasma source for neutral beam injector

    SciTech Connect

    Koguchi, H. Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y.

    2014-02-15

    Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

  17. Reactions of carbon atoms in pulsed molecular beams

    SciTech Connect

    Reisler, H.

    1993-12-01

    This research program consists of a broad scope of experiments designed to unravel the chemistry of atomic carbon in its two spin states, P and D, by using well-controlled initial conditions and state-resolved detection of products. Prerequisite to the proposed studies (and the reason why so little is known about carbon atom reactions), is the development of clean sources of carbon atoms. Therefore, in parallel with the studies of its chemistry and reaction dynamics, the authors continuously explore new, state-specific and efficient ways of producing atomic carbon. In the current program, C({sup 3}P) is produced via laser ablation of graphite, and three areas of study are being pursued: (i) exothermic reactions with small inorganic molecules (e.g., O{sub 2}, N{sub 2}O, NO{sub 2}) that can proceed via multiple pathways; (ii) the influence of vibrational and translational energy on endothermic reactions involving H-containing reactants that yield CH products (e.g., H{sub 2}O H{sub 2}CO); (iii) reactions of C({sup 3}P) with free radicals (e.g., HCO, CH{sub 3}O). In addition, the authors plan to develop a source of C({sup 1}D) atoms by exploiting the pyrolysis of diazotetrazole and its salts in the ablation source. Another important goal involves collaboration with theoreticians in order to obtain relevant potential energy surfaces, rationalize the experimental results and predict the roles of translational and vibrational energies.

  18. Characterization of laser beam interaction with carbon materials

    NASA Astrophysics Data System (ADS)

    Janićijević, Milovan; Srećković, Milesa; Kaluđerović, Branka; Bojanić, Slobodan; Družijanić, Dragan; Dinulović, Mirko; Kovačević, Aleksander

    2013-05-01

    This paper presents simulation and experimental results for the exposure of some carbon-based materials to alexandrite and Nd3+:YAG (yttrium aluminum garnet) laser radiation. Simulation of the heating effects was carried out using the COMSOL Multiphysics 3.5 package for samples of carbon-based P7295-2 fiber irradiated using an alexandrite laser and carbon-based P4396-2 fiber irradiated using an Nd3+:YAG laser, as well as by applying finite element modeling for P7295-2 samples irradiated using an Nd3+:YAG laser. In the experimental part, P7295-2 samples were exposed to alexandrite laser radiation while samples of carbon-based composite 3D C/C were exposed to Nd3+:YAG laser radiation. Micrographs of the laser induced craters were obtained by light and scanning electron microscopy, and the images analyzed using the ImageJ software. The results obtained enable identification of the laser-material interaction spots, and characterization of the laser induced changes in the materials investigated.

  19. Optical transition radiation from a thin carbon foil: a beam profile monitor for the SLC

    SciTech Connect

    Jenkins, E.W.

    1983-11-01

    This memo considers placement of an ultra thin carbon foil into the SLC beam. Transition radiation light would be emitted from the surface of the foil. The optical spot from the foil could be viewed with a microscope objective lens and registered with an image detector. Multiple scattering for the foil thicknesses necessary will not affect the beam emittance. Calculations show that a thin carbon foil can withstand the electron beam if the electron beam is larger than 10 ..mu..m in size. There are many possible radiation mechanisms from a foil - bremsstrahlung, black body temperature radiation, Cerenkov light, scintillation light, and transition radiation. Transition radiation is apparently dominant. It is proposed to use thin carbon foils, 75 to 150 A thick. Calculations indicate that 5 x 10/sup 10/ beam electrons will radiate a useable number of optical photons. Specifically with 150 A foils the fractional yield of useful optical photons is 10/sup -3/ photons per incident electron 5 x 10/sup +7/ optical photons imaged upon an image plane. Spread these photons over a 32 x 32 pixel CCD and one has the readout system of a monitor.

  20. SEMICONDUCTOR TECHNOLOGY Supercritical carbon dioxide process for releasing stuck cantilever beams

    NASA Astrophysics Data System (ADS)

    Yu, Hui; Chaoqun, Gao; Lei, Wang; Yupeng, Jing

    2010-10-01

    The multi-SCCO2 (supercritical carbon dioxide) release and dry process based on our specialized SCCO2 semiconductor process equipment is investigated and the releasing mechanism is discussed. The experiment results show that stuck cantilever beams were held up again under SCCO2 high pressure treatment and the repeatability of this process is nearly 100%.

  1. Morphological and structural modifications of multiwalled carbon nanotubes by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Elsehly, Emad M.; Chechenin, N. G.; Makunin, A. V.; Motaweh, H. A.

    2016-10-01

    Effects of electron beam irradiation on a morphology and structure of multiwalled carbon nanotubes sample in a normal imaging regime of a scanning electron microscope (SEM) were investigated. Direct SEM observations give evidence that irradiation by electron beam in SEM eliminates morphological unevenness, in the form of round spots of white contrast, on the surface of carbon nanotubes (CNTs) and makes the tubes thinner. Electron dispersive analysis and Raman spectroscopy are used to explore the origin and nature of these spots. From this analysis we found that e-beam irradiation improves the CNTs graphitization. The synergy of thermal heating and ionization produced by the irradiation are discussed as possible mechanisms of the observed effects.

  2. Performance of laser inter-satellite links with dynamic beam waist adjustment.

    PubMed

    Song, Tianyu; Wang, Qian; Wu, Ming-Wei; Kam, Pooi-Yuen

    2016-05-30

    In this paper, we propose the idea of dynamic beam waist adjustment for laser inter-satellite communications, and study the performance of this dynamic-beam scheme. The beam waist adjustment is based on continuous detection of the instantaneous pointing error angle, which is performed at the transmitter side. Using a square to approximate the circular detector region, we obtain a closed-form expression for calculating the proportion of power that can be collected by the receiver aperture, and derive a simple algebraic solution for the optimum dynamic beam waist. Due to its simple form, the dynamic beam waist value can be computed in real time at the transmitter, and therefore, the adjustment is practically implementable. It is shown that the performance of laser inter-satellite links with dynamic beam waist is better than that with fixed beam waist. PMID:27410117

  3. Performance of laser inter-satellite links with dynamic beam waist adjustment.

    PubMed

    Song, Tianyu; Wang, Qian; Wu, Ming-Wei; Kam, Pooi-Yuen

    2016-05-30

    In this paper, we propose the idea of dynamic beam waist adjustment for laser inter-satellite communications, and study the performance of this dynamic-beam scheme. The beam waist adjustment is based on continuous detection of the instantaneous pointing error angle, which is performed at the transmitter side. Using a square to approximate the circular detector region, we obtain a closed-form expression for calculating the proportion of power that can be collected by the receiver aperture, and derive a simple algebraic solution for the optimum dynamic beam waist. Due to its simple form, the dynamic beam waist value can be computed in real time at the transmitter, and therefore, the adjustment is practically implementable. It is shown that the performance of laser inter-satellite links with dynamic beam waist is better than that with fixed beam waist.

  4. The E-beam resist test facility: performance testing and benchmarking of E-beam resists for advanced mask writers

    NASA Astrophysics Data System (ADS)

    Malloy, Matt; Jang, Il Yong; Mellish, Mac; Litt, Lloyd C.; Raghunathan, Ananthan; Hartley, John

    2012-11-01

    With each new generation of e-beam mask writers comes the ability to write leading edge photomasks with improved patterning performance and increased throughput. However, these cutting-edge e-beam tools are often used with older generation resists, preventing the end-user from taking full advantage of the tool's potential. The generation gap between tool and resist will become even more apparent with the commercialization of multi-beam mask writers, which are expected to be available for pilot line use around 2015. The mask industry needs resists capable of meeting the resolution, roughness, and sensitivity requirements of these advanced tools and applications. The E-beam Resist Test Facility (ERTF) has been established to fill the need for consortium-based testing of e-beam resists for mask writing applications on advanced mask writers out to the 11nm half-pitch node and beyond. SEMATECH and the College of Nanoscale Science and Engineering (CNSE) began establishing the ERTF in early 2012 to test e-beam resist samples from commercial suppliers and university labs against the required performance metrics for each application at the target node. Operations officially began on June 12, 2012, at which time the first e-beam resist samples were tested. The ERTF uses the process and metrology infrastructure available at CNSE, including a Vistec VB300 Vectorscan e-beam tool adjusted to operate at 50kv. Initial testing results show that multiple resists already meet, or are close to meeting, the resolution requirements for mask writing at the 11nm node, but other metrics such as line width roughness still need improvement. An overview of the ERTF and its capabilities is provided here. Tools, baseline processes, and operation strategy details are discussed, and resist testing and benchmarking results are shown. The long-term outlook for the ERTF and plans to expand capability and testing capacity, including resist testing for e-beam direct write lithography, are also

  5. Investigation of industrial-scale carbon dioxide reduction using pulsed electron beams

    NASA Astrophysics Data System (ADS)

    Petrov, G. M.; Apruzese, J. P.; Petrova, Tz. B.; Wolford, M. F.

    2016-03-01

    Carbon dioxide is the most important greenhouse gas contributing to global warming. To help mitigate increasing CO2 concentrations, we investigate a method of carbon dioxide reduction using high-power electron beams, which can be used on an industrial scale. A series of experiments are conducted in which the reduction of CO2 is measured for different gas compositions and power deposition rates. An electron beam deposition model is applied to compute reduction rates of CO2 and energy cost for breaking a CO2 molecule in flue gas and pure carbon dioxide at atmospheric pressure. For flue gas consisting of 82% N2, 6% O2, and 12% CO2, the calculated energy cost is 85 eV per molecule. In order to dissociate 50% of the CO2 molecules, beam energy density deposition on the order of 20 J/cm3 is required. Electron beam irradiation of 12.6 liter gas volume containing 90% CO2 and 10% CH4 at beam energy density deposition of 4.2 J/cm3, accumulated over 43 shots in a 20 min interval, reduced the CO2 concentration to 78%. Analogous experiments with a gas mixture containing 11.5% CO2, 11.5% CH4, and balance of Ar, reduced the CO2 concentration to below 11% with energy deposition 0.71 J/cm3, accumulated over 10 shots in a 5 min interval. The experimental data and the theoretical predictions of CO2 reduction using pulsed electron beams are in agreement within the experimental error. Other techniques to enhance the removal of CO2 with pulsed electron beams are also explored, yielding new possible avenues of research.

  6. Effect of Electron Beam Irradiation on the Tensile Properties of Carbon Nanotubes Sheets and Yarns

    NASA Technical Reports Server (NTRS)

    Williams, Tiffany S.; Miller, Sandi G.; Baker, James S.; McCorkle, Linda S.; Meador, Michael A.

    2013-01-01

    Carbon nanotube sheets and yarns were irradiated using electron beam (e-beam) energy to determine the effect of irradiation dose on the tensile properties. Results showed that a slight change in tensile strength occurred after irradiating as-received CNT sheets for 20 minutes, and a slight decrease in tensile strength as the irradiation time approached 90 minutes. On the other hand, the addition of small molecules to the CNT sheet surface had a greater effect on the tensile properties of e-beam irradiated CNT sheets. Some functionalized CNT sheets displayed up to a 57% increase in tensile strength following 90 minutes of e-beam exposure. In addition, as-received CNT yarns showed a significant increase in tensile strength as the irradiation time increased.

  7. The RHIC p-Carbon CNI Polarimeter Upgrade For The Beam Polarization And Intensity Measurements

    SciTech Connect

    Zelenski, A.; Bazilevski, A.; Bunce, G.; Gill, R.; Huang, H.; Mahler, G.; Makdisi, Y.; Morozov, B.; Nemesure, S.; Russo, T.; Steski, D.; Sivertz, M.

    2009-08-04

    Proton polarization measurements in the AGS and RHIC (Relativistic Heavy Ion Collider at the beam energies 24-250 GeV) are based on proton-carbon and proton-proton elastic scattering in the Coulomb Nuclear Interference (CNI) region. Polarimeter operation in the scanning mode also gives polarization profile and beam intensity profile (beam emittance) measurements. Bunch by bunch emittance measurement is a very powerful tool for machine setup. Presently, the polarization and beam intensity profile measurements (in both vertical and horizontal planes) are restricted by the long target switching time and possible target destruction during this complicated motion. The RHIC polarimeters were operated near the limit of the counting rate for present silicon strip detectors. The ongoing polarimeter upgrade for the 2009 run will address all these problems. The upgrade should allow significant reduction of the polarization measurement errors by making feasible the complete polarization measurements, which includes polarization profiles in both the horizontal and vertical planes.

  8. Stray Electric Field Due to the Carbon Foil Resistance in Hydrogen Beam-Foil-Spectroscopy Measurements

    NASA Astrophysics Data System (ADS)

    Singer, W.; Dehaes, J. C.; Carmeliet, J.

    1980-01-01

    We have measured the linear polarization of the Hβ transition at 486.1 nm excited by passage of a 110 keV proton beam through perpendicular carbon foils. We have observed that the polarization depends upon the beam intensity and on the relative position of the foil and its holder. We have shown that these dependences are linked to the presence of a stray electric field at the immediate vicinity of the foil. The field is due to the potential distribution at the foil surface resulting from the electron radial flow in the high foil electric resistance (about 50 kΩ). It introduces a perturbation which in our case is more important than the temperature effect observed by Gay and Berry (Phys. Rev. A19, 952 (1979)). The field is proportional to the beam current density and is reduced for large foil and beam diameters.

  9. Friction and Wear of Ion-Beam-Deposited Diamondlike Carbon on Chemical-Vapor-Deposited, Fine-Grain Diamond

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Wu, Richard L. C.; Lanter, William C.

    1996-01-01

    Friction and wear behavior of ion-beam-deposited diamondlike carbon (DLC) films coated on chemical-vapor-deposited (CVD), fine-grain diamond coatings were examined in ultrahigh vacuum, dry nitrogen, and humid air environments. The DLC films were produced by the direct impact of an ion beam (composed of a 3:17 mixture of Ar and CH4) at ion energies of 1500 and 700 eV and an RF power of 99 W. Sliding friction experiments were conducted with hemispherical CVD diamond pins sliding on four different carbon-base coating systems: DLC films on CVD diamond; DLC films on silicon; as-deposited, fine-grain CVD diamond; and carbon-ion-implanted, fine-grain CVD diamond on silicon. Results indicate that in ultrahigh vacuum the ion-beam-deposited DLC films on fine-grain CVD diamond (similar to the ion-implanted CVD diamond) greatly decrease both the friction and wear of fine-grain CVD diamond films and provide solid lubrication. In dry nitrogen and in humid air, ion-beam-deposited DLC films on fine-grain CVD diamond films also had a low steady-state coefficient of friction and a low wear rate. These tribological performance benefits, coupled with a wider range of coating thicknesses, led to longer endurance life and improved wear resistance for the DLC deposited on fine-grain CVD diamond in comparison to the ion-implanted diamond films. Thus, DLC deposited on fine-grain CVD diamond films can be an effective wear-resistant, lubricating coating regardless of environment.

  10. Analysis of carbon in SrTiO{sub 3} grown by hybrid molecular beam epitaxy

    SciTech Connect

    Jalan, Bharat; Cagnon, Joeel; Mates, Thomas E.; Stemmer, Susanne

    2009-11-15

    Secondary ion mass spectroscopy (SIMS) was used to investigate carbon impurity concentrations in stoichiometric SrTiO{sub 3} films grown by a hybrid molecular beam epitaxy approach that uses an effusion cell to supply strontium, a rf plasma source for oxygen and a metal organic titanium source (titanium tetra isopropoxide). The carbon concentration in the films was measured as a function of growth parameters. At sufficiently high growth temperatures (>800 degree sign C), the films contain a few ppm of carbon. The challenges in accurately quantifying low carbon concentrations are discussed. A carbon-containing contamination layer is detected on the surfaces of SrTiO{sub 3} substrates and air-exposed films by SIMS and in scanning transmission electron microscopy. The contamination layer could be removed by high-temperature predeposition oxygen plasma cleaning.

  11. Distribution of hydrogen peroxide-dependent reaction in a gelatin sample irradiated by carbon ion beam.

    PubMed

    Matsumoto, Ken-ichiro; Aoki, Ichio; Nakanishi, Ikuo; Matsumoto, Atsuko; Nyui, Minako; Endo, Kazutoyo; Anzai, Kazunori

    2010-01-01

    We investigated the amount and distribution of hydrogen peroxide (H(2)O(2)) generated in a solid gelatin sample irradiated by heavy ion (carbon) beam. We irradiated the gelatin sample, which contained a nitroxyl radical (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, TEMPOL), with a 290-MeV/nucleon carbon beam (~128 Gy). To verify the distribution of H(2)O(2) generation in the irradiated sample, we employed both electron paramagnetic resonance (EPR) spectroscopic and magnetic resonance (MR) imaging methods based on H(2)O(2)-dependent paramagnetic loss of TEMPOL. We obtained a distribution profile of the H(2)O(2)-dependent reaction in the gelatin sample when we irradiated gelatin samples with carbon beams with several different linear energy transfer (LET) values. Because the profiles of oxygen consumption in the gelatin sample measured by L-band EPR oxymetry and of the H(2)O(2)-dependent reaction have almost the same shape, the profile of the H(2)O(2)-dependent reaction can be used as an estimation of the profile of the generation of H(2)O(2). The H(2)O(2) profile in one intact gelatin sample scanned by 7-tesla MR imaging showed a similar shape as a result of the EPR experiment. We obtained several hundreds of micromolars of H(2)O(2) generated in a gelatin sample irradiated by carbon beam when 200 Gy was given at the surface of the sample. H(2)O(2) distribution was almost flat, with only a slight peak just before the end of the beam.

  12. Optical and Scratch Resistant Properties of Diamondlike Carbon Films Deposited with Single and Dual Ion Beams

    NASA Technical Reports Server (NTRS)

    Kussmaul, Michael T.; Bogdanski, Michael S.; Banks, Bruce A.; Mirtich, Michael J.

    1993-01-01

    Amorphous diamond-like carbon (DLC) films were deposited using both single and dual ion beam techniques utilizing filament and hollow cathode ion sources. Continuous DLC films up to 3000 A thick were deposited on fused quartz plates. Ion beam process parameters were varied in an effort to create hard, clear films. Total DLC film absorption over visible wavelengths was obtained using a Perkin-Elmer spectrophotometer. An ellipsometer, with an Ar-He laser (wavelength 6328 A) was used to determine index of refraction for the DLC films. Scratch resistance, frictional, and adherence properties were determined for select films. Applications for these films range from military to the ophthalmic industries.

  13. Optical and scratch resistant properties of diamondlike carbon films deposited with single and dual ion beams

    NASA Technical Reports Server (NTRS)

    Kussmaul, Michael T.; Bogdanski, Michael S.; Banks, Bruce A.; Mirtich, Michael J.

    1993-01-01

    Amorphous diamondlike carbon (DLC) films were deposited using both single and dual ion beam techniques utilizing filament and hollow cathode ion sources. Continuous DLC films up to 3000 A thick were deposited on fused quartz plates. Ion beam process parameters were varied in an effort to create hard, clear films. Total DLC film absorption over visible wavelengths was obtained using a Perkin-Elmer spectrophotometer. An ellipsometer, with an Ar-He laser (wavelength 6328 A) was used to determine index of refraction for the DLC films. Scratch resistance and frictional and adherence properties were determined for select films. Applications for these films range from military to the ophthalmic industries.

  14. Experimental study of the water-to-air stopping power ratio of monoenergetic carbon ion beams for particle therapy.

    PubMed

    Sánchez-Parcerisa, D; Gemmel, A; Jäkel, O; Parodi, K; Rietzel, E

    2012-06-01

    Reference dosimetry with ionization chambers requires a number of chamber-specific and beam-specific calibration factors. For carbon ion beams, IAEA report TRS-398 yields a total uncertainty of 3% in the determination of the absorbed dose to water, for which the biggest contribution arises from the water-to-air stopping power ratio (s(w, air)), with an uncertainty of 2%. The variation of (s(w, air)) along the treatment field has been studied in several Monte Carlo works presented over the last few years. Their results were, in all cases, strongly dependent on the choice of mean ionization potentials (I-values) for air and water. A smaller dependence of (s(w, air)) with penetration depth was observed. Since a consensus on I(w, air) and I(air) has not yet been reached, the validity of such studies for clinical use cannot be assessed independently. Our approach is based on a direct experimental measurement of water-equivalent thicknesses of different air gaps at different beam energies. A theoretical expression describing the variation of the stopping power ratio with kinetic energy, s(w,air)(E), was derived from the Bethe-Bloch formula and fit to the measured data, yielding a coherent pair of I(w) and I(air) values with I(air)/I(w) = 1.157 ± 0.023. Additionally, the data from five different beam energies were combined in an average value of s(w,air) = 1.132 ± 0.003 (statistical) ± 0.003 (variation over energy range), valid for monoenergetic carbon ion beams at the plateau area of the depth dose distribution. A detailed uncertainty analysis was performed on the data, in order to assess the limitations of the method, yielding an overall standard uncertainty below 1% in s(w,air)(E). Therefore, when properly combined with the appropriate models for the fragment spectra, our experimental work can contribute to narrow the uncertainty margins currently in use in absorbed dose to water determination for dosimetry of carbon ion beam radiotherapy.

  15. Experimental study of the water-to-air stopping power ratio of monoenergetic carbon ion beams for particle therapy

    NASA Astrophysics Data System (ADS)

    Sánchez-Parcerisa, D.; Gemmel, A.; Jäkel, O.; Parodi, K.; Rietzel, E.

    2012-06-01

    Reference dosimetry with ionization chambers requires a number of chamber-specific and beam-specific calibration factors. For carbon ion beams, IAEA report TRS-398 yields a total uncertainty of 3% in the determination of the absorbed dose to water, for which the biggest contribution arises from the water-to-air stopping power ratio (sw, air), with an uncertainty of 2%. The variation of (sw, air) along the treatment field has been studied in several Monte Carlo works presented over the last few years. Their results were, in all cases, strongly dependent on the choice of mean ionization potentials (I-values) for air and water. A smaller dependence of (sw, air) with penetration depth was observed. Since a consensus on Iw, air and Iair has not yet been reached, the validity of such studies for clinical use cannot be assessed independently. Our approach is based on a direct experimental measurement of water-equivalent thicknesses of different air gaps at different beam energies. A theoretical expression describing the variation of the stopping power ratio with kinetic energy, sw,air(E), was derived from the Bethe-Bloch formula and fit to the measured data, yielding a coherent pair of Iw and Iair values with Iair/Iw = 1.157 ± 0.023. Additionally, the data from five different beam energies were combined in an average value of sw,air = 1.132 ± 0.003 (statistical) ± 0.003 (variation over energy range), valid for monoenergetic carbon ion beams at the plateau area of the depth dose distribution. A detailed uncertainty analysis was performed on the data, in order to assess the limitations of the method, yielding an overall standard uncertainty below 1% in sw,air(E). Therefore, when properly combined with the appropriate models for the fragment spectra, our experimental work can contribute to narrow the uncertainty margins currently in use in absorbed dose to water determination for dosimetry of carbon ion beam radiotherapy.

  16. In silico carbon molecular beam epitaxial growth of graphene on the h-BN substrate: carbon source effect on van der Waals epitaxy.

    PubMed

    Lee, Jonghoon; Varshney, Vikas; Park, Jeongho; Farmer, Barry L; Roy, Ajit K

    2016-05-01

    Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon molecular beam epitaxy (CMBE) techniques using solid carbon sublimation have reported relatively poor quality of the graphene. In this article, the CMBE growth of graphene on the h-BN substrate is numerically studied in order to identify the effect of the carbon source on the quality of the graphene film. The carbon molecular beam generated by the sublimation of solid carbon source materials such as graphite and glassy carbon is mostly composed of atomic carbon, carbon dimers and carbon trimers. Therefore, the graphene film growth becomes a complex process involving various deposition characteristics of a multitude of carbon entities. Based on the study of surface adsorption and film growth characteristics of these three major carbon entities comprising graphite vapour, we report that carbon trimers convey strong traits of vdW epitaxy prone to high quality graphene growth, while atomic carbon deposition is a surface-reaction limited process accompanied by strong chemisorption. The vdW epitaxial behaviour of carbon trimers is found to be substantial enough to nucleate and develop into graphene like planar films within a nanosecond of high flux growth simulation, while reactive atomic carbons tend to impair the structural integrity of the crystalline h-BN substrate upon deposition to form an amorphous interface between the substrate and the growing carbon film. The content of reactive atomic carbons in the molecular beam is suspected to be the primary cause of low quality graphene reported in the literature. A possible optimization of the molecular beam composition towards the synthesis of better quality graphene films is suggested.

  17. In silico carbon molecular beam epitaxial growth of graphene on the h-BN substrate: carbon source effect on van der Waals epitaxy.

    PubMed

    Lee, Jonghoon; Varshney, Vikas; Park, Jeongho; Farmer, Barry L; Roy, Ajit K

    2016-05-01

    Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon molecular beam epitaxy (CMBE) techniques using solid carbon sublimation have reported relatively poor quality of the graphene. In this article, the CMBE growth of graphene on the h-BN substrate is numerically studied in order to identify the effect of the carbon source on the quality of the graphene film. The carbon molecular beam generated by the sublimation of solid carbon source materials such as graphite and glassy carbon is mostly composed of atomic carbon, carbon dimers and carbon trimers. Therefore, the graphene film growth becomes a complex process involving various deposition characteristics of a multitude of carbon entities. Based on the study of surface adsorption and film growth characteristics of these three major carbon entities comprising graphite vapour, we report that carbon trimers convey strong traits of vdW epitaxy prone to high quality graphene growth, while atomic carbon deposition is a surface-reaction limited process accompanied by strong chemisorption. The vdW epitaxial behaviour of carbon trimers is found to be substantial enough to nucleate and develop into graphene like planar films within a nanosecond of high flux growth simulation, while reactive atomic carbons tend to impair the structural integrity of the crystalline h-BN substrate upon deposition to form an amorphous interface between the substrate and the growing carbon film. The content of reactive atomic carbons in the molecular beam is suspected to be the primary cause of low quality graphene reported in the literature. A possible optimization of the molecular beam composition towards the synthesis of better quality graphene films is suggested. PMID:27108606

  18. Formation of Carbonized Polystyrene Sphere/hemisphere Shell Arrays by Ion Beam Irradiation and Subsequent Annealing or Chloroform Treatment

    NASA Astrophysics Data System (ADS)

    Song, Xianyin; Dai, Zhigao; Xiao, Xiangheng; Li, Wenqing; Zheng, Xudong; Shang, Xunzhong; Zhang, Xiaolei; Cai, Guangxu; Wu, Wei; Meng, Fanli; Jiang, Changzhong

    2015-12-01

    Heat-resistant two-dimensional (2D) sphere/hemisphere shell array is significant for the fabrication of novel nanostructures. Here large-area, well-ordered arrays of carbonized polystyrene (PS) hollow sphere/hemisphere with controlled size and morphology are prepared by combining the nanosphere self-assembly, kV Ag ion beam modification, and subsequent annealing or chloroform treatment. Potential mechanisms for the formation and evolution of the heat-resistant carbonized PS spherical shell with increasing ion fluence and energy are discussed. Combined with noble metal or semiconductor, these modified PS sphere arrays should open up new possibilities for high-performance nanoscale optical sensors or photoelectric devices.

  19. Formation of Carbonized Polystyrene Sphere/hemisphere Shell Arrays by Ion Beam Irradiation and Subsequent Annealing or Chloroform Treatment

    PubMed Central

    Song, Xianyin; Dai, Zhigao; Xiao, Xiangheng; Li, Wenqing; Zheng, Xudong; Shang, Xunzhong; Zhang, Xiaolei; Cai, Guangxu; Wu, Wei; Meng, Fanli; Jiang, Changzhong

    2015-01-01

    Heat-resistant two-dimensional (2D) sphere/hemisphere shell array is significant for the fabrication of novel nanostructures. Here large-area, well-ordered arrays of carbonized polystyrene (PS) hollow sphere/hemisphere with controlled size and morphology are prepared by combining the nanosphere self-assembly, kV Ag ion beam modification, and subsequent annealing or chloroform treatment. Potential mechanisms for the formation and evolution of the heat-resistant carbonized PS spherical shell with increasing ion fluence and energy are discussed. Combined with noble metal or semiconductor, these modified PS sphere arrays should open up new possibilities for high-performance nanoscale optical sensors or photoelectric devices. PMID:26640125

  20. Formation of Carbonized Polystyrene Sphere/hemisphere Shell Arrays by Ion Beam Irradiation and Subsequent Annealing or Chloroform Treatment.

    PubMed

    Song, Xianyin; Dai, Zhigao; Xiao, Xiangheng; Li, Wenqing; Zheng, Xudong; Shang, Xunzhong; Zhang, Xiaolei; Cai, Guangxu; Wu, Wei; Meng, Fanli; Jiang, Changzhong

    2015-01-01

    Heat-resistant two-dimensional (2D) sphere/hemisphere shell array is significant for the fabrication of novel nanostructures. Here large-area, well-ordered arrays of carbonized polystyrene (PS) hollow sphere/hemisphere with controlled size and morphology are prepared by combining the nanosphere self-assembly, kV Ag ion beam modification, and subsequent annealing or chloroform treatment. Potential mechanisms for the formation and evolution of the heat-resistant carbonized PS spherical shell with increasing ion fluence and energy are discussed. Combined with noble metal or semiconductor, these modified PS sphere arrays should open up new possibilities for high-performance nanoscale optical sensors or photoelectric devices. PMID:26640125

  1. Modeling and simulation performance of sucker rod beam pump

    SciTech Connect

    Aditsania, Annisa; Rahmawati, Silvy Dewi Sukarno, Pudjo; Soewono, Edy

    2015-09-30

    Artificial lift is a mechanism to lift hydrocarbon, generally petroleum, from a well to surface. This is used in the case that the natural pressure from the reservoir has significantly decreased. Sucker rod beam pumping is a method of artificial lift. Sucker rod beam pump is modeled in this research as a function of geometry of the surface part, the size of sucker rod string, and fluid properties. Besides its length, sucker rod string also classified into tapered and un-tapered. At the beginning of this research, for easy modeling, the sucker rod string was assumed as un-tapered. The assumption proved non-realistic to use. Therefore, the tapered sucker rod string modeling needs building. The numerical solution of this sucker rod beam pump model is computed using finite difference method. The numerical result shows that the peak of polished rod load for sucker rod beam pump unit C-456-D-256-120, for non-tapered sucker rod string is 38504.2 lb, while for tapered rod string is 25723.3 lb. For that reason, to avoid the sucker rod string breaks due to the overload, the use of tapered sucker rod beam string is suggested in this research.

  2. Modeling and simulation performance of sucker rod beam pump

    NASA Astrophysics Data System (ADS)

    Aditsania, Annisa; Rahmawati, Silvy Dewi; Sukarno, Pudjo; Soewono, Edy

    2015-09-01

    Artificial lift is a mechanism to lift hydrocarbon, generally petroleum, from a well to surface. This is used in the case that the natural pressure from the reservoir has significantly decreased. Sucker rod beam pumping is a method of artificial lift. Sucker rod beam pump is modeled in this research as a function of geometry of the surface part, the size of sucker rod string, and fluid properties. Besides its length, sucker rod string also classified into tapered and un-tapered. At the beginning of this research, for easy modeling, the sucker rod string was assumed as un-tapered. The assumption proved non-realistic to use. Therefore, the tapered sucker rod string modeling needs building. The numerical solution of this sucker rod beam pump model is computed using finite difference method. The numerical result shows that the peak of polished rod load for sucker rod beam pump unit C-456-D-256-120, for non-tapered sucker rod string is 38504.2 lb, while for tapered rod string is 25723.3 lb. For that reason, to avoid the sucker rod string breaks due to the overload, the use of tapered sucker rod beam string is suggested in this research.

  3. Performance of a High Resolution Cavity Beam Position Monitor System

    SciTech Connect

    Walston, Sean; Boogert, Stewart; Chung, Carl; Fitsos, Joe; Frisch, Joe; Gronberg, Jeff; Hayano, Hitoshi; Honda, Yosuke; Kolomensky, Yury; Lyapin, Alexey; Malton, Stephen; May, Justin; McCormick, Douglas; Meller, Robert; Miller, David John; Orimoto, Toyoko; Ross, Marc; Slater, Mark; Smith, Steve; Smith, Tonee; Terunuma, Nobuhiro; /Fermilab /UC, Berkeley /LBL, Berkeley /Cambridge U. /Royal Holloway, U. of London /Cornell U., LNS /LLNL, Livermore /University Coll. London /SLAC /Caltech /KEK, Tsukuba

    2007-06-08

    It has been estimated that an RF cavity Beam Position Monitor (BPM) could provide a position measurement resolution of less than one nanometer. We have developed a high resolution cavity BPM and associated electronics. A triplet comprised of these BPMs was installed in the extraction line of the Accelerator Test Facility (ATF) at the High Energy Accelerator Research Organization (KEK) for testing with its ultra-low emittance beam. The three BPMs were each rigidly mounted inside an alignment frame on six variable-length struts which could be used to move the BPMs in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a robust calibration algorithm which is immune to beam jitter. To date, we have demonstrated a position resolution of 15.6 nm and a tilt resolution of 2.1 {mu}rad over a dynamic range of approximately {+-} 20 {mu}m.

  4. Performance of a High Resolution Cavity Beam Position Monitor System

    SciTech Connect

    Walston, S; Boogert, S; Chung, C; Fitsos, P; Frisch, J; Gronberg, J; Hayano, H; Honda, Y; Kolomensky, Y; Lyapin, A; Malton, S; May, J; McCormick, D; Meller, R; Miller, D; Orimoto, T; Ross, M; Slater, M; Smith, S; Smith, T; Terunuma, N; Thomson, M; Urakawa, J; Vogel, V; Ward, D; White, G

    2006-12-18

    It has been estimated that an RF cavity Beam Position Monitor (BPM) could provide a position measurement resolution of less than one nanometer. We have developed a high resolution cavity BPM and associated electronics. A triplet comprised of these BPMs was installed in the extraction line of the Accelerator Test Facility (ATF) at the High Energy Accelerator Research Organization (KEK) for testing with its ultra-low emittance beam. The three BPMs were each rigidly mounted inside an alignment frame on six variable-length struts which could be used to move the BPMs in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a robust calibration algorithm which is immune to beam jitter. To date, we have demonstrated a position resolution of 15.6 nm and a tilt resolution of 2.1 {micro}rad over a dynamic range of approximately {+-} 20 {micro}m.

  5. Demonstrated Efficient Quasi-Monoenergetic Carbon-Ion Beams Approaching Fast Ignition (FI) Requirements

    NASA Astrophysics Data System (ADS)

    Fernández, Juan C.; Palaniyappan, S.; Huang, C.; Gautier, D. C.; Santiago, M.

    2015-11-01

    Using massive computer simulations of relativistic laser-plasma interactions, we have identified a self-organizing scheme that exploits persisting self-generated plasma electric (~TV/m) and magnetic (~104 Tesla) fields to reduce the ion energy spread of intense laser-driven ion beams after the laser exits the plasma. Consistent with the scheme, we have demonstrated on the LANL Trident laser carbon-ion beams with narrow spectral peaks at 220 MeV, with high conversion efficiency (~ 5%). These parameters are within a factor of 2 of FI requirements. The remaining gap may be bridged by increasing the laser intensity by a factor of 4, according to our data. We also discuss how this beam may be focused, to address the remaining requirement for FI, besides the total laser energy. This work is sponsored by the LANL LDRD Program.

  6. Electron beam induced current measurements on single-walled carbon nanotube devices.

    PubMed

    Park, J K; Ahn, Y H; Park, Ji-Yong; Lee, Soonil; Park, K H

    2010-03-19

    We report on electron beam induced current (EBIC) from individual carbon nanotubes (CNTs) which are in contact with metal electrodes. The EBIC signals originate from the diffusion of excess carriers induced by the electron beam bombardment. The EBIC image enables us to locate the individual CNTs efficiently. From the polarity of the EBIC signals we can identify the electrical contacts to the metal electrodes. More importantly, we demonstrate that the EBIC can be used to characterize the local electrical properties of CNT-based devices, such as asymmetry in metal contacts and the presence of defects. EBIC is also observed regardless of the presence of insulating surfaces, indicating that the EBIC is a result of the direct interaction between the CNTs and the electron beams.

  7. Antimony-assisted carbonization of Si(111) with solid source molecular beam epitaxy

    SciTech Connect

    Hackley, Justin; Richardson, Christopher J. K.; Sarney, Wendy L.

    2013-11-15

    The carbonization of an antimony-terminated Si (111) surface in a solid source molecular beam epitaxy system is presented. Reflection high-energy electron diffraction, atomic force microscopy, x-ray photoelectron spectroscopy, and cross-sectional transmission electron microscopy are used to characterize samples grown with and without antimony termination. It is shown that the antimony-terminated surface promotes the formation of thin, smooth and continuous SiC films at a relatively low temperature of 800 °C.

  8. High Performance Multifunctional Carbon Nanotube Fibers

    NASA Astrophysics Data System (ADS)

    Dalton, Alan; Collins, Steve; Munoz, Edgar; Razal, Joselito; Ebron, Von; Ferraris, John; Baughman, Ray

    2003-03-01

    Exploiting the extraordinary properties of carbon nanotubes has remained somewhat elusive due to the inability to process the as produced insoluble soot into functional macroscopic assemblies. To this end we have developed a simple but effective method to produce continuous, homogeneous fibers containing carbon nanotubes having as-spun mechanical properties that compare very favorably to recognized synthetic and natural "super fibers" such as Kevlar and spider silk. By using novel spinning apparatus, spinning solutions, and spinning coagulants, we have spun nanotube fibers having record lengths, record tensile strengths, and having an energy-to-break (toughness) higher than any material that we have found. As an example of the potential multi-functionalities of our fibers, we have fabricated fiber supercapacitors, which we weave into textiles.

  9. Performance Studies of the Vibration Wire Monitor on the Test Stand with Low Energy Electron Beam

    NASA Astrophysics Data System (ADS)

    Okabe, Kota; Yoshimoto, Masahiro; Kinsho, Michikazu

    In the high intensity proton accelerator as the Japan Proton Accelerator Research Complex (J-PARC) accelerators, serious radiation and residual dose is induced by a small beam loss such a beam halo. Therefore, diagnostics of the beam halo formation is one of the most important issues to control the beam loss. For the beam halo monitor, the vibration wire monitor (VWM) has a potential for investigating the beam halo and weak beam scanning. The VWM has a wide dynamic range, high resolution and the VWM is not susceptible to secondary electrons and electric noises. We have studied the VWM features as a new beam-halo monitor on the test stand with low energy electron gun. The frequency shift of the irradiated vibration wire was confirmed about wire material and the electron beam profile measured by using the VWM was consistent with the results of the Faraday cup measurement. Also we calculated a temperature distribution on the vibration wire which is irradiated by the electron beam with the numerical simulation. The simulations have been fairly successful in reproducing the transient of the irradiated vibration wire frequency measured by test stand experiments. In this paper, we will report a result of performance evaluation for the VWM on the test stands and discuss the VWM for beam halo diagnostic

  10. Characterization of polyacrylonitrile based carbon nanofiber mats via electron beam processing.

    PubMed

    Kim, Du-Yeong; Shin, Hye-Kyoung; Jeun, Joon-Pyo; Kim, Hyun-Bin; Oh, Seung-Hwan; Kang, Phil-Hyun

    2012-07-01

    The aim of this study was to evaluate the ability of electron beam irradiation to drive stabilization reactions within PAN nanofiber mats to obtain carbon nanofiber mats. PAN nanofiber mats with fiber diameters of 300-400 nm were prepared via an electrospinning method. Electrospun PAN nanofiber mats were stabilized by electron beam irradiation with various doses up to 5,000 kGy. Using the irradiation-stabilized PAN nanofiber mats, carbon nanofibers were obtained by pyrolysis in a tube furnace for 1 h at 1,000 degrees C under an N2 atmosphere. FT-IR analysis indicated that the transformation of C[triple bond]N groups to C==N groups was accelerated by electron beam stabilization. The thermal behavior of the PAN nanofiber mats was studied using DSC and TGA. DSC thermograms showed that the peak temperatures of the exothermic reactions were found to decrease with increasing electron beam irradiation doses. Irradiation-stabilized PAN nanofiber mats were not observed to dramatically decrease in weight between 290 degrees C and 320 degrees C, an observation presumed to be related to cyclization. The char yields of PAN were found to increase with increasing irradiation doses. PMID:22966719

  11. Performance of MACACO Compton telescope for ion-beam therapy monitoring: first test with proton beams.

    PubMed

    Solevi, Paola; Muñoz, Enrique; Solaz, Carles; Trovato, Marco; Dendooven, Peter; Gillam, John E; Lacasta, Carlos; Oliver, Josep F; Rafecas, Magdalena; Torres-Espallardo, Irene; Llosá, Gabriela

    2016-07-21

    In order to exploit the advantages of ion-beam therapy in a clinical setting, delivery verification techniques are necessary to detect deviations from the planned treatment. Efforts are currently oriented towards the development of devices for real-time range monitoring. Among the different detector concepts proposed, Compton cameras are employed to detect prompt gammas and represent a valid candidate for real-time range verification. We present the first on-beam test of MACACO, a Compton telescope (multi-layer Compton camera) based on lanthanum bromide crystals and silicon photo-multipliers. The Compton telescope was first characterized through measurements and Monte Carlo simulations. The detector linearity was measured employing (22)Na and Am-Be sources, obtaining about 10% deviation from linearity at 3.44 MeV. A spectral image reconstruction algorithm was tested on synthetic data. Point-like sources emitting gamma rays with energy between 2 and 7 MeV were reconstructed with 3-5 mm resolution. The two-layer Compton telescope was employed to measure radiation emitted from a beam of 150 MeV protons impinging on a cylindrical PMMA target. Bragg-peak shifts were achieved via adjustment of the PMMA target location and the resulting measurements used during image reconstruction. Reconstructed Bragg peak profiles proved sufficient to observe peak-location differences within 10 mm demonstrating the potential of the MACACO Compton Telescope as a monitoring device for ion-beam therapy. PMID:27352107

  12. Performance of MACACO Compton telescope for ion-beam therapy monitoring: first test with proton beams

    NASA Astrophysics Data System (ADS)

    Solevi, Paola; Muñoz, Enrique; Solaz, Carles; Trovato, Marco; Dendooven, Peter; Gillam, John E.; Lacasta, Carlos; Oliver, Josep F.; Rafecas, Magdalena; Torres-Espallardo, Irene; Llosá, Gabriela

    2016-07-01

    In order to exploit the advantages of ion-beam therapy in a clinical setting, delivery verification techniques are necessary to detect deviations from the planned treatment. Efforts are currently oriented towards the development of devices for real-time range monitoring. Among the different detector concepts proposed, Compton cameras are employed to detect prompt gammas and represent a valid candidate for real-time range verification. We present the first on-beam test of MACACO, a Compton telescope (multi-layer Compton camera) based on lanthanum bromide crystals and silicon photo-multipliers. The Compton telescope was first characterized through measurements and Monte Carlo simulations. The detector linearity was measured employing 22Na and Am-Be sources, obtaining about 10% deviation from linearity at 3.44 MeV. A spectral image reconstruction algorithm was tested on synthetic data. Point-like sources emitting gamma rays with energy between 2 and 7 MeV were reconstructed with 3-5 mm resolution. The two-layer Compton telescope was employed to measure radiation emitted from a beam of 150 MeV protons impinging on a cylindrical PMMA target. Bragg-peak shifts were achieved via adjustment of the PMMA target location and the resulting measurements used during image reconstruction. Reconstructed Bragg peak profiles proved sufficient to observe peak-location differences within 10 mm demonstrating the potential of the MACACO Compton Telescope as a monitoring device for ion-beam therapy.

  13. Performance of MACACO Compton telescope for ion-beam therapy monitoring: first test with proton beams

    NASA Astrophysics Data System (ADS)

    Solevi, Paola; Muñoz, Enrique; Solaz, Carles; Trovato, Marco; Dendooven, Peter; Gillam, John E.; Lacasta, Carlos; Oliver, Josep F.; Rafecas, Magdalena; Torres-Espallardo, Irene; Llosá, Gabriela

    2016-07-01

    In order to exploit the advantages of ion-beam therapy in a clinical setting, delivery verification techniques are necessary to detect deviations from the planned treatment. Efforts are currently oriented towards the development of devices for real-time range monitoring. Among the different detector concepts proposed, Compton cameras are employed to detect prompt gammas and represent a valid candidate for real-time range verification. We present the first on-beam test of MACACO, a Compton telescope (multi-layer Compton camera) based on lanthanum bromide crystals and silicon photo-multipliers. The Compton telescope was first characterized through measurements and Monte Carlo simulations. The detector linearity was measured employing 22Na and Am-Be sources, obtaining about 10% deviation from linearity at 3.44 MeV. A spectral image reconstruction algorithm was tested on synthetic data. Point-like sources emitting gamma rays with energy between 2 and 7 MeV were reconstructed with 3–5 mm resolution. The two-layer Compton telescope was employed to measure radiation emitted from a beam of 150 MeV protons impinging on a cylindrical PMMA target. Bragg-peak shifts were achieved via adjustment of the PMMA target location and the resulting measurements used during image reconstruction. Reconstructed Bragg peak profiles proved sufficient to observe peak-location differences within 10 mm demonstrating the potential of the MACACO Compton Telescope as a monitoring device for ion-beam therapy.

  14. Performance of MACACO Compton telescope for ion-beam therapy monitoring: first test with proton beams.

    PubMed

    Solevi, Paola; Muñoz, Enrique; Solaz, Carles; Trovato, Marco; Dendooven, Peter; Gillam, John E; Lacasta, Carlos; Oliver, Josep F; Rafecas, Magdalena; Torres-Espallardo, Irene; Llosá, Gabriela

    2016-07-21

    In order to exploit the advantages of ion-beam therapy in a clinical setting, delivery verification techniques are necessary to detect deviations from the planned treatment. Efforts are currently oriented towards the development of devices for real-time range monitoring. Among the different detector concepts proposed, Compton cameras are employed to detect prompt gammas and represent a valid candidate for real-time range verification. We present the first on-beam test of MACACO, a Compton telescope (multi-layer Compton camera) based on lanthanum bromide crystals and silicon photo-multipliers. The Compton telescope was first characterized through measurements and Monte Carlo simulations. The detector linearity was measured employing (22)Na and Am-Be sources, obtaining about 10% deviation from linearity at 3.44 MeV. A spectral image reconstruction algorithm was tested on synthetic data. Point-like sources emitting gamma rays with energy between 2 and 7 MeV were reconstructed with 3-5 mm resolution. The two-layer Compton telescope was employed to measure radiation emitted from a beam of 150 MeV protons impinging on a cylindrical PMMA target. Bragg-peak shifts were achieved via adjustment of the PMMA target location and the resulting measurements used during image reconstruction. Reconstructed Bragg peak profiles proved sufficient to observe peak-location differences within 10 mm demonstrating the potential of the MACACO Compton Telescope as a monitoring device for ion-beam therapy.

  15. The atomistic mechanism of carbon nanotube cutting catalyzed by nickel under an electron beam

    NASA Astrophysics Data System (ADS)

    Lebedeva, Irina V.; Chamberlain, Thomas W.; Popov, Andrey M.; Knizhnik, Andrey A.; Zoberbier, Thilo; Biskupek, Johannes; Kaiser, Ute; Khlobystov, Andrei N.

    2014-11-01

    The cutting of single-walled carbon nanotubes by an 80 keV electron beam catalyzed by nickel clusters is imaged in situ using aberration-corrected high-resolution transmission electron microscopy. Extensive molecular dynamics simulations within the CompuTEM approach provide insight into the mechanism of this process and demonstrate that the combination of irradiation and the nickel catalyst is crucial for the cutting process to take place. The atomistic mechanism of cutting is revealed by a detailed analysis of irradiation-induced reactions of bond reorganization and atom ejection in the vicinity of the nickel cluster, showing a highly complex interplay of different chemical transformations catalysed by the metal cluster. One of the most prevalent pathways includes three consecutive stages: formation of polyyne carbon chains from the carbon nanotube, dissociation of the carbon chains into single and pairs of adatoms adsorbed on the nickel cluster, and ejection of these adatoms leading to the cutting of the nanotube. Significant variations in the atom ejection rate are discovered depending on the process stage and nanotube diameter. The revealed mechanism and kinetic characteristics of the cutting process provide fundamental knowledge for the development of new methodologies for control and manipulation of carbon structures at the nanoscale.The cutting of single-walled carbon nanotubes by an 80 keV electron beam catalyzed by nickel clusters is imaged in situ using aberration-corrected high-resolution transmission electron microscopy. Extensive molecular dynamics simulations within the CompuTEM approach provide insight into the mechanism of this process and demonstrate that the combination of irradiation and the nickel catalyst is crucial for the cutting process to take place. The atomistic mechanism of cutting is revealed by a detailed analysis of irradiation-induced reactions of bond reorganization and atom ejection in the vicinity of the nickel cluster, showing a

  16. Carbon-ion pencil beam scanning for thoracic treatment – initiation report and dose metrics evaluation

    PubMed Central

    Karube, Masataka; Mori, Shinichiro; Tsuji, Hiroshi; Yamamoto, Naoyoshi; Nakajima, Mio; Nakagawa, Keiichi; Kamada, Tadashi

    2016-01-01

    Carbon-ion beam scanning has not previously been used for moving tumor treatments. We have commenced respiratory-gated carbon-ion radiotherapy (CIRT) in the thoracic and abdominal regions under free-breathing conditions as a clinical trial. This study aimed to investigate this treatment in the lungs in comparison with passive scattering CIRT. Five patients had thoracic tumors treated with carbon-ion scanned beams using respiratory gating. We analyzed the actual treatments and calculated passive scattering treatment plans based on the same planning CT. We evaluated tumor size until 3 months post treatment and each treatment plan regarding dose delivered to 95% of the clinical target volume (CTV-D95), mean lung dose, percentage of lung receiving at least 5 Gy (RBE) (Lung-V5), Lung-V10, Lung-V20, heart maximum dose (Dmax), esophagus Dmax, cord Dmax and skin Dmax. Obvious tumor deterioration was not observed up to 3 months post treatment. The dose evaluation metrics were similar item by item between respiratory-gated scanned CIRT and passive scattering CIRT. In conclusion, scanned beam CIRT provided treatments equivalent to passive scattering CIRT for thoracic tumors. Increased sample numbers and longer-term observation are needed. PMID:27380799

  17. Mutagenic effects of carbon ion beam irradiations on dry Lotus japonicus seeds

    NASA Astrophysics Data System (ADS)

    Luo, Shanwei; Zhou, Libin; Li, Wenjian; Du, Yan; Yu, Lixia; Feng, Hui; Mu, Jinhu; Chen, Yuze

    2016-09-01

    Carbon ion beam irradiation is a powerful method for creating mutants and has been used in crop breeding more and more. To investigate the effects of carbon ion beams on Lotus japonicus, dry seeds were irradiated by 80 MeV/u carbon ion beam at dosages of 0, 100, 200, 300, 400, 500 and 600 Gy. The germination rate, survival rate and root length of M1 populations were explored and the dose of 400 Gy was selected as the median lethal dose (LD50) for a large-scale mutant screening. Among 2472 M2 plants, 127 morphological mutants including leaf, stem, flower and fruit phenotypic variation were found, and the mutation frequency was approximately 5.14%. Inter simple sequence repeat (ISSR) assays were utilized to investigate the DNA polymorphism between seven mutants and eight plants without phenotypic variation from M2 populations. No remarkable differences were detected between these two groups, and the total polymorphic rate was 0.567%.

  18. Thermal and Mechanical Performance of a Carbon/Carbon Composite Spacecraft Radiator

    NASA Technical Reports Server (NTRS)

    Kuhn, Jonathan; Benner, Steve; Butler, Dan; Silk, Eric

    1999-01-01

    Carbon-carbon composite materials offer greater thermal efficiency, stiffness to weight ratio, tailorability, and dimensional stability than aluminum. These lightweight thermal materials could significantly reduce the overall costs associated with satellite thermal control and weight. However, the high cost and long lead-time for carbon-carbon manufacture have limited their widespread usage. Consequently, an informal partnership between government and industrial personnel called the Carbon-Carbon Spacecraft Radiator Partnership (CSRP) was created to foster carbon-carbon composite use for thermally and structurally demanding space radiator applications. The first CSRP flight opportunity is on the New Millennium Program (NMP) Earth Orbiter-1 (EO-1) spacecraft, scheduled for launch in late 1999. For EO-1, the CSRP designed and fabricated a Carbon-Carbon Radiator (CCR) with carbon-carbon facesheets and aluminum honeycomb core, which will also serve as a structural shear panel. While carbon-carbon is an ideal thermal candidate for spacecraft radiators, in practice there are technical challenges that may compromise performance. In this work, the thermal and mechanical performance of the EO-1 CCR is assessed by analysis and testing. Both then-nal and mechanical analyses were conducted to predict the radiator response to anticipated launch and on-orbit loads. The thermal model developed was based on thermal balance test conditions. The thermal analysis was performed using SINDA version 4.0. Structural finite element modeling and analysis were performed using SDRC/1-DEAS and UAI/NASTRAN, respectively. In addition, the CCR was subjected to flight qualification thermal/vacuum and vibration tests. The panel meets or exceeds the requirements for space flight and demonstrates promise for future satellite missions.

  19. Focused-Ion-Beam-Milled Carbon Nanoelectrodes for Scanning Electrochemical Microscopy

    PubMed Central

    Chen, Ran; Hu, Keke; Yu, Yun; Mirkin, Michael V.; Amemiya, Shigeru

    2016-01-01

    Nanoscale scanning electrochemical microscopy (SECM) has emerged as a powerful electrochemical method that enables the study of interfacial reactions with unprecedentedly high spatial and kinetic resolution. In this work, we develop carbon nanoprobes with high electrochemical reactivity and well-controlled size and geometry based on chemical vapor deposition of carbon in quartz nanopipets. Carbon-filled nanopipets are milled by focused ion beam (FIB) technology to yield a flat disk tip with a thin quartz sheath as confirmed by transmission electron microscopy. The extremely high electroactivity of FIB-milled carbon nanotips is quantified by enormously high standard electron-transfer rate constants of ≥10 cm/s for Ru(NH3)63+. The tip size and geometry are characterized in electrolyte solutions by SECM approach curve measurements not only to determine inner and outer tip radii of down to ~27 and ~38 nm, respectively, but also to ensure the absence of a conductive carbon layer on the outer wall. In addition, FIB-milled carbon nanotips reveal the limited conductivity of ~100 nm-thick gold films under nanoscale mass-transport conditions. Importantly, carbon nanotips must be protected from electrostatic damage to enable reliable and quantitative nanoelectrochemical measurements. PMID:27642187

  20. Focused-Ion-Beam-Milled Carbon Nanoelectrodes for Scanning Electrochemical Microscopy

    PubMed Central

    Chen, Ran; Hu, Keke; Yu, Yun; Mirkin, Michael V.; Amemiya, Shigeru

    2016-01-01

    Nanoscale scanning electrochemical microscopy (SECM) has emerged as a powerful electrochemical method that enables the study of interfacial reactions with unprecedentedly high spatial and kinetic resolution. In this work, we develop carbon nanoprobes with high electrochemical reactivity and well-controlled size and geometry based on chemical vapor deposition of carbon in quartz nanopipets. Carbon-filled nanopipets are milled by focused ion beam (FIB) technology to yield a flat disk tip with a thin quartz sheath as confirmed by transmission electron microscopy. The extremely high electroactivity of FIB-milled carbon nanotips is quantified by enormously high standard electron-transfer rate constants of ≥10 cm/s for Ru(NH3)63+. The tip size and geometry are characterized in electrolyte solutions by SECM approach curve measurements not only to determine inner and outer tip radii of down to ~27 and ~38 nm, respectively, but also to ensure the absence of a conductive carbon layer on the outer wall. In addition, FIB-milled carbon nanotips reveal the limited conductivity of ~100 nm-thick gold films under nanoscale mass-transport conditions. Importantly, carbon nanotips must be protected from electrostatic damage to enable reliable and quantitative nanoelectrochemical measurements.

  1. Phase Space Generation for Proton and Carbon Ion Beams for External Users’ Applications at the Heidelberg Ion Therapy Center

    PubMed Central

    Tessonnier, Thomas; Marcelos, Tiago; Mairani, Andrea; Brons, Stephan; Parodi, Katia

    2016-01-01

    In the field of radiation therapy, accurate and robust dose calculation is required. For this purpose, precise modeling of the irradiation system and reliable computational platforms are needed. At the Heidelberg Ion Therapy Center (HIT), the beamline has been already modeled in the FLUKA Monte Carlo (MC) code. However, this model was kept confidential for disclosure reasons and was not available for any external team. The main goal of this study was to create efficiently phase space (PS) files for proton and carbon ion beams, for all energies and foci available at HIT. PSs are representing the characteristics of each particle recorded (charge, mass, energy, coordinates, direction cosines, generation) at a certain position along the beam path. In order to achieve this goal, keeping a reasonable data size but maintaining the requested accuracy for the calculation, we developed a new approach of beam PS generation with the MC code FLUKA. The generated PSs were obtained using an infinitely narrow beam and recording the desired quantities after the last element of the beamline, with a discrimination of primaries or secondaries. In this way, a unique PS can be used for each energy to accommodate the different foci by combining the narrow-beam scenario with a random sampling of its theoretical Gaussian beam in vacuum. PS can also reproduce the different patterns from the delivery system, when properly combined with the beam scanning information. MC simulations using PS have been compared to simulations, including the full beamline geometry and have been found in very good agreement for several cases (depth dose distributions, lateral dose profiles), with relative dose differences below 0.5%. This approach has also been compared with measured data of ion beams with different energies and foci, resulting in a very satisfactory agreement. Hence, the proposed approach was able to fulfill the different requirements and has demonstrated its capability for application to

  2. Phase Space Generation for Proton and Carbon Ion Beams for External Users' Applications at the Heidelberg Ion Therapy Center.

    PubMed

    Tessonnier, Thomas; Marcelos, Tiago; Mairani, Andrea; Brons, Stephan; Parodi, Katia

    2015-01-01

    In the field of radiation therapy, accurate and robust dose calculation is required. For this purpose, precise modeling of the irradiation system and reliable computational platforms are needed. At the Heidelberg Ion Therapy Center (HIT), the beamline has been already modeled in the FLUKA Monte Carlo (MC) code. However, this model was kept confidential for disclosure reasons and was not available for any external team. The main goal of this study was to create efficiently phase space (PS) files for proton and carbon ion beams, for all energies and foci available at HIT. PSs are representing the characteristics of each particle recorded (charge, mass, energy, coordinates, direction cosines, generation) at a certain position along the beam path. In order to achieve this goal, keeping a reasonable data size but maintaining the requested accuracy for the calculation, we developed a new approach of beam PS generation with the MC code FLUKA. The generated PSs were obtained using an infinitely narrow beam and recording the desired quantities after the last element of the beamline, with a discrimination of primaries or secondaries. In this way, a unique PS can be used for each energy to accommodate the different foci by combining the narrow-beam scenario with a random sampling of its theoretical Gaussian beam in vacuum. PS can also reproduce the different patterns from the delivery system, when properly combined with the beam scanning information. MC simulations using PS have been compared to simulations, including the full beamline geometry and have been found in very good agreement for several cases (depth dose distributions, lateral dose profiles), with relative dose differences below 0.5%. This approach has also been compared with measured data of ion beams with different energies and foci, resulting in a very satisfactory agreement. Hence, the proposed approach was able to fulfill the different requirements and has demonstrated its capability for application to

  3. Low-Z gas stripper as an alternative to carbon foils for the acceleration of high-power uranium beams

    NASA Astrophysics Data System (ADS)

    Okuno, H.; Fukunishi, N.; Goto, A.; Hasebe, H.; Imao, H.; Kamigaito, O.; Kase, M.; Kuboki, H.; Yano, Y.; Yokouchi, S.; Hershcovitch, A.

    2011-03-01

    The RIKEN accelerator complex started feeding the next-generation exotic beam facility radioisotope beam factory (RIBF) with heavy-ion beams from 2007 after the successful commissioning of RIBF at the end of 2006. Many improvements made from 2007 to 2010 were instrumental in increasing the intensity of various heavy-ion beams. However, the available beam intensity of very heavy ion beams, especially uranium beams, is far below our goal of 1pμA (6×1012particles/s). In order to achieve this goal, upgrade programs are already in progress; the programs include the construction of a new 28-GHz superconducting electron cyclotron resonance ion source and a new injector linac. However, the most serious problem, that of a charge stripper for high-power uranium beams, still remains unsolved, despite extensive research and development work using large foils mounted on a rotating cylinder and a N2 gas stripper. A gas stripper is free from problems related to lifetime, though the equilibrium charge state in this stripper is considerably lower than that in a carbon foil, owing to the absence of the density effect. Nevertheless, the merits of gas strippers motivated us to develop a low-Z gas stripper to achieve a higher equilibrium charge state even in gases. We measured the electron-loss and electron-capture cross sections of uranium ions in He gas as a function of their charge state at 11, 14, and 15MeV/nucleon. The equilibrium charge states extracted from the intersection of the lines of the two cross sections were promisingly higher than those in N2 gas by more than 10. Simple simulations of charge development along the stripper thickness were performed by assuming the measured cross sections. The simulation results show that about 1mg/cm2 of He gas should be accumulated to achieve a charge state higher than that of N2 gas, notwithstanding the difficulty in accumulation of this helium amount owing to its fast dispersion. However, we now believe that the following two

  4. Focused-electron-beam-induced processing (FEBIP) for emerging applications in carbon nanoelectronics

    NASA Astrophysics Data System (ADS)

    Fedorov, Andrei G.; Kim, Songkil; Henry, Mathias; Kulkarni, Dhaval; Tsukruk, Vladimir V.

    2014-12-01

    Focused-electron-beam-induced processing (FEBIP), a resist-free additive nanomanufacturing technique, is an actively researched method for "direct-write" processing of a wide range of structural and functional nanomaterials, with high degree of spatial and time-domain control. This article attempts to critically assess the FEBIP capabilities and unique value proposition in the context of processing of electronics materials, with a particular emphasis on emerging carbon (i.e., based on graphene and carbon nanotubes) devices and interconnect structures. One of the major hurdles in advancing the carbon-based electronic materials and device fabrication is a disjoint nature of various processing steps involved in making a functional device from the precursor graphene/CNT materials. Not only this multi-step sequence severely limits the throughput and increases the cost, but also dramatically reduces the processing reproducibility and negatively impacts the quality because of possible between-the-step contamination, especially for impurity-susceptible materials such as graphene. The FEBIP provides a unique opportunity to address many challenges of carbon nanoelectronics, especially when it is employed as part of an integrated processing environment based on multiple "beams" of energetic particles, including electrons, photons, and molecules. This avenue is promising from the applications' prospective, as such a multi-functional (electron/photon/molecule beam) enables one to define shapes (patterning), form structures (deposition/etching), and modify (cleaning/doping/annealing) properties with locally resolved control on nanoscale using the same tool without ever changing the processing environment. It thus will have a direct positive impact on enhancing functionality, improving quality and reducing fabrication costs for electronic devices, based on both conventional CMOS and emerging carbon (CNT/graphene) materials.

  5. Interaction of pulsed carbon dioxide laser beams with teeth in vitro.

    PubMed

    Brune, D

    1980-08-01

    Beams of pulsed carbon dioxide lasers with energy densities of about 10, 100 or 200 J/mm2 have been applied perpendicularly to third molars in vitro for the purpose of preparing cavities or pin holes for retention. A pulsed beam with an energy density of about 10 J/mm2 produced a hole approximately 2 mm deep with a diameter of about 0.2 mm. With a beam of 100 J/mm2 the hole produced penetrated the tooth to a depth of 4 mm. Minor cracks around the hole in both enamel and dentin could be observed. Around the position where the beam entered the enamel matrix a white mineralized layer was observed, while a brown discoloration was formed around the hole in the dentin at the beam exit. With an energy density of 200 J/mm2 the formation of cracks and discoloration was very pronounced. X-ray diffraction of lased tissue revealed an apatite structure. The wall in the lased hole exhibited a Vicker hardness number similar to that of enamel.

  6. Dosimetric characterization and application of an imaging beam line with a carbon electron target for megavoltage cone beam computed tomography.

    PubMed

    Flynn, Ryan T; Hartmann, Julia; Bani-Hashemi, Ali; Nixon, Earl; Alfredo, R; Siochi, C; Pennington, Edward C; Bayouth, John E

    2009-06-01

    Imaging dose from megavoltage cone beam computed tomography (MVCBCT) can be significantly reduced without loss of image quality by using an imaging beam line (IBL), with no flattening filter and a carbon, rather than tungsten, electron target. The IBL produces a greater keV-range x-ray fluence than the treatment beam line (TBL), which results in a more optimal detector response. The IBL imaging dose is not necessarily negligible, however. In this work an IBL was dosimetrically modeled with the Philips Pinnacle3 treatment planning system (TPS), verified experimentally, and applied to clinical cases. The IBL acquisition dose for a 200 degrees gantry rotation was verified in a customized acrylic cylindrical phantom at multiple imaging field sizes with 196 ion chamber measurements. Agreement between the measured and calculated IBL dose was quantified with the 3D gamma index. Representative IBL and TBL imaging dose distributions were calculated for head and neck and prostate patients and included in treatment plans using the imaging dose incorporation (IDI) method. Surface dose was measured for the TBL and IBL for four head and neck cancer patients with MOSFETs. The IBL model, when compared to the percentage depth dose and profile measurements, had 97% passing gamma indices for dosimetric and distance acceptance criteria of 3%, 3 mm, and 100% passed for 5.2%, 5.2 mm. For the ion chamber measurements of phantom image acquisition dose, the IBL model had 93% passing gamma indices for acceptance criteria of 3%, 3 mm, and 100% passed for 4%, 4 mm. Differences between the IBL- and TBL-based IMRT treatment plans created with the IDI method were dosimetrically insignificant for both the prostate and head and neck cases. For IBL and TBL beams with monitor unit values that would result in the delivery of the same dose to the depth of maximum dose under standard calibration conditions, the IBL imaging surface dose was higher than the TBL imaging surface dose by an average of 18

  7. Experimental characterization of lateral profiles of scanned proton and carbon ion pencil beams for improved beam models in ion therapy treatment planning.

    PubMed

    Schwaab, J; Brons, S; Fieres, J; Parodi, K

    2011-12-21

    Scanned ion pencil beams carry a low-dose envelope which can extend up to several centimeters from the individual beam central axis. Depending on the energy and species of the beam, this halo consists mainly of secondary particles produced by nuclear interactions in the target or of particles undergoing multiple Coulomb scattering in the beam line components. This halo is often neglected by single Gaussian beam modeling in current treatment planning systems. One possibility of improving the accuracy of treatment planning is to upgrade the used pencil beam models by adding a description of the low-dose envelope. But at the same time it is crucial to keep the calculation time and the complexity for treatment planning in reasonable limits. As a first approach we measured the lateral beam profiles of scanned proton and carbon ion pencil beams at different energies and depths in water and air at the Heidelberg Ion Beam Therapy Center. Then we tried to describe their beam halo by adding a supplementary Gaussian function to the standard single Gauss modeling which is used at the moment by our treatment planning systems. This analysis helped to identify trends in the parameters describing the lateral beam broadening to support its modeling. Finally, it is shown that the accuracy of treatment planning could be improved by the proposed upgrade of the pencil beam model. In particular, the presented experimental data can be either used directly as input for dose calculation or serve for representative comparison with the results of calculation models such as Monte Carlo simulations for the generation of lateral basic data to be input in upgraded beam models of treatment planning systems.

  8. A two-bunch beam position monitor performance evaluation

    SciTech Connect

    Traller, Robert; Medvedko, Evgeny; Smith, Steve; Aiello, Roberto

    1998-12-10

    New beam position processing electronics for the Linear Accelerator allow faster feedback and processing of both positron and electron bunch positions in a single machine pulse. More than 30 electron-positron beam position monitors (epBPMs) have been installed at SLAC in various applications and have met all design requirements. The SLC production electron bunch follows the positron bunch down the linac separated by 58.8 nS. The epBPM measures the position of both bunches with an accuracy of better than 5 {mu}m at nominal operating intensities. For SLC, the epBPMs have measured the position of bunches consisting of from 1 to 8x10{sup 10} particles per bunch. For PEP-II (B Factory) injection, epBPMs have been used with larger electrodes and several BPMs have been combined on a single cable set. The signals are separated for measurement in the epBPM by timing. In PEP-II injection we have measured the position of bunches of as little as 2x10{sup 9} particles per bunch. To meet the demands of SLC and PEP-II injection, the epBPM has been designed with three triggering modes: 1. As a self-triggering detector, it can trigger off the beam and hold the peak signal until read out by the control program. 2. The gated mode uses external timing signals to gate the beam trigger. 3. The external trigger mode uses the external timing signals offset with internal vernier delays to precisely catch peak signals in noisy environments. Finally, the epBPM also has built-in timing verniers capable of nulling errors in cable set fabrication and differences in channel-to-channel signal delay. Software has made all this functionality available through the SLC control system.

  9. Performance of the (n,γ)-Based Positron Beam Facility NEPOMUC

    NASA Astrophysics Data System (ADS)

    Schreckenbach, K.; Hugenschmidt, C.; Löwe, B.; Maier, J.; Pikart, P.; Piochacz, C.; Stadlbauer, M.

    2009-01-01

    The in-pile positron source of NEPOMUC at the neutron source Heinz Maier-Leibnitz (FRM II) provides at the experimental site an intense beam of monoenergetic positrons with selectable energy between 15 eV and 3 keV. The principle of the source is based on neutron capture gamma rays produced by cadmium in a beam tube tip close to the reactor core. The gamma ray absorption in platinum produces positrons which are moderated and formed to the beam. An unprecedented beam intensity of 9.108 e+/s is achieved (1 keV). The performance and applications of the facility are presented.

  10. A high-performance electron beam ion source

    SciTech Connect

    Alessi,J.; Beebe, E.; Bellavia, S.; Gould, O.; Kponou, A.; Lambiase, R.; Lockey, R.; McCafferty, D.; Okamura, M.; Pikin, A. I.; Raparia, D.; Ritter, J.; Syndstrup, L.

    2009-06-08

    At Brookhaven National Laboratory, a high current Electron Beam Ion Source (EBIS) has been developed as part of a new preinjector that is under construction to replace the Tandem Van de Graaffs as the heavy ion preinjector for the RHIC and NASA experimental programs. This preinjector will produce milliampere-level currents of essentially any ion species, with q/A {ge} 1/6, in short pulses, for injection into the Booster synchrotron. In order to produce the required intensities, this EBIS uses a 10A electron gun, and an electron collector designed to handle 300 kW of pulsed electron beam power. The EBIS trap region is 1.5 m long, inside a 5T, 2m long, 8-inch bore superconducting solenoid. The source is designed to switch ion species on a pulse-to-pulse basis, at a 5 Hz repetition rate. Singly-charged ions of the appropriate species, produced external to the EBIS, are injected into the trap and confined until the desired charge state is reached via stepwise ionization by the electron beam. Ions are then extracted and matched into an RFQ, followed by a short IH Linac, for acceleration to 2 MeV/A, prior to injection into the Booster synchrotron. An overview of the preinjector is presented, along with experimental results from the prototype EBIS, where all essential requirements have already been demonstrated. Design features and status of construction of the final high intensity EBIS is also be presented.

  11. In situ mass measurement of electron-beam-induced nanometer-sized W-related deposits using a carbon nanotube cantilever

    SciTech Connect

    Sawaya, Shintaro; Akita, Seiji; Nakayama, Yoshikazu

    2006-11-06

    Using a carbon nanotube oscillator, the authors performed in situ measurements of densities of electron-beam-induced tungsten compounds with size of less than 100 nm. Total mass of the deposit was proportional to the deposition time. A higher deposition rate was obtained at lower electron-beam acceleration voltage. Density of the deposit decreased from 2.7 to 1.4 g/cm{sup 3} with increasing acceleration voltage from 5 to 15 kV. These results indicate that the increased density with low-acceleration voltage produces effective decomposition of W(CO){sub 6}.

  12. Impact of Intrafractional Bowel Gas Movement on Carbon Ion Beam Dose Distribution in Pancreatic Radiotherapy

    SciTech Connect

    Kumagai, Motoki; Hara, Ryusuke; Mori, Shinichiro Yanagi, Takeshi; Asakura, Hiroshi; Kishimoto, Riwa; Kato, Hirotoshi; Yamada, Shigeru; Kandatsu, Susumu; Kamada, Tadashi

    2009-03-15

    Purpose: To assess carbon ion beam dose variation due to bowel gas movement in pancreatic radiotherapy. Methods and Materials: Ten pancreatic cancer inpatients were subject to diagnostic contrast-enhanced dynamic helical CT examination under breath-holding conditions, which included multiple-phase dynamic CT with arterial, venous, and delayed phases. The arterial-venous phase and arterial-delayed phase intervals were 35 and 145 s, respectively. A compensating bolus was designed to cover the target obtained at the arterial phase. Carbon ion dose distribution was calculated by applying the bolus to the CT data sets at the other two phases. Results: Dose conformation to the clinical target volume was degraded by beam overshoot/undershoot due to bowel gas movement. The D95 for clinical target volume was degraded from 98.2% (range, 98.0-99.1%) of the prescribed dose to 94.7% (range, 88.0-99.0%) at 145 s. Excessive dosing to normal tissues varied among tissues and was, for example, 12.2 GyE/13.1 GyE (0 s/145 s) for the cord and 38.8 GyE/39.8 GyE (0 s/145 s) for the duodenum. The magnitude of beam overshoot/undershoot was particularly exacerbated from the anterior and left directions. Conclusions: Bowel gas movement causes dosimetric variation to the target during treatment for radiotherapy. The effect of bowel gas movement varies with beam angle, with greatest influence on the anterior-posterior and left-right beams.

  13. Annealing of Diamond and Diamondlike Carbon Films: AN Ion Beam Analysis Study.

    NASA Astrophysics Data System (ADS)

    Zorman, Christian Aaron

    The Van de Graaff accelerator at Case Western Reserve University was used to study annealed diamond and diamondlike carbon films. Rutherford backscattering spectroscopy and elastic recoil detection analysis were used to characterize the as-deposited and annealed samples. The diamond films were deposited by microwave enhanced CVD while the diamondlike carbon films were deposited by plasma enhanced CVD and ion beam techniques. Included in the study were nitrogenated diamondlike carbon films. The samples were annealed inside the ion scattering chamber via a heated sample holder. The samples were annealed in a stepwise manner, beginning at room temperature and ending at 550^circC. RBS and ERD spectra were simultaneously collected at each step in the annealing process. The compositional stability of the diamondlike carbon samples was determined. PECVD diamondlike carbon films remained stable up to 400^circ C, above which the hydrogen effusion was quite high. Nitrogenated diamondlike carbon films containing less than 10 atomic percent hydrogen remained stable up to 400^ circC while the hydrogenated samples were not stable above 200^circC. A distinct hydrogen enriched surface region was observed on the diamond samples. This region disappeared upon annealing at 400^circC and is most likely due to hydrogen containing adsorbates on the surface. The dynamics of this region were investigated and compared with secondary electron emission data on these samples.

  14. Carbon doping in molecular beam epitaxy of GaAs from a heated graphite filament

    NASA Technical Reports Server (NTRS)

    Malik, R. J.; Nottenberg, R. N.; Schubert, E. F.; Walker, J. F.; Ryan, R. W.

    1988-01-01

    Carbon doping of GaAs grown by molecular beam epitaxy has been obtained for the first time by use of a heated graphite filament. Controlled carbon acceptor concentrations over the range of 10 to the 17th-10 to the 20th/cu cm were achieved by resistively heating a graphite filament with a direct current power supply. Capacitance-voltage, p/n junction and secondary-ion mass spectrometry measurements indicate that there is negligible diffusion of carbon during growth and with postgrowth rapid thermal annealing. Carbon was used for p-type doping in the base of Npn AlGaAs/GaAs heterojunction bipolar transistors. Current gains greater than 100 and near-ideal emitter heterojunctions were obtained in transistors with a carbon base doping of 1 x 10 to the 19th/cu cm. These preliminary results indicate that carbon doping from a solid graphite source may be an attractive substitute for beryllium, which is known to have a relatively high diffusion coefficient in GaAs.

  15. Influence of thermal history on the mechanical properties of carbon fiber-acrylate composites cured by electron beam and thermal processes

    SciTech Connect

    Vautard, Frederic; Ozcan, Soydan; Poland, Laura E; Meyer III, Harry M

    2013-01-01

    The mechanical properties of an acrylate resin and its carbon fiber composite, as well as the adhesion strength between them, were characterized in the case of thermal and electron beam curing. The thermal history during the cure was also recorded. It was shown that the properties of the matrix were similar but that the thermal history during the curing had a direct influence on the type of interactions that were generated at the interface, leading to different level of adhesion strength and level of performance for the associated composites. In the case of a thermal cure, the thermal profile allowed the generation of covalent bonding at the interface, leading to a high level of adhesion strength, which was not the case for electron beam curing. The thermal history during the cure appeared to be a determining parameter for the level of performance of composites cured by electron beam.

  16. Performance of a 10 Gbps FSO System Implementing Novel Beam Tracking a Dynamic Buffering Modem

    NASA Technical Reports Server (NTRS)

    Kiriazes, John; Valencia, J. Emilio; Peach, Robert; Visone, Chris; Burdge, Geoffrey; Vickers, John; Leclerc, Troy; Sauer, Paul; Andrews, Larry; Phillips, Ron

    2012-01-01

    A 10 Gbps Free space optical (FSO) system implements beam tracking, a high dynamic range optical receiver, and a dynamic buffering packet modem. Performance was characterized at the 4.5 km Shuttle Landing Facility at Kennedy Space Center Florida.

  17. Structure and performance of carbon aerogel electrodes

    SciTech Connect

    Pekala, R.W.; Mayer, S.T.; Poco, J.F.; Kaschmitter, J.L.

    1994-03-01

    The chemistry and physics of small clusters of atoms (1--100 nm) has received considerable attention in recent years because these assemblies often have properties between the molecular and bulk solid-state limits. The different properties can be explained in terms of the large fraction of atoms that are at the surface of a cluster as compared to the interior. Although the synthesis and properties of metal and. semiconductor clusters, metallocarbohedrenes, fullerenes, and nanotubes are the subject of extensive investigations, little attention has been paid to cluster-assembled porous materials. This oversight is of particular interest to us since we believe that aerogels are one of the few monolithic materials presently available where the benefits of cluster assembly can be demonstrated. In particular, the unique optical, thermal, acoustic, mechanical, and electrical properties of aerogels are directly related to their nanostructure, which is composed of interconnected particles (3--30 nm) with small interstitial pores (< 50 nm). This structure leads to extremely high surface areas (400--1100 m{sup 2}/g) with a large fraction of the atoms covering the surface of the interconnected particles. As a result of these structural features, carbon aerogels are finding applications as electrodes in supercapacitors with high energy and power densities.

  18. Structural performance of notch damaged steel beams repaired with composite materials

    NASA Astrophysics Data System (ADS)

    El-Taly, Boshra

    2016-06-01

    An experimental program and an analytical model using ANSYS program were employed to estimate the structural performance of repaired damaged steel beams using fiber reinforced polymer (FRP) composite materials. The beams were artificially notched in the tension flanges at mid-spans and retrofitted by FRP flexible sheets on the tension flanges and the sheets were extended to cover parts of the beams webs with different heights. Eleven box steel beams, including one intact beam, one notch damaged beam and nine notches damaged beam and retrofitted with composite materials, were tested in two-point loading up to failure. The parameters considered were the FRP type (GFRP and CFRP) and number of layers. The results indicated that bonding CFRP sheets to both of the tension steel flange and part of the webs, instead of the tension flange only, enhances the ultimate load of the retrofitted beams, avoids the occurrence of the debonding and increases the beam ductility. Also the numerical models give acceptable results in comparison with the experimental results.

  19. The atomistic mechanism of carbon nanotube cutting catalyzed by nickel under an electron beam.

    PubMed

    Lebedeva, Irina V; Chamberlain, Thomas W; Popov, Andrey M; Knizhnik, Andrey A; Zoberbier, Thilo; Biskupek, Johannes; Kaiser, Ute; Khlobystov, Andrei N

    2014-12-21

    The cutting of single-walled carbon nanotubes by an 80 keV electron beam catalyzed by nickel clusters is imaged in situ using aberration-corrected high-resolution transmission electron microscopy. Extensive molecular dynamics simulations within the CompuTEM approach provide insight into the mechanism of this process and demonstrate that the combination of irradiation and the nickel catalyst is crucial for the cutting process to take place. The atomistic mechanism of cutting is revealed by a detailed analysis of irradiation-induced reactions of bond reorganization and atom ejection in the vicinity of the nickel cluster, showing a highly complex interplay of different chemical transformations catalysed by the metal cluster. One of the most prevalent pathways includes three consecutive stages: formation of polyyne carbon chains from the carbon nanotube, dissociation of the carbon chains into single and pairs of adatoms adsorbed on the nickel cluster, and ejection of these adatoms leading to the cutting of the nanotube. Significant variations in the atom ejection rate are discovered depending on the process stage and nanotube diameter. The revealed mechanism and kinetic characteristics of the cutting process provide fundamental knowledge for the development of new methodologies for control and manipulation of carbon structures at the nanoscale. PMID:25363681

  20. Electron beam induced current on carbon nanotubes measured through substrate electrodes

    NASA Astrophysics Data System (ADS)

    Park, J. K.; Ahn, Y. H.

    2015-11-01

    We demonstrate substrate electron-beam-induced current (s-EBIC) measurements of individual single-walled carbon nanotubes (SWNTs) by measuring the current collected by the substrate electrode, which penetrates through the insulating oxide layer. We found that s-EBIC provided better image contrast than ordinary secondary electron imaging methods for locating SWNTs that are in contact with metal electrodes. The s-EBIC has been measured for different acceleration voltages and probe currents. We found that s-EBIC did not depend critically on the acceleration voltage when the e-beam irradiated an insulating layer as compared to the case when it irradiated metal electrodes. Importantly, s-EBIC signals were increased by more than 10%, when the SWNT part was irradiated, and this makes s-EBIC imaging a very useful tool for locating individual SWNTs efficiently.

  1. Ranges of applicability for the continuum beam model in the mechanics of carbon nanotubes and nanorods

    NASA Technical Reports Server (NTRS)

    Harik, V. M.

    2001-01-01

    Limitations in the validity of the continuum beam model for carbon nanotubes (NTs) and nanorods are examined. Applicability of all assumptions used in the model is restricted by the two criteria for geometric parameters that characterize the structure of NTs. The key non-dimensional parameters that control the NT buckling behavior are derived via dimensional analysis of the nanomechanical problem. A mechanical law of geometric similitude for NT buckling is extended from continuum mechanics for different molecular structures. A model applicability map, where two classes of beam-like NTs are identified, is constructed for distinct ranges of non-dimensional parameters. Expressions for the critical buckling loads and strains are tailored for two classes of NTs and compared with the data provided by the molecular dynamics simulations. copyright 2001 Elsevier Science Ltd. All rights reserved.

  2. Non uniform shrinkages of double-walled carbon nanotube as induced by electron beam irradiation

    SciTech Connect

    Zhu, Xianfang Li, Lunxiong; Gong, Huimin; Yang, Lan; Sun, Chenghua

    2014-09-01

    Electron beam-induced nanoinstabilities of pristine double-walled carbon nanotubes (DWCNTs) of two different configurations, one fixed at both ends and another fixed at only one end, were in-situ investigated in transmission electron microscope at room temperature. It was observed that the DWCNT fixed at both ends shrank in its diameter uniformly. Meanwhile, the DWCNT fixed at only one end intriguingly shrank preferentially from its free cap end along its axial direction whereas its diameter shrinkage was offset. A mechanism of “diffusion” along with “evaporation” at room temperature which is driven by the nanocurvature of the DWCNTs, and the athermal activation induced by the electron beam was proposed to elucidate the observed phenomena. The effect of the interlayer interaction of the DWCNTs was also discussed.

  3. Performance of Conformable Phenolic Impregnated Carbon Ablator in Aerothermal Environments

    NASA Technical Reports Server (NTRS)

    Thornton, Jeremy; Fan, Wendy; Stackpoole, Mairead; Kao, David; Skokova, Kristina; Chavez-Garcia, Jose

    2012-01-01

    Conformable Phenolic Impregnated Carbon Ablator, a cousin of Phenolic Impregnated Carbon Ablator (PICA), was developed at NASA Ames Research Center as a lightweight thermal protection system under the Fundamental Aeronautics Program. PICA is made using a brittle carbon substrate, which has a very low strain to failure. Conformable PICA is made using a flexible carbon substrate, a felt in this case. The flexible felt significantly increases the strain to failure of the ablator. PICA is limited by its thermal mechanical properties. Future NASA missions will require heatshields that are more fracture resistant than PICA and, as a result, NASA Ames is working to improve PICA's performance by developing conformable PICA to meet these needs. Research efforts include tailoring the chemistry of conformable PICA with varying amounts of additives to enhance mechanical properties and testing them in aerothermal environments. This poster shows the performance of conformable PICA variants in arc jets tests. Some mechanical and thermal properties will also be presented.

  4. A novel carbon electrode material for highly improved EDLC performance.

    PubMed

    Fang, Baizeng; Binder, Leo

    2006-04-20

    Porous materials, developed by grafting functional groups through chemical surface modification with a surfactant, represent an innovative concept in energy storage. This work reports, in detail, the first practical realization of a novel carbon electrode based on grafting of vinyltrimethoxysilane (vtmos) functional group for energy storage in electric double layer capacitor (EDLC). Surface modification with surfactant vtmos enhances the hydrophobisation of activated carbon and the affinity toward propylene carbonate (PC) solvent, which improves the wettability of activated carbon in the electrolyte solution based on PC solvent, resulting in not only a lower resistance to the transport of electrolyte ions within micropores of activated carbon but also more usable surface area for the formation of electric double layer, and accordingly, higher specific capacitance, energy density, and power capability available from the capacitor based on modified carbon. Especially, the effects from surface modification become superior at higher discharge rate, at which much better EDLC performance (i.e., much higher energy density and power capability) has been achieved by the modified carbon, suggesting that the modified carbon is a novel and very promising electrode material of EDLC for large current applications where both high energy density and power capability are required. PMID:16610885

  5. In silico carbon molecular beam epitaxial growth of graphene on the h-BN substrate: carbon source effect on van der Waals epitaxy

    NASA Astrophysics Data System (ADS)

    Lee, Jonghoon; Varshney, Vikas; Park, Jeongho; Farmer, Barry L.; Roy, Ajit K.

    2016-05-01

    Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon molecular beam epitaxy (CMBE) techniques using solid carbon sublimation have reported relatively poor quality of the graphene. In this article, the CMBE growth of graphene on the h-BN substrate is numerically studied in order to identify the effect of the carbon source on the quality of the graphene film. The carbon molecular beam generated by the sublimation of solid carbon source materials such as graphite and glassy carbon is mostly composed of atomic carbon, carbon dimers and carbon trimers. Therefore, the graphene film growth becomes a complex process involving various deposition characteristics of a multitude of carbon entities. Based on the study of surface adsorption and film growth characteristics of these three major carbon entities comprising graphite vapour, we report that carbon trimers convey strong traits of vdW epitaxy prone to high quality graphene growth, while atomic carbon deposition is a surface-reaction limited process accompanied by strong chemisorption. The vdW epitaxial behaviour of carbon trimers is found to be substantial enough to nucleate and develop into graphene like planar films within a nanosecond of high flux growth simulation, while reactive atomic carbons tend to impair the structural integrity of the crystalline h-BN substrate upon deposition to form an amorphous interface between the substrate and the growing carbon film. The content of reactive atomic carbons in the molecular beam is suspected to be the primary cause of low quality graphene reported in the literature. A possible optimization of the molecular beam composition towards the synthesis of better quality graphene films is suggested.Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon

  6. Investigation of local registration performance of IMS Nanofabrication's Multi-Beam Mask Writer

    NASA Astrophysics Data System (ADS)

    Chalom, Daniel; Klikovits, Jan; Geist, David; Hudek, Peter; Eder-Kapl, Stefan; Daneshpanah, Mehdi; Laske, Frank; Eyring, Stefan; Roeth, Klaus-Dieter

    2015-07-01

    Reticles for manufacturing upcoming 10nm and 7nm Logic devices will become very complex, no matter whether 193nm water immersion lithography will continue as main stream production path or EUV lithography will be able to take over volume production of critical layers for the 7nm node. The economic manufacturing of future masks for 193i, EUV and imprint lithography with further increasing complexity drives the need for multi-beam mask writing as this technology can overcome the influence of complexity on write time of today's common variable shape beam writers. Local registration of the multi-beam array is a critical component which greatly differs from variable shape beam systems. In this paper we would like to present the local registration performance of the IMS Multi-Beam Mask Writer system and the metrology tools that enable the characterization optimization.

  7. Design and performance of a refractive optical system that converts a Gaussian to a flattop beam.

    PubMed

    Hoffnagle, J A; Jefferson, C M

    2000-10-20

    A system of two aspheric lenses is described, which efficiently converts a collimated Gaussian beam to a flattop beam. Departing from earlier designs, both aspheric surfaces were convex, simplifying their fabrication; the output beam was designed with a continuous roll-off, allowing control of the far-field diffraction pattern; and diffraction from the entrance and exit apertures was held to a negligible level. The design principles are discussed in detail, and the performance of the as-built optics is compared quantitatively with the theoretical design. Approximately 78% of the incident power is enclosed in a region with 5% rms power variation. The 8-mm-diameter beam propagates approximately 0.5 m without significant change in the intensity profile; when the beam is expanded to 32 mm in diameter, this range increases to several meters.

  8. Design and performance of a high resolution, low latency stripline beam position monitor system

    NASA Astrophysics Data System (ADS)

    Apsimon, R. J.; Bett, D. R.; Blaskovic Kraljevic, N.; Burrows, P. N.; Christian, G. B.; Clarke, C. I.; Constance, B. D.; Dabiri Khah, H.; Davis, M. R.; Perry, C.; Resta López, J.; Swinson, C. J.

    2015-03-01

    A high-resolution, low-latency beam position monitor (BPM) system has been developed for use in particle accelerators and beam lines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system was tested with electron beams in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. It consists of three stripline BPMs instrumented with analogue signal-processing electronics and a custom digitizer for logging the data. The design of the analogue processor units is presented in detail, along with measurements of the system performance. The processor latency is 15.6 ±0.1 ns . A single-pass beam position resolution of 291 ±10 nm has been achieved, using a beam with a bunch charge of approximately 1 nC.

  9. Comparison of the TESLA, NLC and CLIC beam-collimation system performance

    SciTech Connect

    Alexandr I Drozhdin; Grahame Blair; Lewis P Keller

    2003-05-28

    This report describes studies performed in the framework of the Collimation Task Force organized to support the work of the International Linear Collider Technical Review Committee. The post-linac beam-collimation systems in the TESLA, JLC/NLC and CLIC linear-collider designs are compared using the same computer code under the same assumptions. Their performance is quantified in terms of beam-halo and synchrotron-radiation collimation efficiency. The performance of the current designs varies across projects, and does not always meet the original design goals. But these comparisons suggest that achieving the required performance in a future linear collider is feasible.

  10. Non-uniform shrinkage of multiple-walled carbon nanotubes under in situ electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Li, Lunxiong; Su, Jiangbin; Zhu, Xianfang

    2016-10-01

    Instability of multiple-walled carbon nanotubes (MWCNTs) was investigated by in situ transmission electron microscopy at room temperature. Specially, the non-uniform shrinkage of tubes was found: The pristine MWCNT shrank preferentially in its axial direction from the most curved free cap end of the tube, but the shrinkage of the tube diameter was offset by the axial shrinkage: For the complex MWCNT, the two inner MWCNTs also preferentially axially shrank from their most curved cap ends and separated from each other. However, for the effect of the radial pressure from the out walls which enveloped the two inner tubes and the tube amorphization, the two inner tubes were extruded to come close to each other and finally touched again. The new "evaporation" and "diffusion" mechanisms of carbon atoms as driven by the nano-curvature of CNT and the electron beam-induced athermal activation were suggested to explain the above phenomena.

  11. Measurement of inclusive charged current interactions on carbon in a few-GeV neutrino beam

    SciTech Connect

    Nakajima, Y.; jima, Y.Naka; Alcaraz-Aunion, J.L.; Brice, S.J.; Bugel, L.; Catala-Perez, J.; Cheng, G.; Conrad, J.M.; Djurcic, Z.; Dore, U.; Finley, D.A.; /Kyoto U. /Barcelona, IFAE /Fermilab /MIT /Valencia U. /Columbia U. /MIT /Columbia U. /INFN, Rome /Rome U. /Fermilab /Columbia U. /INFN, Rome /Rome U.

    2010-11-01

    The SciBooNE Collaboration reports a measurement of inclusive charged current interactions of muon neutrinos on carbon with an average energy of 0.8 GeV using the Fermilab Booster Neutrino Beam. We compare our measurement with two neutrino interaction simulations: NEUT and NUANCE. The charged current interaction rates (product of flux and cross section) are extracted by fitting the muon kinematics, with a precision of 6-15% for the energy dependent and 3% for the energy integrated analyses. We also extract CC inclusive interaction cross sections from the observed rates, with a precision of 10-30% for the energy dependent and 8% for the energy integrated analyses. This is the first measurement of the CC inclusive cross section on carbon around 1 GeV. These results can be used to convert previous SciBooNE cross section ratio measurements to absolute cross section values.

  12. Measurement of inclusive charged current interactions on carbon in a few-GeV neutrino beam

    NASA Astrophysics Data System (ADS)

    Nakajima, Y.; Alcaraz-Aunion, J. L.; Brice, S. J.; Bugel, L.; Catala-Perez, J.; Cheng, G.; Conrad, J. M.; Djurcic, Z.; Dore, U.; Finley, D. A.; Franke, A. J.; Giganti, C.; Gomez-Cadenas, J. J.; Guzowski, P.; Hanson, A.; Hayato, Y.; Hiraide, K.; Jover-Manas, G.; Karagiorgi, G.; Katori, T.; Kobayashi, Y. K.; Kobilarcik, T.; Kubo, H.; Kurimoto, Y.; Louis, W. C.; Loverre, P. F.; Ludovici, L.; Mahn, K. B. M.; Mariani, C.; Masuike, S.; Matsuoka, K.; McGary, V. T.; Metcalf, W.; Mills, G. B.; Mitsuka, G.; Miyachi, Y.; Mizugashira, S.; Moore, C. D.; Nakaya, T.; Napora, R.; Nienaber, P.; Orme, D.; Otani, M.; Russell, A. D.; Sanchez, F.; Shaevitz, M. H.; Shibata, T.-A.; Sorel, M.; Stefanski, R. J.; Takei, H.; Tanaka, H.-K.; Tanaka, M.; Tayloe, R.; Taylor, I. J.; Tesarek, R. J.; Uchida, Y.; van de Water, R.; Walding, J. J.; Wascko, M. O.; White, H. B.; Yokoyama, M.; Zeller, G. P.; Zimmerman, E. D.

    2011-01-01

    We report a measurement of inclusive charged current interactions of muon neutrinos on carbon with an average energy of 0.8 GeV using the Fermilab Booster Neutrino Beam. We compare our measurement with two neutrino interaction simulations: NEUT and NUANCE. The charged current interaction rates (product of flux and cross section) are extracted by fitting the muon kinematics, with a precision of 6%-15% for the energy dependent and 3% for the energy integrated analyses. We also extract charged current inclusive interaction cross sections from the observed rates, with a precision of 10%-30% for the energy dependent and 8% for the energy integrated analyses. This is the first measurement of the charged current inclusive cross section on carbon around 1 GeV. These results can be used to convert previous SciBooNE cross-section ratio measurements to absolute cross-section values.

  13. Optimizing 50kV hydrogen diagnostic neutral beam performance for active spectroscopy in MST

    NASA Astrophysics Data System (ADS)

    Feng, X.; Boguski, J.; Craig, D.; den Hartog, D. J.; Munaretto, S.; Nornberg, M. D.; Olivia, S.

    2015-11-01

    The 50 kV hydrogen diagnostic neutral beam on MST provides local measurements of impurity ion emission through charge exchange recombination spectroscopy (CHERS) and of core-localized magnetic field through the motional Stark effect (MSE). The beam, which was designed to provide 5A of neutral current at 50 kV to meet these needs, is currently on a test stand to accommodate diagnosis, in order to increase the reliability of beam formation, sustain a steady current of 5 amps for 20ms, and optimize the primary energy fraction. The reliability of arc formation was increased from 40% to 80% success rate with increase of cathode gas pressure from 150kPa to 200kPa, and the stability of the arc current is improved with a decrease of the insulation magnetic field. A calorimeter with 5 thermocouples is installed to measure the horizontal and vertical beam profiles as well as beam divergence. Beam energy components are quantified through Doppler-shift spectroscopy. Preliminary simulation results of the beam using the ALCBEAM code as well as a description of how changes to the beam performance can affect CHERS and MSE measurements are presented. This work is supported by the U.S. DOE.

  14. Nitrogen incorporation in carbon nitride films produced by direct and dual ion-beam sputtering

    SciTech Connect

    Abrasonis, G.; Gago, R.; Jimenez, I.; Kreissig, U.; Kolitsch, A.; Moeller, W.

    2005-10-01

    Carbon (C) and carbon nitride (CN{sub x}) films were grown on Si(100) substrates by direct ion-beam sputtering (IBS) of a carbon target at different substrate temperatures (room temperature-450 deg. C) and Ar/N{sub 2} sputtering gas mixtures. Additionally, the effect of concurrent nitrogen-ion assistance during the growth of CN{sub x} films by IBS was also investigated. The samples were analyzed by elastic recoil detection analysis (ERDA) and x-ray absorption near-edge spectroscopy (XANES). The ERDA results showed that significant nitrogen amount (up to 20 at. %) was incorporated in the films, without any other nitrogen source but the N{sub 2}-containing sputtering gas. The nitrogen concentration is proportional to the N{sub 2} content in the sputtering beam and no saturation limit is reached under the present working conditions. The film areal density derived from ERDA revealed a decrease in the amount of deposited material at increasing growth temperature, with a correlation between the C and N losses. The XANES results indicate that N atoms are efficiently incorporated into the carbon network and can be found in different bonding environments, such as pyridinelike, nitrilelike, graphitelike, and embedded N{sub 2} molecules. The contribution of molecular and pyridinelike nitrogen decreases when the temperature increases while the contribution of the nitrilelike nitrogen increases. The concurrent nitrogen ion assistance resulted in the significant increase of the nitrogen content in the film but it induced a further reduction of the deposited material. Additionally, the assisting ions inhibited the formation of the nitrilelike configurations while promoting nitrogen environments in graphitelike positions. The nitrogen incorporation and release mechanisms are discussed in terms of film growth precursors, ion bombardment effects, and chemical sputtering.

  15. Correlation between cell death and induction of non-rejoining PCC breaks by carbon-ion beams

    NASA Astrophysics Data System (ADS)

    Suzuki, M.; Kase, Y.; Kanai, T.; Ando, K.

    We have shown a correlation between cell death and induction of non-rejoining chromatin breaks in two normal human cells and three human tumor cell lines irradiated by carbon-ion beams and X rays. Non-rejoining chromatin breaks were measured by counting the number of remaining chromatin fragments detected by the premature chromosome condensation (PCC) technique. Carbon-ion beams were accelerated by the Heavy Ion Medical Accelerator in Chiba (HIMAC). The cells were irradiated by two different mono-LET beams (LET = 13 keV/mum and 77 keV/mum) and 200kV X rays. The RBE values of cell death for carbon-ion beams relative to X rays were 1.1 to 1.4 for 13 keV/mum beams and 2.5 to 2.9 for 77 keV/mum beams. The induction rate of non-rejoining PCC breaks per cell per Gy was found to be highest for the 77 keV/mum beams for all of the cell lines. The results found in this study show that there is a good correlation between cell death and induction of non-rejoining PCC breaks for these human cell lines.

  16. High performance testbed for four-beam infrared interferometric nulling and exoplanet detection.

    PubMed

    Martin, Stefan; Booth, Andrew; Liewer, Kurt; Raouf, Nasrat; Loya, Frank; Tang, Hong

    2012-06-10

    Technology development for a space-based infrared nulling interferometer capable of earthlike exoplanet detection and characterization started in earnest in the last 10 years. At the Jet Propulsion Laboratory, the planet detection testbed was developed to demonstrate the principal components of the beam combiner train for a high performance four-beam nulling interferometer. Early in the development of the testbed, the importance of "instability noise" for nulling interferometer sensitivity was recognized, and the four-beam testbed would produce this noise, allowing investigation of methods for mitigating this noise source. The testbed contains the required features of a four-beam combiner for a space interferometer and performs at a level matching that needed for the space mission. This paper describes in detail the design, functions, and controls of the testbed.

  17. High performance testbed for four-beam infrared interferometric nulling and exoplanet detection.

    PubMed

    Martin, Stefan; Booth, Andrew; Liewer, Kurt; Raouf, Nasrat; Loya, Frank; Tang, Hong

    2012-06-10

    Technology development for a space-based infrared nulling interferometer capable of earthlike exoplanet detection and characterization started in earnest in the last 10 years. At the Jet Propulsion Laboratory, the planet detection testbed was developed to demonstrate the principal components of the beam combiner train for a high performance four-beam nulling interferometer. Early in the development of the testbed, the importance of "instability noise" for nulling interferometer sensitivity was recognized, and the four-beam testbed would produce this noise, allowing investigation of methods for mitigating this noise source. The testbed contains the required features of a four-beam combiner for a space interferometer and performs at a level matching that needed for the space mission. This paper describes in detail the design, functions, and controls of the testbed. PMID:22695670

  18. Carbon Material Optimized Biocathode for Improving Microbial Fuel Cell Performance.

    PubMed

    Tursun, Hairti; Liu, Rui; Li, Jing; Abro, Rashid; Wang, Xiaohui; Gao, Yanmei; Li, Yuan

    2016-01-01

    To improve the performance of microbial fuel cells (MFCs), the biocathode electrode material of double-chamber was optimized. Alongside the basic carbon fiber brush, three carbon materials namely graphite granules, activated carbon granules (ACG) and activated carbon powder, were added to the cathode-chambers to improve power generation. The result shows that the addition of carbon materials increased the amount of available electroactive microbes on the electrode surface and thus promote oxygen reduction rate, which improved the generation performance of the MFCs. The Output current (external resistance = 1000 Ω) greatly increased after addition of the three carbon materials and maximum power densities in current stable phase increased by 47.4, 166.1, and 33.5%, respectively. Additionally, coulombic efficiencies of the MFC increased by 16.3, 64.3, and 20.1%, respectively. These results show that MFC when optimized with ACG show better power generation, higher chemical oxygen demands removal rate and coulombic efficiency. PMID:26858695

  19. Carbon Material Optimized Biocathode for Improving Microbial Fuel Cell Performance

    PubMed Central

    Tursun, Hairti; Liu, Rui; Li, Jing; Abro, Rashid; Wang, Xiaohui; Gao, Yanmei; Li, Yuan

    2016-01-01

    To improve the performance of microbial fuel cells (MFCs), the biocathode electrode material of double-chamber was optimized. Alongside the basic carbon fiber brush, three carbon materials namely graphite granules, activated carbon granules (ACG) and activated carbon powder, were added to the cathode-chambers to improve power generation. The result shows that the addition of carbon materials increased the amount of available electroactive microbes on the electrode surface and thus promote oxygen reduction rate, which improved the generation performance of the MFCs. The Output current (external resistance = 1000 Ω) greatly increased after addition of the three carbon materials and maximum power densities in current stable phase increased by 47.4, 166.1, and 33.5%, respectively. Additionally, coulombic efficiencies of the MFC increased by 16.3, 64.3, and 20.1%, respectively. These results show that MFC when optimized with ACG show better power generation, higher chemical oxygen demands removal rate and coulombic efficiency. PMID:26858695

  20. Carbon loss induced by plasma beam irradiation in porous silica films

    SciTech Connect

    Kurihara, K.; Ono, T.; Kohmura, K.; Tanaka, H.; Fujii, N.; Hata, N.; Kikkawa, T.

    2007-06-01

    Plasma-induced damages of porous silica films during plasma processes were investigated by using a plasma beam irradiation apparatus. We used the porous silica films incorporated with methyl groups to achieve high hydrophobicity. The carbon (methyl group) reductions in the film as an index of the level of damages induced by Ar, He, O{sub 2}, H{sub 2}, and N{sub 2} plasma irradiations were examined by x-ray photoelectron spectroscopy and secondary ion mass spectroscopy. The damage due to Ar and He plasma bombardment increased with an increase in the ion dosage, although it was not strongly affected by the ion energy in the range higher than 130 eV. Furthermore, it was found that the damage near the film surface was influenced more by metastable He atoms than by metastable Ar atoms. Both O ions and O atoms caused severe damage. N atoms did not affect the decrease of carbon content but reacted with carbon to form CN bonds. H atoms decreased carbon content slightly, but the amount of decrease was saturated by the further irradiation of H atoms.

  1. Performance of the H- Ion Source Supporting 1-MW Beam Operations at SNS

    SciTech Connect

    Han, Baoxi; Hardek, Thomas W; Kang, Yoon W; Murray Jr, S N; Pennisi, Terry R; Piller, Chip; Santana, Manuel; Welton, Robert F; Stockli, Martin P

    2011-01-01

    The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory reached 1-MW of beam power in September 2009, and now routinely operates near 1-MW for the production of neutrons. This paper reviews the performance, operational issues, implemented and planned mitigations of the SNS H- ion source to support such high power-level beams with high availability. Some results from R&D activities are also briefly described.

  2. Performance of the H{sup -} Ion Source Supporting 1-MW Beam Operations at SNS

    SciTech Connect

    Han, B. X.; Hardek, T.; Kang, Y.; Murray, S. N. Jr.; Pennisi, T. R.; Piller, C.; Santana, M.; Welton, R. F.; Stockli, M. P.

    2011-09-26

    The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory reached 1-MW of beam power in September 2009, and now routinely operates near 1-MW for the production of neutrons. This paper reviews the performance, operational issues, implemented and planned mitigations of the SNS H{sup -} ion source to support such high power-level beams with high availability. Some results from R and D activities are also briefly described.

  3. {gamma}-Spectroscopy and Radioactive Beams: How To Perform Channel Selection ?

    SciTech Connect

    Rosse, B.; Redon, N.; Stezowski, O.; Schmitt, Ch.; Guinet, D.; Meyer, M.; Lautesse, Ph.; De France, G.; Bhattachasyya, S.; Mukherjee, G.

    2006-04-26

    An experiment has been performed using a SPIRAL 76Kr radioactive beam at GANIL to investigate rare-earth nuclei near the proton drip-line. The EXOGAM gamma array was coupled with the DIAMANT light charged-particle detector and the VAMOS spectrometer. We report here on the powerful of this setup to extract fusion-evaporation {gamma}-rays from a large beam contamination.

  4. In silico carbon molecular beam epitaxial growth of graphene on the h-BN substrate: carbon source effect on van der Waals epitaxy

    NASA Astrophysics Data System (ADS)

    Lee, Jonghoon; Varshney, Vikas; Park, Jeongho; Farmer, Barry L.; Roy, Ajit K.

    2016-05-01

    Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon molecular beam epitaxy (CMBE) techniques using solid carbon sublimation have reported relatively poor quality of the graphene. In this article, the CMBE growth of graphene on the h-BN substrate is numerically studied in order to identify the effect of the carbon source on the quality of the graphene film. The carbon molecular beam generated by the sublimation of solid carbon source materials such as graphite and glassy carbon is mostly composed of atomic carbon, carbon dimers and carbon trimers. Therefore, the graphene film growth becomes a complex process involving various deposition characteristics of a multitude of carbon entities. Based on the study of surface adsorption and film growth characteristics of these three major carbon entities comprising graphite vapour, we report that carbon trimers convey strong traits of vdW epitaxy prone to high quality graphene growth, while atomic carbon deposition is a surface-reaction limited process accompanied by strong chemisorption. The vdW epitaxial behaviour of carbon trimers is found to be substantial enough to nucleate and develop into graphene like planar films within a nanosecond of high flux growth simulation, while reactive atomic carbons tend to impair the structural integrity of the crystalline h-BN substrate upon deposition to form an amorphous interface between the substrate and the growing carbon film. The content of reactive atomic carbons in the molecular beam is suspected to be the primary cause of low quality graphene reported in the literature. A possible optimization of the molecular beam composition towards the synthesis of better quality graphene films is suggested.Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon

  5. Dual-ion-beam deposition of carbon films with diamond-like properties

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Swec, D. M.; Angus, J. C.

    1985-01-01

    A single and dual ion beam system was used to generate amorphous carbon films with diamond like properties. A methane/argon mixture at a molar ratio of 0.28 was ionized in the low pressure discharge chamber of a 30-cm-diameter ion source. A second ion source, 8 cm in diameter was used to direct a beam of 600 eV Argon ions on the substrates (fused silica or silicon) while the deposition from the 30-cm ion source was taking place. Nuclear reaction and combustion analysis indicate H/C ratios for the films to be 1.00. This high value of H/C, it is felt, allowed the films to have good transmittance. The films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Although the measured density of the films was approximately 1.8 gm/cu cm, a value lower than diamond, the films exhibited other properties that were relatively close to diamond. These films were compared with diamond like films generated by sputtering a graphite target.

  6. Localized surface grafting reactions on carbon nanofibers induced by gamma and e-beam irradiation

    NASA Astrophysics Data System (ADS)

    Evora, M. C.; Araujo, J. R.; Ferreira, E. H. M.; Strohmeier, B. R.; Silva, L. G. A.; Achete, C. A.

    2015-04-01

    Electron beam and gamma-ray irradiation have potential application to modify the carbon fiber nanostructures in order to produce useful defects in the graphitic structure and create reactive sites. In this study, the methodology to functionalize carbon nanofiber (CNF), via a radiation process and using acrylic acid as a source of oxygen functional groups, was investigated. The samples were submitted to a direct grafting radiation process with electron beam and gamma-ray source. Several parameters were changed such as: acrylic acid concentration, radiation dose and percentage of inhibitor necessary to achieve functionalization, with higher percentage of oxygen functional groups on CNF surface, and better dispersion. The better results achieved were when mixing CNF in a solution of acrylic acid with 6% of inhibitor (FeSO4·7H2O) and irradiated at 100 kGy. The samples were characterized by X-ray photoelectron spectroscopy and the surface composition (atomic%) showed a significant increase of oxygen content for the samples after irradiation. Also, the dispersion of the functionalized CNF in water was stable during months which may be a good indication that the functionalization process of CNF via ionizing radiation was successful.

  7. Comparison of Biological Effectiveness of Carbon-Ion Beams in Japan and Germany

    SciTech Connect

    Uzawa, Akiko; Ando, Koichi Koike, Sachiko; Furusawa, Yoshiya; Matsumoto, Yoshitaka; Takai, Nobuhiko; Hirayama, Ryoichi; Watanabe, Masahiko; Scholz, Michael; Elsaesser, Thilo; Peschke, Peter

    2009-04-01

    Purpose: To compare the biological effectiveness of 290 MeV/amu carbon-ion beams in Chiba, Japan and in Darmstadt, Germany, given that different methods for beam delivery are used for each. Methods and Materials: Murine small intestine and human salivary gland tumor (HSG) cells exponentially growing in vitro were irradiated with 6-cm width of spread-out Bragg peaks (SOBPs) adjusted to achieve nearly identical beam depth-dose profiles at the Heavy-Ion Medical Accelerator in Chiba, and the SchwerIonen Synchrotron in Darmstadt. Cell kill efficiencies of carbon ions were measured by colony formation for HSG cells and jejunum crypts survival in mice. Cobalt-60 {gamma} rays were used as the reference radiation. Isoeffective doses at given survivals were used for relative biological effectiveness (RBE) calculations and interinstitutional comparisons. Results: Isoeffective D{sub 10} doses (mean {+-} standard deviation) of HSG cells ranged from 2.37 {+-} 0.14 Gy to 3.47 {+-} 0.19 Gy for Chiba and from 2.31 {+-} 0.11 Gy to 3.66 {+-} 0.17 Gy for Darmstadt. Isoeffective D{sub 10} doses of gut crypts after single doses ranged from 8.25 {+-} 0.17 Gy to 10.32 {+-} 0.14 Gy for Chiba and from 8.27 {+-} 0.10 Gy to 10.27 {+-} 0.27 Gy for Darmstadt, whereas isoeffective D{sub 30} doses after three fractionated doses were 9.89 {+-} 0.17 Gy through 13.70 {+-} 0.54 Gy and 10.14 {+-} 0.20 Gy through 13.30 {+-} 0.41 Gy for Chiba and Darmstadt, respectively. Overall difference of RBE between the two facilities was 0-5% or 3-7% for gut crypt survival or HSG cell kill, respectively. Conclusion: The carbon-ion beams at the National Institute of Radiological Sciences in Chiba, Japan and the Gesellschaft fuer Schwerionenforschung in Darmstadt, Germany are biologically identical after single and daily fractionated irradiation.

  8. Formation of Diamond-like Carbon Thin Films by Ion Beam Assisted Deposition Method

    NASA Astrophysics Data System (ADS)

    Nakamura, Isao; Takano, Ichiro; Sasaki, Michiko; Takashika, Masaru; Kasiwagi, Tomohumi; Sawada, Yohio

    The mechanical properties of diamond-like carbon (DLC) thin films on SUS304 substrate have been studied. DLC thin films were prepared by the ion beam assisted deposition method. In this method, He+ ion irradiation was carried out in a C2H4 gas atmosphere. He+ ions were accelerated at an energy of 15 keV, and the ion beam current densities were changed from 10 to 100 μA/cm2. Atomic concentration and structure of the films were investigated by X-ray photoelectron spectroscopy and Raman spectroscopy. The mechanical properties of hardness and friction coefficient were determined using the Knoop hardness tester and the pin-on-disk tribometer. The DLC thin films had amorphous structure that composed chiefly of graphite and disorder of graphite states. The Knoop hardness of the films increased with increasing He+ ion current density, and the film prepared at a current density of 80 μA/cm2 showed the maximum Knoop hardness value of 890 kgf/cm2. The friction coefficient of the film prepared at a current density of 60 μA/cm2 indicated lower value than that of the other current densities. From these results, it was cleared that the mechanical properties and structure of DLC thin films were greatly affected by the He+ ion beam current density.

  9. Investigation of beamed-energy ERH thruster performance

    NASA Technical Reports Server (NTRS)

    Myrabo, Leik N.; Strayer, T. Darton; Bossard, John A.; Richard, Jacques C.; Gallimore, Alec D.

    1986-01-01

    The objective of this study was to determine the performance of an External Radiation Heated (ERH) thruster. In this thruster, high intensity laser energy is focused to ignite either a Laser Supported Combustion (LSC) wave or a Laser Supported Detonation (LSD) wave. Thrust is generated as the LSC or LSD wave propagates over the thruster's surface, or in the proposed thruster configuration, the vehicle afterbody. Thrust models for the LSC and LSD waves were developed and simulated on a computer. Performance parameters investigated include the effect of laser intensity, flight Mach number, and altitude on mean-thrust and coupling coefficient of the ERH thruster. Results from these models suggest that the ERH thruster using LSC/LSD wave ignition could provide propulsion performance considerably greater than any propulsion system currently available.

  10. High performance hybrid slow positron beam and its user application spectrum

    NASA Astrophysics Data System (ADS)

    Waeber, W. B.; Shi, M.

    1997-05-01

    A true hybrid beam is operational at PSI. From a β+ radioisotope source and a premoderation of the positrons to medium energies in a high magnetic field confinement of Tesla order, a 3 keV wide spectrum of positrons is extracted and adiabatically guided to low fields of less than 100 G allowing extraction in a highly efficient and quasi-divergency-free way into field free space by increasing the positron's transverse energy spread by less than 20 eV. Double electrostatic focussing followed each time by W-remoderators (air lock anneal is possible) results in a beam diameter of μm dimensions. The microbeam is then transported through a cylindrical mirror beam switch device to five different user ports (one at a time, within minutes). The first target station is equipped with a retractable beam gun and a high precision sample manipulator with six movements for low (-200°C) and high (+950°C) temperatures (sample introduction by an air lock system). At the target chamber a UHV of 3.5 × 10 -11 mbar has been reached and the chamber can be equipped for surface physics experiments, for example to perform PAES. The sample is always at ground potential and the beam energy can be tuned between a few eV and 60 keV. The facility, initially equipped with a source of 500 mCi 58Co, produces a monoenergetic beam intensity (energy spread < 2 eV) at the target of 3 × 10 6 e +/s with an average transverse phase space corresponding to 100 μm × 50 mrad. In one of the user ports an optional 7 mm diameter beam of intensity 10 7 e +/s will be available. Initial beam experiments and possible applications will be discussed and the full potential of beam performance up-grade (intensity > 10 10e+/ s, pulsing, repolarization) will be outlined.

  11. Effects of carbon ion beam irradiation on the shoot regeneration from in vitro axillary bud explants of the Impatiens hawkeri

    NASA Astrophysics Data System (ADS)

    Zhou, Libin; Zhou, Libin; Li, Wenjian; Li, Ping; Dong, Xicun; Qu, Ying; Ma, Shuang; Li, Qiang

    Accelerated ion beams is an excellent mutagen in plant breeding which can induce higher mutation frequencies and wider mutation spectrum than those of low linear energy transfer (LET) irradiations, such as X-rays (Okamura et al. 2003, Yamaguchi et al. 2003). Mutation breeding operation of two Saintpaulia ionahta cultivars using the method combining plant tissue culture technique and carbon ion beam irradiations were set out at Institute of Modern Physics from 2005 (Zhou et al. 2006). The effects of 960 MeV carbon ion beam and 8 MeV X-ray irradiations on regenerated shoots of Impatiens hawkeri from another kind of explants named in vitro axillary buds explants were studied recently. The biology endpoints in this study included relative number of roots (RNR), relative length of roots (RLR), relative height of shoots (RHS), relative number of nodes (RNN), survival fraction (SF) and morphology changes in the regenerated shoots. The experimental results showed that carbon ion beams inhibited the root and stem developments of axillary bud explants more severely than X-rays did. And the 50% lethal dose (LD50 ) is about 23.3 Gy for the carbon ion beam and 49.1 Gy for the X-rays, respectively. Relative biological effectiveness (RBE) of Impatiens hawkeri with respect to X-rays according to 50% SF was about two. Secondly, the percentage of shoots regenerated with malformed shoots including curliness, carnification, nicks in all Impatiens hawkeri axillary bud explants irradiated with carbon ion beam at 20 Gy accounted for 55.6%, while the highest number for the 40 Gy X-ray irradiation was 40%. Last, many regenerated shoots whose vascular bundle fused together were obtained only from explants irradiated with carbon ion beams. Based on the results above, it can be concluded that the effect of mutation induction by carbon ion beam irradiation on the axillary explants of Impatiens hawkeri is better than that by X-ray irradiation; and the optimal mutagenic dose varies from 20 Gy

  12. Prediction of oxidation performance of reinforced carbon-carbon material for Space Shuttle leading edges

    NASA Technical Reports Server (NTRS)

    Medford, J. E.

    1975-01-01

    A method was developed for predicting oxidation performance, in an earth atmospheric entry environment, of reinforced carbon-carbon material, coated for oxidation resistance. A model was developed which describes oxidation control mechanisms, and the equations defining these mechanisms were derived. These relations were used to correlate oxidation test data, and to infer pertinent rate constants. Predictions were made of material oxidation performance in a representative entry environment, and the predictions were compared with ground test data. Results indicate that the method can be successfully used for predicting material oxidation performance.

  13. Lithium Ion Battery Performance of Silicon Nanowires With Carbon Skin

    SciTech Connect

    Bogart, Timothy D.; Oka, Daichi; Lu, Xiaotang; Gu, Meng; Wang, Chong M.; Korgel, Brian A.

    2013-12-06

    Silicon (Si) nanomaterials have emerged as a leading candidate for next generation lithium-ion battery anodes. However, the low electrical conductivity of Si requires the use of conductive additives in the anode film. Here we report a solution-based synthesis of Si nanowires with a conductive carbon skin. Without any conductive additive, the Si nanowire electrodes exhibited capacities of over 2000 mA h g-1 for 100 cycles when cycled at C/10 and over 1200 mA h g-1 when cycled more rapidly at 1C against Li metal.. In situ transmission electron microscopy (TEM) observation reveals that the carbon skin performs dual roles: it speeds lithiation of the Si nanowires significantly, while also constraining the final volume expansion. The present work sheds light on ways to optimize lithium battery performance by smartly tailoring the nanostructure of composition of materials based on silicon and carbon.

  14. THE MEASURED PERFORMANCE OF A MILLIMETER WAVE BEAM SPLITTER

    SciTech Connect

    C.P. MOELLER; J. LOHR; J.L. DOANE

    2002-09-01

    An essential component of any high power transmission system is a directional coupler that provides a sample of the forward and reflected power when this power is being delivered to the intended load. In the case of millimeter power delivered through a highly oversized corrugated waveguide, there is the much more complex issue of mode purity. It is possible to design an effective mode selective branch guide directional coupler in smooth wall overmoded waveguide. In the typical highly overmoded corrugated waveguide propagating the HE{sub 11} mode, however, obtaining an adequate coupling factor can be difficult, and branch guide attenuation and phase velocity matching over several meters become concerns. A more practical approach for large diameter corrugated waveguide is to obtain a sample of the propagating beam at a miter bend mirror. At low power, the mirror could be a thin metal screen. At the megawatt level, however, heat removal must be considered. For example, at 110 GHz at 1 MW, taking the surface resistance of copper to be 0.10 {Omega}, the dissipation on a 45{sup o} copper mirror would be 750 W or 1500 W for H or E plane reflection, respectively. With a peak to average power ratio of 3.7 for the circular HE{sub 11} mode, in 31.75 cm diameter corrugated waveguide the peak dissipation can be as high as 500 W/cm{sup 2} at the center of the mirror. An edge cooled thin metal screen is not therefore practical, but a thick plate containing a single narrow channel, at the bottom of which is a row of holes in the remaining thin wall, can be adequately water-cooled on its face. To maintain vacuum and focus the radiation from the holes, the narrow channel is filled by a fused quartz plate, the shape of which is a 45{sup o} sector of a circle having a truncated apex at the coupling holes. These are being used as power monitors on the DIII-D ECH system and on other systems. Since this single row of holes samples only part of the wave field, however, interference among

  15. High performance stream computing for particle beam transport simulations

    NASA Astrophysics Data System (ADS)

    Appleby, R.; Bailey, D.; Higham, J.; Salt, M.

    2008-07-01

    Understanding modern particle accelerators requires simulating charged particle transport through the machine elements. These simulations can be very time consuming due to the large number of particles and the need to consider many turns of a circular machine. Stream computing offers an attractive way to dramatically improve the performance of such simulations by calculating the simultaneous transport of many particles using dedicated hardware. Modern Graphics Processing Units (GPUs) are powerful and affordable stream computing devices. The results of simulations of particle transport through the booster-to-storage-ring transfer line of the DIAMOND synchrotron light source using an NVidia GeForce 7900 GPU are compared to the standard transport code MAD. It is found that particle transport calculations are suitable for stream processing and large performance increases are possible. The accuracy and potential speed gains are compared and the prospects for future work in the area are discussed.

  16. Analytic expressions for the inelastic scattering and energy loss of electron and proton beams in carbon nanotubes

    SciTech Connect

    Emfietzoglou, D.; Kyriakou, I.; Garcia-Molina, R.; Abril, I.; Kostarelos, K.

    2010-09-15

    We have determined ''effective'' Bethe coefficients and the mean excitation energy of stopping theory (I-value) for multiwalled carbon nanotubes (MWCNTs) and single-walled carbon nanotube (SWCNT) bundles based on a sum-rule constrained optical-data model energy loss function with improved asymptotic properties. Noticeable differences between MWCNTs, SWCNT bundles, and the three allotropes of carbon (diamond, graphite, glassy carbon) are found. By means of Bethe's asymptotic approximation, the inelastic scattering cross section, the electronic stopping power, and the average energy transfer to target electrons in a single inelastic collision, are calculated analytically for a broad range of electron and proton beam energies using realistic excitation parameters.

  17. Nanoengineering heat transfer performance at carbon nanotube interfaces.

    PubMed

    Xu, Zhiping; Buehler, Markus J

    2009-09-22

    Carbon nanotubes are superb materials for nanoscale thermal management and phononic devices applications, due to their extremely high thermal conductivity (3000-6600 W/mK) and quasi-one-dimensional geometry. However, the presence of interfaces between individual carbon nanotubes as found widely in nanocomposites, nanoelectronics, and nanodevices severely limits their performance for larger scale applications. Solving this issue requires a deep understanding of the heat transfer mechanism at this nanoscale interface between low-dimensional structures, where conventional models developed for interfaces in bulk materials do not apply. Here we address this challenge through a bottom-up approach based on atomistic simulations. We demonstrate that the huge thermal resistance of carbon nanotube junctions can be significantly improved through modifying the molecular structure at the interface to enhance both the matching of phonon spectra and phonon mode coupling. Specifically, two approaches based on polymer wrapping and metal coatings are investigated here and have shown to improve both the structural stability and interfacial thermal conductivity of carbon nanotube junctions. By properly designing the interface molecular structure between individual carbon nanotubes, significant performance gains up to a factor of 4 can be achieved. These results pave the way for future designs of thermal management networks and phononic devices with thermally transparent and structurally stable interfaces.

  18. Rapid phase-correlated rescanning irradiation improves treatment time in carbon-ion scanning beam treatment under irregular breathing

    NASA Astrophysics Data System (ADS)

    Mori, Shinichiro; Furukawa, Takuji

    2016-05-01

    To shorten treatment time in pencil beam scanning irradiation, we developed rapid phase-controlled rescanning (rPCR), which irradiates two or more isoenergy layers in a single gating window. Here, we evaluated carbon-ion beam dose distribution with rapid and conventional PCR (cPCR). 4 dimensional computed tomography (4DCT) imaging was performed on 12 subjects with lung or liver tumors. To compensate for intrafractional range variation, the field-specific target volume (FTV) was calculated using 4DCT within the gating window (T20–T80). We applied an amplitude-based gating strategy, in which the beam is on when the tumor is within the gating window defined by treatment planning. Dose distributions were calculated for layered phase-controlled rescanning under an irregular respiratory pattern, although a single 4DCT data set was used. The number of rescannings was eight times. The prescribed doses were 48 Gy(RBE)/1 fr (where RBE is relative biological effectiveness) delivered via four beam ports to the FTV for the lung cases and 45 Gy(RBE)/2 fr delivered via two beam ports to the FTV for the liver cases. In the liver cases, the accumulated dose distributions showed an increased magnitude of hot/cold spots with rPCR compared with cPCR. The results of the dose assessment metrics for the cPCR and rPCR were very similar. The D 95, D max, and D min values (cPCR/rPCR) averaged over all the patients were 96.3  ±  0.9%/96.0  ±  1.2%, 107.3  ±  3.6%/107.1  ±  2.9%, and 88.8  ±  3.2%/88.1  ±  3.1%, respectively. The treatment times in cPCR and rPCR were 110.7 s and 53.5 s, respectively. rPCR preserved dose conformation under irregular respiratory motion and reduced the total treatment time compared with cPCR.

  19. Rapid phase-correlated rescanning irradiation improves treatment time in carbon-ion scanning beam treatment under irregular breathing

    NASA Astrophysics Data System (ADS)

    Mori, Shinichiro; Furukawa, Takuji

    2016-05-01

    To shorten treatment time in pencil beam scanning irradiation, we developed rapid phase-controlled rescanning (rPCR), which irradiates two or more isoenergy layers in a single gating window. Here, we evaluated carbon-ion beam dose distribution with rapid and conventional PCR (cPCR). 4 dimensional computed tomography (4DCT) imaging was performed on 12 subjects with lung or liver tumors. To compensate for intrafractional range variation, the field-specific target volume (FTV) was calculated using 4DCT within the gating window (T20-T80). We applied an amplitude-based gating strategy, in which the beam is on when the tumor is within the gating window defined by treatment planning. Dose distributions were calculated for layered phase-controlled rescanning under an irregular respiratory pattern, although a single 4DCT data set was used. The number of rescannings was eight times. The prescribed doses were 48 Gy(RBE)/1 fr (where RBE is relative biological effectiveness) delivered via four beam ports to the FTV for the lung cases and 45 Gy(RBE)/2 fr delivered via two beam ports to the FTV for the liver cases. In the liver cases, the accumulated dose distributions showed an increased magnitude of hot/cold spots with rPCR compared with cPCR. The results of the dose assessment metrics for the cPCR and rPCR were very similar. The D 95, D max, and D min values (cPCR/rPCR) averaged over all the patients were 96.3  ±  0.9%/96.0  ±  1.2%, 107.3  ±  3.6%/107.1  ±  2.9%, and 88.8  ±  3.2%/88.1  ±  3.1%, respectively. The treatment times in cPCR and rPCR were 110.7 s and 53.5 s, respectively. rPCR preserved dose conformation under irregular respiratory motion and reduced the total treatment time compared with cPCR.

  20. Initial operation and performance of the PDX neutral-beam injection system

    SciTech Connect

    Kugel, H.W.; Eubank, H.P.; Kozub, T.A.; Rossmassler, J.E.; Schilling, G.; van Halle, A.; Williams, M.D.

    1982-01-19

    In 1981, the joint ORNL/PPPL PDX neutral beam heating project succeeded in reliably injecting 7.2 MW of D/sup 0/ into the PDX plasma, at nearly perpendicular angles, and achieved ion temperatures up to 6.5 keV. The expeditious achievement of this result was due to the thorough conditioning and qualification of the PDX neutral beam ion sources at ORNL prior to delivery coupled with several field design changes and improvements in the injection system made at PPPL as a result of neutral beam operating experience with the PLT tokamak. It has been found that the operation of high power neutral beam injection systems in a tokamak-neutral beam environment requires procedures and performance different from those required for development operation on test stands. In this paper, we review the installatin of the PDX neutral beam injection system, and its operation and performance during the initial high power plasma heating experiments with the PDX tokamak.

  1. Robustness of target dose coverage to motion uncertainties for scanned carbon ion beam tracking therapy of moving tumors

    NASA Astrophysics Data System (ADS)

    Eley, John Gordon; Newhauser, Wayne David; Richter, Daniel; Lüchtenborg, Robert; Saito, Nami; Bert, Christoph

    2015-02-01

    Beam tracking with scanned carbon ion radiotherapy achieves highly conformal target dose by steering carbon pencil beams to follow moving tumors using real-time magnetic deflection and range modulation. The purpose of this study was to evaluate the robustness of target dose coverage from beam tracking in light of positional uncertainties of moving targets and beams. To accomplish this, we simulated beam tracking for moving targets in both water phantoms and a sample of lung cancer patients using a research treatment planning system. We modeled various deviations from perfect tracking that could arise due to uncertainty in organ motion and limited precision of a scanned ion beam tracking system. We also investigated the effects of interfractional changes in organ motion on target dose coverage by simulating a complete course of treatment using serial (weekly) 4DCTs from six lung cancer patients. For perfect tracking of moving targets, we found that target dose coverage was high ({{\\overline{V}}95} was 94.8% for phantoms and 94.3% for lung cancer patients, respectively) but sensitive to changes in the phase of respiration at the start of treatment and to the respiratory period. Phase delays in tracking the moving targets led to large degradation of target dose coverage (up to 22% drop for a 15° delay). Sensitivity to technical uncertainties in beam tracking delivery was minimal for a lung cancer case. However, interfractional changes in anatomy and organ motion led to large decreases in target dose coverage (target coverage dropped approximately 8% due to anatomy and motion changes after 1 week). Our findings provide a better understand of the importance of each of these uncertainties for beam tracking with scanned carbon ion therapy and can be used to inform the design of future scanned ion beam tracking systems.

  2. Robustness of Target Dose Coverage to Motion Uncertainties for Scanned Carbon Ion Beam Tracking Therapy of Moving Tumors

    PubMed Central

    Eley, John Gordon; Newhauser, Wayne David; Richter, Daniel; Lüchtenborg, Robert; Saito, Nami; Bert, Christoph

    2015-01-01

    Beam tracking with scanned carbon ion radiotherapy achieves highly conformal target dose by steering carbon pencil beams to follow moving tumors using real-time magnetic deflection and range modulation. The purpose of this study was to evaluate the robustness of target dose coverage from beam tracking in light of positional uncertainties of moving targets and beams. To accomplish this, we simulated beam tracking for moving targets in both water phantoms and a sample of lung cancer patients using a research treatment planning system. We modeled various deviations from perfect tracking that could arise due to uncertainty in organ motion and limited precision of a scanned ion beam tracking system. We also investigated the effects of interfractional changes in organ motion on target dose coverage by simulating a complete course of treatment using serial (weekly) 4DCTs from 6 lung cancer patients. For perfect tracking of moving targets, we found that target dose coverage was high (V̄95 was 94.8% for phantoms and 94.3% for lung cancer patients, respectively) but sensitive to changes in the phase of respiration at the start of treatment and to the respiratory period. Phase delays in tracking the moving targets led to large degradation of target dose coverage (up to 22% drop for a 15 degree delay). Sensitivity to technical uncertainties in beam tracking delivery was minimal for a lung cancer case. However, interfractional changes in anatomy and organ motion led to large decreases in target dose coverage (target coverage dropped approximately 8% due to anatomy and motion changes after 1 week). Our findings provide a better understand of the importance of each of these uncertainties for beam tracking with scanned carbon ion therapy and can be used to inform the design of future scanned ion beam tracking systems. PMID:25650520

  3. Robustness of target dose coverage to motion uncertainties for scanned carbon ion beam tracking therapy of moving tumors.

    PubMed

    Eley, John Gordon; Newhauser, Wayne David; Richter, Daniel; Lüchtenborg, Robert; Saito, Nami; Bert, Christoph

    2015-02-21

    Beam tracking with scanned carbon ion radiotherapy achieves highly conformal target dose by steering carbon pencil beams to follow moving tumors using real-time magnetic deflection and range modulation. The purpose of this study was to evaluate the robustness of target dose coverage from beam tracking in light of positional uncertainties of moving targets and beams. To accomplish this, we simulated beam tracking for moving targets in both water phantoms and a sample of lung cancer patients using a research treatment planning system. We modeled various deviations from perfect tracking that could arise due to uncertainty in organ motion and limited precision of a scanned ion beam tracking system. We also investigated the effects of interfractional changes in organ motion on target dose coverage by simulating a complete course of treatment using serial (weekly) 4DCTs from six lung cancer patients. For perfect tracking of moving targets, we found that target dose coverage was high ([Formula: see text] was 94.8% for phantoms and 94.3% for lung cancer patients, respectively) but sensitive to changes in the phase of respiration at the start of treatment and to the respiratory period. Phase delays in tracking the moving targets led to large degradation of target dose coverage (up to 22% drop for a 15° delay). Sensitivity to technical uncertainties in beam tracking delivery was minimal for a lung cancer case. However, interfractional changes in anatomy and organ motion led to large decreases in target dose coverage (target coverage dropped approximately 8% due to anatomy and motion changes after 1 week). Our findings provide a better understand of the importance of each of these uncertainties for beam tracking with scanned carbon ion therapy and can be used to inform the design of future scanned ion beam tracking systems.

  4. Performance projections for laser beam power to space

    NASA Technical Reports Server (NTRS)

    Greenwood, Darryl P.

    1992-01-01

    We examine the requirements placed on an adaptive-optics system used to compensate atmospheric effects in propagating high-power lasers from ground to space. The particular application involves energy transfer from a ground station to a satellite. Our analysis explores performance associated with various beacon configurations, including satellite-based beacons, beacons in the lead-ahead direction, and synthetic beacons. Other system parameters are adjusted as well, including number of actuators in the deformable mirror and bandwidth of the servo system. We show that with an optimized system design it is possible to achieve collection efficiencies of 10-50 percent over zenith angles as great as 70 deg.

  5. Performance of beam bender for very cold neutrons

    NASA Astrophysics Data System (ADS)

    Kawabata, Yuji; Utsuro, Masahiko; Ebisawa, Tohru

    1992-11-01

    A VCN bender has been installed behind the VCN guide tube in the UCN-VCN facility of KUR. The design and the performance of the VCN bender is described in this paper. The neutron spectra at the end of the VCN bender has been measured by the reflection method using a multilayer monochromator. Neutron radiography films were used to know the neutron flux distribution. The VCN gain factor of the CNS is also derived from the spectrum measurements at the end of the VCN guide tube and the VCN bender.

  6. High-resolution adaptive nulling performance for a lightweight agile EHF multiple beam antenna

    NASA Astrophysics Data System (ADS)

    Fenn, A. J.; Johnson, J. R.; Rispin, L. W.; Cummings, W. C.; Potts, B. M.

    The design and experimental performance of a lightweight high-resolution adaptive nulling extremely high-frequency multiple beam antenna (MBA) are addressed. A 127-beam MBA and a four-channel RF nulling network operating over the 43.5-to-45.5-GHz band were used to adaptively null a jammer in anechoic chamber measurements. Lightweight waveguide transmission lines together with ferrite switches were used to select beam ports from the 127-beam MBA. The MBA was designed to provide simultaneous coverage for three communications system users while providing pattern discrimination or nulling of jammers located within 0.1 deg of the user. Cancellation greater than 30 dB when operating in a wideband mode was experimentally demonstrated.

  7. Strain measurements on concrete beam and carbon fiber cable with distributed optical fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Nellen, Philipp M.; Bronnimann, Rolf; Sennhauser, Urs J.; Askins, Charles G.; Putnam, Martin A.

    1996-09-01

    We report on civil engineering applications of wavelength multiplexed optical fiber Bragg grating arrays directly produced on the draw tower for testing and surveying advanced structures and materials such as carbon fiber reinforced concrete elements and prestressing cables. We equipped a 6 by 0.9 by 0.5 m concrete beam, which was reinforced with carbon fiber reinforced epoxy laminates, and a 7-m long prestressing carbon fiber cable made of seven twisted strands, with optical fiber Bragg grating sensors. Static strains up to 8000 micrometers/m and dynamic strains up to 1200 micrometers/m were measured with a Michelson interferometer used as Fourier spectrometer with a resolution of about 10 micrometers/m for all sensors. Comparative measurements with electrical resistance strain gauges were in good agreement with the fiber optical results. We installed the fiber sensors in two different arrangements: some Bragg grating array elements measured local strain while others were applied in an extensometric configuration to measure moderate strain over a base length of 0.1 to 1 m.

  8. SU-E-T-470: Beam Performance of the Radiance 330 Proton Therapy System

    SciTech Connect

    Nazaryan, H; Nazaryan, V; Wang, F; Flanz, J; Alexandrov, V

    2014-06-01

    Purpose: The ProTom Radiance 330 proton radiotherapy system is a fully functional, compact proton radiotherapy system that provides advanced proton delivery capabilities. It supports three-dimensional beam scanning with energy and intensity modulation. A series of measurements have been conducted to characterize the beam performance of the first installation of the system at the McLaren Proton Therapy Center in Flint, Michigan. These measurements were part of the technical commissioning of the system. Select measurements and results are presented. Methods: The Radiance 330 proton beam energy range is 70–250 MeV for treatment, and up to 330 MeV for proton tomography and radiography. Its 3-D scanning capability, together with a small beam emittance and momentum spread, provides a highly efficient beam delivery. During the technical commissioning, treatment plans were created to deliver uniform maps at various energies to perform Gamma Index analysis. EBT3 Gafchromic films were irradiated using the Planned irradiation maps. Bragg Peak chamber was used to test the dynamic range during a scan in one layer for high (250 MeV) and Low (70 MeV) energies. The maximum and minimum range, range adjustment and modulation, distal dose falloff (80%–20%), pencil beam spot size, spot placement accuracy were also measured. The accuracy testing included acquiring images, image registration, receiving correction vectors and applying the corrections to the robotic patient positioner. Results: Gamma Index analysis of the Treatment Planning System (TPS) data vs. Measured data showed more than 90% of points within (3%, 3mm) for the maps created by the TPS. At Isocenter Beam Size (One sigma) < 3mm at highest energy (250 MeV) in air. Beam delivery was within 0.6 mm of the intended target at the entrance and the exit of the beam, through the phantom. Conclusion: The Radiance 330 Beam Performance Measurements have confirmed that the system operates as designed with excellent clinical

  9. Combination of carbon ion beam and gemcitabine causes irreparable DNA damage and death of radioresistant pancreatic cancer stem-like cells in vitro and in vivo

    PubMed Central

    Sai, Sei; Wakai, Toshifumi; Vares, Guillaume; Yamada, Shigeru; Kamijo, Takehiko; Kamada, Tadashi; Shirai, Toshiyuki

    2015-01-01

    We try to elucidate whether a carbon ion beam alone or in combination with gemcitabine has advantages over X-ray in targeting putative pancreatic cancer stem-like cells (CSCs) in vitro and in vivo. Colony, spheroid formation and tumorigenicity assays confirmed that CD44+/ESA+ cells sorted from PANC1 and PK45 cells have more CSC properties than CD44−/ESA− cells. The number of colonies and spheroids formed from CSCs after carbon ion beam irradiation was significantly reduced compared to after X-ray irradiation, and they were extremely highly suppressed when carbon ion beam combined with gemcitabine. The relative biological effectiveness (RBE) values for the carbon ion beam relative to X-ray at the D10 levels for CSCs were 2.23-2.66. Expressions of multiple cell death-related genes were remarkably highly induced, and large numbers of γH2AX foci in CSCs were formed after carbon ion beam combined with gemcitabine. The highly expressed CSC markers were significantly inhibited after 30 Gy of carbon ion beam and almost lost after 25 Gy carbon ion beam combined with 50 mg/kg gemcitabine. In conclusion, a carbon ion beam combined with gemcitabine has superior potential to kill pancreatic CSCs via irreparable clustered DSB compared to a carbon ion alone or X-rays combined with gemcitabine. PMID:25849939

  10. Performance Modeling and Optimization of a High Energy CollidingBeam Simulation Code

    SciTech Connect

    Shan, Hongzhang; Strohmaier, Erich; Qiang, Ji; Bailey, David H.; Yelick, Kathy

    2006-06-01

    An accurate modeling of the beam-beam interaction is essential to maximizing the luminosity in existing and future colliders. BeamBeam3D was the first parallel code that can be used to study this interaction fully self-consistently on high-performance computing platforms. Various all-to-all personalized communication (AAPC) algorithms dominate its communication patterns, for which we developed a sequence of performance models using a series of micro-benchmarks. We find that for SMP based systems the most important performance constraint is node-adapter contention, while for 3D-Torus topologies good performance models are not possible without considering link contention. The best average model prediction error is very low on SMP based systems with of 3% to 7%. On torus based systems errors of 29% are higher but optimized performance can again be predicted within 8% in some cases. These excellent results across five different systems indicate that this methodology for performance modeling can be applied to a large class of algorithms.

  11. Performance of three pencil-type ionization chambers (10 cm) in computed tomography standard beams

    NASA Astrophysics Data System (ADS)

    de Castro, Maysa C.; Xavier, Marcos; Caldas, Linda V. E.

    2016-07-01

    The use of computed tomography (CT) has increased over the years, thus generating a concern about the doses received by patients undergoing this procedure. Therefore, it is necessary to perform routinely beam dosimetry with the use of a pencil-type ionization chamber. This detector is the most utilized in the procedures of quality control tests on this kind of equipment. The objective of this work was to perform some characterization tests in standard CT beams, as the saturation curve, polarity effect, ion collection efficiency and linearity of response, using three ionization chambers, one commercial and two developed at the IPEN.

  12. Ablative performance of carbon-carbon nosetips in simulated re-entry environments

    NASA Technical Reports Server (NTRS)

    Nestler, D. E.

    1977-01-01

    A summary is presented of ablation performance data for carbon-carbon nosetip models obtained over a range of pressures from 10 to 168 atm. Two classes of tests are reviewed: (1) steady state, in which a constant environment is imposed on the model, and (2) ramp, in which the pressure is increased from 10 to 80 atmospheres to simulate re-entry pressure history. Comparison of arc test parameters with typical reentry vehicle parameters is included, to assess the adequacy of the test simulation. Based on this comparison, recommendations are made for facility developments which would yield improved simulation capability for reentry vehicle nosetip ablative performance.

  13. Analysis of beamed-energy ramjet/scramjet performance

    NASA Technical Reports Server (NTRS)

    Myrabo, L. N.; Powers, M. V.; Zaretzky, C. L.

    1986-01-01

    A study has been performed on a laser-heated ramjet/scramjet vehicle concept for propulsion during the air-breathing portion of an orbital launch trajectory. The concept considers axisymmetric, high-thrust vehicles with external inlets and nozzles. Conceptual design and ramjet/scramjet cycle analysis are emphasized, with propulsive energy provided by combustion of on-board fuel. The conventional ramjet/scramjet combustion chamber is replaced by a laser energy absorption chamber. The elimination of on-board propellant can result in very high thrust-to-weight ratios and payload fractions, in a vehicle with a relatively small degree of mechanical complexity. The basic vehicle has a weight of 12,250 lbf, and a diameter of 5 meters, which is close to the size of the Apollo command module. The ramjet calculations are based on a Mach 3 isentropic inlet with a 13.7 degree half-angle conical tip. The scramjet analysis considers conical inlets with 10, 15, and 30 degree half-angles. Flight Mach numbers from 2 to 20 are considered in the calculations.

  14. High Performance Image Processing And Laser Beam Recording System

    NASA Astrophysics Data System (ADS)

    Fanelli, Anthony R.

    1980-09-01

    The article is meant to provide the digital image recording community with an overview of digital image processing, and recording. The Digital Interactive Image Processing System (DIIPS) was assembled by ESL for Air Force Systems Command under ROME AIR DEVELOPMENT CENTER's guidance. The system provides the capability of mensuration and exploitation of digital imagery with both mono and stereo digital images as inputs. This development provided for system design, basic hardware, software and operational procedures to enable the Air Force's System Command photo analyst to perform digital mensuration and exploitation of stereo digital images as inputs. The engineering model was based on state-of-the-art technology and to the extent possible off-the-shelf hardware and software. A LASER RECORDER was also developed for the DIIPS Systems and is known as the Ultra High Resolution Image Recorder (UHRIR). The UHRIR is a prototype model that will enable the Air Force Systems Command to record computer enhanced digital image data on photographic film at high resolution with geometric and radiometric distortion minimized.

  15. Effect of Graphitic Content on Carbon Supported Catalyst Performance

    SciTech Connect

    A. Patel; K. Artyushkova; P. Atanassov; David Harvey; M. Dutta; V. Colbow; S. Wessel

    2011-07-01

    The effect of graphitic content on carbon supported platinum catalysts was investigated in order to investigate its influence on catalyst performance. Four catalysts of varying surface areas and graphitic content were analyzed using XPS, HREELS, and tested using RDE experiments. The catalysts were also heat treated at 150 C and 100%RH as means to uniformly age them. The heat treated samples were analyzed using the same methods to determine what changes had occurred due to this aging process. When compared to the BOL catalysts, heat treated catalysts displayed increased graphitic carbon and platinum metallic content, however they also showed depressed catalytic activity. The primary cause is still under investigation, though it is believed to be related to loss of amorphous carbon content.

  16. Effect of Graphitic Content on Carbon Supported Catalyst Performance

    SciTech Connect

    Patel, Anant; Artyushkova, Kateryna; Atanassov, Plamen; Harvey, David; Dutta, Monica; Colbow, Vesna

    2011-07-01

    The effect of graphitic content on carbon supported platinum catalysts was investigated in order to investigate its influence on catalyst performance. Four catalysts of varying surface areas and graphitic content were analyzed using XPS, HREELS, and tested using RDE experiments. The catalysts were also heat treated at 150oC and 100%RH as means to uniformly age them. The heat treated samples were analyzed using the same methods to determine what changes had occurred due to this aging process. When compared to the BOL catalysts, heat treated catalysts displayed increased graphitic carbon and platinum metalic content, however they also showed depressed catalytic activity. The primary cause is still under investigation, though it is believed to be related to loss of amorphous carbon content.

  17. Production of clinically useful positron emitter beams during carbon ion deceleration.

    PubMed

    Lazzeroni, M; Brahme, A

    2011-03-21

    In external beam radiation therapy, radioactive beams offer the best clinical solution to simultaneously treat and in vivo monitor the dose delivery and tumor response using PET or PET-CT imaging. However, difficulties mainly linked to the low production efficiency have so far limited their use. This study is devoted to the analysis of the production of high energy (11)C fragments, preferably by projectile fragmentation of a stable monodirectional and monoenergetic primary (12)C beam in different absorbing materials (decelerators) in order to identify the optimal elemental composition. The study was performed using the Monte Carlo code SHIELD-HIT07. The track length and fluence of generated secondary particles were scored in a uniform absorber of 300 cm length and 10 cm radius, divided into slices of 1 cm thickness. The (11)C fluence build-up and mean energy variation with increasing decelerator depth are presented. Furthermore, the fluence of the secondary (11)C beam was studied as a function of its mean energy and the corresponding remaining range in water. It is shown that the maximum (11)C fluence build-up is high in compounds where the fraction by weight of hydrogen is high, being the highest in liquid hydrogen. Furthermore, a cost effective alternative solution to the single medium initially envisaged is presented: a two-media decelerator that comprises a first liquid hydrogen section followed by a second decelerating section made of a hydrogen-rich material, such as polyethylene (C(2)H(4)). The purpose of the first section is to achieve a fast initial (11)C fluence build-up, while the second section is primarily designed to modulate the mean energy of the generated (11)C beam in order to reach the tumor depth. Finally, it was demonstrated that, if the intensity of the primary (12)C beam can be increased by an order of magnitude, a sufficient intensity of the secondary (11)C beam is achieved for therapy and subsequent therapeutic PET imaging sessions. Such an

  18. Production of clinically useful positron emitter beams during carbon ion deceleration

    NASA Astrophysics Data System (ADS)

    Lazzeroni, M.; Brahme, A.

    2011-03-01

    In external beam radiation therapy, radioactive beams offer the best clinical solution to simultaneously treat and in vivo monitor the dose delivery and tumor response using PET or PET-CT imaging. However, difficulties mainly linked to the low production efficiency have so far limited their use. This study is devoted to the analysis of the production of high energy 11C fragments, preferably by projectile fragmentation of a stable monodirectional and monoenergetic primary 12C beam in different absorbing materials (decelerators) in order to identify the optimal elemental composition. The study was performed using the Monte Carlo code SHIELD-HIT07. The track length and fluence of generated secondary particles were scored in a uniform absorber of 300 cm length and 10 cm radius, divided into slices of 1 cm thickness. The 11C fluence build-up and mean energy variation with increasing decelerator depth are presented. Furthermore, the fluence of the secondary 11C beam was studied as a function of its mean energy and the corresponding remaining range in water. It is shown that the maximum 11C fluence build-up is high in compounds where the fraction by weight of hydrogen is high, being the highest in liquid hydrogen. Furthermore, a cost effective alternative solution to the single medium initially envisaged is presented: a two-media decelerator that comprises a first liquid hydrogen section followed by a second decelerating section made of a hydrogen-rich material, such as polyethylene (C2H4). The purpose of the first section is to achieve a fast initial 11C fluence build-up, while the second section is primarily designed to modulate the mean energy of the generated 11C beam in order to reach the tumor depth. Finally, it was demonstrated that, if the intensity of the primary 12C beam can be increased by an order of magnitude, a sufficient intensity of the secondary 11C beam is achieved for therapy and subsequent therapeutic PET imaging sessions. Such an increase in the

  19. A performance-enhanced energy harvester for low frequency vibration utilizing a corrugated cantilevered beam

    NASA Astrophysics Data System (ADS)

    Kim, In-Ho; Jin, SeungSeop; Jang, Seon-Jun; Jung, Hyung-Jo

    2014-03-01

    This note proposes a performance-enhanced piezoelectric energy harvester by replacing a conventional flat cantilevered beam with a corrugated beam. It consists of a proof mass and a sinusoidally or trapezoidally corrugated cantilevered beam covered by a polyvinylidene fluoride (PVDF) film. Compared to the conventional energy harvester of the same size, it has a more flexible bending stiffness and a larger bonding area of the PVDF layer, so higher output voltage from the device can be expected. In order to investigate the characteristics of the proposed energy harvester, analytical developments and numerical simulations on its natural frequency and tip displacement are carried out. Shaking table tests are also conducted to verify the performance of the proposed device. It is clearly shown from the tests that the proposed energy harvester not only has a lower natural frequency than an equivalent sized standard energy harvester, but also generates much higher output voltage than the standard one.

  20. The performance of heterodyne detection system for partially coherent beams in turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Chengqiang, Li; Tingfeng, Wang; Heyong, Zhang; Jingjiang, Xie; Lisheng, Liu; Shuai, Zhao; Jin, Guo

    2015-12-01

    The performance of heterodyne system is discussed for partially coherent beams in turbulent atmosphere by introducing turbulence spectrum of refractive-index fluctuations. Several analytic formulae for the heterodyne detection system using the partially coherent Gaussian Schell-model beam are presented. Based on Tatarskii spectrum model, some numerical results are given for the variation in the heterodyne efficiency with the misalignment angle, detector diameter, turbulence conditions, and parameters of the overlapping beams. According to the numerical results, we find that the turbulent atmosphere degrades the heterodyne efficiency significantly, and the variation in heterodyne efficiency is even slower against the misalignment angle in turbulence. For the deterministic received signal and the detector, the performance of the heterodyne detection can be adjusted by controlling the local oscillator signal parameters.

  1. The performance of the poloidal divertor experiment neutral beam wall armor

    SciTech Connect

    Kugel, H.W.; Eubank, H.P.; Kozub, T.A.; Williams, M.D.; Ulrickson, M.

    1986-05-01

    During 2 yr of experimental operations, the Poloidal Divertor Experiment (PDX) inner wall neutral beam graphite armor provided protection for perpendicular heating injections into normal and disruptive plasmas as well as injection in the absence of plasma for special experiments, calibrations, and tests involving the optimization and development of the PDX neutral beam injection system. About 80 to 100 heating injections occurred per operating day, at a 360-s duty cycle, into plasmas of various densities, and typically approx. =5 to 50% of the injected neutral beam power was transmitted to the armor. More than 10/sup 3/ neutral beam pulses of 100- to 300-ms duration were injected in the absence of plasma at peak power densities of 1.5 to 3 kW/cm/sup 2/, yielding peak surface temperatures of 950 to 1550/sup 0/C. There was no significant impurity production attributable to beam heating of the armor, and no observed beam-induced, macroscopic surface damage. Many of the design constraints and performance issues encountered in this work are relevant to the design of larger fusion devices.

  2. Shear deformable deformation of carbon nanotubes based on a new analytical nonlocal Timoshenko beam nodel

    SciTech Connect

    Zhang, Jianming; Yang, Yang

    2015-03-10

    According to Hamilton’s principle, a new mathematical model and analytical solutions for nonlocal Timoshenko beam model (ANT) is established based on nonlocal elastic continuum theory when shear deformation and nonlocal effect are considered. The new ANT equilibrium equations and boundary conditions are derived for bending analysis of carbon nanotubes (CNTs) with simply supported, clamped and cantilever. The ANT deflection solutions demonstrate that the CNT stiffness is enhanced by the presence of nonlocal stress effects. Furthermore, the new ANT model concluded verifiable bending behaviors for a cantilever CNT with point load at the free end, which depends on the strength of nonlocal stress. Therefore, this new model will gives a better prediction for mechanical behaviors of nanostructures.

  3. Quantification of the Relative Biological Effectiveness for Ion Beam Radiotherapy: Direct Experimental Comparison of Proton and Carbon Ion Beams and a Novel Approach for Treatment Planning

    SciTech Connect

    Elsaesser, Thilo; Weyrather, Wilma K.; Friedrich, Thomas; Durante, Marco; Iancu, Gheorghe; Kraemer, Michael; Kragl, Gabriele; Brons, Stephan; Winter, Marcus; Weber, Klaus-Josef; Scholz, Michael

    2010-11-15

    Purpose: To present the first direct experimental in vitro comparison of the biological effectiveness of range-equivalent protons and carbon ion beams for Chinese hamster ovary cells exposed in a three-dimensional phantom using a pencil beam scanning technique and to compare the experimental data with a novel biophysical model. Methods and Materials: Cell survival was measured in the phantom after irradiation with two opposing fields, thus mimicking the typical patient treatment scenario. The novel biophysical model represents a substantial extension of the local effect model, previously used for treatment planning in carbon ion therapy for more than 400 patients, and potentially can be used to predict effectiveness of all ion species relevant for radiotherapy. A key feature of the new approach is the more sophisticated consideration of spatially correlated damage induced by ion irradiation. Results: The experimental data obtained for Chinese hamster ovary cells clearly demonstrate that higher cell killing is achieved in the target region with carbon ions as compared with protons when the effects in the entrance channel are comparable. The model predictions demonstrate agreement with these experimental data and with data obtained with helium ions under similar conditions. Good agreement is also achieved with relative biological effectiveness values reported in the literature for other cell lines for monoenergetic proton, helium, and carbon ions. Conclusion: Both the experimental data and the new modeling approach are supportive of the advantages of carbon ions as compared with protons for treatment-like field configurations. Because the model predicts the effectiveness for several ion species with similar accuracy, it represents a powerful tool for further optimization and utilization of the potential of ion beams in tumor therapy.

  4. Measurements of the performance of a beam condition monitor prototype in a 5 GeV electron beam

    NASA Astrophysics Data System (ADS)

    Hempel, M.; Afanaciev, K.; Burtowy, P.; Dabrowski, A.; Henschel, H.; Idzik, M.; Karacheban, O.; Lange, W.; Leonard, J.; Levy, I.; Lohmann, W.; Pollak, B.; Przyborowski, D.; Ryjov, V.; Schuwalow, S.; Stickland, D.; Walsh, R.; Zagozdzinska, A.

    2016-08-01

    The Fast Beam Conditions Monitor, BCM1F, in the Compact Muon Solenoid, CMS, experiment was operated since 2008 and delivered invaluable information on the machine induced background in the inner part of the CMS detector supporting a safe operation of the inner tracker and high quality data. Due to the shortening of the time between two bunch crossings from 50 ns to 25 ns and higher expected luminosity at the Large Hadron Collider, LHC, in 2015, BCM1F needed an upgrade to higher bandwidth. In addition, BCM1F is used as an on-line luminometer operated independently of CMS. To match these requirements, the number of single crystal diamond sensors was enhanced from 8 to 24. Each sensor is subdivided into two pads, leading to 48 readout channels. Dedicated fast front-end ASICs were developed in 130 nm technology, and the back-end electronics is completely upgraded. An assembled prototype BCM1F detector comprising sensors, a fast front-end ASIC and optical analog readout was studied in a 5 GeV electron beam at the DESY-II accelerator. Results on the performance are given.

  5. Enhanced Performance Assessment System (EPAS) for carbon sequestration.

    SciTech Connect

    Wang, Yifeng; Sun, Amy Cha-Tien; McNeish, Jerry A.; Dewers, Thomas A.; Hadgu, Teklu; Jove-Colon, Carlos F.

    2010-09-01

    Carbon capture and sequestration (CCS) is an option to mitigate impacts of atmospheric carbon emission. Numerous factors are important in determining the overall effectiveness of long-term geologic storage of carbon, including leakage rates, volume of storage available, and system costs. Recent efforts have been made to apply an existing probabilistic performance assessment (PA) methodology developed for deep nuclear waste geologic repositories to evaluate the effectiveness of subsurface carbon storage (Viswanathan et al., 2008; Stauffer et al., 2009). However, to address the most pressing management, regulatory, and scientific concerns with subsurface carbon storage (CS), the existing PA methodology and tools must be enhanced and upgraded. For example, in the evaluation of a nuclear waste repository, a PA model is essentially a forward model that samples input parameters and runs multiple realizations to estimate future consequences and determine important parameters driving the system performance. In the CS evaluation, however, a PA model must be able to run both forward and inverse calculations to support optimization of CO{sub 2} injection and real-time site monitoring as an integral part of the system design and operation. The monitoring data must be continually fused into the PA model through model inversion and parameter estimation. Model calculations will in turn guide the design of optimal monitoring and carbon-injection strategies (e.g., in terms of monitoring techniques, locations, and time intervals). Under the support of Laboratory-Directed Research & Development (LDRD), a late-start LDRD project was initiated in June of Fiscal Year 2010 to explore the concept of an enhanced performance assessment system (EPAS) for carbon sequestration and storage. In spite of the tight time constraints, significant progress has been made on the project: (1) Following the general PA methodology, a preliminary Feature, Event, and Process (FEP) analysis was performed for

  6. Crystalline magnetic carbon nanoparticle assisted photothermal delivery into cells using CW near-infrared laser beam

    NASA Astrophysics Data System (ADS)

    Gu, Ling; Koymen, Ali R.; Mohanty, Samarendra K.

    2014-05-01

    Efficient and targeted delivery of impermeable exogenous material such as small molecules, proteins, and plasmids into cells in culture as well as in vivo is of great importance for drug, vaccine and gene delivery for different therapeutic strategies. Though advent of optoporation by ultrafast laser microbeam has allowed spatial targeting in cells, the requirement of high peak power to create holes on the cell membrane is not practical and also challenging in vivo. Here, we report development and use of uniquely non-reactive crystalline magnetic carbon nanoparticles (CMCNPs) for photothermal delivery (PTD) of impermeable dyes and plasmids encoding light-sensitive proteins into cells using low power continuous wave near-infrared (NIR) laser beam. Further, we utilized the magnetic nature of these CMCNPs to localize them in desired region by external magnetic field, thus minimizing the required number of nanoparticles. We discovered that irradiation of the CMCNPs near the desired cell(s) with NIR laser beam leads to temperature rise that not only stretch the cell-membrane to ease delivery, it also creates fluid flow to allow mobilization of exogenous substances to the delivery. Due to significant absorption properties of the CMCNPs in the NIR therapeutic window, PTD under in vivo condition is highly possible.

  7. Cost and performance of activated carbon injection for mercury control

    SciTech Connect

    2006-08-15

    Activated carbon injection (ACI) is one technology being developed to absorb mercury from mercury emitted from coal-fired power plants. In 2003/04, the USDOE and NETL selected 14 projects to test and evaluate mercury control technologies. While field testing is still ongoing, DOE/NETL recently completed an economic analysis of mercury control for six test sites spanning three ACI variations - conventional powdered activated carbon (PAC), brominated PAC and conventional PAC combined with a sorbent enhancement additive (SEA) applied to the coal. To evaluate the progress of the field testing program and discern the performance of ACI, a data adjustment methodology was developed to account for baseline methane capture. This data were used to perform economic analyses to achieve low, mid and high levels of mercury control. The costs are given in the article. Full details are available on the DOE/NETL website, www.netl.doe.gov. 2 figs., 1 photo.

  8. Fabrication of carbon nanotube emitters on the graphite rod and their high field emission performance

    SciTech Connect

    Sun, Yuning; Hoon Shin, Dong; Nam Yun, Ki; Song, Yenan; Saito, Yahachi; Jin Lee, Cheol

    2014-01-27

    Carbon nanotube (CNT) emitters with small emission area were fabricated on graphite rods using CNT films. By introducing the edge polishing process, the field emission performance of the CNT emitter was much improved, which showed a very high emission current of 6.34 mA (1.6 A/cm{sup 2}) under an applied electric field of 5.3 V/μm. It also indicates good long-term emission stability, which reveals no degradation in the emission current for 20 h. The emission patterns demonstrate uniform and well-focused electron beam spots. The enhanced field emission performance is mainly attributed to the suppressed edge emission after the edge polishing process.

  9. The Interaction of Functional and Dysfunctional Emotions during Balance Beam Performance

    ERIC Educational Resources Information Center

    Cottyn, Jorge; De Clercq, Dirk; Crombez, Geert; Lenoir, Matthieu

    2012-01-01

    The interaction between functional and dysfunctional emotions, as one of the major tenets of the Individual Zones of Optimal Functioning (IZOF) model (Hanin, 2000), was studied in a sport specific setting. Fourteen female gymnasts performed three attempts of a compulsory balance beam routine at three different heights. Heart rate and self-report…

  10. Curative treatment of Stage I non-small-cell lung cancer with carbon ion beams using a hypofractionated regimen

    SciTech Connect

    Miyamoto, Tadaaki . E-mail: t_miyamt@nirs.go.jp; Baba, Masayuki; Yamamoto, Naoyoshi; Koto, Masashi; Sugawara, Toshiyuki; Yashiro, Tomoyasu; Kadono, Kennoshuke; Ezawa, Hidefumi; Tsujii, Hirohiko; Mizoe, Jun-Etsu; Yoshikawa, Kyosan; Kandatsu, Susumu; Fujisawa, Takehiko

    2007-03-01

    Purpose: A phase I/II study on carbon ion radiotherapy for Stage I non-small-cell lung cancer (NSCLC) was first conducted between 1994 and 1999 and determined the optimal dose. Second, a Phase II study using the optimal dose was performed. The purpose of the present study was to clarify the local control and 5-year survival rates. Methods and Materials: Between April 1999 and December 2000, 50 patients with 51 primary lesions were treated. Using a fixed dose of 72 GyE in nine fractions over 3 weeks, the primary tumors were irradiated with carbon ion beams alone. The average age of the patients was 74.5 years. Thirty-three (66%) of these were medically inoperable. Local control and survival were determined by using the Kaplan-Meier method and the data were statistically processed by using the log-rank test. Results: All patients were observed for a minimum of 5 years or until death with a median follow-up time of 59.2 months (range, 6.0-83.0 months). The local control rate for all patients was 94.7%. The patients' 5-year cause-specific survival rate was 75.7% (IA: 89.4; IB: 55.1), and overall survival 50.0% (IA: 55.2; IB: 42.9). No toxic reactions in the lung greater than Grade 3 were detected. Conclusions: Carbon ion radiotherapy, a new treatment modality with superior benefits in terms of quality of life and activity of daily living, has been proven as a valid alternative to surgery for Stage I NSCLC and to offer particular benefits, especially for elderly and inoperable patients.

  11. Qualitative and quantitative difference in mutation induction between carbon- and neon-ion beams in normal human cells.

    PubMed

    Suzuki, Masao; Tsuruoka, Chizuru; Kanai, Tatsuaki; Kato, Takeshi; Yatagai, Fumio; Watanabe, Masami

    2003-12-01

    We investigated the difference in cell-killing effect and mutation induction between carbon- and neon-ion beams in normal human cells. Carbon- and neon-ion beams were accelerated by the Riken Ring Cyclotron (RRC) at the Institute of Physical and Chemical Research in Japan. Cell-killing effect was measured as the reproductive cell death using the colony formation assay. Mutation induction at the HPRT locus was detected to measure 6-thioguanine-resistant clones. The mutation spectrum of the deletion pattern of exons of induced mutants was analyzed using the multiplex polymerase chain reaction (PCR). Cell-killing effect was almost the same between carbon- and neon-ion beams with similar linear energy transfer (LET) values, while there observed a large difference in mutation frequency. Furthermore, in the case of neon-ion beams 60% of mutants showed total deletions and 35-40% showed partial deletions, while 95-100% of carbon-ion induced mutants showed total deletions. The results suggest that different ion species may cause qualitative and quantitative difference in mutation induction even if the LET values are similar.

  12. Chromosome aberrations in human lymphocytes from the plateau region of the Bragg curve for a carbon-ion beam

    NASA Astrophysics Data System (ADS)

    Manti, L.; Durante, M.; Grossi, G.; Pugliese, M.; Scampoli, P.; Gialanella, G.

    2007-06-01

    Radiotherapy with high-energy carbon ion beams can be more advantageous compared to photons because of better physical dose distribution and higher biological efficiency in tumour cell sterilization. Despite enhanced normal tissue sparing, damage incurred by normal cells at the beam entrance is unavoidable and may affect the progeny of surviving cells in the form of inheritable cytogenetic alterations. Furthermore, the quality of the beam along the Bragg curve is modified by nuclear fragmentation of projectile and target nuclei in the body. We present an experimental approach based on the use of a polymethylmethacrylate (PMMA) phantom that allows the simultaneous exposure to a particle beam of several biological samples positioned at various depths along the beam path. The device was used to measure the biological effectiveness of a 60 MeV/amu carbon-ion beam at inducing chromosomal aberrations in G0-human peripheral blood lymphocytes. Chromosome spreads were obtained from prematurely condensed cells and all structural aberration types were scored in Fluorescence in situ Hybridization (FISH)-painted chromosomes 1 and 2. Our results show a marked increase with depth in the aberration frequency prior to the Bragg peak, which is consistent with a linear energy transfer (LET)-dependent increase in biological effectiveness.

  13. Improvement of capacitive performances of symmetric carbon/carbon supercapacitors by addition of nanostructured polypyrrole powder

    NASA Astrophysics Data System (ADS)

    Benhaddad, L.; Gamby, J.; Makhloufi, L.; Pailleret, A.; Pillier, F.; Takenouti, H.

    2016-03-01

    A nanostructured polypyrrole powder was synthesized in a previous work from the oxidation of pyrrole by a nanostructured MnO2 powder used simultaneously as an oxidizing agent and a sacrificial template in a redox heterogeneous mechanism. In this study, this original PPy powder was used as an active additive material with different ratio in carbon/carbon symmetrical supercapacitors whose performances were studied by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) using a Swagelok-type cell. From the EIS spectra, the complex capacitance was extracted using a model involving two Cole-Cole type complex capacitances linked in series. The specific capacitance values evaluated by EIS and cyclic voltammetry are in a good agreement between them. The results show that the addition of nanostructured polypyrrole powder improves significantly the specific capacitance of the carbon electrode and consequently the performances of carbon/carbon supercapacitors. The original and versatile synthesis method used to produce this polypyrrole powder appears to be attractive for large scale production of promising additives for electrode materials of supercapacitors.

  14. Experimental Study on the Flexural Performance of Parallel Strand Bamboo Beams

    PubMed Central

    Zhou, Aiping; Bian, Yuling

    2014-01-01

    Searching for materials to provide proper housing with less emission and low energy becomes an urgent demand with the ever-growing population. Bamboo has gained a reputation as an ecofriendly, highly renewable source of material. Parallel Strand Bamboo (PSB) is a new biocomposite made of bamboo strips which has superiority performances than wood products. It has attracted considerable interests as a sustainable alternative for more traditional building materials. But the mechanical performance study of PSB as construction materials is still inadequate. Also, the structural behavior of PSB is not quite understood as conventional construction materials, which results in the difficulties to predict the performances of PSB structural members. To achieve this purpose, 4-point bending experiments for PSB beams were carried out. The flexural performances, mode of failure in bending, and the damage mechanism of PSB beams were investigated in this paper. PMID:24701141

  15. Increased Tensile Strength of Carbon Nanotube Yarns and Sheets through Chemical Modification and Electron Beam Irradiation

    NASA Technical Reports Server (NTRS)

    Miller, Sandi G.; Williams, Tiffany S.; Baker, James S.; Sola, Francisco; Lebron-Colon, Marisabel; McCorkle, Linda S.; Wilmoth, Nathan G.; Gaier, James; Chen, Michelle; Meador, Michael A.

    2014-01-01

    The inherent strength of individual carbon nanotubes offers considerable opportunity for the development of advanced, lightweight composite structures. Recent work in the fabrication and application of carbon nanotube (CNT) forms such as yarns and sheets has addressed early nanocomposite limitations with respect to nanotube dispersion and loading; and has pushed the technology toward structural composite applications. However, the high tensile strength of an individual CNT has not directly translated to macro-scale CNT forms where bulk material strength is limited by inter-tube electrostatic attraction and slippage. The focus of this work was to assess post processing of CNT sheet and yarn to improve the macro-scale strength of these material forms. Both small molecule functionalization and e-beam irradiation was evaluated as a means to enhance tensile strength and Youngs modulus of the bulk CNT material. Mechanical testing results revealed a tensile strength increase in CNT sheets by 57 when functionalized, while an additional 48 increase in tensile strength was observed when functionalized sheets were irradiated; compared to unfunctionalized sheets. Similarly, small molecule functionalization increased yarn tensile strength up to 25, whereas irradiation of the functionalized yarns pushed the tensile strength to 88 beyond that of the baseline yarn.

  16. One-dimensional carbon nanostructures for terahertz electron-beam radiation

    NASA Astrophysics Data System (ADS)

    Tantiwanichapan, Khwanchai; Swan, Anna K.; Paiella, Roberto

    2016-06-01

    One-dimensional carbon nanostructures such as nanotubes and nanoribbons can feature near-ballistic electronic transport over micron-scale distances even at room temperature. As a result, these materials provide a uniquely suited solid-state platform for radiation mechanisms that so far have been the exclusive domain of electron beams in vacuum. Here we consider the generation of terahertz light based on two such mechanisms, namely, the emission of cyclotronlike radiation in a sinusoidally corrugated nanowire (where periodic angular motion is produced by the mechanical corrugation rather than an externally applied magnetic field), and the Smith-Purcell effect in a rectilinear nanowire over a dielectric grating. In both cases, the radiation properties of the individual charge carriers are investigated via full-wave electrodynamic simulations, including dephasing effects caused by carrier collisions. The overall light output is then computed with a standard model of charge transport for two particularly suitable types of carbon nanostructures, i.e., zigzag graphene nanoribbons and armchair single-wall nanotubes. Relatively sharp emission peaks at geometrically tunable terahertz frequencies are obtained in each case. The corresponding output powers are experimentally accessible even with individual nanowires, and can be scaled to technologically significant levels using array configurations. These radiation mechanisms therefore represent a promising paradigm for light emission in condensed matter, which may find important applications in nanoelectronics and terahertz photonics.

  17. Measurement of characteristic prompt gamma rays emitted from oxygen and carbon in tissue-equivalent samples during proton beam irradiation

    NASA Astrophysics Data System (ADS)

    Polf, Jerimy C.; Panthi, Rajesh; Mackin, Dennis S.; McCleskey, Matt; Saastamoinen, Antti; Roeder, Brian T.; Beddar, Sam

    2013-09-01

    The purpose of this work was to characterize how prompt gamma (PG) emission from tissue changes as a function of carbon and oxygen concentration, and to assess the feasibility of determining elemental concentration in tissues irradiated with proton beams. For this study, four tissue-equivalent water-sucrose samples with differing densities and concentrations of carbon, hydrogen, and oxygen were irradiated with a 48 MeV proton pencil beam. The PG spectrum emitted from each sample was measured using a high-purity germanium detector, and the absolute detection efficiency of the detector, average beam current, and delivered dose distribution were also measured. Changes to the total PG emission from 12C (4.44 MeV) and 16O (6.13 MeV) per incident proton and per Gray of absorbed dose were characterized as a function of carbon and oxygen concentration in the sample. The intensity of the 4.44 MeV PG emission per incident proton was found to be nearly constant for all samples regardless of their carbon concentration. However, we found that the 6.13 MeV PG emission increased linearly with the total amount (in grams) of oxygen irradiated in the sample. From the measured PG data, we determined that 1.64 × 107 oxygen PGs were emitted per gram of oxygen irradiated per Gray of absorbed dose delivered with a 48 MeV proton beam. These results indicate that the 6.13 MeV PG emission from 16O is proportional to the concentration of oxygen in tissue irradiated with proton beams, showing that it is possible to determine the concentration of oxygen within tissues irradiated with proton beams by measuring 16O PG emission.

  18. Development and characterization of a 2D scintillation detector for quality assurance in scanned carbon ion beams

    NASA Astrophysics Data System (ADS)

    Tamborini, A.; Raffaele, L.; Mirandola, A.; Molinelli, S.; Viviani, C.; Spampinato, S.; Ciocca, M.

    2016-04-01

    At the Centro Nazionale di Adroterapia Oncologica (CNAO Foundation), a two-dimensional high resolution scintillating dosimetry system has been developed and tested for daily Quality Assurance measurements (QA) in carbon ion radiotherapy with active scanning technique, for both single pencil beams and scanned fields produced by a synchrotron accelerator. The detector consists of a thin plane organic scintillator (25×25 cm2, 2 mm thick) coupled with a high spatial resolution CCD camera (0.25 mm) in a light-tight box. A dedicated Labview software was developed for image acquisition triggered with the beam extraction, data post-processing and analysis. The scintillator system was preliminary characterized in terms of short-term reproducibility (found to be within±0.5%), linearity with the number of particles (linear fit χ2 = 0.996) and dependence on particle flux (measured to be < 1.5 %). The detector was then tested for single beam spot measurements (Full Width at Half Maximum and position) and for 6×6 cm2 reference scanned field (determination of homogeneity) for carbon ions with energy from 115 MeV/u up to 400 MeV/u. No major differences in the investigated beam parameters measured with scintillator system and the radiochromic EBT3 reference films were observed. The system allows therefore real-time monitoring of the carbon ion beam relevant parameters, with a significant daily time saving with respect to films currently used. The results of this study show the suitability of the scintillation detector for daily QA in a carbon ion facility with an active beam delivery system.

  19. Measurement of characteristic prompt gamma rays emitted from oxygen and carbon in tissue-equivalent samples during proton beam irradiation

    PubMed Central

    Polf, Jerimy C; Panthi, Rajesh; Mackin, Dennis S; McCleskey, Matt; Saastamoinen, Antti; Roeder, Brian T; Beddar, Sam

    2013-01-01

    The purpose of this work was to characterize how prompt gamma (PG) emission from tissue changes as a function of carbon and oxygen concentration, and to assess the feasibility of determining elemental concentration in tissues irradiated with proton beams. For this study, four tissue-equivalent water-sucrose samples with differing densities and concentrations of carbon, hydrogen, and oxygen were irradiated with a 48 MeV proton pencil beam. The PG spectrum emitted from each sample was measured using a high-purity germanium detector, and the absolute detection efficiency of the detector, average beam current, and delivered dose distribution were also measured. Changes to the total PG emission from 12C (4.44 MeV) and 16O (6.13 MeV) per incident proton and per Gray of absorbed dose were characterized as a function of carbon and oxygen concentration in the sample. The intensity of the 4.44 MeV PG emission per incident proton was found to be nearly constant for all samples regardless of their carbon concentration. However, we found that the 6.13 MeV PG emission increased linearly with the total amount (in grams) of oxygen irradiated in the sample. From the measured PG data, we determined that 1.64 × 107 oxygen PGs were emitted per gram of oxygen irradiated per Gray of absorbed dose delivered with a 48 MeV proton beam. These results indicate that the 6.13 MeV PG emission from 16O is proportional to the concentration of oxygen in tissue irradiated with proton beams, showing that it is possible to determine the concentration of oxygen within tissues irradiated with proton beams by measuring 16O PG emission. PMID:23920051

  20. Dynamic response of RC beams strengthened with near surface mounted Carbon-FRP rods subjected to damage

    NASA Astrophysics Data System (ADS)

    Capozucca, R.; Blasi, M. G.; Corina, V.

    2015-07-01

    Near surface mounted (NSM) technique with fiber reinforced polymer (FRP) is becoming a common method in the strengthening of concrete beams. The availability of NSM FRP technique depends on many factors linked to materials and geometry - dimensions of the rods used, type of FRP material employed, rods’ surface configuration, groove size - and to adhesion between concrete and FRP rods. In this paper detection of damage is investigated measuring the natural frequency values of beam in the case of free-free ends. Damage was due both to reduction of adhesion between concrete and carbon-FRP rectangular and circular rods and cracking of concrete under static bending tests on beams. Comparison between experimental and theoretical frequency values evaluating frequency changes due to damage permits to monitor actual behaviour of RC beams strengthened by NSM CFRP rods.

  1. Optimization of free electron laser performance by dispersion-based beam-tilt correction

    NASA Astrophysics Data System (ADS)

    Guetg, Marc Walter; Beutner, Bolko; Prat, Eduard; Reiche, Sven

    2015-03-01

    Free electron lasers in the X-ray regime require a good slice alignment along the electron bunch to achieve their best performance. A transverse beam slice shift reduces this alignment and spoils projected emittance and optics. Coherent synchrotron radiation specifically for over-compression and transverse wakefields are major contributors to this. In the case of the large-bandwidth operation, based on a strictly monotonic energy chirp of the bunch, the here introduced correction additionally enhances the spectral bandwidth of the FEL pulse. Well-defined leaking of dispersion at places with a strictly monotonic longitudinal phase space can compensate a beam tilt. This work presents a way to characterize the beam tilt as well as a method to correct for it within a linear accelerator with at least one high dispersive section with corrector magnets.

  2. Performance of a Medium-Size Area nGEM Detector for Neutron Beam Diagnostics

    NASA Astrophysics Data System (ADS)

    Croci, G.; Cazzaniga, C.; Albani, G.; Muraro, A.; Claps, G.; Cavenago, M.; Grosso, G.; Murtas, F.; Pasqualotto, R.; Cippo, E. Perelli; Rebai, M.; Tardocchi, M.; Gorini, G.

    Fast neutron detectors with a sub-centimetric space resolution are required in order to qualify neutron beams in applications related to magnetically-controlled nuclear fusion plasmas and to spallation sources. Based on the results obtained with small area prototypes, the first medium-size (20 x 35.2 cm2 active area) nGEM detector has been realized for both the CNESM diagnostic system of the SPIDER NBI prototype for ITER and as a beam monitor for fast neutrons beam lines at spallation sources, too. The nGEM is a Triple GEM gaseous detector equipped with polyethylene layers used to convert fast neutrons into recoil protons through the elastic scattering process. This paper describes the performance of the medium-size nGEM detector tested at the VESUVIO beam line of the ISIS spallation source. Being this detector the actual largest area fast neutron detector based on the GEM technology, particular attention was paid in the study of detector response in different points over the active area. Measurements of GEM counting rate (both as a function of VGEM and of time) and of the capability of the detector to reconstruct the beam in different positions are presented. This detector serves as a basis for the realization of an even larger area detector that will be used in the MITICA NBI prototype for ITER that represents the evolution of SPIDER.

  3. Multifunctional structural supercapacitor composites based on carbon aerogel modified high performance carbon fiber fabric.

    PubMed

    Qian, Hui; Kucernak, Anthony R; Greenhalgh, Emile S; Bismarck, Alexander; Shaffer, Milo S P

    2013-07-10

    A novel multifunctional material has been designed to provide excellent mechanical properties while possessing a high electrochemical surface area suitable for electrochemical energy storage: structural carbon fiber fabrics are embedded in a continuous network of carbon aerogel (CAG) to form a coherent but porous monolith. The CAG-modification process was found to be scalable and to be compatible with a range of carbon fiber fabrics with different surface properties. The incorporation of CAG significantly increased the surface area of carbon fiber fabrics, and hence the electrochemical performance, by around 100-fold, resulting in a CAG-normalized specific electrode capacitance of around 62 F g(-1), determined by cyclic voltammetry in an aqueous electrolyte. Using an ionic liquid (IL) electrolyte, the estimated energy density increased from 0.003 to 1 Wh kg(-1), after introducing the CAG into the carbon fiber fabric. 'Proof-of-concept' multifunctional structural supercapacitor devices were fabricated using an IL-modified solid-state polymer electrolyte as a multifunctional matrix to provide both ionic transport and physical support for the primary fibers. Two CAG-impregnated carbon fabrics were sandwiched around an insulating separator to form a functioning structural electrochemical double layer capacitor composite. The CAG-modification not only improved the electrochemical surface area, but also reinforced the polymer matrix surrounding the primary fibers, leading to dramatic improvements in the matrix-dominated composite properties. Increases in in-plane shear strength and modulus, of up to 4.5-fold, were observed, demonstrating that CAG-modified structural carbon fiber fabrics have promise in both pure structural and multifunctional energy storage applications.

  4. Performance of the beam chamber vacuum system of K = 500 cyclotron at Variable Energy Cyclotron Centre Kolkata

    SciTech Connect

    Pal, Gautam DuttaGupta, Anjan; Chakrabarti, Alok

    2014-07-15

    The beam chamber of Variable Energy Cyclotron Centre, Kolkata's K = 500 superconducting cyclotron is pumped by liquid helium cooled cryopanel with liquid nitrogen cooled radiation shield. Performance of the vacuum system was evaluated by cooling the cryopanel assembly with liquid nitrogen and liquid helium. Direct measurement of beam chamber pressure is quite difficult because of space restrictions and the presence of high magnetic field. Pressure gauges were placed away from the beam chamber. The beam chamber pressure was evaluated using a Monte Carlo simulation software for vacuum system and compared with measurements. The details of the vacuum system, measurements, and estimation of pressure of the beam chamber are described in this paper.

  5. The Cycle Performance of a Hybrid Carbon Battery.

    PubMed

    Ahn, Sang-Yong; Kim, Sang-Chai; Jung, Ho-Young

    2016-02-01

    The behavior of a hybrid carbon battery is studied by using the Hg/Hg2SO4 reference electrode. The performance is confirmed in the discharge mode and a short-term cycle test. The capacities of the cell were 76.1, 60.3, 40.5, and 31.7 mAh at discharge currents of 150, 300, 600, and 900 mA, respectively. In the short-term cycle test, the capacity of the cell, 52.3 mAh at the first cycle, continuously increased to 66.7 mAh upon the fifth cycle (cut-off voltage 0.5 V in the deep cycle mode), indicating high feasibility of the hybrid carbon battery as a large-capacity energy storage system.

  6. Electrochemical performance of Si anode modified with carbonized gelatin binder

    NASA Astrophysics Data System (ADS)

    Jiang, Ying; Mu, Daobin; Chen, Shi; Wu, Borong; Cheng, Kailin; Li, Luyu; Wu, Feng

    2016-09-01

    Gelatin is alternatively adopted as the binder to modify Si anode coupling with its carbonization treatment. The binder can provide good bonding and uniform dispersion of the particles besides its environmental benignancy. Importantly, the carbonized binder containing nitrogen will be advantageous to the electrical conductivity of the electrode. In addition, some spaces are formed in the electrode due to the decomposition and shrinkage of the gelatin binder during heat-treatment, which may facilitate electrolyte penetration and accommodate volume change during cycling. All these merits make contribution to the good electrochemical performance of the modified Si electrode. It exhibits a reversible capacity of 990.3 mA h g-1 after 70 cycles at a current density of 100 mA g-1 and 904 mA h g-1 after 100 cycles at 400 mA g-1.

  7. Calibration and performance of a secondary emission chamber as a beam intensity monitor

    SciTech Connect

    Sivertz, M.; Chiang, I-H,; Rusek, A.

    2011-03-28

    We report on a study of the behavior of a secondary emission chamber (SEC). We show the dependence of the SEC signal on the charge and velocity of the primary beam for beams of protons, and heavy ions including Helium, Neon, Chlorine and Iron. We fill the SEC with a selection of different gases including Hydrogen, Helium, Nitrogen, Argon, and air, studying the SEC response when it is acting as an ion chamber. We also investigate the behavior of the SEC at intermediate pressures between 10{sup -8} torr and atmospheric pressure. The SEC uses thin conducting foils as the source and collector of electrons in a vacuum chamber. When charged particles traverse the vacuum chamber, they pass through a series of thin conducting foils, alternating anode and cathode. Ionization produced in the cathode foils travels across the intervening gap due to an applied high voltage and is collected on the anode foils. Electron production is very inefficient because most of the ionization in the foils remains trapped within the foil due to the short range of most delta-rays and the work function of the foil. It is this inefficiency that allows the SEC to operate at high dose rates and short pulse duration where the standard ion chambers cannot function reliably. The SEC was placed in the NSRL ion beam to receive a variety of heavy ion beams under different beam conditions. We used these ion beams to study the response of the SEC to different species of heavy ion, comparing with proton beams. We studied the response to beam of different energies, and as a function of different counting rate. We compared the behaviour of the SEC when operating under positive and negative high voltage. The SEC can operate as an ion chamber if it is filled with gas. We measured the response of the SEC when filled with a variety of gases, from Hydrogen to Helium, Nitrogen, Argon and air. The performance of the SEC as an ion chamber is compared with the standard NSRL ion chamber, QC3. By evacuating the SEC and

  8. Performance of laser tracking of small targets during turbulence and beam jitter

    NASA Astrophysics Data System (ADS)

    Steinvall, Ove

    2003-08-01

    Small target detection and tracking are important for laser radars in many applications such as Directed Infrared Countermeasures (DIRCM), fire control, target recognition and free space laser communications. The detection and tracking performance is depending on the mode of detection, signal to noise ratio, target signal statistics, beam jitter and turbulence induced intensity variations. We will show results of the rms tracking error vs SNR primarily for direct detection systems. For the general case of a certain signal and noise probability density functions (pdf) it is hard to obtain analytical solutions for the mean and variances of the estimates for the rms tracking error. We have therefore used numerical simulations to illustrate how the pdf and SNR will affect the tracking accuracy. A manifold of gamma functions and other pdf:s can be used to characterize the signal distributions to get a first hand on tracking performance. The results are presented as tracking errors vs the angular spot size of the laser beam in the tracking detector plane. We have also investigated the beam optimization problem for target detection and "power in bucket", that is maximizing the laser energy at the target. We find that there are optimum beam sizes (w) vs. the rms jitter (σ) and that optimum w/σ (minimizing the false alarm rate for a given detection probability Pd) typically fall in the region 1-3 depending on probability of detection and the representative pdf for the application in mind.

  9. An Overview of Brazilian Developments in Beamed Energy Aerospace Propulsion and Vehicle Performance Control

    NASA Astrophysics Data System (ADS)

    Minucci, M. A. S.

    2008-04-01

    Beamed energy propulsion and beamed energy vehicle performance control concepts are equally promising and challenging. In Brazil, the two concepts are being currently investigated at the Prof Henry T Nagamatsu Laboratory of Aerothermodynamics and Hypersonics, of the Institute for Advanced Studies—IEAv, in collaboration with the Rensselaer Polytechnic Institute—RPI, Troy, NY, and the United States Air force Research Laboratory-AFRL. Until recently, only laser energy addition for hypersonic flow control was being investigated at the Laboratory using a 0.3 m nozzle exit diameter hypersonic shock tunnel, T2, and two 7 joule CO2 TEA lasers. Flow visualization, model pressure and heat flux measurements of the laser energy addition perturbed flow around a model were produced as a result of this joint IEAv-RPI investigation. Presently, with the participation of AFRL and the newly commissioned 0.6 m. nozzle exit diameter hypersonic shock tunnel, T3, a more ambitious project is underway. Two 400 Joule Lumonics 620 CO2 TEA lasers will deliver a 20 cm X 25 cm propulsive laser beam to a complete laser propelled air breather/rocket hypersonic engine, located inside T3 test section. Schlieren photographs of the flow inside de engine as well as surface and heat flux measurements will be performed for free stream Mach numbers ranging from 6 to 25. The present paper discusses past, present and future Brazilian activities on beamed energy propulsion and related technologies.

  10. An Overview of Brazilian Developments in Beamed Energy Aerospace Propulsion and Vehicle Performance Control

    SciTech Connect

    Minucci, M. A. S.

    2008-04-28

    Beamed energy propulsion and beamed energy vehicle performance control concepts are equally promising and challenging. In Brazil, the two concepts are being currently investigated at the Prof Henry T Nagamatsu Laboratory of Aerothermodynamics and Hypersonics, of the Institute for Advanced Studies--IEAv, in collaboration with the Rensselaer Polytechnic Institute--RPI, Troy, NY, and the United States Air force Research Laboratory-AFRL. Until recently, only laser energy addition for hypersonic flow control was being investigated at the Laboratory using a 0.3 m nozzle exit diameter hypersonic shock tunnel, T2, and two 7 joule CO{sub 2} TEA lasers. Flow visualization, model pressure and heat flux measurements of the laser energy addition perturbed flow around a model were produced as a result of this joint IEAv-RPI investigation. Presently, with the participation of AFRL and the newly commissioned 0.6 m. nozzle exit diameter hypersonic shock tunnel, T3, a more ambitious project is underway. Two 400 Joule Lumonics 620 CO{sub 2} TEA lasers will deliver a 20 cm X 25 cm propulsive laser beam to a complete laser propelled air breather/rocket hypersonic engine, located inside T3 test section. Schlieren photographs of the flow inside de engine as well as surface and heat flux measurements will be performed for free stream Mach numbers ranging from 6 to 25. The present paper discusses past, present and future Brazilian activities on beamed energy propulsion and related technologies.

  11. Performance of standard fluoroscopy antiscatter grids in flat-detector-based cone-beam CT

    NASA Astrophysics Data System (ADS)

    Wiegert, Jens; Bertram, Matthias; Schaefer, Dirk; Conrads, Norbert; Timmer, Jan; Aach, Til; Rose, Georg

    2004-05-01

    In this paper, the performance of focused lamellar anti-scatter grids, which are currently used in fluoroscopy, is studied in order to determine guidelines of grid usage for flat detector based cone beam CT. The investigation aims at obtaining the signal to noise ratio improvement factor by the use of anti-scatter grids. First, the results of detailed Monte Carlo simulations as well as measurements are presented. From these the general characteristics of the impinging field of scattered and primary photons are derived. Phantoms modeling the head, thorax and pelvis regions have been studied for various imaging geometries with varying phantom size, cone and fan angles and patient-detector distances. Second, simulation results are shown for ideally focused and vacuum spaced grids as best case approach as well as for grids with realistic spacing materials. The grid performance is evaluated by means of the primary and scatter transmission and the signal to noise ratio improvement factor as function of imaging geometry and grid parameters. For a typical flat detector cone beam CT setup, the grid selectivity and thus the performance of anti-scatter grids is much lower compared to setups where the grid is located directly behind the irradiated object. While for small object-to-grid distances a standard grid improves the SNR, the SNR for geometries as used in flat detector based cone beam CT is deteriorated by the use of an anti-scatter grid for many application scenarios. This holds even for the pelvic region. Standard fluoroscopy anti-scatter grids were found to decrease the SNR in many application scenarios of cone beam CT due to the large patient-detector distance and have, therefore, only a limited benefit in flat detector based cone beam CT.

  12. Structural changes of electron and ion beam-deposited contacts in annealed carbon-based electrical devices.

    PubMed

    Batra, Nitin M; Patole, Shashikant P; Abdelkader, Ahmed; Anjum, Dalaver H; Deepak, Francis L; Costa, Pedro M F J

    2015-11-01

    The use of electron and ion beam deposition to make devices containing discrete nanostructures as interconnectors is a well-known nanofabrication process. Classically, one-dimensional materials such as carbon nanotubes (CNTs) have been electrically characterized by resorting to these beam deposition methods. While much attention has been given to the interconnectors, less is known about the contacting electrodes (or leads). In particular, the structure and chemistry of the electrode-interconnector interface is a topic that deserves more attention, as it is critical to understand the device behavior. Here, the structure and chemistry of Pt electrodes, deposited either with electron or ion beams and contacted to a CNT, are analyzed before and after thermally annealing the device in a vacuum. Free-standing Pt nanorods, acting as beam-deposited electrode models, are also characterized pre- and post-annealing. Overall, the as-deposited leads contain a non-negligible amount of amorphous carbon that is consolidated, upon heating, as a partially graphitized outer shell enveloping a Pt core. This observation raises pertinent questions regarding the definition of electrode-nanostructure interfaces in electrical devices, in particular long-standing assumptions of metal-CNT contacts fabricated by direct beam deposition methods.

  13. Structural changes of electron and ion beam-deposited contacts in annealed carbon-based electrical devices

    NASA Astrophysics Data System (ADS)

    Batra, Nitin M.; Patole, Shashikant P.; Abdelkader, Ahmed; Anjum, Dalaver H.; Deepak, Francis L.; Costa, Pedro M. F. J.

    2015-11-01

    The use of electron and ion beam deposition to make devices containing discrete nanostructures as interconnectors is a well-known nanofabrication process. Classically, one-dimensional materials such as carbon nanotubes (CNTs) have been electrically characterized by resorting to these beam deposition methods. While much attention has been given to the interconnectors, less is known about the contacting electrodes (or leads). In particular, the structure and chemistry of the electrode-interconnector interface is a topic that deserves more attention, as it is critical to understand the device behavior. Here, the structure and chemistry of Pt electrodes, deposited either with electron or ion beams and contacted to a CNT, are analyzed before and after thermally annealing the device in a vacuum. Free-standing Pt nanorods, acting as beam-deposited electrode models, are also characterized pre- and post-annealing. Overall, the as-deposited leads contain a non-negligible amount of amorphous carbon that is consolidated, upon heating, as a partially graphitized outer shell enveloping a Pt core. This observation raises pertinent questions regarding the definition of electrode-nanostructure interfaces in electrical devices, in particular long-standing assumptions of metal-CNT contacts fabricated by direct beam deposition methods.

  14. Performance of water jet cooled silicon monochromators in high power x-ray beams (abstract)

    NASA Astrophysics Data System (ADS)

    Berman, Lonny E.; Hart, Michael

    1992-01-01

    beam footprint were undertaken.3 For the line power loading situation, Bragg angle variations of up to 4 arcsec across the beam footprint were observed, resulting in near-perfect performance for the fundamental.4 The harmonic was more sensitive to these strains;4 the described adaptive methods were used to correct for them.5 For the point loading situation, Bragg angle variations of over 200 arcsec were measured, causing distorted fundamental and harmonic reflectivity curves; again, ≳90% compensation was achieved via adaptive techniques.6 The detailed results show that while, for silicon at room temperature, passive crystal cooling methods are sufficient for the present unfocused insertion device beam lines, adaptive methods will have to be considered for future insertion device beam lines. This work was supported in part by th

  15. Enhancing capacitive deionization performance of electrospun activated carbon nanofibers by coupling with carbon nanotubes.

    PubMed

    Dong, Qiang; Wang, Gang; Wu, Tingting; Peng, Senpei; Qiu, Jieshan

    2015-05-15

    Capacitive deionization (CDI) is an alternative, effective and environmentally friendly technology for desalination of brackish water. The performance of the CDI device is highly determined by the electrode materials. In this paper, a composite of carbon nanotubes (CNTs) embedded in activated carbon nanofiber (ACF) was prepared by a direct co-electrospinning way and subsequent CO2 activation. The introduction of CNTs can greatly improve the conductivity while the CO2-mediated activation can render the final product with high porosity. As such, the hybrid structure can provide an excellent storage space and pathways for ion adsorption and conduction. When evaluated as electrode materials for CDI, the as-prepared CNT/ACF composites with higher electrical conductivity and mesopore ratios exhibited higher electrosorption capacity and good regeneration performance in comparison with the pure ACF.

  16. A comparative study on the lithium-ion storage performances of carbon nanotubes and tube-in-tube carbon nanotubes.

    PubMed

    Xu, Yi-Jun; Liu, Xi; Cui, Guanglei; Zhu, Bo; Weinberg, Gisela; Schlögl, Robert; Maier, Joachim; Su, Dang Sheng

    2010-03-22

    A comparative study of the electrochemical performances of carbon nanotubes and tube-in-tube carbon nanotubes reveals a dependence effect of lithium-ion storage behavior on the detailed nanostructure of carbon nanotubes. In particular, the impurity that graphitic particles or graphene fragments inherently present in carbon nanotubes plays a crucial role in the lithium-ion storage capacity of the carbon nanotubes. Compared to acid-washed carbon nanotubes, the assembly of graphitic impurity fragments in the tube-in-tube structures hinders lithium-ion diffusion, thus drastically decreasing the rate performance of lithium-ion storage. Significantly, our results indicate that the lithium-ion storage capacity of carbon nanotubes as anode electrodes can be improved or controlled by optimizing the microstructure composition of impurity graphitic nanoparticles or graphene fragments in the matrix of the carbon nanotubes.

  17. High performance ultracapacitors with carbon nanomaterials and ionic liquids

    DOEpatents

    Lu, Wen; Henry, Kent Douglas

    2012-10-09

    The present invention is directed to the use of carbon nanotubes and/or electrolyte structures in various electrochemical devices, such as ultracapacitors having an ionic liquid electrolyte. The carbon nanotubes are preferably aligned carbon nanotubes. Compared to randomly entangled carbon nanotubes, aligned carbon nanotubes can have better defined pore structures and higher specific surface areas.

  18. A Precision Dose Control Circuit for Maskless E-Beam Lithography With Massively Parallel Vertically Aligned Carbon Nanofibers

    SciTech Connect

    Eliza, Sazia A.; Islam, Syed K; Rahman, Touhidur; Bull, Nora D; Blalock, Benjamin; Baylor, Larry R; Ericson, Milton Nance; Gardner, Walter L

    2011-01-01

    This paper describes a highly accurate dose control circuit (DCC) for the emission of a desired number of electrons from vertically aligned carbon nanofibers (VACNFs) in a massively parallel maskless e-beam lithography system. The parasitic components within the VACNF device cause a premature termination of the electron emission, resulting in underexposure of the photoresist. In this paper, we compensate for the effects of the parasitic components and noise while reducing the area of the chip and achieving a precise count of emitted electrons from the VACNFs to obtain the optimum dose for the e-beam lithography.

  19. Molten carbonate fuel cell networks: Principles, analysis, and performance

    NASA Astrophysics Data System (ADS)

    Wimer, J. G.; Williams, M. C.

    1993-01-01

    The chemical reactions in an internally reforming molten carbonate fuel cell (IRMCFC) are described and combined into the overall IRMCFC reaction. Thermodynamic and electrochemical principles are discussed, and structure and operation of fuel cell stacks are explained. In networking, multiple fuel cell stacks are arranged so that reactant streams are fed and recycled through stacks in series for higher reactant utilization and increased system efficiency. Advantages and performance of networked and conventional systems are compared, using ASPEN simulations. The concept of networking can be applied to any electrochemical membrane, such as that developed for hot gas cleanup in future power plants.

  20. Microdosimetric study for secondary neutrons in phantom produced by a 290 MeV/nucleon carbon beam.

    PubMed

    Endo, Satoru; Tanaka, Kenichi; Takada, Masashi; Onizuka, Yoshihiko; Miyahara, Nobuyuki; Sato, Tatsuhiko; Ishikawa, Masayori; Maeda, Naoko; Hayabuchi, Naofumi; Shizuma, Kiyoshi; Hoshi, Masaharu

    2007-09-01

    Absorbed doses from main charged-particle beams and charged-particle fragments have been measured with high accuracy for particle therapy, but there are few reports for doses from neutron components produced as fragments. This study describes the measurements on neutron doses produced by carbon beams; microdosimetric distributions of secondary neutrons produced by 290 MeV/nucleon carbon beams have been measured by using a tissue equivalent proportional counter at the Heavy Ion Medical Accelerator in Chiba, Japan at the National Institute of Radiological Sciences. The microdosimetric distributions of the secondary neutron were measured on the distal and lateral faces of a body-simulated acrylic phantom (300 mm height x 300 mm width x 253 mm thickness). To confirm the dose measurements, the neutron energy spectra produced by incident carbon beams in the acrylic phantom were simulated by the particle and heavy ion transport code system. The absorbed doses obtained by multiplying the simulated neutron energy spectra with the kerma factor calculated by MCNPX agree with the corresponding experimental data fairly well. Downstream of the Bragg peak, the ratio of the neutron dose to the carbon dose at the Bragg peak was found to be a maximum of 1.4 x 10(-4) and the ratio of neutron dose was a maximum of 3.0 x 10(-7) at a lateral face of the acrylic phantom. The ratios of neutrons to charged particle fragments were 11% to 89% in the absorbed doses at the lateral and the distal faces of the acrylic phantom. We can conclude that the treatment dose will not induce serious secondary neutron effects at distances greater than 90 mm from the Bragg peak in carbon particle therapy.

  1. Microdosimetric study for secondary neutrons in phantom produced by a 290 MeV/nucleon carbon beam

    SciTech Connect

    Endo, Satoru; Tanaka, Kenichi; Takada, Masashi; Onizuka, Yoshihiko; Miyahara, Nobuyuki; Sato, Tatsuhiko; Ishikawa, Masayori; Maeda, Naoko; Hayabuchi, Naofumi; Shizuma, Kiyoshi; Hoshi, Masaharu

    2007-09-15

    Absorbed doses from main charged-particle beams and charged-particle fragments have been measured with high accuracy for particle therapy, but there are few reports for doses from neutron components produced as fragments. This study describes the measurements on neutron doses produced by carbon beams; microdosimetric distributions of secondary neutrons produced by 290 MeV/nucleon carbon beams have been measured by using a tissue equivalent proportional counter at the Heavy Ion Medical Accelerator in Chiba, Japan at the National Institute of Radiological Sciences. The microdosimetric distributions of the secondary neutron were measured on the distal and lateral faces of a body-simulated acrylic phantom (300 mm heightx300 mm widthx253 mm thickness). To confirm the dose measurements, the neutron energy spectra produced by incident carbon beams in the acrylic phantom were simulated by the particle and heavy ion transport code system. The absorbed doses obtained by multiplying the simulated neutron energy spectra with the kerma factor calculated by MCNPX agree with the corresponding experimental data fairly well. Downstream of the Bragg peak, the ratio of the neutron dose to the carbon dose at the Bragg peak was found to be a maximum of 1.4x10{sup -4} and the ratio of neutron dose was a maximum of 3.0x10{sup -7} at a lateral face of the acrylic phantom. The ratios of neutrons to charged particle fragments were 11% to 89% in the absorbed doses at the lateral and the distal faces of the acrylic phantom. We can conclude that the treatment dose will not induce serious secondary neutron effects at distances greater than 90 mm from the Bragg peak in carbon particle therapy.

  2. Nitrated carbon nanoblisters for high-performance glucose dehydrogenase bioanodes.

    PubMed

    de Souza, João C P; Iost, Rodrigo M; Crespilho, Frank N

    2016-03-15

    Recently, many strategies are being explored for efficiently wiring glucose dehydrogenase (GDh) enzymes capable of glucose (fuel) oxidation. For instance, the use of GDh NAD(+)-dependent for glucose oxidation is of great interest in biofuel cell technology because the enzyme are unaffected by the presence of molecular oxygen commonly present in electrolyte. Here we present the fabrication of flexible carbon fibers modified with nitrated carbon nanoblisters and their application as high-performance GDh bioanodes. These bioelectrodes could electro-oxidize glucose at -360 mV (vs. Ag/AgClsat) in the presence of a molecular oxygen saturated electrolyte with current densities higher than 1.0 mAcm(-2) at 0.0 V. It is corroborated by open circuit potential, where a potential stabilization occurs at -150 mV in a long term stability current-transient experiment. This value is in agreement with the quasi-steady current obtained at very low scan rate (0.1 mVs(-1)), where the onset potential for glucose oxidation is -180 mV. X-ray photoelectron spectroscopy and scanning electron microscopy revealed that the nitrated blisters and edge-like carbon structures, enabling highly efficient enzyme immobilization and low overpotential for electron transfer, allowing for glucose oxidation with potential values close to the thermodynamic cofactor. PMID:26516686

  3. Pumpkin-Derived Porous Carbon for Supercapacitors with High Performance.

    PubMed

    Bai, Suying; Tan, Guangqun; Li, Xiaoqin; Zhao, Qian; Meng, Yan; Wang, Yujue; Zhang, Yongzhi; Xiao, Dan

    2016-06-21

    Pumpkin has been employed for the first time as a renewable, low-cost precursor for the preparation of porous carbon materials with excellent performance. Unlike most other precursors, pumpkin is rich in sugars and starch, and it has advantageous properties for large-scale production. The as-prepared materials adopted a unique morphology that consisted of numerous fused sphere-like carbon grains with a high specific surface area (2968 m(2)  g(-1) ), abundant micro and mesopores, and excellent electrochemical properties. The pumpkin-derived activated carbon (PAC) material not only exhibited a high specific capacitance of 419 F g(-1) , but also showed considerable cycling stability, with 93.6 % retention after 10 000 cycles. Moreover, a symmetrical supercapacitor that was based on PAC showed a high energy density of 22.1 W h kg(-1) in aqueous electrolyte. These superior properties demonstrate that PAC holds great promise for applications in electrochemical energy-storage devices. PMID:27124360

  4. Nitrated carbon nanoblisters for high-performance glucose dehydrogenase bioanodes.

    PubMed

    de Souza, João C P; Iost, Rodrigo M; Crespilho, Frank N

    2016-03-15

    Recently, many strategies are being explored for efficiently wiring glucose dehydrogenase (GDh) enzymes capable of glucose (fuel) oxidation. For instance, the use of GDh NAD(+)-dependent for glucose oxidation is of great interest in biofuel cell technology because the enzyme are unaffected by the presence of molecular oxygen commonly present in electrolyte. Here we present the fabrication of flexible carbon fibers modified with nitrated carbon nanoblisters and their application as high-performance GDh bioanodes. These bioelectrodes could electro-oxidize glucose at -360 mV (vs. Ag/AgClsat) in the presence of a molecular oxygen saturated electrolyte with current densities higher than 1.0 mAcm(-2) at 0.0 V. It is corroborated by open circuit potential, where a potential stabilization occurs at -150 mV in a long term stability current-transient experiment. This value is in agreement with the quasi-steady current obtained at very low scan rate (0.1 mVs(-1)), where the onset potential for glucose oxidation is -180 mV. X-ray photoelectron spectroscopy and scanning electron microscopy revealed that the nitrated blisters and edge-like carbon structures, enabling highly efficient enzyme immobilization and low overpotential for electron transfer, allowing for glucose oxidation with potential values close to the thermodynamic cofactor.

  5. Performance of beryllium, carbon, and tungsten under intense thermal fluxes

    NASA Astrophysics Data System (ADS)

    Linke, J.; Akiba, M.; Bolt, H.; Breitbach, G.; Duwe, R.; Makhankov, A.; Ovchinnikov, I.; Rödig, M.; Wallura, E.

    1997-02-01

    Transient heat loads on a millisecond timescale with deposited energy densities beyond 1 MJ m -2 have been simulated in a plasma accelerator facility (VIKA) and in two high power electron beam teststands (JUDITH, JEBIS). Main objective of these experiments was to study and to compare the behaviour of different plasma facing materials (Be, CFC, W) under heat loads which occur during disruptions in future thermonuclear fusion reactors such as ITER. In these tests special attention was paid to the thermal shock resistance, the processes during melt layer formation, and the resulting material erosion. To perform these tests specific loading techniques and diagnostics have been developed and applied. Among these are high heat flux loading experiments at elevated temperatures ( T > DBTT) of the test coupons, fast surface pyrometry, and reliable techniques for the quantification of the absorbed energy.

  6. Design and performance of beam test electronics for the PHENIX Multiplicity Vertex Detector

    SciTech Connect

    Britton, C.L. Jr.; Bryan, W.L.; Emery, M.S.

    1996-12-31

    The system architecture and test results of the custom circuits and beam test system for the Multiplicity-Vertex Detector (MVD) for the PHENIX detector collaboration at the Relativistic Heavy Ion Collider (RHIC) are presented in this paper. The final detector per-channel signal processing chain will consist of a preamplifier-gain stage, a current-mode summed multiplicity discriminator, a 64-deep analog memory (simultaneous read-write), a post-memory analog correlator, and a 10-bit 5 {mu}s ADC. The Heap Manager provides all timing control, data buffering, and data formatting for a single 256-channel multi-chip module (MCM). Each chip set is partitioned into 32-channel sets. Beam test (16-cell deep memory) performance for the various blocks will be presented as well as the ionizing radiation damage performance of the 1.2 {mu} n-well CMOS process used for preamplifier fabrication.

  7. Performance of portable XRF and micro-XRF on carbonates

    NASA Astrophysics Data System (ADS)

    de Winter, Niels; Sinnesael, Matthias; Makarona, Christina; Claeys, Philippe

    2016-04-01

    Variations in elemental abundances in various carbonate archives offer a wealth of paleoenvironmental proxy information. State of the art portable handheld X-Ray Fluorescence (pXRF) and laboratory micro X-Ray Fluorescence (μXRF) instruments provide a relatively inexpensive and fast way of acquiring elemental composition data. However, there are well-known issues and limitations regarding the conversion of XRF spectral data into elemental concentrations. This study aims to offer a guideline for the appropriate use of these XRF techniques for the study of carbonates. Using a certified calcium carbonate standard, accuracy and reproducibility of both a pXRF (Bruker AXS Tracer IV) and a μXRF (Bruker M4 Tornado) instrument are tested under various measurement conditions. The experimental set-up allowed for the variation of several parameters, including measurement area, integration time, quantification method and filter use. The effects on the accuracy and reproducibility of the quantified elemental abundance results are examined in order to investigate under which conditions both devices perform best in determining trace element abundances in natural carbonates. The limits of detection and quantification are evaluated for both instruments for a range of commonly used trace elements (e.g. Sr, Mg, Zn, Fe …). The quality of the XRF spectra is evaluated using spectral processing software. Additionally, different methods of quantification are discussed. As a result, optimized parameter combinations are proposed for a range of commonly used elements. Finally, a comparison between the two X-Ray Fluorescence instruments allows the evaluation of their respective advantages and disadvantages and helps to determine which technique is best suited for a specific research question.

  8. Performance of exponential coupler in the SPS with LHC type beam for transverse broadband instability analysis

    SciTech Connect

    de Maria,R.; Fox, J. D.; Hofle, W.; Kotzian, G.; Rumolo, G.; Salvant, B.; Wehrle, U.

    2009-05-25

    We present the performance and limitations of the SPS exponential coupler [1] for transverse instability measurements with LHC type beam. Data were acquired in 2008 in the SPS in the time domain with a bandwidth of up to 2.5 GHz. The data were filtered to extract the time evolution of transverse oscillations within the less than 5 ns long LHC type bunches. We describe the data filtering techniques and show the limitations of the pick-up due to propagating modes.

  9. Conversion from dose-to-graphite to dose-to-water in an 80 MeV/A carbon ion beam.

    PubMed

    Rossomme, S; Palmans, H; Shipley, D; Thomas, R; Lee, N; Romano, F; Cirrone, P; Cuttone, G; Bertrand, D; Vynckier, S

    2013-08-21

    Based on experiments and numerical simulations, a study is carried out pertaining to the conversion of dose-to-graphite to dose-to-water in a carbon ion beam. This conversion is needed to establish graphite calorimeters as primary standards of absorbed dose in these beams. It is governed by the water-to-graphite mass collision stopping power ratio and fluence correction factors, which depend on the particle fluence distributions in each of the two media. The paper focuses on the experimental and numerical determination of this fluence correction factor for an 80 MeV/A carbon ion beam. Measurements have been performed in the nuclear physics laboratory INFN-LNS in Catania (Sicily, Italy). The numerical simulations have been made with a Geant4 Monte Carlo code through the GATE simulation platform. The experimental data are in good agreement with the simulated results for the fluence correction factors and are found to be close to unity. The experimental values increase with depth reaching 1.010 before the Bragg peak region. They have been determined with an uncertainty of 0.25%. Different numerical results are obtained depending on the level of approximation made in calculating the fluence correction factors. When considering carbon ions only, the difference between measured and calculated values is maximal just before the Bragg peak, but its value is less than 1.005. The numerical value is close to unity at the surface and increases to 1.005 near the Bragg peak. When the fluence of all charged particles is considered, the fluence correction factors are lower than unity at the surface and increase with depth up to 1.025 before the Bragg peak. Besides carbon ions, secondary particles created due to nuclear interactions have to be included in the analysis: boron ions ((10)B and (11)B), beryllium ions ((7)Be), alpha particles and protons. At the conclusion of this work, we have the conversion of dose-to-graphite to dose-to-water to apply to the response of a graphite

  10. Conversion from dose-to-graphite to dose-to-water in an 80 MeV/A carbon ion beam.

    PubMed

    Rossomme, S; Palmans, H; Shipley, D; Thomas, R; Lee, N; Romano, F; Cirrone, P; Cuttone, G; Bertrand, D; Vynckier, S

    2013-08-21

    Based on experiments and numerical simulations, a study is carried out pertaining to the conversion of dose-to-graphite to dose-to-water in a carbon ion beam. This conversion is needed to establish graphite calorimeters as primary standards of absorbed dose in these beams. It is governed by the water-to-graphite mass collision stopping power ratio and fluence correction factors, which depend on the particle fluence distributions in each of the two media. The paper focuses on the experimental and numerical determination of this fluence correction factor for an 80 MeV/A carbon ion beam. Measurements have been performed in the nuclear physics laboratory INFN-LNS in Catania (Sicily, Italy). The numerical simulations have been made with a Geant4 Monte Carlo code through the GATE simulation platform. The experimental data are in good agreement with the simulated results for the fluence correction factors and are found to be close to unity. The experimental values increase with depth reaching 1.010 before the Bragg peak region. They have been determined with an uncertainty of 0.25%. Different numerical results are obtained depending on the level of approximation made in calculating the fluence correction factors. When considering carbon ions only, the difference between measured and calculated values is maximal just before the Bragg peak, but its value is less than 1.005. The numerical value is close to unity at the surface and increases to 1.005 near the Bragg peak. When the fluence of all charged particles is considered, the fluence correction factors are lower than unity at the surface and increase with depth up to 1.025 before the Bragg peak. Besides carbon ions, secondary particles created due to nuclear interactions have to be included in the analysis: boron ions ((10)B and (11)B), beryllium ions ((7)Be), alpha particles and protons. At the conclusion of this work, we have the conversion of dose-to-graphite to dose-to-water to apply to the response of a graphite

  11. Beam width and transmitter power adaptive to tracking system performance for free-space optical communication.

    PubMed

    Arnon, S; Rotman, S; Kopeika, N S

    1997-08-20

    The basic free-space optical communication system includes at least two satellites. To communicate between them, the transmitter satellite must track the beacon of the receiver satellite and point the information optical beam in its direction. Optical tracking and pointing systems for free space suffer during tracking from high-amplitude vibration because of background radiation from interstellar objects such as the Sun, Moon, Earth, and stars in the tracking field of view or the mechanical impact from satellite internal and external sources. The vibrations of beam pointing increase the bit error rate and jam communication between the two satellites. One way to overcome this problem is to increase the satellite receiver beacon power. However, this solution requires increased power consumption and weight, both of which are disadvantageous in satellite development. Considering these facts, we derive a mathematical model of a communication system that adapts optimally the transmitter beam width and the transmitted power to the tracking system performance. Based on this model, we investigate the performance of a communication system with discrete element optical phased array transmitter telescope gain. An example for a practical communication system between a Low Earth Orbit Satellite and a Geostationary Earth Orbit Satellite is presented. From the results of this research it can be seen that a four-element adaptive transmitter telescope is sufficient to compensate for vibration amplitude doubling. The benefits of the proposed model are less required transmitter power and improved communication system performance. PMID:18259455

  12. Beam width and transmitter power adaptive to tracking system performance for free-space optical communication.

    PubMed

    Arnon, S; Rotman, S; Kopeika, N S

    1997-08-20

    The basic free-space optical communication system includes at least two satellites. To communicate between them, the transmitter satellite must track the beacon of the receiver satellite and point the information optical beam in its direction. Optical tracking and pointing systems for free space suffer during tracking from high-amplitude vibration because of background radiation from interstellar objects such as the Sun, Moon, Earth, and stars in the tracking field of view or the mechanical impact from satellite internal and external sources. The vibrations of beam pointing increase the bit error rate and jam communication between the two satellites. One way to overcome this problem is to increase the satellite receiver beacon power. However, this solution requires increased power consumption and weight, both of which are disadvantageous in satellite development. Considering these facts, we derive a mathematical model of a communication system that adapts optimally the transmitter beam width and the transmitted power to the tracking system performance. Based on this model, we investigate the performance of a communication system with discrete element optical phased array transmitter telescope gain. An example for a practical communication system between a Low Earth Orbit Satellite and a Geostationary Earth Orbit Satellite is presented. From the results of this research it can be seen that a four-element adaptive transmitter telescope is sufficient to compensate for vibration amplitude doubling. The benefits of the proposed model are less required transmitter power and improved communication system performance.

  13. Space-to-Space Power Beaming Enabling High Performance Rapid Geocentric Orbit Transfer

    NASA Technical Reports Server (NTRS)

    Dankanich, John W.; Vassallo, Corinne; Tadge, Megan

    2015-01-01

    The use of electric propulsion is more prevalent than ever, with industry pursuing all electric orbit transfers. Electric propulsion provides high mass utilization through efficient propellant transfer. However, the transfer times become detrimental as the delta V transitions from near-impulsive to low-thrust. Increasing power and therefore thrust has diminishing returns as the increasing mass of the power system limits the potential acceleration of the spacecraft. By using space-to-space power beaming, the power system can be decoupled from the spacecraft and allow significantly higher spacecraft alpha (W/kg) and therefore enable significantly higher accelerations while maintaining high performance. This project assesses the efficacy of space-to-space power beaming to enable rapid orbit transfer while maintaining high mass utilization. Concept assessment requires integrated techniques for low-thrust orbit transfer steering laws, efficient large-scale rectenna systems, and satellite constellation configuration optimization. This project includes the development of an integrated tool with implementation of IPOPT, Q-Law, and power-beaming models. The results highlight the viability of the concept, limits and paths to infusion, and comparison to state-of-the-art capabilities. The results indicate the viability of power beaming for what may be the only approach for achieving the desired transit times with high specific impulse.

  14. Recent Performance of the SNS H- ion source and low-energy beam transport system

    SciTech Connect

    Stockli, Martin P; Ewald, Kerry D; Han, Baoxi; Murray Jr, S N; Pennisi, Terry R; Piller, Chip; Santana, Manuel; Tang, Johnny Y; Welton, Robert F

    2014-01-01

    Recent measurements of the H beam current show that SNS is injecting about 55 mA into the RFQ compared to 45 mA in 2010. Since 2010, the H beam exiting the RFQ dropped from 40 mA to 34 mA, which is sufficient for 1 MW of beam power. To minimize the impact of the RFQ degradation, the service cycle of the best performing source was extended to 6 weeks. The only degradation is fluctuations in the electron dump voltage towards the end of some service cycles, a problem that is being investigated. Very recently, the RFQ was retuned, which partly restored its transmission. In addition, the electrostatic low-energy beam transport system was reengineered to double its heat sinking and equipped with a thermocouple that monitors the temperature of the ground electrode between the two Einzel lenses. The recorded data show that emissions from the source at high voltage dominate the heat load. Emissions from the partly Cs-covered first lens cause the temperature to peak several hours after starting up. On rare occasions, the temperature can also peak due to corona discharges between the center ground electrode and one of the lenses.

  15. Characterization of nanometer-scale porosity in reservoir carbonate rock by focused ion beam-scanning electron microscopy.

    PubMed

    Bera, Bijoyendra; Gunda, Naga Siva Kumar; Mitra, Sushanta K; Vick, Douglas

    2012-02-01

    Sedimentary carbonate rocks are one of the principal porous structures in natural reservoirs of hydrocarbons such as crude oil and natural gas. Efficient hydrocarbon recovery requires an understanding of the carbonate pore structure, but the nature of sedimentary carbonate rock formation and the toughness of the material make proper analysis difficult. In this study, a novel preparation method was used on a dolomitic carbonate sample, and selected regions were then serially sectioned and imaged by focused ion beam-scanning electron microscopy. The resulting series of images were used to construct detailed three-dimensional representations of the microscopic pore spaces and analyze them quantitatively. We show for the first time the presence of nanometer-scale pores (50-300 nm) inside the solid dolomite matrix. We also show the degree of connectivity of these pores with micron-scale pores (2-5 μm) that were observed to further link with bulk pores outside the matrix.

  16. Characterization of nanometer-scale porosity in reservoir carbonate rock by focused ion beam-scanning electron microscopy.

    PubMed

    Bera, Bijoyendra; Gunda, Naga Siva Kumar; Mitra, Sushanta K; Vick, Douglas

    2012-02-01

    Sedimentary carbonate rocks are one of the principal porous structures in natural reservoirs of hydrocarbons such as crude oil and natural gas. Efficient hydrocarbon recovery requires an understanding of the carbonate pore structure, but the nature of sedimentary carbonate rock formation and the toughness of the material make proper analysis difficult. In this study, a novel preparation method was used on a dolomitic carbonate sample, and selected regions were then serially sectioned and imaged by focused ion beam-scanning electron microscopy. The resulting series of images were used to construct detailed three-dimensional representations of the microscopic pore spaces and analyze them quantitatively. We show for the first time the presence of nanometer-scale pores (50-300 nm) inside the solid dolomite matrix. We also show the degree of connectivity of these pores with micron-scale pores (2-5 μm) that were observed to further link with bulk pores outside the matrix. PMID:22214656

  17. The Effect of the iBEAM Evo Carbon Fiber Tabletop on Skin Sparing

    SciTech Connect

    Simpson, John B. Godwin, Guy A.

    2011-10-01

    Replicating the attenuation properties of the treatment tabletop are of primary importance for accurate treatment planning; however, the effect of the tabletop on the skin-sparing properties of x-rays can be overlooked. Under some conditions, the reaction of skin to the radiation can be so serious as to be the dose-limiting organ for radiotherapy treatment. Hence, an understanding of the magnitude of the reduction in skin sparing is important. Because of the development of image-guided radiotherapy, modern tabletops have been developed without the use of metal supports that otherwise provided the necessary level of rigidity. Rigidity is instead provided by compressed foam within a carbon-fiber shell, which, although it provides artefact-free imaging and high levels of rigidity, has an adverse affect on the dose in the build-up region. Representative of this type is the iBEAM evo tabletop, whose effect on the skin dose was determined at 6-MV, 10-MV, and 18-MV x-rays. Skin dose was found to increase by 60-70% owing to the tabletop, with the effect increasing with field size and decreasing with energy. By considering an endpoint of erythema, a radiobiological advantage of selecting 10 MV over 6 MV for applicable treatments was demonstrated.

  18. Mutational effects of γ-rays and carbon ion beams on Arabidopsis seedlings.

    PubMed

    Yoshihara, Ryouhei; Nozawa, Shigeki; Hase, Yoshihiro; Narumi, Issay; Hidema, Jun; Sakamoto, Ayako N

    2013-11-01

    To assess the mutational effects of radiation on vigorously proliferating plant tissue, the mutation spectrum was analyzed with Arabidopsis seedlings using the plasmid-rescue method. Transgenic plants containing the Escherichia coli rpsL gene were irradiated with γ-rays and carbon ion beams (320-MeV (12)C(6+)), and mutations in the rpsL gene were analyzed. Mutant frequency increased significantly following irradiation by γ-rays, but not by 320-MeV (12)C(6+). Mutation spectra showed that both radiations increased the frequency of frameshifts and other mutations, including deletions and insertions, but only γ-rays increased the frequency of total base substitutions. These results suggest that the type of DNA lesions which cause base substitutions were less often induced by 320-MeV (12)C(6+) than by γ-rays in Arabidopsis seedlings. Furthermore, γ-rays never increased the frequencies of G:C to T:A or A:T to C:G transversions, which are caused by oxidized guanine; 320-MeV (12)C(6+), however, produced a slight increase in both transversions. Instead, γ-rays produced a significant increase in the frequency of G:C to A:T transitions. These results suggest that 8-oxoguanine has little effect on mutagenesis in Arabidopsis cells.

  19. Investigation of Performance Envelope for Phenolic Impregnated Carbon Ablator (PICA)

    NASA Technical Reports Server (NTRS)

    Agrawal, Parul; Prabhu, Dinesh; Milos, Frank S.; Stackpoole, Mairead

    2016-01-01

    The present work provides the results of a short exploratory study on the performance of Phenolic Impregnated Carbon Ablator, or PICA, at high heat flux and pressure in an arcjet facility at NASA Ames Research Center. The primary objective of the study was to explore the thermal response of PICA at cold-wall heat fluxes well in excess of 1500 W/cm (exp 2). Based on the results of a series of flow simulations, multiple PICA samples were tested at an estimated cold wall heat flux and stagnation pressure of 1800 W/cm (exp 2) and 130 kPa, respectively. All samples survived the test, and no failure was observed either during or after the exposure. The results indicate that PICA has a potential to perform well at environments with significantly higher heat flux and pressure than it has currently been flown.

  20. Optical performance of carbon-nanotube electron sources.

    PubMed

    de Jonge, Niels; Allioux, Myriam; Oostveen, Jim T; Teo, Kenneth B K; Milne, William I

    2005-05-13

    The figure of merit for the electron optical performance of carbon-nanotube (CNT) electron sources is presented. This figure is given by the relation between the reduced brightness and the energy spread in the region of stable emission. It is shown experimentally that a CNT electron source exhibits a highly stable emission process that follows the Fowler-Nordheim theory for field emission, fixing the relationship among the energy spread, the current, and the radius. The performance of the CNT emitter under realistic operating conditions is compared with state-of-the-art electron point sources. It is demonstrated that the reduced brightness is a function of the tunneling parameter, a measure of the energy spread at low temperatures, only, independent of the geometry of the emitter. PMID:15904397

  1. Optical Performance of Carbon-Nanotube Electron Sources

    NASA Astrophysics Data System (ADS)

    de Jonge, Niels; Allioux, Myriam; Oostveen, Jim T.; Teo, Kenneth B.; Milne, William I.

    2005-05-01

    The figure of merit for the electron optical performance of carbon-nanotube (CNT) electron sources is presented. This figure is given by the relation between the reduced brightness and the energy spread in the region of stable emission. It is shown experimentally that a CNT electron source exhibits a highly stable emission process that follows the Fowler-Nordheim theory for field emission, fixing the relationship among the energy spread, the current, and the radius. The performance of the CNT emitter under realistic operating conditions is compared with state-of-the-art electron point sources. It is demonstrated that the reduced brightness is a function of the tunneling parameter, a measure of the energy spread at low temperatures, only, independent of the geometry of the emitter.

  2. Tobacco Stem-Based Activated Carbons for High Performance Supercapacitors

    NASA Astrophysics Data System (ADS)

    Xia, Xiaohong; Liu, Hongbo; Shi, Lei; He, Yuede

    2012-09-01

    Tobacco stem-based activated carbons (TS-ACs) were prepared by simple KOH activation and their application as electrodes in the electrical double layer capacitor (EDLC) performed successfully. The BET surface area, pore volume, and pore size distribution of the TS-ACs were evaluated based on N2 adsorption isotherms at 77 K. The surface area of the obtained activated carbons varies over a wide range (1472.8-3326.7 m2/g) and the mesoporosity was enhanced significantly as the ratio of KOH to tobacco stem (TS) increased. The electrochemical behaviors of series TS-ACs were characterized by means of galvanostatic charging/discharging, cyclic voltammetry, and impedance spectroscopy. The correlation between electrochemical properties and pore structure was investigated. A high specific capacitance value as 190 F/g at 1 mA/cm2 was obtained in 1 M LiPF6-EC/DMC/DEC electrolyte solution. Furthermore, good performance is also achieved even at high current densities. A development of new use for TS into a valuable energy storage material is explored.

  3. Nitrogen-doped mesoporous carbons for high performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Wu, Kai; Liu, Qiming

    2016-08-01

    The mesoporous carbons have been synthesized by using α-D(+)-Glucose, D-Glucosamine hydrochloride or their mixture as carbon precursors and mesoporous silicas (SBA-15 or MCF) as hard templates. The as-prepared products show a large pore volume (0.59-0.97 cm3 g-1), high surface areas (352.72-1152.67 m2 g-1) and rational nitrogen content (ca. 2.5-3.9 wt.%). The results of electrochemical tests demonstrate that both heteroatom doping and suitable pore structure play a decisive role in the performance of supercapacitors. The representative sample of SBA-15 replica obtained using D-Glucosamine hydrochloride only exhibits high specific capacitance (212.8 F g-1 at 0.5 A g-1) and good cycle durability (86.1% of the initial capacitance after 2000 cycles) in 6 M KOH aqueous electrolyte, which is attributed to the contribution of double layer capacitance and pseudo-capacitance. The excellent electrochemical performance makes it a promising electrode material for supercapacitors.

  4. Advanced carbon-based material C{sub 60} modification using partially ionized cluster and energetic beams

    SciTech Connect

    Du Yuancheng; Ren Zhongmin; Ning Zhifeng; Xu Ning; Li Fuming

    1997-06-20

    Two processes have been undertaken using Partially ionized cluster deposition (PICBD) and energetic ion bombardment beams deposition (IBD) respectively. C{sub 60} films deposited by PICBD at V=0 and 65 V, which result in highly textured close-packed structure in orientation (110) and being more polycrystalline respectively, the resistance of C{sub 60} films to oxygen diffusion contamination will be improved. In the case of PICBD, the ionized C{sub 60} soccer-balls molecules in the evaporation beams will be fragmented in collision with the substrate under the elevated accelerating fields Va. As a new synthetic IBD processing, two low energy (400 and 1000 eV) nitrogen ion beams have been used to bombard C{sub 60} films to synthesize the carbon nitride films.

  5. Electron and laser beam-induced current measurements of diamond-like carbon films modified by scanning probe method

    NASA Astrophysics Data System (ADS)

    Hayashi, Shigehiro; Han, Younggun; Choi, Woon; Tomokage, Hajime

    2013-03-01

    A nitrogen-doped diamond-like carbon (DLC) film deposited on n-type silicon is modified by applying an electric field in a vacuum between a tungsten tip and the DLC film surface using a scanning probe field emission current method. The resistance decreases and a Schottky barrier is formed between the modified DLC and the silicon surface, while micro-Raman measurements show a slight nano-crystalline graphitization. The electron beam induced current from the modified area is measured without any metal contact deposition. An infrared laser beam with a wavelength of 1400 nm is scanned across the backside of the silicon, and the induced current from the DLC modified area is measured. It is shown that both infrared laser and electron beam induced current measurements were possible for the modified DLC film on silicon structures.

  6. Performances of PID and Different Fuzzy Methods for Controlling a Ball on Beam

    NASA Astrophysics Data System (ADS)

    Minh, Vu Trieu; Mart, Tamre; Moezzi, Reza; Oliver, Mets; Martin, Jurise; Ahti, Polder; Leo, Teder; Mart, Juurma

    2016-05-01

    This paper develops and analyses the performances evaluation of different control strategies applied for a nonlinear motion of a ball on a beam system. Comparison results provide in-depth comprehension on the stable ability of different controllers for this real mechanical application. The three different controllers are a conventional PID method, a Mamdani-type fuzzy rule method and a Sugeno-type fuzzy rule method. In this study, the PID shows the fastest sinuous reference tracking while the Mamdani-type fuzzy method proves the highest stability performance for tracking square wave motions.

  7. Charge exchange recombination spectroscopy measurements in the extreme ultraviolet region of central carbon concentrations during high power neutral beam heating in TFTR (Tokamak Fusion Test Reactor)

    SciTech Connect

    Stratton, B.C.; Fonck, R.J.; Ramsey, A.T.; Synakowski, E.J.; Grek, B.; Hill, K.W.; Johnson, D.W.; Mansfield, D.K.; Park, H.; Taylor, G.; Valanju, P.M. . Plasma Physics Lab.; Texas Univ., Austin, TX . Fusion Research Center)

    1989-09-01

    The carbon concentration in the central region of TFTR discharges with high power neutral beam heating has been measured by charge-extracted recombination spectroscopy (CXRS) of the C{sup +5} n = 3--4 transition in the extreme ultraviolet region. The carbon concentrations were deduced from absolute measurements of the line brightness using a calculation of the beam attenuation and the appropriate cascade-corrected line excitation rates. As a result of the high ion temperatures in most of the discharges, the contribution of beam halo neutrals to the line brightness was significant and therefore had to be included in the modeling of the data. Carbon concentrations have been measured in discharges with I{sub p} = 1.0-1.6 MA and beam power in the range of 2.6-30 MW, including a number of supershots. The results are in good agreement with carbon concentrations deduced from the visible bremsstrahlung Z{sub eff} and metallic impurity concentrations measured by x-ray pulse-height analysis, demonstrating the reliability of the atomic rates used in the beam attenuation and line excitation calculations. Carbon is the dominant impurity species in these discharges; the oxygen concentration measured via CXRS in a high beam power case was 0.0006 of n{sub e}, compard to 0.04 for carbon. Trends with I{sub p} and beam power in the carbon concentration and the inferred deuteron concentration are presented. The carbon concentration is independent of I{sub p} and decreases from 0.13 at 2.6 MW beam power to 0.04 at 30 MW, while the deuteron concentration increases from 0.25 to 0.75 over the same range of beam power. These changes are primarily the result of beam particle fueling, as the carbon density did not vary significantly with beam power. The time evolutions of the carbon and deuteron concentrations during two high power beam pulses, one which exhibited a carbon bloom and one which did not, are compared. 30 refs., 12 figs., 2 tabs.

  8. In situ study of erosion and deposition of amorphous hydrogenated carbon films by exposure to a hydrogen atom beam

    SciTech Connect

    Markelj, Sabina; Pelicon, Primoz; Cadez, Iztok; Schwarz-Selinger, Thomas; Jacob, Wolfgang

    2012-07-15

    This paper reports on the first dual-beam experiment employing a hydrogen atom beam for sample exposure and an ion beam for analysis, enabling in situ and real-time studies of hydrogen atom interaction with materials. The erosion of an amorphous hydrogenated carbon (a-C:H) layer by deuterium atoms at 580 K sample temperature was studied and the uptake of deuterium during the erosion process was measured in real time. The deuterium areal density increased at the beginning to 7.3 Multiplication-Sign 10{sup 15} D cm{sup -2}, but then stabilized at a constant value of 5.5 Multiplication-Sign 10{sup 15} D cm{sup -2}. Formation of a polymer-like deposit on an a-C:H layer held at room temperature and subjected to the deuterium atom beam was observed and also studied in situ. For both erosion and deposition studies an a-{sup 13}C:H layer on top of an Si substrate was used as a sample, making the experiments isotopically fully specified and thereby differentiating the deposited from the original layer and the interacting D atoms from H atoms present in the layer and in the residual vacuum. From the deposition study it was shown that carbon in the deposited layer originates from carbon-carrying species in the background vacuum that interact with hydrogen atoms. The areal density of the carbon at the surface was determined from the energy shift of the Si edge in the Rutherford backscattering spectrum. The cross section for {sup 7}Li on D at 4.3 MeV Li ion energy and at a recoil angle of 30 Degree-Sign was also determined to be (236 {+-} 16) Multiplication-Sign 10{sup -27} cm{sup 2}/sr. This is a factor of 3 {+-} 0.2 times higher than the Rutherford elastic cross section.

  9. Carbon beam extraction with 14.5 GHz electron cyclotron resonance ion source at Korea Atomic Energy Research Institute

    NASA Astrophysics Data System (ADS)

    Lee, Cheol Ho; Oh, Byung-Hoon; Chang, Dae-Sik; Jeong, Sun-Chan

    2014-02-01

    A 14.5 GHz Electron Cyclotron Resonance ion source (ECRIS) has been made to produce C4+ beam for using a carbon therapy facility and recently tested at KAERI. Highly charged carbon ions have been successfully extracted. When using only CO2 gas, the beam current of C4+ was almost 14 μA at 15 kV extraction voltage. To get higher current of the C4+ beam, while optimizing confinement magnetic field configuration (e.g., axial strengths at minimum and extraction side), gas-mixing (CO2/He), and biased disk were introduced. When the gas mixing ratio of the CO2/He gas is 1:8 at an operational pressure of 5 × 10-7 mbar and the disk was biased to -150 V relative to the ion source body, the highest current of the C4+ beam was achieved to be 50 μA, more than three times higher than previously observed only with CO2 gas. Some details on the operating conditions of the ECRIS were discussed.

  10. Carbon beam extraction with 14.5 GHz electron cyclotron resonance ion source at Korea Atomic Energy Research Institute.

    PubMed

    Lee, Cheol Ho; Oh, Byung-Hoon; Chang, Dae-Sik; Jeong, Sun-Chan

    2014-02-01

    A 14.5 GHz Electron Cyclotron Resonance ion source (ECRIS) has been made to produce C(4+) beam for using a carbon therapy facility and recently tested at KAERI. Highly charged carbon ions have been successfully extracted. When using only CO2 gas, the beam current of C(4+) was almost 14 μA at 15 kV extraction voltage. To get higher current of the C(4+) beam, while optimizing confinement magnetic field configuration (e.g., axial strengths at minimum and extraction side), gas-mixing (CO2/He), and biased disk were introduced. When the gas mixing ratio of the CO2/He gas is 1:8 at an operational pressure of 5 × 10(-7) mbar and the disk was biased to -150 V relative to the ion source body, the highest current of the C(4+) beam was achieved to be 50 μA, more than three times higher than previously observed only with CO2 gas. Some details on the operating conditions of the ECRIS were discussed. PMID:24593482

  11. Seismic performance and comparison of three different I beam to box column joints

    NASA Astrophysics Data System (ADS)

    Saneei Nia, Z.; Mazroi, A.; Ghassemieh, M.; Pezeshki, H.

    2014-12-01

    Despite the inherently advantages of the box column, finding the best option for the I beam to the box column connection is the main challenge in using the box column as a structural member for special moment frames. In this paper, the seismic performance of unreinforced connection, weakened connection and strengthened connection was evaluated through a comprehensive experimental program. The seismic comparisons were fabricated by assessing the strength, ductility and energy dissipation in each configuration. Three full scale tests with several connections were carried out. All the specimens were subjected to cyclic loading and prior to failure by forming a plastic hinge in the beam, all the connections managed to reach an inelastic rotation of more than 6.0% rad. The experimental and analytical results showed that the seismic performance of the strengthened connection with flange and shear plates turned out to be the most effective in the beam to the box column connection. Moreover, the normalized stress distribution of the continuity plates revealed that the possibility of the weld fracture in unreinforced connection is more than other specimens.

  12. Performance enhancement using power beaming for electric propulsion earth orbital transporters

    SciTech Connect

    Dagle, J.E.

    1991-08-01

    An electric propulsion Earth orbital transport vehicle (EOTV) can effectively deliver large payloads using much less propellant than chemical transfer methods. By using an EOTV instead of a chemical upper stage, either a smaller launch vehicle can be used for the same satellite mass or larger satellite can be deployed using the same launch vehicle. However, the propellant mass savings from using the higher specific impulse of electric propulsion may not be enough to overcome the disadvantage of the added mass and cost of the electric propulsion power source. Power system limitations have been a major factor delaying the acceptance and use of electric propulsion. This paper outlines the power requirements of electric propulsion technology being developed today, including arcjets, magnetoplasmadynamic (MPD) thrusters, and ion engines. Power supply characteristics are discussed for nuclear, solar, and power-beaming systems. Operational characteristics are given for each, as are the impacts of the power supply alternative on the overall craft performance. Because of its modular nature, the power-beaming approach is able to meet the power requirements of all three electric propulsion types. Also, commonality of approach allows different electric propulsion approaches to be powered by a single power supply approach. Power beaming exhibits better flexibility and performance than on-board nuclear or solar power systems.

  13. Photorefractive two-beam coupling joint transform correlator: modeling and performance evaluation.

    PubMed

    Nehmetallah, G; Khoury, J; Banerjee, P P

    2016-05-20

    The photorefractive two-beam coupling joint transform correlator combines two features. The first is embedded semi-adaptive optimality, which weighs the correlation against clutter and noise in the input, and the second is the intrinsic dynamic range compression nonlinearity, which improves several metrics simultaneously without metric trade-off. Although the two beam coupling correlator was invented many years ago, its outstanding performance was recognized on only relatively simple images. There was no study about the performance of this correlator on complicated images and using different figures of merit. In this paper, the study is extended to more complicated images. For the first time, to our knowledge, we demonstrate simultaneous improvement in metrics performance without metric trade-off. The performance was evaluated compared to the classical joint transform correlator. A typical experimental result to validate the simulation results was also shown in this work. The best performing operation parameters were identified to guide the experimental work and for future comparison with other well-known optimal correlation filters. PMID:27411127

  14. Performance of a beam-multiplexing diamond crystal monochromator at the Linac Coherent Light Source

    SciTech Connect

    Zhu, Diling Feng, Yiping; Lemke, Henrik T.; Fritz, David M.; Chollet, Matthieu; Glownia, J. M.; Alonso-Mori, Roberto; Sikorski, Marcin; Song, Sanghoon; Williams, Garth J.; Messerschmidt, Marc; Boutet, Sébastien; Robert, Aymeric; Stoupin, Stanislav; Shvyd'ko, Yuri V.; Terentyev, Sergey A.; Blank, Vladimir D.; Driel, Tim B. van

    2014-06-15

    A double-crystal diamond monochromator was recently implemented at the Linac Coherent Light Source. It enables splitting pulses generated by the free electron laser in the hard x-ray regime and thus allows the simultaneous operations of two instruments. Both monochromator crystals are High-Pressure High-Temperature grown type-IIa diamond crystal plates with the (111) orientation. The first crystal has a thickness of ∼100 μm to allow high reflectivity within the Bragg bandwidth and good transmission for the other wavelengths for downstream use. The second crystal is about 300 μm thick and makes the exit beam of the monochromator parallel to the incoming beam with an offset of 600 mm. Here we present details on the monochromator design and its performance.

  15. A parametric analysis of performance characteristics of satellite-borne multiple-beam antennas

    NASA Technical Reports Server (NTRS)

    Salmasi, A. B.

    1980-01-01

    An analytical and empirical model is presented for parametric study of multiple beam antenna frequency reuse capacity and interbeam isolation. Two types of reflector antennas, the axisymmetric parabolic and the offset-parabolic reflectors, are utilized to demonstrate the model. The parameters of the model are introduced and their limitations are discussed in the context of parabolic reflector antennas. The model, however, is not restricted to analysis of reflector antenna performance. Results of the analyses are covered in two tables. The model parameters, objectives, and descriptions are given, multiple-beam antenna frequency reuse capacity and interbeam isolation analysis of the two types of reflectors are discussed as well as future developments of the program model.

  16. How to polarise all neutrons in one beam: a high performance polariser and neutron transport system

    NASA Astrophysics Data System (ADS)

    Rodriguez, D. Martin; Bentley, P. M.; Pappas, C.

    2016-09-01

    Polarised neutron beams are used in disciplines as diverse as magnetism,soft matter or biology. However, most of these applications often suffer from low flux also because the existing neutron polarising methods imply the filtering of one of the spin states, with a transmission of 50% at maximum. With the purpose of using all neutrons that are usually discarded, we propose a system that splits them according to their polarisation, flips them to match the spin direction, and then focuses them at the sample. Monte Carlo (MC) simulations show that this is achievable over a wide wavelength range and with an outstanding performance at the price of a more divergent neutron beam at the sample position.

  17. Ion-beam technologies

    SciTech Connect

    Fenske, G.R.

    1993-01-01

    This compilation of figures and diagrams reviews processes for depositing diamond/diamond-like carbon films. Processes addressed are chemical vapor deposition (HFCVD, PACVD, etc.), plasma vapor deposition (plasma sputtering, ion beam sputtering, evaporation, etc.), low-energy ion implantation, and hybrid processes (biased sputtering, IBAD, biased HFCVD, etc.). The tribological performance of coatings produced by different means is discussed.

  18. Toward high-performance digital logic technology with carbon nanotubes.

    PubMed

    Tulevski, George S; Franklin, Aaron D; Frank, David; Lobez, Jose M; Cao, Qing; Park, Hongsik; Afzali, Ali; Han, Shu-Jen; Hannon, James B; Haensch, Wilfried

    2014-09-23

    The slow-down in traditional silicon complementary metal-oxide-semiconductor (CMOS) scaling (Moore's law) has created an opportunity for a disruptive innovation to bring the semiconductor industry into a postsilicon era. Due to their ultrathin body and ballistic transport, carbon nanotubes (CNTs) have the intrinsic transport and scaling properties to usher in this new era. The remaining challenges are largely materials-related and include obtaining purity levels suitable for logic technology, placement of CNTs at very tight (∼5 nm) pitch to allow for density scaling and source/drain contact scaling. This review examines the potential performance advantages of a CNT-based computing technology, outlines the remaining challenges, and describes the recent progress on these fronts. Although overcoming these issues will be challenging and will require a large, sustained effort from both industry and academia, the recent progress in the field is a cause for optimism that these materials can have an impact on future technologies.

  19. Improving cardiac myocytes performance by carbon nanotubes platforms†

    PubMed Central

    Martinelli, Valentina; Cellot, Giada; Fabbro, Alessandra; Bosi, Susanna; Mestroni, Luisa; Ballerini, Laura

    2013-01-01

    The application of nanotechnology to the cardiovascular system has increasingly caught scientists' attention as a potentially powerful tool for the development of new generation devices able to interface, repair, or boost the performance of cardiac tissue. Carbon nanotubes (CNTs) are considered as promising materials for nanomedicine applications in general and have been recently tested toward excitable cell growth. CNTs are cylindrically shaped structures made up of rolled-up graphene sheets, with unique electrical, thermal, and mechanical properties, able to effectively conducting electrical current in electrochemical interfaces. CNTs-based scaffolds have been recently found to support the in vitro growth of cardiac cells: in particular, their ability to improve cardiomyocytes proliferation, maturation, and electrical behavior are making CNTs extremely attractive for the development and exploitation of interfaces able to impact on cardiac cells physiology and function. PMID:24027533

  20. Investigation of Endurance Performance of Carbon Nanotube Cathodes

    NASA Astrophysics Data System (ADS)

    Saito, Nanako; Yamagiwa, Yoshiki; Ohkawa, Yasushi; Nishida, Shin-Ichiro; Kitamura, Shoji

    The Aerospace Research and Development Directorate of the Japan Aerospace Exploration Agency (JAXA) is considering a demonstration of electrodynamic tether (EDT) systems in low Earth orbit (LEO). Carbon nanotubes (CNTs) have some advantages as electron sources compared to conventional Spindt type emitters, and so are expected to be useful in EDT systems. Experiments to investigate the durability of CNT cathodes in a space environment had been conducted in a diode mode, but it was found that electron extraction tests, in which the cathode with a gate electrode is used, are necessary to evaluate the endurance of CNTs more accurately. In this paper, we conducted long duration operating tests of a cathode with a gate. It was found that there was almost no change in cathode performance at current densities below 100 A/m2 even after the cathode was operated for over 500 hours in the high vacuum environment.

  1. Ion beam assisted deposition of Si-diamond-like carbon coatings on large area substrates

    SciTech Connect

    Fountzoulas, C.G.

    1996-12-31

    Hard, low-friction silicon-containing diamond-like carbon coatings (Si-DLC), were formed by Ar{sup +} ion beam assisted deposition (IBAD), on 5 in. diameter silicon wafers. The diffusion pump oil precursor (tetraphenyl-tetramethyl-trisiloxane: (C{sub 6}H{sub 5}){sub 4}(CH{sub 3}){sub 4}Si{sub 3}O{sub 2}) was evaporated through seven, 3 mm diameter, closely packed apertures (multinozzle/multi-aperture container) arranged in a hexagonal pattern, approximately 5 mm apart according to mathematical model developed at ARL describing the spatial distribution of film deposition from nozzles and apertures onto inclined substrates. The ion energy was kept at 40 keV whereas the ion current density and the oil evaporation temperature were varied to produce hard, lubricious and adherent films. The multinozzle array allowed the relatively uniform ({+-} 20%) coverage of the entire 5 in. substrate. The thickness and the microhardness of the films were measured along the rectilinear surface coordinates of the substrate area. Depending on the deposition parameters the standard deviation of the coating thicknesses and Knoop microhardness varied from 14 to 30% respectively over the substrate. This is a significant improvement from the previously used single nozzle set up where the standard deviation of the coating thickness was 50 to 100% for 2 in. diameter substrates. The Knoop microhardness and the sliding friction coefficient of these coatings ranged from 10,000 to 20,000 MPa and 0.04 and 0.2 respectively. These values are in agreement with the previously reported single nozzle results.

  2. Effects of porous carbon additives and induced fluorine on low dielectric constant polyimide synthesized with an e-beam

    SciTech Connect

    Im, Ji Sun; Bae, Tae-Sung; Lee, Sung Kyu; Lee, Sei-Hyun; Jeong, Euigyung; Kang, Phil Hyun; Lee, Young-Seak

    2010-11-15

    We report the synthesis of a polyimide matrix with a low dielectric constant for application as an intercalation material between metal interconnections in electronic devices. Porous activated carbon was embedded in the polyimide to reduce the dielectric constant, and a thin film of the complex was obtained using the spin-coating and e-beam irradiation methods. The surface of the thin film was modified with fluorine functional groups to impart water resistance and reduce the dielectric constant further. The water resistance was significantly improved by the modification with hydrophobic fluorine groups. The dielectric constant was effectively decreased by porous activated carbon. The fluorine modification also resulted in a low dielectric constant on the polyimide surface by reducing the polar surface free energy. The dielectric constant of polyimide film decreased from 2.98 to 1.9 by effects of porous activated carbon additive and fluorine surface modification.

  3. Simulated Beam Extraction Performance Characterization of a 50-cm Ion Thruster Discharge

    NASA Technical Reports Server (NTRS)

    Foster, John E.; Hubble, Aimee; Nowak-Gucker, Sarah; Davis, Chris; Peterson, Peter; Viges, Eric; Chen, Dave

    2013-01-01

    A 50 cm ion thruster is being developed to operate at >65 percent total efficiency at 11 kW, 2700 s Isp and over 25 kW, 4500 s Isp at a total efficiency of >75 percent. The engine is being developed to address the need for a multimode system that can provide a range of thrust-to- power to service national and commercial near-earth onboard propulsion needs such as station-keeping and orbit transfer. Operating characteristics of the 50 cm ion thruster were measured under simulated beam extraction. The discharge current distribution at the various magnet rings was measured over a range of operating conditions. The relationship between the anode current distribution and the resulting plasma uniformity and ion flux measured at the thruster exit plane is discussed. The thermal envelope will also be investigated through the monitoring of magnet temperatures over the range of discharge powers investigated. Discharge losses as a function of propellant utilization was also characterized at multiple simulated beam currents. Bulk plasma conditions such as electron temperature and electron density near engine centerline was measured over a range of operating conditions using an internal Langmuir probe. Sensitivity of discharge performance to chamber length is also discussed. This data acquired from this discharge study will be used in the refinement of a throttle table in anticipation for eventual beam extraction testing.

  4. CRionScan: A stand-alone real time controller designed to perform ion beam imaging, dose controlled irradiation and proton beam writing

    NASA Astrophysics Data System (ADS)

    Daudin, L.; Barberet, Ph.; Serani, L.; Moretto, Ph.

    2013-07-01

    High resolution ion microbeams, usually used to perform elemental mapping, low dose targeted irradiation or ion beam lithography needs a very flexible beam control system. For this purpose, we have developed a dedicated system (called “CRionScan”), on the AIFIRA facility (Applications Interdisciplinaires des Faisceaux d'Ions en Région Aquitaine). It consists of a stand-alone real-time scanning and imaging instrument based on a Compact Reconfigurable Input/Output (Compact RIO) device from National Instruments™. It is based on a real-time controller, a Field Programmable Gate Array (FPGA), input/output modules and Ethernet connectivity. We have implemented a fast and deterministic beam scanning system interfaced with our commercial data acquisition system without any hardware development. CRionScan is built under LabVIEW™ and has been used on AIFIRA's nanobeam line since 2009 (Barberet et al., 2009, 2011) [1,2]. A Graphical User Interface (GUI) embedded in the Compact RIO as a web page is used to control the scanning parameters. In addition, a fast electrostatic beam blanking trigger has been included in the FPGA and high speed counters (15 MHz) have been implemented to perform dose controlled irradiation and on-line images on the GUI. Analog to Digital converters are used for the beam current measurement and in the near future for secondary electrons imaging. Other functionalities have been integrated in this controller like LED lighting using Pulse Width Modulation and a “NIM Wilkinson ADC” data acquisition.

  5. Performance assessment of natural gas and biogas fueled molten carbonate fuel cells in carbon capture configuration

    NASA Astrophysics Data System (ADS)

    Barelli, Linda; Bidini, Gianni; Campanari, Stefano; Discepoli, Gabriele; Spinelli, Maurizio

    2016-07-01

    The ability of MCFCs as carbon dioxide concentrator is an alternative solution among the carbon capture and storage (CCS) technologies to reduce the CO2 emission of an existing plant, providing energy instead of implying penalties. Moreover, the fuel flexibility exhibited by MCFCs increases the interest on such a solution. This paper provides the performance characterization of MCFCs operated in CCS configuration and fed with either natural gas or biogas. Experimental results are referred to a base CCS unit constituted by a MCFC stack fed from a reformer and integrated with an oxycombustor. A comparative analysis is carried out to evaluate the effect of fuel composition on energy efficiency and CO2 capture performance. A higher CO2 removal ability is revealed for the natural feeding case, bringing to a significant reduction in MCFC total area (-11.5%) and to an increase in produced net power (+13%). Moreover, the separated CO2 results in 89% (natural gas) and 86.5% (biogas) of the CO2 globally delivered by the CCS base unit. Further investigation will be carried out to provide a comprehensive assessment of the different solutions eco-efficiency considering also the biogas source and availability.

  6. DSS-13 beam-waveguide antenna performance in the bypass mode

    NASA Technical Reports Server (NTRS)

    Stewart, S. R.

    1992-01-01

    A new 34-meter beam-waveguide (BWG) antenna that contains two microwave paths, a centerline feed system, and a bypass feed system, was built at the Deep Space Station 13 (DDS 13) at Goldstone, California. Previous articles have described the test results from the evaluation of the centerline BWG feed system in the receive mode as well as the test package hardware used to perform these tests. The test results from the evaluation of the bypass BWG feed system on the DSS-13 antenna in the receive mode, including the operating noise-temperature and the antenna-area-efficiency measurements, are presented.

  7. Performance effects of tie-truss modifications for a 70-meter centerline beam waveguide antenna

    NASA Technical Reports Server (NTRS)

    Cucchissi, J. J.

    1989-01-01

    The elevation-axis tie truss of the 70-m antennas would have to be modified to accommodate a centerline beam waveguide. To accomplish this, the center section of the tie truss has to be altered, causing a change in the tie-truss compliance and affecting structural performance. Even with the center section completely removed, the worst-case rms pathlength error due to gravity load is increased from 0.025 to only 0.030 inches. Using a simple postprocessor technique, the effects of modifying the compliance can be predicted without resorting to multiple and costly re-analyses of large finite-element models on a mainframe computer.

  8. Electron-beam induced diamond-like-carbon passivation of plasmonic devices

    NASA Astrophysics Data System (ADS)

    Balaur, Eugeniu; Sadatnajafi, Catherine; Langley, Daniel; Lin, Jiao; Kou, Shan Shan; Abbey, Brian

    2015-12-01

    Engineered materials with feature sizes on the order of a few nanometres offer the potential for producing metamaterials with properties which may differ significantly from their bulk counterpart. Here we describe the production of plasmonic colour filters using periodic arrays of nanoscale cross shaped apertures fabricated in optically opaque silver films. Due to its relatively low loss in the visible and near infrared range, silver is a popular choice for plasmonic devices, however it is also unstable in wet or even ambient conditions. Here we show that ultra-thin layers of Diamond-Like Carbon (DLC) can be used to prevent degradation due to oxidative stress, ageing and corrosion. We demonstrate that DLC effectively protects the sub-micron features which make up the plasmonic colour filter under both atmospheric conditions and accelerated aging using iodine gas. Through a systematic study we confirm that the nanometre thick DLC layers have no effect on the device functionality or performance.

  9. [Performance of new solid carbon source materials for denitrification].

    PubMed

    Shao, Liu; Xu, Zu-Xin; Wang, Sheng; Jin, Wei; Yin, Hai-Long

    2011-08-01

    Organic carbon is needed as the electron donor in the process of reduction of nitrate transformation to nitrogen gas, which is essential for biological denitrification. Based on previous research, agriculture wastes including corncob, rice hull, rice straw and sawdust were selected as potential carbon source for denitrification. Using the static organic material of carbon source leaching kinetics test and orthogonal experiments of external factors on carbon emission process, carbon release and its mechanism of a variety of carbon materials were studied. Study showed that release process of various types of carbon source materials follows the second dynamics formula, the release curve displayed a better double-reciprocal relationship. It revealed that release amount of rice straw was the highest and sawdust was the lowest. Results showed that corncob could better be used as carbon source for denitrification. Orthogonal test indicated that the increasing of solid-liquid ratio and water temperature would lead to an enhanced release capacity of carbon, however, the change of pH had no significant effect on release capacity of carbon; according to significant degree of water temperature, pH, solid-liquid ratio impacted on the carbon release, it was sorted by solid-liquid ratio > temperature > pH. PMID:22619957

  10. Extended high order sandwich panel theory for bending analysis of sandwich beams with carbon nanotube reinforced face sheets

    NASA Astrophysics Data System (ADS)

    Jedari Salami, S.

    2016-02-01

    Bending analysis of a sandwich beam with soft core and carbon nanotube reinforced composite (CNTRC) face sheets in the literature is presented based on Extended High order Sandwich Panel Theory (EHSAPT). Distribution of fibers through the thickness of the face sheets could be uniform or functionally graded (FG). In this theory the face sheets follow the first order shear deformation theory (FSDT). Besides, the two dimensional elasticity is used for the core. The field equations are derived via the Ritz based solution which is suitable for any essential boundary condition. The influences of boundary conditions on bending response of the sandwich panel with soft core and CNTRC face sheet are investigated. In each type of boundary condition the effect of distribution pattern of CNTRCs on many essential involved parameters of the sandwich beam with functionally graded carbon nanotube reinforced composite (FG- CNTRC) face sheets are studied in detail. Finally, experimental result have been compared with those obtained based on developed solution method. It is concluded that, the sandwich beam with X distribution figure of face sheets is the strongest with the smallest transverse displacement, and followed by the UD, O and ∧-ones, respectively.

  11. Design and Performance of the H_infinity Controller for the Beam-Waveguide Antenna

    NASA Astrophysics Data System (ADS)

    Gawronski, W.

    2011-02-01

    The linear-quadratic-Gaussian (LQG) controllers are currently implemented at the beam-waveguide (BWG) antennas. Each BWG antenna has a different set of LQG coefficients, obtained by tuning and testing each controller individually. Individual coefficients for each antenna are necessary, since the antenna dynamics are not identical and the derivation of the LQG coefficients is a labor-intensive process. Hence, the process could be simplified by using single set of coefficients for all BWG antennas. The purpose of the work reported here is to develop a single set of servo coefficients for all BWG antennas. This is achieved by using the H_infinity controller approach and a robust design technique. In this article, the analysis of the H_infinity controller was performed, and the results obtained (by executing over 10,000 Monte Carlo simulations) showed that it is feasible to use a single set of the H_infinity controller coefficients at all BWG antennas, and that the H_infinity controller performance is similar to or exceeds the "standard" LQG controller performance, i.e., except for the DSS-25 antenna controller performance. Note that the latter controller was derived exceptionally strong. At the remaining antennas, the controller coefficients are weaker, and they represent the "standard" LQG performance. This approach simplifies the development of the controller coefficients for BWG antennas, and simplifies the servo performance evaluation, since the performance should be similar for all six BWG antennas.

  12. External Beam Boost for Cancer of the Cervix Uteri When Intracavitary Therapy Cannot Be Performed

    SciTech Connect

    Barraclough, Lisa Helen Swindell, Ric; Livsey, Jacqueline E.; Hunter, Robin D.; Davidson, Susan E.

    2008-07-01

    Purpose: To assess the outcome of patients treated with radical radiotherapy for cervical cancer who received an external beam boost, in place of intracavitary brachytherapy (ICT), after irradiation to the whole pelvis. Methods and Materials: Case notes were reviewed for all patients treated in this way in a single center between 1996 and 2004. Patient and tumor details, the reasons why ICT was not possible, and treatment outcome were documented. Results: Forty-four patients were identified. The mean age was 56.4 years (range, 26-88 years). Clinical International Federation of Gynecology and Obstetrics or radiologic stage for Stages I, II, III, and IV, respectively, was 16%, 48%, 27%, and 7%. A total radiation dose of 54-70 Gy was given (75% received {>=}60 Gy). Reasons for ICT not being performed were technical limitations in 73%, comorbidity or isolation limitations in 23%, and patient choice in 4%. The median follow-up was 2.3 years. Recurrent disease was seen in 48%, with a median time to recurrence of 2.3 years. Central recurrence was seen in 16 of the 21 patients with recurrent disease. The 5-year overall survival rate was 49.3%. The 3-year cancer-specific survival rate by stage was 100%, 70%, and 42% for Stages I, II, and III, respectively. Late Grades 1 and 2 bowel, bladder, and vaginal toxicity were seen in 41%. Late Grade 3 toxicity was seen in 2%. Conclusion: An external beam boost is a reasonable option after external beam radiotherapy to the pelvis when it is not possible to perform ICT.

  13. Ion-beam and microwave-stimulated functionalization and derivatization of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Makala, Raghuveer S.

    Derivatizing carbon nanotubes (CNTs) with other low-dimensional nanostructures is of widespread interest for creating CNT-based nanocomposites and devices. Conventional routes based on wet-chemical oxidation or hydrophobic adsorption do not allow premeditated control over the location or spatial extent of functionalization. Moreover, aggressive oxidative treatments and agitation in corrosive environments lead to CNT shortening, damage, and incorporation of excess impurity concentrations. Thus, it is imperative to explore and develop alternative functionalization methods to overcome these shortcomings. The work presented in this thesis outlines two such methodologies: one based on focused ion irradiation for siteselective functionalization and the other that employs microwave-stimulation for mild, yet rapid and homogenous CNT functionalization. The utility of 10 and 30 kcV Ga+ focused ion beams (FIB) to thin, slice, weld, and alter the structure and composition at precise locations along the CNT axis is presented. This strategy of harnessing ion-beam-induced defect generation and doping is attractive for modulating chemical and electrical properties along the CNT length, and fabricate CNT-based heterostructures and networks. A novel approach that utilizes focused ion irradiation to site-selectively derivatize preselected segments of CNTs with controlled micro-/nano-scale lateral spatial resolution is demonstrated. Irradiation followed by air-exposure results in functionalized CNT segments ranging from the nanoscopic to the macroscopic scale. The functional moieties are utilized to site-selectively anchor Au nanoparticles, fluorescent nanospheres, an amino acid---lysine, a charge-transfer metalloprotein---azurin, and a photoactive protein---bacteriorhodopsin by means of electrostatic or covalent interactions. This approach is versatile and can be extended to obtaining other molecular moieties and derivatives opening up possibilities for building new types of nano

  14. Study on laser and infrared attenuation performance of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Liu, Xiang-cui; Liu, Qing-hai; Dai, Meng-yan; Cheng, Xiang; Fang, Guo-feng; Zhang, Tong; Liu, Haifeng

    2014-11-01

    In recent years, the weapon systems of laser and infrared (IR) imaging guidance have been widely used in modern warfare because of their high precision and strong anti-interference. However, military smoke, a rapid and effective passive jamming method, can effectively counteract the attack of precision-guided weapons by their scattering and absorbing effects. The traditional smoke has good visible light (0.4-0.76μm) obscurant performance, but hardly any effects to other electromagnetic wave bands while the weapon systems of laser and IR imaging guidance usually work in broad band, including the near-infrared (1-3μm), middle-infrared (3-5μm), far-infrared (8-14μm), and so on. Accordingly, exploiting new effective obscurant materials has attracted tremendous interest worldwide nowadays. As is known, the nano-structured materials have lots of unique properties comparing with the traditional materials suggesting that they might be the perfect alternatives to solve the problems above. Carbon nanotubes (CNTs) are well-ordered, all-carbon hollow graphitic nano-structured materials with a high aspect ratio, lengths from several hundred nanometers to several millimeters. CNTs possess many unique intrinsic physical-chemical properties and are investigated in many areas reported by the previous studies. However, no application research about CNTs in smoke technology field is reported yet. In this paper, the attenuation performances of CNTs smoke to laser and IR were assessed in 20m3 smoke chamber. The testing wavebands employed in experiments are 1.06μm and 10.6μm laser, 3-5μm and 8-14μm IR radiation. The main parameters were obtained included the attenuation rate, transmission rate, mass extinction coefficient, etc. The experimental results suggest that CNTs smoke exhibits excellent attenuation ability to the broadband IR radiation. Their mass extinction coefficients are all above 1m2·g-1. Nevertheless, the mass extinction coefficients vary with the sampling time

  15. High performance carbon nanotube - polymer nanofiber hybrid fabrics

    NASA Astrophysics Data System (ADS)

    Yildiz, Ozkan; Stano, Kelly; Faraji, Shaghayegh; Stone, Corinne; Willis, Colin; Zhang, Xiangwu; Jur, Jesse S.; Bradford, Philip D.

    2015-10-01

    Stable nanoscale hybrid fabrics containing both polymer nanofibers and separate and distinct carbon nanotubes (CNTs) are highly desirable but very challenging to produce. Here, we report the first instance of such a hybrid fabric, which can be easily tailored to contain 0-100% millimeter long CNTs. The novel CNT - polymer hybrid nonwoven fabrics were created by simultaneously electrospinning nanofibers onto aligned CNT sheets which were drawn and collected on a grounded, rotating mandrel. Due to the unique properties of the CNTs, the hybrids show very high tensile strength, very small pore size, high specific surface area and electrical conductivity. In order to further examine the hybrid fabric properties, they were consolidated under pressure, and also calendered at 70 °C. After calendering, the fabric's strength increased by an order of magnitude due to increased interactions and intermingling with the CNTs. The hybrids are highly efficient as aerosol filters; consolidated hybrid fabrics with a thickness of 20 microns and areal density of only 8 g m-2 exhibited ultra low particulate (ULPA) filter performance. The flexibility of this nanofabrication method allows for the use of many different polymer systems which provides the opportunity for engineering a wide range of nanoscale hybrid materials with desired functionalities.Stable nanoscale hybrid fabrics containing both polymer nanofibers and separate and distinct carbon nanotubes (CNTs) are highly desirable but very challenging to produce. Here, we report the first instance of such a hybrid fabric, which can be easily tailored to contain 0-100% millimeter long CNTs. The novel CNT - polymer hybrid nonwoven fabrics were created by simultaneously electrospinning nanofibers onto aligned CNT sheets which were drawn and collected on a grounded, rotating mandrel. Due to the unique properties of the CNTs, the hybrids show very high tensile strength, very small pore size, high specific surface area and electrical

  16. The performance of supercapacitor electrodes developed from chemically activated carbon produced from waste tea

    NASA Astrophysics Data System (ADS)

    Inal, I. Isil Gurten; Holmes, Stuart M.; Banford, Anthony; Aktas, Zeki

    2015-12-01

    Highly microporous and mesoporous activated carbons were produced from waste tea for application as supercapacitor electrodes, utilising a chemical activation method involving treatment with either K2CO3 or H3PO4. The area, pore structure characteristics and surface functionality of the activated carbons were evaluated to investigate the influence on electrochemical performance. The performance of the activated carbons as supercapacitor electrodes was tested by cyclic voltammetry (CV), impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD) measurements, in an aqueous electrolyte. The results showed that the pore structure and type of the activated carbon have significant impact on the supercapacitor performance. Both waste tea-based activated carbon electrodes showed good cyclic stability. However, despite its lower specific surface area the highly microporous activated carbon produced with K2CO3, exhibited much better capacitive performance than that of the mesoporous activated carbon produced with H3PO4.

  17. Assessing the Health and Performance Risks of Carbon Dioxide Exposures

    NASA Technical Reports Server (NTRS)

    James, John T.; Meyers, V. E.; Alexander, D.

    2010-01-01

    Carbon dioxide (CO2) is an anthropogenic gas that accumulates in spacecraft to much higher levels than earth-normal levels. Controlling concentrations of this gas to acceptable levels to ensure crew health and optimal performance demands major commitment of resources. NASA has many decades of experience monitoring and controlling CO2, yet we are uncertain of the levels at which subtle performance decrements develop. There is limited evidence from ground-based studies that visual disturbances can occur during brief exposures and visual changes have been noted in spaceflight crews. These changes may be due to CO2 alone or in combination with other known spaceflight factors such as increased intracranial pressure due to fluid shifts. Discerning the comparative contribution of each to performance decrements is an urgent issue if we hope to optimize astronaut performance aboard the ISS. Long-term, we must know the appropriate control levels for exploration-class missions to ensure that crewmembers can remain cooperative and productive in a highly stressful environment. Furthermore, we must know the magnitude of interindividual variability in susceptibility to the adverse effects of CO2 so that the most tolerant crewmembers can be identified. Ground-based studies have been conducted for many years to set exposure limits for submariners; however, these studies are typically limited and incompletely reported. Nonetheless, NASA, in cooperation with the National Research Council, has set exposure limits for astronauts using this limited database. These studies do not consider the interactions of spaceflight-induced fluid shifts and CO2 exposures. In an attempt to discern whether CO2 levels affect the incidence of headache and visual disturbances in astronauts we performed a retrospective study comparing average CO2 levels and the prevalence of headache and visual disturbances. Our goal is to narrow gaps in the risk profile for in-flight CO2 exposures. Such studies can

  18. Carbon nanosheet buckypaper: A graphene-carbon nanotube hybrid material for enhanced supercapacitor performance

    NASA Astrophysics Data System (ADS)

    Brown, Billyde; Swain, Benjamin; Hiltwine, Judy; Brooks, D. Bradford; Zhou, Zhiguo

    2014-12-01

    Carbon nanosheets (CNS) are a graphene-based material with unique properties to improve both the speed and energy storage capability of electrochemical capacitors. In this study we employ CNS to demonstrate the fastest known response time of any electrochemical capacitor, with a turn-on frequency of 36 kHz exceeding that of Al electrolytic capacitors. Further we introduce a new hybrid material, "CNS-buckypaper", i.e. CNS deposited onto freestanding buckypaper made from single-walled carbon nanotubes. Conformal deposition was achieved on ∼3 μm diameter nanotube bundles (or ropes) along the surface of the buckypaper which enabled a significant (∼4×) improvement in specific capacitance (from 60 to 230 F g-1) compared to as-produced buckypaper. We also discuss the synthesis, characterization, and integration of ultra-fast CNS-Ni current collectors and CNS-buckypaper electrodes into single and multi-cell supercapacitor devices. The packaged devices show high pulse-power performance at moderate energy density (∼1 Wh kg-1 at 22 kW kg-1) indicating potential for insertion into double-layer capacitor markets.

  19. Engineering the atomic structure of carbon nanotubes by a focused electron beam: new morphologies at the sub-nanometer scale.

    PubMed

    Rodríguez-Manzo, Julio A; Krasheninnikov, Arkady V; Banhart, Florian

    2012-07-16

    Carbon atoms are displaced in pre-selected locations of carbon nanotubes by using a focused electron beam in a scanning transmission electron microscope. Sub-nanometer-sized holes are created that change the morphology of double and triple-walled carbon nanotubes and connect the shells in a unique way. By combining in situ transmission electron microscopy experiments with atomistic simulations, we study the bonding between defective shells in the new structures which are reminiscent of the shape of a flute. We demonstrate that in double-walled nanotubes the shells locally merge by forming nanoarches while atoms with dangling bonds can be preserved in triple-walled carbon nanotubes. In the latter system, nanoarches are formed between the inner- and outermost shells, shielding small graphenic islands with open edges between the neighboring shells. Our results indicate that arrays of quantum dots may be produced in carbon nanotubes by spatially localized electron irradiation, generating atoms with dangling bonds that may give rise to localized magnetic moments. PMID:22407751

  20. Performance characteristics of the MIT fission converter based epithermal neutron beam.

    PubMed

    Riley, K J; Binns, P J; Harling, O K

    2003-04-01

    A pre-clinical characterization of the first fission converter based epithermal neutron beam (FCB) designed for boron neutron capture therapy (BNCT) has been performed. Calculated design parameters describing the physical performance of the aluminium and Teflon filtered beam were confirmed from neutron fluence and absorbed dose rate measurements performed with activation foils and paired ionization chambers. The facility currently provides an epithermal neutron flux of 4.6 x 10(9) n cm(-2) s(-1) in-air at the patient position that makes it the most intense BNCT source in the world. This epithermal neutron flux is accompanied by very low specific photon and fast neutron absorbed doses of 3.5 +/- 0.5 and 1.4 +/- 0.2 x 10(-13) Gy cm2, respectively. A therapeutic dose rate of 1.7 RBE Gy min(-1) is achievable at the advantage depth of 97 mm when boronated phenylalanine (BPA) is used as the delivery agent, giving an average therapeutic ratio of 5.7. In clinical trials of normal tissue tolerance when using the FCB, the effective prescribed dose is due principally to neutron interactions with the nonselectively absorbed BPA present in brain. If an advanced compound is considered, the dose to brain would instead be predominately from the photon kerma induced by thermal neutron capture in hydrogen and advantage parameters of 0.88 Gy min(-1), 121 mm and 10.8 would be realized for the therapeutic dose rate, advantage depth and therapeutic ratio, respectively. This study confirms the success of a new approach to producing a high intensity, high purity epithermal neutron source that attains near optimal physical performance and which is well suited to exploit the next generation of boron delivery agents.

  1. Dynamic modulation of electronic properties of graphene by localized carbon doping using focused electron beam induced deposition

    NASA Astrophysics Data System (ADS)

    Kim, S.; Russell, M.; Henry, M.; Kim, S. S.; Naik, R. R.; Voevodin, A. A.; Jang, S. S.; Tsukruk, V. V.; Fedorov, A. G.

    2015-09-01

    We report on the first demonstration of controllable carbon doping of graphene to engineer local electronic properties of a graphene conduction channel using focused electron beam induced deposition (FEBID). Electrical measurements indicate that an ``n-p-n'' junction on graphene conduction channel is formed by partial carbon deposition near the source and drain metal contacts by low energy (<50 eV) secondary electrons due to inelastic collisions of long range backscattered primary electrons generated from a low dose of high energy (25 keV) electron beam (1 × 1018 e- per cm2). Detailed AFM imaging provides direct evidence of the new mechanism responsible for dynamic evolution of the locally varying graphene doping. The FEBID carbon atoms, which are physisorbed and weakly bound to graphene, diffuse towards the middle of graphene conduction channel due to their surface chemical potential gradient, resulting in negative shift of Dirac voltage. Increasing a primary electron dose to 1 × 1019 e- per cm2 results in a significant increase of carbon deposition, such that it covers the entire graphene conduction channel at high surface density, leading to n-doping of graphene channel. Collectively, these findings establish a unique capability of FEBID technique to dynamically modulate the doping state of graphene, thus enabling a new route to resist-free, ``direct-write'' functional patterning of graphene-based electronic devices with potential for on-demand re-configurability.We report on the first demonstration of controllable carbon doping of graphene to engineer local electronic properties of a graphene conduction channel using focused electron beam induced deposition (FEBID). Electrical measurements indicate that an ``n-p-n'' junction on graphene conduction channel is formed by partial carbon deposition near the source and drain metal contacts by low energy (<50 eV) secondary electrons due to inelastic collisions of long range backscattered primary electrons generated

  2. High performance transistors via aligned polyfluorene-sorted carbon nanotubes

    SciTech Connect

    Brady, Gerald J.; Joo, Yongho; Singha Roy, Susmit; Gopalan, Padma; Arnold, Michael S.

    2014-02-24

    We evaluate the performance of exceptionally electronic-type sorted, semiconducting, aligned single-walled carbon nanotubes (s-SWCNTs) in field effect transistors (FETs). High on-conductance and high on/off conductance modulation are simultaneously achieved at channel lengths which are both shorter and longer than individual s-SWCNTs. The s-SWCNTs are isolated from heterogeneous mixtures using a polyfluorene-derivative as a selective agent and aligned on substrates via dose-controlled, floating evaporative self-assembly at densities of ∼50 s-SWCNTs μm{sup −1}. At a channel length of 9 μm the s-SWCNTs percolate to span the FET channel, and the on/off ratio and charge transport mobility are 2.2 × 10{sup 7} and 46 cm{sup 2} V{sup −1} s{sup −1}, respectively. At a channel length of 400 nm, a large fraction of the s-SWCNTs directly span the channel, and the on-conductance per width is 61 μS μm{sup −1} and the on/off ratio is 4 × 10{sup 5}. These results are considerably better than previous solution-processed FETs, which have suffered from poor on/off ratio due to spurious metallic nanotubes that bridge the channel. 4071 individual and small bundles of s-SWCNTs are tested in 400 nm channel length FETs, and all show semiconducting behavior, demonstrating the high fidelity of polyfluorenes as selective agents and the promise of assembling s-SWCNTs from solution to create high performance semiconductor electronic devices.

  3. All-carbon based graphene field effect transistor with graphitic electrodes fabricated by e-beam direct writing on PMMA.

    PubMed

    Chen, Wei; Yu, Yayun; Zheng, Xiaoming; Qin, Shiqiao; Wang, Fei; Fang, Jingyue; Wang, Guang; Wang, Chaocheng; Wang, Li; Peng, Gang; Zhang, Xue-Ao

    2015-07-21

    A so called all-carbon based graphene field effect transistor (GFET) in which the electrodes are composed of graphite-like nano-sheets instead of metals in the traditional devices is fabricated by one-step e-beam direct writing (EBDW). It is also found that the graphite-like nano-sheets in electrodes are perpendicular to the channel graphene, which is confirmed by the transmission electron microscopy (HRTEM). The one-step fabrication of the carbonaceous electrodes is more convenient and lower-cost comparing to the preparation of traditional metal electrodes and can be applied to many other nano-electronic devices.

  4. All-carbon based graphene field effect transistor with graphitic electrodes fabricated by e-beam direct writing on PMMA

    PubMed Central

    Chen, Wei; Yu, Yayun; Zheng, Xiaoming; Qin, Shiqiao; Wang, Fei; Fang, Jingyue; Wang, Guang; Wang, Chaocheng; Wang, Li; Peng, Gang; Zhang, Xue-Ao

    2015-01-01

    A so called all-carbon based graphene field effect transistor (GFET) in which the electrodes are composed of graphite-like nano-sheets instead of metals in the traditional devices is fabricated by one-step e-beam direct writing (EBDW). It is also found that the graphite-like nano-sheets in electrodes are perpendicular to the channel graphene, which is confirmed by the transmission electron microscopy (HRTEM). The one-step fabrication of the carbonaceous electrodes is more convenient and lower-cost comparing to the preparation of traditional metal electrodes and can be applied to many other nano-electronic devices. PMID:26195033

  5. Ion beam induced charge collection (IBICC) from integrated circuit test structures using a 10 MeV carbon microbeam

    SciTech Connect

    Guo, B. N.; El Bouanani, M.; Duggan, J. L.; McDaniel, F. D.; Renfrow, S. N.; Doyle, B. L.; Walsh, D. S.; Aton, T. J.

    1999-06-10

    As feature sizes of Integrated Circuits (ICs) continue to shrink, the sensitivity of these devices, particularly SRAMs and DRAMs, to natural radiation is increasing. In this paper, the Ion Beam Induced Charge Collection (IBICC) technique is utilized to simulate neutron-induced Si recoil effects in ICs. The IBICC measurements, conducted at the Sandia National Laboratories, employed a 10 MeV carbon microbeam with 1{mu}m diameter spot to scan test structures on specifically designed ICs. With the aid of IC layout information, an analysis of the charge collection efficiency from different test areas is presented.

  6. First-principles simulation and comparison with beam tests for transverse instabilities and damper performance in the Fermilab Main Injector

    SciTech Connect

    Nicklaus, Dennis; Foster, G.William; Kashikhin, Vladimir; /Fermilab

    2005-05-01

    An end-to-end performance calculation and comparison with beam tests was performed for the bunch-by-bunch digital transverse damper in the Fermilab Main Injector. Time dependent magnetic wakefields responsible for ''Resistive Wall'' transverse instabilities in the Main Injector were calculated with OPERA-2D using the actual beam pipe and dipole magnet lamination geometry. The leading order dipole component was parameterized and used as input to a bunch-by-bunch simulation which included the filling pattern and injection errors experienced in high-intensity operation of the Main Injector. The instability growth times, and the spreading of the disturbance due to newly misinjected batches was compared between simulations and beam data collected by the damper system. Further simulation models the effects of the damper system on the beam.

  7. Carbon Dioxide: Surprising Effects on Decision Making and Neurocognitive Performance

    NASA Technical Reports Server (NTRS)

    James, John T.

    2013-01-01

    The occupants of modern submarines and the International Space Station (ISS) have much in common as far as their air quality is concerned. Air is polluted by materials offgassing, use of utility compounds, leaks of systems chemicals, and anthropogenic sources. The primary anthropogenic compound of concern to submariners and astronauts has been carbon dioxide (CO2). NASA and the US Navy rely on the National Research Council Committee on Toxicology (NRC-COT) to help formulate exposure levels to CO2 that are thought to be safe for exposures of 3-6 months. NASA calls its limits Spacecraft Maximum Allowable Concentrations (SMACs). Years of experience aboard the ISS and a recent publication on deficits in decision making in ground-based subjects exposed briefly to 0.25% CO2 suggest that exposure levels that have been presumed acceptable to preserve health and performance need to be reevaluated. The current CO2 exposure limits for 3-6 months set by NASA and the UK Navy are 0.7%, and the limit for US submariners is 0.5%, although the NRC-COT recommended a 90-day level of 0.8% as safe a few years ago. NASA has set a 1000-day SMAC at 0.5% for exploration-class missions. Anecdotal experience with ISS operations approaching the current 180-day SMAC of 0.7% suggest that this limit is too high. Temporarily, NASA has limited exposures to 0.5% until further peer-reviewed data become available. In the meantime, a study published last year in the journal Environmental Health Perspectives (Satish U, et al. 2012) demonstrated that complexdecision- making performance is somewhat affected at 0.1% CO2 and becomes "dysfunctional" for at least half of the 9 indices of performance at concentrations approaching 0.25% CO2. The investigators used the Strategic Management Simulation (SMS) method of testing for decisionmaking ability, and the results were so surprising to the investigators that they declared that their findings need to be independently confirmed. NASA has responded to the

  8. Evaluation of imaging performance of megavoltage cone-beam CT over an extended period

    PubMed Central

    Sumida, Iori; Yamaguchi, Hajime; Kizaki, Hisao; Yamada, Yuji; Koizumi, Masahiko; Yoshioka, Yasuo; Ogawa, Kazuhiko; Kakimoto, Naoya; Murakami, Shumei; Furukawa, Souhei

    2014-01-01

    A linear accelerator vendor and the AAPM TG-142 report propose that quality assurance testing for image-guided devices such megavoltage cone-beam CT (MV-CBCT) be conducted on a monthly basis. In clinical settings, however, unpredictable errors such as image artifacts can occur even when quality assurance results performed at this frequency are within tolerance limits. Here, we evaluated the imaging performance of MV-CBCT on a weekly basis for ∼ 1 year using a Siemens ONCOR machine with a 6-MV X-ray and an image-quality phantom. Image acquisition was undertaken using 15 monitor units. Geometric distortion was evaluated with beads evenly distributed in the phantom, and the results were compared with the expected position in three dimensions. Image-quality characteristics of the system were measured and assessed qualitatively and quantitatively, including image noise and uniformity, low-contrast resolution, high-contrast resolution and spatial resolution. All evaluations were performed 100 times each. For geometric distortion, deviation between the measured and expected values was within the tolerance limit of 2 mm. However, a subtle systematic error was found which meant that the phantom was rotated slightly in a clockwise manner, possibly due to geometry calibration of the MV-CBCT system. Regarding image noise and uniformity, two incidents over tolerance occurred in 100 measurements. This phenomenon disappeared after dose calibration of beam output for MV-CBCT. In contrast, all results for low-contrast resolution, high-contrast resolution and spatial resolution were within their respective tolerances. PMID:23979076

  9. Boosting runtime-performance of photon pencil beam algorithms for radiotherapy treatment planning.

    PubMed

    Siggel, M; Ziegenhein, P; Nill, S; Oelfke, U

    2012-10-01

    Pencil beam algorithms are still considered as standard photon dose calculation methods in Radiotherapy treatment planning for many clinical applications. Despite their established role in radiotherapy planning their performance and clinical applicability has to be continuously adapted to evolving complex treatment techniques such as adaptive radiation therapy (ART). We herewith report on a new highly efficient version of a well-established pencil beam convolution algorithm which relies purely on measured input data. A method was developed that improves raytracing efficiency by exploiting the capability of modern CPU architecture for a runtime reduction. Since most of the current desktop computers provide more than one calculation unit we used symmetric multiprocessing extensively to parallelize the workload and thus decreasing the algorithmic runtime. To maximize the advantage of code parallelization, we present two implementation strategies - one for the dose calculation in inverse planning software, and one for traditional forward planning. As a result, we could achieve on a 16-core personal computer with AMD processors a superlinear speedup factor of approx. 18 for calculating the dose distribution of typical forward IMRT treatment plans. PMID:22071169

  10. Highly stable linear carbonate-containing electrolytes with fluoroethylene carbonate for high-performance cathodes in sodium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lee, Yongwon; Lee, Jaegi; Kim, Hyungsub; Kang, Kisuk; Choi, Nam-Soon

    2016-07-01

    Employing linear carbonates such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as electrolyte solvents provides an opportunity to design appropriate electrolyte systems for high-performance sodium-ion batteries (SIBs). However, in practice, the use of linear carbonate-containing electrolytes is quite challenging because linear carbonates readily decompose at Na metal electrodes or sodiated anodes. One of the promising approaches is using an electrolyte additive to resolve the critical problems related to linear carbonates. Our investigation reveals that remarkable enhancement in electrochemical performance of Na4Fe3(PO4)2(P2O7) cathodes with linear carbonate-containing electrolytes is achieved by using a fluoroethylene carbonate (FEC) additive. Importantly, the initial Coulombic efficiency of the Na deposition/stripping on a stainless steel (SS) electrode is drastically improved from 16% to 90% by introducing the FEC additive into ethylene carbonate (EC)/propylene carbonate (PC)/DEC (5/3/2, v/v/v)/0.5 M NaClO4. The underlying mechanism of FEC at the electrode-electrolyte interface is clearly demonstrated by 13C nuclear magnetic resonance (NMR). In addition, the Na4Fe3(PO4)2(P2O7) cathode in EC/PC/DEC (5/3/2, v/v/v)/0.5 M sodium perchlorate (NaClO4) with FEC delivers a discharge capacity of 90.5 mAh g-1 at a current rate of C/2 and exhibits excellent capacity retention of 97.5% with high Coulombic efficiency of 99.6% after 300 cycles at 30 °C.

  11. Development of long-lived thick carbon stripper foils for high energy heavy ion accelerators by a heavy ion beam sputtering method

    SciTech Connect

    Muto, Hideshi; Ohshiro, Yukimitsu; Kawasaki, Katsunori; Oyaizu, Michihiro; Hattori, Toshiyuki

    2013-04-19

    In the past decade, we have developed extremely long-lived carbon stripper foils of 1-50 {mu}g/cm{sup 2} thickness prepared by a heavy ion beam sputtering method. These foils were mainly used for low energy heavy ion beams. Recently, high energy negative Hydrogen and heavy ion accelerators have started to use carbon stripper foils of over 100 {mu}g/cm{sup 2} in thickness. However, the heavy ion beam sputtering method was unsuccessful in production of foils thicker than about 50 {mu}g/cm{sup 2} because of the collapse of carbon particle build-up from substrates during the sputtering process. The reproduction probability of the foils was less than 25%, and most of them had surface defects. However, these defects were successfully eliminated by introducing higher beam energies of sputtering ions and a substrate heater during the sputtering process. In this report we describe a highly reproducible method for making thick carbon stripper foils by a heavy ion beam sputtering with a Krypton ion beam.

  12. PERFORMING DIAGNOSTICS ON THE SPALLATION NEUTRON SOURCE VISION BEAM LINE TO ELIMINATE HIGH VIBRATION LEVELS AND PROVIDE A SUSTAINABLE OPERATION

    SciTech Connect

    Van Hoy, Blake W

    2014-01-01

    The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) provides variable energy neutrons for a variety of experiments. The neutrons proceed down beam lines to the experiment hall, which houses a variety of experiments and test articles. Each beam line has one or more neutron choppers which filter the neutron beam based on the neutron energy by using a rotating neutron absorbing material passing through the neutron beam. Excessive vibration of the Vision beam line, believed to be caused by the T0 chopper, prevented the Vision beam line from operating at full capacity. This problem had been addressed several times by rebalancing/reworking the T0 beam chopper but the problem stubbornly persisted. To determine the cause of the high vibration, dynamic testing was performed. Twenty-seven accelerometer and motor current channels of data were collected during drive up, drive down, coast down, and steady-state conditions; resonance testing and motor current signature analysis were also performed. The data was analyzed for traditional mechanical/machinery issues such as misalignment and imbalance using time series analysis, frequency domain analysis, and operating deflection shape analysis. The analysis showed that the chopper base plate was experiencing an amplified response to the excitation provided by the T0 beam chopper. The amplified response was diagnosed to be caused by higher than expected base plate flexibility, possibly due to improper grouting or loose floor anchors. Based on this diagnosis, a decision was made to dismantle the beam line chopper and remount the base plate. Neutron activation of the beam line components make modifications to the beam line especially expensive and time consuming due to the radiation handling requirements, so this decision had significant financial and schedule implications. It was found that the base plate was indeed loose because of improper grouting during its initial installation. The base plate was

  13. Recent advances in electron-beam curing of carbon fiber-reinforced composites

    NASA Astrophysics Data System (ADS)

    Coqueret, Xavier; Krzeminski, Mickael; Ponsaud, Philippe; Defoort, Brigitte

    2009-07-01

    Cross-linking polymerization initiated by high-energy radiation is a very attractive technique for the fabrication of high-performance composite materials. The method offers many advantages compared to conventional energy- and time-consuming thermal curing processes. Free radical and cationic poly-addition chemistries have been investigated in some details by various research groups along the previous years. A high degree of control over curing kinetics and material properties can be exerted by adjusting the composition of matrix precursors as well as by acting on process parameters. However, the comparison with state-of-the-art thermally cured composites revealed the lower transverse mechanical properties of radiation-cured composites and the higher brittleness of the radiation-cured matrix. Improving fiber-matrix adhesion and upgrading polymer network toughness are thus two major challenges in this area. We have investigated several points related to these issues, and particularly the reduction of the matrix shrinkage on curing, the wettability of carbon fibers, the design of fiber-matrix interface and the use of thermoplastic toughening agents. Significant improvements were achieved on transverse strain at break by applying original surface treatments on the fibers so as to induce covalent coupling with the matrix. A drastic enhancement of the K IC value exceeding 2 MPa m 1/2 was also obtained for acrylate-based matrices toughened with high T g thermoplastics.

  14. Design and performance of the pulsed positron beam at Chalmers University of Technology

    NASA Astrophysics Data System (ADS)

    Mileshina, L.; Nordlund, A.

    2009-09-01

    A slow monoenergetic pulsed positron beam at Chalmers University of Technology has been built. The system consists mainly of chopper, buncher and accelerator. The achieved positron energy range is in range between 230 eV and 15 keV. The FWHM of the beam resolution function is around 700 ps. The beam intensity is around 103 cps.

  15. High performance quantum cascade lasers: Loss, beam stability, and gain engineering

    NASA Astrophysics Data System (ADS)

    Bouzi, Pierre Michel

    recently emerged with high optical power and high efficiency at cryogenic temperatures. However their performances decay rather rapidly with temperature in both pulsed and continuous wave modes. Through detailed measurements and analysis, we investigate several possible causes of this shortcoming and propose design modifications for temperature performance improvement. While the strong coupling devices are efficient and powerful, their performance often suffers from unintentional and potentially harmful beam steering at high power. Here, we identify the root of this pointing instability to be from non-linear interactions between multiple transverse modes. And, to resolve this issue, we employ focused ion beam (FIB) milling to etch small lateral constrictions on top of the devices and fill them with metal. This has the effect of greatly reducing the intensity of higher order transverse modes as they propagate through the cavity. A good grasp of the microscopic details involved in QC device operations will result in better lasers, with high beam quality. This, in turn, will enable new applications, such as the detection of SO2 isotopologues near 7.4 micron, which is of particular importance for the study of ultraviolet photolysis and the sulfur cycle on Venus.

  16. Performance of positive ion based high power ion source of EAST neutral beam injector.

    PubMed

    Hu, Chundong; Xie, Yahong; Xie, Yuanlai; Liu, Sheng; Xu, Yongjian; Liang, Lizhen; Jiang, Caichao; Li, Jun; Liu, Zhimin

    2016-02-01

    The positive ion based source with a hot cathode based arc chamber and a tetrode accelerator was employed for a neutral beam injector on the experimental advanced superconducting tokamak (EAST). Four ion sources were developed and each ion source has produced 4 MW @ 80 keV hydrogen beam on the test bed. 100 s long pulse operation with modulated beam has also been tested on the test bed. The accelerator was upgraded from circular shaped to diamond shaped in the latest two ion sources. In the latest campaign of EAST experiment, four ion sources injected more than 4 MW deuterium beam with beam energy of 60 keV into EAST.

  17. High performance supercapacitor using porous carbon nanomaterial from corn cob

    NASA Astrophysics Data System (ADS)

    Sharma, Nallin; Mishra, Neeraj; Sharon, Madhuri; Sharon, Maheshwar

    2013-06-01

    Carbon synthesized from corn-cob has been used as an electrode in Electrochemical Double Layer Capacitor (EDLC). Dried Corn Cobs, soaked in 1N KOH, 1N HCl or 5% ZnCl2 at 10 0°C for 24 hr, were pyrolyzed in presence of Ar using Co as catalyst at 700-900 °C having dwell time of 60-180 min. The morphology of thus obtained carbon was studied under SEM that showed it to be porous carbon. All the carbon samples synthesized using different parameters were used as electrode for EDLC. Cyclic Voltammetry was used to measure the capacitance. Carbon synthesized from corn cobs pre-treated with 5% ZnCl2 using Co as catalyst pyrolyzed at 700°C for a dwell time of 120 min gave higher Specific capacitance of 270 F/g at scan rate of 5 mV/s. Moreover, this carbon, as observed under SEM, exhibited larger pore size.

  18. Performance improvement options for the supercritical carbon dioxide brayton cycle.

    SciTech Connect

    Moisseytsev, A.; Sienicki, J. J.; Nuclear Engineering Division

    2008-07-17

    The supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle is under development at Argonne National Laboratory as an advanced power conversion technology for Sodium-Cooled Fast Reactors (SFRs) as well as other Generation IV advanced reactors as an alternative to the traditional Rankine steam cycle. For SFRs, the S-CO{sub 2} Brayton cycle eliminates the need to consider sodium-water reactions in the licensing and safety evaluation, reduces the capital cost of the SFR plant, and increases the SFR plant efficiency. Even though the S-CO{sub 2} cycle has been under development for some time and optimal sets of operating parameters have been determined, those earlier development and optimization studies have largely been directed at applications to other systems such as gas-cooled reactors which have higher operating temperatures than SFRs. In addition, little analysis has been carried out to investigate cycle configurations deviating from the selected 'recompression' S-CO{sub 2} cycle configuration. In this work, several possible ways to improve S-CO{sub 2} cycle performance for SFR applications have been identified and analyzed. One set of options incorporates optimization approaches investigated previously, such as variations in the maximum and minimum cycle pressure and minimum cycle temperature, as well as a tradeoff between the component sizes and the cycle performance. In addition, the present investigation also covers options which have received little or no attention in the previous studies. Specific options include a 'multiple-recompression' cycle configuration, intercooling and reheating, as well as liquid-phase CO{sub 2} compression (pumping) either by CO{sub 2} condensation or by a direct transition from the supercritical to the liquid phase. Some of the options considered did not improve the cycle efficiency as could be anticipated beforehand. Those options include: a double recompression cycle, intercooling between the compressor stages, and reheating

  19. Physical performance and image optimization of megavoltage cone-beam CT

    SciTech Connect

    Morin, Olivier; Aubry, Jean-Francois; Aubin, Michele; Chen, Josephine; Descovich, Martina; Hashemi, Ali-Bani; Pouliot, Jean

    2009-04-15

    Megavoltage cone-beam CT (MVCBCT) is the most recent addition to the in-room CT systems developed for image-guided radiation therapy. The first generation MVCBCT system consists of a 6 MV treatment x-ray beam produced by a conventional linear accelerator equipped with a flat panel amorphous silicon detector. The objective of this study was to evaluate the physical performance of MVCBCT in order to optimize the system acquisition and reconstruction parameters for image quality. MVCBCT acquisitions were performed with the clinical system but images were reconstructed and analyzed with a separate research workstation. The geometrical stability and the positioning accuracy of the system were evaluated by comparing geometrical calibrations routinely performed over a period of 12 months. The beam output and detector intensity stability during MVCBCT acquisition were also evaluated by analyzing in-air acquisitions acquired at different exposure levels. Several system parameters were varied to quantify their impact on image quality including the exposure (2.7, 4.5, 9.0, 18.0, and 54.0 MU), the craniocaudal imaging length (2, 5, 15, and 27.4 cm), the voxel size (0.5, 1, and 2 mm), the slice thickness (1, 3, and 5 mm), and the phantom size. For the reconstruction algorithm, the study investigated the effect of binning, averaging and diffusion filtering of raw projections as well as three different projection filters. A head-sized water cylinder was used to measure and improve the uniformity of MVCBCT images. Inserts of different electron densities were placed in a water cylinder to measure the contrast-to-noise ratio (CNR). The spatial resolution was obtained by measuring the point-spread function of the system using an iterative edge blurring technique. Our results showed that the geometric stability and accuracy of MVCBCT were better than 1 mm over a period of 12 months. Beam intensity variations per projection of up to 35.4% were observed for a 2.7 MU MVCBCT acquisition

  20. Beam performance and luminosity limitations in the high-energy storage ring (HESR)

    NASA Astrophysics Data System (ADS)

    Lehrach, A.; Boine-Frankenheim, O.; Hinterberger, F.; Maier, R.; Prasuhn, D.

    2006-06-01

    The high-energy storage ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an antiproton synchrotron storage ring in the momentum range 1.5-15 GeV/ c. An important feature of this new facility is the combination of phase space cooled beams and dense internal targets (e.g. pellet targets), which results in demanding beam parameter requirements for two operation modes: high luminosity mode with peak luminosities to 2×10 32 cm -2 s -1, and high-resolution mode with a momentum spread down to 10 -5. To reach these beam parameters one needs a very powerful phase space cooling, utilizing high-energy electron cooling and high-bandwidth stochastic cooling. The effects of beam-target scattering and intra-beam interaction are investigated in order to study beam equilibria and beam losses for the two different operation modes.

  1. Effects of Carbon Structure and Surface Oxygen on the Carbon's Performance as the Anode in Lithium-Ion Battery Determined

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    2000-01-01

    Four carbon materials (C1, C2, C3, and C4) were tested electrochemically at the NASA Glenn Research Center at Lewis Field to determine their performance in lithium-ion batteries. They were formed as shown in the figure. This process caused very little carbon loss. Products C1 and C3 contained very little oxygen because of the final overnight heating at 540 C. Products C2 and C4, on the other hand, contained small amounts of basic oxide. The electrochemical test involved cycles of lithium intercalation and deintercalation using C/saturated LiI-50/50 (vol %) ethylene carbonate (EC) and dimethyl carbonate (DMC)/Li half cell. The cycling test, which is summarized in the table, resulted in three major conclusions. The capacity of the carbon with a basic oxide surface converges to a constant 1. value quickly (within 4 cycles), possibly because the oxide prevents solvent from entering the carbon structure and, therefore, prolongs the carbon s cycle life. Under certain conditions, the disordered carbon can store more lithium than its 2. precursor. These samples and their precursor can intercalate at 200 mA/g and deintercalate at 3. a rate of 2000 mA/g without significant capacity loss.

  2. Investigation of surface characteristics evolution and laser damage performance of fused silica during ion-beam sputtering

    NASA Astrophysics Data System (ADS)

    Xu, Mingjin; Dai, Yifan; Zhou, Lin; Shi, Feng; Wan, Wen; Xie, Xuhui; Sui, Tingting

    2016-08-01

    Surface characteristics have great influence on the optical properties especially the laser radiation resistivity of optics. In this paper, the surface characteristics evolutions of fused silica during ion-beam sputtering and their effects on the laser damage performance were investigated. The results show that roughness change is strongly removal depth dependent and a super-smooth surface (0.25 nm RMS) can be obtained by the ion-induced smoothing effect. The concentration of metal impurities (especially Ce element) in subsurface can be effectively decreased after the removal of polishing re-deposition layer. During ion-beam sputtering process, the plastic scratches can be removed while the brittle cracks can be broadened and passivated without increase in the depth direction. Laser damage threshold of fused silica improved by 36% after ion-beam sputtering treatment. Research results have a guiding significance for ion-beam sputtering process technology of fused silica optics.

  3. Cathode performance during two beam operation of the high current high polarization electron gun for eRHIC

    SciTech Connect

    Rahman, O.; Ben-Zvi, I.; Degen, C.; Gassner, D. M.; Lambiase, R.; Meng, W.; Pikin, A.; Rao, T.; Sheehy, B.; Skaritka, J.; Wang, E.; Pietz, J.; Ackeret, M.; Yeckel, C.; Miller, R.; Dobrin, E.; Thompson, K.

    2015-05-03

    Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place in Stangenes Industries in Palo Alto, CA, where the cathodes were placed in diagonally opposite locations inside the high voltage shroud. No significant cross talking between the cathodes was found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.

  4. Characterization and restoration of performance of {open_quotes}aged{close_quotes} radioiodine removing activated carbons

    SciTech Connect

    Freeman, W.P.

    1997-08-01

    The degradation of radioiodine removal performance for impregnated activated carbons because of ageing is well established. However, the causes for this degradation remain unclear. One theory is that this reduction in performance from the ageing process results from an oxidation of the surface of the carbon. Radioiodine removing activated carbons that failed radioiodine removal tests showed an oxidized surface that had become hydrophilic compared with new carbons. We attempted to restore the performance of these {open_quotes}failed{close_quotes} carbons with a combination of thermal and chemical treatment. The results of these investigations are presented and discussed with the view of extending the life of radioiodine removing activated carbons. 4 refs., 2 tabs.

  5. Geant4 simulation for a study of a possible use of carbon ion pencil beams for the treatment of ocular melanomas with the active scanning system at CNAO

    NASA Astrophysics Data System (ADS)

    Farina, E.; Piersimoni, P.; Riccardi, C.; Rimoldi, A.; Tamborini, A.; Ciocca, M.

    2015-12-01

    The aim of this work was to study a possible use of carbon ion pencil beams (delivered with active scanning modality) for the treatment of ocular melanomas at the Centro Nazionale di Adroterapia Oncologica (CNAO). The promising aspect of carbon ions radiotherapy for the treatment of this disease lies in its superior relative radio-biological effectiveness (RBE). The Monte Carlo (MC) Geant4 10.00 toolkit was used to simulate the complete CNAO extraction beamline, with the active and passive components along it. A human eye modeled detector, including a realistic target tumor volume, was used as target. Cross check with previous studies at CNAO using protons allowed comparisons on possible benefits on using such a technique with respect to proton beams. Experimental data on proton and carbon ion beams transverse distributions were used to validate the simulation.

  6. Effect of secondary particles on image quality of dynamic flat panels in carbon ion scanning beam treatment

    PubMed Central

    Amano, S; Furukawa, T; Shirai, T; Noda, K

    2015-01-01

    Objective: Real-time markerless tumour tracking using radiographic fluoroscopic imaging is one of the better solutions to improving respiratory-gated radiotherapy. However, particle beams cause secondary particles from patients, which could affect radiographs. Here, we evaluated the quality of radiographs during carbon ion pencil beam scanning (CPBS) irradiation for respiratory gating. Methods: A water phantom and chest phantom were used. The phantoms were irradiated with CPBS at 290 MeV n−1 from orthogonal directions. Dose rates were 3.4 × 108, 1.14 × 108 and 3.79 × 107 particles per second. A dynamic flat panel detector (DFPD) was installed on the upstream (DFPD1) or downstream (DFPD2) side of the vertical irradiation port. DFPD images were acquired during CPBS at 15.00, 7.50 and 3.75 frames per second (fps). Charge on the DFPD was cleaned using fast readout technique every 30 fps. DFPD images were acquired during CPBS with radiographic exposure, and results with and without fast readout technique were compared. Results: Secondary particles were visualized as spots or streak-like shapes. Capture of secondary particles from the horizontal beam direction was lower with fast readout technique than without it. With regard to beam irradiation direction dependency, CPBS from the horizontal direction resulted in a greater magnitude of secondary particles reaching DFPD2 than reaching DFPD1. When CPBS was delivered from the vertical direction, however, the magnitude of secondary particles on both DFPDs was very similar. Conclusion: Fast readout technique minimized the effect of secondary particles on DFPD images during CPBS. Advances in knowledge: This technique may be useful for markerless tumour tracking for respiratory gating. PMID:25536444

  7. Computer simulations and models for the performance characteristics of spectrally equivalent X-ray beams in medical diagnostic radiology

    PubMed Central

    Okunade, Akintunde A.

    2007-01-01

    In order to achieve uniformity in radiological imaging, it is recommended that the concept of equivalence in shape (quality) and size (quantity) of clinical Xray beams should be used for carrying out the comparative evaluation of image and patient dose. When used under the same irradiation geometry, X-ray beams that are strictly or relatively equivalent in terms of shape and size will produce identical or relatively identical image quality and patient dose. Simple mathematical models and software program EQSPECT.FOR were developed for the comparative evaluation of the performance characteristics in terms of contrast (C), contrast to noise ratio (CNR) and figure-of-merit (FOM = CNR2/DOSE) for spectrally equivalent beams transmitted through filter materials referred to as conventional and k-edged. At the same value of operating potential (kVp), results show that spectrally equivalent beam transmitted through conventional filter with higher atomic number (Z-value) in comparison with that transmitted through conventional filter with lower Z-value resulted in the same value of C and FOM. However, in comparison with the spectrally equivalent beam transmitted through filter of lower Z-value, the beam through filter of higher Z-value produced higher value of CNR and DOSE at equal tube loading (mAs) and kVp. Under the condition of equivalence of spectrum, at scaled (or reduced) tube loading and same kVp, filter materials of higher Z-value can produce the same values of C, CNR, DOSE and FOM as filter materials of lower Z-value. Unlike the case of comparison of spectrally equivalent beam transmitted through one conventional filter and that through another conventional filter, it is not possible to derive simple mathematical formulations for the relative performance of spectrally equivalent beam transmitted through a given conventional filter material and that through kedge filter material. PMID:21224928

  8. Ion beam analysis of tungsten layers in EUROFER model systems and carbon plasma facing components

    NASA Astrophysics Data System (ADS)

    Ström, Petter; Petersson, Per; Rubel, Marek; Primetzhofer, Daniel; Brezinsek, Sebastijan; Kreter, Arkadi; Unterberg, Bernhard; Sergienko, Gennady; Sugiyama, Kazuyoshi

    2016-03-01

    The tungsten enriched surface layers in two fusion-relevant EUROFER steel model samples, consisting of an iron-tungsten mixture exposed to sputtering by deuterium ions, were studied by Rutherford backscattering spectrometry and medium energy ion scattering. Exposure conditions were the same for the two samples and the total amount of tungsten atoms per unit area in the enriched layers were similar (2 · 1015 and 2.4 · 1015 atoms/cm2 respectively), despite slightly different initial atomic compositions. A depth profile featuring exponential decrease in tungsten content towards higher depths with 10-20 at.% of tungsten at the surface and a decay constant between 0.05 and 0.08 Å-1 was indicated in one sample, whereas only the total areal density of tungsten atoms was measured in the other. In addition, two different beams, iodine and chlorine, were employed for elastic recoil detection analysis of the deposited layer on a polished graphite plate from a test limiter in the TEXTOR tokamak following experiments with tungsten hexafluoride injection. The chlorine beam was preferred for tungsten analysis, mainly because it (as opposed to the iodine beam) does not give rise to problems with overlap of forward scattered beam particles and recoiled tungsten in the spectrum.

  9. A 30-cm mercury ion thruster performance with a 1 kW capacitor-diode voltage multiplier beam supply

    NASA Technical Reports Server (NTRS)

    Terdan, F. F.; Harrigill, W. T., Jr.

    1978-01-01

    A 1 kW solar array and capacitor-diode voltage multiplier converter (S/A-CDVM) was successfully integrated with a 30 cm diameter mercury ion thruster system to provide ion beam power. Measurements were made to compare steady state and transient response performance of a conventional bridge converter with the S/A-CDVM converter used for the ion beam supply. The ability to recover from screen to accelerator arcs and promptly re-establish stable thruster performance was demonstrated. Solar array transient response to thruster arcing was measured.

  10. Radiosensitizing effect of carboplatin and paclitaxel to carbon-ion beam irradiation in the non-small-cell lung cancer cell line H460.

    PubMed

    Kubo, Nobuteru; Noda, Shin-ei; Takahashi, Akihisa; Yoshida, Yukari; Oike, Takahiro; Murata, Kazutoshi; Musha, Atsushi; Suzuki, Yoshiyuki; Ohno, Tatsuya; Takahashi, Takeo; Nakano, Takashi

    2015-03-01

    The present study investigated the ability of carboplatin and paclitaxel to sensitize human non-small-cell lung cancer (NSCLC) cells to carbon-ion beam irradiation. NSCLC H460 cells treated with carboplatin or paclitaxel were irradiated with X-rays or carbon-ion beams, and radiosensitivity was evaluated by clonogenic survival assay. Cell proliferation was determined by counting the number of viable cells using Trypan blue. Apoptosis and senescence were evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining and senescence-associated β-galactosidase (SA-β-gal) staining, respectively. The expression of cleaved caspase-3, Bax, p53 and p21 was analyzed by western blotting. Clonogenic survival assays demonstrated a synergistic radiosensitizing effect of carboplatin and paclitaxel with carbon-ion beams; the sensitizer enhancement ratios (SERs) at the dose giving a 10% survival fraction (D10) were 1.21 and 1.22, respectively. Similarly, carboplatin and paclitaxel showed a radiosensitizing effect with X-rays; the SERs were 1.41 and 1.29, respectively. Cell proliferation assays validated the radiosensitizing effect of carboplatin and paclitaxel with both carbon-ion beam and X-ray irradiation. Carboplatin and paclitaxel treatment combined with carbon-ion beams increased TUNEL-positive cells and the expression of cleaved caspase-3 and Bax, indicating the enhancement of apoptosis. The combined treatment also increased SA-β-gal-positive cells and the expression of p53 and p21, indicating the enhancement of senescence. In summary, carboplatin and paclitaxel radiosensitized H460 cells to carbon-ion beam irradiation by enhancing irradiation-induced apoptosis and senescence.

  11. Nickel clusters embedded in carbon nanotubes as high performance magnets

    NASA Astrophysics Data System (ADS)

    Shiozawa, Hidetsugu; Briones-Leon, Antonio; Domanov, Oleg; Zechner, Georg; Sato, Yuta; Suenaga, Kazu; Saito, Takeshi; Eisterer, Michael; Weschke, Eugen; Lang, Wolfgang; Peterlik, Herwig; Pichler, Thomas

    2015-10-01

    Ensembles of fcc nickel nanowires have been synthesized with defined mean sizes in the interior of single-wall carbon nanotubes. The method allows the intrinsic nature of single-domain magnets to emerge with large coercivity as their size becomes as small as the exchange length of nickel. By means of X-ray magnetic circular dichroism we probe electronic interactions at nickel-carbon interfaces where nickel exhibit no hysteresis and size-dependent spin magnetic moment. A manifestation of the interacting two subsystems on a bulk scale is traced in the nanotube’s magnetoresistance as explained within the framework of weak localization.

  12. Nickel clusters embedded in carbon nanotubes as high performance magnets

    PubMed Central

    Shiozawa, Hidetsugu; Briones-Leon, Antonio; Domanov, Oleg; Zechner, Georg; Sato, Yuta; Suenaga, Kazu; Saito, Takeshi; Eisterer, Michael; Weschke, Eugen; Lang, Wolfgang; Peterlik, Herwig; Pichler, Thomas

    2015-01-01

    Ensembles of fcc nickel nanowires have been synthesized with defined mean sizes in the interior of single-wall carbon nanotubes. The method allows the intrinsic nature of single-domain magnets to emerge with large coercivity as their size becomes as small as the exchange length of nickel. By means of X-ray magnetic circular dichroism we probe electronic interactions at nickel-carbon interfaces where nickel exhibit no hysteresis and size-dependent spin magnetic moment. A manifestation of the interacting two subsystems on a bulk scale is traced in the nanotube’s magnetoresistance as explained within the framework of weak localization. PMID:26459370

  13. Beam-based analysis of day-night performance variations at the SLC linac

    SciTech Connect

    Decker, F.J.; Akre, R.; Assmann, R.; Bane, K.L.F.; Minty, M.G.; Phinney, N.; Spence, W.L.

    1998-07-01

    Diurnal temperature variations in the linac gallery of the Stanford Linear Collider (SLC) can affect the amplitude and phase of the rf used to accelerate the beam. The SLC employs many techniques for stabilization and compensation of these effects, but residual uncorrected changes still affect the quality of the delivered beam. This paper presents methods developed to monitor and investigate these errors through the beam response. Variations resulting from errors in the rf amplitude or phase can be distinguished by studying six different beam observables: betatron phase advance, oscillation amplitude growth, rms jitter along the linac, measurements of the beam phase with respect to the rf, changes in the required injection phase, and the global energy correction factor. By quantifying the beam response, an uncorrected variation of 14{sup o} (S-band) during 28 F temperature swings was found in the main rf drive line system between the front and end of the linac.

  14. Dosimetric study of mandible examinations performed with three cone-beam computed tomography scanners.

    PubMed

    Khoury, Helen J; Andrade, Marcos E; Araujo, Max Well; Brasileiro, Izabela V; Kramer, Richard; Huda, Amir

    2015-07-01

    The objective of this work was to evaluate the air kerma-area product (PKA) and the skin absorbed dose in the region of the eyes, salivary glands and thyroid of the patient from mandible examinations performed with three cone-beam computed tomography (CBCT) scanners, i.e. i-CAT classic, Gendex CB-500 and PreXion 3D. For the dosimetric evaluation, an anthropomorphic head phantom (model RS-250) was used to simulate an adult patient. The CBCT examinations were performed using standard and high-resolution protocols for mandible acquisitions for adult patients. During the phantom's exposure, the PKA was measured using an ionising chamber and the absorbed doses to the skin in the region of the eyes, thyroid and salivary glands were estimated using thermoluminescence dosemeters (TLDs) positioned on the phantom's surface. The PKA values estimated with the CBCT scanners varied from 26 to 138 µGy m(2). Skin absorbed doses in the region of the eyes varied from 0.07 to 0.34 mGy; at the parotid glands, from 1.31 to 5.93 mGy; at the submandibular glands, from 1.41 to 6.86 mGy; and at the thyroid, from 0.18 to 2.45 mGy. PKA and absorbed doses showed the highest values for the PreXion 3D scanner due to the use of the continuous exposure mode and a high current-time product.

  15. Atomistic description of electron beam damage in nitrogen-doped graphene and single-walled carbon nanotubes.

    PubMed

    Susi, Toma; Kotakoski, Jani; Arenal, Raul; Kurasch, Simon; Jiang, Hua; Skakalova, Viera; Stephan, Odile; Krasheninnikov, Arkady V; Kauppinen, Esko I; Kaiser, Ute; Meyer, Jannik C

    2012-10-23

    By combining ab initio simulations with state-of-the-art electron microscopy and electron energy loss spectroscopy, we study the mechanism of electron beam damage in nitrogen-doped graphene and carbon nanotubes. Our results show that the incorporation of nitrogen atoms results in noticeable knock-on damage in these structures already at an acceleration voltage of 80 kV, at which essentially no damage is created in pristine structures at corresponding doses. Contrary to an early estimate predicting rapid destruction via sputtering of the nitrogen atoms, in the case of substitutional doping, damage is initiated by displacement of carbon atoms neighboring the nitrogen dopant, leading to the conversion of substitutional dopant sites into pyridinic ones. Although such events are relatively rare at 80 kV, they become significant at higher voltages typically used in electron energy loss spectroscopy studies. Correspondingly, we measured an energy loss spectrum time series at 100 kV that provides direct evidence for such conversions in nitrogen-doped single-walled carbon nanotubes, in excellent agreement with our theoretical prediction. Besides providing an improved understanding of the irradiation stability of these structures, we show that structural changes cannot be neglected in their characterization employing high-energy electrons.

  16. Beam dynamics and expected RHIC performance with 56MHz RF upgrade

    SciTech Connect

    Fedotov,A.V.; Ben-Zvi, I.

    2009-05-04

    An upgrade of the RHIC storage RF system with a superconducting 56 MHz cavity was recently proposed. This upgrade will provide a significant increase in the acceptance of the RHIC 197 MHz storage RF bucket. This paper summarizes simulations of beam evolution due to intra-beam scattering (IBS) for beam parameters expected with the 56 MHz SRF cavity upgrade. Expected luminosity improvements are shown for Au ions at 100 GeV/nucleon and protons at 250 GeV.

  17. Flexible carbon nanotube films for high performance strain sensors.

    PubMed

    Kanoun, Olfa; Müller, Christian; Benchirouf, Abderahmane; Sanli, Abdulkadir; Dinh, Trong Nghia; Al-Hamry, Ammar; Bu, Lei; Gerlach, Carina; Bouhamed, Ayda

    2014-01-01

    Compared with traditional conductive fillers, carbon nanotubes (CNTs) have unique advantages, i.e., excellent mechanical properties, high electrical conductivity and thermal stability. Nanocomposites as piezoresistive films provide an interesting approach for the realization of large area strain sensors with high sensitivity and low manufacturing costs. A polymer-based nanocomposite with carbon nanomaterials as conductive filler can be deposited on a flexible substrate of choice and this leads to mechanically flexible layers. Such sensors allow the strain measurement for both integral measurement on a certain surface and local measurement at a certain position depending on the sensor geometry. Strain sensors based on carbon nanostructures can overcome several limitations of conventional strain sensors, e.g., sensitivity, adjustable measurement range and integral measurement on big surfaces. The novel technology allows realizing strain sensors which can be easily integrated even as buried layers in material systems. In this review paper, we discuss the dependence of strain sensitivity on different experimental parameters such as composition of the carbon nanomaterial/polymer layer, type of polymer, fabrication process and processing parameters. The insights about the relationship between film parameters and electromechanical properties can be used to improve the design and fabrication of CNT strain sensors. PMID:24915183

  18. Flexible Carbon Nanotube Films for High Performance Strain Sensors

    PubMed Central

    Kanoun, Olfa; Müller, Christian; Benchirouf, Abderahmane; Sanli, Abdulkadir; Dinh, Trong Nghia; Al-Hamry, Ammar; Bu, Lei; Gerlach, Carina; Bouhamed, Ayda

    2014-01-01

    Compared with traditional conductive fillers, carbon nanotubes (CNTs) have unique advantages, i.e., excellent mechanical properties, high electrical conductivity and thermal stability. Nanocomposites as piezoresistive films provide an interesting approach for the realization of large area strain sensors with high sensitivity and low manufacturing costs. A polymer-based nanocomposite with carbon nanomaterials as conductive filler can be deposited on a flexible substrate of choice and this leads to mechanically flexible layers. Such sensors allow the strain measurement for both integral measurement on a certain surface and local measurement at a certain position depending on the sensor geometry. Strain sensors based on carbon nanostructures can overcome several limitations of conventional strain sensors, e.g., sensitivity, adjustable measurement range and integral measurement on big surfaces. The novel technology allows realizing strain sensors which can be easily integrated even as buried layers in material systems. In this review paper, we discuss the dependence of strain sensitivity on different experimental parameters such as composition of the carbon nanomaterial/polymer layer, type of polymer, fabrication process and processing parameters. The insights about the relationship between film parameters and electromechanical properties can be used to improve the design and fabrication of CNT strain sensors. PMID:24915183

  19. Fabrication of carbon/SiO2 composites from the hydrothermal carbonization process of polysaccharide and their adsorption performance.

    PubMed

    Li, Yinhui; Li, Kunyu; Su, Min; Ren, Yanmei; Li, Ying; Chen, Jianxin; Li, Liang

    2016-11-20

    In this work, carbon/SiO2 composites, using amylose and tetraethyl orthosilicate (TEOS) as raw materials, were successfully prepared by a facial hydrothermal carbonization process. The carbon/SiO2 composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive Spectroscopy (EDS), transmission electron microscope (TEM), N2 adsorption and Thermogravimetric (TG) analysis. The composites, which were made up of amorphous SiO2 and amorphous carbon, were found to have hierarchical porous structures. The mass ratios of amylose and SiO2 and the hydrothermal carbonization time had significant effects on the morphology of the composites, which had three shapes including monodispersed spheres, porous pieces and the nano-fibers combined with nano-spheres structures. The adsorption performance of the composites was studied using Pb(2+) as simulated contaminants from water. When the mass ratio of amylose and SiO2 was 9/1, the hydrothermal time was 30h and the hydrothermal temperature was 180°C, the adsorption capacity of the composites achieved to 52mg/g. Experimental data show that adsorption kinetics of the carbon/SiO2 composites can be fitted well by the Elovich model, while the isothermal data can be perfectly described by the Langmuir adsorption model and Freundlich adsorption model. The maximum adsorption capacity of the carbon/SiO2 composites is 56.18mgg(-1). PMID:27561502

  20. Fabrication of carbon/SiO2 composites from the hydrothermal carbonization process of polysaccharide and their adsorption performance.

    PubMed

    Li, Yinhui; Li, Kunyu; Su, Min; Ren, Yanmei; Li, Ying; Chen, Jianxin; Li, Liang

    2016-11-20

    In this work, carbon/SiO2 composites, using amylose and tetraethyl orthosilicate (TEOS) as raw materials, were successfully prepared by a facial hydrothermal carbonization process. The carbon/SiO2 composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive Spectroscopy (EDS), transmission electron microscope (TEM), N2 adsorption and Thermogravimetric (TG) analysis. The composites, which were made up of amorphous SiO2 and amorphous carbon, were found to have hierarchical porous structures. The mass ratios of amylose and SiO2 and the hydrothermal carbonization time had significant effects on the morphology of the composites, which had three shapes including monodispersed spheres, porous pieces and the nano-fibers combined with nano-spheres structures. The adsorption performance of the composites was studied using Pb(2+) as simulated contaminants from water. When the mass ratio of amylose and SiO2 was 9/1, the hydrothermal time was 30h and the hydrothermal temperature was 180°C, the adsorption capacity of the composites achieved to 52mg/g. Experimental data show that adsorption kinetics of the carbon/SiO2 composites can be fitted well by the Elovich model, while the isothermal data can be perfectly described by the Langmuir adsorption model and Freundlich adsorption model. The maximum adsorption capacity of the carbon/SiO2 composites is 56.18mgg(-1).

  1. Toward uniform and ultrathin carbon layer coating on lithium iron phosphate using liquid carbon dioxide for enhanced electrochemical performance

    NASA Astrophysics Data System (ADS)

    Hong, Seung-Ah; Kim, Dong Hyun; Chung, Kyung Yoon; Chang, Wonyoung; Yoo, Jibeom; Kim, Jaehoon

    2014-09-01

    In this communication, uniform and ultrathin carbon coating on LiFePO4 (LFP) particles are performed using liquid carbon dioxide (l-CO2)-based free-meniscus coating. The uniform and conformal coverage of the carbon layer on LFP with a thickness of 3.3 nm, and a uniform distribution of carbon on the entire surface of the LFP particle are confirmed. The carbon-coated LFP (C-LFP) with a carbon content of 1.9 wt.% obtained using l-CO2-based coating exhibits a discharge capacity of 169 mAh g-1 at 0.1 C and 71 mAh g-1 at 30 C, while much lower discharge capacity of 146 mAh g-1 at 0.1 C and 17 mAh g-1 at 30 C is observed when C-LFP with an optimized carbon content of 6.0 wt.% is prepared using conventional aqueous-based coating.

  2. Enhanced performance of electrospun carbon fibers modified with carbon nanotubes: promising electrodes for enzymatic biofuel cells

    NASA Astrophysics Data System (ADS)

    Both Engel, A.; Cherifi, A.; Tingry, S.; Cornu, D.; Peigney, A.; Laurent, Ch

    2013-06-01

    New nanostructured electrodes, promising for the production of clean and renewable energy in biofuel cells, were developed with success. For this purpose, carbon nanofibers were produced by the electrospinning of polyacrylonitrile solution followed by convenient thermal treatments (stabilization followed by carbonization at 1000, 1200 and 1400° C), and carbon nanotubes were adsorbed on the surfaces of the fibers by a dipping method. The morphology of the developed electrodes was characterized by several techniques (SEM, Raman spectroscopy, electrical conductivity measurement). The electrochemical properties were evaluated through cyclic voltammetry, where the influence of the carbonization temperature of the fibers and the beneficial contribution of the carbon nanotubes were observed through the reversibility and size of the redox peaks of K3Fe(CN)6 versus Ag/AgCl. Subsequently, redox enzymes were immobilized on the electrodes and the electroreduction of oxygen to water was realized as a test of their efficiency as biocathodes. Due to the fibrous and porous structure of these new electrodes, and to the fact that carbon nanotubes may have the ability to promote electron transfer reactions of redox biomolecules, the new electrodes developed were capable of producing higher current densities than an electrode composed only of electrospun carbon fibers.

  3. Enhanced performance of electrospun carbon fibers modified with carbon nanotubes: promising electrodes for enzymatic biofuel cells.

    PubMed

    Engel, A Both; Cherifi, A; Tingry, S; Cornu, D; Peigney, A; Laurent, Ch

    2013-06-21

    New nanostructured electrodes, promising for the production of clean and renewable energy in biofuel cells, were developed with success. For this purpose, carbon nanofibers were produced by the electrospinning of polyacrylonitrile solution followed by convenient thermal treatments (stabilization followed by carbonization at 1000, 1200 and 1400° C), and carbon nanotubes were adsorbed on the surfaces of the fibers by a dipping method. The morphology of the developed electrodes was characterized by several techniques (SEM, Raman spectroscopy, electrical conductivity measurement). The electrochemical properties were evaluated through cyclic voltammetry, where the influence of the carbonization temperature of the fibers and the beneficial contribution of the carbon nanotubes were observed through the reversibility and size of the redox peaks of K3Fe(CN)6 versus Ag/AgCl. Subsequently, redox enzymes were immobilized on the electrodes and the electroreduction of oxygen to water was realized as a test of their efficiency as biocathodes. Due to the fibrous and porous structure of these new electrodes, and to the fact that carbon nanotubes may have the ability to promote electron transfer reactions of redox biomolecules, the new electrodes developed were capable of producing higher current densities than an electrode composed only of electrospun carbon fibers.

  4. High-performance carbon nanotube-implanted mesoporous carbon spheres for supercapacitors with low series resistance

    SciTech Connect

    Yi, Bin; Chen, Xiaohua; Guo, Kaimin; Xu, Longshan; Chen, Chuansheng; Yan, Haimei; Chen, Jianghua

    2011-11-15

    Research highlights: {yields} CNTs-implanted porous carbon spheres are prepared by using gelatin as soft template. {yields} Homogeneously distributed CNTs form a well-develop network in carbon spheres. {yields} CNTs act as a reinforcing backbone assisting the formation of pore structure. {yields} CNTs improve electrical conductivity and specific capacitance of supercapacitor. -- Abstract: Carbon nanotube-implanted mesoporous carbon spheres were prepared by an easy polymerization-induced colloid aggregation method using gelatin as a soft template. Scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption measurements reveal that the materials are mesoporous carbon spheres, with a diameter of {approx}0.5-1.0 {mu}m, a specific surface area of 284 m{sup 2}/g and average pore size of 3.9 nm. Using the carbon nanotube-implanted mesoporous carbon spheres as electrode material for supercapacitors in an aqueous electrolyte solution, a low equivalent series resistance of 0.83 {Omega} cm{sup 2} and a maximum specific capacitance of 189 F/g with a measured power density of 8.7 kW/kg at energy density of 6.6 Wh/kg are obtained.

  5. The molten carbonate carbon dioxide concentrator - Cathode performance at high CO2 utilization. [in manned space station cabin atmospheres

    NASA Technical Reports Server (NTRS)

    Weaver, J. L.; Winnick, J.

    1983-01-01

    An experimental study of the cathode performance of the molten carbonate carbon dioxide concentrator (MCCDC) at typical gas concentrations is reported, and the behavior is described in terms of standard electrochemical kinetic analysis. Theoretical aspects of the MCCDC are discussed, including the current-generating processes, the overpotential, and the reaction kinetics. A final working equation is derived, and the electrochemical cell is described. The parameters determined by the experiments include cathode overpotentials and removal and current efficiency as a function of current density, as well as carbon dioxide removal rate as a function of flow rate. The results are compared with data for other cells; the agreement with data for the molten carbonate fuel cell suggests that the major difference between the two cells is in the wetting characteristics. The MCCDC achieves high removal efficiencies at high current efficiencies. The lowest current efficiency recorded was 80 percent, and at most current densities, current efficiencies were above 100 percent.

  6. 3D hybrid-porous carbon derived from carbonization of metal organic frameworks for high performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Bao, Weizhai; Mondal, Anjon Kumar; Xu, Jing; Wang, Chengyin; Su, Dawei; Wang, Guoxiu

    2016-09-01

    We report a rational design and synthesis of 3D hybrid-porous carbon with a hierarchical pore architecture for high performance supercapacitors. It contains micropores (<2 nm diameter) and mesopores (2-4 nm), derived from carbonization of unique porous metal organic frameworks (MOFs). Owning to the synergistic effect of micropores and mesopores, the hybrid-porous carbon has exceptionally high ion-accessible surface area and low ion diffusion resistance, which is desired for supercapacitor applications. When applied as electrode materials in supercapacitors, 3D hybrid-porous carbon demonstrates a specific capacitance of 332 F g-1 at a constant charge/discharge current of 500 mA g-1. The supercapacitors can endure more than 10,000 cycles without degradation of capacitance.

  7. Performance Characteristics and Quality Assurance Aspects of Kilovoltage Cone-Beam CT on Medical Linear Accelerator

    SciTech Connect

    Saw, Cheng B. . E-mail: cbsaw2003@yahoo.com; Yang, Yong; Li Fang; Yue, Ning J.; Ding Chuxiong; Komanduri, Krishna; Huq, Saiful; Heron, Dwight E.

    2007-07-01

    A medical linear accelerator equipped with optical position tracking, ultrasound imaging, portal imaging, and radiographic imaging systems was installed at University of Pittsburgh Cancer Institute for the purpose of performing image-guided radiation therapy (IGRT) and image-guided radiosurgery (IGRS) in October 2005. We report the performance characteristics and quality assurance aspects of the kilovoltage cone-beam computed tomography (kV-CBCT) technique. This radiographic imaging system consists of a kilovoltage source and a large-area flat panel amorphous silicon detector mounted on the gantry of the medical linear accelerator via controlled arms. The performance characteristics and quality assurance aspects of this kV-CBCT technique involves alignment of the kilovoltage imaging system to the isocenter of the medical linear accelerator and assessment of (a) image contrast, (b) spatial accuracy of the images, (c) image uniformity, and (d) computed tomography (CT)-to-electron density conversion relationship were investigated. Using the image-guided tools, the alignment of the radiographic imaging system was assessed to be within a millimeter. The low-contrast resolution was found to be a 6-mm diameter hole at 1% contrast level and high-contrast resolution at 9 line pairs per centimeter. The spatial accuracy (50 mm {+-} 1%), slice thickness (2.5 mm and 5.0 mm {+-} 5%), and image uniformity ({+-} 20 HU) were found to be within the manufacturer's specifications. The CT-to-electron density relationship was also determined. By using well-designed procedures and phantom, the number of parameter checks for quality assurance of the IGRT system can be carried out in a relatively short time.

  8. Facile synthesis of carbon nanofibers-bridged porous carbon nanosheets for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Jiang, Yuting; Yan, Jun; Wu, Xiaoliang; Shan, Dandan; Zhou, Qihang; Jiang, Lili; Yang, Deren; Fan, Zhuangjun

    2016-03-01

    A facile and one-step method is demonstrated to prepare carbon nanofibers (CNFs)-bridged porous carbon nanosheets (PCNs) through carbonization of the mixture of bacterial cellulose and potassium citrate. The CNFs bridge PCNs to form integrated porous carbon architecture with high specific surface area of 1037 m2 g-1, much higher than those of pure PCNs (381 m2 g-1) and CNFs (510 m2 g-1). As a consequence, the PCN/CNF composite displays high specific capacitance of 261 F g-1, excellent rate capability and outstanding cycling stability (97.6% of capacitance retention after 10000 cycles). Moreover, the assembled symmetric supercapacitor with PCN/CNF electrodes delivers an ultrahigh energy density of 20.4 Wh kg-1 and outstanding cycling life (94.8% capacitance retention after 10000 cycles) in an aqueous electrolyte.

  9. The role of carbon in ion beam nano-patterning of silicon

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, S.; Karmakar, P.; Naik, V.; Sinha, A. K.; Chakrabarti, A.

    2013-10-01

    We report a comparative study of nano-pattern formations on a carbon film and a smooth Si(100) surface following inert and chemically active ion bombardment. For the case of carbon film, patterns could be formed both by inert (Ar+) and self (C+) ion bombardment with the former producing ripples at relatively lower fluence. In contrast, bombardment by inert Ar+ failed to form the nano patterns on Si surface, while bombardment by the same energy C+ generated the ripples. Thus, impurity induced chemical effect seems to be crucial rather than the Bradley-Harper or Carter-Vishnyakov effects for destabilizing the surface for ripple formation.

  10. Enhancing the performance of fluorescence emission difference microscopy using beam modulation

    NASA Astrophysics Data System (ADS)

    Li, Shuai; Kuang, Cuifang; Hao, Xiang; Wang, Yifan; Ge, Jianhong; Liu, Xu

    2013-12-01

    Fluorescence emission difference microscopy (FED) has been proved to be an effective method to break the diffraction barrier which had restricted the spatial resolution of optical microscopy in the far-field for a long time. In this paper, we theoretically demonstrate that the attainable resolution of FED can be further enhanced by using beam modulation. By applying beam shape modulating, polarization state modulating, phase encoding and beam blocking to the illumination beams in the process of FED imaging, we optimize the size of the corresponding PSFs and thus improve the resolving ability of FED. The simulation tests demonstrate that in the optimal case after beam modulation, the resolution of FED can be enhanced by a factor of 26% compared with a conventional one.

  11. Performance of piezoresistive carbon sensors in contact with porous materials

    SciTech Connect

    Gourdin, W.H.; Weinland, S.L.

    1986-07-01

    Piezoresistive carbon sensors were used to determine the stress-time history in unsintered powders during shock-wave compaction in a gas gun. Powders of both spherical and irregular shape were examined, including steel, aluminum--silicon alloy, copper, tungsten, and aluminum nitride. A calibration relationship was established between direct sensor response and stress levels determined by impedance matching; it corrects apparent systematic errors in the manufacturer's calibration for stresses in excess of about 2.0 GPa.

  12. Improved measurement of neutral current coherent $\\pi^0$ production on carbon in a few-GeV neutrino beam

    SciTech Connect

    Kurimoto, Y.; Alcaraz-Aunion, J.L.; Brice, S.J.; Bugel, L.; Catala-Perez, J.; Cheng, G.; Conrad, J.M.; Djurcic, Z.; Dore, U.; Finley, D.A.; Franke, A.J.; /Columbia U. /INFN, Rome

    2010-05-01

    The SciBooNE Collaboration reports a measurement of neutral current coherent neutral pion production on carbon by a muon neutrino beam with average energy 0.8 GeV. The separation of coherent from inclusive neutral pion production has been improved by detecting recoil protons from resonant neutral pion production. We measure the ratio of the neutral current coherent neutral pion production to total charged current cross sections to be (1.16 +/- 0.24) x 10-2. The ratio of charged current coherent pion to neutral current coherent pion production is calculated to be 0.14+0.30 -0.28, using our published charged current coherent pion measurement.

  13. Improved measurement of neutral current coherent π0 production on carbon in a few-GeV neutrino beam

    NASA Astrophysics Data System (ADS)

    Kurimoto, Y.; Alcaraz-Aunion, J. L.; Brice, S. J.; Bugel, L.; Catala-Perez, J.; Cheng, G.; Conrad, J. M.; Djurcic, Z.; Dore, U.; Finley, D. A.; Franke, A. J.; Giganti, C.; Gomez-Cadenas, J. J.; Guzowski, P.; Hanson, A.; Hayato, Y.; Hiraide, K.; Jover-Manas, G.; Karagiorgi, G.; Katori, T.; Kobayashi, Y. K.; Kobilarcik, T.; Kubo, H.; Louis, W. C.; Loverre, P. F.; Ludovici, L.; Mahn, K. B. M.; Mariani, C.; Masuike, S.; Matsuoka, K.; McGary, V. T.; Metcalf, W.; Mills, G. B.; Mitsuka, G.; Miyachi, Y.; Mizugashira, S.; Moore, C. D.; Nakajima, Y.; Nakaya, T.; Napora, R.; Nienaber, P.; Orme, D.; Otani, M.; Russell, A. D.; Sanchez, F.; Shaevitz, M. H.; Shibata, T.-A.; Sorel, M.; Stefanski, R. J.; Takei, H.; Tanaka, H.-K.; Tanaka, M.; Tayloe, R.; Taylor, I. J.; Tesarek, R. J.; Uchida, Y.; van de Water, R.; Walding, J. J.; Wascko, M. O.; White, H. B.; Wilking, M. J.; Yokoyama, M.; Zeller, G. P.; Zimmerman, E. D.

    2010-06-01

    The SciBooNE Collaboration reports a measurement of neutral current coherent π0 production on carbon by a muon neutrino beam with average energy 0.8 GeV. The separation of coherent from inclusive π0 production has been improved by detecting recoil protons from resonant π0 production. We measure the ratio of the neutral current coherent π0 production to total charged current cross sections to be (1.16±0.24)×10-2. The ratio of charged current coherent π+ to neutral current coherent π0 production is calculated to be 0.14-0.28+0.30, using our published charged current coherent pion measurement.

  14. Mechanical performance of pyrolytic carbon in prosthetic heart valve applications.

    PubMed

    Cao, H

    1996-06-01

    An experimental procedure has been developed for rigorous characterization of the fracture resistance and fatigue crack extension in pyrolytic carbon for prosthetic heart valve application. Experiments were conducted under sustained and cyclic loading in a simulated biological environment using Carbomedics Pyrolite carbon. While the material was shown to have modest fracture toughness, it exhibited excellent resistance to subcritical crack growth. The crack growth kinetics in pyrolytic carbon were formulated using a phenomenological description. A fatigue threshold was observed below which the crack growth rate diminishes. A damage tolerance concept based on fracture mechanics was used to develop an engineering design approach for mechanical heart valve prostheses. In particular, a new quantity, referred to as the safe-life index, was introduced to assess the design adequacy against subcritical crack growth in brittle materials. In addition, a weakest-link statistical description of the fracture strength is provided and used in the design of component proof-tests. It is shown that the structural reliability of mechanical heart valves can be assured by combining effective flaw detection and manufacturing quality control with adequate damage tolerance design.

  15. High-performance soft-tissue imaging in extremity cone-beam CT

    NASA Astrophysics Data System (ADS)

    Zbijewski, W.; Sisniega, A.; Stayman, J. W.; Muhit, A.; Thawait, G.; Packard, N.; Senn, R.; Yang, D.; Yorkston, J.; Carrino, J. A.; Siewerdsen, J. H.

    2014-03-01

    Purpose: Clinical performance studies of an extremity cone-beam CT (CBCT) system indicate excellent bone visualization, but point to the need for improvement of soft-tissue image quality. To this end, a rapid Monte Carlo (MC) scatter correction is proposed, and Penalized Likelihood (PL) reconstruction is evaluated for noise management. Methods: The accelerated MC scatter correction involved fast MC simulation with low number of photons implemented on a GPU (107 photons/sec), followed by Gaussian kernel smoothing in the detector plane and across projection angles. PL reconstructions were investigated for reduction of imaging dose for projections acquired at ~2 mGy. Results: The rapid scatter estimation yielded root-mean-squared-errors of scatter projections of ~15% of peak scatter intensity for 5ṡ106 photons/projection (runtime ~0.5 sec/projection) and 25% improvement in fat-muscle contrast in reconstructions of a cadaveric knee. PL reconstruction largely restored soft-tissue visualization at 2 mGy dose to that of 10 mGy FBP image. Conclusion: The combination of rapid (5-10 minutes/scan) MC-based, patient-specific scatter correction and PL reconstruction offers an important means to overcome the current limitations of extremity CBCT in soft-tissue imaging.

  16. Nitrogen Doping of Single-Walled Carbon Nanotube by Using Mass-Separated Low-Energy Ion Beams

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kazuhiro; Kamimura, Takafumi; Matsumoto, Kazuhiko

    2005-04-01

    Mass-separated nitrogen ions with the mass number of 14 were irradiated to the single-walled carbon nanotubes (SWCNTs) under an ultra high-vacuum pressure of 10-7 Pa for the purpose of achieving nitrogen doping in nanotubes. The incident angle of the ion beam was normal to the target nanotube, and the ion beam energy was 30 eV, which was close to the displacement energy of graphite. The dependence of the structure of SWCNTs on the ion dose was investigated. The ion dose ranged from 2.8× 1014 to 2.2× 1016 ions/cm2. The nitrogen ions are incorporated into graphite sheets of SWCNTs after irradiation at 2.8× 1014 ions/cm2. The graphite structure is distorted and many defects are induced in the nanotube by the nitrogen incorporation. The structure is changed to amorphous after irradiation at 2.2× 1016 ions/cm2. The nitrogen ions with the ion energy of 25 eV are irradiated to the field effect transistor device with the nanotube channel. The n-type characteristic appears upon ion irradiation, and the device exhibits ambipolar behavior.

  17. SU-E-T-601: Patient Specific QA Check for Radiotherapy with Carbon Beam at SAGA HIMAT

    SciTech Connect

    Himukai, T; Tsunashima, Y; Kanazawa, M; Mizota, M; Shioyama, Y; Endo, M

    2015-06-15

    Purpose: To verify a patient specific QA for a prescribed dose per monitor unit (MU) and range check of carbon ion radiotherapy with a beam wobbling method at SAGA HIMAT. Methods: The dose distribution in a water phantom was recalculated with a treatment plan made by XiO-N (Mitsubishi Electric Corporation, Tokyo). The depth dose distributions at central axis were compared with measurements using pinpoint ionization chamber (PTW31014). Measured data were analyzed for dose and distance difference with criteria of 3% and 2mm. To check for the MU and range, analysis data were used at center and distal end of a spread out bragg peak (SOBP) depth, respectively. Results: Treatment plan of 1400 beams in 500 patients were used for analysis. The pass rate of the MU and range was about 98% and 74%, respectively. The rate of both was 73%. The plan data passed only the MU check were verified depth dose profile. The data passed only the range and failed of both were compared depth dose distributions at off axis. If it was failed, we discussed with physicians. Conclusion: Most of patient specific QA check for a prescribed MU and range check at SAGA HIMAT were passed.

  18. Fabrication of Glassy Carbon Molds Using Hydrogen Silsequioxane Patterned by Electron Beam Lithography as O2 Dry Etching Mask

    NASA Astrophysics Data System (ADS)

    Yasui, Manabu; Sugiyama, Yoshinari; Takahashi, Masaharu; Kaneko, Satoru; Uegaki, Jun-ichi; Hirabayashi, Yasuo; Sugimoto, Koh-ichi; Maeda, Ryutaro

    2008-06-01

    Glass is a good candidate material for optical devices because of its enhanced optical properties, the technique of die machining has not been established for the hot embossing of glass. In this study, we used the glassy carbon (GC) mold for the hot embossing of glass. An inductively coupled plasma reactive ion etching (ICP-RIE) using oxygen plasma was employed for the submicron structuring of the GC mold. Hydrogen silsesquioxane (HSQ) is a negative-type electron beam (EB) resist used to be resistant to oxygen plasma. HSQ patterns drawn by electron beam lithography (EBL) were used as the O2 dry etching mask. The etching selectivity between HSQ and GC was 35. The average of the extent of side etching was 40 nm at a depth of 300 nm. The side etching functioning as the draft angle was caused mainly by oxygen radicals, because HSQ patterns remained even after GC patterns were side-etched. We confirmed that the GC mold fabricated by O2 dry etching can be used for glass hot embossing. Since the mold lubricant was not rubbed on the mold surface, GC is the appropriate mold material for Pyrex glass.

  19. Fabrication and characterization of tunnel barriers in a multi-walled carbon nanotube formed by argon atom beam irradiation

    SciTech Connect

    Tomizawa, H.; Yamaguchi, T.; Akita, S.; Ishibashi, K.

    2015-07-28

    We have evaluated tunnel barriers formed in multi-walled carbon nanotubes (MWNTs) by an Ar atom beam irradiation method and applied the technique to fabricate coupled double quantum dots. The two-terminal resistance of the individual MWNTs was increased owing to local damage caused by the Ar beam irradiation. The temperature dependence of the current through a single barrier suggested two different contributions to its Arrhenius plot, i.e., formed by direct tunneling through the barrier and by thermal activation over the barrier. The height of the formed barriers was estimated. The fabrication technique was used to produce coupled double quantum dots with serially formed triple barriers on a MWNT. The current measured at 1.5 K as a function of two side-gate voltages resulted in a honeycomb-like charge stability diagram, which confirmed the formation of the double dots. The characteristic parameters of the double quantum dots were calculated, and the feasibility of the technique is discussed.

  20. Poster — Thur Eve — 19: Performance assessment of a 160-leaf beam collimation system

    SciTech Connect

    Ali, E. S. M.; La Russa, D. J.; Vandervoort, E.

    2014-08-15

    In this study, the performance of the new beam collimation system with 160 leaves, each with a 5 mm leaf width projected at isocenter, is evaluated in terms of positional accuracy and plan/delivery quality. Positional accuracy was evaluated using a set of static and dynamic MLC/jaw delivery patterns at different gantry angles, dose rates, and MLC/jaw speeds. The impact on IMRT plan quality was assessed by comparing against a previous generation collimation system using the same optimization parameters, while delivery quality was quantified using a combination of patient-specific QA measurements with ion chambers, film, and a bi-planar diode array. Positional accuracy for four separate units was comparable. The field size accuracy, junction width, and total displacement over 16 cm leaf travel are 0.3 ± 0.2 mm, 0.4 ± 0.3 mm, and 0.5 ± 0.2 mm, respectively. The typical leaf minor offset is 0.05 ± 0.04 mm, and MLC hysteresis effects are 0.2 ± 0.1 mm over 16 cm travel. The dynamic output is linear with MU and MLC/jaw speed, and is within 0.7 ± 0.3 % of the planning system value. Plan quality is significantly improved both in terms of target coverage and OAR sparing due, in part, to the larger allowable MLC and jaw speeds. γ-index pass rates for the patient-specific QA measurements exceeded 97% using criteria of 2%/2 mm. In conclusion, the performance of the Agility system is consistent among four separate installations, and is superior to its previous generations of collimation systems.

  1. Investigation of beam steering performances in rotation Risley-prism scanner.

    PubMed

    Li, Anhu; Sun, Wansong; Yi, Wanli; Zuo, Qiyou

    2016-06-13

    Rotation Risley-prism scanner appears to be the most promising solution to high-accuracy beam scanning and target tracking. In the paper, some important issues crucial to the function implementation are thoroughly investigated. First the forming law of scan blind zone relative to double-prism structural parameters is explored by a quantitative analysis method. Then the nonlinear relationship between the rotation speeds of double prisms and the change rate of beam deviation angle is presented, and the beam scan singularity is indicated as an essential factor that confines the beam scan region. Finally, the high-accuracy radial scan theory is verified to illustrate the important application owing to the high reduction ratio from the rotation angles of double prisms to the deviation angles of the emergent beam. The research not only reveals the inner mechanisms of the Risley-prism beam scanning in principle, but also provide a foundation for the nonlinear control of various beam scan modes. PMID:27410303

  2. Seismic performance of RC shear wall structure with novel shape memory alloy dampers in coupling beams

    NASA Astrophysics Data System (ADS)

    Mao, Chenxi; Dong, Jinzhi; Li, Hui; Ou, Jinping

    2012-04-01

    Shear wall system is widely adopted in high rise buildings because of its high lateral stiffness in resisting earthquakes. According to the concept of ductility seismic design, coupling beams in shear wall structure are required to yield prior to the damage of wall limb. However, damage in coupling beams results in repair cost post earthquake and even in some cases it is difficult to repair the coupling beams if the damage is severe. In order to solve this problem, a novel passive SMA damper was proposed in this study. The coupling beams connecting wall limbs are split in the middle, and the dampers are installed between the ends of the two cantilevers. Then the relative flexural deformation of the wall limbs is transferred to the ends of coupling beams and then to the SMA dampers. After earthquakes the deformation of the dampers can recover automatically because of the pseudoelasticity of austenite SMA material. In order to verify the validity of the proposed dampers, seismic responses of a 12-story coupled shear wall with such passive SMA dampers in coupling beams was investigated. The additional stiffness and yielding deformation of the dampers and their ratios to the lateral stiffness and yielding displacements of the wall limbs are key design parameters and were addressed. Analytical results indicate that the displacement responses of the shear wall structure with such dampers are reduced remarkably. The deformation of the structure is concentrated in the dampers and the damage of coupling beams is reduced.

  3. Reflective electron-beam lithography performance for the 10nm logic node

    NASA Astrophysics Data System (ADS)

    Freed, Regina; Gubiotti, Thomas; Sun, Jeff; Cheung, Anthony; Yang, Jason; McCord, Mark; Petric, Paul; Carroll, Allen; Ummethala, Upendra; Hale, Layton; Hench, John; Kojima, Shinichi; Mieher, Walter; Bevis, Chris F.

    2012-11-01

    Maskless electron beam lithography has the potential to extend semiconductor manufacturing to the sub-10 nm technology node. KLA-Tencor is currently developing Reflective Electron Beam Lithography (REBL) for high-volume 10 nm logic (16 nm HP). This paper reviews progress in the development of the REBL system towards its goal of 100 wph throughput for High Volume Lithography (HVL) at the 2X and 1X nm nodes. In this paper we introduce the Digital Pattern Generator (DPG) with integrated CMOS and MEMs lenslets that was manufactured at TSMC and IMEC. For REBL, the DPG is integrated to KLA-Tencor pattern generating software that can be programmed to produce complex, gray-scaled lithography patterns. Additionally, we show printing results for a range of interesting lithography patterns using Time Domain Imaging (TDI). Previously, KLA-Tencor reported on the development of a Reflective Electron Beam Lithography (REBL) tool for maskless lithography at and below the 22 nm technology node1. Since that time, the REBL team and its partners (TSMC, IMEC) have made good progress towards developing the REBL system and Digital Pattern Generator (DPG) for direct write lithography. Traditionally, e-beam direct write lithography has been too slow for most lithography applications. Ebeam direct write lithography has been used for mask writing rather than wafer processing since the maximum blur requirements limit column beam current - which drives e-beam throughput. To print small features and a fine pitch with an e-beam tool requires a sacrifice in processing time unless one significantly increases the total number of beams on a single writing tool. Because of the continued uncertainty with regards to the optical lithography roadmap beyond the 22 nm technology node, the semiconductor equipment industry is in the process of designing and testing e-beam lithography tools with the potential for HVL.

  4. Fibrous nanocomposites of carbon nanotubes and graphene-oxide with synergetic mechanical and actuative performance.

    PubMed

    Wang, Ranran; Sun, Jing; Gao, Lian; Xu, Chaohe; Zhang, Jing

    2011-08-14

    Fibrous nanocomposites of carbon nanotubes, graphene-oxide or graphene were prepared by a simple coagulation spinning technique exhibiting synergetic enhancement of mechanical strength, electronic conductivity and electrical actuation performance. PMID:21725531

  5. PERFORMANCE OF ACTIVATED SLUDGE-POWDERED ACTIVATED CARBON-WET AIR REGENERATION SYSTEMS

    EPA Science Inventory

    The investigation summarized in the report was undertaken to evaluate the performance of powdered activated carbon (PAC) technology used in conjunction with wet air regeneration (WAR) at municipal wastewater treatment plants. Excessive ash concentrations accumulated in the mixed ...

  6. High-performance beam steering using electrowetting-driven liquid prism fabricated by a simple dip-coating method

    NASA Astrophysics Data System (ADS)

    Enrico Clement, Carlos; Park, Sung-Yong

    2016-05-01

    A high degree of beam steering is demonstrated using an electrowetting-driven liquid prism. While prism devices have typically relied on complex and expensive laboratory setups, such as high-vacuum facilities for fabrication of dielectric layers, this work utilizes a simple dip-coating method to provide an ion gel layer as a dielectric, offering 2 or 3 orders higher specific capacitance (c ≈ 10 μF/cm2) than that of conventional dielectrics. Analytical studies present the effects of liquid selection and arrangement on overall prism performance. For experimental demonstrations of high-performance beam steering, we not only selected two immiscible liquids of water and 1-bromonaphthalene (1-BN) oil which provide the large refractive index difference (nwater = 1.33 and n1-BN = 1.65 at λ = 532 nm) between them, but also utilized a double-stacked prism configuration which increases the number of interfaces for incoming light to be steered. At a prism apex angle of φ = 27°, we were able to achieve significantly large beam steering of up to β = 19.06°, which is the highest beam steering performance ever demonstrated using electrowetting technology.

  7. Design and characterization of a multi-beam micro-CT scanner based on carbon nanotube field emission x-ray technology

    NASA Astrophysics Data System (ADS)

    Peng, Rui

    In this dissertation, I will present the results for my Ph.D. research for the past five years. My project mainly focuses on advanced imaging applications with a multi-beam x-ray source array based on carbon nanotube field emission technology. In the past few years, research in carbon nanotubes gradually changed from the raw material science to its application. Field emission x-ray application is one of the hottest research areas for carbon nanotube. Compared to traditional thermionic x-ray sources, the carbon nanotube field emission x-ray source has some natural advantages over traditional thermionic x-ray sources such as instantaneous x-ray generation, programmability and miniaturization. For the past few years, the research and development of carbon nanotube field emission x-ray has shifted from single x-ray beam applications to spatially distributed multi-beam x-ray sources. Previously in Zhou group, we have already built a gated micro-CT system with single beam micro-focus x-ray tube for higher spatial and temporal resolution as required in live animal imaging and a multi-beam tomosynthesis system targeting for faster and more stable breast imaging. Now my project mainly focused on the design, characterization and optimization of a multi-beam micro-CT imaging system. With the increase of gantry rotation speed approaching the mechanical limit, it is getting more and more difficult to further speed up the CT scanning. My new system promises a potential solution for the problem, and it serves as a great test platform for truly stationary micro-CT geometry. The potential capabilities it showed during the characterization and imaging measurements was promising. The dissertation is composed of five chapters. In Chapter 1, I will generally review the physics principles of x-ray generation and interaction with matter. Then the discovery of carbon nanotube and its great potential to serve as an excellent field emission electron source will be introduced in the second

  8. Imaging Carbon Nanotubes in High Performance Polymer Composites via Magnetic Force Microscope

    NASA Technical Reports Server (NTRS)

    Lillehei, Peter T.; Park, Cheol; Rouse, Jason H.; Siochi, Emilie J.; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    Application of carbon nanotubes as reinforcement in structural composites is dependent on the efficient dispersion of the nanotubes in a high performance polymer matrix. The characterization of such dispersion is limited by the lack of available tools to visualize the quality of the matrix/carbon nanotube interaction. The work reported herein demonstrates the use of magnetic force microscopy (MFM) as a promising technique for characterizing the dispersion of nanotubes in a high performance polymer matrix.

  9. The role of carbon in ion beam nano-patterning of silicon

    SciTech Connect

    Bhattacharjee, S.

    2013-10-28

    We report a comparative study of nano-pattern formations on a carbon film and a smooth Si(100) surface following inert and chemically active ion bombardment. For the case of carbon film, patterns could be formed both by inert (Ar{sup +}) and self (C{sup +}) ion bombardment with the former producing ripples at relatively lower fluence. In contrast, bombardment by inert Ar{sup +} failed to form the nano patterns on Si surface, while bombardment by the same energy C{sup +} generated the ripples. Thus, impurity induced chemical effect seems to be crucial rather than the Bradley-Harper or Carter-Vishnyakov effects for destabilizing the surface for ripple formation.

  10. Performance evaluations of oxidation-resistant carbon-carbon composites in simulated hypersonic vehicle environments

    NASA Technical Reports Server (NTRS)

    Barrett, D. M.; Maahs, H. G.; Ohlhorst, C. W.; Vaughn, W. L.; Martin, R. H.

    1989-01-01

    An evaluation is made of the oxidation-protection requirements of carbon-carbon composite (CCC) structural components in a hypersonic vehicle aerothermodynamic environment, where maximum test temperatures in air are of the order of 2800 F, and pressures range from 0.03 to 1.0 atm. The specimens were exposed to high humidity between tests. Attention was given to the effects of coating composition and thickness, and of substrate architecture and surface preparation, on the oxidation resistance of CCCs. Both surface preparation and coating chemistry have a profound effect on coating adherence and longevity.

  11. Effect of carbon coating on scuffing performance in diesel fuels

    SciTech Connect

    Ajayi, O. O.; Alzoubi, M. F.; Erdemir, A.; Fenske, G. R.

    2000-06-29

    Low-sulfur and low-aromatic diesel fuels are being introduced in order to reduce various types of emissions in diesel engines to levels in compliance with current and impending US federal regulations. The low lubricity of these fuels, however, poses major reliability and durability problems for fuel injection components that depend on diesel fuel for their lubrication. In the present study, the authors evaluated the scuff resistance of surfaces in regular diesel fuel containing 500 ppm sulfur and in Fischer-Tropsch synthetic diesel fuel containing no sulfur or aromatics. Tests were conducted with the high frequency reciprocating test rig (HFRR) using 52100 steel balls and H-13 tool-steel flats with and without Argonne's special carbon coatings. Test results showed that the sulfur-containing fuels provide about 20% higher scuffing resistance than does fuel without sulfur. Use of the carbon coating on the flat increased scuffing resistance in both regular and synthetic fuels by about ten times, as measured by the contact severity index at scuffing. Scuffing failure in tests conducted with coated surfaces did not occur until the coating had been removed by the two distinct mechanisms of spalling and wear.

  12. Understanding of carbonate fuel cell resistance issues for performance improvement

    SciTech Connect

    Yuh, C.Y.; Farooque, M.; Johnsen, R.

    1992-09-01

    The overall objective of the current Task 6 under Contract AC21-90MC27168 is to develop understanding as well as quantification of cell ohmic resistance in carbonate fuel cell. The important resistance-contributing interfaces and elements are being investigated in high-temperature out-of-cell resistance experiments, using an AC-impedance technique. Ohmic resistance loss in a state-of-the-art carbonate fuel cell contributes about 65 mV loss at BOL (beginning-of-life). It may increase to about as much as 145 mV after 40,000 hours. Its reduction will offer further improvement in fuel cell power plant efficiency. The important resistance contributing elements/interfaces are illustrated in Figure 1. The majority of the ohmic loss attributed to electrolyte matrix (ionic) and cathode-side hardware (electronic). The ohmic loss due to anode-side hardware can generally be neglected because the anode-side hardware is surface protected resulting in very little surface oxide formation. The ohmic resistance of the electrodes is also negligible. The matrix ionic resistance is influenced by many factors: electrolyte conductivity, matrix porosity, tortuosity, electrolyte fill level and matrix thickness. At present, matrix contributes to > 300 m{Omega}cm{sup 2} (>70% of the total cell ohmic resistance) and is the major resistance contributor.

  13. Understanding of carbonate fuel cell resistance issues for performance improvement

    SciTech Connect

    Yuh, C.Y.; Farooque, M.; Johnsen, R.

    1992-01-01

    The overall objective of the current Task 6 under Contract AC21-90MC27168 is to develop understanding as well as quantification of cell ohmic resistance in carbonate fuel cell. The important resistance-contributing interfaces and elements are being investigated in high-temperature out-of-cell resistance experiments, using an AC-impedance technique. Ohmic resistance loss in a state-of-the-art carbonate fuel cell contributes about 65 mV loss at BOL (beginning-of-life). It may increase to about as much as 145 mV after 40,000 hours. Its reduction will offer further improvement in fuel cell power plant efficiency. The important resistance contributing elements/interfaces are illustrated in Figure 1. The majority of the ohmic loss attributed to electrolyte matrix (ionic) and cathode-side hardware (electronic). The ohmic loss due to anode-side hardware can generally be neglected because the anode-side hardware is surface protected resulting in very little surface oxide formation. The ohmic resistance of the electrodes is also negligible. The matrix ionic resistance is influenced by many factors: electrolyte conductivity, matrix porosity, tortuosity, electrolyte fill level and matrix thickness. At present, matrix contributes to > 300 m{Omega}cm{sup 2} (>70% of the total cell ohmic resistance) and is the major resistance contributor.

  14. Iris clipping of a diode laser beam when performing retinal photocoagulation.

    PubMed Central

    Woon, W. H.; ffytche, T. J.; Hamilton, A. M.; Marshall, J.

    1991-01-01

    The Microlase infrared diode laser has recently become available for retinal photocoagulation. It uses a laser beam with a large convergence angle (23 degrees). This gives rise to a laser beam with a relatively large cross section at the subject's pupil. In this study the pupillary area required to view the fundus at the slit-lamp with a 90-dioptre lens is determined. It is found that the pupillary area required to view the fundus is smaller than the cross section of the Microlase laser beam at the pupil. Thus iris clipping of the laser beam can occur even though the surgeon has a clear and bright view of the fundus. Care should be taken to use the Microlase only in the presence of a widely dilated pupil. Images PMID:1854689

  15. Pyrolytic carbon-coated silicon/carbon nanofiber composite anodes for high-performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Chen, Yanli; Hu, Yi; Shao, Jianzhong; Shen, Zhen; Chen, Renzhong; Zhang, Xiangwu; He, Xia; Song, Yuanze; Xing, Xiuli

    2015-12-01

    Pyrolytic carbon-coated Si/C nanofibers (Si/C-CNFs) composites have been prepared through the sucrose coating and secondary thermal treatment of Si/CNFs composites produced via electrospinning and carbonization. This results in a structure in which Si nanoparticles are distributed along the fibers, with the fiber surface being coated with an amorphous carbon layer through pyrolysis of the sucrose. This carbon coating not only limits the volume expansion of the exposed Si nanoparticles, preventing their direct contact with the electrolyte, but also creates a connection between the fibers that is beneficial to Li+ ion transport, structural integrity, and electrochemical conductivity. Consequently, the Si/C-CNFs composite exhibits a more stable cycle performance, better rate performance, and higher conductivity than Si/CNFs alone. The optimal level of performance was attained with a 20:200 mass ratio of sucrose to deionized water, with a high retained capacity of 1215.2 mAh g-1 after 50 cycles, thus indicating that it is a suitable anode material for Li-ion batteries.

  16. Characterization and electrochemical performance of graphene-containing carbon aerogel for supercapacitor.

    PubMed

    Lee, Yoon Jae; Park, Hai Woong; Hong, Ung Gi; Song, In Kyu

    2013-12-01

    Graphene-containing carbon aerogel was prepared by a polycondensation of resorcinol with formaldehyde using chemically exfoliated graphene oxide in ambient conditions, and its electrochemical performance as an electrode for supercapacitor was examined. The effect of pH in the preparation of RFGO (resorcinol-formaldehyde and graphene oxide) solution on the physical and electrochemical properties of graphene-containing carbon aerogel was investigated. For comparison, graphene-free carbon aerogel was also prepared. Among the samples, graphene-containing carbon aerogel prepared at pH 6.5 showed the highest BET surface area (733 m2/g) and the largest pore volume (1.39 cm3/g) with well-developed porous structure. Electrochemical properties of graphene-containing carbon aerogel and graphene-free carbon aerogel electrodes were measured by cyclic voltammetry at a scan rate of 10 mV/sec and by charge/discharge test at constant current of 1 A/g in 6 M KOH electrolyte. From cyclic voltammetry measurements, it was found that graphene-containing carbon aerogel prepared at pH 6.5 showed higher specific capacitance than graphene-free carbon aerogel (63 F/g vs. 54 F/g). Specific capacitance calculated by charge/discharge test also revealed that graphene-containing carbon aerogel prepared at pH 6.5 showed higher specific capacitance than graphene-free carbon aerogel (85 F/g vs. 79 F/g). Thus, electrochemical performance of graphene-containing carbon aerogel prepared at pH 6.5 could be enhanced by adding graphene into carbon aerogel.

  17. Proton exchange membrane fuel cell reversible performance loss induced by carbon monoxide produced during operation

    NASA Astrophysics Data System (ADS)

    Decoopman, B.; Vincent, R.; Rosini, S.; Paganelli, G.; Thivel, P.-X.

    2016-08-01

    Cyclic voltammetry measurements at the anode have been carried out and reveal the presence of carbon monoxide in steady-state operation, with pure hydrogen. Experiments have been performed both in single cell and in stack to find out its origin. The contamination of the anode catalyst is partly due the reverse-water gas shift (RWGS) with carbon dioxide from the cathode. However, this study shows a temperature-activated and time-related corrosion mechanism which appears under humidified hydrogen. Due to this degradation mechanism, a reversible 25 mV-loss of performances is observed and can be recovered by oxidizing carbon monoxide on the anode.

  18. Proton exchange membrane fuel cell reversible performance loss induced by carbon monoxide produced during operation

    NASA Astrophysics Data System (ADS)

    Decoopman, B.; Vincent, R.; Rosini, S.; Paganelli, G.; Thivel, P.-X.

    2016-08-01

    Cyclic voltammetry measurements at the anode have been carried out and reveal the presence of carbon monoxide in steady-state operation, with pure hydrogen. Experiments have been performed both in single cell and in stack to find out its origin. The contamination of the anode catalyst is partly due the reverse-water gas shift (RWGS) with carbon dioxide from the cathode. However, this study shows a temperature-activated and time-related corrosion mechanism which appears under humidified hydrogen. Due to this degradation mechanism, a reversible 25 mV-loss of performances is observed and can be recovered by oxidizing carbon monoxide on the anode.

  19. A dual cone-beam CT system for image guided radiotherapy: Initial performance characterization

    SciTech Connect

    Li Hao; Bowsher, James; Yin Fangfang; Giles, William

    2013-02-15

    Purpose: The purpose of this study is to evaluate the performance of a recently developed benchtop dual cone-beam computed tomography (CBCT) system with two orthogonally placed tube/detector sets. Methods: The benchtop dual CBCT system consists of two orthogonally placed 40 Multiplication-Sign 30 cm flat-panel detectors and two conventional x-ray tubes with two individual high-voltage generators sharing the same rotational axis. The x-ray source to detector distance is 150 cm and x-ray source to rotational axis distance is 100 cm for both subsystems. The objects are scanned through 200 Degree-Sign of rotation. The dual CBCT system utilized 110 Degree-Sign of projection data from one detector and 90 Degree-Sign from the other while the two individual single CBCTs utilized 200 Degree-Sign data from each detector. The system performance was characterized in terms of uniformity, contrast, spatial resolution, noise power spectrum, and CT number linearity. The uniformities, within the axial slice and along the longitudinal direction, and noise power spectrum were assessed by scanning a water bucket; the contrast and CT number linearity were measured using the Catphan phantom; and the spatial resolution was evaluated using a tungsten wire phantom. A skull phantom and a ham were also scanned to provide qualitative evaluation of high- and low-contrast resolution. Each measurement was compared between dual and single CBCT systems. Results: Compared to single CBCT, the dual CBCT presented: (1) a decrease in uniformity by 1.9% in axial view and 1.1% in the longitudinal view, as averaged for four energies (80, 100, 125, and 150 kVp); (2) comparable or slightly better contrast (0{approx}25 HU) for low-contrast objects and comparable contrast for high-contrast objects; (3) comparable spatial resolution; (4) comparable CT number linearity with R{sup 2}{>=} 0.99 for all four tested energies; (5) lower noise power spectrum in magnitude. Dual CBCT images of the skull phantom and the

  20. The effect of carbon nanofillers on the performance of electromechanical polyaniline-based composite actuators

    NASA Astrophysics Data System (ADS)

    García-Gallegos, J. C.; Martín-Gullón, I.; Conesa, J. A.; Vega-Cantú, Y. I.; Rodríguez-Macías, F. J.

    2016-01-01

    Different types of crystalline carbon nanomaterials were used to reinforce polyaniline for use in electromechanical bilayer bending actuators. The objective is to analyze how the different graphitic structures of the nanocarbons affect and improve the in situ polymerized polyaniline composites and their subsequent actuator behavior. The nanocarbons investigated were multiwalled carbon nanotubes, nitrogen-doped carbon nanotubes, helical-ribbon carbon nanofibers and graphene oxide, each one presenting different shape and structural characteristics. Films of nanocarbon-PAni composite were tested in a liquid electrolyte cell system. Experimental design was used to select the type of nanocarbon filler and composite loadings, and yielded a good balance of electromechanical properties. Raman spectroscopy suggests good interaction between PAni and the nanocarbon fillers. Electron microscopy showed that graphene oxide dispersed the best, followed by multiwall carbon nanotubes, while nitrogen-doped nanotube composites showed dispersion problems and thus poor performance. Multiwall carbon nanotube composite actuators showed the best performance based on the combination of bending angle, bending velocity and maximum working cycles, while graphene oxide attained similarly good performance due to its best dispersion. This parallel testing of a broad set of nanocarbon fillers on PAni-composite actuators is unprecedented to the best of our knowledge and shows that the type and properties of the carbon nanomaterial are critical to the performance of electromechanical devices with other conditions remaining equal.

  1. The effect of carbon nanofillers on the performance of electromechanical polyaniline-based composite actuators.

    PubMed

    García-Gallegos, J C; Martín-Gullón, I; Conesa, J A; Vega-Cantú, Y I; Rodríguez-Macías, F J

    2016-01-01

    Different types of crystalline carbon nanomaterials were used to reinforce polyaniline for use in electromechanical bilayer bending actuators. The objective is to analyze how the different graphitic structures of the nanocarbons affect and improve the in situ polymerized polyaniline composites and their subsequent actuator behavior. The nanocarbons investigated were multiwalled carbon nanotubes, nitrogen-doped carbon nanotubes, helical-ribbon carbon nanofibers and graphene oxide, each one presenting different shape and structural characteristics. Films of nanocarbon-PAni composite were tested in a liquid electrolyte cell system. Experimental design was used to select the type of nanocarbon filler and composite loadings, and yielded a good balance of electromechanical properties. Raman spectroscopy suggests good interaction between PAni and the nanocarbon fillers. Electron microscopy showed that graphene oxide dispersed the best, followed by multiwall carbon nanotubes, while nitrogen-doped nanotube composites showed dispersion problems and thus poor performance. Multiwall carbon nanotube composite actuators showed the best performance based on the combination of bending angle, bending velocity and maximum working cycles, while graphene oxide attained similarly good performance due to its best dispersion. This parallel testing of a broad set of nanocarbon fillers on PAni-composite actuators is unprecedented to the best of our knowledge and shows that the type and properties of the carbon nanomaterial are critical to the performance of electromechanical devices with other conditions remaining equal. PMID:26595669

  2. Characteristics performance of production-worthy multiple e-beam maskless lithography

    NASA Astrophysics Data System (ADS)

    Lin, S. J.; Wang, W. C.; Chen, P. S.; Liu, C. Y.; Lo, T. N.; Chen, Jack J. H.; Krecinic, Faruk; Lin, Burn J.

    2010-03-01

    E-beam direct write (EBDW) is one of the potential solutions for technology nodes of 28-nm half-pitch (HP) and beyond. Throughput limitation confined its development mostly to small-volume prototyping. Recently, proposals have been made to achieve throughput greater than 10 wafers per hour (WPH) on a single column with >10,000 beams writing in parallel (MEBDW), or even greater than 100 WPH by further clustering multiple columns within a typical production-tool footprint. The MAPPER concept contains a CMOS-MEMS blanker array driven by high-speed optical data path architecture to simultaneously control >10,000 beams, switching them on and off independently. The MAPPER Pre-Alpha Tool with a 110-beam, 5-keV column and a 300-mm wafer stage has been installed in a semiconductor manufacturing cleanroom environment and is ready for imaging test. In this paper, the resist imaging results of 110-beam parallel raster-scan writing for 30-nm half-pitch (HP) dense hole on 300-mm wafer is shown. The challenges of implementing multiple e-beam maskless lithography (MEBML2) in mass production environment, including resolution, local variation, focusing, energy latitude, proximity effect correction and electron scattering model fitting of hole patterning are discussed. Similar to mask-error-enhanced-factor (MEEF), the new writing-error-enhanced-factor (WEEF) to describe the impact of writing error, is introduced.

  3. Cross-beam pulsed laser fabrication of Free-Standing Nanostructured Carbon Nanotubes-Pt-Ceria Anode with unprecedented electroactivity and durability for ethanol oxidation

    NASA Astrophysics Data System (ADS)

    Wang, Youling; Tabet-Aoul, Amel; Gougis, Maxime; Mohamedi, Mohamed

    2015-01-01

    Owing to its inherent properties such as great capacity to store and release oxygen, lattice oxygen that has a key role in removing the CO poisoning effect, non-toxicity, abundance, low cost and low temperature processing, CeO2 is emerging as a unique class of electrode material for low temperature polymer electrolyte fuel cells such as direct ethanol fuel cells (DEFCs). However, the maximal exploitation of its functional properties is strictly reliant on the availability of optimized synthesis routes that allow tailor-designing, architecturing and manipulation of CeO2 in a precise manner when it is combined with other functional materials. Here we use the cross-beam pulsed laser deposition (CBPLD) technique to synthesize free-standing (binderless) Pt-CeO2 nanostructured thin films onto carbon nanotubes as anodes for ethanol oxidation reaction. Further significance of this work is that it establishes the importance in the design of the catalyst layer architecture. Indeed, we demonstrate here that when CeO2 material is beneath or when it is mixed with Pt, the interactions between Pt with CeO2 are not similar leading inevitably to different electrocatalytic performances. Given proper tailoring synthesis conditions, CBPLD-developed Pt-CeO2 thin films are remarkably stable and provide electrochemical performance much greater than the layer onto layer CeO2/Pt architecture.

  4. ION EXCHANGE PERFORMANCE OF TITANOSILICATES, GERMANATES AND CARBON NANOTUBES

    SciTech Connect

    Alsobrook, A. N.; Hobbs, D. T.

    2013-04-24

    This report presents a summary of testing the affinity of titanosilicates (TSP), germanium-substituted titanosilicates (Ge-TSP) and multiwall carbon nanotubes (MWCNT) for lanthanide ions in dilute nitric acid solution. The K-TSP ion exchanger exhibited the highest affinity for lanthanides in dilute nitric acid solutions. The Ge-TSP ion exchanger shows promise as a material with high affinity, but additional tests are needed to confirm the preliminary results. The MWCNT exhibited much lower affinities than the K-TSP in dilute nitric acid solutions. However, the MWCNT are much more chemically stable to concentrated nitric acid solutions and, therefore, may candidates for ion exchange in more concentrated nitric acid solutions. This technical report serves as the deliverable documenting completion of the FY13 research milestone, M4FT-13SR0303061 – measure actinide and lanthanide distribution values in nitric acid solutions with sodium and potassium titanosilicate materials.

  5. In vivo performance of selective electron beam-melted Ti-6Al-4V structures.

    PubMed

    Ponader, Sabine; von Wilmowsky, Cornelius; Widenmayer, Martin; Lutz, Rainer; Heinl, Peter; Körner, Carolin; Singer, Robert F; Nkenke, Emeka; Neukam, Friedrich W; Schlegel, Karl A

    2010-01-01

    Highly porous titanium structures are widely used for maxillofacial and orthopedic surgery because of their excellent mechanical properties similar to those of human bone and their facilitation of bone ingrowth. In contrast to common methods, the generation of porous titaniumproducts by selective electron beam melting (SEBM), an additive manufacturing technology, overcomes difficulties concerning the extreme chemical affinity of liquid titanium to atmospheric gases which consequently leads to strongly reduced ductility of the metal. The purpose of this study was to assess the suitability of a smooth compact and a porous Ti-6Al-4V structure directly produced by the SEBM process as scaffolds for bone formation. SEBM-processed titanium implants were placed into defects in the frontal skull of 15 domestic pigs. To evaluate the direct contact between bone and implant surfaces and to assess the ingrowth of osseous tissue into the porous structure, microradiographs and histomorphometric analyses were performed 14, 30, and 60 days after surgery. Bone ingrowth increased significantly during the period of this study. After 14 days the most outer regions of the implants were already filled with newly formed bone tissue (around 14%). After 30 days the bone volume inside the implants reached almost 30% and after 60 days abundant bone formation inside the implants attained 46%. During the study only scarce bone-implant contact was found around all implants, which did not exceed 9% around compact specimens and 6% around porous specimens after 60 days. This work demonstrates that highly porous titanium implants with excellent interconnectivity manufactured using the SEBM method are suitable scaffolds for bone ingrowth. This technique is a good candidate for orthopedic and maxillofacial applications.

  6. A thermal-metallurgical model of laser beam welding simulation for carbon steels

    NASA Astrophysics Data System (ADS)

    Mi, Gaoyang; Zhan, Xiaohong; Wei, Yanhong; Ou, Wenmin; Gu, Cheng; Yu, Fengyi

    2015-04-01

    A coupled thermal-metallurgical model is developed to predict the temperature fields and spatial distribution of volume fraction of phases during laser beam welding of 1020, 1045, and 1060 steels. The classical transient heat conduction model is used to calculate the temperature fields during laser beam welding. For phase transformation, the austenization, the austenite-to-pearlite/ferrite transformation, the austenite-to-bainite transformation, and the austenite-to-martensite transformation are modeled respectively. All of these transformation models are solved by the finite element method (FEM) based on the simulated temperature fields. The thermal properties of the three steels are determined by the linear interpolation base of the phase fractions, and thermal properties for each pure phase. The temperature fields and spatial distribution of phases are predicted by 3D finite element method (FEM) code which is developed by the authors to solve the thermal-metallurgical models. In addition, comparison between the coupled model and the pure conduction model without considering phase transformations is carried out to study the influence of phase transformation on temperature fields during welding. According to the comparison, the temperature of the coupled model is higher than the pure conduction model in the temperature region above 1000 °C, but the temperature profiles are very similar at the temperature region under 1000 °C. The predicted volume fractions of 1020 and 1060 steels are close to experimental results. However, there is an obvious difference between predicted and experimental results of the phase fraction of 1045 steels.

  7. Effective generation of the spread-out-Bragg peak from the laser accelerated proton beams using a carbon-proton mixed target.

    PubMed

    Yoo, Seung Hoon; Cho, Ilsung; Cho, Sungho; Song, Yongkeun; Jung, Won-Gyun; Kim, Dae-Hyun; Shin, Dongho; Lee, Se Byeong; Pae, Ki-Hong; Park, Sung Yong

    2014-12-01

    Conventional laser accelerated proton beam has broad energy spectra. It is not suitable for clinical use directly, so it is necessary for employing energy selection system. However, in the conventional laser accelerated proton system, the intensity of the proton beams in the low energy regime is higher than that in the high energy regime. Thus, to generate spread-out-Bragg peak (SOBP), stronger weighting value to the higher energy proton beams is needed and weaker weighting value to the lower energy proton beams is needed, which results in the wide range of weighting values. The purpose of this research is to investigate a method for efficient generating of the SOBP with varying magnetic field in the energy selection system using a carbon-proton mixture target. Energy spectrum of the laser accelerated proton beams was acquired using Particle-In-Cell simulations. The Geant4 Monte Carlo simulation toolkit was implemented for energy selection, particle transportation, and dosimetric property measurement. The energy selection collimator hole size of the energy selection system was changed from 1 to 5 mm in order to investigate the effect of hole size on the dosimetric properties for Bragg peak and SOBP. To generate SOBP, magnetic field in the energy selection system was changed during beam irradiation with each beam weighting factor. In this study, our results suggest that carbon-proton mixture target based laser accelerated proton beams can generate quasi-monoenergetic energy distribution and result in the efficient generation of SOBP. A further research is needed to optimize SOBP according to each range and modulated width using an optimized weighting algorithm.

  8. A Study of Charged Current Single Charged Pion Productions on Carbon in a Few-GeV Neutrino Beam

    SciTech Connect

    Hiraide, Katsuki

    2009-01-01

    Understanding single charged pion production via neutrino-nucleus charged current interaction in the neutrino energy region of a few GeV is essential for future neutrino oscillation experiments since this process is a dominant background for vμ → vx oscillation measurements. There are two contributions to this process: single pion production via baryonic resonance (vμN → μ-+) and coherent pion production interacting with the entire nucleus (vμA → μ-+), where N is nucleon in the nucleus and A is the nucleus. The purpose of the study presented in this thesis is a precise measurement of charged current single charged pion productions, resonant and coherent pion productions, with a good final state separation in the neutrino energy region of a few GeV. In this thesis, we focus on the study of charged current coherent pion production from muon neutrinos scattering on carbon, vμ 12C → μ-12+, in the SciBooNE experiment. This is motivated by the fact that without measuring this component first, the precise determination of resonant pion production cross section can not be achieved since the contribution of coherent pion production in the region of small muon scattering angle is not small. Furthermore, the coherent process is particularly interesting because it is deeply rooted in fundamental physics via Adler's partially conserved axial-vector current theorem. We took data from June 2007 until August 2008, in both the neutrino and antineutrino beam. In total, 2.52 x 1020 protons on target were collected. We have performed a search for charged current coherent pion production by using SciBooNE's full neutrino data set, corresponding to 0.99 x 1020 protons on target. No evidence for coherent pion production is observed. We set 90% confidence level upper limits on the cross section ratio of charged

  9. Seismic performance of RC beam-column connections with continuous rectangular spiral transverse reinforcements for low ductility classes.

    PubMed

    Azimi, Mohammadamin; Bin Adnan, Azlan; Sam, Abdul Rahman Bin Mohd; Tahir, Mahmood Md; Faridmehr, Iman; Hodjati, Reza

    2014-01-01

    The seismic performance of RC columns could be significantly improved by continuous spiral reinforcement as a result of its adequate ductility and energy dissipation capacity. Due to post-earthquake brittle failure observations in beam-column connections, the seismic behaviour of such connections could greatly be improved by simultaneous application of this method in both beams and columns. In this study, a new proposed detail for beam to column connection introduced as "twisted opposing rectangular spiral" was experimentally and numerically investigated and its seismic performance was compared against normal rectangular spiral and conventional shear reinforcement systems. In this study, three full scale beam to column connections were first designed in conformance with Eurocode (EC2-04) for low ductility class connections and then tested by quasistatic cyclic loading recommended by ACI Building Code (ACI 318-02). Next, the experimental results were validated by numerical methods. Finally, the results revealed that the new proposed connection could improve the ultimate lateral resistance, ductility, and energy dissipation capacity. PMID:25309957

  10. Seismic Performance of RC Beam-Column Connections with Continuous Rectangular Spiral Transverse Reinforcements for Low Ductility Classes

    PubMed Central

    Adnan, Azlan Bin; Bin Mohd Sam, Abdul Rahman; Tahir, Mahmood Md; Hodjati, Reza

    2014-01-01

    The seismic performance of RC columns could be significantly improved by continuous spiral reinforcement as a result of its adequate ductility and energy dissipation capacity. Due to post-earthquake brittle failure observations in beam-column connections, the seismic behaviour of such connections could greatly be improved by simultaneous application of this method in both beams and columns. In this study, a new proposed detail for beam to column connection introduced as “twisted opposing rectangular spiral” was experimentally and numerically investigated and its seismic performance was compared against normal rectangular spiral and conventional shear reinforcement systems. In this study, three full scale beam to column connections were first designed in conformance with Eurocode (EC2-04) for low ductility class connections and then tested by quasistatic cyclic loading recommended by ACI Building Code (ACI 318-02). Next, the experimental results were validated by numerical methods. Finally, the results revealed that the new proposed connection could improve the ultimate lateral resistance, ductility, and energy dissipation capacity. PMID:25309957

  11. Seismic performance of RC beam-column connections with continuous rectangular spiral transverse reinforcements for low ductility classes.

    PubMed

    Azimi, Mohammadamin; Bin Adnan, Azlan; Sam, Abdul Rahman Bin Mohd; Tahir, Mahmood Md; Faridmehr, Iman; Hodjati, Reza

    2014-01-01

    The seismic performance of RC columns could be significantly improved by continuous spiral reinforcement as a result of its adequate ductility and energy dissipation capacity. Due to post-earthquake brittle failure observations in beam-column connections, the seismic behaviour of such connections could greatly be improved by simultaneous application of this method in both beams and columns. In this study, a new proposed detail for beam to column connection introduced as "twisted opposing rectangular spiral" was experimentally and numerically investigated and its seismic performance was compared against normal rectangular spiral and conventional shear reinforcement systems. In this study, three full scale beam to column connections were first designed in conformance with Eurocode (EC2-04) for low ductility class connections and then tested by quasistatic cyclic loading recommended by ACI Building Code (ACI 318-02). Next, the experimental results were validated by numerical methods. Finally, the results revealed that the new proposed connection could improve the ultimate lateral resistance, ductility, and energy dissipation capacity.

  12. Durability, Performance, and Emission of Diesel Engines Using Carbon Fiber Piston and Liner

    NASA Technical Reports Server (NTRS)

    Afify, E. M.; Roberts, W. L.

    1999-01-01

    This report summarizes the research conducted by NC State University in investigating the durability, performance and emission of a carbon fiber piston and liner in our single cylinder research Diesel engine. Both the piston and liner were supplied to NC State University by NASA LaRC and manufactured by C-CAT under a separate contract to NASA LaRC. The carbon-carbon material used to manufacture the piston and liner has significantly lower thermal conductivity, coefficient of thermal expansion, and superior strength characteristics at elevated temperatures when compared to conventional piston materials such as aluminum. The results of the carbon-carbon fiber piston testing were compared to a baseline configuration, which used a conventional aluminum piston in a steel liner. The parameters measured were the brake specific fuel consumption, ignition delay, frictional horsepower, volumetric efficiency, and durability characteristics of the two pistons. Testing was performed using a naturally aspirated Labeco Direct Injection single cylinder diesel engine. Two test cases were performed over a range of loads and speeds. The fixed test condition between the aluminum and carbon-carbon piston configurations was the brake mean effective pressure. The measured data was the fuel consumption rate, volumetric efficiency, load, speed, cylinder pressure, needle lift, and exhaust gas temperature. The cylinder pressure, and fuel consumption, exhaust gas temperature, and needle lift were recorded using a National Instruments DAQ board and a PC. All test cases used Diesel no. 2 for fuel.

  13. Improving ion beam injector performance by augmenting capacitance of vacuum diode

    SciTech Connect

    Goerz, D. A., LLNL

    1998-06-24

    The recirculating induction accelerator is a new class of particle accelerator being developed at LLNL as a reduced-cost driver for heavy-ion beam driven inertial fusion energy. Ongoing research and development of advanced beam control technologies for the recirculator system requires a very stable and reproducible ion beam source. The injector pulse modulator must be capable of producing very precise high-voltage pulses in order to reduce the current modulation instability and achieve the required beam reproducibility. Computer modeled simulations of beam dynamics have established that errors greater than 0.1 percent in the flatness of the 120 kV injector pulse can create intolerable energy deviations. The pulse modulator that was developed to satisfy the stringent requirements is described in the accompanying paper by Wilson [1]. A crucial aspect of the overall solution is a modification made to the vacuum diode apparatus, whereby high-voltage capacitors were added in close proximity to the thermionic potassium-ion emitter. This paper discusses the rationale for augmenting the normally small capacitance of the injector diode, and presents design information, including an illustrated layout, electrostatic field modeling results, and data on ceramic capacitors operating at elevated levels.

  14. Microstructure and property of diamond-like carbon films with Al and Cr co-doping deposited using a hybrid beams system

    NASA Astrophysics Data System (ADS)

    Dai, Wei; Liu, Jingmao; Geng, Dongsen; Guo, Peng; Zheng, Jun; Wang, Qimin

    2016-12-01

    DLC films with weak carbide former Al and carbide former Cr co-doping (Al:Cr-DLC) were deposited by a hybrid beams system comprising an anode-layer linear ion beam source (LIS) and high power impulse magnetron sputtering using a gas mixture of C2H2 and Ar as the precursor. The doped Al and Cr contents were controlled via adjusting the C2H2 fraction in the gas mixture. The composition, microstructure, compressive stress, mechanical properties and tribological behaviors of the Al:Cr-DLC films were researched carefully using X-ray photoelectron spectroscopy, transmission electron microscopy, Raman spectroscopy, stress-tester, nanoindentation and ball-on-plate tribometer as function of the C2H2 fraction. The results show that the Al and Cr contents in the films increased continuously as the C2H2 fraction decreased. The doped Cr atoms preferred to bond with the carbon while the Al atoms mainly existed in metallic state. Structure modulation with alternate multilayer consisted of Al-poor DLC layer and Al-rich DLC layer was found in the films. Those periodic Al-rich DLC layers can effectively release the residual stress of the films. On the other hand, the formation of the carbide component due to Cr incorporation can help to increase the film hardness. Accordingly, the residual stress of the DLC films can be reduced without sacrificing the film hardness though co-doping Al and Cr atoms. Furthermore, it was found that the periodic Al-rich layer can greatly improve the elastic resilience of the DLC films and thus decreases the film friction coefficient and wear rate significantly. However, the existence of the carbide component would cause abrasive wear and thus deteriorate the wear performance of the films.

  15. Dosimetric precision of an ion beam tracking system

    PubMed Central

    2010-01-01

    Background Scanned ion beam therapy of intra-fractionally moving tumors requires motion mitigation. GSI proposed beam tracking and performed several experimental studies to analyse the dosimetric precision of the system for scanned carbon beams. Methods A beam tracking system has been developed and integrated in the scanned carbon ion beam therapy unit at GSI. The system adapts pencil beam positions and beam energy according to target motion. Motion compensation performance of the beam tracking system was assessed by measurements with radiographic films, a range telescope, a 3D array of 24 ionization chambers, and cell samples for biological dosimetry. Measurements were performed for stationary detectors and moving detectors using the beam tracking system. Results All detector systems showed comparable data for a moving setup when using beam tracking and the corresponding stationary setup. Within the target volume the mean relative differences of ionization chamber measurements were 0.3% (1.5% standard deviation, 3.7% maximum). Film responses demonstrated preserved lateral dose gradients. Measurements with the range telescope showed agreement of Bragg peak depth under motion induced range variations. Cell survival experiments showed a mean relative difference of -5% (-3%) between measurements and calculations within the target volume for beam tracking (stationary) measurements. Conclusions The beam tracking system has been successfully integrated. Full functionality has been validated dosimetrically in experiments with several detector types including biological cell systems. PMID:20591160

  16. High performance batteries with carbon nanomaterials and ionic liquids

    DOEpatents

    Lu, Wen

    2012-08-07

    The present invention is directed to lithium-ion batteries in general and more particularly to lithium-ion batteries based on aligned graphene ribbon anodes, V.sub.2O.sub.5 graphene ribbon composite cathodes, and ionic liquid electrolytes. The lithium-ion batteries have excellent performance metrics of cell voltages, energy densities, and power densities.

  17. The use of multi-gap resistive plate chambers for in-beam PET in proton and carbon ion therapy

    PubMed Central

    Watts, David; Borghi, Giacomo; Sauli, Fabio; Amaldi, Ugo

    2013-01-01

    On-line verification of the delivered dose during proton and carbon ion radiotherapy is currently a very desirable goal for quality assurance of hadron therapy treatment plans. In-beam positron emission tomography (ibPET), which can provide an image of the β+ activity induced in the patient during irradiation, which in turn is correlated to the range of the ion beam, is one of the modalities for achieving this goal. Application to hadron therapy requires that the scanner geometry be modified from that which is used in nuclear medicine. In particular, PET detectors that allow a sub-nanosecond time-of-flight (TOF) registration of the collinear photons have been proposed. Inclusion of the TOF information in PET data leads to more effective PET sensitivity. Considering the challenges inherent in the ibPET technique, namely limited β+ activity and the effect of biological washout due to blood flow, TOF-PET technologies are very attractive. In this context, the TERA Foundation is investigating the use of resistive plate chambers (RPC) for an ibPET application because of their excellent timing properties and low cost. In this paper we present a novel compact multi-gap RPC (MRPC) module design and construction method, which considering the large number of modules that would be needed to practically implement a high-sensitivity RPC-PET scanner, could be advantageous. Moreover, we give an overview of the efficiency and timing measurements that have been obtained in the laboratory using such single-gap and multi-gap RPC modules. PMID:23824118

  18. Fragmentation of 200 and 244 MEV/u Carbon Beams in Thick Tissue-Like Absorbers

    NASA Technical Reports Server (NTRS)

    Golovchenko, A. N.; Skvarc, J.; Ilic, R.; Sihver, L.; Bamblevski, V. P.; Tretyakova, S. P.; Schardt, D.; Tripathi, R. K.; Wilson, J. W.; Bimbot, R.

    1999-01-01

    Stacks consisting of thin CR-39 sheets sandwiched between thick lucite and water absorbers were perpendicularly bombarded by C-12 ions at 200 and 244 MeV/u. Track radius distributions representing the charge composition of the fragmented beams were automatically measured by a particle track analysis system. After analysis of the nuclear charge distributions, the total charge removal cross-sections and elemental production cross-sections of fragments with atomic numbers from 5 to 3, were obtained down to the lower energies (approx. 50 and 100 MeV/u, respectively). It has been found that the measured total charge removal cross-section agrees with theoretical predictions within approx. 10% and very well with previous experiments in corresponding energy regions. Two model calculations for production of B fragment are in good agreement with our measured data while a third model overestimates it by approx. 12%. Theoretical cross-sections for Be and Li fragments differ strongly among the different models and from measured values.

  19. Description of the performances of a thermo-mechanical energy harvester using bimetallic beams

    NASA Astrophysics Data System (ADS)

    Arnaud, A.; Boughaleb, J.; Monfray, S.; Boeuf, F.; Cugat, O.; Skotnicki, T.

    2016-06-01

    Many recent researches have been focused on the development of thermal energy harvesters using thermo-mechanical or thermo-electrical coupling phenomena associated to a first-order thermodynamic transition. In the case of the bimetallic strip heat engine, the exploitation of the thermo-mechanical instability of bimetallic membranes placed in a thermal gradient enables to convert heat into kinetic energy. This paper is a contribution to the modeling and the comprehension of these heat engines. By restraining the study to the simply-supported bimetallic beams and using a Ritz approximation of the beam shape, this paper aims to give an analytical solution to the first mode of the composite beams and then to evaluate the efficiency of the harvesters exploiting these kinds of instability.

  20. Performance of a liquid argon time projection chamber exposed to the CERN West Area Neutrino Facility neutrino beam

    SciTech Connect

    Arneodo, F.; Cavanna, F.; Mitri, I. De; Mortari, G. Piano; Benetti, P.; Borio di Tigliole, A.; Calligarich, E.; Cesana, E.; Dolfini, R.; Mauri, F.; Montanari, C.; Rappoldi, A.; Raselli, G. L.; Rubbia, C.; Terrani, M.; Vignoli, C.; Bonesini, M.; Boschetti, B.; Cavalli, D.; Curioni, A.

    2006-12-01

    We present the results of the first exposure of a Liquid Argon TPC to a multi-GeV neutrino beam. The data have been collected with a 50 liters ICARUS-like chamber located between the CHORUS and NOMAD experiments at the CERN West Area Neutrino Facility (WANF). We discuss both the instrumental performance of the detector and its capability to identify and reconstruct low-multiplicity neutrino interactions.

  1. The EGFR mutation status affects the relative biological effectiveness of carbon-ion beams in non-small cell lung carcinoma cells.

    PubMed

    Amornwichet, Napapat; Oike, Takahiro; Shibata, Atsushi; Nirodi, Chaitanya S; Ogiwara, Hideaki; Makino, Haruhiko; Kimura, Yuka; Hirota, Yuka; Isono, Mayu; Yoshida, Yukari; Ohno, Tatsuya; Kohno, Takashi; Nakano, Takashi

    2015-06-11

    Carbon-ion radiotherapy (CIRT) holds promise to treat inoperable locally-advanced non-small cell lung carcinoma (NSCLC), a disease poorly controlled by standard chemoradiotherapy using X-rays. Since CIRT is an extremely limited medical resource, selection of NSCLC patients likely to benefit from it is important; however, biological predictors of response to CIRT are ill-defined. The present study investigated the association between the mutational status of EGFR and KRAS, driver genes frequently mutated in NSCLC, and the relative biological effectiveness (RBE) of carbon-ion beams over X-rays. The assessment of 15 NSCLC lines of different EGFR/KRAS mutational status and that of isogenic NSCLC lines expressing wild-type or mutant EGFR revealed that EGFR-mutant NSCLC cells, but not KRAS-mutant cells, show low RBE. This was attributable to (i) the high X-ray sensitivity of EGFR-mutant cells, since EGFR mutation is associated with a defect in non-homologous end joining, a major pathway for DNA double-strand break (DSB) repair, and (ii) the strong cell-killing effect of carbon-ion beams due to poor repair of carbon-ion beam-induced DSBs regardless of EGFR mutation status. These data highlight the potential of EGFR mutation status as a predictor of response to CIRT, i.e., CIRT may show a high therapeutic index in EGFR mutation-negative NSCLC.

  2. The EGFR mutation status affects the relative biological effectiveness of carbon-ion beams in non-small cell lung carcinoma cells.

    PubMed

    Amornwichet, Napapat; Oike, Takahiro; Shibata, Atsushi; Nirodi, Chaitanya S; Ogiwara, Hideaki; Makino, Haruhiko; Kimura, Yuka; Hirota, Yuka; Isono, Mayu; Yoshida, Yukari; Ohno, Tatsuya; Kohno, Takashi; Nakano, Takashi

    2015-01-01

    Carbon-ion radiotherapy (CIRT) holds promise to treat inoperable locally-advanced non-small cell lung carcinoma (NSCLC), a disease poorly controlled by standard chemoradiotherapy using X-rays. Since CIRT is an extremely limited medical resource, selection of NSCLC patients likely to benefit from it is important; however, biological predictors of response to CIRT are ill-defined. The present study investigated the association between the mutational status of EGFR and KRAS, driver genes frequently mutated in NSCLC, and the relative biological effectiveness (RBE) of carbon-ion beams over X-rays. The assessment of 15 NSCLC lines of different EGFR/KRAS mutational status and that of isogenic NSCLC lines expressing wild-type or mutant EGFR revealed that EGFR-mutant NSCLC cells, but not KRAS-mutant cells, show low RBE. This was attributable to (i) the high X-ray sensitivity of EGFR-mutant cells, since EGFR mutation is associated with a defect in non-homologous end joining, a major pathway for DNA double-strand break (DSB) repair, and (ii) the strong cell-killing effect of carbon-ion beams due to poor repair of carbon-ion beam-induced DSBs regardless of EGFR mutation status. These data highlight the potential of EGFR mutation status as a predictor of response to CIRT, i.e., CIRT may show a high therapeutic index in EGFR mutation-negative NSCLC. PMID:26065573

  3. The formation of nanostructured carbon material on a ferrocene-containing polymer surface induced by a high-power ion beam

    NASA Astrophysics Data System (ADS)

    Kovivchak, V. S.; Kryazhev, Yu. G.; Zapevalova, E. S.

    2016-02-01

    The surface morphology and the composition of polymer layers based on chlorinated polyvinylchloride with addition of ferrocene (up to 10% of the polymer mass) subject to the action of a nanosecond high-power ion beam are studied. It is demonstrated that carbon material in the form of nanofibers with an average diameter of 80 nm and a length of up to 10 μm is formed on a surface singly irradiated by such beam with a current density of ˜100 A/cm2. A possible mechanism of the observed phenomenon is discussed.

  4. Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers

    NASA Astrophysics Data System (ADS)

    Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

    2015-02-01

    Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

  5. Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers.

    PubMed

    Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

    2015-01-01

    Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

  6. Facile Carbon Fixation to Performic Acids by Water-Sealed Dielectric Barrier Discharge.

    PubMed

    Kawasaki, Mitsuo; Morita, Tatsuo; Tachibana, Kunihide

    2015-01-01

    Carbon fixation refers to the conversion of carbon dioxide (CO2) to organic materials, as commonly performed in nature through photosynthesis by plants and other autotrophic organisms. The creation of artificial carbon fixation processes is one of the greatest challenges for chemistry to solve the critical environmental issue concerning the reduction of CO2 emissions. We have developed an electricity-driven facile CO2 fixation process that yields performic acid, HCO2OH, from CO2 and water at neutral pH by dielectric barrier discharge with an input electric power conversion efficiency of currently 0.2-0.4%. This method offers a promising future technology for artificial carbon fixation on its own, and may also be scaled up in combination with e.g., the post-combustion CO2 capture and storage technology. PMID:26439402

  7. Facile Carbon Fixation to Performic Acids by Water-Sealed Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Kawasaki, Mitsuo; Morita, Tatsuo; Tachibana, Kunihide

    2015-10-01

    Carbon fixation refers to the conversion of carbon dioxide (CO2) to organic materials, as commonly performed in nature through photosynthesis by plants and other autotrophic organisms. The creation of artificial carbon fixation processes is one of the greatest challenges for chemistry to solve the critical environmental issue concerning the reduction of CO2 emissions. We have developed an electricity-driven facile CO2 fixation process that yields performic acid, HCO2OH, from CO2 and water at neutral pH by dielectric barrier discharge with an input electric power conversion efficiency of currently 0.2-0.4%. This method offers a promising future technology for artificial carbon fixation on its own, and may also be scaled up in combination with e.g., the post-combustion CO2 capture and storage technology.

  8. Facile Carbon Fixation to Performic Acids by Water-Sealed Dielectric Barrier Discharge

    PubMed Central

    Kawasaki, Mitsuo; Morita, Tatsuo; Tachibana, Kunihide

    2015-01-01

    Carbon fixation refers to the conversion of carbon dioxide (CO2) to organic materials, as commonly performed in nature through photosynthesis by plants and other autotrophic organisms. The creation of artificial carbon fixation processes is one of the greatest challenges for chemistry to solve the critical environmental issue concerning the reduction of CO2 emissions. We have developed an electricity-driven facile CO2 fixation process that yields performic acid, HCO2OH, from CO2 and water at neutral pH by dielectric barrier discharge with an input electric power conversion efficiency of currently 0.2−0.4%. This method offers a promising future technology for artificial carbon fixation on its own, and may also be scaled up in combination with e.g., the post-combustion CO2 capture and storage technology. PMID:26439402

  9. Recent performance of the SNS H{sup −} ion source and low-energy beam transport system

    SciTech Connect

    Stockli, Martin P. Ewald, K. D.; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Piller, C.; Santana, M.; Tang, J.; Welton, R.

    2014-02-15

    Recent measurements of the H{sup −} beam current show that SNS is injecting about 55 mA into the RFQ compared to ∼45 mA in 2010. Since 2010, the H{sup −} beam exiting the RFQ dropped from ∼40 mA to ∼34 mA, which is sufficient for 1 MW of beam power. To minimize the impact of the RFQ degradation, the service cycle of the best performing source was extended to 6 weeks. The only degradation is fluctuations in the electron dump voltage towards the end of some service cycles, a problem that is being investigated. Very recently, the RFQ was retuned, which partly restored its transmission. In addition, the electrostatic low-energy beam transport system was reengineered to double its heat sinking and equipped with a thermocouple that monitors the temperature of the ground electrode between the two Einzel lenses. The recorded data show that emissions from the source at high voltage dominate the heat load. Emissions from the partly Cs-covered first lens cause the temperature to peak several hours after starting up. On rare occasions, the temperature can also peak due to corona discharges between the center ground electrode and one of the lenses.

  10. Performance of a superconducting magnet system operated in the Super Omega Muon beam line at J-PARC

    SciTech Connect

    Makida, Yasuhiro; Ikedo, Yutaka; Ogitsu, Toru; Shimomura, Koichiro; Miyake, Yasuhiro; Yoshida, Makoto; Adachi, Taihei; Kadono, Ryosuke; Kawamura, Naritoshi; Strasser, Patric; Koda, Akihiro; Fujimori, Hiroshi; Nishiyama, Kusuo; Ohhata, Hirokatsu; Okamura, Takahiro; Okada, Ryutaro; Orikasa, Tomofumi

    2014-01-29

    A superconducting magnet system, which is composed of an 8 m long solenoid for transportation and 12 short solenoids for focusing, has been developed for Muon Science Establishment facility of J-PARC. The transport solenoid is composed of a 6 m straight section connected to a 45 degree curved section at each end. Muons of various momenta and of both electric charges are transported through the solenoid inner bore with an effective diameter of 0.3 m, where 2 T magnetic field is induced. There are 12 focusing solenoids with an effective bore diameter of 0.6 m and a length of 0.35 m arranged on a straight line at suitable intervals. The maximum central field of each focusing solenoid is 0.66 T. All solenoid coils are cooled by GM cryocoolers through their own conductions. The magnet system has been installed into the beam line in the summer of 2012, and its performance has been checked. Beam commissioning has been carried out since October 2012. During beam operation, temperature rise over 6 K in the transport solenoid due to a nuclear heating from the muon production target is observed at beam intensity of about 300 kW.

  11. Performance of the Compact Visual Beam Imaging System on the GM/CA BM Beamline at the APS

    NASA Astrophysics Data System (ADS)

    Xu, S.; Ogata, C. M.; Makarov, O.; Corcoran, S.; Ferguson, D.; Fischetti, R. F.

    2013-03-01

    A typical problem encountered on a beamline with a sagittal focusing monochromator is the difficulty of optimizing the crystal alignment because the full width of the monochromatic, unfocused beam cannot be visualized. This problem is particularly acute on beamlines that accept a wide swath of radiation combined with a fixed experimental setup consisting of constrained apertures that only allow the focused beam to pass through to the sample position. To address this problem, an imaging system has been designed and implemented on the GM/CA bending magnet beamline at the Advanced Photon Source, Argonne National Laboratory. This imaging system consists of a 30mm × 50mm flat YAG crystal, right angle prism/mirror and video camera located downstream of the vertical collimating mirror, sagittally focusing monochromator and vertical focusing mirror. The YAG crystal was installed in a 6-way vacuum cross in the beam path, and was mounted on a linear translation feedthrough allowing remote controlled insertion and removal of the crystal from the beam path. The CCD camera was mounted outside the vacuum chamber and views the x-ray induced scintillation from the YAG crystal through a window. This visualizer allows one to optimize the twist, yaw and roll of the second crystal, facilitates proper sagittal focusing and serves as a remote controlled diagnostic tool. An overview of the design and the performance of the imaging system will be presented.

  12. Advances in performance and beam quality of 9xx-nm laser diodes tailored for efficient fiber coupling

    NASA Astrophysics Data System (ADS)

    Lauer, Christian; König, Harald; Grönninger, Günther; Hein, Sebastian; Gomez-Iglesias, Alvaro; Furitsch, Michael; Maric, Josip; Kissel, Heiko; Wolf, Paul; Biesenbach, Jens; Strauss, Uwe

    2012-03-01

    The impact of new direct-diode and fiber laser systems on industrial manufacturing drives the demand for highbrightness diode laser pump sources suitable for simple fiber coupling with high efficiency. Within the German funded project HEMILAS laser mini-bars with different bar geometries and small fill factors were investigated. We present results on 9xx nm bars with tailored beam parameter products for simplified coupling to fibers with core diameters of 200μm and 300μm with a numerical aperture of 0.22 and compare beam quality parameters, brightness, conversion efficiency, and thermal performance of different bar designs. Optimized epitaxy structures yield conversion efficiency maxima above 66%. The slow axis divergence angle of mini-bars with a fill factor of 10% featuring five 100μm wide and 4mm long emitters based on this epitaxy structure stays below 7°, which corresponds to a beam parameter product of 15mm mrad, up to very high output power of over 45W. This result was achieved for mounting on actively cooled submounts using hard solder. A similar bar with 5mm cavity length and using soft soldering reached an output power of 60W at the same beam parameter product. At 4mm cavity length, no COMD failures were observed up to currents exceeding the thermal rollover and the maximum output cw power was 95W.

  13. Comparison of Reported and Inferred Neutral Beam Performance by Neutron and Spectroscopic Measurements on DIII-D

    NASA Astrophysics Data System (ADS)

    Rozansky, R. N.; Grierson, B. A.; Heidbrink, W. W.

    2013-10-01

    The DIII-D tokamak is equipped with eight sources for neutral beam injection (NBI). Recent studies of neutron rates indicate that the power injected by each source can differ from the values derived from NBI transmission calculations. During experimental operation, the first discharge of each day is a ``reference shot'' that provides information on wall conditions and neutral beam performance. During this reference shot all NBI sources are injected into steady plasma conditions enabling qualitative comparison between sources, and absolute comparison with fusion neutron counters. Spectroscopic diagnostics measure the neutral beam emission from up to six of the eight sources, as well as the circulating fast-ion content injected from all sources by the fast-ion D-alpha (FIDA) technique. Comparison of the neutron rate, beam emission, and fast-ion emission will be made with theoretical models of these processes in order to determine qualitative and quantitative agreement with expectations derived from reported NBI powers. Work supported by the National Undergraduate Fellowship Program in Plasma Physics and Fusion Energy Sciences and the US Department of Energy under DE-FC02-04ER54698, DE-AC02-09CH11466, and SC-G903402.

  14. Dynamic response of concrete beams externally reinforced with carbon fiber reinforced plastic (CFRP) subjected to impulsive loads

    SciTech Connect

    Jerome, D.M.; Ross, C.A.

    1996-12-31

    A series of 54 laboratory scale concrete beams 3 x 3 x 30 in. in size were impulsively loaded to failure in a drop weight impact machine. The beams had no internal reinforcement, but instead were externally reinforced on the bottom or tension side of the beams with 1, 2, and 3 ply AS4C/1919 graphite epoxy panels. In addition, several of the beams were also reinforced on the sides with 3 ply CFRP. The beams were simply supported in a drop weight machine and subjected to impact loads with amplitudes up to 10 kips, and durations less than 1 ms, at beam midspan. Measurements made during the loading event included beam total load, midspan displacement, as well as midspan strain at 3 locations in the beam`s cross-section. A high speed framing camera was also used to record the beam`s displacement-time behavior as well as to gain insight into the failure mechanisms. Beam midspan accelerations were determined by double differentiation of the displacement versus time data, and in turn, the beam`s inertial loads were calculated using the beam`s equivalent mass. Beam dynamic bending loads versus time were determined from the difference between the total load versus time and the inertial load versus time data. Bending loads versus displacements were also determined along with fracture energies. Failure to correct the loads for inertia will result in incorrect conclusions being drawn from the data, especially for bending resistance of brittle concrete test specimens. A comparison with quasistatic bending (fracture) energy data showed that the dynamic failure energy absorbed by the beams was always less than the static fracture energy, due to the brittle nature of concrete when impulsively loaded.

  15. Simulations of the performance of the Fusion-FEM, for an increased e-beam emittance

    SciTech Connect

    Tulupov, A.V.; Urbanus, W.H.; Caplan, M.

    1995-12-31

    The original design of the Fusion-FEM, which is under construction at the FOM-Institute for Plasma Physics, was based on an electron beam emittance of 50 {pi} mm mrad. Recent measurements of the emittance of the beam emitted by the electron gun showed that the actual emittance is 80 {pi} mm mrad. This results in a 2.5 times lower beam current density inside the undulator. As a result it changes the linear gain, the start-up time, the saturation level and the frequency spectrum. The main goal of the FEM project is to demonstrate a stable microwave output power of at least 1 MW. The decrease of the electron beam current density has to be compensated by variations of the other FEM parameters, such as the reflection (feedback) coefficient of the microwave cavity and the length of the drift gap between the two sections of the step-tapered undulator. All basic dependencies of the linear and nonlinear gain, and of the output power on the main FEM parameters have been simulated numerically with the CRMFEL code. Regimes of stable operation of the FEM with the increased emittance have been found. These regimes could be found because of the original flexibility of the FEM design.

  16. Ion beam nanopatterning and micro-Raman spectroscopy analysis on HOPG for testing FIB performances.

    PubMed

    Archanjo, B S; Maciel, I O; Ferreira, E H Martins; Peripolli, S B; Damasceno, J C; Achete, C A; Jorio, A

    2011-07-01

    This work reports Ga(+) focused ion beam nanopatterning to create amorphous defects with periodic square arrays in highly oriented pyrolytic graphite and the use of Raman spectroscopy as a new protocol to test and compare progresses in ion beam optics, for low fluence bombardment or fast writing speed. This can be ultimately used as a metrological tool for comparing different FIB machines and can contribute to Focused Ion Beam (FIB) development in general for tailoring nanostructures with higher precision. In order to do that, the amount of ion at each spot was varied from about 10(6) down to roughly 1 ion per dot. These defects were also analyzed by using high resolution scanning electron microscopy and atomic force microscopy. The sensitivities of these techniques were compared and a geometrical model is proposed for micro-Raman spectroscopy in which the intensity of the defect induced D band, for a fixed ion dose, is associated with the diameter of the ion beam. In addition, the lateral increase in the bombarded spot due to the cascade effect of the ions on graphite surface was extracted from this model. A semi-quantitative analysis of the distribution of ions at low doses per dot or high writing speed for soft modification of materials is discussed.

  17. Broadband performance of a piezoelectric energy harvester based on the internal resonance of buckled beam

    NASA Astrophysics Data System (ADS)

    Xiong, Liuyang; Tang, Lihua; Ding, Hu; Chen, Liqun; Mace, Brian

    2016-04-01

    Nonlinear internal resonance mechanism is exploited in piezoelectric vibration energy harvesting (PVEH) for the purpose of broadening the resonance band. Conventional linear energy harvester has narrow operating bandwidth. In this research, a buckled piezoelectric beam structure with preload under transverse excitation is investigated to demonstrate the superiority of internal resonance. The condition for 2:1 internal resonance could be established by truncating the continuum beam with geometrical nonlinearity. Integro-partial-differential equations are derived for governing transverse motion measured from a stable equilibrium position. At specific initial axial compressive force, two modes are coupled through the internal resonance interaction. For weak nonlinear perturbations, multiple scales method is used to explore the amplitude-frequency responses of the buckled beam system under primary resonance with 2:1 internal resonance. Numerical examples demonstrate that the resonance bandwidth is broadened thanks to the coexistence of softening and hardening nonlinear characteristics. Moreover, validity of the approximate analytical method is demonstrated by comparing with simulation. Furthermore, the optimal resistance is discussed with a pure resistive load. This research on the internal resonance of buckled beam provides a basis for structure design and optimization in broadband PVEH.

  18. The design, construction and performance of a variable collimator for epithermal neutron capture therapy beams.

    PubMed

    Riley, K J; Binns, P J; Ali, S J; Harling, O K

    2004-05-21

    A patient collimator for the fission converter based epithermal neutron beam (FCB) at the Massachusetts Institute of Technology Research Reactor (MITR-II) was built for clinical trials of boron neutron capture therapy (BNCT). A design was optimized by Monte Carlo simulations of the entire beam line and incorporates a modular construction for easy modifications in the future. The device was formed in-house by casting a mixture of lead spheres (7.6 mm diameter) in epoxy resin loaded with either 140 mg cm(-3) of boron carbide or 210 mg cm(-3) of lithium fluoride (95% enriched in 6Li). The cone shaped collimator allows easy field placement anywhere on the patient and is equipped with a laser indicator of central axis, beam's eye view optics and circular apertures of 80, 100, 120 and 160 mm diameter. Beam profiles and the collateral dose in a half-body phantom were measured for the 160 mm field using fission counters, activation foils as well as tissue equivalent (A-150) and graphite walled ionization chambers. Leakage radiation through the collimator contributes less than 10% to the total collateral dose up to 0.15 m beyond the edge of the aperture and becomes relatively more prominent with lateral displacement. The measured whole body dose equivalent of 24 +/- 2 mSv per Gy of therapeutic dose is comparable to doses received during conventional therapy and is due principally (60-80%) to thermal neutron capture reactions with boron. These findings, together with the dose distributions for the primary beam, demonstrate the suitability of this patient collimator for BNCT.

  19. Electrochemical Performance of Glucose/Oxygen Biofuel Cells Based on Carbon Nanostructures.

    PubMed

    Koo, Min-Hye; Das, Gautam; Yoon, Hyon Hee

    2016-03-01

    The electrochemical performance of glucose/oxygen biofuel cells based on carbon nanostructures was investigated in the present study. Different types of carbon nanomaterials, including multi-walled carbon nanotubes (MWCNT), functionalized MWCNT (f-MWCNT), carbon nanofibers (CNF), and functionalized CNF (f-CNF) were examined for electrode fabrications. The anode for glucose/oxygen biofuel cells were prepared by sequential coating of carbon nanomaterials, charge transfer complex (CTC), glucose oxidase (GOx) and nafion membrane. The anode was then integrated with a bilirubin oxidase-immobilized cathode for the biofuel cell test. It was found that the electrochemical performance of the enzyme electrodes was remarkably enhanced by the amalgamation of carbon nanomaterials with the CTC. The biofuel cell with anode comprising of f-CNF and the cathode with MWCNT exhibited the best electrochemical performance with a maximum power density of 210 μW/cm2 at a cell voltage of 0.44 V for 20 mM glucose concentration, which is comparable with the best power density value reported earlier. PMID:27455759

  20. Electrochemical Performance of Glucose/Oxygen Biofuel Cells Based on Carbon Nanostructures.

    PubMed

    Koo, Min-Hye; Das, Gautam; Yoon, Hyon Hee

    2016-03-01

    The electrochemical performance of glucose/oxygen biofuel cells based on carbon nanostructures was investigated in the present study. Different types of carbon nanomaterials, including multi-walled carbon nanotubes (MWCNT), functionalized MWCNT (f-MWCNT), carbon nanofibers (CNF), and functionalized CNF (f-CNF) were examined for electrode fabrications. The anode for glucose/oxygen biofuel cells were prepared by sequential coating of carbon nanomaterials, charge transfer complex (CTC), glucose oxidase (GOx) and nafion membrane. The anode was then integrated with a bilirubin oxidase-immobilized cathode for the biofuel cell test. It was found that the electrochemical performance of the enzyme electrodes was remarkably enhanced by the amalgamation of carbon nanomaterials with the CTC. The biofuel cell with anode comprising of f-CNF and the cathode with MWCNT exhibited the best electrochemical performance with a maximum power density of 210 μW/cm2 at a cell voltage of 0.44 V for 20 mM glucose concentration, which is comparable with the best power density value reported earlier.

  1. Phthalonitrile-Based Carbon Foam with High Specific Mechanical Strength and Superior Electromagnetic Interference Shielding Performance.

    PubMed

    Zhang, Liying; Liu, Ming; Roy, Sunanda; Chu, Eng Kee; See, Kye Yak; Hu, Xiao

    2016-03-23

    Electromagnetic interference (EMI) performance materials are urgently needed to relieve the increasing stress over electromagnetic pollution problems arising from the growing demand for electronic and electrical devices. In this work, a novel ultralight (0.15 g/cm(3)) carbon foam was prepared by direct carbonization of phthalonitrile (PN)-based polymer foam aiming to simultaneously achieve high EMI shielding effectiveness (SE) and deliver effective weight reduction without detrimental reduction of the mechanical properties. The carbon foam prepared by this method had specific compressive strength of ∼6.0 MPa·cm(3)/g. High EMI SE of ∼51.2 dB was achieved, contributed by its intrinsic nitrogen-containing structure (3.3 wt% of nitrogen atoms). The primary EMI shielding mechanism of such carbon foam was determined to be absorption. Moreover, the carbon foams showed excellent specific EMI SE of 341.1 dB·cm(3)/g, which was at least 2 times higher than most of the reported material. The remarkable EMI shielding performance combined with high specific compressive strength indicated that the carbon foam could be considered as a low-density and high-performance EMI shielding material for use in areas where mechanical integrity is desired.

  2. Effect of mission cycling on the fatigue performance of SiC-coated carbon-carbon composites

    NASA Technical Reports Server (NTRS)

    Mahfuz, H.; Das, P. S.; Jeelani, S.; Baker, D. M.; Johnson, S. A.

    1993-01-01

    The effects of thermal and pressure cycling on the fatigue performance of carbon-carbon composites, and the influence of mission cycling on these effects, were investigated by subjecting both virgin and mission-cycled two-dimensional specimens of SiC-coated carbon-carbon composites to fatigue tests, conducted at room temperature in three-point bending, with a stress ratio of 0.2 and a frequency of 1 Hz. It was found that the fatigue strength of C-C composites is high (about 90 percent of the ultimate flexural strength), but decreased with the mission cycling. The lowering of the fatigue strength with mission cycling is attributed to the increase in interfacial bond strength due to thermal and pressure cycling of the material. The already high sensitivity of C-C composites to stress during cyclic loading increases further with the amount of mission cycling. Results of NDE suggest that the damage growth in virgin C-C, in the high-cycle range, is slow at the initial stage of the cyclic life, but propagates rapidly after certain threshold cycles of the fatigue life.

  3. Modeling the Effects of Beam Size and Flaw Morphology on Ultrasonic Pulse/Echo Sizing of Delaminations in Carbon Composites

    NASA Technical Reports Server (NTRS)

    Margetan, Frank J.; Leckey, Cara A.; Barnard, Dan

    2012-01-01

    The size and shape of a delamination in a multi-layered structure can be estimated in various ways from an ultrasonic pulse/echo image. For example the -6dB contours of measured response provide one simple estimate of the boundary. More sophisticated approaches can be imagined where one adjusts the proposed boundary to bring measured and predicted UT images into optimal agreement. Such approaches require suitable models of the inspection process. In this paper we explore issues pertaining to model-based size estimation for delaminations in carbon fiber reinforced laminates. In particular we consider the influence on sizing when the delamination is non-planar or partially transmitting in certain regions. Two models for predicting broadband sonic time-domain responses are considered: (1) a fast "simple" model using paraxial beam expansions and Kirchhoff and phase-screen approximations; and (2) the more exact (but computationally intensive) 3D elastodynamic finite integration technique (EFIT). Model-to-model and model-to experiment comparisons are made for delaminations in uniaxial composite plates, and the simple model is then used to critique the -6dB rule for delamination sizing.

  4. Search for charged current coherent pion production on carbon in a few-GeV neutrino beam

    NASA Astrophysics Data System (ADS)

    Hiraide, K.; Alcaraz-Aunion, J. L.; Brice, S. J.; Bugel, L.; Catala-Perez, J.; Cheng, G.; Conrad, J. M.; Djurcic, Z.; Dore, U.; Finley, D. A.; Franke, A. J.; Giganti, C.; Gomez-Cadenas, J. J.; Guzowski, P.; Hanson, A.; Hayato, Y.; Jover-Manas, G.; Karagiorgi, G.; Katori, T.; Kobayashi, Y. K.; Kobilarcik, T.; Kubo, H.; Kurimoto, Y.; Louis, W. C.; Loverre, P. F.; Ludovici, L.; Mahn, K. B. M.; Mariani, C.; Masuike, S.; Matsuoka, K.; Metcalf, W.; Mills, G.; Mitsuka, G.; Miyachi, Y.; Mizugashira, S.; Moore, C. D.; Nakajima, Y.; Nakaya, T.; Napora, R.; Nienaber, P.; Nguyen, V.; Orme, D.; Otani, M.; Russell, A. D.; Sanchez, F.; Shaevitz, M. H.; Shibata, T.-A.; Sorel, M.; Stefanski, R. J.; Takei, H.; Tanaka, H.-K.; Tanaka, M.; Tayloe, R.; Taylor, I. J.; Tesarek, R. J.; Uchida, Y.; van de Water, R.; Walding, J. J.; Wascko, M. O.; White, H.; Wilking, M. J.; Yokoyama, M.; Zeller, G. P.; Zimmerman, E. D.

    2008-12-01

    The SciBooNE Collaboration has performed a search for charged current coherent pion production from muon neutrinos scattering on carbon, νμC12→μ-C12π+, with two distinct data samples. No evidence for coherent pion production is observed. We set 90% confidence level upper limits on the cross section ratio of charged current coherent pion production to the total charged current cross section at 0.67×10-2 at mean neutrino energy 1.1 GeV and 1.36×10-2 at mean neutrino energy 2.2 GeV.

  5. Impact of gas products around the anode on the performance of a direct carbon fuel cell using a carbon/carbonate slurry

    NASA Astrophysics Data System (ADS)

    Watanabe, Hirotatsu; Umehara, Daisuke; Hanamura, Katsunori

    2016-10-01

    This paper investigates the impact of gas products around the anode on cell performance via an in situ observation. In a direct carbon fuel cell used this study, the anode is inserted into the carbon/carbonate slurry. The current-voltage (I-V) curves are measured before and after a long discharge in the constant current discharge mode. An in situ observation shows that the anode is almost completely covered by gas bubbles when the voltage becomes nearly 0 V in the constant current discharge at 40 mA/cm2; this indicates that gas products such as CO2 prevent the carbon particles and ions from reaching the anode. Meanwhile, the long discharge at 20 mA/cm2 is achieved for 30 min, even though the anode is covered by the CO2 bubbles at 15 min. The I-V curves at 1 min after the termination of the long discharge at 20 mA/cm2 are lower than those prior to the long discharge. The overpotential significantly increases at higher current densities, where mass transport becomes the limiting process. The cell performance is significantly influenced by the gas products around the anode.

  6. Performance of alumina-supported Pt catalysts in an electron-beam-sustained CO2 laser amplifier

    NASA Technical Reports Server (NTRS)

    Cunningham, D. L.; Jones, P. L.; Miyake, C. I.; Moody, S. E.

    1990-01-01

    The performance of an alumina-supported Pt catalyst system used to maintain the gas purity in an electron-beam-sustained (636) isotope CO2 laser amplifier has been tested. The system characteristics using the two-zone, parallel flow reactor were determined for both continuous- and end-of-day reactor operation using on-line mass spectrometric sampling. The laser amplifier was run with an energy loading of typically 110 J-l/atm and an electron-beam current of 4 mA/sq cm. With these conditions and a pulse repetition frequency of 10 Hz for up to 10,000 shots, increases on the order of 100 ppm O2 were observed with the purifier on and 150 ppm with it off. The 1/e time recovery time was found to be approximately 75 minutes.

  7. Computational modelling of a non-viscous fluid flow in a multi-walled carbon nanotube modelled as a Timoshenko beam.

    PubMed

    Khosravian, N; Rafii-Tabar, H

    2008-07-01

    In the design of nanotube-based fluidic devices, a critical issue is the effect of the induced vibrations in the nanotube arising from the fluid flow, since these vibrations can promote structural instabilities, such as buckling transitions. It is known that the induced resonant frequencies depend on the fluid flow velocity in a significant manner. We have studied, for the first time, the flow of a non-viscous fluid in stubby multi-walled carbon nanotubes, using the Timoshenko classical beam theory to model the nanotubes as a continuum structure. We have obtained the variations of the resonant frequencies with the fluid flow velocity under several experimentally interesting boundary conditions and aspect ratios of the nanotube. The main finding from our work is that, compared to an Euler-Bernoulli classical beam model of a nanotube, the Timoshenko beam predicts the loss of stability at lower fluid flow velocities. PMID:21828715

  8. The Influence of Hollow Imperfections of Adhesive on Performances of Interface of RC Beams Strengthened with HFRP

    SciTech Connect

    Guo Yongchang; Li Lijuan; Deng Jun; Zhong Genquan

    2010-05-21

    The mechanical characteristics of the interface with hollow imperfections for reinforced concrete (RC) beams strengthened with Carbon-Glass fiber sheet is discussed, which is a new hybrid strengthening method. By establishing the constitutive equations of different materials, three interfacial models including imperfection dimension, imperfection location and imperfection amount are simulated using nonlinear finite element method. The shear stress and normal stress of glue layer, the first principal stress of concrete at the end of the interface and the stress distributions of different strengthening modes are analyzed. The results show that the shear stress of glue layer is sensitive for imperfection dimension and significantly increases with the imperfection dimension. However, the first principal stress of the concrete at the end of the interface marginally decreases with the imperfection dimension.

  9. Carbon emissions performance of commercial logging in East Kalimantan, Indonesia.

    PubMed

    Griscom, Bronson; Ellis, Peter; Putz, Francis E

    2014-03-01

    Adoption of reduced-impact logging (RIL) methods could reduce CO2 emissions by 30-50% across at least 20% of remaining tropical forests. We developed two cost effective and robust indices for comparing the climate benefits (reduced CO2 emissions) due to RIL. The indices correct for variability in the volume of commercial timber among concessions. We determined that a correction for variability in terrain slope was not needed. We found that concessions certified by the Forest Stewardship Council (FSC, N = 3), when compared with noncertified concessions (N = 6), did not have lower overall CO2 emissions from logging activity (felling, skidding, and hauling). On the other hand, FSC certified concessions did have lower emissions from one type of logging impact (skidding), and we found evidence of a range of improved practices using other field metrics. One explanation of these results may be that FSC criteria and indicators, and associated RIL practices, were not designed to achieve overall emissions reductions. Also, commonly used field metrics are not reliable proxies for overall logging emissions performance. Furthermore, the simple distinction between certified and noncertified concessions does not fully represent the complex history of investments in improved logging practices. To clarify the relationship between RIL and emissions reductions, we propose the more explicit term 'RIL-C' to refer to the subset of RIL practices that can be defined by quantified thresholds and that result in measurable emissions reductions. If tropical forest certification is to be linked with CO2 emissions reductions, certification standards need to explicitly require RIL-C practices.

  10. Contrast Enhancement of the LOASIS CPA Laser and Effects on Electron Beam Performance of LWFA

    SciTech Connect

    Toth, Csaba; Gonsalves, Anthony J.; Panasenko, Dmitriy; Matlis, Nicholas H.; Leemans, Wim P.; Albert, Olivier; Canova, Lorenzo; Plateau, Guillaume

    2009-01-22

    A nonlinear optical pulse cleaning technique based on cross-polarized wave (XPW) generation filtering [1] has been implemented to improve laser pulse contrast, and consequently to control pre-ionization in laser-plasma accelerator experiments. Three orders of magnitude improvement in pre-pulse contrast has been achieved, resulting in 4-fold increase in electron charge and improved stability of both the electron beam energy and THz radiation generated as a secondary process in the gas-jet-based LWFA experiments.

  11. Contrast Enhancement of the LOASIS CPA Laser and Effects on Electron Beam Performance of LWFA

    NASA Astrophysics Data System (ADS)

    Tóth, Csaba; Albert, Olivier; Canova, Lorenzo; Gonsalves, Anthony J.; Panasenko, Dmitriy; Matlis, Nicholas H.; Plateau, Guillaume; Leemans, Wim P.

    2009-01-01

    A nonlinear optical pulse cleaning technique based on cross-polarized wave (XPW) generation filtering [1] has been implemented to improve laser pulse contrast, and consequently to control pre-ionization in laser-plasma accelerator experiments. Three orders of magnitude improvement in pre-pulse contrast has been achieved, resulting in 4-fold increase in electron charge and improved stability of both the electron beam energy and THz radiation generated as a secondary process in the gas-jet-based LWFA experiments.

  12. Polarized Positive and Negative Muon Beams to perform DVCS Measurements at COMPASS

    SciTech Connect

    D'Hose, Nicole

    2009-09-02

    The high energies available at CERN, and the option of using either positive or negative polarized muon beams, make the fixed-target COMPASS set-up a unique place for studying GPDs, through Deeply Virtual Compton Scattering (DVCS). A GPD program is part of the Medium and Long Term Plans at COMPASS [1]. This contribution presents the methodology and the goal of such experiments.

  13. Integrative characterization of the thermoelectric performance of an individual multiwalled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Miao, Tingting; Shi, Shaoyi; Yan, Shen; Ma, Weigang; Zhang, Xing; Takahashi, Koji; Ikuta, Tatsuya

    2016-09-01

    Carbon nanotube-based organic composites and carbon nanotube networks are important flexible and lightweight thermoelectric materials. Characterization of the thermoelectric performance of individual carbon nanotubes is of vital importance for exploring the coupling mechanism between carbon nanotubes and organic composites, and proposing further improvement measures. The thermoelectric performance of an individual multiwalled carbon nanotube with a diameter of 66 nm has been comprehensively studied by applying our T-type method from 260 K to 420 K, using the same measurement configuration. The figure of merit increases from 4.84 × 10-8 to 1.32 × 10-6 on increasing the temperature, which is smaller than previous experimental results on carbon nanotube samples. The thermal conductivity increases from 706 W m-1 K-1 at 260 K to 769.3 W m-1 K-1 at 320 K, and then stays nearly constant until 420 K. The phonons dominate the thermal transport. The electrical conductivity exhibits thermally activated carrier generation and transport with an energy barrier of 194.5 meV. The Seebeck coefficient is in the range of 29.4-41.0 μV K-1 and tends to decrease with temperature.

  14. Promising porous carbon derived from celtuce leaves with outstanding supercapacitance and CO₂ capture performance.

    PubMed

    Wang, Rutao; Wang, Peiyu; Yan, Xingbin; Lang, Junwei; Peng, Chao; Xue, Qunji

    2012-11-01

    Business costs and energy/environmental concerns have increased interested in biomass materials for production of activated carbons, especially as electrode materials for supercapacitors or as solid-state adsorbents in CO₂ adsorption area. In this paper, waste celtuce leaves were used to prepare porous carbon by air-drying, pyrolysis at 600 °C in argon, followed by KOH activation. The as-prepared porous carbon have a very high specific surface area of 3404 m²/g and a large pore volume of 1.88 cm³/g. As an electroactive material, the porous carbon exhibits good capacitive performance in KOH aqueous electrolyte, with the specific capacitances of 421 and 273 F/g in three and two-electrode systems, respectively. As a solid-state adsorbent, the porous carbon has an excellent CO₂ adsorption capacity at ambient pressures of up to 6.04 and 4.36 mmol/g at 0 and 25 °C, respectively. With simple production process, excellent recyclability and regeneration stability, the porous carbon that was derived from celtuce leaves is among the most promising materials for high-performance supercapacitors and CO₂ capture.

  15. Performance evaluation for carbonation of steel-making slags in a slurry reactor.

    PubMed

    Chang, E-E; Chen, Chung-Hua; Chen, Yi-Hung; Pan, Shu-Yuan; Chiang, Pen-Chi

    2011-02-15

    CO(2) sequestration by the aqueous carbonation of steel-making slag under various operational conditions was investigated in this study. The effects of the operational conditions, including type of steel-making slag, reaction time, reaction temperature, and CO(2) flow rate, on the performance of the carbonation process were evaluated. The results indicated that the BOF slag had the highest carbonation conversion, approximately 72%, at a reaction time of 1h, an operating pressure of 101 kPa and a temperature of 60°C due to its higher BET surface area of BOF slag compared to UF, FA, and BHC slags. The major factors affecting the carbonation conversion are reaction time and temperature. The reaction kinetics of the carbonation conversion can be expressed by the shrinking-core model. The measurements of the carbonated material by the SEM and XRD instruments provide evidence indicating the suitability of using the shrinking-core model in this investigation. Comparison of the results with other studies suggests that aqueous carbonation by slurry reactor is viable due to its higher mass transfer rate.

  16. Preparation of cribriform sheet-like carbon-coated zinc oxide with improved electrochemical performance

    NASA Astrophysics Data System (ADS)

    Huang, Jianhang; Yang, Zhanhong; Xie, Xiaoe; Feng, Zhaobin; Zhang, Zheng

    2015-09-01

    Cribriform sheet-like carbon-coated ZnO are prepared using pyrrole as the carbon source. It is found that a sheet-like precursor will form when polymerizing pyrrole in the presence of ZnO particles. After the carbonization of precursor, cribriform sheet-like carbon-coated ZnO can be obtained. Morphology and structure analysis of as-prepared carbon-coated ZnO is conducted by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The carbon overlayer not only present a barrier layer on the surface of the ZnO particles, which keeps relative high discharge capacity by inhibiting the active materials in electrode from dissolving into electrolyte, but also modify the surface status of ZnO particles so as to obtain more uniform current distribution and improved conductivity. As a result, when evaluated as an anode material for Zn/Ni cell, carbon-coated ZnO exhibit a more stable cycle performance than bare ZnO electrode.

  17. Carbon-ion beams effectively induce growth inhibition and apoptosis in human neural stem cells compared with glioblastoma A172 cells

    PubMed Central

    Isono, Mayu; Yoshida, Yukari; Takahashi, Akihisa; Oike, Takahiro; Shibata, Atsushi; Kubota, Yoshiki; Kanai, Tatsuaki; Ohno, Tatsuya; Nakano, Takashi

    2015-01-01

    Carbon-ion radiotherapy (CIRT) holds promise in the treatment of glioblastoma, an aggressive X-ray–resistant brain tumor. However, since glioblastoma cells show a highly invasive nature, carbon-ion (C-ion) irradiation of normal tissues surrounding the tumor is inevitable. Recent studies have revealed the existence of neural stem cells in the adult brain. Therefore, the damaging effect of C-ion beams on the neural stem cells has to be carefully considered in the treatment planning of CIRT. Here, we investigated the growth and death mode of human neural stem cells (hNSCs) and glioblastoma A172 cells after X-ray or C-ion beam irradiation. The X-ray dose resulting in a 50% growth rate (D50) was 0.8 Gy in hNSCs and 3.0 Gy in A172 cells, while the D50 for C-ion beams was 0.4 Gy in hNSCs and 1.6 Gy in A172 cells; the relative biological effectiveness value of C-ion beams was 2.0 in hNSCs and 1.9 in A172 cells. Importantly, both X-rays and C-ion beams preferentially induced apoptosis, not necrosis, in hNSCs; however, radiation-induced apoptosis was less evident in A172 cells. The apoptosis-susceptible nature of the irradiated hNSCs was associated with prolonged upregulation of phosphorylated p53, whereas the apoptosis-resistant nature of A172 cells was associated with a high basal level of nuclear factor kappa B expression. Taken together, these data indicate that apoptosis is the major cell death pathway in hNSCs after irradiation. The high sensitivity of hNSCs to C-ion beams underscores the importance of careful target volume delineation in the treatment planning of CIRT for glioblastoma. PMID:26070322

  18. High-Performance Sorbents for Carbon Dioxide Capture from Air

    SciTech Connect

    Sholl, David; Jones, Christopher

    2013-03-13

    This project has focused on capture of CO{sub 2} from ambient air (“air capture”). If this process is technically and economically feasible, it could potentially contribute to net reduction of CO{sub 2} emissions in ways that are complementary to better developed techniques for CO{sub 2} from concentrated point sources. We focused on cyclic adsorption processes for CO{sub 2} capture from air in which the entire cycle is performed at moderate temperatures. The project involved both experimental studies of sorbent materials and process level modeling of cyclic air capture processes. In our experimental work, a series of amine-functionalized silica adsorbents were prepared and characterized to determine the impact of molecular architecture on CO{sub 2} capture. Some key findings were: • Amine functionalized silicas can be prepared with high enough CO{sub 2} capacities under ambient conditions to merit consideration for use in air capture processes. • Primary amines are better candidates for CO{sub 2} capture than secondary or tertiary amines, both in terms of amine efficiency for CO{sub 2} adsorption and enhanced water affinity. • Mechanistic understanding of degradation of these materials can enable control of molecular architecture to significantly improve material stability. Our process modeling work provided the first publically available cost and energy estimates for cyclic adsorption processes for air capture of CO{sub 2}. Some key findings were: • Cycles based on diurnal ambient heating and cooling cannot yield useful purities or amounts of captured CO{sub 2}. • Cycles based on steam desorption at 110 oC can yield CO{sub 2} purities of ~88%. • The energy requirements for cycles using steam desorption are dominated by needs for thermal input, which results in lower costs than energy input in the form of electricity. Cyclic processes with operational costs of less than $100 tCO{sub 2}-net were described, and these results point to process and

  19. Performance of Spent Mushroom Farming Waste (SMFW) Activated Carbon for Ni (II) Removal

    NASA Astrophysics Data System (ADS)

    Desa, N. S. Md; Ghani, Z. Ab; Talib, S. Abdul; Tay, C. C.

    2016-07-01

    The feasibility of a low cost agricultural waste of spent mushroom farming waste (SMFW) activated carbon for Ni(II) removal was investigated. The batch adsorption experiments of adsorbent dosage, pH, contact time, metal concentration, and temperature were determined. The samples were shaken at 125 rpm, filtered and analyzed using ICP-OES. The fifty percent of Ni(II) removal was obtained at 0.63 g of adsorbent dosage, pH 5-6 (unadjusted), 60 min contact time, 50 mg/L Ni(II) concentration and 25 °C temperature. The evaluated SMFW activated carbon showed the highest performance on Ni(II) removal compared to commercial Amberlite IRC86 resin and zeolite NK3. The result indicated that SMFW activated carbon is a high potential cation exchange adsorbent and suitable for adsorption process for metal removal. The obtained results contribute toward application of developed SMFW activated carbon in industrial pilot study.

  20. Improvement of spread-out Bragg peak flatness for a carbon-ion beam by the use of a ridge filter with a ripple filter.

    PubMed

    Hara, Yousuke; Takada, Yoshihisa; Hotta, Kenji; Tansho, Ryohei; Nihei, Tetsuya; Suzuki, Yojiro; Nagafuchi, Kosuke; Kawai, Ryuichi; Tanabe, Masaki; Mizutani, Shohei; Himukai, Takeshi; Matsufuji, Naruhiro

    2012-03-21

    We have developed a novel design method of ridge filters for carbon-ion therapy using a broad-beam delivery system to improve the flatness of a biologically effective dose in the spread-out Bragg peak (SOBP). So far, the flatness of the SOBP is limited to about ±5% for carbon beams since the weight control of component Bragg curves composing the SOBP is difficult. This difficulty arises from using a large number of ridge-bar steps (e.g. about 100 for a SOBP width of 60 mm) required to form the SOBP for the pristine Bragg curve with an extremely sharp distal falloff. Instead of using a single ridge filter, we introduce a ripple filter to broaden the Bragg peak so that the number of ridge-bar steps can be reduced to about 30 for SOBP with of 60 mm for the ridge filter designed for the broadened Bragg peak. Thus we can manufacture the ridge filter more accurately and then attain a better flatness of the SOBP due to well-controlled weights of the component Bragg curves. We placed the ripple filter on the same frame of the ridge filter and arranged the direction of the ripple-filter-bar array perpendicular to that of the ridge-filter-bar array. We applied this method to a 290 MeV u(-1) carbon-ion beam in Heavy Ion Medical Accelerator in Chiba and verified the effectiveness by measurements.

  1. Characterization and performance evaluation of an innovative mesoporous activated carbon used for drinking water purification in comparison with commercial carbons.

    PubMed

    Gong, Xu-Jin; Li, Wei-Guang; Wang, Guang-Zhi; Zhang, Duo-Ying; Fan, Wen-Biao; Yin, Zhao-Dong

    2015-09-01

    The preparation, characterization, and performance evaluation of an innovative mesoporous activated carbon (C-XHIT) were conducted in this study. Comparative evaluation with commercial carbons (C-PS and C-ZJ15) and long-term performance evaluation of C-XHIT were conducted in small-scale system-A (S-A) and pilot-scale system-B (S-B-1 and S-B-2 in series), respectively, for treating water from Songhua River. The cumulative uptake of micropollutants varied with KBV (water volume fed to columns divided by the mass of carbons, m(3) H2O/kg carbon) was employed in the performance evaluation. The results identified that mesoporous and microporous volumes were simultaneously well-developed in C-XHIT. Higher mesoporosity (63.94 %) and average pore width (37.91 Å) of C-XHIT ensured a higher adsorption capacity for humic acid compared to C-PS and C-ZJ15. When the KBV of S-A reached 12.58 m(3) H2O/kg carbon, cumulative uptake of organic pollutants achieved by C-XHIT increased by 32.82 and 156.29 % for DOC (QC) and 22.53 and 112.48 % for UV254 (QUV) compared to C-PS and C-ZJ15, respectively; in contrast, the adsorption capacity of NH4 (+)-N did not improve significantly. C-XHIT achieved high average removal efficiencies for DOC (77.43 ± 16.54 %) and UV254 (83.18 ± 13.88 %) in S-B over 253 days of operation (KBV = 62 m(3) H2O/kg carbon). Adsorption dominated the removal of DOC and UV254 in the initial phases of KBV (0-15 m(3) H2O/kg carbon), and simultaneous biodegradation and adsorption were identified as the mechanisms for organic pollutant uptake at KBV above 25 m(3) H2O/kg carbon. The average rates contributed by S-B-1 and S-B-2 for QC and QUV were approximately 0.75 and 0.25, respectively. Good linear and exponential correlations were observed between S-A and S-B in terms of QC and QUV obtained by C-XHIT, respectively, for the same KBV ranges, indicating a rapid and cost-saving evaluation method. The linear correlation between mesoporosity and QC

  2. Characterization and performance evaluation of an innovative mesoporous activated carbon used for drinking water purification in comparison with commercial carbons.

    PubMed

    Gong, Xu-Jin; Li, Wei-Guang; Wang, Guang-Zhi; Zhang, Duo-Ying; Fan, Wen-Biao; Yin, Zhao-Dong

    2015-09-01

    The preparation, characterization, and performance evaluation of an innovative mesoporous activated carbon (C-XHIT) were conducted in this study. Comparative evaluation with commercial carbons (C-PS and C-ZJ15) and long-term performance evaluation of C-XHIT were conducted in small-scale system-A (S-A) and pilot-scale system-B (S-B-1 and S-B-2 in series), respectively, for treating water from Songhua River. The cumulative uptake of micropollutants varied with KBV (water volume fed to columns divided by the mass of carbons, m(3) H2O/kg carbon) was employed in the performance evaluation. The results identified that mesoporous and microporous volumes were simultaneously well-developed in C-XHIT. Higher mesoporosity (63.94 %) and average pore width (37.91 Å) of C-XHIT ensured a higher adsorption capacity for humic acid compared to C-PS and C-ZJ15. When the KBV of S-A reached 12.58 m(3) H2O/kg carbon, cumulative uptake of organic pollutants achieved by C-XHIT increased by 32.82 and 156.29 % for DOC (QC) and 22.53 and 112.48 % for UV254 (QUV) compared to C-PS and C-ZJ15, respectively; in contrast, the adsorption capacity of NH4 (+)-N did not improve significantly. C-XHIT achieved high average removal efficiencies for DOC (77.43 ± 16.54 %) and UV254 (83.18 ± 13.88 %) in S-B over 253 days of operation (KBV = 62 m(3) H2O/kg carbon). Adsorption dominated the removal of DOC and UV254 in the initial phases of KBV (0-15 m(3) H2O/kg carbon), and simultaneous biodegradation and adsorption were identified as the mechanisms for organic pollutant uptake at KBV above 25 m(3) H2O/kg carbon. The average rates contributed by S-B-1 and S-B-2 for QC and QUV were approximately 0.75 and 0.25, respectively. Good linear and exponential correlations were observed between S-A and S-B in terms of QC and QUV obtained by C-XHIT, respectively, for the same KBV ranges, indicating a rapid and cost-saving evaluation method. The linear correlation between mesoporosity and QC

  3. High nitrogen-containing cotton derived 3D porous carbon frameworks for high-performance supercapacitors

    PubMed Central

    Fan, Li-Zhen; Chen, Tian-Tian; Song, Wei-Li; Li, Xiaogang; Zhang, Shichao

    2015-01-01

    Supercapacitors fabricated by 3D porous carbon frameworks, such as graphene- and carbon nanotube (CNT)-based aerogels, have been highly attractive due to their various advantages. However, their high cost along with insufficient yield has inhibited their large-scale applications. Here we have demonstrated a facile and easily scalable approach for large-scale preparing novel 3D nitrogen-containing porous carbon frameworks using ultralow-cost commercial cotton. Electrochemical performance suggests that the optimal nitrogen-containing cotton-derived carbon frameworks with a high nitrogen content (12.1 mol%) along with low surface area 285 m2 g−1 present high specific capacities of the 308 and 200 F g−1 in KOH electrolyte at current densities of 0.1 and 10 A g−1, respectively, with very limited capacitance loss upon 10,000 cycles in both aqueous and gel electrolytes. Moreover, the electrode exhibits the highest capacitance up to 220 F g−1 at 0.1 A g−1 and excellent flexibility (with negligible capacitance loss under different bending angles) in the polyvinyl alcohol/KOH gel electrolyte. The observed excellent performance competes well with that found in the electrodes of similar 3D frameworks formed by graphene or CNTs. Therefore, the ultralow-cost and simply strategy here demonstrates great potential for scalable producing high-performance carbon-based supercapacitors in the industry. PMID:26472144

  4. Discrete carbon nanotubes increase lead acid battery charge acceptance and performance

    NASA Astrophysics Data System (ADS)

    Swogger, Steven W.; Everill, Paul; Dubey, D. P.; Sugumaran, Nanjan

    2014-09-01

    Performance demands placed upon lead acid batteries have outgrown the technology's ability to deliver. These demands, typically leading to Negative Active Material (NAM) failure, include: short, high-current surges; prolonged, minimal, overvoltage charging; repeated, Ah deficit charging; and frequent deep discharges. Research shows these failure mechanisms are attenuated by inclusion of carbon allotropes into the NAM. Addition of significant quantities of carbon, however, produces detrimental changes in paste rheology, leading to lowered industrial throughput. Additionally, capacity, cold-cranking performance, and other battery metrics are negatively affected at high carbon loads. Presented here is Molecular Rebar® Lead Negative, a new battery additive comprising discrete carbon nanotubes (dCNT) which uniformly disperse within battery pastes during mixing. NS40ZL batteries containing dCNT show enhanced charge acceptance, reserve capacity, and cold-cranking performance, decreased risk of polarization, and no detrimental changes to paste properties, when compared to dCNT-free controls. This work focuses on the dCNT as NAM additives only, but early-stage research is underway to test their functionality as a PAM additive. Batteries infused with Molecular Rebar® Lead Negative address the needs of modern lead acid battery applications, produce none of the detrimental side effects associated with carbon additives, and require no change to existing production lines.

  5. High nitrogen-containing cotton derived 3D porous carbon frameworks for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Fan, Li-Zhen; Chen, Tian-Tian; Song, Wei-Li; Li, Xiaogang; Zhang, Shichao

    2015-10-01

    Supercapacitors fabricated by 3D porous carbon frameworks, such as graphene- and carbon nanotube (CNT)-based aerogels, have been highly attractive due to their various advantages. However, their high cost along with insufficient yield has inhibited their large-scale applications. Here we have demonstrated a facile and easily scalable approach for large-scale preparing novel 3D nitrogen-containing porous carbon frameworks using ultralow-cost commercial cotton. Electrochemical performance suggests that the optimal nitrogen-containing cotton-derived carbon frameworks with a high nitrogen content (12.1 mol%) along with low surface area 285 m2 g-1 present high specific capacities of the 308 and 200 F g-1 in KOH electrolyte at current densities of 0.1 and 10 A g-1, respectively, with very limited capacitance loss upon 10,000 cycles in both aqueous and gel electrolytes. Moreover, the electrode exhibits the highest capacitance up to 220 F g-1 at 0.1 A g-1 and excellent flexibility (with negligible capacitance loss under different bending angles) in the polyvinyl alcohol/KOH gel electrolyte. The observed excellent performance competes well with that found in the electrodes of similar 3D frameworks formed by graphene or CNTs. Therefore, the ultralow-cost and simply strategy here demonstrates great potential for scalable producing high-performance carbon-based supercapacitors in the industry.

  6. Control performance and biomembrane disturbance of carbon nanotube artificial water channels by nitrogen-doping.

    PubMed

    Yang, Yuling; Li, Xiaoyi; Jiang, Jinliang; Du, Huailiang; Zhao, Lina; Zhao, Yuliang

    2010-10-26

    To establish ways to control the performance of artificial water channels is a big challenge. With molecular dynamics studies, we found that water flow inside the water channels of carbon nanotubes (CNTs) can be controlled by reducing or intensifying interaction energy between water molecules and the wall of the CNTs channel. A way of example toward this significant goal was demonstrated by the doping of nitrogen into the wall of CNTs. Different ratios of nitrogen doping result in different controllable water performance which is dominated mainly through a gradient of van der Waals forces created by the heteroatom doping in the wall of CNTs. Further results revealed that the nitrogen-doped CNT channels show less influence on the integrality of biomembrane than the pristine one, while the nitrogen-doped double-walled carbon nanotube exhibits fewer disturbances to the cellular membrane integrality than the nitrogen-doped single-walled carbon nanotube when interacting with biomembranes.

  7. Hard Carbon Fibers Pyrolyzed from Wool as High-Performance Anode for Sodium-Ion Batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoming; Li, Qian; Qiu, Shen; Liu, Xiaoling; Xiao, Lifen; Ai, Xinping; Yang, Hanxi; Cao, Yuliang

    2016-10-01

    In this paper, we first demonstrate that the wool from worn-out clothes can serve as a low-cost and easy-to-collect precursor to preparing high-performance hard carbons for Na-ion batteries. Morphological characterizations demonstrate that this wool-derived hard carbon presents well-defined and homogeneously dispersed fiber networks. X-ray diffraction results combined with high-resolution transmission electron microscopy analysis reveal that the interlayer space (d(002)) of the graphitic layers is 0.376 nm, sufficient for Na insertion into the stacked graphene layers. Electrochemical results show that the wool-derived hard carbon can deliver a high capacity of 303 mAh g-1 and excellent cycle stability over 80 cycles. This satisfactory electrochemical performance and easy synthetic procedure make it a promising anode material for practical SIBs.

  8. Functionalization of Petroleum Coke-Derived Carbon for Synergistically Enhanced Capacitive Performance

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Li, Xuejin; Huang, Jufeng; Xing, Wei; Yan, Zifeng

    2016-03-01

    Petroleum coke is a valuable and potential source for clean energy storage if it could be modified legitimately and facilely. In the present study, porous carbon with high surface area and abundant oxygen-containing groups was prepared from petroleum coke by chemical activation and modification processes. The as-prepared carbon exhibits a high surface area (1129 m2 · g-1) and stable micrographic structure. It presents a high specific capacitance and excellent rate performance in KOH electrolyte. Even at an ultrahigh current density of 50 A · g-1, the specific capacitance of the prepared carbon can still reach up to an unprecedented value of 261 F · g-1 with a superhigh retention rate of 81 %. In addition, the energy density of this material in aqueous electrolyte can be as high as 13.9 Wh · kg-1. The high energy density and excellent rate performance ensure its prosperous application in high-power energy storage system.

  9. Hard Carbon Fibers Pyrolyzed from Wool as High-Performance Anode for Sodium-Ion Batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoming; Li, Qian; Qiu, Shen; Liu, Xiaoling; Xiao, Lifen; Ai, Xinping; Yang, Hanxi; Cao, Yuliang

    2016-08-01

    In this paper, we first demonstrate that the wool from worn-out clothes can serve as a low-cost and easy-to-collect precursor to preparing high-performance hard carbons for Na-ion batteries. Morphological characterizations demonstrate that this wool-derived hard carbon presents well-defined and homogeneously dispersed fiber networks. X-ray diffraction results combined with high-resolution transmission electron microscopy analysis reveal that the interlayer space (d(002)) of the graphitic layers is 0.376 nm, sufficient for Na insertion into the stacked graphene layers. Electrochemical results show that the wool-derived hard carbon can deliver a high capacity of 303 mAh g-1 and excellent cycle stability over 80 cycles. This satisfactory electrochemical performance and easy synthetic procedure make it a promising anode material for practical SIBs.

  10. Highly Flexible Freestanding Porous Carbon Nanofibers for Electrodes Materials of High-Performance All-Carbon Supercapacitors.

    PubMed

    Liu, Ying; Zhou, Jinyuan; Chen, Lulu; Zhang, Peng; Fu, Wenbin; Zhao, Hao; Ma, Yufang; Pan, Xiaojun; Zhang, Zhenxing; Han, Weihua; Xie, Erqing

    2015-10-28

    Highly flexible porous carbon nanofibers (P-CNFs) were fabricated by electrospining technique combining with metal ion-assistant acid corrosion process. The resultant fibers display high conductivity and outstanding mechanical flexibility, whereas little change in their resistance can be observed under repeatedly bending, even to 180°. Further results indicate that the improved flexibility of P-CNFs can be due to the high graphitization degree caused by Co ions. In view of electrode materials for high-performance supercapacitors, this type of porous nanostructure and high graphitization degree could synergistically facilitate the electrolyte ion diffusion and electron transportation. In the three electrodes testing system, the resultant P-CNFs electrodes can exhibit a specific capacitance of 104.5 F g(-1) (0.2 A g(-1)), high rate capability (remain 56.5% at 10 A g(-1)), and capacitance retention of ∼94% after 2000 cycles. Furthermore, the assembled symmetric supercapacitors showed a high flexibility and can deliver an energy density of 3.22 Wh kg(-1) at power density of 600 W kg(-1). This work might open a way to improve the mechanical properties of carbon fibers and suggests that this type of freestanding P-CNFs be used as effective electrode materials for flexible all-carbon supercapacitors.

  11. IBS and expected luminosity performance for RHIC beams at top energy with 56 MHz SRF cavity

    SciTech Connect

    Fedotov,A.

    2008-10-01

    The purpose of RF system in RHIC is to capture injected bunches, accelerate them to the top energy, and store bunches at the top energy for many hours. The accelerating RF system operates at harmonic number h=360 of the particle revolution frequency f=78.196 kHz, which corresponds to 28.15MHz. The storage RF system accepts the shortened bunches at top energy and provides longitudinal focusing to keep these bunches short during the store time (collision mode). The storage system operates at harmonic number h=7x360=2520, which corresponds to an RF frequency of 197.05 MHz [1]. Recently, an upgrade of storage RF system with a superconducting 56 MHz cavity was proposed [2]. This upgrade will provide significant increase in the acceptance of storage RF bucket. Presently, the short bunch length for collisions is obtained via RF gymnastics with bunch rotation (called re-bucketing), because the length of 197MHz bucket of 5 nsec is too short to accommodate long bunches otherwise. However, due to bucket non-linearity and hardware complications some increase in the longitudinal emittance occurs during re-bucketing. The 56MHz cavity will produce sufficiently short bunches which would allow one to operate without re-bucketing procedure. This Note summarizes simulation of beam evolution due to Intra-beam scattering (IBS) for beam parameters expected with the 56 MHz SRF cavity upgrade. Expected luminosity improvement is shown both for Au ions at 100 GeV/nucleon and for protons at 250 GeV.

  12. Performance of preproduction model cesium beam frequency standards for spacecraft applications

    NASA Technical Reports Server (NTRS)

    Levine, M. W.

    1978-01-01

    A cesium beam frequency standards for spaceflight application on Navigation Development Satellites was designed and fabricated and preliminary testing was completed. The cesium standard evolved from an earlier prototype model launched aboard NTS-2 and the engineering development model to be launched aboard NTS satellites during 1979. A number of design innovations, including a hybrid analog/digital integrator and the replacement of analog filters and phase detectors by clocked digital sampling techniques are discussed. Thermal and thermal-vacuum testing was concluded and test data are presented. Stability data for 10 to 10,000 seconds averaging interval, measured under laboratory conditions, are shown.

  13. Performance Monitoring: Evaluating an Organic Carbon-Limestone PRB for Treatment of Heavy Metals and Acidity

    EPA Science Inventory

    Since 2004, researchers from the U.S. EPA National Risk Management Research Laboratory (NRMRL) have annually evaluated performance of an organic carbon-limestone permeable reactive barrier (PRB) system installed in 2003 by EPA Region 6 at the Delatte Metals Superfund site in Ponc...

  14. Ultrahigh-Power-Factor Carbon Nanotubes and an Ingenious Strategy for Thermoelectric Performance Evaluation.

    PubMed

    Zhou, Wenbin; Fan, Qingxia; Zhang, Qiang; Li, Kewei; Cai, Le; Gu, Xiaogang; Yang, Feng; Zhang, Nan; Xiao, Zhuojian; Chen, Huiliang; Xiao, Shiqi; Wang, Yanchun; Liu, Huaping; Zhou, Weiya; Xie, Sishen

    2016-07-01

    An ingenious strategy is put forward to evaluate accurately the thermoelectric performance of carbon nanotube (CNT) thin films, including thermal conductivity, electrical conductivity, and Seebeck coefficient in the same direction. The results reveal that the as-prepared CNT interconnected films and CNT fibers possess enormous potential of thermoelectric applications because of their ultrahigh power factors. PMID:27199099

  15. PERFORMANCE EVALUATION OF A CARBON-BASED REACTIVE BARRIER FOR NITRATE REMEDIATION

    EPA Science Inventory

    Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constr...

  16. Irradiation With Carbon Ion Beams Induces Apoptosis, Autophagy, and Cellular Senescence in a Human Glioma-Derived Cell Line

    SciTech Connect

    Jinno-Oue, Atsushi; Shimizu, Nobuaki; Hamada, Nobuyuki; Wada, Seiichi; Tanaka, Atsushi; Shinagawa, Masahiko; Ohtsuki, Takahiro; Mori, Takahisa; Saha, Manujendra N.; Hoque, Ariful S.; Islam, Salequl; Kogure, Kimitaka; Funayama, Tomoo; Kobayashi, Yasuhiko

    2010-01-15

    Purpose: We examined biological responses of human glioma cells to irradiation with carbon ion beams (C-ions). Methods and Materials: A human glioma-derived cell line, NP-2, was irradiated with C-ions. Apoptotic cell nuclei were stained with Hoechst 33342. Induction of autophagy was examined either by staining cells with monodansylcadaverine (MDC) or by Western blotting to detect conversion of microtuble-associated protein light chain 3 (MAP-LC3) (LC3-I) to the membrane-bound form (LC3-II). Cellular senescence markers including induction of senescence-associated beta-galactosidase (SA-beta-gal) were examined. The mean telomere length of irradiated cells was determined by Southern blot hybridization. Expression of tumor suppressor p53 and cyclin/cyclin-dependent kinase inhibitor p21{sup WAF1/CIP1} in the irradiated cells was analyzed by Western blotting. Results: When NP-2 cells were irradiated with C-ions at 6 Gy, the major population of the cells died of apoptosis and autophagy. The residual fraction of attached cells (<1% of initially irradiated cells) could not form a colony: however, they showed a morphological phenotype consistent with cellular senescence, that is, enlarged and flattened appearance. The senescent nature of these attached cells was further indicated by staining for SA-beta-gal. The mean telomere length was not changed after irradiation with C-ions. Phosphorylation of p53 at serine 15 as well as the expression of p21{sup WAF1/CIP1} was induced in NP-2 cells after irradiation. Furthermore, we found that irradiation with C-ions induced cellular senescence in a human glioma cell line lacking functional p53. Conclusions: Irradiation with C-ions induced apoptosis, autophagy, and cellular senescence in human glioma cells.

  17. Effects of X-ray and carbon ion beam irradiation on membrane permeability and integrity in Saccharomyces cerevisiae cells.

    PubMed

    Cao, Guozhen; Zhang, Miaomiao; Miao, Jianshun; Li, Wenjian; Wang, Jufang; Lu, Dong; Xia, Jiefang

    2015-03-01

    Saccharomyces cerevisiae has served as a eukaryotic model in radiation biology studies of cellular responses to ionizing radiation (IR). Research in this field has thus far mainly been focused on DNA strand breaks, DNA base damage, or inhibition of protein activity. However, the effects of IR on S. cerevisiae cell membranes have barely been studied. Here, we investigated the changes in the permeability and integrity of S. cerevisiae cell membranes induced by high-linear energy transfer carbon ion (CI) beam or low-linear energy transfer X-ray. After CI exposure, protein elution and nucleotide diffusion were more pronounced than after X-ray treatment at the same doses, although these features were most prevalent following irradiation doses of 25-175 Gy. Flow cytometry of forward scatter light versus side scatter light and double-staining with fluorescein diacetate and propidium iodide showed that CI and X-ray irradiation significantly affected S. cerevisiae cell membrane integrity and cellular enzyme activity compared with untreated control cells. The extent of lesions in CI-irradiated cells, which exhibited markedly altered morphology and size, was greater than that in X-ray-irradiated cells. The relationships between permeabilized cells, esterase activity, and non-viable cell numbers furthermore indicated that irradiation-induced increases in cell permeabilization and decreases in esterase activity are dependent on the type of radiation and that these parameters correspond well with cell viability. These results also indicate that the patterns of cell inactivity due to X-ray or CI irradiation may be similar in terms of cell membrane damage.

  18. Ion beam fabrication of aluminum-doped zinc oxide layer for high-performance liquid crystals alignment.

    PubMed

    Liu, Yang; Lee, Ju Hwan; Seo, Dae-Shik

    2016-07-25

    In this paper, a 1.8 keV ion beam (IB) sputtered thin layer of aluminum-doped zinc oxide (AZO) with columnar AZO bumps covering the surface working as an alignment layer for the homogeneous alignment of liquid crystals (LC) is investigated. Bumpy AZO alignment layers in twisted nematic (TN) cells generated larger LC pre-tilt angles and thus enabled accelerated switching of LC, and the highly conductive bumpy AZO thin layers allowed super-fast release of accumulated charges, and led to low residual DC performance. These results indicate the promising applications of AZO bumps layer as alignment layer in LC devices. PMID:27464189

  19. A portable Ku-band front-end test package for beam-waveguide antenna performance evaluation

    NASA Technical Reports Server (NTRS)

    Otoshi, T. Y.; Stewart, S. R.; Franco, M. M.

    1991-01-01

    A 34-m beam-waveguide (BWG) antenna has been built a Deep Space Station 13 (DDS 13) in the Goldstone Deep Space Communications Complex. This antenna is designed to be efficient at X-, Ku-, and Ka-bands, and it is the first NASA tracking antenna to use a BWG design. The design of a Ku-band test package for the new BWG antenna at 11.7-12.2 GHz is presented. Results of linear polarization measurements with the test package on the ground are also presented. This report is the fifth in a series of articles concerned with test package design and performance.

  20. Design and Performance Evaluation of Optical Ethernet Switching Architecture with Liquid Crystal on Silicon-Based Beam-Steering Technology

    NASA Astrophysics Data System (ADS)

    Cheng, Yuh-Jiuh; Chou, H.-H.; Shiau, Yhi; Cheng, Shu-Ying

    2016-07-01

    A non-blocking optical Ethernet switching architecture with liquid crystal on a silicon-based beam-steering switch and optical output buffer strategies are proposed. For preserving service packet sequencing and fairness of routing sequence, priority and round-robin algorithms are adopted at the optical output buffer in this research. Four methods were used to implement tunable fiber delay modules for the optical output buffers to handle Ethernet packets with variable bit-rates. The results reported are based on the simulations performed to evaluate the proposed switching architecture with traffic analysis under a traffic model captured from a real-core network.

  1. Hierarchical porous carbon aerogel derived from bagasse for high performance supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Hao, Pin; Zhao, Zhenhuan; Tian, Jian; Li, Haidong; Sang, Yuanhua; Yu, Guangwei; Cai, Huaqiang; Liu, Hong; Wong, C. P.; Umar, Ahmad

    2014-09-01

    Renewable, cost-effective and eco-friendly electrode materials have attracted much attention in the energy conversion and storage fields. Bagasse, the waste product from sugarcane that mainly contains cellulose derivatives, can be a promising candidate to manufacture supercapacitor electrode materials. This study demonstrates the fabrication and characterization of highly porous carbon aerogels by using bagasse as a raw material. Macro and mesoporous carbon was first prepared by carbonizing the freeze-dried bagasse aerogel; consequently, microporous structure was created on the walls of the mesoporous carbon by chemical activation. Interestingly, it was observed that the specific surface area, the pore size and distribution of the hierarchical porous carbon were affected by the activation temperature. In order to evaluate the ability of the hierarchical porous carbon towards the supercapacitor electrode performance, solid state symmetric supercapacitors were assembled, and a comparable high specific capacitance of 142.1 F g-1 at a discharge current density of 0.5 A g-1 was demonstrated. The fabricated solid state supercapacitor displayed excellent capacitance retention of 93.9% over 5000 cycles. The high energy storage ability of the hierarchical porous carbon was attributed to the specially designed pore structures, i.e., co-existence of the micropores and mesopores. This research has demonstrated that utilization of sustainable biopolymers as the raw materials for high performance supercapacitor electrode materials is an effective way to fabricate low-cost energy storage devices.Renewable, cost-effective and eco-friendly electrode materials have attracted much attention in the energy conversion and storage fields. Bagasse, the waste product from sugarcane that mainly contains cellulose derivatives, can be a promising candidate to manufacture supercapacitor electrode materials. This study demonstrates the fabrication and characterization of highly porous carbon

  2. Comparison of denitrification performances using PLA/starch with different mass ratios as carbon source.

    PubMed

    Wu, Chuanfu; Tang, Danqi; Wang, Qunhui; Wang, Juan; Liu, Jianguo; Guo, Yan; Liu, Shu

    2015-01-01

    A suitable carbon source is significant for biological nitrate removal from groundwater. In this study, slow-release carbon sources containing polylactic acid (PLA) and starch at 8:2, 7:3, 6:4, 5:5, 4:6, and 3:7 ratios were prepared using a blending and fusing technique. The PLA/starch blend was then used as a solid carbon source for biological nitrate removal. The carbon release rate of PLA/starch was found to increase with increased starch content in leaching experiments. PLA/starch at 5:5 mass ratio was found to have the highest denitrification performance and organic carbon consumption efficiency in semi-continuous denitrification experiments, and was also revealed to support complete denitrification at 50 mg-N/L influent nitrate concentration in continuous experiments. The effluent nitrate concentration was <2 mg NO(3)(-)-N/L, which met the national standard (GB 14848-93) for groundwater. Scanning electron microscopy results further showed that the surface roughness of PLA/starch increased with prolonged experimental time, which may be conducive to microorganism attachment. Therefore, PLA/starch was a suitable carbon source and biofilm carrier for groundwater remediation.

  3. Performance of carbon material derived from starch mixed with flame retardant as electrochemical capacitor

    NASA Astrophysics Data System (ADS)

    Tsubota, Toshiki; Morita, Masaki; Murakami, Naoya; Ohno, Teruhisa

    2014-12-01

    Carbon materials derived from starch with an added flame retardant, such as melamine polyphosphate, melamine sulfate, guanylurea phosphate, or guanidine phosphate, were synthesized for investigating the performance as the electrode of an electrochemical capacitor. The yield after the heat treatment of the carbonization reaction increased by the addition of these flame retardants up to 800 °C. Although both the specific surface area and electrical resistivity are almost independent of the addition of the flame retardants, the capacitance values are improved with the addition of the flame retardants. The nitrogen atoms derived from the flame retardants are introduced to some extent into the synthesized carbon material. Moreover, the phosphorous atoms or the sulfur atoms derived from the flame retardants are doped into the synthesized carbon material. The method applied in this study, that is, the addition of flame retardants before the carbonization process can be used for the doping of the hetero atom such as N, P and S into the carbon material.

  4. Three dimensionally ordered mesoporous carbon as a stable, high-performance Li-O₂ battery cathode.

    PubMed

    Xie, Jin; Yao, Xiahui; Cheng, Qingmei; Madden, Ian P; Dornath, Paul; Chang, Chun-Chih; Fan, Wei; Wang, Dunwei

    2015-03-27

    Enabled by the reversible conversion between Li2O2 and O2, Li-O2 batteries promise theoretical gravimetric capacities significantly greater than Li-ion batteries. The poor cycling performance, however, has greatly hindered the development of this technology. At the heart of the problem is the reactivity exhibited by the carbon cathode support under cell operation conditions. One strategy is to conceal the carbon surface from reactive intermediates. Herein, we show that long cyclability can be achieved on three dimensionally ordered mesoporous (3DOm) carbon by growing a thin layer of FeO(x) using atomic layer deposition (ALD). 3DOm carbon distinguishes itself from other carbon materials with well-defined pore structures, providing a unique material to gain insight into processes key to the operations of Li-O2 batteries. When decorated with Pd nanoparticle catalysts, the new cathode exhibits a capacity greater than 6000 mAh g(carbon) (-1) and cyclability of more than 68 cycles.

  5. Chemical Cleavage of Layered Carbon Nitride with Enhanced Photoluminescent Performances and Photoconduction.

    PubMed

    Zhou, Zhixin; Shen, Yanfei; Li, Ying; Liu, Anran; Liu, Songqin; Zhang, Yuanjian

    2015-12-22

    Graphene quantum dots (GQDs) and carbon dots (C-dots) have various alluring properties and potential applications, but they are often limited by unsatisfied optical performance such as low quantum yield, ambiguous fluorescence emission mechanism, and narrow emission wavelength. Herein, we report that bulk polymeric carbon nitride could be utilized as a layered precursor to prepare carbon nitride nanostructures such as nanorods, nanoleaves and quantum dots by chemical tailoring. As doped carbon materials, these carbon nitride nanostructures not only intrinsically emitted UV lights but also well inherited the explicit photoluminescence mechanism of the bulk pristine precursor, both of which were rarely reported for GQDs and C-dots. Especially, carbon nitride quantum dots (CNQDs) had a photoluminescence quantum yield (QY) up to 46%, among the highest QY for metal-free quantum dots so far. As examples, the CNQDs were utilized as a photoluminescence probe for rapid detection of Fe(3+) with a detection limit of 1 μM in 2 min and a photoconductor in an all-solid-state device. This work would open up an avenue for doped nanocarbon in developing photoelectrical devices and sensors.

  6. Effect of nano-scale characteristics of graphene on electrochemical performance of activated carbon supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Jasni, M. R. M.; Deraman, M.; Suleman, M.; Hamdan, E.; Sazali, N. E. S.; Nor, N. S. M.; Shamsudin, S. A.

    2016-02-01

    Graphene with its typical nano-scale characteristic properties has been widely used as an additive in activated carbon electrodes in order to enhance the performance of the electrodes for their use in high performance supercapacitors. Activated carbon monoliths (ACMs) electrodes have been prepared by carbonization and activation of green monoliths (GMs) of pre-carbonized fibers of oil palm empty fruit bunches or self-adhesive carbon grains (SACGs) and SACGs added with 6 wt% of KOH-treated multi-layer graphene. ACMs electrodes have been assembled in symmetrical supercapacitor cells that employed aqueous KOH electrolyte (6 M). The cells have been tested with cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge discharge methods to investigate the effect of graphene addition on the specific capacitance (Csp), specific energy (E), specific power (P), equivalent series resistance (ESR) and response time (τo) of the supercapacitor cells. The results show that the addition of graphene in the GMs change the values of Csp, Emax, Pmax, ESR and τo from (61-96) F/g, 2 Wh/kg, 104 W/kg, 2.6 Ω and 38 s, to the respective values of (110-124) F/g, 3 Wh/kg, 156 W/kg, 3.4 Ω and 63 s. This study demonstrates that the graphene addition in the GMs has a significant effect on the electrochemical behavior of the electrodes.

  7. Low Cost Carbon Fibre: Applications, Performance and Cost Models - Chapter 17

    SciTech Connect

    Warren, Charles David; Wheatley, Dr. Alan; Das, Sujit

    2014-01-01

    Weight saving in automotive applications has a major bearing on fuel economy. It is generally accepted that, typically, a 10% weight reduction in an automobile will lead to a 6-8% improvement in fuel economy. In this respect, carbon fibre composites are extremely attractive in their ability to provide superlative mechanical performance per unit weight. That is why they are specified for high-end uses such as Formula 1 racing cars and the latest aircraft (e.g. Boeing 787, Airbus A350 and A380), where they comprise over 50% by weight of the structure However, carbon fibres are expensive and this renders their composites similarly expensive. Research has been carried out at Oak Ridge National Laboratories (ORNL), Tennessee, USA for over a decade with the aim of reducing the cost of carbon fibre such that it becomes a cost-effective option for the automotive industry. Aspects of this research relating to the development of low cost carbon fibre have been reported in Chapter 3 of this publication. In this chapter, the practical industrial applications of low-cost carbon fibre are presented, together with considerations of the performance and cost models which underpin the work.

  8. Scale-dependent performances of CMIP5 earth system models in simulating terrestrial vegetation carbon

    NASA Astrophysics Data System (ADS)

    Jiang, L.; Luo, Y.; Yan, Y.; Hararuk, O.

    2013-12-01

    Mitigation of global changes will depend on reliable projection for the future situation. As the major tools to predict future climate, Earth System Models (ESMs) used in Coupled Model Intercomparison Project Phase 5 (CMIP5) for the IPCC Fifth Assessment Report have incorporated carbon cycle components, which account for the important fluxes of carbon between the ocean, atmosphere, and terrestrial biosphere carbon reservoirs; and therefore are expected to provide more detailed and more certain projections. However, ESMs are never perfect; and evaluating the ESMs can help us to identify uncertainties in prediction and give the priorities for model development. In this study, we benchmarked carbon in live vegetation in the terrestrial ecosystems simulated by 19 ESMs models from CMIP5 with an observationally estimated data set of global carbon vegetation pool 'Olson's Major World Ecosystem Complexes Ranked by Carbon in Live Vegetation: An Updated Database Using the GLC2000 Land Cover Product' by Gibbs (2006). Our aim is to evaluate the ability of ESMs to reproduce the global vegetation carbon pool at different scales and what are the possible causes for the bias. We found that the performance CMIP5 ESMs is very scale-dependent. While CESM1-BGC, CESM1-CAM5, CESM1-FASTCHEM and CESM1-WACCM, and NorESM1-M and NorESM1-ME (they share the same model structure) have very similar global sums with the observation data but they usually perform poorly at grid cell and biome scale. In contrast, MIROC-ESM and MIROC-ESM-CHEM simulate the best on at grid cell and biome scale but have larger differences in global sums than others. Our results will help improve CMIP5 ESMs for more reliable prediction.

  9. The influence of Stone-Thrower-Wales defect on vibrational characteristics of single-walled carbon nanotubes incorporating Timoshenko beam element

    NASA Astrophysics Data System (ADS)

    Maleki Moghadam, Reza; Hosseini, Seyyed Ahmad; Salehi, Manouchehr

    2014-08-01

    The influence of Stone-Thrower-Wales (STW) defect is scrutinized on the fundamental frequency of single walled carbon nanotube invoking molecular mechanics approach. The modal finite element analysis is carried out by employing Timoshenko's beam element to construct the Carbon-Carbon bond of CNT lattice structure. Hence, three configurations of defective CNTs are taken into account by applying two kinds of boundary conditions. The results demonstrate that the frequencies are dependent on boundary conditions, CNT length, chirality and defect position as the critical position of STW defect is near the fixed end for both cantilever and bridge boundary conditions. Likewise, the results reveal that the natural frequencies extremely depend on the orientation of C-C bond concentrated at the STW defect. Meanwhile, by increasing the number of defects, the models indicate different behaviors ascribing to bond rearrangement imposed by STW defect. The results are in good agreement with those from other literatures.

  10. Four-Dimensional Lung Treatment Planning in Layer-Stacking Carbon Ion Beam Treatment: Comparison of Layer-Stacking and Conventional Ungated/Gated Irradiation

    SciTech Connect

    Mori, Shinichiro; Kanematsu, Nobuyuki; Asakura, Hiroshi; Sharp, Gregory C.; Kumagai, Motoki; Dobashi, Suguru; Nakajima, Mio; Yamamoto, Naoyoshi; Kandatsu, Susumu; Baba, Masayuki

    2011-06-01

    Purpose: We compared four-dimensional (4D) layer-stacking and conventional carbon ion beam distribution in the treatment of lung cancer between ungated and gated respiratory strategies using 4DCT data sets. Methods and Materials: Twenty lung patients underwent 4DCT imaging under free-breathing conditions. Using planning target volumes (PTVs) at respective respiratory phases, two types of compensating bolus were designed, a full single respiratory cycle for the ungated strategy and an approximately 30% duty cycle for the exhalation-gated strategy. Beams were delivered to the PTVs for the ungated and gated strategies, PTV(ungated) and PTV(gated), respectively, which were calculated by combining the respective PTV(Tn)s by layer-stacking and conventional irradiation. Carbon ion beam dose distribution was calculated as a function of respiratory phase by applying a compensating bolus to 4DCT. Accumulated dose distributions were calculated by applying deformable registration. Results: With the ungated strategy, accumulated dose distributions were satisfactorily provided to the PTV, with D95 values for layer-stacking and conventional irradiation of 94.0% and 96.2%, respectively. V20 for the lung and Dmax for the spinal cord were lower with layer-stacking than with conventional irradiation, whereas Dmax for the skin (14.1 GyE) was significantly lower (21.9 GyE). In addition, dose conformation to the GTV/PTV with layer-stacking irradiation was better with the gated than with the ungated strategy. Conclusions: Gated layer-stacking irradiation allows the delivery of a carbon ion beam to a moving target without significant degradation of dose conformity or the development of hot spots.

  11. Oxidized carbon nitrides: water-dispersible, atomically thin carbon nitride-based nanodots and their performances as bioimaging probes.

    PubMed

    Oh, Junghoon; Yoo, Ran Ji; Kim, Seung Yeon; Lee, Yong Jin; Kim, Dong Wook; Park, Sungjin

    2015-04-13

    Three-dimensional (3D) carbon nitride (C3 N4 )-based materials show excellent performance in a wide range of applications because of their suitable band structures. To realize the great promise of two-dimensional (2D) allotropes of various 3D materials, it is highly important to develop routes for the production of 2D C3 N4 materials, which are one-atom thick, in order to understand their intrinsic properties and identify their possible applications. In this work, water-dispersible, atomically thin, and small carbon nitride nanodots were produced using the chemical oxidation of graphitic C3 N4 . Various analyses, including X-ray diffraction, X-ray photoelectron, Fourier-transform infrared spectroscopy, and combustion-based elemental analysis, and thermogravimetric analysis, confirmed the production of 3D oxidized C3 N4 materials. The 2D C3 N4 nanodots were successfully exfoliated as individual single layers; their lateral dimension was several tens of nanometers. They showed strong photoluminescence in the visible region as well as excellent performances as cell-imaging probes in an in vitro study using confocal fluorescence microscopy.

  12. Effect of O{sub 2}{sup +}, H{sub 2}{sup +}+ O{sub 2}{sup +}, and N{sub 2}{sup +}+ O{sub 2}{sup +} ion-beam irradiation on the field emission properties of carbon nanotubes

    SciTech Connect

    Acuna, J. J. S.; Alvarez, F.; Escobar, M.; Goyanes, S. N.; Candal, R. J.; Zanatta, A. R.

    2011-06-01

    The effect of O{sub 2}{sup +}, H{sub 2}{sup +}+ O{sub 2}{sup +}, and N{sub 2}{sup +}+ O{sub 2}{sup +} ion-beam irradiation of carbon nanotubes (CNTs) films on the chemical and electronic properties of the material is reported. The CNTs were grown by the chemical vapor deposition technique (CVD) on silicon TiN coated substrates previously decorated with Ni particles. The Ni decoration and TiN coating were successively deposited by ion-beam assisted deposition (IBAD) and afterwards the nanotubes were grown. The whole deposition procedure was performed in situ as well as the study of the effect of ion-beam irradiation on the CNTs by x-ray photoelectron spectroscopy (XPS). Raman scattering, field-effect emission gun scanning electron microscopy (FEG-SEM), and field emission (FE) measurements were performed ex situ. The experimental data show that: (a) the presence of either H{sub 2}{sup +} or N{sub 2}{sup +} ions in the irradiation beam determines the oxygen concentration remaining in the samples as well as the studied structural characteristics; (b) due to the experimental conditions used in the study, no morphological changes have been observed after irradiation of the CNTs; (c) the FE experiments indicate that the electron emission from the CNTs follows the Fowler-Nordheim model, and it is dependent on the oxygen concentration remaining in the samples; and (d) in association with FE results, the XPS data suggest that the formation of terminal quinone groups decreases the CNTs work function of the material.

  13. High performance low temperature carbon composite catalysts for flexible dye sensitized solar cells.

    PubMed

    Hashmi, Syed Ghufran; Halme, Janne; Saukkonen, Tapio; Rautama, Eeva-Leena; Lund, Peter

    2013-10-28

    Roll-to-roll manufacturing of dye sensitized solar cells (DSSCs) requires efficient and low cost materials that adhere well on the flexible substrates used. In this regard, different low temperature carbon composite counter electrode (CE) catalyst ink formulations for flexible DSSCs were developed that can be simply and quickly coated on plastic substrates and dried below 150 °C. The CEs were investigated in terms of photovoltaic performance in DSSCs by current-voltage measurements, mechanical adhesion properties by bending and tape tests, electro-catalytic performance by electrochemical impedance spectroscopy and microstructure by electron microscopy. In the bending and tape tests, PEDOT-carbon composite catalyst layers exhibited higher elasticity and better adhesion on all the studied substrates (ITO-PET and ITO-PEN plastic, and FTO-glass), compared to a binder free carbon composite and a TiO2 binder enriched carbon composite, and showed lower charge transfer resistance (1.5-3 Ω cm(2)) than the traditional thermally platinized CE (5 Ω cm(2)), demonstrating better catalytic performance for the tri-iodide reduction reaction. Also the TiO2 binder enriched carbon composite showed good catalytic characteristics and relatively good adhesion on ITO-PET, but on ITO-PEN its adhesion was poor. A DSSC with the TiO2 binder enriched catalyst layer reached 85% of the solar energy conversion efficiency of the reference DSSC based on the traditional thermally platinized CE. Based on the aforementioned characteristics, these carbon composites are promising candidates for replacing the platinum catalyst in a high volume roll-to-roll manufacturing process of DSSCs. PMID:24042582

  14. A three-dimensional carbon nano-network for high performance lithium ion batteries

    DOE PAGESBeta

    Tian, Miao; Wang, Wei; Liu, Yang; Jungjohann, Katherine L.; Thomas Harris, C.; Lee, Yung -Cheng; Yang, Ronggui

    2014-11-20

    Three-dimensional (3D) network structure has been envisioned as a superior architecture for lithium ion battery (LIB) electrodes, which enhances both ion and electron transport to significantly improve battery performance. Herein, a 3D carbon nano-network is fabricated through chemical vapor deposition of carbon on a scalably manufactured 3D porous anodic alumina (PAA) template. As a demonstration on the applicability of 3D carbon nano-network for LIB electrodes, the low conductivity active material, TiO2, is then uniformly coated on the 3D carbon nano-network using atomic layer deposition. High power performance is demonstrated in the 3D C/TiO2 electrodes, where the parallel tubes and gapsmore » in the 3D carbon nano-network facilitates fast Li ion transport. A large areal capacity of ~0.37 mAh·cm–2 is achieved due to the large TiO2 mass loading in the 60 µm-thick 3D C/TiO2 electrodes. At a test rate of C/5, the 3D C/TiO2 electrode with 18 nm-thick TiO2 delivers a high gravimetric capacity of ~240 mAh g–1, calculated with the mass of the whole electrode. A long cycle life of over 1000 cycles with a capacity retention of 91% is demonstrated at 1C. In this study, the effects of the electrical conductivity of carbon nano-network, ion diffusion, and the electrolyte permeability on the rate performance of these 3D C/TiO2 electrodes are systematically studied.« less

  15. A three-dimensional carbon nano-network for high performance lithium ion batteries

    SciTech Connect

    Tian, Miao; Wang, Wei; Liu, Yang; Jungjohann, Katherine L.; Thomas Harris, C.; Lee, Yung -Cheng; Yang, Ronggui

    2014-11-20

    Three-dimensional (3D) network structure has been envisioned as a superior architecture for lithium ion battery (LIB) electrodes, which enhances both ion and electron transport to significantly improve battery performance. Herein, a 3D carbon nano-network is fabricated through chemical vapor deposition of carbon on a scalably manufactured 3D porous anodic alumina (PAA) template. As a demonstration on the applicability of 3D carbon nano-network for LIB electrodes, the low conductivity active material, TiO2, is then uniformly coated on the 3D carbon nano-network using atomic layer deposition. High power performance is demonstrated in the 3D C/TiO2 electrodes, where the parallel tubes and gaps in the 3D carbon nano-network facilitates fast Li ion transport. A large areal capacity of ~0.37 mAh·cm–2 is achieved due to the large TiO2 mass loading in the 60 µm-thick 3D C/TiO2 electrodes. At a test rate of C/5, the 3D C/TiO2 electrode with 18 nm-thick TiO2 delivers a high gravimetric capacity of ~240 mAh g–1, calculated with the mass of the whole electrode. A long cycle life of over 1000 cycles with a capacity retention of 91% is demonstrated at 1C. In this study, the effects of the electrical conductivity of carbon nano-network, ion diffusion, and the electrolyte permeability on the rate performance of these 3D C/TiO2 electrodes are systematically studied.

  16. High-Performance Carbon Monoxide Oxidation Catalysts Engineered for Carbon Dioxide Lasers

    NASA Astrophysics Data System (ADS)

    Gardner, Steven Dwayne

    1990-01-01

    The low-temperature CO oxidation activity of numerous materials has been evaluated in order to develop efficient catalysts for use in CO_2 lasers. The materials were screened for activity in small, stoichiometric concentrations of CO and O_2 at temperatures near 55^circC. An Au/MnO_{rm x} catalyst was synthesized which exhibited exceptional CO oxidation activity while maintaining negligible performance decay over a period of at least 70 days. The data suggest that Au/MnO_{rm x} has potential applications in air purification and CO gas sensing as well. Extensive surface characterization data from Pt/SnO _{rm x} and Au/MnO _{rm x} catalysts are reported which relate surface composition and chemical state information to corresponding CO oxidation activity data. Ion scattering spectroscopy (ISS), Auger electron spectroscopy (AES), angle-resolved Auger electron spectroscopy (ARAES) and X-ray photoelectron spectroscopy (XPS) were utilized to observe the behavior of these surfaces as a function of numerous pretreatments which alter their catalytic activity. The results suggest that Pt(OH)_2 and Pt/Sn alloy formation may play a key role in the CO oxidation mechanism on Pt/SnO_{ rm x} surfaces. A Pt_3 Sn alloy was subsequently characterized before and after H_2 reduction to study its surface characteristics. Surface characterization of Au/MnO_ {rm x} and MnO_{ rm x} was performed in order to elucidate the CO oxidation mechanism. The spectral data yield evidence that the enhanced CO oxidation activity of Au/MnO _{rm x} is related to Mn present primarily as Mn_3O _4 with substantial amounts of water or hydroxyl groups. The spectra are consistent with very small Au particles which may exist in an oxidized state. The behavior of Au/MnO_{rm x} and MnO_{rm x} toward an inert pretreatment suggests the possibility of a Au -MnO_{rm x} interaction.

  17. Ranges of Applicability for the Continuum-beam Model in the Constitutive Analysis of Carbon Nanotubes: Nanotubes or Nano-beams?

    NASA Technical Reports Server (NTRS)

    Harik, Vasyl Michael; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    Ranges of validity for the continuum-beam model, the length-scale effects and continuum assumptions are analyzed in the framework of scaling analysis of NT structure. Two coupled criteria for the applicability of the continuum model are presented. Scaling analysis of NT buckling and geometric parameters (e.g., diameter and length) is carried out to determine the key non-dimensional parameters that control the buckling strains and modes of NT buckling. A model applicability map, which represents two classes of NTs, is constructed in the space of non-dimensional parameters. In an analogy with continuum mechanics, a mechanical law of geometric similitude is presented for two classes of beam-like NTs having different geometries. Expressions for the critical buckling loads and strains are tailored for the distinct groups of NTs and compared with the data provided by the molecular dynamics simulations. Implications for molecular dynamics simulations and the NT-based scanning probes are discussed.

  18. Effect of beam expansion loss in a carbon nanotube-doped PVA film on passively mode-locked erbium-doped fiber lasers with different feedback ratios

    NASA Astrophysics Data System (ADS)

    Cheng, Kuang-Nan; Chi, Yu-Chieh; Cheng, Chih-Hsien; Lin, Yung-Hsiang; Lo, Jui-Yung; Lin, Gong-Ru

    2014-10-01

    The effect of beam expansion induced divergent loss in a single-wall carbon nanotube (SWCNT) doped polyvinyl alcohol (PVA) based ultrafast saturable absorber (SA) film thickness on the passive mode-locking (PML) performances of erbium-doped fiber lasers are demonstrated. The variation on the PML pulsewidth of the EDFL is discussed by changing the SWCNT-PVA SA film thicknesses, together with adjusting the pumping power and the intra-cavity feedback ratio. An almost 6 dB increment of divergent loss when enlarging the SWCNT-PVA based SA film thickness from 30-130 µm is observed. When shrinking the SA thickness to 30 µm at the largest pumping power of 52.5 mW, the optical spectrum red-shifts to 1558.8 nm with its 3 dB spectral linewidth broadening up to 2.7 nm, while the pulse has already entered the soliton regime with multi-order Kelly sidebands aside the spectral shoulder. The soliton pulsewidth is as short as 790 fs, which is much shorter than those obtained with other thicker SWCNT doped PVA polymer film based SAs; therefore, the peak power from the output of the PML-EDFL is significantly enlarged accompanied by a completely suppressed residual continuous-wave level to achieve the largest on/off extinction ratio. The main mechanism of pulse shortening with reducing thickness of SWCNT doped PVA polymer film based SA is attributed to the limited beam expansion as well as the enlarged modulation depth, which results in shortened soliton pulsewidth with a clean dc background, and broadened spectrum with enriched Kelly sidebands. The increase of total SWCNT amount in the thicker SA inevitably causes a higher linear absorption; hence, the mode-locking threshold also rises accordingly. By enlarging pumping power from 38.5-52.5 mW, the highest ascent on pulse extinction of up to 32 dB is observed among all kinds of feedback conditions. Nevertheless, the enlargement on the extinction slightly decays with increasing the feedback ratio from 30-90%, as

  19. Improving the performance of E-beam 2nd writing in mask alignment accuracy and pattern faultless for CPL technology

    NASA Astrophysics Data System (ADS)

    Lee, Booky; Hung, Richard; Lin, Orson; Wu, Yuan-Hsun; Kozuma, Makoto; Shih, Chiang-Lin; Hsu, Michael; Hsu, Stephen D.

    2005-01-01

    The chromeless phase lithography (CPL) is a potential technology for low k1 optical image. For the CPL technology, we can control the local transmission rate to get optimized through pitch imaging performance. The CPL use zebra pattern to manipulate the pattern local transmission as a tri-tone structure in mask manufacturing. It needs the 2nd level writing to create the zebra pattern. The zebra pattern must be small enough not to be printed out and the 2nd writing overlay accuracy must keep within 40nm. The request is a challenge to E-beam 2nd writing function. The focus of this paper is in how to improve the overlay accuracy and get a precise pattern to form accurate pattern transmission. To fulfill this work several items have been done. To check the possibility of contamination in E-Beam chamber by the conductive layer coating we monitor the particle count in the E-Beam chamber before and after the coated blank load-unload. The conductivity of our conductive layer has been checked to eliminate the charging effect by optimizing film thickness. The dimension of alignment mark has also been optimized through experimentation. And finally we checked the PR remain to ensure sufficient process window in our etching process. To verify the performance of our process we check the 3D SEM picture. Also we use AIMs to prove the resolution improvement capability in CPL compared to the traditional methods-Binary mask and Half Tone mask. The achieved overlay accuracy and process can provide promising approach for NGL reticle manufacturing of CPL technology.

  20. Low carbon technology performance vs infrastructure vulnerability: analysis through the local and global properties space.

    PubMed

    Dawson, David A; Purnell, Phil; Roelich, Katy; Busch, Jonathan; Steinberger, Julia K

    2014-11-01

    Renewable energy technologies, necessary for low-carbon infrastructure networks, are being adopted to help reduce fossil fuel dependence and meet carbon mitigation targets. The evolution of these technologies has progressed based on the enhancement of technology-specific performance criteria, without explicitly considering the wider system (global) impacts. This paper presents a methodology for simultaneously assessing local (technology) and global (infrastructure) performance, allowing key technological interventions to be evaluated with respect to their effect on the vulnerability of wider infrastructure systems. We use exposure of low carbon infrastructure to critical material supply disruption (criticality) to demonstrate the methodology. A series of local performance changes are analyzed; and by extension of this approach, a method for assessing the combined criticality of multiple materials for one specific technology is proposed. Via a case study of wind turbines at both the material (magnets) and technology (turbine generators) levels, we demonstrate that analysis of a given intervention at different levels can lead to differing conclusions regarding the effect on vulnerability. Infrastructure design decisions should take a systemic approach; without these multilevel considerations, strategic goals aimed to help meet low-carbon targets, that is, through long-term infrastructure transitions, could be significantly jeopardized.