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Sample records for performance carbon beam

  1. 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.

  2. 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.

  3. 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.

  4. Focused Ion Beam Microscopy of ALH84001 Carbonate Disks

    NASA Astrophysics Data System (ADS)

    Thomas-Keprta, K. L.; Clemett, S. J.; Bazylinski, D. A.; Kirschvink, J. L.; McKay, D. S.; Vali, H.; Gibson, E. K., Jr.; Romanek, C. S.

    2005-03-01

    Our aim is to understand the mechanism(s) of formation of carbonate assemblages in ALH84001. We present here analyses by transmission electron microscopy (TEM) of carbonate thin sections produced by both focused ion beam (FIB) sectioning and ultramicrotomy.

  5. Performance Comparison: Superbeams, Beta Beams, Neutrino Factory

    SciTech Connect

    Winter, Walter

    2011-10-06

    In this talk, the performance comparison among superbeams (SB), beta beams (BB), and the Neutrino Factory (NF) is discussed. The ingredients to such a comparison are described, and the optimization and status of BB and NF are addressed. Finally, one example for the performance comparison is shown.

  6. 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.

  7. 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. PMID:22380206

  8. Geant4 simulations of proton beam transport through a carbon or beryllium degrader and following a beam line.

    PubMed

    van Goethem, M J; van der Meer, R; Reist, H W; Schippers, J M

    2009-10-01

    Monte Carlo simulations based on the Geant4 simulation toolkit were performed for the carbon wedge degrader used in the beam line at the Center of Proton Therapy of the Paul Scherrer Institute (PSI). The simulations are part of the beam line studies for the development and understanding of the GANTRY2 and OPTIS2 treatment facilities at PSI, but can also be applied to other beam lines. The simulated stopping power, momentum distributions at the degrader exit and beam line transmission have been compared to accurate benchmark measurements. Because the beam transport through magnetic elements is not easily modeled using Geant4a connection to the TURTLE beam line simulation program was made. After adjusting the mean ionization potential of the carbon degrader material from 78 eV to 95 eV, we found an accurate match between simulations and benchmark measurements, so that the simulation model could be validated. We found that the degrader does not completely erase the initial beam phase space even at low degraded beam energies. Using the validation results, we present a study of the usability of beryllium as a degrader material (mean ionization potential 63.7 eV). We found an improvement in the transmission of 30-45%, depending on the degraded beam energy, the higher value for the lower energies. PMID:19741273

  9. Numerical simulation of polarization beam splitter with triangular lattice of multi-walled carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Wu, Xingxing; Yun, Maojin; Wang, Mei; Liu, Chao; Li, Kai; Qin, Xiheng; Kong, Weijin; Dong, Lifeng

    2015-12-01

    A kind of polarization beam splitter with triangular lattice of multi-walled carbon nanotube arrays is designed and simulated. In the employed structure transverse-electric (TE) light is confined in the line defect with photonic band gap effect, while transverse-magnetic (TM) light is guided through it with extremely low diffraction. The performance of the designed polarization beam splitter is evaluated by utilizing optical properties of multi-walled carbon nanotubes, finite element modeling of wave propagation and transmission through periodic arrays. Simulation results indicate that the designed polarization beam splitter has low loss and less cross talk, and thereby may have practical applications in the integrated optical field.

  10. 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

  11. 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].

  12. Carbon Beam Radio-Therapy and Research Activities at HIMAC

    NASA Astrophysics Data System (ADS)

    Kanazawa, Mitsutaka

    2007-05-01

    Radio-therapy with carbon ion beam has been carried out since 1994 at HIMAC (Heavy Ion Medical Accelerator in Chiba) in NIRS (National Institute of Radiological Sciences). Now, many types of tumors can be treated with carbon beam with excellent local controls of the tumors. Stimulated with good clinical results, requirement of the dedicated compact facility for carbon beam radio-therapy is increased. To realize this requirement, design study of the facility and the R&D's of the key components in this design are promoted by NIRS. According successful results of these activities, the dedicated compact facility will be realized in Gunma University. In this facility, the established irradiation method is expected to use, which is passive irradiation method with wobbler magnets and ridge filter. In this presentation, above R&D's will be presented together with clinical results and basic research activities at HIMAC.

  13. 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.

  14. Radiative instability of electron beam in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Batrakov, Konstantin G.; Kuzhir, Polina P.; Maksimenko, Sergey A.

    2006-08-01

    Basic mechanisms of the interaction of electron beam tavelling through a carbon nanotube with electromagnetic wave, resulting in the radiative instability and generation of stimulated radiation, are considered. The effect of the surface electromagnetic wave slow-down in CNT (c/v > 100) [Slepyan et al., Phys. Rev. B 60, 17136, 1999] is exploited to synchronize the wave and the beam and thus to realize the Cherenkov radiation mechanism. Alternative mechanism of the electron beam instability is proposed based on the undulator emission arising due to the interband transitions of electrons moving in nanotube. The dispersion equations of the electron beam instability and threshold conditions for the stimulated radiation are derived and studied. The analysis of the threshold conditions estimates the possibility of the stimulated emission by electron beam as realistic and attainable at present-day experimental technique.

  15. 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.

  16. 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.

  17. A family of carbon-based nanocomposite tubular structures created by in situ electron beam irradiation.

    PubMed

    Liu, Jian-Wei; Xu, Jie; Ni, Yong; Fan, Feng-Jia; Zhang, Chuan-Ling; Yu, Shu-Hong

    2012-05-22

    We report a unique approach for the fabrication of a family of curling tubular nanostructures rapidly created by a rolling up of carbon membranes under in situ TEM electron beam irradiation. Multiwall tubes can also be created if irradiation by electron beam is performed long enough. This general approach can be extended to curve the conductive carbon film loaded with various functional nanomaterials, such as nanocrystals, nanorods, nanowires, and nanosheets, providing a unique strategy to make composite tubular structures and composite materials by a combination of desired optical, electronic, and magnetic properties, which could find potential applications, including fluid transportation, encapsulation, and capillarity on the nanometer scale. PMID:22530775

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Carbon-Ion Beam Irradiation Effectively Suppresses Migration and Invasion of Human Non-Small-Cell Lung Cancer Cells

    SciTech Connect

    Akino, Yuichi; Teshima, Teruki Kihara, Ayaka; Kodera-Suzumoto, Yuko; Inaoka, Miho; Higashiyama, Shigeki; Furusawa, Yoshiya; Matsuura, Nariaki

    2009-10-01

    Purpose: Control of cancer metastasis is one of the most important issues in cancer treatment. We previously demonstrated that carbon particle irradiation suppresses the metastatic potential of cancer cells, and many studies have reported that photon irradiation promotes it. The purpose of this study was to investigate the effect of carbon beam on non-small-cell lung cancer (NSCLC) cell aggressiveness and gene expression. Methods and Materials: A549 (lung adenocarcinoma) and EBC-1 (lung squamous cell carcinoma) cells were treated with 290 MeV/nucleon carbon ion beam at the Heavy Ion Medical Accelerator in Chiba or with 4-MV X-ray at Osaka University. We tested proliferative, migratory, and invasive activities by cell proliferation assay, Boyden chamber assay, and Matrigel chemoinvasion assay, respectively. cDNA microarray and reverse transcription polymerase chain reaction were also performed to assess mRNA expression alteration. Results: X-irradiation increased cell proliferation of A549 cells at 0.5 Gy, whereas high-dose X-ray reduced migration and invasion of A549 cells. By contrast, carbon beam irradiation did not enhance proliferation, and it reduced the migration and invasion capabilities of both A549 and EBC-1 cells more effectively than did X-irradiation. Carbon beam irradiation induced alteration of various gene expression profiles differently from X-ray irradiation. mRNA expression of ANLN, a homologue of anillin, was suppressed to 60% levels of basal expression in carbon beam-irradiated A549 cells after 12 h. Conclusion: Carbon beam effectively suppresses the metastatic potential of A549 and EBC-1 cells. Carbon beam also has different effects on gene expressions, and downregulation of ANLN was induced only by carbon beam irradiation.

  9. Microdosimetry for a carbon ion beam using track-etched detectors.

    PubMed

    Ambrožová, I; Vondráček, V; Šefl, M; Štěpán, V; Pachnerová Brabcová, K; Ploc, O; Incerti, S; Davídková, M

    2015-09-01

    Track-etched detectors (TED) have been used as linear energy transfer (LET) spectrometers in heavy ion beams for many years. LET spectra and depth-dose distribution of a carbon ion beam were measured behind polymethylmethacrylate degraders at Heavy Ion Medical Accelerator in Chiba, Japan. The measurements were performed along monoenergetic beam with energy 290 MeV u(-1) in different positions: (1) at beam extraction area, (2) at beginning, (3) maximum and (4) behind the Bragg peak region (0, 117, 147 and 151 mm of water-equivalent depth, respectively). The LET spectra inside and outside of the primary ion beam have been evaluated. TED record only heavy charged particles with LET above 8-10 keV µm(-1), while electrons and ions with lower LET are not detected. The Geant4 simulation toolkit version 4.9.6.P01 has been used to estimate the contribution of non-detected particles to absorbed dose. Presented results demonstrate the applicability of TED for microdosimetry measurements in therapeutic carbon ion beams. PMID:25862534

  10. 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.

  11. 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

  12. 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.

  13. Molecular sputter depth profiling using carbon cluster beams

    PubMed Central

    Winograd, Nicholas

    2010-01-01

    Sputter depth profiling of organic films while maintaining the molecular integrity of the sample has long been deemed impossible because of the accumulation of ion bombardment-induced chemical damage. Only recently, it was found that this problem can be greatly reduced if cluster ion beams are used for sputter erosion. For organic samples, carbon cluster ions appear to be particularly well suited for such a task. Analysis of available data reveals that a projectile appears to be more effective as the number of carbon atoms in the cluster is increased, leaving fullerene ions as the most promising candidates to date. Using a commercially available, highly focused C60q+ cluster ion beam, we demonstrate the versatility of the technique for depth profiling various organic films deposited on a silicon substrate and elucidate the dependence of the results on properties such as projectile ion impact energy and angle, and sample temperature. Moreover, examples are shown where the technique is applied to organic multilayer structures in order to investigate the depth resolution across film-film interfaces. These model experiments allow collection of valuable information on how cluster impact molecular depth profiling works and how to understand and optimize the depth resolution achieved using this technique. PMID:19649771

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. Resolution of a High Performance Cavity Beam Positron 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.; /SLAC /Caltech /KEK, Tsukuba

    2007-07-06

    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.

  20. 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.

  1. Enhanced piezoelectric performance from carbon fluoropolymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Baur, Cary; DiMaio, Jeffrey R.; McAllister, Elliot; Hossini, Reza; Wagener, Earl; Ballato, John; Priya, Shashank; Ballato, Arthur; Smith, Dennis W.

    2012-12-01

    The piezoelectric performance of polyvinylidene fluoride (PVDF) is shown to double through the controlled incorporation of carbon nanomaterial. Specifically, PVDF composites containing carbon fullerenes (C60) and single-walled carbon nanotubes (SWNT) are fabricated over a range of compositions and optimized for their Young's modulus, dielectric constant, and d31 piezoelectric coefficient. Thermally stimulated current measurements show a large increase in internal charge and polarization in the composites over pure PVDF. The electromechanical coupling coefficients (k31) at optimal loading levels are found to be 1.84 and 2 times greater than pure PVDF for the PVDF-C60 and PVDF-SWNT composites, respectively. Such property-enhanced nanocomposites could have significant benefit to electromechanical systems employed for structural sensing, energy scavenging, sonar, and biomedical imaging.

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Harris, Michael R.; Willetts, David V.

    1990-06-01

    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.

  5. 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.

  6. Performance model of molten carbonate fuel cell

    SciTech Connect

    Matsumoto, S.; Sasaki, A.; Urushibata, H.; Tanaka, T. )

    1990-06-01

    A performance model of a molten carbonate fuel cell (MCFC), that is an electrochemical energy conversion device for electric power generation, is discussed. The authors' purpose is to improve the presumptive ability of the MCFC model and to investigate the impact of MCFC characteristics in fuel cell system simulations. Basic data are obtained experimentally by single-cell tests. The authors pay special attention to the MCFC overall characteristics with respect to oxidant composition. A correlation formula based on the experimental data is derived as for the cell voltage, oxygen and carbon dioxide partial pressures. After three types of the MCFC system option are assumed, trade-off studies are made dependant on the performance models.

  7. A trichrome beam model for biological dose calculation in scanned carbon-ion radiotherapy treatment planning

    NASA Astrophysics Data System (ADS)

    Inaniwa, T.; Kanematsu, N.

    2015-01-01

    In scanned carbon-ion (C-ion) radiotherapy, some primary C-ions undergo nuclear reactions before reaching the target and the resulting particles deliver doses to regions at a significant distance from the central axis of the beam. The effects of these particles on physical dose distribution are accounted for in treatment planning by representing the transverse profile of the scanned C-ion beam as the superposition of three Gaussian distributions. In the calculation of biological dose distribution, however, the radiation quality of the scanned C-ion beam has been assumed to be uniform over its cross-section, taking the average value over the plane at a given depth (monochrome model). Since these particles, which have relatively low radiation quality, spread widely compared to the primary C-ions, the radiation quality of the beam should vary with radial distance from the central beam axis. To represent its transverse distribution, we propose a trichrome beam model in which primary C-ions, heavy fragments with atomic number Z ≥ 3, and light fragments with Z ≤ 2 are assigned to the first, second, and third Gaussian components, respectively. Assuming a realistic beam-delivery system, we performed computer simulations using Geant4 Monte Carlo code for analytical beam modeling of the monochrome and trichrome models. The analytical beam models were integrated into a treatment planning system for scanned C-ion radiotherapy. A target volume of 20  ×  20  ×  40 mm3 was defined within a water phantom. A uniform biological dose of 2.65 Gy (RBE) was planned for the target with the two beam models based on the microdosimetric kinetic model (MKM). The plans were recalculated with Geant4, and the recalculated biological dose distributions were compared with the planned distributions. The mean target dose of the recalculated distribution with the monochrome model was 2.72 Gy (RBE), while the dose with the trichrome model was 2.64 Gy (RBE). The monochrome model

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Fast beam condition monitor for CMS: Performance and upgrade

    NASA Astrophysics Data System (ADS)

    Leonard, Jessica L.; Bell, Alan; Burtowy, Piotr; Dabrowski, Anne; Hempel, Maria; Henschel, Hans; Lange, Wolfgang; Lohmann, Wolfgang; Odell, Nathaniel; Penno, Marek; Pollack, Brian; Przyborowski, Dominik; Ryjov, Vladimir; Stickland, David; Walsh, Roberval; Warzycha, Weronika; Zagozdzinska, Agnieszka

    2014-11-01

    The CMS beam and radiation monitoring subsystem BCM1F (Fast Beam Condition Monitor) consists of 8 individual diamond sensors situated around the beam pipe within the pixel detector volume, for the purpose of fast bunch-by-bunch monitoring of beam background and collision products. In addition, effort is ongoing to use BCM1F as an online luminosity monitor. BCM1F will be running whenever there is beam in LHC, and its data acquisition is independent from the data acquisition of the CMS detector, hence it delivers luminosity even when CMS is not taking data. A report is given on the performance of BCM1F during LHC run I, including results of the van der Meer scan and on-line luminosity monitoring done in 2012. In order to match the requirements due to higher luminosity and 25 ns bunch spacing, several changes to the system must be implemented during the upcoming shutdown, including upgraded electronics and precise gain monitoring. First results from Run II preparation are shown.

  13. Analytical, Numerical and Experimental Examination of Reinforced Composites Beams Covered with Carbon Fiber Reinforced Plastic

    NASA Astrophysics Data System (ADS)

    Kasimzade, A. A.; Tuhta, S.

    2012-03-01

    In the article, analytical, numerical (Finite Element Method) and experimental investigation results of beam that was strengthened with fiber reinforced plastic-FRP composite has been given as comparative, the effect of FRP wrapping number to the maximum load and moment capacity has been evaluated depending on this results. Carbon FRP qualitative dependences have been occurred between wrapping number and beam load and moment capacity for repair-strengthen the reinforced concrete beams with carbon fiber. Shown possibilities of application traditional known analysis programs, for the analysis of Carbon Fiber Reinforced Plastic (CFRP) strengthened structures.

  14. 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

  15. 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.

  16. 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.

  17. Performance of the KTeV high-energy neutral kaon beam at Fermilab

    SciTech Connect

    Bocean, V.

    1998-06-01

    The performance of the primary and secondary beams for the KTeV experiments E832 and E799-II is reviewed. The beam was commissioned in the summer of 1996 and initially operated for approximately one year. The report includes results on the primary beam, target station including primary beam dump and muon sweeping system, neutral beam collimation system, and alignment.

  18. Ion beam deposition of amorphous carbon films with diamond like properties

    NASA Technical Reports Server (NTRS)

    Angus, John C.; Mirtich, Michael J.; Wintucky, Edwin G.

    1982-01-01

    Carbon films were deposited on silicon, quartz, and potassium bromide substrates from an ion beam. Growth rates were approximately 0.3 micron/hour. The films were featureless and amorphous and contained only carbon and hydrogen in significant amounts. The density and carbon/hydrogen ratio indicate the film is a hydrogen deficient polymer. One possible structure, consistent with the data, is a random network of methylene linkages and tetrahedrally coordinated carbon atoms.

  19. Robust, easily shaped, and epoxy-free carbon-fiber-aluminum cathodes for generating high-current electron beams

    NASA Astrophysics Data System (ADS)

    Liu, Lie; Li, Limin; Wen, Jianchun; Wan, Hong

    2009-02-01

    This paper presents the construction of carbon-fiber-aluminum (CFA) cathode by squeezing casting and its applications for generating high-current electron beams to drive high-power microwave sources. The fabrication process avoided using epoxy, a volatile deteriorating the vacuum system. These cathodes had a higher hardness than conventional aluminum, facilitating machining. After surface treatment, carbon fibers became the dominator determining emission property. A multineedle CFA cathode was utilized in a triode virtual cathode oscillator (vircator), powered by a ˜450 kV, ˜400 ns pulse. It was found that 300-400 MW, ˜250 ns microwave was radiated at a dominant frequency of 2.6 GHz. Further, this cathode can endure high-current-density emission without detectable degradation in performance as the pulse shot proceeded, showing the robust nature of carbon fibers as explosive emitters. Overall, this new class of cold cathodes offers a potential prospect of developing high-current electron beam sources.

  20. Test beam performance of the CDF plug upgrade hadron calorimeter

    SciTech Connect

    de Barbaro, P.; CDF Plug Upgrade Group

    1998-01-13

    We report on the performance of the CDF End Plug Hadron Calorimeter in a test beam. The sampling calorimeter is constructed using 2 inch iron absorber plates and scintillator planes with wavelength shifting fibers for readout. The linearity and energy resolution of the calorimeter response to pions, and the transverse uniformity of the response to muons and pions are presented. The parameter e/h, representing the ratio of the electromagnetic to hadronic response, is extracted from the data.

  1. Performance of a reentrant cavity beam position monitor

    NASA Astrophysics Data System (ADS)

    Simon, Claire; Luong, Michel; Chel, Stéphane; Napoly, Olivier; Novo, Jorge; Roudier, Dominique; Rouvière, Nelly; Baboi, Nicoleta; Mildner, Nils; Nölle, Dirk

    2008-08-01

    The beam-based alignment and feedback systems, essential operations for the future colliders, require high resolution beam position monitors (BPMs). In the framework of the European CARE/SRF program, a reentrant cavity BPM with its associated electronics was developed by the CEA/DSM/Irfu in collaboration with DESY. The design, the fabrication, and the beam test of this monitor are detailed within this paper. This BPM is designed to be inserted in a cryomodule, work at cryogenic temperature in a clean environment. It has achieved a resolution better than 10μm and has the possibility to perform bunch to bunch measurements for the x-ray free electron laser (X-FEL) and the International Linear Collider (ILC). Its other features are a small size of the rf cavity, a large aperture (78 mm), and an excellent linearity. A first prototype of a reentrant cavity BPM was installed in the free electron laser in Hamburg (FLASH), at Deutsches Elektronen-Synchrotron (DESY) and demonstrated its operation at cryogenic temperature inside a cryomodule. The second, installed, also, in the FLASH linac to be tested with beam, measured a resolution of approximately 4μm over a dynamic range ±5mm in single bunch.

  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. Physical and engineering aspect of carbon beam therapy

    NASA Astrophysics Data System (ADS)

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

    2003-08-01

    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.

  4. 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

  5. Electron beam evaporated carbon doping of InGaAs layers grown by gas source molecular beam epitaxy

    SciTech Connect

    Salokatve, A.; Toivonen, M.; Asonen, H.; Pessa, M.; Likonen, J.

    1996-12-31

    The authors have studied carbon doping of GaInAs grown by gas-source molecular beam epitaxy. Graphite was used as a source material for carbon evaporation. GaInAs was studied due to its importance as a base layer in InP-based heterojunction bipolar transistors. They show that useful p-type acceptor concentrations can be achieved by evaporation from graphite source for GaInAs grown by gas-source molecular beam epitaxy. Secondary ion mass spectroscopy and Van der Pauw Hall measurements were used to characterize the carbon and net acceptor concentrations of their GaInAs layers. The effect of rapid thermal annealing on acceptor concentrations and Hall mobilities was also studied.

  6. 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.

  7. Test beam performance of CDF plug upgrade EM calorimeter

    SciTech Connect

    Fukui, Y.

    1998-11-01

    CDF Plug Upgrade(tile-fiber) EM Calorimeter performed resolution of 15{percent}/{radical} (E) {circle_plus}0.7{percent} with non-linearity less than 1{percent} in a energy range of 5{endash}180 GeV at Fermilab Test Beam. Transverse uniformity of inside-tower-response of the EM Calorimeter was 2.2{percent} with 56 GeV positron, which was reduced to 1.0{percent} 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}C{sub s} Source was stable within 1{percent} in the period of 8 months. {copyright} {ital 1998 American Institute of Physics.}

  8. Effects of scattered radiation and beam quality on low contrast performance in cone beam breast CT

    NASA Astrophysics Data System (ADS)

    Altunbas, M. Cem; Shaw, Chris; Chen, Lingyun; Wang, Tianpeng; Tu, Shuju

    2006-03-01

    In this work, we investigated the effects of scattered radiation and beam quality on the low contrast performance relevant to cone beam breast CT imaging. For experiments, we used our benchtop conebeam CT system and constructed a phantom consisting of simulated fat and soft tissues. We varied the field of view (FOV) along the z direction to observe its effect on scattered radiation. The beam quality was altered by varying the tube voltage from 50 to 100 kV. We computed the contrast-to-noise ratio (CNR) from reconstructed images and normalized it to the square root of dose measured at the center of the phantom. The results were used as the figure of merit (FOM). The effect of the beam quality on the scatter to primary ratio (SPR) had minimal impact and the SPR was primarily dominated by the FOV. In the central section of the phantom, increasing the FOV from 4 to 16 cm resulted in drop of CNR in the order of 15-20% at any given kVp setting. For a given FOV, the beam quality had insignificant effect on the FOM in the central section of the phantom. In the peripheral section, a 10 % drop in FOM was observed when the kVp setting was increased from 50 to 100. At lower kVp values, the primary x-ray transmission through the thicker parts of the phantom was severely reduced. Under such circumstances, ring artifacts were observed due to imperfect flat field correction at very low signal intensities. Higher kVp settings and higher SPRs helped to increase the signal intensity in highly attenuating regions and suppressed the ring artifacts.

  9. Multi-pulsed intense electron beam emission from velvet, carbon fibers, carbon nano-tubes and dispenser cathodes

    NASA Astrophysics Data System (ADS)

    Xia, Lian-Sheng; Yang, An-Min; Chen, Yi; Zhang, Huang; Liu, Xing-Guang; Li, Jin; Jiang, Xiao-Guo; Zhang, Kai-Zhi; Shi, Jin-Shui; Deng, Jian-Jun; Zhang, Lin-Wen

    2010-11-01

    The experimental results of studies of four kinds of cathode emitting intense electron beams are demonstrated under multi-pulsed mode based on an experimental setup including two multi-pulse high voltage sources. The tested cathodes include velvet, carbon fibers, carbon nano-tubes (CNTs) and dispenser cathodes. The results indicate that all four are able to emit multi-pulsed beams. For velvet, carbon fiber and CNTs, the electron induced cathode plasma emission may be the main process and this means that there are differences in beam parameters from pulse to pulse. For dispenser cathodes tested in the experiment, although there is a little difference from pulse to pulse for some reason, thermal-electric field emission may be the main process.

  10. Using Pyrolysis Molecular Beam Mass Spectrometry to Characterize Soil Organic Carbon in Native Prairie Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to characterize soil organic carbon (SOC) with pyrolysis molecular beam mass spectrometry (py-MBMS) and then to determine correlations between the mass spectra and associated soil characterization data. Both soil carbon chemistry and the organic forms in which SOC is...

  11. Practical biological spread-out Bragg peak design for a carbon beam

    NASA Astrophysics Data System (ADS)

    Kim, Chang Hyeuk; Lee, Hwa-Ryun; Chang, Seduk; Jang, Hong Suk; Kim, Jeong Hwan; Park, Dong Wook; Hwang, Won Taek; Yang, Tea-Keun

    2015-10-01

    In radiation therapy, the carbon beams has more advantages with respect to biological properties then a proton beam. The carbon beam has a high linear energy transfer (LET) to the medium and a higher relative biological effectiveness (RBE). To design the spread-out Bragg peak (SOBP) of biological dose for a carbon beam, we propose a practical method using the linear-quadratic (LQ) model and the Geant4-based Monte Carlo simulation code. Various Bragg peak profiles and LETs were calculated for each slice in the target region. To generate an appropriate biological SOBP, we applied a set of weighting factors, which are power functions in terms of energy steps, to each obtained physical dose. The designed biological SOBP showed a uniformity of 1.34%.

  12. Fabrication of carbon layer coated FE-nanoparticles using an electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Kim, Hyun Bin; Jeun, Joon Pyo; Kang, Phil Hyun; Oh, Seung-Hwan

    2016-01-01

    A novel synthesis of carbon encapsulated Fe nanoparticles was developed in this study. Fe chloride (III) and polyacrylonitrile (PAN) were used as precursors. The crosslinking of PAN molecules and the nucleation of Fe nanoparticles were controlled by the electron beam irradiation dose. Stabilization and carbonization processes were carried out using a vacuum furnace at 275 °C and 1000 °C, respectively. Micro structures were evaluated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Fe nanoparticles were formed with diameters of 100 nm, and the Fe nanoparticles were encapsulated by carbon layers. As the electron beam irradiation dose increased, it was observed that the particle sizes decreased.

  13. 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.

  14. 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.

  15. 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

  16. Neutron beam design, development, and performance for neutron capture therapy

    SciTech Connect

    Harling, O.K.; Bernard, J.A. ); Zamenhof, R.G. )

    1990-01-01

    The report presents topics presented at a workshop on neutron beams and neutron capture therapy. Topics include: neutron beam design; reactor-based neutron beams; accelerator-based neutron beams; and dosimetry and treatment planning. Individual projects are processed separately for the databases. (CBS)

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

    PubMed Central

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

    2010-01-01

    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. Inmost 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

  18. 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

  19. Evaluation of beam delivery and ripple filter design for non-isocentric proton and carbon ion therapy

    NASA Astrophysics Data System (ADS)

    Grevillot, L.; Stock, M.; Vatnitsky, S.

    2015-10-01

    This study aims at selecting and evaluating a ripple filter design compatible with non-isocentric proton and carbon ion scanning beam treatment delivery for a compact nozzle. The use of non-isocentric treatments when the patient is shifted as close as possible towards the nozzle exit allows for a reduction in the air gap and thus an improvement in the quality of scanning proton beam treatment delivery. Reducing the air gap is less important for scanning carbon ions, but ripple filters are still necessary for scanning carbon ion beams to reduce the number of energy steps required to deliver homogeneous SOBP. The proper selection of ripple filters also allows a reduction in the possible transverse and depth-dose inhomogeneities that could appear in non-isocentric conditions in particular. A thorough review of existing ripple filter designs over the past 16 years is performed and a design for non-isocentric treatment delivery is presented. A unique ripple filter quality index (QIRiFi) independent of the particle type and energy and representative of the ratio between energy modulation and induced scattering is proposed. The Bragg peak width evaluated at the 80% dose level (BPW80) is proposed to relate the energy modulation of the delivered Bragg peaks and the energy layer step size allowing the production of homogeneous SOBP. Gate/Geant4 Monte Carlo simulations have been validated for carbon ion and ripple filter simulations based on measurements performed at CNAO and subsequently used for a detailed analysis of the proposed ripple filter design. A combination of two ripple filters in a series has been validated for non-isocentric delivery and did not show significant transverse and depth-dose inhomogeneities. Non-isocentric conditions allow a significant reduction in the spot size at the patient entrance (up to 350% and 200% for protons and carbon ions with range shifter, respectively), and therefore in the lateral penumbra in the patients.

  20. Evaluation of beam delivery and ripple filter design for non-isocentric proton and carbon ion therapy.

    PubMed

    Grevillot, L; Stock, M; Vatnitsky, S

    2015-10-21

    This study aims at selecting and evaluating a ripple filter design compatible with non-isocentric proton and carbon ion scanning beam treatment delivery for a compact nozzle. The use of non-isocentric treatments when the patient is shifted as close as possible towards the nozzle exit allows for a reduction in the air gap and thus an improvement in the quality of scanning proton beam treatment delivery. Reducing the air gap is less important for scanning carbon ions, but ripple filters are still necessary for scanning carbon ion beams to reduce the number of energy steps required to deliver homogeneous SOBP. The proper selection of ripple filters also allows a reduction in the possible transverse and depth-dose inhomogeneities that could appear in non-isocentric conditions in particular. A thorough review of existing ripple filter designs over the past 16 years is performed and a design for non-isocentric treatment delivery is presented. A unique ripple filter quality index (QIRiFi) independent of the particle type and energy and representative of the ratio between energy modulation and induced scattering is proposed. The Bragg peak width evaluated at the 80% dose level (BPW80) is proposed to relate the energy modulation of the delivered Bragg peaks and the energy layer step size allowing the production of homogeneous SOBP. Gate/Geant4 Monte Carlo simulations have been validated for carbon ion and ripple filter simulations based on measurements performed at CNAO and subsequently used for a detailed analysis of the proposed ripple filter design. A combination of two ripple filters in a series has been validated for non-isocentric delivery and did not show significant transverse and depth-dose inhomogeneities. Non-isocentric conditions allow a significant reduction in the spot size at the patient entrance (up to 350% and 200% for protons and carbon ions with range shifter, respectively), and therefore in the lateral penumbra in the patients. PMID:26418366

  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. 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.

  3. 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

  4. 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.

  5. Cancer stem cells: The potential of carbon ion beam radiation and new radiosensitizers (Review).

    PubMed

    Baek, Sung-Jae; Ishii, Hideshi; Tamari, Keisuke; Hayashi, Kazuhiko; Nishida, Naohiro; Konno, Masamitsu; Kawamoto, Koichi; Koseki, Jun; Fukusumi, Takahito; Hasegawa, Shinichiro; Ogawa, Hisataka; Hamabe, Atsushi; Miyo, Masaaki; Noguchi, Kozo; Seo, Yuji; Doki, Yuichiro; Mori, Masaki; Ogawa, Kazuhiko

    2015-11-01

    Cancer stem cells (CSCs) are a small population of cells in cancer with stem-like properties such as cell proliferation, multiple differentiation and tumor initiation capacities. CSCs are therapy-resistant and cause cancer metastasis and recurrence. One key issue in cancer therapy is how to target and eliminate CSCs, in order to cure cancer completely without relapse and metastasis. To target CSCs, many cell surface markers, DNAs and microRNAs are considered as CSC markers. To date, the majority of the reported markers are not very specific to CSCs and are also present in non-CSCs. However, the combination of several markers is quite valuable for identifying and targeting CSCs, although more specific identification methods are needed. While CSCs are considered as critical therapeutic targets, useful treatment methods remain to be established. Epigenetic gene regulators, microRNAs, are associated with tumor initiation and progression. MicroRNAs have been recently considered as promising therapeutic targets, which can alter the therapeutic resistance of CSCs through epigenetic modification. Moreover, carbon ion beam radiotherapy is a promising treatment for CSCs. Evidence indicates that the carbon ion beam is more effective against CSCs than the conventional X-ray beam. Combination therapies of radiosensitizing microRNAs and carbon ion beam radiotherapy may be a promising cancer strategy. This review focuses on the identification and treatment resistance of CSCs and the potential of microRNAs as new radiosensitizers and carbon ion beam radiotherapy as a promising therapeutic strategy against CSCs. PMID:26330103

  6. GPU-accelerated automatic identification of robust beam setups for proton and carbon-ion radiotherapy

    NASA Astrophysics Data System (ADS)

    Ammazzalorso, F.; Bednarz, T.; Jelen, U.

    2014-03-01

    We demonstrate acceleration on graphic processing units (GPU) of automatic identification of robust particle therapy beam setups, minimizing negative dosimetric effects of Bragg peak displacement caused by treatment-time patient positioning errors. Our particle therapy research toolkit, RobuR, was extended with OpenCL support and used to implement calculation on GPU of the Port Homogeneity Index, a metric scoring irradiation port robustness through analysis of tissue density patterns prior to dose optimization and computation. Results were benchmarked against an independent native CPU implementation. Numerical results were in agreement between the GPU implementation and native CPU implementation. For 10 skull base cases, the GPU-accelerated implementation was employed to select beam setups for proton and carbon ion treatment plans, which proved to be dosimetrically robust, when recomputed in presence of various simulated positioning errors. From the point of view of performance, average running time on the GPU decreased by at least one order of magnitude compared to the CPU, rendering the GPU-accelerated analysis a feasible step in a clinical treatment planning interactive session. In conclusion, selection of robust particle therapy beam setups can be effectively accelerated on a GPU and become an unintrusive part of the particle therapy treatment planning workflow. Additionally, the speed gain opens new usage scenarios, like interactive analysis manipulation (e.g. constraining of some setup) and re-execution. Finally, through OpenCL portable parallelism, the new implementation is suitable also for CPU-only use, taking advantage of multiple cores, and can potentially exploit types of accelerators other than GPUs.

  7. 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.

  8. 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.

  9. 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.

  10. Beam-hardening artifacts on computed tomography images caused by lanthanum carbonate hydrate in a patient on dialysis.

    PubMed

    Hayashi, Hiromitsu; Machida, Minoru; Sekine, Tetsuro; Yamaguchi, Hidenori; Kiriyama, Tomonari; Kumita, Shin-Ichiro

    2010-05-01

    Lanthanum carbonate hydrate is a nonaluminum, noncalcium phosphate binder containing lanthanum (La). It is effective in decreasing the serum phosphate level in patients on dialysis. Because the atomic number of the La contained in lanthanum carbonate hydrate is relatively high, at 57, this agent may cause strong artifacts on computed tomography (CT) images, which may be mistakenly interpreted as foreign bodies. We recently performed CT examination of a patient on Fosrenol chewable tablets (i.e., lanthanum carbonate hydrate). The CT images were difficult to evaluate because of strong beam hardening artifacts, and differentiation from foreign body aspiration was required. We report here our experience and a discussion of the characteristics of this artifact. PMID:20512553

  11. Studies on the Performance of RC Beam-Column Joints Strengthened Using Different Composite Materials

    NASA Astrophysics Data System (ADS)

    Sheela, S.; Anu Geetha, B.

    2012-02-01

    Many reinforced concrete structures in our country are in a deteriorated or distressed state. Hence strengthening such structures or reducing the load limit on them is becoming necessary to extend their service life. Beam-column joint is the crucial zone in a reinforced concrete moment resisting frame since it is subjected to large forces during severe ground shaking. In the present study, an attempt has been made to determine the cost-effective composite material and optimum number of layers of composite material for strengthening beam-column joints. Specimens were strengthened using ferrocement, glass fibre reinforced polymer (GFRP) and carbon fibre reinforced polymer (CFRP) and studied their behaviour under static as well as cyclic loading. It was found that the rotation at ultimate moment of all the strengthened beam-column joints were greater than that of the control specimens. The specimens strengthened with more number of layers of strengthening material showed better moment-rotation characteristics. The joints strengthened using GFRP showed better performance in terms of ultimate load, moment rotation characteristics, ductility, energy absorption capacity and strength-to-cost ratio, when compared to that of the specimens strengthened with other composite materials. However, CFRP strengthened specimens showed good ductility and better cracking characteristics and prevented the failure at the joint.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. 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. PMID:24593646

  14. 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.

  15. 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)

  16. 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.

  17. 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.

  18. 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.

  19. Evaluation of w values for carbon beams in air, using a graphite calorimeter.

    PubMed

    Sakama, Makoto; Kanai, Tatsuaki; Fukumura, Akifumi; Abe, Kyoko

    2009-03-01

    Despite recent progress in carbon therapy, accurate values for physical data such as the w value in air or stopping power ratios for ionization chamber dosimetry have not been obtained. The absorbed dose to graphite obtained with the graphite calorimeter was compared with that obtained using the ionization chambers following the IAEA protocol in order to evaluate the w values in air for mono-energetic carbon beams of 135, 290, 400 and 430 MeV/n. Two cylindrical chambers (PTW type 30001 and PTW type 30011, Farmer) and two plane-parallel chambers (PTW type 23343, Markus and PTW type 34001, Roos) calibrated by the absorbed dose to graphite and exposure to the (60)Co photon beam were used. The comparisons to our calorimeter measurements revealed that, using the ionization chambers, the absorbed dose to graphite comes out low by 2-6% in this experimental energy range and with these chamber types and calibration methods. In the therapeutic energy range, the w values in air for carbon beams indicated a slight energy dependence; we, however, assumed these values to be constant for practical use because of the large uncertainty and unknown perturbation factors of the ionization chambers. The w values in air of the carbon beams were evaluated to be 35.72 J C(-1) +/- 1.5% in the energy range used in this study. This value is 3.5% larger than that recommended by the IAEA TRS 398 for heavy-ion beams. Using this evaluated result, the absorbed dose to water in the carbon beams would be increased by the same amount. PMID:19174597

  20. 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.

  1. 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.

  2. Some Aspects of the Two Beam Performance of DCI

    SciTech Connect

    Krishnagopal, S.; Siemann, R.H.

    1991-09-01

    The results of beam-beam simulations that model DCI operating as an e{sup +}e{sup -} collider are reported. The simulation techniques, including a new procedure for incorporating synchrotron radiation, are described. Phase advance errors between the interaction points explain the beam-beam limit at the operating point q{sub x} = q{sub y} = 0.725 (q denotes the fractional part of the tune). The effects of radiation damping are also studied near that operating point. Simulation and experiments disagree in a second operating region, q{sub x} = q{sub y} {approx} 0.795, indicating additional physics outside the scope of our model.

  3. Preliminary studies of PQS PET detector module for dose verification of carbon beam therapy

    NASA Astrophysics Data System (ADS)

    Kim, H.-I.; An, S. Jung; Lee, C. Y.; Jo, W. J.; Min, E.; Lee, K.; Kim, Y.; Joung, J.; Chung, Y. H.

    2014-05-01

    PET imaging can be used to verify dose distributions of therapeutic particle beams such as carbon ion beams. The purpose of this study was to develop a PET detector module which was designed for an in-beam PET scanner geometry integrated into a carbon beam therapy system, and to evaluate its feasibility as a monitoring system of patient dose distribution. A C-shaped PET geometry was proposed to avoid blockage of the carbon beam by the detector modules. The proposed PET system consisted of 14 detector modules forming a bore with 30.2 cm inner diameter for brain imaging. Each detector module is composed of a 9 × 9 array of 4.0 mm × 4.0 mm × 20.0 mm LYSO crystal module optically coupled with four 29 mm diameter PMTs using Photomultiplier-quadrant-sharing (PQS) technique. Because the crystal pixel was identified based upon the distribution of scintillation lights of four PMTs, the design of the reflector between crystal elements should be well optimized. The optical design of reflectors was optimized using DETECT2000, a Monte Carlo code for light photon transport. A laser-cut reflector set was developed using the Enhanced Specular Reflector (ESR, 3M Co.) mirror-film with a high reflectance of 98% and a thickness of 0.064 mm. All 81 crystal elements of detector module were identified. Our result demonstrates that the C-shaped PET system is under development and we present the first reconstructed image.

  4. Interfacial electrical properties of ion-beam sputter deposited amorphous carbon on silicon

    NASA Technical Reports Server (NTRS)

    Khan, A. A.; Woollam, J. A.; Chung, Y.; Banks, B.

    1983-01-01

    Amorphous, 'diamond-like' carbon films have been deposited on Si substrates, using ion-beam sputtering. The interfacial properties are studied using capacitance and conductance measurements. Data are analyzed using existing theories for interfacial electrical properties. The density of electronic states at the interface, along with corresponding time constants are determined.

  5. Protective effects of shikonin on brain injury induced by carbon ion beam irradiation in mice.

    PubMed

    Gan, Lu; Wang, Zhen Hua; Zhang, Hong; Zhou, Rong; Sun, Chao; Liu, Yang; Si, Jing; Liu, Yuan Yuan; Wang, Zhen Guo

    2015-02-01

    Radiation encephalopathy is the main complication of cranial radiotherapy. It can cause necrosis of brain tissue and cognitive dysfunction. Our previous work had proved that a natural antioxidant shikonin possessed protective effect on cerebral ischemic injury. Here we investigated the effects of shikonin on carbon ion beam induced radiation brain injury in mice. Pretreatment with shikonin significantly increased the SOD and CAT activities and the ratio of GSH/GSSG in mouse brain tissues compared with irradiated group (P<0.01), while obviously reduced the MDA and PCO contents and the ROS levels derived from of the brain mitochondria. The shikonin also noticeably improved the spatial memory deficits caused by carbon ion beam irradiation. All results demonstrated that shikonin could improve the irradiated brain injury which might resulted from its modulation effects on the oxidative stress induced by the 12C6+ ion beam. PMID:25716567

  6. 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.

  7. 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.

  8. Lifetime dependence of nitrided carbon stripper foils on sputter angle during N+ ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Sugai, I.; Oyaizu, M.; Takeda, Y.; Kawakami, H.; Kawasaki, K.; Hattori, T.; Kadono, T.

    2015-09-01

    We fabricated high-lifetime thin nitride carbon stripper (NCS) foils with high nitrogen contents using ion-beam sputtering with reactive nitrogen gas and investigated the dependence of their lifetimes on the sputter angle. The nitrogen in carbon foils plays a critical role in determining their lifetime. Therefore, in order to investigate the effects of the nitrogen level in NCS foils on foil lifetime, we measured the sputtering yield for different sputter angles at a sputtering voltage of 10 kV while using carbon-based targets. We also measured the nitrogen-to-carbon thickness ratios of the foils using Rutherford backscattering spectrometry. The foils made at a sputter angle of 15° using a glassy amorphous carbon target exhibited an average increase of 200-fold in lifetime when compared to commercially available foils.

  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. 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

  11. 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.

  12. 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.

  13. Experimental study on fatigue crack propagation rate of RC beam strengthened with carbon fiber laminate

    NASA Astrophysics Data System (ADS)

    Huang, Peiyan; Liu, Guangwan; Guo, Xinyan; Huang, Man

    2008-11-01

    The experimental research on fatigue crack propagation rate of reinforced concrete (RC) beams strengthened with carbon fiber laminate (CFL) is carried out by MTS system in this paper. The experimental results show that, the main crack propagation on strengthened beam can be summarized into three phases: 1) fast propagation phase; 2) steady propagation and rest phase; 3) unsteady propagation phase. The phase 2-i.e. steady propagation and rest stage makes up about 95% of fatigue life of the strengthened beam. The propagation rate of the main crack, da/dN, in phase 2 can be described by Paris formula, and the constant C and m can be confirmed by the fatigue crack propagation experiments of the RC beams strengthened with CFL under three-point bending loads.

  14. 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.

  15. 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

  16. Carbon and carbon-coated electrodes for multistage depressed collectors for electron-beam devices - A technology review

    NASA Technical Reports Server (NTRS)

    Curren, Arthur N.

    1986-01-01

    Various aspects of carbon and carbon-coated multistaged depressed collector (MDC) electrode technology are reviewed. The physical properties of untreated graphite electrodes, ion-textured graphite electrodes, and textured, carbon-coated copper electrodes, and surface treatment procedures for these electrodes are described. The secondary electron emissions of the three electrode types are analyzed. MDC fabrication methods are discussed. The performances of MDCs fabricated with untreated graphite electrodes, ion-textured graphite electrodes, and textured, carbon-coated copper electrodes are evaluated. MDC and TWT efficiency levels for tubes fabricated with the three materials are measured.

  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. Robust, easily shaped, and epoxy-free carbon-fiber-aluminum cathodes for generating high-current electron beams.

    PubMed

    Liu, Lie; Li, Limin; Wen, Jianchun; Wan, Hong

    2009-02-01

    This paper presents the construction of carbon-fiber-aluminum (CFA) cathode by squeezing casting and its applications for generating high-current electron beams to drive high-power microwave sources. The fabrication process avoided using epoxy, a volatile deteriorating the vacuum system. These cathodes had a higher hardness than conventional aluminum, facilitating machining. After surface treatment, carbon fibers became the dominator determining emission property. A multineedle CFA cathode was utilized in a triode virtual cathode oscillator (vircator), powered by a approximately 450 kV, approximately 400 ns pulse. It was found that 300-400 MW, approximately 250 ns microwave was radiated at a dominant frequency of 2.6 GHz. Further, this cathode can endure high-current-density emission without detectable degradation in performance as the pulse shot proceeded, showing the robust nature of carbon fibers as explosive emitters. Overall, this new class of cold cathodes offers a potential prospect of developing high-current electron beam sources. PMID:19256641

  19. Carbon ion beam focusing using laser irradiated heated diamond hemispherical shells

    SciTech Connect

    Offermann, Dustin T; Flippo, Kirk A; Gaillard, Sandrine A

    2009-01-01

    Experiments preformed at the Los Alamos National Laboratory's Trident Laser Facility were conducted to observe the acceleration and focusing of carbon ions via the TNSA mechanism using hemispherical diamond targets. Trident is a 200TW class laser system with 80J of 1 {micro}m, short-pulse light delivered in 0.5ps, with a peak intensity of 5 x 10{sup 20} W/cm{sup 2}. Targets where Chemical Vapor Deposition (CVD) diamonds formed into hemispheres with a radius of curvature of 400{micro}m and a thickness of 5{micro}m. The accelerated ions from the hemisphere were diagnosed by imaging the shadow of a witness copper mesh grid located 2mm behind the target onto a film pack located 5cm behind the target. Ray tracing was used to determine the location of the ion focal spot. The TNSA mechanism favorably accelerates hydrogen found in and on the targets. To make the carbon beam detectable, targets were first heated to several hundred degrees Celsius using a CW, 532nm, 8W laser. Imaging of the carbon beam was accomplished via an auto-radiograph of a nuclear activated lithium fluoride window in the first layer of the film pack. The focus of the carbon ion beam was determined to be located 630 {+-} 110 {micro}m from the vertex of the hemisphere.

  20. Optimizing the thermoelectric performance of zigzag and chiral carbon nanotubes

    PubMed Central

    2012-01-01

    Using nonequilibrium molecular dynamics simulations and nonequilibrium Green's function method, we investigate the thermoelectric properties of a series of zigzag and chiral carbon nanotubes which exhibit interesting diameter and chirality dependence. Our calculated results indicate that these carbon nanotubes could have higher ZT values at appropriate carrier concentration and operating temperature. Moreover, their thermoelectric performance can be significantly enhanced via isotope substitution, isoelectronic impurities, and hydrogen adsorption. It is thus reasonable to expect that carbon nanotubes may be promising candidates for high-performance thermoelectric materials. PMID:22325623

  1. 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.

  2. 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.

  3. 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. PMID:22596046

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Performance and beam characteristics of the Siemens Primus linear accelerator.

    PubMed

    Sontag, M R; Steinberg, T H

    1999-05-01

    Siemens Primus is a small footprint, klystron driven medical linear accelerator incorporating a compact solid state modulator. A double focused multileaf collimator (MLC) replaces the lower jaw. The first Primus in the world was installed at St. Jude Children's Research Hospital in early 1997 with x-ray energies of 6 and 15 MV and electron energies of 8, 10, 12, 15, 18, and 21 MeV. The 10 cm depth dose for a 100 cm SSD 10 X 10 cm2 beam is 68% and 77% for 6 and 15 MV x rays, respectively. For both x-ray energies, beam flatness is slightly better than the manufacturers specification of 3% and beam symmetry is considerably better than 1%. The double focus design of the MLC produces a sharp penumbra (5-7 mm at 6 MV and 6-8 mm at 15 MV), increasing modestly with beam size. MLC leaf leakage is less than 1.25%. The depths of the 80% depth dose for the six electron energies of 8, 10, 12, 15, 18, and 21 MeV are 2.6, 3.2, 4.0, 4.9, 6.0, and 7.4 cm, respectively. Beam flatness is typically 2%-3% for all electron energies except 21 MeV, where it reaches 4% for a 25 X 25 cm2 cone. Electron beam symmetry is better than 1% for all energies except 21 MeV, where it is equal to 1%. The results are stored electronically and may be retrieved using anonymous ftp from the American Institute of Physics, Physics Auxiliary Publication Service. PMID:10360534

  13. 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.

  14. Radiological characteristics of MRI-based VIP polymer gel under carbon beam irradiation

    NASA Astrophysics Data System (ADS)

    Maeyama, T.; Fukunishi, N.; Ishikawa, K. L.; Furuta, T.; Fukasaku, K.; Takagi, S.; Noda, S.; Himeno, R.; Fukuda, S.

    2015-02-01

    We study the radiological characteristics of VIP polymer gel dosimeters under carbon beam irradiation with energy of 135 and 290 AMeV. To evaluate dose response of VIP polymer gels, the transverse (or spin-spin) relaxation rate R2 of the dosimeters measured by magnetic resonance imaging (MRI) as a function of linear energy transfer (LET), rather than penetration depth, as is usually done in previous reports. LET is evaluated by use of the particle transport simulation code PHITS. Our results reveal that the dose response decreases with increasing dose-averaged LET and that the dose response-LET relation also varies with incident carbon beam energy. The latter can be explained by taking into account the contribution from fragmentation products.

  15. Advanced carbon-based material C60 modification using partially ionized cluster and energetic beams

    NASA Astrophysics Data System (ADS)

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

    1997-06-01

    Two processes have been undertaken using Partially ionized cluster deposition (PICBD) and energetic ion bombardment beams deposition (IBD) respectively. C60 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 C60 films to oxygen diffusion contamination will be improved. In the case of PICBD, the ionized C60 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 C60 films to synthesize the carbon nitride films.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Studies on PAN-based carbon fibers irradiated by Ar+ ion beams.

    PubMed

    Park, Soo-Jin; Seo, Min-Kang; Kim, Hak-Yong; Lee, Douk-Rae

    2003-05-15

    In this work, the effects of Ar+ ion beam irradiation on carbon fibers were studied using tensile and surface analytical techniques. The single-fiber pull-out test was executed in order to characterize the fiber/epoxy matrix interfacial adhesion. The Ar+ ion beam was irradiated using an ion-assisted reaction (IAR) method in reactive gas conditions under an oxygen environment with 1 x 10(16) ions/cm(2) Ar+ ion dose (ID), 6 sccm blown gas flow rate, and different ion beam energy intensities. From the experimental results, both the interfacial shear strength (IFSS) and fracture toughness (Gi) were found to increase with increasing Ar+ ion irradiation intensity. This was probably due to the fact that Ar+ ion beam irradiation on carbon fibers was effective in altering their surface physical chemistry and structural morphology, resulting in improved interfacial adhesion in the fiber/epoxy matrix. The reliability of single-fiber pull-out test data could be improved by statistical analysis using the Weibull distribution, which served to predict the variation of the mechanical interfacial properties in a composite system. PMID:16256547

  1. 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%.

  2. 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.

  3. Tilting of carbon encapsulated metallic nanocolumns in carbon-nickel nanocomposite films by ion beam assisted deposition

    SciTech Connect

    Krause, Matthias; Muecklich, Arndt; Zschornak, Matthias; Wintz, Sebastian; Gemming, Sibylle; Abrasonis, Gintautas; Oates, Thomas W. H.; Luis Endrino, Jose

    2012-07-30

    The influence of assisting low-energy ({approx}50-100 eV) ion irradiation effects on the morphology of C:Ni ({approx}15 at. %) nanocomposite films during ion beam assisted deposition (IBAD) is investigated. It is shown that IBAD promotes the columnar growth of carbon encapsulated metallic nanoparticles. The momentum transfer from assisting ions results in tilting of the columns in relation to the growing film surface. Complex secondary structures are obtained, in which a significant part of the columns grows under local epitaxy via the junction of sequentially deposited thin film fractions. The influence of such anisotropic film morphology on the optical properties is highlighted.

  4. Unusual High Oxygen Reduction Performance in All-Carbon Electrocatalysts

    PubMed Central

    Wei, Wei; Tao, Ying; Lv, Wei; Su, Fang-Yuan; Ke, Lei; Li, Jia; Wang, Da-Wei; Li, Baohua; Kang, Feiyu; Yang, Quan-Hong

    2014-01-01

    Carbon-based electrocatalysts are more durable and cost-effective than noble materials for the oxygen reduction reaction (ORR), which is an important process in energy conversion technologies. Heteroatoms are considered responsible for the excellent ORR performance in many carbon-based electrocatalysts. But whether an all-carbon electrocatalyst can effectively reduce oxygen is unknown. We subtly engineered the interfaces between planar graphene sheets and curved carbon nanotubes (G-CNT) and gained a remarkable activity/selectivity for ORR (larger current, and n = 3.86, ~93% hydroxide + ~7% peroxide). This performance is close to that of Pt; and the durability is much better than Pt. We further demonstrate the application of this G-CNT hybrid as an all-carbon cathode catalyst for lithium oxygen batteries.We speculate that the high ORR activity of this G-CNT hybrid stems from the localized charge separation at the interface of the graphene and carbon nanotube, which results from the tunneling electron transfer due to the Fermi level mismatch on the planar and curved sp2 surfaces. Our result represents a conceptual breakthrough and pioneers the new avenues towards practical all-carbon electrocatalysis. PMID:25189141

  5. 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.

  6. 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

  7. 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.

  8. Superior performance of cone beam tomography in detecting a calcaneus fracture

    PubMed Central

    Lohse, Christian; Catala-Lehnen, Philip; Regier, Marc; Heiland, Max

    2015-01-01

    Cone beam computed tomography is a state-of-the-art imaging tool, initially developed for dental and maxillofacial application. With its high resolution and low radiation dose, cone beam tomography has been expanding its application fields, for example, to diagnosis of traumata and fractures in the head and neck area. In this study, we demonstrate superior and satisfactory performance of cone beam tomography for the imaging of a calcaneus fracture in comparison to conventional X-ray and computed tomography. PMID:26605132

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

    SciTech Connect

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

    2011-04-23

    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 1 p{mu}A (6 x 10{sup 12} particles/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 N{sup 2} 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 15 MeV/nucleon. The equilibrium charge states extracted from the intersection of the lines of the two cross sections were promisingly higher than those in N{sub 2} 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 1 mg/cm{sup 2} of He gas should be accumulated to achieve a charge state higher than that of N{sub 2} gas, notwithstanding the difficulty in accumulation of this helium amount owing to its fast dispersion. However, we now

  11. 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

  12. 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

  13. A two-bunch beam position monitor performance evaluation

    SciTech Connect

    Traller, R.; Medvedko, E.; Smith, S.; Aiello, R.

    1998-12-01

    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 8{times}10{sup 10} particles per bunch. For PEP-II ({ital 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 2{times}10{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. {copyright} {ital 1998 American Institute of Physics.}

  14. 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.

  15. 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.

  16. 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.

  17. 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}.

  18. 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.

  19. Performance of the (n,{gamma})-Based Positron Beam Facility NEPOMUC

    SciTech Connect

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

    2009-01-28

    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 9.10{sup 8} e{sup +}/s is achieved (1 keV). The performance and applications of the facility are presented.

  20. 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.

  1. 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

  2. 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

  3. Performance of a fast acquisition system for in-beam PET monitoring tested with clinical proton beams

    NASA Astrophysics Data System (ADS)

    Piliero, M. A.; Bisogni, M. G.; Cerello, P.; Del Guerra, A.; Fiorina, E.; Liu, B.; Morrocchi, M.; Pennazio, F.; Pirrone, G.; Wheadon, R.

    2015-12-01

    In this work we present the performance of a fast acquisition system for in-beam PET monitoring during the irradiation of a PMMA phantom with a clinical proton beam. The experimental set-up was based on 4 independent detection modules. Two detection modules were placed at one side of a PMMA phantom and the other two modules were placed at the opposite side of the phantom. One detection module was composed of a Silicon Photon Multiplier produced by AdvanSiD coupled to a single scintillating LYSO crystal. The read-out system was based on the TOFPET ASIC managed by a Xilinx ML605 FPGA Evaluation Board (Virtex 6). The irradiation of the PMMA phantom was performed at the CNAO hadrontherapy facility (Pavia, Italy) with a 95 MeV pulsed proton beam. The pulsed time structure of the proton beam was reconstructed by each detection module. The β+ annihilation peak was successfully measured and the production of β+ isotopes emitters was observed as increasing number of 511 keV events detected during irradiation. Finally, after the irradiation, the half lives of the 11C and 15O radioactive isotopes were estimated.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Crystallization effects and diamond formation in amorphous carbon films under low energy ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Patsalas, P.; Logothetidis, S.

    2001-05-01

    The crystallization effects occurring in various types of amorphous carbon (a-C) thin films with different structure and bonding induced by post-growth low energy (<1.5 keV) Ar + ion beam irradiation are presented. Detailed X-ray diffraction (XRD) measurements were used to identify several allotropic forms of carbon such as graphite and diamond as well as SiC detected in a-C films after ion irradiation. The diamond and SiC nucleation occurs close to the a-C/Si interface, beyond the ion penetration depth suggesting a non-direct nucleation mechanism. The relative content, grain size, distribution and orientation of each particular crystalline phase in the films depend strongly on the microstructural characteristics of the as-grown films. We also consider the effects of ion energy and fluence and substrate material on the crystallization process in an effort to get a deeper insight of the fundamental mechanisms occurring during the interaction of various carbon materials with low energy ion beams.

  9. Soft-Templated Mesoporous Carbon-Carbon Nanotube Composites for High Performance Lithium-ion Batteries

    SciTech Connect

    Guo, Bingkun; Wang, Xiqing; Fulvio, Pasquale F.; Chi, Miaofang; Mahurin, Shannon M.; Sun, Xiao-Guang; Dai, Sheng

    2011-09-13

    Mesoporous carbon with homogeneously dispersed multi-walled carbon nanotubes (MWNTs) are synthesized via a one-step "brick and mortar" soft-templating approach. Nanocomposites exhibit a reversible lithium storage capacity of 900 mA h g⁻¹ and a good rate performance. Such homogeneous nanocomposites are ideal candidates for electric vehicle applications where high power and energy density are primary requirements.

  10. ASR DIAGNOSIS BY PETROGRAPHIC INVESTIGATION AND EVALUATION OF MECHANICAL PERFORMANCE OF ASR DETERIORATED PRETENSIONED PC BEAM

    NASA Astrophysics Data System (ADS)

    Tomiyama, Jun; Yamada, Kazuo; Kaneda, Kazuo; Iraha, Shigeo; Oshiro, Takeshi

    ASR diagnosis and evaluation of load carrying capacity have been performed on the pre-tensioned PC beam which was cut out of a national high way bridge. The bridge was replaced lately after 25years service due to ASR deterioration. Comprehensive investigations such as crack measurement, material strength test, petrographic investigation, beam bending test have been performed on the deteriorated beam. Cracks have been observed on all sides and the appearance has been classified as severe deterioration grade. Petrographic investigation concluded that the reacted mineral was mainly reactive cristobalite contained in andesite of fine aggregates and EPMA investigation found that the reaction seemed to be the final stage. The late expansive ASR has been superimposed by cryptocrystalline quartz in coarse aggregates and it is still in progress. Deteriorated concrete cores with no visual crack have reduced only 10% of compressive strength compared with design strength, but significant loss has been observed on the elastic modulus. The static bending load test on the deteriorated test beam showed 95% of design load capacity indicating that the visual deterioration on surfaces has affected slight damages at this moment. But loss of bending rigidity has been appeared on the deteriorated beam .after bending cracks have started. This comprehensive study including the petrographic diagnosis and the appraisal on mechanical performance of the deteriorated beam conclude that there is a possibility of ASR deterioration in progress and further loss of mechanical performance though the beam had some margin for loading capacity at this moment.

  11. 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

  12. 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.

  13. 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.

  14. Performance and measurements of the AGS and Booster beams

    SciTech Connect

    Weng, W.T.

    1996-06-01

    In May 1995, the AGS reached its upgrade intensity goal of 6{times}10{sup 13} ppp, the highest world intensity record for a proton synchrotron on a single pulse basis. At the same time, the Booster reached 2.2{times}10{sup 13} ppp surpassing the design goal of 1.5{times}10{sup 13} ppp due to the introduction of second harmonic cavity during injection. The critical accelerator manipulations, such as resonance stopband corrections, second harmonics cavity, direct rf feedback, gamma-transition jump, longitudinal phase space dilution, and transverse instability damping, will be described as well as some beam measurements. Possible future intensity and brightness upgrades will also be reported. {copyright} {ital 1996 American Institute of Physics.}

  15. Electroanalytical performance of carbon films with near-atomic flatness.

    PubMed

    Ranganathan, S; McCreery, R L

    2001-03-01

    Physicochemical and electrochemical characterization of carbon films obtained by pyrolyzing a commercially available photoresist has been performed. Photoresist spin-coated on to a silicon wafer was pyrolyzed at 1,000 degrees C in a reducing atmosphere (95% nitrogen and 5% hydrogen) to produce conducting carbon films. The pyrolyzed photoresist films (PPF) show unusual surface properties compared to other carbon electrodes. The surfaces are nearly atomically smooth with a root-mean-square roughness of <0.5 nm. PPF have a very low background current and oxygen/carbon atomic ratio compared to conventional glassy carbon and show relatively weak adsorption of methylene blue and anthraquinone-2,6-disulfonate. The low oxygen/carbon ratio and the relative stability of PPF indicate that surfaces may be partially hydrogen terminated. The pyrolyzed films were compared to glassy carbon (GC) heat treated under the same conditions as pyrolysis to evaluate the electroanalytical utility of PPF. Heterogeneous electron-transfer kinetics of various redox systems were evaluated. For Ru(NH3)6(3+/2+), Fe(CN)6(3-/4-), and chlorpromazine, fresh PPF surfaces show electron-transfer rates similar to those on GC, but for redox systems such as Fe3+/2+, ascorbic acid, dopamine, and oxygen, the kinetics on PPF are slower. Very weak interactions between the PPF surface and these redox systems lead to their slow electron-transfer kinetics. Electrochemical anodization results in a simultaneous increase in background current, adsorption, and electron-transfer kinetics. The PPF surfaces can be chemically modified via diazonium ion reduction to yield a covalently attached monolayer. Such a modification could help in the preparation of low-cost, high-volume analyte-specific electrodes for diverse electroanalytical applications. Overall, pyrolysis of the photoresist yields an electrode surface with properties similar to a very smooth version of glassy carbon, with some important differences in surface

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    El-Taly, Boshra

    2016-03-01

    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.

  18. Design and performance of an automated video-based laser beam alignment system

    SciTech Connect

    Rundle, W.J. ); Kartz, M.W. ); Bliss, E.S.; English, R.E. Jr.; Peterson, R.L.; Thompson, G.R.; Uhlich, D.M. )

    1992-07-14

    This paper describes the design and performance of an automated, closed-loop, laser beam alignment system. Its function is to sense a beam alignment error in a laser beam transport system and automatically steer mirrors preceding the sensor location as required to maintain beam alignment. The laser beam is sampled by an optomechanical package which uses video cameras to sense pointing and centering errors. The camera outputs are fed to an image processing module, which includes video digitizers and uses image storage and software to sense the centroid of the image. Signals are sent through a VMEbus to an optical device controller'' (ODC), which drives stepper-motor actuators on mirror mounts preceding the beam-sampling location to return the beam alignment to the prescribed condition. Photodiodes are also used to extend the control bandwidth beyond that which is achievable with video cameras. This system has been operated at LLNL in the Atomic Vapor Laser Isotope Separation (AVLIS) program to maintain the alignment of copper and dye laser beams, the latter to within [plus minus]2 [mu]r in pointing and less than 1 mm in centering. The optomechanical design of the instrumented package, which includes lens, mirror, and video mounts in a rigid housing, the automated control system architecture, and the performance of this equipment is described.

  19. Design and performance of an automated video-based laser beam alignment system

    SciTech Connect

    Rundle, W.J.; Kartz, M.W.; Bliss, E.S.; English, R.E. Jr.; Peterson, R.L.; Thompson, G.R.; Uhlich, D.M.

    1992-07-14

    This paper describes the design and performance of an automated, closed-loop, laser beam alignment system. Its function is to sense a beam alignment error in a laser beam transport system and automatically steer mirrors preceding the sensor location as required to maintain beam alignment. The laser beam is sampled by an optomechanical package which uses video cameras to sense pointing and centering errors. The camera outputs are fed to an image processing module, which includes video digitizers and uses image storage and software to sense the centroid of the image. Signals are sent through a VMEbus to an ``optical device controller`` (ODC), which drives stepper-motor actuators on mirror mounts preceding the beam-sampling location to return the beam alignment to the prescribed condition. Photodiodes are also used to extend the control bandwidth beyond that which is achievable with video cameras. This system has been operated at LLNL in the Atomic Vapor Laser Isotope Separation (AVLIS) program to maintain the alignment of copper and dye laser beams, the latter to within {plus_minus}2 {mu}r in pointing and less than 1 mm in centering. The optomechanical design of the instrumented package, which includes lens, mirror, and video mounts in a rigid housing, the automated control system architecture, and the performance of this equipment is described.

  20. Improving the electrochemical performance of carbon filaments by solvent cleansing

    SciTech Connect

    Shui, X.; Chung, D.D.L.; Frysz, C.A.

    1995-12-31

    Found inherent in the submicron-diameter vapor-grown carbon filament fabrication process was a tarry residue, which comprised polyaromatic hydrocarbons. Cyclic voltammetry conducted using carbon working electrodes and an iron cyanide electrolyte showed that the residue harmed the electrochemical performance. Removal of the residue from the filaments using a solvent resulted in increases in the electron transfer rate (to values as high as 0.2 cm/s) and reversibility of the iron cyanide redox species, increase in the packing density and decrease in the filament-filament contact electrical resistivity.

  1. 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.

  2. ENGINEERED INTERFACE CHEMISTRY TO IMPROVE THE MECHANICAL PROPERTIES OF CARBON FIBER COMPOSITES CURED BY ELECTRON BEAM

    SciTech Connect

    Vautard, Frederic; Grappe, Hippolyte A.; Ozcan, Soydan

    2014-01-01

    A reactive sizing was designed to achieve high levels of interfacial adhesion and mechanical properties with a carbon fiber-acrylate system cured by electron beam (EB). The sizing was made of a partially cured epoxy sizing with a high density of pendant functional groups (acrylate functionality) able to generate a covalent bonding with the matrix. The interlaminar shear strength was clearly improved from 61 MPa to 81 MPa (+ 33 %) without any post-processing, reaching a similar value to the one obtained with the same system cured by a thermal treatment. Observation of the fracture profiles clearly highlighted a change in the fracture mechanism from a purely adhesive failure to a cohesive failure. Such improvements of the mechanical properties of carbon fiber composites cured by EB, without any post-cure, have not been reported previously to the best of our knowledge. This constitutes a breakthrough for the industrial development of composites EB curing.

  3. 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.

  4. 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.

  5. 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.

  6. Performance of Doublet III neutral beam injector cryopumping system

    SciTech Connect

    Langhorn, A.R.; Kim, J.; Tupper, M.L.; Williams, J.P.; Fasolo, J.

    1984-04-01

    The Doublet III neutral beam injector system is based on three beamlines; each beamline employs two 80 kV/80 A hydrogen ion sources. Two liquid helium (LHe) cooled cryopanel arrays were designed as an integral part of the beamline in order to provide high differential pumping of hydrogen gas along the beamline. The cryopanel arrays consist of a front (nearer to the torus) disk panel (3 m/sup 2/ each side) with liquid nitrogen (LN/sub 2/) cooled chevrons and a rear cylindrical panel of modified Santeler panels (8 m/sup 2/) which also employs LN/sub 2/ cooled surfaces shielding LHe cooled surfaces. These cryopanels are piped in series. The LHe delivery is based on a closed-loop, forced-flow scheme intended for variable panel temperatures (3.7 to 4.3 K). It uses small tubes for mechanical flexibility and thermal resiliency providing ease of economic defrosting. The cryogenic system consists of a liquefier (100 l/h), a large Dewar, a heat exchanger, and a liquid ring pump. Three beamlines are serviced simultaneously by the system. Pumping speeds measured locally at ionization gauges, were well in excess of the 1.4 x 10/sup 6/ l/s design goal.

  7. Enhanced magnetorheological performance of highly uniform magnetic carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Lee, Seungae; Shin, Keun-Young; Jang, Jyongsik

    2015-05-01

    Magnetic carbon nanoparticles (MC NPs) are prepared on a multi-gram scale through carbonization of iron-doped polypyrrole nanoparticles (PPy NPs). Three different-sized MC NPs (ca. 40, 60 and 90 nm) are prepared and adopted as dispersing materials for magnetorheological (MR) fluids to investigate the influence of particle size on MR properties. The MC NP-based MR fluids exhibit outstanding MR performances compared to the conventional magnetic carbon material-based fluids. In addition, the MR activities are enhanced with decreasing particle diameter and increasing applied magnetic field strength. Furthermore, anti-sedimentation properties are examined in order to achieve in-depth insight into the effect of the particle size on MR fluids.Magnetic carbon nanoparticles (MC NPs) are prepared on a multi-gram scale through carbonization of iron-doped polypyrrole nanoparticles (PPy NPs). Three different-sized MC NPs (ca. 40, 60 and 90 nm) are prepared and adopted as dispersing materials for magnetorheological (MR) fluids to investigate the influence of particle size on MR properties. The MC NP-based MR fluids exhibit outstanding MR performances compared to the conventional magnetic carbon material-based fluids. In addition, the MR activities are enhanced with decreasing particle diameter and increasing applied magnetic field strength. Furthermore, anti-sedimentation properties are examined in order to achieve in-depth insight into the effect of the particle size on MR fluids. Electronic supplementary information (ESI) available: The reaction mechanism at each step, and high-resolution TEM and SAED pattern analysis. See DOI: 10.1039/c4nr07168a

  8. Thermally induced transformations of amorphous carbon nanostructures fabricated by electron beam induced deposition.

    PubMed

    Kulkarni, Dhaval D; Rykaczewski, Konrad; Singamaneni, Srikanth; Kim, Songkil; Fedorov, Andrei G; Tsukruk, Vladimir V

    2011-03-01

    We studied the thermally induced phase transformations of electron-beam-induced deposited (EBID) amorphous carbon nanostructures by correlating the changes in its morphology with internal microstructure by using combined atomic force microscopy (AFM) and high resolution confocal Raman microscopy. These carbon deposits can be used to create heterogeneous junctions in electronic devices commonly known as carbon-metal interconnects. We compared two basic shapes of EBID deposits: dots/pillars with widths from 50 to 600 nm and heights from 50 to 500 nm and lines with variable heights from 10 to 150 nm but having a constant length of 6 μm. We observed that during thermal annealing, the nanoscale amorphous deposits go through multistage transformation including dehydration and stress-relaxation around 150 °C, dehydrogenation within 150-300 °C, followed by graphitization (>350 °C) and formation of nanocrystalline, highly densified graphitic deposits around 450 °C. The later stage of transformation occurs well below commonly observed graphitization for bulk carbon (600-800 °C). It was observed that the shape of the deposits contribute significantly to the phase transformations. We suggested that this difference is controlled by different contributions from interfacial footprints area. Moreover, the rate of graphitization was different for deposits of different shapes with the lines showing a much stronger dependence of its structure on the density than the dots. PMID:21319745

  9. 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

  10. 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.

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

    PubMed

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

    1998-01-01

    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/micrometer and 77 keV/micrometer ) and 200 kV 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/micrometer beams and 2.5 to 2.9 for 77 keV/micrometer beams. The induction rate of non-rejoining PCC breaks per cell per Gy was found to be highest for the 77 keV/micrometer 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. PMID:11542786

  12. 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.

  13. Approaching maximal performance of longitudinal beam compression in induction accelerator drivers

    SciTech Connect

    Mark, J.W.K.; Ho, D.D.M.; Brandon, S.T.; Chang, C.L.; Drobot, A.T.; Faltens, A.; Lee, E.P.; Krafft, G.A.

    1986-05-27

    Longitudinal beam compression is an integral part of the US induction accelerator development effort for heavy ion fusion. Producing maximal performance for key accelerator components is an essential element of the effort to reduce driver costs. We outline here initial studies directed towards defining the limits of final beam compression including considerations such as: maximal available compression, effects of longitudinal dispersion and beam emittance, combining pulse-shaping with beam compression to reduce the total number of beam manipulations, etc. The use of higher ion charge state Z greater than or equal to 3 is likely to test the limits of the previously envisaged beam compression and final focus hardware. A more conservative approach is to use additional beamlets in final compression and focus. On the other end of the spectrum of choices, alternate approaches might consider new final focus with greater tolerances for systematic momentum and current variations. Development of such final focus concepts would also allow more compact (and hopefully cheaper) hardware packages where the previously separate processes of beam compression, pulse-shaping and final focus occur as partially combined and nearly concurrent beam manipulations.

  14. 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.

  15. 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

  16. 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.

  17. Structure and properties of titanium surface layers after electron beam alloying with powder mixtures containing carbon

    NASA Astrophysics Data System (ADS)

    Lenivtseva, O. G.; Bataev, I. A.; Golkovskii, M. G.; Bataev, A. A.; Samoilenko, V. V.; Plotnikova, N. V.

    2015-11-01

    The structure and tribological properties of commercially pure titanium (cp-Ti) samples after non-vacuum electron beam surface alloying with carbon were studied. Two types of powders were used to introduce carbon in surface layer of cp-Ti: titanium carbide (TiC) and mixture of pure titanium and graphite ("Ti + C"). Single layer and multilayer coatings were studied. Application of electron beam for alloying provided cladding rate of 4.5 m2/h. The thickness of the clad coatings was 1.6-2.0 mm. The main phases received after "Ti + C" powder cladding were α-titanium, TiC, and retained graphite. In the samples obtained by cladding of TiC, graphite was not observed. A factor determining the microhardness and tribological properties of the cladded layer was the volume fraction of TiC. Maximum coating microhardness of 8 GPa was obtained by cladding of single layer of TiC powder or two layers of the "Ti + C" mixture. Two types of tests were carried out to evaluate the wear resistance of the samples. In friction tests against loose abrasive particles, the wear rate of the best samples was 9.3 times lower than that of cp-Ti. In wear tests using fixed abrasive particles, the relative wear resistance of the best samples was 2.3 times higher than that of cp-Ti.

  18. Physical properties of nitrogenated amorphous carbon films produced by ion-beam-assisted deposition

    NASA Astrophysics Data System (ADS)

    Rossi, Francois; Andre, Bernard; Veen, A. Van; Mijnarends, P. E.; Schut, H.; Labohm, F.; Delplancke, Marie Paule; Dunlop, Hugh; Anger, Eric

    1994-12-01

    Carbon films with up to 32 at.% N (a-C:N) have been prepared using an ion-beam-assisted magnetron, with an N2(+) beam at energies between 50 and 300 eV. The composition and density of the films vary strongly with the deposition parameters. Electron energy loss spectroscopy shows that these a-C:N films are mostly graphitic with up to 20% C Sp3 bonding. Rutherford backscattering spectroscopy and neutron depth profiling show that the density goes through a maximum as the average deposited energy per unit depth increases. X-ray photoelectron spectroscopy shows that nitrogen is mostly combined with carbon in triple (C(triple bond)N and double (C=N) bonds. Positron annihilation spectroscopy shows that the void concentration in the films goes through a minimum with deposited energy. These results are consistent with a densification induced by the collisions at low deposited energy, and damage-induced graphitization at high deposited energy values.

  19. 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

  20. 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.

  1. Effects of evolving surface morphology on yield during focused ion beam milling of carbon.

    SciTech Connect

    Mayer, Thomas Michael; Adams, David Price; Archuleta, Kim M.; Vasile, Michael J.

    2005-07-01

    We investigate evolving surface morphology during focused ion beam bombardment of C and determine its effects on sputter yield over a large range of ion dose (10{sup 17}-10{sup 19} ions/cm{sup 2}) and incidence angles ({Theta} = 0-80{sup o}). Carbon bombarded by 20 keV Ga{sup +} either retains a smooth sputtered surface or develops one of two rough surface morphologies (sinusoidal ripples or steps/terraces) depending on the angle of ion incidence. For conditions that lead to smooth sputter-eroded surfaces there is no change in yield with ion dose after erosion of the solid commences. However, for all conditions that lead to surface roughening we observe coarsening of morphology with increased ion dose and a concomitant decrease in yield. A decrease in yield occurs as surface ripples increase wavelength and, for large {Theta}, as step/terrace morphologies evolve. The yield also decreases with dose as rippled surfaces transition to have steps and terraces at {Theta} = 75{sup o}. Similar trends of decreasing yield are found for H{sub 2}O-assisted focused ion beam milling. The effects of changing surface morphology on yield are explained by the varying incidence angles exposed to the high-energy beam.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

    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.

  4. 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.

  5. 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.

  6. {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.

  7. The emission carbonate crystallite and oxide cathode performance in electron tubes

    NASA Astrophysics Data System (ADS)

    Shafer, Don; Turnbull, John

    Emission from an oxide cathode is dependent upon the ratio of alkaline earth carbonates present at the cathodes surface. The method by which each carbonate is made plays a key role in its function in a cathode. Other factors effecting the performance of the oxide cathode are the type of constituents in the base metal. These constituents play key roles in barium diffusion and evaporation. It has been found that the crystalline structure of the alkaline earth carbonates affects the life of oxide cathode tubes. The rates of diffusion and evaporation of alkaline earth oxides, were studied with the use of the SEM-electron beam probe and energy dispersive X-ray Edax. Cathode surfaces to the depths of 1000 Å (approximately 200 atomic layers) were scanned. Many cathodes were studied after conversion from carbonates to oxides. It was found that barium oxide evaporated to 1/3 of the original formulation at oxide conversion. This diffusion and evaporation reaction took place throughout tube life. This work has shown that the crystal size, structure, and composition may be modified to lengthen the BaO half life and therefore lengthen the overall life of the electron tube.

  8. 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

  9. 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

  10. The influence of lateral beam profile modifications in scanned proton and carbon ion therapy: a Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Parodi, K.; Mairani, A.; Brons, S.; Naumann, J.; Krämer, M.; Sommerer, F.; Haberer, T.

    2010-09-01

    Scanned ion beam delivery promises superior flexibility and accuracy for highly conformal tumour therapy in comparison to the usage of passive beam shaping systems. The attainable precision demands correct overlapping of the pencil-like beams which build up the entire dose distribution in the treatment field. In particular, improper dose application due to deviations of the lateral beam profiles from the nominal planning conditions must be prevented via appropriate beam monitoring in the beamline, prior to the entrance in the patient. To assess the necessary tolerance thresholds of the beam monitoring system at the Heidelberg Ion Beam Therapy Center, Germany, this study has investigated several worst-case scenarios for a sensitive treatment plan, namely scanned proton and carbon ion delivery to a small target volume at a shallow depth. Deviations from the nominal lateral beam profiles were simulated, which may occur because of misaligned elements or changes of the beam optic in the beamline. Data have been analysed with respect to the lateral penumbra, homogeneity and coverage of the dose deposition in the target volume. The results indicate that homogeneity is not seriously compromised by extremely narrow profiles for the standard planning choices of the lateral raster scan stepping and dose grid. Differently, broad beam distributions can significantly deteriorate the conformality of the dose delivery and too large increases (above ≈150-200% of the nominal spotsize) must be prevented.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

    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.

  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. 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.

  15. Response of the FBX system to a carbon beam: its potential as a dosimeter in heavy particle radiotherapy.

    PubMed

    Semwal, M K; Banerjee, Milan; Sarma, Asiti; Vidyasagar, P B

    2002-06-21

    The FBX aqueous chemical dosimeter contains 0.2 mol m(-3) ferrous ammonium sulphate, 5.0 mol m(-3) benzoic acid and 0.20 mol m(-3) xylenol orange in 40.0 mol m(-3) sulphuric acid. The dosimeter can measure photon and electron doses in the range 0.1 to 3000 cGy in radiotherapy. The response of this dosimeter was measured for a 53.2 MeV carbon beam in the present work. Our initial result indicates that the sensitivity of the FBX system to the carbon beam as compared to cobalt-60 gamma rays is 25.5%, and thus we believe that the FBX system could be a useful dosimeter for carbon beams and similar heavy ions considered useful in radiotherapy. PMID:12118611

  16. 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.

  17. 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.

  18. Ion Beam Optimized Mechanical Characteristics of Glassy Polymeric Carbon for Medical Applications

    NASA Astrophysics Data System (ADS)

    Rodrigues, M. G.; da Cruz, N. C.; Rangel, E. C.; Zimmerman, R. L.; Ila, D.; Poker, D. B.; Hensley, D. K.

    2003-08-01

    Glassy Polymeric Carbon (GPC) has medical applications owing to its inertness and biocompatible characteristics. Commercial GPC prosthetics include mitral, aortic and hydrocephalic valves. Surface treatment of GPC increases the adhesion of endothelic tissue on GPC and avoids the occurrence of thrombus in cardiac implant. In this work, ion beam was used to improve the mechanical characteristics of GPC surface. Hardness was measured as a function of depth in precursor and GPC samples heat treated from 300 to 2500 °C before and after bombardment with energetic ions of silicon, carbon, oxygen and gold at energies of 5, 6, 8 and 10 MeV and fluences between 1.0×1013 and 1.0×1016 ions/cm2. Comparison shows that hardness increases of the bombarded samples depend on heat treatment temperature. We verify that ion bombardment promotes carbonization due to an increased linkage between the chains of the polymeric material in lateral groups that are more numerous for samples heat treated to 700 °C.

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

    PubMed

    Mori, Shinichiro; Furukawa, Takuji

    2016-05-21

    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. PMID:27100312

  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

    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. PMID:25650520

  3. 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

  4. Beam tail effect of a performance-enhanced EC-ITC RF gun

    NASA Astrophysics Data System (ADS)

    Hu, Tong-Ning; Pei, Yuan-Ji; Qin, Bin; Chen, Qu-Shan

    2013-12-01

    The beam tail effect of multi-bunches will influence the electron beam performance in a high intensity thermionic RF gun. Beam dynamic calculations that illustrate the working states of single beam tail and multi-pulse feed-in of a performance-enhanced EC-ITC (external cathode independent tunable cavity) RF gun for an FEL (free electron laser) injector are performed to estimate the extracted bunch properties. By using both Parmela and homemade MATLAB codes, the effects of a single beam tail as well as interactions of multi-pulses are analyzed, where a ring-based electron algorithm is adopted to calculated RF fields and the space-charge field. Furthermore, the procedure of unexpected deviated-energy particles mixed with an effective bunch head is described by the MATLAB code as well. As a result, the performance-enhanced EC-ITC RF gun is proved to have the capability to extract continual stable bunches suitable for a high requirement THz-FEL.

  5. Chemical investigations of isotope separation on line target units for carbon and nitrogen beams

    SciTech Connect

    Fraanberg, H.; Ammann, M.; Gaeggeler, H.W.; Koester, U.

    2006-03-15

    Radioactive ion beams (RIBs) are of significant interest in a number of applications. Isotope separation on line (ISOL) facilities provide RIB with high beam intensities and good beam quality. An atom that is produced within the ISOL target will first diffuse out from the target material. During the effusion towards the transfer line and into the ion source the many contacts with the surrounding surfaces may cause unacceptable delays in the transport and, hence, losses of the shorter-lived isotopes. We performed systematic chemical investigations of adsorption in a temperature and concentration regime relevant for ISOL targets and ion source units, with regard to CO{sub x} and NO{sub x} on Al{sub 2}O{sub 3} and SiO{sub 2}. These materials are potential construction materials for the above-mentioned areas. Off-line and on-line tests have been performed using a gas thermochromatography setup with radioactive tracers. The experiments were performed at the production of tracers for atmospheric chemistry (PROTRAC) facility at the Paul Scherrer Institute in Villigen, Switzerland.

  6. Performance of a scanning pencil-beam spaceborne scatterometer for ocean wind measurements

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Kennett, R. G.; Fuk, K.

    1988-01-01

    Simulation results show that a scatterometer design using two pencil beams scanning at different incidence angles measures the near-surface oceanic winds from a satellite better under most conditions than previous designs. The return signals from the ocean surface are much stronger than those from the fan beams used previously. Performance on a polar-orbiting satellite is compared with that of a fan beam spaceborne scatterometer. A wider and continuous swath is covered. The improvement in performance is higher at low wind speeds, so it is particularly suitable for measuring the low-mean-speed tropical wind fields. Performance on a low altitude tropic-orbiting platform such as the Space Station is also shown.

  7. 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.

  8. Ultra stable carbon fiber high power CO2 laser with high quality laser beam and AOM implementation

    NASA Astrophysics Data System (ADS)

    Bohrer, Markus

    2015-03-01

    High security printing as well as ultra high precision engraving need laser resonators with very stable laser beams (600 - 800W) especially in combination with AOMs. Based upon a unique carbon fiber structure - stable within the sub-micrometer range - a new resonator has been developed, accompanied by most recent thermo-mechanical FEM calculations. The resulting beam is evaluated on an automated optical bench allowing to optimize the complete beam path with collimators and AOM. Synchronous on-line evaluation with PyroCams and thus knowledge about how to minimize distortions within the nonlinear elements is presented in this paper.

  9. 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.

  10. 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

  11. Engineering heterojunctions with carbon nanostructures: towards high-performance optoelectronics

    NASA Astrophysics Data System (ADS)

    Wu, Judy Z.

    2015-08-01

    Low-dimensional carbon nanostructures such as nanotubes (CNTs) and graphene have excellent electronic, optoelectronic and mechanical properties, which provide fresh opportunities for designs of optoelectronic devices of extraordinary performance in addition to the benefits of low cost, large abundance, and light weight. This work investigates photodetectors made with CNTs and graphene with a particular focus on carbon-based nanohybrids aiming at a nanoscale control of photon absorption, exciton dissociation and charge transfer. Through several examples including graphene/GaSe-nanosheets, graphene/aligned ZnO nanorods, SWCNT/P3HT, and SWCNT/biomolecule, we show an atomic-scale control on the interfacial heterojunctions is the key to high responsivity and fast photoresponse in these nanohybrids optoelectronic devices.

  12. 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.

  13. 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.

  14. 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.

  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. PMID:25595622

  16. 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.

  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. 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.

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

    PubMed Central

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

    2014-01-01

    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. PMID:24870227

  20. 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.

  1. 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

  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. Preparation and electrochemical performance of ultra-short carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Xiao X.; Wang, Jian N.; Su, Lian F.

    Current carbon nanotubes (CNTs) are typically synthesized with micrometer lengths, low dispersion and low purity and thus oppose their applications in many fields. In this study, we make the first report on using a Fe compound (FeS) as a catalyst for controlling the length of CNTs to be less than 300 nm. This is achieved by dissolution of a proper proportion of ferrocene and thiophene in alcohol and pyrolysis of this solution at high temperature. Sulfur, resulting from the decomposition of thiophene, is shown to play key roles in promoting the growth of CNTs and limiting their length. The reason is suggested to be that FeS retards the dissociation of carbon source and diffusion of carbon in it as compared with pure Fe. Short CNTs from the present direct synthesis and from our previous solid-state cutting are used as an electrode material in Li-ion batteries and catalyst supports in fuel cells. Compared with conventional long CNTs, short CNTs show much better electrochemical performance. Due to the simplicity of the present synthetic technique, it may be used for mass production of short CNTs. Furthermore, the application of such a new material may be investigated in wide areas such as information technology, biomedicine, environmental and energy industries.

  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. 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.

  6. Design and Near-Field Measurement Performance Evaluation of the Sea Winds Dual- Beam Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Hussein, Z.; Rahmat-Samii, Y.; Kellogg, K.

    1997-01-01

    This paper presents the design and performance evaluation of a lightweight, composite material, elliptical-aperture, parabolic-reflector antenna. The performance characterization is obtained using the cylindrical near-field measurement facility at JPL as shown. The reflector has been designed and calibrated for the SeaWinds spaceborne scatterometer instrument. The instrument operates at Ku-band and is designed to accurately measure wind speed and direction over Earth's ocean surface. The SeaWinds antenna design requires two linearly polarized independent beams pointed at 40 deg.and 46 deg. from nadir as shown. The inner beam, pointed at 40 deg. from nadir, is horizontally polarized with 1.6 in x 1.8 in required beamwidths in the elevation and azimuth planes, respectively. The outer beam, pointed at 46 deg. from nadir, is vertically polarized with 1.4 in x 1.7 in required beamwidths. Noteworthy, the reflector boresight axis is pointed at 43 deg. from nadir. Both beams are required to have the first sidelobe level below -15 dB relative to the peak of the beam.

  7. Plasma and ion beam enhanced chemical vapour deposition of diamond and diamond-like carbon

    NASA Astrophysics Data System (ADS)

    Tang, Yongji

    WC-Co cutting tools are widely used in the machining industry. The application of diamond coatings on the surfaces of the tools would prolong the cutting lifetime and improves the manufacturing efficiency. However, direct chemical vapor deposition (CVD) of diamond coatings on WC-Co suffer from severe premature adhesion failure due to interfacial graphitization induced by the binder phase Co. In this research, a combination of hydrochloric acid (HCl) and hydrogen (H2) plasma pretreatments and a novel double interlayer of carbide forming element (CFE)/Al were developed to enhance diamond nucleation and adhesion. The results showed that both the pretreatments and interlayers were effective in forming continuous and adhesive nanocrystalline diamond coatings. The method is a promising replacement of the hazardous Murakami's regent currently used in WC-Co pretreatment with a more environmental friendly approach. Apart from coatings, diamond can be fabricated into other forms of nanostructures, such as nanotips. In this work, it was demonstrated that oriented diamond nanotip arrays can be fabricated by ion beam etching of as-grown CVD diamond. The orientation of diamond nanotips can be controlled by adjusting the direction of incident ion beam. This method overcomes the limits of other techniques in producing nanotip arrays on large areas with controlled orientation. Oriented diamond nano-tip arrays have been used to produce anisotropic frictional surface, which is successfully used in ultra-precision positioning systems. Diamond-like carbon (DLC) has many properties comparable to diamond. In this thesis, the preparation of alpha-C:H thin films by end-Hall (EH) ion source and the effects of ion energy and nitrogen doping on the microstructure and mechanical properties of the as-deposited thin films were investigated. The results have demonstrated that smooth and uniform alpha-C:H and alpha-C:H:N films with large area and reasonably high hardness and Young's modulus can be

  8. 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…

  9. 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.

  10. 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.

  11. Gold nanoclusters on amorphous carbon synthesized by ion-beam deposition

    SciTech Connect

    Thune, Elsa; Carpene, Ettore; Sauthoff, Katharina; Seibt, Michael; Reinke, Petra

    2005-08-01

    Gold clusters have been deposited by a monoenergetic, mass-selected ion beam with low energies (20-350 eV) on amorphous carbon substrates in order to minimize the influence of the surface crystallinity and the ion-induced structural changes. Gold has been used as a model system, due to the poor reactivity with carbon, to study the ion-energy dependence, the temporal evolution, and the influence of the temperature on the cluster distribution. The cluster size is very sensitive to the energy and the mean size strongly decreases from 4 to less than 1 nm as the ion energy increases. We can also note that the size distribution becomes broader. For impact energies below 100 eV, surface processes dominate the cluster nucleation and growth. If higher energies are used, an increasing number of ions is implanted below the surface and different processes control the cluster formation. When the energy increases above 350 eV, the cluster size drastically drops below 5 nm. The samples are analyzed with different methods such as atomic force microscopy, transmission electron microscopy, and x-ray photoelectron spectroscopy to determine their size distribution, composition, and structure.

  12. Development of the carbon foils as charge strippers for high-intensity uranium ion beams

    NASA Astrophysics Data System (ADS)

    Hasebe, Hiroo; Kuboki, Hironori; Okuno, Hiroki; Fukunishi, Nobuhisa; Kamigaito, Osamu; Imao, Hiroshi; Goto, Akira; Kase, Masayuki

    2011-11-01

    carbon foil (C-foil) is commonly used as a charge stripper in the heavy-ion accelerators. Since 2005, the polymer-coated carbon foils (PCC-foils) have been fabricated at Nishina Center to prepare larger and thicker C-foils than those previously used as charge strippers. However, the multi-layer PCC-foils did not have sufficiently long life-time. Since August 2009, a new magnetron sputtering system is used to fabricate a thick C-foil. The foils coated with polymer are used as strippers. Life-times of the new single-layer PCC-foils under the uranium beam were measured in two configurations: at the first one a small piece of C-foil was attached to a fixed holder and in the second one a large C-foil was attached to a "rotating-cylinder stripper" device. The properties of the new single-layer PCC-foils and the results of the life-time measurements are reported in this contribution.

  13. 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.

  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. Effects of Ion Beam on Nanoindentation Characteristics of Glassy Polymeric Carbon Surface

    SciTech Connect

    Rodrigues, M. G.; Da Cruz, N. C.; Rangel, E. C.; Zimmerman, R. L.; Ila, Dr. Daryush; Poker, David B; Hensley, Dale K

    2005-01-01

    Glassy polymeric carbon (GPC) is a useful material for medical applications due to its chemical inertness and biocompatible characteristics. Mitral and aortic and hydrocephalic valves are examples of GPC prosthetic devices that have been fabricated and commercialized in Brazil. In this work, ion beam was used to improve the mechanical characteristics of GPC surface and therefore to avoid the propagation of microcracks where the cardiac valves are more fragile. A control group of phenolic resin samples heat-treated at 300, 400, 700, 1000, 1500, and 2500 C was characterized by measuring their hardness and Young's reduced elastic modulus with the depth of indentation. The control group was compared to results obtained with samples heat-treated at 700, 1000, and 1500 C and bombarded with energetic ions of silicon, carbon, oxygen, and gold at energies of 5, 6, 8, and 10 MeV, respectively, with fluences between 1.0 x 10{sup 13} and 1.0 x 10{sup 16} ions/cm{sup 2}. GPC nonbombarded samples showed that hardness depends on the heat treatment temperature (HTT), with a maximum hardness for heat treatment at 1000 C. The comparison between the control group and bombarded group also showed that hardness, after bombardment, had a greater increase for samples prepared at 700 C than for samples prepared at higher temperatures. The Young's elastic modulus presents an exponential relationship with depth. The parameters obtained by fitting depend on the HTT and on the ion used in the bombardment more than on energy and fluence. The hardness results show clearly that bombardment can promote carbonization, increase the linkage between the chains of the polymeric material, and promote recombination of broken bonds in lateral groups that are more numerous for samples heat-treated at 700 C.

  16. 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.

  17. 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

  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. 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. 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.

  1. 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.

  2. Optical design and performance of the X25 hybrid wiggler beam line at the NSLS

    SciTech Connect

    Berman, L.E.; Hastings, J.B.; Oversluizen, T.; Woodle, M.

    1991-01-01

    The X25 beam line at the National Synchrotron Light Source (NSLS) began full-power commissioning in 1990. It extracts radiation from a 27 pole hybrid wiggler, which produces up to 1.8 kW of total power with a peak horizontal density of 450 W/mrad and critical energy of 4.6 keV. The design and performance of the beam line optics are described, in particular the cooling of the first monochromator crystal. 28 refs., 5 figs.

  3. Performance Characterization and Vibration Testing of 30-cm Carbon-Carbon Ion Optics

    NASA Technical Reports Server (NTRS)

    Steven Snyder, John; Brophy, John R.

    2004-01-01

    Carbon-based ion optics have the potential to significantly increase the operable life and power ranges of ion thrusters because of reduced erosion rates compared to molybdenum optics. The development of 15-cm and larger diameter grids has encountered many problems, however, not the least of which is the ability to pass vibration testing. JPL has recently developed a new generation of 30-cm carbon-carbon ion optics in order to address these problems and demonstrate the viability of the technology. Perveance, electron backstreaming, and screen grid transparency data are presented for two sets of optics. Vibration testing was successfully performed on two different sets of ion optics with no damage and the results of those tests are compared to models of grid vibrational behavior. It will be shown that the vibration model is a conservative predictor of grid response and can accurately describe test results. There was no change in grid alignment as a result of vibration testing and a slight improvement, if any change at all, in optics performance.

  4. Electrical conductivity of cluster-assembled carbon/titania nanocomposite films irradiated by highly focused vacuum ultraviolet photon beams

    SciTech Connect

    Amati, M.; Lenardi, C.; Agostino, R. G.; Caruso, T.; Ducati, C.; La Rosa, S.; Bongiorno, G.; Cassina, V.; Podesta, P.; Ravagnan, L.; Piseri, P.; Milani, P.

    2007-03-15

    We investigated the electrical transport properties of nanostructured carbon and carbon/titanium oxide nanocomposite films produced by supersonic cluster beam deposition and irradiated by highly focused vacuum UV photon beam. We have observed a relevant increase of the density of states at Fermi level, suggesting that the films acquire a 'metallic' character. This is confirmed by the increment of the conductivity of four orders of magnitude for pure nanostructured carbon films and at least eight orders of magnitude for films containing 9 at. % of titanium. A partial reversibility of the process is observed by exposing the modified films to molecular oxygen or directly to air. We demonstrate the capability of writing micrometric conductive strips (2-3 {mu}m width and 60 {mu}m length) and controlling the variation of the conductivity as a function of the titanium concentration.

  5. Behaviour of fibre-reinforced high-performance concrete in exterior beam-column joint

    NASA Astrophysics Data System (ADS)

    Muthupriya, P.; Boobalan, S. C.; Vishnuram, B. G.

    2014-09-01

    This paper presents the effect of reinforced high performance concrete (HPC) in exterior beam-column joint with and without fibre under monotonic loading. In this experimental investigation, cross-diagonal bars have been provided at the joint for reducing the congestion of reinforcement in joints, and also M75 grade of concrete with optimum mix proportion of 10 % silica fume and 0.3 % glass fibre was used. Four exterior beam-column joint sub-assemblages were tested. The specimens were divided into two types based on the reinforcement detailing. Type A comprises two joint sub-assemblages with joint detailing as per construction code of practice in India (IS 456-2000), and Type B comprises two joint sub-assemblages with joint detailing as per ductile detailing code of practice in India (IS 13920-1993). In each group there was one specimen of control mix and the remaining one specimen of fibre-reinforced mix. All the test specimens were designed to satisfy the strong column-weak beam concept. The performances of specimens were compared with the control mix and the fibre-reinforced mix. The results show that exterior beam-column joint specimens with silica fume and glass fibre in the HPC mix showed better performance.

  6. 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.

  7. Investigating the energy harvesting capabilities of a hybrid ZnO nanowires/carbon fiber polymer composite beam.

    PubMed

    Masghouni, N; Burton, J; Philen, M K; Al-Haik, M

    2015-03-01

    Hybrid piezoelectric composite structures that are able to convert mechanical energy into electricity have gained growing attention in the past few years. In this work, an energy harvesting composite beam is developed by growing piezoelectric zinc oxide nanowires on the surface of carbon fiber prior to forming structural composites. The piezoelectric behavior of the composite beam was demonstrated under different vibration sources such as water bath sonicator and permanent magnet vibration shaker. The beam was excited at its fundamental natural frequency (43.2 Hz) and the open circuit voltage and the short circuit current were measured to be 3.1 mV and 23 nA, respectively. Upon connecting an optimal resistor (1.2 kΩ) in series with the beam a maximum power output 2.5 nW was achieved. PMID:25670370

  8. 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.

  9. Fatigue and post-fatigue performance of Fabry-Perot FOS installed on CFRP-strengthened RC-beams

    NASA Astrophysics Data System (ADS)

    Gheorghiu, Catalin; Labossiere, Pierre; Proulx, Jean

    2004-07-01

    There is a growing need for built-in monitoring systems for civil engineering infrastructures, due to problems such as increasing traffic loads and rising costs of maintenance and repair. Fibre optic sensors (FOS), capable of reading various parameters are promising candidates for life-long health monitoring of these structures. However, since FOS have only been introduced recently into the field of structural monitoring, their acceptance and widespread implementation will be conditioned by their durability under severe climatic and loading conditions. This paper reports on the performance of strain extrinsic FOS attached to carbon fibre reinforced polymer (CFRP) plates used to strengthen concrete structures. The specimens tested in this project are reinforced concrete (RC) beams with an additional external CFRP reinforcement. The FOS-instrumented beams were first subjected to fatigue loading for various numbers of cycles and load amplitudes. Then, they were tested monotonically to failure under four-point-bending. The test results provide an insight on the fatigue and post-fatigue behaviour of FOS used for monitoring reinforced concrete structures.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Enhanced thermoelectric performance of carbon nanotubes at elevated temperature.

    PubMed

    Jiang, P H; Liu, H J; Fan, D D; Cheng, L; Wei, J; Zhang, J; Liang, J H; Shi, J

    2015-11-01

    The electronic and transport properties of the (10, 0) single-walled carbon nanotube are studied by performing first-principles calculations and semi-classical Boltzmann theory. It is found that the (10, 0) tube exhibits a considerably large Seebeck coefficient and electrical conductivity which are highly desirable for good thermoelectric materials. Together with the lattice thermal conductivity predicted by non-equilibrium molecular dynamics simulations, the room temperature ZT value of the (10, 0) tube is estimated to be 0.15 for p-type carriers. Moreover, the ZT value exhibits strong temperature dependence and can reach to 0.77 at 1000 K. Such a ZT value can be further enhanced to as high as 1.9 by isotopic substitution and chemisorptions of hydrogen on the tube surface. PMID:26426972

  17. 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.

  18. 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

  19. Flexible high-performance carbon nanotube integrated circuits.

    PubMed

    Sun, Dong-ming; Timmermans, Marina Y; Tian, Ying; Nasibulin, Albert G; Kauppinen, Esko I; Kishimoto, Shigeru; Mizutani, Takashi; Ohno, Yutaka

    2011-03-01

    Carbon nanotube thin-film transistors are expected to enable the fabrication of high-performance, flexible and transparent devices using relatively simple techniques. However, as-grown nanotube networks usually contain both metallic and semiconducting nanotubes, which leads to a trade-off between charge-carrier mobility (which increases with greater metallic tube content) and on/off ratio (which decreases). Many approaches to separating metallic nanotubes from semiconducting nanotubes have been investigated, but most lead to contamination and shortening of the nanotubes, thus reducing performance. Here, we report the fabrication of high-performance thin-film transistors and integrated circuits on flexible and transparent substrates using floating-catalyst chemical vapour deposition followed by a simple gas-phase filtration and transfer process. The resulting nanotube network has a well-controlled density and a unique morphology, consisting of long (~10 µm) nanotubes connected by low-resistance Y-shaped junctions. The transistors simultaneously demonstrate a mobility of 35 cm(2) V(-1) s(-1) and an on/off ratio of 6 × 10(6). We also demonstrate flexible integrated circuits, including a 21-stage ring oscillator and master-slave delay flip-flops that are capable of sequential logic. Our fabrication procedure should prove to be scalable, for example, by using high-throughput printing techniques. PMID:21297625

  20. 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.

  1. Thermal and mechanical performance of a carbon-carbon composite spacecraft radiator

    NASA Astrophysics Data System (ADS)

    Kuhn, Jonathan L.; Benner, Steve M.; Butler, C. Dan; Silk, Eric A.

    1999-09-01

    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 cost 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 Earth Orbiter-1 (EO-1) spacecraft, scheduled for launch in late 1999. For EO-1, the CSRP designed and fabricated a Carbon-Carbon Radiator with carbon-carbon facesheets and aluminum honeycomb core, which will also serve as a structural shear panel.

  2. 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.

  3. 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

  4. Performance characteristics of a novel megavoltage cone-beam-computed tomography device.

    PubMed

    Fast, M F; Koenig, T; Oelfke, U; Nill, S

    2012-02-01

    In this work, the image quality of a novel megavoltage cone-beam-computed tomography (CBCT) scanner is compared to three other image-guided radiation therapy devices by analysing images of different-sized quality assurance phantoms. The following devices are compared in terms of image uniformity, signal-to-noise ratio, contrast-to-noise ratio (CNR), electron density to HU conversion, presampling modulation transfer function (MTF(pre)) and combined spatial resolution and noise (Q-factor): (i) the Siemens Artiste kilovoltage (kV) (121 kV) CBCT device, (ii) the Artiste treatment beam line (TBL), 6 MV, (iii) the Tomotherapy (3.5 MV) fan-beam CT and (iv) Siemens' novel approach using a carbon target for a dedicated imaging beam line (IBL), 4.2 MV. Machine settings were selected to produce the same imaging dose for all devices. For a head phantom, IBL scans display CNR values 2.6 ± 0.3 times higher than for the TBL at the same dose level (for a CT-number range of -200 to -60 HU). kV CBCT, on the other hand, displays CNR values 7.9 ± 0.3 times higher than the IBL. There was no significant deviation in spatial resolution between IBL, TBL and Tomotherapy in terms of 50% and 10% MTF(pre). For kV CBCT, the MTF(pre) was significantly higher than those for other devices. In our Q-factor analysis, the IBL (14.6) scores higher than the TBL (7.9) and Tomotherapy (9.7) due to its lower noise level. The linearity of electron density to HU conversion is demonstrated for different-sized phantoms. Employing the IBL instead of the TBL significantly reduces the imaging dose by up to a factor of 5 at a constant image quality level, providing an immediate benefit for the patient. PMID:22251668

  5. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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 (10B and 11B), beryllium ions (7Be), 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

  8. 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.

  9. 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.

  10. Increased tensile strength of carbon nanotube yarns and sheets through chemical modification and electron beam irradiation.

    PubMed

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

    2014-05-14

    The inherent strength of individual carbon nanotubes (CNTs) offers considerable opportunity for the development of advanced, lightweight composite structures. Recent work in the fabrication and application of 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 into that of sheets and yarns, where the bulk material strength is limited by intertube electrostatic attractions and slippage. The focus of this work was to assess postprocessing of CNT sheets and yarns to improve the macro-scale strength of these material forms. Both small-molecule functionalization and electron-beam irradiation were evaluated as means to enhance the tensile strength and Young's modulus of the bulk CNT materials. Mechanical testing revealed a 57% increase in tensile strength of CNT sheets upon functionalization compared with unfunctionalized sheets, while an additional 48% increase in tensile strength was observed when functionalized sheets were irradiated. Similarly, small-molecule functionalization increased tensile strength of yarn by up to 25%, whereas irradiation of the functionalized yarns pushed the tensile strength to 88% beyond that of the baseline yarn. PMID:24720450

  11. Spatial fragment distribution from a therapeutic pencil-like carbon beam in water

    NASA Astrophysics Data System (ADS)

    Matsufuji, Naruhiro; Komori, Masataka; Sasaki, Hitomi; Akiu, Kengo; Ogawa, Masako; Fukumura, Akifumi; Urakabe, Eriko; Inaniwa, Taku; Nishio, Teiji; Kohno, Toshiyuki; Kanai, Tatsuaki

    2005-07-01

    The latest heavy ion therapy tends to require information about the spatial distribution of the quality of radiation in a patient's body in order to make the best use of any potential advantage of swift heavy ions for the therapeutic treatment of a tumour. The deflection of incident particles is described well by Molière's multiple-scattering theory of primary particles; however, the deflection of projectile fragments is not yet thoroughly understood. This paper reports on our investigation of the spatial distribution of fragments produced from a therapeutic carbon beam through nuclear reactions in thick water. A ΔE-E counter telescope system, composed of a plastic scintillator, a gas-flow proportional counter and a BGO scintillator, was rotated around a water target in order to measure the spatial distribution of the radiation quality. The results revealed that the observed deflection of fragment particles exceeded the multiple scattering effect estimated by Molière's theory. However, the difference can be sufficiently accounted for by considering one term involved in the multiple-scattering formula; this term corresponds to a lateral 'kick' at the point of production of the fragment. This kick is successfully explained as a transfer of the intra-nucleus Fermi momentum of a projectile to the fragment; the extent of the kick obeys the expectation derived from the Goldhaber model.

  12. 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.

  13. The effect of Ar neutral beam treatment of screen-printed carbon nanotubes for enhanced field emission

    SciTech Connect

    Kyung, Se Jin; Park, Jae Beom; Park, Byung Jae; Min, Kyung Seok; Lee, June Hee; Yeom, Geun Young; Shin, Yong Sook; Park, Chong Yun

    2007-04-15

    This study examined the effectiveness of an Ar neutral beam as a surface treatment for improving the field emission properties of screen-printed carbon nanotubes (CNTs). A short period of the neutral beam treatment on tape-activated CNTs enhanced the emission properties of the CNTs, showing a decrease in the turn-on field and an increase in the number of emission sites. The neutral beam treatment appeared to render the CNT surfaces more actively by exposing more CNTs from the CNT paste without cutting or kinking the already exposed long CNT emitters. The treated CNTs emitted more electrons than the CNTs treated using other methods. When the field emission properties were measured after the neutral beam treatment, the turn-on field decreased from 1.65 to 0.60 V/{mu}m and the emission field at 1 mA/cm{sup 2} decreased from 3.10 to 2.41 V/{mu}m. After the neutral beam treatment for 10 s, there was an improvement in the stability of the emission current at a constant electric field. It is expected that the neutral beam treatment introduced in this study will provide an easy way of improving the emission intensity and stability of screen-printed CNT emitters.

  14. 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

  15. 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.

  16. 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.

  17. Wetting characteristics and performance of molten carbonate fuel cell electrode

    NASA Astrophysics Data System (ADS)

    Hong, Suk-Gi

    For the wetting studies of the molten carbonates, the meniscus height due to polarization was experimentally measured in the oxidant and reducing atmospheres and its dependence on polarization, gas environment, electrolyte melt composition and temperature was thoroughly investigated. A stochastic electrode structure was introduced to simulate the MCFC porous electrodes. In building the structure, the porosity was employed for the assignment of particles and the fixed-volume capillary equilibrium concept was adopted for the distribution of electrolyte. The wetting properties determined from the experiment were used for the capillary equilibrium approach. By virtue of the structure, the porous electrode was visualized and the (cumulative) pore size distribution was estimated. The electrolyte fill level within the porous electrode was predicted and polarization effect on electrolyte distribution was examined. The stochastic structure model was combined with an agglomerate-type porous electrode performance model. The agglomerates were defined by combining the particle, electrolyte, and pore cells in the structure according to well-defined rules and the structure-dependent model parameters were determined. Using the agglomerate model, a performance of porous MCFC electrode was predicted with the solution technique based on the finite element method.

  18. 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.

  19. 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.

  20. 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.

  1. Modelling of tests performed in order to evaluate the residual strength of corroded beams in the framework of the benchmark of the rance beams

    NASA Astrophysics Data System (ADS)

    Millard, A.; Vivier, M.

    2006-11-01

    The Benchmark of the Rance beams has been organised in order to evaluate the capabilities of various modelling tools, to predict the residual load carrying capacity of corroded beams. The Rance beams have been corroded in a marine environment for nearly 40years. Different types of prestressed beams, made of different types of cement, have been subjected to four points bending monotonous and cyclic tests as well as direct traction tests. The tests have been carried on up to failure, in order to evaluate the residual carrying capacity of the beams. Different teams have participated to the blind prediction of the tests results. In this framework, the CEA/DM2S/LM2S team has performed bidimensionnal modellings which are described in details in this paper. The various constitutive elements of the beams are represented : for concrete, the isotropic Mazars' damage model is used, in a non local version, for prestressing and passive steels, an elasto-plastic strain hardening model is adopted. The corrosion effects, taken into account for the longitudinal rebars, are derived on one hand from the measurements performed on the beams after the tests, and on the other hand from the literature. They consist mainly in a reduction of the rebars cross-section, as well as in their ductility. In principle, the properties of the bond between steel and rebars are also modified by the corrosion. Here, because of the unavailability of specific data on the smooth rebars of the Rance beams, the bond has been modelled by means of specific joint finite elements. The load carrying capacity has been calculated for the monotonous as well as the cyclic tests. Moreover, a sensitivity analysis has been performed, by considering variants where either the rebars are sane, or they have only reduced sections, with their original ductility. The results are compared to the experimental database, and discussed.

  2. 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.

  3. Effects of carbon-ion beams on human pancreatic cancer cell lines that differ in genetic status.

    PubMed

    Matsui, Yoshifumi; Asano, Takehide; Kenmochi, Takashi; Iwakawa, Mayumi; Imai, Takashi; Ochiai, Takenori

    2004-02-01

    The relative biologic effectiveness (RBE) of carbon-ion beams at 3 different linear energy transfer (LET) values (13, 50, and 80 keV/microm) accelerated by the Heavy Ion Medical Accelerator in Chiba on human pancreatic cancer cell lines differing in genetic status was determined. The RBE values were calculated as D10, the dose (Gy) required to reduce the surviving fraction to 10%, relative to X-rays. We also investigated apoptosis and the relationship between D10 and the cell cycle checkpoint using morphologic examination and flow cytometry analysis, respectively. The RBE values calculated by the D10 values ranged from 1.16 to 1.77 for the 13-keV/microm beam and from 1.83 to 2.46 for the 80-keV/microm beam. A correlation between the D10 values of each cell line and intensity of G2/M arrest was observed. In contrast, LET values did not clearly correlate with induction of apoptosis. These results suggest that carbon-ion beam therapy is a promising modality. Elucidation of the mechanisms of G2/M arrest and apoptosis may provide clues to enhancing the effects of radiation on pancreatic cancer. PMID:14758129

  4. 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

  5. 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

  6. Beam modeling and VMAT performance with the Agility 160-leaf multileaf collimator.

    PubMed

    Bedford, James L; Thomas, Michael D R; Smyth, Gregory

    2013-01-01

    The Agility multileaf collimator (Elekta AB, Stockholm, Sweden) has 160 leaves of projected width 0.5 cm at the isocenter, with maximum leaf speed 3.5 cms-1. These characteristics promise to facilitate fast and accurate delivery of radiotherapy, particularly volumetric-modulated arc therapy (VMAT). The aim of this study is therefore to create a beam model for the Pinnacle3 treatment planning system (Philips Radiation Oncology Systems, Fitchburg, WI), and to use this beam model to explore the performance of the Agility MLC in delivery of VMAT. A 6 MV beam model was created and verified by measuring doses under irregularly shaped fields. VMAT treatment plans for five typical head-and-neck patients were created using the beam model and delivered using both binned and continuously variable dose rate (CVDR). Results were compared with those for an MLCi unit without CVDR. The beam model has similar parameters to those of an MLCi model, with interleaf leakage of only 0.2%. The verification of irregular fields shows a mean agreement between measured and planned dose of 1.3% (planned dose higher). The Agility VMAT head-and-neck plans show equivalent plan quality and delivery accuracy to those for an MLCi unit, with 95% of verification measurements within 3% and 3 mm of planned dose. Mean delivery time is 133 s with the Agility head and CVDR, 171 s without CVDR, and 282 s with an MLCi unit. Pinnacle3 has therefore been shown to model the Agility MLC accurately, and to provide accurate VMAT treatment plans which can be delivered significantly faster with Agility than with an MLCi. PMID:23470941

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. The Performance of the Gamma-Ray Energy Tracking In-Beam Nuclear Array GRETINA

    SciTech Connect

    Paschalis, S.; Lee, I. Y.; Macchiavelli, A. O.; Campbell, C. M.; Cromaz, M.; Gros, S.; Pavin, J.; Qian, J.; Clark, R. M.; Crawford, H. L.; Doering, D.; Fallon, P.; Lionberger, C.; Loew, T.; Petri, M.; Stezelberger, T.; Zimmerman, S.; Radford, David C; Lagergren, Karin B; Weisshaar, D.; Winkler, R.; Glasmacher, T.; Anderson, J. T,; Beausang, C. W.

    2013-01-01

    The Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA) is a new generation high-resolution -ray spectrometer consisting of electrically segmented high-purity germanium crystals. GRETINA is capable of reconstructing the energy and position of each -ray interaction point inside the crystal with high resolution. This enables -ray energy tracking which in turn provides an array with large photopeak efficiency, high resolution and good peak-to-total ratio. GRETINA is used for nuclear structure studies with demanding -ray detection requirements and it is suitable for experiments with radioactive-ion beams with high recoil velocities. The GRETINA array has a 1 solid angle coverage and constitutes the first stage towards the full 4 array GRETA. We present in this paper the main parts and the performance of the GRETINA system.

  14. 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.

  15. Simulated performance of the in-beam conversion-electron spectrometer, SPICE

    NASA Astrophysics Data System (ADS)

    Ketelhut, S.; Evitts, L. J.; Garnsworthy, A. B.; Bolton, C.; Ball, G. C.; Churchman, R.; Dunlop, R.; Hackman, G.; Henderson, R.; Moukaddam, M.; Rand, E. T.; Svensson, C. E.; Witmer, J.

    2014-07-01

    The SPICE spectrometer is a new in-beam electron spectrometer designed to operate in conjunction with the TIGRESS HPGe Clover array at TRIUMF-ISAC. The spectrometer consists of a large area, annular, segmented lithium-drifted silicon electron detector shielded from the target by a photon shield. A permanent magnetic lens directs electrons around the photon shield to the detector. Experiments will be performed utilising Coulomb excitation, inelastic-scattering, transfer and fusion-evaporation reactions using stable and radioactive ion beams with suitable heavy-ion detection. Good detection efficiency can be achieved in a large energy range up to 3500 keV electron energy using several magnetic lens designs which are quickly interchangeable. COMSOL and Geant4 simulations have been used to maximise the detection efficiency. In addition, the simulations have guided the design of components to minimise the contributions from various sources of backgrounds.

  16. Impact of beam smoothing method on direct drive target performance for the NIF

    SciTech Connect

    Rothenberg, J.E.; Weber, S.V.

    1996-11-01

    The impact of smoothing method on the performance of a direct drive target is modeled and examined in terms of its l-mode spectrum. In particular, two classes of smoothing methods are compared, smoothing by spectral dispersion (SSD) and the induced spatial incoherence (ISI) method. It is found that SSD using sinusoidal phase modulation (FM) results in poor smoothing at low l-modes and therefore inferior target performance at both peak velocity and ignition. Modeling of the hydrodynamic nonlinearity shows that saturation tends to reduce the difference between target performance for the smoothing methods considered. However, using SSD with more generalized phase modulation results in a smoothed spatial spectrum, and therefore target performance, which is identical to that obtained with the ISI or similar method where random phase plates are present in both methods and identical beam divergence is assumed.

  17. 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.

  18. Dynamic modulation of electronic properties of graphene by localized carbon doping using focused electron beam induced deposition.

    PubMed

    Kim, S; Russell, M; Henry, M; Kim, S S; Naik, R R; Voevodin, A A; Jang, S S; Tsukruk, V V; Fedorov, A G

    2015-09-28

    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 × 10(18) e(-) per cm(2)). 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 × 10(19) e(-) per cm(2) 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. PMID:26302897

  19. Spine-like Nanostructured Carbon Interconnected by Graphene for High-performance Supercapacitors

    NASA Astrophysics Data System (ADS)

    Park, Sang-Hoon; Yoon, Seung-Beom; Kim, Hyun-Kyung; Han, Joong Tark; Park, Hae-Woong; Han, Joah; Yun, Seok-Min; Jeong, Han Gi; Roh, Kwang Chul; Kim, Kwang-Bum

    2014-08-01

    Recent studies on supercapacitors have focused on the development of hierarchical nanostructured carbons by combining two-dimensional graphene and other conductive sp2 carbons, which differ in dimensionality, to improve their electrochemical performance. Herein, we report a strategy for synthesizing a hierarchical graphene-based carbon material, which we shall refer to as spine-like nanostructured carbon, from a one-dimensional graphitic carbon nanofiber by controlling the local graphene/graphitic structure via an expanding process and a co-solvent exfoliation method. Spine-like nanostructured carbon has a unique hierarchical structure of partially exfoliated graphitic blocks interconnected by thin graphene sheets in the same manner as in the case of ligaments. Owing to the exposed graphene layers and interconnected sp2 carbon structure, this hierarchical nanostructured carbon possesses a large, electrochemically accessible surface area with high electrical conductivity and exhibits high electrochemical performance.

  20. 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.

  1. The new vertical neutron beam line at the CERN n_TOF facility design and outlook on the performance

    NASA Astrophysics Data System (ADS)

    Weiß, C.; Chiaveri, E.; Girod, S.; Vlachoudis, V.; Aberle, O.; Barros, S.; Bergström, I.; Berthoumieux, E.; Calviani, M.; Guerrero, C.; Sabaté-Gilarte, M.; Tsinganis, A.; Andrzejewski, J.; Audouin, L.; Bacak, M.; Balibrea-Correa, J.; Barbagallo, M.; Bécares, V.; Beinrucker, C.; Belloni, F.; Bečvář, F.; Billowes, J.; Bosnar, D.; Brugger, M.; Caamaño, M.; Calviño, F.; Cano-Ott, D.; Cerutti, F.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Damone, L.; Deo, K.; Diakaki, M.; Domingo-Pardo, C.; Dupont, E.; Durán, I.; Dressler, R.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Frost, R.; Furman, V.; Ganesan, S.; Gheorghe, A.; Glodariu, T.; Göbel, K.; Gonçalves, I. F.; González-Romero, E.; Goverdovski, A.; Griesmayer, E.; Gunsing, F.; Harada, H.; Heftrich, T.; Heinitz, S.; Hernández-Prieto, A.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Kadi, Y.; Käppeler, F.; Katabuchi, T.; Kavrigin, P.; Ketlerov, V.; Khryachkov, V.; Kimura, A.; Kivel, N.; Kokkoris, M.; Krtička, M.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Lerendegui, J.; Licata, M.; Lo Meo, S.; López, D.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P. F.; Mastromarco, M.; Matteucci, F.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Musumarra, A.; Nolte, R.; Palomo Pinto, R.; Paradela, C.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, I.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Robles, M. S.; Rubbia, C.; Ryan, J.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Sedyshev, P.; Smith, G.; Stamatopoulos, A.; Steinegger, P.; Suryanarayana, S. V.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlastou, R.; Wallner, A.; Warren, S.; Weigand, M.; Wright, T.; Žugec, P.

    2015-11-01

    At the neutron time-of-flight facility n_TOF at CERN a new vertical beam line was constructed in 2014, in order to extend the experimental possibilities at this facility to an even wider range of challenging cross-section measurements of interest in astrophysics, nuclear technology and medical physics. The design of the beam line and the experimental hall was based on FLUKA Monte Carlo simulations, aiming at maximizing the neutron flux, reducing the beam halo and minimizing the background from neutrons interacting with the collimator or back-scattered in the beam dump. The present paper gives an overview on the design of the beam line and the relevant elements and provides an outlook on the expected performance regarding the neutron beam intensity, shape and energy resolution, as well as the neutron and photon backgrounds.

  2. 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

  3. 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.

  4. RHIC performance with 56 MHz RF and gold ion beams pre-cooled at lower energy

    SciTech Connect

    Fedotov,A.

    2008-10-01

    Presently there is an R&D ERL under construction at Collider-Accelerator Department (CAD) at BNL with its commissioning scheduled for FY09-10 [1]. The use of this full energy 21 MeV ERL in RHIC tunnel was recently proposed for a Proof-of-Principle demonstration of Coherent Electron Cooling of gold ions at 40 GeV/nucleon [2]. The purpose of this Note is to summarize numerical studies aimed at understanding the potential improvement of RHIC luminosity by using this R&D ERL for pre-cooling of Au ion beams with conventional electron cooling system at 40 GeV/nucleon. The constraints were such that electron beam parameters should be close to those expected from R&D ERL. Additionally, the cooling section in RHIC should not require major RHIC modification. As a result of these studies it was found that pre-cooling of gold ion at about 40 GeV/nucleon approximately doubles the average store luminosity of RHIC at top energy of 100 GeV/nucleon compared to the expected luminosity improvement with 56MHz RF upgrade [3, 4]. Significant luminosity improvement may be also gained on top of future expected luminosity performance with combined upgrades of 56MHz RF and all-plane stochastic cooling system with present beam parameters [5]. The electron beam parameters needed for such pre-cooling (see Table 1) are close to those expected from the R&D ERL which is presently under construction at BNL. With electron beam parameters from Table 1 it takes about 20 minutes to cool the transverse emittance of gold ions by a factor of two at 40 GeV/nucleon. Similar studies were done for protons as well. However, it was found that the electron beam parameters needed for pre-cooling of protons would require a significant upgrade of the present injector of the R&D ERL. Thus, discussion about protons is omitted from the present Note.

  5. 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.

  6. The Design and Performance Evaluation of Hydroformed Tubular Torsion Beam Axle

    NASA Astrophysics Data System (ADS)

    Kim, Jaehyun; Oh, Jinho; Choi, Hanho

    2010-06-01

    Suspensions for vehicles are structural devices used for suspending a vehicle body and absorbing shocks from the road. Thus, the suspensions must be designed such that they can attenuate shocks from a road and make passengers feel comfortable despite the shocks, and improve steering stability, determined by the ground contact force of tires during running of vehicles. Another important factor to be considered while designing suspensions is that the suspensions must maintain desired stiffness and desired durability despite the repeated application of shocks from roads thereto. The present relates, in general, to a tubular torsion beam for rear suspensions of vehicles and a manufacturing method thereof and, more particularly, to the provision of tubular torsion beams having excellent roll stiffness and excellent roll strength, produced through hydroforming. The hydroforming technology has a lot of benefit which is shape accuracy, good durability caused by compressive pressure, and good forming quality. In this study, the performance evaluation of the hydroformed tubular torsion beam axle is evaluated.

  7. 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.

  8. 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.

  9. Site-specific carbon deposition for hierarchically ordered core/shell-structured graphitic carbon with remarkable electrochemical performance.

    PubMed

    Lv, Yingying; Wu, Zhangxiong; Qian, Xufang; Fang, Yin; Feng, Dan; Xia, Yongyao; Tu, Bo; Zhao, Dongyuan

    2013-10-01

    A fascinating core-shell-structured graphitic carbon material composed of ordered microporous core and uniform mesoporous shell is fabricated for the first time through a site-specific chemical vapor deposition process by using a nanozeolite@mesostructured silica composite molecular sieve as the template. The mesostructure-directing agent cetyltrimethylammonium bromide in the shell of the template can be either burned off or carbonized so that it is successfully utilized as a pore switch to turn the shell of the template "on" or "off" to allow selective carbon deposition. The preferred carbon deposition process can be performed only in the inner microporous zeolite cores or just within the outer mesoporous shells, resulting in a zeolite-like ordered microporous carbon or a hollow mesoporous carbon. Full carbon deposition in the template leads to the new core-shell-structured microporous@mesoporous carbon with a nanographene-constructed framework for fast electron transport, a microporous nanocore with large surface area for high-capacity storage of lithium ions, a mesoporous shell with highly opened mesopores as a transport layer for lithium ions and electron channels to access inner cores. The ordered micropores are protected by the mesoporous shell, avoiding pore blockage as the formation of solid electrolyte interphase layers. Such a unique core-shell-structured microporous@mesoporous carbon material represents a newly established lithium ion storage model, demonstrating high reversible energy storage, excellent rate capability, and long cyclic stability. PMID:24039038

  10. Performance of a tungsten-cerium fluoride sampling calorimeter in high-energy electron beam tests

    NASA Astrophysics Data System (ADS)

    Becker, R.; Bianchini, L.; Dissertori, G.; Djambazov, L.; Donega, M.; Lustermann, W.; Marini, A. C.; Nessi-Tedaldi, F.; Pandolfi, F.; Peruzzi, M.; Schönenberger, M.; Cavallari, F.; Dafinei, I.; Diemoz, M.; Lope, C. Jorda; Meridiani, P.; Nuccetelli, M.; Paramatti, R.; Pellegrino, F.; Micheli, F.; Organtini, G.; Rahatlou, S.; Soffi, L.; Brianza, L.; Govoni, P.; Martelli, A.; Fatis, T. Tabarelli de; Monti, V.; Pastrone, N.; Trapani, P. P.; Candelise, V.; Ricca, G. Della

    2015-12-01

    A prototype for a sampling calorimeter made out of cerium fluoride crystals interleaved with tungsten plates, and read out by wavelength-shifting fibres, has been exposed to beams of electrons with energies between 20 and 150 GeV, produced by the CERN Super Proton Synchrotron accelerator complex. The performance of the prototype is presented and compared to that of a GEANT4 simulation of the apparatus. Particular emphasis is given to the response uniformity across the channel front face, and to the prototype's energy resolution.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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

  19. Toward Two-Dimensional All-Carbon Heterostructures via Ion Beam Patterning of Single-Layer Graphene

    PubMed Central

    2015-01-01

    Graphene has many claims to fame: it is the thinnest possible membrane, it has unique electronic and excellent mechanical properties, and it provides the perfect model structure for studying materials science at the atomic level. However, for many practical studies and applications the ordered hexagon arrangement of carbon atoms in graphene is not directly suitable. Here, we show that the atoms can be locally either removed or rearranged into a random pattern of polygons using a focused ion beam (FIB). The atomic structure of the disordered regions is confirmed with atomic-resolution scanning transmission electron microscopy images. These structural modifications can be made on macroscopic scales with a spatial resolution determined only by the size of the ion beam. With just one processing step, three types of structures can be defined within a graphene layer: chemically inert graphene, chemically active amorphous 2D carbon, and empty areas. This, along with the changes in properties, gives promise that FIB patterning of graphene will open the way for creating all-carbon heterostructures to be used in fields ranging from nanoelectronics and chemical sensing to composite materials. PMID:26161575

  20. One-step carbonization synthesis of hollow carbon nanococoons with multimodal pores and their enhanced electrochemical performance for supercapacitors.

    PubMed

    Zhang, Jianan; Wang, Kaixi; Guo, Shaojun; Wang, Shoupei; Liang, Zhiqiang; Chen, Zhimin; Fu, Jianwei; Xu, Qun

    2014-02-12

    Hollow carbon capsules with multimodal pores are highly promising for developing novel electrode materials for high-performance electrochemical devices due to their more active sites for ion and electron transfer. However, at present, most of the previous efforts are focused on the multistep process for the synthesis of hollow carbon nanostructures with individual pores. Herein, hollow carbon nanococoons (HCNCs) with non-spherical cavity and multimodal hierarchical pores have been facilely synthesized via a one-step carbonization of a Fe2O3/carbon precursor core/shell nanospindle at 850 °C. We interestingly found that during the carbonization, Fe2O3 was automatically "escaped" from the inside nanospindle, leading to the formation of new HCNCs. Most importantly, the spindle-shaped cavity of the obtained HCNCs with high conductivity can offer a multimodal ion diffusion pathway, which can facilitate the reaction kinetics in a supercapacitor. As a result, the HCNCs-based supacapacitor exhibits the capacitance of 220.0 F g(-1) at a given scan rate of 5 mV s(-1), 3.5 times higher than that of hollow carbon spheres, high stability with 98% of the initial capacity maintained even after 1000 cycles, and high rate capability. This work provides a new and facile avenue for enhancing performance of a HCNCs-based supercapacitor by using the non-spherical hollow structures with multimodal pores. PMID:24433086

  1. Study on reinforced concrete beams strengthened using shape memory alloy wires in combination with carbon-fiber-reinforced polymer plates

    NASA Astrophysics Data System (ADS)

    Li, Hui; Liu, Zhi-qiang; Ou, Jin-ping

    2007-12-01

    It has been proven that carbon-fiber-reinforced polymer (CFRP) sheets or plates are capable of improving the strength of reinforced concrete (RC) structures. However, residual deformation of RC structures in service reduces the effect of CFRP strengthening. SMA can be applied to potentially decrease residual deformation and even close concrete cracks because of its recovery forces imposed on the concrete when heated. Therefore, a method of a RC structure strengthened by CFRP plates in combination with SMA wires is proposed in this paper. The strengthening effect of this method is investigated through experiments and numerical study based on the nonlinear finite element software ABAQUS in simple RC beams. Parametric analysis and assessment of damage by defining a damage index are carried out. The results indicate that recovery forces of SMA wires can decrease deflections and even close cracks in the concrete. The recovery rate of deflection of the beam increases with increasing the ratio of SMA wires. The specimen strengthened with CFRP plates has a relatively large stiffness and smaller damage index value when the residual deformation of the beam is first reduced by activation of the SMA wires. The effectiveness of this strengthening method for RC beams is verified by experimental and numerical results.

  2. 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.

  3. Thermomechanical finite element simulations of selective electron beam melting processes: performance considerations

    NASA Astrophysics Data System (ADS)

    Riedlbauer, Daniel; Steinmann, Paul; Mergheim, Julia

    2014-07-01

    The present contribution is concerned with the macroscopic modelling of the selective electron beam melting process by using the finite element method. The modelling and simulation of the selective electron beam melting process involves various challenges: complex material behaviour, phase changes, thermomechanical coupling, high temperature gradients, different time and length scales etc. The present contribution focuses on performance considerations of solution approaches for thermomechanically coupled problems, i.e. the monolithic and the adiabatic split approach. The material model is restricted to nonlinear thermoelasticity with temperature-dependent material parameters. As a numerical example a straight scanning path is simulated, the predicted temperatures and stresses are analysed and the performance of the two algorithms is compared. The adiabatic split approach turned out to be much more efficient for linear thermomechanical problems, i.e. the solution time is three times less than with the monolithic approach. For nonlinear problems, stability issues necessitated the use of the Euler backward integration scheme, and therefore, the adiabatic split approach required small time steps for reasonable accuracy. Thus, for nonlinear problems and in combination with the Euler backward integration scheme, the monolithic solver turned out to be more efficient.

  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. Survivability of Silicon-Doped Diamond-Like Carbon Films in Energetic Atomic/Molecular Oxygen Beam Environments

    NASA Astrophysics Data System (ADS)

    Tagawa, Masahito; Kishida, Kazuhiro; Yokota, Kumiko; Matsumoto, Koji; Yoshigoe, Akitaka; Teraoka, Yuden; Zhang, Jianming; Minton, Timothy K.

    Volatile products were measured from two types of diamond-like carbon films under the hyperthermal atomic oxygen (AO) beam bombardment. It was clearly observed that CO and CO2 were formed at the conventional hydrogenated DLC surface when exposed to hyperthermal AO beam. Desorption rates of CO and CO2 are constant with AO fluence which reflects the constant erosion rate of the hydrogenated DLC. In contrast, Si-doped DLC shows decrease in amount of CO and CO2 with increasing AO fluence. Oxidation of Si atoms at the DLC surface was detected by X-ray photoelectron spectroscopy, confirming the formation of SiO2 film formed at the DLC surface that could prevent AO reaction with C atoms in DLC which leads to loss of DLC. Since a self-healing capability can be expected on Si-doped DLC, metal doping is a promising technology for space application of DLC.

  6. 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

  7. Dosimetric performance evaluation regarding proton beam incident angles of a lithium-based AB-BNCT design.

    PubMed

    Lee, Pei-Yi; Liu, Yuan-Hao; Jiang, Shiang-Huei

    2014-10-01

    The (7)Li(p,xn)(7)Be nuclear reaction, based on the low-energy protons, could produce soft neutrons for accelerator-based boron neutron capture therapy (AB-BNCT). Based on the fact that the induced neutron field is relatively divergent, the relationship between the incident angle of proton beam and the neutron beam quality was evaluated in this study. To provide an intense epithermal neutron beam, a beam-shaping assembly (BSA) was designed. And a modified Snyder head phantom was used in the calculations for evaluating the dosimetric performance. From the calculated results, the intensity of epithermal neutrons increased with the increase in proton incident angle. Hence, either the irradiation time or the required proton current can be reduced. When the incident angle of 2.5-MeV proton beam is 120°, the required proton current is ∼13.3 mA for an irradiation time of half an hour. PMID:24493784

  8. Correlation of Microstructure and Ballistic Performance of Multilayered Zr-based Amorphous Surface Composites Fabricated by High-Energy Electron-Beam Irradiation

    NASA Astrophysics Data System (ADS)

    Do, Jeonghyeon; Jeon, Changwoo; Nam, Duk-Hyun; Kim, Choongnyun Paul; Song, Young Buem; Lee, Sunghak

    2011-05-01

    In this study, multilayered, Zr-based amorphous surface composites were fabricated by high-energy electron-beam irradiation; the correlation of their microstructure, hardness, compressive properties, and fracture properties with ballistic performance was investigated. The mixture of Zr-based amorphous powders and LiF + MgF2 flux powders was deposited on a pure Ti substrate or a plain carbon steel substrate, and then an electron beam was irradiated on this powder mixture to fabricate a one-layered surface composite. The multilayered surface composite was fabricated by an irradiating electron beam several times again onto the powder mixture deposited on the one-layered surface composite. The microstructural analysis results indicated that a small amount of fine crystalline particles was distributed homogeneously in the surface composite layer. Because the surface composite layers absorbed the ballistic impact energy by forming many cracks or microcracks, the surface composite plates were not perforated during the ballistic impact test. On the one hand, in the surface composite without containing ductile β phases, the composite layer was cracked completely and fallen off from the substrate. On the other hand, a small amount of fragmentation was found in the impacted area of the composite containing β phases because it had the sufficient hardness and fracture toughness simultaneously for effectively blocking the traveling of a projectile, thereby improving ballistic performance.

  9. 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.

  10. Nickel clusters embedded in carbon nanotubes as high performance magnets.

    PubMed

    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

  11. 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

  12. Carbon fiber composite targets for nuclear fusion technology: a focused ion beam/scanning electron microscope investigation.

    PubMed

    Ghezzi, F; Magni, S; Milani, M; Tatti, F

    2007-01-01

    Carbon fiber composite (CFC) targets are investigated by a focused ion beam/scanning electron microscope (FIB/SEM) in a joint project aiming at the development of robust divertors in the International Thermonuclear Experimental Reactor (ITER). These mockups are exposed to a plasma that simulates the off-normal thermal loads foreseen for ITER and display a rich, puzzling impact scenario. Morphological elements are identified at the exposed surface and beneath it, and are examined in order to point out the relevant processes involved. Each technique adopted is discussed and evaluated. PMID:18200678

  13. All-carbon based graphene field effect transistor with graphitic electrodes fabricated by e-beam direct writing on PMMA

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Yu, Yayun; Zheng, Xiaoming; Qin, Shiqiao; Wang, Fei; Fang, Jingyue; Wang, Guang; Wang, Chaocheng; Wang, Li; Peng, Gang; Zhang, Xue-Ao

    2015-07-01

    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.

  14. 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.

  15. 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

  16. Coaxial carbon/metal oxide/aligned carbon nanotube arrays as high-performance anodes for lithium ion batteries.

    PubMed

    Lou, Fengliu; Zhou, Haitao; Tran, Trung Dung; Melandsø Buan, Marthe Emelie; Vullum-Bruer, Fride; Rønning, Magnus; Walmsley, John Charles; Chen, De

    2014-05-01

    Coaxial carbon/metal oxide/aligned carbon nanotube (ACNT) arrays over stainless-steel foil are reported as high-performance binder-free anodes for lithium ion batteries. The coaxial arrays were prepared by growth of ACNTs over stainless-steel foil followed by coating with metal oxide and carbon. The carbon/manganese oxide/ACNT arrays can deliver an initial capacity of 738 mAh g(-1) with 99.9 % capacity retention up to 100 cycles and a capacity of 374 mAh g(-1) at a high current density of 6000 mA g(-1). The external carbon layer was recognized as a key component for high performance, and the mechanism of performance enhancement was investigated by electrochemical impedance spectroscopy, electron microscopy, and X-ray diffraction analysis. The layer increases rate capability by enhancing electrical conductivity and maintaining a low mass-transfer resistance and also improves cyclic stability by avoiding aggregation of metal-oxide particles and stabilizing the solid electrolyte interface. The resultant principle of rational electrode design was applied to an iron oxide-based system, and similar improvements were found. These coaxial nanotube arrays present a promising strategy for the rational design of high-performance binder-free anodes for lithium ion batteries. PMID:24578068

  17. Synthesis of carbon-supported PtRh random alloy nanoparticles using electron beam irradiation reduction method

    NASA Astrophysics Data System (ADS)

    Matsuura, Yoshiyuki; Seino, Satoshi; Okazaki, Tomohisa; Akita, Tomoki; Nakagawa, Takashi; Yamamoto, Takao A.

    2016-05-01

    Bimetallic nanoparticle catalysts of PtRh supported on carbon were synthesized using an electron beam irradiation reduction method. The PtRh nanoparticle catalysts were composed of particles 2-3 nm in size, which were well dispersed on the surface of the carbon support nanoparticles. Analyses of X-ray diffraction and scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy revealed that the PtRh nanoparticles have a randomly alloyed structure. The lattice constant of the PtRh nanoparticles showed good correlation with Vegard's law. These results are explained by the radiochemical formation process of the PtRh nanoparticles. Catalytic activities of PtRh/C nanoparticles for ethanol oxidation reaction were found to be higher than those obtained with Pt/C.

  18. 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

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. The beam combiners of Gravity VLTI instrument: concept, development, and performance in laboratory

    NASA Astrophysics Data System (ADS)

    Jocou, L.; Perraut, K.; Moulin, T.; Magnard, Y.; Labeye, P.; Lapras, V.; Nolot, A.; Perrin, G.; Eisenhauer, F.; Holmes, C.; Amorim, A.; Brandner, W.; Straubmeier, C.

    2014-07-01

    Gravity is one of the second-generation instruments of the Very Large Telescope Interferometer that operates in the near infrared range and that is designed for precision narrow-angle astrometry and interferometric imaging. With its infrared wavefront sensors, pupil stabilization, fringe tracker, and metrology, the instrument is tailored to provide a high sensitivity, imaging with 4-millisecond resolution, and astrometry with a 10μarcsec precision. It will probe physics close to the event horizon of the Galactic Centre black hole, and allow to study mass accretion and jets in young stellar objects and active galactic nuclei, planet formation in circumstellar discs, or detect and measure the masses of black holes in massive star clusters throughout the Milky Way. As the instrument required an outstanding level of precision and stability, integrated optics has been chosen to collect and combine the four VLTI beams in the K band. A dedicated integrated optics chip glued to a fiber array has been developed. Technology breakthroughs have been mandatory to fulfill all the specifications. This paper is focused on the interferometric beam combination system of Gravity. Once the combiner concept described, the paper details the developments that have been led, the integration and the performance of the assemblies.

  6. Performance evaluation of the two-inch return-beam vidicon three-camera subsystem.

    NASA Technical Reports Server (NTRS)

    Miller, B. P.; Beck, G. A.; Barletta, J. M.

    1972-01-01

    A very-high resolution multispectral television camera system is being developed for NASA for use on the Earth Resources Technology Satellite (ERTS) program. There are three cameras in the system, each viewing the same area but operating in the blue-green, red and near-infrared spectral bands. In the laboratory the cameras' limiting resolution is 4500 TV lines over the 25 x 25-mm image format of the Return Beam Vidicon (RBV). Analysis of typical ERTS scenes shows that actual contrast ratios will be much lower than those of laboratory test targets. A model was developed to predict the resolving power performance of the RBV camera under realistic conditions. The methods used are applicable to all types of imaging systems. To verify the model, tests were conducted using the RBV camera, a laser-beam image reproducer and a series of AF tribar test patterns of known values of contrast. As a more graphic demonstration, simulated multispectral images were generated using color-IR photographs from Apollo 9.

  7. 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.

  8. 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.

  9. Development of long-lived thick carbon stripper foils for high energy heavy ion accelerators by a heavy ion beam sputtering method

    NASA Astrophysics Data System (ADS)

    Muto, Hideshi; Ohshiro, Yukimitsu; Kawasaki, Katsunori; Oyaizu, Michihiro; Hattori, Toshiyuki

    2013-04-01

    In the past decade, we have developed extremely long-lived carbon stripper foils of 1-50 μg/cm2 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 μg/cm2 in thickness. However, the heavy ion beam sputtering method was unsuccessful in production of foils thicker than about 50 μg/cm2 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.

  10. 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.

  11. Performance characteristics of HBC stripper foils irradiated by 650 keV H- and high intensity DC ion beams

    NASA Astrophysics Data System (ADS)

    Sugai, I.; Takagi, A.; Takeda, Y.; Irie, Y.; Oyaizu, M.; Kawakami, H.

    2014-06-01

    Newly developed Hybrid type Boron mixed Carbon (HBC) stripper foils are extensively used not only for the RCS of J-PARC and PSR of LANL, but also for other low energy, high intensity proton accelerators in medical applications. We had before tested HBC stripper foils with 3.2 MeV Ne+ and DC heavy ion beams. In order to further understand characteristics of HBC stripper foils, we measured the following parameters using the KEK-650 keV H- and light ion Cockcroft Walton DC accelerator: foil lifetime, thickness reduction, uniformity before and after beam irradiation, and foil deformation. Energy deposition in the present experiment was adjusted to a similar level to that of the HBC foil used in the RCS of J-PARC’. In addition, to understand the reason why the HBC stripper foils have high durability against high intensity beam irradiation, we investigated various physical properties, and compared them between the HBC foils and other tested carbon stripper foils. The sizes of the carbon particles in the HBC foil were found to play a vital role in the lifetime.

  12. From carbon nanostructures to high-performance sorbents for chromatographic separation and preconcentration

    NASA Astrophysics Data System (ADS)

    Postnov, V. N.; Rodinkov, O. V.; Moskvin, L. N.; Novikov, A. G.; Bugaichenko, A. S.; Krokhina, O. A.

    2016-02-01

    Information on carbon nanostructures (fullerenes, nanotubes, graphene, nanodiamond and nanodispersed active carbon) used to develop high-performance sorbents of organics and heavy metal ions from aqueous solutions is collected and analyzed. The advantages in the synthesis of hybrid carbon nanostructures and the possibilities of surface modification of these systems in order to carry out fast sorption pre-concentration are considered. Prospects for application of these materials in sorption technologies and analytical chemistry are discussed. The bibliography includes 364 references.

  13. 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.

  14. Performance analysis of molten carbonate fuel cell using a Li/Na electrolyte

    NASA Astrophysics Data System (ADS)

    Morita, H.; Komoda, M.; Mugikura, Y.; Izaki, Y.; Watanabe, T.; Masuda, Y.; Matsuyama, T.

    Several years ago, Li/Na carbonate (Li 2CO 3/Na 2CO 3) was developed as the electrolyte of molten carbonate fuel cells (MCFCs) in place of the usual Li/K carbonate (Li 2CO 3/K 2CO 3) to the advantage of a higher ionic conductivity and lower rate of cathode NiO dissolution. To estimate the potential of Li/Na carbonate as the MCFC electrolyte, the dependence of the cell performance on the operating conditions and the behavior during long-term performance was investigated in several bench-scale cell operations. The obtained data on the performance of Li/Na cells was analyzed to estimate the impact of voltage losses by using a performance model and discussed in comparison with the data of conventional Li/K cell performance.

  15. Performance evaluation of the source description of the THOR BNCT epithermal neutron beam.

    PubMed

    Liu, Yuan-Hao; Tsai, Pi-En; Yu, Hui-Ting; Lin, Yi-Chun; Huang, Yu-Shiang; Huang, Chun-Kai; Liu, Yen-Wan Hsueh; Liu, Hong-Ming; Jiang, Shiang-Huei

    2011-12-01

    This paper aims to evaluate the performance of the source description of the THOR BNCT beam via different measurement techniques in different phantoms. The measurement included (1) the absolute reaction rate measurement of a set of triple activation foils, (2) the neutron and gamma-ray dose rates measured using the paired ionization chamber method, and (3) the relative reaction rate distributions obtained using the indirect neutron radiography. Three source descriptions, THOR-Y09, surface source file RSSA, and THOR-50C, were tested. The comparison results concluded that THOR-Y09 is a well-tested source description not only for neutron components, but also for gamma-ray component. PMID:21570855

  16. 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

  17. 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.

  18. Tribological performance of diamond and diamondlike carbon films at elevated temperatures

    SciTech Connect

    Erdemir, A.; Fenske, G.R.

    1995-09-01

    In this study, we investigated the tribological performance of diamond and diamondlike carbon (DLC) films as a function of ambient temperature. Both films were deposited on silicon carbide (SiC) by microwave plasma chemical vapor deposition and ion-beam deposition processes. Tribological tests were performed on a reciprocating wear machine in open air (20 to 30% relative humidity) and under a 10-N load using SiC pins. For the test conditions explored, the steady- state friction coefficients of test pairs without a diamond or DLC film were 0.7 to 0.9 and the average wear rates of pins were 10{sup {minus}5} to 10{sup {minus}7} mm{sup 3}/N.m, depending on ambient temperature. DLC films reduced the steady-state friction coefficients of test pairs by factors of 3 to 5 and the wear rates of pins by two to three orders of magnitude. Low friction coefficients were also obtained with the diamond films, but wear rates of the counterface pins were high due to the very abrasive nature of these films. The wear of SiC disks coated with either diamond or DLC films was virtually unmeasurable while the wear of uncoated disks was substantial. Test results showed that the DLC films could afford low friction up to about 300{degrees}C. At higher temperatures, the DLC films became graphitized and were removed from the surface. The diamond films could withstand much higher temperatures, but their tribological behavior degraded. Raman spectroscopy and scanning electron microscopy were used to elucidate the friction and wear mechanisms of both films at high temperatures.

  19. A scintillating gas detector for 2D dose measurements in clinical carbon beams.

    PubMed

    Seravalli, E; de Boer, M; Geurink, F; Huizenga, J; Kreuger, R; Schippers, J M; van Eijk, C W E; Voss, B

    2008-09-01

    A two-dimensional position sensitive dosimetry system based on a scintillating gas detector has been developed for pre-treatment verification of dose distributions in hadron therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process, photons are emitted by the excited Ar/CF4 gas molecules and detected by a mirror-lens-CCD camera system. Since the amount of emitted light is proportional to the dose deposited in the sensitive volume of the detector by the incoming beam, the intensity distribution of the measured light spot is proportional to the 2D hadron dose distribution. For a measurement of a 3D dose distribution, the scintillating gas detector is mounted at the beam exit side of a water-bellows phantom, whose thickness can be varied in steps. In this work, the energy dependence of the output signal of the scintillating gas detector has been verified in a 250 MeV/u clinical 12C ion beam by means of a depth-dose curve measurement. The underestimation of the measured signal at the Bragg peak depth is only 9% with respect to an air-filled ionization chamber. This is much smaller than the underestimation found for a scintillating Gd2O2S:Tb ('Lanex') screen under the same measurement conditions (43%). Consequently, the scintillating gas detector is a promising device for verifying dose distributions in high LET beams, for example to check hadron therapy treatment plans which comprise beams with different energies. PMID:18695295

  20. A scintillating gas detector for 2D dose measurements in clinical carbon beams

    NASA Astrophysics Data System (ADS)

    Seravalli, E.; de Boer, M.; Geurink, F.; Huizenga, J.; Kreuger, R.; Schippers, J. M.; van Eijk, C. W. E.; Voss, B.

    2008-09-01

    A two-dimensional position sensitive dosimetry system based on a scintillating gas detector has been developed for pre-treatment verification of dose distributions in hadron therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process, photons are emitted by the excited Ar/CF4 gas molecules and detected by a mirror-lens-CCD camera system. Since the amount of emitted light is proportional to the dose deposited in the sensitive volume of the detector by the incoming beam, the intensity distribution of the measured light spot is proportional to the 2D hadron dose distribution. For a measurement of a 3D dose distribution, the scintillating gas detector is mounted at the beam exit side of a water-bellows phantom, whose thickness can be varied in steps. In this work, the energy dependence of the output signal of the scintillating gas detector has been verified in a 250 MeV/u clinical 12C ion beam by means of a depth-dose curve measurement. The underestimation of the measured signal at the Bragg peak depth is only 9% with respect to an air-filled ionization chamber. This is much smaller than the underestimation found for a scintillating Gd2O2S:Tb ('Lanex') screen under the same measurement conditions (43%). Consequently, the scintillating gas detector is a promising device for verifying dose distributions in high LET beams, for example to check hadron therapy treatment plans which comprise beams with different energies.

  1. 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

  2. Cone-beam computed tomography with a flat-panel imager: initial performance characterization.

    PubMed

    Jaffray, D A; Siewerdsen, J H

    2000-06-01

    The development and performance of a system for x-ray cone-beam computed tomography (CBCT) using an indirect-detection flat-panel imager (FPI) is presented. Developed as a bench-top prototype for initial investigation of FPI-based CBCT for bone and soft-tissue localization in radiotherapy, the system provides fully three-dimensional volumetric image data from projections acquired during a single rotation. The system employs a 512 x 512 active matrix of a-Si:H thin-film transistors and photodiodes in combination with a luminescent phosphor. Tomographic imaging performance is quantified in terms of response uniformity, response linearity, voxel noise, noise-power spectrum (NPS), and modulation transfer function (MTF), each in comparison to the performance measured on a conventional CT scanner. For the geometry employed and the objects considered, response is uniform to within 2% and linear within 1%. Voxel noise, at a level of approximately 20 HU, is comparable to the conventional CT scanner. NPS and MTF results highlight the frequency-dependent transfer characteristics, confirming that the CBCT system can provide high spatial resolution and does not suffer greatly from additive noise levels. For larger objects and/or low exposures, additive noise levels must be reduced to maintain high performance. Imaging studies of a low-contrast phantom and a small animal (a euthanized rat) qualitatively demonstrate excellent soft-tissue visibility and high spatial resolution. Image quality appears comparable or superior to that of the conventional scanner. These quantitative and qualitative results clearly demonstrate the potential of CBCT systems based upon flat-panel imagers. Advances in FPI technology (e.g., improved x-ray converters and enhanced electronics) are anticipated to allow high-performance FPI-based CBCT for medical imaging. General and specific requirements of kilovoltage CBCT systems are discussed, and the applicability of FPI-based CBCT systems to tomographic

  3. 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.

  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 this report was undertaken to evaluate the performance of powdered activated carbon (PAC) technology used in conjuntion with wet air regeneration (WAR) at municipal wastewater treatment plants. xcessive ash concentrations accumulated in the mixed l...

  6. 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 ...

  7. 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

  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. 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.

  10. 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.

  11. 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.

  12. 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. PMID:25599995

  13. 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.

  14. High-performance radio frequency transistors based on diameter-separated semiconducting carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cao, Yu; Che, Yuchi; Seo, Jung-Woo T.; Gui, Hui; Hersam, Mark C.; Zhou, Chongwu

    2016-06-01

    In this paper, we report the high-performance radio-frequency transistors based on the single-walled semiconducting carbon nanotubes with a refined average diameter of ˜1.6 nm. These diameter-separated carbon nanotube transistors show excellent transconductance of 55 μS/μm and desirable drain current saturation with an output resistance of ˜100 KΩ μm. An exceptional radio-frequency performance is also achieved with current gain and power gain cut-off frequencies of 23 GHz and 20 GHz (extrinsic) and 65 GHz and 35 GHz (intrinsic), respectively. These radio-frequency metrics are among the highest reported for the carbon nanotube thin-film transistors. This study provides demonstration of radio frequency transistors based on carbon nanotubes with tailored diameter distributions, which will guide the future application of carbon nanotubes in radio-frequency electronics.

  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. 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

  17. Fundamental radiological and geometric performance of two types of proton beam modulated discrete scanning systems

    SciTech Connect

    Farr, J. B.; Schoenenberg, D.; Dessy, F.; De Wilde, O.; Bietzer, O.

    2013-07-15

    Purpose: The purpose of this investigation was to compare and contrast the measured fundamental properties of two new types of modulated proton scanning systems. This provides a basis for clinical expectations based on the scanned beam quality and a benchmark for computational models. Because the relatively small beam and fast scanning gave challenges to the characterization, a secondary purpose was to develop and apply new approaches where necessary to do so.Methods: The following performances of the proton scanning systems were investigated: beamlet alignment, static in-air beamlet size and shape, scanned in-air penumbra, scanned fluence map accuracy, geometric alignment of scanning system to isocenter, maximum field size, lateral and longitudinal field uniformity of a 1 l cubic uniform field, output stability over time, gantry angle invariance, monitoring system linearity, and reproducibility. A range of detectors was used: film, ionization chambers, lateral multielement and longitudinal multilayer ionization chambers, and a scintillation screen combined with a digital video camera. Characterization of the scanned fluence maps was performed with a software analysis tool.Results: The resulting measurements and analysis indicated that the two types of delivery systems performed within specification for those aspects investigated. The significant differences were observed between the two types of scanning systems where one type exhibits a smaller spot size and associated penumbra than the other. The differential is minimum at maximum energy and increases inversely with decreasing energy. Additionally, the large spot system showed an increase in dose precision to a static target with layer rescanning whereas the small spot system did not.Conclusions: The measured results from the two types of modulated scanning types of system were consistent with their designs under the conditions tested. The most significant difference between the types of system was their proton

  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. 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.

  20. Initial Performance Characterization for a Thermalized Neutron Beam for Neutron Capture Therapy Research at Washington State University

    SciTech Connect

    David W. Nigg; P.E> Sloan; J.R. Venhuizen; C.A. Wemple

    2005-11-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) and Washington State University (WSU) have constructed a new epithermal-neutron beam for collaborative Boron Neutron Capture Therapy (BNCT) preclinical research at the WSU TRIGATM research reactor facility1. More recently, additional beamline components were developed to permit the optional thermalization of the beam for certain types of studies where it is advantageous to use a thermal neutron source rather than an epithermal source. This article summarizes the results of some initial neutronic performance measurements for the thermalized system, with a comparison to the expected performance from the design computations.

  1. 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.

  2. Role of HF in oxygen removal from carbon nanotubes: implications for high performance carbon electronics.

    PubMed

    Li, Xiaokai; Huang, Jing-Shun; Nejati, Siamak; McMillon, Lyndsey; Huang, Su; Osuji, Chinedum O; Hazari, Nilay; Taylor, André D

    2014-11-12

    Oxygen removal from SWNTs is crucial for many carbon electronic devices. This work shows that HF treatment followed by current stimulation is a very effective method for oxygen removal. Using a procedure involving HF treatment, current stimulation and spin-casting AgNWs onto a SWNT thin film, record high efficiency SWNT/p-Si solar cells have been developed. PMID:25286024

  3. Nanotribological performance of fullerene-like carbon nitride films

    NASA Astrophysics Data System (ADS)

    Flores-Ruiz, Francisco Javier; Enriquez-Flores, Christian Ivan; Chiñas-Castillo, Fernando; Espinoza-Beltrán, Francisco Javier

    2014-09-01

    Fullerene-like carbon nitride films exhibit high elastic modulus and low friction coefficient. In this study, thin CNx films were deposited on silicon substrate by DC magnetron sputtering and the tribological behavior at nanoscale was evaluated using an atomic force microscope. Results show that CNx films with fullerene-like structure have a friction coefficient (CoF ∼ 0.009-0.022) that is lower than amorphous CNx films (CoF ∼ 0.028-0.032). Analysis of specimens characterized by X-ray photoelectron spectroscopy shows that films with fullerene-like structure have a higher number of sp3 CN bonds and exhibit the best mechanical properties with high values of elastic modulus (E > 180 GPa) and hardness (H > 20 GPa). The elastic recovery determined on specimens with a fullerene-like CNx structure was of 95% while specimens of amorphous CNx structure had only 75% elastic recovery.

  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. 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.

  6. Performance Evaluation of Activated Carbon Nanofiber as Carbon Supports to Improve the Cyclability of Li-Air Batteries.

    PubMed

    Park, Inyeong; Kim, Heeyun; Shim, Sang Eun; Baeck, Sung-Hyeon

    2015-11-01

    This study addresses the effects of the pore structures of carbon materials used as cathodes for non-aqueous lithium-air batteries on cycle life. Carbon Nanofibers (CNFs) were synthesized by electrospinning polyacrylonitrile (PAN) and carbonization. The synthesized CNF was then converted to activated carbon nanofibers (ACNFs) under flowing CO2. The specific surface areas CNFs were increased on activation. ACNFs were arranged randomly to form a web-like structure providing both oxygen pathways and a means of discharging products. To examine the electrochemical properties of ACNF, charge-discharge tests were conducted using a Swagelok-type cell at a constant current density of 0.2 mA/cm2; impedance tests were also conducted. ACNF sheet electrodes had cycle lives of up to 50 cycles, which was attributed to high surface area and porosity, although overpotentials for both charge and discharge were high. This cycling performance showed that the pore structure of sheet ACNF is more suitable for the transport of oxygen and for the storage of discharge products than carbon powders. PMID:26726643

  7. High performance cone-beam spiral backprojection with voxel-specific weighting

    NASA Astrophysics Data System (ADS)

    Steckmann, Sven; Knaup, Michael; Kachelrieß, Marc

    2009-06-01

    Cone-beam spiral backprojection is computationally highly demanding. At first sight, the backprojection requirements are similar to those of cone-beam backprojection from circular scans such as it is performed in the widely used Feldkamp algorithm. However, there is an additional complication: the illumination of each voxel, i.e. the range of angles the voxel is seen by the x-ray cone, is a complex function of the voxel position. In general, one needs to multiply a voxel-specific weight w(x, y, z, α) prior to adding a projection from angle α to a voxel at position x, y, z. Often, the weight function has no analytically closed form and must be numerically determined. Storage of the weights is prohibitive since the amount of memory required equals the number of voxels per spiral rotation times the number of projections a voxel receives contributions and therefore is in the order of up to 1012 floating point values for typical spiral scans. We propose a new algorithm that combines the spiral symmetry with the ability of today's 64 bit operating systems to store large amounts of precomputed weights, even above the 4 GB limit. Our trick is to backproject into slices that are rotated in the same manner as the spiral trajectory rotates. Using the spiral symmetry in this way allows one to exploit data-level paralellism and thereby to achieve a very high level of vectorization. An additional postprocessing step rotates these slices back to normal images. Our new backprojection algorithm achieves up to 17 giga voxel updates per second on our systems that are equipped with four standard Intel X7460 hexa core CPUs (Intel Xeon 7300 platform, 2.66 GHz, Intel Corporation). This equals the reconstruction of 344 images per second assuming that each slice consists of 512 × 512 pixels and receives contributions from 512 projections. Thereby, it is an order of magnitude faster than a highly optimized code that does not make use of the spiral symmetry. In its present version, the

  8. High performance cone-beam spiral backprojection with voxel-specific weighting.

    PubMed

    Steckmann, Sven; Knaup, Michael; Kachelriess, Marc

    2009-06-21

    Cone-beam spiral backprojection is computationally highly demanding. At first sight, the backprojection requirements are similar to those of cone-beam backprojection from circular scans such as it is performed in the widely used Feldkamp algorithm. However, there is an additional complication: the illumination of each voxel, i.e. the range of angles the voxel is seen by the x-ray cone, is a complex function of the voxel position. In general, one needs to multiply a voxel-specific weight w(x, y, z, alpha) prior to adding a projection from angle alpha to a voxel at position x, y, z. Often, the weight function has no analytically closed form and must be numerically determined. Storage of the weights is prohibitive since the amount of memory required equals the number of voxels per spiral rotation times the number of projections a voxel receives contributions and therefore is in the order of up to 10(12) floating point values for typical spiral scans. We propose a new algorithm that combines the spiral symmetry with the ability of today's 64 bit operating systems to store large amounts of precomputed weights, even above the 4 GB limit. Our trick is to backproject into slices that are rotated in the same manner as the spiral trajectory rotates. Using the spiral symmetry in this way allows one to exploit data-level paralellism and thereby to achieve a very high level of vectorization. An additional postprocessing step rotates these slices back to normal images. Our new backprojection algorithm achieves up to 17 giga voxel updates per second on our systems that are equipped with four standard Intel X7460 hexa core CPUs (Intel Xeon 7300 platform, 2.66 GHz, Intel Corporation). This equals the reconstruction of 344 images per second assuming that each slice consists of 512 x 512 pixels and receives contributions from 512 projections. Thereby, it is an order of magnitude faster than a highly optimized code that does not make use of the spiral symmetry. In its present version

  9. 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.

  10. Preparation of diamond-like carbon and boron nitirde films by high-intensity pulsed ion beam deposition

    SciTech Connect

    Rej, D.J.; Davis, H.A.; Remnev, G.E.

    1995-05-01

    Intense ion beams (300-keV C{sup +}, O{sup +}, and H{sup +}, 20--30 kA, 50 to 400-ns pulsewidth, up to 0.3-Hz repetition rate) were used to prepare diamond-like carbon (DLC) and boron nitride (BN) films. Deposition rates of up to 25{plus_minus}5 nm/pulse were obtained with instantaneous rates exceeding 1 mm/s. Most films were uniform, light brown, translucent, and nonporous with some micron-size particulates. Raman and parallel electron energy loss spectroscopy indicated the presence of DLC. The films possessed favorable electron field-emission characteristics desirable for cold-cathode displays. Transmission electron microscopy (TEM) and transmission electron diffraction (TED) revealed that the C films contained diamond crystals with 25 to 125-nm grain size. BN films were composed of hexagonal, cubic and wurtzite phases.

  11. 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.

  12. Performance of the Carbon Dioxide Information Analysis Center (CDIAC)

    SciTech Connect

    Stoss, F.W.; Jones, S.B.

    1993-11-01

    The Carbon Dioxide Information Analysis Center (CDIAC) provides information and data resources in support of the US Department of Energy`s Global Change Research Program. CDIAC also serves as a resource of global change information for a broader international commonly of researchers, policymakers, managers, educators, and students. The number of requests for CDIAC`s data products, information services, and publications has grown over the years and represents multidisciplinary interests in the physical, life, and social sciences and from diverse work settings in government, business, and academia. CDIAC`s staff addresses thousands of requests yearly for data and information resources. In response to these requests, CDIAC has distributed tens of thousands of data products, technical reports, newsletters, and other information resources worldwide since 1982. This paper describes CDIAC, examines CDIAC`s user community, and describes CDIAC`s response to requests for information. The CDIAC Information System, which serves as a comprehensive PC-based inventory and information management tracking system, is also described.

  13. Design features and performance of the LAMPF high-intensity beam area

    SciTech Connect

    Agnew, L.; Grisham, D.; Macek, R.J.; Sommer, W.F.; Werbeck, R.D.

    1983-01-01

    LAMPF is a multi-purpose high-intensity meson factory capable of producing a 1 mA beam of 800-MeV protons. The three target cells and the beam stop facilities in the high intensity area have many special design features that are required for operation in the presence of high heat loads and intense radiation fields where accessibility is extremely limited. Reliable targets, beam windows, beam stops, beam transport and diagnostic components, vacuum enclosures, and auxiliary systems have been developed. Sophisticated remote-handling systems are employed for maintenance. Complex protection systems have been developed to guard against damage caused by errant beam. Beam availability approaching 90% has been achieved at currents of 600 to 700 ..mu..A. A new facility for direct proton and neutron radiation effects studies will be installed in 1985. The new facility will provide an integrated spallation neutron flux of up to 5 x 10/sup 17/ m/sup -2/s/sup -1/ and will anable proton irradiation studies in the primary beam.

  14. 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.

  15. Design and performance analysis of an ultraprecision ion beam polishing tool.

    PubMed

    Lu, Ying; Xie, Xuhui; Zhou, Lin

    2016-03-01

    First, we introduce requirements for the ion beam polishing tool used in the subnanometer precision process. Based on the ion beam figuring (IBF) principle, the definitive factor of the IBF capability is analyzed, and the deficiencies of the ion beam polishing tool are identified. The effect of focused ion optics on the ion beam removal function is based on theoretic calculation and computer simulation; and focused three-grid ion optics are developed and tested. Finally, a 150 mm flat optics element is figured and results show that the contour error decreases from 15.58 nm RMS to 0.796 nm RMS, demonstrating that the ion beam polishing tool is very efficient for optical IBF. PMID:26974611

  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. PMID:26932029

  17. High-Performance Soft-Tissue Imaging in Extremity Cone-Beam CT

    PubMed Central

    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.

    2014-01-01

    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 5·106 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. PMID:25076825

  18. Performance of beta tool for low-energy electron-beam proximity-projection lithography (LEEPL)

    NASA Astrophysics Data System (ADS)

    Yoshida, Akira; Kasahara, Haruo; Higuchi, Akira; Nozue, Hiroshi; Endo, Akihiro; Shimazu, Nobuo

    2003-06-01

    The two LEEPL beta-tools were completed in earlier 2002 and have been evaluated for the performance. 50nm CH patterns and 70nm L/S patterns are attained and the CD uniformity of 70nm L/S patterns with 37 shots on a 200mm wafer is under 4nm with the LEEPL beta-tools. In addition, it is proven that the fine tuning deflector can correct a mask and a wafer distortion by giving a minute angle to the electron beam. The mask distortion with respect to orthogonality and magnification is decreased on a wafer by 1/5. By means of this fine tuning deflector, Mix & Match accuracy with any other lithography tools will be better and difficulty of 1X stencil mask fabrication wil be easier. Referring to the data which has been obtained with the evaluation of the LEEPL beta-tools, the first LEEPL production tool dubbed "LEEPL-3000" is under construction to realize the satisfactory ability for 65nm node device fabrication. The shipping of the first LEEPL-3000 is scheduled in earlier 2003 and it is earlier than any other Next Generation Lithography technologies.

  19. 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.

  20. 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.

  1. Fabrication and characterization of tunnel barriers in a multi-walled carbon nanotube formed by argon atom beam irradiation

    NASA Astrophysics Data System (ADS)

    Tomizawa, H.; Yamaguchi, T.; Akita, S.; Ishibashi, K.

    2015-07-01

    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.

  2. A study on focused ion beam milling of glassy carbon molds for the thermal imprinting of quartz and borosilicate glasses

    NASA Astrophysics Data System (ADS)

    Youn, Sung Won; Takahashi, Masaharu; Goto, Hiroshi; Maeda, Ryutaro

    2006-12-01

    The need for a flexible, low-cost and high-throughput process for the fabrication of a nano/micro glass-based micro fluidic device is becoming increasingly acute as the bio-MEMS industry is expanding very fast. In this study, repetitive-pass milling with a focused ion beam (FIB) was used for maskless and resistless fabrication of glassy carbon (GC) molds, which will then be the primary elements in the mass production of nano/micro glass devices by mold replication processes. The aim of the study is to establish basic process conditions and to investigate possible problems that occur during both FIB milling of GC and thermal imprint of glasses. First, the milled depth-beam dwell time curve for GC was investigated experimentally, and the relationship between the areal ion dose and the milled depth was formulated for application to the design of mold parts using FIB milling. Then, GC molds were produced and used for imprinting glasses to make micro fluidic parts. Surface contamination due to the FIB milling could be eliminated by a vacuum heat treatment at 1400 °C for 10 min. Finally, a dimensional mismatch arising from a thermal expansion coefficient mismatch between the GC mold and the glass materials was discussed. This article was presented at the 1st Topical Meeting on Microfactories 'Desktop MEMS and Nano Factories', Tsukuba, Japan, 17-19 October 2005.

  3. 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.

  4. Erosion and erosion products of tungsten and carbon-based materials irradiated by a high energy electron beam

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Yoshida, Naoaki; Noda, Nobuaki; Zhang, Fu; Xu, Zengyu; Liu, Yong

    2003-03-01

    A pulsed electron beam test was used to simulate the thermal response of plasma facing materials under high heat loads during plasma disruptions, particularly for relatively 'long' duration off-normal events such as plasma vertical displacement events. The erosion and erosion products of purified tungsten made by powder metallurgy (PM-W), W and B 4C plasma sprayed coatings on CFC or copper and C/C composite were investigated. The time evolution of the target current indicates that the erosion products or screening clouds partly or completely shield the incident electron beam, leading to a reduction of the target current and changes in the target current profile. The weight loss of PM-W is smaller than that of the tungsten coating or C/C composite, which is in agreement with the erosion behavior. Erosion products indicate that evaporation is a major erosion mechanism of PM-W, and exfoliation and particle emission are the dominant erosion mechanisms of carbon-based materials and W plasma sprayed coatings.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. Adsorption and desorption performance of benzene over hierarchically structured carbon-silica aerogel composites.

    PubMed

    Dou, Baojuan; Li, Jinjun; Wang, Yufei; Wang, Hailin; Ma, Chunyan; Hao, Zhengping

    2011-11-30

    Hierarchically structured carbon-silica aerogel (CSA) composites were synthesized from cheap water glass precursors and granulated activated carbon via a post-synthesis surface modification with trimethylchlorosilane (TMCS) and a low-cost ambient pressure drying procedure. The resultant CSA composites possess micro/mesoporous structure and hydrophobic surface. The adsorption and desorption performance of benzene on carbon-silica aerogel composite (CSA-2) under static and dynamic conditions were investigated, comparing with pure silica aerogel (CSA-0) and microporous activated carbon (AC). It was found that CSA-2 has high affinity towards aromatic molecules and fast adsorption kinetics. Excellent performance of dynamic adsorption and desorption observed on CSA-2 is related to its higher adsorption capacity than CSA-0 and less mass transfer resistance than AC, arising from the well-developed microporosity and open foam mesostructure in the CSA composites. PMID:21962860

  10. 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

  11. 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.

  12. 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. PMID:25692264

  13. 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.

  14. 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

  15. 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.

  16. Correlation study of structural, optical and electrical properties of amorphous carbon thin films prepared by ion beam sputtering deposition technique

    NASA Astrophysics Data System (ADS)

    Mohagheghpour, E.; Rajabi, M.; Gholamipour, R.; Larijani, M. M.; Sheibani, S.

    2016-01-01

    The correlation of structural, optical and electrical properties of amorphous carbon thin films deposited by ion beam sputtering technique on the glass substrate was investigated. The film thickness varied over a wide range from 57 to 408 nm by controlling the deposition time. Raman spectra and X-ray photoelectron spectroscopy showed that the size of the graphite crystallites with sp2 bonds (La) and the sp3/sp2 fraction are smaller than 1.5 nm and 1.4, respectively. The values of ID/IG ratio, the 'G' peak position, and surface roughness depend on the film thickness; all of them increased by increasing film thickness up to 360 nm, and then decreased by increasing time and thickness. Furthermore, the resistivity followed similar trends of these structural properties. According to Tauc equation the optical band gap of these films was in the range of 3.2-3.9 eV. A broad emission peak at around 2.94 eV was observed on a photoluminescence spectrum of amorphous carbon film with highest resistivity.

  17. Inactive and mutagenic effects induced by carbon beams of different LET values in a red yeast strain

    NASA Astrophysics Data System (ADS)

    Wang, Jufang; Lu, Dong; Wu, Xin; Sun, Haining; Ma, Shuang; Li, Renmin; Li, Wenjian

    2010-09-01

    To evaluate biological action of microorganism exposed to charged particles during the long distance space exploration, induction of inactivation and mutation in a red yeast strain Rhodotorula glutinis AY 91015 by carbon beams of different LET values (14.9-120.0 keV μm -1) was investigated. It was found that survival curves were exponential, and mutation curves were linear for all LET values. The dependence of inactivation cross section on LET approached saturation near 120.0 keV μm -1. The mutation cross section saturated when LET was higher than 58.2 keV μm -1. Meanwhile, the highest RBE i for inactivation located at 120.0 keV μm -1 and the highest RBE m for mutation was at 58.2 keV μm -1. The experiments imply that the most efficient mutagenic part of the depth dose profile of carbon ion is at the plateau region with intermediate LET value in which energy deposited is high enough to induce mutagenic lesions but too low to induce over kill effect in the yeast cells.

  18. Ion Beam Induced Charge Collection (IBICC) from Integrated Circuit Test Structures Using a 10 MeV Carbon Microbeam

    SciTech Connect

    Aton, T.J.; Doyle, B.L.; Duggan, J.L.; El Bouanani, M.; Guo, B.N.; McDaniel, F.D.; Renfrow, S.N.; Walsh, D.S.

    1998-11-18

    As future 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 1pm diameter spot to scan test structures on specifically designed ICS. With the aid of layout information, an analysis of the charge collection efficiency from different test areas is presented. In the present work a 10 MeV Carbon high-resolution microbeam was used to demonstrate the differential charge collection efficiency in ICS with the aid of the IC design Information. When ions strike outside the FET, the charge was only measured on the outer ring, and decreased with strike distance from this diode. When ions directly strike the inner and ring diodes, the collected charge was localized to these diodes. The charge for ions striking the gate region was shared between the inner and ring diodes. I The IBICC measurements directly confirmed the interpretations made in the earlier work.

  19. 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

  20. 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.

  1. 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

  2. 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. PMID:26910405

  3. Performance evaluation of a metal-insulator-metal surface plasmon resonance optical gas sensor under the effect of Gaussian beams.

    PubMed

    Anous, Noha H; Khalil, Diaa A

    2014-04-10

    In this work, the performance of a nonconventional IR surface plasmon resonance (SPR) gas sensor structure based on the use of a metal-insulator-metal (MIM) structure is studied. This MIM-based sensor structure gives enhanced performance five times better than the conventional MI SPR optical gas sensors. The performance of the SPR gas sensors is studied under the effect of oblique incident Gaussian beams with different spot sizes, and the performance enhancement of the MIM structure is confirmed for different spot sizes. The simulation technique used to generate the results is also verified by comparing them to actual experimental results available in the literature. PMID:24787425

  4. 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

  5. (abstract) Effect of Electrolyte Composition on Carbon Electrode Performance

    NASA Technical Reports Server (NTRS)

    Huang, C-K.; Surampudi, S.; Shen, D. H.; Halpert, G.

    1993-01-01

    Rechargeable lithium cells containing lithium foil anodes are reported to have limited cycle life (at 100% DOD) performance and safety problems. These limitations are understood to be due to the high reactivity of elemental Li with the electrolyte and the formation of high surface area Li during cycling. To mitigate these problems, several lithium alloys and lithium intercalation compounds are being investigated as alternate lithium anode materials. Li(sub x)C has been identified as a promising lithium anode material due to its low equivalent weight, low voltage vs. Li, and improved stability towards various electrolytes. In this paper, we report the results of our studies on the electrolyte evaluation for the Li(sub x)C anode.

  6. Performance of MBE-4: An experimental multiple beam induction linear accelerator for heavy ions

    SciTech Connect

    Warwick, A.I.; Fessenden, T.J.; Keefe, D.; Kim, C.H.; Meuth, H.

    1988-06-01

    An experimental induction linac, called MBE-4, has been constructed to demonstrate acceleration and current amplification of multiple heavy ion beams. This work is part of a program to study the use of such an accelerator as a driver for heavy ion inertial fusion. MBE-4 is 16m long and accelerates four space-charge-dominated beams of singly-charged cesium ions, in this case from 200 keV to 700 keV, amplifying the current in each beam from 10mA by a factor of nine. Construction of the experiment was completed late in 1987 and we present the results of detailed measurements of the longitudinal beam dynamics. Of particular interest is the contribution of acceleration errors to the growth of current fluctuations and to the longitudinal emittance. The effectiveness of the longitudinal focusing, accomplished by means of the controlled time dependence of the accelerating fields, is also discussed. 4 refs., 5 figs., 1 tab.

  7. Design and performance of the traveling-wave beam chopper for the SSRL injector

    SciTech Connect

    Borland, M.; Weaver, J.N.; Baltay, M.; Emery, L.; Fisher, A.S.; Golceff, P.; Hettel, R.; Morales, H.; Sebek, J.; Wiedemann, H.; Youngman, B. . Stanford Synchrotron Radiation Lab.); Anderson, R. ); Miller, R.H. )

    1991-05-01

    A pulsed, split-parallel plate chopper has been designed built, and installed as part of the preinjector of the SSRL Injector. Its function is to allow the linear accelerator three consecutive S-band bunches from the long bunch train provided by a RF gun. A permanent magnet deflector (PMD) at the chopper entrance deflects the beam into an absorber when the chopper pulse is off. The beam is swept across a pair of slits at the beam output end when a 7 kV, 10-ns rise-time pulse passes in the opposite direction through the 75 {Omega} stripline formed by the deflecting plates. Bunches exiting the slits have their trajectories corrected by another PMD, and enter the linac. Beam tests demonstrate that the chopper functions as expected. 9 refs., 5 figs.

  8. 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.

  9. Achieving enhanced DSSC performance by microwave plasma incorporation of carbon into TiO2 photoelectrodes

    NASA Astrophysics Data System (ADS)

    Dang, Binh H. Q.; MacElroy, Don; Dowling, Denis P.

    2013-06-01

    The photoactivity of carbon-incorporated titanium dioxide (TiO2) has been widely reported. This study involves a novel approach to the incorporation of carbon into TiO2 through the use of microwave plasma processing. The process involved thermally treating printed TiO2 nanoparticle coatings in a microwave-induced argon-oxygen plasma containing low concentrations of methane. The resulting deposited carbon layer was characterized using XRD, XPS, Raman, UV-vis, ellipsometry, and optical profilometry. It was found that the methane gas was dissociated in the microwave plasma into its carbon species, which were then deposited as a nm-thick layer onto the TiO2 coatings, most likely in the form of graphite. The photovoltaic performances of both the TiO2 and the carbon-incorporated TiO2 were assessed through J-V and IPCE measurements of the N719-sensitized solar cells using the titania as their photoanodes. Up to a 72% improvement in the maximum power density (Pd-max) was observed for the carbon-incorporated TiO2 samples as compared to the TiO2, onto which no carbon was added. This improvement was found to be mainly associated with an increase in the short-circuit current density (Jsc), but independent from the open-circuit voltage (Voc), the filter factor (FF), and the level of dye adsorption. Possible contributory factors to the improved performance of the carbon-incorporated TiO2 were the enhanced electron conductivity and electron lifetime, both of which were elucidated through electrochemical impedance spectroscopy (EIS). When the surface layer was examined using XPS, the optimal carbon content on the TiO2 coating surface was found to be 8.4%, beyond which there was a reduction in the DSSC efficiency.

  10. Reflectance measurements and optical constants in the extreme ultraviolet of thin films of ion-beam-deposited carbon

    NASA Astrophysics Data System (ADS)

    Larruquert, Juan I.; Keski-Kuha, Ritva A. M.

    2000-09-01

    Reflectance measurements of ion-beam-deposited (IBD) C films were performed in the extreme ultraviolet (EUV) spectral region from 49 to 200 nm. Near normal incidence reflectance of IBD C films was determined to be higher than that of evaporated C films but lower than that of diamond. Optical constants of IBD C films were obtained from reflectance measurements as a function of the angle of incidence in the spectral range 49.0-121.6 nm. The relatively high reflectance of IBD C films in the spectral region 49-92 nm and its stability when stored in a desiccator make it an interesting coating material for the EUV.

  11. Effects of ion beam heating on Raman spectra of single-walled carbon nanotubes

    SciTech Connect

    Hulman, Martin; Skakalova, Viera; Krasheninnikov, A. V.; Roth, S.

    2009-02-16

    Free standing films of single-wall carbon nanotubes were irradiated with energetic N{sup +} and C{sup 4+} ions. The observed changes in the Raman line shape of the radial breathing mode and the G band of the C{sup 4+} irradiated samples were similar to those found for a thermally annealed sample. We ascribe these changes to thermal desorption of volatile dopants from the initially doped nanotubes. A simple geometry of the experiment allows us to estimate the temperature rise by one-dimensional heat conductance equation. The calculation indicates that irradiation-mediated increase in temperature may account for the observed Raman spectra changes.

  12. Equilibrium thickness of carbon target interacting with nitrogen and neon ion beams

    NASA Astrophysics Data System (ADS)

    Belkova, Yu. A.; Novikov, N. V.; Teplova, Ya. A.

    2016-04-01

    The method for calculation of the target thickness which is required for the formation of equilibrium charge distribution of ions is proposed. The description of nonequilibrium processes is based on empirical estimations of charge-exchange cross sections, taking the density effect for solids into account. The variation of the average charge and the width of the nonequilibrium charge distribution as a function of the target thickness is analyzed. The results of calculations for nitrogen and neon ions in carbon are compared with experimental data.

  13. Laser beam hardening of cast carbon steels, plain cast irons, and high-speed steels

    NASA Astrophysics Data System (ADS)

    Bylica, Andrzej; Adamiak, Stanislaw; Bochnowski, Wojciech; Dziedzic, Andrzej

    2000-11-01

    The examinations of the structure, hardness and abrasion resistance of surface layer of Fe-C alloys having the contents of carbon up to 4% and high-speed steel: 6-5-2, 4- 4-2-5+C after laser hardening are presented in the paper. They are compared with the properties obtained after conventional hardening. Laser of impulse operation - YAG:Nd and of continuous operation - CO2 were used. Analysis of structure was carried out based on metallographic and fractographic examinations as well as on X-ray properties, parameters of laser and conventional heat treatment of steels were defined.

  14. 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.

  15. 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

  16. AFM investigation on surface evolution of amorphous carbon during ion-beam-assisted deposition

    NASA Astrophysics Data System (ADS)

    Zhu, X. D.; Ding, F.; Naramoto, H.; Narumi, K.

    2006-11-01

    Hydrogen-free amorphous carbons (a-C) have been prepared on mirror-polished Si(1 1 1) wafers through thermally evaporated C 60 with simultaneous bombardments of Ne + ions. The time evolution of film surfaces has been characterized by atomic force microscopy (AFM) at two temperatures of 400 and 700 °C, respectively. Based on the topography images and the root-mean-square (rms) roughness analysis, it is found that the a-C surfaces present roughening growth at the initial stage. With increasing growth time, the cooperative nucleation of the islands and pits appears on the surfaces, suggesting three-dimensional growth, and then they continue to evolve to irregular mounds at 400 °C, and elongated mounds at 700 °C. At the steady growth stage, these surfaces further develop to the structures of bamboo joints and ripples corresponding to these two temperatures, respectively. It is believed that besides ion sputtering effect, the chemical bonding configurations in the amorphous carbon films should be taken into considerations for elucidating the surface evolutions.

  17. Electrochemical Corrosion Behavior of Low Carbon I-Beam Steels In Simulated Yucca Mountain Repository Environment

    SciTech Connect

    Arjunan, Venugopal; Lamb, Joshua; Chandra, Dhanesh; Daemen, Jack; Jones, Denny A.; Engelhard, Mark H.; Lea, Alan S.

    2005-04-01

    The electrochemical corrosion behavior of low carbon steel was examined in a simulated Yucca Mountain (YM) ground water by varying the electrolyte concentration and temperature under aerated and deaerated conditions. The results show that in deaerated conditions, the corrosion rate is low in the order of 0.6 to 4.5mpy, between 25 to 85 C, respectively. However, in aerated conditions the measured rates were expectedly very high, in the order of 3-55mpy in the above mentioned temperature levels. The rates initially increased up to 45 C, and a decreasing trend was observed with further increase in temperature from 65 to 85 C. The maximum corrosion rate was occurred at 45 C (54.5mpy). The low corrosion rates observed in all deaerated conditions, and in aerated solutions at higher temperatures were due to the preferential adsorption of Mg-species on the steel surface, as identified by XPS analyses. The results also indicate possible localized corrosion behavior of carbon steel in aerated conditions up to 45 C.

  18. 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. PMID:24022913

  19. 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. PMID:25154880

  20. Performance comparison of front-side silver pastes using polyalkylene carbonates for cleaner burning binder system

    NASA Astrophysics Data System (ADS)

    Stephenson, Richard; Ferraro, Peter

    2015-09-01

    Clean-burning binder systems used in paste formulations for front side solar cell applications offer advantages of reduced residual carbon, improved conductive feature density, and overall performance and reliability. This paper presents the technical advantages of employing polyalkylene carbonates (QPAC®) as the principle binder for paste formulations used in front side solar screen printing applications. Thermal and rheological characteristics are presented and compared with standard or conventional pastes currently employed in production lines producing solar cell front side geometry. Microstructural comparisons of conductive features of the front side geometry are examined and related to aspects of adhesion performance and resistive losses.

  1. High Performance Perovskite Hybrid Solar Cells with E-beam-Processed TiOx Electron Extraction Layer.

    PubMed

    Meng, Tianyu; Liu, Chang; Wang, Kai; He, Tianda; Zhu, Yu; Al-Enizi, Abdullah; Elzatahry, Ahmed; Gong, Xiong

    2016-01-27

    Perovskite hybrid solar cells (pero-HSCs) have drawn great attention in the last 5 years. The efficiencies of pero-HSCs have been boosted from 3.8% to over 20%. However, one of the bottlenecks for commercialization of pero-HSCs is to make a high electrical conductive TiOx electron extraction layer (EEL). In this study, we report high performance pero-HSCs with TiOx EEL, where the TiOx EEL is fabricated by electron beam (e-beam) evaporation, which has been proved to be a well-developed manufacturing process. The resistance of the e-beam evaporated TiOx EEL is smaller than that of sol-gel processed TiOx EEL. Moreover, the dark current densities and interfacial charge carrier recombination of pero-HSCs incorporated with e-beam processed TiOx EEL is also smaller than that of pero-HSCs incorporated with sol-gel processed TiOx EEL. All these result in efficient pero-HSCs with high reproducibility. These results demonstrate that our method provides a simple and facile way to approach high performance pero-HSCs. PMID:26727027

  2. 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

  3. 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

  4. 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. PMID:21168964

  5. 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.

  6. The Effect of Laser Surface Reconstruction of Disordered Carbons on Performance

    SciTech Connect

    EVEN JR., WILLIAM R.; GUIDOTTI, RONALD A.

    1999-10-06

    The reconstruction of the surface of disordered carbons was examined by heating carbons derived from polymethacrylonitrile (PMAN) and divinylbenzene (DVB) with a pulsed infrared laser in an argon or helium atmosphere, both fluidized and under static conditions. By graphitizing the outer surface of the carbons, it was hoped to reduce the high first-cycle losses associated with such disordered materials in Li-ion cells. The power to the sample was varied to observed the effects on surface morphology and electrochemical performance in 1M LiPF{sub 6} ethylene carbonate-dimethyl carbonate. The use various reactive atmosphere such as ethylene, 2-vinylpyridine, pyrrole, and furfuryl alcohol were also evaluated as an alternative means of hopefully forming a thin graphitic layer on the carbon particles to reduce first-cycle irreversibility. While some improvement was realized, these losses were still unacceptably high. The laser heating did improve the rate capabilities of the carbons, however. More work in this area is necessary to fully understand surface and bulk effects.

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. High nitrogen-containing cotton derived 3D porous carbon frameworks for high-performance supercapacitors.

    PubMed

    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 m(2) 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

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. Improved MCFC performance with Li/Na/Ba/Ca carbonate electrolyte.

    SciTech Connect

    Centeno, C.-J.; Kaun, T. D.; Krumpelt, M.; Schoeler, A.

    1999-07-21

    Earlier electrolyte segregation tests of Li/Na carbonate used chemical analysis such as inductively coupled plasma/atomic emission spectroscopy (ICP/AES) of matrix strips wetted with carbonate and exposed to 5- to 20-V potential gradients. A segregation factor was correlated to the Li/Na carbonate composition. While fairly substantial segregation occurs at the eutectic composition of 52% Li, it is minimal at 60% to 75% Li. Such lithium-rich Li/Na carbonates may not be practical because the melting points are too high (i.e., liquidus point is 625 C). By adding calcium and barium to the lithium/sodium carbonates, we were able to lower the melting point and maintain nonsegregating behavior. This work is directed at examining the long-term stability of the quaternary Li/Na/Ba/Ca electrolytes. Electrolyte optimization work evaluates Li/Na ratio and Ba/Ca level to improve cell performance at 320 mA/cm{sup 2} and reduce temperature sensitivity. A number of cells with quaternary Li/Na/Ba/Ca electrolytes ranging from 3 to 5% Ba/Ca have operated well with stable, long-term performance. Congruent melting carbonate is important for commercial development. The best so far is 3.5% Ba/Ca/Na/Li (3.5 mol%/3.5 mol% Ba/Ca) carbonate (m.p. 440 C). Performance at 160 mA/cm{sup 2} is increased up to 150mV as compared with the baseline cell containing the Li/Na eutectic composition. Life stability has been reproduced by a number of bench-scale MCFC test with operations of 2000-4300 h and the electrolyte composition across the matrix little changed.

  17. 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.

  18. 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.

  19. 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.

  20. The EGFR mutation status affects the relative biological effectiveness of carbon-ion beams in non-small cell lung carcinoma cells

    PubMed Central

    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

  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

    2015-01-01

    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

  2. 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. PMID:26449440

  3. Radiation processing of Nylon 6 by e-beam for improved properties and performance

    NASA Astrophysics Data System (ADS)

    Pramanik, N. K.; Haldar, R. S.; Bhardwaj, Y. K.; Sabharwal, S.; Niyogi, U. K.; Khandal, R. K.

    2009-03-01

    Percent water absorption of Nylon 6 was reduced substantially when irradiated by e-beam radiation in presence of triallyl isocyanurate. Hardness, tensile strength, flexural strength, and impact resistance of Nylon 6 were also improved with the dose of e-beam radiation. Improvement of mechanical properties and reduction of water absorption were due to the cross-linking of polyamide molecules in the presence of high-energy radiation. Increase of cross-linking with increasing radiation dose was verified by the increase of gel content at higher doses.

  4. 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.

  5. 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...

  6. Ordered mesoporous carbon nanochannel reactors for high-performance Fischer-Tropsch synthesis.

    PubMed

    Ha, Kyoung-Su; Kwak, Geunjae; Jun, Ki-Won; Hwang, Jongkook; Lee, Jinwoo

    2013-06-01

    A hexagonally ordered mesoporous carbon, CMK-3, was utilized as a support for a Fischer-Tropsch catalyst. Each array of elongated pore structures with Co nanoparticles can be regarded as a nanochannel reactor. Due to the pore confinement and the hydrophobic nature of the support, this catalyst demonstrated excellent catalytic performance. PMID:23482917

  7. 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

  8. 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...

  9. PERFORMANCE AND MODELING OF A HOT POTASSIUM CARBONATE ACID GAS REMOVAL SYSTEM IN TREATING COAL GAS

    EPA Science Inventory

    The report discusses the performance and modeling of a hot potassium carbonate (K2CO3) acid gas removal system (AGRS) in treating coal gas. Aqueous solutions of K2CO3, with and without amine additive, were used as the acid gas removal solvent in the Coal Gasification/Gas Cleaning...

  10. 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

  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. 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.

  13. 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.

  14. 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.

  15. Capacitive performance of ordered mesoporous carbons with tunable porous texture in ionic liquid electrolytes

    NASA Astrophysics Data System (ADS)

    Zhou, Jin; Xing, Wei; Zhuo, Shuping; Zhao, Yi

    2011-11-01

    Ordered mesoporous carbons with tunable pore size and surface chemical properties are prepared by doping boric acid using a hard-templating method. The capacitive performance of these carbons is investigated in two common ionic liquids of EMImBF 4 and EMImTSFI. As demonstrated by the structure analysis, the pore size increases from 3.3 to 5.7 nm and the content of oxygenated groups on the carbon surface increases from 2.0 to 5.2 mol% with the increase of the boron doping from 0 to 50 mol%. In ionic liquid electrolyte, the carbons mainly show typical electric double layer capacitance, and the capacitance retention ratio and ion diffusion in the carbon channels is determined to the surface chemical property. The prepared carbons present visible pseudo-capacitance due to the rapid redox reactions of the oxygenated groups in hydrophilic EMImBF 4, reflecting by the increasing of the specific surface capacitance, while no visible pseudo-capacitive behavior was observed in hydrophobic EMImTSFI.

  16. Synthesis of N-Doped Hollow-Structured Mesoporous Carbon Nanospheres for High-Performance Supercapacitors.

    PubMed

    Liu, Chao; Wang, Jing; Li, Jiansheng; Zeng, Mengli; Luo, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing; Wang, Lianjun

    2016-03-23

    We have demonstrated a facile and controllable synthesis of monodispersed N-doped hollow mesoporous carbon nanospheres (N-HMCSs) and yolk-shell hollow mesoporous carbon nanospheres (N-YSHMCSs) by a modified "silica-assisted" route. The synthesis process can be carried out by using resorcinol-formaldehyde resin as a carbon precursor, melamine as a nitrogen source, hexadecyl trimethylammonium chloride as a template, and silicate oligomers as structure-supporter. The morphological (i.e., particle size, shell thickness, cavity size, and core diameter) and textural features of the carbon nanospheres are easily controlled by varying the amount of ammonium. The resultant carbon nanospheres possess high surface areas (up to 2464 m(2) g(-1)), large pore volumes (up to 2.36 cm(3) g(-1)), and uniform mesopore size (∼2.4 nm for N-HMCSs, ∼ 4.5 nm for N-YSHMCSs). Through combining the hollow mesoporous structure, high porosity, large surface area, and N heteroatomic functionality, the as-synthesized N-doped hollow-structured carbon nanospheres manifest excellent supercapacitor performance with high capacitance (up to 240 F/g), favorable capacitance retention (97.0% capacitive retention after 5000 cycles), and high energy density (up to 11.1 Wh kg(-1)). PMID:26942712

  17. 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.

  18. PERFORMANCE EVALUATION OF PARTICLE BEAM LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY FOR THE MEASUREMENT OF ACID HERBICIDES

    EPA Science Inventory

    Particle beam liquid chromatography/mass spectrometry (LC/MS) was evaluated for the measurement of acid herbicides. n acetic acid/ammonium acetate/methano1 solvent system with a C-8 reversed Phase column gave baseline resolution of all target analytes. etection limits in the full...

  19. 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.

  20. 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.