Klynac: Compact Linear Accelerator with Integrated Power Supply

NASA Astrophysics Data System (ADS)

Malyzhenkov, A. V.

Accelerators and accelerator-based light sources have a wide range of applications in science, engineering technology and medicine. Today the scientific community is working towards improving the quality of the accelerated beam and its parameters, while trying to develop technology for reducing accelerator size. This work describes a design of a compact linear accelerator (linac) prototype: resonant Klynac device, which is a combined linear accelerator and its power supply - klystron. The intended purpose of a Klynac device is to provide a compact and inexpensive alternative to a conventional 1 to 6 MeV accelerator, which typically requires a separate RF source, accelerator itself and all the associated hardware. Because the Klynac is a single structure, it has the potential to be much less sensitive to temperature variations than a system with separate klystron and linac. We start by introducing a simplified theoretical model for a Klynac device. We then demonstrate how a prototype is designed step-by-step using Particle-In-Cell simulation studies for mono-resonant and bi-resonant structures. Finally, we discuss design options from a stability point of view and required input power as well as behavior of competing modes for the actual built device.

Compact and tunable focusing device for plasma wakefield acceleration

NASA Astrophysics Data System (ADS)

Pompili, R.; Anania, M. P.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Lollo, V.; Notargiacomo, A.; Picardi, L.; Ronsivalle, C.; Rosenzweig, J. B.; Shpakov, V.; Vannozzi, A.

2018-03-01

Plasma wakefield acceleration, either driven by ultra-short laser pulses or electron bunches, represents one of the most promising techniques able to overcome the limits of conventional RF technology and allows the development of compact accelerators. In the particle beam-driven scenario, ultra-short bunches with tiny spot sizes are required to enhance the accelerating gradient and preserve the emittance and energy spread of the accelerated bunch. To achieve such tight transverse beam sizes, a focusing system with short focal length is mandatory. Here we discuss the development of a compact and tunable system consisting of three small-bore permanent-magnet quadrupoles with 520 T/m field gradient. The device has been designed in view of the plasma acceleration experiments planned at the SPARC_LAB test-facility. Being the field gradient fixed, the focusing is adjusted by tuning the relative position of the three magnets with nanometer resolution. Details about its magnetic design, beam-dynamics simulations, and preliminary results are examined in the paper.

Modeling Firn Compaction in Dynamic Regions

NASA Astrophysics Data System (ADS)

Horlings, Annika N.; Christianson, Knut; Waddington, Edwin D.; Stevens, C. Max; Holschuh, Nicholas

2017-04-01

Firn compaction remains the largest source of uncertainty in assessments of ice-sheet mass balance from repeat altimetry measurements due to our limited understanding of the physical processes responsible for the transformation of snow into ice. In addition to the lack of a comprehensive, physically-based constitutive relationship that describes firn compaction, dynamic thinning is an important process in some regions, but is generally neglected in firn-compaction models due to their one-dimensional nature. Here, we report on preliminary results incorporating dynamic strain thinning into firn compaction models. Using a Lagrangian (material-following) reference frame, we first compact each firn element using a standard 1-D firn-compaction model without longitudinal strain. Then, we stretch each firn parcel at each time step by applying a prescribed longitudinal strain rate in the absence of further density changes; this produces additional vertical thinning. To assess variations among firn models, we compare results from eight firn densification models currently included in the UW Community Firn Model. We focus on the Northeast Greenland Ice Stream due to the high extensile strain rates (10-3 yr-1 or higher) in the ice stream's shear margins and the extensive firn-density data in this area from seismic measurements and shallow firn/ice cores. For temperatures and accumulation rates typical for northeast Greenland, our preliminary results indicate up to an 18-meter decrease in bubble close-off depth in the shear margins compared to nearby areas either inside or outside the ice stream, which compares favorably to field data. Further work includes incorporating physically-based constitutive relations and applying these improved models to other dynamic regions, such as the Amundsen Sea Embayment, where dynamic strain thinning has accelerated in recent decades.

Staging of RF-accelerating Units in a MEMS-based Ion Accelerator

NASA Astrophysics Data System (ADS)

Persaud, A.; Seidl, P. A.; Ji, Q.; Feinberg, E.; Waldron, W. L.; Schenkel, T.; Ardanuc, S.; Vinayakumar, K. B.; Lal, A.

Multiple Electrostatic Quadrupole Array Linear Accelerators (MEQALACs) provide an opportunity to realize compact radio- frequency (RF) accelerator structures that can deliver very high beam currents. MEQALACs have been previously realized with acceleration gap distances and beam aperture sizes of the order of centimeters. Through advances in Micro-Electro-Mechanical Systems (MEMS) fabrication, MEQALACs can now be scaled down to the sub-millimeter regime and batch processed on wafer substrates. In this paper we show first results from using three RF stages in a compact MEMS-based ion accelerator. The results presented show proof-of-concept with accelerator structures formed from printed circuit boards using a 3 × 3 beamlet arrangement and noble gas ions at 10 keV. We present a simple model to describe the measured results. We also discuss some of the scaling behaviour of a compact MEQALAC. The MEMS-based approach enables a low-cost, highly versatile accelerator covering a wide range of currents (10 μA to 100 mA) and beam energies (100 keV to several MeV). Applications include ion-beam analysis, mass spectrometry, materials processing, and at very high beam powers, plasma heating.

Staging of RF-accelerating Units in a MEMS-based Ion Accelerator

DOE PAGES

Persaud, A.; Seidl, P. A.; Ji, Q.; ...

2017-10-26

Multiple Electrostatic Quadrupole Array Linear Accelerators (MEQALACs) provide an opportunity to realize compact radio- frequency (RF) accelerator structures that can deliver very high beam currents. MEQALACs have been previously realized with acceleration gap distances and beam aperture sizes of the order of centimeters. Through advances in Micro-Electro-Mechanical Systems (MEMS) fabrication, MEQALACs can now be scaled down to the sub-millimeter regime and batch processed on wafer substrates. In this paper we show first results from using three RF stages in a compact MEMS-based ion accelerator. The results presented show proof-of-concept with accelerator structures formed from printed circuit boards using a 3more » × 3 beamlet arrangement and noble gas ions at 10 keV. We present a simple model to describe the measured results. We also discuss some of the scaling behaviour of a compact MEQALAC. The MEMS-based approach enables a low-cost, highly versatile accelerator covering a wide range of currents (10 μA to 100 mA) and beam energies (100 keV to several MeV). Applications include ion-beam analysis, mass spectrometry, materials processing, and at very high beam powers, plasma heating.« less

Staging of RF-accelerating Units in a MEMS-based Ion Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Persaud, A.; Seidl, P. A.; Ji, Q.

Multiple Electrostatic Quadrupole Array Linear Accelerators (MEQALACs) provide an opportunity to realize compact radio- frequency (RF) accelerator structures that can deliver very high beam currents. MEQALACs have been previously realized with acceleration gap distances and beam aperture sizes of the order of centimeters. Through advances in Micro-Electro-Mechanical Systems (MEMS) fabrication, MEQALACs can now be scaled down to the sub-millimeter regime and batch processed on wafer substrates. In this paper we show first results from using three RF stages in a compact MEMS-based ion accelerator. The results presented show proof-of-concept with accelerator structures formed from printed circuit boards using a 3more » × 3 beamlet arrangement and noble gas ions at 10 keV. We present a simple model to describe the measured results. We also discuss some of the scaling behaviour of a compact MEQALAC. The MEMS-based approach enables a low-cost, highly versatile accelerator covering a wide range of currents (10 μA to 100 mA) and beam energies (100 keV to several MeV). Applications include ion-beam analysis, mass spectrometry, materials processing, and at very high beam powers, plasma heating.« less

Statistics of vacuum breakdown in the high-gradient and low-rate regime

NASA Astrophysics Data System (ADS)

Wuensch, Walter; Degiovanni, Alberto; Calatroni, Sergio; Korsbäck, Anders; Djurabekova, Flyura; Rajamäki, Robin; Giner-Navarro, Jorge

2017-01-01

In an increasing number of high-gradient linear accelerator applications, accelerating structures must operate with both high surface electric fields and low breakdown rates. Understanding the statistical properties of breakdown occurrence in such a regime is of practical importance for optimizing accelerator conditioning and operation algorithms, as well as of interest for efforts to understand the physical processes which underlie the breakdown phenomenon. Experimental data of breakdown has been collected in two distinct high-gradient experimental set-ups: A prototype linear accelerating structure operated in the Compact Linear Collider Xbox 12 GHz test stands, and a parallel plate electrode system operated with pulsed DC in the kV range. Collected data is presented, analyzed and compared. The two systems show similar, distinctive, two-part distributions of number of pulses between breakdowns, with each part corresponding to a specific, constant event rate. The correlation between distance and number of pulses between breakdown indicates that the two parts of the distribution, and their corresponding event rates, represent independent primary and induced follow-up breakdowns. The similarity of results from pulsed DC to 12 GHz rf indicates a similar vacuum arc triggering mechanism over the range of conditions covered by the experiments.

MID-INFRARED EVIDENCE FOR ACCELERATED EVOLUTION IN COMPACT GROUP GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, Lisa May; Johnson, Kelsey E.; Gallagher, Sarah C.

2010-11-15

Compact galaxy groups are at the extremes of the group environment, with high number densities and low velocity dispersions that likely affect member galaxy evolution. To explore the impact of this environment in detail, we examine the distribution in the mid-infrared (MIR) 3.6-8.0 {mu}m color space of 42 galaxies from 12 Hickson compact groups (HCGs) in comparison with several control samples, including the LVL+SINGS galaxies, interacting galaxies, and galaxies from the Coma Cluster. We find that the HCG galaxies are strongly bimodal, with statistically significant evidence for a gap in their distribution. In contrast, none of the other samples showmore » such a marked gap, and only galaxies in the Coma infall region have a distribution that is statistically consistent with the HCGs in this parameter space. To further investigate the cause of the HCG gap, we compare the galaxy morphologies of the HCG and LVL+SINGS galaxies, and also probe the specific star formation rate (SSFR) of the HCG galaxies. While galaxy morphology in HCG galaxies is strongly linked to position with MIR color space, the more fundamental property appears to be the SSFR, or star formation rate normalized by stellar mass. We conclude that the unusual MIR color distribution of HCG galaxies is a direct product of their environment, which is most similar to that of the Coma infall region. In both cases, galaxy densities are high, but gas has not been fully processed or stripped. We speculate that the compact group environment fosters accelerated evolution of galaxies from star-forming and neutral gas-rich to quiescent and neutral gas-poor, leaving few members in the MIR gap at any time.« less

Applications of the Strategic Defense Initiative's compact accelerators

NASA Technical Reports Server (NTRS)

Montanarelli, Nick; Lynch, Ted

1991-01-01

The Strategic Defense Initiative's (SDI) investment in particle accelerator technology for its directed energy weapons program has produced breakthroughs in the size and power of new accelerators. These accelerators, in turn, have produced spinoffs in several areas: the radio frequency quadrupole linear accelerator (RFQ linac) was recently incorporated into the design of a cancer therapy unit at the Loma Linda University Medical Center, an SDI-sponsored compact induction linear accelerator may replace Cobalt-60 radiation and hazardous ethylene-oxide as a method for sterilizing medical products, and other SDIO-funded accelerators may be used to produce the radioactive isotopes oxygen-15, nitrogen-13, carbon-11, and fluorine-18 for positron emission tomography (PET). Other applications of these accelerators include bomb detection, non-destructive inspection, decomposing toxic substances in contaminated ground water, and eliminating nuclear waste.

A compact electron cyclotron resonance proton source for the Paul Scherrer Institute's proton accelerator facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baumgarten, C.; Barchetti, A.; Einenkel, H.

2011-05-15

A compact electron cyclotron resonance proton source has been developed and installed recently at thePaul Scherrer Institute's high intensity proton accelerator. Operation at the ion source test stand and the accelerator demonstrates a high reliability and stability of the new source. When operated at a 10 - 12 mA net proton current the lifetime of the source exceeds 2000 h. The essential development steps towards the observed performance are described.

High Energy electron and proton acceleration by circularly polarized laser pulse from near critical density hydrogen gas target.

PubMed

Sharma, Ashutosh

2018-02-01

Relativistic electron rings hold the possibility of very high accelerating rates, and hopefully a relatively cheap and compact accelerator/collimator for ultrahigh energy proton source. In this work, we investigate the generation of helical shaped quasi-monoenergetic relativistic electron beam and high-energy proton beam from near critical density plasmas driven by petawatt-circularly polarized-short laser pulses. We numerically observe the efficient proton acceleration from magnetic vortex acceleration mechanism by using the three dimensional particle-in-cell simulations; proton beam with peak energy 350 MeV, charge ~10nC and conversion efficiency more than 6% (which implies 2.4 J proton beam out of the 40 J incident laser energy) is reported. We detailed the microphysics involved in the ion acceleration mechanism, which requires investigating the role of self-generated plasma electric and magnetic fields. The concept of efficient generation of quasi-monoenergetic electron and proton beam from near critical density gas targets may be verified experimentally at advanced high power - high repetition rate laser facilities e.g. ELI-ALPS. Such study should be an important step towards the development of high quality electron and proton beam.

Advanced Accelerators for Medical Applications

NASA Astrophysics Data System (ADS)

Uesaka, Mitsuru; Koyama, Kazuyoshi

We review advanced accelerators for medical applications with respect to the following key technologies: (i) higher RF electron linear accelerator (hereafter “linac”); (ii) optimization of alignment for the proton linac, cyclotron and synchrotron; (iii) superconducting magnet; (iv) laser technology. Advanced accelerators for medical applications are categorized into two groups. The first group consists of compact medical linacs with high RF, cyclotrons and synchrotrons downsized by optimization of alignment and superconducting magnets. The second group comprises laser-based acceleration systems aimed of medical applications in the future. Laser plasma electron/ion accelerating systems for cancer therapy and laser dielectric accelerating systems for radiation biology are mentioned. Since the second group has important potential for a compact system, the current status of the established energy and intensity and of the required stability are given.

Advanced Accelerators for Medical Applications

NASA Astrophysics Data System (ADS)

Uesaka, Mitsuru; Koyama, Kazuyoshi

We review advanced accelerators for medical applications with respect to the following key technologies: (i) higher RF electron linear accelerator (hereafter "linac"); (ii) optimization of alignment for the proton linac, cyclotron and synchrotron; (iii) superconducting magnet; (iv) laser technology. Advanced accelerators for medical applications are categorized into two groups. The first group consists of compact medical linacs with high RF, cyclotrons and synchrotrons downsized by optimization of alignment and superconducting magnets. The second group comprises laserbased acceleration systems aimed of medical applications in the future. Laser plasma electron/ion accelerating systems for cancer therapy and laser dielectric accelerating systems for radiation biology are mentioned. Since the second group has important potential for a compact system, the current status of the established energy and intensity and of the required stability are given.

Recent results of studies of acceleration of compact toroids

NASA Astrophysics Data System (ADS)

Hammer, J. H.; Hartmen, C. W.; Eddleman, J.

1984-03-01

The observed gross stability and self-contained structure of compact toroids (CT's) give rise to the possibility, unique among magnetically confined plasmas, of translating CT's from their point of origin over distances many times their own length. This feature has led us to consider magnetic acceleration of CT's to directed kinetic energies much greater than their stored magnetic and thermal energies. A CT accelerator falls in the very broad gap between traditional particle accelerators at one extreme, which are limited in the number of particles per bunch by electrostatic repulsive forces, and mass accelerators such as rail guns at the other extreme, which accelerate many particles but are forced by the stress limitations of solids to far smaller accelerations. A typical CT has about a Coulomb of particles, weighs 10 micrograms and can be accelerated by magnetic forces of several tons, leading to an acceleration on the order of 10(11) gravities.

Fiber Based Seed Laser for CO 2 Ultrafast Laser Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yuchuan

A compact and effective 10-micron femtosecond laser with pulse duration <500fs and repetition rate of >100Hz or smaller is desirable by DOE for seeding CO 2 ultrafast laser systems to improve the stability, reliability and efficiency in generating 10-micron laser from GW up to 100TW peak power, which is irreplaceable in driving an accelerator for particle beam generation due to the efficiency proportional to the square of the laser wavelength. Agiltron proposes a fiber based ultrafast 10-micron seed laser that can provide the required specifications and high performance. Its success will directly benefit DOE’s compact proton and ion sources. Themore » innovative technology can be used for ultrafast laser generation over the whole mid-IR range, and speed up the development of mid-IR laser applications. Agiltron, Inc. has successfully completed all tasks and demonstrated the feasibility of a fiber based 10-micron ultrafast laser in Phase I of the Program. We built a mode-locked fiber laser that generated < 400fs ultrafast laser pulses and successfully controlled the repetition rate to be the required 100Hz. Using this mode-locked laser, we demonstrated the feasibility of parametric femtosecond laser generation based on frequency down conversion. The experimental results agree with our simulation results. The investigation results of Phase I will be used to optimize the design of the laser system and build a fully functional prototype for delivery to the DOE in the Phase II program. The prototype development in Phase II program will be in the collaboration with Professor Chandrashekhar Joshi, the leader of UCLA Laser-Plasma group. Prof. Joshi discovered a new mechanism for generation of monoenergetic proton/ion beams: Shock Wave Acceleration in a near critical density plasma and demonstrated that high-energy proton beams using CO 2 laser driven collisionless shocks in a gas jet plasma, which opened an opportunity to develop a rather compact high-repetition rate ion source for medical and other applications which could be significantly cheaper than that based on RF acceleration. We propose an output energy >1 μJ, one order of magnitude higher than the DOE original requirement. The performance of the prototype will be tested at UCLA by directly seeding the CO 2 laser system driving an accelerator.« less

Relativistic klystron driven compact high gradient accelerator as an injector to an X-ray synchrotron radiation ring

DOEpatents

Yu, David U. L.

1990-01-01

A compact high gradient accelerator driven by a relativistic klystron is utilized to inject high energy electrons into an X-ray synchrotron radiation ring. The high gradients provided by the relativistic klystron enables accelerator structure to be much shorter (typically 3 meters) than conventional injectors. This in turn enables manufacturers which utilize high energy, high intensity X-rays to produce various devices, such as computer chips, to do so on a cost effective basis.

Compact particle accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elizondo-Decanini, Juan M.

2017-08-29

A compact particle accelerator having an input portion configured to receive power to produce particles for acceleration, where the input portion includes a switch, is provided. In a general embodiment, a vacuum tube receives particles produced from the input portion at a first end, and a plurality of wafer stacks are positioned serially along the vacuum tube. Each of the plurality of wafer stacks include a dielectric and metal-oxide pair, wherein each of the plurality of wafer stacks further accelerate the particles in the vacuum tube. A beam shaper coupled to a second end of the vacuum tube shapes themore » particles accelerated by the plurality of wafer stacks into a beam and an output portion outputs the beam.« less

Roller Compacted Concrete over Soil Cement under Accelerated Loading : Research Project Capsule

DOT National Transportation Integrated Search

2012-09-01

Roller compacted concrete (RCC) is a stiff , zero-slump concrete mixture placed with modifi ed : asphalt paving equipment and compacted by vibratory rollers. Properly designed RCC mixes : can achieve outstanding compressive strengths similar to those...

Assessment of Homomorphic Analysis for Human Activity Recognition from Acceleration Signals.

PubMed

Vanrell, Sebastian Rodrigo; Milone, Diego Humberto; Rufiner, Hugo Leonardo

2017-07-03

Unobtrusive activity monitoring can provide valuable information for medical and sports applications. In recent years, human activity recognition has moved to wearable sensors to deal with unconstrained scenarios. Accelerometers are the preferred sensors due to their simplicity and availability. Previous studies have examined several \\azul{classic} techniques for extracting features from acceleration signals, including time-domain, time-frequency, frequency-domain, and other heuristic features. Spectral and temporal features are the preferred ones and they are generally computed from acceleration components, leaving the acceleration magnitude potential unexplored. In this study, based on homomorphic analysis, a new type of feature extraction stage is proposed in order to exploit discriminative activity information present in acceleration signals. Homomorphic analysis can isolate the information about whole body dynamics and translate it into a compact representation, called cepstral coefficients. Experiments have explored several configurations of the proposed features, including size of representation, signals to be used, and fusion with other features. Cepstral features computed from acceleration magnitude obtained one of the highest recognition rates. In addition, a beneficial contribution was found when time-domain and moving pace information was included in the feature vector. Overall, the proposed system achieved a recognition rate of 91.21% on the publicly available SCUT-NAA dataset. To the best of our knowledge, this is the highest recognition rate on this dataset.

Effects of livestock species and stocking density on accretion rates in grazed salt marshes

NASA Astrophysics Data System (ADS)

Nolte, Stefanie; Esselink, Peter; Bakker, Jan P.; Smit, Christian

2015-01-01

Coastal ecosystems, such as salt marshes, are threatened by accelerated sea-level rise (SLR). Salt marshes deliver valuable ecosystem services such as coastal protection and the provision of habitat for a unique flora and fauna. Whether salt marshes in the Wadden Sea area are able to survive accelerated SLR depends on sufficient deposition of sediments which add to vertical marsh accretion. Accretion rate is influenced by a number of factors, and livestock grazing was recently included. Livestock grazing is assumed to reduce accretion rates in two ways: (a) directly by increasing soil compaction through trampling, and (b) indirectly by affecting the vegetation structure, which may lower the sediment deposition. For four years, we studied the impact of two livestock species (horse and cattle) at two stocking densities (0.5 and 1.0 animal ha-1) on accretion in a large-scale grazing experiment using sedimentation plates. We found lower cumulative accretion rates in high stocking densities, probably because more animals cause more compaction and create a lower canopy. Furthermore, a trend towards lower accretion rates in horse-compared to cattle-grazed treatments was found, most likely because (1) horses are more active and thus cause more compaction, and (2) herbage intake by horses is higher than by cattle, which causes a higher biomass removal and shorter canopy. During summer periods, negative accretion rates were found. When the grazing and non-grazing seasons were separated, the impact of grazing differed among years. In summer, we only found an effect of different treatments if soil moisture (precipitation) was relatively low. In winter, a sufficiently high inundation frequency was necessary to create differences between grazing treatments. We conclude that stocking densities, and to a certain extent also livestock species, affect accretion rates in salt marshes. Both stocking densities and livestock species should thus be taken into account in management decisions of salt marshes. In our study accretion rates were higher than the current SLR. Further research is needed to include grazing effects into sedimentation models, given the importance of grazing management in the Wadden Sea area.

Radiobiological effectiveness of laser accelerated electrons in comparison to electron beams from a conventional linear accelerator.

PubMed

Laschinsky, Lydia; Baumann, Michael; Beyreuther, Elke; Enghardt, Wolfgang; Kaluza, Malte; Karsch, Leonhard; Lessmann, Elisabeth; Naumburger, Doreen; Nicolai, Maria; Richter, Christian; Sauerbrey, Roland; Schlenvoigt, Hans-Peter; Pawelke, Jörg

2012-01-01

The notable progress in laser particle acceleration technology promises potential medical application in cancer therapy through compact and cost effective laser devices that are suitable for already existing clinics. Previously, consequences on the radiobiological response by laser driven particle beams characterised by an ultra high peak dose rate have to be investigated. Therefore, tumour and non-malignant cells were irradiated with pulsed laser accelerated electrons at the JETI facility for the comparison with continuous electrons of a conventional therapy LINAC. Dose response curves were measured for the biological endpoints clonogenic survival and residual DNA double strand breaks. The overall results show no significant differences in radiobiological response for in vitro cell experiments between laser accelerated pulsed and clinical used electron beams. These first systematic in vitro cell response studies with precise dosimetry to laser driven electron beams represent a first step toward the long term aim of the application of laser accelerated particles in radiotherapy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokollik, Thomas; Shiraishi, Satomi; Osterhoff, Jens

We present experimental results on a tape-drive based plasma mirror which could be used for a compact coupling of a laser beam into a staged laser driven electron accelerator. This novel kind of plasma mirror is suitable for high repetition rates and for high number of laser shots. In order to design a compact, staged laser plasma based accelerator or collider [1], the coupling of the laser beam into the different stages represents one of the key issues. To limit the spatial foot print and thus to realize a high overall acceleration gradient, a concept has to be found whichmore » realizes this in-coupling within a few centimeters (cf. Fig 1). The fluence of the laser pulse several centimeters away from the acceleration stage (focus) exceeds the damage threshold of any available mirror coating. Therefore, in reference [2] a plasma mirror was suggested for this purpose. We present experiments on a tape-drive based plasma mirror which could be used to reflect the focused laser beam into the acceleration stage. Plasma mirrors composed of antireflection coated glass substrates are usually used to improve the temporal laser contrast of laser pulses by several orders of magnitudes [3,4]. This is particularly important for laser interaction with solid matter, such as ion acceleration [5,6] and high harmonic generation on surfaces [7]. Therefore, the laser pulse is weekly focused onto a substrate. The main pulse generates a plasma and is reflected at the critical surface, whereas the low intensity pre-pulse (mainly the Amplified Spontaneous Emission pedestal) will be transmitted through the substrate before the mirror has been triggered. Several publications [3,4] demonstrate a conservation of the spatial beam quality and a reflectivity of about 70 %. The drawback of this technique is the limited repetition rate since for every shot a fresh surface has to be provided. In the past years several novel approaches for high repetition rate plasma mirrors have been developed [2, 8]. Nevertheless, for the staged accelerator scheme a second important requirement has to be considered. Since the electron beam has to propagate through the mirror, the thickness of the substrate has to be as thin as possible to reduce the distortion of the electron beam. A tape of only several micrometer thickness can overcome these disadvantages. It can be used with a sufficient repetition rate while it allows the electron beam to propagate through with a minimum of scattering.« less

Applications of compact accelerator-driven neutron sources: An updated assessment from the perspective of materials research in Italy

DOE PAGES

Andreani, C.; Anderson, I. S.; Carpenter, J. M.; ...

2014-12-24

In 2005 the International Atomic Energy Agency (IAEA) in Vienna published a report [1] on ‘Development Opportunities of Small and Medium Scale Accelerator Driven Neutron Sources’ which summarized the prospect of smaller sources in supporting the large spallation neutron sources for materials characterization and instrumentation, a theme advocated by Bauer, Clausen, Mank, and Mulhauser in previous publications [2-4]. In 2010 the Union for Compact Accelerator-driven Neutron Sources (UCANS) was established [5], galvanizing cross-disciplinary collaborations on new source and neutronics development and expanded applications based on both slow-neutron scattering and other neutron-matter interactions of neutron energies ranging from 10⁻⁶ to 10²more » MeV [6]. Here, we first cover the recent development of ongoing and prospective projects of compact accelerator-driven neutron sources (CANS) but concentrate on prospective accelerators currently proposed in Italy. Two active R&D topics, irradiation effects on electronics and cultural heritage studies, are chosen to illustrate the impact of state-of-the-art CANS on these programs with respect to the characteristics and complementarity of the accelerator and neutronics systems as well as instrumentation development.« less

Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz

DOE PAGES

Graves, W.  S.; Bessuille, J.; Brown, P.; ...

2014-12-01

A design for a compact x-ray light source (CXLS) with flux and brilliance orders of magnitude beyond existing laboratory scale sources is presented. The source is based on inverse Compton scattering of a high brightness electron bunch on a picosecond laser pulse. The accelerator is a novel high-efficiency standingwave linac and rf photoinjector powered by a single ultrastable rf transmitter at X-band rf frequency. The high efficiency permits operation at repetition rates up to 1 kHz, which is further boosted to 100 kHz by operating with trains of 100 bunches of 100 pC charge, each separated by 5 ns. Themore » entire accelerator is approximately 1 meter long and produces hard x rays tunable over a wide range of photon energies. The colliding laser is a Yb:YAG solid-state amplifier producing 1030 nm, 100 mJ pulses at the same 1 kHz repetition rate as the accelerator. The laser pulse is frequency-doubled and stored for many passes in a ringdown cavity to match the linac pulse structure. At a photon energy of 12.4 keV, the predicted x-ray flux is 5 × 10¹¹ photons/second in a 5% bandwidth and the brilliance is 2 × 10¹² photons/(sec mm² mrad² 0.1%) in pulses with rms pulse length of 490 fs. The nominal electron beam parameters are 18 MeV kinetic energy, 10 microamp average current, 0.5 microsecond macropulse length, resulting in average electron beam power of 180 W. Optimization of the x-ray output is presented along with design of the accelerator, laser, and x-ray optic components that are specific to the particular characteristics of the Compton scattered x-ray pulses.« less

Spectrometers for compact neutron sources

NASA Astrophysics Data System (ADS)

Voigt, J.; Böhm, S.; Dabruck, J. P.; Rücker, U.; Gutberlet, T.; Brückel, T.

2018-03-01

We discuss the potential for neutron spectrometers at novel accelerator driven compact neutron sources. Such a High Brilliance Source (HBS) relies on low energy nuclear reactions, which enable cryogenic moderators in very close proximity to the target and neutron optics at comparably short distances from the moderator compared to existing sources. While the first effect aims at increasing the phase space density of a moderator, the second allows the extraction of a large phase space volume, which is typically requested for spectrometer applications. We find that competitive spectrometers can be realized if (a) the neutron production rate can be synchronized with the experiment repetition rate and (b) the emission characteristics of the moderator can be matched to the phase space requirements of the experiment. MCNP simulations for protons or deuterons on a Beryllium target with a suitable target/moderator design yield a source brightness, from which we calculate the sample fluxes by phase space considerations for different types of spectrometers. These match closely the figures of todays spectrometers at medium flux sources. Hence we conclude that compact neutron sources might be a viable option for next generation neutron sources.

A compact 300 kV solid-state high-voltage nanosecond generator for dielectric wall accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Yi; Wang, Wei; Liu, Yi

2015-05-15

Compact solid-state system is the main development trend in pulsed power technologies. A compact solid-state high-voltage nanosecond pulse generator with output voltage of 300 kV amplitude, 10 ns duration (FWHM), and 3 ns rise-time was designed for a dielectric wall accelerator. The generator is stacked by 15 planar-plate Blumlein pulse forming lines (PFL). Each Blumlein PFL consists of two solid-state planar transmission lines, a GaAs photoconductive semiconductor switch, and a laser diode trigger. The key components of the generator and the experimental results are reported in this paper.

Properties of a new type Al/Pb-0.3%Ag alloy composite anode for zinc electrowinning

NASA Astrophysics Data System (ADS)

Yang, Hai-tao; Liu, Huan-rong; Zhang, Yong-chun; Chen, Bu-ming; Guo, Zhong-cheng; Xu, Rui-dong

2013-10-01

An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 A·m-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 g·m-2·h-1, respectively, in accelerated corrosion test for 8 h at 2000 A·m-2. The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.

Topics in gamma ray astronomy

NASA Technical Reports Server (NTRS)

Ramaty, R.; Lingenfelter, R. E.

1986-01-01

Observations of gamma rays from solar flares, gamma ray bursts, the Galactic center, galactic nucleosynthesis, SS433, and Cygnus X-3, and their effects on astrophysical problems are discussed. It is observed that gamma ray spectra from solar flares are applicable to the study of particle acceleration and confinement and the determination of chemical abundances in the solar atmosphere. The gamma ray lines from the compact galactic object SS433 are utilized to examine the acceleration of jets, and analysis of the gamma ray lines of Cygnus X-3 reveal that particles can be accelerated in compact sources to ultrahigh energies.

Towards ion beam therapy based on laser plasma accelerators.

PubMed

Karsch, Leonhard; Beyreuther, Elke; Enghardt, Wolfgang; Gotz, Malte; Masood, Umar; Schramm, Ulrich; Zeil, Karl; Pawelke, Jörg

2017-11-01

Only few ten radiotherapy facilities worldwide provide ion beams, in spite of their physical advantage of better achievable tumor conformity of the dose compared to conventional photon beams. Since, mainly the large size and high costs hinder their wider spread, great efforts are ongoing to develop more compact ion therapy facilities. One promising approach for smaller facilities is the acceleration of ions on micrometre scale by high intensity lasers. Laser accelerators deliver pulsed beams with a low pulse repetition rate, but a high number of ions per pulse, broad energy spectra and high divergences. A clinical use of a laser based ion beam facility requires not only a laser accelerator providing beams of therapeutic quality, but also new approaches for beam transport, dosimetric control and tumor conformal dose delivery procedure together with the knowledge of the radiobiological effectiveness of laser-driven beams. Over the last decade research was mainly focused on protons and progress was achieved in all important challenges. Although currently the maximum proton energy is not yet high enough for patient irradiation, suggestions and solutions have been reported for compact beam transport and dose delivery procedures, respectively, as well as for precise dosimetric control. Radiobiological in vitro and in vivo studies show no indications of an altered biological effectiveness of laser-driven beams. Laser based facilities will hardly improve the availability of ion beams for patient treatment in the next decade. Nevertheless, there are possibilities for a need of laser based therapy facilities in future.

Low Emittance, High Brilliance Relativistic Electron Beams from a Laser-Plasma Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brunetti, E.; Shanks, R. P.; Manahan, G. G.

2010-11-19

Progress in laser wakefield accelerators indicates their suitability as a driver of compact free-electron lasers (FELs). High brightness is defined by the normalized transverse emittance, which should be less than 1{pi} mm mrad for an x-ray FEL. We report high-resolution measurements of the emittance of 125 MeV, monoenergetic beams from a wakefield accelerator. An emittance as low as 1.1{+-}0.1{pi} mm mrad is measured using a pepper-pot mask. This sets an upper limit on the emittance, which is comparable with conventional linear accelerators. A peak transverse brightness of 5x10{sup 15} A m{sup -1} rad{sup -1} makes it suitable for compact XUVmore » FELs.« less

Optimization of radiation shielding material aiming at compactness, lightweight, and low activation for a vehicle-mounted accelerator-driven D-T neutron source.

PubMed

Cai, Yao; Hu, Huasi; Lu, Shuangying; Jia, Qinggang

2018-05-01

To minimize the size and weight of a vehicle-mounted accelerator-driven D-T neutron source and protect workers from unnecessary irradiation after the equipment shutdown, a method to optimize radiation shielding material aiming at compactness, lightweight, and low activation for the fast neutrons was developed. The method employed genetic algorithm, combining MCNP and ORIGEN codes. A series of composite shielding material samples were obtained by the method step by step. The volume and weight needed to build a shield (assumed as a coaxial tapered cylinder) were adopted to compare the performance of the materials visually and conveniently. The results showed that the optimized materials have excellent performance in comparison with the conventional materials. The "MCNP6-ACT" method and the "rigorous two steps" (R2S) method were used to verify the activation grade of the shield irradiated by D-T neutrons. The types of radionuclide, the energy spectrum of corresponding decay gamma source, and the variation in decay gamma dose rate were also computed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Tailored electron bunches with smooth current profiles for enhanced transformer ratios in beam-driven acceleration

DOE PAGES

Lemery, F.; Piot, P.

2015-08-03

Collinear high-gradient O(GV/m) beam-driven wakefield methods for charged-particle acceleration could be critical to the realization of compact, cost-efficient, accelerators, e.g., in support of TeV-scale lepton colliders or multiple-user free-electron laser facilities. To make these options viable, the high accelerating fields need to be complemented with large transformer ratios >2, a parameter characterizing the efficiency of the energy transfer between a wakefield-exciting “drive” bunch to an accelerated “witness” bunch. While several potential current distributions have been discussed, their practical realization appears challenging due to their often discontinuous nature. In this paper we propose several alternative continuously differentiable (smooth) current profiles whichmore » support enhanced transformer ratios. We especially demonstrate that one of the devised shapes can be implemented in a photo-emission electron source by properly shaping the photocathode-laser pulse. We finally discuss a possible superconducting linear-accelerator concept that could produce shaped drive bunches at high-repetition rates to drive a dielectric-wakefield accelerator with accelerating fields on the order of ~60 MV/m and a transformer ratio ~5 consistent with a recently proposed multiuser free-electron laser facility.« less

Tailored electron bunches with smooth current profiles for enhanced transformer ratios in beam-driven acceleration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemery, F.; Piot, P.

Collinear high-gradient O(GV/m) beam-driven wakefield methods for charged-particle acceleration could be critical to the realization of compact, cost-efficient, accelerators, e.g., in support of TeV-scale lepton colliders or multiple-user free-electron laser facilities. To make these options viable, the high accelerating fields need to be complemented with large transformer ratios >2, a parameter characterizing the efficiency of the energy transfer between a wakefield-exciting “drive” bunch to an accelerated “witness” bunch. While several potential current distributions have been discussed, their practical realization appears challenging due to their often discontinuous nature. In this paper we propose several alternative continuously differentiable (smooth) current profiles whichmore » support enhanced transformer ratios. We especially demonstrate that one of the devised shapes can be implemented in a photo-emission electron source by properly shaping the photocathode-laser pulse. We finally discuss a possible superconducting linear-accelerator concept that could produce shaped drive bunches at high-repetition rates to drive a dielectric-wakefield accelerator with accelerating fields on the order of ~60 MV/m and a transformer ratio ~5 consistent with a recently proposed multiuser free-electron laser facility.« less

Development of a compact, rf-driven, pulsed ion source for neutron generation

NASA Astrophysics Data System (ADS)

Perkins, L. T.; Celata, C.; Lee, Y.; Leung, K. N.; Picard, D. S.; Vilaithong, R.; Williams, M. D.; Wutte, D.

1997-02-01

Lawrence Berkeley National Laboratory is currently developing a compact, sealed-accelerator-tube neutron generator capable of producing a neutron flux in the range of 109 to 1010 D-T neutrons per second. The ion source, a miniaturized variation of earlier radio-frequency (rf)-driven multicusp ion sources, is designed to fit within a ˜5 cm diameter borehole. Typical operating parameters include repetition rates up to 100 pps, with pulse widths between 10 and 80 μs (limited only by the available rf power supply) and source pressures as low as ˜5 mTorr. In this configuration, peak extractable hydrogen current densities exceeding 1180 mA/cm2 with H1+ yields over 94% having been achieved.

The Collaborative Compact: Operating Principles Lay the Groundwork for Successful Group Work

ERIC Educational Resources Information Center

Garmston, Robert J.; Zimmerman, Diane P.

2013-01-01

Leaders often have common complaints about managing meetings and feel thwarted by attempts to collaborate. Teachers feel that time spent on collaboration is often wasted because of poor meeting management. Leaders can accelerate collaboration by creating collaborative compacts. A collaborative compact is a set of accords about how a group will…

Compact x-ray source and panel

DOEpatents

Sampayon, Stephen E [Manteca, CA

2008-02-12

A compact, self-contained x-ray source, and a compact x-ray source panel having a plurality of such x-ray sources arranged in a preferably broad-area pixelized array. Each x-ray source includes an electron source for producing an electron beam, an x-ray conversion target, and a multilayer insulator separating the electron source and the x-ray conversion target from each other. The multi-layer insulator preferably has a cylindrical configuration with a plurality of alternating insulator and conductor layers surrounding an acceleration channel leading from the electron source to the x-ray conversion target. A power source is connected to each x-ray source of the array to produce an accelerating gradient between the electron source and x-ray conversion target in any one or more of the x-ray sources independent of other x-ray sources in the array, so as to accelerate an electron beam towards the x-ray conversion target. The multilayer insulator enables relatively short separation distances between the electron source and the x-ray conversion target so that a thin panel is possible for compactness. This is due to the ability of the plurality of alternating insulator and conductor layers of the multilayer insulators to resist surface flashover when sufficiently high acceleration energies necessary for x-ray generation are supplied by the power source to the x-ray sources.

Recirculating Electron Accelerators with Noncircular Electron Orbits as Radiation Sources for Applications (a Review)

NASA Astrophysics Data System (ADS)

Dubinov, Alexander E.; Ochkina, Elena I.

2018-05-01

State-of-the-art compact recirculating electron accelerators operating at intermediate energies (tens of MeV) are reviewed. The acceleration schemes implemented in the rhodotron, ridgetron, fantron, and cylindertron machines are discussed. Major accelerator components such as the electron guns, accelerating cavities, and bending magnets are described. The parameters of currently operating recirculating accelerators are tabulated, and applications of these accelerators in different processes of irradiation are exemplified.

Neutron yield when fast deuterium ions collide with strongly charged tritium-saturated dust particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akishev, Yu. S., E-mail: akishev@triniti.ru; Karal’nik, V. B.; Petryakov, A. V.

2017-02-15

The ultrahigh charging of dust particles in a plasma under exposure to an electron beam with an energy up to 25 keV and the formation of a flux of fast ions coming from the plasma and accelerating in the strong field of negatively charged particles are considered. Particles containing tritium or deuterium atoms are considered as targets. The calculated rates of thermonuclear fusion reactions in strongly charged particles under exposure to accelerated plasma ions are presented. The neutron generation rate in reactions with accelerated deuterium and tritium ions has been calculated for these targets. The neutron yield has been calculatedmore » when varying the plasma-forming gas pressure, the plasma density, the target diameter, and the beam electron current density. Deuterium and tritium-containing particles are shown to be the most promising plasmaforming gas–target material pair for the creation of a compact gas-discharge neutron source based on the ultrahigh charging of dust particles by beam electrons with an energy up to 25 keV.« less

Intelligent Compaction and Infrared Scanning Field Projects with Consulting Support

DOT National Transportation Integrated Search

2018-02-01

The Missouri Department of Transportation (MoDOT) was awarded a grant from the FHWA Accelerated Innovation Deployment (AID) program, in 2016. MoDOT provided the required matching funds to support this Intelligent Compaction (IC) and Infrared Scanning...

Accelerated Innovation Deployment (AID) Demonstration Project : Intelligent Compaction and Infrared Scanning Projects

DOT National Transportation Integrated Search

2018-02-01

This report documents the Missouri Department of Transportation (MoDOT) demonstration grant award for field demonstration projects using intelligent compaction (IC) and infrared scanning (IR) (also called paver-mounted thermal profiles PMTP in the AA...

Laser Acceleration of Ions for Radiation Therapy

NASA Astrophysics Data System (ADS)

Tajima, Toshiki; Habs, Dietrich; Yan, Xueqing

Ion beam therapy for cancer has proven to be a successful clinical approach, affording as good a cure as surgery and a higher quality of life. However, the ion beam therapy installation is large and expensive, limiting its availability for public benefit. One of the hurdles is to make the accelerator more compact on the basis of conventional technology. Laser acceleration of ions represents a rapidly developing young field. The prevailing acceleration mechanism (known as target normal sheath acceleration, TNSA), however, shows severe limitations in some key elements. We now witness that a new regime of coherent acceleration of ions by laser (CAIL) has been studied to overcome many of these problems and accelerate protons and carbon ions to high energies with higher efficiencies. Emerging scaling laws indicate possible realization of an ion therapy facility with compact, cost-efficient lasers. Furthermore, dense particle bunches may allow the use of much higher collective fields, reducing the size of beam transport and dump systems. Though ultimate realization of a laser-driven medical facility may take many years, the field is developing fast with many conceptual innovations and technical progress.

A new high quality X-ray source for Cultural Heritage

NASA Astrophysics Data System (ADS)

Walter, Philippe; Variola, Alessandro; Zomer, Fabian; Jaquet, Marie; Loulergue, Alexandre

2009-09-01

Compton based photon sources have generated much interest since the rapid advance in laser and accelerator technologies has allowed envisaging their utilisation for ultra-compact radiation sources. These should provide X-ray short pulses with a relatively high average flux. Moreover, the univocal dependence between the scattered photon energy and its angle gives the possibility of obtaining a quasi-monochromatic beam with a simple diaphragm system. For the most ambitious projects the expected performance takes into account a rate of 10-10 photons/s, with an angular divergence of few mrad, an X-ray energy cut-off of few tens of keV and a bandwidth ΔE/E˜1-10%. Even if the integrated rate cannot compete with synchrotron radiation sources, the cost and the compactness of these Compton based machines make them attractive for a wide spectrum of applications. We explore here the interest of these systems for Cultural Heritage preservation. To cite this article: P. Walter et al., C. R. Physique 10 (2009).

Feasibility study of a cyclotron complex for hadron therapy

NASA Astrophysics Data System (ADS)

Smirnov, V.; Vorozhtsov, S.

2018-04-01

An accelerator complex for hadron therapy based on a chain of cyclotrons is under development at JINR (Dubna, Russia), and the corresponding conceptual design is under preparation. The complex mainly consists of two superconducting cyclotrons. The first accelerator is a compact cyclotron used as an injector to the main accelerator, which is a six-fold separated sector machine. The facility is intended for generation of protons and carbon beams. The H2+ and 12C6+ ions from the corresponding ECR ion sources are accelerated in the injector-cyclotron up to the output energy of 70 MeV/u. Then, the H2+ ions are extracted from the injector by a stripping foil, and the resulting proton beam with the energy of 70 MeV is used for medical purposes. After acceleration in the main cyclotron, the carbon beam can be either used directly for therapy or introduced to the main cyclotron for obtaining the final energy of 400 MeV/u. The basic requirements to the project are the following: compliance to medical requirements, compact size, feasible design, and high reliability of all systems of the complex. The advantages of the dual cyclotron design can help reaching these goals. The initial calculations show that this design is technically feasible with acceptable beam dynamics. The accelerator complex with a relatively compact size can be a good solution for medical applications. The basic parameters of the facility and detailed investigation of the magnetic system and beam dynamics are described.

Compact Torus Acceleration and Injection Experiment

NASA Astrophysics Data System (ADS)

Fukumoto, Naoyuki; Fujiwara, Makoto; Nagata, Masayoshi; Uyama, Tadao; Oda, Yasushi; Azuma, Kingo

1996-11-01

The spheromak-type compact torus (CT) acceleration and injection experiment has been carried out using the Himeji Institute of Technology Compact Torus Injector (HIT-CTI). We explore the possibility of refueling, density control, current drive, and edge electric field control of tokamak plasma by means of CT injection. In last September the new HIT-CTI was built up to achieve higher speed (Vct>200 km/s) and higher density CT plasmoid by improving the capacitor bank system and eliminating the impurity and neutral particles. At initial formation discharge tests the gun for formation and compression successfully produced a CT plasmoid and injected it between electrodes for acceleration. (Initial velocity Vct.ini. 32 km/s, Bct 1 kG, Rct=5.5 cm). The formation capacitor bank will be upgraded to two 36 mF capacitors operating at 20 kV (14.4 kJ). The acceleration capacitor bank will be also upgraded to two 36 mF capacitors operating at 20 kV (14.4 kJ). The HIT-CTI will be optimized to obtain suitable CT parameters after acceleration (Bct>5 kG, Lct 20 cm, Vct>200 km/s). In the respect of CT parameter measurement magnetic probes and a He-Ne laser interferometer will be employed in order to measure the CT magnetic field, velocity, density, and length. CT acceleration experimental data on the HIT-CTI and the plan of CT injection experiment on the JFT-2M tokamak (JAERI) will be presented at the meeting.

A Variable Energy CW Compact Accelerator for Ion Cancer Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnstone, Carol J.; Taylor, J.; Edgecock, R.

2016-03-10

Cancer is the second-largest cause of death in the U.S. and approximately two-thirds of all cancer patients will receive radiation therapy with the majority of the radiation treatments performed using x-rays produced by electron linacs. Charged particle beam radiation therapy, both protons and light ions, however, offers advantageous physical-dose distributions over conventional photon radiotherapy, and, for particles heavier than protons, a significant biological advantage. Despite recognition of potential advantages, there is almost no research activity in this field in the U.S. due to the lack of clinical accelerator facilities offering light ion therapy in the States. In January, 2013, amore » joint DOE/NCI workshop was convened to address the challenges of light ion therapy [1], inviting more than 60 experts from diverse fields related to radiation therapy. This paper reports on the conclusions of the workshop, then translates the clinical requirements into accelerat or and beam-delivery technical specifications. A comparison of available or feasible accelerator technologies is compared, including a new concept for a compact, CW, and variable energy light ion accelerator currently under development. This new light ion accelerator is based on advances in nonscaling Fixed-Field Alternating gradient (FFAG) accelerator design. The new design concepts combine isochronous orbits with long (up to 4m) straight sections in a compact racetrack format allowing inner circulating orbits to be energy selected for low-loss, CW extraction, effectively eliminating the high-loss energy degrader in conventional CW cyclotron designs.« less

Fluid-injection and the mechanics of frictional stability of shale-bearing faults

NASA Astrophysics Data System (ADS)

Scuderi, Marco Maria; Collettini, Cristiano; Marone, Chris

2017-04-01

Fluid overpressure is one of the primary mechanisms for triggering tectonic fault slip and human-induced seismicity. This mechanism is appealing because fluids lubricate the fault and reduce the effective normal stress that holds the fault in place. However, current models of earthquake nucleation, based on rate- and state- friction, imply that stable sliding is favored by the increase of pore fluid pressure. Despite this apparent dilemma, there are a few studies on the role of fluid pressure in frictional stability under controlled, laboratory conditions. Here, we describe laboratory experiments on shale fault gouge, conducted in the double direct shear configuration in a true-triaxial machine. To characterize frictional stability and hydrological properties we performed three types of experiments: 1) stable sliding shear experiment to determine the material failure envelope resulting in fault strength of µ=0.28 and fault zone permeability (k 10-19m2); 2) velocity step experiments to determine the rate- and state- frictional properties, characterized by a velocity strengthening behavior with a negative rate parameter b, indicative of stable aseismic creep; 3) creep experiment to study fault slip evolution with increasing pore-fluid pressure. In these creep experiments fault slip history can be divided in three main stages: a) for low fluid pressure the fault is locked and undergoes compaction; b) with increasing fluid pressurization, we observe aseismic creep (i.e. v=0.0001 µm/s) associated with fault dilation, with maintained low permeability; c) As fluid pressure is further increased and we approach the failure criteria fault begins to accelerate, the dilation rate increases causing an increase in permeability. Following the first acceleration we document complex fault slip behavior characterized by periodic accelerations and decelerations with slip velocity that remains slow (i.e. v 200 µm/s), never approaching dynamic slip rates. Surprisingly, this complex slip behavior is associated with fault zone compaction and permeability increase as opposite to the dilation hardening mechanism that is usually invoked to quench the instability. We relate this complex fault slip behaviour to the interplay between fault weakening induced by fluid pressurization and the strong rate-strengthening behaviour of shales. Our data show that fault rheology and fault stability is controlled by the coupling between fluid pressure and rate- and state- friction parameters suggesting that their comprehensive characterization is fundamental for assessing the role of fluid pressure in natural and human induced earthquakes.

An investigation of the mechanism of release of the amphoteric drug amoxycillin from poly(D,L-lactide-co-glycolide) matrices.

PubMed

Mollo, A Rosario; Corrigan, Owen I

2002-01-01

Amoxycillin-poly (D,L-lactide-co-glycolide) (PLGA) compacts were prepared by direct compression of both powder mixtures or films in a pre-heated press. Release profiles generally showed two phases separated by an induction period. Thus, both diffusion and polymer degradation mechanisms were involved in drug release, the relative importance of each depending on processing type and drug loading. Drug release parameters for each phase were determined. The fraction of total drug released, in the initial release phase, increased with drug loading and was much larger for compressed physical mixtures than for compressed composites prepared from co-evaporate films. Comparison of the polymer mass loss profiles of drug-loaded and drug-free discs indicated that the presence of the amphoteric drug amoxycillin had little impact on the polymer degradation rate, in contrast to the marked acceleration previously reported for basic drugs. Significant drug degradation occurred and was associated with release at later times. Release data was fitted to an equation accounting for degradation of the drug on release and suggested accelerated amoxycillin degradation during the polymer degradation controlled release phase, consistent with changes in pH in the microenvironment of the eroding compact.

Active Plasma Lensing for Relativistic Laser-Plasma-Accelerated Electron Beams

DOE PAGES

van Tilborg, J.; Steinke, S.; Geddes, C. G. R.; ...

2015-10-28

The compact, tunable, radially symmetric focusing of electrons is critical to laser-plasma accelerator (LPA) applications. Experiments are presented demonstrating the use of a discharge-capillary active plasma lens to focus 100-MeV-level LPA beams. The lens can provide tunable field gradients in excess of 3000 T/m, enabling cm-scale focal lengths for GeV-level beam energies and allowing LPA-based electron beams and light sources to maintain their compact footprint. For a range of lens strengths, excellent agreement with simulation was obtained.

Model for Generation of Neutrons in a Compact Diode with Laser-Plasma Anode and Suppression of Electron Conduction Using a Permanent Cylindrical Magnet

NASA Astrophysics Data System (ADS)

Shikanov, A. E.; Vovchenko, E. D.; Kozlovskii, K. I.; Rashchikov, V. I.; Shatokhin, V. L.

2018-04-01

A model for acceleration of deuterons and generation of neutrons in a compact laser-plasma diode with electron isolation using magnetic field generated by a hollow cylindrical permanent magnet is presented. Experimental and computer-simulated neutron yields are compared for the diode structure under study. An accelerating neutron tube with a relatively high neutron generation efficiency can be constructed using suppression of electron conduction with the aid of a magnet placed in the vacuum volume.

Beam-based measurements of long-range transverse wakefields in the Compact Linear Collider main-linac accelerating structure

DOE PAGES

Zha, Hao; Latina, Andrea; Grudiev, Alexej; ...

2016-01-20

The baseline design of CLIC (Compact Linear Collider) uses X-band accelerating structures for its main linacs. In order to maintain beam stability in multibunch operation, long-range transverse wakefields must be suppressed by 2 orders of magnitude between successive bunches, which are separated in time by 0.5 ns. Such strong wakefield suppression is achieved by equipping every accelerating structure cell with four damping waveguides terminated with individual rf loads. A beam-based experiment to directly measure the effectiveness of this long-range transverse wakefield and benchmark simulations was made in the FACET test facility at SLAC using a prototype CLIC accelerating structure. Furthermore,more » the experiment showed good agreement with the simulations and a strong suppression of the wakefields with an unprecedented minimum resolution of 0.1 V/(pC mm m).« less

State of the art in electromagnetic modeling for the Compact Linear Collider

DOE Office of Scientific and Technical Information (OSTI.GOV)

Candel, Arno; Kabel, Andreas; Lee, Lie-Quan

SLAC's Advanced Computations Department (ACD) has developed the parallel 3D electromagnetic time-domain code T3P for simulations of wakefields and transients in complex accelerator structures. T3P is based on state-of-the-art Finite Element methods on unstructured grids and features unconditional stability, quadratic surface approximation and up to 6th-order vector basis functions for unprecedented simulation accuracy. Optimized for large-scale parallel processing on leadership supercomputing facilities, T3P allows simulations of realistic 3D structures with fast turn-around times, aiding the design of the next generation of accelerator facilities. Applications include simulations of the proposed two-beam accelerator structures for the Compact Linear Collider (CLIC) - wakefieldmore » damping in the Power Extraction and Transfer Structure (PETS) and power transfer to the main beam accelerating structures are investigated.« less

Mechanical compaction directly modulates the dynamics of bile canaliculi formation.

PubMed

Wang, Yan; Toh, Yi-Chin; Li, Qiushi; Nugraha, Bramasta; Zheng, Baixue; Lu, Thong Beng; Gao, Yi; Ng, Mary Mah Lee; Yu, Hanry

2013-02-01

Homeostatic pressure-driven compaction is a ubiquitous mechanical force in multicellular organisms and is proposed to be important in the maintenance of multicellular tissue integrity and function. Previous cell-free biochemical models have demonstrated that there are cross-talks between compaction forces and tissue structural functions, such as cell-cell adhesion. However, its involvement in physiological tissue function has yet to be directly demonstrated. Here, we use the bile canaliculus (BC) as a physiological example of a multicellular functional structure in the liver, and employ a novel 3D microfluidic hepatocyte culture system to provide an unprecedented opportunity to experimentally modulate the compaction states of primary hepatocyte aggregates in a 3D physiological-mimicking environment. Mechanical compaction alters the physical attributes of the hepatocyte aggregates, including cell shape, cell packing density and cell-cell contact area, but does not impair the hepatocytes' remodeling and functional capabilities. Characterization of structural and functional polarity shows that BC formation in compact hepatocyte aggregates is accelerated to as early as 12 hours post-seeding; whereas non-compact control requires 48 hours for functional BC formation. Further dynamic immunofluorescence imaging and gene expression profiling reveal that compaction accelerated BC formation is accompanied by changes in actin cytoskeleton remodeling dynamics and transcriptional levels of hepatic nuclear factor 4α and Annexin A2. Our report not only provides a novel strategy of modeling BC formation for in vitro hepatology research, but also shows a first instance that homeostatic pressure-driven compaction force is directly coupled to the higher-order multicellular functions.

Inverse compton light source: a compact design proposal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deitrick, Kirsten Elizabeth

In the last decade, there has been an increasing demand for a compact Inverse Compton Light Source (ICLS) which is capable of producing high-quality X-rays by colliding an electron beam and a high-quality laser. It is only in recent years when both SRF and laser technology have advanced enough that compact sources can approach the quality found at large installations such as the Advanced Photon Source at Argonne National Laboratory. Previously, X-ray sources were either high flux and brilliance at a large facility or many orders of magnitude lesser when produced by a bremsstrahlung source. A recent compact source wasmore » constructed by Lyncean Technologies using a storage ring to produce the electron beam used to scatter the incident laser beam. By instead using a linear accelerator system for the electron beam, a significant increase in X-ray beam quality is possible, though even subsequent designs also featuring a storage ring offer improvement. Preceding the linear accelerator with an SRF reentrant gun allows for an extremely small transverse emittance, increasing the brilliance of the resulting X-ray source. In order to achieve sufficiently small emittances, optimization was done regarding both the geometry of the gun and the initial electron bunch distribution produced off the cathode. Using double-spoke SRF cavities to comprise the linear accelerator allows for an electron beam of reasonable size to be focused at the interaction point, while preserving the low emittance that was generated by the gun. An aggressive final focusing section following the electron beam's exit from the accelerator produces the small spot size at the interaction point which results in an X-ray beam of high flux and brilliance. Taking all of these advancements together, a world class compact X-ray source has been designed. It is anticipated that this source would far outperform the conventional bremsstrahlung and many other compact ICLSs, while coming closer to performing at the levels found at large facilities than ever before. The design process, including the development between subsequent iterations, is presented here in detail, with the simulation results for this groundbreaking X-ray source.« less

The failure of earthquake failure models

USGS Publications Warehouse

Gomberg, J.

2001-01-01

In this study I show that simple heuristic models and numerical calculations suggest that an entire class of commonly invoked models of earthquake failure processes cannot explain triggering of seismicity by transient or "dynamic" stress changes, such as stress changes associated with passing seismic waves. The models of this class have the common feature that the physical property characterizing failure increases at an accelerating rate when a fault is loaded (stressed) at a constant rate. Examples include models that invoke rate state friction or subcritical crack growth, in which the properties characterizing failure are slip or crack length, respectively. Failure occurs when the rate at which these grow accelerates to values exceeding some critical threshold. These accelerating failure models do not predict the finite durations of dynamically triggered earthquake sequences (e.g., at aftershock or remote distances). Some of the failure models belonging to this class have been used to explain static stress triggering of aftershocks. This may imply that the physical processes underlying dynamic triggering differs or that currently applied models of static triggering require modification. If the former is the case, we might appeal to physical mechanisms relying on oscillatory deformations such as compaction of saturated fault gouge leading to pore pressure increase, or cyclic fatigue. However, if dynamic and static triggering mechanisms differ, one still needs to ask why static triggering models that neglect these dynamic mechanisms appear to explain many observations. If the static and dynamic triggering mechanisms are the same, perhaps assumptions about accelerating failure and/or that triggering advances the failure times of a population of inevitable earthquakes are incorrect.

Laser Wakefield Accelerators: Next-Generation Light Sources

DOE PAGES

Albert, Felicie

2018-01-01

Here, a new breed of compact particle accelerators, capable of producing electron-beam energies in the GeV range, could soon bring some of the experimental power of synchrotrons and X-ray free-electron lasers to a tabletop near you.

Laser Wakefield Accelerators: Next-Generation Light Sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albert, Felicie

Here, a new breed of compact particle accelerators, capable of producing electron-beam energies in the GeV range, could soon bring some of the experimental power of synchrotrons and X-ray free-electron lasers to a tabletop near you.

GPU-accelerated low-latency real-time searches for gravitational waves from compact binary coalescence

NASA Astrophysics Data System (ADS)

Liu, Yuan; Du, Zhihui; Chung, Shin Kee; Hooper, Shaun; Blair, David; Wen, Linqing

2012-12-01

We present a graphics processing unit (GPU)-accelerated time-domain low-latency algorithm to search for gravitational waves (GWs) from coalescing binaries of compact objects based on the summed parallel infinite impulse response (SPIIR) filtering technique. The aim is to facilitate fast detection of GWs with a minimum delay to allow prompt electromagnetic follow-up observations. To maximize the GPU acceleration, we apply an efficient batched parallel computing model that significantly reduces the number of synchronizations in SPIIR and optimizes the usage of the memory and hardware resource. Our code is tested on the CUDA ‘Fermi’ architecture in a GTX 480 graphics card and its performance is compared with a single core of Intel Core i7 920 (2.67 GHz). A 58-fold speedup is achieved while giving results in close agreement with the CPU implementation. Our result indicates that it is possible to conduct a full search for GWs from compact binary coalescence in real time with only one desktop computer equipped with a Fermi GPU card for the initial LIGO detectors which in the past required more than 100 CPUs.

Phase II, Compact AMS System for Biological Tracer Detection Final Report CRADA No. TSV-1533-96

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, T. A.; Hamm, R. W.

2017-11-01

The objective of this collaboration between LLNL and AccSys Technology, Inc. of Pleasanton, California was to build and demonstrate a low cost, compact tritium (3H) Accelerator Mass Spectrometer (AMS) system matched to the requirements of biomedical research.

Compact torus accelerator as a driver for ICF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tobin, M.T.; Meier, W.R.; Morse, E.C.

1986-01-01

The authors have carried out further investigations of the technical issues associated with using a compact torus (CT) accelerator as a driver for inertial confinement fusion (ICF). In a CT accelerator, a magnetically confined, torus-shaped plasma is compressed, accelerated, and focused by two concentric electrodes. After its initial formation, the torus shape is maintained for lifetimes exceeding 1 ms by inherent poloidal and toroidal currents. Hartman suggests acceleration and focusing of such a plasma ring will not cause dissolution within certain constraints. In this study, we evaluated a point design based on an available capacitor bank energy of 9.2 MJ.more » This accelerator, which was modeled by a zero-dimensional code, produces a xenon plasma ring with a 0.73-cm radius, a velocity of 4.14 x 10/sup 9/ cm/s, and a mass of 4.42 ..mu..g. The energy of the plasma ring as it leaves the accelerator is 3.8 MJ, or 41% of the capacitor bank energy. Our studies confirm the feasibility of producing a plasma ring with the characteristics required to induce fusion in an ICF target with a gain greater than 50. The low cost and high efficiency of the CT accelerator are particularly attractive. Uncertainties concerning propagation, accelerator lifetime, and power supply must be resolved to establish the viability of the accelerator as an ICF driver.« less

Compact Superconducting Radio-frequency Accelerators and Innovative RF Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kephart, Robert; Chattopadhyay, Swaapan; Milton, Stephen

2015-04-10

We will present several new technical and design breakthroughs that enable the creation of a new class of compact linear electron accelerators for industrial purposes. Use of Superconducting Radio-Frequency (SRF) cavities allow accelerators less than 1.5 M in length to create electron beams beyond 10 MeV and with average beam powers measured in 10’s of KW. These machines can have the capability to vary the output energy dynamically to produce brehmstrahlung x-rays of varying spectral coverage for applications such as rapid scanning of moving cargo for security purposes. Such compact accelerators will also be cost effective for many existing andmore » new industrial applications. Examples include radiation crosslinking of plastics and rubbers, creation of pure materials with surface properties radically altered from the bulk, modification of bulk or surface optical properties of materials, sterilization of medical instruments animal solid or liquid waste, and destruction of organic compounds in industrial waste water effluents. Small enough to be located on a mobile platform, such accelerators will enable new remediation methods for chemical and biological spills and/or in-situ crosslinking of materials. We will describe one current design under development at Fermilab including plans for prototype and value-engineering to reduce costs. We will also describe development of new nano-structured field-emitter arrays as sources of electrons, new methods for fabricating and cooling superconducting RF cavities, and a new novel RF power source based on magnetrons with full phase and amplitude control.« less

Routes for the production of isotopes for PET with high intensity deuteron accelerators

NASA Astrophysics Data System (ADS)

Arias de Saavedra, F.; Porras, I.; Praena, J.

2018-04-01

Recent advances in accelerator science are opening new possibilities in different fields of physics. In particular, the development of compact linear accelerators that can provide charged particles of low-medium energy (few MeV) with high current (above mA) allows for the study of new possibilities in neutron production and for new routes for the production of radioisotopes. Keeping in mind how radioisotopes are actually produced in dedicated facilities, we have performed a study of alternative reactions to produce PET isotopes induced by low-energy deuterons. We have fitted the EXFOR cross sections data, used the fitted values of the stopping power by Andersen and Ziegler and calculated by numerical integration the production rate of isotopes for charged particles up to 20 MeV. The results for deuterons up to 3 MeV are compared with the ones from cyclotrons, which are able to provide higher energies to the charged projectiles but with lower intensities. Our results indicate that using linear accelerators may be a good alternative for producing PET isotopes, reducing the problem of neutron activation.

Compact, maintainable 80-KeV neutral beam module

DOEpatents

Fink, Joel H.; Molvik, Arthur W.

1980-01-01

A compact, maintainable 80-keV arc chamber, extractor module for a neutral beam system immersed in a vacuum of <10.sup.-2 Torr, incorporating a nested 60-keV gradient shield located midway between the high voltage ion source and surrounding grounded frame. The shield reduces breakdown or arcing path length without increasing the voltage gradient, tends to keep electric fields normal to conducting surfaces rather than skewed and reduces the peak electric field around irregularities on the 80-keV electrodes. The arc chamber or ion source is mounted separately from the extractor or ion accelerator to reduce misalignment of the accelerator and to permit separate maintenance to be performed on these systems. The separate mounting of the ion source provides for maintaining same without removing the ion accelerator.

Theory of unfolded cyclotron accelerator

NASA Astrophysics Data System (ADS)

Rax, J.-M.; Robiche, J.

2010-10-01

An acceleration process based on the interaction between an ion, a tapered periodic magnetic structure, and a circularly polarized oscillating electric field is identified and analyzed, and its potential is evaluated. A Hamiltonian analysis is developed in order to describe the interplay between the cyclotron motion, the electric acceleration, and the magnetic modulation. The parameters of this universal class of magnetic modulation leading to continuous acceleration without Larmor radius increase are expressed analytically. Thus, this study provides the basic scaling of what appears as a compact unfolded cyclotron accelerator.

High-gradient low-β accelerating structure using the first negative spatial harmonic of the fundamental mode

NASA Astrophysics Data System (ADS)

Kutsaev, Sergey V.; Agustsson, Ronald; Boucher, Salime; Fischer, Richard; Murokh, Alex; Mustapha, Brahim; Nassiri, Alireza; Ostroumov, Peter N.; Plastun, Alexander; Savin, Evgeny; Smirnov, Alexander Yu.

2017-12-01

The development of high-gradient accelerating structures for low-β particles is the key for compact hadron linear accelerators. A particular example of such a machine is a hadron therapy linac, which is a promising alternative to cyclic machines, traditionally used for cancer treatment. Currently, the practical utilization of linear accelerators in radiation therapy is limited by the requirement to be under 50 m in length. A usable device for cancer therapy should produce 200-250 MeV protons and/or 400 - 450 MeV /u carbon ions, which sets the requirement of having 35 MV /m average "real-estate gradient" or gradient per unit of actual accelerator length, including different accelerating sections, focusing elements and beam transport lines, and at least 50 MV /m accelerating gradients in the high-energy section of the linac. Such high accelerating gradients for ion linacs have recently become feasible for operations at S-band frequencies. However, the reasonable application of traditional S-band structures is practically limited to β =v /c >0.4 . However, the simulations show that for lower phase velocities, these structures have either high surface fields (>200 MV /m ) or low shunt impedances (<35 M Ω /m ). At the same time, a significant (˜10 % ) reduction in the linac length can be achieved by using the 50 MV /m structures starting from β ˜0.3 . To address this issue, we have designed a novel radio frequency structure where the beam is synchronous with the higher spatial harmonic of the electromagnetic field. In this paper, we discuss the principles of this approach, the related beam dynamics and especially the electromagnetic and thermomechanical designs of this novel structure. Besides the application to ion therapy, the technology described in this paper can be applied to future high gradient normal conducting ion linacs and high energy physics machines, such as a compact hadron collider. This approach preserves linac compactness in settings with limited space availability.

Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch

DOE PAGES

Kuschel, S.; Hollatz, D.; Heinemann, T.; ...

2016-07-20

We report on the first demonstration of passive all-optical plasma lensing using a two-stage setup. An intense femtosecond laser accelerates electrons in a laser wakefield accelerator (LWFA) to 100 MeV over millimeter length scales. By adding a second gas target behind the initial LWFA stage we introduce a robust and independently tunable plasma lens. We observe a density dependent reduction of the LWFA electron beam divergence from an initial value of 2.3 mrad, down to 1.4 mrad (rms), when the plasma lens is in operation. Such a plasma lens provides a simple and compact approach for divergence reduction well matchedmore » to the mm-scale length of the LWFA accelerator. The focusing forces are provided solely by the plasma and driven by the bunch itself only, making this a highly useful and conceptually new approach to electron beam focusing. Possible applications of this lens are not limited to laser plasma accelerators. Since no active driver is needed the passive plasma lens is also suited for high repetition rate focusing of electron bunches. As a result, its understanding is also required for modeling the evolution of the driving particle bunch in particle driven wake field acceleration.« less

Compact RF ion source for industrial electrostatic ion accelerator

NASA Astrophysics Data System (ADS)

Kwon, Hyeok-Jung; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub

2016-02-01

Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

Compact RF ion source for industrial electrostatic ion accelerator.

PubMed

Kwon, Hyeok-Jung; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub

2016-02-01

Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

Compact lumped circuit model of discharges in DC accelerator using partial element equivalent circuit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banerjee, Srutarshi; Rajan, Rehim N.; Singh, Sandeep K.

2014-07-01

DC Accelerators undergoes different types of discharges during its operation. A model depicting the discharges has been simulated to study the different transient conditions. The paper presents a Physics based approach of developing a compact circuit model of the DC Accelerator using Partial Element Equivalent Circuit (PEEC) technique. The equivalent RLC model aids in analyzing the transient behavior of the system and predicting anomalies in the system. The electrical discharges and its properties prevailing in the accelerator can be evaluated by this equivalent model. A parallel coupled voltage multiplier structure is simulated in small scale using few stages of coronamore » guards and the theoretical and practical results are compared. The PEEC technique leads to a simple model for studying the fault conditions in accelerator systems. Compared to the Finite Element Techniques, this technique gives the circuital representation. The lumped components of the PEEC are used to obtain the input impedance and the result is also compared to that of the FEM technique for a frequency range of (0-200) MHz. (author)« less

Bright betatron X-ray radiation from a laser-driven-clustering gas target

PubMed Central

Chen, L. M.; Yan, W. C.; Li, D. Z.; Hu, Z. D.; Zhang, L.; Wang, W. M.; Hafz, N.; Mao, J. Y.; Huang, K.; Ma, Y.; Zhao, J. R.; Ma, J. L.; Li, Y. T.; Lu, X.; Sheng, Z. M.; Wei, Z. Y.; Gao, J.; Zhang, J.

2013-01-01

Hard X-ray sources from femtosecond (fs) laser-produced plasmas, including the betatron X-rays from laser wakefield-accelerated electrons, have compact sizes, fs pulse duration and fs pump-probe capability, making it promising for wide use in material and biological sciences. Currently the main problem with such betatron X-ray sources is the limited average flux even with ultra-intense laser pulses. Here, we report ultra-bright betatron X-rays can be generated using a clustering gas jet target irradiated with a small size laser, where a ten-fold enhancement of the X-ray yield is achieved compared to the results obtained using a gas target. We suggest the increased X-ray photon is due to the existence of clusters in the gas, which results in increased total electron charge trapped for acceleration and larger wiggling amplitudes during the acceleration. This observation opens a route to produce high betatron average flux using small but high repetition rate laser facilities for applications. PMID:23715033

Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator

NASA Astrophysics Data System (ADS)

Čufar, Aljaž; Batistoni, Paola; Conroy, Sean; Ghani, Zamir; Lengar, Igor; Milocco, Alberto; Packer, Lee; Pillon, Mario; Popovichev, Sergey; Snoj, Luka; JET Contributors

2017-03-01

At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium-tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle-energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons.

A compact linear accelerator based on a scalable microelectromechanical-system RF-structure

DOE PAGES

Persaud, A.; Ji, Q.; Feinberg, E.; ...

2017-06-08

Here, a new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number ofmore » parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further red ucing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Finally, ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.« less

A compact linear accelerator based on a scalable microelectromechanical-system RF-structure

NASA Astrophysics Data System (ADS)

Persaud, A.; Ji, Q.; Feinberg, E.; Seidl, P. A.; Waldron, W. L.; Schenkel, T.; Lal, A.; Vinayakumar, K. B.; Ardanuc, S.; Hammer, D. A.

2017-06-01

A new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number of parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further reducing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.

A compact linear accelerator based on a scalable microelectromechanical-system RF-structure.

PubMed

Persaud, A; Ji, Q; Feinberg, E; Seidl, P A; Waldron, W L; Schenkel, T; Lal, A; Vinayakumar, K B; Ardanuc, S; Hammer, D A

2017-06-01

A new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number of parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further reducing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.

Pathway to a compact SASE FEL device

NASA Astrophysics Data System (ADS)

Dattoli, G.; Di Palma, E.; Petrillo, V.; Rau, Julietta V.; Sabia, E.; Spassovsky, I.; Biedron, S. G.; Einstein, J.; Milton, S. V.

2015-10-01

Newly developed high peak power lasers have opened the possibilities of driving coherent light sources operating with laser plasma accelerated beams and wave undulators. We speculate on the combination of these two concepts and show that the merging of the underlying technologies could lead to new and interesting possibilities to achieve truly compact, coherent radiator devices.

Aquifer-System Compaction and Land Subsidence: Measurements, Analyses, and Simulations-the Holly Site, Edwards Air Force Base, Antelope Valley, California

USGS Publications Warehouse

Sneed, Michelle; Galloway, Devin L.

2000-01-01

Land subsidence resulting from ground-water-level declines has long been recognized as a problem in Antelope Valley, California. At Edwards Air Force Base (EAFB), ground-water extractions have caused more than 150 feet of water-level decline, resulting in nearly 4 feet of subsidence. Differential land subsidence has caused sinklike depressions and earth fissures and has accelerated erosion of the playa lakebed surface of Rogers Lake at EAFB, adversely affecting the runways on the lakebed which are used for landing aircraft such as the space shuttles. Since 1990, about 0.4 foot of aquifer-system compaction has been measured at a deep (840 feet) borehole extensometer (Holly site) at EAFB. More than 7 years of paired ground-water-level and aquifer-system compaction measurements made at the Holly site were analyzed for this study. Annually, seasonal water-level fluctuations correspond to steplike variations in aquifer-system compaction; summer water-level drawdowns are associated with larger rates of compaction, and winter water-level recoveries are associated with smaller rates of compaction. The absence of aquifer-system expansion during recovery is consistent with the delayed drainage and resultant delayed, or residual, compaction of thick aquitards. A numerical one-dimensional MODFLOW model of aquitard drainage was used to refine estimates of aquifer-system hydraulic parameters that control compaction and to predict potential future compaction at the Holly site. The analyses and simulations of aquifer-system compaction are based on established theories of aquitard drainage. Historical ground-water-level and land-subsidence data collected near the Holly site were used to constrain simulations of aquifer-system compaction and land subsidence at the site for the period 1908?90, and ground-water-level and aquifer- system compaction measurements collected at the Holly site were used to constrain the model for the period 1990?97. Model results indicate that two thick aqui- tards, which total 129 feet or about half the aggregate thickness of all the aquitards penetrated by the Holly boreholes, account for most (greater than 99 percent) of the compaction measured at the Holly site during the period 1990?97. The results of three scenarios of future water-level changes indicate that these two thick aquitards account for most of the future compaction. The results also indicate that if water levels decline to about 30 feet below the 1997 water levels an additional 1.7 feet of compaction may occur during the next 30 years. If water levels remain at 1997 levels, the model predicts that only 0.8 foot of compaction may occur during the same period, and even if water levels recover to about 30 feet above 1997 water levels, another 0.5 foot of compaction may occur in the next 30 years. In addition, only a portion of the compaction that ultimately will occur likely will occur within the next 30 years; therefore, the residual compaction and associated land subsidence attributed to slowly equilibrating aquitards is important to consider in the long-term management of land and water resources at EAFB.

A compact tunable polarized X-ray source based on laser-plasma helical undulators

PubMed Central

Luo, J.; Chen, M.; Zeng, M.; Vieira, J.; Yu, L. L.; Weng, S. M.; Silva, L. O.; Jaroszynski, D. A.; Sheng, Z. M.; Zhang, J.

2016-01-01

Laser wakefield accelerators have great potential as the basis for next generation compact radiation sources because of their extremely high accelerating gradients. However, X-ray radiation from such devices still lacks tunability, especially of the intensity and polarization distributions. Here we propose a tunable polarized radiation source based on a helical plasma undulator in a plasma channel guided wakefield accelerator. When a laser pulse is initially incident with a skew angle relative to the channel axis, the laser and accelerated electrons experience collective spiral motions, which leads to elliptically polarized synchrotron-like radiation with flexible tunability on radiation intensity, spectra and polarization. We demonstrate that a radiation source with millimeter size and peak brilliance of 2 × 1019 photons/s/mm2/mrad2/0.1% bandwidth can be made with moderate laser and electron beam parameters. This brilliance is comparable with third generation synchrotron radiation facilities running at similar photon energies, suggesting that laser plasma based radiation sources are promising for advanced applications. PMID:27377126

GPU accelerated manifold correction method for spinning compact binaries

NASA Astrophysics Data System (ADS)

Ran, Chong-xi; Liu, Song; Zhong, Shuang-ying

2018-04-01

The graphics processing unit (GPU) acceleration of the manifold correction algorithm based on the compute unified device architecture (CUDA) technology is designed to simulate the dynamic evolution of the Post-Newtonian (PN) Hamiltonian formulation of spinning compact binaries. The feasibility and the efficiency of parallel computation on GPU have been confirmed by various numerical experiments. The numerical comparisons show that the accuracy on GPU execution of manifold corrections method has a good agreement with the execution of codes on merely central processing unit (CPU-based) method. The acceleration ability when the codes are implemented on GPU can increase enormously through the use of shared memory and register optimization techniques without additional hardware costs, implying that the speedup is nearly 13 times as compared with the codes executed on CPU for phase space scan (including 314 × 314 orbits). In addition, GPU-accelerated manifold correction method is used to numerically study how dynamics are affected by the spin-induced quadrupole-monopole interaction for black hole binary system.

First muon acceleration using a radio-frequency accelerator

NASA Astrophysics Data System (ADS)

Bae, S.; Choi, H.; Choi, S.; Fukao, Y.; Futatsukawa, K.; Hasegawa, K.; Iijima, T.; Iinuma, H.; Ishida, K.; Kawamura, N.; Kim, B.; Kitamura, R.; Ko, H. S.; Kondo, Y.; Li, S.; Mibe, T.; Miyake, Y.; Morishita, T.; Nakazawa, Y.; Otani, M.; Razuvaev, G. P.; Saito, N.; Shimomura, K.; Sue, Y.; Won, E.; Yamazaki, T.

2018-05-01

Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu- ), which are bound states of positive muons (μ+) and two electrons, are generated from μ+'s through the electron capture process in an aluminum degrader. The generated Mu- 's are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ). In the RFQ, the Mu- 's are accelerated to 89 keV. The accelerated Mu- 's are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

Compact injector with alternating phase focusing-interdigital H-mode linac and superconducting electron cyclotron resonance ion source for heavy ion cancer therapy

NASA Astrophysics Data System (ADS)

Hayashizaki, Noriyosu; Hattori, Toshiyuki; Matsui, Shinjiro; Tomizawa, Hiromitsu; Yoshida, Toru; Isokawa, Katsushi; Kitagawa, Atsushi; Muramatsu, Masayuki; Yamada, Satoru; Okamura, Masahiro

2000-02-01

We have researched a compact medical accelerator with low investment and running cost for the popularization of heavy ion cancer therapy. As the first step, the compact injector system has been investigated for a Heavy Ion Medical Accelerator in Chiba at National Institute of Radiological Sciences. The proposed new injector system consists of a 6 MeV/u interdigital H-mode (IH) linac of 3.1 m long and a 18 GHz superconducting electron cyclotron resonance (ECR) (SC-ECR) ion source. The IH linac with high power efficiency is appropriate to a medical and industrial injector system. Its beam trajectory was simulated and a prototype has been constructed. The SC-ECR ion source has been designed to realize lightweight and low power consumption and the mirror field distribution was estimated.

A CW FFAG for Proton Computed Tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnstone, C.; Neuffer, D. V.; Snopok, P.

2012-05-01

An advantage of the cyclotron in proton therapy is the continuous (CW) beam output which reduces complexity and response time in the dosimetry requirements and beam controls. A CW accelerator requires isochronous particle orbits at all energie s through the acceleration cycle and present compact isochronous cyclotrons for proton therapy reach only 250 MeV (kinetic energy) which is required for patient treatment, but low for full Proton Computed Tomography (PCT) capability. PCT specifications ne ed 300-330 MeV in order for protons to transit the human body. Recent innovations in nonscaling FFAG design have achieved isochronous performance in a compact (~3more » m radius) design at these higher energies. Preliminary isochronous designs are presented her e. Lower energy beams can be efficiently extracted for patient treatment without changes to the acceleration cycle and magnet currents.« less

Transport and energy selection of laser generated protons for postacceleration with a compact linac

NASA Astrophysics Data System (ADS)

Sinigardi, Stefano; Turchetti, Giorgio; Londrillo, Pasquale; Rossi, Francesco; Giove, Dario; De Martinis, Carlo; Sumini, Marco

2013-03-01

Laser accelerated proton beams have a considerable potential for various applications including oncological therapy. However, the most consolidated target normal sheath acceleration regime based on irradiation of solid targets provides an exponential energy spectrum with a significant divergence. The low count number at the cutoff energy seriously limits at present its possible use. One realistic scenario for the near future is offered by hybrid schemes. The use of transport lines for collimation and energy selection has been considered. We present here a scheme based on a high field pulsed solenoid and collimators which allows one to select a beam suitable for injection at 30 MeV into a compact linac in order to double its energy while preserving a significant intensity. The results are based on a fully 3D simulation starting from laser acceleration.

Compact Plasma Accelerator for Micropropulsion Applications

NASA Technical Reports Server (NTRS)

Foster, John E.

2001-01-01

There is a need for a low power, light-weight (compact), high specific impulse electric propulsion device to satisfy mission requirements for microsatellite (1 to 20 kg) class missions. Satisfying these requirements entails addressing the general problem of generating a sufficiently dense plasma within a relatively small volume and then accelerating it. In the work presented here, the feasibility of utilizing a magnetic cusp to generate a dense plasma over small length scales of order 1 mm is investigated. This approach could potentially mitigate scaling issues associated with conventional ion thruster plasma containment schemes. Plume and discharge characteristics were documented using a Faraday probe and a retarding potential analyzer.

A compact 500 MHz 4 kW Solid-State Power Amplifier for accelerator applications

NASA Astrophysics Data System (ADS)

Gaspar, M.; Pedrozzi, M.; Ferreira, L. F. R.; Garvey, T.

2011-05-01

We present the development of a compact narrow-band Solid-State Power Amplifier (SSPA). We foresee a promising application of solid-state amplifiers specifically in accelerators for new generation synchrotron light sources. Such a new technology has reached a competitive price/performance ratio and expected lifetime in comparison with klystron and IOT amplifiers. The increasing number of synchrotron light sources using 500 MHz as base frequency justifies the effort in the development of the proposed amplifier. Two different techniques are also proposed to improve the control and performance of these new distributed amplification systems which we call, respectively, complete distributed system and forced compression.

Recent advances in laser-driven neutron sources

NASA Astrophysics Data System (ADS)

Alejo, A.; Ahmed, H.; Green, A.; Mirfayzi, S. R.; Borghesi, M.; Kar, S.

2016-11-01

Due to the limited number and high cost of large-scale neutron facilities, there has been a growing interest in compact accelerator-driven sources. In this context, several potential schemes of laser-driven neutron sources are being intensively studied employing laser-accelerated electron and ion beams. In addition to the potential of delivering neutron beams with high brilliance, directionality and ultra-short burst duration, a laser-driven neutron source would offer further advantages in terms of cost-effectiveness, compactness and radiation confinement by closed-coupled experiments. Some of the recent advances in this field are discussed, showing improvements in the directionality and flux of the laser-driven neutron beams.

[Morphological changes of neurons and neuroglial cells in the brain of senescence-accelerated prone 1 (SAMP1) mice].

PubMed

Khudoerkov, R M; Sal'kov, V N; Sal'nikova, O V; Sobolev, V B

2014-01-01

Computerized morphometry was used to examine the sizes of neuronal bodies and the compactness of arrangement of neurons and neuroglial cells in layers III and V of the sensorimotor cortex in senescence-accelerated prone 1 (SAMP1) mice (an experimental group) and senescence-accelerated-resistant strain 1 (SAMR1) ones (a control group). In the SAMP1 mice as compared to the SAMR1 ones, the neuronal body sizes were significantly unchanged; the compactness of their arrangement decreased by 17 and 20% in layers III and V, respectively; that of neuroglial cells significantly increased by 14% in layer III only. In the SAMP1 mice versus the SAMR1 ones, the glial index rose by 36% in layer III and by 24% in layer V. During simulation of physiological aging, the sizes of neuronal bodies were shown to be virtually unchanged in the cerebral cortex; the compactness of their arrangement (cell counts) moderately reduced and that of neuroglial cells increased, which caused a rise in the glioneuronal index that was indicative of the enhanced supporting function of neuroglial cells during the physiological aging of brain structures.

Ultra-High Accelerating Gradients in Radio-Frequency Cryogenic Copper Structures

NASA Astrophysics Data System (ADS)

Cahill, Alexander David

Normal conducting radio-frequency (rf) particle accelerators have many applications, including colliders for high energy physics, high-intensity synchrotron light sources, non-destructive testing for security, and medical radiation therapy. In these applications, the accelerating gradient is an important parameter. Specifically for high energy physics, increasing the accelerating gradient extends the potential energy reach and is viewed as a way to mitigate their considerable cost. Furthermore, a gradient increase will enable for more compact and thus accessible free electron lasers (FELs). The major factor limiting larger accelerating gradients is vacuum rf breakdown. Basic physics of this phenomenon has been extensively studied over the last few decades. During which, the occurrence of rf breakdowns was shown to be probabilistic, and can be characterized by a breakdown rate. The current consensus is that vacuum rf breakdowns are caused by movements of crystal defects induced by periodic mechanical stress. The stress may be caused by pulsed surface heating and large electric fields. A compelling piece of evidence that supports this hypothesis is that accelerating structures constructed from harder materials exhibit larger accelerating gradients for similar breakdown rates. One possible method to increase sustained electric fields in copper cavities is to cool them to temperatures below 77 K, where the rf surface resistance and coefficient of thermal expansion decrease, while the yield strength (which correlates with hardness) and thermal conductivity increase. These changes in material properties at low temperature increases metal hardness and decreases the mechanical stress from exposure to rf electromagnetic fields. To test the validity of the improvement in breakdown rate, experiments were conducted with cryogenic accelerating cavities in the Accelerator Structure Test Area (ASTA) at SLAC National Accelerator Laboratory. A short 11.4 GHz standing wave accelerating structure was conditioned to an accelerating gradient of 250 MV/m at 45 K with 108 rf pulses. At gradients greater than 150 MV/m I observed a degradation in the intrinsic quality factor of the cavity, Q0. I developed a model for the change in Q0 using measured field emission currents and rf signals. I found that the Q 0 degradation is consistent with the rf power being absorbed by strong field emission currents accelerated inside the cavity. I measured rf breakdown rates for 45 K and found 2*10-4/pulse/meter when accounting for any change in Q0. These are the largest accelerating gradients for a structure with similar breakdown rates. The final chapter presents the design of an rf photoinjector electron source that uses the cryogenic normal conducting accelerator technology: the TOPGUN. With this cryogenic rf photoinjector, the beam brightness will increase by over an order of a magnitude when compared to the current photoinjector for the Linac Coherent Light Source (LCLS). When using the TOPGUN as the source for an X-ray Free Electron Laser, the higher brightness would allow for a decrease in the required length of the LCLS undulator by more than a factor of two.

Post-acceleration of laser driven protons with a compact high field linac

NASA Astrophysics Data System (ADS)

Sinigardi, Stefano; Londrillo, Pasquale; Rossi, Francesco; Turchetti, Giorgio; Bolton, Paul R.

2013-05-01

We present a start-to-end 3D numerical simulation of a hybrid scheme for the acceleration of protons. The scheme is based on a first stage laser acceleration, followed by a transport line with a solenoid or a multiplet of quadrupoles, and then a post-acceleration section in a compact linac. Our simulations show that from a laser accelerated proton bunch with energy selection at ~ 30MeV, it is possible to obtain a high quality monochromatic beam of 60MeV with intensity at the threshold of interest for medical use. In the present day experiments using solid targets, the TNSA mechanism describes accelerated bunches with an exponential energy spectrum up to a cut-off value typically below ~ 60MeV and wide angular distribution. At the cut-off energy, the number of protons to be collimated and post-accelerated in a hybrid scheme are still too low. We investigate laser-plasma acceleration to improve the quality and number of the injected protons at ~ 30MeV in order to assure efficient post-acceleration in the hybrid scheme. The results are obtained with 3D PIC simulations using a code where optical acceleration with over-dense targets, transport and post-acceleration in a linac can all be investigated in an integrated framework. The high intensity experiments at Nara are taken as a reference benchmarks for our virtual laboratory. If experimentally confirmed, a hybrid scheme could be the core of a medium sized infrastructure for medical research, capable of producing protons for therapy and x-rays for diagnosis, which complements the development of all optical systems.

Exploring Granular Flows at Intermediate Velocities

NASA Astrophysics Data System (ADS)

Brodsky, E. E.; van der Elst, N.

2012-12-01

Geophysical and geomorphological flows often encompass a wide range of strain rates. Landslides accelerate from nearly static conditions to velocities in the range of meters/seconds. The rheology of granular flows for the end-members is moderately well-understood, but the constitutive low at intermediate velocities is largely unexplored. Here we present evidence that granular flows transition through a regime in which internally generated acoustic waves play a critical role in controlling rheology. In laboratory experiments on natural sand under shear in a commercial rheometer, we observe that the steady-state flows at intermediate velocities are compacted relative to the end members. In a confined volume, this compaction results in a decrease in stress on the boundaries. We establish the key role of the acoustic waves by measuring the noise generated by the shear flows with an accelerometer and then exciting the flow with similar amplitude noise under lower shear rate conditions. The observed compaction for a given amplitude noise is the same in both cases, regardless of whether the noise is generated internally by the grains colliding or artificially applied externally. The boundaries of this acoustically controlled regime can be successfully predicted through non-dimensional analysis balancing the overburden, acoustic pressure and granular inertial terms. In our laboratory experiments, this regime corresponds to 0.1 to 10 cm/s. The controlling role of acoustic waves in intermediate velocities is significant because: (1) Geological systems must pass through this regime on their route to instability. (2) Acoustic waves are much more efficiently generated by angular particles, likely to be found in natural samples, than by perfectly spherical particles, which are more tractable for laboratory and theoretical studies. Therefore, this regime is likely to be missed in many analog and computational approaches. (3) Different mineralogies and shapes result in different noise generation. Therefore, there is a potential to extrapolate and predict rheological behavior of an active flow through studies of the recoverable granular products.Steady-state thickness vs. shear rate for angular sand and glass beads. Individual curves represent multiple up-going and down-going velocity ramps, and thick error bars show means and standard deviations between runs. Thickness is independent of shear rate at low shear rates, and strongly dependent on shear rate for intermediate and high shear rates. Compaction is observed at intermediate shear rates for angular sand, but not for smooth glass beads.

Compact Torus plasma ring accelerator: a new type driver for inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartman, C.W.; Eddleman, J.L.; Hammer, J.H.

1986-08-22

We discuss the acceleration of magnetically-confined plasma rings to provide a driver for ICF. The acceleration of plasma rings is predicted to be efficient and following focusing, to generate ion-bombardment power in the range 10/sup 15/ to 10/sup 16/ W/cm/sup 2/ at a total deposition energy of multimegajoules. The simplicity of plasma ring accelerator suggests that a 5 MJ (on target) driver would cost in the range 1 to 5 $/joule. First experimental tests of the accelerator are described.

Generation and application of ultrashort coherent mid-infrared electromagnetic radiation

NASA Astrophysics Data System (ADS)

Wandel, Scott

Particle accelerators are useful instruments that help address critical issues for the future development of nuclear energy. Current state-of-the-art accelerators based on conventional radio-frequency (rf) cavities are too large and expensive for widespread commercial use, and alternative designs must be considered for supplying relativistic beams to small-scale applications, including medical imaging, secu- rity screening, and scientific research in a university-scale laboratory. Laser-driven acceleration using micro-fabricated dielectric photonic structures is an attractive approach because such photonic microstructures can support accelerating fields that are 10 to 100 times higher than that of rf cavity-based accelerators. Dielectric laser accelerators (DLAs) use commercial lasers as a driving source, which are smaller and less expensive than the klystrons used to drive current rf-based accelerators. Despite the apparent need for compact and economical laser sources for laser-driven acceleration, the availability of suitable high-peak-power lasers that cover a broad spectral range is currently limited. To address the needs of several innovative acceleration mechanisms like DLA, it is proposed to develop a coherent source of mid-infrared (IR) electromagnetic radiation that can be implemented as a driving source of laser accelerators. The use of ultrashort mid-IR high peak power laser systems in various laser-driven acceleration schemes has shown the potential to greatly reduce the optical pump intensities needed to realize high acceleration gradients. The optical intensity needed to achieve a given ponderomotive potential is 25 times less when using a 5-mum mid-IR laser as compared to using a 1-mum near-IR solid-state laser. In addition, dielectric structure breakdown caused by multiphoton ionization can be avoided by using longer-wavelength driving lasers. Current mid-IR laser sources do not produce sufficiently short pulse durations, broad spectral bandwidths, or high energies as required by certain accelerator applications. The use of a high-peak-power mid-IR laser system in DLA could enable tabletop accelerators on the MeV to GeV scale for security scanners, medical therapy devices, and compact x-ray light sources. This dissertation reports on the design and construction of a simple and robust, short-pulse parametric source operating at a center wavelength of 5 mum. The design and construction of a high-energy, short-pulse 2-mum parametric source is also presented, which serves as a surrogate pumping source for the 5-mum source. An elegant method for mid-IR pulse characterization is demonstrated, which makes use of ubiquitous silicon photodetectors, traditionally reserved for the characterization of near-IR radiation. In addition, a dual-chirped parametric amplification technique is extended into the mid-IR spectral region, producing a bandwidth-tunable mid-IR source in a simple design without sacrificing conversion efficiency. The design and development of a compact single-shot mid-IR prism spectrometer is also reported, and its implementation in a number of condensed matter studies at the Linac Coherent Light Source (LCLS) at the Stanford Linear Accelerator Center is discussed. Rapid tuning and optimization of a high-energy parametric laser system using the mid-IR spectrometer is demonstrated, which significantly enhances the capabilities of performing optical measurements on superconducting materials using the LCLS instrument. All of the laser sources and optical technologies presented in this dissertation were developed using relatively simple designs to provide compact and cost-e ective systems to address some of the challenges facing accelerator and IR spectroscopy technologies. (Abstract shortened by ProQuest.).

Quasi-monoenergetic multi-GeV electron acceleration by optimizing the spatial and spectral phases of PW laser pulses

NASA Astrophysics Data System (ADS)

Shin, Junghun; Kim, Hyung Taek; Pathak, V. B.; Hojbota, Calin; Lee, Seong Ku; Sung, Jae Hee; Lee, Hwang Woon; Yoon, Jin Woo; Jeon, Cheonha; Nakajima, Kazuhisa; Sylla, F.; Lifschitz, A.; Guillaume, E.; Thaury, C.; Malka, V.; Nam, Chang Hee

2018-06-01

Generation of high-quality electron beams from laser wakefield acceleration requires optimization of initial experimental parameters. We present here the dependence of accelerated electron beams on the temporal profile of a driving PW laser, the density, and length of an interacting medium. We have optimized the initial parameters to obtain 2.8 GeV quasi-monoenergetic electrons which can be applied further to the development of compact electron accelerators and radiations sources.

Thomson-backscattered x rays from laser-accelerated electrons.

PubMed

Schwoerer, H; Liesfeld, B; Schlenvoigt, H-P; Amthor, K-U; Sauerbrey, R

2006-01-13

We present the first observation of Thomson-backscattered light from laser-accelerated electrons. In a compact, all-optical setup, the "photon collider," a high-intensity laser pulse is focused into a pulsed He gas jet and accelerates electrons to relativistic energies. A counterpropagating laser probe pulse is scattered from these high-energy electrons, and the backscattered x-ray photons are spectrally analyzed. This experiment demonstrates a novel source of directed ultrashort x-ray pulses and additionally allows for time-resolved spectroscopy of the laser acceleration of electrons.

Research opportunities with compact accelerator-driven neutron sources

NASA Astrophysics Data System (ADS)

Anderson, I. S.; Andreani, C.; Carpenter, J. M.; Festa, G.; Gorini, G.; Loong, C.-K.; Senesi, R.

2016-10-01

Since the discovery of the neutron in 1932 neutron beams have been used in a very broad range of applications, As an aging fleet of nuclear reactor sources is retired the use of compact accelerator-driven neutron sources (CANS) is becoming more prevalent. CANS are playing a significant and expanding role in research and development in science and engineering, as well as in education and training. In the realm of multidisciplinary applications, CANS offer opportunities over a wide range of technical utilization, from interrogation of civil structures to medical therapy to cultural heritage study. This paper aims to provide the first comprehensive overview of the history, current status of operation, and ongoing development of CANS worldwide. The basic physics and engineering regarding neutron production by accelerators, target-moderator systems, and beam line instrumentation are introduced, followed by an extensive discussion of various evolving applications currently exploited at CANS.

The influence of using accelerator addition on High strength self-compacting concrete (HSSCC) in case of enhancement early compressive strength and filling ability parameters

NASA Astrophysics Data System (ADS)

Wibowo; Fadillah, Y.

2018-03-01

Efficiency in a construction works is a very important thing. Concrete with ease of workmanship and rapid achievement of service strength will to determine the level of efficiency. In this research, we studied the optimization of accelerator usage in achieving performance on compressive strength of concrete in function of time. The addition of variation of 0.3% - 2.3% to the weight of cement gives a positive impact of the rapid achievement of hardened concrete, however the speed of increasing of concrete strength achievement in term of time influence present increasing value of filling ability parameter of self-compacting concrete. The right composition of accelerator aligned with range of the values standard of filling ability parameters of HSSCC will be an advantage guidance for producers in the ready-mix concrete industry.

The GALAXIE all-optical FEL project

NASA Astrophysics Data System (ADS)

Rosenzweig, J. B.; Arab, E.; Andonian, G.; Cahill, A.; Fitzmorris, K.; Fukusawa, A.; Hoang, P.; Jovanovic, I.; Marcus, G.; Marinelli, A.; Murokh, A.; Musumeci, P.; Naranjo, B.; O'Shea, B.; O'Shea, F.; Ovodenko, A.; Pogorelsky, I.; Putterman, S.; Roberts, K.; Shumail, M.; Tantawi, S.; Valloni, A.; Yakimenko, V.; Xu, G.

2012-12-01

We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 μm laser development, ultra-high brighness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.

Sequentially pulsed traveling wave accelerator

DOEpatents

Caporaso, George J [Livermore, CA; Nelson, Scott D [Patterson, CA; Poole, Brian R [Tracy, CA

2009-08-18

A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

Permanent magnet focused X-band photoinjector

DOEpatents

Yu, David U. L.; Rosenzweig, James

2002-09-10

A compact high energy photoelectron injector integrates the photocathode directly into a multicell linear accelerator with no drift space between the injection and the linac. High electron beam brightness is achieved by accelerating a tightly focused electron beam in an integrated, multi-cell, X-band rf linear accelerator (linac). The photoelectron linac employs a Plane-Wave-Transformer (PWT) design which provides strong cell-to-cell coupling, easing manufacturing tolerances and costs.

Modular compact solid-state modulators for particle accelerators

NASA Astrophysics Data System (ADS)

Zavadtsev, A. A.; Zavadtsev, D. A.; Churanov, D. V.

2017-12-01

The building of the radio frequency (RF) particle accelerator needs high-voltage pulsed modulator as a power supply for klystron or magnetron to feed the RF accelerating system. The development of a number of solid-state modulators for use in linear accelerators has allowed to develop a series of modular IGBT based compact solid-state modulators with different parameters. This series covers a wide range of needs in accelerator technology to feed a wide range of loads from the low power magnetrons to powerful klystrons. Each modulator of the series is built on base of a number of unified solid-state modules connected to the pulse transformer, and covers a wide range of modulators: voltage up to 250 kV, a peak current up to 250 A, average power up to 100 kW and the pulse duration up to 20 μsec. The parameters of the block with an overall dimensions 880×540×250 mm are: voltage 12 kV, peak current 1600 A, pulse duration 20 μsec, average power 10 kW with air-cooling and 40 kW with liquidcooling. These parameters do not represent a physical limit, and modulators to parameters outside these ranges can be created on request.

Ring design of the Prague synchrotron for cancer therapy

NASA Astrophysics Data System (ADS)

Molodozhentsev, A.; Makoveev, V.; Minashkin, V.; Shevtsov, V.; Sidorov, G.; Prokesh, K.; Sedlak, J.; Kuzmiak, M.

1998-04-01

The paper presents main elements of a dedicated proton synchrotron for hadron therapy. The beam parameters for active scanning of tumours are discussed. The output energy of the beam should be variable in the range 60-220 MeV. The average current of the proton beam is equal to 10 nA. The repetition rate of the accelerator is chosen of 1 Hz to get a spill time for slow extraction of about 500 ms. The timing cycle of the accelerator including the quasi-adiabatic capture process and acceleration is described. The RF gymnastics is utilized to prepare the unbunched beam for slow extraction. The magnetic elements of the ring, compact RF and VCO systems are presented in the paper. The maximum magnet field of the dipole magnet should be 1.2 T and the maximum magnetic field on the pole of the quadrupole lenses should be less than 1 T. The resonator should work on the first harmonic with a frequency from 1.298 MHz till 4.804 MHz. The length of the resonator should be less than 1 m. The maximum voltage on the accelerator gap should be about 2 kV.

Pellet injector development at ORNL (Oak Ridge National Laboratory)

NASA Astrophysics Data System (ADS)

Gouge, M. J.; Argo, B. E.; Baylor, L. R.; Combs, S. K.; Fehling, D. T.; Fisher, P. W.; Foster, C. A.; Foust, C. R.; Milora, S. L.; Qualls, A. L.

1990-09-01

Advanced plasma fueling systems for magnetic confinement experiments are under development at Oak Ridge National Laboratory (ORNL). The general approach is that of producing and accelerating frozen hydrogenic pellets to speeds in the kilometer-per-second range by either pneumatic (light-gas gun) or mechanical (centrifugal force) techniques. ORNL has recently provided a centrifugal pellet injector for the Tore Supra tokamak and a new, simplified, eight-shot pneumatic injector for the Advanced Toroidal Facility stellarator at ORNL. Hundreds of tritium and DT pellets were accelerated at the Tritium Systems Test Assembly facility at Los Alamos in 1988 to 1989. These experiments, done in a single-shot pipe-gun system, demonstrated the feasibility of forming and accelerating tritium pellets at low (sup 3)He levels. A new, tritium-compatible extruder mechanism is being designed for longer-pulse DT applications. Two-stage light-gas guns and electron beam rocket accelerators for speeds of the order of 2 to 10 km/s are also under development. Recently, a repeating, two-stage light-gas gun accelerated 10 surrogate pellets at a 1-Hz repetition rate to speeds in the range of 2 to 3 km/s; and the electron beam rocket accelerator completed initial feasibility and scaling experiments. ORNL has also developed conceptual designs of advanced plasma fueling systems for the Compact Ignition Tokamak and the International Thermonuclear Experimental Reactor.

Compact Torus Injection Experiments on the H.I.T. teststand and the JFT-2M tokamak

NASA Astrophysics Data System (ADS)

Fukumoto, Naoyuki; Fujiwara, Makoto; Kuramoto, Keiji; Ageishi, Masaya; Nagata, Masayoshi; Uyama, Tadao; Ogawa, Hiroaki; Kasai, Satoshi; Hasegawa, Kouichi; Shibata, Takatoshi

1997-11-01

A spheromak-type compact torus (CT) acceleration and injection experiment has been carried out using the Himeji Institute of Technology Compact Torus Injector (HIT-CTI). We investigate the possibility of refueling, density control, current drive, and edge electric field control of tokamak plasmas by means of CT injection. The HIT-CTI produces a CT with a speed of 200 km/s and a density of 1× 10^21m-3. We have constructed new electrodes and power supplies, and will install the HIT-CTI on the JFT-2M tokamak at JAERI in Autumn 1997. The outer electrode serves as a common ground for both the formation bank (144μF, 20kV) and the acceleration bank (92.4μF, 40kV). If the external toroidal field of the tokamak is applied across the CT acceleration region, the CT kinetic energy might decrease during penetration into the field lines joining the inner and outer electrode. This could result in the CT not being able to reach the core of the tokamak plasma. Determining the optimum position of the inner electrode is one of the near term goals of this research. We will present magnetic probe, He-Ne interferometer and fast framing camera data from experiments at H.I.T., where a CT was accelerated into a transverse field. We will also present initial results from the operation of the HIT-CTI on the JFT-2M tokamak.

Focusing and transport of high-intensity multi-MeV proton bunches from a compact laser-driven source

NASA Astrophysics Data System (ADS)

Busold, S.; Schumacher, D.; Deppert, O.; Brabetz, C.; Frydrych, S.; Kroll, F.; Joost, M.; Al-Omari, H.; Blažević, A.; Zielbauer, B.; Hofmann, I.; Bagnoud, V.; Cowan, T. E.; Roth, M.

2013-10-01

Laser ion acceleration provides for compact, high-intensity ion sources in the multi-MeV range. Using a pulsed high-field solenoid, for the first time high-intensity laser-accelerated proton bunches could be selected from the continuous exponential spectrum and delivered to large distances, containing more than 109 particles in a narrow energy interval around a central energy of 9.4 MeV and showing ≤30mrad envelope divergence. The bunches of only a few nanoseconds bunch duration were characterized 2.2 m behind the laser-plasma source with respect to arrival time, energy width, and intensity as well as spatial and temporal bunch profile.

A compact ECG R-R interval, respiration and activity recording system.

PubMed

Yoshimura, Takahiro; Yonezawa, Yoshiharu; Maki, Hiromichi; Ogawa, Hidekuni; Hahn, Allen W; Thayer, Julian F; Caldwell, W Morton

2003-01-01

An ECG R-R interval, respiration and activity recording system has been developed for monitoring variability of heart rate and respiratory frequency during daily life. The recording system employs a variable gain instrumentation amplifier, an accelerometer, a low power 8-bit single-chip microcomputer and a 1024 KB EEPROM. It is constructed on three ECG chest electrodes. The R-R interval and respiration are detected from the ECG. Activity during walking and running is calculated from an accelerator. The detected data are stored in an EEPROM and after recording, are downloaded to a desktop computer for analysis.

ACCELERATION OF COMPACT RADIO JETS ON SUB-PARSEC SCALES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Sang-Sung; Lobanov, Andrei P.; Krichbaum, Thomas P.

2016-08-01

Jets of compact radio sources are highly relativistic and Doppler boosted, making studies of their intrinsic properties difficult. Observed brightness temperatures can be used to study the intrinsic physical properties of relativistic jets, and constrain models of jet formation in the inner jet region. We aim to observationally test such inner jet models. The very long baseline interferometry (VLBI) cores of compact radio sources are optically thick at a given frequency. The distance of the core from the central engine is inversely proportional to the frequency. Under the equipartition condition between the magnetic field energy and particle energy densities, themore » absolute distance of the VLBI core can be predicted. We compiled the brightness temperatures of VLBI cores at various radio frequencies of 2, 8, 15, and 86 GHz. We derive the brightness temperature on sub-parsec scales in the rest frame of the compact radio sources. We find that the brightness temperature increases with increasing distance from the central engine, indicating that the intrinsic jet speed (the Lorentz factor) increases along the jet. This implies that the jets are accelerated in the (sub-)parsec regions from the central engine.« less

RF pulse shape control in the compact linear collider test facility

NASA Astrophysics Data System (ADS)

Kononenko, Oleksiy; Corsini, Roberto

2018-07-01

The Compact Linear Collider (CLIC) is a study for an electron-positron machine aiming at accelerating and colliding particles at the next energy frontier. The CLIC concept is based on the novel two-beam acceleration scheme, where a high-current low-energy drive beam generates RF in series of power extraction and transfer structures accelerating the low-current main beam. To compensate for the transient beam-loading and meet the energy spread specification requirements for the main linac, the RF pulse shape must be carefully optimized. This was recently modelled by varying the drive beam phase switch times in the sub-harmonic buncher so that, when combined, the drive beam modulation translates into the required voltage modulation of the accelerating pulse. In this paper, the control over the RF pulse shape with the phase switches, that is crucial for the success of the developed compensation model, is studied. The results on the experimental verification of this control method are presented and a good agreement with the numerical predictions is demonstrated. Implications for the CLIC beam-loading compensation model are also discussed.

Plasma density characterization at SPARC_LAB through Stark broadening of Hydrogen spectral lines

NASA Astrophysics Data System (ADS)

Filippi, F.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

2016-09-01

Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC_LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC_LAB is presented.

On intrinsic nonlinear particle motion in compact synchrotrons

NASA Astrophysics Data System (ADS)

Hwang, Kyung Ryun

Due to the low energy and small curvature characteristics of compact synchrotrons, there can be unexpected features that were not present or negligible in high energy accelerators. Nonlinear kinetics, fringe field effect, and space charge effect are those features which become important for low energy and small curvature accelerators. Nonlinear kinematics can limit the dynamics aperture for compact machine even if it consists of all linear elements. The contribution of the nonlinear kinematics on nonlinear optics parameters are first derived. As the dipole bending radius become smaller, the dipole fringe field effect become stronger. Calculation of the Lie map generator and corresponding mapping equation of dipole fringe field is presented. It is found that the higher order nonlinear potential is inverse proportional to powers of fringe field extent and correction to focusing and low order nonlinear potential is proportional to powers of fringe field extent. The fringe field also found to cause large closed orbit deviation for compact synchrotrons. The 2:1 and 4:1 space charge resonances are known to cause beam loss, emittance growth and halo formation for low energy high intensity beams. By numerical simulations, we observe a higher order 6:2 space charge resonance, which can successfully be understood by the concatenation of 2:1 and 4:1 resonances via canonical perturbation. We also develop an explicit symplectic tracking method for compact electrostatic storage rings and explore the feasibility of electric dipole moment (EDM) measurements.

A compact control system to achieve stable voltage and low jitter trigger for repetitive intense electron-beam accelerator based on resonant charging

NASA Astrophysics Data System (ADS)

Qiu, Yongfeng; Liu, Jinliang; Yang, Jianhua; Cheng, Xinbing; Yang, Xiao

2017-08-01

A compact control system based on Delphi and Field Programmable Gate Array(FPGA) is developed for a repetitive intense electron-beam accelerator(IEBA), whose output power is 10GW and pulse duration is 160ns. The system uses both hardware and software solutions. It comprises a host computer, a communication module and a main control unit. A device independent applications programming interface, devised using Delphi, is installed on the host computer. Stability theory of voltage in repetitive mode is analyzed and a detailed overview of the hardware and software configuration is presented. High voltage experiment showed that the control system fulfilled the requests of remote operation and data-acquisition. The control system based on a time-sequence control method is used to keep constant of the voltage of the primary capacitor in every shot, which ensured the stable and reliable operation of the electron beam accelerator in the repetitive mode during the experiment. Compared with the former control system based on Labview and PIC micro-controller developed in our laboratory, the present one is more compact, and with higher precision in the time dimension. It is particularly useful for automatic control of IEBA in the high power microwave effects research experiments where pulse-to-pulse reproducibility is required.

TU-H-BRA-02: The Physics of Magnetic Field Isolation in a Novel Compact Linear Accelerator Based MRI-Guided Radiation Therapy System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Low, D; Mutic, S; Shvartsman, S

Purpose: To develop a method for isolating the MRI magnetic field from field-sensitive linear accelerator components at distances close to isocenter. Methods: A MRI-guided radiation therapy system has been designed that integrates a linear accelerator with simultaneous MR imaging. In order to accomplish this, the magnetron, port circulator, radiofrequency waveguide, gun driver, and linear accelerator needed to be placed in locations with low magnetic fields. The system was also required to be compact, so moving these components far from the main magnetic field and isocenter was not an option. The magnetic field sensitive components (exclusive of the waveguide) were placedmore » in coaxial steel sleeves that were electrically and mechanically isolated and whose thickness and placement were optimized using E&M modeling software. Six sets of sleeves were placed 60° apart, 85 cm from isocenter. The Faraday effect occurs when the direction of propagation is parallel to the magnetic RF field component, rotating the RF polarization, subsequently diminishing RF power. The Faraday effect was avoided by orienting the waveguides such that the magnetic field RF component was parallel to the magnetic field. Results: The magnetic field within the shields was measured to be less than 40 Gauss, significantly below the amount needed for the magnetron and port circulator. Additional mu-metal was employed to reduce the magnetic field at the linear accelerator to less than 1 Gauss. The orientation of the RF waveguides allowed the RT transport with minimal loss and reflection. Conclusion: One of the major challenges in designing a compact linear accelerator based MRI-guided radiation therapy system, that of creating low magnetic field environments for the magnetic-field sensitive components, has been solved. The measured magnetic fields are sufficiently small to enable system integration. This work supported by ViewRay, Inc.« less

Laser wakefield accelerated electron beam monitoring and control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koga, J. K.; Mori, M.; Kotaki, H.

2016-03-25

We will discuss our participation in the ImPACT project, which has as one of its goals the development of an ultra-compact electron accelerator using lasers (< 1 GeV, < 10   m) and the generation of an x-ray beam from the accelerated electrons. Within this context we will discuss our investigation into electron beam monitoring and control. Since laser accelerated electrons will be used for x-ray beam generation combined with an undulator, we will present investigation into the possibilities of the improvement of electron beam emittance through cooling.

The Rapid Formation of Localized Compaction Bands Under Hydrostatic Load Leading to Pore-pressure Transients in Compacting Rocks

NASA Astrophysics Data System (ADS)

Faulkner, D.; Leclere, H.; Bedford, J. D.; Behnsen, J.; Wheeler, J.

2017-12-01

Compaction of porous rocks can occur uniformly or within localized deformation bands. The formation of compaction bands and their effects on deformation behaviour are poorly understood. Porosity may be primary and compaction can occur with burial, or it can be produced by metamorphic reactions with a solid volume reduction, that can then undergo collapse. We report results from hydrostatic compaction experiments on porous bassanite (CaSO4.0.5H2O) aggregates. Gypsum (CaSO4.2H2O) is first dehydrated under low effective pressure, 4 MPa, to produce a bassanite aggregate with a porosity of 27%. Compaction is induced by increasing confining pressure at rates from 0.001 MPa/s to 0.02 MPa/s while the sample is maintained at a temperature of 115°C. At slow compaction rates, porosity collapse proceeds smoothly. At higher compaction rates, sudden increases in the pore-fluid pressure occur with a magnitude of 5 MPa. Microstructural investigations using X-ray microtomography and SEM observations show that randomly oriented localized compaction features occur in all samples, where the bulk porosity of 18% outside the band is reduced to 5% inside the band. Previous work on deformation bands has suggested that localized compactive features only form under an elevated differential stress and not under a hydrostatic stress state. The magnitude of the pore-pressure pulses can be explained by the formation of compaction bands. The results indicate that the compaction bands can form by rapid (unstable) propagation across the sample above a critical strain rate, or quasi-statically at low compaction rates without pore-fluid pressure bursts. The absence of pore-fluid pressure bursts at slow compaction rates can be explained by viscous deformation of the bassanite aggregate around the tip of a propagating compaction band, relaxing stress, and promoting stable propagation. Conversely, at higher compaction rates, viscous deformation cannot relax the stress sufficiently and unstable, brittle propagation occurs. In nature, this type of compaction behaviour might result in a mechanism to produce pulses of pore pressure within porous rocks which might have a significant effect on the deformation behaviour at depth.

Laser-driven electron beam acceleration and future application to compact light sources

NASA Astrophysics Data System (ADS)

Hafz, N.; Jeong, T. M.; Lee, S. K.; Pae, K. H.; Sung, J. H.; Choi, I. W.; Yu, T. J.; Jeong, Y. U.; Lee, J.

2009-07-01

Laser-driven plasma accelerators are gaining much attention by the advanced accelerator community due to the potential these accelerators hold in miniaturizing future high-energy and medium-energy machines. In the laser wakefield accelerator (LWFA), the ponderomotive force of an ultrashort high intensity laser pulse excites a longitudinal plasma wave or bubble. Due to huge charge separation, electric fields created in the plasma bubble can be several orders of magnitude higher than those available in conventional microwave and RF-based accelerator facilities which are limited (up to ˜100 MV/m) by material breakdown. Therefore, if an electron bunch is injected into the bubble in phase with its field, it will gain relativistic energies within an extremely short distance. Here, in the LWFA we show the generation of high-quality and high-energy electron beams up to the GeV-class within a few millimeters of gas-jet plasmas irradiated by tens of terawatt ultrashort laser pulses. Thus we realize approximately four orders of magnitude acceleration gradients higher than available by conventional technology. As a practical application of the stable high-energy electron beam generation, we are planning on injecting the electron beams into a few-meters long conventional undulator in order to realize compact X-ray synchrotron (immediate) and FEL (future) light sources. Stable laser-driven electron beam and radiation devices will surely open a new era in science, medicine and technology and will benefit a larger number of users in those fields.

Development of Compact Electron Cyclotron Resonance Ion Source with Permanent Magnets for High-Energy Carbon-Ion Therapy

NASA Astrophysics Data System (ADS)

Muramatsu, M.; Kitagawa, A.; Iwata, Y.; Hojo, S.; Sakamoto, Y.; Sato, S.; Ogawa, Hirotsugu; Yamada, S.; Ogawa, Hiroyuki; Yoshida, Y.; Ueda, T.; Miyazaki, H.; Drentje, A. G.

2008-11-01

Heavy-ion cancer treatment is being carried out at the Heavy Ion Medical Accelerator in Chiba (HIMAC) with 140 to 400 MeV/n carbon ions at National Institute of Radiological Sciences (NIRS) since 1994. At NIRS, more than 4,000 patients have been treated, and the clinical efficiency of carbon ion radiotherapy has been demonstrated for many diseases. A more compact accelerator facility for cancer therapy is now being constricted at the Gunma University. In order to reduce the size of the injector (consists of ion source, low-energy beam transport and post-accelerator Linac include these power supply and cooling system), an ion source requires production of highly charged carbon ions, lower electric power for easy installation of the source on a high-voltage platform, long lifetime and easy operation. A compact Electron Cyclotron Resonance Ion Source (ECRIS) with all permanent magnets is one of the best types for this purpose. An ECRIS has advantage for production of highly charged ions. A permanent magnet is suitable for reduce the electric power and cooling system. For this, a 10 GHz compact ECRIS with all permanent magnets (Kei2-source) was developed. The maximum mirror magnetic fields on the beam axis are 0.59 T at the extraction side and 0.87 T at the gas-injection side, while the minimum B strength is 0.25 T. These parameters have been optimized for the production of C4+ based on experience at the 10 GHz NIRS-ECR ion source. The Kei2-source has a diameter of 320 mm and a length of 295 mm. The beam intensity of C4+ was obtained to be 618 eμA under an extraction voltage of 30 kV. Outline of the heavy ion therapy and development of the compact ion source for new facility are described in this paper.

BEAM DYNAMICS STUDIES FOR A COMPACT CARBON ION LINAC FOR THERAPY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plastun, A.; Mustapha, B.; Nassiri, A.

2016-05-01

Feasibility of an Advanced Compact Carbon Ion Linac (ACCIL) for hadron therapy is being studied at Argonne National Laboratory in collaboration with RadiaBeam Technologies. The 45-meter long linac is designed to deliver 109 carbon ions per second with variable energy from 45 MeV/u to 450 MeV/u. S-band structure provides the acceleration in this range. The carbon beam energy can be adjusted from pulse to pulse, making 3D tumor scanning straightforward and fast. Front end accelerating structures such as RFQ, DTL and coupled DTL are designed to operate at lower frequencies. The design of the linac was accompanied with extensive end-to-endmore » beam dynamics studies which are presented in this paper.« less

Uniformly accelerated black holes

NASA Astrophysics Data System (ADS)

Letelier, Patricio S.; Oliveira, Samuel R.

2001-09-01

The static and stationary C metric are examined in a generic framework and their interpretations studied in some detail, especially those with two event horizons, one for the black hole and another for the acceleration. We find that (i) the spacetime of an accelerated static black hole is plagued by either conical singularities or a lack of smoothness and compactness of the black hole horizon, (ii) by using standard black hole thermodynamics we show that accelerated black holes have a higher Hawking temperature than Unruh temperature of the accelerated frame, and (iii) the usual upper bound on the product of the mass and acceleration parameters (<1/27) is just a coordinate artifact. The main results are extended to accelerated rotating black holes with no significant changes.

Development and application of compact and on-chip electron linear accelerators for dynamic tracking cancer therapy and DNA damage/repair analysis

NASA Astrophysics Data System (ADS)

Uesaka, M.; Demachi, K.; Fujiwara, T.; Dobashi, K.; Fujisawa, H.; Chhatkuli, R. B.; Tsuda, A.; Tanaka, S.; Matsumura, Y.; Otsuki, S.; Kusano, J.; Yamamoto, M.; Nakamura, N.; Tanabe, E.; Koyama, K.; Yoshida, M.; Fujimori, R.; Yasui, A.

2015-06-01

We are developing compact electron linear accelerators (hereafter linac) with high RF (Radio Frequency) frequency (9.3 GHz, wavelength 32.3 mm) of X-band and applying to medicine and non-destructive testing. Especially, potable 950 keV and 3.95 MeV linac X-ray sources have been developed for on-site transmission testing at several industrial plants and civil infrastructures including bridges. 6 MeV linac have been made for pinpoint X-ray dynamic tracking cancer therapy. The length of the accelerating tube is ∼600 mm. The electron beam size at the X-ray target is less than 1 mm and X-ray spot size at the cancer is less than 3 mm. Several hardware and software are under construction for dynamic tracking therapy for moving lung cancer. Moreover, as an ultimate compact linac, we are designing and manufacturing a laser dielectric linac of ∼1 MeV with Yr fiber laser (283 THz, wavelength 1.06 pm). Since the wavelength is 1.06 μm, the length of one accelerating strcture is tens pm and the electron beam size is in sub-micro meter. Since the sizes of cell and nuclear are about 10 and 1 μm, respectively, we plan to use this “On-chip” linac for radiation-induced DNA damage/repair analysis. We are thinking a system where DNA in a nucleus of cell is hit by ∼1 μm electron or X-ray beam and observe its repair by proteins and enzymes in live cells in-situ.

The Effect of Compaction Force on the Transition to Hydrate of Anhydrous Aripiprazole.

PubMed

Togo, Taichiro; Taniguchi, Toshiya; Nakata, Yoshitaka

2018-01-01

Aripiprazole (APZ) is used to treat schizophrenia and is administered as a tablet containing the anhydrous form of APZ. In this study, the effect of compaction force on the crystal form transition was investigated. The crystalline state was observed by X-ray diffraction (XRD). APZ Anhydrous Form II was compacted into tablets. The XRD intensity of anhydrous APZ became lower with higher compressive force. The degree of crystallinity decreased with the compaction force. The powder and the compacted tablets of anhydrous APZ were stored for one week under 60°C and 75% relative humidity. The powder showed no crystal form transition after storage. For the tablets, however, XRD peaks of APZ hydrate were observed after storage. The tablets compacted with higher force showed the higher XRD diffraction intensity of hydrate form. We concluded that the crystallinity reduction of APZ Anhydrous Form II by compaction caused and accelerated the transition to hydrate under high temperature and humidity conditions. In order to manufacture crystallographically stable tablets containing anhydrous APZ, it is important to prevent this crystallinity reduction during compaction.

Compact beam transport system for free-electron lasers driven by a laser plasma accelerator

DOE PAGES

Liu, Tao; Zhang, Tong; Wang, Dong; ...

2017-02-01

Utilizing laser-driven plasma accelerators (LPAs) as a high-quality electron beam source is a promising approach to significantly downsize the x-ray free-electron laser (XFEL) facility. A multi-GeV LPA beam can be generated in several-centimeter acceleration distance, with a high peak current and a low transverse emittance, which will considerably benefit a compact FEL design. However, the large initial angular divergence and energy spread make it challenging to transport the beam and realize FEL radiation. In this paper, a novel design of beam transport system is proposed to maintain the superior features of the LPA beam and a transverse gradient undulator (TGU)more » is also adopted as an effective energy spread compensator to generate high-brilliance FEL radiation. As a result, theoretical analysis and numerical simulations are presented based on a demonstration experiment with an electron energy of 380 MeV and a radiation wavelength of 30 nm.« less

The GALAXIE all-optical FEL project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenzweig, J. B.; Arab, E.; Andonian, G.

2012-12-21

We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 {mu}m laser development, ultra-highmore » brightness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.« less

Design of a low-cost, compact SRF accelerator for flue gas and wastewater treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciovati, Gianluigi

2016-04-01

Funding is being requested pursuant to a proposal that was submitted and reviewed through the Portfolio Analysis and Management System (PAMS). PAMS Proposal ID: 222439. The proposed project consists of the design of a novel superconducting continuous-wave accelerator capable of providing a beam current of ~1 A at an energy of 1-2 MeV for the treatment of flue gases and wastewater streams. The novel approach consists on studying the feasibility of using a single-cell Nb cavity coated with a thin Nb3Sn layer of the inner surface and conductively cooled by to 4.2 K by cryocoolers inside a compact cryomodule. Themore » proposed study will include beam transport simulations, thermal and mechanical engineering analysis of the cryomodule and a cost analysis for both the fabrications costs and the operational and maintenance costs of such accelerator. The outcome of the project will be a report summarizing the analysis and results from the design study.« less

LATTICES FOR HIGH-POWER PROTON BEAM ACCELERATION AND SECONDARY BEAM COLLECTION AND COOLING.

DOE Office of Scientific and Technical Information (OSTI.GOV)

WANG, S.; WEI, J.; BROWN, K.

2006-06-23

Rapid cycling synchrotrons are used to accelerate high-intensity proton beams to energies of tens of GeV for secondary beam production. After primary beam collision with a target, the secondary beam can be collected, cooled, accelerated or decelerated by ancillary synchrotrons for various applications. In this paper, we first present a lattice for the main synchrotron. This lattice has: (a) flexible momentum compaction to avoid transition and to facilitate RF gymnastics (b) long straight sections for low-loss injection, extraction, and high-efficiency collimation (c) dispersion-free straights to avoid longitudinal-transverse coupling, and (d) momentum cleaning at locations of large dispersion with missing dipoles.more » Then, we present a lattice for a cooler ring for the secondary beam. The momentum compaction across half of this ring is near zero, while for the other half it is normal. Thus, bad mixing is minimized while good mixing is maintained for stochastic beam cooling.« less

The compact AMS facility at Guangzhou Institute of Geochemistry, Chinese Academy of Sciences

NASA Astrophysics Data System (ADS)

Zhu, Sanyuan; Ding, Ping; Wang, Ning; Shen, Chengde; Jia, Guodong; Zhang, Gan

2015-10-01

A compact 14C AMS facility manufactured by the National Electrostatics Corporation (NEC) has been installed at Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS). The system is based on a Model 1.5SDH-1 Pelletron accelerator with a maximum terminal volt 0.6 MV. This paper reports the performance and the operation of this machine in the first several months after installation.

Accurate modeling of the hose instability in plasma wakefield accelerators

NASA Astrophysics Data System (ADS)

Mehrling, T. J.; Benedetti, C.; Schroeder, C. B.; Martinez de la Ossa, A.; Osterhoff, J.; Esarey, E.; Leemans, W. P.

2018-05-01

Hosing is a major challenge for the applicability of plasma wakefield accelerators and its modeling is therefore of fundamental importance to facilitate future stable and compact plasma-based particle accelerators. In this contribution, we present a new model for the evolution of the plasma centroid, which enables the accurate investigation of the hose instability in the nonlinear blowout regime. It paves the road for more precise and comprehensive studies of hosing, e.g., with drive and witness beams, which were not possible with previous models.

Overview of Accelerators with Potential Use in Homeland Security

NASA Astrophysics Data System (ADS)

Garnett, Robert W.

Quite a broad range of accelerators have been applied to solving many of the challenging problems related to homeland security and defense. These accelerator systems range from relatively small, simple, and compact, to large and complex, based on the specific application requirements. They have been used or proposed as sources of primary and secondary probe beams for applications such as radiography and to induce specific reactions that are key signatures for detecting conventional explosives or fissile material. A brief overview and description of these accelerator systems, their specifications, and application will be presented. Some recent technology trends will also be discussed.

Maximum proton kinetic energy and patient-generated neutron fluence considerations in proton beam arc delivery radiation therapy.

PubMed

Sengbusch, E; Pérez-Andújar, A; DeLuca, P M; Mackie, T R

2009-02-01

Several compact proton accelerator systems for use in proton therapy have recently been proposed. Of paramount importance to the development of such an accelerator system is the maximum kinetic energy of protons, immediately prior to entry into the patient, that must be reached by the treatment system. The commonly used value for the maximum kinetic energy required for a medical proton accelerator is 250 MeV, but it has not been demonstrated that this energy is indeed necessary to treat all or most patients eligible for proton therapy. This article quantifies the maximum kinetic energy of protons, immediately prior to entry into the patient, necessary to treat a given percentage of patients with rotational proton therapy, and examines the impact of this energy threshold on the cost and feasibility of a compact, gantry-mounted proton accelerator treatment system. One hundred randomized treatment plans from patients treated with IMRT were analyzed. The maximum radiological pathlength from the surface of the patient to the distal edge of the treatment volume was obtained for 180 degrees continuous arc proton therapy and for 180 degrees split arc proton therapy (two 90 degrees arcs) using CT# profiles from the Pinnacle (Philips Medical Systems, Madison, WI) treatment planning system. In each case, the maximum kinetic energy of protons, immediately prior to entry into the patient, that would be necessary to treat the patient was calculated using proton range tables for various media. In addition, Monte Carlo simulations were performed to quantify neutron production in a water phantom representing a patient as a function of the maximum proton kinetic energy achievable by a proton treatment system. Protons with a kinetic energy of 240 MeV, immediately prior to entry into the patient, were needed to treat 100% of patients in this study. However, it was shown that 90% of patients could be treated at 198 MeV, and 95% of patients could be treated at 207 MeV. Decreasing the proton kinetic energy from 250 to 200 MeV decreases the total neutron energy fluence produced by stopping a monoenergetic pencil beam in a water phantom by a factor of 2.3. It is possible to significantly lower the requirements on the maximum kinetic energy of a compact proton accelerator if the ability to treat a small percentage of patients with rotational therapy is sacrificed. This decrease in maximum kinetic energy, along with the corresponding decrease in neutron production, could lower the cost and ease the engineering constraints on a compact proton accelerator treatment facility.

Self-shielded electron linear accelerators designed for radiation technologies

NASA Astrophysics Data System (ADS)

Belugin, V. M.; Rozanov, N. E.; Pirozhenko, V. M.

2009-09-01

This paper describes self-shielded high-intensity electron linear accelerators designed for radiation technologies. The specific property of the accelerators is that they do not apply an external magnetic field; acceleration and focusing of electron beams are performed by radio-frequency fields in the accelerating structures. The main characteristics of the accelerators are high current and beam power, but also reliable operation and a long service life. To obtain these characteristics, a number of problems have been solved, including a particular optimization of the accelerator components and the application of a variety of specific means. The paper describes features of the electron beam dynamics, accelerating structure, and radio-frequency power supply. Several compact self-shielded accelerators for radiation sterilization and x-ray cargo inspection have been created. The introduced methods made it possible to obtain a high intensity of the electron beam and good performance of the accelerators.

Adjusting the Ion Permeability of Polyelectrolyte Multilayers through Layer-by-Layer Assembly under a High Gravity Field.

PubMed

Jiang, Chao; Luo, Caijun; Liu, Xiaolin; Shao, Lei; Dong, Youqing; Zhang, Yingwei; Shi, Feng

2015-05-27

The layer-by-layer (LbL) assembled multilayer has been widely used as good barrier film or capsule due to the advantages of its flexible tailoring of film permeability and compactness. Although many specific systems have been proposed for film design, developing a versatile strategy to control film compactness remains a challenge. We introduced the simple mechanical energy of a high gravity field to the LbL assembly process to tailor the multilayer permeability through adjusting film compactness. By taking poly(diallyldimethylammonium chloride) (PDDA) and poly{1-4[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl sodium salt} (PAzo) as a model system, we investigated the LbL assembly process under a high gravity field. The results showed that the high gravity field introduced effectively accelerated the multilayer deposition process by 20-fold compared with conventional dipping assembly; the adsorption rate was positively dependent on the rotating speed of the high gravity equipment and the concentration of the building block solutions. More interestingly, the film compactness of the PDDA/PAzo multilayer prepared under the high gravity field increased remarkably with the growing rotational speed of the high gravity equipment, as demonstrated through comparisons of surface morphology, cyclic voltammetry curves, and photoisomerization kinetics of PDDA/PAzo multilayers fabricated through the conventional dipping method and through LbL assembly under a high gravity field, respectively. In this way, we have introduced a simple and versatile external form of mechanical energy into the LbL assembling process to improve film compactness, which should be useful for further applications in controlled ion permeability, anticorrosion, and drug loading.

Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions.

PubMed

Straume, T; Braby, L A; Borak, T B; Lusby, T; Warner, D W; Perez-Nunez, D

2015-10-01

Effects on human health from the complex radiation environment in deep space have not been measured and can only be simulated here on Earth using experimental systems and beams of radiations produced by accelerators, usually one beam at a time. This makes it particularly important to develop instruments that can be used on deep-space missions to measure quantities that are known to be relatable to the biological effectiveness of space radiation. Tissue-equivalent proportional counters (TEPCs) are such instruments. Unfortunately, present TEPCs are too large and power intensive to be used beyond low Earth orbit (LEO). Here, the authors describe a prototype of a compact TEPC designed for deep space applications with the capability to detect both ambient galactic cosmic rays and intense solar particle event radiation. The device employs an approach that permits real-time determination of yD (and thus quality factor) using a single detector. This was accomplished by assigning sequential sampling intervals as detectors “1” and “2” and requiring the intervals to be brief compared to the change in dose rate. Tests with g rays show that the prototype instrument maintains linear response over the wide dose-rate range expected in space with an accuracy of better than 5% for dose rates above 3 mGy h(-1). Measurements of yD for 200 MeV n(-1) carbon ions were better than 10%. Limited tests with fission spectrum neutrons show absorbed dose-rate accuracy better than 15%.

Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions

PubMed Central

Straume, T.; Braby, L.A.; Borak, T.B.; Lusby, T.; Warner, D.W.; Perez-Nunez, D.

2015-01-01

Abstract Effects on human health from the complex radiation environment in deep space have not been measured and can only be simulated here on Earth using experimental systems and beams of radiations produced by accelerators, usually one beam at a time. This makes it particularly important to develop instruments that can be used on deep-space missions to measure quantities that are known to be relatable to the biological effectiveness of space radiation. Tissue-equivalent proportional counters (TEPCs) are such instruments. Unfortunately, present TEPCs are too large and power intensive to be used beyond low Earth orbit (LEO). Here, the authors describe a prototype of a compact TEPC designed for deep space applications with the capability to detect both ambient galactic cosmic rays and intense solar particle event radiation. The device employs an approach that permits real-time determination of (and thus quality factor) using a single detector. This was accomplished by assigning sequential sampling intervals as detectors “1” and “2” and requiring the intervals to be brief compared to the change in dose rate. Tests with γ rays show that the prototype instrument maintains linear response over the wide dose-rate range expected in space with an accuracy of better than 5% for dose rates above 3 mGy h−1. Measurements of for 200 MeV n−1 carbon ions were better than 10%. Limited tests with fission spectrum neutrons show absorbed dose-rate accuracy better than 15%. PMID:26313585

Radiography with cosmic-ray and compact accelerator muons; Exploring inner-structure of large-scale objects and landforms

PubMed Central

NAGAMINE, Kanetada

2016-01-01

Cosmic-ray muons (CRM) arriving from the sky on the surface of the earth are now known to be used as radiography purposes to explore the inner-structure of large-scale objects and landforms, ranging in thickness from meter to kilometers scale, such as volcanic mountains, blast furnaces, nuclear reactors etc. At the same time, by using muons produced by compact accelerators (CAM), advanced radiography can be realized for objects with a thickness in the sub-millimeter to meter range, with additional exploration capability such as element identification and bio-chemical analysis. In the present report, principles, methods and specific research examples of CRM transmission radiography are summarized after which, principles, methods and perspective views of the future CAM radiography are described. PMID:27725469

Radiography with cosmic-ray and compact accelerator muons; Exploring inner-structure of large-scale objects and landforms.

PubMed

Nagamine, Kanetada

2016-01-01

Cosmic-ray muons (CRM) arriving from the sky on the surface of the earth are now known to be used as radiography purposes to explore the inner-structure of large-scale objects and landforms, ranging in thickness from meter to kilometers scale, such as volcanic mountains, blast furnaces, nuclear reactors etc. At the same time, by using muons produced by compact accelerators (CAM), advanced radiography can be realized for objects with a thickness in the sub-millimeter to meter range, with additional exploration capability such as element identification and bio-chemical analysis. In the present report, principles, methods and specific research examples of CRM transmission radiography are summarized after which, principles, methods and perspective views of the future CAM radiography are described.

Collective Deceleration: Toward a Compact Beam Dump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, H.-C.; /Munich, Max Planck Inst. Quantenopt.; Tajima, T.

With the increasing development of laser accelerators, the electron energy is already beyond GeV and even higher in near future. Conventional beam dump based on ionization or radiation loss mechanism is cumbersome and costly, also has radiological hazards. We revisit the stopping power of high-energy charged particles in matter and discuss the associated problem of beam dump from the point of view of collective deceleration. The collective stopping length in an ionized gas can be several orders of magnitude shorter than the Bethe-Bloch and multiple electromagnetic cascades stopping length in solid. At the mean time, the tenuous density of themore » gas makes the radioactivation negligible. Such a compact and non-radioactivating beam dump works well for short and dense bunches, which is typically generated from laser wakefield accelerator.« less

Narrow bandwidth Laser-Plasma Accelerator driven Thomson photon source development

NASA Astrophysics Data System (ADS)

Geddes, C. G. R.; Tsai, H.-E.; Otero, G.; Liu, X.; van Tilborg, J.; Toth, Cs.; Vay, J.-L.; Lehe, R.; Schroeder, C. B.; Esarey, E.; Friedman, A.; Grote, D. P.; Leemans, W. P.

2017-10-01

Compact, high-quality photon sources at MeV energies can be provided by Thomson scattering of a laser from the electron beam of a Laser-Plasma Accelerator (LPA). Recent experiments and simulations demonstrate controllable LPAs in the energy range appropriate to MeV sources. Simulations indicate that high flux with narrow energy spread can be achieved via control of the scattering laser pulse shape and laser guiding, and that undesired background bremsstrahlung can be mitigated by plasma based deceleration of the electron beam after photon production. Construction of experiments and laser capabilities to combine these elements will be presented, along with initial operations, towards a compact photon source system. Work supported by US DOE NNSA DNN R&D and by Sc. HEP under contract DE-AC02-05CH11231.

High brightness electron accelerator

DOEpatents

Sheffield, Richard L.; Carlsten, Bruce E.; Young, Lloyd M.

1994-01-01

A compact high brightness linear accelerator is provided for use, e.g., in a free electron laser. The accelerator has a first plurality of acclerating cavities having end walls with four coupling slots for accelerating electrons to high velocities in the absence of quadrupole fields. A second plurality of cavities receives the high velocity electrons for further acceleration, where each of the second cavities has end walls with two coupling slots for acceleration in the absence of dipole fields. The accelerator also includes a first cavity with an extended length to provide for phase matching the electron beam along the accelerating cavities. A solenoid is provided about the photocathode that emits the electons, where the solenoid is configured to provide a substantially uniform magnetic field over the photocathode surface to minimize emittance of the electons as the electrons enter the first cavity.

Frictional stability and earthquake triggering during fluid pressure stimulation of an experimental fault

NASA Astrophysics Data System (ADS)

Scuderi, M. M.; Collettini, C.; Marone, C.

2017-11-01

It is widely recognized that the significant increase of M > 3.0 earthquakes in Western Canada and the Central United States is related to underground fluid injection. Following injection, fluid overpressure lubricates the fault and reduces the effective normal stress that holds the fault in place, promoting slip. Although, this basic physical mechanism for earthquake triggering and fault slip is well understood, there are many open questions related to induced seismicity. Models of earthquake nucleation based on rate- and state-friction predict that fluid overpressure should stabilize fault slip rather than trigger earthquakes. To address this controversy, we conducted laboratory creep experiments to monitor fault slip evolution at constant shear stress while the effective normal stress was systematically reduced via increasing fluid pressure. We sheared layers of carbonate-bearing fault gouge in a double direct shear configuration within a true-triaxial pressure vessel. We show that fault slip evolution is controlled by the stress state acting on the fault and that fluid pressurization can trigger dynamic instability even in cases of rate strengthening friction, which should favor aseismic creep. During fluid pressurization, when shear and effective normal stresses reach the failure condition, accelerated creep occurs in association with fault dilation; further pressurization leads to an exponential acceleration with fault compaction and slip localization. Our work indicates that fault weakening induced by fluid pressurization can overcome rate strengthening friction resulting in fast acceleration and earthquake slip. Our work points to modifications of the standard model for earthquake nucleation to account for the effect of fluid overpressure and to accurately predict the seismic risk associated with fluid injection.

Surface disturbances: their role in accelerating desertification

USGS Publications Warehouse

Belnap, Jayne

1995-01-01

Maintaining soil stability and normal water and nutrient cycles in desert systems is critical to avoiding desertification. These particular ecosystem processes are threatened by trampling of livestock and people, and by off-road vehicle use. Soil compaction and disruption of cryptobiotic soil surfaces (composed of cyanobacteria, lichens, and mosses) can result in decreased water availability to vascular plants through decreased water infiltration and increased albedo with possible decreased precipitation. Surface disturbance may also cause accelerated soil loss through wind and water erosion and decreased diversity and abundance of soil biota. In addition, nutrient cycles can be altered through lowered nitrogen and carbon inputs and slowed decomposition of soil organic matter, resulting in lower nutrient levels in associated vascular plants. Some cold desert systems may be especially susceptible to these disruptions due to the paucity of surface-rooting vascular plants for soil stabilization, fewer nitrogen-fixing higher plants, and lower soil temperatures, which slow nutrient cycles. Desert soils may recover slowly from surface disturbances, resulting in increased vulnerability to desertification. Recovery from compaction and decreased soil stability is estimated to take several hundred years. Re-establishment rates for soil bacterial and fungal populations are not known. The nitrogen fixation capability of soil requires at least 50 years to recover. Recovery of crusts can be hampered by large amounts of moving sediment, and re-establishment can be extremely difficult in some areas. Given the sensitivity of these resources and slow recovery times, desertification threatens million of hectares of semiarid lands in the United States.

Monte Carlo simulation of a compact microbeam radiotherapy system based on carbon nanotube field emission technology.

PubMed

Schreiber, Eric C; Chang, Sha X

2012-08-01

Microbeam radiation therapy (MRT) is an experimental radiotherapy technique that has shown potent antitumor effects with minimal damage to normal tissue in animal studies. This unique form of radiation is currently only produced in a few large synchrotron accelerator research facilities in the world. To promote widespread translational research on this promising treatment technology we have proposed and are in the initial development stages of a compact MRT system that is based on carbon nanotube field emission x-ray technology. We report on a Monte Carlo based feasibility study of the compact MRT system design. Monte Carlo calculations were performed using EGSnrc-based codes. The proposed small animal research MRT device design includes carbon nanotube cathodes shaped to match the corresponding MRT collimator apertures, a common reflection anode with filter, and a MRT collimator. Each collimator aperture is sized to deliver a beam width ranging from 30 to 200 μm at 18.6 cm source-to-axis distance. Design parameters studied with Monte Carlo include electron energy, cathode design, anode angle, filtration, and collimator design. Calculations were performed for single and multibeam configurations. Increasing the energy from 100 kVp to 160 kVp increased the photon fluence through the collimator by a factor of 1.7. Both energies produced a largely uniform fluence along the long dimension of the microbeam, with 5% decreases in intensity near the edges. The isocentric dose rate for 160 kVp was calculated to be 700 Gy∕min∕A in the center of a 3 cm diameter target. Scatter contributions resulting from collimator size were found to produce only small (<7%) changes in the dose rate for field widths greater than 50 μm. Dose vs depth was weakly dependent on filtration material. The peak-to-valley ratio varied from 10 to 100 as the separation between adjacent microbeams varies from 150 to 1000 μm. Monte Carlo simulations demonstrate that the proposed compact MRT system design is capable of delivering a sufficient dose rate and peak-to-valley ratio for small animal MRT studies.

Interaction dynamics of high Reynolds number magnetized plasma flow on the CTIX plasma accelerator

NASA Astrophysics Data System (ADS)

Howard, Stephen James

The Compact Toroid Injection eXperiment, (CTIX), is a coaxial railgun that forms and accelerates magnetized plasma rings called compact toroids (CT's). CTIX consists of a pair of cylindrical coaxial electrodes with the region between them kept at high vacuum (2 m long, 15 cm outer diameter). Hydrogen is typically the dominant constituent of the CT plasma, however helium can also be used. The railgun effect that accelerates the CT can be accounted for by the Lorentz j x B force density created by the power input from a capacitor bank of roughly a Giga-Watt peak. The final velocity of the CT can be as high as 300 km/s, with an acceleration of about 3 billion times Earth's gravity. The compact toroid is able to withstand these forces because of a large internal magnetic field of about 1 Tesla. Understanding the nature of high speed flow of a magnetized plasma has been the primary challenge of this work. In this dissertation we will explore a sequence of fundamental questions regarding the plasma physics of CTIX. First we will go over some new results about the structure and dynamics of the compact toroid's magnetic field, and its electrical resistivity. Then we will present the results from a sequence of key experiments involving reconnection/compression and thermalization of the plasma during interaction of the CT with target magnetic fields of various geometries. Next, we look at the Doppler shift of a spectral line of the He II ion as a measurement of plasma velocity, and to gain insight into the ionization physics of helium in our plasma. These preliminary experiments provide the background for our primary experimental tool for investigating turbulence, a technique called Gas Puff Imaging (GPI) in which a cloud of helium can be used to enhance plasma brightness, allowing plasma density fluctuations to be imaged. We will conclude with an analysis of the images that show coherent density waves, as well as the transition to turbulence during the interaction with a wire target perturbation.

Current subsidence rates due to compaction of Holocene sediments in southern Louisiana

USGS Publications Warehouse

Meckel, T.A.; ten Brink, Uri S.; Williams, S.J.

2006-01-01

Relative contributions of geologic and anthropogenic processes to subsidence of southern Louisiana are vigorously debated. Of these, shallow sediment compaction is often considered dominant, although this has never been directly observed or effectively demonstrated. Quantitative understanding of subsidence is important for predicting relative sea level rise, storm surge flooding due to hurricanes, and for successful wetland restoration. Despite many shallow borings, few appropriate stratigraphic and geotechnical data are available for site-specific calculations. We overcome this by determining present compaction rates from Monte Carlo simulations of the incremental sedimentation and compaction of stratigraphies typical of the Holocene of southern Louisiana. This approach generates distributions of present compaction rates that are not expected to exceed 5 mm/yr, but may locally. Locations with present subsidence rates greater than the predicted maximum probable shallow compaction rates are likely influenced by additional processes.

Overview of accelerators with potential use in homeland security

DOE PAGES

Garnett, Robert W.

2015-06-18

Quite a broad range of accelerators have been applied to solving many of the challenging problems related to homeland security and defense. These accelerator systems range from relatively small, simple, and compact, to large and complex, based on the specific application requirements. They have been used or proposed as sources of primary and secondary probe beams for applications such as radiography and to induce specific reactions that are key signatures for detecting conventional explosives or fissile material. A brief overview and description of these accelerator systems, their specifications, and application will be presented. Some recent technology trends will also bemore » discussed.« less

Ultra-High Gradient S-band Linac for Laboratory and Industrial Applications

NASA Astrophysics Data System (ADS)

Faillace, L.; Agustsson, R.; Dolgashev, V.; Frigola, P.; Murokh, A.; Rosenzweig, J.; Yakimenko, V.

2010-11-01

A strong demand for high gradient structures arises from the limited real estate available for linear accelerators. RadiaBeam Technologies is developing a Doubled Energy Compact Accelerator (DECA) structure: an S-band standing wave electron linac designed to operate at accelerating gradients of up to 50 MV/m. In this paper, we present the radio-frequency design of the DECA S-band accelerating structure, operating at 2.856 GHz in the π-mode. The structure design is heavily influenced by NLC collaboration experience with ultra high gradient X-band structures; S-band, however, is chosen to take advantage of commonly available high power S-band klystrons.

Antarctic Firn Compaction Rates from Repeat-Track Airborne Radar Data: I. Methods

NASA Technical Reports Server (NTRS)

Medley, B.; Ligtenberg, S. R. M.; Joughin, I.; Van Den Broeke, M. R.; Gogineni, S.; Nowicki, S.

2015-01-01

While measurements of ice-sheet surface elevation change are increasingly used to assess mass change, the processes that control the elevation fluctuations not related to ice-flow dynamics (e.g. firn compaction and accumulation) remain difficult to measure. Here we use radar data from the Thwaites Glacier (West Antarctica) catchment to measure the rate of thickness change between horizons of constant age over different time intervals: 2009-10, 2010-11 and 2009-11. The average compaction rate to approximately 25m depth is 0.33ma(exp -1), with largest compaction rates near the surface. Our measurements indicate that the accumulation rate controls much of the spatio-temporal variations in the compaction rate while the role of temperature is unclear due to a lack of measurements. Based on a semi-empirical, steady-state densification model, we find that surveying older firn horizons minimizes the potential bias resulting from the variable depth of the constant age horizon. Our results suggest that the spatiotemporal variations in the firn compaction rate are an important consideration when converting surface elevation change to ice mass change. Compaction rates varied by up to 0.12ma(exp -1) over distances less than 6km and were on average greater than 20% larger during the 2010-11 interval than during 2009-10.

Small Accelerators for the Next Generation of BNCT Irradiation Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kobayashi, T.; Tanaka, K.; Bengua, G.

2005-01-15

The neutron irradiation system for boron neutron capture therapy (BNCT) using compact accelerators installed at hospitals was mainly investigated for the usage of direct neutrons from near-threshold {sup 7}Li(p,n){sup 7}Be, and moderated neutrons from 2.5 MeV {sup 7}Li(p,n){sup 7}Be reactions and other reactions. This kind of system can supply the medical doctors and patients with convenience to carry out BNCT in hospitals. The accelerator system would be regarded as the next-generation of BNCT in the near future.

Accurate modeling of the hose instability in plasma wakefield accelerators

DOE PAGES

Mehrling, T. J.; Benedetti, C.; Schroeder, C. B.; ...

2018-05-20

Hosing is a major challenge for the applicability of plasma wakefield accelerators and its modeling is therefore of fundamental importance to facilitate future stable and compact plasma-based particle accelerators. In this contribution, we present a new model for the evolution of the plasma centroid, which enables the accurate investigation of the hose instability in the nonlinear blowout regime. Lastly, it paves the road for more precise and comprehensive studies of hosing, e.g., with drive and witness beams, which were not possible with previous models.

Accurate modeling of the hose instability in plasma wakefield accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehrling, T. J.; Benedetti, C.; Schroeder, C. B.

Hosing is a major challenge for the applicability of plasma wakefield accelerators and its modeling is therefore of fundamental importance to facilitate future stable and compact plasma-based particle accelerators. In this contribution, we present a new model for the evolution of the plasma centroid, which enables the accurate investigation of the hose instability in the nonlinear blowout regime. Lastly, it paves the road for more precise and comprehensive studies of hosing, e.g., with drive and witness beams, which were not possible with previous models.

High Luminosity LHC: challenges and plans

NASA Astrophysics Data System (ADS)

Arduini, G.; Barranco, J.; Bertarelli, A.; Biancacci, N.; Bruce, R.; Brüning, O.; Buffat, X.; Cai, Y.; Carver, L. R.; Fartoukh, S.; Giovannozzi, M.; Iadarola, G.; Li, K.; Lechner, A.; Medina Medrano, L.; Métral, E.; Nosochkov, Y.; Papaphilippou, Y.; Pellegrini, D.; Pieloni, T.; Qiang, J.; Redaelli, S.; Romano, A.; Rossi, L.; Rumolo, G.; Salvant, B.; Schenk, M.; Tambasco, C.; Tomás, R.; Valishev, S.; Van der Veken, F. F.

2016-12-01

The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will undergo a major upgrade in the 2020s. This will increase its rate of collisions by a factor of five beyond the original design value and the integrated luminosity by a factor ten. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11-12 T superconducting magnets, including Nb3Sn-based magnets never used in accelerators before, compact superconducting cavities for longitudinal beam rotation, new technology and physical processes for beam collimation. The dynamics of the HL-LHC beams will be also particularly challenging and this aspect is the main focus of this paper.

Design, fabrication, and high-gradient testing of an X -band, traveling-wave accelerating structure milled from copper halves

NASA Astrophysics Data System (ADS)

Argyropoulos, Theodoros; Catalan-Lasheras, Nuria; Grudiev, Alexej; Mcmonagle, Gerard; Rodriguez-Castro, Enrique; Syrachev, Igor; Wegner, Rolf; Woolley, Ben; Wuensch, Walter; Zha, Hao; Dolgashev, Valery; Bowden, Gorden; Haase, Andrew; Lucas, Thomas Geoffrey; Volpi, Matteo; Esperante-Pereira, Daniel; Rajamäki, Robin

2018-06-01

A prototype 11.994 GHz, traveling-wave accelerating structure for the Compact Linear Collider has been built, using the novel technique of assembling the structure from milled halves. The use of milled halves has many advantages when compared to a structure made from individual disks. These include the potential for a reduction in cost, because there are fewer parts, as well as a greater freedom in choice of joining technology because there are no rf currents across the halves' joint. Here we present the rf design and fabrication of the prototype structure, followed by the results of the high-power test and post-test surface analysis. During high-power testing the structure reached an unloaded gradient of 100 MV /m at a rf breakdown rate of less than 1.5 ×10-5 breakdowns /pulse /m with a 200 ns pulse. This structure has been designed for the CLIC testing program but construction from halves can be advantageous in a wide variety of applications.

High-Field High-Repetition-Rate Sources for the Coherent THz Control of Matter

PubMed Central

Green, B.; Kovalev, S.; Asgekar, V.; Geloni, G.; Lehnert, U.; Golz, T.; Kuntzsch, M.; Bauer, C.; Hauser, J.; Voigtlaender, J.; Wustmann, B.; Koesterke, I.; Schwarz, M.; Freitag, M.; Arnold, A.; Teichert, J.; Justus, M.; Seidel, W.; Ilgner, C.; Awari, N.; Nicoletti, D.; Kaiser, S.; Laplace, Y.; Rajasekaran, S.; Zhang, L.; Winnerl, S.; Schneider, H.; Schay, G.; Lorincz, I.; Rauscher, A. A.; Radu, I.; Mährlein, S.; Kim, T. H.; Lee, J. S.; Kampfrath, T.; Wall, S.; Heberle, J.; Malnasi-Csizmadia, A.; Steiger, A.; Müller, A. S.; Helm, M.; Schramm, U.; Cowan, T.; Michel, P.; Cavalleri, A.; Fisher, A. S.; Stojanovic, N.; Gensch, M.

2016-01-01

Ultrashort flashes of THz light with low photon energies of a few meV, but strong electric or magnetic field transients have recently been employed to prepare various fascinating nonequilibrium states in matter. Here we present a new class of sources based on superradiant enhancement of radiation from relativistic electron bunches in a compact electron accelerator that we believe will revolutionize experiments in this field. Our prototype source generates high-field THz pulses at unprecedented quasi-continuous-wave repetition rates up to the MHz regime. We demonstrate parameters that exceed state-of-the-art laser-based sources by more than 2 orders of magnitude. The peak fields and the repetition rates are highly scalable and once fully operational this type of sources will routinely provide 1 MV/cm electric fields and 0.3 T magnetic fields at repetition rates of few 100 kHz. We benchmark the unique properties by performing a resonant coherent THz control experiment with few 10 fs resolution. PMID:26924651

High-Field High-Repetition-Rate Sources for the Coherent THz Control of Matter

DOE PAGES

Green, B.; Kovalev, S.; Asgekar, V.; ...

2016-02-29

Ultrashort flashes of THz light with low photon energies of a few meV, but strong electric or magnetic field transients have recently been employed to prepare various fascinating nonequilibrium states in matter. Here we present a new class of sources based on superradiant enhancement of radiation from relativistic electron bunches in a compact electron accelerator that we believe will revolutionize experiments in this field. Our prototype source generates high-field THz pulses at unprecedented quasi-continuous-wave repetition rates up to the MHz regime. We demonstrate parameters that exceed state-of-the-art laser-based sources by more than 2 orders of magnitude. The peak fields andmore » the repetition rates are highly scalable and once fully operational this type of sources will routinely provide 1 MV/cm electric fields and 0.3 T magnetic fields at repetition rates of few 100 kHz. In conclusion, we benchmark the unique properties by performing a resonant coherent THz control experiment with few 10 fs resolution.« less

Development of a repetitive compact torus injector

NASA Astrophysics Data System (ADS)

Onchi, Takumi; McColl, David; Dreval, Mykola; Rohollahi, Akbar; Xiao, Chijin; Hirose, Akira; Zushi, Hideki

2013-10-01

A system for Repetitive Compact Torus Injection (RCTI) has been developed at the University of Saskatchewan. CTI is a promising fuelling technology to directly fuel the core region of tokamak reactors. In addition to fuelling, CTI has also the potential for (a) optimization of density profile and thus bootstrap current and (b) momentum injection. For steady-state reactor operation, RCTI is necessary. The approach to RCTI is to charge a storage capacitor bank with a large capacitance and quickly charge the CT capacitor bank through a stack of integrated-gate bipolar transistors (IGBTs). When the CT bank is fully charged, the IGBT stack will be turned off to isolate banks, and CT formation/acceleration sequence will start. After formation of each CT, the fast bank will be replenished and a new CT will be formed and accelerated. Circuits for the formation and the acceleration in University of Saskatchewan CT Injector (USCTI) have been modified. Three CT shots at 10 Hz or eight shots at 1.7 Hz have been achieved. This work has been sponsored by the CRC and NSERC, Canada.

Laser-driven electron beam and radiation sources for basic, medical and industrial sciences.

PubMed

Nakajima, Kazuhisa

2015-01-01

To date active research on laser-driven plasma-based accelerators have achieved great progress on production of high-energy, high-quality electron and photon beams in a compact scale. Such laser plasma accelerators have been envisaged bringing a wide range of applications in basic, medical and industrial sciences. Here inheriting the groundbreaker's review article on "Laser Acceleration and its future" [Toshiki Tajima, (2010)],(1)) we would like to review recent progress of producing such electron beams due to relativistic laser-plasma interactions followed by laser wakefield acceleration and lead to the scaling formulas that are useful to design laser plasma accelerators with controllability of beam energy and charge. Lastly specific examples of such laser-driven electron/photon beam sources are illustrated.

Intense combined source of neutrons and photons for interrogation based on compact deuteron RF accelerator

DOE PAGES

Kurennoy, S. S.; Garnett, R. W.; Rybarcyk, L. J.

2015-06-18

Interrogation of special nuclear materials can benefit from mobile sources providing significant fluxes of neutrons (10 8/s at 2.5 MeV, 10 10/s at 14.1 MeV) and of photons (>10 12/s at 1-3 MeV). We propose a source that satisfies these requirements simultaneously plus also provides, via the reaction 11B(d,n) 12C(γ 15.1), a significant flux of 15-MeV photons, which are highly penetrating and optimal for inducing photo-fission in actinides. The source is based on a compact (< 5 m) deuteron RF accelerator that delivers an average current of a few mA of deuterons at 3-4 MeV to a boron target.more » The accelerator consists of a short RFQ followed by efficient inter-digital H-mode structures with permanent-magnet-quadrupole beam focusing [Kurennoy et al. (2012)], which suit perfectly for deuteron acceleration at low energies. Our estimates, based on recent measurements, indicate that the required fluxes of both neutrons and photons can be achieved at ~1 mA of 4-MeV deuterons. The goal of the proposed study is to confirm feasibility of the approach and develop requirements for future full system implementation.« less

Vacuum system of the compact Energy Recovery Linac

DOE Office of Scientific and Technical Information (OSTI.GOV)

Honda, T., E-mail: tohru.honda@kek.jp; Tanimoto, Y.; Nogami, T.

2016-07-27

The compact Energy Recovery Linac (cERL), a test accelerator to establish important technologies demanded for future ERL-based light sources, was constructed in late 2013 at KEK. The accelerator was successfully commissioned in early 2014, and demonstrated beam circulation with energy recovery. In the cERL vacuum system, low-impedance vacuum components are required to circulate high-intensity, low-emittance and short-bunch electron beams. We therefore developed ultra-high-vacuum (UHV)-compatible flanges that can connect beam tubes seamlessly, and employed retractable beam monitors, namely, a movable Faraday cup and screen monitors. In most parts of the accelerator, pressures below 1×10{sup −7} Pa are required to mitigate beam-gasmore » interactions. Particularly, near the photocathode electron gun and the superconducting (SC) cavities, pressures below 1×10{sup −8} Pa are required. The beam tubes in the sections adjoining the SC cavities were coated with non-evaporable getter (NEG) materials, to reduce gas condensation on the cryo-surfaces. During the accelerator commissioning, stray magnetic fields from the permanent magnets of some cold cathode gauges (CCGs) were identified as a source of the disturbance to the beam orbit. Magnetic shielding was specially designed as a remedy for this issue.« less

Proton acceleration to above 5.5 MeV by interaction of 1017 W/cm2 laser pulse with H2O nano-wire targets

NASA Astrophysics Data System (ADS)

Schleifer, E.; Bruner, N.; Eisenmann, S.; Botton, M.; Pikuz, S. A., Jr.; Faenov, A. Y.; Gordon, D.; Zigler, A.

2011-05-01

Compact sources of high energy protons (50-500MeV) are expected to be key technology in a wide range of scientific applications 1-8. Particularly promising is the target normal sheah acceleration (TNSA) scheme 9,10, holding record level of 67MeV protons generated by a peta-Watt laser 11. In general, laser intensity exceeding 1018 W/cm2 is required to produce MeV level protons. Enhancing the energy of generated protons using compact laser sources is very attractive task nowadays. Recently, nano-scale targets were used to accelerate ions 12,13. Here we report on the first generation of 5.5-7.5MeV protons by modest laser intensities (4.5 × 1017 W/cm2) interacting with H2O nano-wires (snow) deposited on a Sapphire substrate. In this setup, the plasma near the tip of the nano-wire is subject to locally enhanced laser intensity with high spatial gradients, and confined charge separation is obtained. Electrostatic fields of extremely high intensities are produced, and protons are accelerated to MeV-level energies. Nano-wire engineered targets will relax the demand of peak energy from laser based sources.

Estimation of Stresses in a Dry Sand Layer Tested on Shaking Table

NASA Astrophysics Data System (ADS)

Sawicki, Andrzej; Kulczykowski, Marek; Jankowski, Robert

2012-12-01

Theoretical analysis of shaking table experiments, simulating earthquake response of a dry sand layer, is presented. The aim of such experiments is to study seismic-induced compaction of soil and resulting settlements. In order to determine the soil compaction, the cyclic stresses and strains should be calculated first. These stresses are caused by the cyclic horizontal acceleration at the base of soil layer, so it is important to determine the stress field as function of the base acceleration. It is particularly important for a proper interpretation of shaking table tests, where the base acceleration is controlled but the stresses are hard to measure, and they can only be deduced. Preliminary experiments have shown that small accelerations do not lead to essential settlements, whilst large accelerations cause some phenomena typical for limit states, including a visible appearance of slip lines. All these problems should be well understood for rational planning of experiments. The analysis of these problems is presented in this paper. First, some heuristic considerations about the dynamics of experimental system are presented. Then, the analysis of boundary conditions, expressed as resultants of respective stresses is shown. A particular form of boundary conditions has been chosen, which satisfies the macroscopic boundary conditions and the equilibrium equations. Then, some considerations are presented in order to obtain statically admissible stress field, which does not exceed the Coulomb-Mohr yield conditions. Such an approach leads to determination of the limit base accelerations, which do not cause the plastic state in soil. It was shown that larger accelerations lead to increase of the lateral stresses, and the respective method, which may replace complex plasticity analyses, is proposed. It is shown that it is the lateral stress coefficient K0 that controls the statically admissible stress field during the shaking table experiments.

A compact, low cost Marx bank for generating capillary discharge plasmas.

PubMed

Dyson, A E; Thornton, C; Hooker, S M

2016-09-01

We describe in detail a low power Compact Marx Bank (CMB) circuit that can provide 20 kV, 500 A pulses of approximately 100-200 ns duration. One application is the generation of capillary discharge plasmas of density ≈10 18 cm -3 used in laser plasma accelerators. The CMB is triggered with a high speed solid state switch and gives a high voltage output pulse with a ns scale rise time into a 50 Ω load (coaxial cable) with <4 ns voltage jitter. Its small size (10 cm  ×  25 cm  ×  5 cm) means that it can be placed right next to the capillary discharge in the target chamber to avoid the need to impedance match. The electrical energy required per discharge is <1 J, and the CMB can be run at shot repetition rates of ≳1 Hz. This low power requirement means that the circuit can easily be powered by a small lead acid battery and, therefore, can be floated relative to laboratory earth. The CMB is readily scalable and pulses >45 kV are demonstrated in air discharges.

A compact, low cost Marx bank for generating capillary discharge plasmas

NASA Astrophysics Data System (ADS)

Dyson, A. E.; Thornton, C.; Hooker, S. M.

2016-09-01

We describe in detail a low power Compact Marx Bank (CMB) circuit that can provide 20 kV, 500 A pulses of approximately 100-200 ns duration. One application is the generation of capillary discharge plasmas of density ≈1018 cm-3 used in laser plasma accelerators. The CMB is triggered with a high speed solid state switch and gives a high voltage output pulse with a ns scale rise time into a 50 Ω load (coaxial cable) with <4 ns voltage jitter. Its small size (10 cm × 25 cm × 5 cm) means that it can be placed right next to the capillary discharge in the target chamber to avoid the need to impedance match. The electrical energy required per discharge is <1 J, and the CMB can be run at shot repetition rates of ≳1 Hz. This low power requirement means that the circuit can easily be powered by a small lead acid battery and, therefore, can be floated relative to laboratory earth. The CMB is readily scalable and pulses >45 kV are demonstrated in air discharges.

Evaluation of a digital data acquisition system and optimization of n-γ discrimination for a compact neutron spectrometer.

PubMed

Giacomelli, L; Zimbal, A; Reginatto, M; Tittelmeier, K

2011-01-01

A compact NE213 liquid scintillation neutron spectrometer with a new digital data acquisition (DAQ) system is now in operation at the Physikalisch-Technische Bundesanstalt (PTB). With the DAQ system, developed by ENEA Frascati, neutron spectrometry with high count rates in the order of 5×10(5) s(-1) is possible, roughly an order of magnitude higher than with an analog acquisition system. To validate the DAQ system, a new data analysis code was developed and tests were done using measurements with 14-MeV neutrons made at the PTB accelerator. Additional analysis was carried out to optimize the two-gate method used for neutron and gamma (n-γ) discrimination. The best results were obtained with gates of 35 ns and 80 ns. This indicates that the fast and medium decay time components of the NE213 light emission are the ones that are relevant for n-γ discrimination with the digital acquisition system. This differs from what is normally implemented in the analog pulse shape discrimination modules, namely, the fast and long decay emissions of the scintillating light.

Evaluation of Stress Corrosion Cracking Susceptibility Using Fracture Mechanics Techniques, Part 1. [environmental tests of aluminum alloys, stainless steels, and titanium alloys

NASA Technical Reports Server (NTRS)

Sprowls, D. O.; Shumaker, M. B.; Walsh, J. D.; Coursen, J. W.

1973-01-01

Stress corrosion cracking (SSC) tests were performed on 13 aluminum alloys, 13 precipitation hardening stainless steels, and two titanium 6Al-4V alloy forgings to compare fracture mechanics techniques with the conventional smooth specimen procedures. Commercially fabricated plate and rolled or forged bars 2 to 2.5-in. thick were tested. Exposures were conducted outdoors in a seacoast atmosphere and in an inland industrial atmosphere to relate the accelerated tests with service type environments. With the fracture mechanics technique tests were made chiefly on bolt loaded fatigue precracked compact tension specimens of the type used for plane-strain fracture toughness tests. Additional tests of the aluminum alloy were performed on ring loaded compact tension specimens and on bolt loaded double cantilever beams. For the smooth specimen procedure 0.125-in. dia. tensile specimens were loaded axially in constant deformation type frames. For both aluminum and steel alloys comparative SCC growth rates obtained from tests of precracked specimens provide an additional useful characterization of the SCC behavior of an alloy.

Erosion characteristics of ethylene propylene diene monomer composite insulation by high-temperature dense particles

NASA Astrophysics Data System (ADS)

Li, Jiang; Guo, Meng-fei; Lv, Xiang; Liu, Yang; Xi, Kun; Guan, Yi-wen

2018-04-01

In this study, a dense particles erosion test motor which can simulate the erosion state of a solid rocket motor under high acceleration was developed. Subsequently, erosion experiments were carried out for the ethylene propylene diene monomer composite insulation and the microstructure of the char layer analysed. A turning point effect was found from the influence of the particle impact velocity on the ablation rate, and three erosion modes were determined according to the micro-morphology of the char layer. A reasonable explanation for the different structures of the char layer in the three modes was presented based on the formation mechanism of the compact/loose structure of the char layer.

Study on Effects of Different Replacement Rate on Bending Behavior of Big Recycled Aggregate Self Compacting Concrete

NASA Astrophysics Data System (ADS)

Li, Jing; Guo, Tiantian; Gao, Shuai; Jiang, Lin; Zhao, Zhijun; Wang, Yalin

2018-03-01

Big recycled aggregate self compacting concrete is a new type of recycled concrete, which has the advantages of low hydration heat and green environmental protection, but its bending behavior can be affected by different replacement rate. Therefor, in this paper, the research status of big Recycled aggregate self compacting concrete was systematically introduced, and the effect of different replacement rate of big recycled aggregate on failure mode, crack distribution and bending strength of the beam were studied through the bending behavior test of 4 big recycled aggregate self compacting concrete beams. The results show that: The crack distribution of the beam can be affected by the replacement rate; The failure modes of big recycled aggregate beams are the same as those of ordinary concrete; The plane section assumption is applicable to the big recycled aggregate self compacting concrete beam; The higher the replacement rate, the lower the bending strength of big recycled aggregate self compacting concrete beams.

Overview of graduate training program of John Adams Institute for Accelerator Science

NASA Astrophysics Data System (ADS)

Seryi, Andrei

The John Adams Institute for Accelerator Science is a center of excellence in the UK for advanced and novel accelerator technology, providing expertise, research, development and training in accelerator techniques, and promoting advanced accelerator applications in science and society. We work in JAI on design of novel light sources upgrades of 3-rd generation and novel FELs, on plasma acceleration and its application to industrial and medical fields, on novel energy recovery compact linacs and advanced beam diagnostics, and many other projects. The JAI is based on three universities - University of Oxford, Imperial College London and Royal Holloway University of London. Every year 6 to 10 accelerators science experts, trained via research on cutting edge projects, defend their PhD thesis in JAI partner universities. In this presentation we will overview the research and in particular the highly successful graduate training program in JAI.

Wavefront-sensor-based electron density measurements for laser-plasma accelerators.

PubMed

Plateau, G R; Matlis, N H; Geddes, C G R; Gonsalves, A J; Shiraishi, S; Lin, C; van Mourik, R A; Leemans, W P

2010-03-01

Characterization of the electron density in laser produced plasmas is presented using direct wavefront analysis of a probe laser beam. The performance of a laser-driven plasma-wakefield accelerator depends on the plasma wavelength and hence on the electron density. Density measurements using a conventional folded-wave interferometer and using a commercial wavefront sensor are compared for different regimes of the laser-plasma accelerator. It is shown that direct wavefront measurements agree with interferometric measurements and, because of the robustness of the compact commercial device, offer greater phase sensitivity and straightforward analysis, improving shot-to-shot plasma density diagnostics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garnett, Robert W.

Quite a broad range of accelerators have been applied to solving many of the challenging problems related to homeland security and defense. These accelerator systems range from relatively small, simple, and compact, to large and complex, based on the specific application requirements. They have been used or proposed as sources of primary and secondary probe beams for applications such as radiography and to induce specific reactions that are key signatures for detecting conventional explosives or fissile material. A brief overview and description of these accelerator systems, their specifications, and application will be presented. Some recent technology trends will also bemore » discussed.« less

Wavefront-sensor-based electron density measurements for laser-plasma accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plateau, Guillaume; Matlis, Nicholas; Geddes, Cameron

2010-02-20

Characterization of the electron density in laser produced plasmas is presented using direct wavefront analysis of a probe laser beam. The performance of a laser-driven plasma-wakefield accelerator depends on the plasma wavelength, hence on the electron density. Density measurements using a conventional folded-wave interferometer and using a commercial wavefront sensor are compared for different regimes of the laser-plasma accelerator. It is shown that direct wavefront measurements agree with interferometric measurements and, because of the robustness of the compact commercial device, have greater phase sensitivity, straightforward analysis, improving shot-to-shot plasma-density diagnostics.

New shielding material development for compact accelerator-driven neutron source

NASA Astrophysics Data System (ADS)

Hu, Guang; Hu, Huasi; Wang, Sheng; Han, Hetong; Otake, Y.; Pan, Ziheng; Taketani, A.; Ota, H.; Hashiguchi, Takao; Yan, Mingfei

2017-04-01

The Compact Accelerator-driven Neutron Source (CANS), especially the transportable neutron source is longing for high effectiveness shielding material. For this reason, new shielding material is researched in this investigation. The component of shielding material is designed and many samples are manufactured. Then the attenuation detection experiments were carried out. In the detections, the dead time of the detector appeases when the proton beam is too strong. To grasp the linear range and nonlinear range of the detector, two currents of proton are employed in Pb attenuation detections. The transmission ratio of new shielding material, polyethylene (PE), PE + Pb, BPE + Pb is detected under suitable current of proton. Since the results of experimental neutrons and γ-rays appear as together, the MCNP and PHITS simulations are applied to assisting the analysis. The new shielding material could reduce of the weight and volume compared with BPE + Pb and PE + Pb.

Commissioning of a compact laser-based proton beam line for high intensity bunches around 10Â MeV

NASA Astrophysics Data System (ADS)

Busold, S.; Schumacher, D.; Deppert, O.; Brabetz, C.; Kroll, F.; Blažević, A.; Bagnoud, V.; Roth, M.

2014-03-01

We report on the first results of experiments with a new laser-based proton beam line at the GSI accelerator facility in Darmstadt. It delivers high current bunches at proton energies around 9.6 MeV, containing more than 109 particles in less than 10 ns and with tunable energy spread down to 2.7% (ΔE/E0 at FWHM). A target normal sheath acceleration stage serves as a proton source and a pulsed solenoid provides for beam collimation and energy selection. Finally a synchronous radio frequency (rf) field is applied via a rf cavity for energy compression at a synchronous phase of -90 deg. The proton bunch is characterized at the end of the very compact beam line, only 3 m behind the laser matter interaction point, which defines the particle source.

Computational electronics and electromagnetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shang, C. C.

The Computational Electronics and Electromagnetics thrust area at Lawrence Livermore National Laboratory serves as the focal point for engineering R&D activities for developing computer-based design, analysis, and tools for theory. Key representative applications include design of particle accelerator cells and beamline components; engineering analysis and design of high-power components, photonics, and optoelectronics circuit design; EMI susceptibility analysis; and antenna synthesis. The FY-96 technology-base effort focused code development on (1) accelerator design codes; (2) 3-D massively parallel, object-oriented time-domain EM codes; (3) material models; (4) coupling and application of engineering tools for analysis and design of high-power components; (5) 3-D spectral-domainmore » CEM tools; and (6) enhancement of laser drilling codes. Joint efforts with the Power Conversion Technologies thrust area include development of antenna systems for compact, high-performance radar, in addition to novel, compact Marx generators. 18 refs., 25 figs., 1 tab.« less

rf design of a pulse compressor with correction cavity chain for klystron-based compact linear collider

NASA Astrophysics Data System (ADS)

Wang, Ping; Zha, Hao; Syratchev, Igor; Shi, Jiaru; Chen, Huaibi

2017-11-01

We present an X-band high-power pulse compression system for a klystron-based compact linear collider. In this system design, one rf power unit comprises two klystrons, a correction cavity chain, and two SLAC Energy Doubler (SLED)-type X-band pulse compressors (SLEDX). An rf pulse passes the correction cavity chain, by which the pulse shape is modified. The rf pulse is then equally split into two ways, each deploying a SLEDX to compress the rf power. Each SLEDX produces a short pulse with a length of 244 ns and a peak power of 217 MW to power four accelerating structures. With the help of phase-to-amplitude modulation, the pulse has a dedicated shape to compensate for the beam loading effect in accelerating structures. The layout of this system and the rf design and parameters of the new pulse compressor are described in this work.

High Energy Observational Investigations of Supernova Remnants and their Interactions with Surroundings

NASA Astrophysics Data System (ADS)

Hui, Chung-Yue

2013-09-01

Here we review the effort of Fermi Asian Network (FAN) in exploring the supernova remnants (SNRs) with state-of-art high energy observatories, including Fermi Gamma-ray Space Telescope and Chandra X-ray Observatory, in the period of 2011- 2012. Utilizing the data from Fermi LAT, we have discovered the GeV emission at the position of the Galactic SNR Kes 17 which provides evidence for the hadronic acceleration. Our study also sheds light on the propagation of cosmic rays from their acceleration site to the intersteller medium. We have also launched an identification campaign of SNR candidates in the Milky Way, in which a new SNR G308.3-1.4 have been uncovered with our Chandra observation. Apart from the remnant, we have also discovered an associated compact object at its center. The multiwavelength properties of this X-ray source suggest it can possibly be the compact binary that survived a supernova explosion.

SimTrack: A compact c++ code for particle orbit and spin tracking in accelerators

DOE PAGES

Luo, Yun

2015-08-29

SimTrack is a compact c++ code of 6-d symplectic element-by-element particle tracking in accelerators originally designed for head-on beam–beam compensation simulation studies in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. It provides a 6-d symplectic orbit tracking with the 4th order symplectic integration for magnet elements and the 6-d symplectic synchro-beam map for beam–beam interaction. Since its inception in 2009, SimTrack has been intensively used for dynamic aperture calculations with beam–beam interaction for RHIC. Recently, proton spin tracking and electron energy loss due to synchrotron radiation were added. In this article, I will present the code architecture,more » physics models, and some selected examples of its applications to RHIC and a future electron-ion collider design eRHIC.« less

SimTrack: A compact c++ library for particle orbit and spin tracking in accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Yun

2015-06-24

SimTrack is a compact c++ library of 6-d symplectic element-by-element particle tracking in accelerators originally designed for head-on beam-beam compensation simulation studies in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. It provides a 6-d symplectic orbit tracking with the 4th order symplectic integration for magnet elements and the 6-d symplectic synchro-beam map for beam-beam interaction. Since its inception in 2009, SimTrack has been intensively used for dynamic aperture calculations with beam-beam interaction for RHIC. Recently, proton spin tracking and electron energy loss due to synchrotron radiation were added. In this article, I will present the code architecture,more » physics models, and some selected examples of its applications to RHIC and a future electron-ion collider design eRHIC.« less

Laser-driven electron beam and radiation sources for basic, medical and industrial sciences

PubMed Central

NAKAJIMA, Kazuhisa

2015-01-01

To date active research on laser-driven plasma-based accelerators have achieved great progress on production of high-energy, high-quality electron and photon beams in a compact scale. Such laser plasma accelerators have been envisaged bringing a wide range of applications in basic, medical and industrial sciences. Here inheriting the groundbreaker’s review article on “Laser Acceleration and its future” [Toshiki Tajima, (2010)],1) we would like to review recent progress of producing such electron beams due to relativistic laser-plasma interactions followed by laser wakefield acceleration and lead to the scaling formulas that are useful to design laser plasma accelerators with controllability of beam energy and charge. Lastly specific examples of such laser-driven electron/photon beam sources are illustrated. PMID:26062737

A laser driven pulsed X-ray backscatter technique for enhanced penetrative imaging.

PubMed

Deas, R M; Wilson, L A; Rusby, D; Alejo, A; Allott, R; Black, P P; Black, S E; Borghesi, M; Brenner, C M; Bryant, J; Clarke, R J; Collier, J C; Edwards, B; Foster, P; Greenhalgh, J; Hernandez-Gomez, C; Kar, S; Lockley, D; Moss, R M; Najmudin, Z; Pattathil, R; Symes, D; Whittle, M D; Wood, J C; McKenna, P; Neely, D

2015-01-01

X-ray backscatter imaging can be used for a wide range of imaging applications, in particular for industrial inspection and portal security. Currently, the application of this imaging technique to the detection of landmines is limited due to the surrounding sand or soil strongly attenuating the 10s to 100s of keV X-rays required for backscatter imaging. Here, we introduce a new approach involving a 140 MeV short-pulse (< 100 fs) electron beam generated by laser wakefield acceleration to probe the sample, which produces Bremsstrahlung X-rays within the sample enabling greater depths to be imaged. A variety of detector and scintillator configurations are examined, with the best time response seen from an absorptive coated BaF2 scintillator with a bandpass filter to remove the slow scintillation emission components. An X-ray backscatter image of an array of different density and atomic number items is demonstrated. The use of a compact laser wakefield accelerator to generate the electron source, combined with the rapid development of more compact, efficient and higher repetition rate high power laser systems will make this system feasible for applications in the field. Content includes material subject to Dstl (c) Crown copyright (2014). Licensed under the terms of the Open Government Licence except where otherwise stated. To view this licence, visit http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: psi@ nationalarchives.gsi.gov.uk.

The Effect of Polymer Char on Nitridation Kinetics of Silicon

NASA Technical Reports Server (NTRS)

Chan, Rickmond C.; Bhatt, Ramakrishna T.

1994-01-01

Effects of polymer char on nitridation kinetics of attrition milled silicon powder have been investigated from 1200 to 1350 C. Results indicate that at and above 1250 C, the silicon compacts containing 3.5 wt percent polymer char were fully converted to Si3N4 after 24 hr exposure in nitrogen. In contrast, the silicon compacts without polymer char could not be fully converted to Si3N4 at 1350 C under similar exposure conditions. At 1250 and 1350 C, the silicon compacts with polymer char showed faster nitridation kinetics than those without the polymer char. As the polymer char content is increased, the amount of SiC in the nitrided material is also increased. By adding small amounts (approx. 2.5 wt percent) of NiO, the silicon compacts containing polymer char can be completely nitrided at 1200 C. The probable mechanism for the accelerated nitridation of silicon containing polymer char is discussed.

Investigations into dual-grating THz-driven accelerators

NASA Astrophysics Data System (ADS)

Wei, Y.; Ischebeck, R.; Dehler, M.; Ferrari, E.; Hiller, N.; Jamison, S.; Xia, G.; Hanahoe, K.; Li, Y.; Smith, J. D. A.; Welsch, C. P.

2018-01-01

Advanced acceleration technologies are receiving considerable interest in order to miniaturize future particle accelerators. One such technology is the dual-grating dielectric structures, which can support accelerating fields one to two orders of magnitude higher than the metal RF cavities in conventional accelerators. This opens up the possibility of enabling high accelerating gradients of up to several GV/m. This paper investigates numerically a quartz dual-grating structure which is driven by THz pulses to accelerate electrons. Geometry optimizations are carried out to achieve the trade-offs between accelerating gradient and vacuum channel gap. A realistic electron bunch available from the future Compact Linear Accelerator for Research and Applications (CLARA) is loaded into an optimized 100-period dual-grating structure for a detailed wakefield study. A THz pulse is then employed to interact with this CLARA bunch in the optimized structure. The computed beam quality is analyzed in terms of emittance, energy spread and loaded accelerating gradient. The simulations show that an accelerating gradient of 348 ± 12 MV/m with an emittance growth of 3.0% can be obtained.

High-velocity winds from a dwarf nova during outburst

NASA Technical Reports Server (NTRS)

Cordova, F. A.; Mason, K. O.

1982-01-01

An ultraviolet spectrum of the dwarf nova TW Vir during an optical outburst shows shortward-shifted absorption features with edge velocities as high as 4800 km/s, about the escape velocity of a white dwarf. A comparison of this spectrum with the UV spectra of other cataclysmic variables suggests that mass loss is evident only for systems with relatively high luminosities (more than about 10 solar luminosities) and low inclination angles with respect to the observer's line of sight. The mass loss rate for cataclysmic variables is of order 10 to the -11th solar mass per yr; this is from 0.01 to 0.001 of the mass accretion rate onto the compact star in the binary. The mass loss may occur by a mechanism similar to that invoked for early-type stars, i.e., radiation absorbed in the lines accelerates the accreting gas to the high velocities observed.

Experimental Results from a Resonant Dielectric Laser Accelerator

NASA Astrophysics Data System (ADS)

Yoder, Rodney; McNeur, Joshua; Sozer, Esin; Travish, Gil; Hazra, Kiran Shankar; Matthews, Brian; England, Joel; Peralta, Edgar; Wu, Ziran

2015-04-01

Laser-powered accelerators have the potential to operate with very large accelerating gradients (~ GV/m) and represent a path toward extremely compact colliders and accelerator technology. Optical-scale laser-powered devices based on field-shaping structures (known as dielectric laser accelerators, or DLAs) have been described and demonstrated recently. Here we report on the first experimental results from the Micro-Accelerator Platform (MAP), a DLA based on a slab-symmetric resonant optical-scale structure. As a resonant (rather than near-field) device, the MAP is distinct from other DLAs. Its cavity resonance enhances its accelerating field relative to the incoming laser fields, which are coupled efficiently through a diffractive optic on the upper face of the device. The MAP demonstrated modest accelerating gradients in recent experiments, in which it was powered by a Ti:Sapphire laser well below its breakdown limit. More detailed results and some implications for future developments will be discussed. Supported in part by the U.S. Defense Threat Reduction Agency (UCLA); U.S. Dept of Energy (SLAC); and DARPA (SLAC).

Compact all-fiber interferometer system for shock acceleration measurement

NASA Astrophysics Data System (ADS)

Zhao, Jiang; Pi, Shaohua; Hong, Guangwei; Zhao, Dong; Jia, Bo

2013-08-01

Acceleration measurement plays an important role in a variety of fields in science and engineering. In particular, the accurate, continuous and non-contact recording of the shock acceleration profiles of the free target surfaces is considered as a critical technique in shock physics. Various kinds of optical interferometers have been developed to monitor the motion of the surfaces of shocked targets since the 1960s, for instance, the velocity interferometer system for any reflector, the fiber optic accelerometer, the photonic Doppler velocimetry system and the displacement interferometer. However, most of such systems rely on the coherent quasi-monochromatic illumination and discrete optic elements, which are costly in setting-up and maintenance. In 1996, L. Levin et al reported an interferometric fiber-optic Doppler velocimeter with high-dynamic range, in which fiber-coupled components were used to replace the discrete optic elements. However, the fringe visibility of the Levin's system is low because of the coupled components, which greatly limits the reliability and accuracy in the shock measurement. In this paper, a compact all-fiber interferometer system for measuring the shock acceleration is developed and tested. The advantage of the system is that not only removes the non-interfering light and enhances the fringe visibility, but also reduces polarization induced signal fading and the polarization induced phase shift. Moreover, it also does not require a source of long coherence length. The system bases entirely on single-mode fiber optics and mainly consists of a polarization beam splitter, a faraday rotator, a depolarizer and a 3×3 single-mode fiber coupler which work at 1310 nm wavelength. The optical systems of the interferometer are described and the experimental results compared with a shock acceleration calibration system with a pneumatic exciter (PneuShockTM Model 9525C by The Modal Shop) are reported. In the shock acceleration test, the interferometer system measured shock acceleration with peak accelerations of ~100,000 m/s2 and the durations of ~0.2 ms which are conformed to the results of the shock acceleration calibration system. The measured relative error of the acceleration is within 3%.

First neutron generation in the BINP accelerator based neutron source.

PubMed

Bayanov, B; Burdakov, A; Chudaev, V; Ivanov, A; Konstantinov, S; Kuznetsov, A; Makarov, A; Malyshkin, G; Mekler, K; Sorokin, I; Sulyaev, Yu; Taskaev, S

2009-07-01

Pilot innovative facility for neutron capture therapy was built at Budker Institute of Nuclear Physics, Novosibirsk. This facility is based on a compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915 MeV protons bombarding a lithium target using (7)Li(p,n)(7)Be threshold reaction. The results of the first experiments on neutron generation are reported and discussed.

Cosmic Ray Production in Supernovae

NASA Astrophysics Data System (ADS)

Bykov, A. M.; Ellison, D. C.; Marcowith, A.; Osipov, S. M.

2018-02-01

We give a brief review of the origin and acceleration of cosmic rays (CRs), emphasizing the production of CRs at different stages of supernova evolution by the first-order Fermi shock acceleration mechanism. We suggest that supernovae with trans-relativistic outflows, despite being rather rare, may accelerate CRs to energies above 10^{18} eV over the first year of their evolution. Supernovae in young compact clusters of massive stars, and interaction powered superluminous supernovae, may accelerate CRs well above the PeV regime. We discuss the acceleration of the bulk of the galactic CRs in isolated supernova remnants and re-acceleration of escaped CRs by the multiple shocks present in superbubbles produced by associations of OB stars. The effects of magnetic field amplification by CR driven instabilities, as well as superdiffusive CR transport, are discussed for nonthermal radiation produced by nonlinear shocks of all speeds including trans-relativistic ones.

Investigating Compaction by Intergranular Pressure Solution Using the Discrete Element Method

NASA Astrophysics Data System (ADS)

van den Ende, M. P. A.; Marketos, G.; Niemeijer, A. R.; Spiers, C. J.

2018-01-01

Intergranular pressure solution creep is an important deformation mechanism in the Earth's crust. The phenomenon has been frequently studied and several analytical models have been proposed that describe its constitutive behavior. These models require assumptions regarding the geometry of the aggregate and the grain size distribution in order to solve for the contact stresses and often neglect shear tractions. Furthermore, analytical models tend to overestimate experimental compaction rates at low porosities, an observation for which the underlying mechanisms remain to be elucidated. Here we present a conceptually simple, 3-D discrete element method (DEM) approach for simulating intergranular pressure solution creep that explicitly models individual grains, relaxing many of the assumptions that are required by analytical models. The DEM model is validated against experiments by direct comparison of macroscopic sample compaction rates. Furthermore, the sensitivity of the overall DEM compaction rate to the grain size and applied stress is tested. The effects of the interparticle friction and of a distributed grain size on macroscopic strain rates are subsequently investigated. Overall, we find that the DEM model is capable of reproducing realistic compaction behavior, and that the strain rates produced by the model are in good agreement with uniaxial compaction experiments. Characteristic features, such as the dependence of the strain rate on grain size and applied stress, as predicted by analytical models, are also observed in the simulations. DEM results show that interparticle friction and a distributed grain size affect the compaction rates by less than half an order of magnitude.

Effects of Alloying Elements on the Formation of Core-Shell-Structured Reinforcing Particles during Heating of Al–Ti Powder Compacts

PubMed Central

Chen, Tijun; Gao, Min; Tong, Yunqi

2018-01-01

To prepare core-shell-structured Ti@compound particle (Ti@compoundp) reinforced Al matrix composite via powder thixoforming, the effects of alloying elements, such as Si, Cu, Mg, and Zn, on the reaction between Ti powders and Al melt, and the microstructure of the resulting reinforcements were investigated during heating of powder compacts at 993 K (720 °C). Simultaneously, the situations of the reinforcing particles in the corresponding semisolid compacts were also studied. Both thermodynamic analysis and experiment results all indicate that Si participated in the reaction and promoted the formation of Al–Ti–Si ternary compounds, while Cu, Mg, and Zn did not take part in the reaction and facilitated Al3Ti phase to form to different degrees. The first-formed Al–Ti–Si ternary compound was τ1 phase, and then it gradually transformed into (Al,Si)3Ti phase. The proportion and existing time of τ1 phase all increased as the Si content increased. In contrast, Mg had the largest, Cu had the least, and Si and Zn had an equivalent middle effect on accelerating the reaction. The thicker the reaction shell was, the larger the stress generated in the shell was, and thus the looser the shell microstructure was. The stress generated in (Al,Si)3Ti phase was larger than that in τ1 phase, but smaller than that in Al3Ti phase. So, the shells in the Al–Ti–Si system were more compact than those in the other systems, and Si element was beneficial to obtain thick and compact compound shells. Most of the above results were consistent to those in the semisolid state ones except the product phase constituents in the Al–Ti–Mg system and the reaction rate in the Al–Ti–Zn system. More importantly, the desirable core-shell structured Ti@compoundp was only achieved in the semisolid Al–Ti–Si system. PMID:29342946

Effects of Alloying Elements on the Formation of Core-Shell-Structured Reinforcing Particles during Heating of Al-Ti Powder Compacts.

PubMed

Chen, Tijun; Gao, Min; Tong, Yunqi

2018-01-15

To prepare core-shell-structured Ti@compound particle (Ti@compound p ) reinforced Al matrix composite via powder thixoforming, the effects of alloying elements, such as Si, Cu, Mg, and Zn, on the reaction between Ti powders and Al melt, and the microstructure of the resulting reinforcements were investigated during heating of powder compacts at 993 K (720 °C). Simultaneously, the situations of the reinforcing particles in the corresponding semisolid compacts were also studied. Both thermodynamic analysis and experiment results all indicate that Si participated in the reaction and promoted the formation of Al-Ti-Si ternary compounds, while Cu, Mg, and Zn did not take part in the reaction and facilitated Al₃Ti phase to form to different degrees. The first-formed Al-Ti-Si ternary compound was τ1 phase, and then it gradually transformed into (Al,Si)₃Ti phase. The proportion and existing time of τ1 phase all increased as the Si content increased. In contrast, Mg had the largest, Cu had the least, and Si and Zn had an equivalent middle effect on accelerating the reaction. The thicker the reaction shell was, the larger the stress generated in the shell was, and thus the looser the shell microstructure was. The stress generated in (Al,Si)₃Ti phase was larger than that in τ1 phase, but smaller than that in Al₃Ti phase. So, the shells in the Al-Ti-Si system were more compact than those in the other systems, and Si element was beneficial to obtain thick and compact compound shells. Most of the above results were consistent to those in the semisolid state ones except the product phase constituents in the Al-Ti-Mg system and the reaction rate in the Al-Ti-Zn system. More importantly, the desirable core-shell structured Ti@compound p was only achieved in the semisolid Al-Ti-Si system.

Multipurpose neutron generators based on the radio frequency quadrupole linear accelerator

NASA Astrophysics Data System (ADS)

Hamm, Robert W.

2000-12-01

Neutron generators based on the Radio Frequency Quadrupole accelerator are now used for a variety of applications. These compact linear accelerators can produce from 108 to more than 1013 neutrons/second using either proton or deuteron beams to bombard beryllium targets. They exhibit long lifetimes at full output, as there is little target or beam degradation. Since they do not use radioactive materials, licensing requirements are less stringent than for isotopic sources or tritium sealed tube generators. The light weight and compact size of these robust systems make them transportable. The low divergence output beam from the RFQ also allows use of a remote target, which can reduce the seize of the shielding and moderator. The RFQ linac can be designed with a wide range of output beam energy and used with other targets such as lithium and deuterium to produce a neutron spectrum tailored to a specific application. These pulsed systems are well-suited for applications requiring a high peak neutron flux, including activation analysis of very short-lived reaction products. They can replace conventional sources in non-destructive testing applications such as thermal or fast neutron radiography, and can also be used for cancer therapy.

Slot-coupled CW standing wave accelerating cavity

DOEpatents

Wang, Shaoheng; Rimmer, Robert; Wang, Haipeng

2017-05-16

A slot-coupled CW standing wave multi-cell accelerating cavity. To achieve high efficiency graded beta acceleration, each cell in the multi-cell cavity may include different cell lengths. Alternatively, to achieve high efficiency with acceleration for particles with beta equal to 1, each cell in the multi-cell cavity may include the same cell design. Coupling between the cells is achieved with a plurality of axially aligned kidney-shaped slots on the wall between cells. The slot-coupling method makes the design very compact. The shape of the cell, including the slots and the cone, are optimized to maximize the power efficiency and minimize the peak power density on the surface. The slots are non-resonant, thereby enabling shorter slots and less power loss.

Design and system integration of the superconducting wiggler magnets for the Compact Linear Collider damping rings

NASA Astrophysics Data System (ADS)

Schoerling, Daniel; Antoniou, Fanouria; Bernhard, Axel; Bragin, Alexey; Karppinen, Mikko; Maccaferri, Remo; Mezentsev, Nikolay; Papaphilippou, Yannis; Peiffer, Peter; Rossmanith, Robert; Rumolo, Giovanni; Russenschuck, Stephan; Vobly, Pavel; Zolotarev, Konstantin

2012-04-01

To achieve high luminosity at the collision point of the Compact Linear Collider (CLIC), the normalized horizontal and vertical emittances of the electron and positron beams must be reduced to 500 and 4 nm before the beams enter the 1.5 TeV linear accelerators. An effective way to accomplish ultralow emittances with only small effects on the electron polarization is using damping rings operating at 2.86 GeV equipped with superconducting wiggler magnets. This paper describes a technical design concept for the CLIC damping wigglers.

Angular Speed of a Compact Disc

NASA Astrophysics Data System (ADS)

Sawicki, Mikolaj ``Mik''

2006-09-01

A spinning motion of a compact disc in a CD player offers an interesting and challenging problem in rotational kinematics with a nonconstant angular acceleration that can be incorporated into a typical introductory physics class for engineers and scientists. It can be used either as an example presented during the lecture, emphasizing application of calculus, or as a homework assignment that could be handled easily with the help of a spreadsheet, thus eliminating the calculus aspect altogether. I tried both approaches, and the spreadsheet study was favored by my students.

Liquid-metal-fed Pulsed Plasma Thrusters for In-space Propulsion

NASA Technical Reports Server (NTRS)

Markusic, Thomas E.

2004-01-01

Liquid metal propellants may provide a path toward more reliable and efficient pulsed plasma thrusters (PPTs). Conceptual thruster designs which eliminate the need for high current switches and propellant metering valves are described. Propellant loading techniques are suggested that show promise to increase thruster propellant utilization, dynamic, and electrical efficiency. Calibration results from a compact, electromagnetically-pumped propellant feed system are presented. Results for lithium and gallium propellants show capability to meter propellant at flow rates up to 10 +/- 0.1 mg/s. Experiments investigating the initiation of arc discharges using liquid metal droplets are presented. High speed photography and laser interferometry provide spatially and temporally resolved information on the decomposition of liquid metal droplets , and the evolution of the accelerating current channel.

Field evaluation of roller integrated intelligent compaction monitoring : tech summary.

DOT National Transportation Integrated Search

2016-04-01

The objectives of the research were to: : 1. Demonstrate the value of RICM to accelerate construction, reduce re-work, and improve uniformity : of pavement layers. : 2. Evaluate the reliability and potential use of RICM data for acceptance and measur...

Advanced low-beta cavity development for proton and ion accelerators

NASA Astrophysics Data System (ADS)

Conway, Z. A.; Kelly, M. P.; Ostroumov, P. N.

2015-05-01

Recent developments in designing and processing low-beta superconducting cavities at Argonne National Laboratory are very encouraging for future applications requiring compact proton and ion accelerators. One of the major benefits of these accelerating structures is achieving real-estate accelerating gradients greater than 3 MV/m very efficiently either continuously or for long-duty cycle operation (>1%). The technology has been implemented in low-beta accelerator cryomodules for the Argonne ATLAS heavy-ion linac where the cryomodules are required to have real-estate gradients of more than 3 MV/m. In offline testing low-beta cavities with even higher gradients have already been achieved. This paper will review this work where we have achieved surface fields greater than 166 mT magnetic and 117 MV/m electric in a 72 MHz quarter-wave resonator optimized for β = 0.077 ions.

Water-level altitudes 2012 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2011 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2012-01-01

Compaction of subsurface sediments (mostly in the clay layers) composing the Chicot and Evangeline aquifers was recorded continuously at 13 borehole extensometers at 11 sites. For the period of record beginning in 1973 (or later) and ending in December 2011, cumulative compaction data collected from the 13 extensometers ranged from 0.102 ft at the Texas City–Moses Lake site to 3.621 ft at the Addicks site. The rate of compaction varies from site to site because of differences in groundwater withdrawals near each site and differences among sites in the clay-to-sand ratio in the subsurface sediments. Therefore, it is not possible to extrapolate or infer a rate of compaction for adjacent areas on the basis of the rate of compaction measured at a nearby extensometer.

Compact quasi-monoenergetic photon sources from laser-plasma accelerators for nuclear detection and characterization

NASA Astrophysics Data System (ADS)

Geddes, Cameron G. R.; Rykovanov, Sergey; Matlis, Nicholas H.; Steinke, Sven; Vay, Jean-Luc; Esarey, Eric H.; Ludewigt, Bernhard; Nakamura, Kei; Quiter, Brian J.; Schroeder, Carl B.; Toth, Csaba; Leemans, Wim P.

2015-05-01

Near-monoenergetic photon sources at MeV energies offer improved sensitivity at greatly reduced dose for active interrogation, and new capabilities in treaty verification, nondestructive assay of spent nuclear fuel and emergency response. Thomson (also referred to as Compton) scattering sources are an established method to produce appropriate photon beams. Applications are however restricted by the size of the required high-energy electron linac, scattering (photon production) system, and shielding for disposal of the high energy electron beam. Laser-plasma accelerators (LPAs) produce GeV electron beams in centimeters, using the plasma wave driven by the radiation pressure of an intense laser. Recent LPA experiments are presented which have greatly improved beam quality and efficiency, rendering them appropriate for compact high-quality photon sources based on Thomson scattering. Designs for MeV photon sources utilizing the unique properties of LPAs are presented. It is shown that control of the scattering laser, including plasma guiding, can increase photon production efficiency. This reduces scattering laser size and/or electron beam current requirements to scale compatible with the LPA. Lastly, the plasma structure can decelerate the electron beam after photon production, reducing the size of shielding required for beam disposal. Together, these techniques provide a path to a compact photon source system.

Current driven wiggler

NASA Astrophysics Data System (ADS)

Tournes, C.; Aucouturier, J.; Arnaud, B.; Brasile, J. P.; Convert, G.; Simon, M.

1992-07-01

A current-driven wiggler is the cornerstone of an innovative, compact, high-efficiency, transportable tunable free-electron laser (FEL), the feasibility of which is currently being evaluated by Thomson-CSF. The salient advantages are: compactness of the FEL, along with the possibility to accelerate the beam through several successive passes through the accelerating section (the number of passes being defined by the final wavelength of the radiation; i.e. visible, MWIR, LWIR); the wiggler can be turned off and be transparent to the beam until the last pass. Wiggler periodicities as small as 5 mm can be achieved, hence contributing to FEL compactness. To achieve overall efficiencies in the range of 10% at visible wavelengths, not only the wiggler periodicity must be variable, but the strength of the magnetic field of each period can be adjusted separately and fine-tuned versus time during the macropulse, so as to take into account the growing contribution of the wave energy in the cavity to the total ponderomotive force. The salient theoretical point of this design is the optimization of the parameters defining each period of the wiggler for each micropacket of the macropulse. The salient technology point is the mechanical and thermal design of the wiggler which allows the required high currents to achieve magnetic fields up to 2T.

Efficient and portable acceleration of quantum chemical many-body methods in mixed floating point precision using OpenACC compiler directives

NASA Astrophysics Data System (ADS)

Eriksen, Janus J.

2017-09-01

It is demonstrated how the non-proprietary OpenACC standard of compiler directives may be used to compactly and efficiently accelerate the rate-determining steps of two of the most routinely applied many-body methods of electronic structure theory, namely the second-order Møller-Plesset (MP2) model in its resolution-of-the-identity approximated form and the (T) triples correction to the coupled cluster singles and doubles model (CCSD(T)). By means of compute directives as well as the use of optimised device math libraries, the operations involved in the energy kernels have been ported to graphics processing unit (GPU) accelerators, and the associated data transfers correspondingly optimised to such a degree that the final implementations (using either double and/or single precision arithmetics) are capable of scaling to as large systems as allowed for by the capacity of the host central processing unit (CPU) main memory. The performance of the hybrid CPU/GPU implementations is assessed through calculations on test systems of alanine amino acid chains using one-electron basis sets of increasing size (ranging from double- to pentuple-ζ quality). For all but the smallest problem sizes of the present study, the optimised accelerated codes (using a single multi-core CPU host node in conjunction with six GPUs) are found to be capable of reducing the total time-to-solution by at least an order of magnitude over optimised, OpenMP-threaded CPU-only reference implementations.

Quasi-monoenergetic laser-plasma acceleration of electrons to 2 GeV

PubMed Central

Wang, Xiaoming; Zgadzaj, Rafal; Fazel, Neil; Li, Zhengyan; Yi, S. A.; Zhang, Xi; Henderson, Watson; Chang, Y.-Y.; Korzekwa, R.; Tsai, H.-E.; Pai, C.-H.; Quevedo, H.; Dyer, G.; Gaul, E.; Martinez, M.; Bernstein, A. C.; Borger, T.; Spinks, M.; Donovan, M.; Khudik, V.; Shvets, G.; Ditmire, T.; Downer, M. C.

2013-01-01

Laser-plasma accelerators of only a centimetre’s length have produced nearly monoenergetic electron bunches with energy as high as 1 GeV. Scaling these compact accelerators to multi-gigaelectronvolt energy would open the prospect of building X-ray free-electron lasers and linear colliders hundreds of times smaller than conventional facilities, but the 1 GeV barrier has so far proven insurmountable. Here, by applying new petawatt laser technology, we produce electron bunches with a spectrum prominently peaked at 2 GeV with only a few per cent energy spread and unprecedented sub-milliradian divergence. Petawatt pulses inject ambient plasma electrons into the laser-driven accelerator at much lower density than was previously possible, thereby overcoming the principal physical barriers to multi-gigaelectronvolt acceleration: dephasing between laser-driven wake and accelerating electrons and laser pulse erosion. Simulations indicate that with improvements in the laser-pulse focus quality, acceleration to nearly 10 GeV should be possible with the available pulse energy. PMID:23756359

Roadmap to the Future

NASA Astrophysics Data System (ADS)

Colby, Eric R.; Len, L. K.

Most particle accelerators today are expensive devices found only in the largest laboratories, industries, and hospitals. Using techniques developed nearly a century ago, the limiting performance of these accelerators is often traceable to material limitations, power source capabilities, and the cost tolerance of the application. Advanced accelerator concepts aim to increase the gradient of accelerators by orders of magnitude, using new power sources (e.g. lasers and relativistic beams) and new materials (e.g. dielectrics, metamaterials, and plasmas). Worldwide, research in this area has grown steadily in intensity since the 1980s, resulting in demonstrations of accelerating gradients that are orders of magnitude higher than for conventional techniques. While research is still in the early stages, these techniques have begun to demonstrate the potential to radically change accelerators, making them much more compact, and extending the reach of these tools of science into the angstrom and attosecond realms. Maturation of these techniques into robust, engineered devices will require sustained interdisciplinary, collaborative R&D and coherent use of test infrastructure worldwide. The outcome can potentially transform how accelerators are used.

Roadmap to the Future

NASA Astrophysics Data System (ADS)

Colby, Eric R.; Len, L. K.

Most particle accelerators today are expensive devices found only in the largest laboratories, industries, and hospitals. Using techniques developed nearly a century ago, the limiting performance of these accelerators is often traceable to material limitations, power source capabilities, and the cost tolerance of the application. Advanced accelerator conceptsa aim to increase the gradient of accelerators by orders of magnitude, using new power sources (e.g. lasers and relativistic beams) and new materials (e.g. dielectrics, metamaterials, and plasmas). Worldwide, research in this area has grown steadily in intensity since the 1980s, resulting in demonstrations of accelerating gradients that are orders of magnitude higher than for conventional techniques. While research is still in the early stages, these techniques have begun to demonstrate the potential to radically change accelerators, making them much more compact, and extending the reach of these tools of science into the angstrom and attosecond realms. Maturation of these techniques into robust, engineered devices will require sustained interdisciplinary, collaborative R&D and coherent use of test infrastructure worldwide. The outcome can potentially transform how accelerators are used.

Carbon-ion Radiotherapy for Prostate Cancer: Analysis of Morbidities and Change in Health-related Quality of Life.

PubMed

Ishikawa, Hitoshi; Katoh, Hiroyuki; Kaminuma, Takuya; Kawamura, Hidemasa; Ito, Kazuto; Matsui, Hiroshi; Hirato, Junko; Shimizu, Nobuaki; Takezawa, Yutaka; Tsuji, Hiroshi; Suzuki, Kazuhiro; Ohno, Tatsuya; Nakano, Takashi

2015-10-01

To prospectively evaluate the feasibility of carbon-ion radiotherapy (C-ion RT) for prostate cancer using a new compact-sized accelerator. Seventy-six patients underwent C-ion RT at our center using a recommended dose fractionation of 57.6 GyE in 16 fractions established at the National Institute of Radiological Sciences. Health-related Quality of Life (HRQOL) assessment was also performed using the Medical Outcome Study 8-items Short Form Health Survey (SF-8) questionnaire. The median follow-up time was 51 months (range=8-58 months). Grade 2 gastrointestinal and genitourinary complications developed in 1 (1.3%) and 5 (6.6%) patients, respectively. Recurrences occurred in 4 patients, and the 4-year biochemical relapse-free rate was 94.6%. The HRQOL scores after C-ion RT were objectively well-maintained. Irrespective of the small number of patients of the study, C-ion RT for prostate cancer using the first commercial-based accelerator reproduced the toxicity outcomes at the NIRS. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

High Luminosity LHC: Challenges and plans

DOE PAGES

Arduini, G.; Barranco, J.; Bertarelli, A.; ...

2016-12-28

The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will undergo a major upgrade in the 2020s. This will increase its rate of collisions by a factor of five beyond the original design value and the integrated luminosity by a factor ten. The new configuration, known as High Luminosity LHC (HL-LHC), willmore » rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11–12 T superconducting magnets, including Nb 3Sn-based magnets never used in accelerators before, compact superconducting cavities for longitudinal beam rotation, new technology and physical processes for beam collimation. As a result, the dynamics of the HL-LHC beams will be also particularly challenging and this aspect is the main focus of this paper.« less

Ice-sheet thinning and acceleration at Camp Century, Greenlan

NASA Astrophysics Data System (ADS)

Colgan, W. T.

2017-12-01

Camp Century, Greenland (77.18 °N, 61.12 °W, 1900 m), is located approximately 150 km inland from the ice-sheet margin in Northwest Greenland. In-situ and remotely-sensed measurements of ice-sheet elevation at Camp Century exhibit a thinning trend between 1964 and the present. A comparison of 1966 and 2017 firn density profiles indicates that a portion of this ice-sheet thinning is attributable to increased firn compaction rate. In-situ measurements of increasing ice surface velocity over the 1977-2017 period indicate that enhanced horizontal divergence of ice flux is also contributing to ice dynamic thinning at Camp Century. This apparent ice dynamic thinning could potentially result from a migrating local flow divide or decreasing effective ice viscosity. In a shorter-term context, observations of decadal-scale ice-sheet thinning and acceleration at Camp Century highlights underappreciated transience in inland ice form and flow during the satellite era. In a longer-term context, these multi-decadal observations contrast with inferences of millennial-scale ice-sheet thickening and deceleration at Camp Century.

Performance characteristics and typical industrial applications of Selfshield® electron accelerators (< 300 kV)

NASA Astrophysics Data System (ADS)

Aaronson, Judith N.; Nablo, Sam V.

1985-05-01

Selfshielded electron accelerators have been successfully used in industry for more than ten years. One of the important advantages of these machines is their compactness for easy adaptation to conventional coating and product finishing machinery. It is equally important that these machines qualify for use under "unrestricted" conditions as specified by OSHA. The shielding and product handling configurations which make this unrestricted designation possible for operating voltages under 300 kV are discussed. Thin film dosimetry techniques used for the determination of the machine performance parameters are discussed along with the rotary scanner techniques employed for the dose rate studies which are important in the application of these processors. Paper and wood coatings, which are important industrial applications involving electron initiated polymerization, are reviewed. The sterilization and disinfestation applications are also discussed. The increasing concern of these industries for the more efficient use of energy and for compliance with more stringent pollution regulations, coupled with the novel processes this energy source makes possible, assure a bright future for this developing technology.

An Undulator-Based Laser Wakefield Accelerator Electron Beam Diagnostic

NASA Astrophysics Data System (ADS)

Bakeman, Michael S.

Currently particle accelerators such as the Large Hadron Collider use RF cavities with a maximum field gradient of 50-100 MV/m to accelerate particles over long distances. A new type of plasma based accelerator called a Laser Plasma Accelerator (LPA) is being investigated at the LOASIS group at Lawrence Berkeley National Laboratory which can sustain field gradients of 10-100 GV/m. This new type of accelerator offers the potential to create compact high energy accelerators and light sources. In order to investigate the feasibility of producing a compact light source an undulator-based electron beam diagnostic for use on the LOASIS LPA has been built and calibrated. This diagnostic relies on the principal that the spectral analysis of synchrotron radiation from an undulator can reveal properties of the electron beam such as emittance, energy and energy spread. The effects of electron beam energy spread upon the harmonics of undulator produced synchrotron radiation were derived from the equations of motion of the beam and numerically simulated. The diagnostic consists of quadrupole focusing magnets to collimate the electron beam, a 1.5 m long undulator to produce the synchrotron radiation, and a high resolution high gain XUV spectrometer to analyze the radiation. The undulator was aligned and tuned in order to maximize the flux of synchrotron radiation produced. The spectrometer was calibrated at the Advanced Light Source, with the results showing the ability to measure electron beam energy spreads at resolutions as low as 0.1% rms, a major improvement over conventional magnetic spectrometers. Numerical simulations show the ability to measure energy spreads on realistic LPA produced electron beams as well as the improvements in measurements made with the quadrupole magnets. Experimentally the quadrupoles were shown to stabilize and focus the electron beams at specific energies for their insertion into the undulator, with the eventual hope of producing an all optical Free Electron Laser operating in the XUV and soft x-ray regimes.

The Care and Feeding of Bright Kids.

ERIC Educational Resources Information Center

Starko, Alane J.

1989-01-01

The article describes ways to nurture gifted students without shortchanging the rest of the class. Curriculum compacting techniques allow teachers to plan for students with similar capabilities, determining which skills are already known, which need work, and what acceleration activities should be added. (SM)

Water-level altitudes 2014 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2013 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2014-01-01

Compaction of subsurface sediments (mostly in the fine-grained clay and silt layers) composing the Chicot and Evangeline aquifers was recorded continuously by using analog technology at the 13 borehole extensometers at 11 sites that were either activated or installed between 1973 and 1980. For the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2013, measured cumulative compaction at the 13 extensometers ranged from 0.100 ft at the Texas City-Moses Lake extensometer to 3.654 ft at the Addicks extensometer. The rate of compaction varies from site to site because of differences in rates of groundwater withdrawal in the areas adjacent to each extensometer site and differences among sites in the ratios of clay, silt, and sand and compressibility of the subsurface sediments. Therefore, it is not appropriate to extrapolate or infer a rate of compaction for an adjacent area on the basis of the rate of compaction measured at nearby extensometers.

Plasma physics and related challenges of millimeter-wave-to-terahertz and high power microwave generationa)

NASA Astrophysics Data System (ADS)

Booske, John H.

2008-05-01

Homeland security and military defense technology considerations have stimulated intense interest in mobile, high power sources of millimeter-wave (mmw) to terahertz (THz) regime electromagnetic radiation, from 0.1 to 10THz. While vacuum electronic sources are a natural choice for high power, the challenges have yet to be completely met for applications including noninvasive sensing of concealed weapons and dangerous agents, high-data-rate communications, high resolution radar, next generation acceleration drivers, and analysis of fluids and condensed matter. The compact size requirements for many of these high frequency sources require miniscule, microfabricated slow wave circuits. This necessitates electron beams with tiny transverse dimensions and potentially very high current densities for adequate gain. Thus, an emerging family of microfabricated, vacuum electronic devices share many of the same plasma physics challenges that are currently confronting "classic" high power microwave (HPM) generators including long-life bright electron beam sources, intense beam transport, parasitic mode excitation, energetic electron interaction with surfaces, and rf air breakdown at output windows. The contemporary plasma physics and other related issues of compact, high power mmw-to-THz sources are compared and contrasted to those of HPM generation, and future research challenges and opportunities are discussed.

A light-weight compact proton gantry design with a novel dose delivery system for broad-energetic laser-accelerated beams

NASA Astrophysics Data System (ADS)

Masood, U.; Cowan, T. E.; Enghardt, W.; Hofmann, K. M.; Karsch, L.; Kroll, F.; Schramm, U.; Wilkens, J. J.; Pawelke, J.

2017-07-01

Proton beams may provide superior dose-conformity in radiation therapy. However, the large sizes and costs limit the widespread use of proton therapy (PT). The recent progress in proton acceleration via high-power laser systems has made it a compelling alternative to conventional accelerators, as it could potentially reduce the overall size and cost of the PT facilities. However, the laser-accelerated beams exhibit different characteristics than conventionally accelerated beams, i.e. very intense proton bunches with large divergences and broad-energy spectra. For the application of laser-driven beams in PT, new solutions for beam transport, such as beam capture, integrated energy selection, beam shaping and delivery systems are required due to the specific beam parameters. The generation of these beams are limited by the low repetition rate of high-power lasers and this limitation would require alternative solutions for tumour irradiation which can efficiently utilize the available high proton fluence and broad-energy spectra per proton bunch to keep treatment times short. This demands new dose delivery system and irradiation field formation schemes. In this paper, we present a multi-functional light-weight and compact proton gantry design for laser-driven sources based on iron-less pulsed high-field magnets. This achromatic design includes improved beam capturing and energy selection systems, with a novel beam shaping and dose delivery system, so-called ELPIS. ELPIS system utilizes magnetic fields, instead of physical scatterers, for broadening the spot-size of broad-energetic beams while capable of simultaneously scanning them in lateral directions. To investigate the clinical feasibility of this gantry design, we conducted a treatment planning study with a 3D treatment planning system augmented for the pulsed beams with optimizable broad-energetic widths and selectable beam spot sizes. High quality treatment plans could be achieved with such unconventional beam parameters, deliverable via the presented gantry and ELPIS dose delivery system. The conventional PT gantries are huge and require large space for the gantry to rotate the beam around the patient, which could be reduced up to 4 times with the presented pulse powered gantry system. The further developments in the next generation petawatt laser systems and laser-targets are crucial to reach higher proton energies. However, if proton energies required for therapy applications are reached it could be possible in future to reduce the footprint of the PT facilities, without compromising on clinical standards.

A light-weight compact proton gantry design with a novel dose delivery system for broad-energetic laser-accelerated beams.

PubMed

Masood, U; Cowan, T E; Enghardt, W; Hofmann, K M; Karsch, L; Kroll, F; Schramm, U; Wilkens, J J; Pawelke, J

2017-07-07

Proton beams may provide superior dose-conformity in radiation therapy. However, the large sizes and costs limit the widespread use of proton therapy (PT). The recent progress in proton acceleration via high-power laser systems has made it a compelling alternative to conventional accelerators, as it could potentially reduce the overall size and cost of the PT facilities. However, the laser-accelerated beams exhibit different characteristics than conventionally accelerated beams, i.e. very intense proton bunches with large divergences and broad-energy spectra. For the application of laser-driven beams in PT, new solutions for beam transport, such as beam capture, integrated energy selection, beam shaping and delivery systems are required due to the specific beam parameters. The generation of these beams are limited by the low repetition rate of high-power lasers and this limitation would require alternative solutions for tumour irradiation which can efficiently utilize the available high proton fluence and broad-energy spectra per proton bunch to keep treatment times short. This demands new dose delivery system and irradiation field formation schemes. In this paper, we present a multi-functional light-weight and compact proton gantry design for laser-driven sources based on iron-less pulsed high-field magnets. This achromatic design includes improved beam capturing and energy selection systems, with a novel beam shaping and dose delivery system, so-called ELPIS. ELPIS system utilizes magnetic fields, instead of physical scatterers, for broadening the spot-size of broad-energetic beams while capable of simultaneously scanning them in lateral directions. To investigate the clinical feasibility of this gantry design, we conducted a treatment planning study with a 3D treatment planning system augmented for the pulsed beams with optimizable broad-energetic widths and selectable beam spot sizes. High quality treatment plans could be achieved with such unconventional beam parameters, deliverable via the presented gantry and ELPIS dose delivery system. The conventional PT gantries are huge and require large space for the gantry to rotate the beam around the patient, which could be reduced up to 4 times with the presented pulse powered gantry system. The further developments in the next generation petawatt laser systems and laser-targets are crucial to reach higher proton energies. However, if proton energies required for therapy applications are reached it could be possible in future to reduce the footprint of the PT facilities, without compromising on clinical standards.

The development of enabling technologies for producing active interrogation beams.

PubMed

Kwan, Thomas J T; Morgado, Richard E; Wang, Tai-Sen F; Vodolaga, B; Terekhin, V; Onischenko, L M; Vorozhtsov, S B; Samsonov, E V; Vorozhtsov, A S; Alenitsky, Yu G; Perpelkin, E E; Glazov, A A; Novikov, D L; Parkhomchuk, V; Reva, V; Vostrikov, V; Mashinin, V A; Fedotov, S N; Minayev, S A

2010-10-01

A U.S./Russian collaboration of accelerator scientists was directed to the development of high averaged-current (∼1 mA) and high-quality (emittance ∼15 πmm mrad; energy spread ∼0.1%) 1.75 MeV proton beams to produce active interrogation beams that could be applied to counterterrorism. Several accelerator technologies were investigated. These included an electrostatic tandem accelerator of novel design, a compact cyclotron, and a storage ring with energy compensation and electron cooling. Production targets capable of withstanding the beam power levels were designed, fabricated, and tested. The cyclotron/storage-ring system was theoretically studied and computationally designed, and the electrostatic vacuum tandem accelerator at BINP was demonstrated for its potential in active interrogation of explosives and special nuclear materials.

Electrostatic accelerators with high energy resolution

NASA Astrophysics Data System (ADS)

Uchiyama, T.; Agawa, Y.; Nishihashi, T.; Takagi, K.; Yamakawa, H.; Isoya, A.; Takai, M.; Namba, S.

1991-05-01

Several models of electrostatic accelerators based on rotating disks (Disktron) have been manufactured for various ion beam applications like surface analyses and implantation. The high voltage terminal of the Disktron with a terminal voltage of up to 500 kV is open in air, while the generator part is enclosed in FRP (fiber reinforced plastics) or a ceramic vessel filled with sf 6 gas. The 1 MV model is completely enclosed in a steel vessel. A compact tandem accelerator of the pellet chain type with a terminal voltage of 1.5 MV has also been manufactured. The good energy stability of these accelerators, typically in the range of 10 -4, has proved to be quite favorable for applications in precise studies of material surfaces, including the use of microbeam techniques.

SECOND TARGET STATION MODERATOR PERFORMANCE WITH A ROTATING TARGET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Remec, Igor; Gallmeier, Franz X; Rennich, Mark J

2016-01-01

Oak Ridge National Laboratory manages and operates the Spallation Neutron Source and the High Flux Isotope Reactor, two of the world's most advanced neutron scattering facilities. Both facilities are funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Science, and are available to researchers from all over the world. Delivering cutting edge science requires continuous improvements and development of the facilities and instruments. The SNS was designed from the outset to accommodate an additional target station, or Second Target Station (STS), and an upgraded accelerator feeding proton beams to STS and the existing First Targetmore » Station (FTS). Upgrade of the accelerator and the design and construction of STS are being proposed. The presently considered STS configuration is driven with short (<1 s) proton pulses at 10 Hz repetition rate and 467 kW proton beam power, and is optimized for high intensity and high resolution long wavelength neutron applications. STS will allow installation of 22 beamlines and will expand and complement the current national neutron scattering capabilities. In 2015 the STS studies were performed for a compact tungsten target; first a stationary tungsten plate target was analyzed to considerable details and then dropped in favor of a rotating target. For both target options the proton beam footprint as small as acceptable from mechanical and heat removal aspects is required to arrive at a compact-volume neutron production zone in the target, which is essential for tight coupling of target and moderators and for achieving high-intensity peak neutron fluxes. This paper will present recent STS work with the emphasis on neutronics and moderator performance.« less

Pyroelectric Crystal Accelerator In The Department Of Physics And Nuclear Engineering At West Point

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gillich, Don; Kovanen, Andrew; Anderson, Tom

The Nuclear Science and Engineering Research Center (NSERC), a Defense Threat Reduction Agency (DTRA) office located at the United States Military Academy (USMA), sponsors and manages cadet and faculty research in support of DTRA objectives. The NSERC has created an experimental pyroelectric crystal accelerator program to enhance undergraduate education at USMA in the Department of Physics and Nuclear Engineering. This program provides cadets with hands-on experience in designing their own experiments using an inexpensive tabletop accelerator. This device uses pyroelectric crystals to ionize and accelerate gas ions to energies of {approx}100 keV. Within the next year, cadets and faculty atmore » USMA will use this device to create neutrons through the deuterium-deuterium (D-D) fusion process, effectively creating a compact, portable neutron generator. The double crystal pyroelectric accelerator will also be used by students to investigate neutron, x-ray, and ion spectroscopy.« less

Acceleration of deuterons with suppression of electronic conductance in a vacuum diode with a laser target on the anode

NASA Astrophysics Data System (ADS)

Shikanov, A. E.; Vovchenko, E. D.; Kozlovskii, K. I.; Shatokhin, V. L.

2016-12-01

We report new experimental results on the acceleration of deuterons in a compact coaxial diode with the suppression of electronic conductance by a constant longitudinal magnetic field. Plasma containing deuterons is created on a laser TiD target located on the anode. The pulse of accelerating voltage is formed by means of the Arkad'ev-Marx generator. The cathode symmetrically surrounds the anode and comprises a hollow permanent ring magnet with an inner radius of no more than 0.02 m and an on-axis induction of up to 0.4 T, which provides the magnetic insulation of the accelerating gap. The experiments demonstrate the possibility of obtaining accelerated deuterons with energy of up to 300 keV and a current of up to 0.5 kA with a pulse duration of 0.2 μs.

Advanced low-beta cavity development for proton and ion accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conway, Z. A.; Kelly, M. P.; Ostroumov, P. N.

2015-05-01

Recent developments in designing and processing low-beta superconducting cavities at Argonne National Laboratory are very encouraging for future applications requiring compact proton and ion accelerators. One of the major benefits of these accelerating structures is achieving real-estate accelerating gradients greater than 3 MV/m very efficiently either continuously or for long-duty cycle operation (>1%). The technology has been implemented in low-beta accelerator cryomodules for the Argonne ATLAS heavy-ion linac where the cryomodules are required to have real-estate gradients of more than 3 MV/m. In offline testing low-beta cavities with even higher gradients have already been achieved. This paper will review thismore » work where we have achieved surface fields greater than 166 mT magnetic and 117 MV/m electric in a 72 MHz quarter-wave resonator optimized for beta = 0.077 ions.« less

Driver-witness electron beam acceleration in dielectric mm-scale capillaries

NASA Astrophysics Data System (ADS)

Lekomtsev, K.; Aryshev, A.; Tishchenko, A. A.; Shevelev, M.; Lyapin, A.; Boogert, S.; Karataev, P.; Terunuma, N.; Urakawa, J.

2018-05-01

We investigated a corrugated mm-scale capillary as a compact accelerating structure in the driver-witness acceleration scheme, and suggested a methodology to measure the acceleration of the witness bunch. The accelerating fields produced by the driver bunch and the energy spread of the witness bunch in a corrugated capillary and in a capillary with a constant inner radius were measured and simulated for both on-axis and off-axis beam propagation. Our simulations predicted a change in the accelerating field structure for the corrugated capillary. Also, an approximately twofold increase of the witness bunch energy gain on the first accelerating cycle was expected for both capillaries for the off-axis beam propagation. These results were confirmed in the experiment, and the maximum measured acceleration of 170 keV /m at 20 pC driver beam charge was achieved for off-axis beam propagation. The driver bunch showed an increase in energy spread of up to 11%, depending on the capillary geometry and beam propagation, with a suppression of the longitudinal energy spread in the witness bunch of up to 15%.

Preferential enhancement of laser-driven carbon ion acceleration from optimized nanostructured surfaces

PubMed Central

Dalui, Malay; Wang, W.-M.; Trivikram, T. Madhu; Sarkar, Subhrangshu; Tata, Sheroy; Jha, J.; Ayyub, P.; Sheng, Z. M.; Krishnamurthy, M.

2015-01-01

High-intensity ultrashort laser pulses focused on metal targets readily generate hot dense plasmas which accelerate ions efficiently and can pave way to compact table-top accelerators. Laser-driven ion acceleration studies predominantly focus on protons, which experience the maximum acceleration owing to their highest charge-to-mass ratio. The possibility of tailoring such schemes for the preferential acceleration of a particular ion species is very much desired but has hardly been explored. Here, we present an experimental demonstration of how the nanostructuring of a copper target can be optimized for enhanced carbon ion acceleration over protons or Cu-ions. Specifically, a thin (≈0.25 μm) layer of 25–30 nm diameter Cu nanoparticles, sputter-deposited on a polished Cu-substrate, enhances the carbon ion energy by about 10-fold at a laser intensity of 1.2×1018  W/cm2. However, particles smaller than 20 nm have an adverse effect on the ion acceleration. Particle-in-cell simulations provide definite pointers regarding the size of nanoparticles necessary for maximizing the ion acceleration. The inherent contrast of the laser pulse is found to play an important role in the species selective ion acceleration. PMID:26153048

A tandem-based compact dual-energy gamma generator.

PubMed

Persaud, A; Kwan, J W; Leitner, M; Leung, K-N; Ludewigt, B; Tanaka, N; Waldron, W; Wilde, S; Antolak, A J; Morse, D H; Raber, T

2010-02-01

A dual-energy tandem-type gamma generator has been developed at E. O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications. Both positively charged ions and atoms of hydrogen are created from negative ions via a gas stripper. In this paper, we show first results of the working tandem-based gamma generator and that a gas stripper can be utilized in a compact source design. Preliminary results of monoenergetic gamma production are shown.

Application of graphics processing units to search pipelines for gravitational waves from coalescing binaries of compact objects

NASA Astrophysics Data System (ADS)

Chung, Shin Kee; Wen, Linqing; Blair, David; Cannon, Kipp; Datta, Amitava

2010-07-01

We report a novel application of a graphics processing unit (GPU) for the purpose of accelerating the search pipelines for gravitational waves from coalescing binaries of compact objects. A speed-up of 16-fold in total has been achieved with an NVIDIA GeForce 8800 Ultra GPU card compared with one core of a 2.5 GHz Intel Q9300 central processing unit (CPU). We show that substantial improvements are possible and discuss the reduction in CPU count required for the detection of inspiral sources afforded by the use of GPUs.

Central region of SKKUCY-9 compact cyclotron

NASA Astrophysics Data System (ADS)

Jung, S. Y.; Kim, H. W.; Ghergherehchi, M.; Park, J. K.; Chai, J. S.; Kim, S. H.

2014-04-01

The development of a 9 MeV compact cyclotron for the production of radioisotopes for medical applications has been recently completed. The machine accelerates negative hydrogen ions generated from an internal PIG (Penning Ion Gauge) ion source following spiral orbits. Some of the structures designed for early beam acceleration, including a pair of center poles providing ions a circular direction, the head of the ion source, and the electrodes, are located in the center of the cyclotron. In this paper we discuss and evaluate the design of the central region that pulls the ions from the chimney of the ion source and directs them into the equilibrium orbit. The magnetic field produced by the center poles was analyzed using the magnetic solver in OPERA-3D TOSCA, and the phase error and ion equilibrium orbit, which is dependent on the kinetic energy within the designed field, were calculated using CYCLONE v8.4. The electric field produced in the acceleration gap was designed using an electrostatic solver. Then, the single beam trajectory was calculated by our own Cyclotron Beam Dynamics (CBD) code. The early orbits, vertical oscillation, acceptable RF phase and the energy gain during the early turns was evaluated. Final goal was to design the central region by the iterative optimization process and verify it with 1 MeV beam experiment.

Recovery of severely compacted soils in the Mojave Desert, California, USA

USGS Publications Warehouse

Webb, R.H.

2002-01-01

Often as a result of large-scale military maneuvers in the past, many soils in the Mojave Desert are highly vulnerable to soil compaction, particularly when wet. Previous studies indicate that natural recovery of severely compacted desert soils is extremely slow, and some researchers have suggested that subsurface compaction may not recover. Poorly sorted soils, particularly those with a loamy sand texture, are most vulnerable to soil compaction, and these soils are the most common in alluvial fans of the Mojave Desert. Recovery of compacted soil is expected to vary as a function of precipitation amounts, wetting-and-drying cycles, freeze-thaw cycles, and bioturbation, particularly root growth. Compaction recovery, as estimated using penetration depth and bulk density, was measured at 19 sites with 32 site-time combinations, including the former World War II Army sites of Camps Ibis, Granite, Iron Mountain, Clipper, and Essex. Although compaction at these sites was caused by a wide variety of forces, ranging from human trampling to tank traffic, the data do not allow segregation of differences in recovery rates for different compaction forces. The recovery rate appears to be logarithmic, with the highest rate of change occurring in the first few decades following abandonment. Some higher-elevation sites have completely recovered from soil compaction after 70 years. Using a linear model of recovery, the full recovery time ranges from 92 to 100 years; using a logarithmic model, which asymptotically approaches full recovery, the time required for 85% recovery ranges from 105-124 years.

Efficient acceleration of neutral atoms in laser produced plasma

DOE PAGES

Dalui, M.; Trivikram, T. M.; Colgan, James Patrick; ...

2017-06-20

Recent advances in high-intensity laser-produced plasmas have demonstrated their potential as compact charge particle accelerators. Unlike conventional accelerators, transient quasi-static charge separation acceleration fields in laser produced plasmas are highly localized and orders of magnitude larger. Manipulating these ion accelerators, to convert the fast ions to neutral atoms with little change in momentum, transform these to a bright source of MeV atoms. The emittance of the neutral atom beam would be similar to that expected for an ion beam. Since intense laser-produced plasmas have been demonstrated to produce high-brightness-low-emittance beams, it is possible to envisage generation of high-flux, low-emittance, highmore » energy neutral atom beams in length scales of less than a millimeter. Here, we show a scheme where more than 80% of the fast ions are reduced to energetic neutral atoms and demonstrate the feasibility of a high energy neutral atom accelerator that could significantly impact applications in neutral atom lithography and diagnostics.« less

Direct longitudinal laser acceleration of electrons in free space

NASA Astrophysics Data System (ADS)

Carbajo, Sergio; Nanni, Emilio A.; Wong, Liang Jie; Moriena, Gustavo; Keathley, Phillip D.; Laurent, Guillaume; Miller, R. J. Dwayne; Kärtner, Franz X.

2016-02-01

Compact laser-driven accelerators are pursued heavily worldwide because they make novel methods and tools invented at national laboratories widely accessible in science, health, security, and technology [V. Malka et al., Principles and applications of compact laser-plasma accelerators, Nat. Phys. 4, 447 (2008)]. Current leading laser-based accelerator technologies [S. P. D. Mangles et al., Monoenergetic beams of relativistic electrons from intense laser-plasma interactions, Nature (London) 431, 535 (2004); T. Toncian et al., Ultrafast laser-driven microlens to focus and energy-select mega-electron volt protons, Science 312, 410 (2006); S. Tokita et al. Single-shot ultrafast electron diffraction with a laser-accelerated sub-MeV electron pulse, Appl. Phys. Lett. 95, 111911 (2009)] rely on a medium to assist the light to particle energy transfer. The medium imposes material limitations or may introduce inhomogeneous fields [J. R. Dwyer et al., Femtosecond electron diffraction: "Making the molecular movie,", Phil. Trans. R. Soc. A 364, 741 (2006)]. The advent of few cycle ultraintense radially polarized lasers [S. Carbajo et al., Efficient generation of ultraintense few-cycle radially polarized laser pulses, Opt. Lett. 39, 2487 (2014)] has ushered in a novel accelerator concept [L. J. Wong and F. X. Kärtner, Direct acceleration of an electron in infinite vacuum by a pulsed radially polarized laser beam, Opt. Express 18, 25035 (2010); F. Pierre-Louis et al. Direct-field electron acceleration with ultrafast radially polarized laser beams: Scaling laws and optimization, J. Phys. B 43, 025401 (2010); Y. I. Salamin, Electron acceleration from rest in vacuum by an axicon Gaussian laser beam, Phys. Rev. A 73, 043402 (2006); C. Varin and M. Piché, Relativistic attosecond electron pulses from a free-space laser-acceleration scheme, Phys. Rev. E 74, 045602 (2006); A. Sell and F. X. Kärtner, Attosecond electron bunches accelerated and compressed by radially polarized laser pulses and soft-x-ray pulses from optical undulators, J. Phys. B 47, 015601 (2014)] avoiding the need of a medium or guiding structure entirely to achieve strong longitudinal energy transfer. Here we present the first observation of direct longitudinal laser acceleration of nonrelativistic electrons that undergo highly directional multi-GeV /m accelerating gradients. This demonstration opens a new frontier for direct laser-driven particle acceleration capable of creating well collimated and relativistic attosecond electron bunches [C. Varin and M. Piché, Relativistic attosecond electron pulses from a free-space laser-acceleration scheme, Phys. Rev. E 74, 045602 (2006)] and x-ray pulses [A. Sell and F. X. Kärtner, Attosecond electron bunches accelerated and compressed by radially polarized laser pulses and soft-x-ray pulses from optical undulators, J. Phys. B 47, 015601 (2014)].

SU-E-T-512: Electromagnetic Simulations of the Dielectric Wall Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uselmann, A; Mackie, T

Purpose: To characterize and parametrically study the key components of a dielectric wall accelerator through electromagnetic modeling and particle tracking. Methods: Electromagnetic and particle tracking simulations were performed using a commercial code (CST Microwave Studio, CST Inc.) utilizing the finite integration technique. A dielectric wall accelerator consists of a series of stacked transmission lines sequentially fired in synchrony with an ion pulse. Numerous properties of the stacked transmission lines, including geometric, material, and electronic properties, were analyzed and varied in order to assess their impact on the transverse and axial electric fields. Additionally, stacks of transmission lines were simulated inmore » order to quantify the parasitic effect observed in closely packed lines. Particle tracking simulations using the particle-in-cell method were performed on the various stacks to determine the impact of the above properties on the resultant phase space of the ions. Results: Examination of the simulation results show that novel geometries can shape the accelerating pulse in order to reduce the energy spread and increase the average energy of accelerated ions. Parasitic effects were quantified for various geometries and found to vary with distance from the end of the transmission line and along the beam axis. An optimal arrival time of an ion pulse relative to the triggering of the transmission lines for a given geometry was determined through parametric study. Benchmark simulations of single transmission lines agree well with published experimental results. Conclusion: This work characterized the behavior of the transmission lines used in a dielectric wall accelerator and used this information to improve them in novel ways. Utilizing novel geometries, we were able to improve the accelerating gradient and phase space of the accelerated particle bunch. Through simulation, we were able to discover and optimize design issues with the device at low cost. Funding: Morgridge Institute for Research, Madison WI; Conflict of Interest: Dr. Mackie is an investor and board member at CPAC, a company developing compact accelerator designs similar to those discussed in this work, but designs discussed are not directed by CPAC. Funding: Morgridge Institute for Research, Madison WI; Conflict of Interest: Dr. Mackie is an investor and board member at CPAC, a company developing compact accelerator designs similar to those discussed in this work, but designs discussed are not directed by CPAC.« less

A compact model for electroosmotic flows in microfluidic devices

NASA Astrophysics Data System (ADS)

Qiao, R.; Aluru, N. R.

2002-09-01

A compact model to compute flow rate and pressure in microfluidic devices is presented. The microfluidic flow can be driven by either an applied electric field or a combined electric field and pressure gradient. A step change in the ζ-potential on a channel wall is treated by a pressure source in the compact model. The pressure source is obtained from the pressure Poisson equation and conservation of mass principle. In the proposed compact model, the complex fluidic network is simplified by an electrical circuit. The compact model can predict the flow rate, pressure distribution and other basic characteristics in microfluidic channels quickly with good accuracy when compared to detailed numerical simulation. Using the compact model, fluidic mixing and dispersion control are studied in a complex microfluidic network.

Wnt/β-catenin signaling directs the regional expansion of first and second heart field-derived ventricular cardiomyocytes

PubMed Central

Buikema, Jan Willem; Mady, Ahmed S.; Mittal, Nikhil V.; Atmanli, Ayhan; Caron, Leslie; Doevendans, Pieter A.; Sluijter, Joost P. G.; Domian, Ibrahim J.

2013-01-01

In mammals, cardiac development proceeds from the formation of the linear heart tube, through complex looping and septation, all the while increasing in mass to provide the oxygen delivery demands of embryonic growth. The developing heart must orchestrate regional differences in cardiomyocyte proliferation to control cardiac morphogenesis. During ventricular wall formation, the compact myocardium proliferates more vigorously than the trabecular myocardium, but the mechanisms controlling such regional differences among cardiomyocyte populations are not understood. Control of definitive cardiomyocyte proliferation is of great importance for application to regenerative cell-based therapies. We have used murine and human pluripotent stem cell systems to demonstrate that, during in vitro cellular differentiation, early ventricular cardiac myocytes display a robust proliferative response to β-catenin-mediated signaling and conversely accelerate differentiation in response to inhibition of this pathway. Using gain- and loss-of-function murine genetic models, we show that β-catenin controls ventricular myocyte proliferation during development and the perinatal period. We further demonstrate that the differential activation of the Wnt/β-catenin signaling pathway accounts for the observed differences in the proliferation rates of the compact versus the trabecular myocardium during normal cardiac development. Collectively, these results provide a mechanistic explanation for the differences in localized proliferation rates of cardiac myocytes and point to a practical method for the generation of the large numbers of stem cell-derived cardiac myocytes necessary for clinical applications. PMID:24026118

Hydrodynamic simulations of stellar wind disruption by a compact X-ray source

NASA Technical Reports Server (NTRS)

Blondin, John M.; Kallman, Timothy R.; Fryxell, Bruce A.; Taam, Ronald E.

1990-01-01

This paper presents two-dimensional numerical simulations of the gas flow in the orbital plane of a massive X-ray binary system, in which the mass accretion is fueled by a radiation-driven wind from an early-type companion star. These simulations are used to examine the role of the compact object (either a neutron star or a black hole) in disturbing the radiatively accelerating wind of the OB companion, with an emphasis on understanding the origin of the observed soft X-ray photoelectric absorption seen at late orbital phases in these systems. On the basis of these simulations, it is suggested that the phase-dependent photoelectric absorption seen in several of these systems can be explained by dense filaments of compressend gas formed in the nonsteady accreation bow shock and wake of the compact object.

Development of a Dielectric-Loaded Accelerator Test Facility Based on an X-Band Magnicon Amplifier

NASA Astrophysics Data System (ADS)

Gold, S. H.; Kinkead, A. K.; Gai, W.; Power, J. G.; Konecny, R.; Jing, C.; Tantawi, S. G.; Nantista, C. D.; Hu, Y.; Du, X.; Tang, C.; Lin, Y.; Bruce, R. W.; Bruce, R. L.; Fliflet, A. W.; Lewis, D.

2006-01-01

The Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), are developing a dielectric-loaded accelerator (DLA) test facility powered by the 11.424-GHz magnicon amplifier that was developed jointly by NRL and Omega-P, Inc. Thus far, DLA structures developed by ANL have been tested at the NRL Magnicon Facility without injected electrons, including tests of alumina and magnesium calcium titanate structures at gradients up to ˜8 MV/m. The next step is to inject electrons in order to build a compact DLA test accelerator. The Accelerator Laboratory of Tsinghua University in Beijing, China has developed a 5-MeV electron injector for the accelerator, and SLAC is developing a means to combine the two magnicon output arms, and to drive the injector and an accelerator section with separate control of the power ratio and relative phase. Also, RWBruce Associates, working with NRL, is developing a means to join ceramic tubes to produce long accelerating sections using a microwave brazing process. The installation and commissioning of the first dielectric-loaded test accelerator, including injector, DLA structure, and spectrometer, should take place within the next year.

Analysis of ultrasonic effect on powder and application to radioactive sample compaction

NASA Astrophysics Data System (ADS)

Kim, Jungsoon; Sim, Minseop; Kim, Jihyang; Kim, Moojoon

2018-07-01

The effect of ultrasound on powder compaction was analyzed. The decreasing in the friction coefficient of the powder sample is derived theoretically. The compaction rate was improved by the ultrasound. We applied the effect to the compaction of environmental radioactive soil samples. From γ-ray spectroscopy analysis, more radionuclides could be detectable in the sample compacted with ultrasound.

High power tests of an electroforming cavity operating at 11.424 GHz

NASA Astrophysics Data System (ADS)

Dolgashev, V. A.; Gatti, G.; Higashi, Y.; Leonardi, O.; Lewandowski, J. R.; Marcelli, A.; Rosenzweig, J.; Spataro, B.; Tantawi, S. G.; Yeremian, D. A.

2016-03-01

The achievement of ultra high accelerating gradients is mandatory in order to fabricate compact accelerators at 11.424 GHz for scientific and industrial applications. An extensive experimental and theoretical program to determine a reliable ultra high gradient operation of the future linear accelerators is under way in many laboratories. In particular, systematic studies on the 11.424 GHz frequency accelerator structures, R&D on new materials and the associated microwave technology are in progress to achieve accelerating gradients well above 120 MeV/m. Among the many, the electroforming procedure is a promising approach to manufacture high performance RF devices in order to avoid the high temperature brazing and to produce precise RF structures. We report here the characterization of a hard high gradient RF accelerating structure at 11.424 GHz fabricated using the electroforming technique. Low-level RF measurements and high power RF tests carried out at the SLAC National Accelerator Laboratory on this prototype are presented and discussed. In addition, we present also a possible layout where the water-cooling of irises based on the electroforming process has been considered for the first time.

Distribution uniformity of laser-accelerated proton beams

NASA Astrophysics Data System (ADS)

Zhu, Jun-Gao; Zhu, Kun; Tao, Li; Xu, Xiao-Han; Lin, Chen; Ma, Wen-Jun; Lu, Hai-Yang; Zhao, Yan-Ying; Lu, Yuan-Rong; Chen, Jia-Er; Yan, Xue-Qing

2017-09-01

Compared with conventional accelerators, laser plasma accelerators can generate high energy ions at a greatly reduced scale, due to their TV/m acceleration gradient. A compact laser plasma accelerator (CLAPA) has been built at the Institute of Heavy Ion Physics at Peking University. It will be used for applied research like biological irradiation, astrophysics simulations, etc. A beamline system with multiple quadrupoles and an analyzing magnet for laser-accelerated ions is proposed here. Since laser-accelerated ion beams have broad energy spectra and large angular divergence, the parameters (beam waist position in the Y direction, beam line layout, drift distance, magnet angles etc.) of the beamline system are carefully designed and optimised to obtain a radially symmetric proton distribution at the irradiation platform. Requirements of energy selection and differences in focusing or defocusing in application systems greatly influence the evolution of proton distributions. With optimal parameters, radially symmetric proton distributions can be achieved and protons with different energy spread within ±5% have similar transverse areas at the experiment target. Supported by National Natural Science Foundation of China (11575011, 61631001) and National Grand Instrument Project (2012YQ030142)

Particle-in-cell simulation of x-ray wakefield acceleration and betatron radiation in nanotubes

DOE PAGES

Zhang, Xiaomei; Tajima, Toshiki; Farinella, Deano; ...

2016-10-18

Though wakefield acceleration in crystal channels has been previously proposed, x-ray wakefield acceleration has only recently become a realistic possibility since the invention of the single-cycled optical laser compression technique. We investigate the acceleration due to a wakefield induced by a coherent, ultrashort x-ray pulse guided by a nanoscale channel inside a solid material. By two-dimensional particle-in-cell computer simulations, we show that an acceleration gradient of TeV/cm is attainable. This is about 3 orders of magnitude stronger than that of the conventional plasma-based wakefield accelerations, which implies the possibility of an extremely compact scheme to attain ultrahigh energies. In additionmore » to particle acceleration, this scheme can also induce the emission of high energy photons at ~O(10–100) MeV. Here, our simulations confirm such high energy photon emissions, which is in contrast with that induced by the optical laser driven wakefield scheme. In addition to this, the significantly improved emittance of the energetic electrons has been discussed.« less

Experimental realization of underdense plasma photocathode wakefield acceleration at FACET

NASA Astrophysics Data System (ADS)

Scherkl, Paul

2017-10-01

Novel electron beam sources from compact plasma accelerator concepts currently mature into the driving technology for next generation high-energy physics and light source facilities. Particularly electron beams of ultra-high brightness could pave the way for major advances for both scientific and commercial applications, but their generation remains tremendously challenging. The presentation outlines the experimental demonstration of the world's first bright electron beam source from spatiotemporally synchronized laser pulses injecting electrons into particle-driven plasma wakefields at FACET. Two distinctive types of operation - laser-triggered density downramp injection (``Plasma Torch'') and underdense plasma photocathode acceleration (``Trojan Horse'') - and their intermediate transitions are characterized and contrasted. Extensive particle-in-cell simulations substantiate the presentation of experimental results. In combination with novel techniques to minimize the beam energy spread, the acceleration scheme presented here promises ultra-high beam quality and brightness.

A Compact, Pi-Mode Extraction Scheme for the Axial B-Field Recirculating Planar Magnetron

DTIC Science & Technology

2012-07-23

Figure 4). Thus, in a planar magnetron, the minimum phase velocity, vph , to stay above cutoff in the rectangular waveguide is ℎ = ...as magnetrons, electrons must be accelerated such that they are in synchronism with the phase velocity, vph , of the electromagnetic wave for an

Compact X-ray sources: X-rays from self-reflection

NASA Astrophysics Data System (ADS)

Mangles, Stuart P. D.

2012-05-01

Laser-based particle acceleration offers a way to reduce the size of hard-X-ray sources. Scientists have now developed a simple scheme that produces a bright flash of hard X-rays by using a single laser pulse both to generate and to scatter an electron beam.

High-gradient compact linear accelerator

DOEpatents

Carder, B.M.

1998-05-26

A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter. 10 figs.

High-gradient compact linear accelerator

DOEpatents

Carder, Bruce M.

1998-01-01

A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter.

Water-level altitudes 2013 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973--2012 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

2013-01-01

Compaction of subsurface sediments (mostly in the clay and silt layers) of the Chicot and Evangeline aquifers was recorded continuously by 13 borehole extensometers at 11 sites that were either activated or installed between 1973 and 1980. For the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2012, cumulative measured compaction by 12 of the 13 extensometers ranged from 0.100 ft at the Texas City-Moses Lake extensometer to 3.632 ft at the Addicks extensometer (data were used from only one of two extensometers at one site). The rate of compaction varies from site to site because of differences in groundwater withdrawals near each site and differences among sites in the clay-to-sand ratio in the subsurface sediments. Therefore, it is not possible to extrapolate or infer a rate of compaction for adjacent areas based on the rate of compaction measured at a nearby extensometer.

Tunable Low Energy, Compact and High Performance Neuromorphic Circuit for Spike-Based Synaptic Plasticity

PubMed Central

Rahimi Azghadi, Mostafa; Iannella, Nicolangelo; Al-Sarawi, Said; Abbott, Derek

2014-01-01

Cortical circuits in the brain have long been recognised for their information processing capabilities and have been studied both experimentally and theoretically via spiking neural networks. Neuromorphic engineers are primarily concerned with translating the computational capabilities of biological cortical circuits, using the Spiking Neural Network (SNN) paradigm, into in silico applications that can mimic the behaviour and capabilities of real biological circuits/systems. These capabilities include low power consumption, compactness, and relevant dynamics. In this paper, we propose a new accelerated-time circuit that has several advantages over its previous neuromorphic counterparts in terms of compactness, power consumption, and capability to mimic the outcomes of biological experiments. The presented circuit simulation results demonstrate that, in comparing the new circuit to previous published synaptic plasticity circuits, reduced silicon area and lower energy consumption for processing each spike is achieved. In addition, it can be tuned in order to closely mimic the outcomes of various spike timing- and rate-based synaptic plasticity experiments. The proposed circuit is also investigated and compared to other designs in terms of tolerance to mismatch and process variation. Monte Carlo simulation results show that the proposed design is much more stable than its previous counterparts in terms of vulnerability to transistor mismatch, which is a significant challenge in analog neuromorphic design. All these features make the proposed design an ideal circuit for use in large scale SNNs, which aim at implementing neuromorphic systems with an inherent capability that can adapt to a continuously changing environment, thus leading to systems with significant learning and computational abilities. PMID:24551089

Tunable low energy, compact and high performance neuromorphic circuit for spike-based synaptic plasticity.

PubMed

Rahimi Azghadi, Mostafa; Iannella, Nicolangelo; Al-Sarawi, Said; Abbott, Derek

2014-01-01

Cortical circuits in the brain have long been recognised for their information processing capabilities and have been studied both experimentally and theoretically via spiking neural networks. Neuromorphic engineers are primarily concerned with translating the computational capabilities of biological cortical circuits, using the Spiking Neural Network (SNN) paradigm, into in silico applications that can mimic the behaviour and capabilities of real biological circuits/systems. These capabilities include low power consumption, compactness, and relevant dynamics. In this paper, we propose a new accelerated-time circuit that has several advantages over its previous neuromorphic counterparts in terms of compactness, power consumption, and capability to mimic the outcomes of biological experiments. The presented circuit simulation results demonstrate that, in comparing the new circuit to previous published synaptic plasticity circuits, reduced silicon area and lower energy consumption for processing each spike is achieved. In addition, it can be tuned in order to closely mimic the outcomes of various spike timing- and rate-based synaptic plasticity experiments. The proposed circuit is also investigated and compared to other designs in terms of tolerance to mismatch and process variation. Monte Carlo simulation results show that the proposed design is much more stable than its previous counterparts in terms of vulnerability to transistor mismatch, which is a significant challenge in analog neuromorphic design. All these features make the proposed design an ideal circuit for use in large scale SNNs, which aim at implementing neuromorphic systems with an inherent capability that can adapt to a continuously changing environment, thus leading to systems with significant learning and computational abilities.

Hydrologic behavior of model slopes with synthetic water repellent soils

NASA Astrophysics Data System (ADS)

Zheng, Shuang; Lourenço, Sérgio D. N.; Cleall, Peter J.; Chui, Ting Fong May; Ng, Angel K. Y.; Millis, Stuart W.

2017-11-01

In the natural environment, soil water repellency decreases infiltration, increases runoff, and increases erosion in slopes. In the built environment, soil water repellency offers the opportunity to develop granular materials with controllable wettability for slope stabilization. In this paper, the influence of soil water repellency on the hydrological response of slopes is investigated. Twenty-four flume tests were carried out in model slopes under artificial rainfall; soils with various wettability levels were tested, including wettable (Contact Angle, CA < 90°), subcritical water repellent (CA ∼ 90°) and water repellent (CA > 90°). Various rainfall intensities (30 mm/h and 70 mm/h), slope angles (20° and 40°) and relative compactions (70% and 90%) were applied to model the response of natural and man-made slopes to rainfall. To quantitatively assess the hydrological response, a number of measurements were made: runoff rate, effective rainfall rate, time to ponding, time to steady state, runoff acceleration, total water storage and wetting front rate. Overall, an increase in soil water repellency reduces infiltration and shortens the time for runoff generation, with the effects amplified for high rainfall intensity. Comparatively, the slope angle and relative compaction had only a minor contribution to the slope hydrology. The subcritical water repellent soils sustained infiltration for longer than both the wettable and water repellent soils, which presents an added advantage if they are to be used in the built environment as barriers. This study revealed substantial impacts of man-made or synthetically induced soil water repellency on the hydrological behavior of model slopes in controlled conditions. The results shed light on our understanding of hydrological processes in environments where the occurrence of natural soil water repellency is likely, such as slopes subjected to wildfires and in agricultural and forested slopes.

High Efficiency Electron-Laser Interactions in Tapered Helical Undulators

NASA Astrophysics Data System (ADS)

Duris, Joseph Patrick

Efficient coupling of relativistic electron beams with high power radiation lies at the heart of advanced accelerator and light source research and development. The inverse free electron laser is a stable accelerator capable of harnessing very high intensity laser electric fields to efficiently transfer large powers from lasers to electron beams. In this dissertation, we first present the theoretical framework to describe the interaction, and then apply our improved understanding of the IFEL to the design and numerical study of meter-long, GeV IFELs for compact light sources. The central experimental work of the dissertation is the UCLA BNL helical inverse free electron laser experiment at the Accelerator Test Facility in Brookhaven National Laboratory which used a strongly tapered 54cm long, helical, permanent magnet undulator and a several hundred GW CO2 laser to accelerate electrons from 52 to 106MeV, setting new records for inverse free electron laser energy gain (54MeV) and average accelerating gradient (100MeV/m). The undulator design and fabrication as well as experimental diagnostics are presented. In order to improve the stability and quality of the accelerated electron beam, we redesigned the undulator for a slightly reduced output energy by modifying the magnet gap throughout the undulator, and we used this modified undulator to demonstrated capture of >25% of the injected beam without prebunching. In the study of heavily loaded GeV inverse free electron lasers, we show that a majority of the power may be transferred from a laser to the accelerated electron beam. Reversing the process to decelerate high power electron beams, a mechanism we refer to as tapering enhanced stimulated superradiant amplification, offers a clear path to high power light sources. We present studies of radiation production for a wide range of wavelengths (10mum, 13nm, and 0.3nm) using this method and discuss the design for a deceleration experiment using the same undulator used for acceleration in this experiment. By accounting for the evolving radiation field in the design of the undulator tapering, a large fraction of energy may be transferred between the electrons and laser, enabling compact, high-current GeV accelerators and various wavelength light-sources of unprecedented peak powers.

Multipactor Physics, Acceleration, and Breakdown in Dielectric-Loaded Accelerating Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, Richard P.; Gold, Steven H.

2016-07-01

The objective of this 3-year program is to study the physics issues associated with rf acceleration in dielectric-loaded accelerating (DLA) structures, with a focus on the key issue of multipactor loading, which has been found to cause very significant rf power loss in DLA structures whenever the rf pulsewidth exceeds the multipactor risetime (~10 ns). The experiments are carried out in the X-band magnicon laboratory at the Naval Research Laboratory (NRL) in collaboration with Argonne National Laboratory (ANL) and Euclid Techlabs LLC, who develop the test structures with support from the DoE SBIR program. There are two main elements inmore » the research program: (1) high-power tests of DLA structures using the magnicon output (20 MW @11.4 GHz), and (2) tests of electron acceleration in DLA structures using relativistic electrons from a compact X-band accelerator. The work during this period has focused on a study of the use of an axial magnetic field to suppress multipactor in DLA structures, with several new high power tests carried out at NRL, and on preparation of the accelerator for the electron acceleration experiments.« less

A new concept of a vacuum insulation tandem accelerator.

PubMed

Sorokin, I; Taskaev, S

2015-12-01

A tandem accelerator with vacuum insulation has been proposed and developed in the Budker Institute of Nuclear Physics. Negative hydrogen ions are accelerated by the positive 1 MV potential of the high voltage electrode, converted into protons in the gas stripping target inside the electrode, and then the protons are accelerated again by the same potential. The potential for high voltage and intermediate electrodes is supplied by the sectioned rectifier through a sectioned bushing insulator with a resistive divider. In this work, we propose a radical improvement of the accelerator concept. It is proposed to abandon the separate placement of the accelerator and the power supply and connect them through the bushing insulator. The source of high voltage is proposed to be located inside the accelerator insulator with high voltage and intermediate electrodes mounted on it. This will reduce the facility height from 7 m to 3m and make it really compact and attractive for placing in a clinic. This will significantly increase the stability of the accelerator because the potential for intermediate electrodes can be fed directly from the relevant sections of the rectifier. Copyright © 2015 Elsevier Ltd. All rights reserved.

Beam manipulation with velocity bunching for PWFA applications

NASA Astrophysics Data System (ADS)

Pompili, R.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Bisesto, F.; Chiadroni, E.; Cianchi, A.; Croia, M.; Curcio, A.; Di Giovenale, D.; Ferrario, M.; Filippi, F.; Galletti, M.; Gallo, A.; Giribono, A.; Li, W.; Marocchino, A.; Mostacci, A.; Petrarca, M.; Petrillo, V.; Di Pirro, G.; Romeo, S.; Rossi, A. R.; Scifo, J.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zhu, J.

2016-09-01

The activity of the SPARC_LAB test-facility (LNF-INFN, Frascati) is currently focused on the development of new plasma-based accelerators. Particle accelerators are used in many fields of science, with applications ranging from particle physics research to advanced radiation sources (e.g. FEL). The demand to accelerate particles to higher and higher energies is currently limited by the effective efficiency in the acceleration process that requires the development of km-size facilities. By increasing the accelerating gradient, the compactness can be improved and costs reduced. Recently, the new technique which attracts main efforts relies on plasma acceleration. In the following, the current status of plasma-based activities at SPARC_LAB is presented. Both laser- and beam-driven schemes will be adopted with the aim to provide an adequate accelerating gradient (1-10 GV/m) while preserving the brightness of the accelerated beams to the level of conventional photo-injectors. This aspect, in particular, requires the use of ultra-short (< 100 fs) electron beams, consisting in one or more bunches. We show, with the support of simulations and experimental results, that such beams can be produced using RF compression by velocity-bunching.

Spectral and spatial characterisation of laser-driven positron beams

DOE PAGES

Sarri, G.; Warwick, J.; Schumaker, W.; ...

2016-10-18

The generation of high-quality relativistic positron beams is a central area of research in experimental physics, due to their potential relevance in a wide range of scientific and engineering areas, ranging from fundamental science to practical applications. There is now growing interest in developing hybrid machines that will combine plasma-based acceleration techniques with more conventional radio-frequency accelerators, in order to minimise the size and cost of these machines. Here we report on recent experiments on laser-driven generation of high-quality positron beams using a relatively low energy and potentially table-top laser system. Lastly, the results obtained indicate that current technology allowsmore » to create, in a compact setup, positron beams suitable for injection in radio-frequency accelerators.« less

Fatigue crack growth in 7475-T651 aluminum alloy plate in hard vacuum and water vapor. M.S. Thesis - George Washington Univ.

NASA Technical Reports Server (NTRS)

Dicus, D. L.

1981-01-01

Compact specimens of 25 mm thick aluminum alloy plate were subjected to constant amplitude fatigue testing at a load ratio of 0.2. Crack growth rates were determined at frequencies of 1 Hz and 10 Hz in hard vacuum and laboratory air, and in mixtures of water vapor and nitrogen at water vapor partial pressures ranging from 94 Pa to 3.8 kPa. A significant effect of water vapor on fatigue crack growth rates was observed at the lowest water vapor pressure tested. Crack rates changed little for pressures up to 1.03 kPa, but abruptly accelerated at higher pressures. At low stress intensity factor ranges, cracking rates at the lowest and highest water vapor pressure tested were, respectively, two and five times higher than rates in vacuum. Although a frequency was observed in laboratory air, cracking rates in water vapor and vacuum are insensitive to a ten-fold change in frequency. Surfaces of specimens tested in water vapor and vacuum exhibited different amounts of residual deformation. Reduced deformation on the fracture surfaces of the specimens tested in water vapor suggests embrittlement of the plastic zone ahead of the crack tip as a result of environmental interaction.

TU-H-BRA-01: The Physics of High Power Radiofrequency Isolation in a Novel Compact Linear Accelerator Based MRI Guided Radiation Therapy System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamb, J; Low, D; Mutic, S

Purpose: To develop a method for isolating the radiofrequency waves emanating from linear accelerator components from the magnetic resonance imaging (MRI) system of an integrated MRI-linac. Methods: An MRI-guided radiation therapy system has been designed that integrates a linear accelerator with simultaneous MR imaging. The radiofrequency waves created by the accelerating process would degrade MR image quality, so a method for containing the radiofrequency waves and isolating the MR imager from them was developed. The linear accelerator radiofrequency modulator was placed outside the room, so a filter was designed to eliminate the radiofrequency corresponding to the proton Larmour frequency ofmore » 14.7 MHz. Placing the radiofrequency emitting components in a typical Faraday cage would have reduced the radiofrequency emissions, but the design would be susceptible to small gaps in the shield due to the efficiency of the Faraday cage reflecting internal radiofrequency emissions. To reduce internal radiofrequency reflections, the Faraday cage was lined with carbon fiber sheets. Carbon fiber has the property of attenuating the radiofrequency energy so that the overall radiofrequency field inside the Faraday cage is reduced, decreasing any radiofrequency energy emitted from small gaps in the cage walls. Results: Within a 1.2 MHz band centered on the Larmor frequency, the radiofrequency (RF) leakage from the Faraday cage was measured to be −90 dB with no RF on, −40 dB with the RF on and no shield, returning to −90 dB with the RF on and shields in place. The radiofrequency filter attenuated the linear accelerator modulator emissions in the 14.7 MHz band by 70 dB. Conclusions: One of the major challenges in designing a compact linear accelerator based MRI-guided radiation therapy system, that of isolating the high power RF system from the MRI, has been solved. The measured radiofrequency emissions are sufficiently small to enable system integration. This research was funded by ViewRay, Inc., Oakwood, OH.« less

Carbon Corrosion in PEM Fuel Cells and the Development of Accelerated Stress Tests

DOE PAGES

Macauley, Natalia; Papadias, Dennis D.; Fairweather, Joseph; ...

2018-03-15

Here, carbon corrosion is an important degradation mechanism that can impair PEMFC performance through the destruction of catalyst connectivity, collapse of the electrode pore structure, loss of hydrophobic character, and an increase of the catalyst particle size. In this study, carbon corrosion was quantified in situ by measurement of carbon dioxide in the fuel cell exhaust gases through non-dispersive infrared spectroscopy during simulated drive cycle operations consisting of potential cycling with varying upper and lower potential limits. These studies were conducted for three different types of carbon supports. A reduction in the catalyst layer thickness was observed during a simulatedmore » drive cycle operation with a concomitant decrease in catalyst layer porosity, which led to performance losses due to increased mass transport limitations. The observed thickness reduction was primarily due to compaction of the catalyst layer, with the actual mass of carbon oxidation (loss) contributing only a small fraction (< 20%). The dynamics of carbon corrosion are presented along with a model that simulates the transient and dynamic corrosion rates observed in our experiments. Accelerated carbon corrosion stress tests are presented and their effects are compared to those observed for the drive cycle test.« less

Carbon Corrosion in PEM Fuel Cells and the Development of Accelerated Stress Tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Macauley, Natalia; Papadias, Dennis D.; Fairweather, Joseph

Here, carbon corrosion is an important degradation mechanism that can impair PEMFC performance through the destruction of catalyst connectivity, collapse of the electrode pore structure, loss of hydrophobic character, and an increase of the catalyst particle size. In this study, carbon corrosion was quantified in situ by measurement of carbon dioxide in the fuel cell exhaust gases through non-dispersive infrared spectroscopy during simulated drive cycle operations consisting of potential cycling with varying upper and lower potential limits. These studies were conducted for three different types of carbon supports. A reduction in the catalyst layer thickness was observed during a simulatedmore » drive cycle operation with a concomitant decrease in catalyst layer porosity, which led to performance losses due to increased mass transport limitations. The observed thickness reduction was primarily due to compaction of the catalyst layer, with the actual mass of carbon oxidation (loss) contributing only a small fraction (< 20%). The dynamics of carbon corrosion are presented along with a model that simulates the transient and dynamic corrosion rates observed in our experiments. Accelerated carbon corrosion stress tests are presented and their effects are compared to those observed for the drive cycle test.« less

Geologic effects and coastal vulnerability to sea-level rise, erosion, and storms

USGS Publications Warehouse

Williams, S.J.; Gutierrez, B.T.; Thieler, E.R.; Pendleton, E.

2008-01-01

A combination of natural and human factors are driving coastal change and making coastal regions and populations increasingly vulnerable. Sea level, a major agent of coastal erosion, has varied greatly from -120 m below present during glacial period low-stands to + 4 to 6 m above present during interglacial warm periods. Geologic and tide gauge data show that global sea level has risen about 12 to 15 cm during the past century with satellite measurements indicating an acceleration since the early 1990s due to thermal expansion and ice-sheet melting. Land subsidence due to tectonic forces and sediment compaction in regions like the mid-Atlantic and Louisiana increase the rate of relative sea-level rise to 40 cm to 100 cm per century. Sea- level rise is predicted to accelerate significantly in the near future due to climate change, resulting in pervasive impacts to coastal regions and putting populations increasingly at risk. The full implications of climate change for coastal systems need to be understood better and long-term plans are needed to manage coasts in order to protect natural resources and mitigate the effects of sea-level rise and increased storms on human infrastructure. 

Compact Spreader Schemes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Placidi, M.; Jung, J. -Y.; Ratti, A.

2014-07-25

This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibilitymore » when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.« less

Introducing a novel gravitation-based high-velocity compaction analysis method for pharmaceutical powders.

PubMed

Tanner, Timo; Antikainen, Osmo; Ehlers, Henrik; Yliruusi, Jouko

2017-06-30

With modern tableting machines large amounts of tablets are produced with high output. Consequently, methods to examine powder compression in a high-velocity setting are in demand. In the present study, a novel gravitation-based method was developed to examine powder compression. A steel bar is dropped on a punch to compress microcrystalline cellulose and starch samples inside the die. The distance of the bar is being read by a high-accuracy laser displacement sensor which provides a reliable distance-time plot for the bar movement. In-die height and density of the compact can be seen directly from this data, which can be examined further to obtain information on velocity, acceleration and energy distribution during compression. The energy consumed in compact formation could also be seen. Despite the high vertical compression speed, the method was proven to be cost-efficient, accurate and reproducible. Copyright © 2017 Elsevier B.V. All rights reserved.

Single-stage plasma-based correlated energy spread compensation for ultrahigh 6D brightness electron beams

PubMed Central

Manahan, G. G.; Habib, A. F.; Scherkl, P.; Delinikolas, P.; Beaton, A.; Knetsch, A.; Karger, O.; Wittig, G.; Heinemann, T.; Sheng, Z. M.; Cary, J. R.; Bruhwiler, D. L.; Rosenzweig, J. B.; Hidding, B.

2017-01-01

Plasma photocathode wakefield acceleration combines energy gains of tens of GeV m−1 with generation of ultralow emittance electron bunches, and opens a path towards 5D-brightness orders of magnitude larger than state-of-the-art. This holds great promise for compact accelerator building blocks and advanced light sources. However, an intrinsic by-product of the enormous electric field gradients inherent to plasma accelerators is substantial correlated energy spread—an obstacle for key applications such as free-electron-lasers. Here we show that by releasing an additional tailored escort electron beam at a later phase of the acceleration, when the witness bunch is relativistically stable, the plasma wave can be locally overloaded without compromising the witness bunch normalized emittance. This reverses the effective accelerating gradient, and counter-rotates the accumulated negative longitudinal phase space chirp of the witness bunch. Thereby, the energy spread is reduced by an order of magnitude, thus enabling the production of ultrahigh 6D-brightness beams. PMID:28580954

Single-stage plasma-based correlated energy spread compensation for ultrahigh 6D brightness electron beams

NASA Astrophysics Data System (ADS)

Manahan, G. G.; Habib, A. F.; Scherkl, P.; Delinikolas, P.; Beaton, A.; Knetsch, A.; Karger, O.; Wittig, G.; Heinemann, T.; Sheng, Z. M.; Cary, J. R.; Bruhwiler, D. L.; Rosenzweig, J. B.; Hidding, B.

2017-06-01

Plasma photocathode wakefield acceleration combines energy gains of tens of GeV m-1 with generation of ultralow emittance electron bunches, and opens a path towards 5D-brightness orders of magnitude larger than state-of-the-art. This holds great promise for compact accelerator building blocks and advanced light sources. However, an intrinsic by-product of the enormous electric field gradients inherent to plasma accelerators is substantial correlated energy spread--an obstacle for key applications such as free-electron-lasers. Here we show that by releasing an additional tailored escort electron beam at a later phase of the acceleration, when the witness bunch is relativistically stable, the plasma wave can be locally overloaded without compromising the witness bunch normalized emittance. This reverses the effective accelerating gradient, and counter-rotates the accumulated negative longitudinal phase space chirp of the witness bunch. Thereby, the energy spread is reduced by an order of magnitude, thus enabling the production of ultrahigh 6D-brightness beams.

Compact compressive arc and beam switchyard for energy recovery linac-driven ultraviolet free electron lasers

NASA Astrophysics Data System (ADS)

Akkermans, J. A. G.; Di Mitri, S.; Douglas, D.; Setija, I. D.

2017-08-01

High gain free electron lasers (FELs) driven by high repetition rate recirculating accelerators have received considerable attention in the scientific and industrial communities in recent years. Cost-performance optimization of such facilities encourages limiting machine size and complexity, and a compact machine can be realized by combining bending and bunch length compression during the last stage of recirculation, just before lasing. The impact of coherent synchrotron radiation (CSR) on electron beam quality during compression can, however, limit FEL output power. When methods to counteract CSR are implemented, appropriate beam diagnostics become critical to ensure that the target beam parameters are met before lasing, as well as to guarantee reliable, predictable performance and rapid machine setup and recovery. This article describes a beam line for bunch compression and recirculation, and beam switchyard accessing a diagnostic line for EUV lasing at 1 GeV beam energy. The footprint is modest, with 12 m compressive arc diameter and ˜20 m diagnostic line length. The design limits beam quality degradation due to CSR both in the compressor and in the switchyard. Advantages and drawbacks of two switchyard lines providing, respectively, off-line and on-line measurements are discussed. The entire design is scalable to different beam energies and charges.

UH-FLUX: Compact, Energy Efficient Superconducting Asymmetric Energy Recovery LINAC for Ultra-high Fluxes of X-ray and THz Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konoplev, Ivan; Ainsworth, Robert; Burt, Graeme

The conventional ERLs have limited peak beam current because increasing the beam charge and repetition rate leads to appearance of the beam break-up instabilities. At this stage the highest current, from the SRF ERL, is around 300 mA. A single-turn (the beam will be transported through the accelerating section, interaction point and deceleration section of the AERL only once) Asymmetric Energy Recovery LINAC (AERL) is proposed. The RF cells in different sections of the cavity are tuned in such a way that only operating mode is uniform inside all of the cells. The AERL will drive the electron beams withmore » typical energies of 10 - 30 MeV and peak currents above 1 A, enabling the generation of high flux UV/X-rays and high power coherent THz radiation. We aim to build a copper prototype of the RF cavity for a compact AERL to study its EM properties. The final goal is to build AERL based on the superconducting RF cavity. Preliminary design for AERL's cavity has been developed and will be presented. The results of numerical and analytical models and the next steps toward the AERL operation will also be discussed.« less

Different Solutions for the Generator-accelerator Module

NASA Astrophysics Data System (ADS)

Savin, E. A.; Matsievskiy, S. V.; Sobenin, N. P.; Zavadtsev, A. A.; Zavadtsev, D. A.

The most important part of the particle accelerators [1] - is the power generator together with the whole feeding system [2]. All types of generators, such as klystrons, magnetrons, solid state generators cover their own field of power and pulse length values. For the last couple of year the Inductive Output Tubes (IOT) becomes very popular because of their comparative construction simplicity: it represents the klystron output cavity with the grid modulated electron beam injected in it. Now such IOTs are used with the superconductive particle accelerators at 700 MHz operating frequency with around 1MW output power. Higher frequencies problem - is the inability to apply high frequency modulated voltage to the grid. Thus we need to figure out some kind of RF gun. But this article is about the first steps of the geometry and beam dynamics simulation in the six beam S-band IOT, which will be used with the compact biperiodic accelerating structure.

Compact laser accelerators for X-ray phase-contrast imaging

PubMed Central

Najmudin, Z.; Kneip, S.; Bloom, M. S.; Mangles, S. P. D.; Chekhlov, O.; Dangor, A. E.; Döpp, A.; Ertel, K.; Hawkes, S. J.; Holloway, J.; Hooker, C. J.; Jiang, J.; Lopes, N. C.; Nakamura, H.; Norreys, P. A.; Rajeev, P. P.; Russo, C.; Streeter, M. J. V.; Symes, D. R.; Wing, M.

2014-01-01

Advances in X-ray imaging techniques have been driven by advances in novel X-ray sources. The latest fourth-generation X-ray sources can boast large photon fluxes at unprecedented brightness. However, the large size of these facilities means that these sources are not available for everyday applications. With advances in laser plasma acceleration, electron beams can now be generated at energies comparable to those used in light sources, but in university-sized laboratories. By making use of the strong transverse focusing of plasma accelerators, bright sources of betatron radiation have been produced. Here, we demonstrate phase-contrast imaging of a biological sample for the first time by radiation generated by GeV electron beams produced by a laser accelerator. The work was performed using a greater than 300 TW laser, which allowed the energy of the synchrotron source to be extended to the 10–100 keV range. PMID:24470414

Multistage Coupling of Laser-Wakefield Accelerators with Curved Plasma Channels.

PubMed

Luo, J; Chen, M; Wu, W Y; Weng, S M; Sheng, Z M; Schroeder, C B; Jaroszynski, D A; Esarey, E; Leemans, W P; Mori, W B; Zhang, J

2018-04-13

Multistage coupling of laser-wakefield accelerators is essential to overcome laser energy depletion for high-energy applications such as TeV-level electron-positron colliders. Current staging schemes feed subsequent laser pulses into stages using plasma mirrors while controlling electron beam focusing with plasma lenses. Here a more compact and efficient scheme is proposed to realize the simultaneous coupling of the electron beam and the laser pulse into a second stage. A partly curved channel, integrating a straight acceleration stage with a curved transition segment, is used to guide a fresh laser pulse into a subsequent straight channel, while the electrons continue straight. This scheme benefits from a shorter coupling distance and continuous guiding of the electrons in plasma while suppressing transverse beam dispersion. Particle-in-cell simulations demonstrate that the electron beam from a previous stage can be efficiently injected into a subsequent stage for further acceleration while maintaining high capture efficiency, stability, and beam quality.

Multistage Coupling of Laser-Wakefield Accelerators with Curved Plasma Channels

NASA Astrophysics Data System (ADS)

Luo, J.; Chen, M.; Wu, W. Y.; Weng, S. M.; Sheng, Z. M.; Schroeder, C. B.; Jaroszynski, D. A.; Esarey, E.; Leemans, W. P.; Mori, W. B.; Zhang, J.

2018-04-01

Multistage coupling of laser-wakefield accelerators is essential to overcome laser energy depletion for high-energy applications such as TeV-level electron-positron colliders. Current staging schemes feed subsequent laser pulses into stages using plasma mirrors while controlling electron beam focusing with plasma lenses. Here a more compact and efficient scheme is proposed to realize the simultaneous coupling of the electron beam and the laser pulse into a second stage. A partly curved channel, integrating a straight acceleration stage with a curved transition segment, is used to guide a fresh laser pulse into a subsequent straight channel, while the electrons continue straight. This scheme benefits from a shorter coupling distance and continuous guiding of the electrons in plasma while suppressing transverse beam dispersion. Particle-in-cell simulations demonstrate that the electron beam from a previous stage can be efficiently injected into a subsequent stage for further acceleration while maintaining high capture efficiency, stability, and beam quality.

Modeling multi-GeV class laser-plasma accelerators with INF&RNO

NASA Astrophysics Data System (ADS)

Benedetti, Carlo; Schroeder, Carl; Bulanov, Stepan; Geddes, Cameron; Esarey, Eric; Leemans, Wim

2016-10-01

Laser plasma accelerators (LPAs) can produce accelerating gradients on the order of tens to hundreds of GV/m, making them attractive as compact particle accelerators for radiation production or as drivers for future high-energy colliders. Understanding and optimizing the performance of LPAs requires detailed numerical modeling of the nonlinear laser-plasma interaction. We present simulation results, obtained with the computationally efficient, PIC/fluid code INF&RNO (INtegrated Fluid & paRticle simulatioN cOde), concerning present (multi-GeV stages) and future (10 GeV stages) LPA experiments performed with the BELLA PW laser system at LBNL. In particular, we will illustrate the issues related to the guiding of a high-intensity, short-pulse, laser when a realistic description for both the laser driver and the background plasma is adopted. Work Supported by the U.S. Department of Energy under contract No. DE-AC02-05CH11231.

XCAMS: The compact 14C accelerator mass spectrometer extended for 10Be and 26Al at GNS Science, New Zealand

NASA Astrophysics Data System (ADS)

Zondervan, A.; Hauser, T. M.; Kaiser, J.; Kitchen, R. L.; Turnbull, J. C.; West, J. G.

2015-10-01

A detailed description is given of the 0.5 MV tandem accelerator mass spectrometry (AMS) system for 10Be, 14C, 26Al, installed in early 2010 at GNS Science, New Zealand. Its design follows that of previously commissioned Compact 14C-only AMS (CAMS) systems based on the Pelletron tandem accelerator. The only basic departure from that design is an extension of the rare-isotope achromat with a 45° magnet and a two-anode gas-ionisation detector, to provide additional filtering for 10Be. Realised performance of the three AMS modes is discussed in terms of acceptance-test scores, 14C Poisson and non-Poisson errors, and 10Be detection limit and sensitivity. Operational details and hardware improvements, such as 10Be beam transport and particle detector setup, are highlighted. Statistics of repeat measurements of all graphitised 14C calibration cathodes since start-up show that 91% of their total uncertainty values are less than 0.3%, indicating that the rare-isotope beamline extension has not affected precision of 14C measurement. For 10Be, the limit of detection in terms of the isotopic abundance ratio 10Be/9Be is 6 × 10-15 at at-1 and the total efficiency of counting atoms in the sample cathode is 1/8500 (0.012%).

A Fabry-Pérot interferometer with wire-grid polarizers as beamsplitters at terahertz frequencies

NASA Astrophysics Data System (ADS)

Harrison, H.; Lancaster, A. J.; Konoplev, I. V.; Doucas, G.; Aryshev, A.; Shevelev, M.; Terunuma, N.; Urakawa, J.; Huggard, P. G.

2018-03-01

The design of a compact Fabry-Pérot interferometer (FPi) and results of the experimental studies carried out using the device are presented. Our FPi uses freestanding wire-grid polarizers (WGPs) as beamsplitters and is suitable for use at terahertz (THz) frequencies. The FPi was studied at the LUCX facility, KEK, Japan, and an 8 MeV linear electron accelerator was used to generate coherent Smith-Purcell radiation. The FPi was designed to be easy to align and reposition for experiments at linear accelerator facilities. All of the components used were required to have a flat or well understood frequency response in the THz range. The performance of the FPi with WGPs was compared to that of a Michelson interferometer and the FPi is seen to perform well. The effectiveness of the beamsplitters used in the FPi is also investigated. Measurements made with the FPi using WGPs, the preferred beamsplitters, are compared to measurements made with the FPi using silicon wafers as alternative beamsplitters. The FPi performs well with both types of beamsplitter in the frequency range used (0.3-0.5 THz). The successful measurements taken with the FPi demonstrate a compact and adaptable interferometer that is capable of analyzing THz radiation over a broad frequency range. The scheme is particularly well suited for polarization studies of THz radiation produced in an accelerator environment.

Fermilab Heroes of the LHC: Joel Butler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butler, Joel

2017-08-23

Particle physics research is both international and collaborative, with large national laboratories working together to most efficiently advance science. Joel Butler, Distinguished Scientist at Fermi National Accelerator Laboratory is the leader of the Compact Muon Solenoid experiment at the CERN laboratory in Europe. In this video, Joel tells us a bit about what it’s like.

Particle beam and crabbing and deflecting structure

DOEpatents

Delayen, Jean [Yorktown, VA

2011-02-08

A new type of structure for the deflection and crabbing of particle bunches in particle accelerators comprising a number of parallel transverse electromagnetic (TEM)-resonant) lines operating in opposite phase from each other. Such a structure is significantly more compact than conventional crabbing cavities operating the transverse magnetic TM mode, thus allowing low frequency designs.

Development of a magnetized coaxial plasma gun for compact toroid injection into the C-2 field-reversed configuration device.

PubMed

Matsumoto, T; Sekiguchi, J; Asai, T; Gota, H; Garate, E; Allfrey, I; Valentine, T; Morehouse, M; Roche, T; Kinley, J; Aefsky, S; Cordero, M; Waggoner, W; Binderbauer, M; Tajima, T

2016-05-01

A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode. A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10(21) m(-3), ∼40 eV, and 0.5-1.0 × 10(19), respectively.

Gyrotron-driven high current ECR ion source for boron-neutron capture therapy neutron generator

NASA Astrophysics Data System (ADS)

Skalyga, V.; Izotov, I.; Golubev, S.; Razin, S.; Sidorov, A.; Maslennikova, A.; Volovecky, A.; Kalvas, T.; Koivisto, H.; Tarvainen, O.

2014-12-01

Boron-neutron capture therapy (BNCT) is a perspective treatment method for radiation resistant tumors. Unfortunately its development is strongly held back by a several physical and medical problems. Neutron sources for BNCT currently are limited to nuclear reactors and accelerators. For wide spread of BNCT investigations more compact and cheap neutron source would be much more preferable. In present paper an approach for compact D-D neutron generator creation based on a high current ECR ion source is suggested. Results on dense proton beams production are presented. A possibility of ion beams formation with current density up to 600 mA/cm2 is demonstrated. Estimations based on obtained experimental results show that neutron target bombarded by such deuteron beams would theoretically yield a neutron flux density up to 6·1010 cm-2/s. Thus, neutron generator based on a high-current deuteron ECR source with a powerful plasma heating by gyrotron radiation could fulfill the BNCT requirements significantly lower price, smaller size and ease of operation in comparison with existing reactors and accelerators.

Status of the development of Delhi Light Source (DLS) at IUAC

NASA Astrophysics Data System (ADS)

Ghosh, S.; Joshi, V.; Urakawa, J.; Terunuma, N.; Aryshev, A.; Fukuda, S.; Fukuda, M.; Sahu, B. K.; Patra, P.; Abhilash, S. R.; Karmakar, J.; Karmakar, B.; Kabiraj, D.; Kumar, N.; Sharma, A.; Chaudhari, G. K.; Pandey, A.; Tripathi, S.; Deshpande, A.; Naik, V.; Roy, A.; Rao, T.; Bhandari, R. K.; Kanjilal, D.

2017-07-01

A project to construct a compact pre-bunched Free Electron Laser by using a normal conducting photocathode electron gun has been undertaken at Inter University Accelerator Centre (IUAC), New Delhi, India. In this facility, the short laser pulses from a high power laser system will be split into many pulses (2-16) commonly known as 'Comb beam' and will strike the photocathode material (metal and semiconductor) to produce electron beam bunches. The electrons will be accelerated up to an energy of ∼8 MeV by a copper cavity operated at a frequency of 2860 MHz and the beam will be injected into a compact, planar permanent undulator magnet to produce THz radiation. The radiation frequency designed to be tuned in the range of 0.15-3 THz by varying the magnetic field of the undulator and/or changing the energy of the electron. The separation of the laser micro-pulses will be varied by adjusting the path length difference to alter the separation of the electron micro-bunches and to maximise the radiation intensity.

Euler force actuation mechanism for siphon valving in compact disk-like microfluidic chips.

PubMed

Deng, Yongbo; Fan, Jianhua; Zhou, Song; Zhou, Teng; Wu, Junfeng; Li, Yin; Liu, Zhenyu; Xuan, Ming; Wu, Yihui

2014-03-01

Based on the Euler force induced by the acceleration of compact disk (CD)-like microfluidic chip, this paper presents a novel actuation mechanism for siphon valving. At the preliminary stage of acceleration, the Euler force in the tangential direction of CD-like chip takes the primary place compared with the centrifugal force to function as the actuation of the flow, which fills the siphon and actuates the siphon valving. The Euler force actuation mechanism is demonstrated by the numerical solution of the phase-field based mathematical model for the flow in siphon valve. In addition, experimental validation is implemented in the polymethylmethacrylate-based CD-like microfluidic chip manufactured using CO2 laser engraving technique. To prove the application of the proposed Euler force actuation mechanism, whole blood separation and plasma extraction has been conducted using the Euler force actuated siphon valving. The newly introduced actuation mechanism overcomes the dependence on hydrophilic capillary filling of siphon by avoiding external manipulation or surface treatments of polymeric material. The sacrifice for highly integrated processing in pneumatic pumping technique is also prevented by excluding the volume-occupied compressed air chamber.

The goals of gamma-ray spectroscopy in high energy astrophysics

NASA Technical Reports Server (NTRS)

Lingenfelter, Richard E.; Higdon, James C.; Leventhal, Marvin; Ramaty, Reuven; Woosley, Stanford E.

1990-01-01

The use of high resolution gamma-ray spectroscopy in astrophysics is discussed with specific attention given to the application of the Nuclear Astrophysics Explorer (NAE). The gamma-ray lines from nuclear transitions in radionucleic decay and positron annihilation permits the study of current sites, rates and models of nucleosynthesis, and galactic structure. Diffuse galactic emission is discussed, and the high-resolution observations of gamma-ray lines from discrete sites are also described. Interstellar mixing and elemental abundances can also be inferred from high-resolution gamma-ray spectroscopy of nucleosynthetic products. Compact objects can also be examined by means of gamma-ray emissions, allowing better understanding of neutron stars and the accreting black hole near the galactic center. Solar physics can also be investigated by examining such features as solar-flare particle acceleration and atmospheric abundances.

Acceleration of a trailing positron bunch in a plasma wakefield accelerator

DOE PAGES

Doche, A.; Beekman, C.; Corde, S.; ...

2017-10-27

High gradients of energy gain and high energy efficiency are necessary parameters for compact, cost-efficient and high-energy particle colliders. Plasma Wakefield Accelerators (PWFA) offer both, making them attractive candidates for next-generation colliders. Here in these devices, a charge-density plasma wave is excited by an ultra-relativistic bunch of charged particles (the drive bunch). The energy in the wave can be extracted by a second bunch (the trailing bunch), as this bunch propagates in the wake of the drive bunch. While a trailing electron bunch was accelerated in a plasma with more than a gigaelectronvolt of energy gain, accelerating a trailing positronmore » bunch in a plasma is much more challenging as the plasma response can be asymmetric for positrons and electrons. We report the demonstration of the energy gain by a distinct trailing positron bunch in a plasma wakefield accelerator, spanning nonlinear to quasi-linear regimes, and unveil the beam loading process underlying the accelerator energy efficiency. A positron bunch is used to drive the plasma wake in the experiment, though the quasi-linear wake structure could as easily be formed by an electron bunch or a laser driver. Finally, the results thus mark the first acceleration of a distinct positron bunch in plasma-based particle accelerators.« less

Acceleration of a trailing positron bunch in a plasma wakefield accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doche, A.; Beekman, C.; Corde, S.

High gradients of energy gain and high energy efficiency are necessary parameters for compact, cost-efficient and high-energy particle colliders. Plasma Wakefield Accelerators (PWFA) offer both, making them attractive candidates for next-generation colliders. Here in these devices, a charge-density plasma wave is excited by an ultra-relativistic bunch of charged particles (the drive bunch). The energy in the wave can be extracted by a second bunch (the trailing bunch), as this bunch propagates in the wake of the drive bunch. While a trailing electron bunch was accelerated in a plasma with more than a gigaelectronvolt of energy gain, accelerating a trailing positronmore » bunch in a plasma is much more challenging as the plasma response can be asymmetric for positrons and electrons. We report the demonstration of the energy gain by a distinct trailing positron bunch in a plasma wakefield accelerator, spanning nonlinear to quasi-linear regimes, and unveil the beam loading process underlying the accelerator energy efficiency. A positron bunch is used to drive the plasma wake in the experiment, though the quasi-linear wake structure could as easily be formed by an electron bunch or a laser driver. Finally, the results thus mark the first acceleration of a distinct positron bunch in plasma-based particle accelerators.« less

BINP accelerator based epithermal neutron source.

PubMed

Aleynik, V; Burdakov, A; Davydenko, V; Ivanov, A; Kanygin, V; Kuznetsov, A; Makarov, A; Sorokin, I; Taskaev, S

2011-12-01

Innovative facility for neutron capture therapy has been built at BINP. This facility is based on compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915-2.5 MeV protons bombarding a lithium target using (7)Li(p,n)(7)Be threshold reaction. In the article, diagnostic techniques for proton beam and neutrons developed are described, results of experiments on proton beam transport and neutron generation are shown, discussed, and plans are presented. Copyright © 2011 Elsevier Ltd. All rights reserved.

Conceptual Design for CLIC Gun Pulser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Tao

The Compact Linear Collider (CLIC) is a proposed future electron-positron collider, designed to perform collisions at energies from 0.5 to 5 TeV, with a nominal design optimized for 3 TeV (Dannheim, 2012). The Drive Beam Accelerator consists of a thermionic DC gun, bunching section and an accelerating section. The thermionic gun needs deliver a long (~143us) pulse of current into the buncher. A pulser is needed to drive grid of the gun to generate a stable current output. This report explores the requirements of the gun pulser and potential solutions to regulate grid current.

Water-level altitudes 2015 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2014 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Ramage, Jason K.; Houston, Natalie A.; Johnson, Michaela R.; Schmidt, Tiffany S.

2015-01-01

Compaction of subsurface sediments (mostly in the fine-grained silt and clay layers) composing the Chicot and Evangeline aquifers was recorded continuously by using analog technology at the 13 borehole extensometers at 11 sites that were either activated or installed between 1973 and 1980. For the period of record beginning in 1973 (or later depending on activation or installation date) and ending in December 2014, measured cumulative compaction at the 13 extensometers ranged from 0.101 ft at the Texas City-Moses Lake extensometer to 3.668 ft at the Addicks extensometer. During 2014, a total of 10 of the 13 extensometers recorded a slight net decrease of land-surface elevation; the extensometers at the Lake Houston and Clear Lake (shallow) sites recorded slight net increases of land-surface elevation, and the extensometer at the Texas City-Moses Lake site recorded no change in elevation. The rate of compaction varies from site to site because of differences in rates of groundwater withdrawal in the areas adjacent to each extensometer site and differences among sites in the ratios of sand, silt, and clay and compressibilities of the subsurface sediments. It is not appropriate, therefore, to extrapolate or infer a rate of compaction for an adjacent area on the basis of the rate of compaction measured at nearby extensometers.

Prospects for compact high-intensity laser synchrotron x-ray and gamma sources

NASA Astrophysics Data System (ADS)

Pogorelsky, I. V.

1997-03-01

A laser interacting with a relativistic electron beam behaves like a virtual wiggler of an extremely short period equal to half of the laser wavelength. This approach opens a route to relatively compact, high-brightness x-ray sources alternative or complementary to conventional synchrotron light sources. Although not new, the laser synchrotron source (LSS) concept is still waiting for a convincing demonstration. Available at the BNL Accelerator Test Facility (ATF), a high-brightness electron beam and the high-power CO2 laser may be used for prototype LSS demonstration. In a feasible demonstration experiment, 10-GW, 100-ps CO2 laser beam will be brought to a head-on collision with a 10-ps, 0.5-nC, 50 MeV electron bunch. Flashes of collimated 4.7 keV (2.6 Å) x-rays of 10-ps pulse duration, with a flux of ˜1019photons/sec, will be produced via linear Compton backscattering. The x-ray spectrum is tunable proportionally to the e-beam energy. A rational short-term extension of the proposed experiment would be further enhancement of the x-ray flux to the 1022 photons/sec level, after the ongoing ATF CO2 laser upgrade to 5 TW peak power and electron bunch shortening to 3 ps is realized. In the future, exploiting the promising approach of a high-gradient laser wake field accelerator, a compact "table-top" LSS of monochromatic gamma radiation may become feasible.

[A study of the properties of compacts from a mixed dry binder on the base of alpha-lactose monohydrate and microcrystalline cellulose].

PubMed

Muzíková, J; Páleník, L

2005-05-01

The paper studies the tensile strength and disintegration time of compacts from the mixed dry binder MicroceLac 100. Tensile strength and disintegration time of tablets were tested in connection with the following factors: compression force, compression rate, addition of magnesium stearate, addition of ascorbic acid, the model active principle. The compression forces employed were 5, 6, and 7 kN, compression rates, 20 and 40 mm/min, stearate concentration 0, 0.4, and 0.8%, ascorbic acid concentration, 25 and 50%. With increasing addition of the stearate, the strength of compacts from MicroceLacu 100 was decreased for both compression rates, but with a higher rate, in a concentration of 0.4%, the decrease in strength was more marked. Disintegration time was increased with compression force and the addition of the stearate, but in all cases it was very short. Increased addition of ascorbic acid further intensified the decrease in the strength of compacts and decreased the disintegration time and the effect of the stearate on it. Disintegration time of compacts with ascorbic acid in a concentration of 50% did not increase with compression force.

Design, Construction, and Test of a 473 MHZ Four - Cavity Rfq.

NASA Astrophysics Data System (ADS)

Kazimi, Reza

1992-01-01

An RFQ accelerator using the new four-rod cavity design has been fabricated and successfully tested at Texas Accelerator Center. The RFQ is designed to accelerate a 10 mA H^- ion beam from 30 keV to 500 keV with the operating frequency of 473 MHz. This new type of RFQ structure not only promises simplicity of design, construction, and operation, but also can be manufactured to operate at higher frequencies than previously achieved by other four-rod type RFQs. Combination of simplicity and compactness due to higher operating frequencies (400 to 500 MHz) makes the design desirable for injector of proton accelerators, medical linear accelerators, and variety of other applications. This dissertation presents the steps I went through in inventing, developing, and experimentally testing this new RFQ design. First an introduction to accelerators is given, and the basic accelerator physics terminologies are defined. The principles of operations of the RFQs are described, and the theory behind new type of RFQ structure is explained. Then the beam dynamics and cavity design of the RFQ are presented. Finally, the mechanical design and construction procedure are discussed, and experimental results of rf tests and actual H ^- beam test are given.

Roller compaction of different pseudopolymorphic forms of theophylline: Effect on compressibility and tablet properties.

PubMed

Hadzović, Ervina; Betz, Gabriele; Hadzidedić, Seherzada; El-Arini, Silvia Kocova; Leuenberger, Hans

2010-08-30

The effect of roller compaction on disintegration time, dissolution rate and compressibility of tablets prepared from theophylline anhydrate powder, theophylline anhydrate fine powder and theophylline monohydrate was studied. In addition, the influence of adding microcrystalline cellulose, a commonly used excipient, in mixtures with these materials was investigated. Theophylline anhydrate powder was used as a model drug to investigate the influence of different compaction pressures on the tablet properties. Tablets with same porosity were prepared by direct compaction and by roller compaction/re-compaction. Compressibility was characterized by Heckel and modified Heckel equations. Due to the property of polymorphic materials to change their form during milling and compression, X-ray diffraction analysis of theophylline anhydrate powder, theophylline anhydrate fine powder and theophylline monohydrate powders and granules was carried out. After roller compaction the disintegration time and the dissolution rate of the tablets were significantly improved. Compressibility of theophylline anhydrate powder and theophylline anhydrate fine powder was decreased, while theophylline monohydrate showed higher compressibility after roller compaction. Microcrystalline cellulose affected compressibility of theophylline anhydrate powder, theophylline anhydrate fine powder and theophylline monohydrate whereby the binary mixtures showed higher compressibility than the individual materials. X-ray diffraction analyses confirmed that there were no polymorphic/pseudopolymorphic changes after roller compaction. Copyright 2010 Elsevier B.V. All rights reserved.

Effects of forming temperature and sintering rate to the final properties of FeCuAl powder compacts formed through uniaxial die compaction process

NASA Astrophysics Data System (ADS)

Rahman, M. M.; Ismail, M. A.; Sopyan, I.; Rahman, H. Y.

2018-01-01

This paper presents the outcomes of an experimental investigation on the effects of forming temperature and sintering schedule to the final characteristics of FeCuAl powder mass formed at different temperature and sintered at different schedule. A lab-scale uni-axial die compaction rig was designed and fabricated which enabled the compaction of powder mass at room temperature as well as elevated temperature. Iron (Fe) powder ASC 100.29 was mechanically mixed with other elemental powders, namely copper (Cu), and aluminum (Al) for 60 minutes and compacted at three different temperature, i.e., 30°C, 150°C, and 200°C by applying 425 MPa of simultaneous downward and upward axial loading to generate green compacts. The as-pressed samples were inspected visually and the defect-free green compacts were subsequently sintered in an argon gas fired furnace at 800°C for 60 min at three different heating/cooling rates, i.e., 5, 10, and 15°C/min, respectively. The sintered samples were then characterised for their physical, electrical, and mechanical properties. The microstructures of the sintered samples were also analysed. The results revealed that a forming temperature of 150°C and a sintering rate of 10°C/min could produce a product with better characteristics.

Diamond field emitter array cathodes and possibilities for employing additive manufacturing for dielectric laser accelerating structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simakov, Evgenya Ivanovna; Andrews, Heather Lynn; Herman, Matthew Joseph

2016-09-20

These are slides for a presentation at Stanford University. The outline is as follows: Motivation: customers for compact accelerators, LANL's technologies for laser acceleration, DFEA cathodes, and additive manufacturing of micron-size structures. Among the stated conclusions are the following: preliminary study identified DFEA cathodes as promising sources for DLAs--high beam current and small emittance; additive manufacturing with Nanoscribe Professional GT can produce structures with the right scale features for a DLA operating at micron wavelengths (fabrication tolerances need to be studied, DLAs require new materials). Future plans include DLA experiment with a beam produced by the DFEA cathode with fieldmore » emission, demonstration of photoemission from DFEAs, and new structures to print and test.« less

Optically controlled laser-plasma electron accelerator for compact gamma-ray sources

NASA Astrophysics Data System (ADS)

Kalmykov, S. Y.; Davoine, X.; Ghebregziabher, I.; Shadwick, B. A.

2018-02-01

Generating quasi-monochromatic, femtosecond γ-ray pulses via Thomson scattering (TS) demands exceptional electron beam (e-beam) quality, such as percent-scale energy spread and five-dimensional brightness over 1016 A m-2. We show that near-GeV e-beams with these metrics can be accelerated in a cavity of electron density, driven with an incoherent stack of Joule-scale laser pulses through a mm-size, dense plasma (n 0 ˜ 1019 cm-3). Changing the time delay, frequency difference, and energy ratio of the stack components controls the e-beam phase space on the femtosecond scale, while the modest energy of the optical driver helps afford kHz-scale repetition rate at manageable average power. Blue-shifting one stack component by a considerable fraction of the carrier frequency makes the stack immune to self-compression. This, in turn, minimizes uncontrolled variation in the cavity shape, suppressing continuous injection of ambient plasma electrons, preserving a single, ultra-bright electron bunch. In addition, weak focusing of the trailing component of the stack induces periodic injection, generating, in a single shot, a train of bunches with controllable energy spacing and femtosecond synchronization. These designer e-beams, inaccessible to conventional acceleration methods, generate, via TS, gigawatt γ-ray pulses (or multi-color pulse trains) with the mean energy in the range of interest for nuclear photonics (4-16 MeV), containing over 106 photons within a microsteradian-scale observation cone.

I. Final Report for DOE SBIR Phase I Project DE-SC0013795 Final Report for DOE SBIR Phase I Project DE-SC0013795 Microtron-based Compact, Portable Gamma-Ray Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abrams, Robert J.

Microtron-based Compact, Portable Gamma-Ray Source. The objective of Phase I of this project was to produce a conceptual design of a prototype compact microtron electron accelerator, which could be designed, built, and demonstrated in Phase II of the project. The conceptual design study included an analysis of the parameters of the microtron and its components, and the expected performance of the prototype microtron as a source of x-rays and/or RF neutrons in the MeV energy range. The major components of the microtron are the magnet, the accelerating system, the power system, the vacuum system, the control system, the beam extractionmore » system and the targets to produce x-rays (and/or neutrons). Our objectives for the design of the prototype were for it to be compact, cost-effective, capable of producing high intensity x-ray (an/or neutron) fluxes. In addition, the prototype was to be easily assembled and disassembled so that components could be easily replaced. The main parameters for the prototype are the following: the range of electron kinetic energies, the output power, the RF frequency band (X-band, C-band, or S-Band), the type of injection (Type I or Type II), the magnet type, i.e. permanent magnet, electromagnet, or a hybrid combination of permanent and electromagnet. The results of the Phase I study and analysis for a prototype microtron are the following: The electron energy range can be varied from below 6 MeV to 9 MeV, the optimal frequency range is S-Band (2-4 GHz) RF frequency, Type II injection (described below), and the magnet type is the hybrid version. The prototype version will be capable of producing gamma ray doses of ~1800 R/min-m and neutron fluxes of up to ~6 x 10 10 n/s with appropriate targets. The results of the Phase I study and analysis are provided below. The proposed Phase II plan was to demonstrate the prototype at low beam power. In the subsequent Phase III, high power tests would be performed, and the design of commercial versions of microtrons with various energies, sizes and types would be produced and marketed, including a more compact and more portable 6 MeV battery-powered model that more closely meets the requirements in the original FOA topic description. In the course of the Phase I study, we also identified another microtron version, one that was larger (not compact) and more powerful than that of the Phase II prototype, which could serve as an intense source of photo- neutrons, up to 4 x 10 12 n/s for use in nuclear medicine, short-lived isotope production, or other applications. In addition, it could produce gamma dose rates up to 130 kR/min-m with a heavy metal bremsstrahlung target. The results and specifications of this were submitted to IPAC16 (Reference [12]) the paper is included in Addendum B. Because this version was beyond the scope of the Phase I project, there is no additional description in the Final Report.« less

Bunch length compression method for free electron lasers to avoid parasitic compressions

DOEpatents

Douglas, David R.; Benson, Stephen; Nguyen, Dinh Cong; Tennant, Christopher; Wilson, Guy

2015-05-26

A method of bunch length compression method for a free electron laser (FEL) that avoids parasitic compressions by 1) applying acceleration on the falling portion of the RF waveform, 2) compressing using a positive momentum compaction (R.sub.56>0), and 3) compensating for aberration by using nonlinear magnets in the compressor beam line.

Fast Track Initiative: Building a Global Compact for Education. Education Notes

ERIC Educational Resources Information Center

Human Development Network Education, 2005

2005-01-01

This note series is intended to summarize lessons learned and key policy findings on the World Bank's work in education. "Fast Track Initiative" ("FTI") was launched in 2002 as a partnership between donor and developing countries to accelerate progress towards the Millennium Development Goal (MDG) of universal primary education. "FTI" is built on…

Instrument Records And Plays Back Acceleration Signals

NASA Technical Reports Server (NTRS)

Bozeman, Richard J.

1994-01-01

Small, battery-powered, hand-held instrument feeds power to accelerometer and records time-varying component of output for 15 seconds in analog form. No power needed to maintain content of memory; memory chip removed after recording and stored indefinitely. Recorded signal plays back at any time up to several years later. Principal advantages: compactness, portability, and low cost.

10 CFR Appendix W to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Medium Base Compact Fluorescent Lamps

Code of Federal Regulations, 2010 CFR

2010-01-01

... of Medium Base Compact Fluorescent Lamps W Appendix W to Subpart B of Part 430 Energy DEPARTMENT OF... Consumption of Medium Base Compact Fluorescent Lamps 1. Scope: This appendix covers the test requirements used... rated life, rapid cycle stress, and lamp life of medium base compact fluorescent lamps. 2. Definitions...

10 CFR Appendix W to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Medium Base Compact Fluorescent Lamps

Code of Federal Regulations, 2012 CFR

2012-01-01

... of Medium Base Compact Fluorescent Lamps W Appendix W to Subpart B of Part 430 Energy DEPARTMENT OF... Consumption of Medium Base Compact Fluorescent Lamps 1. Scope: This appendix covers the test requirements used... rated life, rapid cycle stress, and lamp life of medium base compact fluorescent lamps. 2. Definitions...

10 CFR Appendix W to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Medium Base Compact Fluorescent Lamps

Code of Federal Regulations, 2011 CFR

2011-01-01

... of Medium Base Compact Fluorescent Lamps W Appendix W to Subpart B of Part 430 Energy DEPARTMENT OF... Consumption of Medium Base Compact Fluorescent Lamps 1. Scope: This appendix covers the test requirements used... rated life, rapid cycle stress, and lamp life of medium base compact fluorescent lamps. 2. Definitions...

10 CFR Appendix W to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Medium Base Compact Fluorescent Lamps

Code of Federal Regulations, 2014 CFR

2014-01-01

... of Medium Base Compact Fluorescent Lamps W Appendix W to Subpart B of Part 430 Energy DEPARTMENT OF... Consumption of Medium Base Compact Fluorescent Lamps 1. Scope: This appendix covers the test requirements used... rated life, rapid cycle stress, and lamp life of medium base compact fluorescent lamps. 2. Definitions...

A long-term soil structure observatory for post-compaction soil structure evolution: design and initial soil structure recovery observations

NASA Astrophysics Data System (ADS)

Keller, Thomas; Colombi, Tino; Ruiz, Siul; Grahm, Lina; Reiser, René; Rek, Jan; Oberholzer, Hans-Rudolf; Schymanski, Stanislaus; Walter, Achim; Or, Dani

2016-04-01

Soil compaction due to agricultural vehicular traffic alters the geometrical arrangement of soil constituents, thereby modifying mechanical properties and pore spaces that affect a range of soil hydro-ecological functions. The ecological and economic costs of soil compaction are dependent on the immediate impact on soil functions during the compaction event, and a function of the recovery time. In contrast to a wealth of soil compaction information, mechanisms and rates of soil structure recovery remain largely unknown. A long-term (>10-yr) soil structure observatory (SSO) was established in 2014 on a loamy soil in Zurich, Switzerland, to quantify rates and mechanisms of structure recovery of compacted arable soil under different post-compaction management treatments. We implemented three initial compaction treatments (using a two-axle agricultural vehicle with 8 Mg wheel load): compaction of the entire plot area (i.e. track-by-track), compaction in wheel tracks, and no compaction. After compaction, we implemented four post-compaction soil management systems: bare soil (BS), permanent grass (PG), crop rotation without mechanical loosening (NT), and crop rotation under conventional tillage (CT). BS and PG provide insights into uninterrupted natural processes of soil structure regeneration under reduced (BS) and normal biological activity (PG). The two cropping systems (NT and CT) enable insights into soil structure recovery under common agricultural practices with minimal (NT) and conventional mechanical soil disturbance (CT). Observations include periodic sampling and measurements of soil physical properties, earthworm abundance, crop measures, electrical resistivity and ground penetrating radar imaging, and continuous monitoring of state variables - soil moisture, temperature, CO2 and O2 concentrations, redox potential and oxygen diffusion rates - for which a network of sensors was installed at various depths (0-1 m). Initial compaction increased soil bulk density to about half a metre, decreased gas and water transport functions (air permeability, gas diffusivity, saturated hydraulic conductivity), and increased mechanical impedance. Water infiltration at the soil surface was initially reduced by three orders of magnitude, but significantly recovered within a year. However, within the soil profile, recovery of transport properties is much smaller. Air permeability tended to recover more than gas diffusivity, suggesting that initial post-compaction recovery is initiated by new macropores (e.g. biopores). Tillage recovered topsoil bulk density but not topsoil transport functions. Compaction changed grass species composition in PG, and significantly reduced grass biomass in PG and crop yields in NT and CT.

An evaluation of the various aspects of the progress in clinical applications of laser driven ionizing radiation

NASA Astrophysics Data System (ADS)

Hideghéty, K.; Szabó, E. R.; Polanek, R.; Szabó, Z.; Ughy, B.; Brunner, S.; Tőkés, T.

2017-03-01

There has been a vast development of laser-driven particle acceleration (LDPA) using high power lasers. This has initiated by the radiation oncology community to use the dose distribution and biological advantages of proton/heavy ion therapy in cancer treatment with a much greater accessibility than currently possible with cyclotron/synchrotron acceleration. Up to now, preclinical experiments have only been performed at a few LDPA facilities; technical solutions for clinical LDPA have been theoretically developed but there is still a long way to go for the clinical introduction of LDPA. Therefore, to explore the further potential bio-medical advantages of LDPA has pronounced importance. The main characteristics of LDPA are the ultra-high beam intensity, the flexibility in beam size reduction and the potential particle and energy selection whilst conventional accelerators generate single particle, quasi mono-energetic beams. There is a growing number of studies on the potential advantages and applications of Energy Modulated X-ray Radiotherapy, Modulated Electron Radiotherapy and Very High Energy Electron (VHEE) delivery system. Furthermore, the ultra-high space and/or time resolution of super-intense beams are under intensive investigation at synchrotrons (microbeam radiation and very high dose rate (> 40 Gy/s) electron accelerator flash irradiation) with growing evidence of significant improvement of the therapeutic index. Boron Neutron Capture Therapy (BNCT) is an advanced cell targeted binary treatment modality. Because of the high linear energy transfer (LET) of the two particles (7Li and 4He) released by 10BNC reaction, all of the energy is deposited inside the tumour cells, killing them with high probability, while the neighbouring cells are not damaged. The limited availability of appropriate neutron sources, prevent the more extensive exploration of clinical benefit of BNCT. Another boron-based novel binary approach is the 11B-Proton Fusion, which result in the release of three high LET alpha particles. These promising, innovative approaches for cancer therapy present huge challenges for dose calculation, dosimetry and for investigation of the biological effects. The planned LDPA (photons, VHEE, protons, carbon ions) at ELI facilities has the unique property of ultra-high dose rate (> Gy/s-10), short pulses, and at ELI-ALPS high repetition rate, have the potential to develop and establish encouraging novel methods working towards compact hospital-based clinical applications.

Deformation Rates From Climate Cycles in Marine Synorogenic Turbidites, Jaca Basin, Spanish Pyrenees

NASA Astrophysics Data System (ADS)

Anastasio, D. J.; Kodama, K. P.; Pares, J. M.; Hinnov, L. A.

2007-12-01

Synsedimentary structures provide a link between depositional and deformational processes in orogenic belts. Marine growth strata offer great promise in determining precise long-term deformation rates such as uplift, shortening, fault-slip, and folding rates. Magnetostratigraphy and cyclostratigraphy of the Eocene Arguis Fm., a delta slope deposit and the overlying delta plain Belsue-Atares Fm. monitors the varying pace of deformation at Pico del Aguila, a transverse decollement fold in the south Pyrenean foothills. Anhysteretic remanent magnetization (ARM) data show hierarchical cyclicity at all predicted Milankovitch frequencies. ARM is a proxy for fine-grained detrital magnetite concentration. The age distorting effects of pre-lithification compaction on bed thickness and on the rock and paleomagnetic data series were removed using empirical calibration of anisotropy of anhysteretic remanence magnetization to volume loss from laboratory compaction experiments. The decompacted ARM depth domain was converted to time using an improved magnetostratigraphy within the growth section. Tuning filtered ARM data series to the precession index according to the LA2004 orbital model refined the magnetostratigraphic time scale. The precession-tuned growth strata mapped with precision GPS record variable folding rates at 100skyr timescales for 7 Myr and55° of limb tilt. Folding rates accelerate twice to ~30°/Myr and are punctuated by more gradual decelerations to 0-3°/Myr. Submarine folding rates at Pico del Aguila are attributed to episodic thrusting in the fold core along a roof ramp fault and along the basal decollement. Formation-scale deposition in the Paleogene wedge-top basin responded to tectonic forcing, however, clastic facies patterns in the prodeltaic and slope environments reflect regional uplift controlling sediment supply, sea level variations controlling delta front position and climate forcing (e.g. monsoon strength and frequency, pedogenesis) of runoff variability and ecology in intermountain watersheds. Lithologic parameters sensitive to sea level, such as bed thickness and grain size variations in the turbidite section record strong obliquity and eccentricity modulation, whereas, the ARM derived magnetite concentrations record terrestrial watershed sensitive processes such as aridity and windiness operating at precessional time scales.

Measurements and analyses of the distribution of the radioactivity induced by the secondary neutrons produced by 17-MeV protons in compact cyclotron facility

NASA Astrophysics Data System (ADS)

Matsuda, Norihiro; Izumi, Yuichi; Yamanaka, Yoshiyuki; Gandou, Toshiyuki; Yamada, Masaaki; Oishi, Koji

2017-09-01

Measurements of reaction rates by secondary neutrons produced from beam losses by 17-MeV protons are conducted at a compact cyclotron facility with the foil activation method. The experimentally obtained distribution of the reaction rates of 197Au (n, γ) 198Au on the concrete walls suggests that a target and an electrostatic deflector as machine components for beam extraction of the compact cyclotron are principal beam loss points. The measurements are compared with calculations by the Monte Carlo code: PHITS. The calculated results based on the beam losses are good agreements with the measured ones within 21%. In this compact cyclotron facility, exponential attenuations with the distance from the electrostatic deflector in the distributions of the measured reaction rates were observed, which was looser than that by the inverse square of distance.

Challenging developments in three decades of accelerator mass spectrometry at ETH: from large particle accelerators to table size instruments.

PubMed

Suter, Martin

2010-01-01

Accelerator mass spectrometry (AMS) was invented for the detection of radiocarbon at natural isotopic concentrations (10(-12) to 10(-15)) more than 30 years ago. Meanwhile this method has also been applied for the analysis of many other long-lived radioisotopes, which are found at very low concentrations. The first investigations were made at large tandem accelerators originally built for nuclear physics research and operating at voltages of 6-12 MV. Today dedicated instruments are mostly used for AMS, which are optimized for associated applications. In the past 15 years, a new generation of much smaller instruments has been developed. For many years it was believed that accelerators with voltages of 2 MV or higher are needed to eliminate the molecular interferences. At these energies the ions are predominantly stripped to charge state 3+, thereby removing the binding electrons of the molecules. In contrast, the new compact facilities use 1+ or 2+ ions. In this case the molecular destruction process is based on molecule-atom collisions in the gas cell. The cross sections for this destruction are sufficiently large that the intensity of molecular components such as (12)CH(2) and (13)CH can be reduced by 10 orders of magnitude. These new facilities can be built much smaller due to the lower energies. Universal instruments providing analysis for many isotopes over the whole range of periodic table have a space requirement of about 4 x 6 m(2); dedicated radiocarbon facilities based on a 200 kV accelerator have a footprint of about 2.5 x 3 m(2). This smallest category of instruments use special technologies: The high voltage terminal with the gas stripper canal is vacuum insulated and the gas is pumped to ground potential through a ceramic pipe. A conventional 200 kV power supply provides the terminal voltage from outside. A review of this new generation of compact AMS facilities is given. Design considerations and performance of these new instruments will be presented. With these developments, new AMS instruments are not much larger than conventional mass spectrometers, allowing a significant reduction in cost.

FirnCover: Observations on the evolution of firn compaction, firn temperatures and porosity in the interior of the Greenland ice sheet

NASA Astrophysics Data System (ADS)

MacFerrin, M. J.; Stevens, C.; Colgan, W. T.; Waddington, E. D.; Abdalati, W.

2016-12-01

As Greenland warms, increasing amounts of summer meltwater are changing the behavior of snow and firn in high-elevation regions of the ice. The Firn Compaction Verification and Reconnaissance (FirnCover) network in Greenland provides real-time measurements of compaction, firn temperatures and other observations across Greenland's interior, ranging from regions of dry snow to areas of heavy melt and refreezing. Here we present results from FirnCover measurements that illustrate a distinct shift in seasonal thermal cycles within the firn in regions with increased melt, whereby seasonal temperature cycles are both enhanced (in magnitude) and delayed (in timing) in response to increased latent heat from refreezing. Seasonal firn-compaction rates correlate strongly with these thermal cycles. Comparisons to historical cores illustrate that despite warming temperatures, compaction rates have not changed substantially in dry-snow regions of Greenland where meltwater has not yet been generated to a significant degree. In regions with enhanced melt and refreezing, historical comparisons indicate annual rates of compaction have dramatically increased in recent decades. In regions where near-surface firn has exceeded a critical saturation cutoff, water has begun to run off downhill rather than refreezing in years of high melt. In such regions these seasonal thermal cycles (and corresponding compaction rates) are greatly reduced due to the isolation of deep firn from meltwater above. We present current observations that suggest such saturated regions are rapidly expanding in Greenland in response to warming and enhanced summer melt. We outline the strong implications these observations have for interpreting Greenland's seasonal and inter-annual mass balance from airborne and satellite altimetry, as well as for the future evolution of runoff from Greenland's interior in a warming climate.

A compact, rugged, high repetition rate CO2 laser incorporating catalyst

NASA Technical Reports Server (NTRS)

Schwarzenberger, P. M.; Matzangou, X.

1990-01-01

The principal design features and operating characteristics of a high repetition rate CO2 laser are outlined. The laser is a compact, rugged unit, completely sealed and incorporating an unheated solid catalyst. Stable operation has been successfully demonstrated over a temperature range of -35 C to 65 C.

Compaction dynamics of crunchy granular material

NASA Astrophysics Data System (ADS)

Guillard, François; Golshan, Pouya; Shen, Luming; Valdès, Julio R.; Einav, Itai

2017-06-01

Compaction of brittle porous material leads to a wide variety of densification patterns. Static compaction bands occurs naturally in rocks or bones, and have important consequences in industry for the manufacturing of powder tablets or metallic foams for example. Recently, oscillatory compaction bands have been observed in brittle porous media like snow or cereals. We will discuss the great variety of densification patterns arising during the compaction of puffed rice, including erratic compaction at low velocity, one or several travelling compaction bands at medium velocity and homogeneous compaction at larger velocity. The conditions of existence of each pattern are studied thanks to a numerical spring lattice model undergoing breakage and is mapped to the phase diagram of the patterns based on dimensionless characteristic quantities. This also allows to rationalise the evolution of the compaction behaviour during a single test. Finally, the localisation of compaction bands is linked to the strain rate sensitivity of the material.

Dustiness behaviour of loose and compacted Bentonite and organoclay powders: What is the difference in exposure risk?

NASA Astrophysics Data System (ADS)

Jensen, Keld Alstrup; Koponen, Ismo Kalevi; Clausen, Per Axel; Schneider, Thomas

2009-01-01

Single-drop and rotating drum dustiness testing was used to investigate the dustiness of loose and compacted montmorillonite (Bentonite) and an organoclay (Nanofil®5), which had been modified from montmorillonite-rich Bentonite. The dustiness was analysed based on filter measurements as well as particle size distributions, the particle generation rate, and the total number of generated particles. Particle monitoring was completed using a TSI Fast Mobility Particle Sizer (FMPS) and a TSI Aerosol Particle Sizer (APS) at 1 s resolution. Low-pressure uniaxial powder compaction of the starting materials showed a logarithmic compaction curve and samples subjected to 3.5 kg/cm2 were used for dustiness testing to evaluate the role of powder compaction, which could occur in powders from large shipments or high-volume storage facilities. The dustiness tests showed intermediate dustiness indices (1,077-2,077 mg/kg powder) in tests of Nanofil®5, Bentonite, and compacted Bentonite, while a high-level dustiness index was found for compacted Nanofil®5 (3,487 mg/kg powder). All powders produced multimodal particle size-distributions in the dust cloud with one mode around 300 nm (Bentonite) or 400 nm (Nanofil®5) as well as one (Nanofil®5) or two modes (Bentonite) with peaks between 1 and 2.5 μm. The dust release was found to occur either as a burst (loose Bentonite and Nanofil®5), constant rate (compacted Nanofil®5), or slowly increasing rate (compacted Bentonite). In rotating drum experiments, the number of particles generated in the FMPS and APS size-ranges were in general agreement with the mass-based dustiness index, but the same order was not observed in the single-drop tests. Compaction of Bentonite reduced the number of generated particles with app. 70 and 40% during single-drop and rotating drum dustiness tests, respectively. Compaction of Nanofil®5 reduced the dustiness in the single-drop test, but it was more than doubled in the rotating drum test. Physically relevant low-pressure compaction may reduce the risk of particle exposure if powders are handled in operations with few agitations such as pouring or tapping. Repeated agitation, e.g., mixing, of these compacted powders, would result in reduced (app. 20% for Bentonite) or highly increased (app. 225% for Nanofil®5) dustiness and thereby alter the exposure risk significantly.

Design of an electron-accelerator-driven compact neutron source for non-destructive assay

NASA Astrophysics Data System (ADS)

Murata, A.; Ikeda, S.; Hayashizaki, N.

2017-09-01

The threat of nuclear and radiological terrorism remains one of the greatest challenges to international security, and the threat is constantly evolving. In order to prevent nuclear terrorism, it is important to avoid unlawful import of nuclear materials, such as uranium and plutonium. Development of technologies for non-destructive measurement, detection and recognition of nuclear materials is essential for control at national borders. At Tokyo Institute of Technology, a compact neutron source system driven by an electron-accelerator has been designed for non-destructive assay (NDA). This system is composed of a combination of an S-band (2.856 GHz) RF-gun, a tungsten target to produce photons by bremsstrahlung, a beryllium target, which is suitable for use in generating neutrons because of the low threshold energy of photonuclear reactions, and a moderator to thermalize the fast neutrons. The advantage of this system can accelerate a short pulse beam with a pulse width less than 1 μs which is difficult to produce by neutron generators. The amounts of photons and neutron produced by electron beams were simulated using the Monte Carlo simulation code PHITS 2.82. When the RF-gun is operated with an average electron beam current of 0.1 mA, it is expected that the neutron intensities are 1.19 × 109 n/s and 9.94 × 109 n/s for incident electron beam energies of 5 MeV and 10 MeV, respectively.

Collimated electron beam accelerated at 12 kV from a Penning discharge.

PubMed

Toader, D; Oane, M; Ticoş, C M

2015-01-01

A pulsed electron beam accelerated at 12 kV with a duration of 40 μs per pulse is obtained from a Penning discharge with a hollow anode and two cathodes. The electrons are extracted through a hole in one of the cathodes and focused by a pair of coils. The electron beam has a diameter of a few mm in the cross section, while the beam current reaches peak values of 400 mA, depending on the magnetic field inside the focussing coils. This relatively inexpensive and compact device is suitable for the irradiation of small material samples placed in high vacuum.

Observation of Gigawatt-Class THz Pulses from a Compact Laser-Driven Particle Accelerator

NASA Astrophysics Data System (ADS)

Gopal, A.; Herzer, S.; Schmidt, A.; Singh, P.; Reinhard, A.; Ziegler, W.; Brömmel, D.; Karmakar, A.; Gibbon, P.; Dillner, U.; May, T.; Meyer, H.-G.; Paulus, G. G.

2013-08-01

We report the observation of subpicosecond terahertz (T-ray) pulses with energies ≥460μJ from a laser-driven ion accelerator, thus rendering the peak power of the source higher even than that of state-of-the-art synchrotrons. Experiments were performed with intense laser pulses (up to 5×1019W/cm2) to irradiate thin metal foil targets. Ion spectra measured simultaneously showed a square law dependence of the T-ray yield on particle number. Two-dimensional particle-in-cell simulations show the presence of transient currents at the target rear surface which could be responsible for the strong T-ray emission.

Nuclear nanoprobe development for visualization of three-dimensional nanostructures

NASA Astrophysics Data System (ADS)

Takai, M.; Abo, S.; Wakaya, F.; Kikuchi, T.; Sawaragi, H.

2007-08-01

A nanoprobe system, having a liquid metal ion source with a compact electrostatic accelerating column with a maximum accelerating voltage of 200 kV and an ultra high vacuum chamber, giving rise to the enhanced sensitivity because of the large scattering cross-section, has been designed for analysis of nanostructures. The focusing performance of the probes down to 10 nm was measured and compared with the simulation. Time-of-flight (TOF) RBS using a micro channel plate (MCP) further increases the sensitivity because of the increase in acceptance angle, which realizes the visualization of nanostructures with a beam spot diameter less than 10 nm with less probe damage.

Wakefield Computations for the CLIC PETS using the Parallel Finite Element Time-Domain Code T3P

DOE Office of Scientific and Technical Information (OSTI.GOV)

Candel, A; Kabel, A.; Lee, L.

In recent years, SLAC's Advanced Computations Department (ACD) has developed the high-performance parallel 3D electromagnetic time-domain code, T3P, for simulations of wakefields and transients in complex accelerator structures. T3P is based on advanced higher-order Finite Element methods on unstructured grids with quadratic surface approximation. Optimized for large-scale parallel processing on leadership supercomputing facilities, T3P allows simulations of realistic 3D structures with unprecedented accuracy, aiding the design of the next generation of accelerator facilities. Applications to the Compact Linear Collider (CLIC) Power Extraction and Transfer Structure (PETS) are presented.

Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging.

PubMed

Golovin, G; Banerjee, S; Liu, C; Chen, S; Zhang, J; Zhao, B; Zhang, P; Veale, M; Wilson, M; Seller, P; Umstadter, D

2016-04-19

The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.

Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging

DOE PAGES

Golovin, G.; Banerjee, S.; Liu, C.; ...

2016-04-19

Here, the recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense lasermore » probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Candel, Arno; Li, Z.; Ng, C.

The Compact Linear Collider (CLIC) provides a path to a multi-TeV accelerator to explore the energy frontier of High Energy Physics. Its novel two-beam accelerator concept envisions rf power transfer to the accelerating structures from a separate high-current decelerator beam line consisting of power extraction and transfer structures (PETS). It is critical to numerically verify the fundamental and higher-order mode properties in and between the two beam lines with high accuracy and confidence. To solve these large-scale problems, SLAC's parallel finite element electromagnetic code suite ACE3P is employed. Using curvilinear conformal meshes and higher-order finite element vector basis functions, unprecedentedmore » accuracy and computational efficiency are achieved, enabling high-fidelity modeling of complex detuned structures such as the CLIC TD24 accelerating structure. In this paper, time-domain simulations of wakefield coupling effects in the combined system of PETS and the TD24 structures are presented. The results will help to identify potential issues and provide new insights on the design, leading to further improvements on the novel CLIC two-beam accelerator scheme.« less

Dense blocks of energetic ions driven by multi-petawatt lasers

PubMed Central

Weng, S. M.; Liu, M.; Sheng, Z. M.; Murakami, M.; Chen, M.; Yu, L. L.; Zhang, J.

2016-01-01

Laser-driven ion accelerators have the advantages of compact size, high density, and short bunch duration over conventional accelerators. Nevertheless, it is still challenging to simultaneously enhance the yield and quality of laser-driven ion beams for practical applications. Here we propose a scheme to address this challenge via the use of emerging multi-petawatt lasers and a density-modulated target. The density-modulated target permits its ions to be uniformly accelerated as a dense block by laser radiation pressure. In addition, the beam quality of the accelerated ions is remarkably improved by embedding the target in a thick enough substrate, which suppresses hot electron refluxing and thus alleviates plasma heating. Particle-in-cell simulations demonstrate that almost all ions in a solid-density plasma of a few microns can be uniformly accelerated to about 25% of the speed of light by a laser pulse at an intensity around 1022 W/cm2. The resulting dense block of energetic ions may drive fusion ignition and more generally create matter with unprecedented high energy density. PMID:26924793

Single-stage plasma-based correlated energy spread compensation for ultrahigh 6D brightness electron beams

DOE PAGES

Manahan, Grace G.; Habib, A. F.; Scherkl, P.; ...

2017-06-05

Plasma photocathode wakefield acceleration combines energy gains of tens of GeV m –1 with generation of ultralow emittance electron bunches, and opens a path towards 5D-brightness orders of magnitude larger than state-of-the-art. This holds great promise for compact accelerator building blocks and advanced light sources. However, an intrinsic by-product of the enormous electric field gradients inherent to plasma accelerators is substantial correlated energy spread—an obstacle for key applications such as free-electron-lasers. Here we show that by releasing an additional tailored escort electron beam at a later phase of the acceleration, when the witness bunch is relativistically stable, the plasma wavemore » can be locally overloaded without compromising the witness bunch normalized emittance. Here, this reverses the effective accelerating gradient, and counter-rotates the accumulated negative longitudinal phase space chirp of the witness bunch. Thereby, the energy spread is reduced by an order of magnitude, thus enabling the production of ultrahigh 6D-brightness beams.« less

Investigation of Embedded Si/C System Exposed to a Hybrid Reaction of Centrifugal-Assisted Thermite Method

PubMed Central

Mahmoodian, Reza; Yahya, Rosiyah; Dabbagh, Ali; Hamdi, Mohd; Hassan, Mohsen A.

2015-01-01

A novel method is proposed to study the behavior and phase formation of a Si+C compacted pellet under centrifugal acceleration in a hybrid reaction. Si+C as elemental mixture in the form of a pellet is embedded in a centrifugal tube. The pellet assembly and tube are exposed to the sudden thermal energy of a thermite reaction resulted in a hybrid reaction. The hybrid reaction of thermite and Si+C produced unique phases. X-ray diffraction pattern (XRD) as well as microstructural and elemental analyses are then investigated. XRD pattern showed formation of materials with possible electronic and magnetic properties. The cooling rate and the molten particle viscosity mathematical model of the process are meant to assist in understanding the physical and chemical phenomena took place during and after reaction. The results analysis revealed that up to 85% of materials converted into secondary products as ceramics-matrix composite. PMID:26641651

Investigation of Embedded Si/C System Exposed to a Hybrid Reaction of Centrifugal-Assisted Thermite Method.

PubMed

Mahmoodian, Reza; Yahya, Rosiyah; Dabbagh, Ali; Hamdi, Mohd; Hassan, Mohsen A

2015-01-01

A novel method is proposed to study the behavior and phase formation of a Si+C compacted pellet under centrifugal acceleration in a hybrid reaction. Si+C as elemental mixture in the form of a pellet is embedded in a centrifugal tube. The pellet assembly and tube are exposed to the sudden thermal energy of a thermite reaction resulted in a hybrid reaction. The hybrid reaction of thermite and Si+C produced unique phases. X-ray diffraction pattern (XRD) as well as microstructural and elemental analyses are then investigated. XRD pattern showed formation of materials with possible electronic and magnetic properties. The cooling rate and the molten particle viscosity mathematical model of the process are meant to assist in understanding the physical and chemical phenomena took place during and after reaction. The results analysis revealed that up to 85% of materials converted into secondary products as ceramics-matrix composite.

Waveguide-Mode Terahertz Free Electron Lasers Driven by Magnetron-Based Microtrons

NASA Astrophysics Data System (ADS)

Jeong, Young Uk; Miginsky, Sergey; Gudkov, Boris; Lee, Kitae; Mun, Jungho; Shim, Gyu Il; Bae, Sangyoon; Kim, Hyun Woo; Jang, Kyu-Ha; Park, Sunjeong; Park, Seong Hee; Vinokurov, Nikolay

2016-04-01

We have developed small-sized terahertz free-electron lasers by using low-cost and compact microtrons combining with magnetrons as high-power RF sources. We could stabilize the bunch repetition rate by optimizing a modulator for the magnetron and by coupling the magnetron with an accelerating cavity in the microtron. By developing high-performance undulators and low-loss waveguide-mode resonators having small cross-sectional areas, we could strengthen the interaction between the electron beam and the THz wave inside the FEL resonators to achieve lasing even with low-current electron beams from the microtron. We used a parallel-plate waveguide in a planar electromagnet undulator for our first THz FEL. We try to reduce the size of the FEL resonator by combining a dielectric-coated circular waveguide and a variable-period helical undulator to realize a table-top THz FEL for applying it to the security inspection on airports.

Subsidence driving forces in large Delta Plain

NASA Astrophysics Data System (ADS)

Grall, C.; Steckler, M. S.

2017-12-01

Recent studies show large variability in subsidence rates among large delta plains that directly impact coastal management of these highly vulnerable environments. Observations show both significant spatial variation in subsidence across each delta, as well as large differences in magnitude between different deltas. This variability raises the question of what are the driving forces that control subsidence in large delta plains that this study aims to address. Subsidence and sediment compaction is studied in 4 end-member large Delta Plains: the Ganges-Brahmaputra, the Mekong, the Mississippi and the Nile. Those large delta plains drastically contrast in subsidence rates (from values to several mm/yr to several cm/yr), in the nature of the sediment (notably in clay and organic matter content), and in the volume of sediment supplied by the large rivers that feed those coastal environments. The volume of sediment deposited in each delta plain during the Holocene is estimated and the compaction of the underlying sedimentary column is computed by using a backstripping approach. Sediment compaction behaviors are defined accordingly to the observed clay, silt and organic contents, and the rate of subsidence associated with compaction is determined. Results suggest that about 2/3 of observed Holocene subsidence may be associated with the mechanical and chemical compaction of the underlying sedimentary column due to the load of sediment deposited. The compaction appears to be significantly higher in delta plains characterized by a high sediment input and a high organic matter and clay content. Thus, the observed subsidence rates in the (muddy) Mekong delta appear to be one order of magnitude higher than other delta plains. In contrast, subsidence rates are modest in the Ganges-Brahmaputra, the Mississippi and the Nile delta plains, except away from the major rivers where deposits are muddier.

Generation of quasi-monoenergetic heavy ion beams via staged shock wave acceleration driven by intense laser pulses in near-critical plasmas

NASA Astrophysics Data System (ADS)

Zhang, W. L.; Qiao, B.; Shen, X. F.; You, W. Y.; Huang, T. W.; Yan, X. Q.; Wu, S. Z.; Zhou, C. T.; He, X. T.

2016-09-01

Laser-driven ion acceleration potentially offers a compact, cost-effective alternative to conventional accelerators for scientific, technological, and health-care applications. A novel scheme for heavy ion acceleration in near-critical plasmas via staged shock waves driven by intense laser pulses is proposed, where, in front of the heavy ion target, a light ion layer is used for launching a high-speed electrostatic shock wave. This shock is enhanced at the interface before it is transmitted into the heavy ion plasmas. Monoenergetic heavy ion beam with much higher energy can be generated by the transmitted shock, comparing to the shock wave acceleration in pure heavy ion target. Two-dimensional particle-in-cell simulations show that quasi-monoenergetic {{{C}}}6+ ion beams with peak energy 168 MeV and considerable particle number 2.1 × {10}11 are obtained by laser pulses at intensity of 1.66 × {10}20 {{W}} {{cm}}-2 in such staged shock wave acceleration scheme. Similarly a high-quality {{Al}}10+ ion beam with a well-defined peak with energy 250 MeV and spread δ E/{E}0=30 % can also be obtained in this scheme.

High-energy radiation from the relativistic jet of Cygnus X-3

NASA Astrophysics Data System (ADS)

Cerutti, B.; Dubus, G.; Henri, G.

2010-12-01

Cygnus X-3 is an accreting high-mass X-ray binary composed of a Wolf-Rayet star and an unknown compact object, possibly a black hole. The gamma-ray space telescope Fermi found definitive evidence that high-energy emission is produced in this system. We propose a scenario to explain the GeV gamma-ray emission in Cygnus X-3. In this model, energetic electron-positron pairs are accelerated at a specific location in the relativistic jet, possibly related to a recollimation shock, and upscatter the stellar photons to high energies. The comparison with Fermi observations shows that the jet should be inclined close to the line of sight and pairs should not be located within the system. Energetically speaking, a massive compact object is favored. We report also on our investigations of the gamma-ray absorption of GeV photons with the radiation emitted by a standard accretion disk in Cygnus X-3. This study shows that the gamma-ray source should not lie too close to the compact object.

Development of Compact Ozonizer with High Ozone Output by Pulsed Power

NASA Astrophysics Data System (ADS)

Tanaka, Fumiaki; Ueda, Satoru; Kouno, Kanako; Sakugawa, Takashi; Akiyama, Hidenori; Kinoshita, Youhei

Conventional ozonizer with a high ozone output using silent or surface discharges needs a cooling system and a dielectric barrier, and therefore becomes a large machine. A compact ozonizer without the cooling system and the dielectric barrier has been developed by using a pulsed power generated discharge. The wire to plane electrodes made of metal have been used. However, the ozone output was low. Here, a compact and high repetition rate pulsed power generator is used as an electric source of a compact ozonizer. The ozone output of 6.1 g/h and the ozone yield of 86 g/kWh are achieved at 500 pulses per second, input average power of 280 W and an air flow rate of 20 L/min.

Study on compressive strength of self compacting mortar cubes under normal & electric oven curing methods

NASA Astrophysics Data System (ADS)

Prasanna Venkatesh, G. J.; Vivek, S. S.; Dhinakaran, G.

2017-07-01

In the majority of civil engineering applications, the basic building blocks were the masonry units. Those masonry units were developed as a monolithic structure by plastering process with the help of binding agents namely mud, lime, cement and their combinations. In recent advancements, the mortar study plays an important role in crack repairs, structural rehabilitation, retrofitting, pointing and plastering operations. The rheology of mortar includes flowable, passing and filling properties which were analogous with the behaviour of self compacting concrete. In self compacting (SC) mortar cubes, the cement was replaced by mineral admixtures namely silica fume (SF) from 5% to 20% (with an increment of 5%), metakaolin (MK) from 10% to 30% (with an increment of 10%) and ground granulated blast furnace slag (GGBS) from 25% to 75% (with an increment of 25%). The ratio between cement and fine aggregate was kept constant as 1: 2 for all normal and self compacting mortar mixes. The accelerated curing namely electric oven curing with the differential temperature of 128°C for the period of 4 hours was adopted. It was found that the compressive strength obtained from the normal and electric oven method of curing was higher for self compacting mortar cubes than normal mortar cube. The cement replacement by 15% SF, 20% MK and 25%GGBS obtained higher strength under both curing conditions.

Enzyme clustering accelerates processing of intermediates through metabolic channeling

PubMed Central

Castellana, Michele; Wilson, Maxwell Z.; Xu, Yifan; Joshi, Preeti; Cristea, Ileana M.; Rabinowitz, Joshua D.; Gitai, Zemer; Wingreen, Ned S.

2015-01-01

We present a quantitative model to demonstrate that coclustering multiple enzymes into compact agglomerates accelerates the processing of intermediates, yielding the same efficiency benefits as direct channeling, a well-known mechanism in which enzymes are funneled between enzyme active sites through a physical tunnel. The model predicts the separation and size of coclusters that maximize metabolic efficiency, and this prediction is in agreement with previously reported spacings between coclusters in mammalian cells. For direct validation, we study a metabolic branch point in Escherichia coli and experimentally confirm the model prediction that enzyme agglomerates can accelerate the processing of a shared intermediate by one branch, and thus regulate steady-state flux division. Our studies establish a quantitative framework to understand coclustering-mediated metabolic channeling and its application to both efficiency improvement and metabolic regulation. PMID:25262299

Laboratory Plasma Studies

DTIC Science & Technology

1989-05-23

Intense Rela- tivistic Electron Beams S . A Compact Accelerator Powercd by the Relativistic Klystron Amplifier T. Numerical and Experimental Studies of...Research Laboratory Washingto, IX 2075.6000 NRL Memorandum Report 6419 Megavolt, Multi-Kiloamp K - Band Gyrotron Oscillator Experiment W. M. BLACK,* S . H...Ka- Band Gyrotron Oscillator Experiments with Slotted and Unslotted Cavities S . H. GOLD, MEMBER, IEEE. A. W. FLIFLET, MEMBER, IEEE, W. M. MANHEIMER

Optical control of hard X-ray polarization by electron injection in a laser wakefield accelerator

PubMed Central

Schnell, Michael; Sävert, Alexander; Uschmann, Ingo; Reuter, Maria; Nicolai, Maria; Kämpfer, Tino; Landgraf, Björn; Jäckel, Oliver; Jansen, Oliver; Pukhov, Alexander; Kaluza, Malte Christoph; Spielmann, Christian

2013-01-01

Laser-plasma particle accelerators could provide more compact sources of high-energy radiation than conventional accelerators. Moreover, because they deliver radiation in femtosecond pulses, they could improve the time resolution of X-ray absorption techniques. Here we show that we can measure and control the polarization of ultra-short, broad-band keV photon pulses emitted from a laser-plasma-based betatron source. The electron trajectories and hence the polarization of the emitted X-rays are experimentally controlled by the pulse-front tilt of the driving laser pulses. Particle-in-cell simulations show that an asymmetric plasma wave can be driven by a tilted pulse front and a non-symmetric intensity distribution of the focal spot. Both lead to a notable off-axis electron injection followed by collective electron–betatron oscillations. We expect that our method for an all-optical steering is not only useful for plasma-based X-ray sources but also has significance for future laser-based particle accelerators. PMID:24026068

Proton acceleration: new developments for focusing and energy selection, and applications in plasma physics

NASA Astrophysics Data System (ADS)

Audebert, P.

2007-11-01

In the last few years, intense research has been conducted on laser-accelerated ion sources and their applications. These sources have exceptional properties, i.e. high brightness and high spectral cut-off, high directionality and laminarity, short burst duration. We have shown that for proton energies >10 MeV, the transverse and longitudinal emittance are respectively <0.004 mm-mrad and <10-4 eV-s, i.e. at least 100-fold and may be as much as 10^4-fold better than conventional accelerators beams. Thanks to these properties, these sources allow for example point-projection radiography with unprecedented resolution. We will show example of such time and space-resolved radiography of fast evolving fields, either of associated with the expansion of a plasma in vacuum [*] or with the propagation of a ICF-relevant laser beam in an underdense plasma. These proton sources also open new opportunities for ion beam generation and control, and could stimulate development of compact ion accelerators for many applications.

Design Considerations for Proposed Fermilab Integrable RCS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eldred, Jeffrey; Valishev, Alexander

2017-03-02

Integrable optics is an innovation in particle accelerator design that provides strong nonlinear focusing while avoiding parametric resonances. One promising application of integrable optics is to overcome the traditional limits on accelerator intensity imposed by betatron tune-spread and collective instabilities. The efficacy of high-intensity integrable accelerators will be undergo comprehensive testing over the next several years at the Fermilab Integrable Optics Test Accelerator (IOTA) and the University of Maryland Electron Ring (UMER). We propose an integrable Rapid-Cycling Synchrotron (iRCS) as a replacement for the Fermilab Booster to achieve multi-MW beam power for the Fermilab high-energy neutrino program. We provide amore » overview of the machine parameters and discuss an approach to lattice optimization. Integrable optics requires arcs with integer-pi phase advance followed by drifts with matched beta functions. We provide an example integrable lattice with features of a modern RCS - long dispersion-free drifts, low momentum compaction, superperiodicity, chromaticity correction, separate-function magnets, and bounded beta functions.« less

Jet-driven and jet-less fireballs from compact binary mergers

NASA Astrophysics Data System (ADS)

Salafia, O. S.; Ghisellini, G.; Ghirlanda, G.

2018-02-01

During a compact binary merger involving at least one neutron star (NS), a small fraction of the gravitational energy could be liberated in such a way to accelerate a small fraction (˜10-6) of the NS mass in an isotropic or quasi-isotropic way. In presence of certain conditions, a pair-loaded fireball can form, which undergoes accelerated expansion reaching relativistic velocities. As in the standard fireball scenario, internal energy is partly transformed into kinetic energy. At the photospheric radius, the internal radiation can escape, giving rise to a pulse that lasts for a time equal to the delay time since the merger. The subsequent interaction with the interstellar medium can then convert part of the remaining kinetic energy back into radiation in a weak isotropic afterglow at all wavelengths. This scenario does not require the presence of a jet: the associated isotropic prompt and afterglow emission should be visible for all NS-NS and BH-NS mergers within 90 Mpc, independent of their inclination. The prompt emission is similar to that expected from an off-axis jet, either structured or much slower than usually assumed (Γ ˜ 10), or from the jet cocoon. The predicted afterglow emission properties can discriminate among these scenarios.

Design of a compact all-permanent magnet ECR ion source injector for ReA at the MSU NSCL

NASA Astrophysics Data System (ADS)

Pham, Alfonse N.; Leitner, Daniela; Glennon, Patrick; Ottarson, Jack; Lawton, Don; Portillo, Mauricio; Machicoane, Guillaume; Wenstrom, John; Lajoie, Andrew

2016-06-01

The design of a compact all-permanent magnet electron cyclotron resonance (ECR) ion source injector for the ReAccelerator Facility (ReA) at the Michigan State University (MSU) National Superconducting Cyclotron Laboratory (NSCL) is currently being carried out. The ECR ion source injector will complement the electron beam ion trap (EBIT) charge breeder as an off-line stable ion beam injector for the ReA linac. The objective of the ECR ion source injector is to provide continuous-wave beams of heavy ions from hydrogen to masses up to 136Xe within the ReA charge-to-mass ratio (Q / A) operational range from 0.2 to 0.5. The ECR ion source will be mounted on a high-voltage platform that can be adjusted to obtain the required 12 keV/u injection energy into a room temperature radio-frequency quadrupole (RFQ) for further acceleration. The beam line consists of a 30 kV tetrode extraction system, mass analyzing section, and optical matching section for injection into the existing ReA low energy beam transport (LEBT) line. The design of the ECR ion source and the associated beam line are discussed.

Development of a magnetized coaxial plasma gun for compact toroid injection into the C-2 field-reversed configuration device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsumoto, T., E-mail: cstd14003@g.nihon-u.ac.jp; Sekiguchi, J.; Asai, T.

A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode.more » A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10{sup 21} m{sup −3}, ∼40 eV, and 0.5–1.0 × 10{sup 19}, respectively.« less

Euler force actuation mechanism for siphon valving in compact disk-like microfluidic chips

PubMed Central

Deng, Yongbo; Fan, Jianhua; Zhou, Song; Zhou, Teng; Wu, Junfeng; Li, Yin; Liu, Zhenyu; Xuan, Ming; Wu, Yihui

2014-01-01

Based on the Euler force induced by the acceleration of compact disk (CD)-like microfluidic chip, this paper presents a novel actuation mechanism for siphon valving. At the preliminary stage of acceleration, the Euler force in the tangential direction of CD-like chip takes the primary place compared with the centrifugal force to function as the actuation of the flow, which fills the siphon and actuates the siphon valving. The Euler force actuation mechanism is demonstrated by the numerical solution of the phase-field based mathematical model for the flow in siphon valve. In addition, experimental validation is implemented in the polymethylmethacrylate-based CD-like microfluidic chip manufactured using CO2 laser engraving technique. To prove the application of the proposed Euler force actuation mechanism, whole blood separation and plasma extraction has been conducted using the Euler force actuated siphon valving. The newly introduced actuation mechanism overcomes the dependence on hydrophilic capillary filling of siphon by avoiding external manipulation or surface treatments of polymeric material. The sacrifice for highly integrated processing in pneumatic pumping technique is also prevented by excluding the volume-occupied compressed air chamber. PMID:24753736

MEMS-based, RF-driven, compact accelerators

NASA Astrophysics Data System (ADS)

Persaud, A.; Seidl, P. A.; Ji, Q.; Breinyn, I.; Waldron, W. L.; Schenkel, T.; Vinayakumar, K. B.; Ni, D.; Lal, A.

2017-10-01

Shrinking existing accelerators in size can reduce their cost by orders of magnitude. Furthermore, by using radio frequency (RF) technology and accelerating ions in several stages, the applied voltages can be kept low paving the way to new ion beam applications. We make use of the concept of a Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) and have previously shown the implementation of its basic components using printed circuit boards, thereby reducing the size of earlier MEQALACs by an order of magnitude. We now demonstrate the combined integration of these components to form a basic accelerator structure, including an initial beam-matching section. In this presentation, we will discuss the results from the integrated multi-beam ion accelerator and also ion acceleration using RF voltages generated on-board. Furthermore, we will show results from Micro-Electro-Mechanical Systems (MEMS) fabricated focusing wafers, which can shrink the dimension of the system to the sub-mm regime and lead to cheaper fabrication. Based on these proof-of-concept results we outline a scaling path to high beam power for applications in plasma heating in magnetized target fusion and in neutral beam injectors for future Tokamaks. This work was supported by the Office of Science of the US Department of Energy through the ARPA-e ALPHA program under contracts DE-AC02-05CH11231.

APPARATUS FOR MEASURING TOTAL NEUTRON CROSS SECTIONS

DOEpatents

Cranberg, L.

1959-10-13

An apparatus is described for measuring high-resolution total neutron cross sections at high counting rate in the range above 50-kev neutron energy. The pulsed-beam time-of-flight technique is used to identify the neutrons of interest which are produced in the target of an electrostatic accelerator. Energy modulation of the accelerator . makes it possible to make observations at 100 energy points simultaneously. 761O An apparatus is described for monitoring the proton resonance of a liquid which is particulariy useful in the continuous purity analysis of heavy water. A hollow shell with parallel sides defines a meander chamber positioned within a uniform magnetic fieid. The liquid passes through an inlet at the outer edge of the chamber and through a spiral channel to the central region of the chamber where an outlet tube extends into the chamber perpendicular to the magnetic field. The radiofrequency energy for the monitor is coupled to a coil positioned coaxially with the outlet tube at its entrance point within the chamber. The improvement lies in the compact mechanical arrangement of the monitor unit whereby the liquid under analysis is subjected to the same magnetic field in the storage and sensing areas, and the entire unit is shielded from external electrostatic influences.

Increased foot-stretcher height improves rowing performance: evidence from biomechanical perspectives on water.

PubMed

Liu, Yang; Gao, Binghong; Li, Jiru; Ma, Zuchang; Sun, Yining

2018-06-07

The aim of this study was to investigate whether changes on foot-stretcher height were associated with characteristics of better rowing performance. Ten male rowers performed a 200 m rowing trial at their racing rate at each of three foot-stretcher heights. A single scull was equipped with an accelerometer to collect boat acceleration, an impeller with embedded magnets to collect boat speed, specially designed gate sensors to collect gate force and angle, and a compact string potentiometer to collect leg drive length. All sensor signals were sampled at 50 Hz. A one-way repeated measures ANOVA showed that raising foot-stretcher position had a significant reduction on total gate angle and leg drive length. However, a raised foot-stretcher position had a deeper negative peak of boat acceleration at the catch, a lower boat fluctuation, a faster leg drive speed, a larger gate force for the port and starboard side separately. This could be attributed to the optimisation of the magnitude and direction of the foot force with a raised foot-stretcher position. Although there was a significant negative influence of a raised foot-stretcher position on two kinematic variables, biomechanical evidence suggested that a raised foot-stretcher position could contribute to the improvement of rowing performance.

APPLICATION OF FLOW SIMULATION FOR EVALUATION OF FILLING-ABILITY OF SELF-COMPACTING CONCRETE

NASA Astrophysics Data System (ADS)

Urano, Shinji; Nemoto, Hiroshi; Sakihara, Kohei

In this paper, MPS method was applied to fluid an alysis of self-compacting concrete. MPS method is one of the particle method, and it is suitable for the simulation of moving boundary or free surface problems and large deformation problems. The constitutive equation of self-compacting concrete is assumed as bingham model. In order to investigate flow Stoppage and flow speed of self-compacting concrete, numerical analysis examples of slump flow and L-flow test were performed. In addition, to evaluate verification of compactability of self-compacting concrete, numerical analys is examples of compaction at the part of CFT diaphragm were performed. As a result, it was found that the MPS method was suitable for the simulation of compaction of self-compacting concrete, and a just appraisal was obtained by setting shear strain rate of flow-limit πc and limitation point of segregation.

Laser experiments to simulate coronal mass ejection driven magnetospheres and astrophysical plasma winds on compact magnetized stars

NASA Astrophysics Data System (ADS)

Horton, W.; Ditmire, T.; Zakharov, Yu. P.

2010-06-01

Laboratory experiments using a plasma wind generated by laser-target interaction are proposed to investigate the creation of a shock in front of the magnetosphere and the dynamo mechanism for creating plasma currents and voltages. Preliminary experiments are shown where measurements of the electron density gradients surrounding the obstacles are recorded to infer the plasma winds. The proposed experiments are relevant to understanding the electron acceleration mechanisms taking place in shock-driven magnetic dipole confined plasmas surrounding compact magnetized stars and planets. Exploratory experiments have been published [P. Brady, T. Ditmire, W. Horton, et al., Phys. Plasmas 16, 043112 (2009)] with the one Joule Yoga laser and centimeter sized permanent magnets.

A compact, coherent light source system architecture

NASA Astrophysics Data System (ADS)

Biedron, S. G.; Dattoli, G.; DiPalma, E.; Einstein, J.; Milton, S. V.; Petrillo, V.; Rau, J. V.; Sabia, E.; Spassovsky, I. P.; van der Slot, P. J. M.

2016-09-01

Our team has been examining several architectures for short-wavelength, coherent light sources. We are presently exploring the use and role of advanced, high-peak power lasers for both accelerating the electrons and generating a compact light source with the same laser. Our overall goal is to devise light sources that are more accessible by industry and in smaller laboratory settings. Although we cannot and do not want to compete directly with sources such as third-generation light sources or that of national-laboratory-based free-electron lasers, we have several interesting schemes that could bring useful and more coherent, short-wavelength light source to more researchers. Here, we present and discuss several results of recent simulations and our future steps for such dissemination.

A compact permanent magnet cyclotrino for accelerator mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, A.T.; Clark, D.J.; Kunkel, W.B.

1995-02-01

The authors describe the development of a new instrument for the detection of trace amounts of rare isotopes, a Cyclotron Mass Spectrometer (CMS). A compact low energy cyclotron optimized for high mass resolution has been designed and has been fabricated. The instrument has high sensitivity and is designed to measure carbon-14 at abundances of < 10{sup {minus}12}. A novel feature of the instrument is the use of permanent magnets to energize the iron poles of the cyclotron. The instrument uses axial injection, employing a spiral inflector. The instrument has been assembled and preliminary measurements of the magnetic field show thatmore » it has a uniformity on the order of 2 parts in 10{sup 4}.« less

The Capacity for Compaction Weakening in Fault Gouge in Nature and Experiment

NASA Astrophysics Data System (ADS)

Faulkner, D.; Boulton, C. J.; Sanchez Roa, C.; Den Hartog, S. A. M.; Bedford, J. D.

2017-12-01

As faults form in low permeability rocks, the compaction of fault gouge can lead to significant pore-fluid pressure increases. The pore pressure increase results from the collapse of the porosity through shear-enhanced compaction and the low hydraulic diffusivity of the gouge that inhibits fluid flow. In experiments, the frictional properties of clay-bearing fault gouges are significantly affected by the development of locally high pore-fluid pressures when compaction rates are high due to fast displacement rates or slip in underconsolidated materials. We show how the coefficient of friction of fault gouges sheared at different slip velocities can be explained with a numerical model that is constrained by laboratory measurements of contemporaneous changes in permeability and porosity. In nature, for compaction weakening to play an important role in earthquake nucleation (and rupture propagation), a mechanism is required to reset the porosity, i.e., maintain underconsolidated gouge along the fault plane. We use the observations of structures within the principal slip zone of the Alpine Fault in New Zealand to suggest that cyclic fluidization of the gouge occurs during coseismic slip, thereby resetting the gouge porosity prior to the next seismic event. Results from confined laboratory rotary shear measurements at elevated slip rates appear to support the hypothesis that fluidization leads to underconsolidation and, thus, to potential weakening by shear-enhanced compaction-induced pore-fluid pressurization.

Reconstructing Common Era relative sea-level change on the Gulf Coast of Florida

USGS Publications Warehouse

Gerlach, Matthew J.; Engelhart, Simon E.; Kemp, Andrew C.; Moyer, Ryan P.; Smoak, Joseph M.; Bernhardt, Christopher E.; Cahill, Niamh

2017-01-01

To address a paucity of Common Era data in the Gulf of Mexico, we reconstructed ~ 1.1 m of relative sea-level (RSL) rise over the past ~ 2000 years at Little Manatee River (Gulf Coast of Florida, USA). We applied a regional-scale foraminiferal transfer function to fossil assemblages preserved in a core of salt-marsh peat and organic silt that was dated using radiocarbon and recognition of pollution, 137Cs and pollen chronohorizons. Our proxy reconstruction was combined with tide-gauge data from four nearby sites spanning 1913–2014 CE. Application of an Errors-in-Variables Integrated Gaussian Process (EIV-IGP) model to the combined proxy and instrumental dataset demonstrates that RSL fell from ~ 350 to 100 BCE, before rising continuously to present. This initial RSL fall was likely the result of local-scale processes (e.g., silting up of a tidal flat or shallow sub-tidal shoal) as salt-marsh development at the site began. Since ~ 0 CE, we consider the reconstruction to be representative of regional-scale RSL trends. We removed a linear rate of 0.3 mm/yr from the RSL record using the EIV-IGP model to estimate climate-driven sea-level trends and to facilitate comparison among sites. This analysis demonstrates that since ~ 0 CE sea level did not deviate significantly from zero until accelerating continuously from ~ 1500 CE to present. Sea level was rising at 1.33 mm/yr in 1900 CE and accelerated until 2014 CE when a rate of 2.02 mm/yr was attained, which is the fastest, century-scale trend in the ~ 2000-year record. Comparison to existing reconstructions from the Gulf coast of Louisiana and the Atlantic coast of northern Florida reveal similar sea-level histories at all three sites. We explored the influence of compaction and fluvial processes on our reconstruction and concluded that compaction was likely insignificant. Fluvial processes were also likely insignificant, but further proxy evidence is needed to fully test this hypothesis. Our results indicate that no significant Common Era sea-level changes took place on the Gulf and southeastern Atlantic U.S. coasts until the onset of modern sea-level rise in the late 19th century.

Gene family size conservation is a good indicator of evolutionary rates.

PubMed

Chen, Feng-Chi; Chen, Chiuan-Jung; Li, Wen-Hsiung; Chuang, Trees-Juen

2010-08-01

The evolution of duplicate genes has been a topic of broad interest. Here, we propose that the conservation of gene family size is a good indicator of the rate of sequence evolution and some other biological properties. By comparing the human-chimpanzee-macaque orthologous gene families with and without family size conservation, we demonstrate that genes with family size conservation evolve more slowly than those without family size conservation. Our results further demonstrate that both family expansion and contraction events may accelerate gene evolution, resulting in elevated evolutionary rates in the genes without family size conservation. In addition, we show that the duplicate genes with family size conservation evolve significantly more slowly than those without family size conservation. Interestingly, the median evolutionary rate of singletons falls in between those of the above two types of duplicate gene families. Our results thus suggest that the controversy on whether duplicate genes evolve more slowly than singletons can be resolved when family size conservation is taken into consideration. Furthermore, we also observe that duplicate genes with family size conservation have the highest level of gene expression/expression breadth, the highest proportion of essential genes, and the lowest gene compactness, followed by singletons and then by duplicate genes without family size conservation. Such a trend accords well with our observations of evolutionary rates. Our results thus point to the importance of family size conservation in the evolution of duplicate genes.

Wide Bandgap Extrinsic Photoconductive Switches

NASA Astrophysics Data System (ADS)

Sullivan, James Stephen

Wide Bandgap Extrinsic Photoconductive Switches Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6H-SiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators. The successful development of a vanadium compensated, 6H-SiC extrinsic photoconductive switch for use as a closing switch for compact accelerator applications was realized by improvements made to the vanadium, nitrogen and boron impurity densities. The changes made to the impurity densities were based on the physical intuition outlined and simple rate equation models. The final 6H-SiC impurity 'recipe' calls for vanadium, nitrogen and boron densities of 2.5 e17 cm-3, 1.25e17 cm-3 and ≤ 1e16 cm-3, respectively. This recipe was originally developed to maximize the quantum efficiency of the vanadium compensated 6H-SiC, while maintaining a thermally stable semi-insulating material. The rate equation models indicate that, besides increasing the quantum efficiency, the impurity recipe should be expected to also increase the carrier recombination time. Three generations of 6H-SiC materials were tested. The third generation vanadium compensated 6H-SiC has average impurity densities close to the recipe values. Extrinsic photoconductive switches constructed from the third generation vanadium compensated, 6H-SiC, 1 mm thick, 1 cm2, substrates have achieved high power operation at 16 kV with pulsed currents exceeding 1400 Amperes and a minimum on resistance of 1 ohm. The extrinsic photoconductive switch performance of the third generation 6H-SiC material was improved by a factor of up to 50 for excitation at the 532 nm wavelength compared to the initial 6H-SiC material. Switches based on this material have been incorporated into a prototype compact proton medical accelerator being developed by the Compact Particle Acceleration Corporation (CPAC). The vanadium compensated, 6H-SiC, extrinsic photoconductive switch operates differently when excited by 1064, or 532 nm, wavelength light. The 6H-SiC extrinsic photoconductive switch is a unipolar device when excited with 1064 nm light. The carriers are electrons excited from filled vanadium acceptor levels and other electron traps located within 1.17 eV of the conduction band. The switch is bipolar at 532 nm since the carriers consist of holes, as well as electrons. The holes are primarily generated by the excitation of valence band electrons into empty trap/acceptor levels and by two-photon absorption. Carrier generation by two-photon absorption becomes more important at high applied optical intensity at 532 nm and contributes to the supralinear behavior of switch conductance as a function of optical power. The 6H-SiC switch material is trap dominated at low nitrogen to vanadium ratios. The trap dominated vanadium compensated 6H-SiC exhibits low quantum efficiency when excited with 1064 and 532 nm light and has a carrier recombination time of ˜ 150 - 300 ps. The vanadium compensated 6H-SiC transitions to an impurity dominated material as the ratio of nitrogen to vanadium is increased to 0.5. The increased nitrogen doping produces a material with much higher quantum efficiency and carrier recombination time of 0.9 to 1.0 ns. The iron compensated 2H-GaN did not perform well as an extrinsic photoconductive switch. The density of carriers generated at 1064 nm was, low indicating that there were very few electrons trapped in the iron acceptor level located at 0.5 - 0.6 eV below the conduction band. Carrier generation at 532 nm was dominated by two photon absorption resulting in the switch conductance increasing as the square of applied optical intensity. A minimum switch resistance of 0.8 ohms was calculated for the 400 nm thick, 1.2 by 1.2 cm, 2H-GaN switch for an applied optical intensity of 41.25 MW/cm2. An optical intensity of ˜ 70 MW/cm2 at 532 nm would be required to achieve a 0.8 ohm on resistance for a 1 mm thick, 1 cm2, 2H-GaN switch.

The impact of compaction and leachate recirculation on waste degradation in simulated landfills.

PubMed

Ko, Jae Hac; Yang, Fan; Xu, Qiyong

2016-07-01

This study investigated the impact of compaction and leachate recirculation on anaerobic degradation of municipal solid waste (MSW) at different methane formation phases. Two stainless steel lysimeters, C1 and C2, were constructed by equipping a hydraulic cylinder to apply pressure load (42kPs) on the MSW. When MSW started to produce methane, C1 was compacted, but C2 was compacted when the methane production rate declined from the peak generation rate. Methane production of C1was inhibited by the compaction and resulted in producing a total of 106L methane (44L/kgVS). However, the compaction in C2 promoted MSW degradation resulting in producing a total of 298L methane (125L/kgVS). The concentrations of volatile fatty acids and chemical oxygen demand showed temporary increases, when pressure load was applied. It was considered that the increased substrate accessibility within MSW by compaction could cause either the inhibition or the enhancement of methane production, depending the tolerability of methanogens on the acidic inhibition. Leachate recirculation also gave positive effects on methane generation from wet waste in the decelerated methanogenic phase by increasing mass transfer and the concentrations of volatile fatty acids. Copyright © 2016 Elsevier Ltd. All rights reserved.

Compaction bands in shale revealed through digital volume correlation of time-resolved X-ray tomography scans

NASA Astrophysics Data System (ADS)

McBeck, J.; Kobchenko, M.; Hall, S.; Tudisco, E.; Cordonnier, B.; Renard, F.

2017-12-01

Previous studies have identified compaction bands primarily within sandstones, and in fewer instances, within other porous rocks and sediments. Using Digital Volume Correlation (DVC) of X-ray microtomography scans, we find evidence of localized zones of high axial contraction that form tabular structures sub-perpendicular to maximum compression, σ1, in Green River shale. To capture in situ strain localization throughout loading, two shale cores were deformed in the HADES triaxial deformation apparatus installed on the X-ray microtomography beamline ID19 at the European Synchrotron Radiation Facility. In these experiments, we increase σ1 in increments of two MPa, with constant confining pressure (20 MPa), until the sample fails in macroscopic shear. After each stress step, a 3D image of the sample inside the rig is acquired at a voxel resolution of 6.5 μm. The evolution of lower density regions within 3D reconstructions of linear attenuation coefficients reveal the development of fractures that fail with some opening. If a fracture produces negligible dilation, it may remain undetected in image segmentation of the reconstructions. We use the DVC software TomoWarp2 to identify undetected fractures and capture the 3D incremental displacement field between each successive pair of microtomography scans acquired in each experiment. The corresponding strain fields reveal localized bands of high axial contraction that host minimal shear strain, and thus match the kinematic definition of compaction bands. The bands develop sub-perpendicular to σ1 in the two samples in which pre-existing bedding laminations were oriented parallel and perpendicular to σ1. As the shales deform plastically toward macroscopic shear failure, the number of bands and axial contraction within the bands increase, while the spacing between the bands decreases. Compaction band development accelerates the rate of overall axial contraction, increasing the mean axial contraction throughout the sample, and strengthens the shale sufficiently to localize shear faults. These results are critical to robust assessment of deformation patterns in shale rocks in contexts such as nuclear waste storage, hydrocarbon recovery and groundwater access.

Attrition and success rates of accelerated students in nursing courses: a systematic review.

PubMed

Doggrell, Sheila Anne; Schaffer, Sally

2016-01-01

There is a comprehensive literature on the academic outcomes (attrition and success) of students in traditional/baccalaureate nursing programs, but much less is known about the academic outcomes of students in accelerated nursing programs. The aim of this systematic review is to report on the attrition and success rates (either internal examination or NCLEX-RN) of accelerated students, compared to traditional students. For the systematic review, the databases (Pubmed, Cinahl and PsychINFO) and Google Scholar were searched using the search terms 'accelerated' or 'accreditation for prior learning', 'fast-track' or 'top up' and 'nursing' with 'attrition' or 'retention' or 'withdrawal' or 'success' from 1994 to January 2016. All relevant articles were included, regardless of quality. The findings of 19 studies of attrition rates and/or success rates for accelerated students are reported. For international accelerated students, there were only three studies, which are heterogeneous, and have major limitations. One of three studies has lower attrition rates, and one has shown higher success rates, than traditional students. In contrast, another study has shown high attrition and low success for international accelerated students. For graduate accelerated students, most of the studies are high quality, and showed that they have rates similar or better than traditional students. Thus, five of six studies have shown similar or lower attrition rates. Four of these studies with graduate accelerated students and an additional seven studies of success rates only, have shown similar or better success rates, than traditional students. There are only three studies of non-university graduate accelerated students, and these had weaknesses, but were consistent in reporting higher attrition rates than traditional students. The paucity and weakness of information available makes it unclear as to the attrition and/or success of international accelerated students in nursing programs. The good information available suggests that accelerated programs may be working reasonably well for the graduate students. However, the limited information available for non-university graduate students is weak, but consistent, in suggesting they may struggle in accelerated courses. Further studies are needed to determine the attrition and success rates of accelerated students, particularly for international and non-university graduate students.

On Shaft Data Acquisition System (OSDAS)

NASA Technical Reports Server (NTRS)

Pedings, Marc; DeHart, Shawn; Formby, Jason; Naumann, Charles

2012-01-01

On Shaft Data Acquisition System (OSDAS) is a rugged, compact, multiple-channel data acquisition computer system that is designed to record data from instrumentation while operating under extreme rotational centrifugal or gravitational acceleration forces. This system, which was developed for the Heritage Fuel Air Turbine Test (HFATT) program, addresses the problem of recording multiple channels of high-sample-rate data on most any rotating test article by mounting the entire acquisition computer onboard with the turbine test article. With the limited availability of slip ring wires for power and communication, OSDAS utilizes its own resources to provide independent power and amplification for each instrument. Since OSDAS utilizes standard PC technology as well as shared code interfaces with the next-generation, real-time health monitoring system (SPARTAA Scalable Parallel Architecture for Real Time Analysis and Acquisition), this system could be expanded beyond its current capabilities, such as providing advanced health monitoring capabilities for the test article. High-conductor-count slip rings are expensive to purchase and maintain, yet only provide a limited number of conductors for routing instrumentation off the article and to a stationary data acquisition system. In addition to being limited to a small number of instruments, slip rings are prone to wear quickly, and introduce noise and other undesirable characteristics to the signal data. This led to the development of a system capable of recording high-density instrumentation, at high sample rates, on the test article itself, all while under extreme rotational stress. OSDAS is a fully functional PC-based system with 48 channels of 24-bit, high-sample-rate input channels, phase synchronized, with an onboard storage capacity of over 1/2-terabyte of solid-state storage. This recording system takes a novel approach to the problem of recording multiple channels of instrumentation, integrated with the test article itself, packaged in a compact/rugged form factor, consuming limited power, all while rotating at high turbine speeds.

Experimental and Numerical Investigation of Compact Dielectric Wakefield Accelerators

DTIC Science & Technology

2016-03-01

kt) (TNT equivalent) 4.184 × 10 12 joule (J) British thermal unit (Btu) (thermochemical) 1.054 350 × 10 3 joule (J) foot-pound-force (ft lbf...respectively xs ’ ηδF , where η ’ 0.75 m is the horizontal dispersion function, and ys ’ κzF where κ ’ 20 is the vertical shearing factor and (zF , δF

The production of radionuclides for nuclear medicine from a compact, low-energy accelerator system.

PubMed

Webster, William D; Parks, Geoffrey T; Titov, Dmitry; Beasley, Paul

2014-05-01

The field of nuclear medicine is reliant on radionuclides for medical imaging procedures and radioimmunotherapy (RIT). The recent shut-downs of key radionuclide producers have highlighted the fragility of the current radionuclide supply network, however. To ensure that nuclear medicine can continue to grow, adding new diagnostic and therapy options to healthcare, novel and reliable production methods are required. Siemens are developing a low-energy, high-current - up to 10 MeV and 1 mA respectively - accelerator. The capability of this low-cost, compact system for radionuclide production, for use in nuclear medicine procedures, has been considered. The production of three medically important radionuclides - (89)Zr, (64)Cu, and (103)Pd - has been considered, via the (89)Y(p,n), (64)Ni(p,n) and (103)Rh(p,n) reactions, respectively. Theoretical cross-sections were generated using TALYS and compared to experimental data available from EXFOR. Stopping power values generated by SRIM have been used, with the TALYS-generated excitation functions, to calculate potential yields and isotopic purity in different irradiation regimes. The TALYS excitation functions were found to have a good agreement with the experimental data available from the EXFOR database. It was found that both (89)Zr and (64)Cu could be produced with high isotopic purity (over 99%), with activity yields suitable for medical diagnostics and therapy, at a proton energy of 10MeV. At 10MeV, the irradiation of (103)Rh produced appreciable quantities of (102)Pd, reducing the isotopic purity. A reduction in beam energy to 9.5MeV increased the radioisotopic purity to 99% with only a small reduction in activity yield. This work demonstrates that the low-energy, compact accelerator system under development by Siemens would be capable of providing sufficient quantities of (89)Zr, (64)Cu, and (103)Pd for use in medical diagnostics and therapy. It is suggested that the system could be used to produce many other isotopes currently useful to nuclear medicine. Copyright © 2014 Elsevier Inc. All rights reserved.

Efficiency of Magnetic to Kinetic Energy Conversion in a Monopole Magnetosphere

NASA Astrophysics Data System (ADS)

Tchekhovskoy, Alexander; McKinney, Jonathan C.; Narayan, Ramesh

2009-07-01

Unconfined relativistic outflows from rotating, magnetized compact objects are often well modeled by assuming that the field geometry is approximately a split-monopole at large radii. Earlier work has indicated that such an unconfined flow has an inefficient conversion of magnetic energy to kinetic energy. This has led to the conclusion that ideal magnetohydrodynamical (MHD) processes fail to explain observations of, e.g., the Crab pulsar wind at large radii where energy conversion appears efficient. In addition, as a model for astrophysical jets, the monopole field geometry has been abandoned in favor of externally confined jets since the latter appeared to be generically more efficient jet accelerators. We perform time-dependent axisymmetric relativistic MHD simulations in order to find steady-state solutions for a wind from a compact object endowed with a monopole field geometry. Our simulations follow the outflow for 10 orders of magnitude in distance from the compact object, which is large enough to study both the initial "acceleration zone" of the magnetized wind as well as the asymptotic "coasting zone." We obtain the surprising result that acceleration is actually efficient in the polar region, which develops a jet despite not being confined by an external medium. Our models contain jets that have sufficient energy to account for moderately energetic long and short gamma-ray burst (GRB) events (~1051-1052 erg), collimate into narrow opening angles (opening half-angle θ j ≈ 0.03 rad), become matter-dominated at large radii (electromagnetic energy flux per unit matter energy flux σ < 1), and move at ultrarelativistic Lorentz factors (γ j ~ 200 for our fiducial model). The simulated jets have γ j θ j ~ 5-15, so they are in principle capable of generating "achromatic jet breaks" in GRB afterglow light curves. By defining a "causality surface" beyond which the jet cannot communicate with a generalized "magnetic nozzle" near the axis of rotation, we obtain approximate analytical solutions for the Lorentz factor that fit the numerical solutions well. This allows us to extend our results to monopole wind models with arbitrary magnetization. Overall, our results demonstrate that the production of ultrarelativistic jets is a more robust process than previously thought.

How rivers remember: The impacts of prior stress history on grain scale topography and bedload transport

NASA Astrophysics Data System (ADS)

Masteller, C.; Finnegan, N. J.

2016-12-01

Memory is preserved in rivers through the sorting and arrangement of grains on their beds, which reflect previous flow conditions. Manifestations of this phenomenon include observed hysteresis in bedload rating curves (e.g., Moog and Whiting, 1998; Reid et al., 1985) and correlations between the stage at the start of a transport event and the stage at the end of transport during a previous event (Turowski et al., 2011). This observed history dependence represents a key difficulty in the accurate prediction of bedload transport rates. To begin to systematically explore these memory effects on fluvial bedload transport, we experimentally examined how a gravel bed river responds to variations in prior stress history. Specifically, we compare the response of the grain-scale topography of a gravel riverbed to both below and above threshold flow conditions. We find that under low flow, when no sediment transport occurs, the bed compacts as the highest protruding grains pivot into low elevation pockets. This reorganization appears to occur logarithmically with low flow duration, making it analogous to compaction observed in dry granular flows subjected to agitation. The amount of prior compaction affects bedload transport rates at the onset of above threshold flow, with more compact beds yielding less bedload flux. In contrast, we find that under sediment-transporting flows, the bed dilates because grains are re-deposited in relatively precarious positions. During the same applied transport flow, we observe that the most pronounced dilation occurs when the initial bed is the most compact, suggesting that the potential for dilation is related to the degree of previous compaction. These observations highlight that a gravel bed experiences two different behaviors, compaction under low shear stresses, and dilation under high, sediment transporting, shear stresses. This observation is consistent with previous studies on the compaction and dilation of granular media, as well as flume experiments conducted using glass beads. Further, this study highlights the varying response of grain-scale topography and bedload transport rates to prior flow and bed conditions, demonstrating history dependence in fluvial systems.

Greenland Ice Sheet Mass Balance: Distribution of Increased Mass Loss with Climate Warming; 2003-07 Versus 1992-2002

NASA Technical Reports Server (NTRS)

Zwally, H. Jay; Li, Jun; Benner, Anita C.; Beckley, Matthew; Cornejo, Helen G.; DiMarzio, John; Giovinetto, Mario B.; Neumann, Thomas A.; Robbins, John; Saba, Jack L.;

Ice-sheet modelling accelerated by graphics cards

NASA Astrophysics Data System (ADS)

Brædstrup, Christian Fredborg; Damsgaard, Anders; Egholm, David Lundbek

2014-11-01

Studies of glaciers and ice sheets have increased the demand for high performance numerical ice flow models over the past decades. When exploring the highly non-linear dynamics of fast flowing glaciers and ice streams, or when coupling multiple flow processes for ice, water, and sediment, researchers are often forced to use super-computing clusters. As an alternative to conventional high-performance computing hardware, the Graphical Processing Unit (GPU) is capable of massively parallel computing while retaining a compact design and low cost. In this study, we present a strategy for accelerating a higher-order ice flow model using a GPU. By applying the newest GPU hardware, we achieve up to 180× speedup compared to a similar but serial CPU implementation. Our results suggest that GPU acceleration is a competitive option for ice-flow modelling when compared to CPU-optimised algorithms parallelised by the OpenMP or Message Passing Interface (MPI) protocols.

The NSCL electron beam ion trap for the reacceleration of rare isotopes coming to life: first extraction tests with a high-current electron gun.

PubMed

Schwarz, S; Bollen, G; Johnson, M; Kester, O; Kostin, M; Ottarson, J; Portillo, M; Wilson, C; López-Urrutia, J R Crespo; Dilling, J

2010-02-01

NSCL is currently constructing the ReA3 reaccelerator, which will accelerate rare isotopes obtained from gas stopping of fast-fragment beams to energies of up to 3 MeV/u for uranium and higher for lighter ions. A high-current charge breeder, based on an electron beam ion trap (EBIT), has been chosen as the first step in the acceleration process, as it has the potential to efficiently produce highly charged ions in a single charge state. These ions are fed into a compact linear accelerator consisting of a radio frequency quadrupole structure and superconducting cavities. The NSCL EBIT has been fully designed with most of the parts constructed. The design concept of the EBIT and results from initial commissioning tests of the electron gun and collector with a temporary 0.4 T magnet are presented.

X-ray phase contrast imaging of biological specimens with femtosecond pulses of betatron radiation from a compact laser plasma wakefield accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kneip, S.; Center for Ultrafast Optical Science, University of Michigan, Ann Arbor 48109; McGuffey, C.

2011-08-29

We show that x-rays from a recently demonstrated table top source of bright, ultrafast, coherent synchrotron radiation [Kneip et al., Nat. Phys. 6, 980 (2010)] can be applied to phase contrast imaging of biological specimens. Our scheme is based on focusing a high power short pulse laser in a tenuous gas jet, setting up a plasma wakefield accelerator that accelerates and wiggles electrons analogously to a conventional synchrotron, but on the centimeter rather than tens of meter scale. We use the scheme to record absorption and phase contrast images of a tetra fish, damselfly and yellow jacket, in particular highlightingmore » the contrast enhancement achievable with the simple propagation technique of phase contrast imaging. Coherence and ultrafast pulse duration will allow for the study of various aspects of biomechanics.« less

Control of quasi-monoenergetic electron beams from laser-plasma accelerators with adjustable shock density profile

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, Hai-En; Swanson, Kelly K.; Barber, Sam K.

The injection physics in a shock-induced density down-ramp injector was characterized, demonstrating precise control of a laser-plasma accelerator (LPA). Using a jet-blade assembly, experiments systematically v aried the shock injector profile, including shock angle, shock position, up-ramp width, and acceleration length. Our work demonstrates that beam energy, energy spread, and pointing can be controlled by adjusting these parameters. As a result, an electron beam that was highly tunable from 25 to 300 MeV with 8% energy spread (ΔE FWHM/E), 1.5 mrad divergence, and 0.35 mrad pointing fluctuation was produced. Particle-in-cell simulation characterized how variation in the shock angle and up-rampmore » width impacted the injection process. This highly controllable LPA represents a suitable, compact electron beam source for LPA applications such as Thomson sources and free-electron lasers.« less

Cryogenic system for BERLinPro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anders, W.; Hellwig, A.; Knobloch, J.

2014-01-29

In 2010 Helmholtz-Zentrum Berlin (HZB) received funding to design and build the Berlin Energy Recovery Linac Project BERLinPro. The goal of this compact Energy recovery linac (ERL) is to develop the accelerator physics and technology required to generate and accelerate a 100-mA, 1-mm mrad emittance electron beam. The BERLinPro know-how can then be transferred to various ERL-based applications. All accelerating RF cavities including the electron source are based on superconducting technology operated at 1.8 K. A Linde L700 helium liquefier is supplying 4.5 K helium. The subatmospheric pressure of 16 mbar of the helium bath of the cavities will bemore » achieved by pumping with a set of cold compressors and warm vacuum pumps. While the L700 is already in operating, the 1.8 K system and the helium transfer system are in design phase.« less

Generation of three-dimensional optical cusp beams with ultrathin metasurfaces.

PubMed

Liu, Weiwei; Zhang, Yuchao; Gao, Jie; Yang, Xiaodong

2018-06-22

Cusp beams are one type of complex structured beams with unique multiple self-accelerating channels and needle-like field structures owning great potentials to advance applications such as particle micromanipulation and super-resolution imaging. The traditional method to generate optical catastrophe is based on cumbrous reflective diffraction optical elements, which makes optical system complicated and hinders the nanophotonics integration. Here we design geometric phase based ultrathin plasmonic metasurfaces made of nanoslit antennas to produce three-dimensional (3D) optical cusp beams with variable numbers of self-accelerating channels in a broadband wavelength range. The entire beam propagation profiles of the cusp beams generated from the metasurfaces are mapped theoretically and experimentally. The special self-accelerating behavior and caustics concentration property of the cups beams are also demonstrated. Our results provide great potentials for promoting metasurface-enabled compact photonic devices used in wide applications of light-matter interactions.

Enabling large-scale viscoelastic calculations via neural network acceleration

NASA Astrophysics Data System (ADS)

Robinson DeVries, P.; Thompson, T. B.; Meade, B. J.

2017-12-01

One of the most significant challenges involved in efforts to understand the effects of repeated earthquake cycle activity are the computational costs of large-scale viscoelastic earthquake cycle models. Deep artificial neural networks (ANNs) can be used to discover new, compact, and accurate computational representations of viscoelastic physics. Once found, these efficient ANN representations may replace computationally intensive viscoelastic codes and accelerate large-scale viscoelastic calculations by more than 50,000%. This magnitude of acceleration enables the modeling of geometrically complex faults over thousands of earthquake cycles across wider ranges of model parameters and at larger spatial and temporal scales than have been previously possible. Perhaps most interestingly from a scientific perspective, ANN representations of viscoelastic physics may lead to basic advances in the understanding of the underlying model phenomenology. We demonstrate the potential of artificial neural networks to illuminate fundamental physical insights with specific examples.

Control of quasi-monoenergetic electron beams from laser-plasma accelerators with adjustable shock density profile

DOE PAGES

Tsai, Hai-En; Swanson, Kelly K.; Barber, Sam K.; ...

2018-04-13

The injection physics in a shock-induced density down-ramp injector was characterized, demonstrating precise control of a laser-plasma accelerator (LPA). Using a jet-blade assembly, experiments systematically v aried the shock injector profile, including shock angle, shock position, up-ramp width, and acceleration length. Our work demonstrates that beam energy, energy spread, and pointing can be controlled by adjusting these parameters. As a result, an electron beam that was highly tunable from 25 to 300 MeV with 8% energy spread (ΔE FWHM/E), 1.5 mrad divergence, and 0.35 mrad pointing fluctuation was produced. Particle-in-cell simulation characterized how variation in the shock angle and up-rampmore » width impacted the injection process. This highly controllable LPA represents a suitable, compact electron beam source for LPA applications such as Thomson sources and free-electron lasers.« less

Parametric emittance measurements of electron beams produced by a laser plasma accelerator

NASA Astrophysics Data System (ADS)

Barber, S. K.; van Tilborg, J.; Schroeder, C. B.; Lehe, R.; Tsai, H.-E.; Swanson, K. K.; Steinke, S.; Nakamura, K.; Geddes, C. G. R.; Benedetti, C.; Esarey, E.; Leemans, W. P.

2018-05-01

Laser plasma accelerators (LPA) offer an exciting possibility to deliver high energy, high brightness electrons beams in drastically smaller distance scales than is typical for conventional accelerators. As such, LPAs draw considerable attention as potential drivers for next generation light sources and for a compact linear collider. In order to asses the viability of an LPA source for a particular application, the brightness of the source should be properly characterized. In this paper, we present charge dependent transverse emittance measurements of LPA sources using both ionization injection and shock induced density down ramp injection, with the latter delivering smaller transverse emittances by a factor of two when controlling for charge density. The single shot emittance method is described in detail with a discussion on limitations related to second order transport effects. The direct role of space charge is explored through a series of simulations and found to be consistent with experimental observations.

Control of quasi-monoenergetic electron beams from laser-plasma accelerators with adjustable shock density profile

NASA Astrophysics Data System (ADS)

Tsai, Hai-En; Swanson, Kelly K.; Barber, Sam K.; Lehe, Remi; Mao, Hann-Shin; Mittelberger, Daniel E.; Steinke, Sven; Nakamura, Kei; van Tilborg, Jeroen; Schroeder, Carl; Esarey, Eric; Geddes, Cameron G. R.; Leemans, Wim

2018-04-01

The injection physics in a shock-induced density down-ramp injector was characterized, demonstrating precise control of a laser-plasma accelerator (LPA). Using a jet-blade assembly, experiments systematically varied the shock injector profile, including shock angle, shock position, up-ramp width, and acceleration length. Our work demonstrates that beam energy, energy spread, and pointing can be controlled by adjusting these parameters. As a result, an electron beam that was highly tunable from 25 to 300 MeV with 8% energy spread (ΔEFWHM/E), 1.5 mrad divergence, and 0.35 mrad pointing fluctuation was produced. Particle-in-cell simulation characterized how variation in the shock angle and up-ramp width impacted the injection process. This highly controllable LPA represents a suitable, compact electron beam source for LPA applications such as Thomson sources and free-electron lasers.

Mechanism of vacuum breakdown in radio-frequency accelerating structures

NASA Astrophysics Data System (ADS)

Barengolts, S. A.; Mesyats, V. G.; Oreshkin, V. I.; Oreshkin, E. V.; Khishchenko, K. V.; Uimanov, I. V.; Tsventoukh, M. M.

2018-06-01

It has been investigated whether explosive electron emission may be the initiating mechanism of vacuum breakdown in the accelerating structures of TeV linear electron-positron colliders (Compact Linear Collider). The physical processes involved in a dc vacuum breakdown have been considered, and the relationship between the voltage applied to the diode and the time delay to breakdown has been found. Based on the results obtained, the development of a vacuum breakdown in an rf electric field has been analyzed and the main parameters responsible for the initiation of explosive electron emission have been estimated. The formation of craters on the cathode surface during explosive electron emission has been numerically simulated, and the simulation results are discussed.

GASEOUS DISCHARGE DEVICE

DOEpatents

Gow, J.D.

1961-01-10

An extremely compact two-terminal gaseous discharge device is described that is capable of producing neutrons in copious quantities, relatively high energy ions, intense x rays, and the like. Principal novelty resides in the provision of a crossed electric-magnetic field region in the discharge envelope that traps electrons and accelerates them to very high energies to provide an intense ionizing medium adjacent the anode of the device for ionizing gas therein with extremely high efficiency. In addition, the crossed-field trapping region holds the electrons close to the anode whereby the acceleration of ions to the cathode is not materially effected by the electron sheath and the ions assume substantially the full energy of the anodecathode potential drop. (auth)

Generation of Ramped Current Profiles in Relativistic Electron Beams Using Wakefields in Dielectric Structures

DOE PAGES

Andonian, G.; Barber, S.; O’Shea, F. H.; ...

2017-02-03

We show that temporal pulse tailoring of charged-particle beams is essential to optimize efficiency in collinear wakefield acceleration schemes. In this Letter, we demonstrate a novel phase space manipulation method that employs a beam wakefield interaction in a dielectric structure, followed by bunch compression in a permanent magnet chicane, to longitudinally tailor the pulse shape of an electron beam. This compact, passive, approach was used to generate a nearly linearly ramped current profile in a relativistic electron beam experiment carried out at the Brookhaven National Laboratory Accelerator Test Facility. Here, we report on these experimental results including beam and wakefieldmore » diagnostics and pulse profile reconstruction techniques.« less

Slip behaviour of carbonate-bearing faults subjected to fluid pressure stimulations

NASA Astrophysics Data System (ADS)

Collettini, Cristiano; Scuderi, Marco; Marone, Chris

2017-04-01

Earthquakes caused by fluid injection within reservoir have become an important topic of political and social discussion as new drilling and improved technologies enable the extraction of oil and gas from previously unproductive formations. During reservoir stimulation, the coupled interactions of frictional and fluid flow properties together with the stress state control both the onset of fault slip and fault slip behaviour. However, currently, there are no studies under controlled, laboratory conditions for which the effect of fluid pressure on fault slip behaviour can be deduced. To cover this gap, we have developed laboratory experiments where we monitor fault slip evolution at constant shear stress but with increasing fluid pressure, i.e. reducing the effective normal stress. Experiments have been conducted in the double direct shear configuration within a pressure vessel on carbonate fault gouge, characterized by a slightly velocity strengthening friction that is indicative of stable aseismic creep. In our experiments fault slip history can be divided in three main stages: 1) for high effective normal stress the fault is locked and undergoes compaction; 2) when the shear and effective normal stress reach the failure condition, accelerated creep is associated to fault dilation; 3) further pressurization leads to an exponential acceleration during fault compaction and slip localization. Our results indicate that fault weakening induced by fluid pressurization overcomes the velocity strengthening behaviour of calcite gouge, resulting in fast acceleration and earthquake slip. As applied to tectonic faults our results suggest that a larger number of crustal faults, including those slightly velocity strengthening, can experience earthquake slip due to fluid pressurization.

[Effect of compaction pressure on the properties of dental machinable zirconia ceramic].

PubMed

Huang, Hui; Wei, Bin; Zhang, Fu-qiang; Sun, Jing; Gao, Lian

2010-10-01

To investigate the effect of compaction pressure on the linear shrinkage, sintering property and machinability of the dental zirconia ceramic. The nano-size zirconia powder was compacted at different isostatic pressure and sintered at different temperature. The linear shrinkage of sintered body was measured and the relative density was tested using the Archimedes method. The cylindrical surface of pre-sintering blanks was traversed using a hard metal tool. Surface and edge quality were checked visually using light stereo microscopy. The sintering behaviour depended on the compaction pressure. Increasing compaction pressure led to higher sintering rate and lower sintering temperature. Increasing compaction pressure also led to decreasing linear shrinkage of the sintered bodies, from 24.54% of 50 MPa to 20.9% of 400 MPa. Compaction pressure showed only a weak influence on machinability of zirconia blanks, but the higher compaction pressure resulted in the poor surface quality. The better sintering property and machinability of dental zirconia ceramic is found for 200-300 MPa compaction pressure.

Searching Ultra-compact Pulsar Binaries with Abnormal Timing Behavior

NASA Astrophysics Data System (ADS)

Gong, B. P.; Li, Y. P.; Yuan, J. P.; Tian, J.; Zhang, Y. Y.; Li, D.; Jiang, B.; Li, X. D.; Wang, H. G.; Zou, Y. C.; Shao, L. J.

2018-03-01

Ultra-compact pulsar binaries are both ideal sources of gravitational radiation for gravitational wave detectors and laboratories for fundamental physics. However, the shortest orbital period of all radio pulsar binaries is currently 1.6 hr. The absence of pulsar binaries with a shorter orbital period is most likely due to technique limit. This paper points out that a tidal effect occurring on pulsar binaries with a short orbital period can perturb the orbital elements and result in a significant change in orbital modulation, which dramatically reduces the sensitivity of the acceleration searching that is widely used. Here a new search is proposed. The abnormal timing residual exhibited in a single pulse observation is simulated by a tidal effect occurring on an ultra-compact binary. The reproduction of the main features represented by the sharp peaks displayed in the abnormal timing behavior suggests that pulsars like PSR B0919+06 could be a candidate for an ultra-compact binary of an orbital period of ∼10 minutes and a companion star of a white dwarf star. The binary nature of such a candidate is further tested by (1) comparing the predicted long-term binary effect with decades of timing noise observed and (2) observing the optical counterpart of the expected companion star. Test (1) likely supports our model, while more observations are needed in test (2). Some interesting ultra-compact binaries could be found in the near future by applying such a new approach to other binary candidates.

Controllability in Multi-Stage Laser Ion Acceleration

NASA Astrophysics Data System (ADS)

Kawata, S.; Kamiyama, D.; Ohtake, Y.; Barada, D.; Ma, Y. Y.; Kong, Q.; Wang, P. X.; Gu, Y. J.; Li, X. F.; Yu, Q.

2015-11-01

The present paper shows a concept for a future laser ion accelerator, which should have an ion source, ion collimators, ion beam bunchers and ion post acceleration devices. Based on the laser ion accelerator components, the ion particle energy and the ion energy spectrum are controlled, and a future compact laser ion accelerator would be designed for ion cancer therapy or for ion material treatment. In this study each component is designed to control the ion beam quality. The energy efficiency from the laser to ions is improved by using a solid target with a fine sub-wavelength structure or a near-critical density gas plasma. The ion beam collimation is performed by holes behind the solid target or a multi-layered solid target. The control of the ion energy spectrum and the ion particle energy, and the ion beam bunching are successfully realized by a multi-stage laser-target interaction. A combination of each component provides a high controllability of the ion beam quality to meet variable requirements in various purposes in the laser ion accelerator. The work was partly supported by MEXT, JSPS, ASHULA project/ ILE, Osaka University, CORE (Center for Optical Research and Education, Utsunomiya University, Japan), Fudan University and CDI (Creative Dept. for Innovation) in CCRD, Utsunomiya University.

3D Resistive MHD Simulations of Formation, Compression, and Acceleration of Compact Tori

NASA Astrophysics Data System (ADS)

Woodruff, Simon; Meyer, Thomas; Stuber, James; Romero-Talamas, Carlos; Brown, Michael; Kaur, Manjit; Schaffner, David

2017-10-01

We present results from extended resistive 3D MHD simulations (NIMROD) pertaining to a new formation method for toroidal plasmas using a reconnection region that forms in a radial implosion, and results from the acceleration of CTs along a drift tube that are accelerated by a coil and are allowed to go tilt unstable and form a helical minimum energy state. The new formation method results from a reconnection region that is generated between two magnetic compression coils that are ramped to 320kV in 2 μs. When the compressing field is aligned anti-parallel to a pre-existing CT, a current sheet and reconnection region forms that accelerates plasma radially inwards up to 500km/s which stagnates and directed energy converts to thermal, raising temperatures to 500eV. When field is aligned parallel to the pre-existing CT, the configuration can be accelerated along a drift tube. For certain ratios of magnetic field to density, the CT goes tilt-unstable forming a twisted flux rope, which can also be accelerated and stagnated on an end wall, where temperature and field increases as the plasma compresses. We compare simulation results with adiabatic scaling relations. Work supported by ARPA-E ALPHA program and DARPA.

Demonstration of the hollow channel plasma wakefield accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gessner, Spencer J.

2016-09-17

A plasma wakefield accelerator is a device that converts the energy of a relativistic particle beam into a large-amplitude wave in a plasma. The plasma wave, or wakefield, supports an enormous electricfield that is used to accelerate a trailing particle beam. The plasma wakefield accelerator can therefore be used as a transformer, transferring energy from a high-charge, low-energy particle beam into a high-energy, low-charge particle beam. This technique may lead to a new generation of ultra-compact, high-energy particle accelerators. The past decade has seen enormous progress in the field of plasma wakefield acceleration with experimental demonstrations of the acceleration ofmore » electron beams by several gigaelectron-volts. The acceleration of positron beams in plasma is more challenging, but also necessary for the creation of a high-energy electron-positron collider. Part of the challenge is that the plasma responds asymmetrically to electrons and positrons, leading to increased disruption of the positron beam. One solution to this problem, first proposed over twenty years ago, is to use a hollow channel plasma which symmetrizes the response of the plasma to beams of positive and negative charge, making it possible to accelerate positrons in plasma without disruption. In this thesis, we describe the theory relevant to our experiment and derive new results when needed. We discuss the development and implementation of special optical devices used to create long plasma channels. We demonstrate for the first time the generation of meter-scale plasma channels and the acceleration of positron beams therein.« less

The FAST (FRC Acceleration Space Thruster) Experiment

NASA Technical Reports Server (NTRS)

Martin, Adam; Eskridge, R.; Lee, M.; Richeson, J.; Smith, J.; Thio, Y. C. F.; Slough, J.; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

The Field Reverse Configuration (FRC) is a magnetized plasmoid that has been developed for use in magnetic confinement fusion. Several of its properties suggest that it may also be useful as a thruster for in-space propulsion. The FRC is a compact toroid that has only poloidal field, and is characterized by a high plasma beta = (P)/(B (sup 2) /2Mu0), the ratio of plasma pressure to magnetic field pressure, so that it makes efficient use of magnetic field to confine a plasma. In an FRC thruster, plasmoids would be repetitively formed and accelerated to high velocity; velocities of = 250 km/s (Isp = 25,000s) have already been achieved in fusion experiments. The FRC is inductively formed and accelerated, and so is not subject to the problem of electrode erosion. As the plasmoid may be accelerated over an extended length, it can in principle be made very efficient. And the achievable jet powers should be scalable to the MW range. A 10 kW thruster experiment - FAST (FRC Acceleration Space Thruster) has just started at the Marshall Space Flight Center. The design of FAST and the status of construction and operation will be presented.

Applications of laser wakefield accelerator-based light sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albert, Felicie; Thomas, Alec G. R.

Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons inmore » the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. Here, we first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.« less

Applications of laser wakefield accelerator-based light sources

DOE PAGES

Albert, Felicie; Thomas, Alec G. R.

2016-10-01

Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons inmore » the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. Here, we first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.« less

Evaluation of the deformation behavior of binary systems of methacrylic acid copolymers and hydroxypropyl methylcellulose using a compaction simulator.

PubMed

Tatavarti, Aditya S; Muller, Francis X; Hoag, Stephen W

2008-02-04

Methacrylic acid copolymers have been shown to enhance release of weakly basic drugs from rate controlling polymer matrices through the mechanism of microenvironmental pH modulation. Since these matrices are typically formed through a compaction process, an understanding of the deformation behavior of these polymers in there neat form and in combination with rate controlling polymers such as HPMC is critical to their successful formulation. Binary mixes of two methacrylic acid copolymers, Eudragit L100 and L100-55 in combination with HPMC K4M were subjected to compaction studies on a compaction simulator. The deformation behavior of the powder mixes was analyzed based on pressure-porosity relationships, strain rate sensitivity (SRS), residual die wall force data and work of compaction. Methacrylic acid copolymers, L100-55 and L-100 and the hydrophilic polymer, HPMC K4M exhibited Heckel plots representative of plastic deformation although L-100 exhibited significantly greater resistance to densification as evident from the high yield pressure values ( approximately 120MPa). The yield pressures for the binary mixes were linearly related to the weight fractions of the components. All powder mixes exhibited significant speed sensitivity with SRS values ranging from 21.7% to 42.4%. The residual die-wall pressures indicated that at slow speeds (1mm/s) and at lower pressures (<150MPa), HPMC possesses significant elastic behavior. However, the good compacts formed at this punch speed indicate significant plastic deformation and bond formation which is able to predominate over the elastic recovery component. The apparent mean yield pressure values, the residual die-wall forces and the net work of compaction exhibited a linear relationship with mixture composition, thereby indicating predictability of these parameters based on the behavior of the neat materials.

Accelerating rates of cognitive decline and imaging markers associated with β-amyloid pathology.

PubMed

Insel, Philip S; Mattsson, Niklas; Mackin, R Scott; Schöll, Michael; Nosheny, Rachel L; Tosun, Duygu; Donohue, Michael C; Aisen, Paul S; Jagust, William J; Weiner, Michael W

2016-05-17

To estimate points along the spectrum of β-amyloid pathology at which rates of change of several measures of neuronal injury and cognitive decline begin to accelerate. In 460 patients with mild cognitive impairment (MCI), we estimated the points at which rates of florbetapir PET, fluorodeoxyglucose (FDG) PET, MRI, and cognitive and functional decline begin to accelerate with respect to baseline CSF Aβ42. Points of initial acceleration in rates of decline were estimated using mixed-effects regression. Rates of neuronal injury and cognitive and even functional decline accelerate substantially before the conventional threshold for amyloid positivity, with rates of florbetapir PET and FDG PET accelerating early. Temporal lobe atrophy rates also accelerate prior to the threshold, but not before the acceleration of cognitive and functional decline. A considerable proportion of patients with MCI would not meet inclusion criteria for a trial using the current threshold for amyloid positivity, even though on average, they are experiencing cognitive/functional decline associated with prethreshold levels of CSF Aβ42. Future trials in early Alzheimer disease might consider revising the criteria regarding β-amyloid thresholds to include the range of amyloid associated with the first signs of accelerating rates of decline. © 2016 American Academy of Neurology.

Accelerating rates of cognitive decline and imaging markers associated with β-amyloid pathology

PubMed Central

Mattsson, Niklas; Mackin, R. Scott; Schöll, Michael; Nosheny, Rachel L.; Tosun, Duygu; Donohue, Michael C.; Aisen, Paul S.; Jagust, William J.; Weiner, Michael W.

2016-01-01

Objective: To estimate points along the spectrum of β-amyloid pathology at which rates of change of several measures of neuronal injury and cognitive decline begin to accelerate. Methods: In 460 patients with mild cognitive impairment (MCI), we estimated the points at which rates of florbetapir PET, fluorodeoxyglucose (FDG) PET, MRI, and cognitive and functional decline begin to accelerate with respect to baseline CSF Aβ42. Points of initial acceleration in rates of decline were estimated using mixed-effects regression. Results: Rates of neuronal injury and cognitive and even functional decline accelerate substantially before the conventional threshold for amyloid positivity, with rates of florbetapir PET and FDG PET accelerating early. Temporal lobe atrophy rates also accelerate prior to the threshold, but not before the acceleration of cognitive and functional decline. Conclusions: A considerable proportion of patients with MCI would not meet inclusion criteria for a trial using the current threshold for amyloid positivity, even though on average, they are experiencing cognitive/functional decline associated with prethreshold levels of CSF Aβ42. Future trials in early Alzheimer disease might consider revising the criteria regarding β-amyloid thresholds to include the range of amyloid associated with the first signs of accelerating rates of decline. PMID:27164667

Accelerating rates of cognitive decline and imaging markers associated with β-amyloid pathology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Insel, Philip S.; Mattsson, Niklas; Mackin, R. Scott

Objective: Our objective is to estimate points along the spectrum of β-amyloid pathology at which rates of change of several measures of neuronal injury and cognitive decline begin to accelerate. Methods: In 460 patients with mild cognitive impairment (MCI), we estimated the points at which rates of florbetapir PET, fluorodeoxyglucose (FDG) PET, MRI, and cognitive and functional decline begin to accelerate with respect to baseline CSF Aβ 42. Points of initial acceleration in rates of decline were estimated using mixed-effects regression. Results: Rates of neuronal injury and cognitive and even functional decline accelerate substantially before the conventional threshold for amyloidmore » positivity, with rates of florbetapir PET and FDG PET accelerating early. Temporal lobe atrophy rates also accelerate prior to the threshold, but not before the acceleration of cognitive and functional decline. Conclusions: A considerable proportion of patients with MCI would not meet inclusion criteria for a trial using the current threshold for amyloid positivity, even though on average, they are experiencing cognitive/functional decline associated with prethreshold levels of CSF Aβ 42. Lastly, future trials in early Alzheimer disease might consider revising the criteria regarding β-amyloid thresholds to include the range of amyloid associated with the first signs of accelerating rates of decline.« less

Accelerating rates of cognitive decline and imaging markers associated with β-amyloid pathology

DOE PAGES

Insel, Philip S.; Mattsson, Niklas; Mackin, R. Scott; ...

2016-04-15

Objective: Our objective is to estimate points along the spectrum of β-amyloid pathology at which rates of change of several measures of neuronal injury and cognitive decline begin to accelerate. Methods: In 460 patients with mild cognitive impairment (MCI), we estimated the points at which rates of florbetapir PET, fluorodeoxyglucose (FDG) PET, MRI, and cognitive and functional decline begin to accelerate with respect to baseline CSF Aβ 42. Points of initial acceleration in rates of decline were estimated using mixed-effects regression. Results: Rates of neuronal injury and cognitive and even functional decline accelerate substantially before the conventional threshold for amyloidmore » positivity, with rates of florbetapir PET and FDG PET accelerating early. Temporal lobe atrophy rates also accelerate prior to the threshold, but not before the acceleration of cognitive and functional decline. Conclusions: A considerable proportion of patients with MCI would not meet inclusion criteria for a trial using the current threshold for amyloid positivity, even though on average, they are experiencing cognitive/functional decline associated with prethreshold levels of CSF Aβ 42. Lastly, future trials in early Alzheimer disease might consider revising the criteria regarding β-amyloid thresholds to include the range of amyloid associated with the first signs of accelerating rates of decline.« less

A compact and continuously driven supersonic plasma and neutral source.

PubMed

Asai, T; Itagaki, H; Numasawa, H; Terashima, Y; Hirano, Y; Hirose, A

2010-10-01

A compact and repetitively driven plasma source has been developed by utilizing a magnetized coaxial plasma gun (MCPG) for diagnostics requiring deep penetration of a large amount of neutral flux. The system consists of a MCPG 95mm in length with a DN16 ConFlat connection port and an insulated gate bipolar transistor (IGBT) inverter power unit. The power supply consists of an array of eight IGBT units and is able to switch the discharge on and off at up to 10 kV and 600 A with a maximum repetitive frequency of 10 kHz. Multiple short duration discharge pulses maximize acceleration efficiency of the plasmoid. In the case of a 10 kHz operating frequency, helium-plasmoids in the velocity range of 20 km/s can be achieved.

Compact mass spectrometer for plasma discharge ion analysis

DOEpatents

Tuszewski, M.G.

1997-07-22

A mass spectrometer and methods are disclosed for mass spectrometry which are useful in characterizing a plasma. This mass spectrometer for determining type and quantity of ions present in a plasma is simple, compact, and inexpensive. It accomplishes mass analysis in a single step, rather than the usual two-step process comprised of ion extraction followed by mass filtering. Ions are captured by a measuring element placed in a plasma and accelerated by a known applied voltage. Captured ions are bent into near-circular orbits by a magnetic field such that they strike a collector, producing an electric current. Ion orbits vary with applied voltage and proton mass ratio of the ions, so that ion species may be identified. Current flow provides an indication of quantity of ions striking the collector. 7 figs.

Compact mass spectrometer for plasma discharge ion analysis

DOEpatents

Tuszewski, Michel G.

1997-01-01

A mass spectrometer and methods for mass spectrometry which are useful in characterizing a plasma. This mass spectrometer for determining type and quantity of ions present in a plasma is simple, compact, and inexpensive. It accomplishes mass analysis in a single step, rather than the usual two-step process comprised of ion extraction followed by mass filtering. Ions are captured by a measuring element placed in a plasma and accelerated by a known applied voltage. Captured ions are bent into near-circular orbits by a magnetic field such that they strike a collector, producing an electric current. Ion orbits vary with applied voltage and proton mass ratio of the ions, so that ion species may be identified. Current flow provides an indication of quantity of ions striking the collector.

Effects of acceleration rate on Rayleigh-Taylor instability in elastic-plastic materials

NASA Astrophysics Data System (ADS)

Banerjee, Arindam; Polavarapu, Rinosh

2016-11-01

The effect of acceleration rate in the elastic-plastic transition stage of Rayleigh-Taylor instability in an accelerated non-Newtonian material is investigated experimentally using a rotating wheel experiment. A non-Newtonian material (mayonnaise) was accelerated at different rates by varying the angular acceleration of a rotating wheel and growth patterns of single mode perturbations with different combinations of amplitude and wavelength were analyzed. Experiments were run at two different acceleration rates to compare with experiments presented in prior years at APS DFD meetings and the peak amplitude responses are captured using a high-speed camera. Similar to the instability acceleration, the elastic-plastic transition acceleration is found to be increasing with increase in acceleration rate for a given amplitude and wavelength. The experimental results will be compared to various analytical strength models and prior experimental studies using Newtonian fluids. Authors acknowledge funding support from Los Alamos National Lab subcontract(370333) and DOE-SSAA Grant (DE-NA0001975).

Numerical simulation of mechanical compaction of deepwater shallow sediments

NASA Astrophysics Data System (ADS)

Sun, Jin; Wu, Shiguo; Deng, Jingen; Lin, Hai; Zhang, Hanyu; Wang, Jiliang; Gao, Jinwei

2018-02-01

To study the compaction law and overpressure evolution in deepwater shallow sediments, a large-strain compaction model that considers material nonlinearity and moving boundary is formulated. The model considers the dependence of permeability and material properties on void ratio. The modified Cam-Clay model is selected as the constitutive relations of the sediments, and the deactivation/reactivation method is used to capture the moving top surface during the deposition process. A one-dimensional model is used to study the compaction law of the shallow sediments. Results show that the settlement of the shallow sediments is large under their own weight during compaction. The void ratio decreases strictly with burial depth and decreases more quickly near the seafloor than in the deeper layers. The generation of abnormal pressure in the shallow flow sands is closely related to the compaction law of shallow sediments. The two main factors that affect the generation of overpressure in the sands are deposition rate and permeability of overlying clay sediments. Overpressure increases with an increase in deposition rate and a decrease in the permeability of the overlying clay sediment. Moreover, an upper limit for the overpressure exists. A two-dimensional model is used to study the differential compaction of the shallow sediments. The pore pressure will still increase due to the inflow of the pore fluid from the neighboring clay sediment even though the deposition process is interrupted.

[Studies on sintering of dental porcelain. (Part 1) Binary system sintering of alumina and low fusing frit (author's transl)].

PubMed

Kuwayama, N; Kon, M

1981-04-01

Dental porcelains were made from frit and glass powder with electro fused alumina powder addition in the range from 20 to 60 wt% using sintering method at the temperature from 500 degree C to 1 000 degree C, and the effects of alumina content and firing temperature on firing processes of sintered composite were investigated. Shrinkage curves of the powder compacts varied with kind of frit and content of alumina. Particulary, powder compact with alumina addition in the range from 50 to 55% was found to have a remarkable influence for extention of firing temperature range. The densification of the powder compacts was considered to be accelerated by the dissolution of a small a mount of alumina particle into the frit and glass above 900 degree C. Expansion coefficient value of sintered composite of alumina and Pyrex glass powder gradually increased with increase of alumina content. Inversely, expansion coefficient of soda-lime-silica glass showed the minimum value at 40 wt% alumina content and then had a tendency of slight increases with increase of alumina content.

Characterization by X-ray tomography of granulated alumina powder during in situ die compaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cottrino, Sandrine; Jorand, Yves, E-mail: yves.jorand@insa-lyon.fr; Maire, Eric

2013-07-15

Compaction process, the aim of which being to obtain green bodies with low porosity and small size, is often used before sintering treatment. Prior to die filling, the ceramic powder is generally granulated to improve flowability. However during compaction, density heterogeneity and critical size defects may appear due to intergranule and granule-die wall frictions. In this work, the influence of granule formulation on the compact morphology has been studied. To do so, a compaction setup was installed inside an X-ray tomography equipment so that the evolution of the compact morphology could be analysed during the whole compaction process. We havemore » demonstrated that high humidity rate and the addition of binder in the granule formulation increase density heterogeneity and generate larger defects. - Highlights: • An original compaction set up was installed inside an X-Ray tomography equipment. • The compaction process of granulated ceramic powder is imaged. • The compact green microstructure is quantified and related to the compaction stages. • The most detrimental defects of dry-pressed parts are caused by hollow granules. • Formulations without binder allow a reduction of the number of large defects.« less

Saclay Compact Accelerator-driven Neutron Sources (SCANS)

NASA Astrophysics Data System (ADS)

Marchix, A.; Letourneau, A.; Tran, HN; Chauvin, N.; Menelle, A.; Ott, F.; Schwindling, J.

2018-06-01

For next decade, the European neutron scattering community will face of important changes, as many facilities will close, strictly fission-based sources. This statement mainly concerns France with the planned closure of Orphee and ILL. At CEA-Saclay, the project SONATE has been launched in order to provide a high intensity neutron source in Saclay site, this project is based on Compact Accelerator-driven Neutron Sources technology coupled to high-intensity beams. The goal of SONATE is to develop a 50 kW target, aiming to produce at least a neutron yield of 1013 s-1 in pulse mode with a peak current of 100 mA. We have investigated in this document the best combinations of beam/target which would lead to this substantial neutron yields. Further investigations and tests have to be carry out, especially due to sparse data on thick target and such low-energy beams considered in this document. An intermediate step to the SONATE project is under test and development, called IPHI-NEUTRON, which would lead to provide a small-size neutron facility mainly devoted to neutron imagery for industry. This step is based on the existing 3 MeV proton beam, named IPHI. Best target candidates are Lithium and Beryllium, leading respectively to a neutron yield of about 2.1013 s-1 and 4.1012 s-1.

A 1kW EUV source for lithography based on FEL emission in a compact storage ring

NASA Astrophysics Data System (ADS)

Feser, Michael; Ruth, Ron; Loewen, Rod

2017-10-01

EUV has long been hailed as the next generation lithography technology. Its adoption into high volume manufacturing (HVM), however, has been delayed several technology nodes due to technical issues, many of which can be attributed to the EUV source performance. Today's EUV lithography scanners are powered by laser produce plasma (LPP) sources. They have issues with power scaling beyond 300 W, reliability and contamination. Free Electron Lasers (FELs) have been considered as an alternative EUV source. Advantages of accelerator based sources are the maturity of the accelerator technology, lack of debris/contamination, and ability to provide high power. Industry turned away from this technology because of the requirement to feed up to 10 scanners from one linear FEL to make it economically feasible, the large footprint, and generation of radioactive byproducts. All of these issues are overcome in the presented concept using a compact storage ring with steady-state FEL lasing action. At 1 kW output power, comparable cost and footprint to an LPP source, this source is ideally suited for use on a single scanner and promises reliable, contamination free operation. FEL action in the storage ring is sustained by operating the FEL well below the saturation regime and preserving the equilibrium low emittance and energy distribution of the ring.

Implementation and Optimization of miniGMG - a Compact Geometric Multigrid Benchmark

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Samuel; Kalamkar, Dhiraj; Singh, Amik

2012-12-01

Multigrid methods are widely used to accelerate the convergence of iterative solvers for linear systems used in a number of different application areas. In this report, we describe miniGMG, our compact geometric multigrid benchmark designed to proxy the multigrid solves found in AMR applications. We explore optimization techniques for geometric multigrid on existing and emerging multicore systems including the Opteron-based Cray XE6, Intel Sandy Bridge and Nehalem-based Infiniband clusters, as well as manycore-based architectures including NVIDIA's Fermi and Kepler GPUs and Intel's Knights Corner (KNC) co-processor. This report examines a variety of novel techniques including communication-aggregation, threaded wavefront-based DRAM communication-avoiding,more » dynamic threading decisions, SIMDization, and fusion of operators. We quantify performance through each phase of the V-cycle for both single-node and distributed-memory experiments and provide detailed analysis for each class of optimization. Results show our optimizations yield significant speedups across a variety of subdomain sizes while simultaneously demonstrating the potential of multi- and manycore processors to dramatically accelerate single-node performance. However, our analysis also indicates that improvements in networks and communication will be essential to reap the potential of manycore processors in large-scale multigrid calculations.« less

Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

PubMed Central

Yang, X.; Brunetti, E.; Gil, D. Reboredo; Welsh, G. H.; Li, F. Y.; Cipiccia, S.; Ersfeld, B.; Grant, D. W.; Grant, P. A.; Islam, M. R.; Tooley, M. P.; Vieux, G.; Wiggins, S. M.; Sheng, Z. M.; Jaroszynski, D. A.

2017-01-01

Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5–10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°–60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators. PMID:28281679

What We Don't Understand About Ion Acceleration Flares

NASA Technical Reports Server (NTRS)

Reames, Donald V.; Ng, C. K.; Tylka, A. J.

1999-01-01

There are now strong associations between the (3)He-rich, Fe-rich ions in "impulsive" solar energetic particle (SEP) events and the similar abundances derived from gamma-ray lines from flares. Compact flares, where wave energy can predominate, are ideal sites for the study of wave-particle physics. Yet there are nagging questions about the magnetic geometry, the relation between ions that escape and those that interact, and the relative roles of cascading Alfven waves and the EMIC waves required to enhance He-3. There are also questions about the relative timing of ion and electron acceleration and of heating; these relate to the variation of ionization states before and during acceleration and during transport out of the corona. We can construct a model that addresses many of these issues, but problems do remain. Our greatest lack is realistic theoretical simulations of element abundances, spectra, and their variations. By contrast, we now have a much better idea of the acceleration at CME-driven shock waves in the rare but large "gradual" SEP events, largely because of their slow temporal evolution and great spatial extent.

Design Challenges of a Rapid Cycling Synchrotron for Carbon/Proton Therapy

NASA Astrophysics Data System (ADS)

Cook, Nathan

2012-03-01

The growing interest in radiation therapy with protons and light ions has driven demand for new methods of ion acceleration and the delivery of ion beams. One exciting new platform for ion beam acceleration and delivery is the rapid cycling synchrotron. Operating at 15Hz, rapid cycling achieves faster treatment times by making beam extraction possible at any energy during the cycle. Moreover, risk to the patient is reduced by requiring fewer particles in the beam line at a given time, thus eliminating the need for passive filtering and reducing the consequences of a malfunction. Lastly, the ability to switch between carbon ion and proton beam therapy provides the machine with an unmatched flexibility. However, these features do stipulate challenges in accelerator design. Maintaining a compact lattice requires careful tuning of lattice functions, tight focusing combined function magnets, and fast injection and extraction systems. Providing the necessary acceleration over a short cycle time also necessitates a five-fold frequency swing for carbon ions, further burdening the design requirements of ferrite-driven radiofrequency cavities. We will consider these challenges as well as some solutions selected for our current design.

Relativistically strong electromagnetic radiation in a plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bulanov, S. V., E-mail: svbulanov@gmail.com, E-mail: bulanov.sergei@jaea.go.jp; Esirkepov, T. Zh.; Kando, M.

Physical processes in a plasma under the action of relativistically strong electromagnetic waves generated by high-power lasers have been briefly reviewed. These processes are of interest in view of the development of new methods for acceleration of charged particles, creation of sources of bright hard electromagnetic radiation, and investigation of macroscopic quantum-electrodynamical processes. Attention is focused on nonlinear waves in a laser plasma for the creation of compact electron accelerators. The acceleration of plasma bunches by the radiation pressure of light is the most efficient regime of ion acceleration. Coherent hard electromagnetic radiation in the relativistic plasma is generated inmore » the form of higher harmonics and/or electromagnetic pulses, which are compressed and intensified after reflection from relativistic mirrors created by nonlinear waves. In the limit of extremely strong electromagnetic waves, radiation friction, which accompanies the conversion of radiation from the optical range to the gamma range, fundamentally changes the behavior of the plasma. This process is accompanied by the production of electron–positron pairs, which is described within quantum electrodynamics theory.« less

On-shot characterization of single plasma mirror temporal contrast improvement

NASA Astrophysics Data System (ADS)

Obst, L.; Metzkes-Ng, J.; Bock, S.; Cochran, G. E.; Cowan, T. E.; Oksenhendler, T.; Poole, P. L.; Prencipe, I.; Rehwald, M.; Rödel, C.; Schlenvoigt, H.-P.; Schramm, U.; Schumacher, D. W.; Ziegler, T.; Zeil, K.

2018-05-01

We report on the setup and commissioning of a compact recollimating single plasma mirror (PM) for temporal contrast enhancement at the Draco 150 TW laser during laser-proton acceleration experiments. The temporal contrast with and without PM is characterized single-shot by means of self-referenced spectral interferometry with extended time excursion at unprecedented dynamic and temporal range. This allows for the first single-shot measurement of the PM trigger point, which is interesting for the quantitative investigation of the complex pre-plasma formation process at the surface of the target used for proton acceleration. As a demonstration of high contrast laser plasma interaction we present proton acceleration results with ultra-thin liquid crystal targets of ∼ 1 μm down to 10 nm thickness. Focus scans of different target thicknesses show that highest proton energies are reached for the thinnest targets at best focus. This indicates that the contrast enhancement is effective such that the acceleration process is not limited by target pre-expansion induced by laser light preceding the main laser pulse.

Doing More with Less: Cost-effective, Compact Particle Accelerators (489th Brookhaven Lecture)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trbojevic, Dejan

2013-10-22

Replace a 135-ton magnet used for cancer-fighting particle therapies with a magnet that weighs only two tons? Such a swap is becoming possible thanks to new particle accelerator advances being developed by researchers at Brookhaven Lab. With an approach that combines techniques used by synchrotron accelerators with the ability to accept more energy, these new technologies could be used for more than fighting cancer. They could also decrease the lifecycle of byproducts from nuclear power plants and reduce costs for eRHIC—a proposed electron-ion collider for Brookhaven Lab that researchers from around the world would use to explore the glue thatmore » holds together the universe’s most basic building blocks and explore the proton-spin puzzle. During this lecture, Dr. Trbojevic provides an overview of accelerator technologies and techniques—particularly a non-scaling, fixed-focused alternating gradient—to focus particle beams using fewer, smaller magnets. He discusses how these technologies will benefit eRHIC and other applications, including particle therapies being developed to combat cancer.« less

Current Sheets in Pulsar Magnetospheres and Winds: Particle Acceleration and Pulsed Gamma Ray Emission

NASA Astrophysics Data System (ADS)

Arons, Jonathan

The research proposed addresses understanding of the origin of non-thermal energy in the Universe, a subject beginning with the discovery of Cosmic Rays and continues, including the study of relativistic compact objects - neutron stars and black holes. Observed Rotation Powered Pulsars (RPPs) have rotational energy loss implying they have TeraGauss magnetic fields and electric potentials as large as 40 PetaVolts. The rotational energy lost is reprocessed into particles which manifest themselves in high energy gamma ray photon emission (GeV to TeV). Observations of pulsars from the FERMI Gamma Ray Observatory, launched into orbit in 2008, have revealed 130 of these stars (and still counting), thus demonstrating the presence of efficient cosmic accelerators within the strongly magnetized regions surrounding the rotating neutron stars. Understanding the physics of these and other Cosmic Accelerators is a major goal of astrophysical research. A new model for particle acceleration in the current sheets separating the closed and open field line regions of pulsars' magnetospheres, and separating regions of opposite magnetization in the relativistic winds emerging from those magnetopsheres, will be developed. The currents established in recent global models of the magnetosphere will be used as input to a magnetic field aligned acceleration model that takes account of the current carrying particles' inertia, generalizing models of the terrestrial aurora to the relativistic regime. The results will be applied to the spectacular new results from the FERMI gamma ray observatory on gamma ray pulsars, to probe the physics of the generation of the relativistic wind that carries rotational energy away from the compact stars, illuminating the whole problem of how compact objects can energize their surroundings. The work to be performed if this proposal is funded involves extending and developing concepts from plasma physics on dissipation of magnetic energy in thin sheets of electric current that separate regions of differing magnetization into the domain of highly relativistic magnetic fields - those with energy density large compared to the rest mass energy of the charged particles - the plasma - caught in that field. The investigators will create theoretical and computational models of the magnetic dissipation - a form of viscous flow in the thin sheets of electric current that form in the magnetized regions around the rotating stars - using Particle in-Cell plasma simulations. These simulations use a large computer to solve the equations of motion of many charged particles - millions to billions in the research that will be pursued - to unravel the dissipation of those fields and the acceleration of beams of particles in the thin sheets. The results will be incorporated into macroscopic MHD models of the magnetic structures around the stars which determine the location and strength of the current sheets, so as to model and analyze the pulsed gamma ray emission seen from hundreds of Rotation Powered Pulsars. The computational models will be assisted by ``pencil and paper'' theoretical modeling designed to motivate and interpret the computer simulations, and connect them to the observations.

Temperature effect on mechanical and tribological characterization of Mg-SiC nanocomposite fabricated by high rate compaction

NASA Astrophysics Data System (ADS)

Majzoobi, G. H.; Rahmani, K.; Atrian, A.

2018-01-01

In this paper, dynamic compaction is employed to produce Mg-SiC nanocomposite samples using a mechanical drop hammer. Different volume fractions of SiC nano reinforcement and magnesium (Mg) micron-size powder as the matrix are mechanically milled and consolidated at different temperatures. It is found that with the increase of temperature the sintering requirements is satisfied and higher quality samples are fabricated. The density, hardness, compressive strength and the wear resistance of the compacted specimens are characterized in this work. It was found that by increasing the content of nano reinforcement, the relative density of the compacted samples decreases, whereas, the micro-hardness and the strength of the samples enhance. Furthermore, higher densification temperatures lead to density increase and hardness reduction. Additionally, it is found that the wear rate of the nanocomposite is increased remarkably by increasing the SiC nano reinforcement.

Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

NASA Astrophysics Data System (ADS)

Cha, Sungsu; Kim, Yujong; Lee, Byung Cheol; Park, Hyung Dal; Lee, Seung Hyun; Buaphad, Pikad

2017-05-01

KAERI is developing a 6 MeV X-band radio frequency (RF) electron linear accelerator for medical purposes. The proposed X-band accelerator consists of an e-gun, an accelerating structure, two solenoid magnets, two steering magnets, a magnetron, a modulator, and an automatic frequency control (AFC) system. The accelerating structure of the component consists of oxygen-free high-conductivity copper (OFHC). Therefore, the ambient temperature changes the volume, and the resonance frequency of the accelerating structure also changes. If the RF frequency of a 9300 MHz magnetron and the resonance frequency of the accelerating structure do not match, it can degrade the performance. That is, it will decrease the output power, lower the beam current, decrease the X-ray dose rate, increase the reflection power, and result in unstable operation of the accelerator. Accelerator operation should be possible at any time during all four seasons. To prevent humans from being exposed to radiation when it is operated, the accelerator should also be operable through remote monitoring and remote control. Therefore, the AFC system is designed to meet these requirements; it is configured based on the concept of a phase-locked loop (PLL) model, which includes an RF section, an intermediate frequency (IF) [1-3] section, and a local oscillator (LO) section. Some resonance frequency controllers use a DC motor, chain, and potentiometer to store the position and tune the frequency [4,5]. Our AFC system uses a step motor to tune the RF frequency of the magnetron. The maximum tuning turn number of our magnetron frequency tuning shaft is ten. Since the RF frequency of our magnetron is 9300±25 MHz, it gives 5 MHz (∵±25 MHz/10 turns → 50 MHz/10 turns =5 MHz/turn) frequency tuning per turn. The rotation angle of our step motor is 0.72° per step and the total step number per one rotation is 360°/0.72°=500 steps. Therefore, the tuning range per step is 10 kHz/step (=5 MHz per turn/500 steps per turn). The developed system is a more compact new resonance frequency control system. In addition, a frequency measuring part is included and it can measure the real-time resonance frequency from the magnetron. We have succeeded in the stable provisioning of RF power by recording the results of a 0.01% frequency deviation in the AFC during an RF test. Accordingly, in this paper, the detailed design, fabrication, and a high power test of the AFC system for the X-band linac are presented.

Evaluation of beam wobbling methods for heavy-ion radiotherapy.

PubMed

Yonai, Shunsuke; Kanematsu, Nobuyuki; Komori, Masataka; Kanai, Tatsuaki; Takei, Yuka; Takahashi, Osamu; Isobe, Yoshiharu; Tashiro, Mutsumi; Koikegami, Hajime; Tomita, Hideki

2008-03-01

The National Institute of Radiological Sciences (NIRS) has extensively studied carbon-ion radiotherapy at the Heavy-Ion Medical Accelerator in Chiba (HIMAC) with some positive outcomes, and has established its efficacy. Therefore, efforts to distribute the therapy to the general public should be made, for which it is essential to enable direct application of clinical and technological experiences obtained at NIRS. For widespread use, it is very important to reduce the cost through facility downsizing with minimal acceleration energy to deliver the HIMAC-equivalent clinical beams. For the beam delivery system, the requirement of miniaturization is translated to reduction in length while maintaining the clinically available field size and penetration range for range-modulated uniform broad beams of regular fields that are either circular or square for simplicity. In this paper, we evaluate the various wobbling methods including original improvements, especially for application to the compact facilities through the experimental and computational studies. The single-ring wobbling method used at HIMAC is the best one including a lot of experience at HIMAC but the residual range is a fatal problem in the case of a compact facility. On the other hand, uniform wobbling methods such as the spiral and zigzag wobbling methods are effective and suitable for a compact facility. Furthermore, these methods can be applied for treatment with passive range modulation including respiratory gated irradiation. In theory, the choice between the spiral and zigzag wobbling methods depends on the shape of the required irradiation field. However, we found that it is better to use the zigzag wobbling method with transformation of the wobbling pattern even when a circular uniform irradiation field is required, because it is difficult to maintain the stability of the wobbler magnet due to the rapid change of the wobbler current in the spiral wobbling method. The regulated wobbling method, which is our improvement, can well expand the uniform irradiation field and lead to reducing the power requirement of the wobbler magnets. Our evaluations showed that the regulated zigzag wobbling method is the most suitable method for use in currently designed compact carbon-therapy facilities.

Robustness of waves with a high phase velocity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tajima, T., E-mail: ttajima@uci.edu; Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, CA 92688; Necas, A., E-mail: anecas@trialphaenergy.com

Norman Rostoker pioneered research of (1) plasma-driven accelerators and (2) beam-driven fusion reactors. The collective acceleration, coined by Veksler, advocates to drive above-ionization plasma waves by an electron beam to accelerate ions. The research on this, among others, by the Rostoker group incubated the idea that eventually led to the birth of the laser wakefield acceleration (LWFA), by which a large and robust accelerating collective fields may be generated in plasma in which plasma remains robust and undisrupted. Besides the emergence of LWFA, the Rostoker research spawned our lessons learned on the importance of adiabatic acceleration of ions in collectivemore » accelerators, including the recent rebirth in laser-driven ion acceleration efforts in a smooth adiabatic fashion by a variety of ingenious methods. Following Rostoker’s research in (2), the beam-driven Field Reversed Configuration (FRC) has accomplished breakthroughs in recent years. The beam-driven kinetic plasma instabilities have been found to drive the reactivity of deuteron-deuteron fusion beyond the thermonuclear yield in C-2U plasma that Rostoker started. This remarkable result in FRCs as well as the above mentioned LWFA may be understood with the aid of the newly introduced idea of the “robustness hypothesis of waves with a high phase velocity”. It posits that when the wave driven by a particle beam (or laser pulse) has a high phase velocity, its amplitude is high without disrupting the supporting bulk plasma. This hypothesis may guide us into more robust and efficient fusion reactors and more compact accelerators.« less

Dynamic imperfections and optimized feedback design in the Compact Linear Collider main linac

NASA Astrophysics Data System (ADS)

Eliasson, Peder

2008-05-01

The Compact Linear Collider (CLIC) main linac is sensitive to dynamic imperfections such as element jitter, injected beam jitter, and ground motion. These effects cause emittance growth that, in case of ground motion, has to be counteracted by a trajectory feedback system. The feedback system itself will, due to jitter effects and imperfect beam position monitors (BPMs), indirectly cause emittance growth. Fast and accurate simulations of both the direct and indirect effects are desirable, but due to the many elements of the CLIC main linac, simulations may become very time consuming. In this paper, an efficient way of simulating linear (or nearly linear) dynamic effects is described. The method is also shown to facilitate the analytic determination of emittance growth caused by the different dynamic imperfections while using a trajectory feedback system. Emittance growth expressions are derived for quadrupole, accelerating structure, and beam jitter, for ground motion, and for noise in the feedback BPMs. Finally, it is shown how the method can be used to design a feedback system that is optimized for the optics of the machine and the ground motion spectrum of the particular site. This feedback system gives an emittance growth rate that is approximately 10 times lower than that of traditional trajectory feedbacks. The robustness of the optimized feedback system is studied for a number of additional imperfections, e.g., dipole corrector imperfections and faulty knowledge about the machine optics, with promising results.

FEL system with homogeneous average output

DOEpatents

Douglas, David R.; Legg, Robert; Whitney, R. Roy; Neil, George; Powers, Thomas Joseph

2018-01-16

A method of varying the output of a free electron laser (FEL) on very short time scales to produce a slightly broader, but smooth, time-averaged wavelength spectrum. The method includes injecting into an accelerator a sequence of bunch trains at phase offsets from crest. Accelerating the particles to full energy to result in distinct and independently controlled, by the choice of phase offset, phase-energy correlations or chirps on each bunch train. The earlier trains will be more strongly chirped, the later trains less chirped. For an energy recovered linac (ERL), the beam may be recirculated using a transport system with linear and nonlinear momentum compactions M.sub.56, which are selected to compress all three bunch trains at the FEL with higher order terms managed.

Development of C⁶⁺ laser ion source and RFQ linac for carbon ion radiotherapy.

PubMed

Sako, T; Yamaguchi, A; Sato, K; Goto, A; Iwai, T; Nayuki, T; Nemoto, K; Kayama, T; Takeuchi, T

2016-02-01

A prototype C(6+) injector using a laser ion source has been developed for a compact synchrotron dedicated to carbon ion radiotherapy. The injector consists of a laser ion source and a 4-vane radio-frequency quadrupole (RFQ) linac. Ion beams are extracted from plasma and directly injected into the RFQ. A solenoid guides the low-energy beams into the RFQ. The RFQ is designed to accelerate high-intensity pulsed beams. A structure of monolithic vanes and cavities is adopted to reduce its power consumption. In beam acceleration tests, a solenoidal magnetic field set between the laser ion source and the RFQ helped increase both the peak currents before and after the RFQ by a factor of 4.

Development of C6+ laser ion source and RFQ linac for carbon ion radiotherapy

NASA Astrophysics Data System (ADS)

Sako, T.; Yamaguchi, A.; Sato, K.; Goto, A.; Iwai, T.; Nayuki, T.; Nemoto, K.; Kayama, T.; Takeuchi, T.

2016-02-01

A prototype C6+ injector using a laser ion source has been developed for a compact synchrotron dedicated to carbon ion radiotherapy. The injector consists of a laser ion source and a 4-vane radio-frequency quadrupole (RFQ) linac. Ion beams are extracted from plasma and directly injected into the RFQ. A solenoid guides the low-energy beams into the RFQ. The RFQ is designed to accelerate high-intensity pulsed beams. A structure of monolithic vanes and cavities is adopted to reduce its power consumption. In beam acceleration tests, a solenoidal magnetic field set between the laser ion source and the RFQ helped increase both the peak currents before and after the RFQ by a factor of 4.

Space-Charge Simulation of Integrable Rapid Cycling Synchrotron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eldred, Jeffery; Valishev, Alexander

2017-05-01

Integrable optics is an innovation in particle accelerator design that enables strong nonlinear focusing without generating parametric resonances. We use a Synergia space-charge simulation to investigate the application of integrable optics to a high-intensity hadron ring that could replace the Fermilab Booster. We find that incorporating integrability into the design suppresses the beam halo generated by a mismatched KV beam. Our integrable rapid cycling synchrotron (iRCS) design includes other features of modern ring design such as low momentum compaction factor and harmonically canceling sextupoles. Experimental tests of high-intensity beams in integrable lattices will take place over the next several yearsmore » at the Fermilab Integrable Optics Test Accelerator (IOTA) and the University of Maryland Electron Ring (UMER).« less

GPU-accelerated computational tool for studying the effectiveness of asteroid disruption techniques

NASA Astrophysics Data System (ADS)

Zimmerman, Ben J.; Wie, Bong

2016-10-01

This paper presents the development of a new Graphics Processing Unit (GPU) accelerated computational tool for asteroid disruption techniques. Numerical simulations are completed using the high-order spectral difference (SD) method. Due to the compact nature of the SD method, it is well suited for implementation with the GPU architecture, hence solutions are generated at orders of magnitude faster than the Central Processing Unit (CPU) counterpart. A multiphase model integrated with the SD method is introduced, and several asteroid disruption simulations are conducted, including kinetic-energy impactors, multi-kinetic energy impactor systems, and nuclear options. Results illustrate the benefits of using multi-kinetic energy impactor systems when compared to a single impactor system. In addition, the effectiveness of nuclear options is observed.

A numerical investigation of wind accretion in persistent supergiant X-ray binaries - I. Structure of the flow at the orbital scale

NASA Astrophysics Data System (ADS)

El Mellah, I.; Casse, F.

2017-05-01

Classical supergiant X-ray binaries host a neutron star orbiting a supergiant OB star and display persistent X-ray luminosities of 1035-1037 erg s-1. The stellar wind from the massive companion is believed to be the main source of matter accreted by the compact object. With this first paper, we introduce a ballistic model to evaluate the influence of the orbital effects on the structure of the accelerating winds that participate to the accretion process. Thanks to the parametrization we retained the numerical pipeline we designed, we can investigate the supersonic flow and the subsequent observables as a function of a reduced set of characteristic numbers and scales. We show that the shape of the permanent flow is entirely determined by the mass ratio, the filling factor, the Eddington factor and the α-force multiplier that drives the stellar wind acceleration. Provided scales such as the orbital period are known, we can trace back the observables to evaluate the mass accretion rates, the accretion mechanism, the shearing of the inflow and the stellar parameters. We discuss the likelihood of wind-formed accretion discs around the accretors in each case and confront our model to three persistent supergiant X-ray binaries (Vela X-1, IGR J18027-2016, XTE J1855-026).

High power diode lasers emitting from 639 nm to 690 nm

NASA Astrophysics Data System (ADS)

Bao, L.; Grimshaw, M.; DeVito, M.; Kanskar, M.; Dong, W.; Guan, X.; Zhang, S.; Patterson, J.; Dickerson, P.; Kennedy, K.; Li, S.; Haden, J.; Martinsen, R.

2014-03-01

There is increasing market demand for high power reliable red lasers for display and cinema applications. Due to the fundamental material system limit at this wavelength range, red diode lasers have lower efficiency and are more temperature sensitive, compared to 790-980 nm diode lasers. In terms of reliability, red lasers are also more sensitive to catastrophic optical mirror damage (COMD) due to the higher photon energy. Thus developing higher power-reliable red lasers is very challenging. This paper will present nLIGHT's released red products from 639 nm to 690nm, with established high performance and long-term reliability. These single emitter diode lasers can work as stand-alone singleemitter units or efficiently integrate into our compact, passively-cooled Pearl™ fiber-coupled module architectures for higher output power and improved reliability. In order to further improve power and reliability, new chip optimizations have been focused on improving epitaxial design/growth, chip configuration/processing and optical facet passivation. Initial optimization has demonstrated promising results for 639 nm diode lasers to be reliably rated at 1.5 W and 690nm diode lasers to be reliably rated at 4.0 W. Accelerated life-test has started and further design optimization are underway.

Constructing an Invasion Machine: The Rapid Evolution of a Dispersal-Enhancing Phenotype During the Cane Toad Invasion of Australia.

PubMed

Hudson, C M; McCurry, M R; Lundgren, P; McHenry, C R; Shine, R

Biological invasions can induce rapid evolutionary change. As cane toads (Rhinella marina) have spread across tropical Australia over an 80-year period, their rate of invasion has increased from around 15 to 60 km per annum. Toads at the invasion front disperse much faster and further than conspecifics from range-core areas, and their offspring inherit that rapid dispersal rate. We investigated morphological changes that have accompanied this dramatic acceleration, by conducting three-dimensional morphometric analyses of toads from both range-core and invasion-front populations. Morphology of heads, limbs, pectoral girdles and pelvic girdles differed significantly between toads from the two areas, ranging from 0.5% to 16.5% difference in mean bone dimensions between populations, with invasion-front toads exhibiting wider forelimbs, narrower hindlimbs and more compact skulls. Those changes plausibly reflect an increased reliance on bounding (multiple short hops in quick succession) rather than separate large leaps. Within an 80-year period, invasive cane toads have converted the basic anuran body plan - which evolved for occasional large leaps to evade predators - into a morphotype better-suited to sustained long-distance travel.

78 FR 20355 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-04

... discussion are expected to include: (1) Methods to Reduce the Civil Fingerprint Submission Reject Rate (2) Revised Privacy Act Statement for Applicants/Licensees and Other Civil Submitters of Fingerprints (3...

Modeling of Firn Compaction for Estimating Ice-Sheet Mass Change from Observed Ice-Sheet Elevation Change

NASA Technical Reports Server (NTRS)

Li, Jun; Zwally, H. Jay

2011-01-01

Changes in ice-sheet surface elevation are caused by a combination of ice-dynamic imbalance, ablation, temporal variations in accumulation rate, firn compaction and underlying bedrock motion. Thus, deriving the rate of ice-sheet mass change from measured surface elevation change requires information on the rate of firn compaction and bedrock motion, which do not involve changes in mass, and requires an appropriate firn density to associate with elevation changes induced by recent accumulation rate variability. We use a 25 year record of surface temperature and a parameterization for accumulation change as a function of temperature to drive a firn compaction model. We apply this formulation to ICESat measurements of surface elevation change at three locations on the Greenland ice sheet in order to separate the accumulation-driven changes from the ice-dynamic/ablation-driven changes, and thus to derive the corresponding mass change. Our calculated densities for the accumulation-driven changes range from 410 to 610 kg/cu m, which along with 900 kg/cu m for the dynamic/ablation-driven changes gives average densities ranging from 680 to 790 kg/cu m. We show that using an average (or "effective") density to convert elevation change to mass change is not valid where the accumulation and the dynamic elevation changes are of opposite sign.

Extraordinary Tools for Extraordinary Science: The Impact ofSciDAC on Accelerator Science&Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryne, Robert D.

2006-08-10

Particle accelerators are among the most complex and versatile instruments of scientific exploration. They have enabled remarkable scientific discoveries and important technological advances that span all programs within the DOE Office of Science (DOE/SC). The importance of accelerators to the DOE/SC mission is evident from an examination of the DOE document, ''Facilities for the Future of Science: A Twenty-Year Outlook''. Of the 28 facilities listed, 13 involve accelerators. Thanks to SciDAC, a powerful suite of parallel simulation tools has been developed that represent a paradigm shift in computational accelerator science. Simulations that used to take weeks or more now takemore » hours, and simulations that were once thought impossible are now performed routinely. These codes have been applied to many important projects of DOE/SC including existing facilities (the Tevatron complex, the Relativistic Heavy Ion Collider), facilities under construction (the Large Hadron Collider, the Spallation Neutron Source, the Linac Coherent Light Source), and to future facilities (the International Linear Collider, the Rare Isotope Accelerator). The new codes have also been used to explore innovative approaches to charged particle acceleration. These approaches, based on the extremely intense fields that can be present in lasers and plasmas, may one day provide a path to the outermost reaches of the energy frontier. Furthermore, they could lead to compact, high-gradient accelerators that would have huge consequences for US science and technology, industry, and medicine. In this talk I will describe the new accelerator modeling capabilities developed under SciDAC, the essential role of multi-disciplinary collaboration with applied mathematicians, computer scientists, and other IT experts in developing these capabilities, and provide examples of how the codes have been used to support DOE/SC accelerator projects.« less

Extraordinary tools for extraordinary science: the impact of SciDAC on accelerator science and technology

NASA Astrophysics Data System (ADS)

Ryne, Robert D.

2006-09-01

Particle accelerators are among the most complex and versatile instruments of scientific exploration. They have enabled remarkable scientific discoveries and important technological advances that span all programs within the DOE Office of Science (DOE/SC). The importance of accelerators to the DOE/SC mission is evident from an examination of the DOE document, ''Facilities for the Future of Science: A Twenty-Year Outlook.'' Of the 28 facilities listed, 13 involve accelerators. Thanks to SciDAC, a powerful suite of parallel simulation tools has been developed that represent a paradigm shift in computational accelerator science. Simulations that used to take weeks or more now take hours, and simulations that were once thought impossible are now performed routinely. These codes have been applied to many important projects of DOE/SC including existing facilities (the Tevatron complex, the Relativistic Heavy Ion Collider), facilities under construction (the Large Hadron Collider, the Spallation Neutron Source, the Linac Coherent Light Source), and to future facilities (the International Linear Collider, the Rare Isotope Accelerator). The new codes have also been used to explore innovative approaches to charged particle acceleration. These approaches, based on the extremely intense fields that can be present in lasers and plasmas, may one day provide a path to the outermost reaches of the energy frontier. Furthermore, they could lead to compact, high-gradient accelerators that would have huge consequences for US science and technology, industry, and medicine. In this talk I will describe the new accelerator modeling capabilities developed under SciDAC, the essential role of multi-disciplinary collaboration with applied mathematicians, computer scientists, and other IT experts in developing these capabilities, and provide examples of how the codes have been used to support DOE/SC accelerator projects.

Multi-gigaelectronvolt acceleration of positrons in a self-loaded plasma wakefield.

PubMed

Corde, S; Adli, E; Allen, J M; An, W; Clarke, C I; Clayton, C E; Delahaye, J P; Frederico, J; Gessner, S; Green, S Z; Hogan, M J; Joshi, C; Lipkowitz, N; Litos, M; Lu, W; Marsh, K A; Mori, W B; Schmeltz, M; Vafaei-Najafabadi, N; Walz, D; Yakimenko, V; Yocky, G

2015-08-27

Electrical breakdown sets a limit on the kinetic energy that particles in a conventional radio-frequency accelerator can reach. New accelerator concepts must be developed to achieve higher energies and to make future particle colliders more compact and affordable. The plasma wakefield accelerator (PWFA) embodies one such concept, in which the electric field of a plasma wake excited by a bunch of charged particles (such as electrons) is used to accelerate a trailing bunch of particles. To apply plasma acceleration to electron-positron colliders, it is imperative that both the electrons and their antimatter counterpart, the positrons, are efficiently accelerated at high fields using plasmas. Although substantial progress has recently been reported on high-field, high-efficiency acceleration of electrons in a PWFA powered by an electron bunch, such an electron-driven wake is unsuitable for the acceleration and focusing of a positron bunch. Here we demonstrate a new regime of PWFAs where particles in the front of a single positron bunch transfer their energy to a substantial number of those in the rear of the same bunch by exciting a wakefield in the plasma. In the process, the accelerating field is altered--'self-loaded'--so that about a billion positrons gain five gigaelectronvolts of energy with a narrow energy spread over a distance of just 1.3 metres. They extract about 30 per cent of the wake's energy and form a spectrally distinct bunch with a root-mean-square energy spread as low as 1.8 per cent. This ability to transfer energy efficiently from the front to the rear within a single positron bunch makes the PWFA scheme very attractive as an energy booster to an electron-positron collider.

Enhancement of Loperamide Dissolution Rate by Liquisolid Compact Technique.

PubMed

Venkateswarlu, Kambham; Preethi, Jami Komala; Chandrasekhar, Kothapalli Bonnoth

2016-09-01

Purpose: The aim of present study was to improve the dissolution rate of poorly soluble drug Loperamide (LPM) by liquisolid compact technique. Methods: Liquisolid compacts of LPM were prepared using Propylene glycol (PG) as a solvent, Avicel pH 102 as carrier, Aerosil as coating material and Sodium Starch Glycolate (SSG) as superdisintegrant. Interactions between the drug and excipients were examined by Fourier Transform Infrared (FTIR) spectroscopy. The dissolution studies for LPM liquisolid formulation, marketed product and pure drug were carried out in pH 1.2 HCl buffer as dissolution media. Results: Results confirmed the absence of chemical interactions between the drug and excipients. From the solubility studies, it was observed the LPM was highly soluble in PG thereby it was selected as a solvent. The dissolution efficiency of LPM at 15 min was increased from 9.99 % for pure drug and 54.57% for marketed product to 86.81% for the tablets prepared by liquisolid compact technique. Stability studies showed no significant change in percent cumulative drug release, hardness, disintegration time, friability and drug content for 3 months. Conclusion: Formulation F2 showed significant increase in dissolution rate compared to the marketed product at pH 1.2 where LPM is largely absorbed. Around 90% of the drug was released from F2 in 30 min compared to the marketed product and it might be due to the increased wetting and surface area of the particles. Hence, the liquisolid compact technique appears to be a promising approach for improving the dissolution rate of poorly soluble drug.

COMPACT E+A GALAXIES AS A PROGENITOR OF MASSIVE COMPACT QUIESCENT GALAXIES AT 0.2 < z < 0.8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zahid, H. Jabran; Hochmuth, Nicholas Baeza; Geller, Margaret J.

We search the Sloan Digital Sky Survey and the Baryon Oscillation Sky Survey to identify ∼5500 massive compact quiescent galaxy candidates at 0.2 < z < 0.8. We robustly classify a subsample of 438 E+A galaxies based on their spectral properties and make this catalog publicly available. We examine sizes, stellar population ages, and kinematics of galaxies in the sample and show that the physical properties of compact E+A galaxies suggest that they are a progenitor of massive compact quiescent galaxies. Thus, two classes of objects—compact E+A and compact quiescent galaxies—may be linked by a common formation scenario. The typicalmore » stellar population age of compact E+A galaxies is <1 Gyr. The existence of compact E+A galaxies with young stellar populations at 0.2 < z < 0.8 means that some compact quiescent galaxies first appear at intermediate redshifts. We derive a lower limit for the number density of compact E+A galaxies. Assuming passive evolution, we convert this number density into an appearance rate of new compact quiescent galaxies at 0.2 < z < 0.8. The lower limit number density of compact quiescent galaxies that may appear at z < 0.8 is comparable to the lower limit of the total number density of compact quiescent galaxies at these intermediate redshifts. Thus, a substantial fraction of the z < 0.8 massive compact quiescent galaxy population may descend from compact E+A galaxies at intermediate redshifts.« less

Gas breakthrough and emission through unsaturated compacted clay in landfill final cover

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ng, C.W.W.; Chen, Z.K.; Coo, J.L.

Highlights: • Explore feasibility of unsaturated clay as a gas barrier in landfill cover. • Gas breakthrough pressure increases with clay thickness and degree of saturation. • Gas emission rate decreases with clay thickness and degree of saturation. • A 0.6 m-thick clay layer may be sufficient to meet gas emission rate limit. - Abstract: Determination of gas transport parameters in compacted clay plays a vital role for evaluating the effectiveness of soil barriers. The gas breakthrough pressure has been widely studied for saturated swelling clay buffer commonly used in high-level radioactive waste disposal facility where the generated gas pressuremore » is very high (in the order of MPa). However, compacted clay in landfill cover is usually unsaturated and the generated landfill gas pressure is normally low (typically less than 10 kPa). Furthermore, effects of clay thickness and degree of saturation on gas breakthrough and emission rate in the context of unsaturated landfill cover has not been quantitatively investigated in previous studies. The feasibility of using unsaturated compacted clay as gas barrier in landfill covers is thus worthwhile to be explored over a wide range of landfill gas pressures under various degrees of saturation and clay thicknesses. In this study, to evaluate the effectiveness of unsaturated compacted clay to minimize gas emission, one-dimensional soil column tests were carried out on unsaturated compacted clay to determine gas breakthrough pressures at ultimate limit state (high pressure range) and gas emission rates at serviceability limit state (low pressure range). Various degrees of saturation and thicknesses of unsaturated clay sample were considered. Moreover, numerical simulations were carried out using a coupled gas–water flow finite element program (CODE-BRIGHT) to better understand the experimental results by extending the clay thickness and varying the degree of saturation to a broader range that is typical at different climate conditions. The results of experimental study and numerical simulation reveal that as the degree of saturation and thickness of clay increase, the gas breakthrough pressure increases but the gas emission rate decreases significantly. Under a gas pressure of 10 kPa (the upper bound limit of typical landfill gas pressure), a 0.6 m or thicker compacted clay is able to prevent gas breakthrough at degree of saturation of 60% or above (in humid regions). Furthermore, to meet the limit of gas emission rate set by the Australian guideline, a 0.6 m-thick clay layer may be sufficient even at low degree of saturation (i.e., 10% like in arid regions)« less

GroEL actively stimulates folding of the endogenous substrate protein PepQ.

PubMed

Weaver, Jeremy; Jiang, Mengqiu; Roth, Andrew; Puchalla, Jason; Zhang, Junjie; Rye, Hays S

2017-06-30

Many essential proteins cannot fold without help from chaperonins, like the GroELS system of Escherichia coli. How chaperonins accelerate protein folding remains controversial. Here we test key predictions of both passive and active models of GroELS-stimulated folding, using the endogenous E. coli metalloprotease PepQ. While GroELS increases the folding rate of PepQ by over 15-fold, we demonstrate that slow spontaneous folding of PepQ is not caused by aggregation. Fluorescence measurements suggest that, when folding inside the GroEL-GroES cavity, PepQ populates conformations not observed during spontaneous folding in free solution. Using cryo-electron microscopy, we show that the GroEL C-termini make physical contact with the PepQ folding intermediate and help retain it deep within the GroEL cavity, resulting in reduced compactness of the PepQ monomer. Our findings strongly support an active model of chaperonin-mediated protein folding, where partial unfolding of misfolded intermediates plays a key role.

High power microwave source development

NASA Astrophysics Data System (ADS)

Benford, James N.; Miller, Gabriel; Potter, Seth; Ashby, Steve; Smith, Richard R.

1995-05-01

The requirements of this project have been to: (1) improve and expand the sources available in the facility for testing purposes and (2) perform specific tasks under direction of the Defense Nuclear Agency about the applications of high power microwaves (HPM). In this project the HPM application was power beaming. The requirements of this program were met in the following way: (1) We demonstrated that a compact linear induction accelerator can drive HPM sources at repetition rates in excess of 100 HZ at peak microwave powers of a GW. This was done for the relativistic magnetron. Since the conclusion of this contract such specifications have also been demonstrated for the relativistic klystron under Ballistic Missile Defense Organization funding. (2) We demonstrated an L band relativistic magnetron. This device has been used both on our single pulse machines, CAMEL and CAMEL X, and the repetitive system CLIA. (3) We demonstrated that phase locking of sources together in large numbers is a feasible technology and showed the generation of multigigawatt S-band radiation in an array of relativistic magnetrons.

A Laminar Flow-Based Microfluidic Tesla Pump via Lithography Enabled 3D Printing.

PubMed

Habhab, Mohammed-Baker; Ismail, Tania; Lo, Joe Fujiou

2016-11-23

Tesla turbine and its applications in power generation and fluid flow were demonstrated by Nicholas Tesla in 1913. However, its real-world implementations were limited by the difficulty to maintain laminar flow between rotor disks, transient efficiencies during rotor acceleration, and the lack of other applications that fully utilize the continuous flow outputs. All of the aforementioned limits of Tesla turbines can be addressed by scaling to the microfluidic flow regime. Demonstrated here is a microscale Tesla pump designed and fabricated using a Digital Light Processing (DLP) based 3D printer with 43 µm lateral and 30 µm thickness resolutions. The miniaturized pump is characterized by low Reynolds number of 1000 and a flow rate of up to 12.6 mL/min at 1200 rpm, unloaded. It is capable of driving a mixer network to generate microfluidic gradient. The continuous, laminar flow from Tesla turbines is well-suited to the needs of flow-sensitive microfluidics, where the integrated pump will enable numerous compact lab-on-a-chip applications.

The anti-sigma factor RsrA responds to oxidative stress by reburying its hydrophobic core

PubMed Central

Rajasekar, Karthik V.; Zdanowski, Konrad; Yan, Jun; Hopper, Jonathan T. S.; Francis, Marie-Louise R.; Seepersad, Colin; Sharp, Connor; Pecqueur, Ludovic; Werner, Jörn M.; Robinson, Carol V.; Mohammed, Shabaz; Potts, Jennifer R.; Kleanthous, Colin

2016-01-01

Redox-regulated effector systems that counteract oxidative stress are essential for all forms of life. Here we uncover a new paradigm for sensing oxidative stress centred on the hydrophobic core of a sensor protein. RsrA is an archetypal zinc-binding anti-sigma factor that responds to disulfide stress in the cytoplasm of Actinobacteria. We show that RsrA utilizes its hydrophobic core to bind the sigma factor σR preventing its association with RNA polymerase, and that zinc plays a central role in maintaining this high-affinity complex. Oxidation of RsrA is limited by the rate of zinc release, which weakens the RsrA–σR complex by accelerating its dissociation. The subsequent trigger disulfide, formed between specific combinations of RsrA's three zinc-binding cysteines, precipitates structural collapse to a compact state where all σR-binding residues are sequestered back into its hydrophobic core, releasing σR to activate transcription of anti-oxidant genes. PMID:27432510

Conceptual design study of an improved gas turbine powertrain

NASA Technical Reports Server (NTRS)

Chapman, W. I.

1980-01-01

The conceptual design for an improved gas turbine (IGT) powertrain and vehicle was investigated. Cycle parameters, rotor systems, and component technology were reviewed and a dual rotor gas turbine concept was selected and optimized for best vehicle fuel economy. The engine had a two stage centrifugal compressor with a design pressure ratio of 5.28, two axial turbine stages with advanced high temperature alloy integral wheels, variable power turbine nozzle for turbine temperature and output torque control, catalytic combustor, and annular ceramic recuperator. The engine was rated at 54.81 kW, using water injection on hot days to maintain vehicle acceleration. The estimated vehicle fuel economy was 11.9 km/l in the combined driving cycle, 43 percent over the 1976 compact automobile. The estimated IGT production vehicle selling price was 10 percent over the comparable piston engine vehicle, but the improved fuel economy and reduced maintenance and repair resulted in a 9 percent reduction in life cycle cost.

Development of a Compact Neutron Generator to be Used For Associated Particle Imaging Utilizing a RF-Driven Ion Source

NASA Astrophysics Data System (ADS)

Wu, Ying

2009-11-01

The development of a prototype compact neutron generator for the application of associated particle imaging (API) to be used for explosive and contraband detection will be presented. The API technique makes use of the 3.5 MeV alpha particles that are produced simultaneously with the 14 MeV neutrons in the deuterium-tritium (^2D(^3T,n)^4α) fusion reaction to determine the direction of the neutrons and reduce background noise. This method determines the spatial position of each neutron interaction and requires the neutrons to be generated from a small spot in order to achieve high spatial resolution. In this work an axial type neutron generator was designed and built with a predicted neutron yield of 10^8 n/s for a 50 μA D/T ion beam current accelerated to 80 kV. It was shown that the measured yield for a D/D gas filled generator was 2x10^5n/s, which scales to 2x10^7 n/s if a D/T gas fill is used. The generator utilizes an RF planar spiral antenna at 13.56 MHz to create a highly efficient inductively coupled plasma at the ion source. Experimental results show that beams with an atomic ion fraction of > 80% can be obtained with only 100 watts of RF power in the ion source. A single acceleration gap with a secondary electron suppression electrode is used in the acceleration column, to suppress secondary backscattered electrons produced at the target. Initial measurements of the neutron generator performance including the beam spot size and neutron yield under sealed operation will be discussed, along with suggestions for future improvements.

Opportunities for Electrochemical Capacitors as Energy-Storage Solutions in Present and Future Navy and Marine Corps Missions

DTIC Science & Technology

2009-12-31

system, being used to both harvest energy through regenerative braking and to deliver that energy for quick bursts of acceleration or low-speed...conventional braking . The most visible applications of hybrid-electric systems are for transportation, with examples ranging from compact cars to garbage...EDLCs is particularly effective for regenerative energy capture in hybrid-electric systems, but is also beneficial for addressing power quality issues

Application of Advanced Nuclear Emulsion Technique to Fusion Neutron Diagnostics

NASA Astrophysics Data System (ADS)

Nakayama, Y.; Tomita, H.; Morishima, K.; Yamashita, F.; Hayashi, S.; Cheon, MunSeong; Isobe, M.; Ogawa, K.; Naka, T.; Nakano, T.; Nakamura, M.; Kawarabayashi, J.; Iguchi, T.; Ochiai, K.

In order to measure the 2.5 MeV neutrons produced by DD nuclear fusion reactions, we have developed a compact neutron detector based on nuclear emulsion. After optimization of development conditions, we evaluated the response of the detector to an accelerator-based DD neutron source. The absolute efficiency at an energy of 2.5 MeV was estimated to be (4.1±0.2)×10-6 tracks/neutron.

Catching Collisions in the LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fruguiele, Claudia; Hirschauer, Jim

Now that the Large Hadron Collider has officially turned back on for its second run, within every proton collision could emerge the next new discovery in particle physics. Learn how the detectors on the Compact Muon Solenoid, or CMS, experiment capture and track particles as they are expelled from a collision. Talking us through these collisions are Claudia Fruguiele and Jim Hirschauer of Fermi National Accelerator Laboratory, the largest U.S. institution collaborating on the LHC.

Catching Collisions in the LHC

ScienceCinema

Fruguiele, Claudia; Hirschauer, Jim

2018-01-16

Now that the Large Hadron Collider has officially turned back on for its second run, within every proton collision could emerge the next new discovery in particle physics. Learn how the detectors on the Compact Muon Solenoid, or CMS, experiment capture and track particles as they are expelled from a collision. Talking us through these collisions are Claudia Fruguiele and Jim Hirschauer of Fermi National Accelerator Laboratory, the largest U.S. institution collaborating on the LHC.

Compact, Isolating Elastomeric Suspension for Vehicle Acoustic Vector Sensor

DTIC Science & Technology

2007-09-30

well as underwater acoustics. His Master’s thesis, funded by NUSC, was a study of near-body acoustic signal behavior entitled “Some Characteristics of ...in non-polymer based composites, including cermets . He has formulated a very wide range of materials for an equally wide range of applications, and...with a moving vehicle of an instrument responsive to particle accelerations in the surrounding medium. The overall goal of this project is to develop

Compaction of North-sea chalk by pore-failure and pressure solution in a producing reservoir

NASA Astrophysics Data System (ADS)

Keszthelyi, Daniel; Dysthe, Dag; Jamtveit, Bjorn

2016-02-01

The Ekofisk field, Norwegian North sea,is an example of compacting chalk reservoir with considerable subsequent seafloor subsidence due to petroleum production. Previously, a number of models were created to predict the compaction using different phenomenological approaches. Here we present a different approach, we use a new creep model based on microscopic mechanisms with no fitting parameters to predict strain rate at core scale and at reservoir scale. The model is able to reproduce creep experiments and the magnitude of the observed subsidence making it the first microstructural model which can explain the Ekofisk compaction.

The Heavy Photon Search test detector

DOE PAGES

Battaglieri, M.; Boyarinov, S.; Bueltmann, S.; ...

2014-12-17

The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment's technical feasibility and to confirm that the trigger rates and occupancies are as expected. This paper describes the HPS Test Run apparatus and readout electronics and its performance. In this setting, a heavy photon can be identified as a narrow peak in themore » e⁺e⁻invariant mass spectrum above the trident background or as a narrow invariant mass peak with a decay vertex displaced from the production target, so charged particle tracking and vertexing are needed for its detection. In the HPS Test Run, charged particles are measured with a compact forward silicon microstrip tracker inside a dipole magnet. Electromagnetic showers are detected in a PbW0 4 crystal calorimeter situated behind the magnet, and are used to trigger the experiment and identify electrons and positrons. Both detectors are placed close to the beam line and split top-bottom. This arrangement provides sensitivity to low-mass heavy photons, allows clear passage of the unscattered beam, and avoids the spray of degraded electrons coming from the target. The discrimination between prompt and displaced e⁺e⁻ pairs requires the first layer of silicon sensors be placed only 10 cm downstream of the target. The expected signal is small, and the trident background huge, so the experiment requires very large statistics. In addition, the HPS Test Run utilizes high-rate readout and data acquisition electronics and a fast trigger to exploit the essentially 100% duty cycle of the CEBAF accelerator at JLab.« less

Feasibility of Colliding-beam fast-fission reactor via 238U80++238 U80+ --> 4 FF + 5n + 430 MeV beam with suppressed plutonium and direct conversion of fission fragment (FF) energy into electricity and/or Rocket propellant with high specific impulse

NASA Astrophysics Data System (ADS)

Maglich, Bogdan; Hester, Tim; Calsec Collaboration

2015-10-01

Uranium-uranium colliding beam experiment1, used fully ionized 238U92+ at energy 100GeV --> <-- 100 GeV, has measured total σ = 487 b. Reaction rate of colliding beams is proportional to neutron flux-squared. First functional Auto-Collider3-6, a compact Migma IV, 1 m in diameter, had self-colliding deuterons, D+, of 725 KeV --> <-- 725 KeV, resulting in copious production of T and 3He. U +U Autocollider``EXYDER'' will use strong-focusing magnet7, which would increase reaction rate by 104. 80 times ionized U ions accelerated through 3 MV accelerator, will collide beam 240 MeV --> <-- 240 MeV. Reaction is: 238U80+ +238 U80+ --> 4 FF + 5n + 430 MeV. Using a simple model1 fission σf ~ 100 b. Suppression of Pu by a factor of 106 will be achieved because NO thermal neutron fission can take place; only fast, 1-3 MeV, where σabs is negligible. Direct conversion of 95% of 430 MeV produced is carried by electrically charged FFs which are magnetically funneled for direct conversion of energy of FFs via electrostatic decelerators4,11. 90% of 930 MeV is electrically recoverable. Depending on the assumptions, we project electric _ power density production of 20 to 200 MWe m-3, equivalent to Thermal 1.3 - 13 GWthm-3. If one-half of unburned U is used for propulsion while rest powers system, heavy FF ion mass provides specific impulse Isp = 106 sec., 103 times higher than current rocket engines.

Dissolution of Hydrocarbon Gas Hydrates in Seawater at 1030-m; Effects of Porosity, Structure, and Compositional Variation as Determined by High-Definition Video and SEM Imaging.

NASA Astrophysics Data System (ADS)

Stern, L. A.; Peltzer, E. T.; Durham, W. B.; Kirby, S. H.; Brewer, P. G.; Circone, S.; Rehder, G.

2002-12-01

We compare dissolution rates of pure, porous, compacted, and oil-contaminated sI methane hydrate and sII methane-ethane hydrate to rates measured previously on pure, compacted, sI methane hydrate and sI carbon dioxide hydrate (Rehder et al., Fall AGU 2001). Laboratory-synthesized test specimens were used in both studies, allowing characterization of test materials prior to their transport and exposure to seawater at 1030-meter depth on the Monterey Canyon seafloor, off coastal Moss Landing, CA. Although pressure and temperature (P-T) conditions at this site are within the nominal P-T equilibrium fields of all gas hydrates tested here, the seawater is undersaturated with respect to the hydrate-forming gas species. Hence, samples dissolve with time, at a rate dependent on water current flow. Four samples were deployed in this second experiment: (1) pure, 30% porous methane hydrate; (2) pure, compacted methane hydrate; (3) pure methane hydrate compacted and then contaminated with a low-T mineral oil; and (4) pure, compacted sII methane-ethane hydrate with methane:ethane molar ratio 0.72. Samples were transferred by pressure vessel at 0 ° C and 15 MPa to the seafloor observatory via the MBARI remotely operated vehicle Ventana. Samples were then exposed to the deep ocean environment and monitored by HDTV camera for several hours at the beginning and end of a 25-hour period. Local current speed and direction were also measured throughout the experiment. Those samples that did not undergo complete dissolution after 25 h were successfully recovered to the laboratory for subsequent analysis by scanning electron microscopy (SEM). Previously, video analysis showed dissolution rates corresponding to 4.0 +/- 0.5 mmole CO2/m2 s for compacted CO2 hydrate samples, and 0.37 +/- 0.03 mmole CH4/m2s for compacted methane hydrate samples (Rehder et al, AGU 2001). The ratio of dissolution rates fits a simple diffusive boundary layer model that incorporates relative gas solubilities appropriate to the field site. These calculations assume that dissolution occurred only along the outer (i.e. imaged) surface of the samples. This assumption is now validated by SEM analysis of recovered samples from the second dive, showing little to no internal alteration of compacted material following their partial dissolution. Quantitative comparison of results from the two dives poses challenges due to variations in sample size and orientation. However, both compacted methane hydrate samples from the second dive in fact exhibited comparable behavior to that measured in the previous experiment; the oily sample did not dissolve at a slower rate, as might be expected if a hydrophobic contaminant inhibits seawater contact. Surprisingly, the porous methane hydrate exhibited significantly slower face retreat than its compacted counterparts. The sII methane-ethane hydrate dissolved measurably slower than all other samples, consistent with the solubility properties of its guest components. While these results represent only a first step in emulating the more complex interactions of seawater with naturally occurring hydrate-bearing sediments, such end member studies should aid preliminary modelling investigations of the chemical stability and lifetime of gas hydrates exposed at the seafloor.

Broadband Observations and Modeling of the Shell-Type Supernova Remnant G347.3-0.5

NASA Technical Reports Server (NTRS)

Ellison, Donald C.; Slane, Patrick O.; Gaensler, Bryan M.

2002-01-01

The supernova remnant G347.3-0.5 emits a featureless power law in X-rays, thought to indicate shock acceleration of electrons to high energies. We here produce a broadband spectrum of the bright northwest limb of this source by combining radio observations from the Australia Telescope Compact Array (ATCA), X-ray observations from the Advanced Satellite for Cosmology and Astrophysics (ASCA), and TeV gamma-ray observations from the CANGAROO imaging Cerenkov telescope. We assume that this emission is produced by an electron population generated by diffusive shock acceleration at the remnant forward shock. The nonlinear aspects of the particle acceleration force a connection between the widely different wavelength bands and between the electrons and the unseen ions, presumably accelerated simultaneously with the electrons. This allows us to infer the relativistic proton spectrum and estimate ambient parameters such as the supernova explosion energy, magnetic field, matter density in the emission region, and efficiency of the shock acceleration process. We find convincing evidence that the shock acceleration is efficient, placing greater than 25% of the shock kinetic energy flux into relativistic ions. Despite this high efficiency, the maximum electron and proton energies, while depending somewhat on assumptions for the compression of the magnetic field in the shock, are well below the observed 'knee' at 10(exp 15) eV in the Galactic cosmic-ray spectrum.

First heavy ion beam tests with a superconducting multigap CH cavity

NASA Astrophysics Data System (ADS)

Barth, W.; Aulenbacher, K.; Basten, M.; Busch, M.; Dziuba, F.; Gettmann, V.; Heilmann, M.; Kürzeder, T.; Miski-Oglu, M.; Podlech, H.; Rubin, A.; Schnase, A.; Schwarz, M.; Yaramyshev, S.

2018-02-01

Very compact accelerating-focusing structures, as well as short focusing periods, high accelerating gradients and short drift spaces are strongly required for superconducting (sc) accelerator sections operating at low and medium energies for continuous wave (cw) heavy ion beams. To keep the GSI-super heavy element (SHE) program competitive on a high level and even beyond, a standalone sc cw linac (Helmholtz linear accelerator) in combination with the GSI high charge state injector (HLI), upgraded for cw operation, is envisaged. Recently the first linac section (financed by Helmholtz Institute Mainz (HIM) and GSI) as a demonstration of the capability of 217 MHz multigap crossbar H-mode structures (CH) has been commissioned and extensively tested with heavy ion beam from the HLI. The demonstrator setup reached acceleration of heavy ions up to the design beam energy. The required acceleration gain was achieved with heavy ion beams even above the design mass to charge ratio at high beam intensity and full beam transmission. This paper presents systematic beam measurements with varying rf amplitudes and phases of the CH cavity, as well as phase space measurements for heavy ion beams with different mass to charge ratio. The worldwide first and successful beam test with a superconducting multigap CH cavity is a milestone of the R&D work of HIM and GSI in collaboration with IAP in preparation of the HELIAC project and other cw-ion beam applications.

A mini-photofragment translational spectrometer with ion velocity map imaging using low voltage acceleration

NASA Astrophysics Data System (ADS)

Qi, Wenke; Jiang, Pan; Lin, Dan; Chi, Xiaoping; Cheng, Min; Du, Yikui; Zhu, Qihe

2018-01-01

A mini time-sliced ion velocity map imaging photofragment translational spectrometer using low voltage acceleration has been constructed. The innovation of this apparatus adopts a relative low voltage (30-150 V) to substitute the traditional high voltage (650-4000 V) to accelerate and focus the fragment ions. The overall length of the flight path is merely 12 cm. There are many advantages for this instrument, such as compact structure, less interference, and easy to operate and control. Low voltage acceleration gives a longer turn-around time to the photofragment ions forming a thicker Newton sphere, which provides sufficient time for slicing. Ion trajectory simulation has been performed for determining the structure dimensions and the operating voltages. The photodissociation and multiphoton ionization of O2 at 224.999 nm is used to calibrate the ion images and examine the overall performance of the new spectrometer. The velocity resolution (Δν/ν) of this spectrometer from O2 photodissociation is about 0.8%, which is better than most previous results using high acceleration voltage. For the case of CF3I dissociation at 277.38 nm, many CF3 vibrational states have been resolved, and the anisotropy parameter has been measured. The application of low voltage acceleration has shown its advantages on the ion velocity map imaging (VMI) apparatus. The miniaturization of the VMI instruments can be realized on the premise of high resolution.

The Integration of Climate Science and Collaborative Processes in Building Regional Climate Resiliency in Southeast Florida

NASA Astrophysics Data System (ADS)

Jurado, J.

2016-12-01

Southeast Florida is widely recognized as one of the most vulnerable regions in the United States to the impacts of climate change, especially sea level rise. Dense urban populations, low land elevations, flat topography, complex shorelines and a porous geology all contribute to the region's challenges. Regional and local governments have been working collaboratively to address shared climate mitigation and adaptation concerns as part of the four-county Southeast Florida Regional Climate Change Compact (Compact). This partnership has emphasized, in part, the use of climate data and the development of advanced technical tools and visualizations to help inform decision-making, improve communications, and guide investments. Prominent work products have included regional vulnerability maps and assessments, a unified sea level rise projection for southeast Florida, the development and application of hydrologic models in scenario planning, interdisciplinary resilient redesign planning workshops, and the development of regional climate indicators. Key to the Compact's efforts has been the engagement and expertise of academic and agency partners, including a formal collaboration between the Florida Climate Institute and the Compact to improve research and project collaborations focused on southeast Florida. This presentation will focus on the collaborative processes and work products that have served to accelerate resiliency planning and investments in southeast Florida, with specific examples of how local governments are using these work products to modernize agency processes, and build support among residents and business leaders.

Studies on the S-band bunching system with the Hybrid Bunching-accelerating Structure

NASA Astrophysics Data System (ADS)

Pei, Shi-Lun; Gao, Bin

2018-04-01

Generally, a standard bunching system is composed of a standing-wave (SW) pre-buncher (PB), a traveling-wave (TW) buncher (B) and a standard accelerating structure. In the industrial area, the bunching system is usually simplified by eliminating the PB and integrating the B and the standard accelerating structure together to form a β-varied accelerating structure. The beam capturing efficiency for this kind of simplified system is often worse than that for the standard one. The hybrid buncher (HB) has been proved to be a successful attempt to reduce the cost but preserve the beam quality as much as possible. Here we propose to exclusively simplify the standard bunching system by integrating the PB, the B and the standard accelerating structure together to form a Hybrid Bunching-accelerating Structure (HBaS). Compared to the standard bunching system, the one based on the HBaS is more compact, and the cost is lowered to the largest extent. With almost the same beam transportation efficiency (∼70%) from the electron gun to the linac exit, the peak-to-peak (p-to-p) beam energy spread and the 1 σ emittance of the linac with the HBaS are ∼20% and ∼60% bigger than those of the linac based on the split PB/B/standard accelerating structure system. Nonetheless, the proposed HBaS can be widely applied in the industrial linacs to greatly increase the beam capturing efficiency without fairly increasing the construction cost.

Optimization of batteries for plug-in hybrid electric vehicles

NASA Astrophysics Data System (ADS)

English, Jeffrey Robb

This thesis presents a method to quickly determine the optimal battery for an electric vehicle given a set of vehicle characteristics and desired performance metrics. The model is based on four independent design variables: cell count, cell capacity, state-of-charge window, and battery chemistry. Performance is measured in seven categories: cost, all-electric range, maximum speed, acceleration, battery lifetime, lifetime greenhouse gas emissions, and charging time. The performance of each battery is weighted according to a user-defined objective function to determine its overall fitness. The model is informed by a series of battery tests performed on scaled-down battery samples. Seven battery chemistries were tested for capacity at different discharge rates, maximum output power at different charge levels, and performance in a real-world automotive duty cycle. The results of these tests enable a prediction of the performance of the battery in an automobile. Testing was performed at both room temperature and low temperature to investigate the effects of battery temperature on operation. The testing highlighted differences in behavior between lithium, nickel, and lead based batteries. Battery performance decreased with temperature across all samples with the largest effect on nickel-based chemistries. Output power also decreased with lead acid batteries being the least affected by temperature. Lithium-ion batteries were found to be highly efficient (>95%) under a vehicular duty cycle; nickel and lead batteries have greater losses. Low temperatures hindered battery performance and resulted in accelerated failure in several samples. Lead acid, lead tin, and lithium nickel alloy batteries were unable to complete the low temperature testing regime without losing significant capacity and power capability. This is a concern for their applicability in electric vehicles intended for cold climates which have to maintain battery temperature during long periods of inactivity. Three sample optimizations were performed: a compact car, a, truck, and a sports car. The compact car benefits from increased battery capacity despite the associated higher cost. The truck returned the smallest possible battery of each chemistry, indicating that electrification is not advisable. The sports car optimization resulted in the largest possible battery, indicating large performance from increased electrification. These results mirror the current state of the electric vehicle market.

Collisionless Shocks and Particle Acceleration.

NASA Astrophysics Data System (ADS)

Malkov, M.

2016-12-01

Collisionless shocks emerged in the 50s and 60s of the last century as an important branch of plasma physics and have remained ever since. New applications pose new challenges to our understanding of collisionless shock mechanisms. Particle acceleration in astrophysical settings, primarily studied concerning the putative origin of cosmic rays (CR) in supernova remnant (SNR) shocks, stands out with the collisionless shock mechanism being the key. Among recent laboratory applications, a laser-based tabletop proton accelerator is an affordable compact alternative to big synchrotron accelerators. The much-anticipated proof of cosmic ray (CR) acceleration in supernova remnants is hindered by our limited understanding of collisionless shock mechanisms. Over the last decade, dramatically improved observations were puzzling the theorists with unexpected discoveries. The difference between the helium/carbon and proton CR rigidity (momentum to charge ratio) spectra, seemingly inconsistent with the acceleration and propagation theories, and the perplexing positron excess in the 10-300 GeV range are just two recent examples. The latter is now also actively discussed in the particle physics and CR communities as a possible signature of decay or annihilation of hypothetical dark matter particles. By considering an initial (injection) phase of a diffusive shock acceleration mechanism, including particle reflection off the shock front - where an elemental similarity of particle dynamics does not apply - I will discuss recent suggestions of how to address the new data from the collisionless shock perspective. The backreaction of accelerated particles on the shock structure, its environment, and visibility across the electromagnetic spectrum from radio to gamma rays is another key aspect of collisionless shock that will be discussed.

Commercialization of an S-band standing-wave electron accelerator for industrial applications

NASA Astrophysics Data System (ADS)

Moon, Jin-Hyeok; Kwak, Gyeong-Il; Han, Jae-Ik; Lee, Gyu-Baek; Jeon, Seong-Hwan; Kim, Jae-Young; Hwang, Cheol-Bin; Lee, Gi-Yong; Kim, Young-Man; Park, Sung-Ju

2016-09-01

An electron accelerator system has been developed for use in industrial, as well as possible medical, applications. Based on our experiences achieved during prototype system development and various electron beam acceleration tests, we have built a stable and compact system for sales purposes. We have integrated a self-developed accelerating cavity, an E-gun pulse driver, a radio-frequency (RF) power system, a vacuum system, a cooling system, etc. into a frame with a size of 1800 × 1000 × 1500 mm3. The accelerating structure is a side-coupled standing-wave type operating in the π/2 mode (tuned to~3 GHz). The RF power is provided by using a magnetron driven by a solid-state modulator. The electron gun is a triode type with a dispenser cathode (diameter of 11 mm). The system is capable of delivering a maximum 900-W average electron beam power with tight focusing at the target. Until now, we have performed various electron beam tests and X-ray beam tests after having built the system, have completed the beam assessment for commercializations, and have been preparing full-fledged sales activity. This article reports on our system development processes and on some of our early test results for commercializations.

Laser acceleration of quasi-monoenergetic MeV ion beams.

PubMed

Hegelich, B M; Albright, B J; Cobble, J; Flippo, K; Letzring, S; Paffett, M; Ruhl, H; Schreiber, J; Schulze, R K; Fernández, J C

2006-01-26

Acceleration of particles by intense laser-plasma interactions represents a rapidly evolving field of interest, as highlighted by the recent demonstration of laser-driven relativistic beams of monoenergetic electrons. Ultrahigh-intensity lasers can produce accelerating fields of 10 TV m(-1) (1 TV = 10(12) V), surpassing those in conventional accelerators by six orders of magnitude. Laser-driven ions with energies of several MeV per nucleon have also been produced. Such ion beams exhibit unprecedented characteristics--short pulse lengths, high currents and low transverse emittance--but their exponential energy spectra have almost 100% energy spread. This large energy spread, which is a consequence of the experimental conditions used to date, remains the biggest impediment to the wider use of this technology. Here we report the production of quasi-monoenergetic laser-driven C5+ ions with a vastly reduced energy spread of 17%. The ions have a mean energy of 3 MeV per nucleon (full-width at half-maximum approximately 0.5 MeV per nucleon) and a longitudinal emittance of less than 2 x 10(-6) eV s for pulse durations shorter than 1 ps. Such laser-driven, high-current, quasi-monoenergetic ion sources may enable significant advances in the development of compact MeV ion accelerators, new diagnostics, medical physics, inertial confinement fusion and fast ignition.

Compact, compression-free, displaceable, and resealable vacuum feedthrough with built-in strain relief for sensitive components such as optical fibers.

PubMed

Buchholz, B; Ebert, V

2014-05-01

For the direct fiber coupling of small optical measurement cells, we developed a new compact vacuum feedthrough for glass fibers and other similarly shaped objects that are compact and that offer the possibility of adjusting the fiber in longitudinal and in circular direction. The feedthrough assembly avoids compression or torsion on the fiber and thus protects, e.g., highly frangible fiber materials. In the following, we will present a brief simulation of the tightness requirements for low-pressure and low-concentration water vapor measurements and we will explain an integrated concept for a displaceable and self-adjustable, compression-free, compact, ultra-high vacuum, resealable feedthrough with good strain relief. The feedthrough has been successfully tested in a laboratory test facility and in several extractive airborne tunable diode laser absorption spectroscopy hygrometers. The leakage rate of the feedthrough presented here was tested via a helium leak searcher and was quantified further in an 8-week vacuum measurement campaign. The leakage rate is determined to be 0.41 ± 0.04 × 10(-9) hPa l/s, which--to our knowledge--is the first time a leakage rate for such a feedthrough has been quantified.

Comparative study of active plasma lenses in high-quality electron accelerator transport lines

NASA Astrophysics Data System (ADS)

van Tilborg, J.; Barber, S. K.; Benedetti, C.; Schroeder, C. B.; Isono, F.; Tsai, H.-E.; Geddes, C. G. R.; Leemans, W. P.

2018-05-01

Electrically discharged active plasma lenses (APLs) are actively pursued in compact high-brightness plasma-based accelerators due to their high-gradient, tunable, and radially symmetric focusing properties. In this manuscript, the APL is experimentally compared with a conventional quadrupole triplet, highlighting the favorable reduction in the energy dependence (chromaticity) in the transport line. Through transport simulations, it is explored how the non-uniform radial discharge current distribution leads to beam-integrated emittance degradation and a charge density reduction at focus. However, positioning an aperture at the APL entrance will significantly reduce emittance degradation without additional loss of charge in the high-quality core of the beam. An analytical model is presented that estimates the emittance degradation from a short beam driving a longitudinally varying wakefield in the APL. Optimizing laser plasma accelerator operation is discussed where emittance degradation from the non-uniform discharge current (favoring small beams inside the APL) and wakefield effects (favoring larger beam sizes) is minimized.

Comparative study of active plasma lenses in high-quality electron accelerator transport lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

van Tilborg, J.; Barber, S. K.; Benedetti, C.

Electrically discharged active plasma lenses (APLs) are actively pursued in compact high-brightness plasma-based accelerators due to their high-gradient, tunable, and radially symmetric focusing properties. In this paper, the APL is experimentally compared with a conventional quadrupole triplet, highlighting the favorable reduction in the energy dependence (chromaticity) in the transport line. Through transport simulations, it is explored how the non-uniform radial discharge current distribution leads to beam-integrated emittance degradation and a charge density reduction at focus. However, positioning an aperture at the APL entrance will significantly reduce emittance degradation without additional loss of charge in the high-quality core of the beam.more » An analytical model is presented that estimates the emittance degradation from a short beam driving a longitudinally varying wakefield in the APL. Finally, optimizing laser plasma accelerator operation is discussed where emittance degradation from the non-uniform discharge current (favoring small beams inside the APL) and wakefield effects (favoring larger beam sizes) is minimized.« less

Comparative study of active plasma lenses in high-quality electron accelerator transport lines

DOE PAGES

van Tilborg, J.; Barber, S. K.; Benedetti, C.; ...

2018-03-13

Electrically discharged active plasma lenses (APLs) are actively pursued in compact high-brightness plasma-based accelerators due to their high-gradient, tunable, and radially symmetric focusing properties. In this paper, the APL is experimentally compared with a conventional quadrupole triplet, highlighting the favorable reduction in the energy dependence (chromaticity) in the transport line. Through transport simulations, it is explored how the non-uniform radial discharge current distribution leads to beam-integrated emittance degradation and a charge density reduction at focus. However, positioning an aperture at the APL entrance will significantly reduce emittance degradation without additional loss of charge in the high-quality core of the beam.more » An analytical model is presented that estimates the emittance degradation from a short beam driving a longitudinally varying wakefield in the APL. Finally, optimizing laser plasma accelerator operation is discussed where emittance degradation from the non-uniform discharge current (favoring small beams inside the APL) and wakefield effects (favoring larger beam sizes) is minimized.« less

Direct acceleration of electrons by a CO2 laser in a curved plasma waveguide

PubMed Central

Yi, Longqing; Pukhov, Alexander; Shen, Baifei

2016-01-01

Laser plasma interaction with micro-engineered targets at relativistic intensities has been greatly promoted by recent progress in the high contrast lasers and the manufacture of advanced micro- and nano-structures. This opens new possibilities for the physics of laser-matter interaction. Here we propose a novel approach that leverages the advantages of high-pressure CO2 laser, laser-waveguide interaction, as well as micro-engineered plasma structure to accelerate electrons to peak energy greater than 1 GeV with narrow slice energy spread (~1%) and high overall efficiency. The acceleration gradient is 26 GV/m for a 1.3 TW CO2 laser system. The micro-bunching of a long electron beam leads to the generation of a chain of ultrashort electron bunches with the duration roughly equal to half-laser-cycle. These results open a way for developing a compact and economic electron source for diverse applications. PMID:27320197

Perspectives of boron-neutron capture therapy of malignant brain tumors

NASA Astrophysics Data System (ADS)

Kanygin, V. V.; Kichigin, A. I.; Krivoshapkin, A. L.; Taskaev, S. Yu.

2017-09-01

Boron neutron capture therapy (BNCT) is characterized by a selective effect directly on the cells of malignant tumors. The carried out research showed the perspective of the given kind of therapy concerning malignant tumors of the brain. However, the introduction of BNCT into clinical practice is hampered by the lack of a single protocol for the treatment of patients and the difficulty in using nuclear reactors to produce a neutron beam. This problem can be solved by using a compact accelerator as a source of neutrons, with the possibility of installation in a medical institution. Such a neutron accelerator for BNCT was developed at Budker Institute of Nuclear Physics, Novosibirsk. A neutron beam was obtained on this accelerator, which fully complies with the requirements of BNCT, as confirmed by studies on cell cultures and experiments with laboratory animals. The conducted experiments showed the relative safety of the method with the absence of negative effects on cell cultures and living organisms, and also confirmed the effectiveness of BNCT for malignant brain tumors.

Accelerating image reconstruction in dual-head PET system by GPU and symmetry properties.

PubMed

Chou, Cheng-Ying; Dong, Yun; Hung, Yukai; Kao, Yu-Jiun; Wang, Weichung; Kao, Chien-Min; Chen, Chin-Tu

2012-01-01

Positron emission tomography (PET) is an important imaging modality in both clinical usage and research studies. We have developed a compact high-sensitivity PET system that consisted of two large-area panel PET detector heads, which produce more than 224 million lines of response and thus request dramatic computational demands. In this work, we employed a state-of-the-art graphics processing unit (GPU), NVIDIA Tesla C2070, to yield an efficient reconstruction process. Our approaches ingeniously integrate the distinguished features of the symmetry properties of the imaging system and GPU architectures, including block/warp/thread assignments and effective memory usage, to accelerate the computations for ordered subset expectation maximization (OSEM) image reconstruction. The OSEM reconstruction algorithms were implemented employing both CPU-based and GPU-based codes, and their computational performance was quantitatively analyzed and compared. The results showed that the GPU-accelerated scheme can drastically reduce the reconstruction time and thus can largely expand the applicability of the dual-head PET system.

Physics and Novel Schemes of Laser Radiation Pressure Acceleration for Quasi-monoenergetic Proton Generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Chuan S.; Shao, Xi

2016-06-14

The main objective of our work is to provide theoretical basis and modeling support for the design and experimental setup of compact laser proton accelerator to produce high quality proton beams tunable with energy from 50 to 250 MeV using short pulse sub-petawatt laser. We performed theoretical and computational studies of energy scaling and Raleigh--Taylor instability development in laser radiation pressure acceleration (RPA) and developed novel RPA-based schemes to remedy/suppress instabilities for high-quality quasimonoenergetic proton beam generation as we proposed. During the project period, we published nine peer-reviewed journal papers and made twenty conference presentations including six invited talks onmore » our work. The project supported one graduate student who received his PhD degree in physics in 2013 and supported two post-doctoral associates. We also mentored three high school students and one undergraduate student of physics major by inspiring their interests and having them involved in the project.« less

Multistage Coupling of Laser-Wakefield Accelerators with Curved Plasma Channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, J.; Chen, M.; Wu, W. Y.

Multistage coupling of laser-wakefield accelerators is essential to overcome laser energy depletion for high-energy applications such as TeV level electron-positron colliders. Current staging schemes feed subsequent laser pulses into stages using plasma mirrors, while controlling electron beam focusing with plasma lenses. Here a more compact and efficient scheme is proposed to realize simultaneous coupling of the electron beam and the laser pulse into a second stage. Furthermore, a curved channel with transition segment is used to guide a fresh laser pulse into a subsequent straight channel, while allowing the electrons to propagate in a straight channel. This scheme then benefitsmore » from a shorter coupling distance and continuous guiding of the electrons in plasma, while suppressing transverse beam dispersion. Within moderate laser parameters, particle-in-cell simulations demonstrate that the electron beam from a previous stage can be efficiently injected into a subsequent stage for further acceleration, while maintaining high capture efficiency, stability, and beam quality.« less

Multistage Coupling of Laser-Wakefield Accelerators with Curved Plasma Channel

DOE PAGES

Luo, J.; Chen, M.; Wu, W. Y.; ...

2018-04-10

Multistage coupling of laser-wakefield accelerators is essential to overcome laser energy depletion for high-energy applications such as TeV level electron-positron colliders. Current staging schemes feed subsequent laser pulses into stages using plasma mirrors, while controlling electron beam focusing with plasma lenses. Here a more compact and efficient scheme is proposed to realize simultaneous coupling of the electron beam and the laser pulse into a second stage. Furthermore, a curved channel with transition segment is used to guide a fresh laser pulse into a subsequent straight channel, while allowing the electrons to propagate in a straight channel. This scheme then benefitsmore » from a shorter coupling distance and continuous guiding of the electrons in plasma, while suppressing transverse beam dispersion. Within moderate laser parameters, particle-in-cell simulations demonstrate that the electron beam from a previous stage can be efficiently injected into a subsequent stage for further acceleration, while maintaining high capture efficiency, stability, and beam quality.« less

RF critical field measurement of MgB2 thin films coated on Nb

NASA Astrophysics Data System (ADS)

Tajima, T.; Eremeev, G.; Zou, G.; Dolgashev, V.; Martin, D.; Nantista, C.; Tantawi, S.; Yoneda, C.; Moeckly, B. H.; Campisi, I.

2010-06-01

Niobium (Nb) Superconducting RF (SRF) cavities have been used or will be used for a number of particle accelerators. The fundamental limit of the accelerating gradient has been thought to be around 50 MV/m due to its RF critical magnetic field of around 200 mT. This limit will prevent new projects requiring higher gradient and compact accelerators from considering SRF structures. There is a theory, however, that promises to overcome this limitation by coating thin (less than the penetration depth) superconductors on Nb. We initiated measurements of critical magnetic fields of Nb coated with various thin film superconductors, starting with MgB2 films deposited using reactive evaporation technique, with the goal to apply this coating to SRF cavities. This paper will present first test results of the RF critical magnetic field of a system consisting of a 10 nm B and a 100 nm MgB2 films deposited on a chemically polished 2-inch single grain Nb substrate.

The role of sediment compaction and groundwater withdrawal in local sea-level rise, Sandy Hook, New Jersey, USA

NASA Astrophysics Data System (ADS)

Johnson, Christopher S.; Miller, Kenneth G.; Browning, James V.; Kopp, Robert E.; Khan, Nicole S.; Fan, Ying; Stanford, Scott D.; Horton, Benjamin P.

2018-02-01

The rate of relative sea-level (RSL) rise at Sandy Hook, NJ (4.0 ± 0.5 mm/yr) was higher than The Battery, NY (3.0 ± 0.3 mm/yr) from 1900 to 2012 despite being separated by just 26 km. The difference cannot be explained by differential glacial isostatic adjustment (GIA; 1.4 ± 0.4 and 1.3 ± 0.4 mm/yr RSL rise, respectively) alone. We estimate the contribution of sediment compaction to subsidence at Sandy Hook using high-resolution grain size, percent organic matter, and porosity data from three upper Quaternary (≤13,350 cal yr) cores. The organic matter content (<2%) is too low to contribute to local subsidence. However, numerical modeling of the grain size-depth-age-porosity relationship indicates that compaction of deglacial silts likely reduced the column thickness by 10-20% over the past 13,350 cal yrs. While compaction rates were high immediately after the main silt deposition (13,350-13,150 cal yrs BP), rates decreased exponentially after deposition to an average 20th century rate of 0.16 mm/yr (90% Confidence Interval (C.I.), 0.06-0.32 mm/yr). The remaining ∼0.7 mm/yr (90% C.I. 0.3-1.2 mm/yr) difference in subsidence between Sandy Hook and The Battery is likely due to anthropogenic groundwater withdrawal. Historical data from Fort Hancock wells (2 km to the southeast of the Sandy Hook tide gauge) and previous regional work show that local and regional water extraction lowered the water levels in the aquifers underlying Sandy Hook. We suggest that the modern order of contribution to subsidence (highest to lowest) appears to be GIA, local/regional groundwater extraction, and compaction of thick Quaternary silts.

Focused electron and ion beam systems

DOEpatents

Leung, Ka-Ngo; Reijonen, Jani; Persaud, Arun; Ji, Qing; Jiang, Ximan

2004-07-27

An electron beam system is based on a plasma generator in a plasma ion source with an accelerator column. The electrons are extracted from a plasma cathode in a plasma ion source, e.g. a multicusp plasma ion source. The beam can be scanned in both the x and y directions, and the system can be operated with multiple beamlets. A compact focused ion or electron beam system has a plasma ion source and an all-electrostatic beam acceleration and focusing column. The ion source is a small chamber with the plasma produced by radio-frequency (RF) induction discharge. The RF antenna is wound outside the chamber and connected to an RF supply. Ions or electrons can be extracted from the source. A multi-beam system has several sources of different species and an electron beam source.

Frequency-Domain Streak Camera and Tomography for Ultrafast Imaging of Evolving and Channeled Plasma Accelerator Structures

NASA Astrophysics Data System (ADS)

Li, Zhengyan; Zgadzaj, Rafal; Wang, Xiaoming; Reed, Stephen; Dong, Peng; Downer, Michael C.

2010-11-01

We demonstrate a prototype Frequency Domain Streak Camera (FDSC) that can capture the picosecond time evolution of the plasma accelerator structure in a single shot. In our prototype Frequency-Domain Streak Camera, a probe pulse propagates obliquely to a sub-picosecond pump pulse that creates an evolving nonlinear index "bubble" in fused silica glass, supplementing a conventional Frequency Domain Holographic (FDH) probe-reference pair that co-propagates with the "bubble". Frequency Domain Tomography (FDT) generalizes Frequency-Domain Streak Camera by probing the "bubble" from multiple angles and reconstructing its morphology and evolution using algorithms similar to those used in medical CAT scans. Multiplexing methods (Temporal Multiplexing and Angular Multiplexing) improve data storage and processing capability, demonstrating a compact Frequency Domain Tomography system with a single spectrometer.

Ultrashort megaelectronvolt positron beam generation based on laser-accelerated electrons

NASA Astrophysics Data System (ADS)

Xu, Tongjun; Shen, Baifei; Xu, Jiancai; Li, Shun; Yu, Yong; Li, Jinfeng; Lu, Xiaoming; Wang, Cheng; Wang, Xinliang; Liang, Xiaoyan; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

2016-03-01

Experimental generation of ultrashort MeV positron beams with high intensity and high density using a compact laser-driven setup is reported. A high-density gas jet is employed experimentally to generate MeV electrons with high charge; thus, a charge-neutralized MeV positron beam with high density is obtained during laser-accelerated electrons irradiating high-Z solid targets. It is a novel electron-positron source for the study of laboratory astrophysics. Meanwhile, the MeV positron beam is pulsed with an ultrashort duration of tens of femtoseconds and has a high peak intensity of 7.8 × 1021 s-1, thus allows specific studies of fast kinetics in millimeter-thick materials with a high time resolution and exhibits potential for applications in positron annihilation spectroscopy.

Beam tuning and bunch length measurement in the bunch compression operation at the cERL

NASA Astrophysics Data System (ADS)

Honda, Y.; Shimada, M.; Miyajima, T.; Hotei, T.; Nakamura, N.; Kato, R.; Obina, T.; Takai, R.; Harada, K.; Ueda, A.

2017-12-01

Realization of a short bunch beam by manipulating the longitudinal phase space distribution with a finite longitudinal dispersion following an off-crest acceleration is a widely used technique. The technique was applied in a compact test accelerator of an energy-recovery linac scheme for compressing the bunch length at the return loop. A diagnostic system utilizing coherent transition radiation was developed for the beam tuning and for estimating the bunch length. By scanning the beam parameters, we experimentally found the best condition for the bunch compression. The RMS bunch length of 250 ±50 fs was obtained at a bunch charge of 2 pC. This result confirmed the design and the tuning procedure of the bunch compression operation for the future energy-recovery linac (ERL).

Cyclotron Production of Medical Radioisotopes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avila-Rodriguez, M. A.; Zarate-Morales, A.; Flores-Moreno, A.

2010-08-04

The cyclotron production of radioisotopes for medical applications is gaining increased significance in diagnostic molecular imaging techniques such as PET and SPECT. In this regard, radioisotope production has never been easier or more convenient until de introduction of compact medical cyclotrons in the last few decades, which allowed the use of short-lived radioisotopes in in vivo nuclear medicine studies on a routine basis. This review outlines some general considerations about the production of radioisotopes using charged particle accelerators.

Ion beam lithography system

DOEpatents

Leung, Ka-Ngo

2005-08-02

A maskless plasma-formed ion beam lithography tool provides for patterning of sub-50 nm features on large area flat or curved substrate surfaces. The system is very compact and does not require an accelerator column and electrostatic beam scanning components. The patterns are formed by switching beamlets on or off from a two electrode blanking system with the substrate being scanned mechanically in one dimension. This arrangement can provide a maskless nano-beam lithography tool for economic and high throughput processing.

Probing the cytochrome c' folding landscape.

PubMed

Pletneva, Ekaterina V; Zhao, Ziqing; Kimura, Tetsunari; Petrova, Krastina V; Gray, Harry B; Winkler, Jay R

2007-11-01

The folding kinetics of R. palustris cytochrome c' (cyt c') have been monitored by heme absorption and native Trp72 fluorescence at pH 5. The Trp72 fluorescence burst signal suggests early compaction of the polypeptide ensemble. Analysis of heme transient absorption spectra reveals deviations from two-state behavior, including a prominent slow phase that is accelerated by the prolyl isomerase cyclophilin. A nonnative proline configuration (Pro21) likely interferes with the formation of the helical bundle surrounding the heme.

Compact plasma accelerator

NASA Technical Reports Server (NTRS)

Foster, John E. (Inventor)

2004-01-01

A compact plasma accelerator having components including a cathode electron source, an anodic ionizing gas source, and a magnetic field that is cusped. The components are held by an electrically insulating body having a central axis, a top axial end, and a bottom axial end. The cusped magnetic field is formed by a cylindrical magnet having an axis of rotation that is the same as the axis of rotation of the insulating body, and magnetized with opposite poles at its two axial ends; and an annular magnet coaxially surrounding the cylindrical magnet, magnetized with opposite poles at its two axial ends such that a top axial end has a magnetic polarity that is opposite to the magnetic polarity of a top axial end of the cylindrical magnet. The ionizing gas source is a tubular plenum that has been curved into a substantially annular shape, positioned above the top axial end of the annular magnet such that the plenum is centered in a ring-shaped cusp of the magnetic field generated by the magnets. The plenum has one or more capillary-like orifices spaced around its top such that an ionizing gas supplied through the plenum is sprayed through the one or more orifices. The plenum is electrically conductive and is positively charged relative to the cathode electron source such that the plenum functions as the anode; and the cathode is positioned above and radially outward relative to the plenum.

A compact electron spectrometer for an LWFA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumpkin, A.; Crowell, R.; Li, Y.

2007-01-01

The use of a laser wakefield accelerator (LWFA) beam as a driver for a compact free-electron laser (FEL) has been proposed recently. A project is underway at Argonne National Laboratory (ANL) to operate an LWFA in the bubble regime and to use the quasi-monoenergetic electron beam as a driver for a 3-m-long undulator for generation of sub-ps UV radiation. The Terawatt Ultrafast High Field Facility (TUHFF) in the Chemistry Division provides the 20-TW peak power laser. A compact electron spectrometer whose initial fields of 0.45 T provide energy coverage of 30-200 MeV has been selected to characterize the electron beams.more » The system is based on the Ecole Polytechnique design used for their LWFA and incorporates the 5-cm-long permanent magnet dipole, the LANEX scintillator screen located at the dispersive plane, a Roper Scientific 16-bit MCP-intensified CCD camera, and a Bergoz ICT for complementary charge measurements. Test results on the magnets, the 16-bit camera, and the ICT will be described, and initial electron beam data will be presented as available. Other challenges will also be addressed.« less

mA beam acceleration efforts on 100 MeV H- cyclotron at CIAE

NASA Astrophysics Data System (ADS)

Zhang, Tianjue; An, Shizhong; Lv, Yinlong; Ge, Tao; Jia, Xianlu; Ji, Bin; Yin, Zhiguo; Pan, Gaofeng; Cao, Lei; Guan, Fengping; Yang, Jianjun; Li, Zhenguo; Zhao, Zhenlu; Wu, Longcheng; Zhang, He; Wang, Jingfeng; Zhang, Yiwang; Liu, Jingyuan; Li, Shiqiang; Lu, Xiaotong; Liu, Zhenwei; Li, Yaoqian; Guo, Juanjuan; Cao, Xuelong; Guan, Leilei; Wang, Fei; Wang, Yang; Yang, Guang; Zhang, Suping; Hou, Shigang; Wang, Feng

2017-09-01

Various technologies for high current compact H- cyclotron have been developed at CIAE since 1990s. A 375 μA proton beam was extracted from a 30 MeV compact H- cyclotron CYCIAE-30 at the end of 1994. A central region model cyclotron CYCIAE-CRM was developed for the design verification of a 100 MeV high current compact H- cyclotron CYCIAE-100. It is also a 10 MeV proton machine as a prototype for PET application. A 430 μA beam was achieved in 2009. The first beam was extracted from the CYCIAE-100 cyclotron on July 4, 2014, the operation stability has been improved and beam current has been increased gradually. A 1.1 mA proton beam was measured on the internal target in July 2016. The effort for an increasing of proton beam has continued till now. In this paper, the effort on several aspects for mA beam development will be presented, including the multi-cusp source, buncher, matching from the energy of the injected beam, vertical beam line and central region, beam loading of the RF system and instrumentation for beam diagnostics etc.

Compact Torus Fueling of the STOR-M Tokamak

NASA Astrophysics Data System (ADS)

Xiao, C.; Hirose, A.; Zawalski, W.; White, D.; Raman, R.; Decoste, R.; Gregory, B. C.; Martin, F.

1996-11-01

Tangential injection of accelerated compact torus (CT) has been performed on the STOR-M tokamak (R/a=46/12 cm, B_t<1 T, I_p<= 50 kA, barn_e=(0.5 - 1)×10^13 cm-3) using the University of Saskatchewan Compact Torus Injector (USCTI). The CT parameters are: m~=1 μg, v=120 km/sec, B=0.1 T and n=(2 - 4)×10^15 cm-3. After CT injection, the electron density in tokamak doubles and the poloidal β-value increases. Indications of reduction in the loop voltage and H_α emission level have also been observed. Currently, following efforts are being made: (a) to coat chromium on the electrode surface, (b) to increase the on-line baking temperature, and (c) to reduce the neutral gas load which follows the CT plasma. In addition, numerical calculation of CT motion in a tokamak magnetic field has been carried out. For horizontal injection, the initial CT magnetic dipole direction should be aligned with the CT velocity for deeper penetration. In the case of vertical injection, the CT trajectory is independent of the initial magnetic dipole direction and central penetration is facilitated by off-axis injection.

Microfabricated Ion Beam Drivers for Magnetized Target Fusion

NASA Astrophysics Data System (ADS)

Persaud, Arun; Seidl, Peter; Ji, Qing; Ardanuc, Serhan; Miller, Joseph; Lal, Amit; Schenkel, Thomas

2015-11-01

Efficient, low-cost drivers are important for Magnetized Target Fusion (MTF). Ion beams offer a high degree of control to deliver the required mega joules of driver energy for MTF and they can be matched to several types of magnetized fuel targets, including compact toroids and solid targets. We describe an ion beam driver approach based on the MEQALAC concept (Multiple Electrostatic Quadrupole Array Linear Accelerator) with many beamlets in an array of micro-fabricated channels. The channels consist of a lattice of electrostatic quadrupoles (ESQ) for focusing and of radio-frequency (RF) electrodes for ion acceleration. Simulations with particle-in-cell and beam envelope codes predict >10x higher current densities compared to state-of-the-art ion accelerators. This increase results from dividing the total ion beam current up into many beamlets to control space charge forces. Focusing elements can be biased taking advantage of high breakdown electric fields in sub-mm structures formed using MEMS techniques (Micro-Electro-Mechanical Systems). We will present results on ion beam transport and acceleration in MEMS based beamlets. Acknowledgments: This work is supported by the U.S. DOE under Contract No. DE-AC02-05CH11231.

Underground Nuclear Astrophysics - from LUNA to CASPAR

NASA Astrophysics Data System (ADS)

Strieder, Frank; Caspar Collaboration

2015-04-01

It is in the nature of astrophysics that many of the processes and objects are physically inaccessible. Thus, it is important that those aspects that can be studied in the laboratory are well understood. Nuclear reactions are such quantities that can be partly measured in the laboratory. These reactions influence the nucleosynthesis of the elements in the Big Bang as well as in all objects formed thereafter, and control the associated energy generation and evolution of stars. Since 20 years LUNA (Laboratory for Underground Nuclear Astrophysics) has been measuring cross sections relevant for hydrogen burning in the Gran Sasso Laboratory and demonstrated the research potential of an underground accelerator facility. Unfortunately, the number of reactions is limited by the energy range accessible with the 400 kV LUNA accelerator. The CASPAR (Compact Accelerator System for Performing Astrophysical Research) Collaboration will implement a high intensity 1 MV accelerator at the Sanford Underground Research Facility (SURF) and overcome the current limitation at LUNA. This project will primarily focus on the neutron sources for the so-called s-process, e.g. 13 C(α , n) 16 O and 22 Ne(α , n) 25 Mg , and lead to unprecedented measurements compared to previous studies.

Steady state compact toroidal plasma production

DOEpatents

Turner, William C.

1986-01-01

Apparatus and method for maintaining steady state compact toroidal plasmas. A compact toroidal plasma is formed by a magnetized coaxial plasma gun and held in close proximity to the gun electrodes by applied magnetic fields or magnetic fields produced by image currents in conducting walls. Voltage supply means maintains a constant potential across the electrodes producing an increasing magnetic helicity which drives the plasma away from a minimum energy state. The plasma globally relaxes to a new minimum energy state, conserving helicity according to Taylor's relaxation hypothesis, and injecting net helicity into the core of the compact toroidal plasma. Controlling the voltage so as to inject net helicity at a predetermined rate based on dissipative processes maintains or increases the compact toroidal plasma in a time averaged steady state mode.

Reduced withdrawal and failure rates of accelerated nursing students enrolled in pharmacology is associated with a supportive intervention.

PubMed

Doggrell, Sheila Anne; Schaffer, Sally

2016-02-01

To reduce nursing shortages, accelerated nursing programs are available for domestic and international students. However, the withdrawal and failure rates from these programs may be different than for the traditional programs. The main aim of our study was to improve the retention and experience of accelerated nursing students. The academic background, age, withdrawal and failure rates of the accelerated and traditional students were determined. Data from 2009 and 2010 were collected prior to intervention. In an attempt to reduce the withdrawal of accelerated students, we set up an intervention, which was available to all students. The assessment of the intervention was a pre-post-test design with non-equivalent groups (the traditional and the accelerated students). The elements of the intervention were a) a formative website activity of some basic concepts in anatomy, physiology and pharmacology, b) a workshop addressing study skills and online resources, and c) resource lectures in anatomy/physiology and microbiology. The formative website and workshop was evaluated using questionnaires. The accelerated nursing students were five years older than the traditional students (p < 0.0001). The withdrawal rates from a pharmacology course are higher for accelerated nursing students, than for traditional students who have undertaken first year courses in anatomy and physiology (p = 0.04 in 2010). The withdrawing students were predominantly the domestic students with non-university qualifications or equivalent experience. The failure rates were also higher for this group, compared to the traditional students (p = 0.05 in 2009 and 0.03 in 2010). In contrast, the withdrawal rates for the international and domestic graduate accelerated students were very low. After the intervention, the withdrawal and failure rates in pharmacology for domestic accelerated students with non-university qualifications were not significantly different than those of traditional students. The accelerated international and domestic graduate nursing students have low withdrawal rates and high success rates in a pharmacology course. However, domestic students with non-university qualifications have higher withdrawal and failure rates than other nursing students and may be underprepared for university study in pharmacology in nursing programs. The introduction of an intervention was associated with reduced withdrawal and failure rates for these students in the pharmacology course.

Design approach for the development of a cryomodule for compact crab cavities for Hi-Lumi LHC

NASA Astrophysics Data System (ADS)

Pattalwar, Shrikant; Jones, Thomas; Templeton, Niklas; Goudket, Philippe; McIntosh, Peter; Wheelhouse, Alan; Burt, Graeme; Hall, Ben; Wright, Loren; Peterson, Tom

2014-01-01

A prototype Superconducting RF (SRF) cryomodule, comprising multiple compact crab cavities is foreseen to realise a local crab crossing scheme for the "Hi-Lumi LHC", a project launched by CERN to increase the luminosity performance of LHC. A cryomodule with two cavities will be initially installed and tested on the SPS drive accelerator at CERN to evaluate performance with high-intensity proton beams. A series of boundary conditions influence the design of the cryomodule prototype, arising from; the complexity of the cavity design, the requirement for multiple RF couplers, the close proximity to the second LHC beam pipe and the tight space constraints in the SPS and LHC tunnels. As a result, the design of the helium vessel and the cryomodule has become extremely challenging. This paper assesses some of the critical cryogenic and engineering design requirements and describes an optimised cryomodule solution for the evaluation tests on SPS.

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.

Development of a compact filament-discharge multi-cusp H- ion source.

PubMed

Jia, XianLu; Zhang, TianJue; Zheng, Xia; Qin, JiuChang

2012-02-01

A 14 MeV medical cyclotron with the external ion source has been designed and is being constructed at China Institute of Atomic Energy. The H(-) ion will be accelerated by this machine and the proton beam will be extracted by carbon strippers in dual opposite direction. The compact multi-cusp H(-) ion source has been developed for the cyclotron. The 79.5 mm long ion source is 48 mm in diameter, which is consisting of a special shape filament, ten columns of permanent magnets providing a multi-cusp field, and a three-electrode extraction system. So far, the 3 mA∕25 keV H(-) beam with an emittance of 0.3 π mm mrad has been obtained from the ion source. The paper gives the design details and the beam test results. Further experimental study is under way and an extracted beam of 5 mA is expected.

Effects of calcium phosphate/chitosan composite on bone healing in rats: calcium phosphate induces osteon formation.

PubMed

Fernández, Tulio; Olave, Gilberto; Valencia, Carlos H; Arce, Sandra; Quinn, Julian M W; Thouas, George A; Chen, Qi-Zhi

2014-07-01

Vascularization of an artificial graft represents one of the most significant challenges facing the field of bone tissue engineering. Over the past decade, strategies to vascularize artificial scaffolds have been intensively evaluated using osteoinductive calcium phosphate (CaP) biomaterials in animal models. In this work, we observed that CaP-based biomaterials implanted into rat calvarial defects showed remarkably accelerated formation and mineralization of new woven bone in defects in the initial stages, at a rate of ∼60 μm/day (0.8 mg/day), which was considerably higher than normal bone growth rates (several μm/day, 0.1 mg/day) in implant-free controls of the same age. Surprisingly, we also observed histological evidence of primary osteon formation, indicated by blood vessels in early-region fibrous tissue, which was encapsulated by lamellar osteocyte structures. These were later fully replaced by compact bone, indicating complete regeneration of calvarial bone. Thus, the CaP biomaterial used here is not only osteoinductive, but vasculogenic, and it may have contributed to the bone regeneration, despite an absence of osteons in normal rat calvaria. Further investigation will involve how this strategy can regulate formation of vascularized cortical bone such as by control of degradation rate, and use of models of long, dense bones, to more closely approximate repair of human cortical bone.

Novel Linac Structures For Low-Beta Ions And For Muons

NASA Astrophysics Data System (ADS)

Kurennoy, Sergey S.

2011-06-01

Development of two innovative linacs is discussed. (1) High-efficiency normal-conducting accelerating structures for ions with beam velocities in the range of a few percent of the speed of light. Two existing accelerator technologies—the H-mode resonator cavities and transverse beam focusing by permanent-magnet quadrupoles (PMQ)—are merged to create efficient structures for light-ion beams of considerable currents. The inter-digital H-mode accelerator with PMQ focusing (IH-PMQ) has the shunt impedance 10-20 times higher than the standard drift-tube linac. Results of the combined 3-D modeling for an IH-PMQ accelerator tank—electromagnetic computations, beam-dynamics simulations, and thermal-stress analysis—are presented. H-PMQ structures following a short RFQ accelerator can be used in the front end of ion linacs or in stand-alone applications like a compact mobile deuteron-beam accelerator up to a few MeV. (2) A large-acceptance high-gradient linac for accelerating low-energy muons in a strong solenoidal magnetic field. When a proton beam hits a target, many low-energy pions are produced almost isotropically, in addition to a small number of high-energy pions in the forward direction. We propose to collect and accelerate copious muons created as the low-energy pions decay. The acceleration should bring muons to a kinetic energy of ˜200 MeV in about 10 m, where both an ionization cooling of the muon beam and its further acceleration in a superconducting linac become feasible. One potential solution is a normal-conducting linac consisting of independently fed 0-mode RF cavities with wide apertures closed by thin metal windows or grids. The guiding magnetic field is provided by external superconducting solenoids. The cavity choice, overall linac design considerations, and simulation results of muon acceleration are presented. Potential applications range from basic research to homeland defense to industry and medicine.

The Most Compact Bright Radio-loud AGNs. II. VLBA Observations of 10 Sources at 43 and 86 GHz

NASA Astrophysics Data System (ADS)

Cheng, X.-P.; An, T.; Hong, X.-Y.; Yang, J.; Mohan, P.; Kellermann, K. I.; Lister, M. L.; Frey, S.; Zhao, W.; Zhang, Z.-L.; Wu, X.-C.; Li, X.-F.; Zhang, Y.-K.

2018-01-01

Radio-loud active galactic nuclei (AGNs), hosting powerful relativistic jet outflows, provide an excellent laboratory for studying jet physics. Very long baseline interferometry (VLBI) enables high-resolution imaging on milli-arcsecond (mas) and sub-mas scales, making it a powerful tool to explore the inner jet structure, shedding light on the formation, acceleration, and collimation of AGN jets. In this paper, we present Very Long Baseline Array observations of 10 radio-loud AGNs at 43 and 86 GHz that were selected from the Planck catalog of compact sources and are among the brightest in published VLBI images at and below 15 GHz. The image noise levels in our observations are typically 0.3 and 1.5 mJy beam‑1 at 43 and 86 GHz, respectively. Compared with the VLBI data observed at lower frequencies from the literature, our observations with higher resolutions (with the highest resolution being up to 0.07 mas at 86 GHz and 0.18 mas at 43 GHz) and at higher frequencies detected new jet components at sub-parsec scales, offering valuable data for studies of the physical properties of the innermost jets. These include the compactness factor of the radio structure (the ratio of core flux density to total flux density), and core brightness temperature ({T}{{b}}). In all these sources, the compact core accounts for a significant fraction (> 60 % ) of the total flux density. Their correlated flux density at the longest baselines is higher than 0.16 Jy. The compactness of these sources make them good phase calibrators of millimeter-wavelength ground-based and space VLBI.

The Nano-X Linear Accelerator: A Compact and Economical Cancer Radiotherapy System Incorporating Patient Rotation.

PubMed

Eslick, Enid M; Keall, Paul J

2015-10-01

Rapid technological improvements in radiotherapy delivery results in improved outcomes to patients, yet current commercial systems with these technologies on board are costly. The aim of this study was to develop a state-of-the-art cancer radiotherapy system that is economical and space efficient fitting with current world demands. The Nano-X system is a compact design that is light weight combining a patient rotation system with a vertical 6 MV fixed beam. In this paper, we present the Nano-X system design configuration, an estimate of the system dimensions and its potential impact on shielding cost reductions. We provide an assessment of implementing such a radiotherapy system clinically, its advantages and disadvantages compared to a compact conventional gantry rotating linac. The Nano-X system has several differentiating features from current radiotherapy systems, it is [1] compact and therefore can fit into small vaults, [2] light weight, and [3] engineering efficient, i.e., it rotates a relatively light component and the main treatment delivery components are not under rotation (e.g., DMLCs). All these features can have an impact on reducing the costs of the system. In terms of shielding requirements, leakage radiation was found to be the dominant contributor to the Nano-X vault and as such no primary shielding was necessary. For a low leakage design, the Nano-X vault footprint and concrete volume required is 17 m2 and 35 m3 respectively, compared to 54 m2 and 102 m3 for a conventional compact linac vault, resulting in decreased costs in shielding. Key issues to be investigated in future work are the possible patient comfort concerns associated with the patient rotation system, as well as the magnitude of deformation and subsequent adaptation requirements. © The Author(s) 2014.

Part I: RNA hydrolysis catalyzed by imidazole compounds. Part II. Hydrophobic acceleration of reactions and mimics of thiamin-dependent enzymes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kool, E.T.

1988-01-01

Catalysts modeled after the active site groups of the enzyme Ribonuclease A were synthesized and tested for catalysis of the hydrolysis of poly(rU), using a quantitative assay. The most effective of all the catalysts is N,N{prime}-bis-imidazolylmethane, which gave a four-fold rate enhancement as compared to N-methyl-imidazole. The structure/activity relationships are discussed in light of the ribonuclease mechanism. Also examined were reactions catalyzed by the coenzyme thiamine. In an investigation of the effects of restricting conformational freedom, a thiazolium salt was attached in two positions to {beta}-cyclodextrin. Since the catalyst gave about the same rate for tritium exchange from benzaldehyde asmore » singly-attached catalysts, we surmise that any rate enhancement due to the restriction of bond rotations has been lost by forcing the structure into less productive conformations. The benzoin condensation catalyzed by cyanide was also investigated. The reaction was shown to be faster in water than in most organic solvents. Kinetic salt effects and the effects of added {beta}- and {gamma}-cyclodextrin were measured in water; salting-out ions and {gamma}-cyclodextrin increase the rate, while salting-in ions and {beta}-cyclodextrin decrease it. Negative salt effects were observed in formamide, ethylene glycol, and DMSO. All these media effects are discussed in relation to the compact, hydrophobic transition state for the reaction.« less

Selection, Evaluation, and Rating of Compact Heat Exchangers v. 1.006

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, Matthew D.

2016-11-09

SEARCH determines and optimizes the design of a compact heat exchanger for specified process conditions. The user specifies process boundary conditions including the fluid state and flow rate and SEARCH will determine the optimum flow arrangement, channel geometry, and mechanical design for the unit. Fluids are modeled using NIST Refprop or tabulated values. A variety of thermal-hydraulic correlations are available including user-defined equations to accurately capture the heat transfer and pressure drop behavior of the process flows.

Shear-enhanced compaction in viscoplastic rocks

NASA Astrophysics Data System (ADS)

Yarushina, V. M.; Podladchikov, Y. Y.

2012-04-01

The phenomenon of mutual influence of compaction and shear deformation was repeatedly reported in the literature over the past years. Dilatancy and shear-enhanced compaction of porous rocks were experimentally observed during both rate-independent and rate-dependent inelastic deformation. Plastic pore collapse was preceding the onset of dilatancy and shear-enhanced compaction. Effective bulk viscosity is commonly used to describe compaction driven fluid flow in porous rocks. Experimental data suggest that bulk viscosity of a fluid saturated rock might be a function of both the effective pressure and the shear stress. Dilatancy and shear-enhanced compaction can alter the transport properties of rocks through their influence on permeability and compaction length scale. Recent investigations show that shear stresses in deep mantle rocks can be responsible for spontaneous development of localized melt-rich bands and segregation of small amounts of melt from the solid rock matrix through shear channeling instability. Usually it is assumed that effective viscosity is a function of porosity only. Thus coupling between compaction and shear deformation is ignored. Spherical model which considers a hollow sphere subjected to homogeneous tractions on the outer boundary as a representative elementary volume succeeded in predicting the volumetric compaction behavior of porous rocks and metals to a hydrostatic pressure in a wide range of porosities. Following the success of this simple model we propose a cylindrical model of void compaction and decompaction due to the non-hydrostatic load. The infinite viscoplastic layer with a cylindrical hole is considered as a representative volume element. The remote boundary of the volume is subjected to a homogeneous non-hydrostatic load such that plane strain conditions are fulfilled through the volume. At some critical values of remote stresses plastic zone develops around the hole. The dependence of the effective bulk viscosity on the properties of individual components as well as on the stress state is examined. We show that bulk viscosity is a function of porosity, effective pressure and shear stress. Decreasing porosity tends to increase bulk viscosity whereas increasing shear stress and increasing effective pressure reduce it.

A comparison of constant acceleration swimming speeds when acceleration rates are different with critical swimming speeds in Chinese bream under two oxygen tensions.

PubMed

Wang, Jian-Wei; Cao, Zhen-Dong; Fu, Shi-Jian

2016-10-01

To investigate the effect of acceleration rates on the constant acceleration test speed (U cat) and to compare U cat with the critical swimming speed (U crit) in Chinese bream (Parabramis pekinensis), the U cat test at acceleration rates of 0.05, 0.1, 0.2, 0.4 and 0.8 cm s(-2) and the U crit test in juvenile fish at 20 °C in either normoxia (>90 % saturation oxygen tension) or hypoxia (30 % saturation) were compared. The lactate concentration ([lactate]) of white muscle, liver and plasma and the glycogen concentration ([glycogen]) of white muscle and liver were also measured to identify whether tissue substrate depletion or tissue lactate accumulation correlated with exhaustion. The U cat decreased with the acceleration rate, and there was no significant difference between U crit and U cat at lower acceleration rates. Hypoxia resulted in lower U cat and U crit, and the difference increased with decreased acceleration rates of the U cat test, possibly due to the increased contribution of aerobic components in U crit or U cat at low acceleration rates. Hypoxia elicited a significant decrease in muscle [glycogen] and an increase in muscle and liver [lactate] in resting fish. All post-exercise fish had similar muscle [lactate], suggesting that tissue lactate accumulation may correlate with exercise exhaustion. Unlike hypoxia, exercise induced an increase in muscle [lactate] and a significant increase in plasma [lactate], which were worthy of further investigation. The similar swimming speed and biochemical indicators after exercise in the U crit and U cat groups at low acceleration rates suggested that U cat can be an alternative for the more frequently adopted protocols in U crit in Chinese bream and possibly in other cyprinid fish species.

Single-Mode, High Repetition Rate, Compact Ho:YLF Laser for Space-Borne Lidar Applications

NASA Technical Reports Server (NTRS)

Bai, Yingxin; Yu, Jirong; Wong, Teh-Hwa; Chen, Songsheng; Petros, Mulugeta; Singh, Upendra N.

2014-01-01

A single transverse/longitudinal mode, compact Q-switched Ho:YLF laser has been designed and demonstrated for space-borne lidar applications. The pulse energy is between 34-40 mJ for 100-200 Hz operation. The corresponding peak power is >1 MW.

The Inconvenient Truth of Fresh Sediment: Insights from a New Method for Quantifying Subsidence in the Mississippi Delta

NASA Astrophysics Data System (ADS)

Chamberlain, E. L.; Shen, Z.; Tornqvist, T. E.; Kim, W.

2017-12-01

Knowing the rates and drivers of subsidence in deltas is essential to coastal management. There is a growing consensus that relatively shallow processes such as compaction and artificial drainage are primary contributors to subsidence, although deeper processes such as faulting may be locally important. Here we present a new method to quantify subsidence of a 6000 km2 relict bayhead delta of the Mississippi Delta, using the depth of the mouthbar-overbank stratigraphic boundary that formed near the low tide level in combination with OSL chronology. The contributions of isostatic processes are removed by subtracting a relative sea-level rise term previously obtained from basal peat. We find that displacement rates of the boundary, averaged over 750 to 1500 years, are on the order of a few mm/yr. Cumulative displacement is strongly correlated to overburden thickness, decreases coastward coincident with thinning of the bayhead delta deposit, and appears unrelated to the thickness of underlying Holocene strata or the occurrence of previously mapped faults. This supports compaction of shallow strata as a dominant driver of subsidence in the Mississippi Delta. We find that at least 50% of elevation gained through overbank deposition is ultimately lost to subsidence, significantly greater than the 35% loss previously estimated for inland localities underlain by peat. Our results demonstrate that bayhead deltas are especially vulnerable to subsidence. This finding has major relevance to coastal restoration in the Mississippi Delta through engineered river-sediment diversions. While inactive regions of the delta may be fairly stable if not perturbed by humans, the introduction of fresh sediment to the delta plain will inevitably accelerate subsidence. Values obtained with our method will be applied to a delta growth model that predicts the land-building potential of river-sediment diversions discharging into open bays under realistic scenarios of load-driven subsidence.

Exploring mechanisms of compaction in salt-marsh sediments using Common Era relative sea-level reconstructions

NASA Astrophysics Data System (ADS)

Brain, Matthew J.; Kemp, Andrew C.; Hawkes, Andrea D.; Engelhart, Simon E.; Vane, Christopher H.; Cahill, Niamh; Hill, Troy D.; Donnelly, Jeffrey P.; Horton, Benjamin P.

2017-07-01

Salt-marsh sediments provide precise and near-continuous reconstructions of Common Era relative sea level (RSL). However, organic and low-density salt-marsh sediments are prone to compaction processes that cause post-depositional distortion of the stratigraphic column used to reconstruct RSL. We compared two RSL reconstructions from East River Marsh (Connecticut, USA) to assess the contribution of mechanical compression and biodegradation to compaction of salt-marsh sediments and their subsequent influence on RSL reconstructions. The first, existing reconstruction ('trench') was produced from a continuous sequence of basal salt-marsh sediment and is unaffected by compaction. The second, new reconstruction is from a compaction-susceptible core taken at the same location. We highlight that sediment compaction is the only feasible mechanism for explaining the observed differences in RSL reconstructed from the trench and core. Both reconstructions display long-term RSL rise of ∼1 mm/yr, followed by a ∼19th Century acceleration to ∼3 mm/yr. A statistically-significant difference between the records at ∼1100 to 1800 CE could not be explained by a compression-only geotechnical model. We suggest that the warmer and drier conditions of the Medieval Climate Anomaly (MCA) resulted in an increase in sediment compressibility during this time period. We adapted the geotechnical model by reducing the compressive strength of MCA sediments to simulate this softening of sediments. 'Decompaction' of the core reconstruction with this modified model accounted for the difference between the two RSL reconstructions. Our results demonstrate that compression-only geotechnical models may be inadequate for estimating compaction and post-depositional lowering of susceptible organic salt-marsh sediments in some settings. This has important implications for our understanding of the drivers of sea-level change. Further, our results suggest that future climate changes may make salt marshes more susceptible to the impacts of RSL rise by enhancing sediment compressibility. We stress, however, that the cause of the softening remains enigmatic. Until this is better constrained, it is premature to widely extrapolate our findings to existing core-based reconstructions of Holocene RSL.

Lattice Design for a High-Power Infrared FEL

NASA Astrophysics Data System (ADS)

Douglas, D. R.

1997-05-01

A 1 kW infrared FEL, funded by the U.S. Navy, is under construction at Jefferson Lab. This device will be driven by a compact, 42 MeV, 5 mA, energy-recovering, CW SRF-based linear accelerator to produce light in the 3-6.6 μm range. The machine concept comprises a 10 MeV injector, a linac based on a single high-gradient Jefferson Lab accelerator cryomodule, a wiggler and optical cavity, and an energy-recovery recirculation arc. Energy recovery limits cost and technical risk by reducing the RF power requirements in the driver accelerator. Following deceleration to 10 MeV, the beam is dumped. Stringent phase space requirements at the wiggler, low beam energy, and high beam current subject the accelerator lattice to numerous constraints. Principal considerations include: transport and delivery to the FEL of a high-quality, high-current beam; the impact of coherent synchrotron radiation (CSR) during beam recirculation transport; beam optics aberration control, to provide low-loss energy-recovery transport of a 5% relative momentum spread, high-current beam; attention to possible beam breakup (BBU) instabilities in the recirculating accelerator; and longitudinal phase space management during beam transport, to optimize RF drive system control during energy recovery and FEL operation. The presentation will address the design process and design solution for an accelerator transport lattice that meets the requirements imposed by these physical phenomena and operational necessities.

Numerical investigation on the effects of acceleration reversal times in Rayleigh-Taylor Instability with multiple reversals

NASA Astrophysics Data System (ADS)

Farley, Zachary; Aslangil, Denis; Banerjee, Arindam; Lawrie, Andrew G. W.

2017-11-01

An implicit large eddy simulation (ILES) code, MOBILE, is used to explore the growth rate of the mixing layer width of the acceleration-driven Rayleigh-Taylor instability (RTI) under variable acceleration histories. The sets of computations performed consist of a series of accel-decel-accel (ADA) cases in addition to baseline constant acceleration and accel-decel (AD) cases. The ADA cases are a series of varied times for the second acceleration reversal (t2) and show drastic differences in the growth rates. Upon the deceleration phase, the kinetic energy of the flow is shifted into internal wavelike patterns. These waves are evidenced by the examined differences in growth rate in the second acceleration phase for the set of ADA cases. Here, we investigate global parameters that include mixing width, growth rates and the anisotropy tensor for the kinetic energy to better understand the behavior of the growth during the re-acceleration period. Authors acknowledge financial support from DOE-SSAA (DE-NA0003195) and NSF CAREER (#1453056) awards.

Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning

USGS Publications Warehouse

Holland, P. R.; Brisbourne, A.; Corr, H. F. J.; Mcgrath, Daniel; Purdon, K.; Paden, J.; Fricker, H. A.; Paolo, F. S.; Fleming, A.H.

2015-01-01

The catastrophic collapses of Larsen A and B ice shelves on the eastern Antarctic Peninsula have caused their tributary glaciers to accelerate, contributing to sea-level rise and freshening the Antarctic Bottom Water formed nearby. The surface of Larsen C Ice Shelf (LCIS), the largest ice shelf on the peninsula, is lowering. This could be caused by unbalanced ocean melting (ice loss) or enhanced firn melting and compaction (englacial air loss). Using a novel method to analyse eight radar surveys, this study derives separate estimates of ice and air thickness changes during a 15-year period. The uncertainties are considerable, but the primary estimate is that the surveyed lowering (0.066 ± 0.017 m yr−1) is caused by both ice loss (0.28 ± 0.18 m yr−1) and firn-air loss (0.037 ± 0.026 m yr−1). The ice loss is much larger than the air loss, but both contribute approximately equally to the lowering because the ice is floating. The ice loss could be explained by high basal melting and/or ice divergence, and the air loss by low surface accumulation or high surface melting and/or compaction. The primary estimate therefore requires that at least two forcings caused the surveyed lowering. Mechanisms are discussed by which LCIS stability could be compromised in the future. The most rapid pathways to collapse are offered by the ungrounding of LCIS from Bawden Ice Rise or ice-front retreat past a "compressive arch" in strain rates. Recent evidence suggests that either mechanism could pose an imminent risk.

Impacts into porous asteroids

NASA Astrophysics Data System (ADS)

Housen, Kevin R.; Sweet, William J.; Holsapple, Keith A.

2018-01-01

Many small bodies in the solar system have bulk density well below the solid density of the constituent mineral grains in their meteorite counterparts. Those low-density bodies undoubtedly have significant porosity, which is a key factor that affects the formation of impact craters. This paper summarizes the results of lab experiments in which materials with porosity ranging from 43% to 96% were impacted at ∼1800 m/s. The experiments were performed on a geotechnical centrifuge, in order to reproduce the lithostatic overburden stress and ejecta ballistics that occur in large-scale cratering events on asteroids or planetary satellites. Experiments performed at various accelerations, up to 514G, simulate the outcomes of impacts at size scales up to several tens of km in diameter. Our experiments show that an impact into a highly porous cohesionless material generates a large ovoid-shaped cavity, due to crushing by the outgoing shock. The cavity opens up to form a transient crater that grows until the material flow is arrested by gravity. The cavity then collapses to form the final crater. During collapse, finely crushed material that lines the cavity wall is carried down and collected in a localized region below the final crater floor. At large simulated sizes (high accelerations), most of the crater volume is formed by compaction, because growth of the transient crater is quickly arrested. Nearly all ejected material falls back into the crater, leaving the crater without an ejecta blanket. We find that such compaction cratering and suppression of the ejecta blankets occur for large craters on porous bodies when the ratio of the lithostatic stress at one crater depth to the crush strength of the target exceeds ∼0.005. The results are used to identify small solar system bodies on which compaction cratering likely occurs. A model is developed that gives the crater size and ejecta mass that would result for a specified impact into a porous object.