WorldWideScience

Sample records for accelerator pulsed fast assembly

  1. Pulsed neutron source based on accelerator-subcritical-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Makoto; Noda, Akira; Iwashita, Yoshihisa; Okamoto, Hiromi; Shirai, Toshiyuki [Kyoto Univ., Uji (Japan). Inst. for Chemical Research

    1997-03-01

    A new pulsed neutron source which consists of a 300MeV proton linac and a nuclear fuel subcritical assembly is proposed. The proton linac produces pulsed spallation neutrons, which are multipied by the subcritical assembly. A prototype proton linac that accelerates protons up to 7MeV has been developed and a high energy section of a DAW structure is studied with a power model. Halo formations in high intensity beam are also being studied. (author)

  2. Investigation of linear accelerator pulse delivery using fast organic scintillator measurements

    DEFF Research Database (Denmark)

    Beierholm, Anders Ravnsborg; Andersen, Claus Erik; Lindvold, Lars René;

    2010-01-01

    Fiber-coupled organic plastic scintillators present an attractive method for time-resolved dose measurements during radiotherapy. Most organic scintillators exhibit a fast response, making it possible to use them to measure individual high-energy X-ray pulses from a medical linear accelerator. Th...

  3. Energy distribution of fast electrons accelerated by high intensity laser pulse depending on laser pulse duration

    Science.gov (United States)

    Kojima, Sadaoki; Arikawa, Yasunobu; Morace, Alessio; Hata, Masayasu; Nagatomo, Hideo; Ozaki, Tetsuo; Sakata, Shohei; Lee, Seung Ho; Matsuo, Kazuki; Farley Law, King Fai; Tosaki, Shota; Yogo, Akifumi; Johzaki, Tomoyuki; Sunahara, Atsushi; Sakagami, Hitoshi; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Fujioka, Shinsuke; Azechi, Hiroshi

    2016-05-01

    The dependence of high-energy electron generation on the pulse duration of a high intensity LFEX laser was experimentally investigated. The LFEX laser (λ = 1.054 and intensity = 2.5 – 3 x 1018 W/cm2) pulses were focused on a 1 mm3 gold cubic block after reducing the intensities of the foot pulse and pedestal by using a plasma mirror. The full width at half maximum (FWHM) duration of the intense laser pulse could be set to either 1.2 ps or 4 ps by temporally stacking four beams of the LFEX laser, for which the slope temperature of the high-energy electron distribution was 0.7 MeV and 1.4 MeV, respectively. The slope temperature increment cannot be explained without considering pulse duration effects on fast electron generation.

  4. Accelerated ions from pulsed-power-driven fast plasma flow in perpendicular magnetic field

    Science.gov (United States)

    Takezaki, Taichi; Takahashi, Kazumasa; Sasaki, Toru; Kikuchi, Takashi; Harada, Nob.

    2016-06-01

    To understand the interaction between fast plasma flow and perpendicular magnetic field, we have investigated the behavior of a one-dimensional fast plasma flow in a perpendicular magnetic field by a laboratory-scale experiment using a pulsed-power discharge. The velocity of the plasma flow generated by a tapered cone plasma focus device is about 30 km/s, and the magnetic Reynolds number is estimated to be 8.8. After flow through the perpendicular magnetic field, the accelerated ions are measured by an ion collector. To clarify the behavior of the accelerated ions and the electromagnetic fields, numerical simulations based on an electromagnetic hybrid particle-in-cell method have been carried out. The results show that the behavior of the accelerated ions corresponds qualitatively to the experimental results. Faster ions in the plasma flow are accelerated by the induced electromagnetic fields modulated with the plasma flow.

  5. Investigation of linear accelerator pulse delivery using fast organic scintillator measurements

    Energy Technology Data Exchange (ETDEWEB)

    Beierholm, A.R., E-mail: anders.beierholm@risoe.d [Radiation Research Department, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Andersen, C.E.; Lindvold, L.R. [Radiation Research Department, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Aznar, M.C. [Department of Radiation Oncology, Copenhagen University Hospital, DK-2100 Copenhagen (Denmark)

    2010-03-15

    Fiber-coupled organic plastic scintillators present an attractive method for time-resolved dose measurements during radiotherapy. Most organic scintillators exhibit a fast response, making it possible to use them to measure individual high-energy X-ray pulses from a medical linear accelerator. This can be used in complex treatment procedures such as gated intensity-modulated radiotherapy (IMRT), where the advantage of dose rate measurements of high temporal resolution is highly emphasized. We report on development of a fast data acquisition scintillator-based system as well as measurements performed on Varian medical linear accelerators, delivering 6 MV X-ray beams. The dose delivery per radiation pulse was found to agree with expectations within roughly 1%, although minor discrepancies and transients were evident in the measurements.

  6. Electric drive for accelerator target with a timer for a fast pulsed reactor

    International Nuclear Information System (INIS)

    The invention refers to electric drives with digital control. The electric drive provides for cophased rotation of the target-containing particle reflector and the frequency of the accelerator functioning, the syncronization being provided by the current mains. At the same time the reflector may rotate with any given velocity in the necessary range, this being required also for the work of pulse fast neutron reactor. The drive involves a driving syncronic engine, an electromagnetic clutch, a pulse velocity indicator and a digital regulator with a velocity measuring block, a counter and a memory block

  7. Compact pulsed accelerator

    International Nuclear Information System (INIS)

    The formation of fast pulses from a current charged transmission line and opening switch is described. By employing a plasma focus as an opening switch and diode in the prototype device, a proton beam of peak energy 250 keV is produced. The time integrated energy spectrum of the beam is constructed from a Thomson spectrograph. Applications of this device as an inexpensive and portable charged particle accelerator are discussed. 7 refs., 5 figs., 1 tab

  8. Petawatt pulsed-power accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Stygar, William A. (Albuquerque, NM); Cuneo, Michael E. (Albuquerque, NM); Headley, Daniel I. (Albuquerque, NM); Ives, Harry C. (Albuquerque, NM); Ives, legal representative; Berry Cottrell (Albuquerque, NM); Leeper, Ramon J. (Albuquerque, NM); Mazarakis, Michael G. (Albuquerque, NM); Olson, Craig L. (Albuquerque, NM); Porter, John L. (Sandia Park, NM); Wagoner; Tim C. (Albuquerque, NM)

    2010-03-16

    A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

  9. Electric drive for an accelerator target with a timer for a pulsed fast reactor

    International Nuclear Information System (INIS)

    The invention is presented relating to electric drives with numerical control devices. An electric drive is described, comprising a synchronous drive motor, an electromagnetic clutch, a pulse speed transducer, and a numerical control device with a speed measuring unit, a counter, and a storage unit. The electric drive ensures cophasal rotation of a particle reflector with an attached target at the operating frequency of the accelarator, which is synchronized from the mains with a possibility of maintaining the reflector rotation at any preset invariable speed within a desired range

  10. Pulsed Superconductivity Acceleration

    CERN Document Server

    Liepe, M

    2000-01-01

    The design of the proposed linear collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities, operated in pulsed mode. Within the framework of an international collaboration the TESLA Test Facility (TTF) has been set up at DESY, providing the infrastructure for cavity R&D towards higher gradients. More than 60 nine-cell cavities were tested, accelerating gradients as high as 30 MV/m were measured. In the second production of TTF-cavities the average gradient was measured to be 24.7 MV/m. Two modules, each containing eight resonators, are presently used in the TTF-linac. These cavities are operated in pulsed mode: 0.8 ms constant gradient with up to 10 Hz repetitions rate. We will focus on two aspects: Firstly, the cavity fabrication and treatment is discussed, allowing to reach high gradients. Latest results of single cell cavities will be shown, going beyond 40 MV/m. Secondly, the pulsed mode operation of superconducting cavities is reviewed. This includes Lorentz force detuning, mechanic...

  11. Sequentially pulsed traveling wave accelerator

    Science.gov (United States)

    Caporaso, George J.; Nelson, Scott D.; Poole, Brian R.

    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.

  12. Assembly delay line pulse generators

    CERN Multimedia

    1971-01-01

    Assembly of six of the ten delay line pulse generators that will power the ten kicker magnet modules. One modulator part contains two pulse generators. Capacitors, inductances, and voltage dividers are in the oil tank on the left. Triggered high-pressure spark gap switches are on the platforms on the right. High voltage pulse cables to the kicker magnet emerge under the spark gaps. In the centre background are the assembled master gaps.

  13. Load assembly design of the FAST machine

    International Nuclear Information System (INIS)

    The preliminary design of the FAST (Fusion Advanced Studies Torus) Load Assembly is presented. FAST is a compact and cost effective machine operating with plasma current Ip from 3 MA, in the long pulse advanced scenario, up to 7.5 MA, in standard H-Mode. FAST, has a pulsed, resistive copper magnets which are at cryogenic temperatures and adiabatically heated during the plasma pulse. The cooling is guaranteed by Helium gas allowing the extension of the flat-top to about 3 min. The magnet dimensions has been determined by the cooling requirements. TF magnet ripple has limitated with optimized ferromagnetic inserts. The Vacuum Vessel is adequate to accommodate the whole heating system as well as to withstand the electromagnetic loads produced by plasma disruption. The first wall and the divertor are actively cooled by pressurized water. Liquid Lithium as divertor target will be tested. (author)

  14. Accelerator driven assembly

    Energy Technology Data Exchange (ETDEWEB)

    Balderas, J.; Cappiello, M.; Cummings, C.E.; Davidson, R. [and others

    1997-01-01

    This report addresses a Los Alamos National Laboratory (LANL) proposal to build a pulsed neutron source for simulating nuclear-weapons effects. A point design for the pulsed neutron facility was initiated early in FY94 after hosting a Defense Nuclear Agency (DNA) panel review and after subsequently visiting several potential clients and users. The technical and facility designs contained herein fulfill the Statement of Work (SOW) agreed upon by LANL and DNA. However, our point designs and parametric studies identify a unique, cost-effective, above-ground capability for neutron nuclear-weapons-effects studies at threat levels. This capability builds on existing capital installations and infrastructure at LANL. We believe that it is appropriate for us, together with the DNA, to return to the user community and ask for their comments and critiques. We also realize that the requirements of last year have changed significantly. Therefore, the present report is a `working document` that may be revised where feasible as we learn more about the most recent Department of Defense (DoD) and Department of Energy (DOE) needs.

  15. A nanosecond pulsed accelerator facility

    International Nuclear Information System (INIS)

    The operation and performance of a 3-MeV pulsed electrostatic generator producing 1-ns (10-9 s) pulses is described. The system employs terminal pulsing and post-acceleration time-compression to achieve short pulses and high average current. The specifications for this system were based on the following considerations. A 10-μA average beam current represents a reasonable limit based on the ability of a target to dissipate beam power, the 1-ns pulse-length was consistent with other factors such as detector response, energy homogeneity, etc. which determine over-all time resolution, and a repetition rate of 1 MHz/s gives a duty factor consistent with the current capabilities of existing accelerator ion sources. The system consists of a terminal pulsing component which produces pulses of 10 ns in duration by sweeping a beam over an aperture located at the entrance to an accelerator tube. An average output of a current of 10 μA requires a source capable of producing 1 mA of atomic ions. After acceleration this pulse is compressed to 1 ns by the scheme suggested by Mobley. This involves sweeping the beam with proper synchronization across the aperture of a 90o doubly-focusing deflection magnet so that the early portion of the pulse travels through a longer trajectory thani the later portions, thus achieving time compression when the beam is brought to a focus on a suitable target. The radius of beam curvature in the compression magnet is 30 in and the over-all beam divergence at the target is 5o. The choice of these parameters and the effect of the deflection scheme in the beam-energy homogeneity will be discussed. Using existing nanosecond detector techniques, this system has produced over-all system resolutions of 1 ns full-width at half-maximum for both gamma rays and neutrons. It is not yet known what component or components of the system determine the limits on the time resolution of the system. As a facility for investigating neutron inelastic scattering and

  16. Ion Acceleration by Short Chirped Laser Pulses

    Directory of Open Access Journals (Sweden)

    Jian-Xing Li

    2015-02-01

    Full Text Available Direct laser acceleration of ions by short frequency chirped laser pulses is investigated theoretically. We demonstrate that intense beams of ions with a kinetic energy broadening of about 1% can be generated. The chirping of the laser pulse allows the particles to gain kinetic energies of hundreds of MeVs, which is required for hadron cancer therapy, from pulses of energies in the order of 100 J. It is shown that few-cycle chirped pulses can accelerate ions more efficiently than long ones, i.e., higher ion kinetic energies are reached with the same amount of total electromagnetic pulse energy.

  17. Ion Acceleration by Short Chirped Laser Pulses

    CERN Document Server

    Li, Jian-Xing; Keitel, Christoph H; Harman, Zoltán

    2015-01-01

    Direct laser acceleration of ions by short frequency-chirped laser pulses is investigated theoretically. We demonstrate that intense beams of ions with a kinetic energy broadening of about 1 % can be generated. The chirping of the laser pulse allows the particles to gain kinetic energies of hundreds of MeVs, which is required for hadron cancer therapy, from pulses of energies of the order of 100 J. It is shown that few-cycle chirped pulses can accelerate ions more efficiently than long ones, i.e. higher ion kinetic energies are reached with the same amount of total electromagnetic pulse energy.

  18. Fast Neutron Resonance Radiography in a Pulsed Neutron Beam

    OpenAIRE

    Dangendorf, V.; Laczko, G; Kersten, C.; Jagutzki, O.; Spillmann, U

    2003-01-01

    The feasibility of performing fast neutron resonance radiography at the PTB accelerator facility is studied. A neutron beam of a broad spectral distribution is produced by a pulsed 13 MeV deuterium beam hitting a thick Be target. The potential of 3 different neutron imaging detectors with time-of flight capability are investigated. The applied methods comprise wire chambers with hydrogenous converter layers and a fast plastic scintillator with different optical readout schemes. We present the...

  19. Pulse propagation in the laser wakefield accelerator

    International Nuclear Information System (INIS)

    A high-density regime of the laser wakefield accelerator is reviewed in which enhanced acceleration is achieved via resonant self-modulation of the laser pulse. This requires laser power in excess of the critical power for optical guiding and a plasma wavelength short compared to the laser pulse-length. The evolution of the laser pulse is described, including a discussion of self-modulation and laser-hose instabilities. Examples of self-modulated laser wakefield accelerators are presented. copyright 1996 American Institute of Physics

  20. Nanosecond pulse generators for induction linear accelerators

    International Nuclear Information System (INIS)

    The paper reviews five different circuits of nanosecond pulse generators for induction linear accelerators. Hydrogen thyratrons which feature a good stability of parameters in time are used as switches. Short voltage pulses (1 - 5 ns) are shaped using nonlinear ferromagnetic lines.The voltage amplitude range on inductor excitation turns is 20-50 kV. 6 refs., 6 figs., 1 tab

  1. Design of a Compact Pulsed Power Accelerator

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    A 100 kA/60 ns compact pulsed power accelerator was designed to study the influence to the X-pinch by the load. It is composed of a Marx generator, a combined pulse forming (PFL), a gas-filled V/N field distortion switch, a transfer line,

  2. Harmonic ratcheting for fast acceleration

    Science.gov (United States)

    Cook, N.; Brennan, J. M.; Peggs, S.

    2014-04-01

    A major challenge in the design of rf cavities for the acceleration of medium-energy charged ions is the need to rapidly sweep the radio frequency over a large range. From low-power medical synchrotrons to high-power accelerator driven subcritical reactor systems, and from fixed focus alternating gradient accelerators to rapid cycling synchrotrons, there is a strong need for more efficient, and faster, acceleration of protons and light ions in the semirelativistic range of hundreds of MeV/u. A conventional way to achieve a large, rapid frequency sweep (perhaps over a range of a factor of 6) is to use custom-designed ferrite-loaded cavities. Ferrite rings enable the precise tuning of the resonant frequency of a cavity, through the control of the incremental permeability that is possible by introducing a pseudoconstant azimuthal magnetic field. However, rapid changes over large permeability ranges incur anomalous behavior such as the "Q-loss" and "f-dot" loss phenomena that limit performance while requiring high bias currents. Notwithstanding the incomplete understanding of these phenomena, they can be ameliorated by introducing a "harmonic ratcheting" acceleration scheme in which two or more rf cavities take turns accelerating the beam—one turns on when the other turns off, at different harmonics—so that the radio frequency can be constrained to remain in a smaller range. Harmonic ratcheting also has straightforward performance advantages, depending on the particular parameter set at hand. In some typical cases it is possible to halve the length of the cavities, or to double the effective gap voltage, or to double the repetition rate. This paper discusses and quantifies the advantages of harmonic ratcheting in general. Simulation results for the particular case of a rapid cycling medical synchrotron ratcheting from harmonic number 9 to 2 show that stability and performance criteria are met even when realistic engineering details are taken into consideration.

  3. Laser pulse shaping for high gradient accelerators

    Science.gov (United States)

    Villa, F.; Anania, M. P.; Bellaveglia, M.; Bisesto, F.; Chiadroni, E.; Cianchi, A.; Curcio, A.; Galletti, M.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Gatti, G.; Moreno, M.; Petrarca, M.; Pompili, R.; Vaccarezza, C.

    2016-09-01

    In many high gradient accelerator schemes, i.e. with plasma or dielectric wakefield induced by particles, many electron pulses are required to drive the acceleration of one of them. Those electron bunches, that generally should have very short duration and low emittance, can be generated in photoinjectors driven by a train of laser pulses coming inside the same RF bucket. We present the system used to shape and characterize the laser pulses used in multibunch operations at Sparc_lab. Our system gives us control over the main parameter useful to produce a train of up to five high brightness bunches with tailored intensity and time distribution.

  4. Pulse Power Supply for Plasma Dynamic Accelerator

    Institute of Scientific and Technical Information of China (English)

    YANG Xuanzong; LIU Jian; FENG Chunhua; WANG Long

    2008-01-01

    A new concept of a coaxial plasma dynamic accelerator with a self-energized mag-netic compressor coil to simulate the effects of space debris impact is demonstrated. A brief description is presented about the pulse power supply system including the charging circuit, start switch and current transfer system along with some of the key techniques for this kind of acceler-ator. Using this accelerator configuration, ceramic beads of 100 μm in diameter were accelerated to a speed as high as 18 km/sec. The facility can be used in a laboratory setting to study impact phenomena on solar array materials, potential structural materials for use in space.

  5. Fast Neutron Resonance Radiography in a Pulsed Neutron Beam

    CERN Document Server

    Dangendorf, V; Kersten, C; Jagutzki, O; Spillmann, U

    2003-01-01

    The feasibility of performing fast neutron resonance radiography at the PTB accelerator facility is studied. A neutron beam of a broad spectral distribution is produced by a pulsed 13 MeV deuterium beam hitting a thick Be target. The potential of 3 different neutron imaging detectors with time-of flight capability are investigated. The applied methods comprise wire chambers with hydrogenous converter layers and a fast plastic scintillator with different optical readout schemes. We present the neutron facility, the imaging methods employed and results obtained. in beam experiments where samples of carbon rods with various length and diameter were imaged to study resolution and sensitivity of the method.

  6. First measurements of the kinetic response of the muse-4 fast Ads mock-up to fast neutron pulse

    International Nuclear Information System (INIS)

    The MUSE-4 experiment has started its first commissioning measurements at the beginning of the year 2001 at CEA/Cadarache (France). This international experiment co-ordinated by CEA, included in the 5FWP of the European Union and GEDEON, is intended to study the physics of fast sub-critical assemblies coupled with a pulsed external source. To achieve this objective, the GENEPI accelerator, a (d,d) or (d,t) neutron source developed at CRNS/IN2P3/ISN (Grenoble), has been coupled with the MASURCA reactor, a uranium-plutonium MOX-based fast reactor, with solid sodium simulating a liquid metal coolant and a lead buffer to simulate a spallation target. The very short neutron pulse (1 μs) provided by GENEPI, together with the possibility to change the pulse repetition rate up to 5 kHz and the different levels of sub-criticality available will facilitate a study of the reactor kinetic parameters in situations close to most of the proposed accelerator-driven Systems (ADS). The paper presents the first experimental results for dynamic measurements performed in MUSE-4 configurations. Several pulsed neutron source experiments have been carried out using the (d,d) GENEPI neutron source in configurations going from USD 1,33 to USD 12,6. In addition, noise techniques (Rossi and Feynman-alpha) have been applied to stationary states in the same range of sub-criticalities. Reactivity levels obtained by these techniques have been compared with more classic rod drop/source multiplication measurements. The kinetic parameters, β(which ranges between 330 and 360 pcm) and β/Λ (with a value of approximately 6270 s-1), have been determined by Monte Carlo and/or deterministic codes. (author)

  7. Design and development of pulsed electron beam accelerator 'AMBICA - 600'

    Science.gov (United States)

    Verma, Rishi; Deb, Pankaj; Shukla, Rohit; Sharma, Surender; Shyam, Anurag

    2012-11-01

    Short duration, high power pulses with fast rise time and good flat-top are essentially required for driving pulsed electron beam diodes. To attain this objective, a dual resonant Tesla transformer based pulsed power accelerator 'AMBICA-600' has been developed. In this newly developed system, a coaxial water line is charged through single turn Tesla transformer that operates in the dual resonant mode. For making the accelerator compact, in the high power pulse forming line, water has been used as dielectric medium because of its high dielectric constant, high dielectric strength and high energy density. The coaxial waterline can be pulsed charged up to 600kV, has impedance of ~5Ω and generates pulse width of ~60ns. The integrated system is capable of producing intense electron beam of 300keV, 60kA when connected to impedance matched vacuum diode. In this paper, system hardware details and experimental results of gigawatt electron beam generation have been presented.

  8. Important concepts in the assembly and early characterization of the PBFA II accelerator

    International Nuclear Information System (INIS)

    Planning and efficient execution of the assembly and early characterization phases of a large, multi-module superpower generator like PBFA II require development of concepts frequently not found in either the pulsed power RandD community or in the pulsed power industry. To meet the constraints of performance, cost, and schedule of the PBFA II Project, special skills for assembly and characterization of large facilities are being established. These likely will become the technology for activating Sandia's future large accelerators. Some of the concepts for orchestrating large numbers of events associated with accelerator assembly and characterization include: structuring of activity into smaller workable and trackable packages, with associated subelements assigned to each section of the accelerator, and establishing detailed assembly and characterization documentation to assist in component testing and subsystem integration. The application of these and other concepts to FBFA II, and the progress of accelerator assembly are discussed

  9. YALINA-booster subcritical assembly pulsed-neutron experiments : data processing and spatial corrections.

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Y.; Gohar, Y.; Nuclear Engineering Division

    2010-10-11

    The YALINA-Booster experiments and analyses are part of the collaboration between Argonne National Laboratory of USA and the Joint Institute for Power & Nuclear Research - SOSNY of Belarus for studying the physics of accelerator driven systems for nuclear energy applications using low enriched uranium. The YALINA-Booster subcritical assembly is utilized for studying the kinetics of accelerator driven systems with its highly intensive D-T or D-D pulsed neutron source. In particular, the pulsed neutron methods are used to determine the reactivity of the subcritical system. This report examines the pulsed-neutron experiments performed in the YALINA-Booster facility with different configurations for the subcritical assembly. The 1141 configuration with 90% U-235 fuel and the 1185 configuration with 36% or 21% U-235 fuel are examined. The Sjoestrand area-ratio method is utilized to determine the reactivities of the different configurations. The linear regression method is applied to obtain the prompt neutron decay constants from the pulsed-neutron experimental data. The reactivity values obtained from the experimental data are shown to be dependent on the detector locations inside the subcritical assembly and the types of detector used for the measurements. In this report, Bell's spatial correction factors are calculated based on a Monte Carlo model to remove the detector dependences. The large differences between the reactivity values given by the detectors in the fast neutron zone of the YALINA-Booster are reduced after applying the spatial corrections. In addition, the estimated reactivity values after the spatial corrections are much less spatially dependent.

  10. Heavy ion acceleration using femtosecond laser pulses

    CERN Document Server

    Petrov, G M; Thomas, A G R; Krushelnick, K; Beg, F N

    2015-01-01

    Theoretical study of heavy ion acceleration from ultrathin (<200 nm) gold foils irradiated by a short pulse laser is presented. Using two dimensional particle-in-cell simulations the time history of the laser bullet is examined in order to get insight into the laser energy deposition and ion acceleration process. For laser pulses with intensity , duration 32 fs, focal spot size 5 mkm and energy 27 Joules the calculated reflection, transmission and coupling coefficients from a 20 nm foil are 80 %, 5 % and 15 %, respectively. The conversion efficiency into gold ions is 8 %. Two highly collimated counter-propagating ion beams have been identified. The forward accelerated gold ions have average and maximum charge-to-mass ratio of 0.25 and 0.3, respectively, maximum normalized energy 25 MeV/nucleon and flux . Analytical model was used to determine a range of foil thicknesses suitable for acceleration of gold ions in the Radiation Pressure Acceleration regime and the onset of the Target Normal Sheath Acceleratio...

  11. Analysis of selected fast critical assemblies

    International Nuclear Information System (INIS)

    Integral parameters for a series of fast reactor bench-mark assemblies covering a wide range of energy spectra have been calculated with the reference Cadarache Cross Section Library. Multigroup cross sections relative to each assembly were generated using the self-shielding factor approach and were used in a diffusion-cum-perturbation theory code to obtain the parameters. The parameters considered in this study include K-eff, spectral indices (reaction rate ratios), β-effs and central reactivity worths. Results of these calculations indicate that some of the important neutron cross section data need re-evaluation. (author)

  12. The pulsing CPSD method for subcritical assemblies with pulsed sources

    CERN Document Server

    Ballester, D; Ballester, Daniel; Munoz-Cobo, Jose L.

    2005-01-01

    Stochastic neutron transport theory is applied to the derivation of the two-neutron-detectors cross power spectral density for subcritical assemblies when external pulsed sources are used. A general relationship between the two-detector probability generating functions of the kernel and the source is obtained considering the contribution to detectors statistics of both the pulsed source and the intrinsic neutron source. An expansion in alpha-eigenvalues is derived for the final solution, which permits to take into account the effect of higher harmonics in subcritical systems. Further, expressions corresponding to the fundamental mode approximation are compared with recent results from experiments performed under the MUSE-4 European research project.

  13. PULSED-FOCUSING RECIRCULATING LINACS FOR MUON ACCELERATION

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Rolland PAUL

    2014-12-31

    Since the muon has a short lifetime, fast acceleration is essential for high-energy applications such as muon colliders, Higgs factories, or neutrino factories. The best one can do is to make a linear accelerator with the highest possible accelerating gradient to make the accelerating time as short as possible. However, the cost of such a single linear accelerator is prohibitively large due to expensive power sources, cavities, tunnels, and related infrastructure. As was demonstrated in the Thomas Jefferson Accelerator Facility (Jefferson Lab) Continuous Electron Beam Accelerator Facility (CEBAF), an elegant solution to reduce cost is to use magnetic return arcs to recirculate the beam through the accelerating RF cavities many times, where they gain energy on each pass. In such a Recirculating Linear Accelerator (RLA), the magnetic focusing strength diminishes as the beam energy increases in a conventional linac that has constant strength quadrupoles. After some number of passes the focusing strength is insufficient to keep the beam from going unstable and being lost. In this project, the use of fast pulsed quadrupoles in the linac sections was considered for stronger focusing as a function of time to allow more successive passes of a muon beam in a recirculating linear accelerator. In one simulation, it was shown that the number of passes could be increased from 8 to 12 using pulsed magnet designs that have been developed and tested. This could reduce the cost of linac sections of a muon RLA by 8/12, where more improvement is still possible. The expense of a greater number of passes and corresponding number of return arcs was also addressed in this project by exploring the use of ramped or FFAG-style magnets in the return arcs. A better solution, invented in this project, is to use combined-function dipole-quadrupole magnets to simultaneously transport two beams of different energies through one magnet string to reduce costs of return arcs by almost a factor of

  14. Pulse detonation assembly and hybrid engine

    Science.gov (United States)

    Rasheed, Adam (Inventor); Dean, Anthony John (Inventor); Vandervort, Christian Lee (Inventor)

    2010-01-01

    A pulse detonation (PD) assembly includes a number of PD chambers adapted to expel respective detonation product streams and a number of barriers disposed between respective pairs of PD chambers. The barriers define, at least in part, a number of sectors that contain at least one PD chamber. A hybrid engine includes a number of PD chambers and barriers. The hybrid engine further includes a turbine assembly having at least one turbine stage, being in flow communication with the PD chambers and being configured to be at least partially driven by the detonation product streams. A segmented hybrid engine includes a number of PD chambers and segments configured to receive and direct the detonation product streams from respective PD chambers. The segmented hybrid engine further includes a turbine assembly configured to be at least partially driven by the detonation product streams.

  15. Overview of LANL short-pulse ion acceleration activities

    Energy Technology Data Exchange (ETDEWEB)

    Flippo, Kirk A. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Schmitt, Mark J. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Offermann, Dustin [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Cobble, James A. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Gautier, Donald [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Kline, John [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Workman, Jonathan [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Archuleta, Fred [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Gonzales, Raymond [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Hurry, Thomas [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Johnson, Randall [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Letzring, Samuel [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Montgomery, David [Los Alamos National Laboratory; Reid, Sha-Marie [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Shimada, Tsutomu [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Gaillard, Sandrine A. [Univ. of Nevada, Reno, NV (United States); Sentoku, Yasuhiko [Univ. of Nevada, Reno, NV (United States); Bussman, Michael [Forschungszentrum Dresden (Germany); Kluge, Thomas [Forschungszentrum Dresden (Germany); Cowan, Thomas E. [Forschungszentrum Dresden (Germany); Rassuchine, Jenny M. [Forschungszentrum Dresden - Rossendorf (Germany); Lowenstern, Mario E. [Univ. of Michigan, Ann Arbor, MI (United States); Mucino, J. Eduardo [Univ. of Michigan, Ann Arbor, MI (United States); Gall, Brady [Univ. of Missouri, Columbia, MO (United States); Korgan, Grant [Nanolabz, Reno, NV (United States); Malekos, Steven [Nanolabz, Reno, NV (United States); Adams, Jesse [Nanolabz, Reno, NV (United States); Bartal, Teresa [Univ. of California, San Diego, CA (United States); Chawla, Surgreev [Univ. of California, San Diego, CA (United States); Higginson, Drew [Univ. of California, San Diego, CA (United States); Beg, Farhat [Univ. of California, San Diego, CA (United States); Nilson, Phil [Lab. for Laser Energetics, Rochester, NY (United States); Mac Phee, Andrew [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Le Pape, Sebastien [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Hey, Daniel [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Mac Kinnon, Andy [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Geissel, Mattias [Sandia National Lab. (SNL), Albuquerque, NM (United States); Schollmeier, Marius [Sandia National Lab. (SNL), Albuquerque, NM (United States); Stephens, Rich [General Atomics, San Diego, CA (United States)

    2009-12-02

    An overview of Los Alamos National Laboratory's activities related to short-pulse ion acceleration is presented. LANL is involved is several projects related to Inertial Confinement Fusion (Fast Ignition) and Laser-Ion Acceleration. LANL has an active high energy X-ray backlighter program for radiographing ICF implosions and other High Energy Density Laboratory Physics experiments. Using the Trident 200TW laser we are currently developing high energy photon (>10 keV) phase contrast imaging techniques to be applied on Omega and the NIF. In addition we are engaged in multiple programs in laser ion acceleration to boost the ion energies and efficiencies for various potential applications including Fast Ignition, active material interrogation, and medical applications. Two basic avenues to increase ion performance are currently under study: one involves ultra-thin targets and the other involves changing the target geometry. We have recently had success in boosting proton energies above 65 MeV into the medical application range. Highlights covered in the presentation include: The Trident Laser System; X-ray Phase Contrast Imaging for ICF and HEDLP; Improving TNSA Ion Acceleration; Scaling Laws; Flat Targets; Thin Targets; Cone Targets; Ion Focusing;Trident; Omega EP; Scaling Comparisons; and, Conclusions.

  16. Pulsed Electromagnetic Acceleration of Plasma: A Review

    Science.gov (United States)

    Thio, Y. C. Francis; Turchi, Peter J.; Markusic, Thomas E.; Cassibry, Jason T.; Sommer, James; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    Much have been learned in the acceleration mechanisms involved in accelerating a plasma electromagnetically in the laboratory over the last 40 years since the early review by Winston Bostik of 1963, but the accumulated understanding is very much scattered throughout the literature. This literature extends back at least to the early sixties and includes Rosenbluth's snowplow model, discussions by Ralph Lovberg, Colgate's boundary-layer model of a current sheet, many papers from the activity at Columbia by Robert Gross and his colleagues, and the relevant, 1-D unsteady descriptions developed from the U. of Maryland theta-pinch studies. Recent progress on the understanding of the pulsed penetration of magnetic fields into collisionless or nearly collisionless plasmas are also be reviewed. Somewhat more recently, we have the two-dimensional, unsteady results in the collisional regime associated with so-called wall-instability in large radius pinch discharges and also in coaxial plasma guns (e.g., Plasma Flow Switch). Among other things, for example, we have the phenomenon of a high- density plasma discharge propagating in a cooaxial gun as an apparently straight sheet (vs paraboloid) because mass re-distribution (on a microsecond timescale) compensates for the 1/r- squared variation of magnetic pressure. We will attempt to collate some of this vast material and bring some coherence tc the development of the subject.

  17. Fast cooldown coaxial pulse tube microcooler

    Science.gov (United States)

    Nast, T.; Olson, J. R.; Champagne, P.; Roth, E.; Kaldas, G.; Saito, E.; Loung, V.; McCay, B. S.; Kenton, A. C.; Dobbins, C. L.

    2016-05-01

    We report the development and initial testing of the Lockheed Martin first-article, single-stage, compact, coaxial, Fast Cooldown Pulse Tube Microcryocooler (FC-PTM). The new cryocooler supports cooling requirements for emerging large, high operating temperature (105-150K) infrared focal plane array sensors with nominal cooling loads of ~300 mW @105K @293K ambient. This is a sequel development that builds on our inline and coaxial pulse tube microcryocoolers reported at CEC 20137, ICC188,9, and CEC201510. The new FC-PTM and the prior units all share our long life space technology attributes, which typically have 10 year life requirements1. The new prototype microcryocooler builds on the previous development by incorporating cold head design improvements in two key areas: 1) reduced cool-down time and 2) novel repackaging that greatly reduces envelope. The new coldhead and Dewar were significantly redesigned from the earlier versions in order to achieve a cooldown time of 2-3 minutes-- a projected requirement for tactical applications. A design approach was devised to reduce the cold head length from 115mm to 55mm, while at the same time reducing cooldown time. We present new FC-PTM performance test measurements with comparisons to our previous pulse-tube microcryocooler measurements and design predictions. The FC-PTM exhibits attractive small size, volume, weight, power and cost (SWaP-C) features with sufficient cooling capacity over required ambient conditions that apply to an increasing variety of space and tactical applications.

  18. Relativistic electron accelerations associated with the interplanetary pressure pulse

    Science.gov (United States)

    Miyoshi, Yoshizumi; Saito, Shinji; Matsumoto, Yosuke; Hayashi, Masahiro; Amano, Takanobu; Seki, Kanako

    2016-04-01

    The radiation belt electron fluxes are highly variable, and various time scales for the flux enhancements are observed. The rapid flux enhancements of the outer belt electrons have been observed associated with the solar wind pressure pulse. In order to investigate such rapid flux enhancements, we conduct the code-coupling simulations of GEMSIS-RB test particle simulation [Saito et al., 2010] and GEMSIS-GM global MHD simulation [Matsumoto et al., 2010]. The GEMSIS-RB simulation calculates the 3-dimentional guiding-center motion of a number of test particles in the electric/magnetic fields provided from the GEMSIS-GM. After the arrival of the pressure pulse, the outer belt electrons in the dayside moves inward due to the drift resonance with inductive electric fields of the fast mode waves. Some of electrons are strongly accelerated within a few ten minutes and spiral patterns of drifted electrons can be observed. We may discuss the possibility to identify such selected acceleration of relativistic electrons by Van Allen Probes and upcoming ERG satellite.

  19. PROTO-II: a short pulse water insulated accelerator

    International Nuclear Information System (INIS)

    A new accelerator, designated Proto-II, is presently under construction at Sandia Laboratories. Proto-II will have a nominal output of 100 kJ into a two-sided diode at a voltage of 1.5 MV and a total current of over 6 MA for 24 ns. This accelerator will be utilized for electron beam fusion experiments and for pulsed power and developmental studies leading to a proposed further factor of five scale-up in power. The design of Proto-II is based upon recent water switching developments and represents a 10-fold extrapolation of those results. Initial testing of Proto-II is scheduled to begin in 1976. Proto-II power flow starts with eight Marx generators which charge 16 water-insulated storage capacitors. Eight triggered, 3 MV, SF6 gas-insulated switches next transfer the energy through oil-water interfaces into the first stage of 16 parallel lines. Next, the 16 first stages transfer their energy into the pulse forming lines and fast switching sections.The energy is then delivered to two converging, back-to-back, disk-shaped transmission line. Two back-to-back diodes then form the electron beams which are focused onto a common anode

  20. Pulsed power for particle beam accelerators in military applications

    International Nuclear Information System (INIS)

    Techniques useful for generating and conditioning power for high energy pulsed accelerators with potential weapon applications are described. Pulsed electron accelerators are exemplified by ETA and ATA at Lawrence Livermore Laboratories and RADLAC at Sandia Laboratories Albuquerque. Pulse-power techniques used in other applications are briefly mentioned, including some that may be useful for collective ion accelerators. The limitations of pulse-power and the general directions of desirable development are illustrated. The main needs are to increase repetition rate and to decrease size

  1. Scalable fast multipole accelerated vortex methods

    KAUST Repository

    Hu, Qi

    2014-05-01

    The fast multipole method (FMM) is often used to accelerate the calculation of particle interactions in particle-based methods to simulate incompressible flows. To evaluate the most time-consuming kernels - the Biot-Savart equation and stretching term of the vorticity equation, we mathematically reformulated it so that only two Laplace scalar potentials are used instead of six. This automatically ensuring divergence-free far-field computation. Based on this formulation, we developed a new FMM-based vortex method on heterogeneous architectures, which distributed the work between multicore CPUs and GPUs to best utilize the hardware resources and achieve excellent scalability. The algorithm uses new data structures which can dynamically manage inter-node communication and load balance efficiently, with only a small parallel construction overhead. This algorithm can scale to large-sized clusters showing both strong and weak scalability. Careful error and timing trade-off analysis are also performed for the cutoff functions induced by the vortex particle method. Our implementation can perform one time step of the velocity+stretching calculation for one billion particles on 32 nodes in 55.9 seconds, which yields 49.12 Tflop/s.

  2. Fast-acting calorimeter measures heat output of plasma gun accelerator

    Science.gov (United States)

    Dethlefson, R.; Larson, A. V.; Liebing, L.

    1967-01-01

    Calorimeter measures the exhaust energy from a shot of a pulsed plasma gun accelerator. It has a fast response time and requires only one measurement to determine the total energy. It uses a long ribbon of copper foil wound around a glass frame to form a reentrant cavity.

  3. Measurement of fast assembly spectra using time-of-flight method

    International Nuclear Information System (INIS)

    Measurement of neutron spectra made in fast subcritical assemblies HUG 3 and PHUG 3 (uranium-graphite and plutonium-graphite) utilizing time-of-flight techniques are described. The matrix were excited by the pulsed neutron source from the BCMN Linac beam impinging on a target of natural uranium. Details of the experimental procedure, safety studies, detector calibration and data reduction are given

  4. E-field measurement of a pulse line ion accelerator

    Institute of Scientific and Technical Information of China (English)

    WANG Bo; ZENG Rong; NIU Ben; SHEN Xiao-Li; SHEN Xiao-Kang; CAO Shu-Chun; ZHANG Zi-Min

    2013-01-01

    The E-field of pulse line ion accelerator (PLIA) is unique with high frequency (~MHz),large magnitude (~MV/m),and limited measuring space (~cm).The integrated optical E-field sensor (IOES) has remarkable advantages and has been used for PLIA E-field measurement.Firstly,the transfer function of the IOES has been calibrated to ensure measurement accuracy.The time-domain response illustrates that the sensor has a fast dynamic performance to effectively follow a 4 ns rising edge.Then,the E-field distribution along the axis and near the insulator surface of the PLIA was measured,showing that propagation of the E-field is almost lossless and the E-field near the insulation surface is about 1.1 times larger than that along the axis,which is in accordance with the simulation result.

  5. Experimental Research of Fast Proton Generation From Ultra-short Intense Laser Pulses Interaction With Different Thickness Al Foils

    Institute of Scientific and Technical Information of China (English)

    LAN; Xiao-fei; LU; Jian-xin; HUANG; Yong-sheng; WANG; Lei-jian; XI; Xiao-feng; TANG; Xiu-zhang

    2012-01-01

    <正>With the development of laser technology, the generation of fast ions by the interaction of ultra-short ultra-intense laser pulses with matters has recently been attracting considerable attention, especially for acceleration of proton. Before performing experiment, we calibrated the CR39 detector using standard proton beams from conventional accelerator. In the field of proton acceleration driven by ultra-short ultra-intense laser pulses,

  6. Fast magnetic field annihilation driven by two laser pulses in underdense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Y. J.; Kumar, D.; Weber, S.; Korn, G. [Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); Klimo, O. [Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); FNSPE, Czech Technical University in Prague, 11519 Prague (Czech Republic); Bulanov, S. V.; Esirkepov, T. Zh. [Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa-shi, Kyoto 619-0215 (Japan)

    2015-10-15

    Fast magnetic annihilation is investigated by using 2.5-dimensional particle-in-cell simulations of two parallel ultra-short petawatt laser pulses co-propagating in underdense plasma. The magnetic field generated by the laser pulses annihilates in a current sheet formed between the pulses. Magnetic field energy is converted to an inductive longitudinal electric field, which efficiently accelerates the electrons of the current sheet. This new regime of collisionless relativistic magnetic field annihilation with a timescale of tens of femtoseconds can be extended to near-critical and overdense plasma with the ultra-high intensity femtosecond laser pulses.

  7. Flexible Assembly Solar Technology (FAST) Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Toister, Elad [BrightSource Energy Inc., Jerusalem (Israel)

    2014-11-06

    The Flexible Assembly Solar Technology (FAST) project was initiated by BrightSource in an attempt to provide potential solar field EPC contractors with an effective set of tools to perform specific construction tasks. These tasks are mostly associated with heliostat assembly and installation, and require customized non-standard tools. The FAST concept focuses on low equipment cost, reduced setup time and increased assembly throughput as compared to the Ivanpah solar field construction tools.

  8. Hydraulic Experiment for Simulative Assemblies of Blanket Assembly and Np Transmutation Assembly of China Experimental Fast Reactor

    Institute of Scientific and Technical Information of China (English)

    CHENG; Dao-xi; QI; Xiao-guang; ZHAI; Wei-ming; YANG; Bing; ZHOU; Ping

    2013-01-01

    The out-of reactor hydraulic experiment of fast reactor assembly is one of the important experiments in the process of the development of the fast reactor assembly.In this experiment,the size of the throttling element in the foot of the assembly is decided which is fit for the flow division in the reactor and the

  9. Colliding Laser Pulses for Laser-Plasma Accelerator Injection Control

    Energy Technology Data Exchange (ETDEWEB)

    Plateau, Guillaume; Geddes, Cameron; Matlis, Nicholas; Cormier-Michel, Estelle; Mittelberger, Daniel; Nakamura, Kei; Schroeder, Carl; Esarey, Eric; Leemans, Wim

    2011-07-19

    Decoupling injection from acceleration is a key challenge to achieve compact, reliable, tunable laser-plasma accelerators (LPA). In colliding pulse injection the beat between multiple laser pulses can be used to control energy, energy spread, and emittance of the electron beam by injecting electrons in momentum and phase into the accelerating phase of the wake trailing the driver laser pulse. At LBNL, using automated control of spatiotemporal overlap of laser pulses, two-pulse experiments showed stable operation and reproducibility over hours of operation. Arrival time of the colliding beam was scanned, and the measured timing window and density of optimal operation agree with simulations. The accelerator length was mapped by scanning the collision point.

  10. Minimus: a fast, lightweight genome assembler

    Directory of Open Access Journals (Sweden)

    Salzberg Steven L

    2007-02-01

    Full Text Available Abstract Background Genome assemblers have grown very large and complex in response to the need for algorithms to handle the challenges of large whole-genome sequencing projects. Many of the most common uses of assemblers, however, are best served by a simpler type of assembler that requires fewer software components, uses less memory, and is far easier to install and run. Results We have developed the Minimus assembler to address these issues, and tested it on a range of assembly problems. We show that Minimus performs well on several small assembly tasks, including the assembly of viral genomes, individual genes, and BAC clones. In addition, we evaluate Minimus' performance in assembling bacterial genomes in order to assess its suitability as a component of a larger assembly pipeline. We show that, unlike other software currently used for these tasks, Minimus produces significantly fewer assembly errors, at the cost of generating a more fragmented assembly. Conclusion We find that for small genomes and other small assembly tasks, Minimus is faster and far more flexible than existing tools. Due to its small size and modular design Minimus is perfectly suited to be a component of complex assembly pipelines. Minimus is released as an open-source software project and the code is available as part of the AMOS project at Sourceforge.

  11. Two-pulse injector experiments with the RIIM electron accelerator

    International Nuclear Information System (INIS)

    The RADLAC-II accelerator foilless diode injector was operated under double-pulse conditions utilizing the RIIM accelerator as the test bed [M. G. Mazarakis, D. L. Smith, R. B. Miller, R. S. Clark, D. E. Hasti, D. L. Johnson, J. W. Poukey, K. R. Prestwich, and S. L. Shope, IEEE Trans. Nucl. Sci. NS-32, 3237 (1985)]. The original RIIM accelerator pulsed-power network was modified to provide for the generation, transmission, and delivery to the foilless diode of two distinct multimegavolt pulses with variable interpulse separation from 0 to 2 ms. The foilless diode successfully produced two 10-kA current pulses with interpulse separations up to 1 μs. For larger separations, the generated plasma and an excessive neutral gas release following the first pulse prevented the diode from producing a second current pulse

  12. Trapping of Hepatitis B Virus capsid assembly intermediates by phenylpropenamide assembly accelerators

    OpenAIRE

    Katen, Sarah P.; Chirapu, Srinivas Reddy; Finn, M.G.; Zlotnick, Adam

    2010-01-01

    Understanding the biological self-assembly process of virus capsids is key to understanding the viral life cycle, as well as serving as a platform for the design of assembly-based antiviral drugs. Here we identify and characterize the phenylpropenamide family of small molecules, known to have antiviral activity in vivo, as assembly effectors of the Hepatitis B Virus (HBV) capsid. We have found two representative phenylpropenamides to be assembly accelerators, increasing the rate of assembly w...

  13. Method for pulse to pulse dose reproducibility applied to electron linear accelerators

    International Nuclear Information System (INIS)

    An original method for obtaining programmed beam single shots and pulse trains with programmed pulse number, pulse repetition frequency, pulse duration and pulse dose is presented. It is particularly useful for automatic control of absorbed dose rate level, irradiation process control as well as in pulse radiolysis studies, single pulse dose measurement or for research experiments where pulse-to-pulse dose reproducibility is required. This method is applied to the electron linear accelerators, ALIN-10 of 6.23 MeV and 82 W and ALID-7, of 5.5 MeV and 670 W, built in NILPRP. In order to implement this method, the accelerator triggering system (ATS) consists of two branches: the gun branch and the magnetron branch. ATS, which synchronizes all the system units, delivers trigger pulses at a programmed repetition rate (up to 250 pulses/s) to the gun (80 kV, 10 A and 4 ms) and magnetron (45 kV, 100 A, and 4 ms).The accelerated electron beam existence is determined by the electron gun and magnetron pulses overlapping. The method consists in controlling the overlapping of pulses in order to deliver the beam in the desired sequence. This control is implemented by a discrete pulse position modulation of gun and/or magnetron pulses. The instabilities of the gun and magnetron transient regimes are avoided by operating the accelerator with no accelerated beam for a certain time. At the operator 'beam start' command, the ATS controls electron gun and magnetron pulses overlapping and the linac beam is generated. The pulse-to-pulse absorbed dose variation is thus considerably reduced. Programmed absorbed dose, irradiation time, beam pulse number or other external events may interrupt the coincidence between the gun and magnetron pulses. Slow absorbed dose variation is compensated by the control of the pulse duration and repetition frequency. Two methods are reported in the electron linear accelerators' development for obtaining the pulse to pulse dose reproducibility: the method

  14. Fast Heat Pulse Propagation by Turbulence Spreading

    DEFF Research Database (Denmark)

    Naulin, Volker; Juul Rasmussen, Jens; Mantica, Paola;

    2009-01-01

    The propagation of a cold pulse initiated by edge cooling in JET is compared to propagation of the heat wave originating from a modulation of the heating source roughly at mid radius. It is found that the propagation of the cold pulse is by far faster than what could be predicted on the basis of ...

  15. A 7MeV S-Band 2998MHz Variable Pulse Length Linear Accelerator System

    CERN Document Server

    Hernandez, Michael; Mishin, Andrey V; Saverskiy, Aleksandr J; Skowbo, Dave; Smith, Richard

    2005-01-01

    American Science and Engineering High Energy Systems Division (AS&E HESD) has designed and commissioned a variable pulse length 7 MeV electron accelerator system. The system is capable of delivering a 7 MeV electron beam with a pulse length of 10 nS FWHM and a peak current of 1 ampere. The system can also produce electron pulses with lengths of 20, 50, 100, 200, 400 nS and 3 uS FWHM with corresponding lower peak currents. The accelerator system consists of a gridded electron gun, focusing coil, an electrostatic deflector system, Helmholtz coils, a standing wave side coupled S-band linac, a 2.6 MW peak power magnetron, an RF circulator, a fast toroid, vacuum system and a PLC/PC control system. The system has been operated at repetition rates up to 250pps. The design, simulations and experimental results from the accelerator system are presented in this paper.

  16. Multistage linear electron acceleration using pulsed transmission lines

    International Nuclear Information System (INIS)

    A four-stage linear electron accelerator is described which uses pulsed radial transmission lines as the basic accelerating units. An annular electron beam produced by a foilless diode is guided through the accelerator by a strong axial magnetic field. Synchronous firing of the injector and the acccelerating modules is accomplished with self-breaking oil switches. The device has accelerated beam currents of 25 kA to kinetic energies of 9 MV, with 90% current transport efficiency. The average accelerating gradient is 3 MV/m

  17. Generation of laser pulse trains for tests of multi-pulse laser wakefield acceleration

    Science.gov (United States)

    Shalloo, R. J.; Corner, L.; Arran, C.; Cowley, J.; Cheung, G.; Thornton, C.; Walczak, R.; Hooker, S. M.

    2016-09-01

    In multi-pulse laser wakefield acceleration (MP-LWFA) a plasma wave is driven by a train of low-energy laser pulses separated by the plasma period, an approach which offers a route to driving plasma accelerators with high efficiency and at high pulse repetition rates using emerging technologies such as fibre and thin-disk lasers. Whilst these laser technologies are in development, proof-of-principle tests of MP-LWFA require a pulse train to be generated from a single, high-energy ultrafast pulse. Here we demonstrate the generation of trains of up to 7 pulses with pulse separations in the range 150-170 fs from single 40 fs pulses produced by a Ti:sapphire laser.

  18. Linear induction accelerators made from pulse-line cavities with external pulse injection

    International Nuclear Information System (INIS)

    Two types of linear induction accelerator have been reported previously. In one, unidirectional voltage pulses are generated outside the accelerator and injected into the accelerator cavity modules, which contain ferromagnetic material to reduce energy losses in the form of currents induced, in parallel with the beam, in the cavity structure. In the other type, the accelerator cavity modules are themselves pulse-forming lines with energy storage and switches; parallel current losses are made zero by the use of circuits that generate bidirectional acceleration waveforms with a zero voltage-time integral. In a third type of design described here, the cavities are externally driven, and 100% efficient coupling of energy to the beam is obtained by designing the external pulse generators to produce bidirectional voltage waveforms with zero voltage-time integral. A design for such a pulse generator is described that is itself one hundred percent efficient and which is well suited to existing pulse power techniques. Two accelerator cavity designs are described that can couple the pulse from such a generator to the beam; one of these designs provides voltage doubling. Comparison is made between the accelerating gradients that can be obtained with this and the preceding types of induction accelerator

  19. Current pulse generator of an induction accelerator electromagnet

    International Nuclear Information System (INIS)

    Thyristor generator forming in betatron electromagnet coil sinusoidal and quasisinusoidal current unipolar pulses, the field being deforced at the beginning of acceleration cycle, and with the pulse flat top in the cycle end, is described. The current amplitude is controlled by pulse-phase method. The current pulse time shift permitted to decrease the loss rate in the accumulating capacitor. The generator is used in systems with 1-10 ms pulse duration, electromagnet magnetic field maximal energy - 45-450 J, the voltage amplitude in the coil 960-1500 V and amplitude of the current passing the coil 100-500 A, the repetition frequency being 50-200 Hz. In particular, the generator is used to supply betatrons designed for defectoscopy in nonstationary conditions, the accelerated electron energy being 4, 6, 8 and 15 MeV

  20. Current-pulse generator for electromagnet of induction accelerator

    International Nuclear Information System (INIS)

    A thyristor generator is described that produces in the winding of the electromagnet of a betatron unipolar current pulses of sinusoidal and quasisinusoidal shape with deforcing of the field at the beginning of an acceleration cycle and with a plateau on the pulse top at the end of a cycle. The current amplitude is controlled by a pulse-phase method. The generator is used in apparatus with a pulse duration of 1-10 msec, a maximum electromagnet field energy 45-450 J, a winding voltage of 960-1500 V, and a winding current of 100-500 A for a repetition frequency of 50-200 Hz

  1. Chirped pulse inverse free-electron laser vacuum accelerator

    Science.gov (United States)

    Hartemann, Frederic V.; Baldis, Hector A.; Landahl, Eric C.

    2002-01-01

    A chirped pulse inverse free-electron laser (IFEL) vacuum accelerator for high gradient laser acceleration in vacuum. By the use of an ultrashort (femtosecond), ultrahigh intensity chirped laser pulse both the IFEL interaction bandwidth and accelerating gradient are increased, thus yielding large gains in a compact system. In addition, the IFEL resonance condition can be maintained throughout the interaction region by using a chirped drive laser wave. In addition, diffraction can be alleviated by taking advantage of the laser optical bandwidth with negative dispersion focusing optics to produce a chromatic line focus. The combination of these features results in a compact, efficient vacuum laser accelerator which finds many applications including high energy physics, compact table-top laser accelerator for medical imaging and therapy, material science, and basic physics.

  2. Ultra fast imaging of a laser wake field accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Saevert, Alexander; Schnell, Michael; Nicolai, Maria; Reuter, Maria; Schwab, Matthew B.; Moeller, Max [Friedrich-Schiller-Universitaet, Jena (Germany); Mangles, Stuart P.D.; Cole, Jason M.; Poder, Kristjan; Najmudin, Zulfikar [The John Adams Institute Imperial College, London (United Kingdom); Jaeckel, Oliver; Paulus, Gerhard G.; Spielmann, Christian; Kaluza, Malte C. [Friedrich-Schiller-Universitaet, Jena (Germany); Helmholtz Institut Jena, Jena (Germany)

    2014-07-01

    Ultra intense laser pulses are known to excite plasma waves with a relativistic phase velocity. By harnessing these waves it is possible to generate quasi-monoenergetic, ultra-short electron pulses with kinetic energies from 0.1 to 2 GeV by guiding the laser pulse over several Rayleigh lengths. To further improve the stability of these particle pulses and ultimately to be able to tailor the energy spectrum toward their suitability for various applications, the physics underlying the different acceleration scenarios need to be understood as completely as possible. To be able to resolve the acceleration process diagnostics well-suited for this plasma environment need to be designed and realized. By using sub-10 fs probe pulses we were able to freeze the transient accelerating structure in the plasma. We will present the first results of an experiment which was carried out with the 30 TW JETi Laser and a few cycle probe pulse at the Institute of Optics and Quantum Electronics Jena. The resulting snapshots show unprecedented details from the laser plasma interaction and allow a direct comparison to computer simulations.

  3. Development of a fast voltage control method for electrostatic accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Lobanov, Nikolai R.; Linardakis, Peter; Tsifakis, Dimitrios

    2014-12-11

    The concept of a novel fast voltage control loop for tandem electrostatic accelerators is described. This control loop utilises high-frequency components of the ion beam current intercepted by the image slits to generate a correction voltage that is applied to the first few gaps of the low- and high-energy acceleration tubes adjoining the high voltage terminal. New techniques for the direct measurement of the transfer function of an ultra-high impedance structure, such as an electrostatic accelerator, have been developed. For the first time, the transfer function for the fast feedback loop has been measured directly. Slow voltage variations are stabilised with common corona control loop and the relationship between transfer functions for the slow and new fast control loops required for optimum operation is discussed. The main source of terminal voltage instabilities, which are due to variation of the charging current caused by mechanical oscillations of charging chains, has been analysed.

  4. Nanosecond pulse-width electron diode based on dielectric wall accelerator technology

    Science.gov (United States)

    Zhao, Quantang; Zhang, Z. M.; Yuan, P.; Cao, S. C.; Shen, X. K.; Jing, Y.; Yu, C. S.; Li, Z. P.; Liu, M.; Xiao, R. Q.; Zong, Y.; Wang, Y. R.; Zhao, H. W.

    2013-11-01

    An electron diode using a short section of dielectric wall accelerator (DWA) has been under development at the Institute of Modern Physics (IMP), Chinese Academy of Sciences. Tests have been carried out with spark gap switches triggered by lasers. The stack voltage efficiency of a four-layer of Blumleins reached about 60-70% with gas filled spark gap switching. The generated pulse voltage of peak amplitude of 23 kV and pulse width of 5 ns is used to extract and accelerate an electron beam of 320 mA, measured by a fast current transformer. A nanosecond pulse width electron diode was achieved successfully. Furthermore, the principle of a DWA is well proven and the development details and discussions are presented in this article.

  5. Linear induction accelerator and pulse forming networks therefor

    Science.gov (United States)

    Buttram, Malcolm T.; Ginn, Jerry W.

    1989-01-01

    A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities.

  6. Pulsed magnetic field for PHERMEX-injected circular accelerator

    International Nuclear Information System (INIS)

    The PHERMEX accelerator is a standing wave, 50 MHz rf linear accelerator. The rf fields in three cavities are pulsed for a period of 3 ms. The experiments described are directed toward studying injection and trapping of electron rings at modes field strengths (approximately 1 T). A single 200 ns beam macropulse is to be injected transverse to a solenoidal field, which is tilted at a small angle relative to the beam normal so that a beam micropulse does not return and strike the injection point. The pulsed field coils and vacuum chamber are reported under construction, and the capacitor bank being tested

  7. Injection and acceleration system of pulsed racetrack microtron

    CERN Document Server

    Ermakov, A N; Ishkhanov, B S

    2002-01-01

    Paper describes a pulsed racetrack microtron (RM) with 70 MeV beam maximal power. For this project one designed rare-earth permanent magnet base bending magnets, pattern to inject a bunched electron bean through a compact alpha-magnet and prismatic biperiodic accelerating structure (PBAS) characterized by compact transverse dimensions ensuring bar-free passing of electron beam through the first orbit. Besides, the PBAS has a high-frequency quadrupole focusing. These features facilitate essentially RM design and adjustment. Paper describes tests, technique of adjustment and of measuring of systems to inject and to accelerate a pulsed racetrack microtron

  8. Long-pulse induction acceleration of heavy ions

    International Nuclear Information System (INIS)

    A long-pulse induction acceleration unit has been installed in the high-current Cs+ beam line at LBL and has accelerated heavy ions. A maximum energy gain of 250 keV for 1.5 μs is possible. The unit comprises 12 independent modules which may be used to synthesize a variety of waveforms by varying the triggering times of the low voltage trigger generators

  9. Klystron pulse modulator of linear electron accelerator: test results

    Directory of Open Access Journals (Sweden)

    Z. Zimek

    2009-12-01

    Full Text Available Purpose: The purpose of the paper is to describe Klystron pulse modulator of linear electron accelerator.Design/methodology/approach: TH-2158 klystron modulator experimental model is based on semiconductor switch HTS 181-160 FI (acceptable current load 1600 A, and voltage up to 18 kV. The results of test measurements carried out during modulator starting up period are presented in this work. TH-2158 klystron was used as a load. The klystron was connected to the second winding of the pulse HV transformer with 1:10 windings turn ratio. The examined modulator is equipped with safety shutdown circuitry for protection against current overload that may appear at IGBT switch in the case of short-circuiting happened in klystron and waveguide system.Findings: Linear electron accelerator type LAE 10/15 with electron energy 10 MeV and beam power up to 15 kW was designed and completed at Institute of Nuclear Chemistry and Technology. This accelerator was installed in facility for radiation sterilization single use medical devices, implants and tissue grafts. The standing wave accelerating section was selected. Microwave energy used for accelerating process is provided by klystron type TH-2158 working at frequency 2856 MHz.Practical implications: Described HV pulse modulator which designed and constructed for klystron TH-2158 was preliminary tested to evaluate the quality of the klystron HV and load current pulses and optimized selected component parameters. Obtained experimental results are better than those which were predicted by computer simulation method.Originality/value: Description of Klystron pulse modulator of linear electron accelerator.

  10. TOWARDS FAST-PULSED SUPERCONDUCTING SYNCHROTRON MAGNETS.

    Energy Technology Data Exchange (ETDEWEB)

    MORITZ,G.; MUEHLE,C.; ANERELLA,M.; GHOSH,A.; SAMPSON,W.; WANDERER,P.; WILLEN,E.; AGAPOV,N.; KHODZHIBAGIYAN,H.; KOVALENKO,A.; HASSENZAHL,W.V.; WILSON,M.N.

    2001-06-18

    The concept for the new GSI accelerator facilities is based on a large synchrotron designed for operation at BR=200 Tm and with the short cycle-time of about one second to achieve high average beam intensities. Superconducting magnets may reduce considerably investment and operating costs in comparison with conventional magnets. A R and D program was initiated to develop these magnets for a maximum field of 2-4 Tesla and a ramp rate of 4 T/s. In collaboration with JINR (Dubna), the window-frame type Nuclotron dipole, which has been operated with 4 T/s at a maximum field of 2 Tesla, shall be developed to reduce heat losses and to improve the magnetic field quality. Another collaboration with BNL (Brookhaven) was established to develop the one-layer-coil cos{theta}-type RHIC arc dipole designed for operation at 3.5 Tesla with a rather slow ramp-rate of 0.07 T/s towards the design ramp-rate of 4 T/s. The design concepts for both R and D programs are reported.

  11. Ion acceleration with ultra intense and ultra short laser pulses

    International Nuclear Information System (INIS)

    Accelerating ions/protons can be done using short laser pulse (few femto-seconds) focused on few micrometers area on solid target (carbon, aluminum, plastic...). The electromagnetic field intensity reached on target (≥1018 W.cm-2) allows us to turn the solid into a hot dense plasma. The dynamic motion of the electrons is responsible for the creation of intense static electric field at the plasma boundaries. These electric fields accelerate organic pollutants (including protons) located at the boundaries. This acceleration mechanism known as the Target Normal Sheath Acceleration (TNSA) has been the topic of the research presented in this thesis.The goal of this work has been to study the acceleration mechanism and to increase the maximal ion energy achievable. Indeed, societal application such as proton therapy requires proton energy up to few hundreds of MeV. To proceed, we have studied different target configurations allowing us to increase the laser plasma coupling and to transfer as much energy as possible to ions (target with microspheres deposit, foam target, grating). Different experiments have also dealt with generating a pre-plasma on the target surface thanks to a pre-pulse. On the application side, fluorescent material such as CdWO4 has been studied under high flux rate of protons. These high flux rates have been, up to now, beyond the conventional accelerators capabilities. (author)

  12. Effect of plasma inhomogeneity on ion acceleration when an ultra-intense laser pulse interacts with a foil target

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, A.A.; Platonov, K.Yu. [Institute for Laser Physics, SC Vavilov State Optical Institute, St. Petersburg (Russian Federation); Zhidkov, A.G. [University of Tokyo, Graduate School of Engineering, Nuclear Engineering Research Laboratory, Tokai, Naka, Ibaraki (Japan); Sasaki, A. [Advanced Photon Research Center JAERI, Kizu-cho, Soraku-gun, Kyoto (Japan)

    2002-07-01

    Fast electrons generated via the interaction of ultra-intense laser pulses with a solid target can produce multi-MeV ions from laser-induced plasmas. These fast ions can be used for various applications ranging from the ion implantation to the stimulation of nuclear reactions. The most important point here is the efficiency of production of such fast ions. We analyse in detail, with the help of an analytical model and particle-in-cell simulations, the most efficient acceleration mechanisms including the ponderomotive force driving and acceleration by the shock wave, and compare the electrostatic ion acceleration at the front side and at the rear side of a foil target. We also determine the optimal plasma density distribution shaped by the laser pre-pulse. (author)

  13. Repetitive pulse accelerator technology for light ion inertial confinement fusion

    International Nuclear Information System (INIS)

    This paper will overview the technologies being studied for a repetitively pulsed ICF accelerator. As presently conceived, power is supplied by rotating machinery providing 16 MJ in 1 ms. The generator output is transformed to 3 MV, then switched into a pulse compression system using laser triggered spark gaps. These must be synchronized to about 1 ns. Pulse compression is performed with saturable inductor switches, the output being 40 ns, 1.5 MV pulses. These are transformed to 30 MV in a self-magnetically insulated cavity adder structure. Space charge limited ion beams are drawn from anode plasmas with electron counter streaming being magnetically inhibited. The ions are ballistically focused into the entrances of guiding discharge channels for transport to the pellet. The status of component development from the prime power to the ion source will be reviewed

  14. SUAK, a Fast Subcritical Facility for Pulsed Neutron Measurements

    International Nuclear Information System (INIS)

    SUAK is a small unreflected unmoderated assembly fuelled with 20% enriched uranium. The fuel is in the form of thin plates of 2 in x 2 in x 1/B in which are held in square tubes. The tubes are closely packed together, so that assemblies of different size and composition can be realized. The maximum size is a cube of about 35-cm side length. The maximum value of keff is 0.90. To reduce the backscattering of neutrons the assembly is located in the centre of a thin-walled building surrounded at a distance of 25 m by a wall for radiation protection. The control room is embedded in this wall. With a 200-keV pulsed neutron generator, measurements of the prompt neutron decay with different detectors and measurements of spectra by the time-of-flight technique are performed. A description of the assembly is given. First preliminary results are presented and compared with calculations. (author)

  15. Material acceleration estimation by four-pulse tomo-PIV

    Science.gov (United States)

    Lynch, K. P.; Scarano, F.

    2014-08-01

    A tomographic PIV system is introduced for the instantaneous measurement of the material acceleration (material derivative of velocity). The system is conceived to operate with short temporal separation (microseconds) and is therefore suitable for applications up to the high-speed flow regimes. The method of operation consists of tomographic imaging of a measurement volume using three arrays of four CCD cameras and two double-pulse laser systems. Advantages and shortcomings of the approach with respect to the most commonly used method based on light polarization are discussed. Various approaches are compared to determine the optimal utilization of four-pulse data to measure the material acceleration: Eulerian and Lagrangian schemes are compared to the recently introduced fluid trajectory correlation (FTC) technique from the authors. A synthetic image test case of a translating vortex is used to compare the schemes with and without the presence of noise. The truncation errors and sensitivity to random noise for each scheme are highlighted. A discussion is also given on the dynamic range of the schemes. The four-pulse tomographic system is used to measure the separated wake of an axisymmetric truncated base with afterbody at a Reynolds number of 68 000. The system calibration accuracy and the baseline measurement uncertainty of the velocity are evaluated with a zero-time delay test. A novel criterion is introduced to establish the relative accuracy of the material derivative measurement, based on the curl of the material acceleration field. The results indicate that the four-pulse tomo-PIV approach suits the measurement of the material acceleration using a variety of estimation schemes. In particular, the FTC technique gives the lowest error levels and is well-suited to perform accurate material acceleration measurements.

  16. Fast track surgery accelerates the recovery of postoperative insulin sensitivity

    Institute of Scientific and Technical Information of China (English)

    YANG Dong-jie; ZHANG Chang-hua; HE Yu-long; ZHANG Sheng; HE Wei-ling; CHEN Hua-yun; CAI Shi-rong; CHEN Chuang-qi; SONG Xin-ming; CUI Ji; MA Jin-ping

    2012-01-01

    Background Few clinical studies or randomized clinical trial results have reported the impact of fast track surgery on postoperative insulin sensitivity.This study aimed to investigate the effects of fast track surgery on postoperative insulin sensitivity in patients undergoing elective open colorectal resection.Methods Controlled,randomized clinical trial was conducted from November 2008 to January 2009 with one-month post-discharge follow-up.Seventy patients with colorectal carcinoma requiring colorectal resection were randomized into two groups:a fast track group (35 cases) and a conventional care group (35 cases).All included patients received elective open colorectal resection with combined tracheal intubation and general anesthesia.Clinical parameters (complication rates,return of gastrointestinal function and postoperative length of stay),stress index and insulin sensitivity were evaluated in both groups perioperatively.Reaults Sixty-two patients finally completed the study,32 cases in the fast-track group and 30 cases in the conventional care group.Our findings revealed a significantly faster recovery of postoperative insulin sensitivity on postoperative day 7 in the fast-track group than that in the conventional care group.We also found a significantly shorter length of postoperative stay and a significantly faster return of gastrointestinal function in patients undergoing fast-track rehabilitation.Conclusion Fast track surgery accelerates the recovery of postoperative insulin sensitivity in elective surgery for colorectal carcinoma with a shorter length of postoperative hospital stay.

  17. Development of high power toroidal pulse transformer with 10-100 Hz repetition rate for linear induction accelerator

    International Nuclear Information System (INIS)

    Full text: An amorphous-core pulse transformer of 2.5kV /20kV, 20μs, 250J, 100 pps rating has been designed and fabricated for Linear Induction Accelerator. This accelerator will be used to generate intense electron beam pulses at high repetition rate for plastic modification and other material processing applications. The peak power and average power of the pulse transformer are 20MW and 25kW respectively. Modular design based on parallel operation of 6 identical modules has been incorporated in this pulse transformer. Single module has been tested up to 10pps for 10 minute durations. Full transformer assembly has been tested in single pulse mode

  18. Assembly Test of Elastic Averaging Technique to Improve Mechanical Alignment for Accelerating Structure Assemblies in CLIC

    CERN Document Server

    Huopana, J

    2010-01-01

    The CLIC (Compact LInear Collider) is being studied at CERN as a potential multi-TeV e+e- collider [1]. The manufacturing and assembly tolerances for the required RF-components are important for the final efficiency and for the operation of CLIC. The proper function of an accelerating structure is very sensitive to errors in shape and location of the accelerating cavity. This causes considerable issues in the field of mechanical design and manufacturing. Currently the design of the accelerating structures is a disk design. Alternatively it is possible to create the accelerating assembly from quadrants, which favour the mass manufacturing. The functional shape inside of the accelerating structure remains the same and a single assembly uses less parts. The alignment of these quadrants has been previously made kinematic by using steel pins or spheres to align the pieces together. This method proved to be a quite tedious and time consuming method of assembly. To limit the number of different error sources, a meth...

  19. Cyclinac medical accelerators using pulsed C6+/H2+ ion sources

    International Nuclear Information System (INIS)

    Charged particle therapy, or so-called hadrontherapy, is developing very rapidly. There is large pressure on the scientific community to deliver dedicated accelerators, providing the best possible treatment modalities at the lowest cost. In this context, the Italian research Foundation TERA is developing fast-cycling accelerators, dubbed 'cyclinacs'. These are a combination of a cyclotron (accelerating ions to a fixed initial energy) followed by a high gradient linac boosting the ions energy up to the maximum needed for medical therapy. The linac is powered by many independently controlled klystrons to vary the beam energy from one pulse to the next. This accelerator is best suited to treat moving organs with a 4D multipainting spot scanning technique. A dual proton/carbon ion cyclinac is here presented. It consists of an Electron Beam Ion Source, a superconducting isochronous cyclotron and a high-gradient linac. All these machines are pulsed at high repetition rate (100-400 Hz). The source should deliver both C6+ and H2+ ions in short pulses (1.5 μs flat-top) and with sufficient intensity (at least 108 fully stripped carbon ions per pulse at 300 Hz). The cyclotron accelerates the ions to 120 MeV/u. It features a compact design (with superconducting coils) and a low power consumption. The linac has a novel C-band high-gradient structure and accelerates the ions to variable energies up to 400 MeV/u. High RF frequencies lead to power consumptions which are much lower than the ones of synchrotrons for the same ion extraction energy. This work is part of a collaboration with the CLIC group, which is working at CERN on high-gradient electron-positron colliders.

  20. Fast initial continuous current pulses versus return stroke pulses in tower-initiated lightning

    Science.gov (United States)

    Azadifar, Mohammad; Rachidi, Farhad; Rubinstein, Marcos; Rakov, Vladimir A.; Paolone, Mario; Pavanello, Davide; Metz, Stefan

    2016-06-01

    We present a study focused on pulses superimposed on the initial continuous current of upward negative discharges. The study is based on experimental data consisting of correlated lightning current waveforms recorded at the instrumented Säntis Tower in Switzerland and electric fields recorded at a distance of 14.7 km from the tower. Two different types of pulses superimposed on the initial continuous current were identified: (1) M-component-type pulses, for which the microsecond-scale electric field pulse occurs significantly earlier than the onset of the current pulse, and (2) fast pulses, for which the onset of the field matches that of the current pulse. We analyze the currents and fields associated with these fast pulses (return-stroke type (RS-type) initial continuous current (ICC) pulses) and compare their characteristics with those of return strokes. A total of nine flashes containing 44 RS-type ICC pulses and 24 return strokes were analyzed. The median current peaks associated with RS-type ICC pulses and return strokes are, respectively, 3.4 kA and 8 kA. The associated median E-field peaks normalized to 100 km are 1.5 V/m and 4.4 V/m, respectively. On the other hand, the electric field peaks versus current peaks for the two data sets (RS-type ICC pulses and return strokes) are characterized by very similar linear regression slopes, namely, 3.67 V/(m kA) for the ICC pulses and 3.77 V/(m kA) for the return strokes. Assuming the field-current relation based on the transmission line model, we estimated the apparent speed of both the RS-type ICC pulses and return strokes to be about 1.4 × 108 m/s. A strong linear correlation is observed between the E-field risetime and the current risetime for the ICC pulses, similar to the relation observed between the E-field risetime and current risetime for return strokes. The similarity of the RS-type ICC pulses with return strokes suggests that these pulses are associated with the mixed mode of charge transfer to ground.

  1. Nanosecond pulse-width electron diode based on dielectric wall accelerator technology

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Quantang, E-mail: zhaoquantang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Z.M.; Yuan, P.; Cao, S.C.; Shen, X.K.; Jing, Y. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Yu, C.S. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Z.P.; Liu, M.; Xiao, R.Q. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zong, Y.; Wang, Y.R. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, H.W. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2013-11-21

    An electron diode using a short section of dielectric wall accelerator (DWA) has been under development at the Institute of Modern Physics (IMP), Chinese Academy of Sciences. Tests have been carried out with spark gap switches triggered by lasers. The stack voltage efficiency of a four-layer of Blumleins reached about 60–70% with gas filled spark gap switching. The generated pulse voltage of peak amplitude of 23 kV and pulse width of 5 ns is used to extract and accelerate an electron beam of 320 mA, measured by a fast current transformer. A nanosecond pulse width electron diode was achieved successfully. Furthermore, the principle of a DWA is well proven and the development details and discussions are presented in this article. -- Highlights: •The key technology of DWA, including switches and pulse forming lines were studied. •The SiC PCSS obtained from Shanghai Institute were tested. •Two layers ZIP lines (new structure) and four layers Blumlein lines were studied with laser triggered spark gap switches. •A nanosecond pulse-width electron diode based on DWA technologies is achieved and studied experimentally. •The principle of DWA is also proved by the diode.

  2. A Pulsed Synchrotron for Muon Acceleration at a Neutrino Factory

    CERN Document Server

    Summers, D J; Berg, J S; Palmer, R B

    2003-01-01

    A 4600 Hz pulsed synchrotron is considered as a means of accelerating cool muons with superconducting RF cavities from 4 to 20 GeV/c for a neutrino factory. Eddy current losses are held to less than a megawatt by the low machine duty cycle plus 100 micron thick grain oriented silicon steel laminations and 250 micron diameter copper wires. Combined function magnets with 20 T/m gradients alternating within single magnets form the lattice. Muon survival is 83%.

  3. Medium-type pulsed fast-neutron detector

    International Nuclear Information System (INIS)

    A newly developed medium-type pulsed fast neutron detector is proposed. The detector consists of front insulator, n-p converter, absorber, collector and rear insulator. The detection principle is based on the output signal from both recoil-protons of the n-p converter and secondary electrons induced by the recoil-protons passing the interface between the absorber and the collector. Because of its detection of fast neutrons in the medium, unlike many traditional fast neutron detectors which work in the vacuum environment, this detector has obvious advantages. It does not need vacuum environment and high voltage power supply. This makes it to be used easily. By choosing teflon as the absorber and by choosing graphite as the charge collector, the contribution of the secondary electrons to the output signal can be determined experimentally

  4. Pulse-Height Distribution Analysis for Superconducting Nanostripline Ion Detector with a Fast Pulse-Integration Analog-Todigital Converter

    Science.gov (United States)

    Suzuki, Koji; Ukibe, Masahiro; Shiki, Shigetomo; Miki, Shigehito; Wang, Zhen; Takahashi, Yoshihiro; Yoshikawa, Nobuyuki; Ohkubo, Masataka

    Superconducting nano-stripline structure is promising for realizing an ideal ion detector for mass spectrometry (MS); nano-second time resolution and mass-independent detection efficiency from atoms to proteins. We report the first pulse-height spectra of a superconducting nano-stripline ion detector (SSLD) by a pulse-integration analog-to-digital converter (PIADC). A niobium nitride (NbN)-SSLD had a meander structure of the stripline with a thickness of 10 nm and a linewidth of 800 nm on an MgO substrate. A matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometer or a double-focusing mass spectrometer was used to produce and accelerate biomolecule ions (bovine serum albumin) with a molecular weight (MW) of 66,400 and Ar ions with an atomic weight (AW) of 40. Output pulse height did not depend on the MW or ion species for a wide mass range. Moreover, measured pulse-height distribution indicates that our SSLD system is so fast enough to discriminate the simultaneous ion incidence within 200 ns, which is close to the virtual dead time of time-to-digital converters (TDCs) at the practical usage in TOF MS for macromolecules.

  5. Fast magnetic reconnection and particle acceleration in pair plasmas

    Science.gov (United States)

    Bessho, Naoki; Bhattacharjee, A.

    2009-11-01

    Magnetic reconnection without a guide field in both non-relativistic and relativistic regimes has been studied in pair plasmas by 2D PIC simulations. We have found that in both regimes, particle acceleration enhances reconnection rates by an interesting feedback effect. Reconnection rates in the impulsive phase become of the order of 1 when the background density in a Harris sheet equilibrium is of the order of 0.01 of the density in the current sheet. Fast reconnection becomes possible not only because of increase of the time derivative part of the inertial term in the generalized Ohm's law, but also by a positive feedback on the pressure tensor term, bootstrapped by particle acceleration that produces a reduction in the particle density in the diffusion region. In this impulsive phase, the extension of the diffusion region along the outflow region is accompanied by a broadening of the width of the current sheet in the inflow region, keeping the aspect ratio small and sustaining a large reconnection rate. The collisionless resistivity originating from non-ideal terms in the generalized Ohm's law becomes large and nearly spatially uniform along the diffusion region even after the extension of the diffusion region, and can account quantitatively for the fast reconnection rate. We will compare and contrast this with reconnection and particle acceleration in hydrogen plasmas.

  6. Fast Multipole Accelerated Multiscale Analysis on the Sphere

    Science.gov (United States)

    Gutting, M.

    2013-12-01

    Spherical wavelets allow a space-frequency decomposition of many geophysical quantities on the sphere. Moreover, due to their localizing properties regional modeling or the improvement of a global model in a part of the sphere is possible. Certain types of spherical wavelets allow the acceleration of the spherical convolution by the fast multipole method. The main idea of the fast multipole algorithm consists of a hierarchical decomposition of the computational domain into cubes and a kernel approximation for the more distant points. The kernel evaluation is performed directly only for points in neighboring cubes on the finest level. The contributions of the other points are transferred into a set of coefficients. The kernel approximation in terms of inner and outer harmonics is applied on the coarsest possible level using translations of these coefficients. This reduces the numerical effort of the spherical convolution for a prescribed accuracy of the kernel approximation. Wavelet methods on the sphere come along with a tree algorithm that allows the computation of the lower frequency scales from a starting scale that contains the highest frequency parts of the signal. The application of the fast multipole method can accelerate the computation of this starting point as well as the tree algorithm itself. Applications to gravitational field modeling and spherical denoising are presented and finally, the extension to boundary value problems is considered where the boundary is the known surface of the Earth itself.

  7. Intense ion beams accelerated by ultra-intense laser pulses

    Science.gov (United States)

    Roth, Markus; Cowan, T. E.; Gauthier, J. C.; Vehn, J. Meyer-Ter; Allen, M.; Audebert, P.; Blazevic, A.; Fuchs, J.; Geissel, M.; Hegelich, M.; Karsch, S.; Pukhov, A.; Schlegel, T.

    2002-04-01

    The discovery of intense ion beams off solid targets irradiated by ultra-intense laser pulses has become the subject of extensive international interest. These highly collimated, energetic beams of protons and heavy ions are strongly depending on the laser parameters as well as on the properties of the irradiated targets. Therefore we have studied the influence of the target conditions on laser-accelerated ion beams generated by multi-terawatt lasers. The experiments were performed using the 100 TW laser facility at Laboratoire pour l'Utilisation des Laser Intense (LULI). The targets were irradiated by pulses up to 5×1019 W/cm2 (~300 fs,λ=1.05 μm) at normal incidence. A strong dependence on the surface conditions, conductivity, shape and purity was observed. The plasma density on the front and rear surface was determined by laser interferometry. We characterized the ion beam by means of magnetic spectrometers, radiochromic film, nuclear activation and Thompson parabolas. The strong dependence of the ion beam acceleration on the conditions on the target back surface was confirmed in agreement with predictions based on the target normal sheath acceleration (TNSA) mechanism. Finally shaping of the ion beam has been demonstrated by the appropriate tailoring of the target. .

  8. A CFD Simulation Process for Fast Reactor Fuel Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Kurt D. Hamman; Ray A. Berry

    2010-09-01

    A CFD modeling and simulation process for large-scale problems using an arbitrary fast reactor fuel assembly design was evaluated. Three-dimensional flow distributions of sodium for several fast reactor fuel assembly pin spacing configurations were simulated on high performance computers using commercial CFD software. This research focused on 19-pin fuel assembly “benchmark” geometry, similar in design to the Advanced Burner Test Reactor, where each pin is separated by helical wire-wrap spacers. Several two-equation turbulence models including the k–e and SST (Menter) k–? were evaluated. Considerable effort was taken to resolve the momentum boundary layer, so as to eliminate the need for wall functions and reduce computational uncertainty. High performance computers were required to generate the hybrid meshes needed to predict secondary flows created by the wire-wrap spacers; computational meshes ranging from 65 to 85 million elements were common. A general validation methodology was followed, including mesh refinement and comparison of numerical results with empirical correlations. Predictions for velocity, temperature, and pressure distribution are shown. The uncertainty of numerical models, importance of high fidelity experimental data, and the challenges associated with simulating and validating large production-type problems are presented.

  9. A CFD simulation process for fast reactor fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Hamman, Kurt D., E-mail: Kurt.Hamman@inl.go [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-3840 (United States); Berry, Ray A. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-3840 (United States)

    2010-09-15

    A CFD modeling and simulation process for large-scale problems using an arbitrary fast reactor fuel assembly design was evaluated. Three-dimensional flow distributions of sodium for several fast reactor fuel assembly pin spacing configurations were simulated on high performance computers using commercial CFD software. This research focused on 19-pin fuel assembly 'benchmark' geometry, similar in design to the Advanced Burner Test Reactor, where each pin is separated by helical wire-wrap spacers. Several two-equation turbulence models including the k-{epsilon} and SST (Menter) k-{omega} were evaluated. Considerable effort was taken to resolve the momentum boundary layer, so as to eliminate the need for wall functions and reduce computational uncertainty. High performance computers were required to generate the hybrid meshes needed to predict secondary flows created by the wire-wrap spacers; computational meshes ranging from 65 to 85 million elements were common. A general validation methodology was followed, including mesh refinement and comparison of numerical results with empirical correlations. Predictions for velocity, temperature, and pressure distribution are shown. The uncertainty of numerical models, importance of high fidelity experimental data, and the challenges associated with simulating and validating large production-type problems are presented.

  10. Accelerated oxygen precipitation in fast neutron irradiated Czochralski silicon

    Institute of Scientific and Technical Information of China (English)

    Ma Qiao-Yun; Li Yang-Xian; Chen Gui-Feng; Yang Shuai; Liu Li-Li; Niu Ping-Juan; Chen Dong-Feng; Li Hong-Tao

    2005-01-01

    Annealing effect of the oxygen precipitation and the induced defects have been investigated on the fast neutron irradiated Czochralski silicon (CZ-Si) by infrared absorption spectrum and the optical microscopy. It is found that the fast neutron irradiation greatly accelerates the oxygen precipitation that leads to a sharp decrease of the interstitial oxygen with the annealing time. At room temperature (RT), the 1107cm-1 infrared absorption band of interstitial oxygen becomes weak and broadens to low energy side. At low temperature, the infrared absorption peaks appear at 1078cm-1, 1096cm-1, and 1182cm-1, related to different shapes of the oxygen precipitates. The bulk microdefects,including stacking faults, dislocations and dislocation loops, were observed by the optical microscopy. New or large stacking faults grow up when the silicon self-interstitial atoms are created and aggregate with oxygen precipitation.

  11. Fast Neutron Radiography at an RFQ Accelerator System

    Science.gov (United States)

    Daniels, G. C.; Franklyn, C. B.; Dangendorf, V.; Buffler, A.; Bromberger, B.

    This work introduces the Necsa Radio Frequency Quadrupole (RFQ) accelerator facility and its work concerning fast neutron radiography (FNR). Necsa operates a 4-5 MeV, up to 50 mA deuteron RFQ. The previous deuterium gas target station has been modified to enable producing a white neutron beam employing a solid B4C target. Furthermore, the high energy beam transport (HEBT) section is under adjustment to achieve a longer flight-path and a better focus. This work presents an overview of the facility, the modifications made, and introduces past and ongoing neutron radiography investigations.

  12. Cyclinac Medical Accelerators Using Pulsed C6+/H2+ Ion Sources

    CERN Document Server

    Garonna, A; Bonomi, R; Campo, D; Degiovanni, A; Garlasché, M; Mondino, I; Rizzoglio, V; Andrés, S Verdú

    2010-01-01

    Charged particle therapy, or so-called hadrontherapy, is developing very rapidly. There is huge pressure on the scientific community to deliver dedicated accelerators, providing the best possible treatment modalities at the lowest cost. In this context, the Italian Research Foundation TERA is developing fast-cycling accelerators, dubbed cyclinacs. These are a combination of a cyclotron (accelerating ions to a fixed initial energy) followed by a high gradient linac boosting the ions energy up to the maximum needed for medical therapy. The linac is powered by many independently controlled klystrons to vary the beam energy from one pulse to the next. This accelerator is best suited to treat moving organs with a 4D multi-painting spot scanning technique. A dual proton/carbon ion cyclinac is here presented. It consists of an Electron Beam Ion Source, a superconducting isochronous cyclotron and a high-gradient linac. All these machines are pulsed at high repetition rate (100-400 Hz). The source should deliver both ...

  13. LIU 0.5/3000 pulse-periodical linear induction accelerator

    International Nuclear Information System (INIS)

    LIU 0.5/3000 accelerator designed for production of accelerator nanosecond high-current electron beam is described. Its main characteriatics are as follows: electron beam energy in pulse is 50j; electron peak energy - 500 keV; beam pulse power - 15 GW; current amplitude in pulse - 3 kA; beam current duration - 80 ns (at 0.1 level); beam aperture - 8-30cm2; accelerator operates in three modes: single-pulse mode, continuous mode with 50 pulses/s. Succession frequency, mode of pulse train formationfrom 5-10 pulses with equivalent pulse duration in the train up to 200 pulses/s; operating lifetime is ≥ 107 pulses. Accelerator dimensions are 2000x2100x900 mm, its mass - 800 kg

  14. Development of the pulsed power system of the accelerator module for the linear induction accelerator

    International Nuclear Information System (INIS)

    This paper presents a pulsed power system, the terminal load of which is an accelerator module, with this system, A 350 kV, 90 ns (FWHM) voltage with 30 ns rise-time accross the accelerating gap has been obtained. The jitter of the main switch operating at 280 kv is less than 1.5 ns (RMS). Further improvement on the performance of the coaxial field distortion switch is discussed and it is pointed out that the operating voltage of the switch can be increased by 8.2 %. If the triggering electrode is biased by means of equivalent electrical field stress. (author)

  15. Nike Experiments on Acceleration of Planar Targets Stabilized with a Short Spike Pulse^1

    Science.gov (United States)

    Weaver, J. L.; Velikovich, A. L.; Metzler, N.; Aglitskiy, Y.; Oh, J.; Mostovych, A. N.; Gardner, J. H.

    2005-10-01

    Theoretical work has shown that a low energy spike pulse in front of the drive laser pulse can help mitigate the growth of hydrodynamic instabilities in targets for inertial confinement fusion.[1]^ While other experiments [2] used higher spike pulse energies, this study reports the influence of a lower energy spike and longer spike-main pulse delay on the acceleration of planar CH targets. Time evolution of preimposed sinusoidal ripples on the target surface was observed using a monochromatic x-ray imaging system. Delayed onset and/or suppression of mode growth was found for the spike prepulse shots compared to those with a low intensity foot, in good agreement with predictions from FAST2D simulations. The propagation velocity of the decaying shock wave from the spike pulse was measured with VISAR and was also in good agreement with an analytical prediction.[3] [1] Metzler et al., Phys. Plasmas 6, 3283 (1999); 9, 5050 (2002); 10, 1897 (2003);Goncharov et al., Phys. Plasmas 10, 1906 (2003) ;Betti et al., Phys Plamas 12, 042703 (2005) ;[2]Knauer et al., Phys. Plasmas 12, 056306 (2005) ; [3]Velikovich et al., Phys. Plasmas 10, 3270 (2003). ^1Work supported by U. S. Department of Energy

  16. High Spatial Resolution Fast-Neutron Imaging Detectors for Pulsed Fast-Neutron Transmission Spectroscopy

    OpenAIRE

    Mor, I.; Vartsky, D.; Bar, D.; Feldman, G.; Goldberg, M B; Katz, D.; Sayag, E.; Shmueli, I.; Cohen, Y.; Tal, A; Vagish, Z.; Bromberger, B.; Dangendorf, V.; Mugai, D.; Tittelmeier, K.

    2009-01-01

    Two generations of a novel detector for high-resolution transmission imaging and spectrometry of fast-neutrons are presented. These devices are based on a hydrogenous fiber scintillator screen and single- or multiple-gated intensified camera systems (ICCD). This detector is designed for energy-selective neutron radiography with nanosecond-pulsed broad-energy (1 - 10 MeV) neutron beams. Utilizing the Time-of-Flight (TOF) method, such a detector is capable of simultaneously capturing several im...

  17. Eddy Current Modeling and Measuring in Fast-Pulsed Resistive Magnets

    CERN Document Server

    Arpaia, P; Gollucio, G; Montenero, G

    2010-01-01

    A method for modeling and measuring electromagnetic transients due to eddy currents in fast-pulsed resistive magnets is proposed. In particular, an equivalent-circuit model and a method for time-domain measurements of eddy currents are presented. The measurements are needed for an accurate control of the magnetic field quality to ensure adequate stability and performance of the particle beam in particle accelerators in dynamic conditions (field ramps up to about 700 T/s). In the second part, the results of experiments for model definition, identification, and validation are discussed. The tests were carried out on a quadrupole of Linac4, a new linear particle accelerator under construction at CERN (European Organization for Nuclear Research).

  18. Measurement of subcriticality using delayed neutron source combined with pulsed neutron accelerator

    International Nuclear Information System (INIS)

    A new experimental method for subcriticality measurement was developed by using delayed neutron source which is produced by external pulsed neutron source to increase accuracy of measured results by overcoming the space dependency problem which means difference of measured results in different detector position and often appeared in almost all other subcriticality measurement techniques. Experiments were performed at Kyoto University Critical Assembly (KUCA) combined with a DT accelerator to produce pulsed neutron in outside of the core repeatedly. In this method, neutron detection counts in the prompt neutron time region which are appeared just after injection of pulsed neutron are omitted, whereas neutron counts in the delayed neutron time region which are appeared after disappearance of exponential decay of the prompt neutron are adopted in analysis based on neutron source multiplication method or neutron noise analysis method; the variance to mean ratio method. In the delayed neutron time region, neutron sources to initiate fission chain reactions in subcritical state are delayed neutrons from delayed neutron precursors which are mainly produced by fission chain reactions in the prompt neutron time region, and delayed neutron precursors exist only in the fuel region, which makes possible to decrease the space dependency problem. The obtained results were compared with conventional pulsed neutron method, and it was found that the space dependency problem in subcriticality measurement can be fairly decreased by using the present new method compared with conventional one. (author)

  19. Ultra Fast Shutter Driven by Pulsed High Current

    Institute of Scientific and Technical Information of China (English)

    Zeng Jiangtao; Sun Fengju; Qiu Aici; Yin Jiahui; Guo Jianming; Chen Yulan

    2005-01-01

    Radiation simulation utilizing plasma radiation sources (PRS) generates a large number of undesirable debris, which may damage the expensive diagnosing detectors. An ultra fast shutter (UFS) driven by pulsed high current can erect a physical barrier to the slowly moving debris after allowing the passage of X-ray photons. The UFS consists of a pair of thin metal foils twisting the parallel axes in a Nylon cassette, compressed with an outer magnetic field, generated from a fast capacitor bank, discharging into a single turn loop. A typical capacitor bank is of 7.5μF charging voltages varying from 30 kV to 45 kV, with corresponding currents of approximately 90kA to140 kA and discharging current periods of approximately 13.1 μs. A shutter closing time as fast as 38 microseconds has been obtained with an aluminium foil thickness of 100 micrometers and a cross-sectional area of 15 mm by 20 mm. The design, construction and the expressions of the valve-closing time of the UFS are presented along with the measured results of valve-closing velocities.

  20. Scapula behavior associates with fast sprinting in first accelerated running.

    Science.gov (United States)

    Otsuka, Mitsuo; Ito, Taisuke; Honjo, Toyoyuki; Isaka, Tadao

    2016-01-01

    The arm-swing motion is important for coordinated lower limb movement during a fast sprint and is composed of three-dimensional scapulothoracic and glenohumeral joint motion. Here, we aimed to clarify the role of the scapula during the initiation of a sprint running when sprinter run with high horizontal acceleration. Ten sports-active students participated in four 5-m dashes, with scapular constraint using non-elastic therapy tape (constraint condition) and without scapular constraint (free condition). The sprinting kinematics was assessed by a 16-camera motion capture system. In the constraint condition, the 2-m sprint time was significantly longer than that in the free condition. At the instants of foot-contact and take-off during the first step, no significant difference in the humerothoracic flexion angle was seen between these two conditions. In contrast, at the instants of foot-contact and take-off during the first step, the humerothoracic extension angle in the constraint condition was significantly smaller than that in the free condition. The forward leaning vector angle of center of mass during the first step was significantly greater than that in the constraint condition. Although no significant difference in hip extension and foot forward leaning angles was seen at the instant of foot contact during the first step between the two conditions, at the instant of take-off, the hip extension and foot forward leaning angles in the constraint condition were significantly smaller than those in the free condition. Therefore, scapular behavior in first accelerated running contributes to larger upper- and lower-limb motions and facilitates coordinating whole-body balance for a fast sprint.

  1. Alternative concept for a fast energy amplifier accelerator driven reactor

    International Nuclear Information System (INIS)

    Recently Rubbia et al. introduced a conceptual design of a Fast Energy Amplifier (EA) as an advanced innovative reactor which utilizes a neutron spallation source induced by protons as an external source in a subcritical array imbibed a molten lead coolant which, besides being breeder and waste burner, generates energy. This paper introduces some qualitative changes in Rubbia's concept such as more than one point of spallation, in order to reduce the requirement in the energy and current of the accelerator, and mainly to make a more flat neutron distribution. The subcritical core which in Rubbia's concept is an hexagonal array of pins immersed in a molten lead coolant is replaced by a concept of a solid lead calandria with the fuel elements in channels cooled by helium, allowing on line refueling or shuffling, and the utilization of a direct thermodynamic cycle (Brayton), which is more efficient than a vapor cycle. Although the calculations to demonstrate the feasibility of the EA alternative concept are underway and not yet finished, these ideas do not violate the basic physics of the EA, as showed in this paper, with evident advantages in the fuel cycle (on line refueling); reduced requirements in the accelerator complex, which is more realistic and economical in today accelerators technology; and finally the utilization of He as coolant compared with molten Pb is more close to the proved technology given the know how of gas cooled reactors and more efficient from the thermodynamic point of view, allowing simplification and the utilization in other process, besides electricity generation, as hydrogen generation. (author)

  2. Laser plasma accelerator driven by a super-Gaussian pulse

    Science.gov (United States)

    Ostermayr, Tobias; Petrovics, Stefan; Iqbal, Khalid; Klier, Constantin; Ruhl, Hartmut; Nakajima, Kazuhisa; Deng, Aihua; Zhang, Xiaomei; Shen, Baifei; Liu, Jiansheng; Li, Ruxin; Xu, Zhizhan; Tajima, Toshiki; Tajima

    2012-08-01

    A laser wakefield accelerator (LWFA) with a weak focusing force is considered to seek improved beam quality in LWFA. We employ super-Gaussian laser pulses to generate the wakefield and study the behavior of the electron beam dynamics and synchrotron radiation arising from the transverse betatron oscillations through analysis and computation. We note that the super-Gaussian wakefields radically reduce the betatron oscillations and make the electron orbits mainly ballistic over a single stage. This feature permits to obtain small emittance and thus high luminosity, while still benefitting from the low-density operation of LWFA (Nakajima et al. 2011 Phys. Rev. ST Accel. Beams 14, 091301), such as the reduced radiation loss, less number of stages, less beam instabilities, and less required wall plug power than in higher density regimes.

  3. An Experimental Study of a Pulsed Electromagnetic Plasma Accelerator

    Science.gov (United States)

    Thio, Y. C. Francis; Eskridge, Richard; Lee, Mike; Smith, James; Martin, Adam; Markusic, Tom E.; Cassibry, Jason T.; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    Experiments are being performed on the NASA Marshall Space Flight Center (MSFC) pulsed electromagnetic plasma accelerator (PEPA-0). Data produced from the experiments provide an opportunity to further understand the plasma dynamics in these thrusters via detailed computational modeling. The detailed and accurate understanding of the plasma dynamics in these devices holds the key towards extending their capabilities in a number of applications, including their applications as high power (greater than 1 MW) thrusters, and their use for producing high-velocity, uniform plasma jets for experimental purposes. For this study, the 2-D MHD modeling code, MACH2, is used to provide detailed interpretation of the experimental data. At the same time, a 0-D physics model of the plasma initial phase is developed to guide our 2-D modeling studies.

  4. Note: A pulsed laser ion source for linear induction accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H., E-mail: bamboobbu@hotmail.com [Institute of Fluid Physics, China Academy of Engineering Physics, P.O. Box 919-106, Mianyang 621900 (China); School of Physics, Peking University, Beijing 100871 (China); Zhang, K.; Shen, Y.; Jiang, X.; Dong, P.; Liu, Y.; Wang, Y.; Chen, D.; Pan, H.; Wang, W.; Jiang, W.; Long, J.; Xia, L.; Shi, J.; Zhang, L.; Deng, J. [Institute of Fluid Physics, China Academy of Engineering Physics, P.O. Box 919-106, Mianyang 621900 (China)

    2015-01-15

    We have developed a high-current laser ion source for induction accelerators. A copper target was irradiated by a frequency-quadrupled Nd:YAG laser (266 nm) with relatively low intensities of 10{sup 8} W/cm{sup 2}. The laser-produced plasma supplied a large number of Cu{sup +} ions (∼10{sup 12} ions/pulse) during several microseconds. Emission spectra of the plasma were observed and the calculated electron temperature was about 1 eV. An induction voltage adder extracted high-current ion beams over 0.5 A/cm{sup 2} from a plasma-prefilled gap. The normalized beam emittance measured by a pepper-pot method was smaller than 1 π mm mrad.

  5. Fast Decompression Of Ultra-Thin Targets For High-Energy, High-Contrast Laser Pulses

    Science.gov (United States)

    Antici, P.; Fuchs, J.; Lefebvre, E.; Gremillet, L.; Brambrink, E.; Audebert, P.; Pépin, H.

    2010-02-01

    In the laser-plasma interaction process, for ultra-high temporal contrast laser pulses, experimental measurements show that reducing the thickness of solid targets increases the laser-to-fast electrons energy conversion and the hot electron temperature. We have performed an experiment using the LULI 100 TW laser facility working in the chirped pulse amplification (CPA) mode at a wavelength λ0 = 1.057 μm, pulse duration 320 fs, laser spot size FWHM ˜6 μm and intensity ˜1×1018 W/cm2 in which the laser pulses were temporal-contrast enhanced by the use of two plasma mirrors. Shots were performed on Si3N4 aluminum coated targets of thickness 30 nm to 500 nm. Spectra of the laser-accelerated electrons were recorded with a spectrometer and are compared to PIC simulations performed with the CALDER code. The simulations allow an insight into the electron heating process during the laser-matter interaction.

  6. Self-assembling peptide nanofiber scaffolds accelerate wound healing.

    Directory of Open Access Journals (Sweden)

    Aurore Schneider

    Full Text Available Cutaneous wound repair regenerates skin integrity, but a chronic failure to heal results in compromised tissue function and increased morbidity. To address this, we have used an integrated approach, using nanobiotechnology to augment the rate of wound reepithelialization by combining self-assembling peptide (SAP nanofiber scaffold and Epidermal Growth Factor (EGF. This SAP bioscaffold was tested in a bioengineered Human Skin Equivalent (HSE tissue model that enabled wound reepithelialization to be monitored in a tissue that recapitulates molecular and cellular mechanisms of repair known to occur in human skin. We found that SAP underwent molecular self-assembly to form unique 3D structures that stably covered the surface of the wound, suggesting that this scaffold may serve as a viable wound dressing. We measured the rates of release of EGF from the SAP scaffold and determined that EGF was only released when the scaffold was in direct contact with the HSE. By measuring the length of the epithelial tongue during wound reepithelialization, we found that SAP scaffolds containing EGF accelerated the rate of wound coverage by 5 fold when compared to controls without scaffolds and by 3.5 fold when compared to the scaffold without EGF. In conclusion, our experiments demonstrated that biomaterials composed of a biofunctionalized peptidic scaffold have many properties that are well-suited for the treatment of cutaneous wounds including wound coverage, functionalization with bioactive molecules, localized growth factor release and activation of wound repair.

  7. Vein of Galen aneurysm: MRI with a fast gradient refocusing pulse sequence

    International Nuclear Information System (INIS)

    A case of vein of Galen aneurysm, studied with a fast gradient refocusing pulse MRI sequence, is presented. Fast MRI sequences allowed the acquisition of additional hemodynamic information that was not available with either routine MRI or angiography. (orig.)

  8. Enhanced surface acceleration of fast electrons by using sub-wavelength grating targets

    CERN Document Server

    Hu, Guang-yue; Wang, Wen-tao; Wang, Jing-wei; Huang, Lin-gen; Wang, Xin; Xu, Yi; Liu, Jian-sheng; Shen, Bai-fei; Yu, Wei; Li, Ru-xin; Xu, Zhi-zhan

    2010-01-01

    Surface acceleration of fast electrons in intense laser-plasma interaction is improved by using sub-wavelength grating targets. The fast electron beam emitted along the target surface was enhanced by more than three times relative to that by using planar target. The total number of the fast electrons ejected from the front side of target was also increased by about one time. The method to enhance the surface acceleration of fast electron is effective for various targets with sub-wavelength structured surface, and can be applied widely in the cone-guided fast ignition, energetic ion acceleration, plasma device, and other high energy density physics experiments.

  9. A Concept for Directly Coupled Pulsed Electromagnetic Acceleration of Plasmas

    Science.gov (United States)

    Thio, Y.C. Francis; Cassibry, Jason T.; Eskridge, Richard; Smith, James; Wu, S. T.; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    Plasma jets with high momentum flux density are required for a variety of applications in propulsion research. Methods of producing these plasma jets are being investigated at NASA Marshall Space Flight Center. The experimental goal in the immediate future is to develop plasma accelerators which are capable of producing plasma jets with momentum flux density represented by velocities up to 200 km/s and ion density up to 10(exp 24) per cu m, with sufficient precision and reproducibility in their properties, and with sufficiently high efficiency. The jets must be sufficiently focused to allow them to be transported over several meters. A plasma accelerator concept is presented that might be able to meet these requirements. It is a self-switching, shaped coaxial pulsed plasma thruster, with focusing of the plasma flow by shaping muzzle current distribution as in plasma focus devices, and by mechanical tapering of the gun walls. Some 2-D MHD modeling in support of the conceptual design will be presented.

  10. High spatial resolution fast-neutron imaging detectors for Pulsed Fast-Neutron Transmission Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mor, I; Vartsky, D; Bar, D; Feldman, G; Goldberg, M B; Katz, D; Sayag, E; Shmueli, I; Cohen, Y; Tal, A; Vagish, Z [Soreq NRC, 81800 Yavne (Israel); Bromberger, B; Dangendorf, V; Mugai, D; Tittelmeier, K; Weierganz, M [Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig (Germany)], E-mail: ilmor@soreq.gov.il

    2009-05-15

    Two generations of a novel detector for high-resolution transmission imaging and spectrometry of fast-neutrons are presented. These devices are based on a hydrogenous fiber scintillator screen and single- or multiple-gated intensified camera systems (ICCD). This detector is designed for energy-selective neutron radiography with nanosecond-pulsed broad-energy (1-10 MeV) neutron beams. Utilizing the Time-of-Flight (TOF) method, such a detector is capable of simultaneously capturing several images, each at a different neutron energy (TOF). In addition, a gamma-ray image can also be simultaneously registered, allowing combined neutron/gamma inspection of objects. This permits combining the sensitivity of the fast-neutron resonance method to low-Z elements with that of gamma radiography to high-Z materials.

  11. High Spatial Resolution Fast-Neutron Imaging Detectors for Pulsed Fast-Neutron Transmission Spectroscopy

    CERN Document Server

    Mor, I; Bar, D; Feldman, G; Goldberg, M B; Katz, D; Sayag, E; Shmueli, I; Cohen, Y; Tal, A; Vagish, Z; Bromberger, B; Dangendorf, V; Mugai, D; Tittelmeier, K; Weierganz, M

    2009-01-01

    Two generations of a novel detector for high-resolution transmission imaging and spectrometry of fast-neutrons are presented. These devices are based on a hydrogenous fiber scintillator screen and single- or multiple-gated intensified camera systems (ICCD). This detector is designed for energy-selective neutron radiography with nanosecond-pulsed broad-energy (1 - 10 MeV) neutron beams. Utilizing the Time-of-Flight (TOF) method, such a detector is capable of simultaneously capturing several images, each at a different neutron energy (TOF). In addition, a gamma-ray image can also be simultaneously registered, allowing combined neutron/gamma inspection of objects. This permits combining the sensitivity of the fast-neutron resonance method to low-Z elements with that of gamma radiography to high-Z materials.

  12. Divergence of fast ions generated by interaction of intense ultra-high contrast laser pulses with thin foils

    International Nuclear Information System (INIS)

    We propose an analytical model that analyzes the divergence of fast ion beams accelerated at the rear of thin foils irradiated with ultra-short intense laser pulses. We demonstrate the critical role played by the non-stationary character of the side components of the electric field, which is responsible for ion acceleration from the back of the foil. The model predictions are in very good agreement with 2D PIC simulations and with the experiments performed in the ultra-high-contrast regime as well.

  13. Identification of acceleration pulses in near-fault ground motion using the EMD method

    Institute of Scientific and Technical Information of China (English)

    Zhang Yushan; Hu Yuxian; Zhao Fengxin; Liang Jianwen; Yang Caihong

    2005-01-01

    In this paper, response spectral characteristics of one-, two-, and three-lobe sinusoidal acceleration pulses are investigated, and some of their basic properties are derived. Furthermore, the empirical mode decomposition (EMD) method is utilized as an adaptive filter to decompose the near-fault pulse-like ground motions, which were recorded during the September 20, 1999, Chi-Chi earthquake. These ground motions contain distinct velocity pulses, and were decomposed into high-frequency (HF) and low-frequency (LF) components, from which the corresponding HF acceleration pulse (if existing)and LF acceleration pulse could be easily identified and detected. Finally, the identified acceleration pulses are modeled by simplified sinusoidal approximations, whose dynamic behaviors are compared to those of the original acceleration pulses as well as to those of the original HF and LF acceleration components in the context of elastic response spectra. It was demonstrated that it is just the acceleration pulses contained in the near-fault pulse-like ground motion that fundamentally dominate the special impulsive dynamic behaviors of such motion in an engineering sense. The motion thus has a greater potential to cause severe damage than the far-field ground motions, i.e. they impose high base shear demands on engineering structures as well as placing very high deformation demands on long-period structures.

  14. Pulsed Light Accelerated Crosslinking versus Continuous Light Accelerated Crosslinking: One-Year Results

    Directory of Open Access Journals (Sweden)

    Cosimo Mazzotta

    2014-01-01

    Full Text Available Purpose. To compare functional results in two cohorts of patients undergoing epithelium-off pulsed (pl-ACXL and continuous light accelerated corneal collagen crosslinking (cl-ACXL with dextran-free riboflavin solution and high-fluence ultraviolet A irradiation. Design. It is a prospective, comparative, and interventional clinical study. Methods. 20 patients affected by progressive keratoconus were enrolled in the study. 10 eyes of 10 patients underwent an epithelium-off pl-ACXL by the KXL UV-A source (Avedro Inc., Waltham, MS, USA with 8 minutes (1 sec. on/1 sec. off of UV-A exposure at 30 mW/cm2 and energy dose of 7.2 J/cm2; 10 eyes of 10 patients underwent an epithelium-off cl-ACXL at 30 mW/cm2 for 4 minutes. Riboflavin 0.1% dextran-free solution was used for a 10-minutes corneal soaking. Patients underwent clinical examination of uncorrected distance visual acuity and corrected distance visual acuity (UDVA and CDVA, corneal topography and aberrometry (CSO EyeTop, Florence, Italy, corneal OCT optical pachymetry (Cirrus OCT, Zeiss Meditec, Jena, Germany, endothelial cells count (I-Conan Non Co Robot, and in vivo scanning laser confocal microscopy (Heidelberg, Germany at 1, 3, 6, and 12 months of follow-up. Results. Functional results one year after cl-ACXL and pl-ACXL demonstrated keratoconus stability in both groups. Functional outcomes were found to be better in epithelium-off pulsed light accelerated treatment together with showing a deeper stromal penetration. No endothelial damage was recorded during the follow-up in both groups. Conclusions. The study confirmed that oxygen represents the main driver of collagen crosslinking reaction. Pulsed light treatment optimized intraoperative oxygen availability improving postoperative functional outcomes compared with continuous light treatment.

  15. Radiation damage effects and performance of power MOSFET using SPring-8 fast pulse driving power supply

    International Nuclear Information System (INIS)

    We have developed a compact and fast pulsed power supply system using in a fast kicker magnet system which is applied to suppress the perturbation of stored beam at injection to SPring-8 storage ring and to generate short pulsed synchrotron radiation in the SPring-8 storage ring. In this power supply system, we need a special specification to realize rapidity and high power output with compact system volume. We employed the system design to separate the output part from other components of the power supply system in order to place it near a beam pipe of the storage ring. By the employment of this system arrangement, it becomes easier not only to reduce the inductance to achieve above request specifications, but also to protect the main power supply components from radiation damage by placing them outside of the accelerator tunnel. We have employed Si Power MOSFETs as switching devices in the output part of the power supply system. By placing the output part beside of the beam pipe, the life of power MOSFETs naturally becomes to be affected an influence of the radiation. We assessed radiation damage for Si and SiC Power MOSFETs used in the actual operating system. Based on experimental results, we will discuss about the suitable switching device for our next generation power supply system from the point of view of Total Ionizing Dose (TID) effects. (author)

  16. Noise-Tolerant Streaming Real-Time Data Acquisition Fabric for Pulsed Accelerators

    CERN Document Server

    Siskind, E J

    2002-01-01

    A noise-tolerant data communications fabric has been developed to meet the real-time data acquisition and control requirements of fast feedback loops, machine protection systems, pulse-to-pulse sequencing, and machine-experiment communications at next-generation pulsed accelerators such as the Next Linear Collider ("NLC"). The fabric is constructed from "platform" or "system-on-a-chip" field programmable gate arrays ("FPGAs") containing embedded processors, block memory, and multi-gigabit serial transceivers interconnected via an array of point-to-point fiber-optic physical links for standard networks such as gigabit Ethernet. The FPGA-based link hardware segments messages of varying priorities into a continuous sequence of fixed-length data cells, interrupting the cell stream of lower priority messages with those comprising higher priority traffic. A high level of noise-tolerance is provided by dedicating almost half the contents of each cell to Reed-Solomon forward error correcting code ("ECC") data. Furthe...

  17. Laser Zone Annealing - Accelerated Route to Self-Assembled Nanostructures

    Science.gov (United States)

    Majewski, Pawel; Yager, Kevin; Rahman, Atikur; Black, Charles

    We present Laser Zone Annealing - a novel technique of accelerated self-assembly of block copolymer thin films utilizing laser light. In our approach, the laser beam, focused to a narrow line, is rastered across the polymer film coated on the light-absorbing substrate, inducing rapid and highly localized temperature transients in the film. By coupling our method with soft-shear, we demonstrate monolithic alignment of various cylinder-forming block copolymers over extremely short timescales. We utilize the aligned block copolymer films as templates for inorganic nanomaterials pattering. After delivery of inorganic precursors via aqueous or gaseous route, the polymer matrix is ashed leading to extremely well-ordered arrays of inorganic, metallic or semiconducting nanowires. Subsequently, we demonstrate how more complex nanostructures can be created with LZA including multilayered nanomeshes with symmetries beyond the conventional motifs accessible by native block copolymers. We investigate a perspective use of the inorganic arrays as transparent conductors or chemical sensors and characterize their anisotropic electro-optical properties. Research carried out in part at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.

  18. Acceleration of Initially Moving Electrons by a Copropagation Intense Laser Pulse

    Institute of Scientific and Technical Information of China (English)

    JING Guo-Liang; YU Wei; LI Ying-Jun; SENECHA Vinod; CHEN Zhao-Yang; LEI An-Le

    2008-01-01

    Acceleration of an initially moving electron by a copropagation ultra-short ultra-intense laser pulse in vacuum is studied. It is shown that when appropriate laser pulse parameters and focusing conditions are imposed, the acceleration of electron by ascending front of laser pulse can be much stronger compared to the deceleration by descending part. Consequently, the electron can obtain significantly high net energy gain. We also report the results of the new scheme that enables a second-step acceleration of electron using laser pulses of peak intensity in the range of 1019 - 1020 Wμm2/cm2. In the first step the electron acceleration from rest is limited to energies of a few MeV, while in the second step the electron acceleration can be considerably enhanced to about 100 MeV energy.

  19. Pulse-burst laser systems for fast Thomson scattering (invited)

    International Nuclear Information System (INIS)

    Two standard commercial flashlamp-pumped Nd:YAG (YAG denotes yttrium aluminum garnet) lasers have been upgraded to ''pulse-burst'' capability. Each laser produces a burst of up to 15 2 J Q-switched pulses (1064 nm) at repetition rates of 1-12.5 kHz. Variable pulse-width drive (0.15-0.39 ms) of the flashlamps is accomplished by insulated gate bipolar transistor (IGBT) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction, and up to four 2 J laser pulses during one flashlamp pulse. These lasers are used in the Thomson scattering plasma diagnostic system on the MST reversed-field pinch to record the dynamic evolution of the electron temperature profile and temperature fluctuations. To further these investigations, a custom pulse-burst laser system with a maximum pulse repetition rate of 250 kHz is now being commissioned.

  20. Pulse-burst laser systems for fast Thomson scattering (invited).

    Science.gov (United States)

    Den Hartog, D J; Ambuel, J R; Borchardt, M T; Falkowski, A F; Harris, W S; Holly, D J; Parke, E; Reusch, J A; Robl, P E; Stephens, H D; Yang, Y M

    2010-10-01

    Two standard commercial flashlamp-pumped Nd:YAG (YAG denotes yttrium aluminum garnet) lasers have been upgraded to "pulse-burst" capability. Each laser produces a burst of up to 15 2 J Q-switched pulses (1064 nm) at repetition rates of 1-12.5 kHz. Variable pulse-width drive (0.15-0.39 ms) of the flashlamps is accomplished by insulated gate bipolar transistor (IGBT) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction, and up to four 2 J laser pulses during one flashlamp pulse. These lasers are used in the Thomson scattering plasma diagnostic system on the MST reversed-field pinch to record the dynamic evolution of the electron temperature profile and temperature fluctuations. To further these investigations, a custom pulse-burst laser system with a maximum pulse repetition rate of 250 kHz is now being commissioned. PMID:21033868

  1. Important concepts in the assembly and early characterization of the PBFA 2 accelerator

    Science.gov (United States)

    Goldstein, S. A.; Clevenger, R. J.; Donovan, G. L.; Holman, G. T.; Johnston, R. R.; Nations, D. R.

    Some of the concepts for orchestrating large numbers of events associated with accelerator assembly and characterization include: (1) structuring of activity into smaller workable and trackable packages, with associated subelements assigned to each section of the accelerator, (2) establishing detailed assembly and characterization documentation to assist in component testing and subsystem integration, (3) structuring the project team for efficient communication, identification of responsibility, and capability for problem and conflict resolution, and (4) developing technologies for receival, inventory, controlled storage, staging, and phased installation and testing of components and pieceparts. The application of these and other concepts to PBFA II, and the progress of accelerator assembly is discussed.

  2. Double-Relativistic-Electron-Layer Proton Acceleration With High-Contrast Circular-Polarization Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    HUANG; Yong-sheng; WANG; Nai-yan; TANG; Xiu-zhang; SHI; Yi-jin

    2012-01-01

    <正>Laser-ion acceleration has been the focus of international research for many years. However, obtaining mono-energetic proton beams larger than 100 MeV is still a challenge. Although the field strength in laser-plasma acceleration is 3-4 orders higher than that in classic accelerators, it quickly decreases to zero in 1-2 pulse durations for target normal sheath acceleration (TNSA), which is dominated

  3. Experimental Studies on Assemblies 1 and 2 of the Fast Reactor FR-0. Part 2

    International Nuclear Information System (INIS)

    In a first part of this report, published as AE-195, an account was given of critical mass determinations and measurements of flux distribution and reaction ratios in the first assemblies of the fast zero power reactor FR0. This second part of the report deals with various investigations involving the measurement of reactivity. Control rod calibrations have been made using the positive period, the inverse multiplication, the rod drop and the pulsed source techniques, and show satisfactory agreement between the various methods. The reactivity worths of samples of different materials and different sizes have been measured at the core centre. Comparisons with perturbation calculations show that the regular and adjoint fluxes are well predicted in the central region of the core. The variation in the prompt neutron life-time with reactivity has been studied by means of the pulsed source and the Rossi-α techniques. Comparison with one region calculations reveals large discrepancies, indicating that this simple model is inadequate. Some investigations of streaming effects in an empty channel in the reactor and of interaction effects between channels have been made and are compared with theoretical estimates. Measurements of the reactivity worth of an air gap between the reactor halves and of the temperature coefficient are also described in the report. The work has been performed as a joint effort by AB Atomenergi and the Research Institute of National Defence

  4. Investigation of laser-driven proton acceleration using ultra-short, ultra-intense laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Fourmaux, S.; Gnedyuk, S.; Lassonde, P.; Payeur, S.; Pepin, H.; Kieffer, J. C. [INRS-EMT, Universite du Quebec, 1650 Lionel Boulet, Varennes, Quebec J3X 1S2 (Canada); Buffechoux, S.; Albertazzi, B. [INRS-EMT, Universite du Quebec, 1650 Lionel Boulet, Varennes, Quebec J3X 1S2 (Canada); LULI, UMR 7605, CNRS - CEA - Universite Paris 6 - Ecole Polytechnique, 91128 Palaiseau (France); Capelli, D.; Antici, P. [LULI, UMR 7605, CNRS - CEA - Universite Paris 6 - Ecole Polytechnique, 91128 Palaiseau (France); Dipartimento SBAI, Sapienza, Universita di Roma, Via Scarpa 16, 00161 Roma (Italy); Levy, A.; Fuchs, J. [LULI, UMR 7605, CNRS - CEA - Universite Paris 6 - Ecole Polytechnique, 91128 Palaiseau (France); Lecherbourg, L.; Marjoribanks, R. S. [Department of Physics and Institute for Optical Sciences, University of Toronto, Toronto, Ontario M5S 1A7 (Canada)

    2013-01-15

    We report optimization of laser-driven proton acceleration, for a range of experimental parameters available from a single ultrafast Ti:sapphire laser system. We have characterized laser-generated protons produced at the rear and front target surfaces of thin solid targets (15 nm to 90 {mu}m thicknesses) irradiated with an ultra-intense laser pulse (up to 10{sup 20} W Dot-Operator cm{sup -2}, pulse duration 30 to 500 fs, and pulse energy 0.1 to 1.8 J). We find an almost symmetric behaviour for protons accelerated from rear and front sides, and a linear scaling of proton energy cut-off with increasing pulse energy. At constant laser intensity, we observe that the proton cut-off energy increases with increasing laser pulse duration, then roughly constant for pulses longer than 300 fs. Finally, we demonstrate that there is an optimum target thickness and pulse duration.

  5. High-powered pulsed-ion-beam acceleration and transport

    International Nuclear Information System (INIS)

    The state of research on intense ion beam acceleration and transport is reviewed. The limitations imposed on ion beam transport by space charge effects and methods available for neutralization are summarized. The general problem of ion beam neutralization in regions free of applied electric fields is treated. The physics of acceleration gaps is described. Finally, experiments on multi-stage ion acceleration are summarized

  6. Injection of electrons by colliding laser pulses in a laser wakefield accelerator

    Science.gov (United States)

    Hansson, M.; Aurand, B.; Ekerfelt, H.; Persson, A.; Lundh, O.

    2016-09-01

    To improve the stability and reproducibility of laser wakefield accelerators and to allow for future applications, controlling the injection of electrons is of great importance. This allows us to control the amount of charge in the beams of accelerated electrons and final energy of the electrons. Results are presented from a recent experiment on controlled injection using the scheme of colliding pulses and performed using the Lund multi-terawatt laser. Each laser pulse is split into two parts close to the interaction point. The main pulse is focused on a 2 mm diameter gas jet to drive a nonlinear plasma wave below threshold for self-trapping. The second pulse, containing only a fraction of the total laser energy, is focused to collide with the main pulse in the gas jet under an angle of 150°. Beams of accelerated electrons with low divergence and small energy spread are produced using this set-up. Control over the amount of accelerated charge is achieved by rotating the plane of polarization of the second pulse in relation to the main pulse. Furthermore, the peak energy of the electrons in the beams is controlled by moving the collision point along the optical axis of the main pulse, and thereby changing the acceleration length in the plasma.

  7. General purpose pulse shape analysis for fast scintillators implemented in digital readout electronics

    Science.gov (United States)

    Asztalos, Stephen J.; Hennig, Wolfgang; Warburton, William K.

    2016-01-01

    Pulse shape discrimination applied to certain fast scintillators is usually performed offline. In sufficiently high-event rate environments data transfer and storage become problematic, which suggests a different analysis approach. In response, we have implemented a general purpose pulse shape analysis algorithm in the XIA Pixie-500 and Pixie-500 Express digital spectrometers. In this implementation waveforms are processed in real time, reducing the pulse characteristics to a few pulse shape analysis parameters and eliminating time-consuming waveform transfer and storage. We discuss implementation of these features, their advantages, necessary trade-offs and performance. Measurements from bench top and experimental setups using fast scintillators and XIA processors are presented.

  8. Experimental study of the neutronics of the first gas cooled fast reactor benchmark assembly (GCFR phase I assembly)

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, S.K.

    1976-12-01

    The Gas Cooled Fast Reactor (GCFR) Phase I Assembly is the first in a series of ZPR-9 critical assemblies designed to provide a reference set of reactor physics measurements in support of the 300 MW(e) GCFR Demonstration Plant designed by General Atomic Company. The Phase I Assembly was the first complete mockup of a GCFR core ever built. A set of basic reactor physics measurements were performed in the assembly to characterize the neutronics of the assembly and assess the impact of the neutron streaming on the various integral parameters. The analysis of the experiments was carried out using ENDF/B-IV based data and two-dimensional diffusion theory methods. The Benoist method of using directional diffusion coefficients was used to treat the anisotropic effects of neutron streaming within the framework of diffusion theory. Calculated predictions of most integral parameters in the GCFR showed the same kinds of agreements with experiment as in earlier LMFBR assemblies.

  9. Generation of heavy ion beams using femtosecond laser pulses in the target normal sheath acceleration and radiation pressure acceleration regimes

    Science.gov (United States)

    Petrov, G. M.; McGuffey, C.; Thomas, A. G. R.; Krushelnick, K.; Beg, F. N.

    2016-06-01

    Theoretical study of heavy ion acceleration from sub-micron gold foils irradiated by a short pulse laser is presented. Using two dimensional particle-in-cell simulations, the time history of the laser pulse is examined in order to get insight into the laser energy deposition and ion acceleration process. For laser pulses with intensity 3 × 10 21 W / cm 2 , duration 32 fs, focal spot size 5 μm, and energy 27 J, the calculated reflection, transmission, and coupling coefficients from a 20 nm foil are 80%, 5%, and 15%, respectively. The conversion efficiency into gold ions is 8%. Two highly collimated counter-propagating ion beams have been identified. The forward accelerated gold ions have average and maximum charge-to-mass ratio of 0.25 and 0.3, respectively, maximum normalized energy 25 MeV/nucleon, and flux 2 × 10 11 ions / sr . An analytical model was used to determine a range of foil thicknesses suitable for acceleration of gold ions in the radiation pressure acceleration regime and the onset of the target normal sheath acceleration regime. The numerical simulations and analytical model point to at least four technical challenges hindering the heavy ion acceleration: low charge-to-mass ratio, limited number of ions amenable to acceleration, delayed acceleration, and high reflectivity of the plasma. Finally, a regime suitable for heavy ion acceleration has been identified in an alternative approach by analyzing the energy absorption and distribution among participating species and scaling of conversion efficiency, maximum energy, and flux with laser intensity.

  10. Fast Track Teaching: Beginning the Experiment in Accelerated Leadership Development

    Science.gov (United States)

    Churches, Richard; Hutchinson, Geraldine; Jones, Jeff

    2009-01-01

    This article provides an overview of the development of the Fast Track teaching programme and personalised nature of the training and support that has been delivered. Fast Track teacher promotion rates are compared to national statistics demonstrating significant progression for certain groups, particularly women. (Contains 3 tables and 3 figures.)

  11. Multichannel computerized control system of current pulses in LIU-30 electron accelerator

    CERN Document Server

    Gerasimov, A I; Kulgavchuk, V V; Pluzhnikov, A V

    2002-01-01

    In LIU-30 power linear pulsed induction electron accelerator (40 MeV, 10 kA, 25 ns) 288 radial lines with water insulation serve as energy accumulators and shapers of accelerating voltage pulses. The lines are charged simultaneously up to 500 kV using a system comprising 72 Arkadiev-Marx screened generators. To control parameter of synchronous pulses of charging current with up to 60 kA amplitude and 0.85 mu s duration in every of 72 charging circuits one applies a computer-aided system. Current pulse is recorded at output of every generator using the Rogowski coil signal from which via a cable line is transmitted to an analog-digital converter, is processed with 50 ns sampling and is recorded to a memory unit. Upon actuation of accelerator the signals are sequentially or selectively displayed and are compared with pulse typical shape

  12. Multichannel computerized control system of current pulses in LIU-30 electron accelerator

    International Nuclear Information System (INIS)

    In LIU-30 power linear pulsed induction electron accelerator (40 MeV, 10 kA, 25 ns) 288 radial lines with water insulation serve as energy accumulators and shapers of accelerating voltage pulses. The lines are charged simultaneously up to 500 kV using a system comprising 72 Arkadiev-Marx screened generators. To control parameter of synchronous pulses of charging current with up to 60 kA amplitude and 0.85 μs duration in every of 72 charging circuits one applies a computer-aided system. Current pulse is recorded at output of every generator using the Rogowski coil signal from which via a cable line is transmitted to an analog-digital converter, is processed with 50 ns sampling and is recorded to a memory unit. Upon actuation of accelerator the signals are sequentially or selectively displayed and are compared with pulse typical shape

  13. Installation of a 100 kJ pulsed power system to drive pulsed plasma devices

    International Nuclear Information System (INIS)

    A pulsed-plasma accelerator is being developed at CPP-IPR, Assam. The accelerator consists of a co-axial electrode assembly housed inside an evacuated chamber that can produce high speed plasma stream of density approximately equal to 1022 m-3. For driving this plasma accelerator, a Pulsed Power System (PPS) of energy nearly 200kJ will be coupled to the electrode assembly. The voltage appearing across the electrode assembly will breakdown the gas present in the inter-electrode gap and create high density plasma. In this paper, the installation of a 100kJ PPS will be discussed, which is one module of the 200 kJ PPS of the plasma accelerator. In general, the conventional high voltage PPS is basically for producing fast output pulses (time periods of few microseconds) according to their uses. In contrast to that, the newly installed pulsed power system at CPP-IPR will produce relatively longer pulse of time period around 1.0ms. This PPS consists of 5 capacitors of rating 180μF, 15 kV each, connected in parallel by using two parallel plates of SS. The newly installed 100kJ bank has been tested and the detailed report of installation and testing will be presented. (author)

  14. Fast neutron leakage in 18 MeV medical electron accelerator

    CERN Document Server

    Paredes, L; Balcazar, M; Tavera, L; Camacho, E

    1999-01-01

    In this work the neutron fluence of the Varian Clinac 2100C Medical Accelerator has been evaluated using CR39 track dosimeter. The assessment of fast neutron dose to a patient for typical treatment of 200 cGy with an 18 MV photons beam is performed at surface-source distance of 100 cm with a field size of 20x20 cm sup 2. Fast neutron leakage around of the accelerator head is evaluated.

  15. Accelerating protons to therapeutic energies with ultraintense, ultraclean, and ultrashort laser pulses

    International Nuclear Information System (INIS)

    Proton acceleration by high-intensity laser pulses from ultrathin foils for hadron therapy is discussed. With the improvement of the laser intensity contrast ratio to 10-11 achieved on the Hercules laser at the University of Michigan, it became possible to attain laser-solid interactions at intensities up to 1022 W/cm2 that allows an efficient regime of laser-driven ion acceleration from submicron foils. Particle-in-cell (PIC) computer simulations of proton acceleration in the directed Coulomb explosion regime from ultrathin double-layer (heavy ions/light ions) foils of different thicknesses were performed under the anticipated experimental conditions for the Hercules laser with pulse energies from 3 to 15 J, pulse duration of 30 fs at full width half maximum (FWHM), focused to a spot size of 0.8 μm (FWHM). In this regime heavy ions expand predominantly in the direction of laser pulse propagation enhancing the longitudinal charge separation electric field that accelerates light ions. The dependence of the maximum proton energy on the foil thickness has been found and the laser pulse characteristics have been matched with the thickness of the target to ensure the most efficient acceleration. Moreover, the proton spectrum demonstrates a peaked structure at high energies, which is required for radiation therapy. Two-dimensional PIC simulations show that a 150-500 TW laser pulse is able to accelerate protons up to 100-220 MeV energies

  16. Time-resolved fast-neutron imaging with a pulse-counting image intensifier

    OpenAIRE

    Dangendorf, Volker; Lauck, Ronald; Kaufmann, Frank; Barnstedt, Juergen; Breskin, Amos; Jagutzki, Ottmar; Kraemer, Michael; Vartsky, David

    2006-01-01

    A new imaging method that combines high-efficiency fast-neutron detection with sub-ns time resolution is presented. This is achieved by exploiting the high neutron detection efficiency of a thick scintillator and the fast timing capability and flexibility of light-pulse detection with a dedicated image intensifier. The neutron converter is a plastic scintillator slab or, alternatively, a scintillating fibre screen. The scintillator is optically coupled to a pulse counting image intensifier wh...

  17. Theory for resonant ion acceleration by nonlinear magnetosonic fast and slow waves in finite beta plasmas

    International Nuclear Information System (INIS)

    A Korteweg--de Vries equation that is applicable to both the nonlinear magnetosonic fast and slow waves is derived from a two-fluid model with finite ion and electron pressures. As in the cold plasma theory, the fast wave has a critical angle theta/sub c/. For propagation angles greater than theta/sub c/ (quasiperpendicular propagation), the fast wave has a positive soliton, whereas for angles smaller than theta/sub c/, it has a negative soliton. Finite β effects decrease the value of theta/sub c/. The slow wave has a positive soliton for all angles of propagation. The magnitude of resonant ion acceleration (the v/sub p/ x B acceleration) by the nonlinear fast and slow waves is evaluated. In the fast wave, the electron pressure makes the acceleration stronger for all propagation angles. The decrease in theta/sub c/ resulting from finite β effects results in broadening of the region of strong acceleration. It is also found that fairly strong ion acceleration can occur in the nonlinear slow wave in high β plasmas. The possibility of unlimited acceleration of ions by quasiperpendicular magnetosonic fast waves is discussed

  18. Optimisation of resolution in accelerator-based fast neutron radiography

    CERN Document Server

    Rahmanian, H; Watterson, J I W

    2002-01-01

    In fast neutron radiography, imaging geometry, neutron scattering, the fast neutron scintillator and the position-sensitive detector all influence feature contrast, resolution and the signal-to-noise ratio in the image. The effect of imaging geometry can be explored by using a ray-tracing method. This requires following the path of neutrons through the imaging field, which includes the sample of interest. A relationship between imaging geometry and feature detectability can be developed. Monte Carlo methods can be used to explore the effect of neutron scattering on the results obtained with the ray-tracing technique. Fast neutrons are detected indirectly via neutron-nucleon scattering reactions. Using hydrogen-rich scintillators and relying on the recoil protons to ionise the scintillator material is the most sensitive technique available. The efficiency, geometry and composition of these scintillators influence the detectability of features in fast neutron radiography. These scintillator properties have a di...

  19. Design and measurements of a fast high-voltage pulse generator for the MedAustron Low Energy Transfer line fast deflector

    CERN Document Server

    Fowler, T; Mueller, F; Kramer, T; Stadlbauer, T

    2012-01-01

    MedAustron, a centre for ion-therapy and research, will comprise an accelerator facility based on a synchrotron for the delivery of protons and light ions for cancer treatment. The Low Energy Beam Transfer line (LEBT) to the synchrotron contains an electrostatic fast deflector (EFE) which, when energized, deviates the continuous beam arriving from the ion source onto a Faraday Cup: the specified voltage is ±3.5 kV. De-energizing the EFE for variable pulse durations from 500 ns up to d.c. allows beam passage for multi-turn injection into the synchrotron. To maintain beam quality in the synchrotron, the EFE pulse generator requires rise and fall times of less than 300 ns between 90 % of peak voltage and a ±1 V level. To achieve this, a pulsed power supply (PKF), with high voltage MOSFET switches connected in a push-pull configuration, will be mounted in close proximity to the deflector itself. A fast, large dynamic range monitoring circuit will verify switching to the ±1 V level and subsequent flat bottom pu...

  20. Control of high power IGBT modules in the active region for fast pulsed power converters

    CERN Document Server

    Cravero, J M; Garcia Retegui, R; Maestri, S; Uicich, G

    2014-01-01

    At CERN, fast pulsed power converters are used to supply trapezoidal current in different magnet loads. These converters perform output current regulation by using a high power IGBT module in its ohmic region. This paper presents a new strategy for pulsed current control applications using a specifically designed IGBT driver.

  1. Long-pulse beam acceleration of MeV-class H(-) ion beams for ITER NB accelerator.

    Science.gov (United States)

    Umeda, N; Kashiwagi, M; Taniguchi, M; Tobari, H; Watanabe, K; Dairaku, M; Yamanaka, H; Inoue, T; Kojima, A; Hanada, M

    2014-02-01

    In order to realize neutral beam systems in International Thermonuclear Experimental Reactor whose target is to produce a 1 MeV, 200 A/m(2) during 3600 s D(-) ion beam, the electrostatic five-stages negative ion accelerator so-called "MeV accelerator" has been developed at Japan Atomic Energy Agency. To extend pulse length, heat load of the acceleration grids was reduced by controlling the ion beam trajectory. Namely, the beam deflection due to the residual magnetic field of filter magnet was suppressed with the newly developed extractor with a 0.5 mm off-set aperture displacement. The new extractor improved the deflection angle from 6 mrad to 1 mrad, resulting in the reduction of direct interception of negative ions from 23% to 15% of the total acceleration power, respectively. As a result, the pulse length of 130 A/m(2), 881 keV H(-) ion beam has been successfully extended from a previous value of 0.4 s to 8.7 s. This is the first long pulse negative ion beam acceleration over 100 MW/m(2).

  2. Simulation of the relativistic electron dynamics and acceleration in a linearly-chirped laser pulse

    CERN Document Server

    Jisrawi, Najeh M; Salamin, Yousef I

    2014-01-01

    Theoretical investigations are presented, and their results are discussed, of the laser acceleration of a single electron by a chirped pulse. Fields of the pulse are modeled by simple plane-wave oscillations and a $\\cos^2$ envelope. The dynamics emerge from analytic and numerical solutions to the relativistic Lorentz-Newton equations of motion of the electron in the fields of the pulse. All simulations have been carried out by independent Mathematica and Python codes, with identical results. Configurations of acceleration from a position of rest as well as from injection, axially and sideways, at initial relativistic speeds are studied.

  3. Shock-Accelerated Flying Foil Diagnostic with a Chirped Pulse Spectral Interferometry

    Institute of Scientific and Technical Information of China (English)

    陈建平; 李儒新; 曾志男; 王兴涛; 程传福; 徐至展

    2003-01-01

    A shock-accelerated flying foil is diagnosed with a chirped pulse spectral interferometry. The shock is pumped by a 1.2ps chirped laser pulse with a power of~1014 W/cm2 at 785nm irradiating on a 500nm aluminium film and detected by a probe pulse split from the pump based on a Michelson spectral interferometry. A flying foil of~5.595×10-6 g in~400 μm diameter was accelerated to~165 nm away from the initial target rear surface at~1.83 km/s before ablation.

  4. Extremely Fast Acceleration of Cosmic Rays in a Supernova Remnant

    Energy Technology Data Exchange (ETDEWEB)

    Uchiyama, Y.; Aharonian, F.A.; Tanaka, T.; Takahashi, T.; Maeda, Y.; /JAERI, Tokai /Dublin Inst. /Heidelberg, Max Planck Inst. /SLAC

    2007-10-23

    Galactic cosmic rays (CRs) are widely believed to be accelerated by shock waves associated with the expansion of supernova ejecta into the interstellar medium. A key issue in this long-standing conjecture is a theoretical prediction that the interstellar magnetic field can be substantially amplified at the shock of a young supernova remnant (SNR) through magnetohydrodynamic waves generated by cosmic rays. Here we report a discovery of the brightening and decay of X-ray hot spots in the shell of theSNRRXJ1713.723946 on a one-year timescale. This rapid variability shows that the X-rays are produced by ultrarelativistic electrons through a synchrotron process and that electron acceleration does indeed take place in a strongly magnetized environment, indicating amplification of the magnetic field by a factor of more than 100. The X-ray variability also implies that we have witnessed the ongoing shock-acceleration of electrons in real time. Independently, broadband X-ray spectrometric measurements of RXJ1713.723946 indicate that electron acceleration proceeds in the most effective ('Bohm-diffusion') regime. Taken together, these two results provide a strong argument for acceleration of protons and nuclei to energies of 1 PeV (10{sup 15} eV) and beyond in young supernova remnants.

  5. Powerful nanosecond pulsed generators for linear induction accelerators at JINR

    International Nuclear Information System (INIS)

    The paper presents a review of nanosecond pulse generator schemes for LIA developed at the JINR. The main feature of these schemes consists in the use of relatively low-voltage generators (V∼20-50 kV) with low-resistance output impedance (R∼0.5 Ω). A high power in nanosecond pulses (W∼1 GW) is produced by nonlinear compression schemes with distributed parameters which compress electromagnetic energy in time

  6. Acceleration and guiding of fast electrons by a nanobrush target

    Science.gov (United States)

    Zhao, Zongqing; Cao, Lihua; Cao, Leifeng; Wang, Jian; Huang, Wenzhong; Jiang, Wei; He, Yingling; Wu, Yuchi; Zhu, Bin; Dong, Kegong; Ding, Yongkun; Zhang, Baohan; Gu, Yuqiu; Yu, M. Y.; He, X. T.

    2010-12-01

    Laser interaction with a nanobrush target plasma is investigated at the SILEX-I laser facility [X. F. Wei et al., J. Phys. Conf. Ser. 112, 032010 (2008)] with a laser of intensity 7.9×1018 W/cm2. Highly collimated fast electron beams with yields of more than three times higher than that from the planar target can be produced. Two-dimensional particle-in-cell simulation confirms that a layered surface structure can increase the efficiency of laser energy absorption, and the resulting fast electrons are tightly collimated and guided by the plasma layers to a cross section of about the laser spot size.

  7. Ablation experiment and threshold calculation of titanium alloy irradiated by ultra-fast pulse laser

    Directory of Open Access Journals (Sweden)

    Buxiang Zheng

    2014-02-01

    Full Text Available The interaction between an ultra-fast pulse laser and a material's surface has become a research hotspot in recent years. Micromachining of titanium alloy with an ultra-fast pulse laser is a very important research direction, and it has very important theoretical significance and application value in investigating the ablation threshold of titanium alloy irradiated by ultra-fast pulse lasers. Irradiated by a picosecond pulse laser with wavelengths of 1064 nm and 532 nm, the surface morphology and feature sizes, including ablation crater width (i.e. diameter, ablation depth, ablation area, ablation volume, single pulse ablation rate, and so forth, of the titanium alloy were studied, and their ablation distributions were obtained. The experimental results show that titanium alloy irradiated by a picosecond pulse infrared laser with a 1064 nm wavelength has better ablation morphology than that of the green picosecond pulse laser with a 532 nm wavelength. The feature sizes are approximately linearly dependent on the laser pulse energy density at low energy density and the monotonic increase in laser pulse energy density. With the increase in energy density, the ablation feature sizes are increased. The rate of increase in the feature sizes slows down gradually once the energy density reaches a certain value, and gradually saturated trends occur at a relatively high energy density. Based on the linear relation between the laser pulse energy density and the crater area of the titanium alloy surface, and the Gaussian distribution of the laser intensity on the cross section, the ablation threshold of titanium alloy irradiated by an ultra-fast pulse laser was calculated to be about 0.109 J/cm2.

  8. Forward acceleration and generation of femtosecond, megaelectronvolt electron beams by an ultrafast intense laser pulse

    Institute of Scientific and Technical Information of China (English)

    Xiaofang wang(王晓方); Quandong Wang(汪权东); Baifei Shen(沈百飞)

    2003-01-01

    We present a new mechanism of energy gain of electrons accelerated by a laser pulse. It is shown that when the intensity of an ultrafast intense laser pulse decreases rapidly along the direction of propagation, electrons leaving the pulse experience an action of ponderomotive deceleration at the descending part of a lower-intensity laser field than acceleration at the ascending part of a high-intensity field, thus gain net energy from the pulse and move directly forward. By means of such a mechanism, a megaelectronvolt electron beam with a bunch length shorter than 100 fs could be realized with an ultrafast (≤30 fs),intense (>1019 W/cm2) laser pulse.

  9. Design of light Ⅱ-B pulsed power electron accelerator

    International Nuclear Information System (INIS)

    The Light Ⅱ-B was built at the side of the Marx tank of Light Ⅱ-A for X-pinch test, which kept the original capacity of KrF excimer laser, and can be used for relevant researches of X-pinch. It is composed of a Marx generator, a pulse forming line (PFL), a gas-filled switch, a pulse transmission line (PTL), and a copper-sulphate resistive load. The medium of the forming line is deionized water. The input impendence of the pulse forming line is 6 Ω, corresponding to an output impendence of 1.25 Ω for the pulse transfer line. The design of circuit simulation and the debugging results in resistance load were introduced. The results show that the current peak load is about 269 kA, pulse width is about 50 ns, and the current rise tune is less than 30 ns when the load is 1.25 Ω. It indicates that Light Ⅱ-B has the ability to drive low impedance X-pinch experimental line. (authors)

  10. Pulse-shape discrimination of the new plastic scintillators in neutron-gamma mixed field using fast digitizer card

    Science.gov (United States)

    Jančář, A.; Kopecký, Z.; Dressler, J.; Veškrna, M.; Matěj, Z.; Granja, C.; Solar, M.

    2015-11-01

    Recently invented plastic scintillator EJ-299-33 enables pulse-shape discrimination (PSD) and thus measurement of neutron and photon spectra in mixed fields. In this work we compare the PSD properties of EJ-299-33 plastic and the well-known NE-213 liquid scintillator in monoenergetic neutron fields generated by the Van de Graaff accelerator using the 3H(d, n)4He reaction. Pulses from the scintillators are processed by a newly developed digital measuring system employing the fast digitizer card. This card contains two AD converters connected to the measuring computer via 10 Gbps optical ethernet. The converters operate with a resolution of 12 bits and have two differential inputs with a sampling frequency 1 GHz. The resulting digital channels with different gains are merged into one composite channel with a higher digital resolution in a wide dynamic range of energies. Neutron signals are fully discriminated from gamma signals. Results are presented.

  11. Optimizing pulse shaping and zooming for acceleration to high velocities and fusion neutron production on the Nike laser

    Science.gov (United States)

    Karasik, Max; Weaver, J. L.; Aglitskiy, Y.; Zalesak, S. T.; Velikovich, A. L.; Oh, J.; Obenschain, S. P.; Arikawa, Y.; Watari, T.

    2010-11-01

    We will present results from follow-on experiments to the record-high velocities of 1000 km/s achieved on Nike [Karasik et al., Phys. Plasmas 17, 056317 (2010) ], in which highly accelerated planar foils of deuterated polystyrene were made to collide with a witness foil to produce extreme shock pressures and result in heating of matter to thermonuclear temperatures. Still higher velocities and higher target densities are required for impact fast ignition. The aim of these experiments is shaping the driving pulse to minimize shock heating of the accelerated target and using the focal zoom capability of Nike to achieve higher densities and velocities. Spectroscopic measurements of electron temperature achieved upon impact will complement the neutron time-of-flight ion temperature measurement. Work is supported by US DOE and Office of Naval Research.

  12. Optical emission spectroscopy observations of fast pulsed capillary discharge plasmas

    Science.gov (United States)

    Avaria, G.; Ruiz, M.; Guzmán, F.; Favre, M.; Wyndham, E. S.; Chuaqui, H.; Bhuyan, H.

    2014-05-01

    We present time resolved optical emission spectroscopic (OES) observations of a low energy, pulsed capillary discharage (PCD). The optical emission from the capillary plasma and plasma jets emitted from the capillary volume was recorded with with a SpectraPro 275 spectrograph, fitted with a MCP gated OMA system, with 15 ns time resolution. The discharge was operated with different gases, including argon, nitrogen, hydrogen and methane, in a repetitive pulsed discharge mode at 10-50 Hz, with, 10-12 kV pulses applied at the cathode side. The time evolution of the electron density was measured using Stark broadening of the Hβ line. Several features of the capillary plasma dynamics, such as ionization growth, wall effects and plasma jet evolution, are inferred from the time evolution of the optical emission.

  13. Pulsed magnetic welding application of fast breeder austenitic pins plugging

    International Nuclear Information System (INIS)

    For specific nuclear needs, we had to develop pulsed magnetic welding on high resistivity coefficient alloys as austenitic steels. The magnetic force produced by an explosive inductor is transmitted on weld pieces by the use of an aluminium driver. A theoretical work carried out permitted to compare pulsed magnetic welding with explosive welding. With specific recordings, it was possible to study electrical and magnetical behavior during the active welding phase. By means of these informations, we are able to specify and to realize, with the financial help of ANVAR organization, a low impedance high velocity generator permitting to weld with a non destructible inductor. 6 refs

  14. Electron Acceleration by a Focused Gaussian Laser Pulse in Vacuum

    Institute of Scientific and Technical Information of China (English)

    何峰; 余玮; 陆培祥; 徐涵

    2004-01-01

    By numerically solving the relativistic equations of motion of a single electron in laser fields modeled by a Gaussian laser beam, we get the trajectory and energy of the electron. When the drifting distance is comparable to or even longer than the corresponding Rayleigh length, the evolution of the beam waist cannot be neglected. The asymmetry of intensity in acceleration and deceleration leads to the conclusion that the electron can be accelerated effectively and extracted by the longitudinal ponderomotive force. For intensities above, an electron's energy gain about MeV can be realized, and the energetic electron is parallel with the propagation axis.

  15. Ion acceleration in a solitary wave by an intense picosecond laser pulse.

    Science.gov (United States)

    Zhidkov, A; Uesaka, M; Sasaki, A; Daido, H

    2002-11-18

    Acceleration of ions in a solitary wave produced by shock-wave decay in a plasma slab irradiated by an intense picosecond laser pulse is studied via particle-in-cell simulation. Instead of exponential distribution as in known mechanisms of ion acceleration from the target surface, these ions accelerated forwardly form a bunch with relatively low energy spread. The bunch is shown to be a solitary wave moving over expanding plasma; its velocity can exceed the maximal velocity of ions accelerated forward from the rear side of the target.

  16. Ultra Intense Laser Pulse Interactions with Planer and Spherical Plasmas for Fast Ignitor

    Science.gov (United States)

    Tanaka, Kazuo A.

    1999-11-01

    The fast ignitor concept requires the guiding or penetration of an ultra-intense laser close to a highly compressed (1000 times solid density) core and the generation of energetic electrons (MeV). Ultra-intense laser plasma interactions have been intensively studied using the Peta Watt Module (PWM) laser system synchronized with the GEKKO XII laser system. The ultra-intense laser pulse of 50J energy, 0.5-1 psec pulse width and 1053 nm laser wavelength could be focused onto a preformed plasma created on a solid target at an intensity of 1e19 W/cm2. The preformed plasma had a cut-off density surface at around 100 micron from the surface. Changing the focus position of this 100 TW laser pulse relative to the preformed plasma, we found an anomalous mode. Side view of x-ray pinhole camera showed that there was a local tiny spot almost at the surface of the solid target which indicates the propagation of the pulse in the long scale-length plasma into an over-dense region for over 100 micorn distance. The erergy spectrum and angular distribution of more than MeV electrons were measured. Its energy transport was studied with K-a spectroscopy. The backscattered light of the ultra-intense laser light was spectrally and spatially resolved. The backscattered light image showed several hot spots within the focused region. The spatilally resolved spectra of the backscattered light were totally different at the hot spots and surrounding regions. The details of neutron spectra were measured using ``MANDALA" neutron spectormeters with a total of 841 channel photo-multiplier detectors. The data indicates that deuterium ions were accelerated by the hot electrons up to 100 keV and created beam fusion reactions within solid CD targets. Guiding channels were created utilizing a ponderomotive self-focusing in preformed plasmas created on a solid target. The self-focus channel was measured by both UV and x-ray laser probes. The details of the experiment as well as the theoretical

  17. Flyer Acceleration by Pulsed Ion Beam Ablation and Application for Space Propulsion

    International Nuclear Information System (INIS)

    Flyer acceleration by ablation plasma pressure produced by irradiation of intense pulsed ion beam has been studied. Acceleration process including expansion of ablation plasma was simulated based on fluid model. And interaction between incident pulsed ion beam and a flyer target was considered as accounting stopping power of it. In experiments, we used ETIGO-II intense pulsed ion beam generator with two kinds of diodes; 1) Magnetically Insulated Diode (MID, power densities of <100 J/cm2) and 2) Spherical-focused Plasma Focus Diode (SPFD, power densities of up to 4.3 kJ/cm2). Numerical results of accelerated flyer velocity agreed well with measured one over wide range of incident ion beam energy density. Flyer velocity of 5.6 km/s and ablation plasma pressure of 15 GPa was demonstrated by the present experiments. Acceleration of double-layer target consists of gold/aluminum was studied. For adequate layer thickness, such a flyer target could be much more accelerated than a single layer. Effect of waveform of ion beam was also examined. Parabolic waveform could accelerate more efficiently than rectangular waveform. Applicability of ablation propulsion was discussed. Specific impulse of 7000∼8000 seconds and time averaged thrust of up to 5000∼6000N can be expected. Their values can be controllable by changing power density of incident ion beam and pulse duration

  18. High-flux, extended-pulse accelerators: Final report

    International Nuclear Information System (INIS)

    The purpose of the program was to investigate physical phenomena associated with high flux ion beam generation and to develop technology for intense ion beam accelerators with pulselengths in the ms range. At the time the work was initiated, the chief area of application for the technology was ion implantation and materials modification

  19. Simulation and experimental study of the solid pulse forming lines for dielectric wall accelerator

    Institute of Scientific and Technical Information of China (English)

    ZHAO Quan-Tang; YUAN Ping; ZHANG Zi-Min; CAO Shu-Chun; SHEN Xiao-Kang; LIU Ming; JING Yi; ZHAO Hong-Wei

    2011-01-01

    Two types of pulse forming lines for dielectric wall accelerator (DWA) were investigated preliminarily.By simulation with CST Microwave Studio,the results indicate the pulse forming process,which can help to understand the voltage wave transmission process and optimize the line parameters.Furthermore,the principle of the pulse forming process was proved by experiments and some excellent pulse waveforms were obtained.During the experiments,the Blumlein line and zero integral pulse (ZIP) forming line,constructed with aluminum foil,poly plate and air gap self-closing switch,were tested.The full width at half maximum (FWHM) of the waveform is 16 nanoseconds (BL) and 17 nanoseconds (ZIP line),and the formed pulse voltage amplitude is 5 kV (BL) and +2.2 kV/-1.6 kV (ZIP line).The experiments result coincides well with the simulation.

  20. Quantum behavior of a SQUID qubit manipulated with fast pulses

    Energy Technology Data Exchange (ETDEWEB)

    Spilla, Samuele; Messina, Antonino; Napoli, Anna [Dipartimento di Fisica dell' Universita di Palermo, Via Archirafi 36, 90123 Palermo (Italy); Castellano, Maria Gabriella; Chiarello, Fabio [Istituto Fotonica e Nanotecnologie - CNR, Roma (Italy); Migliore, Rosanna [Institute of Biophysics, National Research Council, via Ugo La Malfa 153, 90146 Palermo (Italy)

    2013-07-01

    A SQUID qubit manipulated with fast variation of the energy potential is analyzed. Varying the potential shape from a single to a double-well configuration, quantum behaviors are brought into light and discussed. We show that the presence of quantum coherences in the initial state of the system plays a central role in the appearance of these quantum effects.

  1. Instantaneous coherent destruction of tunneling and fast quantum state preparation for strongly pulsed spin qubits in diamond

    DEFF Research Database (Denmark)

    Wubs, Martijn

    2010-01-01

    Qubits driven by resonant strong pulses are studied and a parameter regime is explored in which the dynamics can be solved in closed form. Instantaneous coherent destruction of tunneling can be seen for longer pulses, whereas shorter pulses allow a fast preparation of the qubit state. Results...... are compared with recent experiments of pulsed nitrogen-vacancy center spin qubits in diamond....

  2. Shaping the electron beams with submicrosecond pulse duration in sources and electron accelerators with plasma emitters

    CERN Document Server

    Gushenets, V I

    2001-01-01

    One studies the techniques in use to shape submicrosecond electron beams and the physical processes associated with extraction of electrons from plasma in plasma emitters. Plasma emitter base sources and accelerators enable to generate pulse beams with currents varying from tens of amperes up to 10 sup 3 A, with current densities up to several amperes per a square centimeter, with pulse duration constituting hundreds of nanoseconds and with high frequencies of repetition

  3. Transport synthetic acceleration for long-characteristics assembly-level transport problems

    Energy Technology Data Exchange (ETDEWEB)

    Zika, M.R.; Adams, M.L.

    2000-02-01

    The authors apply the transport synthetic acceleration (TSA) scheme to the long-characteristics spatial discretization for the two-dimensional assembly-level transport problem. This synthetic method employs a simplified transport operator as its low-order approximation. Thus, in the acceleration step, the authors take advantage of features of the long-characteristics discretization that make it particularly well suited to assembly-level transport problems. The main contribution is to address difficulties unique to the long-characteristics discretization and produce a computationally efficient acceleration scheme. The combination of the long-characteristics discretization, opposing reflecting boundary conditions (which are present in assembly-level transport problems), and TSA presents several challenges. The authors devise methods for overcoming each of them in a computationally efficient way. Since the boundary angular data exist on different grids in the high- and low-order problems, they define restriction and prolongation operations specific to the method of long characteristics to map between the two grids. They implement the conjugate gradient (CG) method in the presence of opposing reflection boundary conditions to solve the TSA low-order equations. The CG iteration may be applied only to symmetric positive definite (SPD) matrices; they prove that the long-characteristics discretization yields an SPD matrix. They present results of the acceleration scheme on a simple test problem, a typical pressurized water reactor assembly, and a typical boiling water reactor assembly.

  4. Transport synthetic acceleration for long-characteristics assembly-level transport problems

    International Nuclear Information System (INIS)

    The authors apply the transport synthetic acceleration (TSA) scheme to the long-characteristics spatial discretization for the two-dimensional assembly-level transport problem. This synthetic method employs a simplified transport operator as its low-order approximation. Thus, in the acceleration step, the authors take advantage of features of the long-characteristics discretization that make it particularly well suited to assembly-level transport problems. The main contribution is to address difficulties unique to the long-characteristics discretization and produce a computationally efficient acceleration scheme. The combination of the long-characteristics discretization, opposing reflecting boundary conditions (which are present in assembly-level transport problems), and TSA presents several challenges. The authors devise methods for overcoming each of them in a computationally efficient way. Since the boundary angular data exist on different grids in the high- and low-order problems, they define restriction and prolongation operations specific to the method of long characteristics to map between the two grids. They implement the conjugate gradient (CG) method in the presence of opposing reflection boundary conditions to solve the TSA low-order equations. The CG iteration may be applied only to symmetric positive definite (SPD) matrices; they prove that the long-characteristics discretization yields an SPD matrix. They present results of the acceleration scheme on a simple test problem, a typical pressurized water reactor assembly, and a typical boiling water reactor assembly

  5. Transport Synthetic Acceleration for Long-Characteristics Assembly-Level Transport Problems

    International Nuclear Information System (INIS)

    We apply the transport synthetic acceleration (TSA) scheme to the long-characteristics spatial discretization for the two-dimensional assembly-level transport problem. This synthetic method employs a simplified transport operator as its low-order approximation. Thus, in the acceleration step, we take advantage of features of the long-characteristics discretization that make it particularly well suited to assembly-level transport problems. Our main contribution is to address difficulties unique to the long-characteristics discretization and produce a computationally efficient acceleration scheme.The combination of the long-characteristics discretization, opposing reflecting boundary conditions (which are present in assembly-level transport problems), and TSA presents several challenges. We devise methods for overcoming each of them in a computationally efficient way. Since the boundary angular data exist on different grids in the high- and low-order problems, we define restriction and prolongation operations specific to the method of long characteristics to map between the two grids. We implement the conjugate gradient (CG) method in the presence of opposing reflection boundary conditions to solve the TSA low-order equations. The CG iteration may be applied only to symmetric positive definite (SPD) matrices; we prove that the long-characteristics discretization yields an SPD matrix. We present results of our acceleration scheme on a simple test problem, a typical pressurized water reactor assembly, and a typical boiling water reactor assembly

  6. Laser accelerated protons captured and transported by a pulse power solenoid

    Science.gov (United States)

    Burris-Mog, T.; Harres, K.; Nürnberg, F.; Busold, S.; Bussmann, M.; Deppert, O.; Hoffmeister, G.; Joost, M.; Sobiella, M.; Tauschwitz, A.; Zielbauer, B.; Bagnoud, V.; Herrmannsdoerfer, T.; Roth, M.; Cowan, T. E.

    2011-12-01

    Using a pulse power solenoid, we demonstrate efficient capture of laser accelerated proton beams and the ability to control their large divergence angles and broad energy range. Simulations using measured data for the input parameters give inference into the phase-space and transport efficiencies of the captured proton beams. We conclude with results from a feasibility study of a pulse power compact achromatic gantry concept. Using a scaled target normal sheath acceleration spectrum, we present simulation results of the available spectrum after transport through the gantry.

  7. Electromagnetic processes in the pulsed inductors of electron accelerators

    Directory of Open Access Journals (Sweden)

    В. Т. Чемерис

    2013-07-01

    Full Text Available The process of magnetic field setting up at its excitation in the cross section of the closed laminated core of the pulsed inductor has been investigated by numerical methods. Analysis of the field expansion from the boundaries of cross section to its center was realized due to using of two-dimensional numerical model of the wave equation written in non-dimensional form with application of equivalent magnetic μ and dielectric ε parameters. Two situations had been taken into consideration: 1 the medium of laminated package has anisotropic ideal magneto-dielectric properties (no electrical conductivity; 2 the medium of package is isotropic, but has the losses of energy due to electrical conductivity of ferromagnetic layers. The ratio  of the basic velocity (which defines via basic dimension of the package cross section and duration of the pulsed field to the speed of electromagnetic wave propagation in this medium  serves as characteristic parameter of similarity for the processes in models with different scale of time and/or dimensions. The magnetic Reynolds’ number  must be used additionally as the measure of the field diffusion. The character of wave processes in the core has been studied and the conditions of their essential influence on the field distribution have been established. That is shown that main criterion for estimation of the core filling up by the magnetic flux (i.e. for estimation of package using effectiveness is the correlation between the dimension of cross section and the path of the wave run during the pulse duration. The criterion for observation only diffusion picture of the field propagation at the magnetic Reynolds’ number is the ratio . Under conditions when the wave phenomena play relatively small role the speed of the field diffusion instead of the velocity of the wave propagation must be used at the estimation of the package cross section effective usage

  8. Acceleration of the Fast Solar Wind by Solitary Waves in Coronal Holes

    Science.gov (United States)

    Ofman, Leon

    2001-01-01

    The purpose of this investigation is to develop a new model for the acceleration of the fast solar wind by nonlinear. time-dependent multidimensional MHD simulations of waves in solar coronal holes. Preliminary computational studies indicate that nonlinear waves are generated in coronal holes by torsional Alfv\\'{e}n waves. These waves in addition to thermal conduction may contribute considerably to the accelerate the solar wind. Specific goals of this proposal are to investigate the generation of nonlinear solitary-like waves and their effect on solar wind acceleration by numerical 2.5D MHD simulation of coronal holes with a broad range of plasma and wave parameters; to study the effect of random disturbances at the base of a solar coronal hole on the fast solar wind acceleration with a more advanced 2.5D MHD model and to compare the results with the available observations; to extend the study to a full 3D MHD simulation of fast solar wind acceleration with a more realistic model of a coronal hole and solar boundary conditions. The ultimate goal of the three year study is to model the, fast solar wind in a coronal hole, based on realistic boundary conditions in a coronal hole near the Sun, and the coronal hole structure (i.e., density, temperature. and magnetic field geometry,) that will become available from the recently launched SOHO spacecraft.

  9. Envelope time reversal of optical pulses following frequency conversion with accelerating quasi-phase-matching

    CERN Document Server

    Yachini, Michal; Bahabad, Alon

    2016-01-01

    It is shown theoretically that the use of accelerating spatiotemporal quasi-phase-matching (QPM) modulation patterns in media with parametric optical interactions makes it possible to generate a time-reversed replica of the pump pulse envelope in a frequency converted signal. The conversion is dependent on the group-velocity mismatch between the fundamental and up-converted harmonics, and controlled by the acceleration rate (chirp) of the QPM phase pattern. Analytical results are corroborated by numerical simulations.

  10. Compact MCP assemblies for mass spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, S. [Hamamatsu Photonics K.K., Shizuoka (Japan). Electron Tube Div.; Umebayashi, S. [Hamamatsu Photonics K.K., Shizuoka (Japan). Electron Tube Div.; Kusuyama, Y. [Hamamatsu Photonics K.K., Shizuoka (Japan). Electron Tube Div.; Natsume, Y. [Hamamatsu Photonics K.K., Shizuoka (Japan). Electron Tube Div.; Oba, K. [Hamamatsu Photonics K.K., Shizuoka (Japan). Electron Tube Div.

    1995-09-01

    We have developed compact microchannel plate (MCP) assemblies which have a high gain, good pulse height resolution and a fast response for MS applications. In this paper, these new assemblies are described referring to their structures, functions and characteristics. (orig.).

  11. A fast rise time high voltage pulse generator for bounded-wave EMP simulator

    International Nuclear Information System (INIS)

    A high voltage pulse generator with fast rise time is developed. The output wave of this generator is presented. The electromagnetic environment with 1.2 ns or 2.8 ns rise time and 50 ns pulse width can be produced when this generator is connected to bounded-wave EMP simulator which is used to investigate the EMP coupling effects of electrical equipment. (authors)

  12. Fast electron transport and heating in ultraintense laser pulse interaction with solid targets

    Science.gov (United States)

    Koenig, Michel; Amiranoff, Francois; Baton, Sophie; Gremillet, Laurent; Martinolli, Emanuele; Batani, Dimitri; Bernardinello, Andrea; Greison, Gabriella; Hall, Tom; Rabec Le Gloahec, Marc; Rousseaux, Christophe; Santos, Joao

    2000-10-01

    In the context of the fast electron transport in solid matter and the fast ignitor scheme, we report on results from ultraintense laser pulse interaction with thick targets. Experiments have been performed at LULI with the 100 TW CPA Nd:glass laser, at intensities up to a few 10^19 W/cm^2. Images obtained from classical and chirped-pulse time-resolved reflectometry diagnostics of the back-side target give evidence of the rear surface heating; the geometry and the dynamics of the energy deposition of the relativistic electrons flux into matter are also inferred.

  13. A Fast Pulsed Neutron Source for Time-of-Flight Detection of Nuclear Materials and Explosives

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, Mahadevan; Bures, Brian; James, Colt; Madden, Robert [Alameda Applied Sciences Corporation, 3077 Teagarden Street, San Leandro, CA 94577 (United States); Hennig, Wolfgang; Breus, Dimitry; Asztalos, Stephen; Sabourov, Konstantin [XIA LLC, 31057 Genstar Road, Hayward, CA 94544 (United States); Lane, Stephen [NSF Center for Biophotonics and School of Medicine, University of California Davis, Sacramento CA, 95817 (United States)

    2011-12-13

    AASC has built a fast pulsed neutron source based on the Dense Plasma Focus (DPF). The more current version stores only 100 J but fires at {approx}10-50 Hz and emits {approx}10{sup 6}n/pulse at a peak current of 100 kA. Both sources emit 2.45{+-}0.1 MeV(DD) neutron pulses of {approx}25-40 ns width. Such fast, quasi-monoenergetic pulses allow time-of-flight detection of characteristic emissions from nuclear materials or high explosives. A test is described in which iron targets were placed at different distances from the point neutron source. Detectors such as Stilbene and LaBr3 were used to capture inelastically induced, 847 keV gammas from the iron target. Shielding of the source and detectors eliminated most (but not all) of the source neutrons from the detectors. Gated detection, pulse shape analysis and time-of-flight discrimination enable separation of gamma and neutron signatures and localization of the target. A Monte Carlo simulation allows evaluation of the potential of such a fast pulsed source for a field-portable detection system. The high rep-rate source occupies two 200 liter drums and uses a cooled DPF Head that is <500 cm{sup 3} in volume.

  14. Protecting and accelerating adiabatic passage with time-delayed pulse sequences

    CERN Document Server

    Sampedro, Pablo; Sola, Ignacio R

    2016-01-01

    Using numerical simulations of two-photon electronic absorption with femtosecond pulses in Na$_2$ we show that: i) it is possible to avoid the characteristic saturation or dumped Rabi oscillations in the yield of absorption by time-delaying the laser pulses; ii) it is possible to accelerate the onset of adiabatic passage by using the vibrational coherence starting in a wave packet; and iii) it is possible to prepare the initial wave packet in order to achieve full state-selective transitions with broadband pulses. The findings can be used, for instance, to achieve ultrafast adiabatic passage by light-induced potentials and understand its intrinsic robustness.

  15. Protecting and accelerating adiabatic passage with time-delayed pulse sequences.

    Science.gov (United States)

    Sampedro, Pablo; Chang, Bo Y; Sola, Ignacio R

    2016-05-21

    Using numerical simulations of two-photon electronic absorption with femtosecond pulses in Na2 we show that: (i) it is possible to avoid the characteristic saturation or dumped Rabi oscillations in the yield of absorption by time-delaying the laser pulses; (ii) it is possible to accelerate the onset of adiabatic passage by using the vibrational coherence starting in a wave packet; and (iii) it is possible to prepare the initial wave packet in order to achieve full state-selective transitions with broadband pulses. The findings can be used, for instance, to achieve ultrafast adiabatic passage by light-induced potentials and understand its intrinsic robustness. PMID:27125342

  16. Single-Shot Femtosecond Electron Diffraction with Laser-Accelerated Electrons: Experimental Demonstration of Electron Pulse Compression

    International Nuclear Information System (INIS)

    We report the first experimental demonstration of longitudinal compression of laser-accelerated electron pulses. Accelerated by a femtosecond laser pulse with an intensity of 1018 W/cm2, an electron pulse with an energy of around 350 keV and a relative momentum spread of about 10-2 was compressed to a 500-fs pulse at a distance of about 50 cm from the electron source by using a magnetic pulse compressor. This pulse was used to generate a clear diffraction pattern of a gold crystal in a single shot. This method solves the space-charge problem in ultrafast electron diffraction.

  17. Stable radiation pressure acceleration of ions by suppressing transverse Rayleigh-Taylor instability with multiple Gaussian pulses

    Science.gov (United States)

    Zhou, M. L.; Liu, B.; Hu, R. H.; Shou, Y. R.; Lin, C.; Lu, H. Y.; Lu, Y. R.; Gu, Y. Q.; Ma, W. J.; Yan, X. Q.

    2016-08-01

    In the case of a thin plasma slab accelerated by the radiation pressure of an ultra-intense laser pulse, the development of Rayleigh-Taylor instability (RTI) will destroy the acceleration structure and terminate the acceleration process much sooner than theoretical limit. In this paper, a new scheme using multiple Gaussian pulses for ion acceleration in a radiation pressure acceleration regime is investigated with particle-in-cell simulation. We found that with multiple Gaussian pulses, the instability could be efficiently suppressed and the divergence of the ion bunch is greatly reduced, resulting in a longer acceleration time and much more collimated ion bunch with higher energy than using a single Gaussian pulse. An analytical model is developed to describe the suppression of RTI at the laser-plasma interface. The model shows that the suppression of RTI is due to the introduction of the long wavelength mode RTI by the multiple Gaussian pulses.

  18. Ultra-fast facial topometry using pulsed holography

    Science.gov (United States)

    Thelen, Andrea; Frey, Susanne; Hirsch, Sven; Ladrière, Natalie; Hering, Peter

    2006-02-01

    For planning, simulation and documentation of interventions in maxillofacial surgery high resolving soft tissue information of the human face in upright position is needed. This information can be gained by holographic methods, which allow a recording of the whole face in an extremely short time period, so that no movement artefacts occur. The hologram is recorded with a single laser pulse of 25 ns duration and stored in photosensitive material. After automated wet-chemical processing, the hologram is optically reconstructed with a cw-laser. During the optical reconstruction, a light field, which is a one-to-one three-dimensional representation of the recorded face, emerges at its original position and is digitized into a set of two-dimensional projections. Digital image processing leads to merging of these projections into a three-dimensional computer model. Besides the topometric information, a high resolving pixel precise texture is also extracted from the holographic reconstruction and used for the texturing of the computer models. The use of mirrors allows the simultaneous recording of three different views of the face with one laser pulse. The three different views of the face can be combined easily, because they are simultaneously recorded. Thus a recording range of approximately 270 degrees is achieved. In addition to the medical application, high resolving and textured computer models of faces are of tremendous importance for facial reconstruction in anthropology, forensic science and archaeology.

  19. Quantitative mapping of fast voltage pulses in tunnel junctions by plasmonic luminescence

    Science.gov (United States)

    Grosse, Christoph; Etzkorn, Markus; Kuhnke, Klaus; Loth, Sebastian; Kern, Klaus

    2013-10-01

    An optical read-out technique is demonstrated that enables mapping the time-dependent electrostatic potential in the tunnel junction of a scanning tunneling microscope with millivolt and nanosecond accuracy. We measure the time-dependent intensity of plasmonic light emitted from the tunnel junction upon excitation with a nanosecond voltage pulse. The light intensity is found to be a quantitative measure of the voltage between tip and sample. This permits non-invasive mapping of fast voltage transients directly at the tunnel junction. Knowledge of the pulse profile reaching the tunnel junction is applied to optimize the experiment's time response by actively shaping the incident pulses.

  20. Disposition of fuel elements from the Aberdeen and Sandia pulse reactor (SPR-II) assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Mckerley, Bill [Los Alamos National Laboratory; Bustamante, Jacqueline M [Los Alamos National Laboratory; Costa, David A [Los Alamos National Laboratory; Drypolcher, Anthony F [Los Alamos National Laboratory; Hickey, Joseph [Los Alamos National Laboratory

    2010-01-01

    We describe the disposition of fuel from the Aberdeen (APR) and the Sandia Pulse Reactors (SPR-II) which were used to provide intense neutron bursts for radiation effects testing. The enriched Uranium - 10% Molybdenum fuel from these reactors was shipped to the Los Alamos National Laboratory (LANL) for size reduction prior to shipment to the Savannah River Site (SRS) for final disposition in the H Canyon facility. The Shipper/Receiver Agreements (SRA), intra-DOE interfaces, criticality safety evaluations, safety and quality requirements and key materials management issues required for the successful completion of this project will be presented. This work is in support of the DOE Consolidation and Disposition program. Sandia National Laboratories (SNL) has operated pulse nuclear reactor research facilities for the Department of Energy since 1961. The Sandia Pulse Reactor (SPR-II) was a bare metal Godiva-type reactor. The reactor facilities have been used for research and development of nuclear and non-nuclear weapon systems, advanced nuclear reactors, reactor safety, simulation sources and energy related programs. The SPR-II was a fast burst reactor, designed and constructed by SNL that became operational in 1967. The SPR-ll core was a solid-metal fuel enriched to 93% {sup 235}U. The uranium was alloyed with 10 weight percent molybdenum to ensure the phase stabilization of the fuel. The core consisted of six fuel plates divided into two assemblies of three plates each. Figure 1 shows a cutaway diagram of the SPR-II Reactor with its decoupling shroud. NNSA charged Sandia with removing its category 1 and 2 special nuclear material by the end of 2008. The main impetus for this activity was based on NNSA Administrator Tom D'Agostino's six focus areas to reenergize NNSA's nuclear material consolidation and disposition efforts. For example, the removal of SPR-II from SNL to DAF was part of this undertaking. This project was in support of NNSA's efforts

  1. Accelerating protons to therapeutic energies with ultraintense, ultraclean, and ultrashort laser pulses

    OpenAIRE

    Bulanov, Stepan S.; Brantov, Andrei; Bychenkov, Valery Yu.; Chvykov, Vladimir; Kalinchenko, Galina; Matsuoka, Takeshi; Rousseau, Pascal; Reed, Stephen; Yanovsky, Victor; Krushelnick, Karl; Litzenberg, Dale William; Maksimchuk, Anatoly

    2008-01-01

    Proton acceleration by high-intensity laser pulses from ultrathin foils for hadron therapy is discussed. With the improvement of the laser intensity contrast ratio to 10−11 achieved on the Hercules laser at the University of Michigan, it became possible to attain laser-solid interactions at intensities up to 1022 W∕cm2 that allows an efficient regime of laser-driven ion acceleration from submicron foils. Particle-in-cell (PIC) computer simulations of proton acceleration in the directed Coulom...

  2. Ag nanoparticles formed by femtosecond pulse laser ablation in water: self-assembled fractal structures

    Energy Technology Data Exchange (ETDEWEB)

    Santillán, Jesica M. J. [CONICET La Plata-CIC, Centro de Investigaciones Ópticas (CIOp) (Argentina); Fernández van Raap, Marcela B., E-mail: raap@fisica.unlp.edu.ar; Mendoza Zélis, Pedro; Coral, Diego [CONICET, Instituto de Física La Plata (IFLP) (Argentina); Muraca, Diego [Universidade Estadual de Campinas, Instituto de Física “Gleb Wataghin” (IFGW) (Brazil); Schinca, Daniel C.; Scaffardi, Lucía B., E-mail: lucias@ciop.unlp.edu.ar [CONICET La Plata-CIC, Centro de Investigaciones Ópticas (CIOp) (Argentina)

    2015-02-15

    We report for the first time on the formation of self-assembled fractals of spherical Ag nanoparticles (Nps) fabricated by femtosecond pulse laser ablation of a solid silver target in water. Fractal structures grew both in two and three Euclidean dimensions (d). Ramified-fractal assemblies of 2 nm height and 5–14 μm large, decorated with Ag Nps of 3 nm size, were obtained in a 2d geometry when highly diluted drops of colloidal suspension were dried at a fast heating rate over a mica substrate. When less-diluted drops were dried at slow heating rate, isolated single Nps or rosette-like structures were formed. Fractal aggregates about 31 nm size in 3d geometry were observed in the as-prepared colloidal suspension. Electron diffraction and optical extinction spectroscopy (OES) analyses performed on the samples confirmed the presence of Ag and Ag{sub 2}O. The analysis of the optical extinction spectrum, using the electrostatic approximation of Mie theory for small spheres, showed the existence of Ag bare core, Ag–Ag{sub 2}O and air–Ag core–shell Nps, Ag–Ag{sub 2}O being the most frequent type [69 % relative abundance (r.a.)]. Core-size and shell-thickness distribution was derived from OES. In situ scattering measurements of the Ag colloidal suspension, carried out by small-angle X-ray scattering, indicate a mass fractal composed of packaged 〈D{sub SAXS}〉 = (5 ± 1) nm particles and fractal dimension d{sub f} = 2.5. Ex situ atomic force microscopy imaging displayed well-ramified structures, which, analyzed with box-counting method, yield a fractal dimension d{sub f} = 1.67. The growing behavior of these 2d and 3d self-assembled fractals is consistent with the diffusion-limited aggregation model.

  3. Complex envelope control of pulsed accelerating fields in superconducting cavities

    CERN Document Server

    Czarski, T

    2010-01-01

    A digital control system for superconducting cavities of a linear accelerator is presented in this work. FPGA (Field Programmable Gate Arrays) based controller, managed by MATLAB, was developed to investigate a novel firmware implementation. The LLRF - Low Level Radio Frequency system for FLASH project in DESY is introduced. Essential modeling of a cavity resonator with signal and power analysis is considered as a key approach to the control methods. An electrical model is represented by the non-stationary state space equation for the complex envelope of the cavity voltage driven by the current generator and the beam loading. The electromechanical model of the superconducting cavity resonator including the Lorentz force detuning has been developed for a simulation purpose. The digital signal processing is proposed for the field vector detection. The field vector sum control is considered for multiple cavities driven by one klystron. An algebraic, complex domain model is proposed for the system analysis. The c...

  4. Intense giga watt pulsed electron accelerators for HPM and FXR generation

    International Nuclear Information System (INIS)

    New development in the field of high power pulsed accelerator is the KALI-30GW system capable of delivering 1 MV, 30 kA, 80 ns electron beam pulses. This system has all indigenous components including energy storage capacitors and transformer oil as the dielectric and insulating medium. The energy balance in each stage of sub-system has been maintained to have better efficiency of energy transfer and improving the life of associated insulators. It has been used for high power microwaves generation using reflex triode and relativistic magnetron successfully. A suitable flash-X-rays gun is also designed and developed for this system. The results of these experiments will be presented in this paper. In order to make pulsed electron accelerators compact and repetitive, two more systems are developed in Accelerator and Pulse Power Division, BTDG, BARC which are Linear Induction Accelerator (LIA-400) tested up to 400 kV, 4 kA,100 ns,1-300 Hz and repetitive Marx generator rated for 300 kV, 12 kA, 300 ns, 10 Hz are also developed which are being used for Intentional ElectroMagnetic Interference (IEMI) studies of various electronics circuitry/devices. A few experimental investigations are also done using these systems to understand the effect of cathode material, relativistic electron beam and flash-X-rays emission. Latest results are being illustrated. (author)

  5. Dosimetry and fast neutron energies characterization of photoneutrons produced in some medical linear accelerators

    Science.gov (United States)

    Khaled, N. E.; Attalla, E. M.; Ammar, H.; Khalil, W.

    2011-12-01

    This work focusses on the estimation of induced photoneutrons energy, fluence, and strength using nuclear track detector (NTD) (CR-39). Photoneutron energy was estimated for three different linear accelerators, LINACs as an example for the commonly used accelerators. For high-energy linear accelerators, neutrons are produced as a consequence of photonuclear reactions in the target nuclei, accelerator head, field-flattening filters and beam collimators, and other irradiated objects. NTD (CR-39) is used to evaluate energy and fluence of the fast neutron. Track length is used to estimate fast photoneutrons energy for linear accelerators (Elekta 10 MV, Elekta 15 MV, and Varian 15 MV). Results show that the estimated neutron energies for the three chosen examples of LINACs reveals neutron energies in the range of 1-2 MeV for 10 and 15 MV X-ray beams. The fluence of neutrons at the isocenter (Φtotal) is found to be (4×106 n cm2 Gy-1) for Elekta machine 10 MV. The neutron source strengths Q are calculated. It was found to be 0.2×1012 n Gy-1 X-ray at the isocenter. This work represents simple, low cost, and accurate methods of measuring fast neutrons dose and energies.

  6. Host-based data acquisition system to control pulsed facilities of the accelerator

    Science.gov (United States)

    Zamriy, V. N.

    2016-09-01

    The report discusses development of the host-based system to carry out timed measurements and data acquisition for the control of pulsed facilities of the accelerator. We consider modes of timing and allocation of operations of channels and the system node. The time of any working cycle of the pulsed facilities, rate of a data flow and an amount of serviced channels are coordinated with operation characteristics of the system node. Estimations of the readout rate of the data and the waiting time demonstrate the system efficiency. The technique has been developed to provide checking of groups of pulse parameters and control the facilities of the linear accelerator of electrons LUE-200 of the neutron source IREN.

  7. Increased efficiency of ion acceleration by using femtosecond laser pulses at higher harmonic frequency

    CERN Document Server

    Psikal, Jan; Weber, Stefan; Margarone, Daniele

    2014-01-01

    The influence of laser frequency on laser-driven ion acceleration is investigated by means of two-dimensional particle-in-cell simulations. When ultrashort intense laser pulse at higher harmonic frequency irradiates a thin solid foil, the target may become relativistically transparent for significantly lower laser pulse intensity compared to irradiation at fundamental laser frequency. The relativistically induced transparency results in an enhanced heating of hot electrons as well as increased maximum energies of accelerated ions and their numbers. Our simulation results have shown the increase of maximum proton energy and of the number of high-energy protons by a factor of 2-3 after the interaction of an ultrashort laser pulse with maximum intensity $7 \\times 10^{21}~\\rm{W/cm^2}$ and a fully ionized plastic foil of realistic density when switching from the fundamental frequency to the third harmonics.

  8. The vestibular evoked response to linear, alternating, acceleration pulses without acoustic masking as a parameter of vestibular function

    NARCIS (Netherlands)

    Oei, MLYM; Segenhout, JM; Wit, HP; Albers, FWJ

    2001-01-01

    In this study, short latency vestibular evoked potentials (VsEPs) were recorded in five guinea pigs in response to alternating linear acceleration pulses with and without acoustic masking. A steel bolt was implanted in the skull and coupled to a shaker. Linear acceleration pulses (n = 400) in upward

  9. The mechatronic design of a fast wire scanner in IHEP U-70 accelerator

    Science.gov (United States)

    Baranov, V. T.; Makhov, S. S.; Savin, D. A.; Terekhov, V. I.

    2016-10-01

    This paper presents the mechatronic design of a fast wire scanner based on a servomotor. The design of the wire scanner is motivated by the need to measure the transverse profile of the high power proton and carbon beams at the IHEP U-70 accelerator. This paper formulates the requirements to the fast wire scanner system for the high intensity proton beam at the U-70 accelerator. The results on the design of electro-mechanical device for the wire scanner with a wire traveling speed 10-20 m/s are presented. The solution consists in a brushless servomotor and standard motor control electronics. High radiation levels in the accelerator enclosure dictate the use of a resolver as the position feedback element.

  10. Controlled nanostructrures formation by ultra fast laser pulses for color marking

    OpenAIRE

    Dusser, Benjamin; Sagan, Sbigniew; Soder, Hervé; Faure, Nicolas; Colombier, Jean-Philippe; Jourlin, Michel; Audouard, Eric

    2010-01-01

    International audience; Precise nanostructuration of surface and the subsequent upgrades in material properties is a strong outcome of ultra fast laser irradiations. Material characteristics can be designed on mesoscopic scales, carrying new optical properties. We demonstrate in this work, the possibility of achieving material modifications using ultra short pulses, via polarization dependent structures generation, that can generate specific color patterns. These oriented nanostructures creat...

  11. Monte Carlo simulations to advance characterisation of landmines by pulsed fast/thermal neutron analysis

    NARCIS (Netherlands)

    Maucec, M.; Rigollet, C.

    2004-01-01

    The performance of a detection system based on the pulsed fast/thermal neutron analysis technique was assessed using Monte Carlo simulations. The aim was to develop and implement simulation methods, to support and advance the data analysis techniques of the characteristic gamma-ray spectra, potentia

  12. Railguns and plasma accelerators: arc armatures, pulse power sources and US patents

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, O.M. Jr.

    1980-11-01

    Railguns and plasma accelerators have the potential for use in many basic and applied research projects, such as in creating high-pressures for equation-of-state studies and in impact fusion. A brief review of railguns and plasma accelerators with references is presented. Railgun performance is critically dependent on armature operation. Plasma arc railgun armatures are addressed. Pulsed power supplies for multi-stage railguns are considered. This includes brief comments on the compensated pulsed alternator, or compulsator, rotating machinery, and distributed energy sources for railguns. References are given at the end of each section. Appendix A contains a brief review of the US Patents on multi-staging techniques for electromagnetic accelerators, plasma propulsion devices, and electric guns.

  13. Railguns and plasma accelerators: arc armatures, pulse power sources and US patents

    International Nuclear Information System (INIS)

    Railguns and plasma accelerators have the potential for use in many basic and applied research projects, such as in creating high-pressures for equation-of-state studies and in impact fusion. A brief review of railguns and plasma accelerators with references is presented. Railgun performance is critically dependent on armature operation. Plasma arc railgun armatures are addressed. Pulsed power supplies for multi-stage railguns are considered. This includes brief comments on the compensated pulsed alternator, or compulsator, rotating machinery, and distributed energy sources for railguns. References are given at the end of each section. Appendix A contains a brief review of the US Patents on multi-staging techniques for electromagnetic accelerators, plasma propulsion devices, and electric guns

  14. The COBRA accelerator pulsed-power driver for Cornell/Sandia ICF research

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.L.; Ingwersen, P.; Bennett, L.F.; Boyes, J.D. [Sandia National Labs., Albuquerque, NM (United States); Anderson, D.E.; Greenly, J.B.; Sudan, R.N.; Hammer, D.A. [Cornell Univ., Ithaca, NY (United States)

    1995-07-01

    This paper introduces and describes the new Cornell Beam Research Accelerator, COBRA, the result of a three and one-half year collaboration. The flexible 4 to 5-MV, 100 to 250-kA, 46-ns pulse width accelerator is based on a four-cavity Inductive Voltage Adder (IVA) design. In addition to being a mix of new and existing components, COBRA is unique in the sense that each cavity is driven by a single pulse forming line, and the IVA output polarity may be reversed by rotating the cavities 1800 about their vertical axis. Our tests with negative high voltage on the inner MITL stalk indicate that the vacuum power flow has established reasonable azimuthal symmetry within about 2 ns (or 0.6 m) after the cavity output cap. Preliminary results with the accelerator, single cavity, and MITL are presented alone, with the design details and circuit model predictions.

  15. Solid-state fast voltage compensator for pulsed power applications requiring constant AC power consumption

    CERN Document Server

    Magallanes, Francisco Cabaleiro; Viarouge, Philippe; Cros, Jérôme

    2015-01-01

    This paper proposes a novel topological solution for pulsed power converters based on capacitor-discharge topologies, integrating a Fast Voltage Compensator which allows an operation at constant power consumption from the utility grid. This solution has been retained as a possible candidate for the CLIC project under study at CERN, which requires more than a thousand synchronously-operated klystron modulators producing a total pulsed power of almost 40 GW. The proposed Fast Voltage Compensator is integrated in the modulator such that it only has to treat the capacitor charger current and a fraction of the charging voltage, meaning that its dimensioning power and cost are minimized. This topology can be used to improve the AC power quality of any pulsed converters based on capacitor-discharge concept. A prototype has been built and exploited to validate the operating principle and demonstrate the benefits of the proposed solution.

  16. Fast acceleration of 2D wave propagation simulations using modern computational accelerators.

    Directory of Open Access Journals (Sweden)

    Wei Wang

    Full Text Available Recent developments in modern computational accelerators like Graphics Processing Units (GPUs and coprocessors provide great opportunities for making scientific applications run faster than ever before. However, efficient parallelization of scientific code using new programming tools like CUDA requires a high level of expertise that is not available to many scientists. This, plus the fact that parallelized code is usually not portable to different architectures, creates major challenges for exploiting the full capabilities of modern computational accelerators. In this work, we sought to overcome these challenges by studying how to achieve both automated parallelization using OpenACC and enhanced portability using OpenCL. We applied our parallelization schemes using GPUs as well as Intel Many Integrated Core (MIC coprocessor to reduce the run time of wave propagation simulations. We used a well-established 2D cardiac action potential model as a specific case-study. To the best of our knowledge, we are the first to study auto-parallelization of 2D cardiac wave propagation simulations using OpenACC. Our results identify several approaches that provide substantial speedups. The OpenACC-generated GPU code achieved more than 150x speedup above the sequential implementation and required the addition of only a few OpenACC pragmas to the code. An OpenCL implementation provided speedups on GPUs of at least 200x faster than the sequential implementation and 30x faster than a parallelized OpenMP implementation. An implementation of OpenMP on Intel MIC coprocessor provided speedups of 120x with only a few code changes to the sequential implementation. We highlight that OpenACC provides an automatic, efficient, and portable approach to achieve parallelization of 2D cardiac wave simulations on GPUs. Our approach of using OpenACC, OpenCL, and OpenMP to parallelize this particular model on modern computational accelerators should be applicable to other

  17. Pulse radiolysis with (sub) nanosecond time resolution using a 3 MV electron accelerator

    International Nuclear Information System (INIS)

    In this thesis the development of equipment for pulse radiolysis is described and the application of the technique to time-resolved measurements of the fluorescence emission of excited states formed after irradiation of some alkanes is dealt with. A review is given of the development of the pulsed 3MV Van de Graaf electron accelerator for the generation of subnanosecond electron beam pulses and of the development of the equipment for optical detection as accomplished by the author. The initial stage of a further development for shorter pulses and higher time resolution is briefly discussed. A collection of papers on the development of apparatus and a collection of papers dealing with the results obtained from measurements of the fluorescence of excited states, formed by the recombination of electrons and ions in irradiated alkanes such as cyclohexane and the decalines, are included. (Auth.)

  18. Studies of the pulse-line accelerator using a circuit model

    International Nuclear Information System (INIS)

    This note describes a simple model developed to explore some of the properties of the pulse-line ion accelerator [1], here represented as a series of lumped elements, in the general parameter regime for the ''NDCX-1d'' experiments. The goals of this modeling are: to understand the evolution of various possible input pulses in the presence of dispersive effects and imperfect termination of the line; to examine scenarios for beam acceleration; and to explore the effects of ''beam loading'', that is, changes to the voltages along the helical line that result from the interaction of the beam's return current with the ''circuitry'' of that line. In Section 1 below, the model is described and the method of solution outlined; in Section 2, a low-current example of beam acceleration is presented; in Section 3, runs are presented showing the development of beam loading-induced voltages as model pulses are followed; in section 4, the modeling of a higher-current beam under acceleration is presented, and the effects of beam loading quantified; and in section 5, a brief summary of complementary efforts and of plans to extend the modeling is presented

  19. Growth Processes for a pulse of leptin in fasting human subjects

    Directory of Open Access Journals (Sweden)

    Geetha.T

    2014-12-01

    Full Text Available A meal-like transient hyperinsulinemia and hyperglycemia, with a pulse of xamethasone, increased serum leptin levels from baseline by 54±21% at 9 h (P = 0.038. In the absence of transient hyperglycemia, leptin increased significantly after doses of both insulin and xamethasone. The effect of insulin was dose-dependent, with a larger increment of serum leptin at 9 h after the highest dose of insulin (75.2±15.7% vs 21.3±8.5%, P = 0.013. Fasting, with or without dexamethasone, resulted in a significant 20% decrease in leptin from morning basal levels. Conversely, the administration of a pulse of insulin and glucose, in the absence of dexamethasone, prevented the drop in serum leptin observed during fasting, regardless of the insulin dose or the serum glucose elevation. The permissive effect of dexamethasone, a single pulse of insulin triggered a rise in serum leptin in humans, even in the absence of transient hyperglycemia. A single pulse of insulin with glucose can prevent the drop in serum leptin normally observed during fasting. We also find the Growth Processes of Leptin

  20. Measurements with the fast repetitive multi-pulse Edge Thomson Scattering system on TEXTOR

    Energy Technology Data Exchange (ETDEWEB)

    Uzgel, Evren; Pospieszczyk, Albrecht; Unterberg, Bernhard [IEF-Plasmaphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Kantor, Mikhail [Ioffe Institute, RAS, Saint Petersburg (Russian Federation); Meiden, Hennie van der; Jaspers, Roger [FOM-Institute for Plasma Physics Rijnhuizen, Nieuwegein (Netherlands)

    2008-07-01

    A fast repetitive multi-pulse Edge Thomson Scattering system is in operation since March 2006 and provides a sophisticated tool for the study of transport processes in the edge region of the tokamak TEXTOR. The specially designed viewing optics enables the study of the dynamics of fast plasma phenomena with high spatial resolution at the plasma edge. Various measurements under different plasma conditions were performed where the influence of resonant magnetic perturbations generated by the Dynamic Ergodic Divertor on fast electron transport in the edge region was a point of emphasis. The electron density and temperature profiles obtained are compared with other edge diagnostics based on different measuring principles. The system utilizes a ruby laser delivering bursts of 15 pulses each with a pulse energy of about 15 J. The TEXTOR plasma itself is inside the laser cavity where the double-pass system allows high laser energies of each laser pulse through the plasma. The edge system (170 mm) has 98 spatial channels of 1.7 mm each. The lower detection limit of the edge system for T{sub e} is observed to be 30 eV.

  1. Measurements with the fast repetitive multi-pulse Edge Thomson scattering system on TEXTOR

    Energy Technology Data Exchange (ETDEWEB)

    Uzgel, Evren; Pospieszczyk, Albrecht; Unterberg, Bernhard [Institut fuer Plasmaphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Kantor, Mikhail; Kouprienko, Denis [Ioffe Institute, RAS, Saint Petersburg (Russian Federation); Meiden, Hennie van der; Oyevaar, Theo; Jaspers, Roger [FOM-Institute for Plasma Physics Rijnhuizen, Nieuwegein (Netherlands)

    2007-07-01

    A fast repetitive multi-pulse Edge Thomson Scattering system is in operation since March 2006 and provides a sophisticated tool for the study of transport processes in the edge region of the tokamak TEXTOR. The specially designed viewing optics enables the study of the dynamics of fast plasma phenomena with high spatial resolution at the plasma edge. Various measurements under different plasma conditions were performed where the influence of resonant magnetic perturbations generated by the Dynamic Ergodic Divertor on fast electron transport in the edge region was a point of emphasis. The electron density and temperature profiles obtained will be compared with other edge diagnostics based on different measuring principles. The system utilizes a ruby laser delivering bursts of 15 pulses each with a pulse energy of about 15 J. The TEXTOR plasma itself is inside the laser cavity where the double-pass system allows high laser energies of each laser pulse through the plasma. The new edge system (170 mm) has 98 spatial channels of 1.7 mm each. The lower detection limit of the edge system for T{sub e} is observed to be 30 eV.

  2. Design trade-off study for a large volume short pulse neutron assembly

    International Nuclear Information System (INIS)

    There is a continuing need within the radiation effects research community for more intense and larger volume pulsed neutron facilities. To fulfill these requirements a study was performed to examine conceptual designs for a neutron assembly that could produce high-intensity, short pulse neutron environments over a large experimental volume. The desired system characteristics were a cylindrical experimental cavity 60 inches long (152.4 cm) with a 24 inch diameter (60.96 cm), a cavity fluence of φr = 8x1014 n/cm2, and a neutron pulse width of τ = 10--20 μs. Attention was focused on booster assemblies which have been studied since the 1950s at Harwell, General Atomic, and at Sandia National Laboratories. Five conceptual designs were developed and evaluated. Only a two-stage coupled core design with a NpO2 primary core assembly was found to meet the design goals. A program is proposed to refine the design and to construct this nuclear assembly. The proposed three-phase effort represents a conservative approach that will yield large increases in the experiment volume even if the final coupled-core design is not realized

  3. Assembly and installation of the 2 MeV FMIT accelerator

    International Nuclear Information System (INIS)

    The front end of the 35-MeV Fusion Materials Irradiation Test (FMIT) Facility accelerator is being assembled and installed at Los Alamos. The machine ultimately will produce a 500-kW continuous-duty beam at 5 MeV, although only the first 2 MeV will be installed this year. The 2-MeV system will include the most-powerful radio-frequency quadrupole (RFQ) in existence. The assembly and installation of the hardware are described, along with the unique problems arising from the large size and high power of the components involved

  4. Laser triggered injection of electrons in a laser wakefield accelerator with the colliding pulse method

    International Nuclear Information System (INIS)

    An injection scheme for a laser wakefield accelerator that employs a counter propagating laser (colliding with the drive laser pulse, used to generate a plasma wake) is discussed. The threshold laser intensity for electron injection into the wakefield was analyzed using a heuristic model based on phase-space island overlap. Analysis shows that the injection can be performed using modest counter propagating laser intensity a1 0 = 1.0. Preliminary experiments were preformed using a drive beam and colliding beam. Charge enhancement by the colliding pulse was observed. Increasing the signal-to-noise ratio by means of a preformed plasma channel is discussed

  5. Electron acceleration by tightly focused radially polarized few-cycle laser pulses

    Institute of Scientific and Technical Information of China (English)

    Liu Jin-Lu; Sheng Zheng-Ming; Zheng Jun

    2012-01-01

    Within the framework of plane-wave angular spectrum analysis of the electromagnetic field structure,a solution valid for tightly focused radially polarized few-cycle laser pulses propagating in vacuum is presented.The resulting field distribution is significantly different from that based on the paraxial approximation for pulses with either small or large beam diameters.We compare the electron accelerations obtained with the two solutions and find that the energy gain obtained with our new solution is usually much larger than that with the paraxial approximation solution.

  6. Monte Carlo modeling and analyses of YALINA- booster subcritical assembly Part II : pulsed neutron source.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, M. Y. A.; Rabiti, C.; Nuclear Engineering Division

    2008-10-22

    One of the most reliable experimental methods for measuring the kinetic parameters of a subcritical assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology for characterizing the kinetic parameters of a subcritical assembly using the Sjoestrand method, which allows comparing the analytical and experimental time dependent reaction rates and the reactivity measurements. In this methodology, the reaction rate, detector response, is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the fission delayed neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction is vanished. The obtained reaction rate is superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The new calculation methodology has shown an excellent agreement with the experimental results available from the YALINA-Booster facility of Belarus. The facility has been driven by a Deuterium-Deuterium or Deuterium-Tritium pulsed neutron source and the (n,p) reaction rate has been experimentally measured by a {sup 3}He detector. The MCNP calculation has utilized the weight window and delayed neutron biasing variance reduction techniques since the detector volume is small compared to the assembly volume. Finally, this methodology was used to calculate the IAEA benchmark of the YALINA-Booster experiment.

  7. Transporting laser-accelerated protons by a pulsed solenoid to a CH- DTL

    International Nuclear Information System (INIS)

    This study demonstrates the transporting and focusing of laser-accelerated protons at energies of ten to several tens of MeV, by a pulsed magnetic solenoid with a field gradient up to 18 T. The unique features of the protons distribution like extremely small emittances and high yield of the order of 1013 protons per shot, make them attractive for study. With respect to transit energies further acceleration by matching into rf linac seems adequate. The bunch injection into a proposed CH- structure is under investigation at IAP Frankfurt. Options and simulation tools are presented.

  8. Controls for a Pulsed Ion Accelerator Using Apache Cassandra (No-SQL) and ZMQ

    CERN Document Server

    Persaud, A; Stettler, M W; Vytla, V K

    2015-01-01

    We report on updates to the accelerator controls for the Neutral Drift Compression Experiment II, a pulsed accelerator for heavy ions. The control infrastructure is built around a LabVIEW interface combined with an Apache Cassandra (No-SQL) backend for data archiving. Recent upgrades added the storing and retrieving of device settings into the database, as well as adding ZMQ as a message broker that replaces LabVIEW's shared variables. Converting to ZMQ also allows easy access using other programming languages, such as Python.

  9. Investigation of longitudinal proton acceleration in exploded targets irradiated by intense short-pulse laser

    Energy Technology Data Exchange (ETDEWEB)

    Gauthier, M. [LULI, École Polytechnique, CNRS, CEA, UPMC, route de Saclay, 91128 Palaiseau (France); CEA, DAM, DIF, 91297 Arpajon (France); Lévy, A. [LULI, École Polytechnique, CNRS, CEA, UPMC, route de Saclay, 91128 Palaiseau (France); Sorbonne Universités, UPMC, Paris 06, CNRS, INSP, UMR 7588, F-75005, Paris (France); D' Humières, E.; Beaucourt, C.; Breil, J.; Feugeas, J. L.; Nicolaï, P.; Tikhonchuk, V. [Univ. Bordeaux, CNRS, CEA, UMR 5107, F-33400 Talence (France); Glesser, M. [LULI, École Polytechnique, CNRS, CEA, UPMC, route de Saclay, 91128 Palaiseau (France); INRS-EMT, Varennes, PQ J3X 1S2 (Canada); Albertazzi, B. [LULI, École Polytechnique, CNRS, CEA, UPMC, route de Saclay, 91128 Palaiseau (France); Univ. Bordeaux, CNRS, CEA, UMR 5107, F-33400 Talence (France); Chen, S. N.; Dervieux, V.; Fuchs, J. [LULI, École Polytechnique, CNRS, CEA, UPMC, route de Saclay, 91128 Palaiseau (France); Pépin, H. [INRS-EMT, Varennes, PQ J3X 1S2 (Canada); Antici, P. [LULI, École Polytechnique, CNRS, CEA, UPMC, route de Saclay, 91128 Palaiseau (France); INRS-EMT, Varennes, PQ J3X 1S2 (Canada); Dipartimento SBAI, Universita di Roma “Sapienza,” Via A. Scarpa 16, 00161 Rome (Italy)

    2014-01-15

    It was recently shown that a promising way to accelerate protons in the forward direction to high energies is to use under-dense or near-critical density targets instead of solids. Simulations have revealed that the acceleration process depends on the density gradients of the plasma target. Indeed, under certain conditions, the most energetic protons are predicted to be accelerated by a collisionless shock mechanism that significantly increases their energy. We report here the results of a recent experiment dedicated to the study of longitudinal ion acceleration in partially exploded foils using a high intensity (∼5 × 10{sup 18} W/cm{sup 2}) picosecond laser pulse. We show that protons accelerated using targets having moderate front and rear plasma gradients (up to ∼8 μm gradient length) exhibit similar maximum proton energy and number compared to proton beams that are produced, in similar laser conditions, from solid targets, in the well-known target normal sheath acceleration regime. Particle-In-Cell simulations, performed in the same conditions as the experiment and consistent with the measurements, allow laying a path for further improvement of this acceleration scheme.

  10. Design of long-pulse fast wave current drive antennas for DIII-D

    Science.gov (United States)

    Baity, F. W.; Batchelor, D. B.; Bills, K. C.; Fogelman, C. H.; Jaeger, E. F.; Ping, J. L.; Riemer, B. W.; Ryan, P. M.; Stallings, D. C.; Taylor, D. J.; Yugo, J. J.

    1994-10-01

    Two new long-pulse fast wave current drive (FWCD) antennas will be installed on DIII-D in early 1994. These antennas will increase the available FWCD power from 2 MW to 6 MW for pulse lengths of up to 2 s, and to 4 MW for up to 10 s. Power for the new antennas is from two ASDEX-type 30- to 120-MHz transmitters. When operated at 90° phasing into a low-density plasma (˜4×1019m-3) with hot electrons (˜10 keV), these two new antennas are predicted to drive approximately 1 MA of plasma current.

  11. Ion acceleration in non-equilibrium plasmas driven by fast drifting electron

    Energy Technology Data Exchange (ETDEWEB)

    Castro, G. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S.Sofia 64, 95123 Catania (Italy); Di Bartolo, F., E-mail: fdibartolo@unime.it [Università di Messina, V.le F. Stagno D’Alcontres 31, 98166, Messina (Italy); Gambino, N. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Metodologie Fisiche e Chimiche per L’ingegneria, Viale A.Doria 6, 95125 Catania (Italy); Mascali, D. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); CSFNSM, Viale A. Doria 6, 95125 Catania (Italy); Romano, F.P. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); CNR-IBAM Via Biblioteca 4, 95124 Catania (Italy); Anzalone, A.; Celona, L.; Gammino, S. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Di Giugno, R. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S.Sofia 64, 95123 Catania (Italy); Lanaia, D. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Miracoli, R. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S.Sofia 64, 95123 Catania (Italy); Serafino, T. [CSFNSM, Viale A. Doria 6, 95125 Catania (Italy); Tudisco, S. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); CSFNSM, Viale A. Doria 6, 95125 Catania (Italy)

    2013-05-01

    We hereby present results on ion acceleration mechanisms in non equilibrium plasmas generated by microwaves or high intensity laser pulses. Experiments point out that in magnetized plasmas X–B conversion takes place for under resonance values of the magnetic field, i.e. an electromagnetic mode is converted into an electrostatic wave. The strong self-generated electric field, of the order of 10{sup 7} V/m, causes a E × B drift which accelerates both ions and electrons, as it is evident by localized sputtering in the plasma chamber. These fields are similar (in magnitude) to the ones obtainable in laser generated plasmas at intensity of 10{sup 12} W/cm{sup 2}. In this latter case, we observe that the acceleration mechanism is driven by electrons drifting much faster than plasma bulk, thus generating an extremely strong electric field ∼10{sup 7} V/m. The two experiments confirm that ions acceleration at low energy is possible with table-top devices and following complementary techniques: i.e. by using microwave-driven (producing CW beams) plasmas, or non-equilibrium laser-driven plasmas (producing pulsed beams). Possible applications involve ion implantation, materials surface modifications, ion beam assisted lithography, etc.

  12. Neutron pulse propagation in natural UO sub(2) subcritical assembly moderated by heavy water

    International Nuclear Information System (INIS)

    Short neutron bursts are fed to the graphite base of CAPITU, a D sub(2)O - natural uranium subcritical assembly. Due to the dispersive properties of the media the wave -components of the neutron pulses are attenuated and phase shifted along the axial direction. The experimental impulse response is Fourier transformed to yield the system's dispersion law, a relationship connecting the neutron diffusion parameters and the inverse complex relaxation length K (ω). The experimental results for five assemblies studied in CAPITU are compared with the theoretical dispersion law obtained from the two group diffusion theory. (author)

  13. Concept of a Staged FEL Enabled by Fast Synchrotron Radiation Cooling of Laser-Plasma Accelerated Beam by Solenoidal Magnetic Fields in Plasma Bubble

    CERN Document Server

    Seryi, Andrei; Andreev, Alexander; Konoplev, Ivan

    2016-01-01

    A novel method for generating GigaGauss solenoidal field in laser-plasma bubble, using screw-shaped laser pulses, has been recently presented in arXiv:1604.01259 [physics.plasm-ph]. Such magnetic fields enable fast synchrotron radiation cooling of the beam emittance of laser-plasma accelerated leptons. This recent finding opens a novel approach for design of laser-plasma FELs or colliders, where the acceleration stages are interleaved with laser-plasma emittance cooling stages. In this concept paper we present an outline of how a staged plasma-acceleration FEL could look like and discuss further studies needed to investigate the feasibility of the concept in detail.

  14. The influence of plasma density decreasement by pre-pulse on the laser wakefield acceleration

    Directory of Open Access Journals (Sweden)

    Ke-Gong Dong

    2011-12-01

    Full Text Available In the laser wakefield acceleration, the generation of electron beam is very sensitive to the plasma density. Not only the laser-wakefield interaction, but also the electron trapping and acceleration would be effected by the plasma density. However, the plasma density could be changed in the experiment by different reasons, which will result in the mismatch of parameters arranged initially. Forward Raman scattering spectrum demonstrated that the interaction density was decreased obviously in the experiment, which was verified by the pre-pulse conditions and two-dimensional particle-in-cell simulations. It was demonstrated that the plasma density was very important on the self-evolutions and energy coupling of laser pulse and wakefield, and eventually the energy spectrum of electron beam.

  15. Laser triggered injection of electrons in a laser wakefield accelerator with the colliding pulse method

    OpenAIRE

    Nakamura, K; Fubiani, G; Geddes, C. G. R.; Michel, P.; van Tilborg, J.; Toth, C; Esarey, E.; Schroeder, C. B.; Leemans, W. P.

    2004-01-01

    An injection scheme for a laser wakefield accelerator that employs a counterpropagating laser (colliding with the drive laser pulse, used to generate a plasma wake) is discussed. The threshold laser intensity for electron injection into the wakefield was analyzed using a heuristic model based on phase-space island overlap. Analysis shows that the injection can be performed using modest counterpropagating laser intensity a_1 < 0.5 for a drive laser intensity of a_0 = 1.0. Preliminary expe...

  16. Design of a boron neutron capture enhanced fast neutron therapy assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhonglu

    2006-08-01

    The use of boron neutron capture to boost tumor dose in fast neutron therapy has been investigated at several fast neutron therapy centers worldwide. This treatment is termed boron neutron capture enhanced fast neutron therapy (BNCEFNT). It is a combination of boron neutron capture therapy (BNCT) and fast neutron therapy (FNT). It is believed that BNCEFNT may be useful in the treatment of some radioresistant brain tumors, such as glioblastoma multiform (GBM). A boron neutron capture enhanced fast neutron therapy assembly has been designed for the Fermilab Neutron Therapy Facility (NTF). This assembly uses a tungsten filter and collimator near the patient's head, with a graphite reflector surrounding the head to significantly increase the dose due to boron neutron capture reactions. The assembly was designed using Monte Carlo radiation transport code MCNP version 5 for a standard 20x20 cm{sup 2} treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm{sup 2} collimation was 21.9% per 100-ppm {sup 10}B for a 5.0-cm tungsten filter and 29.8% for a 8.5-cm tungsten filter. The corresponding dose rate for the 5.0-cm and 8.5-cm thick filters were 0.221 and 0.127 Gy/min, respectively; about 48.5% and 27.9% of the dose rate of the standard 10x10 cm{sup 2} fast neutron treatment beam. To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm{sup 2} collimator. Five 1.0-cm thick 20x20 cm{sup 2} tungsten plates were used to obtain different filter thicknesses and graphite bricks/blocks were used to form a reflector. Measurements of the dose enhancement of the simplified assembly in a water-filled head phantom were performed using a pair of tissue-equivalent ion chambers. One of the ion chambers is loaded with 1000-ppm natural boron (184-ppm {sup 10}B) to measure dose due to boron neutron capture. The measured dose enhancement at 5.0-cm depth

  17. Design of a boron neutron capture enhanced fast neutron therapy assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhonglu [Georgia Inst. of Technology, Atlanta, GA (United States)

    2006-12-01

    The use of boron neutron capture to boost tumor dose in fast neutron therapy has been investigated at several fast neutron therapy centers worldwide. This treatment is termed boron neutron capture enhanced fast neutron therapy (BNCEFNT). It is a combination of boron neutron capture therapy (BNCT) and fast neutron therapy (FNT). It is believed that BNCEFNT may be useful in the treatment of some radioresistant brain tumors, such as glioblastoma multiform (GBM). A boron neutron capture enhanced fast neutron therapy assembly has been designed for the Fermilab Neutron Therapy Facility (NTF). This assembly uses a tungsten filter and collimator near the patient's head, with a graphite reflector surrounding the head to significantly increase the dose due to boron neutron capture reactions. The assembly was designed using Monte Carlo radiation transport code MCNP version 5 for a standard 20x20 cm2 treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm2 collimation was 21.9% per 100-ppm 10B for a 5.0-cm tungsten filter and 29.8% for a 8.5-cm tungsten filter. The corresponding dose rate for the 5.0-cm and 8.5-cm thick filters were 0.221 and 0.127 Gy/min, respectively; about 48.5% and 27.9% of the dose rate of the standard 10x10 cm2 fast neutron treatment beam. To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm2 collimator. Five 1.0-cm thick 20x20 cm2 tungsten plates were used to obtain different filter thicknesses and graphite bricks/blocks were used to form a reflector. Measurements of the dose enhancement of the simplified assembly in a water-filled head phantom were performed using a pair of tissue-equivalent ion chambers. One of the ion chambers is loaded with 1000-ppm natural boron (184-ppm 10B) to measure dose due to boron neutron capture. The

  18. Online calculation of the decay heat of assemblies at the Fast Flux Test Facility

    International Nuclear Information System (INIS)

    The Fast Flux Test Facility (FFTF) is utilized by the US Department of Energy and the international community as a fast reactor research tool. Its use includes, among other things, the irradiation testing of nuclear reactor fuels and materials required for the development of commercial liquid metal reactors. The decay heat rate of assemblies irradiated in the FFTF is an important parameter in establishing the transportation, examination, and storage of irradiated assemblies. The decay heat program which is maintained on a Cray super computer along with a Symphony speadsheet program running on a personal computer (PC) were created to accommodate this need. This unique synthesis provides a method of combing the capabilities of a mainframe computer with those of a PC

  19. FastGCN: a GPU accelerated tool for fast gene co-expression networks.

    Directory of Open Access Journals (Sweden)

    Meimei Liang

    Full Text Available Gene co-expression networks comprise one type of valuable biological networks. Many methods and tools have been published to construct gene co-expression networks; however, most of these tools and methods are inconvenient and time consuming for large datasets. We have developed a user-friendly, accelerated and optimized tool for constructing gene co-expression networks that can fully harness the parallel nature of GPU (Graphic Processing Unit architectures. Genetic entropies were exploited to filter out genes with no or small expression changes in the raw data preprocessing step. Pearson correlation coefficients were then calculated. After that, we normalized these coefficients and employed the False Discovery Rate to control the multiple tests. At last, modules identification was conducted to construct the co-expression networks. All of these calculations were implemented on a GPU. We also compressed the coefficient matrix to save space. We compared the performance of the GPU implementation with those of multi-core CPU implementations with 16 CPU threads, single-thread C/C++ implementation and single-thread R implementation. Our results show that GPU implementation largely outperforms single-thread C/C++ implementation and single-thread R implementation, and GPU implementation outperforms multi-core CPU implementation when the number of genes increases. With the test dataset containing 16,000 genes and 590 individuals, we can achieve greater than 63 times the speed using a GPU implementation compared with a single-thread R implementation when 50 percent of genes were filtered out and about 80 times the speed when no genes were filtered out.

  20. Experimental evidence of nonthermal acceleration of relativistic electrons by an intensive laser pulse.

    Science.gov (United States)

    Kuramitsu, Y; Nakanii, N; Kondo, K; Sakawa, Y; Mori, Y; Miura, E; Tsuji, K; Kimura, K; Fukumochi, S; Kashihara, M; Tanimoto, T; Nakamura, H; Ishikura, T; Takeda, K; Tampo, M; Kodama, R; Kitagawa, Y; Mima, K; Tanaka, K A; Hoshino, M; Takabe, H

    2011-02-01

    Nonthermal acceleration of relativistic electrons is investigated with an intensive laser pulse. An energy distribution function of energetic particles in the universe or cosmic rays is well represented by a power-law spectrum, therefore, nonthermal acceleration is essential to understand the origin of cosmic rays. A possible candidate for the origin of cosmic rays is wakefield acceleration at relativistic astrophysical perpendicular shocks. The wakefield is considered to be excited by large-amplitude precursor light waves in the upstream of the shocks. Substituting an intensive laser pulse for the large amplitude light waves, we performed a model experiment of the shock environments in a laboratory plasma. An intensive laser pulse was propagated in a plasma tube created by imploding a hollow polystyrene cylinder, as the large amplitude light waves propagated in the upstream plasma at an astrophysical shock. Nonthermal electrons were generated, and the energy distribution functions of the electrons have a power-law component with an index of ~2. We described the detailed procedures to obtain the nonthermal components from data obtained by an electron spectrometer.

  1. A thermal-hydraulic test rig for advanced fast reactor fuel assemblies

    International Nuclear Information System (INIS)

    A new design of fast reactor fuel assemblies has been proposed in which the pins are supported in grids attached to the wrapper by flexible skirts. Coolant mixing is enhanced by the skirts diverting flow into the cluster of pins at each grid. There are insufficient empirical data available for the detailed design of the skirt or for the input to computer calculations of flow and heat transfer. A test rig to provide these data has been designed and built. (author)

  2. Multiple quasi-monoenergetic electron beams from laser-wakefield acceleration with spatially structured laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.; Li, M. H.; Li, Y. F.; Wang, J. G.; Tao, M. Z.; Han, Y. J.; Zhao, J. R.; Huang, K.; Yan, W. C.; Ma, J. L.; Li, Y. T. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Chen, L. M., E-mail: lmchen@iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, D. Z. [Institute of High Energy Physics, CAS, Beijing 100049 (China); Chen, Z. Y. [Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621999 (China); Sheng, Z. M. [Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Zhang, J. [Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-08-15

    By adjusting the focus geometry of a spatially structured laser pulse, single, double, and treble quasi-monoenergetic electron beams were generated, respectively, in laser-wakefield acceleration. Single electron beam was produced as focusing the laser pulse to a single spot. While focusing the laser pulse to two spots that are approximately equal in energy and size and intense enough to form their own filaments, two electron beams were produced. Moreover, with a proper distance between those two focal spots, three electron beams emerged with a certain probability owing to the superposition of the diffractions of those two spots. The energy spectra of the multiple electron beams are quasi-monoenergetic, which are different from that of the large energy spread beams produced due to the longitudinal multiple-injection in the single bubble.

  3. 150 keV intense electron beam accelerator system with high repeated pulse

    International Nuclear Information System (INIS)

    A 150 keV electron beam accelerator system has been developed for wide application of high power particle beams. The new wire-ion-plasma electron gun has been adopted. The parameters are as follows: Output energy - 130-150 keV; Electron beam density - 250 mA/cm2; Pulse duration - 1 μs; Pulse rate 100 pps; Section of electron beam - 5 x 50 cm2. This equipment can be used to study repeated pulse CO2 laser, to be a preionizer of high power discharge excimer laser and to perform radiation curing process, and so on. The first part contains principle and design consideration. Next is a description of experimental arrangement. The remainder is devoted to describing experimental results and its application

  4. Fast simulation and optimization of pulse-train chemical exchange saturation transfer (CEST) imaging

    International Nuclear Information System (INIS)

    Chemical exchange saturation transfer (CEST) MRI has been increasingly applied to detect dilute solutes and physicochemical properties, with promising in vivo applications. Whereas CEST imaging has been implemented with continuous wave (CW) radio-frequency irradiation on preclinical scanners, pulse-train irradiation is often chosen on clinical systems. Therefore, it is necessary to optimize pulse-train CEST imaging, particularly important for translational studies. Because conventional Bloch–McConnell formulas are not in the form of homogeneous differential equations, the routine simulation approach simulates the evolving magnetization step by step, which is time consuming. Herein we developed a computationally efficient numerical solution using matrix iterative analysis of homogeneous Bloch–McConnell equations. The proposed algorithm requires simulation of pulse-train CEST MRI magnetization within one irradiation repeat, with 99% computation time reduction from that of conventional approach under typical experimental conditions. The proposed solution enables determination of labile proton ratio and exchange rate from pulse-train CEST MRI experiment, within 5% from those determined from quantitative CW-CEST MRI. In addition, the structural similarity index analysis shows that the dependence of CEST contrast on saturation pulse flip angle and duration between simulation and experiment was 0.98  ±  0.01, indicating that the proposed simulation algorithm permits fast optimization and quantification of pulse-train CEST MRI. (paper)

  5. Fast simulation and optimization of pulse-train chemical exchange saturation transfer (CEST) imaging.

    Science.gov (United States)

    Xiao, Gang; Sun, Phillip Zhe; Wu, Renhua

    2015-06-21

    Chemical exchange saturation transfer (CEST) MRI has been increasingly applied to detect dilute solutes and physicochemical properties, with promising in vivo applications. Whereas CEST imaging has been implemented with continuous wave (CW) radio-frequency irradiation on preclinical scanners, pulse-train irradiation is often chosen on clinical systems. Therefore, it is necessary to optimize pulse-train CEST imaging, particularly important for translational studies. Because conventional Bloch-McConnell formulas are not in the form of homogeneous differential equations, the routine simulation approach simulates the evolving magnetization step by step, which is time consuming. Herein we developed a computationally efficient numerical solution using matrix iterative analysis of homogeneous Bloch-McConnell equations. The proposed algorithm requires simulation of pulse-train CEST MRI magnetization within one irradiation repeat, with 99% computation time reduction from that of conventional approach under typical experimental conditions. The proposed solution enables determination of labile proton ratio and exchange rate from pulse-train CEST MRI experiment, within 5% from those determined from quantitative CW-CEST MRI. In addition, the structural similarity index analysis shows that the dependence of CEST contrast on saturation pulse flip angle and duration between simulation and experiment was 0.98 ± 0.01, indicating that the proposed simulation algorithm permits fast optimization and quantification of pulse-train CEST MRI. PMID:26020414

  6. Optical control of electron phase space in plasma accelerators with incoherently stacked laser pulses

    International Nuclear Information System (INIS)

    It is demonstrated that synthesizing an ultrahigh-bandwidth, negatively chirped laser pulse by incoherently stacking pulses of different wavelengths makes it possible to optimize the process of electron self-injection in a dense, highly dispersive plasma (n0∼1019 cm−3). Avoiding transformation of the driving pulse into a relativistic optical shock maintains a quasi-monoenergetic electron spectrum through electron dephasing and boosts electron energy far beyond the limits suggested by existing scaling laws. In addition, evolution of the accelerating bucket in a plasma channel is shown to produce a background-free, tunable train of femtosecond-duration, 35–100 kA, time-synchronized quasi-monoenergetic electron bunches. The combination of the negative chirp and the channel permits acceleration of electrons beyond 1 GeV in a 3 mm plasma with 1.4 J of laser pulse energy, thus offering the opportunity of high-repetition-rate operation at manageable average laser power

  7. Further Acceleration of MeV Electrons by a Relativistic Laser Pulse

    Institute of Scientific and Technical Information of China (English)

    HE Feng; YU Wei; LU Pei-Xiang; XU Han; SHEN Bai-Fei; QIAN Lie-Jia; LI Ru-Xin; XU Zhi-Zhan

    2005-01-01

    With the development of photocathode rf electron gun, electrons with high-brightness and mono-energy can be obtained easily. By numerically solving the relativistic equations of motion of an electron generated from this facility in laser fields modelled by a circular polarized Gaussian laser pulse, we find the electron can obtain high energy gain from the laser pulse. The corresponding acceleration distance for this electron driven by the ascending part of the laser pulse is much longer than the Rayleigh length, and the light amplitude experienced on the electron is very weak when the laser pulse overtakes the electron. The electron is accelerated effectively and the deceleration can be neglected.For intensities around 1019 W·μm2/cm2,an electron's energy gain near 0.1 GeV can be realized when its initial energy is 4.5 MeV, and the final velocity of the energetic electron is parallel with the propagation axis. The energy gain can be up to 1 GeV if the intensity is about 1021 W·μm2/cm2.The final energy gain of the electron as a function of its initial conditions and the parameters of the laser beam has also been discussed.

  8. A fast Monte Carlo program for pulsed-neutron capture-gamma tools

    Energy Technology Data Exchange (ETDEWEB)

    Hovgaard, J.

    1992-02-01

    A fast model for the pulsed-neutron capture-gamma tool has been developed. It is believed that the program produce valid results even though some approximation have been introduced. A correct {gamma} photon transport simulation, which is under preparation, has for instance not yet been included. Simulations performed so far has shown that the model, with respect to computing time and accuracy, fully lives up to expectations with respect to computing time and accuracy. (au).

  9. A fast Monte Carlo program for pulsed-neutron capture-gamma tools

    Energy Technology Data Exchange (ETDEWEB)

    Hovgaard, J.

    1992-02-01

    A fast model for the pulsed-neutron capture-gamma tool has been developed. It is believed that the program produce valid results even though some approximation have been introduced. A correct [gamma] photon transport simulation, which is under preparation, has for instance not yet been included. Simulations performed so far has shown that the model, with respect to computing time and accuracy, fully lives up to expectations with respect to computing time and accuracy. (au).

  10. Metrological Characterization of an Ultra-low Noise Acquisition System for Fast Voltage Pulses Measurements

    CERN Document Server

    Baccigalupi, Carlo; Martino, Michele

    2015-01-01

    The metrological characterization of a custom designed ultra-low noise analogue front-end for an acquisition system for the measurement of flat-top of fast voltage pulses is presented. The system has challenging r quirements, in particular for Common Mode Rejection Ratio (C M RR), thus custom methods have been defined, by illustrating the experimental results achieved at the European Organization for Nuclear Research (CERN) during the study of the new Compact LInear Collider (CLIC).

  11. Physics analyses of an accelerator-driven sub-critical assembly

    Energy Technology Data Exchange (ETDEWEB)

    Naberezhnev, Dmitry G. [Nuclear Engineering Division, Argonne National Laboratory, 9700 S. Cass Av., Argonne, IL 60439 (United States)]. E-mail: dimitri@anl.gov; Gohar, Yousry [Nuclear Engineering Division, Argonne National Laboratory, 9700 S. Cass Av., Argonne, IL 60439 (United States); Bailey, James [Nuclear Engineering Division, Argonne National Laboratory, 9700 S. Cass Av., Argonne, IL 60439 (United States); Belch, Henry [Nuclear Engineering Division, Argonne National Laboratory, 9700 S. Cass Av., Argonne, IL 60439 (United States)

    2006-06-23

    Physics analyses have been performed for an accelerator-driven sub-critical assembly as a part of the Argonne National Laboratory activity in preparation for a joint conceptual design with the Kharkov Institute of Physics and Technology (KIPT) of Ukraine. KIPT has a plan to construct an accelerator-driven sub-critical assembly targeted towards the medical isotope production and the support of the Ukraine nuclear industry. The external neutron source is produced either through photonuclear reactions in tungsten or uranium targets, or deuteron reactions in a beryllium target. KIPT intends using the high-enriched uranium (HEU) for the fuel of the sub-critical assembly. The main objective of this paper is to study the possibility of utilizing low-enriched uranium (LEU) fuel instead of HEU fuel without penalizing the sub-critical assembly performance, in particular the neutron flux level. In the course of this activity, several studies have been carried out to investigate the main choices for the system's parameters. The external neutron source has been characterized and a pre-conceptual target design has been developed. Several sub-critical configurations with different fuel enrichments and densities have been considered. Based on our analysis, it was shown that the performance of the LEU fuel is comparable with that of the HEU fuel. The LEU fuel sub-critical assembly with 200-MeV electron energy and 100-kW electron beam power has an average total flux of {approx}2.50x10{sup 13} n/s cm{sup 2} in the irradiation channels. The corresponding total facility power is {approx}204 kW divided into 91 and 113 kW deposited in the target and sub-critical assemblies, respectively.

  12. Double ionization effect in electron accelerations by high-intensity laser pulse interaction with a neutral gas

    International Nuclear Information System (INIS)

    We study the effect of laser-induced double-ionization of a helium gas (with inhomogeneous density profile) on vacuum electron acceleration. For enough laser intensity, helium gas can be found doubly ionized and it strengthens the divergence of the pulse. The double ionization of helium gas can defocus the laser pulse significantly, and electrons are accelerated by the front of the laser pulse in vacuum and then decelerated by the defocused trail part of the laser pulse. It is observed that the electrons experience a very low laser-intensity at the trailing part of the laser pulse. Hence, there is not much electron deceleration at the trailing part of the pulse. We found that the inhomogeneity of the neutral gas reduced the rate of tunnel ionization causing less defocusing of the laser pulse and thus the electron energy gain is reduced. (authors)

  13. Central Reactivity Measurements on Assemblies 1 and 3 of the Fast Reactor FR0

    International Nuclear Information System (INIS)

    The reactivity effects of small samples of various materials have been measured, by the period method at the core centre of Assemblies 1 and 3 of the fast zero power reactor FR0. For some materials the reactivity change as a function of sample size has also been determined experimentally. The core of Assembly 1 consisted only of uranium enriched to 20 % whereas the core of Assembly 3 was diluted with 30 % graphite. The results have been compared with calculated values obtained with a second-order transport-theoretical perturbation model and using differently shielded cross sections depending upon sample size. Qualitative agreement has generally been found, although discrepancies still exist. The spectrum perturbation caused by the experimental arrangement has been analyzed and found to be rather important

  14. Developing The Physics Desing for NDCS-II, A Unique Pulse-Compressing Ion Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, A; Barnard, J J; Cohen, R H; Grote, D P; Lund, S M; Sharp, W M; Faltens, A; Henestroza, E; Jung, J; Kwan, J W; Lee, E P; Leitner, M A; Logan, B G; Vay, J -; Waldron, W L; Davidson, R C; Dorf, M; Gilson, E P; Kaganovich, I

    2009-09-24

    The Heavy Ion Fusion Science Virtual National Laboratory (a collaboration of LBNL, LLNL, and PPPL) is using intense ion beams to heat thin foils to the 'warm dense matter' regime at {approx}< 1 eV, and is developing capabilities for studying target physics relevant to ion-driven inertial fusion energy. The need for rapid target heating led to the development of plasma-neutralized pulse compression, with current amplification factors exceeding 50 now routine on the Neutralized Drift Compression Experiment (NDCX). Construction of an improved platform, NDCX-II, has begun at LBNL with planned completion in 2012. Using refurbished induction cells from the Advanced Test Accelerator at LLNL, NDCX-II will compress a {approx}500 ns pulse of Li{sup +} ions to {approx} 1 ns while accelerating it to 3-4 MeV over {approx} 15 m. Strong space charge forces are incorporated into the machine design at a fundamental level. We are using analysis, an interactive 1D PIC code (ASP) with optimizing capabilities and centroid tracking, and multi-dimensional Warpcode PIC simulations, to develop the NDCX-II accelerator. This paper describes the computational models employed, and the resulting physics design for the accelerator.

  15. DEVELOPING THE PHYSICS DESIGN FOR NDCX-II, A UNIQUE PULSE-COMPRESSING ION ACCELERATOR

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, A.; Barnard, J. J.; Cohen, R. H.; Grote, D. P.; Lund, S. M.; Sharp, W. M.; Faltens, A.; Henestroza, E.; Jung, J-Y.; Kwan, J. W.; Lee, E. P.; Leitner, M. A.; Logan, B. G.; Vay, J.-L.; Waldron, W. L.; Davidson, R.C.; Dorf, M.; Gilson, E.P.; Kaganovich, I.

    2009-07-20

    The Heavy Ion Fusion Science Virtual National Laboratory(a collaboration of LBNL, LLNL, and PPPL) is using intense ion beams to heat thin foils to the"warm dense matter" regime at<~;; 1 eV, and is developing capabilities for studying target physics relevant to ion-driven inertial fusion energy. The need for rapid target heating led to the development of plasma-neutralized pulse compression, with current amplification factors exceeding 50 now routine on the Neutralized Drift Compression Experiment (NDCX). Construction of an improved platform, NDCX-II, has begun at LBNL with planned completion in 2012. Using refurbished induction cells from the Advanced Test Accelerator at LLNL, NDCX-II will compress a ~;;500 ns pulse of Li+ ions to ~;;1 ns while accelerating it to 3-4 MeV over ~;;15 m. Strong space charge forces are incorporated into the machine design at a fundamental level. We are using analysis, an interactive 1D PIC code (ASP) with optimizing capabilities and centroid tracking, and multi-dimensional Warpcode PIC simulations, to develop the NDCX-II accelerator. This paper describes the computational models employed, and the resulting physics design for the accelerator.

  16. Enhanced hole boring with two-color relativistic laser pulses in the fast ignition scheme

    Science.gov (United States)

    Yu, Changhai; Deng, Aihua; Tian, Ye; Li, Wentao; Wang, Wentao; Zhang, Zhijun; Qi, Rong; Wang, Cheng; Liu, Jiansheng

    2016-08-01

    A scheme of using two-color laser pulses for hole boring into overdense plasma as well as energy transfer into electron and ion beams has been studied using particle-in-cell simulations. Following an ultra-short ultra-intense hole-boring laser pulse with a short central wavelength in extreme ultra-violet range, the main infrared driving laser pulse can be guided in the hollow channel preformed by the former laser and propagate much deeper into an overdense plasma, as compared to the case using the infrared laser only. In addition to efficiently transferring the main driving laser energy into energetic electrons and ions generation deep inside the overdense plasma, the ion beam divergence can be greatly reduced. The results might be beneficial for the fast ignition concept of inertial confinement fusion.

  17. Multi-MeV electron acceleration by sub-terawatt laser pulses

    CERN Document Server

    Goers, A J; Feder, L; Miao, B; Salehi, F; Milchberg, H M

    2015-01-01

    We demonstrate laser-plasma acceleration of high charge electron beams to the ~10 MeV scale using ultrashort laser pulses with as little energy as 10 mJ. This result is made possible by an extremely dense and thin hydrogen gas jet. Total charge up to ~0.5 nC is measured for energies >1 MeV. Acceleration is correlated to the presence of a relativistically self-focused laser filament accompanied by an intense coherent broadband light flash, associated with wavebreaking, which can radiate more than ~3% of the laser energy in a sub-femtosecond bandwidth consistent with half-cycle optical emission. Our results enable truly portable applications of laser-driven acceleration, such as low dose radiography, ultrafast probing of matter, and isotope production.

  18. A fast pulse phase estimation method for X-ray pulsar signals based on epoch folding

    Institute of Scientific and Technical Information of China (English)

    Xue Mengfan; Li Xiaoping; Sun Haifeng; Fang Haiyan

    2016-01-01

    X-ray pulsar-based navigation (XPNAV) is an attractive method for autonomous deep-space navigation in the future. The pulse phase estimation is a key task in XPNAV and its accuracy directly determines the navigation accuracy. State-of-the-art pulse phase estimation techniques either suffer from poor estimation accuracy, or involve the maximization of generally non-convex object function, thus resulting in a large computational cost. In this paper, a fast pulse phase estimation method based on epoch folding is presented. The statistical properties of the observed profile obtained through epoch folding are developed. Based on this, we recognize the joint prob-ability distribution of the observed profile as the likelihood function and utilize a fast Fourier transform-based procedure to estimate the pulse phase. Computational complexity of the proposed estimator is analyzed as well. Experimental results show that the proposed estimator significantly outperforms the currently used cross-correlation (CC) and nonlinear least squares (NLS) estima-tors, while significantly reduces the computational complexity compared with NLS and maximum likelihood (ML) estimators.

  19. Physical processes at work in sub-30 fs, PW laser pulse-driven plasma accelerators: Towards GeV electron acceleration experiments at CILEX facility

    International Nuclear Information System (INIS)

    Optimal regimes and physical processes at work are identified for the first round of laser wakefield acceleration experiments proposed at a future CILEX facility. The Apollon-10P CILEX laser, delivering fully compressed, near-PW-power pulses of sub-25 fs duration, is well suited for driving electron density wakes in the blowout regime in cm-length gas targets. Early destruction of the pulse (partly due to energy depletion) prevents electrons from reaching dephasing, limiting the energy gain to about 3 GeV. However, the optimal operating regimes, found with reduced and full three-dimensional particle-in-cell simulations, show high energy efficiency, with about 10% of incident pulse energy transferred to 3 GeV electron bunches with sub-5% energy spread, half-nC charge, and absolutely no low-energy background. This optimal acceleration occurs in 2 cm length plasmas of electron density below 1018 cm−3. Due to their high charge and low phase space volume, these multi-GeV bunches are tailor-made for staged acceleration planned in the framework of the CILEX project. The hallmarks of the optimal regime are electron self-injection at the early stage of laser pulse propagation, stable self-guiding of the pulse through the entire acceleration process, and no need for an external plasma channel. With the initial focal spot closely matched for the nonlinear self-guiding, the laser pulse stabilizes transversely within two Rayleigh lengths, preventing subsequent evolution of the accelerating bucket. This dynamics prevents continuous self-injection of background electrons, preserving low phase space volume of the bunch through the plasma. Near the end of propagation, an optical shock builds up in the pulse tail. This neither disrupts pulse propagation nor produces any noticeable low-energy background in the electron spectra, which is in striking contrast with most of existing GeV-scale acceleration experiments

  20. Accelerating monoenergetic protons from ultrathin foils by flat-top laser pulses in the directed-Coulomb-explosion regime

    OpenAIRE

    Bulanov, S. S.; Brantov, A.; Bychenkov, V. Yu.; Chvykov, V.; Kalinchenko, G.; Matsuoka, T.; Rousseau, P.; Reed, S; Yanovsky, V.; Litzenberg, D. W.; Krushelnick, K.; Maksimchuk, A.

    2008-01-01

    We consider the effect of laser beam shaping on proton acceleration in the interaction of a tightly focused pulse with ultrathin double-layer solid targets in the regime of directed Coulomb explosion. In this regime, the heavy ions of the front layer are forced by the laser to expand predominantly in the direction of the pulse propagation, forming a moving longitudinal charge separation electric field, thus increasing the effectiveness of acceleration of second-layer protons. The utilization ...

  1. Control Loop for a Pulse Generator of a Fast Septum Magnet using DSP and Fuzzy Logic

    CERN Document Server

    Aldaz-Carroll, E; Dieperink, J H; Schröder, G; Vossenberg, Eugène B

    1997-01-01

    A prototype of a fast pulsed eddy current septum magnet for one of thebeam extraction's from the SPS towards LHC is under development. The precision of the magnetic field must be better than ±1.0 10-4 during a flat top of 30 µs. The current pulse is generated by discharging the capacitors of a LC circuit that resonates on the 1st and on the 3rd harmonic of a sine wave with a repetition rate of 15 s. The parameters of the circuit and the voltage on the capacitors must be carefully adjusted to meet the specifications. Drifts during operation must be corrected between two pulses by mechanically adjusting the inductance of the coil in the generator as well as the primary capacitor voltage. This adjustment process is automated by acquiring the current pulse waveform with sufficient time and amplitude resolution, calculating the corrections needed and applying these corrections to the hardware for the next pulse. A very cost-effective and practical solution for this adjustment process is the integration of off-th...

  2. Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator

    International Nuclear Information System (INIS)

    The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 (micro)s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.

  3. Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl A [Los Alamos National Laboratory; Abeyta, Epifanio O [Los Alamos National Laboratory; Aragon, Paul [Los Alamos National Laboratory; Archuleta, Rita [Los Alamos National Laboratory; Cook, Gerald [Los Alamos National Laboratory; Dalmas, Dale [Los Alamos National Laboratory; Esquibel, Kevin [Los Alamos National Laboratory; Gallegos, Robert A [Los Alamos National Laboratory; Garnett, Robert [Los Alamos National Laboratory; Harrison, James F [Los Alamos National Laboratory; Johnson, Jeffrey B [Los Alamos National Laboratory; Jacquez, Edward B [Los Alamos National Laboratory; Mccuistian, Brian T [Los Alamos National Laboratory; Montoya, Nicholas A [Los Alamos National Laboratory; Nath, Subrato [Los Alamos National Laboratory; Nielsen, Kurt [Los Alamos National Laboratory; Oro, David [Los Alamos National Laboratory; Prichard, Benjamin [Los Alamos National Laboratory; Rowton, Lawrence [Los Alamos National Laboratory; Sanchez, Manolito [Los Alamos National Laboratory; Scarpetti, Raymond [Los Alamos National Laboratory; Schauer, Martin M [Los Alamos National Laboratory; Seitz, Gerald [Los Alamos National Laboratory; Schulze, Martin [Los Alamos National Laboratory; Bender, Howard A [Los Alamos National Laboratory; Broste, William B [Los Alamos National Laboratory; Carlson, Carl A [Los Alamos National Laboratory; Frayer, Daniel K [Los Alamos National Laboratory; Johnson, Douglas E [Los Alamos National Laboratory; Tom, C Y [Los Alamos National Laboratory; Williams, John [Los Alamos National Laboratory; Hughes, Thomas [Los Alamos National Laboratory; Anaya, Richard [LLNL; Caporaso, George [LLNL; Chambers, Frank [LLNL; Chen, Yu - Jiuan [LLNL; Falabella, Steve [LLNL; Guethlein, Gary [LLNL; Raymond, Brett [LLNL; Richardson, Roger [LLNL; Trainham, C [NSTEC/STL; Watson, Jim [LLNL; Weir, John [LLNL; Genoni, Thomas [VOSS; Toma, Carsten [VOSS

    2009-01-01

    The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 {micro}s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.

  4. Core characteristics on a hybrid type fast reactor system combined with proton accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kowata, Yasuki; Otsubo, Akira [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1997-06-01

    In our study on a hybrid fast reactor system, we have investigated it from the view point of transmutation ability of trans-uranium (TRU) nuclide making the most effective use of special features (controllability, hard neutron spectrum) of the system. It is proved that a proton beam is superior in generation of neutrons compared with an electron beam. Therefore a proton accelerator using spallation reaction with a target nucleus has an advantage to transmutation of TRU than an electron one. A fast reactor is expected to primarily have a merit that the reactor can be operated for a long term without employment of highly enriched plutonium fuel by using external neutron source such as the proton accelerator. Namely, the system has a desirable characteristic of being possible to self-sustained fissile plutonium. Consequently in the present report, core characteristics of the system were roughly studied by analyses using 2D-BURN code. The possibility of self-sustained fuel was investigated from the burnup and neutronic calculation in a cylindrical core with 300w/cc of power density without considering a target material region for the accelerator. For a reference core of which the height and the radius are both 100 cm, there is a fair prospect that a long term reactor operation is possible with subsequent refueling of natural uranium, if the medium enriched (around 10wt%) uranium or plutonium fuels are fully loaded in the initial core. More precise analyses will be planed in a later fiscal year. (author)

  5. Laser Ion Acceleration from the Interaction of Ultra-Intense laser Pulse with thi foils

    Energy Technology Data Exchange (ETDEWEB)

    Allen, M

    2004-03-12

    The discovery that ultra-intense laser pulses (I > 10{sup 18} W/cm{sup 2}) can produce short pulse, high energy proton beams has renewed interest in the fundamental mechanisms that govern particle acceleration from laser-solid interactions. Experiments have shown that protons present as hydrocarbon contaminants on laser targets can be accelerated up to energies > 50 MeV. Different theoretical models that explain the observed results have been proposed. One model describes a front-surface acceleration mechanism based on the ponderomotive potential of the laser pulse. At high intensities (I > 10{sup 18} W/cm{sup 2}), the quiver energy of an electron oscillating in the electric field of the laser pulse exceeds the electron rest mass, requiring the consideration of relativistic effects. The relativistically correct ponderomotive potential is given by U{sub p} = ([1 + I{lambda}{sup 2}/1.3 x 10{sup 18}]{sup 1/2} - 1) m{sub o}c{sup 2}, where I{lambda}{sup 2} is the irradiance in W{micro}m{sup 2}/cm{sup 2} and m{sub o}c{sup 2} is the electron rest mass.At laser irradiance of I{lambda}{sup 2} {approx} 10{sup 20} W{micro}m{sup 2}/cm{sup 2}, the ponderomotive potential can be of order several MeV. A few recent experiments--discussed in Chapter 3 of this thesis--consider this ponderomotive potential sufficiently strong to accelerate protons from the front surface of the target to energies up to tens of MeV. Another model, known as Target Normal Sheath Acceleration (TNSA), describes the mechanism as an electrostatic sheath on the back surface of the laser target. According to the TNSA model, relativistic hot electrons created at the laser-solid interaction penetrate the foil where a few escape to infinity. The remaining hot electrons are retained by the target potential and establish an electrostatic sheath on the back surface of the target.

  6. Plasma wakefield excitation by incoherent laser pulses: a path towards high-average power laser-plasma accelerators

    CERN Document Server

    Benedetti, C; Esarey, E; Leemans, W P

    2014-01-01

    In a laser plasma accelerator (LPA), a short and intense laser pulse propagating in a plasma drives a wakefield (a plasma wave with a relativistic phase velocity) that can sustain extremely large electric fields, enabling compact accelerating structures. Potential LPA applications include compact radiation sources and high energy linear colliders. We propose and study plasma wave excitation by an incoherent combination of a large number of low energy laser pulses (i.e., without constraining the pulse phases). We show that, in spite of the incoherent nature of electromagnetic fields within the volume occupied by the pulses, the excited wakefield is regular and its amplitude is comparable or equal to that obtained using a single, coherent pulse with the same energy. These results provide a path to the next generation of LPA-based applications, where incoherently combined multiple pulses may enable high repetition rate, high average power LPAs.

  7. The non-destructive threshold of the graphite surface by STM in the ultra-fast pulse mode

    Institute of Scientific and Technical Information of China (English)

    Xu Chun-Kai; Wei Zheng; Chen Xiang-Jun; Xu Ke-Zun

    2007-01-01

    In this paper single ultra-fast voltage pulses are introduced to the Pt/Ir tip of a scanning tunnelling microscope (STM),and the non-destructive threshold of the graphite surface is studied systematically in a wide range of pulse durations(from 104 to 8 ns).Considering the waveform distortion of the pulses at the tunnelling region,this paper gives the corrected threshold curve of pulse amplitude depending on pulse duration.A new explanation of threshold power has been suggested and fits the experimental results well.

  8. Sulfur hexafluoride reprocessing system design for a large pulsed power accelerator

    International Nuclear Information System (INIS)

    The Particle Beam Fusion Accelerator-II (PBFA-II) is a large, high power accelerator being constructed at Sandia National Labs to conduct research in inertial confinement fusion. One key to the success of this machine is the ability to produce an electrical pulse at the target with a well defined shape (power versus time). This requires that the 36 electrical drivers be initiated with good simultaneity. Simultaneity (or jitter) of the 36 module shot outputs is controlled by a sequence of pulse outputs starting at the control/monitor input to the trigger amplifier and then to the Marx trigger generators, the Marx generators, and finally the rimfire switches. A homogeneous insulating vapor in these switches is thought to reduce the jitter; however, actual data are not available to establish this concept. PBFA-II uses sulfur hexafluoride (SF6) for this insulating vapor. This paper describes the requirements placed on an SF6 reprocessing system when operating in a fusion research accelerator, resulting in criteria used to design the reprocessing system, and the subsequent design implemented to meet these criteria

  9. AC-loss considerations of a pulse SMES for an accelerator

    Science.gov (United States)

    Lyly, M.; Hiltunen, I.; Järvelä, J.; Korpela, A.; Lehti, L.; Stenvall, A.; Mikkonen, R.

    2010-06-01

    In particle accelerators quasi-DC superconducting magnets are used to keep particles in desired tracks. The needed rapid field variations of these high energy magnets require large energy bursts. If these bursts are taken from and fed back to the utility grid, its voltage is distorted and the quality of the electricity degrades. In addition, these bursts may decrease operation life time of generators and extra arrangements may be required by the electricity producers. Thus, an energy storage is an essential component for a cost-effective particle accelerator. Flywheels, capacitors and superconducting magnetic energy storage (SMES) are possible options for these relatively large and high power energy storages. Here we concentrate on AC-loss of a pulse SMES aiming to demonstrate the feasibility of NbTi SMES in a particle accelerator. The designing of a SMES requires highly reliable AC-loss simulations. In this paper, calorimetric AC-loss measurements of a NbTi magnet have been carried out to consider conductor's suitability in a pulse SMES. In addition, the measured results are compared with AC-loss simulations.

  10. AC-loss considerations of a pulse SMES for an accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Lyly, M; Hiltunen, I; Jaervelae, J; Korpela, A; Lehti, L; Stenvall, A; Mikkonen, R, E-mail: mika.lyly@tut.f [Tampere University of Technology, Electromagnetics, PO Box 692, FI-33101 (Finland)

    2010-06-01

    In particle accelerators quasi-DC superconducting magnets are used to keep particles in desired tracks. The needed rapid field variations of these high energy magnets require large energy bursts. If these bursts are taken from and fed back to the utility grid, its voltage is distorted and the quality of the electricity degrades. In addition, these bursts may decrease operation life time of generators and extra arrangements may be required by the electricity producers. Thus, an energy storage is an essential component for a cost-effective particle accelerator. Flywheels, capacitors and superconducting magnetic energy storage (SMES) are possible options for these relatively large and high power energy storages. Here we concentrate on AC-loss of a pulse SMES aiming to demonstrate the feasibility of NbTi SMES in a particle accelerator. The designing of a SMES requires highly reliable AC-loss simulations. In this paper, calorimetric AC-loss measurements of a NbTi magnet have been carried out to consider conductor's suitability in a pulse SMES. In addition, the measured results are compared with AC-loss simulations.

  11. Acceleration of electrons under the action of petawatt-class laser pulses onto foam targets

    Science.gov (United States)

    Pugachev, L. P.; Andreev, N. E.; Levashov, P. R.; Rosmej, O. N.

    2016-09-01

    Optimization study for future experiments on interaction of petawatt laser pulses with foam targets was done by 3D PIC simulations. Densities in the range 0.5nc-nc and thicknesses in the range 100 - 500 μm of the targets were considered corresponding to those which are currently available. It is shown that heating of electrons mainly occurs under the action of the ponderomotive force of a laser pulse in which amplitude increases up to three times because of self-focusing effect in underdense plasma. Accelerated electrons gain additional energy directly from the high-frequency laser field at the betatron resonance in the emerging plasma density channels. For thicker targets a higher number of electrons with higher energies are obtained. The narrowing of the angular distribution of electrons for thicker targets is explained by acceleration in multiple narrow filaments. Obtained energies of accelerated electrons can be approximated by Maxwell distribution with the temperature 8.5 MeV. The charge carried by electrons with energies higher than 30 MeV is about 30 nC, that is 3-4 order of magnitude higher than the charge predicted by the ponderomotive scaling for the incident laser amplitude.

  12. Plasma diode as a source of power pulses of fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Zavada, N.I.; Tsukerman, V.A.; Volodin, M.D.; Gevorkyan, G.G.; Komarov, P.L.; Lyamin, V.I.; Pilipenko, A.V.

    1981-07-01

    A possibility to obtain power neutron pulses using the GI-3 000 and ORION-1 electrostatic accelerators is studied. Two configurations of electron gap are used in the GI-3 00U accelerator: the system with ''conserved cathode'' and combination of the converted cathode with axial magnetic field. Anode plasma obtained from the thin layer of D/sub 2/O freezed on the anode or plasma from spark ion sources, with elements saturated with deuterium or tritium serves as a ion source. The maximum value of total neutron yield obtained with carbon targets reaches 3x10/sup 9/ at W=25 kJ and 2x1U/sup 10/ neutron per pulse at W=40 kJ and for lithium targets - 2x10/sup 10/ and 1x10/sup 11/ neutron per pulse respectively. A conclusion is made that further increase in neutron yield can be reached by improvement of diode electrode system, realization of the maximum energy store in double forming line (W>=200 kJ), improvement of the target quality and ion beam intensity, increase of electron beam self-isolation or application of crossed electric and magnetic fields in the sistem. The realization of these factors permits to increase the total yield by more than one order.

  13. Fast-neutron spectrometry using a ³He ionization chamber and digital pulse shape analysis.

    Science.gov (United States)

    Chichester, D L; Johnson, J T; Seabury, E H

    2012-08-01

    Digital pulse shape analysis (dPSA) has been used with a Cuttler-Shalev type (3)He ionization chamber to measure the fast-neutron spectra of a deuterium-deuterium electronic neutron generator, a bare (252)Cf spontaneous fission neutron source, and of the transmitted fast neutron spectra of a (252)Cf source attenuated by water, graphite, liquid nitrogen, and magnesium. Rise-time dPSA has been employed using the common approach for analyzing n +(3)He→(1)H+(3)H ionization events and improved to account for wall-effect and pile-up events, increasing the fidelity of these measurements. Simulations have been performed of the different experimental arrangements and compared with the measurements, demonstrating general agreement between the dPSA-processed fast-neutron spectra and predictions. The fast-neutron resonance features of the attenuation cross sections of the attenuating materials are clearly visible within the resolution limits of the electronics used for the measurements, and the potential applications of high-resolution fast-neutron spectrometry for nuclear nonproliferation and safeguards measurements are discussed.

  14. DESIGN CONSIDERATIONS OF FAST KICKER SYSTEMS FOR HIGH INTENSITY PROTON ACCELERATORS

    International Nuclear Information System (INIS)

    In this paper, we discuss the specific issues related to the design of the Fast Kicker Systems for high intensity proton accelerators. To address these issues in the preliminary design stage can be critical since the fast kicker systems affect the machine lattice structure and overall design parameters. Main topics include system architecture, design strategy, beam current coupling, grounding, end user cost vs. system cost, reliability, redundancy and flexibility. Operating experience with the Alternating Gradient Synchrotron injection and extraction kicker systems at Brookhaven National Laboratory and their future upgrade is presented. Additionally, new conceptual designs of the extraction kicker for the Spallation Neutron Source at Oak Ridge and the Advanced Hydrotest Facility at Los Alamos are discussed

  15. Fast and dynamic generation of linear octrees for geological bodies under hardware acceleration

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In the application of 3D Geoscience Modeling,we often need to generate the volumetric representations of geological bodies from their surface representations.Linear octree,as an efficient and easily operated volumetric model,is widely used in 3D Geoscience Modeling.This paper proposes an algorithm for fast and dynamic generation of linear octrees of geological bodies from their surface models under hardware acceleration.The Z-buffers are used to determine the attributes of octants and voxels in a fast way,and a divide-and-conquer strategy is adopted.A stack structure is exploited to record the subdivision,which allows generating linear octrees dynamically.The algorithm avoids large-scale sorting process and bypasses the compression in linear octrees generation.Experimental results indicate its high efficiency in generating linear octrees for large-scale geologic bodies.

  16. Note: High resolution ultra fast high-power pulse generator for inductive load using digital signal processor.

    Science.gov (United States)

    Flaxer, Eli

    2014-08-01

    We present a new design of a compact, ultra fast, high resolution and high-powered, pulse generator for inductive load, using power MOSFET, dedicated gate driver and a digital signal controller. This design is an improved circuit of our old version controller. We demonstrate the performance of this pulse generator as a driver for a new generation of high-pressure supersonic pulsed valves.

  17. Simulation of Cascaded Longitudinal-Space-Charge Amplifier at the Fermilab Accelerator Science & Technology (Fast) Facility

    Energy Technology Data Exchange (ETDEWEB)

    Halavanau, A. [Northern Illinois U.; Piot, P. [Northern Illinois U.

    2015-12-01

    Cascaded Longitudinal Space Charge Amplifiers (LSCA) have been proposed as a mechanism to generate density modulation over a board spectral range. The scheme has been recently demonstrated in the optical regime and has confirmed the production of broadband optical radiation. In this paper we investigate, via numerical simulations, the performance of a cascaded LSCA beamline at the Fermilab Accelerator Science & Technology (FAST) facility to produce broadband ultraviolet radiation. Our studies are carried out using elegant with included tree-based grid-less space charge algorithm.

  18. Shock wave acceleration of protons in inhomogeneous plasma interacting with ultrashort intense laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Lecz, Zs. [ELI-ALPS, ELI-HU Nkft., Szeged (Hungary); Andreev, A. [ELI-ALPS, ELI-HU Nkft., Szeged (Hungary); Max-Born Institute, Berlin (Germany)

    2015-04-15

    The acceleration of protons, triggered by solitary waves in expanded solid targets is investigated using particle-in-cell simulations. The near-critical density plasma is irradiated by ultrashort high power laser pulses, which generate the solitary wave. The transformation of this soliton into a shock wave during propagation in plasma with exponentially decreasing density profile is described analytically, which allows to obtain a scaling law for the proton energy. The high quality proton bunch with small energy spread is produced by reflection from the shock-front. According to the 2D simulations, the mechanism is stable only if the laser pulse duration is shorter than the characteristic development time of the parasitic Weibel instability.

  19. Simulation studies of crystal-photodetector assemblies for the Turkish accelerator center particle factory electromagnetic calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Kocak, F., E-mail: fkocak@uludag.edu.tr

    2015-07-01

    The Turkish Accelerator Center Particle Factory detector will be constructed for the detection of the produced particles from the collision of a 1 GeV electron beam against a 3.6 GeV positron beam. PbWO{sub 4} and CsI(Tl) crystals are considered for the construction of the electromagnetic calorimeter part of the detector. The generated optical photons in these crystals are detected by avalanche or PIN photodiodes. Geant4 simulation code has been used to estimate the energy resolution of the calorimeter for these crystal–photodiode assemblies.

  20. Measurement and analysis of the electric field radiation in pulsed power system of linear induction accelerator

    International Nuclear Information System (INIS)

    The close of high voltage switch in pulsed power system of linear induction accelerator often radiates strong transient electric field, which may influence ambient sensitive electric equipment, signals and performance of other instruments, etc. By performing gridded measurement around the Marx generator, the general distribution law and basic characters of electric field radiation are summarized. The current signal of the discharge circuit is also measured, which demonstrates that the current and the radiated electric field both have a resonance frequency about 150 kHz, and contain much higher frequency components. (authors)

  1. Ion acceleration in shell cylinders irradiated by a short intense laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, A. [Max-Born Institute, Berlin (Germany); ELI-ALPS, Szeged (Hungary); Platonov, K. [St. Petersburg State Polytechnic University, St. Petersburg (Russian Federation); Sharma, A. [ELI-ALPS, Szeged (Hungary); Murakami, M. [ILE, Osaka University, Osaka (Japan)

    2015-09-15

    The interaction of a short high intensity laser pulse with homo and heterogeneous shell cylinders has been analyzed using particle-in-cell simulations and analytical modeling. We show that the shell cylinder is proficient of accelerating and focusing ions in a narrow region. In the case of shell cylinder, the ion energy exceeds the ion energy for a flat target of the same thickness. The constructed model enables the evaluation of the ion energy and the number of ions in the focusing region.

  2. Energy efficiency of electric pulse installation based on a high-current plasma accelerator

    Directory of Open Access Journals (Sweden)

    Shanenkov I.I.

    2014-01-01

    Full Text Available The energy efficiency of electric pulse installation based on a high-current plasma accelerator was investigated. A series of experiments with different central electrodes was carried out. The system based on carbon electrodes has a greater value of the charge energy conversion into the energy of arc discharge and the less discharge current level in comparison with other electrode systems. The power consumption value for producing 1 gram of powdered product was estimated and it was found this value is comparable to the work of the LED light bulb for 1 hour.

  3. A synthetic pulse method for excitation of RF-accelerator structures

    CERN Document Server

    Caspers, Fritz

    1986-01-01

    It is proposed to excite RF-cavity accelerator structures in a phaselocked multifrequency mode of operation. The purpose is to obtain high accelerating gradients with smaller average losses than in the conventional single-frequency operation scheme. In general the resonant frequencies are not harmonically related to each other. Assuming finite Q-values one can always find a frequency fo such that within a 3 dB bandwidth all resonances considered are at integer multiples of f0. For the gap voltage one obtains in this case a periodic pulse in the time domain with T = 1/f0. Increasing the peak gap voltage by adding (exciting) further higher modes with equal CW power on each mode (equal shout impedances assumed) results in power losses proportional to $V_{peak}$ instead of $P_{loss} ~ V_{peak}^2$ for single-frequency operation.

  4. An Experimental Study of a Low-Jitter Pulsed Electromagnetic Plasma Accelerator

    Science.gov (United States)

    Thio, Y. C. Francis; Lee, Michael; Eskridge, Richard; Smith, James; Martin, Adam; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    An experimental plasma accelerator for a variety of applications under development at the NASA Marshall Space Flight Center is described. The accelerator is a pulsed plasma thruster and has been tested experimentally and plasma jet velocities of approximately 50 kilometers per second have been obtained. The plasma jet structure has been photographed with 10 ns exposure times to reveal a stable and repeatable plasma structure. Data for velocity profile information has been obtained using light pipes embedded in the gun walls to record the plasma transit at various barrel locations. Preliminary spatially resolved spectral data and magnetic field probe data are also presented. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter has been characterized and future work for second generation "ultra-low jitter" gun development is identified.

  5. Pulsed spallation neutron source with an induction LINAC and a fixed-field alternating-gradient accelerator

    International Nuclear Information System (INIS)

    The paper describes an accelerator scenario of a Pulsed Spallation Neutron Source made of an Induction Linac injecting into a Fixed-Field Alternating-Gradient Accelerator (FFAG). The motivations underlying the proposal deal with the concern of removing technical risks peculiar to other scenarios involving RF Linacs, Synchrotrons and Accumulator Rings, which originate, for example, from the need of developing intense negative-ion sources and of multi-turn injection into the Compressor Rings. The system proposed here makes use of a positive-ion source of very short pulse duration, and of single-turn transfer into the circular accelerator. (author) 2 figs., 2 tabs., 16 refs

  6. Intense laser pulse propagation and channel formation through plasmas relevant for the fast ignitor scheme

    International Nuclear Information System (INIS)

    Measurements of self-channeling of picosecond laser pulses due to relativistic and ponderomotive expulsion effects have been obtained in preformed plasmas at laser irradiances between 5 - 9x1018 Wcm-2. The self-focused channel was surrounded by a multi-megagauss magnetic field. The orientation of the field was consistent with a forward going relativistic electron beam propagating along the laser pulse. Self-channeling and magnetic field generation mechanisms were modeled by multidimensional particle-in-cell (PIC) simulations and good agreement was obtained with the experimental observations. Measurements of the channel expansion after the interaction were obtained and the rate of expansion was consistent with a blast wave solution. The level of transmission of an intense laser pulse through such performed density channels was observed to increase significantly compared to the case without a channel. High levels of transmission of an intense laser pulse through microtubes were also observed. The relevance of these results to the fast ignitor is discussed. copyright 1999 American Institute of Physics

  7. Design Concepts For A Long Pulse Upgrade For The DIII-D Fast Wave Antenna Array

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, Philip Michael [ORNL; Baity Jr, F Wallace [ORNL; Caughman, John B [ORNL; Goulding, Richard Howell [ORNL; Hosea, J. [Princeton Plasma Physics Laboratory (PPPL); Greenough, Nevell [Princeton Plasma Physics Laboratory (PPPL); Nagy, Alex [Princeton Plasma Physics Laboratory (PPPL); Pinsker, R. [General Atomics; Rasmussen, David A [ORNL

    2009-01-01

    A goal in the 5-year plan for the fast wave program on DIII-D is to couple a total of 3.6 MW of RF power into a long pulse, H-mode plasma for central electron heating. The present short-pulse 285/300 antenna array would need to be replaced with one capable of at least 1.2 MW, 10 s operation at 60 MHz into an H-mode (low resistive loading) plasma condition. The primary design under consideration uses a poloidally-segmented strap (3 sections) for reduced strap voltage near the plasma/Faraday screen region. Internal capacitance makes the antenna structure self-resonant at 60 MHz, strongly reducing peak E-fields in the vacuum coax and feed throughs.

  8. Design of long-pulse fast wave current drive antennas for DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Baity, F.W.; Batchelor, D.B.; Bills, K.C.; Fogelman, C.H.; Jaeger, E.F.; Ping, J.L.; Riemer, B.W.; Ryan, P.M.; Stallings, D.C.; Taylor, D.J.; Yugo, J.J. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States))

    1994-10-15

    Two new long-pulse fast wave current drive (FWCD) antennas will be installed on DIII-D in early 1994. These antennas will increase the available FWCD power from 2 MW to 6 MW for pulse lengths of up to 2 s, and to 4 MW for up to 10 s. Power for the new antennas is from two ASDEX-type 30- to 120-MHz transmitters. When operated at 90[degree] phasing into a low-density plasma ([similar to]4[times]10[sup 19]m[sup [minus]3]) with hot electrons ([similar to]10 keV), these two new antennas are predicted to drive approximately 1 MA of plasma current.

  9. Sensitive and ultra-fast species detection using pulsed cavity ringdown spectroscopy

    KAUST Repository

    Alquaity, Awad

    2015-01-01

    Pulsed cavity ringdown spectroscopy (CRDS) is used to develop a novel, ultra-fast, high-sensitivity diagnostic for measuring species concentrations in shock tube experiments. The diagnostic is demonstrated by monitoring trace concentrations of ethylene in the mid-IR region near 949.47 cm-1. Each ringdown measurement is completed in less than 1 μs and the time period between successive pulses is 10 μs. The high sensitivity diagnostic has a noise-equivalent detection limit of 1.08 x 10-5 cm-1 which enables detection of 15 ppm ethylene at fuel pyrolysis conditions (1845 K and 2 bar) and 294 ppb ethylene under ambient conditions (297 K and 1 bar). To our knowledge, this is the first successful application of the cavity ringdown method to the measurement of species time-histories in a shock tube. © 2015 OSA.

  10. Reshaping, Fragmentation, and Assembly of Gold Nanoparticles Assisted by Pulse Lasers.

    Science.gov (United States)

    González-Rubio, Guillermo; Guerrero-Martínez, Andrés; Liz-Marzán, Luis M

    2016-04-19

    The vast majority of the outstanding applications of metal nanoparticles (NPs) developed during the last two decades have arisen from their unique optical properties. Within this context, rational synthesis and assembly of gold NPs have been the main research focus, aiming at the design of nanoplasmonic devices with tailored optical functionalities. The progress made in this field is thus to be ascribed to the understanding of the origin of the interaction between light and such gold nanostructures, the dynamics of which have been thoroughly investigated with significant contributions from short and ultrashort pulse laser technologies. We focus this Account on the potential of pulse lasers to provide new fundamental insights into the electron dynamics involved in the interaction of light with the free conduction electrons of Au NPs, that is, localized surface plasmon resonances (LSPRs). The excitation of LSPRs with a femtosecond pulse laser is followed by thermalization of the Au NP electrons and the subsequent relaxation of the nanocrystal lattice and the surrounding environment, which generally results in surface melting. By contrast, nanosecond irradiation usually induces AuNP fragmentation and uncontrolled melting due to overlapping excitation and relaxation phenomena. These concepts have been exploited toward the preparation of highly monodisperse gold nanospheres via pulse laser irradiation of polyhedral nanocrystal colloids, or in the fabrication of nanostructures with "written-in" optical properties. The applicability of pulsed coherent light has been extended toward the direct synthesis and manipulation of Au NPs. Through ablation of a gold target in a liquid with pulse lasers, spherical Au NPs can be synthesized with no need of stabilizing ligands, which is a great advantage in terms of reducing toxicity, rendering these NPs particularly suitable for medical applications. In addition, femtosecond laser irradiation has been proven a unique tool for the

  11. Reshaping, Fragmentation, and Assembly of Gold Nanoparticles Assisted by Pulse Lasers.

    Science.gov (United States)

    González-Rubio, Guillermo; Guerrero-Martínez, Andrés; Liz-Marzán, Luis M

    2016-04-19

    The vast majority of the outstanding applications of metal nanoparticles (NPs) developed during the last two decades have arisen from their unique optical properties. Within this context, rational synthesis and assembly of gold NPs have been the main research focus, aiming at the design of nanoplasmonic devices with tailored optical functionalities. The progress made in this field is thus to be ascribed to the understanding of the origin of the interaction between light and such gold nanostructures, the dynamics of which have been thoroughly investigated with significant contributions from short and ultrashort pulse laser technologies. We focus this Account on the potential of pulse lasers to provide new fundamental insights into the electron dynamics involved in the interaction of light with the free conduction electrons of Au NPs, that is, localized surface plasmon resonances (LSPRs). The excitation of LSPRs with a femtosecond pulse laser is followed by thermalization of the Au NP electrons and the subsequent relaxation of the nanocrystal lattice and the surrounding environment, which generally results in surface melting. By contrast, nanosecond irradiation usually induces AuNP fragmentation and uncontrolled melting due to overlapping excitation and relaxation phenomena. These concepts have been exploited toward the preparation of highly monodisperse gold nanospheres via pulse laser irradiation of polyhedral nanocrystal colloids, or in the fabrication of nanostructures with "written-in" optical properties. The applicability of pulsed coherent light has been extended toward the direct synthesis and manipulation of Au NPs. Through ablation of a gold target in a liquid with pulse lasers, spherical Au NPs can be synthesized with no need of stabilizing ligands, which is a great advantage in terms of reducing toxicity, rendering these NPs particularly suitable for medical applications. In addition, femtosecond laser irradiation has been proven a unique tool for the

  12. Acceleration of neutral atoms in strong short-pulse laser fields.

    Science.gov (United States)

    Eichmann, U; Nubbemeyer, T; Rottke, H; Sandner, W

    2009-10-29

    A charged particle exposed to an oscillating electric field experiences a force proportional to the cycle-averaged intensity gradient. This so-called ponderomotive force plays a major part in a variety of physical situations such as Paul traps for charged particles, electron diffraction in strong (standing) laser fields (the Kapitza-Dirac effect) and laser-based particle acceleration. Comparably weak forces on neutral atoms in inhomogeneous light fields may arise from the dynamical polarization of an atom; these are physically similar to the cycle-averaged forces. Here we observe previously unconsidered extremely strong kinematic forces on neutral atoms in short-pulse laser fields. We identify the ponderomotive force on electrons as the driving mechanism, leading to ultrastrong acceleration of neutral atoms with a magnitude as high as approximately 10(14) times the Earth's gravitational acceleration, g. To our knowledge, this is by far the highest observed acceleration on neutral atoms in external fields and may lead to new applications in both fundamental and applied physics. PMID:19865167

  13. Sulfur hexafluoride reprocessing system design for a large pulsed power accelerator

    International Nuclear Information System (INIS)

    The Particle Beam Fusion Accelerator-II (PBFA-II) is a large, high power accelerator being constructed at Sandia National Labs to conduct research in inertial confinement fusion. One key to the success of this machine is the ability to produce an electrical pulse at the target with a well defined shape (power versus time). In the past at Sandia National Labs, a commercial SF6 reclaimer unit has been used to reprocess vapor. These reclaimers are well designed for their primary purpose-the reprocessing of substation transformer and circuit breaker vapor for the electrical generation industry. They are not designed to meet the more exacting needs of a research accelerator such as PBFA-II. An SF6 reprocessing system was designed for use in PBFA-II to overcome the deficiencies found in commercial reclaimers. This paper describes the requirements placed on an SF6 reprocessing system when operating in a fusion research accelerator, resulting in criteria used to design the reprocessing system, and the subsequent design implemented to meet these criteria

  14. Analysis of reactivity coefficients measured in fast critical assemblies. Application to fissile elements in Masurca

    International Nuclear Information System (INIS)

    A simple, fast and sufficiently accurate method to interpret measurements of reactivity effects from sample oscillations is defined. This first-order perturbation method, based on the collision probability theory, accounts for the position of the sample in the cell and for the flux perturbation due to the sample and to its self-shielding. The method has been applied to a set of reactivity experiments carried out on a series of Pu or U cores in the Masurca, Sneak and Hermine assemblies; these provided basic information, especially on the capture cross-sections of Pu-239, U-238, higher isotopes of Pu and structural materials

  15. Neutronic calculations for a fast assembly by using two-group neutron albedo theory

    International Nuclear Information System (INIS)

    Under Two-Group Neutron Albedo Theory, the effective neutron multiplication factor, Keff, explicitly appears and therefore it is possible to obtain an explicit form of variation of Keff. A generalization of the two-group albedo theory can be used if a more detailed energy spectrum treatment is required. The two-group neutron albedo theory is well illustrated by the endeavor of calculating the key parameters for a fast assembly. The results obtained from diffusion approach and albedo method calculations have had excellent concordance. (author)

  16. Multi-Pulse Laser Wakefield Acceleration: A New Route to Efficient, High-Repetition-Rate Plasma Accelerators and High Flux Radiation Sources

    CERN Document Server

    Hooker, S M; Mangles, S P D; Tünnermann, A; Corner, L; Limpert, J; Seryi, A; Walczak, R

    2014-01-01

    Laser-driven plasma accelerators can generate accelerating gradients three orders of magnitude larger than radio-frequency accelerators and have achieved beam energies above 1 GeV in centimetre long stages. However, the pulse repetition rate and wall-plug efficiency of plasma accelerators is limited by the driving laser to less than approximately 1 Hz and 0.1% respectively. Here we investigate the prospects for exciting the plasma wave with trains of low-energy laser pulses rather than a single high-energy pulse. Resonantly exciting the wakefield in this way would enable the use of different technologies, such as fibre or thin-disc lasers, which are able to operate at multi-kilohertz pulse repetition rates and with wall-plug efficiencies two orders of magnitude higher than current laser systems. We outline the parameters of efficient, GeV-scale, 10-kHz plasma accelerators and show that they could drive compact X-ray sources with average photon fluxes comparable to those of third-generation light source but wi...

  17. Inferences from the Distributions of Fast Radio Burst Pulse Widths, Dispersion Measures and Fluences

    CERN Document Server

    Katz, J I

    2015-01-01

    The widths, dispersion measures, dispersion indices and fluences of Fast Radio Bursts (FRB) impose coupled constraints that all models must satisfy. Observation of dispersion indices close to their low density limit of $-2$ sets a model-independent upper bound on the electron density and a lower bound on the size of any dispersive plasma cloud. The non-monotonic dependence of burst widths (after deconvolution of instrumental effects) on dispersion measure excludes the intergalactic medium as the location of scattering that broadens the FRB in time. Temporal broadening far greater than that of pulsars at similar high Galactic latitudes implies that scattering occurs close to the sources, where high densities and strong turbulence are plausible. FRB energetics are consistent with supergiant pulses from young, fast, high-field pulsars at cosmological distances. The distribution of FRB dispersion measures is inconsistent with expanding clouds (such as SNR). It excludes space-limited distributions (such as the loc...

  18. Fast neutron flux analyzer with real-time digital pulse shape discrimination

    Science.gov (United States)

    Ivanova, A. A.; Zubarev, P. V.; Ivanenko, S. V.; Khilchenko, A. D.; Kotelnikov, A. I.; Polosatkin, S. V.; Puryga, E. A.; Shvyrev, V. G.; Sulyaev, Yu. S.

    2016-08-01

    Investigation of subthermonuclear plasma confinement and heating in magnetic fusion devices such as GOL-3 and GDT at the Budker Institute (Novosibirsk, Russia) requires sophisticated equipment for neutron-, gamma- diagnostics and upgrading data acquisition systems with online data processing. Measurement of fast neutron flux with stilbene scintillation detectors raised the problem of discrimination of the neutrons (n) from background cosmic particles (muons) and neutron-induced gamma rays (γ). This paper describes a fast neutron flux analyzer with real-time digital pulse-shape discrimination (DPSD) algorithm FPGA-implemented for the GOL-3 and GDT devices. This analyzer was tested and calibrated with the help of 137Cs and 252Cf radiation sources. The Figures of Merit (FOM) calculated for different energy cuts are presented.

  19. The affect of erbium hydride on the conversion efficience to accelerated protons from ultra-shsort pulse laser irradiated foils

    Energy Technology Data Exchange (ETDEWEB)

    Offermann, Dustin Theodore [The Ohio State Univ., Columbus, OH (United States)

    2008-01-01

    This thesis work explores, experimentally, the potential gains in the conversion efficiency from ultra-intense laser light to proton beams using erbium hydride coatings. For years, it has been known that contaminants at the rear surface of an ultra-intense laser irradiated thin foil will be accelerated to multi-MeV. Inertial Confinement Fusion fast ignition using proton beams as the igniter source requires of about 1016 protons with an average energy of about 3MeV. This is far more than the 1012 protons available in the contaminant layer. Target designs must include some form of a hydrogen rich coating that can be made thick enough to support the beam requirements of fast ignition. Work with computer simulations of thin foils suggest the atomic mass of the non-hydrogen atoms in the surface layer has a strong affect on the conversion efficiency to protons. For example, the 167amu erbium atoms will take less energy away from the proton beam than a coating using carbon with a mass of 12amu. A pure hydrogen coating would be ideal, but technologically is not feasible at this time. In the experiments performed for my thesis, ErH3 coatings on 5 μm gold foils are compared with typical contaminants which are approximately equivalent to CH1.7. It will be shown that there was a factor of 1.25 ± 0.19 improvement in the conversion efficiency for protons above 3MeV using erbium hydride using the Callisto laser. Callisto is a 10J per pulse, 800nm wavelength laser with a pulse duration of 200fs and can be focused to a peak intensity of about 5 x 1019W/cm2. The total number of protons from either target type was on the order of 1010. Furthermore, the same experiment was performed on the Titan laser, which has a 500fs pulse duration, 150J of energy and can be focused to about 3 x 1020 W/cm2. In this experiment 1012 protons were seen from both erbium hydride and

  20. Nonlinear Stabilization of High-Energy and Ultrashort Pulses in Passively Modelocked Lasers with Fast Saturable Absorption

    CERN Document Server

    Wang, Shaokang; Menyuk, Curtis R

    2016-01-01

    The two most commonly used models for passively modelocked lasers with fast saturable absorbers are the Haus modelocking equation (HME) and the cubic-quintic modelocking equation (CQME). The HME corresponds to a special limit of the CQME in which only a cubic nonlinearity in the fast saturable absorber is kept in the model. Here, we use singular perturbation theory to demonstrate that the CQME has a stable high-energy solution for an arbitrarily small but non-zero quintic contribution to the fast saturable absorber. As a consequence, we find that the CQME predicts the existence of stable modelocked pulses when the cubic nonlinearity is orders of magnitude larger than the value at which the HME predicts that modelocked pulses become unstable. This intrinsically larger stability range is consistent with experiments. Our results suggest a possible path to obtain high-energy and ultrashort pulses by fine tuning the higher-order nonlinear terms in the fast saturable absorber.

  1. Shaping of intensive secondary pulsed molecular beam and production of accelerated molecules and radicals in it

    CERN Document Server

    Makarov, G N

    2001-01-01

    The method is described for shaping the intensive secondary pulsed molecular beam, wherein the molecules kinetic energy may be controlled through the powerful IR laser radiation by means of the molecules oscillatory excitation in the source itself. The thickening jump (the shock wave), which is formed by interaction of the intensive pulsed supersonic molecular beam (or flux) with a solid surface, is used as the secondary beam source. The intensive (>= 10 sup 2 sup 0 molecules/stere. s) beams of the SF sub 6 and CF sub 3 I molecules with the kinetic energy correspondingly equal to approximately 1.5 eV and 1.2 eV without gas-carrier and molecular SF sub 6 beams with kinetic energy approx = 2.5 eV are obtained. The spectral and energy characteristics of the SF sub 6 molecules acceleration in the secondary beam are studied. The possibility of obtaining the accelerated radicals in the secondary molecular beam is indicated

  2. On electromagnetic acceleration of material from a plate hit by a pulsed electron beam

    International Nuclear Information System (INIS)

    An intense pulsed electron beam traversing a thin metal plate creates a volume of dense plasma. Current flows in this plasma as a result of the charge and magnetic field introduced by the relativistic electrons. A magnetic field may linger after the electron beam pulse because of the conductivity of the material. This field decays by both diffusing out of the conducting matter and causing it to expand. If the magnetized matter is of low density and high conductivity it may expand quickly. Scaling laws for this acceleration are sought by analyzing the idealization of a steady axisymmetric flow. This case simplifies a general formulation based on both Euler's and Maxwell's equations. As an example, fluid with conductivity σ = 8 x 104 Siemens/m, density ρ = 8 x 10-3 kg/m3, and initially magnetized to B = 1 Tesla can accelerate to v = 104 m/s within a distance comparable to L = 1 mm and a time comparable to σμL2 = 100 ns, which is the magnetic diffusion time. If instead, σ = 8 x 103 Siemens/m and ρ = 8 x 10-5 kg/m3 then v 105 m/s with a magnetic diffusion time σμL2 = 10 ns. These idealized flows have RM = σμvL = 1, where RM is the magnetic Reynolds number. The target magnetizes by a thermal electric effect

  3. Fast, transient cardiac accelerations and decelerations during fear conditioning in rats.

    Science.gov (United States)

    Knippenberg, J M J; Barry, R J; Kuniecki, M J; van Luijtelaar, G

    2012-02-01

    The current study reports on a number of heart rate responses observed in rats subjected to a discriminatory Pavlovian fear conditioning procedure. Rats learned that a series of six auditory pips was followed by a footshock when presented alone, but not when the pip series was preceded by a visual safety signal. Each auditory pip in the series evoked a fast transient (transient decelerations are similar to the human Evoked Cardiac Response 1 (ECR1), a brief modest deceleration evoked by simple sensory stimuli that is thought to reflect an early process of stimulus registration. Immediately following these pip-evoked decelerations, modest fast accelerations were observed. These accelerations were larger when the pip series was followed by shock than when it was not followed by shock. We propose a potential linkage between these accelerations and the human acceleratory ECR2 component, which is associated with more elaborate processing following stimulus registration; something likely to take place when the pip series predicts an aversive event. Both the ECR1- and ECR2-like responses were embedded within a slow, gradual heart rate increase across the entire pip series. This tonic increase was significantly larger on trials with footshock and is therefore probably associated with anticipatory fear of the upcoming shock. An additional special type of cardiac response was found to the first pip in the series not preceded by the safety signal; here, a much larger and more sustained deceleration was apparent. This response appears relatable to the prolonged deceleration reported in humans in response to aversive picture content. We discuss the cardiac responses found in rats in the current study in the context of heart rate responses known in the human literature.

  4. Observational and Theoretical Challenges to Wave or Turbulence Accelerations of the Fast Solar Wind

    Science.gov (United States)

    Roberts, D. Aaron

    2008-01-01

    We use both observations and theoretical considerations to show that hydromagnetic waves or turbulence cannot produce the acceleration of the fast solar wind and the related heating of the open solar corona. Waves do exist as shown by Hinode and other observations, and can play a role in the differential heating and acceleration of minor ions but their amplitudes are not sufficient to power the wind, as demonstrated by extrapolation of magnetic spectra from Helios and Ulysses observations. Dissipation mechanisms invoked to circumvent this conclusion cannot be effective for a variety of reasons. In particular, turbulence does not play a strong role in the corona as shown by both eclipse observations of coronal striations and theoretical considerations of line-tying to a nonturbulent photosphere, nonlocality of interactions, and the nature of kinetic dissipation. In the absence of wave heating and acceleration, the chromosphere and transition region become the natural source of open coronal energization. We suggest a variant of the velocity filtration approach in which the emergence and complex churning of the magnetic flux in the chromosphere and transition region continuously and ubiquitously produces the nonthermal distributions required. These particles are then released by magnetic carpet reconnection at a wide range of scales and produce the wind as described in kinetic approaches. Since the carpet reconnection is not the main source of the energization of the plasma, there is no expectation of an observable release of energy in nanoflares.

  5. Advanced laser particle accelerator development at LANL: from fast ignition to radiation oncology

    Energy Technology Data Exchange (ETDEWEB)

    Flippo, Kirk A [Los Alamos National Laboratory; Gaillard, Sandrine A [Los Alamos National Laboratory; Offermann, D T [Los Alamos National Laboratory; Cobble, J A [Los Alamos National Laboratory; Schmitt, M J [Los Alamos National Laboratory; Gautier, D C [Los Alamos National Laboratory; Kwan, T J T [Los Alamos National Laboratory; Montgomery, D S [Los Alamos National Laboratory; Kluge, Thomas [FZD-GERMANY; Bussmann, Micheal [FZD-GERMANY; Bartal, T [UCSD; Beg, F N [UCSD; Gall, B [UNIV OF MISSOURI; Geissel, M [SNL; Korgan, G [NANOLABZ; Kovaleski, S [UNIV OF MISSOURI; Lockard, T [UNIV OF NEVADA; Malekos, S [NANOLABZ; Schollmeier, M [SNL; Sentoku, Y [UNIV OF NEVADA; Cowan, T E [FZD-GERMANY

    2010-01-01

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, SN M detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high current and high energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology in conjunction with our partners at the ForschungsZentrum Dresden-Rossendorf (FZD). Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent etliciencies of >5% from flat foils, on Trident using only a 5th of the intensity and energy of the Nova Petawatt. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  6. Advanced Laser Particle Accelerator Development at LANL: From Fast Ignition to Radiation Oncology

    Science.gov (United States)

    Flippo, K. A.; Gaillard, S. A.; Kluge, T.; Bussmann, M.; Offermann, D. T.; Cobble, J. A.; Schmitt, M. J.; Bartal, T.; Beg, F. N.; Cowan, T. E.; Gall, B.; Gautier, D. C.; Geissel, M.; Kwan, T. J.; Korgan, G.; Kovaleski, S.; Lockard, T.; Malekos, S.; Montgomery, D. S.; Schollmeier, M.; Sentoku, Y.

    2010-11-01

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, Special Nuclear Material (SNM) detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high-current and high-energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology. Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent efficiencies of >5% from flat foils, on Trident using only a 5th of the intensity [1] and energy of the Nova Petawatt laser [2]. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world [3]. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  7. Jet acceleration of the fast molecular outflows in the Seyfert galaxy IC5063

    CERN Document Server

    Tadhunter, C; Rose, M; Oonk, J B R; Oosterloo, T

    2014-01-01

    Massive outflows driven by active galactic nuclei (AGN) are widely recognised to play a key role in the evolution of galaxies, heating the ambient gas, expelling it from the nuclear regions, and thereby affecting the star formation histories of the galaxy bulges. It has been proposed that the powerful jets of relativistic particles launched by some AGN can both accelerate and heat the molecular gas, which often dominates the mass budgets of the outflows. However, clear evidence for this mechanism in the form of detailed associations between the molecular gas kinematics and features in the radio-emitting jets has been lacking. Here we show that the warm molecular hydrogen gas in the western radio lobe of the Seyfert galaxy IC5063 is moving at high velocities - up to 600 km/s - relative to the galaxy disk. This suggests that the molecules have been accelerated by fast shocks driven into the interstellar medium (ISM) by the expanding radio jets. These results demonstrate the general feasibility of accelerating m...

  8. Scaling magnetized liner inertial fusion on Z and future pulsed-power accelerators

    International Nuclear Information System (INIS)

    The MagLIF (Magnetized Liner Inertial Fusion) concept [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)] has demonstrated fusion–relevant plasma conditions [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] on the Z accelerator with a peak drive current of about 18 MA. We present 2D numerical simulations of the scaling of MagLIF on Z as a function of drive current, preheat energy, and applied magnetic field. The results indicate that deuterium-tritium (DT) fusion yields greater than 100 kJ could be possible on Z when all of these parameters are at the optimum values: i.e., peak current = 25 MA, deposited preheat energy = 5 kJ, and Bz = 30 T. Much higher yields have been predicted [S. A. Slutz and R. A. Vesey, Phys. Rev. Lett. 108, 025003 (2012)] for MagLIF driven with larger peak currents. Two high performance pulsed-power accelerators (Z300 and Z800) based on linear-transformer-driver technology have been designed [W. A. Stygar et al., Phys. Rev. ST Accel. Beams 18, 110401 (2015)]. The Z300 design would provide 48 MA to a MagLIF load, while Z800 would provide 65 MA. Parameterized Thevenin-equivalent circuits were used to drive a series of 1D and 2D numerical MagLIF simulations with currents ranging from what Z can deliver now to what could be achieved by these conceptual future pulsed-power accelerators. 2D simulations of simple MagLIF targets containing just gaseous DT have yields of 18 MJ for Z300 and 440 MJ for Z800. The 2D simulated yield for Z800 is increased to 7 GJ by adding a layer of frozen DT ice to the inside of the liner

  9. Multi-charged heavy ion acceleration from the ultra-intense short pulse laser system interacting with the metal target

    Science.gov (United States)

    Nishiuchi, M.; Sakaki, H.; Maeda, S.; Sagisaka, A.; Pirozhkov, A. S.; Pikuz, T.; Faenov, A.; Ogura, K.; Kanasaki, M.; Matsukawa, K.; Kusumoto, T.; Tao, A.; Fukami, T.; Esirkepov, T.; Koga, J.; Kiriyama, H.; Okada, H.; Shimomura, T.; Tanoue, M.; Nakai, Y.; Fukuda, Y.; Sakai, S.; Tamura, J.; Nishio, K.; Sako, H.; Kando, M.; Yamauchi, T.; Watanabe, Y.; Bulanov, S. V.; Kondo, K.

    2014-02-01

    Experimental demonstration of multi-charged heavy ion acceleration from the interaction between the ultra-intense short pulse laser system and the metal target is presented. Al ions are accelerated up to 12 MeV/u (324 MeV total energy). To our knowledge, this is far the highest energy ever reported for the case of acceleration of the heavy ions produced by the high intensity laser field of ˜1021 W cm-2, the accelerated ions are almost fully stripped, having high charge to mass ratio (Q/M).

  10. Report of specialists' meeting on 'pulse reactor using the particle accelerators'

    International Nuclear Information System (INIS)

    KUR was decided to be continued to operate at the Reactor Laboratory according to the report on 'How to investigate the reactor for study in the Universities' published by Committee of Science Consideration on July, 1997. However, it is necessary to proceed the next program based on the KUR study results in future. From a viewpoint of the study, on considering of beginning of the next program during using KUR still but not establishing it after wasting the KUR, it is preferable to be an equipment with complemental characters for the KUR. As the pulse neutron source, spallation neutron source using large intensity proton accelerator with about 1 GeV is focused most of interests. Use of the proton beam with large neutron generation in comparison with electron beam can make non-critical collector with relatively large non-critical ratio to a target, and can obtain safety without any change of reactivity by means of mechanical method. Furthermore, this accelerator has some times of the non-critical ratio in comparison with the spallation method using only accelerator and has a feature to be low in its cost. In this report, its program, 11 items of lectures and general discussion on them were described. (G.K.)

  11. Petawatt laser-driven wakefield accelerator: All-optical electron injection via collision of laser pulses and radiation cooling of accelerated electron bunches.

    Science.gov (United States)

    Kalmykov, Serguei; Avitzour, Yoav; Yi, S. Austin; Shvets, Gennady

    2007-11-01

    We explore an electron injection into the laser wakefield accelerator (LWFA) using nearly head-on collision of the petawatt ultrashort (˜30 fs) laser pulse (driver) with a low- amplitude laser (seed) beam of the same duration and polarization. To eliminate the threat to the main laser amplifier we consider two options: (i) a frequency-shifted seed and (ii) a seed pulse propagating at a small angle to the axis. We show that the emission of synchrotron radiation due to betatron oscillations of trapped and accelerated electrons results in significant transverse cooling of quasi- monoenergetic accelerated electrons (with energies above 1 GeV). At the same time, the energy losses due to the synchrotron emission preserve the final energy spread of the electron beam. The ``dark current'' due to the electron trapping in multiple wake buckets and the effect of beam loading (wake destruction at the instant of beams collision) are discussed.

  12. Effects of substrate temperature on nanoparticle-assembled Fe films produced by ultrafast pulsed laser deposition

    International Nuclear Information System (INIS)

    Highlights: ► Effects of substrate temperature on nanoparticle-assembled Fe films produced by fs-PLD. ► Low temperature magnetic behavior of nanoparticle-assembled Fe films produced by fs-PLD. ► Role played by the Fe oxide shell in stabilizing the core magnetic moments. ► Influence of the spin disorder in surface oxidized Fe nanoparticles on low temperature coercivity. - Abstract: Ultrafast pulsed laser deposition is an interesting technique for the synthesis of nanoparticles (NP) and NP-assembled films (NPA). The NPA films show a structure with agglomerates of NPs sticking to one another, with a significant shape and orientation anisotropy and negligible coalescence. In this communication, we report preliminary results concerning the effect of the substrate temperature on the magnetic response of the NPA films in the case of Fe NPs deposited on Si (1 0 0). The experimental data evidence a clear role of the substrate temperature on the hysteresis loop of the deposited NPA films due to the aggregation and oxidation degree of the NPs.

  13. The need to address the larger universe of HEU-fueled reactors, including critical assemblies, pulsed reactors and propulsion reactors

    International Nuclear Information System (INIS)

    Full text: The RERTR program has focused thus far primarily on ending shipments of HEU fuel to research reactors. This has resulted in giving highest priority to reactors with steady thermal powers of 1 megawatt or more, because they require regular refuelling. Critical facilities and pulsed reactors can also of serious concern, because some of them contain very large amounts of barely-irradiated HEU and plutonium. They could be costly to convert - and conversion to LEU may be impractical for fast-neutron critical assemblies. An assessment should be carried out first, therefore, as to which are still needed. Critical assemblies are required today primarily to benchmark Monte Carlo neutron-transport codes. Perhaps the world nuclear community could share a few instead of each reactor-design institute having its own. There is also a whole universe of HEU-fuelled pressurized-water reactors used to power submarines and other types of nuclear-powered ships. These reactors collectively require much more HEU fuel each year than research reactors. The risk of HEU diversion from their fuel cycles is not zero but it is difficult for outsiders to discuss conversion because of the fuel designs are classified. This makes the conversion of Russia's civilian icebreaker reactors of particular interest because issues of classified fuel design are less problematic and these reactors load annually fuel containing about 400 kg of U-235. Another reason for interest in developing LEU fuel for these reactors is that the KLT-40 icebreaker reactor is being adapted for a floating nuclear power plant. Finally, the research-reactor community is, in any case, faced with developing fuels that can operate at power-reactor-fuel temperatures because there are a few high-powered research reactors that operate in this temperature range. (author)

  14. Characterization of electrons and x-rays produced using chirped laser pulses in a laser wakefield accelerator

    Science.gov (United States)

    Zhao, T. Z.; Behm, K.; He, Z.-H.; Maksimchuk, A.; Nees, J. A.; Yanovsky, V.; Thomas, A. G. R.; Krushelnick, K.

    2016-11-01

    The electron injection process into a plasma-based laser wakefield accelerator can be influenced by modifying the parameters of the driver pulse. We present an experimental study on the combined effect of the laser pulse duration, pulse shape, and frequency chirp on the electron injection and acceleration process and the associated radiation emission for two different gas types—a 97.5% He and 2.5% N2 mixture and pure He. In general, the shortest pulse duration with minimal frequency chirp produced the highest energy electrons and the most charge. Pulses on the positive chirp side sustained electron injection and produced higher charge, but lower peak energy electrons, compared with negatively chirped pulses. A similar trend was observed for the radiant energy. The relationship between the radiant energy and the electron charge remained linear over a threefold change in the electron density and was independent of the drive pulse characteristics. X-ray spectra showed that ionization injection of electrons into the wakefield generally produced more photons than self-injection for all pulse durations/frequency chirp and had less of a spread in the number of photons around the peak x-ray energy.

  15. Two-dimensional angular energy spectrum of electrons accelerated by the ultra-short relativistic laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Borovskiy, A. V. [Department of Computer Science and Cybernetics, Baikal State University of Economics and Law, 11 Lenin Street, Irkutsk 664003 (Russian Federation); Galkin, A. L. [Coherent and Nonlinear Optics Department, A.M. Prokhorov General Physics Institute of the RAS, 38 Vavilov Street, Moscow 119991 (Russian Federation); Department of Physics of MBF, Pirogov Russian National Research Medical University, 1 Ostrovitianov Street, Moscow 117997 (Russian Federation); Kalashnikov, M. P., E-mail: galkin@kapella.gpi.ru [Max-Born-Institute for Nonlinear Optics and Short-Time Spectroscopy, 2a Max-Born-Strasse, Berlin 12489 (Germany)

    2015-04-15

    The new method of calculating energy spectra of accelerated electrons, based on the parameterization by their initial coordinates, is proposed. The energy spectra of electrons accelerated by Gaussian ultra-short relativistic laser pulse at a selected angle to the axis of the optical system focusing the laser pulse in a low density gas are theoretically calculated. The two-peak structure of the electron energy spectrum is obtained. Discussed are the reasons for its appearance as well as an applicability of other models of the laser field.

  16. Enabling pulse compression and proton acceleration in a modular ICF driver for nuclear and particle physics applications

    CERN Document Server

    Terranova, F; Collier, J L; Kiriyama, H; Pegoraro, F

    2005-01-01

    The existence of efficient ion acceleration regimes in collective laser-plasma interactions opens up the possibility to develop high-energy physics facilities in conjunction with projects for inertial confinement nuclear fusion (ICF) and neutron spallation sources. In this paper, we show that the pulse compression requests to make operative these acceleration mechanisms do not fall in contradiction with current designs for an ICF driver. In particular, we discuss explicitly a solution that exploits optical parametric chirped pulse amplification and the intrinsic modularity of ICF power plants.

  17. Accelerator-based neutron source for the neutron-capture and fast neutron therapy at hospital

    Science.gov (United States)

    Bayanov, B. F.; Belov, V. P.; Bender, E. D.; Bokhovko, M. V.; Dimov, G. I.; Kononov, V. N.; Kononov, O. E.; Kuksanov, N. K.; Palchikov, V. E.; Pivovarov, V. A.; Salimov, R. A.; Silvestrov, G. I.; Skrinsky, A. N.; Soloviov, N. A.; Taskaev, S. Yu.

    The proton accelerator complex for neutron production in lithium target discussed, which can operate in two modes. The first provides a neutron beam kinematically collimated with good forward direction in 25° and average energy of 30 keV, directly applicable for neutron-capture therapy with high efficiency of proton beam use. The proton energy in this mode is 1.883-1.890 MeV that is near the threshold of the 7Li( p, n) 7Be reaction. In the second mode, at proton energy of 2.5 MeV, the complex-produced neutron beam with maximum energy board of 790 keV which can be used directly for fast neutron therapy and for neutron-capture therapy after moderation. The project of such a neutron source is based on the 2.5 MeV original electrostatic accelerator tandem with vacuum insulation developed at BINP which is supplied with a high-voltage rectifier. The rectifier is produced in BINP as a part of ELV-type industrial accelerator. Design features of the tandem determining its high reliability in operation with a high-current (up to 40 mA) H - ion beam are discussed. They are: the absence of ceramic accelerator columns around the beam passage region, good conditions for pumping out of charge-exchange gaseous target region, strong focusing optics and high acceleration rate minimizing the space charge effects. The possibility of stabilization of protons energy with an accuracy level of 0.1% necessary for operation in the near threshold region is considered. The design description of H - continuous ion source with a current of 40 mA is also performed. To operate with a 100 kW proton beam it is proposed to use liquid-lithium targets. A thin lithium layer on the surface of a tungsten disk cooled intensively by a liquid metal heat carrier is proposed for use in case of the vertical beam, and a flat liquid lithium jet flowing through the narrow nozzle - for the horizontal beam.

  18. The role of fast magnetic reconnection in acceleration zones of microquasars and AGNs

    CERN Document Server

    Kadowaki, L H S

    2013-01-01

    Fast magnetic reconnection events can be a very powerful mechanism operating at the jet launching region of microquasars and AGNs. We have recently found that the power released by reconnection between the magnetic field lines of the coronal inner disk region and the lines anchored into the black hole is able to accelerate relativistic particles through a first-order Fermi process and produce the observed radio luminosity from both microquasars and low luminous AGNs (LLAGNs). We also found that the observed correlation between the radio luminosity and the mass of these sources, spanning 10^9 orders of magnitude in mass, is naturally explained by this process. In this work, assuming that the gamma-ray emission is probably originated in the same acceleration zones that produce the radio emission, we have applied the scenario above to investigate the origin of the high energy outcomes from an extensive number of sources including high (HLAGNs) and LLAGNs, microquasars and GRBs. We find correlation of our model w...

  19. Enabling pulse compression and proton acceleration in a modular ICF driver for nuclear and particle physics applications

    OpenAIRE

    Terranova, F.; Bulanov, S. V.; Collier, J L; Kiriyama, H.; Pegoraro, F.

    2005-01-01

    The existence of efficient ion acceleration regimes in collective laser-plasma interactions opens up the possibility to develop high-energy physics facilities in conjunction with projects for inertial confinement nuclear fusion (ICF) and neutron spallation sources. In this paper, we show that the pulse compression requests to make operative these acceleration mechanisms do not fall in contradiction with current technologies for high repetition rate ICF drivers. In particular, we discuss expli...

  20. Ultra-Fast Decay Process of Electrons in LiNbO3 Crystal Induced by Femtosecond Pulse

    Institute of Scientific and Technical Information of China (English)

    CHEN Li; JIANG Hong-Bing; ZHANG Xi-Peng; TANG Shan-Chun; YANG Hong; GONG Qi-Huang

    2007-01-01

    Temporal evolution of absorption induced by single femtosecond pulse (130fs, 800nm) with high intensity in LiNbO3 is obtained using the probe shadow imaging technique in order to investigate light-induced electron relaxation processes. By saturating the polaron density with a high intensity laser pulse, ultra-fast decay process on picosecond time scale is observed. The decay time constant is about 141 ps and it is attributed to the direct interband electron-hole recombination process.

  1. Development of numerical simulation system for thermal-hydraulic analysis in fuel assembly of sodium-cooled fast reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ohshima, Hiroyuki; Uwaba, Tomoyuki [Japan Atomic Energy Agency (4002 Narita, O-arai, Ibaraki 311-1393, Japan) (Japan); Hashimoto, Akihiko; Imai, Yasutomo [NDD Corporation (1-1-6 Jounan, Mito, Ibaraki 310-0803, Japan) (Japan); Ito, Masahiro [NESI Inc. (4002 Narita, O-arai, Ibaraki 311-1393, Japan) (Japan)

    2015-12-31

    A numerical simulation system, which consists of a deformation analysis program and three kinds of thermal-hydraulics analysis programs, is being developed in Japan Atomic Energy Agency in order to offer methodologies to clarify thermal-hydraulic phenomena in fuel assemblies of sodium-cooled fast reactors under various operating conditions. This paper gives the outline of the system and its applications to fuel assembly analyses as a validation study.

  2. Development of numerical simulation system for thermal-hydraulic analysis in fuel assembly of sodium-cooled fast reactor

    Science.gov (United States)

    Ohshima, Hiroyuki; Uwaba, Tomoyuki; Hashimoto, Akihiko; Imai, Yasutomo; Ito, Masahiro

    2015-12-01

    A numerical simulation system, which consists of a deformation analysis program and three kinds of thermal-hydraulics analysis programs, is being developed in Japan Atomic Energy Agency in order to offer methodologies to clarify thermal-hydraulic phenomena in fuel assemblies of sodium-cooled fast reactors under various operating conditions. This paper gives the outline of the system and its applications to fuel assembly analyses as a validation study.

  3. Development of numerical simulation system for thermal-hydraulic analysis in fuel assembly of sodium-cooled fast reactor

    International Nuclear Information System (INIS)

    A numerical simulation system, which consists of a deformation analysis program and three kinds of thermal-hydraulics analysis programs, is being developed in Japan Atomic Energy Agency in order to offer methodologies to clarify thermal-hydraulic phenomena in fuel assemblies of sodium-cooled fast reactors under various operating conditions. This paper gives the outline of the system and its applications to fuel assembly analyses as a validation study

  4. Optimized Fast-FISH with a-satellite probes: acceleration by microwave activation

    Directory of Open Access Journals (Sweden)

    Durm M.

    1997-01-01

    Full Text Available It has been shown for several DNA probes that the recently introduced Fast-FISH (fluorescence in situ hybridization technique is well suited for quantitative microscopy. For highly repetitive DNA probes the hybridization (renaturation time and the number of subsequent washing steps were reduced considerably by omitting denaturing chemical agents (e.g., formamide. The appropriate hybridization temperature and time allow a clear discrimination between major and minor binding sites by quantitative fluorescence microscopy. The well-defined physical conditions for hybridization permit automatization of the procedure, e.g., by a programmable thermal cycler. Here, we present optimized conditions for a commercially available X-specific a-satellite probe. Highly fluorescent major binding sites were obtained for 74oC hybridization temperature and 60 min hybridization time. They were clearly discriminated from some low fluorescent minor binding sites on metaphase chromosomes as well as in interphase cell nuclei. On average, a total of 3.43 ± 1.59 binding sites were measured in metaphase spreads, and 2.69 ± 1.00 in interphase nuclei. Microwave activation for denaturation and hybridization was tested to accelerate the procedure. The slides with the target material and the hybridization buffer were placed in a standard microwave oven. After denaturation for 20 s at 900 W, hybridization was performed for 4 min at 90 W. The suitability of a microwave oven for Fast-FISH was confirmed by the application to a chromosome 1-specific a-satellite probe. In this case, denaturation was performed at 630 W for 60 s and hybridization at 90 W for 5 min. In all cases, the results were analyzed quantitatively and compared to the results obtained by Fast-FISH. The major binding sites were clearly discriminated by their brightness

  5. Design and construction of the clean room for proton beam accelerator assembly

    International Nuclear Information System (INIS)

    The objective of this report is to design, construction and evaluation of clean room for proton beam accelerator assembly. The design conditions o Class : 1,000(1,000 ea ft3), o Flow Rate : 200 m3/h m2, o Temperature : 22 deg C±2, o Humidity : 55%±5. The main design results are summarized as follows: o Air-handling unit : Cooling Capacity : 13,500 kcal/h, Heating Capacity : 10,300 kcal/h, Humidity Capacity : 4 kg/h, Flow Rate : 150 CMM o Air Shower : Flow Rate : 35 CMM, Size : 1500 x 1000 x 2200, Material : In-steel, Out-SUS304, Filter : PRE + HEPA, AIR Velocity : 25 m/s o Relief Damper : Size : Φ250, Casing : SS41, Blade : AL, Shaft : SUS304, Weight Ring : SS41, Grill : AL o HEPA Filter Box : Filter Box Size : 670 x 670 x 630, Filter Size : 610 x 610 x 150, Frame: Poly Wood, Media : Glass Fiber, Filter Efficiency : 0.3μm, 99.97%, Separator : AL, Flow Rate : 17 CMM, Damper Size : Φ300 Following this report will be used important data for the design, construction, operation and maintenance of the clean room, for high precision apparatus assembly laboratory

  6. Self-confinement of a fast pulsed electron beam generated in a double discharge

    Energy Technology Data Exchange (ETDEWEB)

    Goktas, H [Ankara Nuclear Research and Training Center, 06501, Besevler, Ankara (Turkey); Udrea, M [National Institute for Laser, Plasma and Radiation Physics, 76900 Bucharest (Romania); Oke, Gulay [Physics Department, Middle East Technical University, 06531 Ankara (Turkey); Alacakir, A [Ankara Nuclear Research and Training Center, 06501, Besevler, Ankara (Turkey); Demir, A [Physics Department, University of Kocaeli, 41200 Kocaeli (Turkey); Loureiro, J [Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal)

    2005-08-21

    The construction of a double discharge pulsed electron beam generator and the study of the characteristics of the beam are presented in this paper. The electron beam generator consists of a fast filamentary discharge in superposition with an ordinary glow discharge in low-pressure gases. The filling gas is argon or helium at approximately 0.1 Torr pressure. The duration of the electron beam is shorter than 50 ns and the peak current intensity is of the order of amperes. The electron density is evaluated by making use of Stark broadening of the H{sub {beta}} line and compared with the full computer simulation method. The pinch effect of the filamentary discharge is evaluated and its size compared with the diameter of the beam.

  7. Status of the design concepts for a high fluence fast pulse reactor (HFFPR)

    Energy Technology Data Exchange (ETDEWEB)

    Philbin, J.S.; Nelson, W.E.; Rosenstroch, B.

    1978-10-01

    The report describes progress that has been made on the design of a High Fluence Fast Pulse Reactor (HFFPR) through the end of calendar year 1977. The purpose of this study is to present design concepts for a test reactor capable of accommodating large scale reactor safety tests. These concepts for reactor safety tests are adaptations of reactor concepts developed earlier for DOE/OMA for the conduct of weapon effects tests. The preferred driver core uses fuel similar to that developed for Sandia's ACPR upgrade. It is a BeO/UO/sub 2/ fuel that is gas cooled and has a high volumetric heat capacity. The present version of the design can drive large (217) pin bundles of prototypically enriched mixed oxide fuel well beyond the fuel's boiling point. Applicability to specific reactor safety accident scenarios and subsequent design improvements will be presented in future reports on this subject.

  8. Fast repair of oxidizing OH adducts of DNA by hydroxycinnamic acid derivatives. A pulse radiolytic study

    International Nuclear Information System (INIS)

    Using pulse radiolytic techniques, it has been demonstrated that the interactions of oxidizing OH adducts of DNA (ssDNA and dsDNA), polyA and polyG with hydroxycinnamic acid derivatives proceed via an electron transfer process (k=5-30x108 dm3 mol-1 s-1). In addition, the rates for fast repair of OH adducts of dAMP, polyA and DNA (ssDNA and dsDNA) are slower than the corresponding rates for the rest OH adducts of DNA constituents. The slower rates for repair of oxidizing OH adducts of dAMP may be the rate determining step during the interaction of hydroxycinnamic acid derivatives with OH adducts of DNA containing the varieties of OH adducts of DNA constituents

  9. Measurement and Processing of Fast Pulsed Discharge Current in Plasma Focus Machines

    Science.gov (United States)

    Lee, S.; Saw, S. H.; Rawat, R. S.; Lee, P.; Verma, R.; Talebitaher, A.; Hassan, S. M.; Abdou, A. E.; Ismail, Mohamed; Mohamed, Amgad; Torreblanca, H.; Al Hawat, Sh.; Akel, M.; Chong, P. L.; Roy, F.; Singh, A.; Wong, D.; Devi, K.

    2012-04-01

    The fast pulsed electric discharge current drives all physical processes in the plasma focus device; in turn all physical processes in the focus affect the current waveform. Thus the discharge current waveform is the most important indicator of plasma focus performance. This underlies the importance of properly measuring, processing and interpreting the discharge current waveform. This paper reports the measurement of fast pulsed discharge current by the Rogowski coil, in two different modes: the current transformer, "I" mode, and current derivative, "Idot" mode. The processing and interpretation of recorded current waveform to obtain useful information about the physical processes in the plasma focus device are discussed. The current transformer with a large number of turns and a sub-1 Ohm terminator has good high frequency response, necessary for the sharp current dip region when dI/ dt exceeds 2 × 1011 A/s. However the signal is "noisy" in the current dip region. Several methods to extract the current dip from the noise are discussed and examples of how low pass filters affect the signals are shown. The dI/ dt coil, the Rogowski coil in "Idot" mode, with a few turns terminated by 50-Ohm is also described. Integrating the 1 GSa/s digital waveform does remove the high frequency noise components, yet the extracted waveform shows sharp angular features indicative of the retention of short-time features. This makes the dI/ dt coil superior to the current transformer. A 7-turn coil is tested against the Lee Model code and found to be suitable to measure the plasma focus discharge current.

  10. Acceleration of groundwater remediation by deep sweeps and vortex ejections induced by rapidly pulsed pumping

    Science.gov (United States)

    Kahler, David M.; Kabala, Zbigniew J.

    2016-05-01

    One key limiting factor to groundwater remediation is contaminant sequestered in pores whose contents do not mix well with the bulk flow. Mixing between well-connected (pores whose volume is flushed as water flows through the aquifer) and poorly connected pores (pores whose volume does not exchange readily when water flows through the aquifer) is of primary concern. Under steady flow, contaminants are effectively trapped in the poorly connected pores and are transferred only by molecular diffusion. This slow mixing process between pore types is a bottleneck to remediation. We present a novel rapidly pulsed pumping method that increases the mixing between these pore types. We do it in the context of pump-and-treat remediation because it is the most common remediation practice. In rapidly pulsed pumping, the increase in flow causes a deep sweep, which pushes the flow into poorly connected pores and sweeps out sequestered contaminants. The decrease in flow causes a vortex ejection, which causes the vortex within the poorly connected pore to emerge with contaminant. These actions are modeled with computational fluid mechanics to elucidate the individual mechanisms and determine how they function and interact. Cleanup of single and multiple poorly connected pore systems were simulated and show the acceleration possible. This technique can decrease the time and cost needed to remediate contaminated aquifers, which in the United States has been estimated to exceed $1 trillion. Since our rapidly pulsed pumping method enhances mixing between well-connected and poorly connected pores, it can be applied to other remediation schemes such as in situ methods.

  11. Pulsed VHE emission from the Crab Pulsar in the context of magnetocentrifugal particle acceleration

    CERN Document Server

    Osmanov, Z

    2016-01-01

    The Crab Pulsar has been recently detected at very high energies (VHE) with its pulsed VHE emission reaching up to $1.5$ TeV. The VHE peaks appear synchronised with the peaks at GeV energies and show VHE spectra following hard power-law functions. These new findings have been interpreted as evidence for a gamma-ray production that happens very close to the light cylinder. Motivated by these experimental results we consider the efficiency of magnetocentrifugal particle acceleration in the magnetosphere of the Crab Pulsar, reexamining and extending results obtained in a previous work (Osmanov & Rieger 2009). It is shown that efficient magnetocentrifugal acceleration close to the light cylinder could provide the required electron Lorentz factors of $5\\times 10^6$ and that the resulting inverse Compton (IC) scattering off thermal photons might explain the enigmatic TeV emission of the pulsar. We estimate the corresponding VHE luminosity and provide a derivation of its spectral characteristics, that appear rem...

  12. Ultra-fast self-assembly and stabilization of reactive nanoparticles in reduced graphene oxide films

    Science.gov (United States)

    Chen, Yanan; Egan, Garth C.; Wan, Jiayu; Zhu, Shuze; Jacob, Rohit Jiji; Zhou, Wenbo; Dai, Jiaqi; Wang, Yanbin; Danner, Valencia A.; Yao, Yonggang; Fu, Kun; Wang, Yibo; Bao, Wenzhong; Li, Teng; Zachariah, Michael R.; Hu, Liangbing

    2016-08-01

    Nanoparticles hosted in conductive matrices are ubiquitous in electrochemical energy storage, catalysis and energetic devices. However, agglomeration and surface oxidation remain as two major challenges towards their ultimate utility, especially for highly reactive materials. Here we report uniformly distributed nanoparticles with diameters around 10 nm can be self-assembled within a reduced graphene oxide matrix in 10 ms. Microsized particles in reduced graphene oxide are Joule heated to high temperature (~1,700 K) and rapidly quenched to preserve the resultant nano-architecture. A possible formation mechanism is that microsized particles melt under high temperature, are separated by defects in reduced graphene oxide and self-assemble into nanoparticles on cooling. The ultra-fast manufacturing approach can be applied to a wide range of materials, including aluminium, silicon, tin and so on. One unique application of this technique is the stabilization of aluminium nanoparticles in reduced graphene oxide film, which we demonstrate to have excellent performance as a switchable energetic material.

  13. ENDF/B-VII.0 Data Testing for Three Fast Critical Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, D E; Blomquist, R N; Brown, P N; Dean, C J; Dunn, M E; Lee, Y; Lent, E; MacFarlane, R; McKinley, S; Plechaty, E F; Sublet, J C

    2007-07-27

    In this report we consider three fast critical assemblies, each assembly is dominated by a different nuclear fuel: Godiva (U235), Jezebel (Pu239) and Jezebel23 (U233) [1]. We first show the improvement in results when using the new ENDF/B-VII.0 data [2], rather than the older, now frozen, ENDF/B-VI.8 data [3]. We do this using what we call a one code/ multiple library approach, where results from one code (MCNP) are compared using two different data libraries (ENDF/B-VII.0 and VI.8). Next we show that MCNP results are not specific to this one code by using what we call a one data library/multiple code approach; for this purpose we invited many codes to submit results using the ENDF/B-VII.0 data; the most detailed results presented in this report compare MCNP and TART. The bottom line is that we have shown that using the new ENDF/B-VII.0 data library with a variety of transport codes, for the first time we are able to reproduce the expected K-eff values for all three assemblies to within the quoted accuracy of the models, namely 1.0 +/- 0.001. This is a BIG improvement compared to the results obtained using the older ENDF/B-VI.8 data library. Another important result of this study is that we have demonstrated that currently there are many computer codes that can accurately use the new ENDF/B-VII.0 data.

  14. On the origin of the scatter broadening of fast radio burst pulses and astrophysical implications

    CERN Document Server

    Xu, Siyao

    2016-01-01

    Fast radio bursts (FRBs) have been identified as extragalactic sources which can make a probe of turbulence in the intergalactic medium (IGM) and their host galaxies. To account for the observed millisecond pulses caused by scatter broadening, we examine a variety of possible models of electron density fluctuations in both the IGM and the host galaxy medium. We find that a shallow power-law spectrum of density, which may arise in highly supersonic turbulence with pronounced local dense structures of shock-compressed gas in the host interstellar medium (ISM), can produce the required density enhancements at sufficiently small scales to interpret the scattering timescale of FRBs. It implies that an FRB residing in a galaxy with efficient star formation in action tends to have a broadened pulse. The scaling of the scattering time with dispersion measure (DM) in the host galaxy varies in different turbulence and scattering regimes. The host galaxy can be the major origin of scatter broadening, but contribute to a...

  15. Fast Back Propagation Learning Using Optimization of Learning Rate for Pulsed Neural Networks

    Science.gov (United States)

    Yamamoto, Kenji; Koakutsu, Seiichi; Okamoto, Takashi; Hirata, Hironori

    Neural Networks (NN) are widely applied to information processing because of its nonlinear processing capability. Digital hardware implementation of NN seems to be effective in construction of NN systems in which real-time operation and much further wide applications are possible. However, the digital hardware implementation of analogue NN is very difficult because we have to fulfill the restrictions about circuit resource, such as circuit scale, arrangement, and wiring. A technique that uses pulsed neuron model instead of analogue neuron model as a method of solving this problem has been proposed, and its effectiveness has been confirmed. To construct Pulsed Neural Networks (PNN), Back Propagation (BP) learning has been proposed. However, BP learning takes much time to construct PNN compared with the learning of analogue NN. Therefore some method to speed up BP learning of PNN is necessary. In this paper, we propose a fast BP learning using optimization of learning rate for PNN. In the proposed method, the learning rate is optimized so as to speed up the learning at every learning epoch. To evaluate the proposed method, we apply it to some pattern recognition problems, such as XOR, 3-bits parity, and digit recognition. Results of computational experiments indicate the validity of the proposed method.

  16. Energy Efficiency of Inductive Energy Storage System Pulsed Power Generator Using Fast Recovery Diode

    Science.gov (United States)

    Go, Tomio; Kanesawa, Kyousuke; Yamazaki, Nobuyuki; Mukaigawa, Seiji; Takaki, Koichi; Fujiwara, Tamiya

    Characteristics of inductive energy storage system pulsed power generator with semiconductor opening switch (SOS) diodes are investigated with focusing on an energy transfer efficiency from the generator to the resistive load. Fast recovery diodes VMI K100UF were used as SOS and were connected in series and/or in parallel to realize a large current and a high output voltage. The output voltage increases with increasing circuit inductance L and/or primary capacitor capacitance C. The reverse pumping time also increases with LC value and is saturated to 100 ns at LC=50×10-15 HF. The pulse width of the output voltage increases gradually with increasing value of the LC multiplication. The energy transfer efficiency of the generator to the resistive load has a maximum value of 71% at C=4nF and L=12.6μH when the load resistance is 122 Ω. This value is almost two times larger than 56 Ω of the surge impedance Zs=√L/C and much smaller than impedance of the SOS diodes after interrupting the circuit current. The maximum energy transfer efficiency decreases from 71 to 32% with decreasing LC value from 50×10-15 to 1.2×10-15 HF.

  17. Fast Prototyping of Sensorized Cell Culture Chips and Microfluidic Systems with Ultrashort Laser Pulses

    Directory of Open Access Journals (Sweden)

    Sebastian M. Bonk

    2015-03-01

    Full Text Available We developed a confined microfluidic cell culture system with a bottom plate made of a microscopic slide with planar platinum sensors for the measurement of acidification, oxygen consumption, and cell adhesion. The slides were commercial slides with indium tin oxide (ITO plating or were prepared from platinum sputtering (100 nm onto a 10-nm titanium adhesion layer. Direct processing of the sensor structures (approximately three minutes per chip by an ultrashort pulse laser facilitated the production of the prototypes. pH-sensitive areas were produced by the sputtering of 60-nm Si3N4 through a simple mask made from a circuit board material. The system body and polydimethylsiloxane (PDMS molding forms for the microfluidic structures were manufactured by micromilling using a printed circuit board (PCB milling machine for circuit boards. The microfluidic structure was finally imprinted in PDMS. Our approach avoided the use of photolithographic techniques and enabled fast and cost-efficient prototyping of the systems. Alternatively, the direct production of metallic, ceramic or polymeric molding tools was tested. The use of ultrashort pulse lasers improved the precision of the structures and avoided any contact of the final structures with toxic chemicals and possible adverse effects for the cell culture in lab-on-a-chip systems.

  18. Challenges in the Manufacture of Sub-Assemblies for the Indian Fast Reactors

    International Nuclear Information System (INIS)

    Presently NFC is manufacturing the 1st core subassemblies for PFBR. NFC is responsible for manufacturing all types of core subassemblies except for fuel pellets and its encapsulation. This involved development and manufacture of high quality nuclear grade clad tubes and hexcans through cold pilgering route, variety of large number of precision components and complete blanket and other pin manufacturing operations. Indigenous design, development and fabrication of Special Purpose Machines for variety of assembly and fabrication operations were mastered. Optimization of process parameters and quality control techniques, etc., was successfully completed. NFC has manufactured 40% of requirement of all types of replacement and shielding subassemblies for PFBR 1st core. The enormous experience gained by NFC, has given the confidence to meet any future requirements of Fast Reactors, under second stage of Indian Nuclear Power programme by DAE. The paper gives the details of various aspects of different technologies developed at NFC for the manufacture of high performance components and subassemblies for Indian Fast reactor applications. (author)

  19. Investigating the performance of an ion luminescence probe as a multichannel fast-ion energy spectrometer using pulse height analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zurro, B.; Baciero, A. [Laboratorio Nacional de Fusion, Asociacion Euratom-CIEMAT, Madrid (Spain); Jimenez-Rey, D. [Centro de Microanalisis de Materiales, Universidad Autonoma de Madrid, Madrid (Spain); Rodriguez-Barquero, L.; Crespo, M. T. [Laboratorio de Metrologia de Radiaciones lonizantes, CIEMAT, Madrid (Spain)

    2012-10-15

    We investigate the capability of a fast-ion luminescent probe to operate as a pulse height ion energy analyzer. An existing high sensitivity system has been reconfigured as a single channel ion detector with an amplifier to give a bandwidth comparable to the phosphor response time. A digital pulse processing method has been developed to determine pulse heights from the detector signal so as to obtain time-resolved information on the ion energy distribution of the plasma ions lost to the wall of the TJ-II stellarator. Finally, the potential of this approach for magnetic confined fusion plasmas is evaluated by studying representative TJ-II discharges.

  20. Scaling magnetized liner inertial fusion on Z and future pulsed-power accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Slutz, S. A.; Stygar, W. A.; Gomez, M. R.; Peterson, K. J.; Sefkow, A. B.; Sinars, D. B.; Vesey, R. A. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Campbell, E. M.; Betti, R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 146 (United States)

    2016-02-15

    The MagLIF (Magnetized Liner Inertial Fusion) concept [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)] has demonstrated fusion–relevant plasma conditions [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] on the Z accelerator with a peak drive current of about 18 MA. We present 2D numerical simulations of the scaling of MagLIF on Z as a function of drive current, preheat energy, and applied magnetic field. The results indicate that deuterium-tritium (DT) fusion yields greater than 100 kJ could be possible on Z when all of these parameters are at the optimum values: i.e., peak current = 25 MA, deposited preheat energy = 5 kJ, and B{sub z} = 30 T. Much higher yields have been predicted [S. A. Slutz and R. A. Vesey, Phys. Rev. Lett. 108, 025003 (2012)] for MagLIF driven with larger peak currents. Two high performance pulsed-power accelerators (Z300 and Z800) based on linear-transformer-driver technology have been designed [W. A. Stygar et al., Phys. Rev. ST Accel. Beams 18, 110401 (2015)]. The Z300 design would provide 48 MA to a MagLIF load, while Z800 would provide 65 MA. Parameterized Thevenin-equivalent circuits were used to drive a series of 1D and 2D numerical MagLIF simulations with currents ranging from what Z can deliver now to what could be achieved by these conceptual future pulsed-power accelerators. 2D simulations of simple MagLIF targets containing just gaseous DT have yields of 18 MJ for Z300 and 440 MJ for Z800. The 2D simulated yield for Z800 is increased to 7 GJ by adding a layer of frozen DT ice to the inside of the liner.

  1. Magnetic Measurements of Permanent and Fast-Pulsed Quadrupoles for the CERN LINAC4 Project

    CERN Document Server

    Golluccio, G; Buzio, M; Dunkel, O; Giloteaux, D; Lombardi, A; Mateo, F; Ramberger, S

    2010-01-01

    Linac4 is currently under construction at CERN to improve intensity and reliability for the whole accelerator chain. This machine will include about 120 permanent quadrupoles housed in the Drift Tube tanks, as well as about 80 electromagnetic quadrupoles. This paper describes the magnetic measurements carried out at CERN on the first batch of quadrupoles, including several prototypes from different manufacturers, as well as those done on several spare Linac 2 magnets reused in Linac4's 3 MeV test stand. We first describe a prototype test bench based on technology developed for the LHC and able to carry out high-precision harmonic measurements in both continuously-rotating and stepping-coil mode. Next we present the first results obtained in terms of field strength, harmonics quality and effects of fast eddy current transients. Finally, we discuss the expected impact of these findings on the operation of the machine.

  2. Accelerating Protons to Therapeutic Energies with Ultra-Intense Ultra-Clean and Ultra-Short Laser Pulses

    OpenAIRE

    Bulanov, Stepan S.; Brantov, Andrei; Bychenkov, Valery Yu.; Chvykov, Vladimir; Kalinchenko, Galina; Matsuoka, Takeshi; Rousseau, Pascal; Reed, Stephen; Yanovsky, Victor; Krushelnick, Karl; Litzenberg, Dale William; Maksimchuk, Anatoly

    2008-01-01

    Proton acceleration by high-intensity laser pulses from ultra-thin foils for hadron therapy is discussed. With the improvement of the laser intensity contrast ratio to 10-11 achieved on Hercules laser at the University of Michigan, it became possible to attain laser-solid interactions at intensities up to 1022 W/cm2 that allows an efficient regime of laser-driven ion acceleration from submicron foils. Particle-In-Cell (PIC) computer simulations of proton acceleration in the Directed Coulomb e...

  3. Fast neutron tomography with real-time pulse-shape discrimination in organic scintillation detectors

    Science.gov (United States)

    Joyce, Malcolm J.; Agar, Stewart; Aspinall, Michael D.; Beaumont, Jonathan S.; Colley, Edmund; Colling, Miriam; Dykes, Joseph; Kardasopoulos, Phoevos; Mitton, Katie

    2016-10-01

    A fast neutron tomography system based on the use of real-time pulse-shape discrimination in 7 organic liquid scintillation detectors is described. The system has been tested with a californium-252 source of dose rate 163 μSv/h at 1 m and neutron emission rate of 1.5×107 per second into 4π and a maximum acquisition time of 2 h, to characterize two 100×100×100 mm3 concrete samples. The first of these was a solid sample and the second has a vertical, cylindrical void. The experimental data, supported by simulations with both Monte Carlo methods and MATLAB®, indicate that the presence of the internal cylindrical void, corners and inhomogeneities in the samples can be discerned. The potential for fast neutron assay of this type with the capability to probe hydrogenous features in large low-Z samples is discussed. Neutron tomography of bulk porous samples is achieved that combines effective penetration not possible with thermal neutrons in the absence of beam hardening.

  4. Fast radio bursts as giant pulses from young rapidly rotating pulsars

    CERN Document Server

    Lyutikov, Maxim; Popov, Sergei B

    2016-01-01

    We discuss possible association of fast radio bursts (FRBs) with supergiant pulses emitted by young pulsars (ages $\\sim$ tens to hundreds of years) born with regular magnetic field but very short -- few milliseconds -- spin periods. FRBs are extra-Galactic events coming from distances $d \\lesssim 100$ Mpc. Most of the dispersion measure (DM) comes from the material in the freshly ejected SNR shell; for a given burst the DM should decrease with time. FRBs are not expected to be seen below $\\sim 300 $ MHz due to free-free absorption in the expanding ejecta. A supernova might have been detected years before the burst; FRBs are mostly associated with star forming galaxies. The model requires that some pulsars are born with very fast spins, of the order of few milliseconds. The observed distribution of spin-down powers $\\dot{E}$ in young energetic pulsars is consistent with equal birth rate per decade of $\\dot{E}$. Accepting this injection spectrum and scaling the intrinsic brightness of FRBs with $\\dot{E}$, we pr...

  5. Fast radio bursts as giant pulses from young rapidly rotating pulsars

    Science.gov (United States)

    Lyutikov, Maxim; Burzawa, Lukasz; Popov, Sergei B.

    2016-10-01

    We discuss possible association of fast radio bursts (FRBs) with supergiant pulses emitted by young pulsars (ages ˜ tens to hundreds of years) born with regular magnetic field but very short - few milliseconds - spin periods. We assume that FRBs are extra-Galactic events coming from distances d ≲ 100 Mpc and that most of the dispersion measure (DM) comes from the material in the freshly ejected SNR shell. We then predict that for a given burst the DM should decrease with time and that FRBs are not expected to be seen below ˜300 MHz due to free-free absorption in the expanding ejecta. A supernova might have been detected years before the burst; FRBs are mostly associated with star-forming galaxies. The model requires that some pulsars are born with very fast spins, of the order of few milliseconds. The observed distribution of spin-down powers dot{E} in young energetic pulsars is consistent with equal birth rate per decade of dot{E}. Accepting this injection distribution and scaling the intrinsic brightness of FRBs with dot{E}, we predict the following properties of a large sample of FRBs: (i) the brightest observed events come from a broad distribution in distances; (ii) for repeating bursts brightness either remains nearly constant (if the spin-down time is longer than the age of the pulsar) or decreases with time otherwise; in the latter case DM ∝ dot{E}.

  6. Response of neutron dosimeters to pulsed neutron fields in high energy electron accelerators at Indus Complex, RRCAT

    International Nuclear Information System (INIS)

    Indus Accelerator Complex (IAC) comprises of two high energy electron accelerators namely Indus-1 SRS (450 MeV) and Indus-2 SRS (2.5 GeV). The radiation environment present is mainly due to Bremsstrahlung Photons and Photo- neutrons produced due to interaction of high-energy electrons with the structural material of accelerators. Since electron beam is pulsed in nature, the radiations produced are also pulsed. The response of commonly used Rem meters is not proper in severely pulsed neutron fields at high dose rates. They tend to underestimate the actual dose. Due to this uncertainty, an attempt was made to study the response of passive integrating type detectors in the pulsed neutron fields found in high energy electron accelerators to get an idea about the ambient neutron field in IAC. The detectors used were CR-39 foils (provided by PMS, RPAD and RSSD, BARC), Bubble Detectors (provided by Defence Laboratory, Jodhpur) and Rem Meter. Neutron dose assessment in both, accessible and inaccessible areas of IAC was carried out using these detectors and the present paper gives the results of preliminary experiments performed. (author)

  7. Accelerating Protons to Therapeutic Energies with Ultra-Intense Ultra-Clean and Ultra-Short Laser Pulses

    CERN Document Server

    Bulanov, Stepan S; Bychenkov, Valery Yu; Chvykov, Vladimir; Kalinchenko, Galina; Matsuoka, Takeshi; Rousseau, Pascal; Reed, Stephen; Yanovsky, Victor; Krushelnick, Karl; Litzenberg, Dale William; Maksimchuk, Anatoly

    2008-01-01

    Proton acceleration by high-intensity laser pulses from ultra-thin foils for hadron therapy is discussed. With the improvement of the laser intensity contrast ratio to 10-11 achieved on Hercules laser at the University of Michigan, it became possible to attain laser-solid interactions at intensities up to 1022 W/cm2 that allows an efficient regime of laser-driven ion acceleration from submicron foils. Particle-In-Cell (PIC) computer simulations of proton acceleration in the Directed Coulomb explosion regime from ultra-thin double-layer (heavy ions / light ions) foils of different thicknesses were performed under the anticipated experimental conditions for Hercules laser with pulse energies from 3 to 15 J, pulse duration of 30 fs at full width half maximum (FWHM), focused to a spot size of 0.8 microns (FWHM). In this regime heavy ions expand predominantly in the direction of laser pulse propagation enhancing the longitudinal charge separation electric field that accelerates light ions. The dependence of the ma...

  8. CHARACTERISTICS OF A FAST RISE TIME POWER SUPPLY FOR A PULSED PLASMA REACTOR FOR CHEMICAL VAPOR DESTRUCTION

    Science.gov (United States)

    Rotating spark gap devices for switching high-voltage direct current (dc) into a corona plasma reactor can achieve pulse rise times in the range of tens of nanoseconds. The fast rise times lead to vigorous plasma generation without sparking at instantaneous applied voltages highe...

  9. Design of a beam shaping assembly and preliminary modelling of a treatment room for accelerator-based BNCT at CNEA

    International Nuclear Information System (INIS)

    This work reports on the characterisation of a neutron beam shaping assembly (BSA) prototype and on the preliminary modelling of a treatment room for BNCT within the framework of a research programme for the development and construction of an accelerator-based BNCT irradiation facility in Buenos Aires, Argentina. The BSA prototype constructed has been characterised by means of MCNP simulations as well as a set of experimental measurements performed at the Tandar accelerator at the National Atomic Energy Commission of Argentina. - Highlights: ► Characterisation of a neutron beam shaping assembly for accelerator-based BNCT. ► Measurements: total and epi-cadmium neutron fluxes and beam homogeneity. ► Calculations: Monte Carlo simulations with the MCNP code. ► Measured and calculated figure-of-merit parameters in agreement with those of IAEA. ► Initial MCNP dose calculations for a treatment room to define future design actions.

  10. Reducing the Disk IO Bandwidth Bottleneck through Fast Floating Point Compression using Accelerators

    Directory of Open Access Journals (Sweden)

    Ajith Padyana

    2014-03-01

    Full Text Available Compute-intensive tasks in high-end high performance computing (HPC systems often generate large amounts of data, especially floating-point data that need to be transmitted over the network. Although computation speeds are very high, the overall performance of these applications is affected by the data transfer overhead. Moreover, as data sets are growing in size rapidly, bandwidth limitations pose a serious bottleneck in several scientific applications. Fast floating point compression can ameliorate the bandwidth limitations. If data is compressed well, then the amount of data transfer is reduced. This reduction in data transfer time comes at the expense of the increased computation required by compression and decompression. It is important for compression and decompression rates to be greater than the network bandwidth; otherwise, it will be faster to transmit uncompressed data directly [1]. Accelerators such as Graphics Processing Units (GPU provide much computational power. In this paper, we show that the computational power of GPUs and CellBE processor can be harnessed to provide sufficiently fast compression and decompression for this approach to be effective for data produced by many practical applications. In particularly, we use Holt`s Exponential smoothing algorithm from time series analysis, and encode the difference between its predictions and the actual data. This yields a lossless compression scheme. We show that it can be implemented efficiently on GPUs and CellBE to provide an effective compression scheme for the purpose of saving on data transfer overheads The primary contribution of this work lies in demonstrating the potential of floating point compression in reducing the I/O bandwidth bottleneck on modern hardware for important classes of scientific applications.

  11. GPU-accelerated non-uniform fast Fourier transform-based compressive sensing spectral domain optical coherence tomography.

    Science.gov (United States)

    Xu, Daguang; Huang, Yong; Kang, Jin U

    2014-06-16

    We implemented the graphics processing unit (GPU) accelerated compressive sensing (CS) non-uniform in k-space spectral domain optical coherence tomography (SD OCT). Kaiser-Bessel (KB) function and Gaussian function are used independently as the convolution kernel in the gridding-based non-uniform fast Fourier transform (NUFFT) algorithm with different oversampling ratios and kernel widths. Our implementation is compared with the GPU-accelerated modified non-uniform discrete Fourier transform (MNUDFT) matrix-based CS SD OCT and the GPU-accelerated fast Fourier transform (FFT)-based CS SD OCT. It was found that our implementation has comparable performance to the GPU-accelerated MNUDFT-based CS SD OCT in terms of image quality while providing more than 5 times speed enhancement. When compared to the GPU-accelerated FFT based-CS SD OCT, it shows smaller background noise and less side lobes while eliminating the need for the cumbersome k-space grid filling and the k-linear calibration procedure. Finally, we demonstrated that by using a conventional desktop computer architecture having three GPUs, real-time B-mode imaging can be obtained in excess of 30 fps for the GPU-accelerated NUFFT based CS SD OCT with frame size 2048(axial) × 1,000(lateral).

  12. Properties of the First-order Fermi acceleration in fast magnetic reconnection driven by turbulence in collisional MHD flows

    CERN Document Server

    del Valle, M V; Kowal, G

    2016-01-01

    Fast magnetic reconnection may occur in different astrophysical sources, producing flare-like emission and particle acceleration. Currently, this process is being studied as an efficient mechanism to accelerate particles via a first-order Fermi process. In this work we analyse the acceleration rate and the energy distribution of test particles injected in three-dimensional magnetohydrodynamical (MHD) domains with large-scale current sheets where reconnection is made fast by the presence of turbulence. We study the dependence of the particle acceleration time with the relevant parameters of the embedded turbulence, i.e., the Alfv\\'en speed $V_{\\rm A}$, the injection power $P_{\\rm inj}$ and scale $k_{\\rm inj}$ ($k_{\\rm inj} = 1/l_{\\rm inj}$). We find that the acceleration time follows a power-law dependence with the particle kinetic energy: $t_{acc} \\propto E^{\\alpha}$, with $0.2 < \\alpha < 0.6$ for a vast range of values of $c / V_{\\rm A} \\sim 20 - 1000$. The acceleration time decreases with the Alfv\\'en...

  13. DIFFUSIVE SHOCK ACCELERATION OF HIGH-ENERGY CHARGED PARTICLES AT FAST INTERPLANETARY SHOCKS: A PARAMETER SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Giacalone, Joe [Department of Planetary Sciences, University of Arizona, Tucson, AZ (United States)

    2015-01-20

    We present results from numerical simulations of the acceleration of solar energetic particles (SEPs) associated with strong, fast, and radially propagating interplanetary shocks. We focus on the phase of the SEP event at the time of the shock passage at 1 AU, which is when the peak intensity at energies below a few MeV is the highest. The shocks in our study start between 2 and 10 solar radii and propagate beyond 1 AU. We study the effect of various shock and particle input parameters, such as the spatial diffusion coefficient, shock speed, solar wind speed, initial location of the shock, and shock deceleration rate, on the total integrated differential intensity, I, of SEPs with kinetic energies > 10 MeV. I is the integral over energy of the differential intensity spectrum at the time of the shock passage at 1 AU. We find that relatively small changes in the parameters can lead to significant event-to-event changes in I. For example, a factor of 2 increase in the diffusion coefficient at a given energy and spatial location, can lead to a decrease in I by as much as a factor of 50. This may help explain why there are fewer large SEP events seen during the current solar maximum compared to previous maxima. It is known that the magnitude of the interplanetary magnetic field is noticeably weaker this solar cycle than it was in the previous cycle and this will naturally lead to a somewhat larger diffusion coefficient of SEPs.

  14. Containment Design and Study for the Fast Critical Assembly of JAERI

    International Nuclear Information System (INIS)

    The Fast Critical Assembly of the Japan Atomic Energy Research Institute (FCA) at the Tokai site is used to obtain the reactor physics data as the first step of the fast breeder reactor development schedule in Japan. The containment of FCA must meet the Japanese site criteria for the hypothetical accident, which is assumed as the gross-meltdown and resulting critical power excursion. A nuclear energy of 1020 fissions and a chemical energy of 3 x 107 ca l resulting from the rapid metal-air reaction are estimated to be released at the hypothetical accident. The FCA containment consists of the primary containment to absorb the explosive energy equivalent to a TNT 100-kg explosion, and the secondary containment which withstands the internal static pressure of 1.6 kg/cm2 and is gas-tight, less than 2%/24 h at the design pressure. It is also equipped with the argon ejection system to extinguish the metal fire within the containment area at the accident. The primary containment is a reinforced concrete structure (14 m x 14 m x 13.5 m high and 1.1m thick), of which the strain energy is designed to be more than the impulsive energy caused by a TNT 100-kg explosion. Tests were performed with scaled models to obtain the data on the dynamic pressure and impulse distribution and the response of structures due to the TNT explosion. A reinforced concrete cylinder with a hemispherical cap (24 m diam., 21.4 m high and 40 cm thick, lined with 6-mm-thick steel plate) was selected as the secondary containment, as it was considered to be more advantageous than a steel vessel in economy, shielding, and also anti-missile protection. This paper describes the design philosophy of the FCA containment necessary to meet the given criteria and also the data of the model for anti-blast design. (author)

  15. A FOCUSED TRANSPORT APPROACH TO THE TIME-DEPENDENT SHOCK ACCELERATION OF SOLAR ENERGETIC PARTICLES AT A FAST TRAVELING SHOCK

    International Nuclear Information System (INIS)

    Some of the most sophisticated models for solar energetic particle (SEP) acceleration at coronal mass ejection driven shocks are based on standard diffusive shock acceleration theory. However, this theory, which only applies when SEP pitch-angle anisotropies are small, might have difficulty in describing first-order Fermi acceleration or the shock pre-heating and injection of SEPs into first-order Fermi acceleration accurately at lower SEP speeds where SEP pitch-angle anisotropies upstream near the shock can be large. To avoid this problem, we use a time-dependent focused transport model to reinvestigate first-order Fermi acceleration at planar parallel and quasi-parallel spherical traveling shocks between the Sun and Earth with high shock speeds associated with rare extreme gradual SEP events. The focused transport model is also used to investigate and compare three different shock pre-heating mechanisms associated with different aspects of the nonuniform cross-shock solar wind flow, namely, the convergence of the flow (adiabatic compression), the shear tensor of the flow, and the acceleration of the flow, and a fourth shock pre-heating mechanism associated with the cross-shock electric field, to determine which pre-heating mechanism contributes the most to injecting shock pre-heated source particles into the first-order Fermi acceleration process. The effects of variations in traveling shock conditions, such as increasing shock obliquity and shock slowdown, and variations in the SEP source with increasing shock distance from the Sun on the coupled processes of shock pre-heating, injection, and first-order Fermi acceleration are analyzed. Besides the finding that the cross-shock acceleration of the solar wind flow yields the dominant shock pre-heating mechanism at high shock speeds, we find that first-order Fermi acceleration at fast traveling shocks differs in a number of respects from the predictions and assumptions of standard steady-state diffusive shock

  16. A FOCUSED TRANSPORT APPROACH TO THE TIME-DEPENDENT SHOCK ACCELERATION OF SOLAR ENERGETIC PARTICLES AT A FAST TRAVELING SHOCK

    Energy Technology Data Exchange (ETDEWEB)

    Le Roux, J. A.; Webb, G. M. [Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2012-02-10

    Some of the most sophisticated models for solar energetic particle (SEP) acceleration at coronal mass ejection driven shocks are based on standard diffusive shock acceleration theory. However, this theory, which only applies when SEP pitch-angle anisotropies are small, might have difficulty in describing first-order Fermi acceleration or the shock pre-heating and injection of SEPs into first-order Fermi acceleration accurately at lower SEP speeds where SEP pitch-angle anisotropies upstream near the shock can be large. To avoid this problem, we use a time-dependent focused transport model to reinvestigate first-order Fermi acceleration at planar parallel and quasi-parallel spherical traveling shocks between the Sun and Earth with high shock speeds associated with rare extreme gradual SEP events. The focused transport model is also used to investigate and compare three different shock pre-heating mechanisms associated with different aspects of the nonuniform cross-shock solar wind flow, namely, the convergence of the flow (adiabatic compression), the shear tensor of the flow, and the acceleration of the flow, and a fourth shock pre-heating mechanism associated with the cross-shock electric field, to determine which pre-heating mechanism contributes the most to injecting shock pre-heated source particles into the first-order Fermi acceleration process. The effects of variations in traveling shock conditions, such as increasing shock obliquity and shock slowdown, and variations in the SEP source with increasing shock distance from the Sun on the coupled processes of shock pre-heating, injection, and first-order Fermi acceleration are analyzed. Besides the finding that the cross-shock acceleration of the solar wind flow yields the dominant shock pre-heating mechanism at high shock speeds, we find that first-order Fermi acceleration at fast traveling shocks differs in a number of respects from the predictions and assumptions of standard steady-state diffusive shock

  17. Acceleration of multiply charged ions by a high-contrast femtosecond laser pulse of relativistic intensity with the front surface of a solid target

    Science.gov (United States)

    Shulyapov, S. A.; Mordvintsev, I. M.; Ivanov, K. A.; Volkov, R. V.; Zarubin, P. I.; Ambrožová, I.; Turek, K.; Savel'ev, A. B.

    2016-05-01

    It is shown that the acceleration efficiency of protons and multiply charged ions (and also the charge composition of the latter) accelerated backwards under irradiation of the front surface of thick solid targets by high-power femtosecond laser radiation with an intensity of 2 × 1018 W cm-2 is determined by the contrast of this radiation. Thus, highly ionised ions up to C6+, Si12+ and Mo14+ are recorded on polyethylene, silicon and molybdenum targets at a contrast of 10-8, the ions with charges up to C5+, Si10+ and Mo10+ possessing an energy of more than 100 keV per unit charge. In the case of a metal target, the acceleration efficiency of protons is significantly reduced, which indicates cleaning of the target surface by a pre-pulse. The measurements performed at a contrast increased by two-to-three orders of magnitude show the presence of fast protons (up to 300–700 keV) on all targets, and also a decrease in the energy and maximum charge of multiply charged ions.

  18. RF impedance measurements on the DARHT-II accelerator intercell assembly

    Energy Technology Data Exchange (ETDEWEB)

    Fawley, William M.; Eylon, Shmuel; Briggs, Richard

    2003-05-05

    We report upon recent experimental measurements made of RF properties of the intercell assembly of the second axis accelerator[1] of Dual Axis Radiographic Hydrodynamic Test (DARHT) facility at LANL. The intercells provide both pumping and diagnostic access to the main DARHT-II beamline. Their design includes a pumping plenum separated from the main beam pipe by return current rods together with RF shielding provided by a copper-coated stainless steel mesh. Measurements using the twin lead technique (see Ref. [2]) at low frequencies (f < 200 MHz) suggest a constant value for the ratio h of the radial and azimuthal magnetic field components to which the transverse impedance is linearly related. We find that these results compare favorably to predictions from a simple analytic, lumped circuit model which includes the effects of the mesh and return current rods. We also present RF loop-to-loop frequency scans above beam pipe cutoff ({approx}600 MHz) showing the existence of many RF modes with relatively high Q's.

  19. Experimental Study of a Pulsed Ytterbium-Doped Fibre Laser with Fast and Slow Saturable Absorbers in a Linear Cavity

    Institute of Scientific and Technical Information of China (English)

    GAN Yu; XIANG Wang-Hua; ZHOU Xiao-Fang; ZHANG Gui-Zhong; ZHANG Bing; WANG Yong-Gang; MA Xiao-Yu

    2006-01-01

    @@ We present a linear-cavity stretched-pulse fibre laser with mode locking by a nonlinear polarization rotation and by semiconductor saturable-absorber mirrors. A Q-switched mode-locking cw train and a mode-locking pulse train are obtained in the experiment. We investigate the effects of the equivalent fast saturable absorber and the slow saturable absorbers in experiment. It is found that neither the nonlinear polarization evolution effect nor a semiconductor saturable absorber mirror is enough to produce the stable cw mode-locking pulses in this experiment. A nonlinear polarization evolution effect controls the cavity loss to literally carve the pulses;semiconductor saturable absorber mirrors provide the self-restarting and maintain the stability of the modelocking operation.

  20. Experimental investigations of heat transfer during sodium boiling in fuel assembly model in justification of advanced fast reactor safety

    International Nuclear Information System (INIS)

    The experimental facility is built up and investigation of heat exchange during sodium boiling in simulated fast reactor core assembly in conditions of natural and forced circulation with sodium plenum and upper end shield model are conducted. It is shown that in the presence of sodium plenum there is possibility to provide long-term cooling of fuel assembly when heat flux density on the surface of fuel element simulator up to 140 and 170 kW/m2 in conditions of natural and forced circulation, respectively. The obtained data is used for improving calculational model of sodium boiling process in fuel assembly and calculational code COREMELT verification. It is pointed out that heat transfer coefficients in the case of liquid metal boiling in fuel assemblies are slightly over the ones in the case of liquid metals boiling in pipes and pool boiling

  1. Effect of an Additional, Parallel Capacitor on Pulsed Inductive Plasma Accelerator Performance

    Science.gov (United States)

    Polzin, Kurt A.; Sivak, Amy D.; Balla, Joseph V.

    2011-01-01

    A model of pulsed inductive plasma thrusters consisting of a set of coupled circuit equations and a one-dimensional momentum equation has been used to study the effects of adding a second, parallel capacitor into the system. The equations were nondimensionalized, permitting the recovery of several already-known scaling parameters and leading to the identification of a parameter that is unique to the particular topology studied. The current rise rate through the inductive acceleration coil was used as a proxy measurement of the effectiveness of inductive propellant ionization since higher rise rates produce stronger, potentially better ionizing electric fields at the coil face. Contour plots representing thruster performance (exhaust velocity and efficiency) and current rise rate in the coil were generated numerically as a function of the scaling parameters. The analysis reveals that when the value of the second capacitor is much less than the first capacitor, the performance of the two-capacitor system approaches that of the single-capacitor system. In addition, as the second capacitor is decreased in value the current rise rate can grow to be twice as great as the rise rate attained in the single capacitor case.

  2. Device for locating burst claddings in the fuel assemblies of a fast nuclear reactor

    International Nuclear Information System (INIS)

    The device includes at least one localization module comprising a sampling selector, a pump and a neutron detector. The selector has a cylindrical casing provided with holes to which are connected sampling tubes each one linked to a core assembly and a sampling pipe which moves in rubbing contact with the internal surface of the casing. The pipe is composed of a tube fitted with a sampling head at its lower end, mounted inside and along the vertical axis of a tubular drive component. This component is held through its threaded external surface with a nut. This component can be driven rotationally by a gear wheel and by a drive located offset in relation to the axis of the selector and module. The sampling pipe is integral with the component but can be slightly pivoted about a horizontal axis inside the component. A counter weight mounted on the component applies the sampling head to the surface of the casing with a constant pressure. The invention applies in particular to liquid sodium cooled fast nuclear reactors

  3. Experimental Studies on Assemblies 1 and 2 of the Fast Reactor FR-0. Part 1

    International Nuclear Information System (INIS)

    FR0 is a fast zero power reactor built for experiments in reactor physics. It is a split table machine containing vertical fuel elements. 120 kg of U235 are available as fuel, which is fabricated into metallic plates of 20 % enrichment. The control system comprises 5 spring-loaded safety elements and 3 + 1 elements for startup operations and power control. The reactor went critical in February 1964. The first assemblies studied were made up of undiluted fuel into a cylindrical and a spherical core, respectively, surrounded by a reflector made of copper. The present report describes some experiments made on these systems. Primarily, critical mass determinations, flux distribution measurements and studies of the conversion ratio are dealt with. The measured quantities have been compared with theoretical predictions using various transport theory programmes (DSN, TDC) and cross section sets. The experimental results show that the neutron spectrum in the copper reflector is softer than predicted, but apart from this discrepancy agreement with theory has generally been obtained

  4. Development of a dual-pulse RF driver for an S-band (= 2856 MHz) RF electron linear accelerator

    Science.gov (United States)

    Cha, Sungsu; Kim, Yujong; Lee, Byeong-No; Lee, Byung Cheol; Cha, Hyungki; Ha, Jang Ho; Park, Hyung Dal; Lee, Seung Hyun; Kim, Hui Su; Buaphad, Pikad

    2016-04-01

    The radiation equipment research division of Korea Atomic Energy Research Institute has developed a Container Inspection System (CIS) using a Radio Frequency (RF) electron linear accelerator for port security. The primary purpose of the CIS is to detect nuclear materials and explosives, as well country-specific prohibited substances, e.g., smuggled. The CIS consists of a 9/6 MeV dualenergy electron linear accelerator for distinguishing between organic and inorganic materials. The accelerator consists of an electron gun, an RF accelerating structure, an RF driver, a modulator, electromagnets, a cooling system, a X-ray generating target, X-ray collimator, a detector, and a container moving system. The RF driver is an important part of the configuration because it is the RF power source: it supplies the RF power to the accelerating structure. A unique aspect of the RF driver is that it generates dual RF power to generate dual energy (9/6 MeV). The advantage of this RF driver is that it can allow the pulse width to vary and can be used to obtain a wide range of energy output, and pulse repetition rates up to 300 Hz. For this reason, 140 W (5 MW - 9 MeV) and 37 W (3.4 MW - 6 MeV) power outputs are available independently. A high power test for 20 minutes demonstrate that stable dual output powers can be generated. Moreover, the dual power can be applied to the accelerator which has stable accelerator operation. In this paper, the design, fabrication and high power test of the RF driver for the RF electron linear accelerator (linac) are presented.

  5. Irradiation Effects for the Pulsed Fast Neutron Analysis (PFNA) Cargo Interrogation System

    Energy Technology Data Exchange (ETDEWEB)

    Slater, C.O.

    2001-02-02

    At the request of Safety and Ecology Corporation of Tennessee, radiation effects of the proposed Pulsed Fast Neutron Analysis (PFNA) Cargo Interrogation System have been examined. First, fissile cargo were examined to determine if a significant neutron signal would be observable during interrogation. Results indicated that ample multiplication would be seen for near critical bare targets. The water-reflected sphere showed relatively little multiplication. By implication, a fissile target shielded by hydrogenous cargo might not be detectable by neutron interrogation, particularly if reliance is placed on the neutron signal. The cargo may be detectable if use can be made of the ample increase in the photon signal. Second, dose rates were calculated at various locations within and just outside the facility building. These results showed that some dose rates may be higher than the target dose rate of 0.05 mrem/h. However, with limited exposure time, the total dose may be well below the allowed total dose. Lastly, estimates were made of the activation of structures and typical cargo. Most cargo will not be exposed long enough to be activated to levels of concern. On the other hand, portions of the structure may experience buildup of some radionuclides to levels of concern.

  6. Ultra-fast pulse propagation in nonlinear graphene/silicon ridge waveguide.

    Science.gov (United States)

    Liu, Ken; Zhang, Jian Fa; Xu, Wei; Zhu, Zhi Hong; Guo, Chu Cai; Li, Xiu Jian; Qin, Shi Qiao

    2015-11-18

    We report the femtosecond laser propagation in a hybrid graphene/silicon ridge waveguide with demonstration of the ultra-large Kerr coefficient of graphene. We also fabricated a slot-like graphene/silicon ridge waveguide which can enhance its effective Kerr coefficient 1.5 times compared with the graphene/silicon ridge waveguide. Both transverse-electric-like (TE-like) mode and transverse-magnetic-like (TM-like) mode are experimentally measured and numerically analyzed. The results show nonlinearity dependence on mode polarization not in graphene/silicon ridge waveguide but in slot-like graphene/silicon ridge waveguide. Great spectral broadening was observed due to self-phase modulation (SPM) after propagation in the hybrid waveguide with length of 2 mm. Power dependence property of the slot-like hybrid waveguide is also measured and numerically analyzed. The results also confirm the effective Kerr coefficient estimation of the hybrid structures. Spectral blue shift of the output pulse was observed in the slot-like graphene/silicon ridge waveguide. One possible explanation is that the blue shift was caused by the ultra-fast free carrier effect with the optical absorption of the doped graphene. This interesting effect can be used for soliton compression in femtosecond region. We also discussed the broadband anomalous dispersion of the Kerr coefficient of graphene.

  7. Research and development of ns pulse width ultrafast pulsed power supply

    International Nuclear Information System (INIS)

    High repetition rate, nanosecond pulse width fast pulsed power supply is a key technology to be overcome for particle accelerator fast kicker injection and ejection. In this paper, inductive adder topology, the RF MOSFET and its driver circuit were studied by computer simulation and table circuit experiment. On the basis of theory research, a ten-grade inductive adder pulsed power supply evaluating prototype was developed. The preliminary test of the prototype was completed. A ten-grade adder can produce a short pulse of pulse amplitude >4.3 kV, front edge <2.8 ns, and pulse width <9 ns into 50 Ω at 500 Hz repetition rate. (authors)

  8. Still Heart Encodes a Structural HMT, SMYD1b, with Chaperone-Like Function during Fast Muscle Sarcomere Assembly.

    Directory of Open Access Journals (Sweden)

    Kendal Prill

    Full Text Available The vertebrate sarcomere is a complex and highly organized contractile structure whose assembly and function requires the coordination of hundreds of proteins. Proteins require proper folding and incorporation into the sarcomere by assembly factors, and they must also be maintained and replaced due to the constant physical stress of muscle contraction. Zebrafish mutants affecting muscle assembly and maintenance have proven to be an ideal tool for identification and analysis of factors necessary for these processes. The still heart mutant was identified due to motility defects and a nonfunctional heart. The cognate gene for the mutant was shown to be smyd1b and the still heart mutation results in an early nonsense codon. SMYD1 mutants show a lack of heart looping and chamber definition due to a lack of expression of heart morphogenesis factors gata4, gata5 and hand2. On a cellular level, fast muscle fibers in homozygous mutants do not form mature sarcomeres due to the lack of fast muscle myosin incorporation by SMYD1b when sarcomeres are first being assembled (19hpf, supporting SMYD1b as an assembly protein during sarcomere formation.

  9. Fast electron generation and transport in solid matter irradiated at relativistic intensities. Evidence of vxB acceleration

    Science.gov (United States)

    Baton, S. D.; Santos, J. J.; Amiranoff, F.; Popescu, H.; Gremillet, L.; Koenig, M.; Martinolli, E.; Rousseaux, C.; Rabec-Le-Gloahec, M.; Hall, T. A.; Batani, D.; Perelli, E.; Scianitti, F.; Cowan, T. E.

    2002-11-01

    In the context of the fast electron transport in solid matter and the fast ignitor scheme,we report on measurements of second harmonic of the laser light observed on the rear side of solid targets irradiated by the 100 TW laser at LULI. This emission can be explained by the acceleration of short bunches of electrons in the front of the target by the vxB force. The observations indicate that, in our conditions, the minimum fraction of the laser energy transferred to these electron bunches is of the order of 1 °.

  10. Note: Compact high voltage pulse transformer made using a capacitor bank assembled in the shape of primary.

    Science.gov (United States)

    Shukla, Rohit; Banerjee, Partha; Sharma, Surender K; Das, Rashmita; Deb, Pankaj; Prabaharan, T; Das, Basanta; Adhikary, Biswajit; Verma, Rishi; Shyam, Anurag

    2011-10-01

    The experimental results of an air-core pulse transformer are presented, which is very compact (transformer. A high voltage capacitor assembly (pulse-forming-line capacitor, PFL) of 5.1 nF is connected with the secondary of transformer. The transformer output voltage is 160 kV in its second peak appearing in less than 2 μS from the beginning of the capacitor discharge. The primary capacitor bank can be charged up to a maximum of 18 kV, with the voltage delivery of 360 kV in similar capacitive loads.

  11. Preliminary consideration of a double, 480 GeV, fast cycling proton accelerator for production of neutrino beams at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Piekarz, Henryk; Hays, Steven; /Fermilab

    2007-03-01

    We propose to build the DSF-MR (Double Super-Ferric Main Ring), 480 GeV, fast-cycling (2 second repetition rate) two-beam proton accelerator in the Main Ring tunnel of Fermilab. This accelerator design is based on the super-ferric magnet technology developed for the VLHC, and extended recently to the proposed LER injector for the LHC and fast cycling SF-SPS at CERN. The DSF-MR accelerator system will constitute the final stage of the proton source enabling production of two neutrino beams separated by 2 second time period. These beams will be sent alternately to two detectors located at {approx} 3000 km and {approx} 7500 km away from Fermilab. It is expected that combination of the results from these experiments will offer more than 3 order of magnitudes increased sensitivity for detection and measurement of neutrino oscillations with respect to expectations in any current experiment, and thus may truly enable opening the window into the physics beyond the Standard Model. We examine potential sites for the long baseline neutrino detectors accepting beams from Fermilab. The current injection system consisting of 400 MeV Linac, 8 GeV Booster and the Main Injector can be used to accelerate protons to 45 GeV before transferring them to the DSF-MR. The implementation of the DSF-MR will allow for an 8-fold increase in beam power on the neutrino production target. In this note we outline the proposed new arrangement of the Fermilab accelerator complex. We also briefly describe the DSF-MR magnet design and its power supply, and discuss necessary upgrade of the Tevatron RF system for the use with the DSF-MR accelerator. Finally, we outline the required R&D, cost estimate and possible timeline for the implementation of the DSF-MR accelerator.

  12. A fast wire scanner, used to measure the transverse density distribution of beams circulating in an accelerator or storage ring.

    CERN Multimedia

    Maximilien Brice

    2002-01-01

    Fast wire scanners are used to measure the transverse density distribution of beams circulating in an accelerator or storage ring. In order to minimize blow-up of the beam through multiple Coulomb scattering, the wires are very thin (in the version shown here it is actually a twisted strand of carbon fibres with a total diameter of about 25 microns) and are swept through the beam at high speed (a linear motor, not mounted here, accelerates the wires to up to 20 m/s). One measures either the secondary emission current from the wire, or the signal from a scintillator/photomultiplier combination downstream from the wire scanner receiving the shower from nuclear reactions of beam particles with the wire nuclei. There are four such fast wire scanners in the 26 GeV PS and eight in the 1.4 GeV Booster.

  13. Fast Multipole Acceleration of a MoM Code for the Solution of Composed Metallic/Dielectric Scattering Problems

    OpenAIRE

    Jakobus, U.; J. Van Tonder

    2005-01-01

    An existing method of moments (MoM) code for the solution of complex scattering bodies has been accelerated by means of a multilevel fast multipole method (MLFMM). We demonstrate the usage of this technique both for metallic structures (wires and surfaces) and for dielectric bodies (volume and surface equivalence principle). Aspects like the effect of the type of integral equation, preconditioning schemes, or iterative solution techniques are discussed. But also limitations are addressed, whi...

  14. Implementing and diagnosing magnetic flux compression on the Z pulsed power accelerator

    Energy Technology Data Exchange (ETDEWEB)

    McBride, Ryan D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bliss, David E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gomez, Matthew R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hansen, Stephanie B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Matthew R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jennings, Christopher Ashley [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Slutz, Stephen A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rovang, Dean C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knapp, Patrick F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schmit, Paul F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Awe, Thomas James [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hess, M. H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lemke, Raymond W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dolan, D. H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lamppa, Derek C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jobe, Marc Ronald Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fang, Lu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hahn, Kelly D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Chandler, Gordon A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cooper, Gary Wayne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ruiz, Carlos L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Maurer, A. J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Robertson, Grafton Kincannon [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cuneo, Michael E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sinars, Daniel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tomlinson, Kurt [General Atomics, San Diego, CA (United States); Smith, Gary [General Atomics, San Diego, CA (United States); Paguio, Reny [General Atomics, San Diego, CA (United States); Intrator, Tom [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Weber, Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Greenly, John [Cornell Univ., Ithaca, NY (United States)

    2015-11-01

    We report on the progress made to date for a Laboratory Directed Research and Development (LDRD) project aimed at diagnosing magnetic flux compression on the Z pulsed-power accelerator (0-20 MA in 100 ns). Each experiment consisted of an initially solid Be or Al liner (cylindrical tube), which was imploded using the Z accelerator's drive current (0-20 MA in 100 ns). The imploding liner compresses a 10-T axial seed field, B z ( 0 ) , supplied by an independently driven Helmholtz coil pair. Assuming perfect flux conservation, the axial field amplification should be well described by B z ( t ) = B z ( 0 ) x [ R ( 0 ) / R ( t )] 2 , where R is the liner's inner surface radius. With perfect flux conservation, B z ( t ) and dB z / dt values exceeding 10 4 T and 10 12 T/s, respectively, are expected. These large values, the diminishing liner volume, and the harsh environment on Z, make it particularly challenging to measure these fields. We report on our latest efforts to do so using three primary techniques: (1) micro B-dot probes to measure the fringe fields associated with flux compression, (2) streaked visible Zeeman absorption spectroscopy, and (3) fiber-based Faraday rotation. We also mention two new techniques that make use of the neutron diagnostics suite on Z. These techniques were not developed under this LDRD, but they could influence how we prioritize our efforts to diagnose magnetic flux compression on Z in the future. The first technique is based on the yield ratio of secondary DT to primary DD reactions. The second technique makes use of the secondary DT neutron time-of-flight energy spectra. Both of these techniques have been used successfully to infer the degree of magnetization at stagnation in fully integrated Magnetized Liner Inertial Fusion (MagLIF) experiments on Z [P. F. Schmit et al. , Phys. Rev. Lett. 113 , 155004 (2014); P. F. Knapp et al. , Phys. Plasmas, 22 , 056312 (2015)]. Finally, we present some recent developments for designing

  15. Pondermotive acceleration of electrons to GeV energies by a tightly focused ultra-short ultra-intense laser pulse

    Science.gov (United States)

    Tian, Youwei; Yu, Wei; Lu, Peixiang; He, Feng; Xu, Han

    2005-12-01

    Laser-driven pondermotive acceleration of electrons in vacuum has been considered using computer simulations. It is demonstrated that a low-energy free electron can be violently accelerated to final kinetic energy of GeV by a tightly focused ultra-short ultra-intense laser pulse. Suitable conditions that are crucial for this phenomenon to occur have been investigated. It is shown that selection of appropriate initial conditions like relative time delay between electron and the laser pulse, electron's incident angle and momentum, laser pulse duration and its focal spot size play important roles in the efficient acceleration scheme.

  16. Pulse shape discrimination between (fast or thermal) neutrons and gamma rays with plastic scintillators: State of the art

    International Nuclear Information System (INIS)

    We would like to present here with the eyes of the chemist the most recent developments of plastic scintillators (PS) for neutron detection. This review covers the period from 2000 to August 2014, and is fragmented in two main chapters. The first chapter deals with the chemical modifications for thermal neutron capture, whereas the second chapter presents the various strategies used to enhance the response to fast neutrons via pulse shape discrimination. For each chapter the theory is also explained

  17. Pulse shape discrimination between (fast or thermal) neutrons and gamma rays with plastic scintillators: State of the art

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, Guillaume H.V. [CEA, LIST, Laboratoire Capteurs & Architectures Électroniques, CEA Saclay, F-91191 Gif-sur-Yvette cedex (France); Hamel, Matthieu, E-mail: matthieu.hamel@cea.fr [CEA, LIST, Laboratoire Capteurs & Architectures Électroniques, CEA Saclay, F-91191 Gif-sur-Yvette cedex (France); Normand, Stéphane [CEA, DAM, Le Ponant, 25 rue Leblanc, F-75015 Paris (France); Sguerra, Fabien [CEA, LIST, Laboratoire Capteurs & Architectures Électroniques, CEA Saclay, F-91191 Gif-sur-Yvette cedex (France)

    2015-03-11

    We would like to present here with the eyes of the chemist the most recent developments of plastic scintillators (PS) for neutron detection. This review covers the period from 2000 to August 2014, and is fragmented in two main chapters. The first chapter deals with the chemical modifications for thermal neutron capture, whereas the second chapter presents the various strategies used to enhance the response to fast neutrons via pulse shape discrimination. For each chapter the theory is also explained.

  18. The pulsed beam facility at the 3 MV Van de Graaff accelerator in Florence: Overview and examples of applications

    Science.gov (United States)

    Taccetti, N.; Giuntini, L.; Casini, G.; Stefanini, A. A.; Chiari, M.; Fedi, M. E.; Mandò, P. A.

    2002-04-01

    An electrostatic chopper has been installed at the KN 3000 accelerator in Florence to obtain short beam pulses with a number of particles per pulse whose average value can be chosen by varying the current intensity at the deflector plates input. Beam pulses can be obtained containing an average number of particles per pulse from less than one to thousands. The transmitted beam pulses can be as short as 200 ps FWHM, at a repetition rate up to about 100 kHz. Among the many applications of the facility, the direct measurement of energy loss and straggling of protons in Kapton and aluminium is reported. In this measurement, the facility has been tuned for transmission of mainly single-proton pulses; the beam energy is directly measured downstream with a good energy-resolution detector, without and with absorbers in front. In general, measurements of this kind can be directed both to study the basic processes of charged particles interactions in materials, or more practically to obtain the effective values of energy parameters useful in many IBA applications, avoiding the need to rely on simulations or theoretical estimates. Also briefly described is an application to Si-detector testing. In this case, the facility has been tuned for transmission of pulses containing many hundreds of protons of energy Ep=2.5 MeV and the detector is directly exposed to the pulses. Spectra containing equally spaced peaks at energies multiple of Ep are obtained and the response linearity of the detector plus electronics system can thus be checked.

  19. The pulsed beam facility at the 3 MV Van de Graaff accelerator in Florence: Overview and examples of applications

    Energy Technology Data Exchange (ETDEWEB)

    Taccetti, N.; Giuntini, L. E-mail: giuntini@fi.infn.it; Casini, G.; Stefanini, A.A.; Chiari, M.; Fedi, M.E.; Mando, P.A

    2002-04-01

    An electrostatic chopper has been installed at the KN 3000 accelerator in Florence to obtain short beam pulses with a number of particles per pulse whose average value can be chosen by varying the current intensity at the deflector plates input. Beam pulses can be obtained containing an average number of particles per pulse from less than one to thousands. The transmitted beam pulses can be as short as 200 ps FWHM, at a repetition rate up to about 100 kHz. Among the many applications of the facility, the direct measurement of energy loss and straggling of protons in Kapton and aluminium is reported. In this measurement, the facility has been tuned for transmission of mainly single-proton pulses; the beam energy is directly measured downstream with a good energy-resolution detector, without and with absorbers in front. In general, measurements of this kind can be directed both to study the basic processes of charged particles interactions in materials, or more practically to obtain the effective values of energy parameters useful in many IBA applications, avoiding the need to rely on simulations or theoretical estimates. Also briefly described is an application to Si-detector testing. In this case, the facility has been tuned for transmission of pulses containing many hundreds of protons of energy E{sub p}=2.5 MeV and the detector is directly exposed to the pulses. Spectra containing equally spaced peaks at energies multiple of E{sub p} are obtained and the response linearity of the detector plus electronics system can thus be checked.

  20. Technical meeting to 'Review of national programmes on fast reactors and accelerator driven systems (ADS)'. Working material

    International Nuclear Information System (INIS)

    The 35th Annual Meeting of the Technical Working Group on Fast Reactors TWG-FR, previously International Working Group on Fast Reactors (IWG-FR, created in 1967), was hosted by the Forschungszentrum Karlsruhe (FZK) and was attended by TWG-FR members and advisers from the following Member States: Brazil, China, France, Germany, India, Japan, the Republic of Kazakhstan, the Republic of Korea, the Russian Federation, and the United States of America. The objectives of the meeting were: to exchange information on the national programmes on Fast Reactors (FR) and Accelerator Driven Systems (ADS); to review the progress since the 34th TWG-FR Annual Meeting, including the status of the actions; to consider meeting arrangements for 2002 and 2003; to review the Agency's co-ordinated research activities in the field of FRs and ADS, as well as co-ordination of the TWG-FR's activities with other organizations

  1. Experimental and Simulated Characterization of a Beam Shaping Assembly for Accelerator- Based Boron Neutron Capture Therapy (AB-BNCT)

    International Nuclear Information System (INIS)

    In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator-Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte-Carlo simulations and measurements. The neutrons were generated via the 7Li(p, n)7Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.

  2. In-field Calibration of a Fast Neutron Collar for the Measurement of Fresh PWR Fuel Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Swinhoe, Martyn Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); De Baere, Paul [European Commission (Luxembourg). Euratom Safeguards

    2015-04-17

    A new neutron collar has been designed for the measurement of fresh LEU fuel assemblies. This collar uses “fast mode” measurement to reduce the effect of burnable poison rods on the assay and thus reduce the dependence on the operator’s declaration. The new collar design reduces effect of poison rods considerably. Instead of 12 pins of 5.2% Gd causing a 20.4% effect, as in the standard thermal mode collar, they only cause a 3.2% effect in the new collar. However it has higher efficiency so that reasonably precise measurements can be made in 25 minutes, rather than the 1 hour of previous collars. The new collar is fully compatible with the use of the standard data collection and analysis code INCC. This report describes the calibration that was made with a mock-up assembly at Los Alamos National Laboratory and with actual assemblies at the AREVA Fuel fabrication Plant in Lingen, Germany.

  3. Design and fabrication of hollow-core photonic crystal fibers for high power fast laser beam transportation and pulse compression

    Science.gov (United States)

    Wang, Y. Y.; Peng, Xiang; Alharbi, M.; Dutin, C. F.; Bradley, T. D.; Mielke, Michael; Booth, Timothy; Benabid, F.

    2012-03-01

    We report on recent design and fabrication of Kagome type hollow-core photonic crystal fiber (HC-PCF) for the purpose of high power fast laser beam transportation. The fabricated seven-cell three-ring hypocycloid-shaped large core fiber exhibits an up-to-date lowest attenuation (among all Kagome fibers) of 40dB/km over a broadband transmission centered at 1500nm. We show that the large core size, low attenuation, broadband transmission, single modedness, low dispersion and relatively low banding loss makes it an ideal host for high power laser beam transportation. By filling the fiber with helium gas, a 74μJ, 850fs and 40kHz repetition rate ultra-short pulse at 1550nm has been faithfully delivered with little propagation pulse distortion. Compression of a 105μJ laser pulse from 850fs to 300fs has been achieved by operating the fiber in ambient air.

  4. Accelerator

    International Nuclear Information System (INIS)

    The invention claims equipment for stabilizing the position of the front covers of the accelerator chamber in cyclic accelerators which significantly increases accelerator reliability. For stabilizing, it uses hydraulic cushions placed between the electromagnet pole pieces and the front chamber covers. The top and the bottom cushions are hydraulically connected. The cushions are disconnected and removed from the hydraulic line using valves. (J.P.)

  5. Enhanced collimated GeV monoenergetic ion acceleration from a shaped foil target irradiated by a circularly polarized laser pulse

    CERN Document Server

    Chen, M; Yu, T P; Sheng, Z M

    2009-01-01

    Using multi-dimensional particle-in-cell (PIC) simulations we study ion acceleration from a foil irradiated by a circularly polarized laser pulse at 1022W/cm^2 intensity. When the foil is shaped initially in the transverse direction to match the laser intensity profile, the center part of the target can be uniformly accelerated for a longer time compared to a usual flat target. Target deformation and undesirable plasma heating are effectively suppressed. The final energy spectrum of the accelerated ion beam is improved dramatically. Collimated GeV quasi-mono-energetic ion beams carrying as much as 18% of the laser energy are observed in multi-dimensional simulations. Radiation damping effects are also checked in the simulations.

  6. Clocked, fast electronics trigger for high energy physics

    Energy Technology Data Exchange (ETDEWEB)

    Gray, R.; Rutherfoord, J.P.

    1986-04-01

    For a Fermilab experiment we have designed and built gated-pulse-stretcher modules which allow us to clock all of the fast electronics with the accelerator rf, thus simplifying the trigger design. (orig.).

  7. A US perspective on fast reactor fuel fabrication technology and experience part I: metal fuels and assembly design

    International Nuclear Information System (INIS)

    This paper is part I of a review focusing on the United States experience with metallic fast reactor fuel fabrication and assembly design for the Experimental Breeder Reactor-II (EBR-II) and the Fast Flux Test Facility (FFTF). Experience with metal fuel fabrication in the United States is extensive, including over 60 years of research conducted by the government, national laboratories, industry, and academia. This experience has culminated in a considerable amount of research that resulted in significant improvements to the technologies employed to fabricate metallic fast reactor fuel. This part of the review documents the current state of fuel fabrication technologies for metallic fuels, some of the challenges faced by previous researchers, and how these were overcome. Knowledge gained from reviewing previous investigations will aid both researchers and policy makers in forming future decisions relating to nuclear fuel fabrication technologies.

  8. Slow and fast light via SBS in optical fibers for short pulses and broadband pump

    Science.gov (United States)

    Kalosha, V. P.; Chen, Liang; Bao, Xiaoyi

    2006-12-01

    Slow-light effect via stimulated Brillouin scattering (SBS) in single-mode optical fibers was considered for short probe pulses of nanosecond duration relevant to Gb/s data streams. Unlike recent estimations of delay versus pump based on steady-state small-signal approximation we have used numerical solution of three-wave equations describing SBS for a realistic fiber length. Both regimes of small signal and pump depletion (gain saturation) were considered. The physical origin of Stokes pulse distortion is revealed which is related to excitation of long-living acoustic field behind the pulse and prevents effective delay control by pump power increase at cw pumping. We have shown different slope of the gain-dependent delay for different pulse durations. Spectrally broadened pumping by multiple cw components, frequency-modulated pump and pulse train were studied for short pulses which allow to obtain large delay and suppress pulse distortion. In the pump-depletion regime of pumping by pulse train, both pulse delay and distortion decrease with increasing pump, and the pulse achieves advancement.

  9. Slow and fast light via SBS in optical fibers for short pulses and broadband pump.

    Science.gov (United States)

    Kalosha, V P; Chen, Liang; Bao, Xiaoyi

    2006-12-25

    Slow-light effect via stimulated Brillouin scattering (SBS) in single-mode optical fibers was considered for short probe pulses of nanosecond duration relevant to Gb/s data streams. Unlike recent estimations of delay versus pump based on steady-state small-signal approximation we have used numerical solution of three-wave equations describing SBS for a realistic fiber length. Both regimes of small signal and pump depletion (gain saturation) were considered. The physical origin of Stokes pulse distortion is revealed which is related to excitation of long-living acoustic field behind the pulse and prevents effective delay control by pump power increase at cw pumping. We have shown different slope of the gain-dependent delay for different pulse durations. Spectrally broadened pumping by multiple cw components, frequency-modulated pump and pulse train were studied for short pulses which allow to obtain large delay and suppress pulse distortion. In the pump-depletion regime of pumping by pulse train, both pulse delay and distortion decrease with increasing pump, and the pulse achieves advancement. PMID:19532161

  10. Accelerating the Non-equispaced Fast Fourier Transform on Commodity Graphics Hardware

    DEFF Research Database (Denmark)

    Sørensen, Thomas Sangild; Schaeffter, Tobias; Noe, Karsten Østergaard;

    2008-01-01

    We present a fast parallel algorithm to compute the Non-equispaced fast Fourier transform on commodity graphics hardware (the GPU). We focus particularly on a novel implementation of the convolution step in the transform, which was previously its most time consuming part. We describe the performa......We present a fast parallel algorithm to compute the Non-equispaced fast Fourier transform on commodity graphics hardware (the GPU). We focus particularly on a novel implementation of the convolution step in the transform, which was previously its most time consuming part. We describe...

  11. THE MECHANICAL AND SHIELDING DESIGN OF A PORTABLE SPECTROMETER AND BEAM DUMP ASSEMBLY AT BNLS ACCELERATOR TEST FACILITY.

    Energy Technology Data Exchange (ETDEWEB)

    HU,J.P.; CASEY,W.R.; HARDER,D.A.; PJEROV,S.; RAKOWSKY,G.; SKARITKA,J.R.

    2002-09-05

    A portable assembly containing a vertical-bend dipole magnet has been designed and installed immediately down-beam of the Compton electron-laser interaction chamber on beamline 1 of the Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL). The water-cooled magnet designed with field strength of up to 0.7 Tesla will be used as a spectrometer in the Thompson scattering and vacuum acceleration experiments, where field-dependent electron scattering, beam focusing and energy spread will be analyzed. This magnet will deflect the ATF's 60 MeV electron-beam 90{sup o} downward, as a vertical beam dump for the Compton scattering experiment. The dipole magnet assembly is portable, and can be relocated to other beamlines at the ATF or other accelerator facilities to be used as a spectrometer or a beam dump. The mechanical and shielding calculations are presented in this paper. The structural rigidity and stability of the assembly were studied. A square lead shield surrounding the assembly's Faraday Cup was designed to attenuate the radiation emerging from the 1 inch-copper beam stop. All photons produced were assumed to be sufficiently energetic to generate photoneutrons. A safety evaluation of groundwater tritium contamination due to the thermal neutron capturing by the deuterium in water was performed, using updated Monte Carlo neutron-photon coupled transport code (MCNP). High-energy neutron spallation, which is a potential source to directly generate radioactive tritium and sodium-22 in soil, was conservatively assessed in verifying personal and environmental safety.

  12. A new fast neutron collar for safeguards inspection measurements of fresh low enriched uranium fuel assemblies containing burnable poison rods

    International Nuclear Information System (INIS)

    Safeguards inspection measurements must be performed in a timely manner in order to detect the diversion of significant quantities of nuclear material. A shorter measurement time can increase the number of items that a nuclear safeguards inspector can reliably measure during a period of access to a nuclear facility. In turn, this improves the reliability of the acquired statistical sample, which is used to inform decisions regarding compliance. Safeguards inspection measurements should also maintain independence from facility operator declarations. Existing neutron collars employ thermal neutron interrogation for safeguards inspection measurements of fresh fuel assemblies. A new fast neutron collar has been developed for safeguards inspection measurements of fresh low-enriched uranium (LEU) fuel assemblies containing gadolinia (Gd2O3) burnable poison rods. The Euratom Fast Collar (EFC) was designed with high neutron detection efficiency to make a fast (Cd) mode measurement viable whilst meeting the high counting precision and short assay time requirements of the Euratom safeguards inspectorate. A fast mode measurement reduces the instrument sensitivity to burnable poison rod content and therefore reduces the applied poison correction, consequently reducing the dependence on the operator declaration of the poison content within an assembly. The EFC non-destructive assay (NDA) of typical modern European pressurized water reactor (PWR) fresh fuel assembly designs have been simulated using Monte Carlo N-particle extended transport code (MCNPX) simulations. Simulations predict that the EFC can achieve 2% relative statistical uncertainty on the doubles neutron counting rate for a fast mode measurement in an assay time of 600 s (10 min) with the available 241AmLi (α,n) interrogation source strength of 5.7×104 s−1. Furthermore, the calibration range of the new collar has been extended to verify 235U content in variable PWR fuel designs in the presence of up to 32

  13. A new fast neutron collar for safeguards inspection measurements of fresh low enriched uranium fuel assemblies containing burnable poison rods

    Science.gov (United States)

    Evans, Louise G.; Swinhoe, Martyn T.; Menlove, Howard O.; Schwalbach, Peter; Baere, Paul De; Browne, Michael C.

    2013-11-01

    Safeguards inspection measurements must be performed in a timely manner in order to detect the diversion of significant quantities of nuclear material. A shorter measurement time can increase the number of items that a nuclear safeguards inspector can reliably measure during a period of access to a nuclear facility. In turn, this improves the reliability of the acquired statistical sample, which is used to inform decisions regarding compliance. Safeguards inspection measurements should also maintain independence from facility operator declarations. Existing neutron collars employ thermal neutron interrogation for safeguards inspection measurements of fresh fuel assemblies. A new fast neutron collar has been developed for safeguards inspection measurements of fresh low-enriched uranium (LEU) fuel assemblies containing gadolinia (Gd2O3) burnable poison rods. The Euratom Fast Collar (EFC) was designed with high neutron detection efficiency to make a fast (Cd) mode measurement viable whilst meeting the high counting precision and short assay time requirements of the Euratom safeguards inspectorate. A fast mode measurement reduces the instrument sensitivity to burnable poison rod content and therefore reduces the applied poison correction, consequently reducing the dependence on the operator declaration of the poison content within an assembly. The EFC non-destructive assay (NDA) of typical modern European pressurized water reactor (PWR) fresh fuel assembly designs have been simulated using Monte Carlo N-particle extended transport code (MCNPX) simulations. Simulations predict that the EFC can achieve 2% relative statistical uncertainty on the doubles neutron counting rate for a fast mode measurement in an assay time of 600 s (10 min) with the available 241AmLi (α,n) interrogation source strength of 5.7×104 s-1. Furthermore, the calibration range of the new collar has been extended to verify 235U content in variable PWR fuel designs in the presence of up to 32

  14. Stochastic acceleration of electrons by fast magnetosonic waves in solar flares: the effects of anisotropy in velocity and wavenumber space

    Energy Technology Data Exchange (ETDEWEB)

    Pongkitiwanichakul, Peera [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Chandran, Benjamin D. G., E-mail: peera@oddjob.uchicago.edu [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States)

    2014-11-20

    We develop a model for stochastic acceleration of electrons in solar flares. As in several previous models, the electrons are accelerated by turbulent fast magnetosonic waves ({sup f}ast waves{sup )} via transit-time-damping (TTD) interactions. (In TTD interactions, fast waves act like moving magnetic mirrors that push the electrons parallel or anti-parallel to the magnetic field). We also include the effects of Coulomb collisions and the waves' parallel electric fields. Unlike previous models, our model is two-dimensional in both momentum space and wavenumber space and takes into account the anisotropy of the wave power spectrum F{sub k} and electron distribution function f {sub e}. We use weak turbulence theory and quasilinear theory to obtain a set of equations that describes the coupled evolution of F{sub k} and f {sub e}. We solve these equations numerically and find that the electron distribution function develops a power-law-like non-thermal tail within a restricted range of energies E in (E {sub nt}, E {sub max}). We obtain approximate analytic expressions for E {sub nt} and E {sub max}, which describe how these minimum and maximum energies depend upon parameters such as the electron number density and the rate at which fast-wave energy is injected into the acceleration region at large scales. We contrast our results with previous studies that assume that F{sub k} and f {sub e} are isotropic, and we compare one of our numerical calculations with the time-dependent hard-X-ray spectrum observed during the 1980 June 27 flare. In our numerical calculations, the electron energy spectra are softer (steeper) than in models with isotropic F{sub k} and f {sub e} and closer to the values inferred from observations of solar flares.

  15. Fast online Monte Carlo-based IMRT planning for the MRI linear accelerator

    NARCIS (Netherlands)

    Bol, G.H.; Hissoiny, S.; Lagendijk, J. J. W.; Raaymakers, B. W.

    2012-01-01

    The MRI accelerator, a combination of a 6 MV linear accelerator with a 1.5 T MRI, facilitates continuous patient anatomy updates regarding translations, rotations and deformations of targets and organs at risk. Accounting for these demands high speed, online intensity-modulated radiotherapy (IMRT) r

  16. Optical visualization and electrical characterization of fast-rising pulsed dielectric barrier discharge for airflow control applications

    Science.gov (United States)

    Benard, Nicolas; Zouzou, Nourredine; Claverie, Alain; Sotton, Julien; Moreau, Eric

    2012-02-01

    Flow control consists of manipulating flows in an effective and robust manner to improve the global performances of transport systems or industrial processes. Plasma technologies, and particularly surface dielectric barrier discharge (DBD), can be a good candidate for such purpose. The present experimental study focuses on optical and electrical characterization of plasma sheet formed by applying a pulse of voltage with rising and falling periods of 50 ns for a typical surface DBD geometry. Positive and negative polarities are compared in terms of current behavior, deposited energy, fast-imaging of the plasma propagation, and resulting modifications of the surrounding medium by using shadowgraphy acquisitions. Positive and negative pulses of voltage produce streamers and corona type plasma, respectively. Both of them result in the production of a localized pressure wave propagating in the air with a speed maintained at 343 m/s (measurements at room temperature of 20 °C). This suggests that the produced pressure wave can be considered as a propagating sound wave. The intensity of the pressure wave is directly connected to the dissipated energy at the dielectric wall with a linear increase with the applied voltage amplitude and a strong dependence toward the rising time. At constant voltage amplitude, the pressure wave is reinforced by using a positive pulse. The present investigation also reveals that rising and decaying periods of a single pulse of voltage result in two distinct pressure waves. As a result, superposition or successive pressure wave can be produced by adjusting the width of the pulse.

  17. Conceptual design of a 1013 -W pulsed-power accelerator for megajoule-class dynamic-material-physics experiments

    Science.gov (United States)

    Stygar, W. A.; Reisman, D. B.; Stoltzfus, B. S.; Austin, K. N.; Ao, T.; Benage, J. F.; Breden, E. W.; Cooper, R. A.; Cuneo, M. E.; Davis, J.-P.; Ennis, J. B.; Gard, P. D.; Greiser, G. W.; Gruner, F. R.; Haill, T. A.; Hutsel, B. T.; Jones, P. A.; LeChien, K. R.; Leckbee, J. J.; Lewis, S. A.; Lucero, D. J.; McKee, G. R.; Moore, J. K.; Mulville, T. D.; Muron, D. J.; Root, S.; Savage, M. E.; Sceiford, M. E.; Spielman, R. B.; Waisman, E. M.; Wisher, M. L.

    2016-07-01

    We have developed a conceptual design of a next-generation pulsed-power accelerator that is optimized for megajoule-class dynamic-material-physics experiments. Sufficient electrical energy is delivered by the accelerator to a physics load to achieve—within centimeter-scale samples—material pressures as high as 1 TPa. The accelerator design is based on an architecture that is founded on three concepts: single-stage electrical-pulse compression, impedance matching, and transit-time-isolated drive circuits. The prime power source of the accelerator consists of 600 independent impedance-matched Marx generators. Each Marx comprises eight 5.8-GW bricks connected electrically in series, and generates a 100-ns 46-GW electrical-power pulse. A 450-ns-long water-insulated coaxial-transmission-line impedance transformer transports the power generated by each Marx to a system of twelve 2.5-m-radius water-insulated conical transmission lines. The conical lines are connected electrically in parallel at a 66-cm radius by a water-insulated 45-post sextuple-post-hole convolute. The convolute sums the electrical currents at the outputs of the conical lines, and delivers the combined current to a single solid-dielectric-insulated radial transmission line. The radial line in turn transmits the combined current to the load. Since much of the accelerator is water insulated, we refer to it as Neptune. Neptune is 40 m in diameter, stores 4.8 MJ of electrical energy in its Marx capacitors, and generates 28 TW of peak electrical power. Since the Marxes are transit-time isolated from each other for 900 ns, they can be triggered at different times to construct-over an interval as long as 1 μ s -the specific load-current time history required for a given experiment. Neptune delivers 1 MJ and 20 MA in a 380-ns current pulse to an 18 -m Ω load; hence Neptune is a megajoule-class 20-MA arbitrary waveform generator. Neptune will allow the international scientific community to conduct dynamic

  18. Experimental and calculational study of temperature distributions in deformed model fuel assemblies of fast reactors

    International Nuclear Information System (INIS)

    Experimental and calculational data tastify to absence of temperature nonuniformity stabilization in fuel assembly peripheral area. The effect of fuel lattice deformation on the fuel assembly temperature field at shroud crushing in the core centre is demonstrated. 17 refs.; 21 figs

  19. The Crab Nebula super-flare in April 2011: extremely fast particle acceleration and gamma-ray emission

    CERN Document Server

    Striani, E; Piano, G; Donnarumma, I; Pucella, G; Vittorini, V; Bulgarelli, A; Trois, A; Pittori, C; Verrecchia, F; Costa, E; Weisskopf, M; Tennant, A; Argan, A; Barbiellini, G; Caraveo, P; Cardillo, M; Cattaneo, P W; Chen, A W; De Paris, G; Del Monte, E; Di Cocco, G; Evangelista, Y; Ferrari, A; Feroci, M; Fuschino, F; Galli, M; Gianotti, F; Giuliani, A; Labanti, C; Lapshov, I; Lazzarotto, F; Longo, F; Marisaldi, M; Mereghetti, S; Morselli, A; Pacciani, L; Pellizzoni, A; Perotti, F; Picozza, P; Pilia, M; Rapisarda, M; Rappoldi, A; Sabatini, S; Soffitta, P; Trifoglio, M; Vercellone, S; Lucarelli, F; Santolamazza, P; Giommi, P

    2011-01-01

    We report on the extremely intense and fast gamma-ray flare above 100 MeV detected by AGILE from the Crab Nebula in April 2011. This flare is the fourth of a sequence of gamma-ray flaring events produced by the Crab Nebula in the period 2007/mid-2011. These events are attributed to strong radiative instabilities in the inner Crab Nebula, and the study of their properties is crucial to address models of very fast particle acceleration. Here we study the very rapid flux and spectral evolution of the 13-18 April, 2011 event that reached the record-high peak flux of F = (30 +/- 6) x 10^-6 ph cm^-2 s^-1 on a 12-hour timescale. Strong flux and spectral variations are detected on a timescale of a few hours during the pre- and post-flare period. Motivated by the fast variability of the April 2011 event, we also revisit here the AGILE data on the September 2010 Crab Nebula flare that shows similar short timescale variations. The very rapid evolution of the Crab Nebula flares strongly constrains the acceleration proces...

  20. Technical meeting to 'Review of national programmes on fast reactors and accelerator driven systems (ADS)'. Working material

    International Nuclear Information System (INIS)

    36th Annual Meeting of the Technical Working Group on Fast Reactors, the IAEA Technical Meeting (TM) on 'Review of National Programmes on Fast Reactors and Accelerator Driven Systems (ADS)', hosted by the Korean Atomic Energy Research Institute (KAERI) was attended by TWG-FR Members and Advisers from the following Member States (MS) and International Organizations: Brazil, France, Germany, India, Japan, the Republic of Kazakhstan, the Republic of Korea, the Russian Federation, the United Kingdom, the United States of America, and the OECD/NEA. The objectives of the meeting were to: 1) exchange information on the national programmes on Fast Reactors (FR) and Accelerator Driven Systems (ADS); 2) review the progress since the 35th TWG-FR Annual Meeting, including the status of the actions; 3) consider meeting arrangements for 2003 and 2004; 4) review the Agency's co-ordinated research activities in the field of FRs and ADS, as well as co-ordination of the TWG-FR's activities with other organizations. The participants made presentations on the status of the respective national programmes on FR and ADS development. A summary of the highlights for the period since the 35th TWG-FR Annual Meeting

  1. Design of a beam shaping assembly and preliminary modelling of a treatment room for accelerator-based BNCT at CNEA

    Energy Technology Data Exchange (ETDEWEB)

    Burlon, A.A.; Girola, S. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica, San Martin (Argentina)] [Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin, San Martin (Argentina); Valda, A.A., E-mail: valda@tandar.cnea.gov.ar [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica, San Martin (Argentina)] [Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin, San Martin (Argentina); Minsky, D.M.; Kreiner, A.J. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica, San Martin (Argentina)] [Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin, San Martin (Argentina)] [CONICET, Buenos Aires (Argentina); Sanchez, G. [Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin, San Martin (Argentina)

    2011-12-15

    This work reports on the characterisation of a neutron beam shaping assembly (BSA) prototype and on the preliminary modelling of a treatment room for BNCT within the framework of a research programme for the development and construction of an accelerator-based BNCT irradiation facility in Buenos Aires, Argentina. The BSA prototype constructed has been characterised by means of MCNP simulations as well as a set of experimental measurements performed at the Tandar accelerator at the National Atomic Energy Commission of Argentina. - Highlights: Black-Right-Pointing-Pointer Characterisation of a neutron beam shaping assembly for accelerator-based BNCT. Black-Right-Pointing-Pointer Measurements: total and epi-cadmium neutron fluxes and beam homogeneity. Black-Right-Pointing-Pointer Calculations: Monte Carlo simulations with the MCNP code. Black-Right-Pointing-Pointer Measured and calculated figure-of-merit parameters in agreement with those of IAEA. Black-Right-Pointing-Pointer Initial MCNP dose calculations for a treatment room to define future design actions.

  2. The relationship between contrast, resolution and detectability in accelerator-based fast neutron radiography

    International Nuclear Information System (INIS)

    Fast neutron radiography as a method for non destructive testing is a fast growing field of research. At the Schonland Research Center for Nuclear Sciences we have been engaged in the formulation of a model for the physics of image formation in fast neutron radiography (FNR). This involves examining all the various factors that affect image formation in FNR by experimental and Monte Carlo methods. One of the major problems in the development of a model for fast neutron radiography is the determination of the factors that affect image contrast and resolution. Monte Carlo methods offer an ideal tool for the determination of the origin of many of these factors. In previous work the focus of these methods has been the determination of the scattered neutron field in both a scintillator and a fast neutron radiography facility. As an extension of this work MCNP has been used to evaluate the role neutron scattering in a specimen plays in image detectability. Image processing of fast neutron radiographs is a necessary method of enhancing the detectability of features in an image. MCNP has been used to determine the part it can play in indirectly improving image resolution and aiding in image processing. The role noise plays in fast neutron radiography and its impact on image reconstruction has been evaluated. All these factors aid in the development of a model describing the relationship between contrast, resolution and detectability

  3. 11-interval PFG pulse sequence for improved measurement of fast velocities of fluids with high diffusivity in systems with short T2∗

    Science.gov (United States)

    Boyce, C. M.; Rice, N. P.; Sederman, A. J.; Dennis, J. S.; Holland, D. J.

    2016-04-01

    Magnetic resonance (MR) was used to measure SF6 gas velocities in beds filled with particles of 1.1 mm and 0.5 mm in diameter. Four pulse sequences were tested: a traditional spin echo pulse sequence, the 9-interval and 13-interval pulse sequence of Cotts et al. (1989) and a newly developed 11-interval pulse sequence. All pulse sequences measured gas velocity accurately in the region above the particles at the highest velocities that could be achieved (up to 0.1 m s-1). The spin echo pulse sequence was unable to measure gas velocity accurately in the bed of particles, due to effects of background gradients, diffusivity and acceleration in flow around particles. The 9- and 13-interval pulse sequence measured gas velocity accurately at low flow rates through the particles (expected velocity echo time that the new pulse sequence enabled, reducing selective attenuation of signal from faster moving nuclei.

  4. Deuterium Gas-Puff Z-pinch as a Source of Fast Ions Producing Intensive Pulse of Neutrons

    Science.gov (United States)

    Rezac, K.; Cikhardt, J.; Cikhardtova, B.; Klir, D.; Kravarik, J.; Kubes, P.; Sila, O.; Shishlov, A.; Cherdizov, R.; Fursov, F.; Kokshenev, V.; Kovalchuk, B.; Kurmaev, N.; Labetsky, A.; Ratakhin, N.; Turek, K.

    2015-11-01

    A deuterium gas-puff with outer plasma shell has been examined on GIT-12 generator (on the current level of 3 MA) since 2013. Such a configuration caused more stable implosion at final stage of z-pinch. The consequence of this was a production of intensive pulses of fast ions. During last 4 campaigns in 2013-2015, fast ions were examined by several in-chamber diagnostics such as: stack detector (ion energy), pinhole camera (location of ion source), multi-pinhole camera (asymmetry and anisotropy of ion emission), and ion beam detector (dynamics of ion pulses). A CR-39 track detectors and also GAFCHROMIC HD-V2 films from these diagnostics will be presented. On the basis of obtained results, the solid sample for increasing of neutron yield up to 1e13 could be placed below the cathode mesh. Except of neutron yield, other properties such as: neutron energies (up to 33 MeV), neutron emission time (about 20 ns), and emission anisotropy of neutrons were measured. Such a short and intensive neutron pulse provides various applications. This work was supported by the MSMT project LH13283.

  5. Density Determination of Liquid Copper and Liquid Nickel by Means of Fast Resistive Pulse Heating and Electromagnetic Levitation

    Science.gov (United States)

    Schmon, Alexander; Aziz, Kirmanj; Pottlacher, Gernot

    2015-06-01

    Fast resistive pulse-heating techniques and electromagnetic levitation techniques are capable of determining thermophysical properties of metals in the liquid phase. These properties have become increasingly important as input data for modern numerical simulations. Among others, density is a very relevant parameter for e.g., casting modeling. Density determinations of copper and nickel in their liquid states are performed using a fast resistive pulse-heating setup and a recently build up electromagnetic levitation apparatus. Both methods use optical imaging techniques to determine thermal expansion of the specimen under investigation, but are operating at very different experimental durations. The pulse-heating setup provides a heating of the sample using it as part of an electrical discharge circuit. Heating rates of 108 K/s lead to experimental durations of about 60 µs. Temperature is determined by measuring surface radiance emitted from the sample by a pyrometer. The sample's thermal expansion is monitored by an adapted CCD camera system. The electromagnetic levitation apparatus enables noncontact investigations of samples by levitating and heating them by an induction coil generating inhomogeneous electromagnetic fields. Temperature again is determined by a pyrometer. For thermal expansion determination, shadowgraph images are recorded with a high-speed CCD camera and evaluated with an edge detection algorithm. Thermal expansion then is calculated by averaging several 1000 frames for each temperature point. Investigations of copper and nickel in the liquid state were performed with both techniques and are compared to each other and to literature values.

  6. Fast and thermal neutron intensity measurements at the KFUPM PGNAA setup

    CERN Document Server

    Al-Jarallah, M I; Fazal-Ur-Rehman; Abu-Jarad, F A

    2002-01-01

    Fast and thermal neutron intensity distributions have been measured at an accelerator based prompt gamma ray neutron activation analysis (PGNAA) setup. The setup is built at the 350 keV accelerator laboratory of King Fahd University of Petroleum and Minerals (KFUPM). The setup is mainly designed to carry out PGNAA elemental analysis via thermal neutron capture. In this study relative intensity of fast and thermal neutrons was measured as a function of the PGNAA moderator assembly parameters using nuclear track detectors (NTDs). The relative intensity of the neutrons was measured inside the sample region as a function of front moderator thickness as well as sample length. Measurements were carried out at the KFUPM 350 keV accelerator using 2.8 MeV pulsed neutron beam from D(d,n) reaction. The pulsed deuteron beam with 5 ns pulse width and 30 kHz frequency was used to produce neutrons. Experimental results were compared with results of Monte Carlo design calculations of the PGNAA setup. A good agreement has bee...

  7. Fast and thermal neutron intensity measurements at the KFUPM PGNAA setup

    Science.gov (United States)

    Al-Jarallah, M. I.; Naqvi, A. A.; Fazal-ur-Rehman; Abu-jarad, F.

    2002-10-01

    Fast and thermal neutron intensity distributions have been measured at an accelerator based prompt gamma ray neutron activation analysis (PGNAA) setup. The setup is built at the 350 keV accelerator laboratory of King Fahd University of Petroleum and Minerals (KFUPM). The setup is mainly designed to carry out PGNAA elemental analysis via thermal neutron capture. In this study relative intensity of fast and thermal neutrons was measured as a function of the PGNAA moderator assembly parameters using nuclear track detectors (NTDs). The relative intensity of the neutrons was measured inside the sample region as a function of front moderator thickness as well as sample length. Measurements were carried out at the KFUPM 350 keV accelerator using 2.8 MeV pulsed neutron beam from D(d,n) reaction. The pulsed deuteron beam with 5 ns pulse width and 30 kHz frequency was used to produce neutrons. Experimental results were compared with results of Monte Carlo design calculations of the PGNAA setup. A good agreement has been found between the experimental results and the calculations.

  8. Fast and thermal neutron intensity measurements at the KFUPM PGNAA setup

    International Nuclear Information System (INIS)

    Fast and thermal neutron intensity distributions have been measured at an accelerator based prompt gamma ray neutron activation analysis (PGNAA) setup. The setup is built at the 350 keV accelerator laboratory of King Fahd University of Petroleum and Minerals (KFUPM). The setup is mainly designed to carry out PGNAA elemental analysis via thermal neutron capture. In this study relative intensity of fast and thermal neutrons was measured as a function of the PGNAA moderator assembly parameters using nuclear track detectors (NTDs). The relative intensity of the neutrons was measured inside the sample region as a function of front moderator thickness as well as sample length. Measurements were carried out at the KFUPM 350 keV accelerator using 2.8 MeV pulsed neutron beam from D(d,n) reaction. The pulsed deuteron beam with 5 ns pulse width and 30 kHz frequency was used to produce neutrons. Experimental results were compared with results of Monte Carlo design calculations of the PGNAA setup. A good agreement has been found between the experimental results and the calculations

  9. A 3-10 GHz IR-UWB CMOS Pulse Generator With 6-mW Peak Power Dissipation Using A Slow-Charge Fast-Discharge Technique

    OpenAIRE

    Shen, Ming; Yin, Ying-Zheng; Jiang, Hao; Tong, Tian; Mikkelsen, Jan H.

    2014-01-01

    This letter proposes a UWB pulse generator topology featuring low peak power dissipation for applications with stringent instantaneous power requirements. This is accomplished by employing a new slow-charge fast-discharge approach to extend the time duration of the generator's peak current so that the peak value of the current is significantly reduced, while maintaining the waveform of the generated UWB pulse signal. A prototype pulse generator has been implemented using the UMC 0.18 μm CMOS ...

  10. Real-Time Dedispersion for Fast Radio Transient Surveys, using Auto Tuning on Many-Core Accelerators

    CERN Document Server

    Sclocco, Alessio; Bal, Henri E; van Nieuwpoort, Rob V

    2016-01-01

    Dedispersion, the removal of deleterious smearing of impulsive signals by the interstellar matter, is one of the most intensive processing steps in any radio survey for pulsars and fast transients. We here present a study of the parallelization of this algorithm on many-core accelerators, including GPUs from AMD and NVIDIA, and the Intel Xeon Phi. We find that dedispersion is inherently memory-bound. Even in a perfect scenario, hardware limitations keep the arithmetic intensity low, thus limiting performance. We next exploit auto-tuning to adapt dedispersion to different accelerators, observations, and even telescopes. We demonstrate that the optimal settings differ between observational setups, and that auto-tuning significantly improves performance. This impacts time-domain surveys from Apertif to SKA.

  11. Real-time dedispersion for fast radio transient surveys, using auto tuning on many-core accelerators

    Science.gov (United States)

    Sclocco, A.; van Leeuwen, J.; Bal, H. E.; van Nieuwpoort, R. V.

    2016-01-01

    Dedispersion, the removal of deleterious smearing of impulsive signals by the interstellar matter, is one of the most intensive processing steps in any radio survey for pulsars and fast transients. We here present a study of the parallelization of this algorithm on many-core accelerators, including GPUs from AMD and NVIDIA, and the Intel Xeon Phi. We find that dedispersion is inherently memory-bound. Even in a perfect scenario, hardware limitations keep the arithmetic intensity low, thus limiting performance. We next exploit auto-tuning to adapt dedispersion to different accelerators, observations, and even telescopes. We demonstrate that the optimal settings differ between observational setups, and that auto-tuning significantly improves performance. This impacts time-domain surveys from Apertif to SKA.

  12. Fast ion mass spectrometry and charged particle spectrography investigations of transverse ion acceleration and beam-plasma interactions. Final report

    International Nuclear Information System (INIS)

    Ion acceleration transverse to the magnetic field in the topside ionosphere was investigated. Transverse acceleration is believed to be responsible for the upward-moving conical ion distributions commonly observed along auroral field lines at altitudes from several hundred to several thousand kilometers. Of primary concern in this investigation is the extent of these conic events in space and time. Theoretical predictions indicate very rapid initial heating rates, depending on the ion species. These same theories predict that the events will occur within a narrow vertical region of only a few hundred kilometers. Thus an instrument with very high spatial and temporal resolution was required; further, since different heating rates were predicted for different ions, it was necessary to obtain composition as well as velocity space distributions. The fast ion mass spectrometer (FIMS) was designed to meet these criteria. This instrument and its operation is discussed

  13. Fast ion mass spectrometry and charged particle spectrography investigations of transverse ion acceleration and beam-plasma interactions

    Science.gov (United States)

    Gibson, W. C.; Tomlinson, W. M.; Marshall, J. A.

    1987-01-01

    Ion acceleration transverse to the magnetic field in the topside ionosphere was investigated. Transverse acceleration is believed to be responsible for the upward-moving conical ion distributions commonly observed along auroral field lines at altitudes from several hundred to several thousand kilometers. Of primary concern in this investigation is the extent of these conic events in space and time. Theoretical predictions indicate very rapid initial heating rates, depending on the ion species. These same theories predict that the events will occur within a narrow vertical region of only a few hundred kilometers. Thus an instrument with very high spatial and temporal resolution was required; further, since different heating rates were predicted for different ions, it was necessary to obtain composition as well as velocity space distributions. The fast ion mass spectrometer (FIMS) was designed to meet these criteria. This instrument and its operation is discussed.

  14. Laser-plasma acceleration with multi-color pulse stacks: Designer electron beams for advanced radiation sources

    Science.gov (United States)

    Kalmykov, Serge; Shadwick, Bradley; Ghebregziabher, Isaac; Davoine, Xavier

    2015-11-01

    Photon engineering offers new avenues to coherently control electron beam phase space on a femtosecond time scale. It enables generation of high-quality beams at a kHz-scale repetition rate. Reducing the peak pulse power (and thus the average laser power) is the key to effectively exercise such control. A stepwise negative chirp, synthesized by incoherently stacking collinear sub-Joule pulses from conventional CPA, affords a micron-scale bandwidth. It is sufficient to prevent rapid compression of the pulse into an optical shock, while delaying electron dephasing. This extends electron energy far beyond the limits suggested by accepted scalings (beyond 1 GeV in a 3 mm plasma), without compromising beam quality. In addition, acceleration with a stacked pulse in a channel favorably modifies electron beam on a femtosecond time scale, controllably producing synchronized sequences of 100 kA-scale, quasi-monoenergetic bunches. These comb-like, designer GeV electron beams are ideal drivers of polychromatic, tunable inverse Thomson γ-ray sources. The work of SYK and BAS is supported by the US DOE Grant DE-SC0008382 and NSF Grant PHY-1104683. Inverse Thomson scattering simulations were completed utilizing the Holland Computing Center of the University of Nebraska.

  15. Macromolecularly crowded in vitro microenvironments accelerate the production of extracellular matrix-rich supramolecular assemblies

    OpenAIRE

    Kumar, Pramod; Satyam, Abhigyan; Fan, Xingliang; Rodriguez, Brian J.; et al

    2015-01-01

    Therapeutic strategies based on the principles of tissue engineering by self-assembly put forward the notion that functional regeneration can be achieved by utilising the inherent capacity of cells to create highly sophisticated supramolecular assemblies. However, in dilute ex vivo microenvironments, prolonged culture time is required to develop an extracellular matrix-rich implantable device. Herein, we assessed the influence of macromolecular crowding, a biophysical phenomenon that regulate...

  16. A fast-acting hydrogen gas source for staged pneumatic high-speed acceleration of fusion plasma fuel pellets

    International Nuclear Information System (INIS)

    This report describes a possible design of a fast, high-temperature, arc-driven hydrogen gas source module, to be used in a scheme for multistage high-speed pneumatic acceleration of fusion plasma fuel pellets. The potential of this scheme for operating with a moderate driving pressure at long acceleration path lengths is particular attractive for accelerating fragile hydrogen isotope ice pellets. From experiments with an ethanol-based arc unit, design parameters for a propeller module were assessed, and with a barrel-mounted ethanol module staged pneumatic acceleration of a plastic dummy pellet was demonstrated. In experiments with a hydrogenbased, cryogenic arc unit in which 200 joules of electrical energy were dissipated with a power level approaching 5 MW within 30 mus, the velocity of a 23-mg plastic pellet was increased from 1.7 to 2.4 km/s. Results in terms of barrel pressure transients and arc characteristics are described. (author) 20 ills., 8 refs

  17. Accelerated fast spin-echo magnetic resonance imaging of the heart using a self-calibrated split-echo approach.

    Directory of Open Access Journals (Sweden)

    Sabrina Klix

    Full Text Available PURPOSE: Design, validation and application of an accelerated fast spin-echo (FSE variant that uses a split-echo approach for self-calibrated parallel imaging. METHODS: For self-calibrated, split-echo FSE (SCSE-FSE, extra displacement gradients were incorporated into FSE to decompose odd and even echo groups which were independently phase encoded to derive coil sensitivity maps, and to generate undersampled data (reduction factor up to R = 3. Reference and undersampled data were acquired simultaneously. SENSE reconstruction was employed. RESULTS: The feasibility of SCSE-FSE was demonstrated in phantom studies. Point spread function performance of SCSE-FSE was found to be competitive with traditional FSE variants. The immunity of SCSE-FSE for motion induced mis-registration between reference and undersampled data was shown using a dynamic left ventricular model and cardiac imaging. The applicability of black blood prepared SCSE-FSE for cardiac imaging was demonstrated in healthy volunteers including accelerated multi-slice per breath-hold imaging and accelerated high spatial resolution imaging. CONCLUSION: SCSE-FSE obviates the need of external reference scans for SENSE reconstructed parallel imaging with FSE. SCSE-FSE reduces the risk for mis-registration between reference scans and accelerated acquisitions. SCSE-FSE is feasible for imaging of the heart and of large cardiac vessels but also meets the needs of brain, abdominal and liver imaging.

  18. Plasma erosion opening switch in the double-pulse operation mode of a high-current electron accelerator

    International Nuclear Information System (INIS)

    This paper reports the results of investigations of the operation of a fast current opening switch, with a 10/sup 13/-10/sup 16/ plasma density produced either by dielectric surface flashover or by explosive emission of graphite. A series of two pulses was applied to two diodes in parallel. The first pulse produced plasma in the first diode which closed that diode gap by the arrival time of the second pulse. The first, shorted, diode then acted as an erosion switch for the second pulse. A factor of 2.5-3 power multiplication was obtained under optimum conditions. The opening-switch resistance during the magnetic insulation phase, neglecting the electron losses between the switch and the generating diode, exceeded 100 Ω. The duration of the rapid opening phase was less than 5 ns under optimum conditions. This method of plasma production does not require external plasma sources, and permits a wide variation of plasma density, which in turn allows high inductor currents and stored energies

  19. Failure Engineering Study and Accelerated Stress Test Results for the Mars Global Surveyor Spacecraft's Power Shunt Assemblies

    Science.gov (United States)

    Gibbel, Mark; Larson, Timothy

    2000-01-01

    An Engineering-of-Failure approach to designing and executing an accelerated product qualification test was performed to support a risk assessment of a "work-around" necessitated by an on-orbit failure of another piece of hardware on the Mars Global Surveyor spacecraft. The proposed work-around involved exceeding the previous qualification experience both in terms of extreme cold exposure level and in terms of demonstrated low cycle fatigue life for the power shunt assemblies. An analysis was performed to identify potential failure sites, modes and associated failure mechanisms consistent with the new use conditions. A test was then designed and executed which accelerated the failure mechanisms identified by analysis. Verification of the resulting failure mechanism concluded the effort.

  20. Technical committee on review of national programmes on fast reactors and accelerator driven systems (ADS). Working material

    International Nuclear Information System (INIS)

    The objectives of the meeting were: to exchange information on the national programmes on fast reactors (FR) and accelerator driven systems (ADS); to review the progress since the previous IWG-FR meeting, including the status of the actions; to consider meeting arrangements for 2001 and 2002; to review the Agency co-ordinated research activities in the field of FR and ADS, as well as so-ordination of the TWG-FR activities with their organisations. This report covers the reports presented on the relevant activities in Brazil, China, France, Germany, India, Italy, Japan, Kazakhstan, Republic of Korea, Russia, Sweden, United Kingdom and USA

  1. Facile "modular assembly" for fast construction of a highly oriented crystalline MOF nanofilm.

    Science.gov (United States)

    Xu, Gang; Yamada, Teppei; Otsubo, Kazuya; Sakaida, Shun; Kitagawa, Hiroshi

    2012-10-10

    The preparation of crystalline, ordered thin films of metal-organic frameworks (MOFs) will be a critical process for MOF-based nanodevices in the future. MOF thin films with perfect orientation and excellent crystallinity were formed with novel nanosheet-structured components, Cu-TCPP [TCPP = 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin], by a new "modular assembly" strategy. The modular assembly process involves two steps: a "modularization" step is used to synthesize highly crystalline "modules" with a nanosized structure that can be conveniently assembled into a thin film in the following "assembly" step. With this method, MOF thin films can easily be set up on different substrates at very high speed with controllable thickness. This new approach also enabled us to prepare highly oriented crystalline thin films of MOFs that cannot be prepared in thin-film form by traditional techniques.

  2. Vircator with premodulation of electron beam on the basis of heavy-current pulse-periodic accelerator

    CERN Document Server

    Kitsanov, S A; Korovin, S D; Kurkan, I K; Pegel, I V; Polevin, S D

    2002-01-01

    One carried out theoretical, numerical and experimental investigations into vircator with premodulation of wavelength decimeter region electron beam. One analyzed possible mechanisms of generation excitation in systems with a virtual cathode. On the basis of numerical experiment results one developed experimental model of two-section vircator without external magnetic field. In experiments with heavy-current pulse-periodic electron accelerator within wavelength decimeter region one produced supermode generation with up to 1 GW power and approx 25 ns duration at approx 5% efficiency of generation. By varying parameters of resonator one managed to ensure continuous retuning of vircator generation frequency within approx 15% band at half level of power

  3. Vircator with premodulation of electron beam on the basis of heavy-current pulse-periodic accelerator

    International Nuclear Information System (INIS)

    One carried out theoretical, numerical and experimental investigations into vircator with premodulation of wavelength decimeter region electron beam. One analyzed possible mechanisms of generation excitation in systems with a virtual cathode. On the basis of numerical experiment results one developed experimental model of two-section vircator without external magnetic field. In experiments with heavy-current pulse-periodic electron accelerator within wavelength decimeter region one produced supermode generation with up to 1 GW power and ∼ 25 ns duration at ∼ 5% efficiency of generation. By varying parameters of resonator one managed to ensure continuous retuning of vircator generation frequency within ∼ 15% band at half level of power

  4. Comparative study of ion acceleration by linearly polarized laser pulses from optimized targets of solid and near-critical density

    Science.gov (United States)

    Bychenkov, V. Yu; Brantov, A. V.; Govras, E. A.

    2016-03-01

    The results of a 3D optimization study of ion acceleration from ultrathin solid density foils (Brantov et al 2015 Phys. Rev. Spec. Top. Accel. Beams 18 021301) are complemented with an improved analytic model of the directed Coulomb explosion. Similarly to optimizing overdense targets, we also optimize low-density targets to obtain maximum ion energy, motivated by progress in producing a new generation of low-density slab targets whose density can be very homogeneous and as low as the relativistic critical density. Using 3D simulations, we show that for the same laser pulse, the ion energy can be significantly increased with low-density targets. A new acceleration mechanism is responsible for such an increase. This mechanism is described qualitatively, and it explains an advantage of low-density targets for high-energy ion production by lasers.

  5. The Fast Changing Landscape of Sequencing Technologies and Their Impact on Microbial Genome Assemblies and Annotation

    Energy Technology Data Exchange (ETDEWEB)

    Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Brettin, Thomas S [ORNL; Quest, Daniel J [ORNL; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Clum, Alicia [U.S. Department of Energy, Joint Genome Institute; Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute; Klenk, Hans-Peter [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Cottingham, Robert W [ORNL; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute

    2012-01-01

    Background: The emergence of next generation sequencing (NGS) has provided the means for rapid and high throughput sequencing and data generation at low cost, while concomitantly creating a new set of challenges. The number of available assembled microbial genomes continues to grow rapidly and their quality reflects the quality of the sequencing technology used, but also of the analysis software employed for assembly and annotation. Methodology/Principal Findings: In this work, we have explored the quality of the microbial draft genomes across various sequencing technologies. We have compared the draft and finished assemblies of 133 microbial genomes sequenced at the Department of Energy-Joint Genome Institute and finished at the Los Alamos National Laboratory using a variety of combinations of sequencing technologies, reflecting the transition of the institute from Sanger-based sequencing platforms to NGS platforms. The quality of the public assemblies and of the associated gene annotations was evaluated using various metrics. Results obtained with the different sequencing technologies, as well as their effects on downstream processes, were analyzed. Our results demonstrate that the Illumina HiSeq 2000 sequencing system, the primary sequencing technology currently used for de novo genome sequencing and assembly at JGI, has various advantages in terms of total sequence throughput and cost, but it also introduces challenges for the downstream analyses. In all cases assembly results although on average are of high quality, need to be viewed critically and consider sources of errors in them prior to analysis. Conclusion: These data follow the evolution of microbial sequencing and downstream processing at the JGI from draft genome sequences with large gaps corresponding to missing genes of significant biological role to assemblies with multiple small gaps (Illumina) and finally to assemblies that generate almost complete genomes (Illumina+PacBio).

  6. Pulse radiolysis studies of fast reactions in molecular systems. Progress report, February 1, 1981-September 30, 1982

    International Nuclear Information System (INIS)

    The rates of elementary chemical reactions in irradiated solutions are being studied by observation of the formation and decay of reactive intermediates using the pulse radiolysis technique. These short-lived species are monitored by fast optical absorption measurement; optical absorption spectra of the transients are also obtained. Reactive species currently of interest include organic molecule ions (both cations and anions) and radical anions. Transition metal carbonyl radicals in solution, another category of intermediates, are also under investigation. Since the reactions are initiated by a pulse of high energy electrons, this work inherently relates to radiation chemical systems. The information obtained is also of interest in various areas of organic reaction kinetics in which ions play a central role. In the area of homogeneous catalysis, the reactivity of transition metal carbonyl radicals is of interest. Current activities are directed at reactivity of organic ionic species (carbocations and carbanions) in irradiated solutions; and optical spectra and reactivities of transition metal carbonyl radicals

  7. Fast pulsed operation of a small non-radioactive electron source with continuous emission current control.

    Science.gov (United States)

    Cochems, P; Kirk, A T; Bunert, E; Runge, M; Goncalves, P; Zimmermann, S

    2015-06-01

    Non-radioactive electron sources are of great interest in any application requiring the emission of electrons at atmospheric pressure, as they offer better control over emission parameters than radioactive electron sources and are not subject to legal restrictions. Recently, we published a simple electron source consisting only of a vacuum housing, a filament, and a single control grid. In this paper, we present improved control electronics that utilize this control grid in order to focus and defocus the electron beam, thus pulsing the electron emission at atmospheric pressure. This allows short emission pulses and excellent stability of the emitted electron current due to continuous control, both during pulsed and continuous operations. As an application example, this electron source is coupled to an ion mobility spectrometer. Here, the pulsed electron source allows experiments on gas phase ion chemistry (e.g., ion generation and recombination kinetics) and can even remove the need for a traditional ion shutter.

  8. Pulse radiolysis studies of fast reactions in molecular systems. Progress report, November 1976--October 1977

    International Nuclear Information System (INIS)

    Results from research in the following two areas are given: formation, properties, and reactivity of molecular ionic species in irradiated liquid systems; and pulse radiolysis of elementary reactions in protein function

  9. Highly Compact Accelerator-Driven Subcritical Assembly for Medical and Industrial Applications

    International Nuclear Information System (INIS)

    A novel, highly compact, fusion neutron source (CNS) based on a coaxial electrostatic accelerator is under development at the Lawrence Berkeley National Laboratory. This source is designed to generate up to ∼1012 D-D n/s. This source intensity is an order of magnitude too small for Boron Neutron Capture Therapy (BNCT) applications. The objective of this project is to assess the feasibility of using a small, safe and inexpensive subcritical fission assembly to multiply the fusion neutrons by a factor of (ge)30. The overall design objective is to get a treatment time for deep seated rain tumors that does not significantly increase beyond one hour when the effective multiplication factor of the SCM is keff = 0.98. There are two major parts to this study: the optimization of the Sub-Critical Multiplier (SCM) and the optimization of the Beam Shaping Assembly (BSA), including the reflector for both subsystems. The SCM optimization objective is to maximize the current of neutrons that leak out from the SCM in the direction of the patient, without exceeding the maximum permissible keff. Minimizing the required uranium inventory is another objective. SCM design variables considered include the uranium enrichment level in the range not exceeding 20% 235U (for proliferation concerns), SCM geometry and dimensions, fuel thickness and moderator thickness. The objective of the BSA optimization is to maximize the tumor dose rate using the optimal SCM while maintaining a tumor-to-normal tissue dose ratio of at least 20 to 12.5 (corresponding to the tumor control dose and to the healthy tissue dose limit). The BSA design variables include its shape, dimensions and composition. The reflector optimization is, in fact, an integral part of the SCM optimization and of the BSA optimization. The reflector design variables are composition and thickness. The study concludes that it is not quite feasible to achieve the project objective. Nevertheless, it appears feasible to develop a

  10. STATUS OF THE DIELECTRIC WALL ACCELERATOR

    Energy Technology Data Exchange (ETDEWEB)

    Caporaso, G J; Chen, Y; Sampayan, S; Akana, G; Anaya, R; Blackfield, D; Carroll, J; Cook, E; Falabella, S; Guethlein, G; Harris, J; Hawkins, S; Hickman, B; Holmes, C; Horner, A; Nelson, S; Paul, A; Pearson, D; Poole, B; Richardson, R; Sanders, D; Selenes, K; Sullivan, J; Wang, L; Watson, J; Weir, J

    2009-04-22

    The dielectric wall accelerator (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL) uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system is capable of accelerating any charge to mass ratio particle. Applications of high gradient proton and electron versions of this accelerator will be discussed. The status of the developmental new technologies that make the compact system possible will be reviewed. These include, high gradient vacuum insulators, solid dielectric materials, photoconductive switches and compact proton sources.

  11. BESTIA - The next generation ultra-fast CO2 laser for advanced accelerator research

    Science.gov (United States)

    Pogorelsky, Igor V.; Babzien, Markus; Ben-Zvi, Ilan; Skaritka, John; Polyanskiy, Mikhail N.

    2016-09-01

    Over the last two decades, BNL's ATF has pioneered the use of high-peak power CO2 lasers for research in advanced accelerators and radiation sources. Our recent developments in ion acceleration, Compton scattering, and IFELs have further underscored the benefits from expanding the landscape of strong-field laser interactions deeper into the mid-infrared (MIR) range of wavelengths. This extension validates our ongoing efforts in advancing CO2 laser technology, which we report here. Our next-generation, multi-terawatt, femtosecond CO2 laser will open new opportunities for studying ultra-relativistic laser interactions with plasma in the MIR spectral domain, including new regimes in the particle acceleration of ions and electrons.

  12. China ADS sub-critical experimental assembly-Venus-1 and preliminary experiment

    Institute of Scientific and Technical Information of China (English)

    SHI Yongqian; ZHANG Wei; CAO Jian; QUAN Yanhui; LUO Huangda; WU Xiaofei; XIA Pu; LUO Zhanglin; ZHAO Zhixiang; DING Dazhao; LI Yiguo; ZHU Qinfu; XIA Haihong; LI Jien

    2007-01-01

    China's accelerator-driven sub-critical system (ADS) sub-critical experimental assembly--Venus-1 and the preliminary experiment is presented. The core of Venus-1 is a coupled one of a fast neutron zone and a thermal neutron zone. The fast neutron zone is at the centre of the core and formed by natural uranium fuel. A fast neutron spectrum field can be produced in the fast neutron zone and used for the transmutation of minor actinides (Mas). The thermal neutron zone surrounds the fast neutron zone and is formed by low-enriched uranium fuel. It is a fission zone. An epithermal neutron zone between the fast neutron zone and the thermal neutron zone can be established for the transmutation of longlived fission products (LLFP). On July 18, 2005, the first fuel element was loaded into the Venus-Ⅰ sub-critical assembly and some preliminary experiments about the subcritical neutronics were performed. The Venus-1 can be driven by an Am-Be source or other steady neutron source (Cf-252, D-D reaction and D-T reaction) to study the effect of the external neutron source with different energies or a D-T pulsed neutron source on the dynamic characteristics.

  13. Electron Acceleration and the Propagation of Ultrashort High-Intensity Laser Pulses in Plasmas

    International Nuclear Information System (INIS)

    Reported are interactions of high-intensity laser pulses (λ=810 nm and I≤3x1018 W /cm2 ) with plasmas in a new parameter regime, in which the pulse duration (τ=29 fs ) corresponds to 0.6-2.6 plasma periods. Relativistic filamentation is observed to cause laser-beam breakup and scattering of the beam out of the vacuum propagation angle. A beam of megaelectronvolt electrons with divergence angle as small as 1 degree sign is generated in the forward direction, which is correlated to the growth of the relativistic filamentation. Raman scattering, however, is found to be much less than previous long-pulse results. (c) 2000 The American Physical Society

  14. A Fast GPU-accelerated Mixed-precision Strategy for Fully NonlinearWater Wave Computations

    DEFF Research Database (Denmark)

    Glimberg, Stefan Lemvig; Engsig-Karup, Allan Peter; Madsen, Morten G.

    2011-01-01

    -preconditioned defect correction method. The improved strategy improves the performance by exploiting architectural features of modern GPUs for mixed precision computations and is tested in a recently developed generic library for fast prototyping of PDE solvers. The new wave tool is applicable to solve and analyze...

  15. Analysis of the scintillation mechanism in a pressurized 4He fast neutron detector using pulse shape fitting

    Directory of Open Access Journals (Sweden)

    R.P. Kelley

    2015-03-01

    Full Text Available An empirical investigation of the scintillation mechanism in a pressurized 4He gas fast neutron detector was conducted using pulse shape fitting. Scintillation signals from neutron interactions were measured and averaged to produce a single generic neutron pulse shape from both a 252Cf spontaneous fission source and a (d,d neutron generator. An expression for light output over time was then developed by treating the decay of helium excited states in the same manner as the decay of radioactive isotopes. This pulse shape expression was fitted to the measured neutron pulse shape using a least-squares optimization algorithm, allowing an empirical analysis of the mechanism of scintillation inside the 4He detector. A further understanding of this mechanism in the 4He detector will advance the use of this system as a neutron spectrometer. For 252Cf neutrons, the triplet and singlet time constants were found to be 970 ns and 686 ns, respectively. For neutrons from the (d,d generator, the time constants were found to be 884 ns and 636 ns. Differences were noted in the magnitude of these parameters compared to previously published data, however the general relationships were noted to be the same and checked with expected trends from theory. Of the excited helium states produced from a 252Cf neutron interaction, 76% were found to be born as triplet states, similar to the result from the neutron generator of 71%. The two sources yielded similar pulse shapes despite having very different neutron energy spectra, validating the robustness of the fits across various neutron energies.

  16. Analysis of the scintillation mechanism in a pressurized 4He fast neutron detector using pulse shape fitting

    International Nuclear Information System (INIS)

    An empirical investigation of the scintillation mechanism in a pressurized 4He gas fast neutron detector was conducted using pulse shape fitting. Scintillation signals from neutron interactions were measured and averaged to produce a single generic neutron pulse shape from both a 252Cf spontaneous fission source and a (d,d) neutron generator. An expression for light output over time was then developed by treating the decay of helium excited states in the same manner as the decay of radioactive isotopes. This pulse shape expression was fitted to the measured neutron pulse shape using a least-squares optimization algorithm, allowing an empirical analysis of the mechanism of scintillation inside the 4He detector. A further understanding of this mechanism in the 4He detector will advance the use of this system as a neutron spectrometer. For 252Cf neutrons, the triplet and singlet time constants were found to be 970 ns and 686 ns, respectively. For neutrons from the (d,d) generator, the time constants were found to be 884 ns and 636 ns. Differences were noted in the magnitude of these parameters compared to previously published data, however the general relationships were noted to be the same and checked with expected trends from theory. Of the excited helium states produced from a 252Cf neutron interaction, 76% were found to be born as triplet states, similar to the result from the neutron generator of 71%. The two sources yielded similar pulse shapes despite having very different neutron energy spectra, validating the robustness of the fits across various neutron energies

  17. Conceptual designs of two petawatt-class pulsed-power accelerators for high-energy-density-physics experiments

    Science.gov (United States)

    Stygar, W. A.; Awe, T. J.; Bailey, J. E.; Bennett, N. L.; Breden, E. W.; Campbell, E. M.; Clark, R. E.; Cooper, R. A.; Cuneo, M. E.; Ennis, J. B.; Fehl, D. L.; Genoni, T. C.; Gomez, M. R.; Greiser, G. W.; Gruner, F. R.; Herrmann, M. C.; Hutsel, B. T.; Jennings, C. A.; Jobe, D. O.; Jones, B. M.; Jones, M. C.; Jones, P. A.; Knapp, P. F.; Lash, J. S.; LeChien, K. R.; Leckbee, J. J.; Leeper, R. J.; Lewis, S. A.; Long, F. W.; Lucero, D. J.; Madrid, E. A.; Martin, M. R.; Matzen, M. K.; Mazarakis, M. G.; McBride, R. D.; McKee, G. R.; Miller, C. L.; Moore, J. K.; Mostrom, C. B.; Mulville, T. D.; Peterson, K. J.; Porter, J. L.; Reisman, D. B.; Rochau, G. A.; Rochau, G. E.; Rose, D. V.; Rovang, D. C.; Savage, M. E.; Sceiford, M. E.; Schmit, P. F.; Schneider, R. F.; Schwarz, J.; Sefkow, A. B.; Sinars, D. B.; Slutz, S. A.; Spielman, R. B.; Stoltzfus, B. S.; Thoma, C.; Vesey, R. A.; Wakeland, P. E.; Welch, D. R.; Wisher, M. L.; Woodworth, J. R.

    2015-11-01

    We have developed conceptual designs of two petawatt-class pulsed-power accelerators: Z 300 and Z 800. The designs are based on an accelerator architecture that is founded on two concepts: single-stage electrical-pulse compression and impedance matching [Phys. Rev. ST Accel. Beams 10, 030401 (2007)]. The prime power source of each machine consists of 90 linear-transformer-driver (LTD) modules. Each module comprises LTD cavities connected electrically in series, each of which is powered by 5-GW LTD bricks connected electrically in parallel. (A brick comprises a single switch and two capacitors in series.) Six water-insulated radial-transmission-line impedance transformers transport the power generated by the modules to a six-level vacuum-insulator stack. The stack serves as the accelerator's water-vacuum interface. The stack is connected to six conical outer magnetically insulated vacuum transmission lines (MITLs), which are joined in parallel at a 10-cm radius by a triple-post-hole vacuum convolute. The convolute sums the electrical currents at the outputs of the six outer MITLs, and delivers the combined current to a single short inner MITL. The inner MITL transmits the combined current to the accelerator's physics-package load. Z 300 is 35 m in diameter and stores 48 MJ of electrical energy in its LTD capacitors. The accelerator generates 320 TW of electrical power at the output of the LTD system, and delivers 48 MA in 154 ns to a magnetized-liner inertial-fusion (MagLIF) target [Phys. Plasmas 17, 056303 (2010)]. The peak electrical power at the MagLIF target is 870 TW, which is the highest power throughout the accelerator. Power amplification is accomplished by the centrally located vacuum section, which serves as an intermediate inductive-energy-storage device. The principal goal of Z 300 is to achieve thermonuclear ignition; i.e., a fusion yield that exceeds the energy transmitted by the accelerator to the liner. 2D magnetohydrodynamic (MHD) simulations

  18. Synchronization method of digital pulse power supply for heavy ions accelerator in Lanzhou

    International Nuclear Information System (INIS)

    The performance of the synchrotron depends on its synchronization. A kind of synchronization method of digital pulse power supply in Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring (HIRFL-CSR) was presented in detail, which is a kind of system on a programmable chip (SOPC) based on optical fiber and optical-custom component. The test of the digital power supply was performed and the current wave forms of pulse mode were given. The results show that all targets can meet the design requirements. (authors)

  19. Angular spectrum approach for fast simulation of pulsed non-linear ultrasound fields

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2011-01-01

    The paper presents an Angular Spectrum Approach (ASA) for simulating pulsed non-linear ultrasound fields. The source of the ASA is generated by Field II, which can simulate array transducers of any arbitrary geometry and focusing. The non-linear ultrasound simulation program - Abersim, is used...... as the reference. A linear array transducer with 64 active elements is simulated by both Field II and Abersim. The excitation is a 2-cycle sine wave with a frequency of 5 MHz. The second harmonic field in the time domain is simulated using ASA. Pulse inversion is used in the Abersim simulation to remove...... the fundamental and keep the second harmonic field, since Abersim simulates non-linear fields with all harmonic components. ASA and Abersim are compared for the pulsed fundamental and second harmonic fields in the time domain at depths of 30 mm, 40 mm (focal depth) and 60 mm. Full widths at -6 dB (FWHM) are f0...

  20. Fast Electron Transfer Exchange at Self-Assembled Monolayers of Organometallic Ruthenium(II) σ-Arylacetylide Complexes.

    Science.gov (United States)

    Mulas, Andrea; Hervault, Yves-Marie; He, Xiaoyan; Di Piazza, Emmanuel; Norel, Lucie; Rigaut, Stéphane; Lagrost, Corinne

    2015-06-30

    A new series of ruthenium organometallic carbon-rich complexes, exhibiting fast electron transfer kinetics combined to a low oxidation potential, was synthesized for self-assembled monolayer (SAM) formation on gold surfaces. The molecules consist of highly conjugated ruthenium(II) mono(σ-arylacetylide) or bis(σ-arylacetylide) complexes functionalized with different bridge units with specific (protected) anchoring groups that possess high affinity for gold, such as thiol, carbodithioate, and isocyanide. Single component and mixed SAMs were prepared and fully characterized by wettability studies, infrared reflection absorption spectroscopy (IRRAS), X-ray photoelectron spectroscopy (XPS), and electrochemical analyses. By applying the Laviron's formalism, fast electron transfer kinetics (≈10(4) s(-1)) were found at the derived self-assemblies while no significant effect could have been evidenced with variation of the bridging unit and of the anchoring moiety. Interestingly, a hexyl aliphatic spacer in the bridging unit with a thiol group and dilution with suitable nonelectroactive thiols lead to better SAM organization and packing, in comparison with undiluted complexes with shorter spacers. Such features make these compounds suitable alternatives to the widely used ferrocene center as redox-active building blocks for reversible charge storage devices. PMID:26053314

  1. Design of an Ultra-Low Noise Analogue Front-End for Fast Voltage Pulses Measurement

    CERN Document Server

    AUTHOR|(SzGeCERN)712364; Arpaia, Pasquale; Cerqueira Bastos, Miguel; Martino, Michele

    2015-01-01

    A 15MS/s, 10 ppm repeatable acquisition system to characterize 3 μs rise-time trapezoidal voltage pulses is proposed. The system is based mainly on a low-noise, 5MHz bandwidth analog front-end. In this paper, the requirements, the concept and physical design are illustrated. Simulation results aimed at assessing the circuit performance are presented. An experimental case study on the characterization of a pulsed power supply for the klystrons modulators of the Compact Linear Collider (CLIC) under study at CERN is reported. In particular, the experimental metrological characterization of the prototype in terms of bandwidth and noise is presented.

  2. FAST TRACK COMMUNICATION: Selective inactivation of human immunodeficiency virus with subpicosecond near-infrared laser pulses

    Science.gov (United States)

    Tsen, K. T.; Tsen, Shaw-Wei D.; Hung, Chien-Fu; Wu, T.-C.; Kiang, Juliann G.

    2008-06-01

    We demonstrate for the first time that human immunodeficiency virus (HIV) can be inactivated by irradiation with subpicosecond near-infrared laser pulses at a moderate laser power density. By comparing the threshold laser power density for the inactivation of HIV with those of human red blood cells and mouse dendritic cells, we conclude that it is plausible to use the ultrashort pulsed laser to selectively inactivate blood-borne pathogens such as HIV while leaving sensitive materials like human red blood cells unharmed. This finding has important implications in the development of a new laser technology for disinfection of viral pathogens in blood products and in the clinic.

  3. A new coding concept for fast ultrasound imaging using pulse trains

    DEFF Research Database (Denmark)

    Misaridis, T.; Jensen, Jørgen Arendt

    2002-01-01

    Frame rate in ultrasound imaging can he increased by simultaneous transmission of multiple beams using coded waveforms. However, the achievable degree of orthogonality among coded waveforms is limited in ultrasound, and the image quality degrades unacceptably due to interbeam interference....... In this paper, an alternative combined time-space coding approach is undertaken. In the new method all transducer elements are excited with short pulses and the high time-bandwidth (TB) product waveforms are generated acoustically. Each element transmits a short pulse spherical wave with a constant transmit...

  4. Searches for Radio Pulsars & Fast Transients and Multiwavelength Studies of Single-pulse Emission

    Science.gov (United States)

    Mickaliger, Mitchell B.

    Pulsars are excellent tools for studying a wide array of astrophysical phenomena (e.g. gravitational waves, the interstellar medium, general relativity), yet they are still not fully understood. What are their emission processes and how do they change at different energies? How is giant pulse emission different from regular emission? How are different classes of pulsars (RRATs, magnetars, nulling pulsars, etc.) related? Answering these questions will not only help us to understand pulsars in general, but will also help improve techniques for pulsar searches and timing, gravitational wave searches, and single-pulse searches. The work we present here aims to answer these questions through studies of giant pulse emission, the discovery of new pulsars, and single-pulse studies of a large population of pulsars and RRATs. We took advantage of open telescope time on the 43-m telescope in Green Bank, WV to conduct a long-term study of giant pulses from the Crab pulsar at 1.2 GHz and 330 MHz. Over a timespan of 15 months, we collected a total of 95000 giant pulses which we correlated with both gamma-ray photons from the Fermi satellite and giant pulses collected at 8.9 GHz. Statistics of these pulses show that their amplitudes follow power-law distributions, with indices in the range of 2.1 to 3.1. The correlation with giant pulses at 8.9 GHz showed that the emission processes at 1.2 GHz and 8.9 GHz are related, despite significant profile differences. The correlation with Fermi gamma-ray photons was to test if increased pair production in the magnetosphere was the cause of giant pulses. Our findings suggest that, while it may play a role, increased pair production is not the dominant cause of giant pulses. As part of a single-pulse study, we reprocessed the archival Parkes Multibeam Pulsar Survey, discovering six previously unknown pulsars. PSR J0922-52 has a period of 9.68 ms and a DM of 122.4 pc cm-3. PSR J1147-66 has a period of 3.72 ms and a DM of 133.8 pc cm-3. PSR J

  5. Beam dynamics of the Neutralized Drift Compression Experiment-II (NDCX-II), a novel pulse-compressing ion accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, A; Barnard, J J; Cohen, R H; Grote, D P; Lund, S M; Sharp, W M; Faltens, A; Henestroza, E; Jung, J; Kwan, J W; Lee, E P; Leitner, M A; Logan, B G; Vay, J; Waldron, W L; Davidson, R C; Dorf, M; Gilson, E P; Kaganovich, I

    2009-11-19

    Intense beams of heavy ions are well suited for heating matter to regimes of emerging interest. A new facility, NDCX-II, will enable studies of warm dense matter at {approx}1 eV and near-solid density, and of heavy-ion inertial fusion target physics relevant to electric power production. For these applications the beam must deposit its energy rapidly, before the target can expand significantly. To form such pulses, ion beams are temporally compressed in neutralizing plasma; current amplification factors of {approx}50-100 are routinely obtained on the Neutralized Drift Compression Experiment (NDCX) at LBNL. In the NDCX-II physics design, an initial non-neutralized compression renders the pulse short enough that existing high-voltage pulsed power can be employed. This compression is first halted and then reversed by the beam's longitudinal space-charge field. Downstream induction cells provide acceleration and impose the head-to-tail velocity gradient that leads to the final neutralized compression onto the target. This paper describes the discrete-particle simulation models (1-D, 2-D, and 3-D) employed and the space-charge-dominated beam dynamics being realized.

  6. Beam dynamics of the Neutralized Drift Compression Experiment-II (NDCX-II),a novel pulse-compressing ion accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, A.; Barnard, J.J.; Cohen, R.H.; Grote, D.P.; Lund, S.M.; Sharp, W.M.; Faltens, A.; Henestroza, E.; Jung, J.-Y.; Kwan, J.W.; Lee, E.P.; Leitner, M.A.; Logan, B.G.; Vay, J.-L.; Waldron, W.L.; Davidson, R.C.; Dorf, M.; Gilson, E.P.; Kaganovich, I.D.

    2009-12-19

    Intense beams of heavy ions are well suited for heating matter to regimes of emerging interest. A new facility, NDCX-II, will enable studies of warm dense matter at {approx}1 eV and near-solid density, and of heavy-ion inertial fusion target physics relevant to electric power production. For these applications the beam must deposit its energy rapidly, before the target can expand significantly. To form such pulses, ion beams are temporally compressed in neutralizing plasma; current amplification factors of {approx}50-100 are routinely obtained on the Neutralized Drift Compression Experiment (NDCX) at LBNL. In the NDCX-II physics design, an initial non-neutralized compression renders the pulse short enough that existing high-voltage pulsed power can be employed. This compression is first halted and then reversed by the beam's longitudinal space-charge field. Downstream induction cells provide acceleration and impose the head-to-tail velocity gradient that leads to the final neutralized compression onto the target. This paper describes the discrete-particle simulation models (1-D, 2-D, and 3-D) employed and the space-charge-dominated beam dynamics being realized.

  7. Radio frequency pulse compression experiments at SLAC (Stanford Linear Accelerator Center)

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Miller, R.H.; Nantista, C.; Spalek, G.; Wilson, P.B.

    1991-01-01

    Proposed future positron-electron linear colliders would be capable of investigating fundamental processes of interest in the 0.5--5 TeV beam-energy range. At the SLAC Linear Collider (SLC) gradient of about 20 MV/m this would imply prohibitive lengths of about 50--250 kilometers per linac. We can reduce the length by increasing the gradient but this implies high peak power, on the order of 400-- to 1000-MW at X-Band. One possible way to generate high peak power is to generate a relatively long pulse at a relatively low power and compress it into a short pulse with higher peak power. It is possible to compress before DC to RF conversion, as is done using magnetic switching for induction linacs, or after DC to RF conversion, as is done for the SLC. Using RF pulse compression it is possible to boost the 50-- to 100-MW output that has already been obtained from high-power X-Band klystrons the levels required by the linear colliders. In this note only radio frequency pulse compression (RFPC) is considered.

  8. A Heterogeneous Accelerated Matrix Multiplication: OpenCL + APU + GPU+ Fast Matrix Multiply

    OpenAIRE

    D'Alberto, Paolo

    2012-01-01

    As users and developers, we are witnessing the opening of a new computing scenario: the introduction of hybrid processors into a single die, such as an accelerated processing unit (APU) processor, and the plug-and-play of additional graphics processing units (GPUs) onto a single motherboard. These APU processors provide multiple symmetric cores with their memory hierarchies and an integrated GPU. Moreover, these processors are designed to work with external GPUs that can push the peak perform...

  9. Does Abdominal Obesity Accelerate the Effect of Hypertriglyceridemia on Impaired Fasting Glucose?

    OpenAIRE

    Lee, Soojin; Chun, Kihong; Lee, Soonyoung; Kim, Daejung

    2010-01-01

    Purpose This study sought to determine whether abdominal obesity is a risk factor for impaired fasting glucose (IFG) and hypertriglyceridemia and to verify whether moderate effect of abdominal obesity on the relationship between IFG and hypertriglyceridemia in Korea. Materials and Methods Data from the Korean National Health and Nutrition Examination Survey was used for the analysis. The study population included 5,938 subjects aged 20 year old drawn from non-diabetic participants in a health...

  10. Impact of Pre-Plasma on Fast Electron Generation and Transport from Short Pulse High Intensity Lasers

    Science.gov (United States)

    Peebles, J.; McGuffey, C.; Krauland, C.; Jarrott, L. C.; Sorokovikova, A.; Qiao, B.; Krasheninnikov, S.; Beg, F. N.; Wei, M. S.; Park, J.; Link, A.; Chen, H.; McLean, H. S.; Wagner, C.; Minello, V.; McCary, E.; Meadows, A.; Spinks, M.; Gaul, E.; Dyer, G.; Hegelich, B. M.; Martinez, M.; Donovan, M.; Ditmire, T.

    2014-10-01

    We present the results and analysis from recent short pulse laser matter experiments using the Texas Petawatt Laser to study the impact of pre-plasma on fast electron generation and transport. The experimental setup consisted of 3 separate beam elements: a main, high intensity, short pulse beam for the interaction, a secondary pulse of equal intensity interacting with a separate thin foil target to generate protons for side-on proton imaging and a third, low intensity, wider beam to generate a varied scale length pre-plasma. The main target consisted of a multilayer planar Al foil with a buried Cu fluor layer. The electron beam was characterized with multiple diagnostics, including several bremsstrahlung spectrometers, magnetic electron spectrometers and Cu-K α imaging. The protons from the secondary target were used to image the fields on the front of the target in the region of laser plasma interaction. Features seen in the interaction region by these protons will be presented along with characteristics of the generated electron beam. This work performed under the auspices of the US DOE under Contracts DE-FOA-0000583 (FES, NNSA).

  11. Fast beating null strip during the reflection of pulsed Gaussian beams incident at the Rayleigh angle.

    Science.gov (United States)

    Declercq, Nico F

    2006-12-22

    It is well known that harmonic bounded Gaussian beams undergo a transformation into two bounded beams upon reflection on a solid immersed in a liquid. The effect is known as the Schoch effect and can be found at the Rayleigh angle for thick plates and at the different Lamb angles for thin plates. Here, a study is made on the effect of pulsed Gaussian beams reflected on solids. It is found experimentally that the Rayleigh wave phenomenon still generates two reflected bounded beams, whereas Lamb wave phenomena do not generate this effect. This fact may be explained intuitively by realizing that the Rayleigh phenomenon is a coincidental phenomenon that is generated in situ, whereas the Lamb wave phenomenon is a non-coincidental phenomenon that is generated only after incident sound is influenced by both sides of a thin plate. Another explanation is the fact that Rayleigh waves are not dispersive, whereas stimulation and propagation of Lamb waves is frequency dependent. A pulse contains many frequencies and therefore only a fraction of the incident pulse is transformed into a Lamb wave. In this paper, numerical simulations are performed that show that actually the Schoch effect does occur neither for Rayleigh waves, nor for Lamb waves. As a matter of fact, a pulse, incident at the Rayleigh angle, generates two reflected lobes with a null zone of a different kind. The null zone is beating several times during the passage of each pulse. This results in a 'null zone' having a lower mean intensity than any of the two lobes, still less outspoken than for the case of harmonic incident bounded beams. This effect does only occur for Rayleigh wave generation and is much less outspoken for Lamb wave generation. PMID:16815510

  12. FAST

    DEFF Research Database (Denmark)

    Zuidmeer-Jongejan, Laurian; Fernandez-Rivas, Montserrat; Poulsen, Lars K.;

    2012-01-01

    ABSTRACT: The FAST project (Food Allergy Specific Immunotherapy) aims at the development of safe and effective treatment of food allergies, targeting prevalent, persistent and severe allergy to fish and peach. Classical allergen-specific immunotherapy (SIT), using subcutaneous injections...... with aqueous food extracts may be effective but has proven to be accompanied by too many anaphylactic side-effects. FAST aims to develop a safe alternative by replacing food extracts with hypoallergenic recombinant major allergens as the active ingredients of SIT. Both severe fish and peach allergy are caused...... by a single major allergen, parvalbumin (Cyp c 1) and lipid transfer protein (Pru p 3), respectively. Two approaches are being evaluated for achieving hypoallergenicity, i.e. site-directed mutagenesis and chemical modification. The most promising hypoallergens will be produced under GMP conditions. After pre...

  13. Helium-3 and Helium-4 acceleration by high power laser pulses for hadron therapy

    CERN Document Server

    Bulanov, S S; Schroeder, C B; Leemans, W P; Bulanov, S V; Margarone, D; Korn, G; Haberer, T

    2015-01-01

    The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (Magnetic Vortex Acceleration and hole-boring Radiation Pressure Acceleration) of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He3 ions, having almost the same penetration depth as He4 with the ...

  14. Pulsed Laser Annealing of Thin Films of Self-Assembled Nanocrystals

    KAUST Repository

    Baumgardner, William J.

    2011-09-27

    We investigated how pulsed laser annealing can be applied to process thin films of colloidal nanocrystals (NCs) into interconnected nanostructures. We illustrate the relationship between incident laser fluence and changes in morphology of PbSe NC films relative to bulk-like PbSe films. We found that laser pulse fluences in the range of 30 to 200 mJ/cm2 create a processing window of opportunity where the NC film morphology goes through interesting transformations without large-scale coalescence of the NCs. NC coalescence can be mitigated by depositing a thin film of amorphous silicon (a-Si) on the NC film. Remarkably, pulsed laser annealing of the a-Si/PbSe NC films crystallized the silicon while NC morphology and translational order of the NC film are preserved. © 2011 American Chemical Society.

  15. MeV femtosecond electron pulses from direct-field acceleration in low density atomic gases

    CERN Document Server

    Varin, Charles; Hogan-Lamarre, Pascal; Fennel, Thomas; Piché, Michel; Brabec, Thomas

    2015-01-01

    Using three-dimensional particle-in-cell simulations, we show that few-MeV electrons can be produced by focusing tightly few-cycle radially-polarized laser pulses in a low-density atomic gas. In particular, it is observed that for the few-TW laser power needed to reach relativistic electron energies, longitudinal attosecond microbunching occurs naturally, resulting in femtosecond structures with high-contrast attosecond density modulations. The three-dimensional particle-in-cell simulations show that in the relativistic regime the leading pulse of these attosecond substructures survives to propagation over extended distances, suggesting that it could be delivered to a distant target, with the help of a properly designed transport beamline.

  16. Entanglement and dynamics of spin chains in periodically pulsed magnetic fields: accelerator modes

    OpenAIRE

    Boness, T.; Bose, S.; Monteiro, T.

    2006-01-01

    We study the dynamics of a single excitation in a Heisenberg spin-chain subjected to a sequence of periodic pulses from an external, parabolic, magnetic field. We show that, for experimentally reasonable parameters, a pair of counter-propagating coherent states are ejected from the centre of the chain. We find an illuminating correspondence with the quantum time evolution of the well-known paradigm of quantum chaos, the Quantum Kicked Rotor (QKR). From this we can analyse the entanglement pro...

  17. Fast Two-Dimensional NMR Spectroscopy of High Molecular Weight Protein Assemblies

    International Nuclear Information System (INIS)

    An optimized NMR experiment that combines the advantages of methyl-TROSY and SOFAST-HMQC has been developed. It allows the recording of high quality methyl 1H-13C correlation spectra of protein assemblies of several hundreds of kDa in a few seconds. The SOFAST-methyl-TROSY-based experiment offers completely new opportunities for the study of structural and dynamic changes occurring in molecular nano-machines while they perform their biological function in vitro. (authors)

  18. Technologies for the Fast Set-Up of Automated Assembly Processes

    DEFF Research Database (Denmark)

    Krüger, Norbert; Ude, Ales; Petersen, Henrik Gordon;

    2014-01-01

    In this article, we describe technologies facilitating the set-up of automated assembly solutions which have been developed in the context of the IntellAct project (2011–2014). Tedious procedures are currently still required to establish such robot solutions. This hinders especially the automatio...... work on tele-operation, dexterous grasping, pose estimation and learning of control strategies. The prototype developed in IntellAct is at a TRL4 (corresponding to ‘demonstration in lab environment’)....

  19. Hysteresis in Lanthanide Aluminum Oxides Observed by Fast Pulse CV Measurement

    Directory of Open Access Journals (Sweden)

    Chun Zhao

    2014-10-01

    Full Text Available Oxide materials with large dielectric constants (so-called high-k dielectrics have attracted much attention due to their potential use as gate dielectrics in Metal Oxide Semiconductor Field Effect Transistors (MOSFETs. A novel characterization (pulse capacitance-voltage method was proposed in detail. The pulse capacitance-voltage technique was employed to characterize oxide traps of high-k dielectrics based on the Metal Oxide Semiconductor (MOS capacitor structure. The variation of flat-band voltages of the MOS structure was observed and discussed accordingly. Some interesting trapping/detrapping results related to the lanthanide aluminum oxide traps were identified for possible application in Flash memory technology. After understanding the trapping/detrapping mechanism of the high-k oxides, a solid foundation was prepared for further exploration into charge-trapping non-volatile memory in the future.

  20. Pulse radiolysis of fast reactions in molecular systems. Progress report, November 1979-September 1980

    International Nuclear Information System (INIS)

    The rates of elementary chemical reactions in irradiated solutions are being studied by observation of reactive intermediates using the pulse radiolysis technique. Optical absorption spectra of these transient species, which determine the course of the chemistry, are being obtained. The types of reactive species currently of interest are organic molecule ions (both cations and anions) and radical ions, and transition metal carbonyl radicals in solution. Since reaction is initiated by a pulse of high energy electrons, our investigations inherently relate to radiation chemical systems. The information obtained is, however, also of interest in various areas of organic reaction kinetics in which ionic species are known to play a central role. The rectivity of the transition metal carbonyl radicals is of interest in the area of homogeneous catalysis. Current activities involve: spectra and reactivities of transition metal carbonyl radicals of the type M(CO)5; reactivity of organic ionic species (including carbocations and carbanions) in irradiated solutions

  1. Pulse radiolysis studies of fast reactions in molecular systems. Progress report, November 1979-September 1980

    International Nuclear Information System (INIS)

    The rates of elementary chemical reactions in irradiated solutions are being studied by observation of reactive intermediates using the pulse radiolysis technique. Optical absorption spectra of these transient species, which determine the course of the chemistry, are being obtained. The types of reactive species currently of interest are organic molecule ions (both cations and anions) and radical ions, and transition metal carbonyl radicals in solution. Since reaction is initiated by a pulse of high energy electrons, our investigations inherently relate to radiation chemical systems. The information obtained is, however, also of interest in various areas of organic reaction kinetics in which ionic species are known to play a central role. The reactivity of the transition metal carbonyl radicals is of interest in the area of homogeneous catalysis. Current activities involve: spectra and reactivities of transition metal carbonyl radicals of the type M(CO)5; reactivity of organic ionic species (including carbocations and carbanions) in irradiated solutions

  2. Ultra-intense, short pulse laser-plasma interactions with applications to the fast ignitor

    International Nuclear Information System (INIS)

    Due to the advent of chirped pulse amplification (CPA) as an efficient means of creating ultra-high intensity laser light (I > 5x1017 W/cm2) in pulses less than a few picoseconds, new ideas for achieving ignition and gain in DT targets with less than 1 megajoule of input energy are currently being pursued. Two types of powerful lasers are employed in this scheme: (1) channeling beams and (2) ignition beams. The current state of laser-plasma interactions relating to this fusion scheme will be discussed. In particular, plasma physics issues in the ultra-intense regime are crucial to the success of this scheme. We compare simulation and experimental results in this highly nonlinear regime

  3. Effect of Inductive Coil Geometry and Current Sheet Trajectory of a Conical Theta Pinch Pulsed Inductive Plasma Accelerator

    Science.gov (United States)

    Hallock, Ashley K.; Polzin, Kurt A.; Bonds, Kevin W.; Emsellem, Gregory D.

    2011-01-01

    Results are presented demonstrating the e ect of inductive coil geometry and current sheet trajectory on the exhaust velocity of propellant in conical theta pinch pulsed induc- tive plasma accelerators. The electromagnetic coupling between the inductive coil of the accelerator and a plasma current sheet is simulated, substituting a conical copper frustum for the plasma. The variation of system inductance as a function of plasma position is obtained by displacing the simulated current sheet from the coil while measuring the total inductance of the coil. Four coils of differing geometries were employed, and the total inductance of each coil was measured as a function of the axial displacement of two sep- arate copper frusta both having the same cone angle and length as the coil but with one compressed to a smaller size relative to the coil. The measured relationship between total coil inductance and current sheet position closes a dynamical circuit model that is used to calculate the resulting current sheet velocity for various coil and current sheet con gura- tions. The results of this model, which neglects the pinching contribution to thrust, radial propellant con nement, and plume divergence, indicate that in a conical theta pinch ge- ometry current sheet pinching is detrimental to thruster performance, reducing the kinetic energy of the exhausting propellant by up to 50% (at the upper bound for the parameter range of the study). The decrease in exhaust velocity was larger for coils and simulated current sheets of smaller half cone angles. An upper bound for the pinching contribution to thrust is estimated for typical operating parameters. Measurements of coil inductance for three di erent current sheet pinching conditions are used to estimate the magnetic pressure as a function of current sheet radial compression. The gas-dynamic contribution to axial acceleration is also estimated and shown to not compensate for the decrease in axial electromagnetic acceleration

  4. 120 Hz pulse tube cryocooler for fast cooldown to 50 K

    NARCIS (Netherlands)

    Vanapalli, Srinivas; Lewis, Michal; Gan, Zhihua; Radebaugh, Ray

    2007-01-01

    A pulse tube cryocooler operating at 120 Hz with 3.5 MPa average pressure achieved a no-load temperature of about 49.9 K and a cooldown time to 80 K of 5.5 min. The net refrigeration power at 80 K was 3.35 W with an efficiency of 19.7% of Carnot when referred to input pressure-volume (PV or a

  5. Measurements of the Physics Characteristics of the Fast Pulsed Reactor, VIPER

    International Nuclear Information System (INIS)

    The VIPER pulsed reactor was first made critical on 26 May 1967. The physics measurements carried out during its subsequent commissioning to prompt critical are described. These experiments include the measurement of reaction rate distributions, perturbation effects, neutron spectrum, neutron lifetime, and prompt temperature coefficients of reactivity. The measured characteristics of prompt critical transients are compared with predictions based on calculated expansion and Doppler effects. (author)

  6. Ultra-fast pulsed microwave plasma breakdown: evidence of various ignition modes

    Science.gov (United States)

    Carbone, Emile; Nijdam, Sander

    2014-02-01

    In this communication, we investigate the ignition of pulsed microwave plasmas in a narrow dielectric tube with an electrodeless configuration. The plasma is generated using a surfatron cavity. The power is modulated as a square wave with a rise-time of 30 ns at variable frequencies from 100 Hz up to 5 MHz. The ignition and plasma propagation inside the 3 mm radius quartz tube are imaged spatially and resolved with nanosecond time resolution using an iCCD camera. The plasma is found to propagate in the form of a front moving from the launcher to the end of the plasma column with the microwave power being gradually absorbed behind it. The velocity of the plasma front decreases while the plasma goes towards a steady state. The ionization front is found to be strongly non-uniform and various structures as a function of the pulse repetition frequency (i.e. power-off time) are shown in the axial and radial directions. At low frequencies, finger-like structures are found. The plasma becomes more hollow at smaller power-off times. At higher repetition frequencies (kHz regime), a critical repetition frequency is found for which the plasma light intensity sharply increases at the head of the propagation front, taking a shape resembling a plasma bullet. This critical frequency depends on the pressure and power. For even higher frequencies, the bullet shape disappears and plasma volume ignition from the launcher to the end of the plasma column is observed. These results bring a new insight into the ignition mechanisms of pulsed microwave plasmas inside dielectric tubes. A wide variety of effects are found which seem to mostly depend on the background ionization degree. Moreover, the results show that only a 3D time-dependent model can, in general, correctly describe the ignition of a pulsed microwave discharge.

  7. Capture and Transport of Laser Accelerated Protons by Pulsed Magnetic Fields: Advancements Toward Laser-Based Proton Therapy

    Science.gov (United States)

    Burris-Mog, Trevor J.

    The interaction of intense laser light (I > 10 18 W/cm2) with a thin target foil leads to the Target Normal Sheath Acceleration mechanism (TNSA). TNSA is responsible for the generation of high current, ultra-low emittance proton beams, which may allow for the development of a compact and cost effective proton therapy system for the treatment of cancer. Before this application can be realized, control is needed over the large divergence and the 100% kinetic energy spread that are characteristic of TNSA proton beams. The work presented here demonstrates control over the divergence and energy spread using strong magnetic fields generated by a pulse power solenoid. The solenoidal field results in a parallel proton beam with a kinetic energy spread DeltaE/E = 10%. Assuming that next generation lasers will be able to operate at 10 Hz, the 10% spread in the kinetic energy along with the 23% capture efficiency of the solenoid yield enough protons per laser pulse to, for the first time, consider applications in Radiation Oncology. Current lasers can generate proton beams with kinetic energies up to 67.5 MeV, but for therapy applications, the proton kinetic energy must reach 250 MeV. Since the maximum kinetic energy Emax of the proton scales with laser light intensity as Emax ∝ I0.5, next generation lasers may very well accelerate 250 MeV protons. As the kinetic energy of the protons is increased, the magnetic field strength of the solenoid will need to increase. The scaling of the magnetic field B with the kinetic energy of the protons follows B ∝ E1/2. Therefor, the field strength of the solenoid presented in this work will need to be increased by a factor of 2.4 in order to accommodate 250 MeV protons. This scaling factor seems reasonable, even with present technology. This work not only demonstrates control over beam divergence and energy spread, it also allows for us to now perform feasibility studies to further research what a laser-based proton therapy system

  8. Demonstration of sub-luminal propagation of single-cycle terahertz pulses for particle acceleration

    CERN Document Server

    Walsh, D A; Snedden, E W; Cliffe, M J; Graham, D M; Jamison, S P

    2016-01-01

    The sub-luminal phase velocity of electromagnetic waves in free space is generally unobtainable, being closely linked to forbidden faster than light group velocities. The requirement of effective sub-luminal phase-velocity in laser-driven particle acceleration schemes imposes a fundamental limit on the total acceleration achievable in free-space, and necessitates the use of dielectric structures and waveguides for extending the field-particle interaction. Here we demonstrate a new travelling-source and free space propagation approach to overcoming the sub-luminal propagation limits. The approach exploits the relative ease of generating ultrafast optical sources with slow group velocity propagation, and a group-to-phase front conversion through non-linear optical interaction near a material-vacuum boundary. The concept is demonstrated with two terahertz generation processes, non-linear optical rectification and current-surge rectification. The phase velocity is tunable, both above and below vacuum speed of lig...

  9. Present status and future program of YAYOI as a fast pulse reactor

    International Nuclear Information System (INIS)

    Fast neutron source reactor YAYOI was constructed in 1971 and has been operated by the Faculty of Engineering of the University of Tokyo. The reactor is a development of AFSR and HARMONIE and is air cooled, modified to enhance flexibility for research and training, using 93% enriched uranium metal fuel. The YAYOI is principally used for LMFBR development work. The new features of YAYOI include pulsation with or without an electron linac. (author)

  10. 150 keV accelerator as pulsed neutron source; Acelerador de 150 keV como fuente de neutrones pulsada

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, F.

    1970-07-01

    The project of a 150 keV Cockcroft-Walton accelerator built at J.E.N. is described. Beam currents of more than 10 mA, with a neutron intensity of 10{sup 1}1 n.s{sup 1}, are obtained. Also, we report some research made in connection with that project. The role of the contamination in the vacuum system and the performance of the pumps and gauges pumping deuterium gas are studied. Sinusoidal pulses are employed as an analysis method of the discharge in the ion source and the performance of the extracting-focusing system. The parameters of the beam leaving the ion source have been determined; these are used to calculate the electrostatic lenses with the gaussian optics. Measurements concerning deuterium and tritium targets as neutron sources have been made and the processes affecting their practical service life are analyzed. (Author) 71 refs.

  11. Mechanism of self-reinforcing YORP acceleration for fast-rotating asteroids

    Science.gov (United States)

    Statler, T.; Richardson, D.; Walsh, K.; Yu, Y.; Michel, P.

    2014-07-01

    The YORP effect is an important process that directly alters the spin states, and indirectly alters the orbits, of small Solar System bodies. It has been suggested that YORP may be able simultaneously to account for the high fraction of binaries among the near-Earth-asteroid (NEA) population, the frequent radar detections of objects shaped like child's tops, and the abundance of top-shaped asteroids with binary companions. In a compelling demonstration, Walsh et al. (2008, Nature 454, 188) simulated the evolution of idealized, gravitationally bound rubble piles, to which they continually added angular momentum. The centrifugal force caused material to move from mid-latitudes toward the equator, generating the characteristic top shape. Continued spin-up caused the equatorial ridge to shed material, which reaccreted in orbit to form a binary companion. But this mechanism rests on the assumption that YORP will provide all the angular momentum needed to form axisymmetric tops, accelerate them to the mass-shedding limit, and drive enough mass into orbit to form an observable companion. This assumption is problematic, as a truly axisymmetic body would experience no YORP effect at all, and small surface changes on an object with approximate large-scale axisymmetry can easily change the sign of the torque and decelerate the spin (Statler 2009, Icarus 202, 502). So the search is on for a mechanism that can ensure a continual increase in angular momentum to overcome the stochastic effect of topographic changes. One intriguing suggestion is ''tangential YORP'' (Golubov and Krugly 2012, ApJL 752, L11), which arises from asymmetric east-west heat conduction across small exposed structures, and always produces an eastward torque. But tangential YORP relies on structures at a preferred size scale, which shrinks to millimeters as the rotation rate approaches periods of a few hours. How the effects generated at these tiny scales are diluted by the mesoscale (meters to hectometers

  12. A Heterogeneous Accelerated Matrix Multiplication: OpenCL + APU + GPU+ Fast Matrix Multiply

    CERN Document Server

    D'Alberto, Paolo

    2012-01-01

    As users and developers, we are witnessing the opening of a new computing scenario: the introduction of hybrid processors into a single die, such as an accelerated processing unit (APU) processor, and the plug-and-play of additional graphics processing units (GPUs) onto a single motherboard. These APU processors provide multiple symmetric cores with their memory hierarchies and an integrated GPU. Moreover, these processors are designed to work with external GPUs that can push the peak performance towards the TeraFLOPS boundary. We present a case study for the development of dense Matrix Multiplication (MM) codes for matrix sizes up to 19K\\times19K, thus using all of the above computational engines, and an achievable peak performance of 200 GFLOPS for, literally, a made- at-home built. We present the results of our experience, the quirks, the pitfalls, the achieved performance, and the achievable peak performance.

  13. D-Cluster Converter Foil for Laser-Accelerated Deuteron Beams: Towards Deuteron-Beam-Driven Fast Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Miley, George H.

    2012-10-24

    Fast Ignition (FI) uses Petawatt laser generated particle beam pulse to ignite a small volume called a pre-compressed Inertial Confinement Fusion (ICF) target, and is the favored method to achieve the high energy gain per target burn needed for an attractive ICF power plant. Ion beams such as protons, deuterons or heavier carbon ions are especially appealing for FI as they have relative straight trajectory, and easier to focus on the fuel capsule. But current experiments have encountered problems with the 'converter-foil' which is irradiated by the Petawatt laser to produce the ion beams. The problems include depletion of the available ions in the convertor foils, and poor energy efficiency (ion beam energy/ input laser energy). We proposed to develop a volumetrically-loaded ultra-high-density deuteron deuterium cluster material as the basis for converter-foil for deuteron beam generation. The deuterons will fuse with the ICF DT while they slow down, providing an extra 'bonus' energy gain in addition to heating the hot spot. Also, due to the volumetric loading, the foil will provide sufficient energetic deuteron beam flux for 'hot spot' ignition, while avoiding the depletion problem encountered by current proton-driven FI foils. After extensive comparative studies, in Phase I, high purity PdO/Pd/PdO foils were selected for the high packing fraction D-Cluster converter foils. An optimized loading process has been developed to increase the cluster packing fraction in this type of foil. As a result, the packing fraction has been increased from 0.1% to 10% - meeting the original Phase I goal and representing a significant progress towards the beam intensities needed for both FI and pulsed neutron applications. Fast Ignition provides a promising approach to achieve high energy gain target performance needed for commercial Inertial Confinement Fusion (ICF). This is now a realistic goal for near term in view of the anticipated ICF target burn

  14. Interfacial Fast Release Layer in Monodisperse Poly (lactic-co-glycolic acid) Microspheres Accelerates the Drug Release.

    Science.gov (United States)

    Wu, Jun; Zhao, Xiaoli; Yeung, Kelvin W K; To, Michael K T

    2016-01-01

    Understanding microstructural evolutions of drug delivery devices during drug release process is essential for revealing the drug release mechanisms and controlling the drug release profiles. In this study, monodisperse poly (lactic-co-glycolic acid) microspheres in different diameters were fabricated by microfluidics in order to find out the relationships between the microstructural evolutions and the drug release profiles. It was found that poly (lactic-co-glycolic acid) microspheres underwent significant size expansion which took place from the periphery to the center, resulting in the formation of interfacial fast release layers. At the same time, inner pores were created and the diffusion rate was increased so that the early stage drug release was accelerated. Due to the different expansion rates, small poly (lactic-co-glycolic acid) microspheres tendered to follow homogeneous drug release while large poly (lactic-co-glycolic acid) microspheres tendered to follow heterogeneous drug release. This study suggests that the size expansion and the occurrence of interfacial fast release layer were important mechanisms for early stage drug release of poly (lactic-co-glycolic acid) microspheres.

  15. Stability and fast heat removal with He-II cooling for pulsed superconductive magnets

    International Nuclear Information System (INIS)

    The use of pressurized superfluid helium between 1.6 K and 1.8 K is being considered for a number of superconducting magnet applications. This type of cooling is particularly interesting in the case of pulsed field magnets where large heat fluxes need to be evacuated in a short time. This paper reviews a few recent experiments on heat transport properties and stability in He-II, which contribute to evaluating its potential use for such an application. Present technology is illustrated by the description of a large test facility recently operated at Saclay

  16. Mercury as a target material for pulsed (fast) spallation neutron sources systems

    International Nuclear Information System (INIS)

    For spallation neutron systems which are not adversely affected by the high thermal absorption cross section, mercury seems to be a good target material because it is liquid at ambient temperatures, shows good compatibility with low nickel content steels, has a high neutron yield, is easy to purify and has no truly long lived isotopes. Its performance in an engineered target for pulsed spallation sources is expected to be superior to that of its solid competitors Ta and W and equivalent to that of Pb or Pb-Bi but at much less overall technical effort. (author) 5 figs., 5 tabs., 11 refs

  17. Pulsed ultrasound therapy accelerates the recovery of skeletal muscle damage induced by Bothrops jararacussu venom

    Directory of Open Access Journals (Sweden)

    J. Saturnino-Oliveira

    2012-06-01

    Full Text Available We studied the effect of pulsed ultrasound therapy (UST and antibothropic polyvalent antivenom (PAV on the regeneration of mouse extensor digitorum longus muscle following damage by Bothrops jararacussu venom. Animals (Swiss male and female mice weighing 25.0 ± 5.0 g; 5 animals per group received a perimuscular injection of venom (1 mg/kg and treatment with UST was started 1 h later (1 min/day, 3 MHz, 0.3 W/cm², pulsed mode. Three and 28 days after injection, muscles were dissected and processed for light microscopy. The venom caused complete degeneration of muscle fibers. UST alone and combined with PAV (1.0 mL/kg partially protected these fibers, whereas muscles receiving no treatment showed disorganized fascicules and fibers with reduced diameter. Treatment with UST and PAV decreased the effects of the venom on creatine kinase content and motor activity (approximately 75 and 48%, respectively. Sonication of the venom solution immediately before application decreased the in vivo and ex vivo myotoxic activities (approximately 60 and 50%, respectively. The present data show that UST counteracts some effects of B. jararacussu venom, causing structural and functional improvement of the regenerated muscle after venom injury.

  18. Cell wall assembly and intracellular trafficking in plant cells are directly affected by changes in the magnitude of gravitational acceleration.

    Directory of Open Access Journals (Sweden)

    Youssef Chebli

    Full Text Available Plants are able to sense the magnitude and direction of gravity. This capacity is thought to reside in selected cell types within the plant body that are equipped with specialized organelles called statoliths. However, most plant cells do not possess statoliths, yet they respond to changes in gravitational acceleration. To understand the effect of gravity on the metabolism and cellular functioning of non-specialized plant cells, we investigated a rapidly growing plant cell devoid of known statoliths and without gravitropic behavior, the pollen tube. The effects of hyper-gravity and omnidirectional exposure to gravity on intracellular trafficking and on cell wall assembly were assessed in Camellia pollen tubes, a model system with highly reproducible growth behavior in vitro. Using an epi-fluorescence microscope mounted on the Large Diameter Centrifuge at the European Space Agency, we were able to demonstrate that vesicular trafficking is reduced under hyper-gravity conditions. Immuno-cytochemistry confirmed that both in hyper and omnidirectional gravity conditions, the characteristic spatial profiles of cellulose and callose distribution in the pollen tube wall were altered, in accordance with a dose-dependent effect on pollen tube diameter. Our findings suggest that in response to gravity induced stress, the pollen tube responds by modifying cell wall assembly to compensate for the altered mechanical load. The effect was reversible within few minutes demonstrating that the pollen tube is able to quickly adapt to changing stress conditions.

  19. Laser-induced Bessel beams can realize fast all-optical switching in gold nanosol prepared by pulsed laser ablation

    International Nuclear Information System (INIS)

    We demonstrate the possibility of realizing, all-optical switching in gold nanosol. Two overlapping laser beams are used for this purpose, due to which a low-power beam passing collinear to a high-power beam will undergo cross phase modulation and thereby distort the spatial profile. This is taken to advantage for performing logic operations. We have also measured the threshold pump power to obtain a NOT gate and the minimum response time of the device. Contrary to the general notion that the response time of thermal effects used in this application is of the order of milliseconds, we prove that short pump pulses can result in fast switching. Different combinations of beam splitters and combiners will lead to the formation of other logic functions too.

  20. Very Long Baseline Interferometry Experiment on Giant Radio Pulses of Crab Pulsar toward Fast Radio Burst Detection

    CERN Document Server

    Takefuji, K; Kondo, T; Mikami, R; Takeuchi, H; Misawa, H; Tsuchiya, F; Kita, H; Sekido, M

    2016-01-01

    We report on a very long baseline interferometry (VLBI) experiment on giant radio pulses (GPs) from the Crab pulsar in the radio 1.4 to 1.7 GHz range to demonstrate a VLBI technique for searching for fast radio bursts (FRBs). We carried out the experiment on 26 July 2014 using the Kashima 34 m and Usuda 64 m radio telescopes of the Japanese VLBI Network (JVN) with a baseline of about 200 km. During the approximately 1 h observation, we could detect 35 GPs by high-time-resolution VLBI. Moreover, we determined the dispersion measure (DM) to be 56.7585 +/- 0.0025 on the basis of the mean DM of the 35 GPs detected by VLBI. We confirmed that the sensitivity of a detection of GPs using our technique is superior to that of a single-dish mode detection using the same telescope.

  1. Very Long Baseline Interferometry Experiment on Giant Radio Pulses of Crab Pulsar toward Fast Radio Burst Detection

    Science.gov (United States)

    Takefuji, K.; Terasawa, T.; Kondo, T.; Mikami, R.; Takeuchi, H.; Misawa, H.; Tsuchiya, F.; Kita, H.; Sekido, M.

    2016-08-01

    We report on a very long baseline interferometry (VLBI) experiment on giant radio pulses (GPs) from the Crab pulsar in the radio 1.4–1.7 GHz range to demonstrate a VLBI technique for searching for fast radio bursts (FRBs). We carried out the experiment on 2014 July 26 using the Kashima 34 m and Usuda 64 m radio telescopes of the Japanese VLBI Network (JVN) with a baseline of about 200 km. During the approximately 1 hr observation, we could detect 35 GPs by high-time-resolution VLBI. Moreover, we determined the dispersion measure (DM) to be 56.7585 ± 0.0025 on the basis of the mean DM of the 35 GPs detected by VLBI. We confirmed that the sensitivity of a detection of GPs using our technique is superior to that of a single-dish mode detection using the same telescope.

  2. An ultrashort pulse ultra-violet radiation undulator source driven by a laser plasma wakefield accelerator

    OpenAIRE

    Anania, M.P.; Brunetti, E; Wiggins, S M; Grant, D W; Welsh, G. H.; Issac, R.C.; Cipiccia, S.; Shanks, R. P.; Manahan, G. G.; Aniculaesei, C.; van der Geer, S. B.; De Loos, M.J.; Poole, M.W.; Shepherd, B. J. A.; Clarke, J A

    2014-01-01

    Narrow band undulator radiation tuneable over the wavelength range of 150–260 nm has been produced by short electron bunches from a 2 mm long laser plasma wakefield accelerator based on a 20 TW femtosecond laser system. The number of photons measured is up to 9 × 106 per shot for a 100 period undulator, with a mean peak brilliance of 1 × 1018 photons/s/mrad2/mm2/0.1% bandwidth. Simulations estimate that the driving electron bunch r.m.s. duration is as short as 3 fs when the electron beam has ...

  3. Helium-3 and Helium-4 acceleration by high power laser pulses for hadron therapy

    OpenAIRE

    Bulanov, S. S.; Esarey, E.; Schroeder, C. B.; Leemans, W. P.; Bulanov, S. V.; Margarone, D.; Korn, G.; Haberer, T.

    2015-01-01

    The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions. This fact along with the larger biolo...

  4. Compact atomic gravimeter based on a pulsed and accelerated optical lattice

    CERN Document Server

    Andia, Manuel; Nez, François; Biraben, François; Guellati-Khélifa, Saïda; Cladé, Pierre

    2013-01-01

    We present a new scheme of compact atomic gravimeter based on atom interferometry. Atoms are maintained against gravity using a sequence of coherent accelerations performed by the Bloch oscillations technique. We demonstrate a sensitivity of 4.8$\\times 10^{-8}$ with an integration time of 4 min. Combining this method with an atomic elevator allows to measure the local gravity at different positions in the vacuum chamber. This method can be of relevance to improve the measurement of the Newtonian gravitational constant $G$.

  5. An improved pulse-line accelerator-driven, intense current-density, and high-brightness pseudospark electron beam

    International Nuclear Information System (INIS)

    A high-voltage (200 kV), high current-density, low-emittance (23 π·mm mrd), high-brightness (8 x 1010 A/(mrd)2) electron beam was generated in a pseudospark chamber filled with 15 Pa nitrogen and driven by a modified pulse line accelerator. The beam ejected with ≤1-mm diameter, 2.2-kA beam current, 400-ns pulse length, and about 20 cm propagation distance. Exposure of 10 shots on the same film produced a hole of 1.6-mm diameter at 7 cm downstream of the anode, and showed its good reproducibility. After 60 shots, it was observed that almost no destructive damage traces were left on the surfaces of the various electrodes and insulators of the pseudospark discharge chamber. It was experimentally found that the quality of the pseudospark electron beam remains very high, even at high voltages (of several hundred kilovolts), similar to low voltages, and is much better than the quality of the cold-cathode electron beams

  6. ON FABRICATION AND BRAZING OF 15A, 120 keV CONTINUOUS DUTY ACCELERATOR GRID ASSEMBLIES

    Energy Technology Data Exchange (ETDEWEB)

    Biagi, L.A.; Koehler, G.W.; Paterson, J.A.

    1980-05-01

    The development of high intensity neutral beam injectors at the Lawrence Berkeley Laboratory has progressed from relatively low duty cycle, low energy devices to the next generation of continuous duty high energy units. The earlier pulsed versions were designed with edge cooled grid structures described ·in a previous publication. The prerequisites set by the higher duty cycle devices no longer allow the edge cooling methods to be employed. Hollow molybdenum grid rails with deionized cooling water flowing at pressures of approximately 1.73 x 10{sup 6}Pa (250 PSI) at from 1.135 to 1.89 liters per minute (.3 to .5 GPM) are brazed to Type 304L stainless steel rail holders.

  7. Safety training and safe operating procedures written for PBFA (Particle Beam Fusion Accelerator) II and applicable to other pulsed power facilities

    Energy Technology Data Exchange (ETDEWEB)

    Donovan, G.L.; Goldstein, S.A.

    1986-12-01

    To ensure that work in advancing pulsed power technology is performed with an acceptably low risk, pulsed power research facilities at Sandia National Laboratories must satisfy general safety guidelines established by the Department of Energy, policies and formats of the Environment, Safety, and Health (ES and H) Department, and detailed procedures formulated by the Pulsed Power Sciences Directorate. The approach to safety training and to writing safe operating procedures, and the procedures presented here are specific to the Particle Beam Fusion Accelerator II (PBFA II) Facility but are applicable as guidelines to other research and development facilities which have similar hazards.

  8. Safety training and safe operating procedures written for PBFA [Particle Beam Fusion Accelerator] II and applicable to other pulsed power facilities

    International Nuclear Information System (INIS)

    To ensure that work in advancing pulsed power technology is performed with an acceptably low risk, pulsed power research facilities at Sandia National Laboratories must satisfy general safety guidelines established by the Department of Energy, policies and formats of the Environment, Safety, and Health (ES and H) Department, and detailed procedures formulated by the Pulsed Power Sciences Directorate. The approach to safety training and to writing safe operating procedures, and the procedures presented here are specific to the Particle Beam Fusion Accelerator II (PBFA II) Facility but are applicable as guidelines to other research and development facilities which have similar hazards

  9. Linear accelerator of All-Union Scientific Research Institute of Experimental Physics for neutron spectrometry

    International Nuclear Information System (INIS)

    The electron linear accelerator intended for neutron spectrometry with a nominal energy of about 55 MeV at currents of 10 A in electron pulse repetition rate of 2400 Hz started in 1985 is described. The special features of linac construction, the measuring complex assembly, the results of spectrum measurements and neutron yield of uranium target are given. The possibilities of accelerator development for increasing the pulse current and pulse length shortening are considered. (orig.)

  10. Study of Pre-Plasma Effects on Fast Electron Generation and Transport using the Split Pulse Titan Laser

    Science.gov (United States)

    Peebles, J.; Krauland, C. M.; McGuffey, C.; Sorokovikova, A.; Hua, R.; Wei, M. S.; Kerr, S.; Curry, C.; Sio, H.; Forestier-Colleoni, P.; Santos, J.; McLean, H. S.; Krasheninnikov, S.; Beg, F. N.

    2015-11-01

    Relativistic laser plasma interactions (LPI) could facilitate interesting and useful applications, such as table top particle acceleration and high energy K-alpha and gamma ray sources. In recent experiments it has been shown that the presence of an underdense, pre-formed plasma at the target surface has a significant heating effect. PIC simulations have shown that an electrostatic potential well forms on the target surface in this pre-plasma, which traps electrons and allows them to be excited to very high energy. Here we present results from an experiment conducted on the high intensity Titan laser at the Jupiter Laser Facility to further examine the role of pre-plasma in electron heating. We utilized the split beam, short pulse capability of the Titan system to generate and diagnose an interaction via proton radiography. The region was altered with a controlled pre-plasma generated by a wide focus, long pulse beam with variable energy. These experiments show that in the presence of pre-plasma, a hotter secondary population of electrons was generated. This work performed under the auspices of the US DOE Office of Sciences Program under contracts DE-NA0001858.

  11. Fast-ion emission from CO2-laser pulse generated plasma

    International Nuclear Information System (INIS)

    The measurement results are presented of fast-ion emission from plasma generated by a high-power CO2-laser radiationpulse. The energy distribution was measured of multi-charge ions as well as the angular distribution of the ion emission. The electron temperature of the plasma as well as the temperature (energy) of hot electrons were defined. On the basis of the results obtained the energy was assessed carried off by ions from plasma. The results obtained provide information about anomalous phenomena associated with the interaction of laser radiation with plasma. (author)

  12. Calculations to compare different ways of modelling the plate geometry cells of the Zebra fast critical assembly, MZA

    Energy Technology Data Exchange (ETDEWEB)

    Rowlands, John, E-mail: rowlandsjl@aol.com

    2009-03-15

    The core region cells of the Zebra fast critical assembly MZA comprise 14 plates in a square steel tube, with 12 cells being stacked axially to form the core section of the assembly. The cells can be modelled in different levels of detail, ranging from a three-dimensional representation in which the core (The word core is used to describe both the region of a plate containing the main material, such as plutonium, UO{sub 2} or sodium, and the region of the assembly containing fissile material cells.) and canning regions of the plates and the void gaps between the edges of the plates and the steel tube, and between tubes, are represented. Simplified models include a three-dimensional representation in which the void regions are combined with the tube material. A further simplified three-dimensional model, called the MURAL model, represents the core regions of the plates but homogenises the canning, tube material and void regions. Two types of one-dimensional slab geometry model are found in the literature, one in which the materials are homogenised within each of the three axial slab regions of a canned plate (plate core and upper and lower canning regions) and a further simplified version in which the plate is modelled as a single region, the compositions being averaged over the whole thickness of the plate, comprising the plate core material, the canning and the tube material. MONK Monte Carlo calculations have been made for each of these models, and also for the fully homogenised cells, and the k-effective values, core sodium void reactivities and reaction rate ratios are compared.

  13. Analytic characterization of linear accelerator radiosurgery dose distributions for fast optimization

    Science.gov (United States)

    Meeks, Sanford L.; Bova, Frank J.; Buatti, John M.; Friedman, William A.; Eyster, Brian; Kendrick, Lance A.

    1999-11-01

    Linear accelerator (linac) radiosurgery utilizes non-coplanar arc therapy delivered through circular collimators. Generally, spherically symmetric arc sets are used, resulting in nominally spherical dose distributions. Various treatment planning parameters may be manipulated to provide dose conformation to irregular lesions. Iterative manipulation of these variables can be a difficult and time-consuming task, because (a) understanding the effect of these parameters is complicated and (b) three-dimensional (3D) dose calculations are computationally expensive. This manipulation can be simplified, however, because the prescription isodose surface for all single isocentre distributions can be approximated by conic sections. In this study, the effects of treatment planning parameter manipulation on the dimensions of the treatment isodose surface were determined empirically. These dimensions were then fitted to analytic functions, assuming that the dose distributions were characterized as conic sections. These analytic functions allowed real-time approximation of the 3D isodose surface. Iterative plan optimization, either manual or automated, is achieved more efficiently using this real time approximation of the dose matrix. Subsequent to iterative plan optimization, the analytic function is related back to the appropriate plan parameters, and the dose distribution is determined using conventional dosimetry calculations. This provides a pseudo-inverse approach to radiosurgery optimization, based solely on geometric considerations.

  14. Generation of fast neutrons through deuteron acceleration at the PALS laser facility

    International Nuclear Information System (INIS)

    Recent experiments at the laser facility PALS focused on the laser driven fusion of deuterons are reviewed. They benefit of high reaction cross-sections and of a high number of multi-MeV deuterons from thick CD2 targets irradiated by intensity of 3× 1016 W cm−2. In the reported experiments fast fusion neutrons with energy up to 16 MeV were produced through 7Li(d, n)8Be and 11B(d, n)12C reactions in a pitcher-catcher target configuration. When using a large area CD2 foil as a secondary catcher target the total maximum neutron yield from the 2H(d, n)3He reaction increased by a factor of about 5, from 4× 108 to 2× 109. This result reveals that most of the deuterons having enough kinetic energy to enter a fusion reaction are emitted from the primary target into vacuum

  15. Partial flow blockage effects within a (liquid metal cooled fast reactor) LMFBR fuel assembly

    International Nuclear Information System (INIS)

    A lumped thermal-hydraulic model was used to calculate the increase in the sodium and cladding temperatures in the wake behind a non-porous partial flow blockage within a typical LMFBR fuel rod assembly. The model predicts that over 25 percent of the cross sectional flow area may be blocked before the wake fluid temperature reaches boiling; the actual size depends on the blockage axial location and radial location. Agreement with the limited sodium flow rod bundle blockage data is achieved by the model if the wide variation observed in the experimental cladding temperatures within the wake region is attributed to variations in local heat transfer coefficients. (29 references) (U.S.)

  16. FAST TRACK COMMUNICATION Temperature-driven phase transformation in self-assembled diphenylalanine peptide nanotubes

    Science.gov (United States)

    Heredia, A.; Bdikin, I.; Kopyl, S.; Mishina, E.; Semin, S.; Sigov, A.; German, K.; Bystrov, V.; Gracio, J.; Kholkin, A. L.

    2010-11-01

    Diphenylalanine (FF) peptide nanotubes (PNTs) represent a unique class of self-assembled functional biomaterials owing to a wide range of useful properties including nanostructural variability, mechanical rigidity and chemical stability. In addition, strong piezoelectric activity has recently been observed paving the way to their use as nanoscale sensors and actuators. In this work, we fabricated both horizontal and vertical FF PNTs and examined their optical second harmonic generation and local piezoresponse as a function of temperature. The measurements show a gradual decrease in polarization with increasing temperature accompanied by an irreversible phase transition into another crystalline phase at about 140-150 °C. The results are corroborated by the molecular dynamic simulations predicting an order-disorder phase transition into a centrosymmetric (possibly, orthorhombic) phase with antiparallel polarization orientation in neighbouring FF rings. Partial piezoresponse hysteresis indicates incomplete polarization switching due to the high coercive field in FF PNTs.

  17. Chiral-induced self-assembly sphere phase liquid crystal with fast switching time

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Ji-Liang; Ni, Shui-Bin; Ping Chen, Chao; Lu, Jian-Gang, E-mail: lujg@sjtu.edu.cn; Su, Yikai [National Engineering Lab for TFT-LCD Materials and Technologies, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wu, Dong-Qing [College of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Song, Xiao-Long; Chen, Chao-Yuan [The Jiangsu Hecheng Display Technology Co., Ltd., Nanjing 211300 (China); Shieh, Han-Ping D. [National Engineering Lab for TFT-LCD Materials and Technologies, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Photonics and Display Institute, National Chiao Tung University, Hsinchu 300, Taiwan (China)

    2014-03-03

    A fluid self-assembly sphere phase (SP) of liquid crystal induced by chiral dopant is observed in a narrow temperature range between isotropic and blue phase or between isotropic and chiral nematic phase. The SP consists of three-dimensional twist spheres (3-DTSs) and disclinations among 3-DTSs. The temperature range of the SP has been broadened to more than 85 °C by stabilizing the disclinations with amorphous polymer chains. The electro-optical switching time of the polymer-stabilized SP is demonstrated in sub-millisecond with a low switching electric field of 4.4 V μm{sup −1}, which is of promising applications in displays, 3-D tunable photonic crystals, and phase modulators.

  18. Microfluidic assembly kit based on laser-cut building blocks for education and fast prototyping.

    Science.gov (United States)

    Gerber, Lukas C; Kim, Honesty; Riedel-Kruse, Ingmar H

    2015-11-01

    Here, we present an inexpensive rapid-prototyping method that allows researchers and children to quickly assemble multi-layered microfluidic devices from easily pre-fabricated building blocks. We developed low-cost (building block pieces and double-sided tape that allow users to generate water droplets in oil, capture living cells, and conduct basic phototaxis experiments. We developed and tested a 90-min lesson plan with children aged 12-14 yr and provide here the instructions for teachers to replicate these experiments and lessons. All parts of the kit are easy to make or order. We propose to use such easy to fabricate kits in labs with no access to current microfluidic tools as well as in classroom environments to get exposure to the powerful techniques of microfluidics. PMID:26634013

  19. Detection of accelerated particles from pulsed plasma discharge using solid state nuclear track detector

    Indian Academy of Sciences (India)

    G M El-Aragi; U Seddik; A Abd El-Haliem

    2007-04-01

    The ion beam of a Mather-type 23.25 J plasma focus device operated with air filling at 10 Torr was registered using CR-39 nuclear track detector. The irradiated samples were etched in NaOH solution at 70°C for 1 h. It is found here that plasma beam contains multi-components of microbeams. The individual track density of microbeams is estimated and the total current density of the plasma stream is measured to be 1.2 mA/cm2. A model for counting the track density of individual microbeams is proposed here. Faraday cup measurements showed the ion pulse with energy ranging from 5.8 keV to 3.3 keV.

  20. Pulsed nanosecond discharge in air at high specific deposited energy: fast gas heating and active particle production

    Science.gov (United States)

    Popov, N. A.

    2016-08-01

    The results of a numerical study on kinetic processes initiated by a pulsed nanosecond discharge in air at high specific deposited energy, when the dissociation degree of oxygen molecules is high, are presented. The calculations of the temporal dynamics of the electron concentration, density of atomic oxygen, vibrational distribution function of nitrogen molecules, and gas temperature agree with the experimental data. It is shown that quenching of electronically excited states of nitrogen N2(B3Πg), N2(C3Πu), N2(a‧1 Σ \\text{u}- ) by oxygen molecules leads to the dissociation of O2. This conclusion is based on the comparison of calculated dynamics of atomic oxygen in air, excited by a pulsed nanosecond discharge, with experimental data. In air plasma at a high dissociation degree of oxygen molecules ([O]/[O2] > 10%), relaxation of the electronic energy of atoms and molecules in reactions with O atoms becomes extremely important. Active production of NO molecules and fast gas heating in the discharge plasma due to the quenching of electronically excited N2(B3Πg, C3Πu, a‧1 Σ \\text{u}- ) molecules by oxygen atoms is notable. Owing to the high O atom density, electrons are effectively detached from negative ions in the discharge afterglow. As a result, the decay of plasma in the afterglow is determined by electron-ion recombination, and the electron density remains relatively high between the pulses. An increase in the vibrational temperature of nitrogen molecules at the periphery of the plasma channel at time delay t = 1-30 μs after the discharge is obtained. This is due to intense gas heating and, as a result, gas-dynamic expansion of a hot gas channel. Vibrationally excited N2(v) molecules produced near the discharge axis move from the axial region to the periphery. Consequently, at the periphery the vibrational temperature of nitrogen molecules is increased.

  1. Pulsed Laser-Driven Molecular Self-assembly of Cephalexin: Aggregation-Induced Fluorescence and Its Utility as a Mercury Ion Sensor.

    Science.gov (United States)

    Singh, Pradeep Kumar; Prabhune, Asmita; Ogale, Satishchandra

    2015-11-01

    A fluorescent self-assembly of cephalexin is obtained by pulsed laser irradiation process. An intense fluorescence emission is found in the self-assembled form due to occurrence of a typical aggregation-induced emission in cephalexin molecules. It is observed that fluorescence quenching of the self-assembled fluorescent nanostructures occurs in the presence of extremely low Hg(++) ions concentrations (10(-7) m) as compared to other heavy metal ions e.g. Ferrous (Fe(++) ), Manganese (Mn(++) ), Magnesium (Mg(++) ), Cobalt (Co(++) ), Nickel (Ni(++) ) and Zinc (Zn(++) ) at the same concentrations. PMID:26333412

  2. [Spectroscopic study on the high voltage fast pulsed discharge of nitrogen, ammonia or their mixture].

    Science.gov (United States)

    Liu, Z P; Wang, P N; Yang, W D; Zheng, J B; Li, F M

    2001-10-01

    The emission spectra from the pulsed discharge plasma of nitrogen, ammonia or their mixture were measured. In the discharge of pure nitrogen gas, as the pressure increased, the discharge volume decreased and more dissociation of nitrogen molecules occurred due to the higher energy density. In the discharge of ammonia, N,N+ and NH+ were observed, but no NH2 and NH3 were detected, indicating that ammonia, which has the lower dissociation and ionization energies as compared to nitrogen, was highly dissociated. The discharge of the mixture of N2 and NH3 was also studied. The dependence of the dissociation of nitrogen on the ratio of nitrogen to ammonia was investigated by emission spectra. The optimal ratio for nitrogen dissociation was obtained. The advantage of using the mixture of nitrogen and ammonia in the synthesis of nitrides was discussed. PMID:12945317

  3. Colliding pulse injection experiments in non-collinear geometryfor controlled laser plasma wakefield acceleration of electrons

    Energy Technology Data Exchange (ETDEWEB)

    Toth, Carl B.; Esarey, Eric H.; Geddes, Cameron G.R.; Leemans,Wim P.; Nakamura, Kei; Panasenko, Dmitriy; Schroeder, Carl B.; Bruhwiler,D.; Cary, J.R.

    2007-06-25

    An optical injection scheme for a laser-plasma basedaccelerator which employs a non-collinear counter-propagating laser beamto push background electrons in the focusing and acceleration phase viaponderomotive beat with the trailing part of the wakefield driver pulseis discussed. Preliminary experiments were performed using a drive beamof a_0 = 2.6 and colliding beam of a_1 = 0.8 both focused on the middleof a 200 mu m slit jet backed with 20 bar, which provided ~; 260 mu mlong gas plume. The enhancement in the total charge by the collidingpulse was observed with sharp dependence on the delay time of thecolliding beam. Enhancement of the neutron yield was also measured, whichsuggests a generation of electrons above 10 MeV.

  4. Efficient neutron production from sub-nanosecond laser pulse accelerating deuterons on target front side

    International Nuclear Information System (INIS)

    Neutron-producing experiments have been carried out on the Prague Asterix Laser System. At the fundamental wavelength of 1.315 μm, the laser pulse of a 600 J energy and 300 ps duration was focused on a thick deuterated-polyethylene target. Neutron yields reached (4.1 ± 0.8) × 108 at the peak intensity of ≈3 × 1016 W/cm2. A more detailed analysis of neutron time-of-flight signals showed that a significant fraction of neutron yields was produced both by the 2H(d,n)3He reaction and by other neutron-producing reactions. Neutron energies together with delayed neutron and gamma emission showed that MeV deuterons escaped from a laser-produced plasma and interacted ≈50 ns later with a borosilicate blast-shield glass. In order to increase DD neutron yields and to characterize deuteron beams via nuclear reactions, a secondary deuterated polyethylene target was used in a pitcher-catcher scheme at the target front side. In this experimental arrangement, the neutron yield reached (2.0 ± 0.5) × 109 with the peak neutron fluence of (2.5 ± 0.5) × 108 n/sr. From the neutron yield, it was calculated that the secondary target was bombarded by 2 × 1014 deuterons in the 0.5–2.0 MeV energy range. The neutron yield of 2 × 109 at the laser energy of 600 J implied the production efficiency of 3 × 106 n/J. A very important result is that the efficient neutron production was achieved with the low contrast, sub-nanosecond laser pulse of the intensity of 1016 W/cm2. The latter parameters can be achieved in a rep-rate mode more easily than ultra-high intensities and contrasts

  5. Continuing studies of plasma erosion switches for power conditioning on multiterawatt pulsed power accelerators

    International Nuclear Information System (INIS)

    Recent PITHON experiments with plasma erosion switches (PES) have extended the range of operation of the switches by about 50 percent, in terms of closed time and charge passing through the switch. The quantity of charge passed through the switch has been increased to as much as 35 mC. Currents as large as 1 MA and voltages as great as 1.8 MV have been switched off to be diverted to a downstream load. The impedance of the erosion switch can be described as having three stages: 1) essentially zero impedance, 2) a transitional opening phase, and 3) an impedance which is very large (greater than 5 Ω) in comparison with the subohm downstream load. Current diagnostics, consisting of Rogowski coils and segmented shunts, have been successfully developed to monitor the current which propagates to the load region. These monitors have measured rise times as short as 38 ns and slew rates as great as 1014 A/s at the load. With wire array loads, the pulse conditioning of the switch has been observed to reduce the magnitude of the current losses in the feed which are present when no switch is used. Correlations have been made between the switch closed time, voltage, current, and power with the feed inductance and the generator power injected into the magnetic insulated transmission line (MITL)

  6. Development and deployment of CW and pulsed digital low level RF systems for accelerators at RRCAT

    International Nuclear Information System (INIS)

    Indus-2, a 2.5 GeV synchrotron radiation source has four 505.8 MHz RF stations to increase the electron beam energy and compensate the synchrotron radiation losses. Each RF station consists of RF cavity, high power RF amplifier and Low Level RF (LLRF) system operating in CW mode. LLRF control system is used to keep the amplitude and phase of the RF field stable in the RF cavity. The LLRF system of Indus-2 was based on analogue technology and had its inherent limitations. In last few years significant up gradation has been done in Indus-2 RF system that includes development, installation and commissioning of CW, Digital LLRF systems in all four RF stations. These Digital LLRF systems have replaced analogue LLRF systems resulting in improved performance of Indus-2 by providing better RF cavity field stability. Digital LLRF systems are more reliable, adaptable, reproducible, precise and immune to noise and drift errors. All these properties play important role in enhancing the quality and increasing the availability of the synchrotron radiation for the users. In this paper, we shall discuss the development, installation and commissioning of CW Digital LLRF systems in Indus-2 and development of pulsed Digital LLRF system for IRFEL. The results of their deployment and experience of optimization for Klystron and solid state RF amplifier will also be presented

  7. Low-intensity pulsed ultrasound accelerates nerve regeneration following inferior alveolar nerve transection in rats.

    Science.gov (United States)

    Sato, Mai; Motoyoshi, Mitsuru; Shinoda, Masamichi; Iwata, Koichi; Shimizu, Noriyoshi

    2016-06-01

    Inferior alveolar nerve (IAN) injury, which is frequently caused by orofacial surgery or trauma, induces sensory loss in orofacial regions innervated by the IAN. However, no effective treatment for orofacial sensory loss currently exists. We determined whether sensory loss in facial skin above the mental foramen following IAN transection was recovered by exposure of the transected IAN to low-intensity pulsed ultrasound (LIPUS). Inferior alveolar nerve transection (IANX) was performed in 7-wk-old male Sprague-Dawley rats. On day 7 after IANX, the effect of daily LIPUS (from day 0) on the transected IAN, in terms of sensitivity to mechanical stimulation of the facial skin above the mental foramen, was examined. Moreover, the number of trigeminal ganglion (TG) neurons innervating the facial skin above the mental foramen of rats with IANX treated daily with LIPUS was counted using the retrograde neurotracing technique. Daily exposure of the transected IAN to LIPUS significantly promoted recovery of the head-withdrawal threshold in response to mechanical stimulation of the facial skin above the mental foramen, and the number of TG neurons innervating the facial skin above mental foramen was significantly increased in rats with IANX treated daily with LIPUS compared with sham or LIPUS-unexposed rats. Daily treatment of stumps of the transected IAN with LIPUS facilitated morphological and functional regeneration, suggesting that LIPUS is an effective and novel therapy for IAN injury. PMID:27058986

  8. Technical meeting (TM) to 'Review of national programmes on fast reactors and accelerator driven systems (ADS)'. Technical Working Group on Fast Reactors (TWG-FR) (37th annual meeting). Working material

    International Nuclear Information System (INIS)

    The objectives of the 37th Annual Meeting of the Technical Working Group on Fast Reactors, were to: 1) exchange information on the national programmes on Fast Reactors (FR) and Accelerator Driven Systems (ADS); 2) review the progress since the 36th TWG-FR Annual Meeting, including the status of the actions; 3) consider meeting arrangements for 2004 and 2005; 4) review the Agency's co-ordinated research activities in the field of FRs and ADS, as well as co-ordination of the TWG-FR's activities with other organizations. The participants made presentations on the status of the respective national programmes on FR and ADS development. A summary of the highlights for the period since the 36th TWG-FR Annual Meeting is included in this proceedings. Annex IV contains the Review of National Programs on Fast Reactors and Accelerator Driven Systems (ADS), and the TWG-FR Activity Report for the Period May 2003-April 2004

  9. A 3-10 GHz IR-UWB CMOS Pulse Generator With 6-mW Peak Power Dissipation Using A Slow-Charge Fast-Discharge Technique

    DEFF Research Database (Denmark)

    Shen, Ming; Yin, Ying-Zheng; Jiang, Hao;

    2014-01-01

    This letter proposes a UWB pulse generator topology featuring low peak power dissipation for applications with stringent instantaneous power requirements. This is accomplished by employing a new slow-charge fast-discharge approach to extend the time duration of the generator's peak current so tha...

  10. Thermal-Hydraulic Calculation for Simplified Fuel Assembly of Super Fast Reactor Using Two-Fluid Model Analysis Code ACE-3D

    International Nuclear Information System (INIS)

    To evaluate thermal hydraulic characteristics of a fuel assembly of supercritical water-cooled fast reactor (Super Fast Reactor), a simplified fuel assembly was analyzed with a three-dimensional two-fluid model analysis code ACE-3D which has been enhanced by Japan Atomic Energy Agency. In the ACE-3D code, the two-phase flow turbulent model based on the k-ε model were adopted. The analytical geometry simulates a 19-rod fuel assembly, which is a simplified geometry of the 271-rod fuel assembly and includes all three kinds of different subchannel types; (1): adjoining to the channel box, (2): next to type (1), and (3): located inside types (1) and (2). In this calculation, one-twelfth model is adopted as the computational domain taking advantage of symmetry. As the boundary conditions, mass velocity, inlet enthalpy and power per rod are to be the same as the steady state condition of the Super Fast Reactor. Cross-sectional local power distribution in the fuel assembly is set to be flat. Rod surface temperatures take peak values near the top of the rods. Maximum clad surface temperature (MCST) is observed at the position facing to the narrowest gap on the center rod near the outlet and the value is 902 K (629 deg. C). It was confirmed that the predicted MCST satisfies a thermal design criteria to ensure fuel and cladding integrity: the MCST should be less than 650 deg. C. (author)

  11. Effect of Inductive Coil Geometry on the Operating Characteristics of a Pulsed Inductive Plasma Accelerator

    Science.gov (United States)

    Hallock, Ashley K.; Polzin, Kurt A.; Kimberlin, Adam C.

    2012-01-01

    Operational characteristics of two separate inductive thrusters with coils of different cone angles are explored through thrust stand measurements and time-integrated, un- filtered photography. Trends in impulse bit measurements indicate that, in the present experimental configuration, the thruster with the inductive coil possessing a smaller cone angle produced larger values of thrust, in apparent contradiction to results of a previous thruster acceleration model. Areas of greater light intensity in photographs of thruster operation are assumed to qualitatively represent locations of increased current density. Light intensity is generally greater in images of the thruster with the smaller cone angle when compared to those of the thruster with the larger half cone angle for the same operating conditions. The intensity generally decreases in both thrusters for decreasing mass ow rate and capacitor voltage. The location of brightest light intensity shifts upstream for decreasing mass ow rate of propellant and downstream for decreasing applied voltage. Recognizing that there typically exists an optimum ratio of applied electric field to gas pressure with respect to breakdown efficiency, this result may indicate that the optimum ratio was not achieved uniformly over the coil face, leading to non-uniform and incomplete current sheet formation in violation of the model assumption of immediate formation where all the injected propellant is contained in a magnetically-impermeable current sheet.

  12. Pulsed power magnet technology for laser particle acceleration and laser plasma physics - a survey of developments at Helmholtz-Zentrum Dresden-Rossendorf

    International Nuclear Information System (INIS)

    Since the mid-1950s, pulsed high-field magnets have become a common, versatile research tool with application mostly in solid state physics and material research. Recently developed pulsed power magnet technology, specifically designed to meet the demands of laser acceleration and laser plasma experiments, open up new research opportunities: We present a pulsed air core solenoid (up to 20 T) for effective collection and focusing of laser accelerated particles. It could function as a crucial part of a compact, laser-based ion source (pursued by the LIGHT collaboration) or of beam guidance systems. Furthermore, the poster shows a split pair coil, utterly compact and with optical access in between the coil pairs and on axis, to study laser-driven plasma expansion under high magnetic fields (30 T). To power such devices, portable capacitor-based pulse generators have been developed at Helmholtz-Zentrum Dresden-Rossendorf. We present first results of the functional testing of our third-generation pulse generator. Looking forward, we outline a concept for a medical gantry based on pulsed high field beam optics.

  13. Measurements of the temporal and spatial phase variations of a 33 GHz pulsed free electron laser amplifier and application to high gradient RF acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Volfbeyn, P.; Bekefi, G. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1995-12-31

    We report the results of temporal and spatial measurements of phase of a pulsed free electron laser amplifier (FEL) operating in combined wiggler and axial guide magnetic fields. The 33 GHz FEL is driven by a mildly relativistic electron beam (750 kV, 90-300 A, 30 ns) and generates 61 MW of radiation with a high power magnetron as the input source. The phase is measured by an interferometric technique from which frequency shifting is determined. The results are simulated with a computer code. Experimental studies on a CERN-CLIC 32.98 GHz 26-cell high gradient accelerating section (HGA) were carried out for input powers from 0.1 MW to 35 MW. The FEL served as the r.f. power source for the HGA. The maximum power in the transmitted pulse was measured to be 15 MW for an input pulse of 35 MW. The theoretically calculated shunt impedance of 116 M{Omega}/m predicts a field gradient of 65 MeV/m inside the HGA. For power levels >3MW the pulse transmitted through the HGA was observed to be shorter than the input pulse and pulse shortening became more serious with increasing power input. At the highest power levels the output pulse length (about 5 nsec) was about one quarter of the input pulse length. Various tests suggest that these undesirable effects occur in the input coupler to the HGA. Light and X-ray production inside the HGA have been observed.

  14. Miktoarms hyperbranched polymer brushes:One-step fast synthesis by parallel click chemistry and hierarchical self-assembly

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Spherical molecular brushes with amphiphilic heteroarms were facilely synthesized by grafting the arms of hydrophobic 2-azidoethyle palmitate and hydrophilic monoazide-terminated poly(ethylene glycol) onto the core of alkyne-modified hyperbranched polyglycerol (HPG) with high molecular weight (Mn=122 kDa) via one-pot parallel click chemistry.The parallel click grafting strategy was demonstrated to be highly efficient (~100%),very fast (~ 2 h) and well controllable to the amphilicity of molecular brushes.Through adjusting the feeding ratio of hydrophobic and hydrophilic arms,a series of brushes with different arm ratios were readily obtained.The resulting miktoarms hyperbranched polymer brushes (HPG-g-C16/PEG350) were characterized by hydrogen-nuclear magnetic resonance (1H NMR),Fourier transform infrared (FT-IR) spectroscopy,gel permeation chromatography (GPC),and differential scanning calorimetry (DSC) measurements.The spherical molecular brushes showed high molecular weights up to 230 kDa,and thus could be visualized by atomic force microscopy (AFM).AFM and dynamic laser light scattering (DLS) were employed to investigate the self-assembly properties of amphiphilic molecular brushes with closed proportion of hydrophobic and hydrophilic arms.The brushes could self-assemble hierarchically into spherical micelles,and network-like fibre structures,and again spherical micelles by addition of n-hexane into the dichloromethane or chloroform solution of brushes.In addition,this kind of miktoarms polymer brush also showed the ability of dye loading via host-guest encapsulation,which promises the potential application of spherical molecular brushes in supramolecular chemistry.

  15. Fast dynamic 3D MR spectroscopic imaging with compressed sensing and multiband excitation pulses for hyperpolarized 13C studies.

    Science.gov (United States)

    Larson, Peder E Z; Hu, Simon; Lustig, Michael; Kerr, Adam B; Nelson, Sarah J; Kurhanewicz, John; Pauly, John M; Vigneron, Daniel B

    2011-03-01

    Hyperpolarized 13C MR spectroscopic imaging can detect not only the uptake of the pre-polarized molecule but also its metabolic products in vivo, thus providing a powerful new method to study cellular metabolism. Imaging the dynamic perfusion and conversion of these metabolites provides additional tissue information but requires methods for efficient hyperpolarization usage and rapid acquisitions. In this work, we have developed a time-resolved 3D MR spectroscopic imaging method for acquiring hyperpolarized 13C data by combining compressed sensing methods for acceleration and multiband excitation pulses to efficiently use the magnetization. This method achieved a 2 sec temporal resolution with full volumetric coverage of a mouse, and metabolites were observed for up to 60 sec following injection of hyperpolarized [1-(13)C]-pyruvate. The compressed sensing acquisition used random phase encode gradient blips to create a novel random undersampling pattern tailored to dynamic MR spectroscopic imaging with sampling incoherency in four (time, frequency, and two spatial) dimensions. The reconstruction was also tailored to dynamic MR spectroscopic imaging by applying a temporal wavelet sparsifying transform to exploit the inherent temporal sparsity. Customized multiband excitation pulses were designed with a lower flip angle for the [1-(13)C]-pyruvate substrate given its higher concentration than its metabolic products ([1-(13)C]-lactate and [1-(13)C]-alanine), thus using less hyperpolarization per excitation. This approach has enabled the monitoring of perfusion and uptake of the pyruvate, and the conversion dynamics to lactate and alanine throughout a volume with high spatial and temporal resolution. PMID:20939089

  16. A -50 kV electron gun high voltage pulse power supply with 50 kW peak power for electron accelerators

    International Nuclear Information System (INIS)

    An electron gun being developed at RRCAT requires a high voltage (HV) pulse power supply of -50 kV with peak power of 50 kW for acceleration of thermionically generated electrons from cathode of the electron gun. A single switch forward converter is used to energize a step up HV pulse transformer to generate the required high voltage pulse. An RCD clamp circuit is used on primary side of the pulse transformer to clamp the reverse voltage across the primary as well as secondary of the transformer. The design parameters, simulation and experimental results of the power supply and details of resin cast HV transformer are presented in this paper. (author)

  17. Fast-light Enhanced Brillouin Laser Based Active Fiber Optics Sensor for Simultaneous Measurement of Rotation and Acceleration

    CERN Document Server

    Zhou, Minchuan; Fouda, Mohamed; Condon, Nicholas; Scheuer, Jacob; Shahriar, Selim M

    2016-01-01

    We have developed a conceptual design for an Active Fast Light Fiber Optic Sensor (AFLIFOS) that can perform simultaneously or separately as a gyroscope (differential mode effect) and a sensor for acceleration, strain, and other common mode effects. Two Brillouin lasers in opposite directions and separated in frequency by several free spectral ranges are used for this sensor. By coupling two auxiliary resonators to the primary fiber resonator, we produce superluminal effects for two laser modes. We develop a detailed theoretical model for optimizing the design of the AFLIFOS, and show that the enhancement factor of the sensitivity is $\\sim{187}$ and $\\sim{-187}$, respectively for the two Brillouin lasers under the optimized condition, when the effective change in perimeter of the primary fiber resonator is 0.1nm, corresponding to a rotation rate of 0.4 deg/sec for a ring resonator with radius 1m. It may be possible to get much higher enhancement by adjusting the parameters such as the perimeters and the coupl...

  18. Pulsed laser deposition of cluster-assembled films for catalysis and the photocatalysis relevant to energy and the environment

    International Nuclear Information System (INIS)

    Nanoparticles (NPs) catalysts are under intense investigation in the catalysis community due to their exceptional activity and selective nature in catalytic processes as compared to the corresponding bulk counterpart, especially because of their large surface-to-volume atomic ratio, size- and shape-dependent properties, and high concentration of low-coordinated active surface sites. However, there is no general strategy to synthesize NPs of various materials with narrow size distribution, tailored properties, and desired morphologies. The development of a technique able to prepare NPs is thus a goal of great importance to avoid present trial and error approaches. Here we report on selected examples where pulsed laser deposition (PLD) technique greatly contributes toward NPs synthesis. Co NPs embedded in B matrix films have been synthesized by PLD technique by taking advantage of the phase explosion process of superheated liquid where a mixture of vapor and liquid droplets leave the irradiated target surface and get deposited on the substrate. The deposited NPs exhibit catalytic properties comparable to that of precious metals in hydrogen production by hydrolysis of NaBH4 and NH3BH3. These NPs, when supported on rough carbon film prepared by PLD, show about 30% increase in catalytic activity for H2 production as compared to unsupported NPs. Co3O4 NPs assembled coating has been produced by reactive PLD in oxygen atmosphere at various substrate temperatures from room temperature to 250 °C. It was proved that the Co3O4 NPs can be obtained in a single step at low temperatures with mixed disordered-nanocrystalline phase that is a relevant feature for catalysis. The Co3O4 NPs assembled thin coating, employed in degradation of methylene blue solution, in water, via photo Fenton reaction in presence of H2O2, exhibits significantly higher activity as compared to the corresponding homogeneous catalyst.

  19. High power pulsed/microwave technologies for electron accelerators vis a vis 10MeV, 10kW electron LINAC for food irradiation at CAT

    International Nuclear Information System (INIS)

    Use of electron accelerators for irradiation of food items is gathering momentum in India. The various technologies for powering the electron LINAC were needed to be developed in the country due to embargo situations as well as reservations of the developers worldwide to share the information related to this development. Centre for Advanced Technology, CAT, Indore, is engaged in the development of particle accelerators for medical industrial and scientific applications. Amongst other electron accelerators developed in CAT, a 10MeV, 10kW LINAC for irradiation of food items has been commissioned and tested for full rated 10kW beam power. The high power pulsed microwave driver for the LINAC was designed, developed and commissioned with full indigenous efforts, and is right now operational at CAT. It consists of a 6MW, 25kW S-band pulsed klystron, 15MW peak power pulse modulator system for the klystron, microwave driver amplifier chain, stabilized generator, protection and control electronics, waveguide system to handle the high peak and average power, gun modulator electronics, grid electronics etc. The present paper highlights various technologies like the pulsed power systems and components, microwave circuits and systems etc. Also the performance results of the high power microwave driver for the 10MeV LINAC at CAT are discussed. Future strategies for developing the state of art technologies are highlighted. (author)

  20. Pulsed nanosecond discharge in air at high specific deposited energy: fast gas heating and active particle production

    Science.gov (United States)

    Popov, N. A.

    2016-08-01

    The results of a numerical study on kinetic processes initiated by a pulsed nanosecond discharge in air at high specific deposited energy, when the dissociation degree of oxygen molecules is high, are presented. The calculations of the temporal dynamics of the electron concentration, density of atomic oxygen, vibrational distribution function of nitrogen molecules, and gas temperature agree with the experimental data. It is shown that quenching of electronically excited states of nitrogen N2(B3Πg), N2(С3Πu), N2(a‧1 Σ \\text{u}- ) by oxygen molecules leads to the dissociation of O2. This conclusion is based on the comparison of calculated dynamics of atomic oxygen in air, excited by a pulsed nanosecond discharge, with experimental data. In air plasma at a high dissociation degree of oxygen molecules ([O]/[O2]  >  10%), relaxation of the electronic energy of atoms and molecules in reactions with O atoms becomes extremely important. Active production of NO molecules and fast gas heating in the discharge plasma due to the quenching of electronically excited N2(B3Πg, C3Πu, a‧1 Σ \\text{u}- ) molecules by oxygen atoms is notable. Owing to the high O atom density, electrons are effectively detached from negative ions in the discharge afterglow. As a result, the decay of plasma in the afterglow is determined by electron–ion recombination, and the electron density remains relatively high between the pulses. An increase in the vibrational temperature of nitrogen molecules at the periphery of the plasma channel at time delay t  =  1–30 μs after the discharge is obtained. This is due to intense gas heating and, as a result, gas-dynamic expansion of a hot gas channel. Vibrationally excited N2(v) molecules produced near the discharge axis move from the axial region to the periphery. Consequently, at the periphery the vibrational temperature of nitrogen molecules is increased.