WorldWideScience

Sample records for pulsed electron beams

  1. Pulsed electron beam precharger

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. (ed.); Shelton, W.N.

    1990-01-01

    Florida State University is investigating the concept of pulsed electron beams for fly ash precipitation. This report describes the results and data on three of the subtasks of this project and preliminary work only on the remaining five subtasks. Described are the modification of precharger for pulsed and DC energization of anode; installation of the Q/A measurement system; and modification and installation of pulsed power supply to provide both pulsed and DC energization of the anode. The other tasks include: measurement of the removal efficiency for monodisperse simulated fly ash particles; measurement of particle charge; optimization of pulse energization schedule for maximum removal efficiency; practical assessment of results; and measurement of the removal efficiency for polydisperse test particles. 15 figs., 1 tab. (CK)

  2. Pulsed electron beam precharger

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. (ed.); Shelton, W.N.

    1990-01-01

    Electrostatic collection of a high resistivity aerosol using the Electron Beam Precipitator (EBP) collecting section was demonstrated during this reporting period (Quarter Five). Collection efficiency experiments were designed to confirm and extend some of the work performed under the previous contract. The reason for doing this was to attempt to improve upon the collection efficiency of the precipitator alone when testing with a very high resistivity, moderate-to-high concentration dust load. From the collector shakedown runs, a set of suitable operational parameters were determined for the downstream electrostatic collecting sections of the Electron Beam Precipitator wind tunnel. These parameters, along with those for the MINACC electron beam, will generally be held constant while the numerous precharging parameters are varied to produce an optimum particle charge. The electrostatic collector experiments were part of a larger, comprehensive investigation on electron beam precharging of high resistivity aerosol particles performed during the period covered by Quarters Five, Six, and Seven. This body of work used the same experimental apparatus and procedures and the experimental run period lasted nearly continuously for six months. A summary of the Quarter Five work is presented in the following paragraphs. Section II-A of TPR 5 contains a report on the continuing effort which was expended on the modification and upgrade of the pulsed power supply and the monitoring systems prior to the initiation of the electron beam precharging experimental work.

  3. (Pulsed electron beam precharger)

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. (ed.); Shelton, W.N.

    1990-01-01

    This report discusses the following topics on electron beam guns: Precharger Modification; Installation of Charge vs. Radius Apparatus; High Concentration Aerosol Generation; and Data Acquisition and Analysis System.

  4. Pulsed electron beam precharger

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. (ed.); Shelton, W.N.

    1991-01-01

    Electron beam precharging of a high resistivity aerosol was successfully demonstrated during this reporting period (Quarters Five and Six). The initial E-beam particle precharging experiments completed this term were designed to confirm and extend some of the work performed under the previous contract. There are several reasons for doing this: (1) to re-establish a baseline performance criterion for comparison to other runs, (2) to test several recently upgraded or repaired subsystems, and (3) to improve upon the collection efficiency of the electron beam precipitator when testing precharging effectiveness with a very high resistivity, moderate-to-high concentration dust load. In addition, these shakedown runs were used to determine a set of suitable operational parameters for the wind tunnel, the electrostatic collecting sections, and the MINACC E-beam accelerator. These parameters will generally be held constant while the precharging parameters are varied to produce an optimum particle charge.

  5. Pulsed electron beam precharger

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. (ed.); Shelton, W.N.

    1991-01-01

    During the previous reporting period (Quarter Six), the charging and removal of a fine, high resistivity aerosol using the advanced technology of electron beam precipitation was successfully accomplished. Precharging a dust stream circulating through the EBP wind tunnel produced collection efficiency figures of up to 40 times greater than with corona charging and collection alone (Table 1). The increased system collection efficiency attributed to electron beam precharging was determined to be the result of increased particle charge. It was found that as precharger electric field was raised, collection efficiency became greater. In sequence, saturation particle charge varies with the precharger electric field strength, particle migration velocity varies with the precharger and collector electric field, and collection efficiency varies with the migration velocity. Maximizing the system collection efficiency requires both a high charging electric field (provided by the E-beam precharger), and a high collecting electric field (provided by the collector wires and plates). Because increased particle collection efficiency is directly attributable to higher particle charge, the focus of research during Quarter Seven was shifted to learning more about the actual charge magnitude on the aerosol particles. Charge determinations in precipitators have traditionally been made on bulk dust samples collected from the flue gas stream, which gives an overall charge vs. mass (Q/M) ratio measurement. More recently, techniques have been developed which allow the measurement of the charge on individual particles in a rapid and repeatable fashion. One such advanced technique has been developed at FSU for use in characterizing the electron beam precharger.

  6. High current precision long pulse electron beam position monitor

    CERN Document Server

    Nelson, S D; Fessenden, T J; Holmes, C

    2000-01-01

    Precision high current long pulse electron beam position monitoring has typically experienced problems with high Q sensors, sensors damped to the point of lack of precision, or sensors that interact substantially with any beam halo thus obscuring the desired signal. As part of the effort to develop a multi-axis electron beam transport system using transverse electromagnetic stripline kicker technology, it is necessary to precisely determine the position and extent of long high energy beams for accurate beam position control (6 - 40 MeV, 1 - 4 kA, 2 μs beam pulse, sub millimeter beam position accuracy.) The kicker positioning system utilizes shot-to-shot adjustments for reduction of relatively slow (< 20 MHz) motion of the beam centroid. The electron beams passing through the diagnostic systems have the potential for large halo effects that tend to corrupt position measurements.

  7. Flue gas dry scrubbing using pulsed electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Penetrante, B.M.

    1996-02-20

    Electron beam dry scrubbing is a technique for removing in a single step both nitrogen oxides (NO{sub x}) and sulfur dioxide (SO{sub 2}) from the off-gas generated by utilities burning high sulfur coal. The use of pulsed electron beams may provide the most cost-effective solution to the implementation of this technique. This paper presents the results of plasma chemistry calculations to study the effect of dose rate, pulse length and pulse repetition rate on pulsed electron beam processing of NO{sub x} and SO{sub 2} in flue gases. The main objective is to determine if the proposed combinations of dose rate, pulse length and pulse repetition rate would have any deleterious effect on the utilization of radicals for pollutant removal. For a dose rate of 2x10{sup 5} megarads per second and a pulse length of 30 nanoseconds, the average dose per pulse is sufficiently low to prevent any deleterious effect on process efficiency because of radical-radical recombination reactions. During each post-pulse period, the radicals are utilized in the oxidation of NO{sub x} and SO{sub 2} in a timescale of around 200 microseconds; thus, with pulse frequencies of around 5 kilohertz or less, the radical concentrations remain sufficiently low to prevent any significant competition between radical-pollutant and radical-radical reactions. The main conclusion is that a pulsed electron beam reactor, operating with a dose rate of 2x10{sup 5} megarads per second, pulse length of 30 ns and pulse repetition rate of up to around 5 kHz, will have the same plasma chemistry efficiency as an electron beam reactor operating with a very low dose rate in continuous mode.

  8. Uses of pulsed electron beam to solid-states studies

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Noriaki; Nakayama, Takeyoshi; Tanimura, Katsumi; Chong, Taisu; Saidoh, Masahiro

    1982-03-01

    A survey is given on the use of the pulsed electron beams to studies of solid states. Even though main emphasis is placed on the studies carried out at the Faculty of Engineering, Nagoya University, using the Pulsed Electron Facilities installed in 1970, the works carried out at other institutes are also included. Only the studies of crystalline solids with simple structures, such as alkali halides and aromatic hydrocarbons are covered. In the first place several instrumentations which have extended utilities of pulsed-electron beams are presented. Then we discuss the studies of the dynamic of excitons, emphasizing the advantages and disadvantages of the usage of the electron pulses. Then usages of the pulsed-electron beam for the studies of the excited states of the quasi-stable defects are described. Application of the electron pulse for studies of the excitation spectroscopy of the photochemistry is described. The dynamic studies of defects introduced by electron-pulse bombardment is discussed finally. A summary is given, which includes also the possible future experiments.

  9. Cooling of relativistic electron beams in chirped laser pulses

    CERN Document Server

    Yoffe, Samuel R; Kravets, Yevgen; Jaroszynski, Dino A

    2015-01-01

    The next few years will see next-generation high-power laser facilities (such as the Extreme Light Infrastructure) become operational, for which it is important to understand how interaction with intense laser pulses affects the bulk properties of a relativistic electron beam. At such high field intensities, we expect both radiation reaction and quantum effects to play a significant role in the beam dynamics. The resulting reduction in relative energy spread (beam cooling) at the expense of mean beam energy predicted by classical theories of radiation reaction depends only on the energy of the laser pulse. Quantum effects suppress this cooling, with the dynamics additionally sensitive to the distribution of energy within the pulse. Since chirps occur in both the production of high-intensity pulses (CPA) and the propagation of pulses in media, the effect of using chirps to modify the pulse shape has been investigated using a semi-classical extension to the Landau--Lifshitz theory. Results indicate that even la...

  10. Surface modification of pure titanium by pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.D. [Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Laboratoired' Etude des Microstructures et de Mecanique des Materiaux (LEM3), CNRS UMR 7239, Universite Paul Verlaine - Metz, Ile du Saulcy, 57045 Metz (France); Hao, S.Z., E-mail: ebeam@dlut.edu.cn [Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Li, X.N. [Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Dong, C., E-mail: dong@dlut.edu.cn [Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Grosdidier, T., E-mail: Thierry.grosdidier@univ-metz.fr [Laboratoired' Etude des Microstructures et de Mecanique des Materiaux (LEM3), CNRS UMR 7239, Universite Paul Verlaine - Metz, Ile du Saulcy, 57045 Metz (France)

    2011-04-15

    The microstructure, hardness and corrosion resistance of commercially pure Ti treated by low energy high current pulsed electron beam (LEHCPEB) have been investigated. The thin near-surface melted layer rapidly solidified into {beta} and subsequently transformed into ultrafine {alpha}' martensite. This has led to a drastic improvement of the corrosion properties and a significant increase (more than 60%) in hardness of the top surface.

  11. Infrared imaging diagnostics for intense pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiao; Shen, Jie; Liu, Wenbin; Zhong, Haowen; Zhang, Jie; Zhang, Gaolong; Le, Xiaoyun, E-mail: xyle@buaa.edu.cn [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); International Research Center for Nuclei and Particles in the Cosmos, Beihang University, Beijing 100191 (China); Qu, Miao; Yan, Sha [Institute of Heavy Ion Physics, Peking University, Beijing 100871 (China)

    2015-08-15

    Infrared imaging diagnostic method for two-dimensional calorimetric diagnostics has been developed for intense pulsed electron beam (IPEB). By using a 100-μm-thick tungsten film as the infrared heat sink for IPEB, the emitting uniformity of the electron source can be analyzed to evaluate the efficiency and stability of the diode system. Two-dimensional axisymmetric finite element method heat transfer simulation, combined with Monte Carlo calculation, was performed for error estimation and optimization of the method. The test of the method was finished with IPEB generated by explosive emission electron diode with pulse duration (FWHM) of 80 ns, electron energy up to 450 keV, and a total beam current of over 1 kA. The results showed that it is possible to measure the cross-sectional energy density distribution of IPEB with energy sensitivity of 0.1 J/cm{sup 2} and spatial resolution of 1 mm. The technical details, such as irradiation protection of bremsstrahlung γ photons and the functional extensibility of the method were discussed in this work.

  12. Infrared imaging diagnostics for intense pulsed electron beam.

    Science.gov (United States)

    Yu, Xiao; Shen, Jie; Qu, Miao; Liu, Wenbin; Zhong, Haowen; Zhang, Jie; Yan, Sha; Zhang, Gaolong; Le, Xiaoyun

    2015-08-01

    Infrared imaging diagnostic method for two-dimensional calorimetric diagnostics has been developed for intense pulsed electron beam (IPEB). By using a 100-μm-thick tungsten film as the infrared heat sink for IPEB, the emitting uniformity of the electron source can be analyzed to evaluate the efficiency and stability of the diode system. Two-dimensional axisymmetric finite element method heat transfer simulation, combined with Monte Carlo calculation, was performed for error estimation and optimization of the method. The test of the method was finished with IPEB generated by explosive emission electron diode with pulse duration (FWHM) of 80 ns, electron energy up to 450 keV, and a total beam current of over 1 kA. The results showed that it is possible to measure the cross-sectional energy density distribution of IPEB with energy sensitivity of 0.1 J/cm(2) and spatial resolution of 1 mm. The technical details, such as irradiation protection of bremsstrahlung γ photons and the functional extensibility of the method were discussed in this work.

  13. 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

  14. Beam dynamics analysis in pulse compression using electron beam compact simulator for Heavy Ion Fusion

    Directory of Open Access Journals (Sweden)

    Kikuchi Takashi

    2013-11-01

    Full Text Available In a final stage of an accelerator system for heavy ion inertial fusion (HIF, pulse shaping and beam current increase by bunch compression are required for effective pellet implosion. A compact simulator with an electron beam was constructed to understand the beam dynamics. In this study, we investigate theoretically and numerically the beam dynamics for the extreme bunch compression in the final stage of HIF accelerator complex. The theoretical and numerical results implied that the compact experimental device simulates the beam dynamics around the stagnation point for initial low temperature condition.

  15. A 20 kV, 5 A, 1 ns Risetime Pulsed Electron Beam Source

    Institute of Scientific and Technical Information of China (English)

    Chen Yulan; Zeng Zhengzhong; Wang Haiyang; Ma Lianying

    2005-01-01

    A 20 kV, 1 ns risetime pulsed electron beam source was developed using an extremely small gap (0.1 mm) diode driven by a sub-nanosecond risetime, 10 kV rectangular pulse generator. A beam current of 5 A was detected by using a fast response Faraday cup at a distance of 2 cm away from a grid anode. The shot to shot variation of the electron beam pulse was less than 10%.

  16. Modeling of beam-target interaction during pulsed electron beam ablation of graphite: Case of melting

    Science.gov (United States)

    Ali, Muddassir; Henda, Redhouane

    2017-02-01

    A one-dimensional thermal model based on a two-stage heat conduction equation is employed to investigate the ablation of graphite target during nanosecond pulsed electron beam ablation. This comprehensive model accounts for the complex physical phenomena comprised of target heating, melting and vaporization upon irradiation with a polyenergetic electron beam. Melting and vaporization effects induced during ablation are taken into account by introducing moving phase boundaries. Phase transition induced during ablation is considered through the temperature dependent thermodynamic properties of graphite. The effect of electron beam efficiency, power density, and accelerating voltage on ablation is analyzed. For an electron beam operating at an accelerating voltage of 15 kV and efficiency of 0.6, the model findings show that the target surface temperature can reach up to 7500 K at the end of the pulse. The surface begins to melt within 25 ns from the pulse start. For the same process conditions, the estimated ablation depth and ablated mass per unit area are about 0.60 μm and 1.05 μg/mm2, respectively. Model results indicate that ablation takes place primarily in the regime of normal vaporization from the surface. The results obtained at an accelerating voltage of 15 kV and efficiency factor of 0.6 are satisfactorily in good accordance with available experimental data in the literature.

  17. Electron Beam Energy Compensation by Controlling RF Pulse Shape

    CERN Document Server

    Kii, T; Kusukame, K; Masuda, K; Nakai, Y; Ohgaki, H; Yamazaki, T; Yoshikawa, K; Zen, H

    2005-01-01

    We have studied on improvement of electron beam macropulse properties from a thermionic RF gun. Though a thermionic RF gun has many salient features, there is a serious problem that back-bombardment effect worsens quality of the beam. To reduce beam energy degradation by this effect, we tried to feed non-flat RF power into the gun. As a result, we successfully obtained about 1.5 times longer macropulse and two times larger total charge per macropulse. On the other hand, we calculated transient evolution of RF power considering non-constant beam loading. The beam loading is evaluated from time evolution of cathode temperature, by use of one dimensional heat conduction model and electron trajectories' calculations by a particle simulation code. Then we found good agreement between the experimental and calculation results. Furthermore, with the same way, we studied the electron beam output dependence on the cathode radius.

  18. Production and application of pulsed slow-positron beam using an electron LINAC

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, Tetsuo; Suzuki, Ryoichi; Ohdaira, Toshiyuki; Mikado, Tomohisa [Electrotechnical Lab., Tsukuba, Ibaraki (Japan); Kobayashi, Yoshinori

    1997-03-01

    Slow-positron beam is quite useful for non-destructive material research. At the Electrotechnical Laboratory (ETL), an intense slow positron beam line by exploiting an electron linac has been constructed in order to carry out various experiments on material analysis. The beam line can generates pulsed positron beams of variable energy and of variable pulse period. Many experiments have been carried out so far with the beam line. In this paper, various capability of the intense pulsed positron beam is presented, based on the experience at the ETL, and the prospect for the future is discussed. (author)

  19. Evolution of electron beam pulses of short duration in the solar corona

    Science.gov (United States)

    Casillas-Pérez, G. A.; Jeyakumar, S.; Pérez-Enríquez, H. R.; Trinidad, M. A.

    2016-11-01

    Narrowband radio bursts with durations of the order of milliseconds, called spikes, are known to be associated with solar flares. In order to understand the particle beams responsible for the radio spike phenomena, evolution of electron beam pulses injected from a solar flare region into the corona is studied. Numerical integration of the Fokker-Planck (FP) equation is used to follow the evolution of the electron beam pulse. The simulations show that the short duration pulses lose most of their energy within a second of propagation into the corona. Electron beam with a small low energy cut off is thermalized faster than that with a high low energy cut off.

  20. Optimization and control of electron beams from laser wakefield accelerations using asymmetric laser pulses

    Science.gov (United States)

    Gopal, K.; Gupta, D. N.

    2017-10-01

    Optimization and control of electron beam quality in laser wakefield acceleration are explored by using a temporally asymmetric laser pulse of the sharp rising front portion. The temporally asymmetric laser pulse imparts stronger ponderomotive force on the ambient plasma electrons. The stronger ponderomotive force associated with the asymmetric pulse significantly affects the injection of electrons into the wakefield and consequently the quality of the injected bunch in terms of injected charge, mean energy, and emittance. Based on particle-in-cell simulations, we report to generate a monoenergetic electron beam with reduced emittance and enhanced charge in laser wakefield acceleration using an asymmetric pulse of duration 30 fs.

  1. 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.

  2. Acceleration of injected electron beam by ultra-intense laser pulses with phase disturbances

    CERN Document Server

    Nakamura, T; Kato, S; Tanimoto, M; Koyama, K; Koga, J

    2003-01-01

    Acceleration of an injected electron beam by ultra-intense laser pulses with phase disturbances is investigated. The energy gain of the beam electrons depends on the initial energy of the injected electrons in the stochastic acceleration process. The effect is larger for electrons with some injection energy as opposed to electrons with no initial energy. The corresponding accelerating field for electrons having certain amounts of initial energy becomes larger than that of the standard wakefield. (author)

  3. Experimental investigation of electron beam wave interactions utilising short pulses

    CERN Document Server

    Wiggins, S M

    2000-01-01

    Experiments have investigated the production of ultra-short electromagnetic pulses and their interaction with electrons in various resonant structures. Diagnostic systems used in the measurements included large bandwidth detection systems for capturing the short pulses. Deconvolution techniques have been applied to account for bandwidth limitation of the detection systems and to extract the actual pulse amplitudes and durations from the data. A Martin-Puplett interferometer has been constructed for use as a Fourier transform spectrometer. The growth of superradiant electromagnetic spikes from short duration (0.5-1.0 ns), high current (0.6-2.0 kA) electron pulses has been investigated in a Ka-band Cherenkov maser and Ka- and W-band backward wave oscillators (BWO). In the Cherenkov maser, radiation spikes were produced with a peak power = 70 ps and a bandwidth <= 19 %. It is shown that coherent spontaneous emission from the leading edge of the electron pulse drives these interactions, giving rise to self-amp...

  4. Pulse-by-pulse multi-beam-line operation for x-ray free-electron lasers

    Directory of Open Access Journals (Sweden)

    Toru Hara

    2016-02-01

    Full Text Available The parallel operation of plural undulator beam lines is an important means of improving the efficiency and usability of x-ray free-electron laser facilities. After the installation of a second undulator beam line (BL2 at SPring-8 Angstrom compact free-electron laser (SACLA, pulse-by-pulse switching between two beam lines was tested using kicker and dc twin-septum magnets. To maintain a compact size, all undulator beam lines at SACLA are designed to be placed within the same undulator hall located downstream of the accelerator. In order to ensure broad tunability of the laser wavelength, the electron bunches are accelerated to different beam energies optimized for the wavelengths of each beam line. In the demonstration, the 30 Hz electron beam was alternately deflected to two beam lines and simultaneous lasing was achieved with 15 Hz at each beam line. Since the electron beam was deflected twice by 3° in a dogleg to BL2, the coherent synchrotron radiation (CSR effects became non-negligible. Currently in a wavelength range of 4–10 keV, a laser pulse energy of 100–150  μJ can be obtained with a reduced peak current of around 1 kA by alleviating the CSR effects. This paper reports the results and operational issues related to the multi-beam-line operation of SACLA.

  5. On the response of electronic personal dosimeters in constant potential and pulsed X-ray beams

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, Margarete C.; Silva, Teogenes; Silva, Claudete R.E., E-mail: margaretecristinag@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Oliveira, Paulo Marcio C. de [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Anatomia e Imagem

    2015-07-01

    Electronic personal dosimeters (EPDs) based on solid state detectors have widely been used but some deficiencies in their response in pulsed radiation beams have been reported. Nowadays, there is not an international standard for pulsed X-ray beams for calibration or type testing of dosimeters. Irradiation conditions for testing the response of EPDs in both the constant potential and pulsed X-ray beams were established in CDTN. Three different types of EPDs were tested in different conditions in similar ISO and IEC X-ray qualities. Results stressed the need of performing additional checks before using EPDs in constant potential or pulsed X-rays. (author)

  6. On the response of electronic personal dosimeters in constant potential and pulsed x- ray beams

    Science.gov (United States)

    Guimarães, M. C.; Silva, C. R. E.; Oliveira, P. M. C.; da Silva, T. A.

    2016-07-01

    Electronic personal dosimeters (EPDs) based on solid state detectors have widely been used but some deficiencies in their response in pulsed radiation beams have been reported. Nowadays, there is not an international standard for pulsed x-ray beams for calibration or type testing of dosimeters. Irradiation conditions for testing the response of EPDs in both the constant potential and pulsed x-ray beams were established in CDTN. Three different types of EPDs were tested in different conditions in similar ISO and IEC x-ray qualities. Results stressed the need of performing additional checks before using EPDs in constant potential or pulsed x-rays.

  7. Electron molecular beam epitaxy: Layer-by-layer growth of complex oxides via pulsed electron-beam deposition

    Energy Technology Data Exchange (ETDEWEB)

    Comes, Ryan; Liu Hongxue; Lu Jiwei [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Gu, Man [Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States); Khokhlov, Mikhail; Wolf, Stuart A. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Guilford College, Greensboro, North Carolina 27410 (United States)

    2013-01-14

    Complex oxide epitaxial film growth is a rich and exciting field, owing to the wide variety of physical properties present in oxides. These properties include ferroelectricity, ferromagnetism, spin-polarization, and a variety of other correlated phenomena. Traditionally, high quality epitaxial oxide films have been grown via oxide molecular beam epitaxy or pulsed laser deposition. Here, we present the growth of high quality epitaxial films using an alternative approach, the pulsed electron-beam deposition technique. We demonstrate all three epitaxial growth modes in different oxide systems: Frank-van der Merwe (layer-by-layer); Stranski-Krastanov (layer-then-island); and Volmer-Weber (island). Analysis of film quality and morphology is presented and techniques to optimize the morphology of films are discussed.

  8. Electron molecular beam epitaxy: Layer-by-layer growth of complex oxides via pulsed electron-beam deposition

    Science.gov (United States)

    Comes, Ryan; Gu, Man; Khokhlov, Mikhail; Liu, Hongxue; Lu, Jiwei; Wolf, Stuart A.

    2013-01-01

    Complex oxide epitaxial film growth is a rich and exciting field, owing to the wide variety of physical properties present in oxides. These properties include ferroelectricity, ferromagnetism, spin-polarization, and a variety of other correlated phenomena. Traditionally, high quality epitaxial oxide films have been grown via oxide molecular beam epitaxy or pulsed laser deposition. Here, we present the growth of high quality epitaxial films using an alternative approach, the pulsed electron-beam deposition technique. We demonstrate all three epitaxial growth modes in different oxide systems: Frank-van der Merwe (layer-by-layer); Stranski-Krastanov (layer-then-island); and Volmer-Weber (island). Analysis of film quality and morphology is presented and techniques to optimize the morphology of films are discussed.

  9. The Reduction of NOx Using Pulsed Electron Beams

    Science.gov (United States)

    2015-12-30

    instantly with oxygen to form the brown gas NO2. Nitrogen dioxide is toxic. Dinitrogen trioxide (N2O3) exists as a deep blue solid (-21°C), but is...equilibrium constant for this reaction is plotted in Figure 2 (solid blue line) as a function of temperature in degrees Centigrade. The temperature range on...Swanekamp, D. Weidenheimer, D. Welch, D.V. Rose , and S. Searles, “Electron Beam Pumped KrF Lasers for Fusion Energy,” Phys. Plasmas 10, 2142 (2003

  10. Pulse-periodic generation of supershort avalanche electron beams and X-ray emission

    Science.gov (United States)

    Baksht, E. Kh.; Burachenko, A. G.; Erofeev, M. V.; Tarasenko, V. F.

    2014-05-01

    Pulse-periodic generation of supershort avalanche electron beams (SAEBs) and X-ray emission in nitrogen, as well as the transition from a single-pulse mode to a pulse-periodic mode with a high repetition frequency, was studied experimentally. It is shown that, in the pulse-periodic mode, the full width at halfmaximum of the SAEB is larger and the decrease rate of the gap voltage is lower than those in the single-pulse mode. It is found that, when the front duration of the voltage pulse at a nitrogen pressure of 90 Torr decreases from 2.5 to 0.3 ns, the X-ray exposure dose in the pulse-periodic mode increases by more than one order of magnitude and the number of SAEB electrons also increases. It is shown that, in the pulse-periodic mode of a diffuse discharge, gas heating in the discharge gap results in a severalfold increase in the SAEB amplitude (the number of electrons in the beam). At a generator voltage of 25 kV, nitrogen pressure of 90 Torr, and pulse repetition frequency of 3.5 kHz, a runaway electron beam was detected behind the anode foil.

  11. Effect of pulsed hollow electron-lens operation on the proton beam core in LHC

    CERN Document Server

    Fitterer, Miriam; Valishev, Alexander

    2016-01-01

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the HL-LHC. In order to further increase the diffusion rates for a fast halo removal as e.g. desired before the squeeze, the electron lens (e-lens) can be operated in pulsed mode. In case of profile imperfections in the electron beam the pulsing of the e-lens induces noise on the proton beam which can, depending on the frequency content and strength, lead to emittance growth. In order to study the sensitivity to the pulsing pattern and the amplitude, a beam study (machine development MD) at the LHC has been proposed for August 2016 and we present in this note the preparatory simulations and estimates.

  12. Pulse-mode measurement of electron beam halo using diamond-based detector

    Science.gov (United States)

    Aoyagi, Hideki; Asano, Yoshihiro; Itoga, Toshiro; Nariyama, Nobuteru; Bizen, Teruhiko; Tanaka, Takashi; Kitamura, Hideo

    2012-02-01

    Using a diamond-based detector, the electron beam halo in a high-energy accelerator can be measured with a lower detection limit than that using other instruments, such as a core monitor, a dose meter, or an optical fiber. We have successfully measured an electron beam halo using diamond-based detectors operating in the ionization mode, which were installed in the beam duct to measure the intensity of the beam halo directly. Pulse-by-pulse measurements were adopted to suppress the background noise efficiently. Feasibility tests on the diamond-based detector and beam halo monitor were performed in the beam dump area of the 8 GeV SPring-8 synchrotron booster and at the 250 MeV SPring-8 Compact SASE Source test accelerator for the SPring-8 Angstrom Compact free electron LAser (SACLA), respectively. We achieved a lower detection limit of 2×103electrons/pulse for single-shot measurement, which corresponds to a ratio of about 10-6 relative to the typical charge of the beam core of 0.3 pC. We also confirmed the feasibility of the electron beam halo monitor for use as an interlock sensor to protect undulator permanent magnets used in SACLA from radiation damage.

  13. Pulse-mode measurement of electron beam halo using diamond-based detector

    Directory of Open Access Journals (Sweden)

    Hideki Aoyagi

    2012-02-01

    Full Text Available Using a diamond-based detector, the electron beam halo in a high-energy accelerator can be measured with a lower detection limit than that using other instruments, such as a core monitor, a dose meter, or an optical fiber. We have successfully measured an electron beam halo using diamond-based detectors operating in the ionization mode, which were installed in the beam duct to measure the intensity of the beam halo directly. Pulse-by-pulse measurements were adopted to suppress the background noise efficiently. Feasibility tests on the diamond-based detector and beam halo monitor were performed in the beam dump area of the 8 GeV SPring-8 synchrotron booster and at the 250 MeV SPring-8 Compact SASE Source test accelerator for the SPring-8 Angstrom Compact free electron LAser (SACLA, respectively. We achieved a lower detection limit of 2×10^{3}  electrons/pulse for single-shot measurement, which corresponds to a ratio of about 10^{-6} relative to the typical charge of the beam core of 0.3 pC. We also confirmed the feasibility of the electron beam halo monitor for use as an interlock sensor to protect undulator permanent magnets used in SACLA from radiation damage.

  14. Energy-spread measurement of triple-pulse electron beams based on the magnetic dispersion principle

    CERN Document Server

    Wang, Yi; Yang, Zhiyong; Zhang, Huang; Ding, Hengsong; Yang, Anmin; Wang, Minhong

    2016-01-01

    The energy-spread of the triple-pulse electron beam generated by the Dragon-II linear induction accelerator is measured using the method of energy dispersion in the magnetic field. A sector magnet is applied for energy analyzing of the electron beam, which has a bending radius of 300 mm and a deflection angle of 90 degrees. For each pulse, both the time-resolved and the integral images of the electron position at the output port of the bending beam line are recorded by a streak camera and a CCD camera, respectively. Experimental results demonstrate an energy-spread of less than +-2.0% for the electron pulses. The cavity voltage waveforms obtained by different detectors are also analyzed for comparison.

  15. Transient Self-Amplified Cerenkov Radiation with a Short Pulse Electron Beam

    Energy Technology Data Exchange (ETDEWEB)

    Poole, B R; Blackfield, D T; Camacho, J F

    2009-01-22

    An analytic and numerical examination of the slow wave Cerenkov free electron maser is presented. We consider the steady state amplifier configuration as well as operation in the selfamplified spontaneous emission (SASE) regime. The linear theory is extended to include electron beams that have a parabolic radial density inhomogeneity. Closed form solutions for the dispersion relation and modal structure of the electromagnetic field are determined in this inhomogeneous case. To determine the steady state response, a macro-particle approach is used to develop a set of coupled nonlinear ordinary differential equations for the amplitude and phase of the electromagnetic wave, which are solved in conjunction with the particle dynamical equations to determine the response when the system is driven as an amplifier with a time harmonic source. We then consider the case in which a fast rise time electron beam is injected into a dielectric loaded waveguide. In this case, radiation is generated by SASE, with the instability seeded by the leading edge of the electron beam. A pulse of radiation is produced, slipping behind the leading edge of the beam due to the disparity between the group velocity of the radiation and the beam velocity. Short pulses of microwave radiation are generated in the SASE regime and are investigated using particle-in-cell (PIC) simulations. The nonlinear dynamics are significantly more complicated in the transient SASE regime when compared with the steady state amplifier model due to the slippage of the radiation with respect to the beam. As strong self-bunching of the electron beam develops due to SASE, short pulses of superradiant emission develop with peak powers significantly larger than the predicted saturated power based on the steady state amplifier model. As these superradiant pulses grow, their pulse length decreases and forms a series of soliton-like pulses. Comparisons between the linear theory, macro-particle model, and PIC simulations are

  16. Lateral resolution in focused electron beam-induced deposition: scaling laws for pulsed and static exposure

    Energy Technology Data Exchange (ETDEWEB)

    Szkudlarek, Aleksandra [Empa, Laboratory for Mechanics of Materials and Nanostructures, Thun (Switzerland); AGH University of Science and Technology, Department of Solid State Physics, Faculty of Physics and Applied Computer Science, Krakow (Poland); Szmyt, Wojciech; Kapusta, Czeslaw [AGH University of Science and Technology, Department of Solid State Physics, Faculty of Physics and Applied Computer Science, Krakow (Poland); Utke, Ivo [Empa, Laboratory for Mechanics of Materials and Nanostructures, Thun (Switzerland)

    2014-12-15

    In this work, we review the single-adsorbate time-dependent continuum model for focused electron beam-induced deposition (FEBID). The differential equation for the adsorption rate will be expressed by dimensionless parameters describing the contributions of adsorption, desorption, dissociation, and the surface diffusion of the precursor adsorbates. The contributions are individually presented in order to elucidate their influence during variations in the electron beam exposure time. The findings are condensed into three new scaling laws for pulsed exposure FEBID (or FEB-induced etching) relating the lateral resolution of deposits or etch pits to surface diffusion and electron beam exposure dwell time for a given adsorbate depletion state. (orig.)

  17. Plasma electron source for the generation of wide-aperture pulsed beam at forevacuum pressures

    Energy Technology Data Exchange (ETDEWEB)

    Oks, E.; Burdovitsin, V.; Medovnik, A.; Yushkov, Yu. [Tomsk State University of Control Systems and Radioelectronics, Tomsk 634050 (Russian Federation)

    2013-02-15

    This article reports on design and application of wide-aperture pulsed beam source, based on hollow cathode discharge. The source is intended for electron beam generation in pressure range 2-15 Pa. Multi-aperture extraction system, used in a source, provided beam cross-section uniformity of 10% on diameter 40 mm. The limiting values of the current density, pulse duration, and accelerating voltage are 350 mA/cm{sup 2}, 250 {mu}s, and 10 kV, respectively. These parameters are sufficient for surface modification of various materials, including non-conducting matters.

  18. Constraints on photon pulse duration from longitudinal electron beam diagnostics at a soft x-ray free-electron laser

    Directory of Open Access Journals (Sweden)

    C. Behrens

    2012-03-01

    Full Text Available The successful operation of x-ray free-electron lasers (FELs, like the Linac Coherent Light Source or the Free-Electron Laser in Hamburg (FLASH, makes unprecedented research on matter at atomic length and ultrafast time scales possible. However, in order to take advantage of these unique light sources and to meet the strict requirements of many experiments in photon science, FEL photon pulse durations need to be known and tunable. This can be achieved by controlling the FEL driving electron beams, and high-resolution longitudinal electron beam diagnostics can be utilized to provide constraints on the expected FEL photon pulse durations. In this paper, we present comparative measurements of soft x-ray pulse durations and electron bunch lengths at FLASH. The soft x-ray pulse durations were measured by FEL radiation pulse energy statistics and compared to electron bunch lengths determined by frequency-domain spectroscopy of coherent transition radiation in the terahertz range and time-domain longitudinal phase space measurements. The experimental results, theoretical considerations, and simulations show that high-resolution longitudinal electron beam diagnostics provide reasonable constraints on the expected FEL photon pulse durations. In addition, we demonstrated the generation of soft x-ray pulses with durations below 50 fs (FWHM after the implementation of the new uniform electron bunch compression scheme used at FLASH.

  19. Application of strongly focused pulsed electron beam for the reaction wheels balancing

    Science.gov (United States)

    Borduleva, A. O.; Bleykher, G. A.; Solovev, V. V.; Krivobokov, V. P.; Babihina, M. N.

    2016-11-01

    In the given work the material removing possibility by the strongly focused pulsed electron beam was investigated. The optimal mode of flywheels balancing was found. At this mode the power density is 1.6 MW/cm2 and pulse duration is 0.65 s. At such parameters the evaporation rate is equal to 11 g/scm2. It is possible to vary the amount of remote material from 1 to 100 mg, that is sufficient to balance flywheel. It is found that treatment by an electron beam does not change the material structure.

  20. 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.

  1. A Technique for Temperature and Ultimate Load Calculations of Thin Targets in a Pulsed Electron Beam

    DEFF Research Database (Denmark)

    Hansen, Jørgen-Walther; Lundsager, Per

    1979-01-01

    A technique is presented for the calculation of transient temperature distributions and ultimate load of rotationally symmetric thin membranes with uniform lateral load and exposed to a pulsed electron beam from a linear accelerator. Heat transfer by conduction is considered the only transfer...

  2. Low energy high current pulsed electron beam treatment for improving surface microstructure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J; Allain-Bonasso, N; Zhang, X D; Hao, S Z; Grosdider, T; Dong, C [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, UMR-CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Zou, J X, E-mail: jiang.wu@univ-metz.fr, E-mail: thierry.grosdidier@univ-metz.fr [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-06-15

    Low energy high current pulsed electron beam (LEHCPEB) is a fairly new technique for surface modifications authorizing improvement in wear and corrosion properties as well as texture changes and hardening. This contribution highlights some microstructure modifications encountered at the surface of HCPEB treated steels and bulk metallic glasses taking into account the effects of surface melting and the effects of the induced stress.

  3. Pulsed Electron Beam Spectroscopy for Temperature Measurements in Hypersonic Flows

    Science.gov (United States)

    2010-01-01

    as rotational-level dependent, so the proper modeling of k i can be important as temperature changes and if tem perature measurements based on the...through a hy drogen thyratron switch into the primary of a step-up transformer. A limited number of off-th e-shelf prod ucts perfor ming the function...of a thyratron drive for pulse switching were identifie d, but none met the specialize d power a nd switchin g wavefor m requirements of the pulsed

  4. Physics of Neutralization of Intense High-Energy Ion Beam Pulses by Electrons

    Energy Technology Data Exchange (ETDEWEB)

    Kaganovich, I. D.; Davidson, R. C.; Dorf, M. A.; Startsev, E. A.; Sefkow, A. B.; Lee, E. P.; Friedman, A.

    2010-04-28

    Neutralization and focusing of intense charged particle beam pulses by electrons forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self- magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating through the

  5. Synthesis of substituted lithium ferrites under the pulsed and continuous electron beam heating

    Science.gov (United States)

    Lysenko, Elena N.; Surzhikov, Anatoliy P.; Vlasov, Vitaliy A.; Nikolaev, Evgeniy V.; Malyshev, Andrey V.; Bryazgin, Alexandr A.; Korobeynikov, Mikhail V.; Mikhailenko, Mikhail A.

    2017-02-01

    Synthesis of substituted lithium ferrites with chemical formulas Li0.6Fe2.2Ti0.2O4 and Li0.649Fe1.598Ti0.5Zn0.2Mn0.051O4 under the pulsed and continuous electron beam heating was investigated by X-ray diffraction and thermomagnetometric analysis. The electron beams heating of Li2CO3-Fe2O3-TiO2 or Li2CO3-ZnO-Fe2O3-TiO2-MnO mixtures was carried out at a temperature of 750 °C during 60 min using two types of electron accelerators: ELV accelerator generating continuous electron beam or ILU-6 accelerator generating pulse electron beam. It was established that a high energy electron beam heating of initial reagents mixtures allows obtaining the substituted lithium ferrites with final composition at significantly lower temperatures (at least 200 °C lower than in the case of using traditional thermal synthesis) and times of synthesis. That statement is in agreement with results obtained by XRD analysis, showing single phase formation; by magnetic measurements, showing high values of specific magnetization; by DTG measurements showing the certain Curie temperatures of the synthesized samples.

  6. Longitudinal and transverse cooling of relativistic electron beams in intense laser pulses

    CERN Document Server

    Yoffe, Samuel R; Noble, Adam; Jaroszynski, Dino A

    2015-01-01

    With the emergence in the next few years of a new breed of high power laser facilities, it is becoming increasingly important to understand how interacting with intense laser pulses affects the bulk properties of a relativistic electron beam. A detailed analysis of the radiative cooling of electrons indicates that, classically, equal contributions to the phase space contraction occur in the transverse and longitudinal directions. In the weakly quantum regime, in addition to an overall reduction in beam cooling, this symmetry is broken, leading to significantly less cooling in the longitudinal than the transverse directions. By introducing an efficient new technique for studying the evolution of a particle distribution, we demonstrate the quantum reduction in beam cooling, and find that it depends on the distribution of energy in the laser pulse, rather than just the total energy as in the classical case.

  7. Electrostatic diagnostics of nanosecond pulsed electron beams in a Malmberg-Penning trap

    Energy Technology Data Exchange (ETDEWEB)

    Paroli, B.; Bettega, G.; Maero, G.; Rome, M. [Dipartimento di Fisica and I.N.F.N. Sezione di Milano, Universita degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Norgia, M.; Pesatori, A.; Svelto, C. [Dipartimento di Elettronica e Informazione del Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2010-06-15

    A fast electrostatic diagnostic and analysis scheme on nanosecond pulsed beams in the keV energy range has been developed in the Malmberg-Penning trap ELTRAP. Low-noise electronics has been used for the detection of small induced current signals on the trap electrodes. A discrete wavelet-based procedure has been implemented for data postprocessing. The development of an effective electrostatic diagnostics together with proper data analysis techniques is of general interest in view of deducing the beam properties through comparison of the postprocessed data with the theoretically computed signal shape, which contains beam radius, length, and average density as fit parameters.

  8. Electrostatic diagnostics of nanosecond pulsed electron beams in a Malmberg-Penning trap.

    Science.gov (United States)

    Paroli, B; Bettega, G; Maero, G; Romé, M; Norgia, M; Pesatori, A; Svelto, C

    2010-06-01

    A fast electrostatic diagnostic and analysis scheme on nanosecond pulsed beams in the keV energy range has been developed in the Malmberg-Penning trap ELTRAP. Low-noise electronics has been used for the detection of small induced current signals on the trap electrodes. A discrete wavelet-based procedure has been implemented for data postprocessing. The development of an effective electrostatic diagnostics together with proper data analysis techniques is of general interest in view of deducing the beam properties through comparison of the postprocessed data with the theoretically computed signal shape, which contains beam radius, length, and average density as fit parameters.

  9. Simulation calculation for the energy deposition profile and the transmission fraction of intense pulsed electron beam at various incident angles

    CERN Document Server

    Yang Hai Liang; Zhang Jia Sheng; Huang Jian Jun; Sun Jian Feng

    2002-01-01

    The incident angles have a heavy effect on the intense pulsed electron beam energy deposition profile, energy deposition fraction and beam current transmission fraction in material. The author presents electron beam energy deposition profile and energy deposition fraction versus electron energy (0.5-2.0 MeV), at various incident angles for three aluminum targets of various thickness via theoretical calculation. The intense pulsed electron beam current transmission fractions versus electron energy (0.4-1.4 MeV) at various incident angles for three thickness of carbon targets were also theoretically calculated. The calculation results indicate that the deposition energy in unit mass of material surface layer increase with the rise of electron beam incident angle, and electron beam with low incident angle (closer to normal incident angle) penetrates deeper into the target material. The electron beams deposit more energy in unit mass of material surface layer at 60 degree-70 degree incident angle

  10. Laser sources for polarized electron beams in cw and pulsed accelerators

    CERN Document Server

    Hatziefremidis, A; Fraser, D; Avramopoulos, H

    1999-01-01

    We report the characterization of a high power, high repetition rate, mode-locked laser system to be used in continuous wave and pulsed electron accelerators for the generation of polarized electron beams. The system comprises of an external cavity diode laser and a harmonically mode-locked Ti:Sapphire oscillator and it can provide up to 3.4 W average power, with a corresponding pulse energy exceeding 1 nJ at 2856 MHz repetition rate. The system is tunable between 770-785 and 815-835 nm with two sets of diodes for the external cavity diode laser. (author)

  11. Pulsed electron beam propagation in gases under pressure of 6.6 kPa in drift tube

    Science.gov (United States)

    Kholodnaya, G. E.; Sazonov, R. V.; Ponomarev, D. V.; Remnev, G. E.; Poloskov, A. V.

    2017-02-01

    This paper presents the results of an investigation of pulsed electron beam transport propagated in a drift tube filled with different gases (He, H2, N2, Ar, SF6, and CO2). The total pressure in the drift tube was 6.6 kPa. The experiments were carried out using a TEA-500 pulsed electron accelerator. The electron beam was propagated in the drift tube composed of two sections equipped with reverse current shunts. Under a pressure of 6.6 kPa, the maximum value of the electron beam charge closed on the walls of the drift tube was recorded when the beam was propagated in hydrogen and carbon dioxide. The minimum value of the electron beam charge closed on the walls of the drift tube was recorded for sulfur hexafluoride. The visualization of the pulsed electron beam energy losses onto the walls of the drift chamber was carried out using radiation-sensitive film.

  12. Cooling of relativistic electron beams in intense laser pulses: Chirps and radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yoffe, S.R., E-mail: sam.yoffe@strath.ac.uk; Noble, A., E-mail: adam.noble@strath.ac.uk; Macleod, A.J., E-mail: alexander.macleod@strath.ac.uk; Jaroszynski, D.A., E-mail: d.a.jaroszynski@strath.ac.uk

    2016-09-01

    Next-generation high-power laser facilities (such as the Extreme Light Infrastructure) will provide unprecedented field intensities, and will allow us to probe qualitatively new physical regimes for the first time. One of the important fundamental questions which will be addressed is particle dynamics when radiation reaction and quantum effects play a significant role. Classical theories of radiation reaction predict beam cooling in the interaction of a relativistic electron bunch and a high-intensity laser pulse, with final-state properties only dependent on the laser fluence. The observed quantum suppression of this cooling instead exhibits a dependence on the laser intensity directly. This offers the potential for final-state properties to be modified or even controlled by tailoring the intensity profile of the laser pulse. In addition to beam properties, quantum effects will be manifest in the emitted radiation spectra, which could be manipulated for use as radiation sources. We compare predictions made by classical, quasi-classical and stochastic theories of radiation reaction, and investigate the influence of chirped laser pulses on the observed radiation spectra. - Highlights: • Classical theories of radiation reaction predict electron beam cooling in high fields. • Quantum effects lead to a reduction in electron beam cooling. • Quasi-classical model agrees with predictions from a single-emission stochastic model. • Negative frequency chirp found to increase photon emission, but not maximum energy.

  13. Laser-driven electron beam generation for secondary photon sources with few terawatt laser pulses

    Science.gov (United States)

    Bohacek, K.; Chaulagain, U.; Horny, V.; Kozlova, M.; Krus, M.; Nejdl, J.

    2017-05-01

    Relativistic electron beams accelerated by laser wakefield have the ability to serve as sources of collimated, point-like and femtosecond X-ray radiation. Experimental conditions for generation of stable quasi-monoenergetic electron bunches using a femtosecond few-terawatt laser pulse (600 mJ, 50 fs) were investigated as they are crucial for generation of stable betatron radiation and X-ray pulses from inverse Compton scattering. A mixture of helium with argon, and helium with an admixture of synthetic air were tested for this purpose using different backing pressures and the obtained results are compared. The approach to use synthetic air was previously proven to stabilize the energy and energy spread of the generated electron beams at the given laser power. The accelerator was operated in nonlinear regime with forced self-injection and resulted in the generation of stable relativistic electron beams with an energy of tens of MeV and betatron X-ray radiation was generated in the keV range. A razor blade was tested to create a steep density gradient in order to improve the stability of electron injection and to increase the total electron bunch charge. It was proven that the stable electron and X-ray source can be built at small-scale facilities, which readily opens possibilities for various applications due to availability of such few-terawatt laser systems in many laboratories around the world.

  14. Dosimetric response for crystalline and nanostructured aluminium oxide to a high-current pulse electron beam.

    Science.gov (United States)

    Nikiforov, S V; Kortov, V S

    2014-11-01

    The main thermoluminescent (TL) and dosimetric properties of the detectors based on anion-defective crystalline and nanostructured aluminium oxide after exposure to a high-current pulse electron beam are studied. TL peaks associated with deep-trapping centres are registered. It is shown that the use of deep-trap TL at 200-600°С allows registering absorbed doses up to 750 kGy for single-crystalline detectors and those up to 6 kGy for nanostructured ones. A wide range of the doses registered, high reproducibility of the TL signal and low fading contribute to a possibility of using single-crystalline and nanostructured aluminium oxide for the dosimetry of high-current pulse electron beams.

  15. Styrene vapor decomposition in air under the action a pulse electron beam

    CERN Document Server

    Mesyats, G A; Filatov, I E

    2001-01-01

    The results of experiments on the styrene vapor removal from the air through the pulse electron beam of the nanosecond duration and also through the nonindependent voluminous discharge are presented. The macrokinetic equations of the process obtained on the basis of these results, make it possible to systematize the data and also extrapolate them beyond the boundaries of the studied area of concentrations and energy, contained in the gas

  16. Electron-Beam Switches For A High Peak Power Sled-II Pulse Compressor

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay, L. [Yale Univ., New Haven, CT (United States)

    2015-12-02

    Omega-P demonstrated triggered electron-beam switches on the L=2 m dual-delay-line X-band pulse compressor at Naval Research Laboratory (NRL). In those experiments, with input pulses of up to 9 MW from the Omega-P/NRL X-band magnicon, output pulses having peak powers of 140-165 MW and durations of 16-20 ns were produced, with record peak power gains M of 18-20. Switch designs are described based on the successful results that should be suitable for use with the existing SLAC SLED-II delay line system, to demonstrate C=9, M=7, and n>>78%, yielding 173ns compressed pulses with peak powers up to 350MW with input of a single 50-MW.

  17. Effect of pulse electron beam characteristics on internal friction and structural alterations in epoxy

    Energy Technology Data Exchange (ETDEWEB)

    Zaikin, Yu.A. [Al Farabi Kazakh National University, Almaty (Kazakhstan)]. E-mail: drzaykin@mail.ru; Ismailova, G.A. [Al Farabi Kazakh National University, Almaty (Kazakhstan); Al-Sheikhly, M. [University of Maryland, College Park (United States)

    2007-08-15

    Temperature dependence of internal friction is experimentally studied in epoxy irradiated by 2.5 MeV pulse electron beam to different doses. Time dependence of internal friction characteristics associated with radiation-induced processes of polymer scission and cross-linking is analyzed and discussed. Experimental data on kinetics of structural transformations in epoxy are interpreted on the base of analytical solutions of differential equations for free radical accumulation during and after irradiation subject to the pulse irradiation mode and an arbitrary effective order of radical recombination.

  18. Pulsed electron beam precharger. Technical progress report No. 5, September 1--November 30, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. [ed.; Shelton, W.N.

    1990-12-31

    Electrostatic collection of a high resistivity aerosol using the Electron Beam Precipitator (EBP) collecting section was demonstrated during this reporting period (Quarter Five). Collection efficiency experiments were designed to confirm and extend some of the work performed under the previous contract. The reason for doing this was to attempt to improve upon the collection efficiency of the precipitator alone when testing with a very high resistivity, moderate-to-high concentration dust load. From the collector shakedown runs, a set of suitable operational parameters were determined for the downstream electrostatic collecting sections of the Electron Beam Precipitator wind tunnel. These parameters, along with those for the MINACC electron beam, will generally be held constant while the numerous precharging parameters are varied to produce an optimum particle charge. The electrostatic collector experiments were part of a larger, comprehensive investigation on electron beam precharging of high resistivity aerosol particles performed during the period covered by Quarters Five, Six, and Seven. This body of work used the same experimental apparatus and procedures and the experimental run period lasted nearly continuously for six months. A summary of the Quarter Five work is presented in the following paragraphs. Section II-A of TPR 5 contains a report on the continuing effort which was expended on the modification and upgrade of the pulsed power supply and the monitoring systems prior to the initiation of the electron beam precharging experimental work.

  19. Improving oxidation resistance and thermal insulation of thermal barrier coatings by intense pulsed electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Mei Xianxiu, E-mail: xxmei@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); Liu Xiaofei; Wang Cunxia; Wang Younian; Dong Chuang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Pulsed electron beam was used for sealing ZrO{sub 2} thermal barrier coating prepared by electron beam-physical vapor deposition. Black-Right-Pointing-Pointer At irradiation energy densities above 8 J/cm{sup 2}, ZrO{sub 2} ceramic coating surface was fully re-melted and became smooth, dense and shiny. Black-Right-Pointing-Pointer The thermal diffusion rate of the irradiated coating was decreased. Black-Right-Pointing-Pointer Thermal insulation properties and high temperature oxidation resistance were improved. - Abstract: In this paper, intense pulsed electron beam was used for the irradiation treatment of 6-8% Y{sub 2}O{sub 3}-stablized ZrO{sub 2} thermal barrier coating prepared by electron beam-physical vapor deposition to achieve the 'sealing' of columnar crystals, thus improving their thermal insulation properties and high temperature oxidation resistance. The electron beam parameters used were: pulse duration 200 {mu}s, electron voltage 15 kV, energy density 3, 5, 8, 15, 20 J/cm{sup 2}, and pulsed numbers 30. 1050 Degree-Sign C cyclic oxidation and static oxidation experiments were used for the research on oxidation resistance of the coatings. When the energy density of the electron beam was larger than 8 J/cm{sup 2}, ZrO{sub 2} ceramic coating surface was fully re-melted and became smooth, dense and shiny. The coating changed into a smooth polycrystalline structure, thus achieving the 'sealing' effect of the columnar crystals. After irradiations with the energy density of 8-15 J/cm{sup 2}, the thermally grown oxide coating thickness decreased significantly in comparison with non-irradiated coatings, showing that the re-melted coating improved the oxidation resistance of the coatings. The results of thermal diffusivity test by laser flash method showed that the thermal diffusion rate of the irradiated coating was lower than that of the coating without irradiation treatment, and the thermal

  20. Characterization of a pulsed electron beam with a planar charge collector

    Energy Technology Data Exchange (ETDEWEB)

    Paroli, B; Bettega, G; Cavaliere, F; De Luca, F; Maero, G; Pozzoli, R; Rome, M [INFN Sezione di Milano and Dipartimento di Fisica, Universita degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Cavenago, M [INFN Laboratori Nazionali di Legnaro, Viale dell' Universita 2, 35020 Legnaro (Italy); Svelto, C [Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia and Dipartimento di Elettronica e Informazione, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2009-09-07

    Pulsed electron beams produced by a photocathode source in the 1-10 keV energy range have been experimentally characterized by means of an electrostatic diagnostic system. A Malmberg-Penning trap in an open configuration, equipped with a planar charge collector has been used for the experiments. The relevant physical properties of the beams and their dependence on the injection conditions have been inferred through the numerical analysis of the electric signal measured across the overall load impedance of the charge collector. The indirect measurement technique presented here gives a general method to overcome the resolution limits of capacitive charge collectors.

  1. Electron-beam pulse annealed Ti-implanted GaP

    Science.gov (United States)

    Werner, Z.; Barlak, M.; Ratajczak, R.; Konarski, P.; Markov, A. M.; Heller, R.

    2016-08-01

    Gallium phosphide heavily doped with substitutional titanium is a prospective material for intermediate band solar cells. To manufacture such a material, single crystals of GaP were implanted with 120 keV Ti ions to doses between 5 × 1014 cm-2 and 5 × 1015 cm-2. They were next pulse annealed with 2 μs electron-beam pulses of electron energy of about 13 keV and pulse energy density between 1 and 2 Jcm-2. The samples were studied by channeled Rutherford Backscattering, particle induced X-ray emission, and SIMS. The results show full recovery of crystal structure damaged by implantation and good retention of the implanted titanium without, however, its significant substitution at crystal sites.

  2. Short-pulse, high-energy radiation generation from laser-wakefield accelerated electron beams

    Science.gov (United States)

    Schumaker, Will

    2013-10-01

    Recent experimental results of laser wakefield acceleration (LWFA) of ~GeV electrons driven by the 200TW HERCULES and the 400TW ASTRA-GEMINI laser systems and their subsequent generation of photons, positrons, and neutrons are presented. In LWFA, high-intensity (I >1019 W /cm2), ultra-short (τL Z target via bremsstrahlung into low-divergence (Z, the resulting Ne+ /Ne- ratio can approach unity, resulting in a near neutral density plasma jet. These quasi-neutral beams are presumed to retain the short-pulse (τL characteristic of the electron beam, resulting in a high peak density of ne- /e+ ~ 1016 cm-3 , making the source an excellent candidate for laboratory study of astrophysical leptonic jets. Alternatively, the electron beam can be interacted with a counter-propagating, ultra-high intensity (I >1021 W /cm2) laser pulse to undergo inverse Compton scattering and emit a high-peak brightness beam of high-energy photons. Preliminary results and experimental sensitivities of the electron-laser beam overlap are presented. The high-energy photon beams can be spectrally resolved using a forward Compton scattering spectrometer. Moreover, the photon flux can be characterized by a pixelated scintillator array and by nuclear activation and (γ,n) neutron measurements from the photons interacting with a secondary solid target. Monte-Carlo simulations were performed using FLUKA to support the yield estimates. This research was supported by DOE/NSF-PHY 0810979, NSF CAREER 1054164, DARPA AXiS N66001-11-1-4208, SF/DNDO F021166, and the Leverhulme Trust ECF-2011-383.

  3. Acceleration and evolution of a hollow electron beam in wakefields driven by a Laguerre-Gaussian laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guo-Bo [Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); College of Science, National University of Defense Technology, Changsha 410073 (China); Chen, Min, E-mail: minchen@sjtu.edu.cn, E-mail: yanyunma@126.com; Luo, Ji; Zeng, Ming; Yu, Lu-Le; Weng, Su-Ming [Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Schroeder, C. B.; Esarey, E. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Li, Fei-Yu [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Ma, Yan-Yun, E-mail: minchen@sjtu.edu.cn, E-mail: yanyunma@126.com; Yu, Tong-Pu [College of Science, National University of Defense Technology, Changsha 410073 (China); Sheng, Zheng-Ming [Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2016-03-15

    We show that a ring-shaped hollow electron beam can be injected and accelerated by using a Laguerre-Gaussian laser pulse and ionization-induced injection in a laser wakefield accelerator. The acceleration and evolution of such a hollow, relativistic electron beam are investigated through three-dimensional particle-in-cell simulations. We find that both the ring size and the beam thickness oscillate during the acceleration. The beam azimuthal shape is angularly dependent and evolves during the acceleration. The beam ellipticity changes resulting from the electron angular momenta obtained from the drive laser pulse and the focusing forces from the wakefield. The dependence of beam ring radius on the laser-plasma parameters (e.g., laser intensity, focal size, and plasma density) is studied. Such a hollow electron beam may have potential applications for accelerating and collimating positively charged particles.

  4. Influence of spatiotemporal coupling on the capture-and-acceleration-scenario vacuum electron acceleration by ultrashort pulsed laser beam

    Institute of Scientific and Technical Information of China (English)

    Lu Da-Quan; Qian Lie-Jia; Li Yong-Zhong; Fan Dian-Yuan

    2007-01-01

    This paper investigates the properties of the ultrashort pulsed beam aimed to the capture-and-acceleration-scenario(CAS) vacuum electron acceleration. The result shows that the spatiotemporal distribution of the phase velocity, the longitudinal component of the electric field and the acceleration quality factor are qualitatively similar to that of the continuous-wave Gaussian beam, and are slightly influenced by the spatiotemporal coupling of the ultrashort pulsed beam. When the pulse is compressed to an ultrashort one in which the pulse duration TFWHM < 5T0, the variation of the maximum net energy gain due to the carrier-envelope phase is a crucial disadvantage in the CAS acceleration process.

  5. Various categories of defects after surface alloying induced by high current pulsed electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Dian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Tang, Guangze, E-mail: oaktang@hit.edu.cn [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Gu, Le [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, Mingren [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-10-01

    Highlights: • Four kinds of defects are found during surface alloying by high current electron beam. • Exploring the mechanism how these defects appear after irradiation. • Increasing pulsing cycles will help to get good surface quality. • Choosing proper energy density will increase surface quality. - Abstract: High current pulsed electron beam (HCPEB) is an attractive advanced materials processing method which could highly increase the mechanical properties and corrosion resistance. However, how to eliminate different kinds of defects during irradiation by HCPEB especially in condition of adding new elements is a challenging task. In the present research, the titanium and TaNb-TiW composite films was deposited on the carburizing steel (SAE9310 steel) by DC magnetron sputtering before irradiation. The process of surface alloying was induced by HCPEB with pulse duration of 2.5 μs and energy density ranging from 3 to 9 J/cm{sup 2}. Investigation of the microstructure indicated that there were several forms of defects after irradiation, such as surface unwetting, surface eruption, micro-cracks and layering. How the defects formed was explained by the results of electron microscopy and energy dispersive spectroscopy. The results also revealed that proper energy density (∼6 J/cm{sup 2}) and multi-number of irradiation (≥50 times) contributed to high quality of alloyed layers after irradiation.

  6. Surface modification of Al-Pb alloy by high current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    LU You; LI Shi-long; AN Jian; LIU Yong-bing

    2006-01-01

    Al-Pb alloy was modified by high current pulsed electron beam and the microstructure, hardness and tribological characteristics were characterized by scanning electron microscopy, electronic microanalysis probe microanalysis, Knoop hardness indentation and pin-on-disc type wear testing machine. The results show that the microstructure and hardness can be greatly improved, and the modification layer consists of a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone and a transition zone followed by the substrate. The tribological properties of high current pulsed electron beam irradiated Al-Pb alloy are correspondingly improved largely. Optical observation and scanning electron microscopy analysis reveal that the low wear rate and lowest level in coefficient of friction at high load level for irradiated Al-Pb alloy are due to the formation of a lubricious tribolayer covering the worn surface, which is a mixture of Al2O3, Pb3O4 and silicate. The wear mode varies from oxidative wear at low load to film spalling at high load and, finally, adhesive wear.

  7. Effects of high-energy-pulse-electron beam radiation on biomacromolecules

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    To study the molecular mechanism of high mutation frequency induced by high-energy-pulse-electron (HEPE) beam radiation, the effects of HEPE radiation on yeast cells, plasma membrane, plasmid DNA, and protein activity were investigated by means of cell counting, gel electrophoresis, AO/EB double fluorescent staining, etc. The results showed that the viability of yeast cells declined statistically with increase of absorbed doses. The half lethal dose (LD50) was 134 Gy. HEPE beam radiation had little influence on the function of plasma membrane and protein, while it could induce much DNA damage of single strand breaks (SSB) and double strand breaks (DSB) that were required for gene mutation. The G-value for DSB formation of HEPE beam radiation in aqueous solution was 5.7 times higher than that caused by 60Co gamma rays. HEPE can be a new effective method for induced mutation breeding and deserves further research in the future.

  8. Pulsed Plasma Electron Sources

    Science.gov (United States)

    Krasik, Yakov

    2008-11-01

    Pulsed (˜10-7 s) electron beams with high current density (>10^2 A/cm^2) are generated in diodes with electric field of E > 10^6 V/cm. The source of electrons in these diodes is explosive emission plasma, which limits pulse duration; in the case E Hadas and Ya. E. Krasik, Europhysics Lett. 82, 55001 (2008).

  9. Generation of intense attosecond x-ray pulses using ultraviolet laser induced microbunching in electron beams

    Directory of Open Access Journals (Sweden)

    D. Xiang

    2009-06-01

    Full Text Available We propose a scheme that combines the echo-enabled harmonic generation technique with the bunch compression and allows one to generate harmonic numbers of a few hundred in a microbunched beam through up-conversion of the frequency of an ultraviolet seed laser. A few-cycle intense laser is used to generate the required energy chirp in the beam for bunch compression and for selection of an attosecond x-ray pulse. Sending this beam through a short undulator results in an intense isolated attosecond x-ray pulse. Using a representative realistic set of parameters, we show that 1 nm x-ray pulse with peak power of a few hundred MW and duration as short as 20 attoseconds (FWHM can be generated from a 200 nm ultraviolet seed laser. The proposed scheme may enable the study of electronic dynamics with a resolution beyond the atomic unit of time (∼24 attoseconds and may open a new regime of ultrafast sciences.

  10. Microstructures and properties of zirconium-702 irradiated by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shen [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Cai, Jie [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Engineering Institute of Advanced Manufacturing and Modern Equipment Technology, Jiangsu University, Zhenjiang 212013 (China); Lv, Peng; Zhang, Conglin; Huang, Wei [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Guan, Qingfeng, E-mail: guanqf@mail.ujs.edu.cn [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-09-01

    Highlights: • Zirconium-702 irradiated by high current pulsed electron beam was investigated. • Irradiated surface was melted and martensitic phase transformation occurred. • High density dislocations and deformation twins were formed in melted layer. • Micropores and ultrafine structures were also obtained on the irradiated surface. • Microhardness and corrosion resistance were improved after HCPEB irradiation. - Abstract: The microstructure, hardness and corrosion resistance of zirconium-702 before and after high-current pulsed electron beam (HCPEB) irradiation have been investigated. The microstructure evolution and surface morphologies of the samples were characterized by using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results indicate that the sample surface was melted after HCPEB irradiation, and martensitic phase transformation occurred. Besides, two kinds of craters as well as ultrafine structures were obtained in the melted layer. TEM observations suggest that high density dislocations and deformation twins were formed after HCPEB irradiation. With the increasing of pulses, microhardness of the irradiated samples was increased from the initial 178 Hv to 254 Hv. The corrosion resistance was tested by using electrode impedance spectroscopy (EIS) and potentiodynamic polarization curves. Electrochemical results show that, after HCPEB irradiation, all the samples had better corrosion resistance in 1 mol HNO{sub 3} solution compared to the initial one, among which the 5-pulsed sample owned the best corrosion resistance. Ultrafine structures, martensitic phase transformation, surface porosities, dislocations and deformation twins are believed to be the dominant reasons for the improvement of the hardness and corrosion resistance.

  11. Effect of heating samples during pulsed electron beam annealing on the open-circuit voltage of silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Laugier, A.; Barbier, D.; Doghmane, M.S.; Chemisky, G. (Institut National des Sciences Appliquees de Lyon, 69 - Villeurbanne (France))

    1983-01-01

    Defects associated with pulsed electron beam annealing of P implanted Si solar cells lead to poor Vsub(oc) (< 500mV). Their nature is discussed on the basic of S.E.M. observations, deep level transient spectroscopy study and degradation of electrical characteristics of Schottky barriers. An improved pulsed electron beam annealing process is determined, characterized by a low mean energy electron beam (10 keV) associated to a starting temperature of 450/sup 0/C and low fluences (<= 1J/cm/sup 2/). Values of Vsub(oc) similar to conventional thermal annealing are obtained.

  12. Laser-energy transfer and enhancement of plasma waves and electron beams by interfering high-intensity laser pulses.

    Science.gov (United States)

    Zhang, P; Saleh, N; Chen, S; Sheng, Z M; Umstadter, D

    2003-11-28

    The effects of interference due to crossed laser beams were studied experimentally in the high-intensity regime. Two ultrashort (400 fs), high-intensity (4 x 10(17) and 1.6 x 10(18) W/cm(2)) and 1 microm wavelength laser pulses were crossed in a plasma of density 4 x 10(19) cm(3). Energy was observed to be transferred from the higher-power to the lower-power pulse, increasing the amplitude of the plasma wave propagating in the direction of the latter. This results in increased electron self-trapping and plasma-wave acceleration gradient, which led to an increased number of hot electrons (by 300%) and hot-electron temperature (by 70%) and a decreased electron-beam divergence angle (by 45%), as compared with single-pulse illumination. Simulations reveal that increased stochastic heating of electrons may have also contributed to the electron-beam enhancement.

  13. Hydrogen effect on zirconium alloy surface treated by pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Pushilina, N.S.; Lider, A.M. [Department of General Physics, Institute of Physics and Technology, National Research Tomsk Polytechnic University, Lenin Avenue 30, Tomsk 634050 (Russian Federation); Kudiiarov, V.N., E-mail: viktor.kudiiarov@gmail.com [Department of General Physics, Institute of Physics and Technology, National Research Tomsk Polytechnic University, Lenin Avenue 30, Tomsk 634050 (Russian Federation); Chernov, I.P. [Department of General Physics, Institute of Physics and Technology, National Research Tomsk Polytechnic University, Lenin Avenue 30, Tomsk 634050 (Russian Federation); Ivanova, S.V. [National Research Nuclear University “MIFI”, Kashirskoye shosse 31, Moscow 115409 (Russian Federation)

    2015-01-15

    Influence of modification by pulsed electron beam (PEB) and hydrogen adsorption in zirconium alloys have been investigated. Treatment of Zr–1Nb alloy by high-current PEB allows for a decrease in the amount of hydrogen absorbed by the samples during the hydrogenation process from gas atmosphere in the temperature range of (350–550 °S). The effect of the PEB surface treatment on the hydrogen adsorption connected with the formation of a protective oxide film after PEB irradiation and also by the formation of a specific hardening structure under the action of irradiation at temperatures exceeding the melting temperature from the subsequent high-speed surface cooling.

  14. Surface treatment of 0.20% C carbon steel by high-current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    XU Guo-cheng; FU Shi-you; GUAN Qing-feng

    2006-01-01

    A high-current pulsed electron beam(HCPEB) generated on the system of Nadezhda-2 was applied to improve the microstructure and performance of 0.20% C low carbon steel. Surface layers of the samples bombarded by explosive electron beam at different pulses was observed by using electron microscopy. The physical model of the thermal-stress process and related modification mechanism as a result of HCPEB irradiation was also investigated. After HCPEB post treatments, obvious changes in microstructure and significant hardening occur in the depth of 200-250 μm from the surface after HCPEB irradiation. Rapid heating and subsequent rapid solidification induce heavy plastic deformation, which results in that the laminated structure of pearlite is substituted by dispersive rounded-like cementites in the near-surface. The effect of HCPEB treatment can reach more than 500 m depth from the surface. The original crystalline structure is changed to a different degree that grows with the numbers of bombardment, and in the surface layer amorphous states and nanocrystaline structures consisting of grains of γ-phase and cementite are found. The violent stress induced by HCPEB irradiation is the origin of the nanostructured and amorphous structure formation.

  15. Pulsed electron beam precharger. Final report, September 1, 1989--May 31, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. [ed.; Shelton, W.N.

    1992-12-31

    This is the fifth in a series of contracts and grants exploring the advanced particulate pollution control technology of electron beam precipitation. The project currently under contract with the Pittsburgh Energy Technology Center, US DOE, addresses the pressing problem of more efficiently controlling the emission of fine, high resistivity fly ash from low sulfur coal-burning power plants. As such, the project is an integral part of the DOE mission to advance technologies which provide for the safe and economically viable utilization of the nation`s large but potentially polluting coal resources. Within the University Coal Research Program of the DOE, the objective of the project is also consistent with the goal of improving the performance of electrostatic precipitators and possibly fabric filters through the use of a first-stage electron beam particle precharger. Reducing the emission of particulate matter from coal fired boilers is in the national interest from a respiratory health standpoint, while improved power efficiency of the removal process serves the goals of lowered energy consumption. In addition, an earlier spinoff of the ongoing program at FSU was the invention of a new technology using pulsed streamer corona for SO{sub 2} and NO{sub x} removal, the pulse energized electron reactor (PEER) process.

  16. Influence of gas pressure on electron beam emission current of pulsed cathodic-arc-based forevacuum plasma electron source

    Science.gov (United States)

    Burdovitsin, Victor A.; Kazakov, Andrey V.; Medovnik, Alexander V.; Oks, Efim M.

    2017-09-01

    We describe our experimental investigation of the effect of background gas pressure on the emission parameters of a pulsed cathodic-arc-based forevacuum-pressure plasma-cathode electron source. We find that increased gas pressure over the range 4-16 Pa significantly reduces the beam current rise-time and significantly increases the emission current amplitude. For example, at a discharge current of 20 A, increasing the working gas pressure from 4 Pa to 16 Pa increases the emission current from 8 A to 18 A and shortens the beam rise-time from 50 μs to 20 μs. This influence of gas pressure on the electron beam parameters can be explained by the effect of arc discharge current switching from the anode to emission. In our case, the current switching effect is caused by increased working gas pressure. In the forevacuum pressure range, the increase of the electron emission current with the growth of gas pressure is due to a rise in the emission plasma potential which is caused by ion back-streaming from the plasma formed in the electron beam transport region. A model describing the influence of gas pressure on the electron emission from the plasma is presented.

  17. Splash flow from a metal plate hit by an electron beam pulse

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M., LLNL

    1997-09-01

    When a pulsed electron beam hits a metal plate with sufficient energy a volume of the metal becomes hot fluid that subsequently sprays out of the plate. A second pulse of electrons traveling toward the plate would scatter and degrade before impacting the solid plate because of its encounter with the diffuse material of the initial splash. People designing electron beam machines for use as pulsed radiation sources wish to eliminate the interaction between the electrons and the splash because they want sharp radiation pulses emitted from the solid plate. This report presents a compressible fluid model of this splash flow and compares specific cases with experiments and comprehensive calculations performed by B. DeVolder and others at the Los Alamos National Laboratory, see reference (1). My aim was to develop as simple a theory as possible to calculate the speed and density of the splash flow. I have used both simplifying assumptions and mathematical approximations to develop convenient formulas. As I wished to make a clear and interesting presentation of this work to a diverse audience that includes people outside the specialty of fluid dynamics, some of my descriptions may seem wordier than necessary. The plan of the report is as follows. In the section called ``energy deposition`` I describe how an electron beam deposits energy in a solid plate, converting some of the material into a hot fluid. The initial temperature of this fluid is the key parameter in determining the nature of the subsequent flow; an explicit formula is shown. Flow occurs in two regions: along a streamtube within the metal plate and as an expanding plume outside the metal plate. Flow within the plate is described in the section called ``isentropic flow.`` This flow occurs as expansion waves move at the speed of sound through the streamtube. The analysis of this flow provides a formula for the mass flow over time from the plate into the external splash. The section called ``centered expansion

  18. Microstructures and properties of zirconium-702 irradiated by high current pulsed electron beam

    Science.gov (United States)

    Yang, Shen; Cai, Jie; Lv, Peng; Zhang, Conglin; Huang, Wei; Guan, Qingfeng

    2015-09-01

    The microstructure, hardness and corrosion resistance of zirconium-702 before and after high-current pulsed electron beam (HCPEB) irradiation have been investigated. The microstructure evolution and surface morphologies of the samples were characterized by using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results indicate that the sample surface was melted after HCPEB irradiation, and martensitic phase transformation occurred. Besides, two kinds of craters as well as ultrafine structures were obtained in the melted layer. TEM observations suggest that high density dislocations and deformation twins were formed after HCPEB irradiation. With the increasing of pulses, microhardness of the irradiated samples was increased from the initial 178 Hv to 254 Hv. The corrosion resistance was tested by using electrode impedance spectroscopy (EIS) and potentiodynamic polarization curves. Electrochemical results show that, after HCPEB irradiation, all the samples had better corrosion resistance in 1 mol HNO3 solution compared to the initial one, among which the 5-pulsed sample owned the best corrosion resistance. Ultrafine structures, martensitic phase transformation, surface porosities, dislocations and deformation twins are believed to be the dominant reasons for the improvement of the hardness and corrosion resistance.

  19. Relativistic electron beams driven by kHz single-cycle light pulses

    CERN Document Server

    Guénot, D; Vernier, A; Beaurepaire, B; Böhle, F; Bocoum, M; Lozano, M; Jullien, A; Lopez-Martens, R; Lifschitz, A; Faure, J

    2016-01-01

    Laser-plasma acceleration is an emerging technique for accelerating electrons to high energies over very short distances. The accelerated electron bunches have femtosecond duration, making them particularly relevant for applications such as ultrafast imaging or femtosecond X-ray generation. Current laser-plasma accelerators are typically driven by Joule-class laser systems that have two main drawbacks: their relatively large scale and their low repetition-rate, with a few shots per second at best. The accelerated electron beams have energies ranging from 100 MeV to multi-GeV, however a MeV electron source would be more suited to many societal and scientific applications. Here, we demonstrate a compact and reliable laser-plasma accelerator producing high-quality few-MeV electron beams at kilohertz repetition rate. This breakthrough was made possible by using near-single-cycle light pulses, which lowered the required laser energy for driving the accelerator by three orders of magnitude, thus enabling high repet...

  20. Electron Beam Ion Sources

    OpenAIRE

    Zschornacka, G.; Schmidt, M.; Thorn, A.

    2014-01-01

    Electron beam ion sources (EBISs) are ion sources that work based on the principle of electron impact ionization, allowing the production of very highly charged ions. The ions produced can be extracted as a DC ion beam as well as ion pulses of different time structures. In comparison to most of the other known ion sources, EBISs feature ion beams with very good beam emittances and a low energy spread. Furthermore, EBISs are excellent sources of photons (X-rays, ultraviolet, extreme ultraviole...

  1. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M.

    1998-04-16

    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 {sigma} = 8 x 10{sup 4} Siemens/m, density {rho} = 8 x 10{sup -3} kg/m{sup 3}, and initially magnetized to B = 1 Tesla can accelerate to v = 10{sup 4} m/s within a distance comparable to L = 1 mm and a time comparable to {sigma}{mu}L{sup 2} = 100 ns, which is the magnetic diffusion time. If instead, {sigma} = 8 x 10{sup 3} Siemens/m and {rho} = 8 x 10{sup -5} kg/m{sup 3} then v = 10{sup 5} m/s with a magnetic diffusion time {sigma}{mu}L{sup 2} = 10 ns. These idealized flows have R{sub M} = {sigma}{mu}vL = 1, where R{sub M} is the magnetic Reynolds number. The target magnetizes by a thermal electric effect.

  3. Frozen plasma within the flow from a metal plate hit by an electron beam pulse

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M., LLNL

    1997-11-01

    When a pulsed electron beam hits a metal plate with sufficient energy a volume of the metal becomes hot fluid that subsequently sprays out of the plate. A portion of this flow is ionized. This report describes a fluid that expands so rapidly into a vacuum that the ionized portion of the flow departs from local thermodynamic equilibrium. This cold supersonic exhaust will have a much higher degree of ionization, and of higher electron temperature, than would be expected from a gas in thermodynamic equilibrium at the local temperature of the neutral flow. This report presents a continuation of the work described in reference (1). My aim is to develop as simple a model as will reasonably predict the speed and density of neutral flow, and the temperature and density of plasma. I use simplifying assumptions and mathematical approximations to develop convenient formulas, and I test them by comparing specific examples to experimental data and computations by DeVolder and other Los Alamos scientists (2). The phenomenon of sudden expansion of a gas cloud into vacuum is described in several sections of the two-volume work by ZelUdovich and Raizer (3). The criterion I use for estimating the point in the flow where plasma ceases to be in equilibrium is in principle that proposed by Bray (4), (5), and discussed extensively by Vincenti and Kruger (6). The immediate concern motivating this work is how to design a metal target that accurately converts an electron beam pulse train into a radiation pulse train for use in the high-speed radiography of implosion hydrodynamics experiments. In the radiography application, either the electron beam must be swept magnetically along the metal target more quickly than the spread of the debris plume, or the metal plate must move laterally past a fixed point of impact, carrying its plume with it. What is this speed, and how dense is this splash flow? Aside from its technological application, this problem has an intrinsic interest because it

  4. Design and characterization of the annular cathode high current pulsed electron beam source for circular components

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Wei; Wang, Langping, E-mail: aplpwang@hit.edu.cn; Wang, Xiaofeng

    2016-08-01

    Highlights: • An annular cathode for HCPEB irradiation of circular components was designed. • The processing window for the annular cathode is obtained. • Irradiation thickness uniformity along the circumferential direction exceeds 90%. - Abstract: In order to irradiate circular components with high current pulsed electron beam (HCPEB), an annular cathode based on carbon fiber bunches was designed and fabricated. Using an acceleration voltage of 25 kV, the maximum pulsed irradiation current and energy of this annular cathode can reach 7.9 kA and 300 J, respectively. The irradiation current density distribution of the annular cathode HCPEB source measured along the circumferential direction shows that the annular cathode has good emission uniformity. In addition, four 9310 steel substrates fixed uniformly along the circumferential direction of a metal ring substrate were irradiated by this annular cathode HCPEB source. The surface and cross-section morphologies of the irradiated samples were characterized by scanning electron microscopy (SEM). SEM images of the surface reveal that crater and surface undulation have been formed, which hints that the irradiation energy of the HCPEB process is large enough for surface modification of 9310 steel. Meanwhile, SEM cross-section images exhibit that remelted layers with a thickness of about 5.4 μm have been obtained in all samples, which proves that a good practical irradiation uniformity can be achieved by this annular cathode HCPEB source.

  5. Surface Modification of Light Alloys by Low-Energy High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    X. D. Zhang

    2012-01-01

    Full Text Available This paper reviews results obtained by the research groups developing the low-energy high-current pulsed electron beam (LEHCPEB in Dalian (China and Metz (France on the surface treatment of light alloys. The pulsed electron irradiation induces an ultra-fast thermal cycle at the surface combined with the formation of thermal stress and shock waves. As illustrated for Mg alloys and Ti, this results in deep subsurface hardening (over several 100 μm which improves the wear resistance. The analysis of the top surface melted surface of light alloys also often witnesses evaporation and condensation of chemical species. This phenomenon can significantly modify the melt chemistry and was also suggested to lead to the development of specific solidification textures in the rapidly solidified layer. The potential use of the LEHCPEB technique for producing thermomechanical treatments under the so-called heating mode and, thus, modify the surface crystallographic texture, and enhance solid-state diffusion is also demonstrated in the case of the FeAl intermetallic compound.

  6. Microstructure Analysis of HPb59-1 Brass Induced by High Current Pulsed Electron Beam

    Science.gov (United States)

    Lyu, Jike; Gao, Bo; Hu, Liang; Lu, Shuaidan; Tu, Ganfeng

    2016-08-01

    In this paper, the effects of high current pulsed electron beam (HCPEB) on the microstructure evolution of casting HPb59-1 (Cu 57.1 mass%, Pb 1.7 mass% and Zn balance) alloy were investigated. The results showed a "wavy" surface which was formed with Pb element existing in the forms of stacking block and microparticles on the top surface layer after treatment. Nanocrystalline structures including Pb grains and two phases (α and β) were formed on the top remelted layer and their sizes were all less than 100 nm. The disordered β phase was generated in the surface layer after HCPEB treatment, which is beneficial for the improvement of surface properties. Meanwhile, there was a large residual stress on the alloy surface, along with the appearance of microcracks, and the preferred orientations of grains also changed.

  7. The SPARC_LAB femtosecond synchronization for electron and photon pulsed beams

    Science.gov (United States)

    Bellaveglia, M.; Gallo, A.; Piersanti, L.; Pompili, R.; Gatti, G.; Anania, M. P.; Petrarca, M.; Villa, F.; Chiadroni, E.; Biagioni, A.; Mostacci, A.

    2015-05-01

    The SPARC LAB complex hosts a 150 MeV electron photo-injector equipped with an undulator for FEL production (SPARC) together with a high power TW laser (FLAME). Recently the synchronization system reached the performance of < 100 fsRMS relative jitter between lasers, electron beam and RF accelerating fields. This matches the requirements for next future experiments: (i) the production of X-rays by means of Thomson scattering (first collisions achieved in 2014) and (ii) the particle driven PWFA experiment by means of multiple electron bunches. We report about the measurements taken during the machine operation using BAMs (Bunch Arrival Monitors) and EOS (Electro-Optical Sampling) system. A new R and D activity concerning the LWFA using the external injection of electron bunches in a plasma generated by the FLAME laser pulse is under design. The upgrade of the synchronization system is under way to guarantee the < 30 fs RMS jitter required specification. It foresees the transition from electrical to optical architecture that mainly affects the reference signal distribution and the time of arrival detection performances. The new system architecture is presented together with the related experimental data.

  8. A pulsed electron beam synthesis of PEDOT conducting polymers by using sulfate radicals as oxidizing species

    Science.gov (United States)

    Coletta, Cecilia; Cui, Zhenpeng; Dazzi, Alexandre; Guigner, Jean-Michel; Néron, Stéphane; Marignier, Jean-Louis; Remita, Samy

    2016-09-01

    In this study, an original radiolytic method, based on pulsed electron beam irradiation, is used for the synthesis of conducting PEDOT in an aqueous solution containing EDOT monomers in the presence of potassium persulfate, K2S2O8, at 0 °C. At this low temperature, EDOT monomers are not chemically oxidized by S2O82- anions, initiating PEDOT polymerization, but are rather oxidized by sulfate radicals, SO4•-, which are radiolytically generated by the reaction of solvated electrons, produced by water radiolysis, with persulfate anions. Successfully, as demonstrated by UV-vis absorption spectrophotometry and ATR-FTIR spectroscopy, irradiating the aqueous solution, by using a series of accumulated electron pulses, enables complete EDOT oxidation and quantitative in situ PEDOT polymerization through a step-by-step oxidation mechanism. The morphology of PEDOT polymers, mixed with unreacted K2S2O8 salt, is characterized by Cryo-TEM microscopy in aqueous solution and by SEM after deposition. Successfully, in the absence of any washing step, high resolution AFM microscopy, coupled with infrared nanospectroscopy, is used to discriminate between the organic polymers and the inorganic salt and to probe the local chemical composition of PEDOT nanostructures. The results demonstrate that PEDOT polymers form globular self-assembled nanostructures which preferentially adsorb onto unreacted K2S2O8 solid nanoplates. The present results first demonstrate the efficiency of sulfate radicals as oxidizing species for the preparation of nanostructured PEDOT polymers and second highlight the promising potentiality of electron accelerators in the field of conducting polymers synthesis.

  9. [Pulsed electron beam precharger]. Technical progress report No. 2, December 1, 1989--February 28, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. [ed.; Shelton, W.N.

    1990-12-31

    This report discusses the following topics on electron beam guns: Precharger Modification; Installation of Charge vs. Radius Apparatus; High Concentration Aerosol Generation; and Data Acquisition and Analysis System.

  10. Consequences of short electron-beam pulses in the FELIX project

    Science.gov (United States)

    Jaroszynski, D. A.; Oepts, D.; Van Der Meer, A. F. G.; Van Amersfoort, P. W.; Colson, W. B.

    1990-10-01

    We discuss the consequences of short micropulses on the output of infrared and far-infrared free electron lasers with special reference to the FELIX project which operates with 3 ps long electron pulses.

  11. Surface Nanostructure Formations in an AISI 316L Stainless Steel Induced by Pulsed Electron Beam Treatment

    Directory of Open Access Journals (Sweden)

    Yang Cai

    2015-01-01

    Full Text Available High current pulsed electron beam (HCPEB is an efficient technique for surface modifications of metallic materials. In the present work, the formations of surface nanostructures in an AISI 316L stainless steel induced by direct HCPEB treatment and HCPEB alloying have been investigated. After HCPEB Ti alloying, the sample surface contained a mixture of the ferrite and austenite phases with an average grain size of about 90 nm, because the addition of Ti favors the formation of ferrite. In contrast, electron backscattered diffraction (EBSD analyses revealed no structural refinement on the direct HCPEB treated sample. However, transmission electron microscope (TEM observations showed that fine cells having an average size of 150 nm without misorientations, as well as nanosized carbide particles, were formed in the surface layer after the direct HCPEB treatment. The formation of nanostructures in the 316L stainless steel is therefore attributed to the rapid solidification and the generation of different phases other than the steel substrate in the melted layer.

  12. Study on Nanostructures Induced by High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2012-01-01

    Full Text Available Four techniques using high-current pulsed electron beam (HCPEB were proposed to obtain surface nanostructure of metal and alloys. The first method involves the distribution of several fine Mg nanoparticles on the top surface of treated samples by evaporation of pure Mg with low boiling point. The second technique uses superfast heating, melting, and cooling induced by HCPEB irradiation to refine the primary phase or the second phase in alloys to nanosized uniform distributed phases in the matrix, such as the quasicrystal phase Mg30Zn60Y10 in the quasicrystal alloy Mg67Zn30Y3. The third technique involves the refinement of eutectic silicon phase in hypereutectic Al-15Si alloys to fine particles with the size of several nanometers through solid solution and precipitation refinement. Finally, in the deformation zone induced by HCPEB irradiation, the grain size can be refined to several hundred nanometers, such as the grain size of the hypereutectic Al-15Si alloys in the deformation zone, which can reach ~400 nm after HCPEB treatment for 25 pulses. Therefore, HCPEB technology is an efficient way to obtain surface nanostructure.

  13. Formation of the surface alloys by high-intensity pulsed electron beam irradiation of the coating/substrate system

    Science.gov (United States)

    Ivanov, Yu F.; Petrikova, E. A.; Teresov, A. D.; Krysina, O. V.; Rygina, M. E.

    2015-04-01

    The results of the analysis of the structure and properties of the surface layer of aluminum A7 subjected to alloying by the intense pulsed electron beam melting of the film / substrate system. Fold increase in strength and tribological properties of the modified surface layer due to the formation of submicro - nanoscale multiphase structure have been revealed.

  14. The structure and properties of boron carbide ceramics modified by high-current pulsed electron-beam

    Science.gov (United States)

    Ivanov, Yuri; Tolkachev, Oleg; Petyukevich, Maria; Teresov, Anton; Ivanova, Olga; Ikonnikova, Irina; Polisadova, Valentina

    2016-01-01

    The present work is devoted to numerical simulation of temperature fields and the analysis of structural and strength properties of the samples surface layer of boron carbide ceramics treated by the high-current pulsed electron-beam of the submillisecond duration. The samples made of sintered boron carbide ceramics are used in these investigations. The problem of calculating the temperature field is reduced to solving the thermal conductivity equation. The electron beam density ranges between 8…30 J/cm2, while the pulse durations are 100…200 μs in numerical modelling. The results of modelling the temperature field allowed ascertaining the threshold parameters of the electron beam, such as energy density and pulse duration. The electron beam irradiation is accompanied by the structural modification of the surface layer of boron carbide ceramics either in the single-phase (liquid or solid) or two-phase (solid-liquid) states. The sample surface of boron carbide ceramics is treated under the two-phase state (solid-liquid) conditions of the structural modification. The surface layer is modified by the high-current pulsed electron-beam produced by SOLO installation at the Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia. The elemental composition and the defect structure of the modified surface layer are analyzed by the optical instrument, scanning electron and transmission electron microscopes. Mechanical properties of the modified layer are determined measuring its hardness and crack resistance. Research results show that the melting and subsequent rapid solidification of the surface layer lead to such phenomena as fragmentation due to a crack network, grain size reduction, formation of the sub-grained structure due to mechanical twinning, and increase of hardness and crack resistance.

  15. The structure and properties of boron carbide ceramics modified by high-current pulsed electron-beam

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Yuri, E-mail: yufi55@mail.ru [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 2/3 Akademicheskiy Ave. Tomsk, 634055 (Russian Federation); National Research Tomsk State University, 36 Lenina Str., Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenina Str., Tomsk, 634050 (Russian Federation); Tolkachev, Oleg, E-mail: ole.ts@mail.ru; Petyukevich, Maria, E-mail: petukevich@tpu.ru; Polisadova, Valentina, E-mail: polis@tpu.ru [National Research Tomsk Polytechnic University, 30 Lenina Str., Tomsk, 634050 (Russian Federation); Teresov, Anton, E-mail: tad514@sibmail.com [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 2/3 Akademicheskiy Ave. Tomsk, 634055 (Russian Federation); National Research Tomsk State University, 36 Lenina Str., Tomsk, 634050 (Russian Federation); Ivanova, Olga, E-mail: ivaov@mail.ru; Ikonnikova, Irina, E-mail: irina-ikonnikova@yandex.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq., Tomsk, 634003 (Russian Federation)

    2016-01-15

    The present work is devoted to numerical simulation of temperature fields and the analysis of structural and strength properties of the samples surface layer of boron carbide ceramics treated by the high-current pulsed electron-beam of the submillisecond duration. The samples made of sintered boron carbide ceramics are used in these investigations. The problem of calculating the temperature field is reduced to solving the thermal conductivity equation. The electron beam density ranges between 8…30 J/cm{sup 2}, while the pulse durations are 100…200 μs in numerical modelling. The results of modelling the temperature field allowed ascertaining the threshold parameters of the electron beam, such as energy density and pulse duration. The electron beam irradiation is accompanied by the structural modification of the surface layer of boron carbide ceramics either in the single-phase (liquid or solid) or two-phase (solid-liquid) states. The sample surface of boron carbide ceramics is treated under the two-phase state (solid-liquid) conditions of the structural modification. The surface layer is modified by the high-current pulsed electron-beam produced by SOLO installation at the Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia. The elemental composition and the defect structure of the modified surface layer are analyzed by the optical instrument, scanning electron and transmission electron microscopes. Mechanical properties of the modified layer are determined measuring its hardness and crack resistance. Research results show that the melting and subsequent rapid solidification of the surface layer lead to such phenomena as fragmentation due to a crack network, grain size reduction, formation of the sub-grained structure due to mechanical twinning, and increase of hardness and crack resistance.

  16. Large-charge quasimonoenergetic electron beams produced by off-axis colliding laser pulses in underdense plasma

    Science.gov (United States)

    Deng, Z. G.; Zhang, Z. M.; Zhang, B.; He, S. K.; Teng, J.; Hong, W.; Dong, K. G.; Wu, Y. C.; Zhu, B.; Gu, Y. Q.

    2017-02-01

    Electrons can be efficiently injected into a plasma wave by colliding two counterpropagating laser pulses in a laser wakefield acceleration. However, the generation of a high-quality electron beam with a large charge is difficult in the traditional on-axis colliding scheme due to the growth of the electron beam duration coming from the increase of the beam charge. To solve this problem, we propose an off-axis colliding scheme, in which the collision point is away from the axis of the driver pulse. We show that the electrons injected from the off-axis region are highly concentered on the tail of the bubble even for a large trapped charge, thus feeling almost the same accelerating field. As a result, quasimonoenergetic electron beams with a large charge can be produced. The validity of this scheme is confirmed by both the particle-in-cell simulations and the Hamiltonian model. Furthermore, it is shown that a Laguerre-Gauss (LG) laser can be adopted as the injection pulse to realize the off-axis colliding injection in three dimensions symmetrically, which may be useful in simplifying the technical layout of the real experiment setup.

  17. Surface Nanocrystallization of 3Cr13 Stainless Steel Induced by High-Current Pulsed Electron Beam Irradiation

    OpenAIRE

    2013-01-01

    The nanocrystalline surface was produced on 3Cr13 martensite stainless steel surface using high-current pulsed electron beam (HCPEB) technique. The structures of the nanocrystallized surface were characterized by X-ray diffraction and electron microscopy. Two nanostructures consisting of fine austenite grains (50–150 nm) and very fine carbides precipitates are formed in melted surface layer after multiple bombardments via dissolution of carbides and crater eruption. It is demonstrated that th...

  18. Effect of Higher Order Axial Electron Temperature on Self-Focusing of Electromagnetic Pulsed Beam in Collisional Plasma

    Institute of Scientific and Technical Information of China (English)

    夏雄平; 易林

    2012-01-01

    Effect of higher order axial electron temperature on self-focusing of electromagnetic pulsed beam in collisional plasma is investigated.It is shown that higher order axial electron temperature T p4 is not trivial than T p0 and T p2,which can modify slightly radial redistribution of electron density and increases effective dielectric constant.As a result,on one hand,slightly reduce electromagnetic beam self-focusing in the course of oscillatory convergence,on the other hand,quicken beam divergence in the course of steady divergence,i.e.,higher order axial electron temperature T p4 can decrease the influence of collisional nonlinearity in collisional plasma.

  19. Intense terahertz pulses from SLAC electron beams using coherent transition radiation.

    Science.gov (United States)

    Wu, Ziran; Fisher, Alan S; Goodfellow, John; Fuchs, Matthias; Daranciang, Dan; Hogan, Mark; Loos, Henrik; Lindenberg, Aaron

    2013-02-01

    SLAC has two electron accelerators, the Linac Coherent Light Source (LCLS) and the Facility for Advanced Accelerator Experimental Tests (FACET), providing high-charge, high-peak-current, femtosecond electron bunches. These characteristics are ideal for generating intense broadband terahertz (THz) pulses via coherent transition radiation. For LCLS and FACET respectively, the THz pulse duration is typically 20 and 80 fs RMS and can be tuned via the electron bunch duration; emission spectra span 3-30 THz and 0.5 THz-5 THz; and the energy in a quasi-half-cycle THz pulse is 0.2 and 0.6 mJ. The peak electric field at a THz focus has reached 4.4 GV/m (0.44 V/Å) at LCLS. This paper presents measurements of the terahertz pulses and preliminary observations of nonlinear materials response.

  20. Effect of gas heating on the generation of an ultrashort avalanche electron beam in the pulse-periodic regime

    Science.gov (United States)

    Baksht, E. Kh.; Burachenko, A. G.; Lomaev, M. I.; Sorokin, D. A.; Tarasenko, V. F.

    2015-07-01

    The generation of an ultrashort avalanche electron beam (UAEB) in nitrogen in the pulse-periodic regime is investigated. The gas temperature in the discharge gap of the atmospheric-pressure nitrogen is measured from the intensity distribution of unresolved rotational transitions ( C 3Π u , v' = 0) → ( B 3Π g , v″ = 0) in the nitrogen molecule for an excitation pulse repetition rate of 2 kHz. It is shown that an increase in the UAEB current amplitude in the pulse-periodic regime is due to gas heating by a series of previous pulses, which leads to an increase in the reduced electric field strength as a result of a decrease in the gas density in the zone of the discharge formation. It is found that in the pulse-periodic regime and the formation of the diffuse discharge, the number of electrons in the beam increases by several times for a nitrogen pressure of 9 × 103 Pa. The dependences of the number of electrons in the UAEB on the time of operation of the generator are considered.

  1. Soft x-ray generation in gases by means of a pulsed electron beam produced in a high-voltage barier discharge

    NARCIS (Netherlands)

    Azarov, A.V.; Peters, P.J.M.; Boller, K.-J.

    2007-01-01

    A large area pulsed electron beam is produced by a high-voltage barrier discharge. We compare the properties of the x-rays generated by stopping this beam of electrons in a thin metal foil with those generated by stopping the electrons directly in various gases. The generation of x-rays was investig

  2. Ultrashort x-ray pulse generation by electron beam slicing in storage rings

    Directory of Open Access Journals (Sweden)

    A. He

    2014-04-01

    Full Text Available We propose a new method to generate ultrashort x-ray pulses using focused short low energy (∼20  MeV electron bunches to create short slices of electrons from the circulating electron bunches in a synchrotron radiation storage ring. When a low energy electron bunch crosses from the top of a high energy storage ring electron bunch, its Coulomb force will kick a short slice from the core of the storage ring electron bunch. The separated slices, when passing through an undulator, will radiate ultrashort x-ray pulses at about 160 fs. We discuss the advantages, challenges, and provide data which confirm the feasibility of this new method.

  3. Collimated Propagation of Fast Electron Beams Accelerated by High-Contrast Laser Pulses in Highly Resistive Shocked Carbon

    Science.gov (United States)

    Vaisseau, X.; Morace, A.; Touati, M.; Nakatsutsumi, M.; Baton, S. D.; Hulin, S.; Nicolaï, Ph.; Nuter, R.; Batani, D.; Beg, F. N.; Breil, J.; Fedosejevs, R.; Feugeas, J.-L.; Forestier-Colleoni, P.; Fourment, C.; Fujioka, S.; Giuffrida, L.; Kerr, S.; McLean, H. S.; Sawada, H.; Tikhonchuk, V. T.; Santos, J. J.

    2017-05-01

    Collimated transport of ultrahigh intensity electron current was observed in cold and in laser-shocked vitreous carbon, in agreement with simulation predictions. The fast electron beams were created by coupling high-intensity and high-contrast laser pulses onto copper-coated cones drilled into the carbon samples. The guiding mechanism—observed only for times before the shock breakout at the inner cone tip—is due to self-generated resistive magnetic fields of ˜0.5 - 1 kT arising from the intense currents of fast electrons in vitreous carbon, by virtue of its specific high resistivity over the range of explored background temperatures. The spatial distribution of the electron beams, injected through the samples at different stages of compression, was characterized by side-on imaging of hard x-ray fluorescence.

  4. Dosimetric measurements and Monte Carlo simulation for achieving uniform surface dose in pulsed electron beam irradiation facility

    Indian Academy of Sciences (India)

    V C Petwal; J N Rao; Jishnu Dwivedi; V K Senecha; K V Subbaiah

    2010-03-01

    A prototype pulsed electron beam irradiation facility for radiation processing of food and medical products is being commissioned at our centre in Indore, India. Analysis of surface dose and uniformity for a pulsed beam facility is of crucial importance because it is influenced by various operating parameters such as beam current, pulse repetition rate (PRR), scanning current profile and frequency, scanning width and product conveying speed. A large number of experiments are required to determine the harmonized setting of these operating parameters for achieving uniform dose. Since there is no readily available tool to set these parameters, use of Monte Carlo methods and computational tools can prove to be the most viable and time saving technique to support the assessment of the dose distribution. In the present study, Monte Carlo code, MCNP, is used to simulate the transport of 10 MeV electron beam through various mediums coming into the beam path and generate an equivalent dose profile in a polystyrene phantom for stationary state. These results have been verified with experimentally measured dose profile, showing that results are in good agreement within 4%. The Monte Carlo simulation further has been used to optimize the overlapping between the successive pulses of a scan to achieve ± 5% dose uniformity along the scanning direction. A mathematical model, which uses the stationary state data, is developed to include the effect of conveyor speed. The algorithm of the model is discussed and the results are compared with the experimentally measured values, which show that the agreement is better than 15%. Finally, harmonized setting for operating parameters of the accelerator are derived to deliver uniform surface dose in the range of 1–13 kGy/pass.

  5. Single-pulse femtosecond laser Bessel beams drilling of high-aspect-ratio microholes based on electron dynamics control

    Science.gov (United States)

    Zhao, Weiwei; Li, Xiaowei; Xia, Bo; Yan, Xueliang; Han, Weina; Lu, Yongfeng; Jiang, Lan

    2014-11-01

    Microholes drilling has attracted extensive research efforts for its broad applications in photonics, microfluidics, optical fibers and many other fields. A femtosecond (fs) laser is a promising tool for high-precision materials processing with reduced recast/microcracks and minimized heat affected zones. But there remain many challenges in hole drilling using conventional fs laser with Gaussian beams, such as low aspect ratio and taper effects. We report small-diameter and high-aspect-ratio microholes with taper free drilling in PMMA (polymethyl methacrylate) using single-pulse fs laser Bessel beams. Axicon is used to transform Gaussian beams into Bessel beams, which then irradiate in the sample by a telescope consisting of plano-convex lens and microscope objective. Using this technique, we enhance the aspect ratio of microholes by 55 times as compared with Gaussian beams. We attribute this high aspect ratio and high quality microholes formation to the unique spatial intensity distribution and propagation stability of Bessel beams, which can effectively adjust the transient localized electron density distribution leading to a long and uniform localized-interacted zone. By using the optimized pulse energy and focal depth position, the microholes diameter ranges between 1.4-2.1 μm and the aspect ratio can exceed 460. This efficient technique is of great potentials for fabrication of microphotonics devices and microfluidics.

  6. Radiation-Induced Centers in Lead Silicate Glasses Irradiated by Stationary and Pulsed Electron Beams

    Science.gov (United States)

    Zhidkov, I. S.; Zatsepin, A. F.; Konev, S. F.; Cholakh, S. O.

    2015-08-01

    Radiation-induced centers formed in heavy flint glasses irradiated by electron beams are investigated by the methods of optical and EPR spectroscopy. It is revealed that stable and short-living optical absorption centers of close natures are formed under irradiation by fast electrons. A correlation is established between the stable optical absorption bands and the EPR signals interpreted as signals of the (Pb2+)/h+ hole centers. The shortliving color centers are formed due to short-term distortion of the O-Pb bonds, and the stable centers are formed due to the spatial separation, thermalization, and subsequent stabilization of excited electrons and holes in tails of the localized states. Irradiation by electron beams leads to a change in the spectral characteristics of the fundamental absorption edge and, in particular, of the Urbach energy that determines the degree of structural disorder.

  7. Study on flexible and organizable time-resolved measurement system and technology for multi-pulsed electron beam parameter

    CERN Document Server

    Jiang, Xiao-Guo; Yang, Guo-Jun; Li, Hong; Zhang, Zhuo; Yang, Xing-Lin; Liao, Shu-Qing; Wei, Tao; Zhang, Xiao-Ding; Li, Yi-Ding

    2016-01-01

    The proof test and debugging of the multi-pulsed electron accelerator, Dragon-2,requires a thorough comprehension of the quality of the beams. This puts forward a rigid requirement on the measurement system that it should have the ability that not only differentiates the three pulses on the whole but also tells the details of each pulse.In the measurements, beam energy is converted by a target to the Optical Transition Radiation (OTR) light, the information carried by which provides a good approach to measure beam profile and divergence simultaneously. Combining with this characteristic of OTR light, the concept of dual-imaging method is adopted in the design of optical imaging system. To avoid interference of the system optical parameters with one another, the original system is separated into two parts by functions, one for beam profile measurements and the other for divergence measurements. Correspondingly a splitter is interposed immediately after the OTR target which splits the light into two parts in pe...

  8. Pulsed plasma electron sourcesa)

    Science.gov (United States)

    Krasik, Ya. E.; Yarmolich, D.; Gleizer, J. Z.; Vekselman, V.; Hadas, Y.; Gurovich, V. Tz.; Felsteiner, J.

    2009-05-01

    There is a continuous interest in research of electron sources which can be used for generation of uniform electron beams produced at E ≤105 V/cm and duration ≤10-5 s. In this review, several types of plasma electron sources will be considered, namely, passive (metal ceramic, velvet and carbon fiber with and without CsI coating, and multicapillary and multislot cathodes) and active (ferroelectric and hollow anodes) plasma sources. The operation of passive sources is governed by the formation of flashover plasma whose parameters depend on the amplitude and rise time of the accelerating electric field. In the case of ferroelectric and hollow-anode plasma sources the plasma parameters are controlled by the driving pulse and discharge current, respectively. Using different time- and space-resolved electrical, optical, spectroscopical, Thomson scattering and x-ray diagnostics, the parameters of the plasma and generated electron beam were characterized.

  9. Pulsed electron beam precharger. Technical progress report No. 7, March 1--May 31, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. [ed.; Shelton, W.N.

    1991-12-31

    During the previous reporting period (Quarter Six), the charging and removal of a fine, high resistivity aerosol using the advanced technology of electron beam precipitation was successfully accomplished. Precharging a dust stream circulating through the EBP wind tunnel produced collection efficiency figures of up to 40 times greater than with corona charging and collection alone (Table 1). The increased system collection efficiency attributed to electron beam precharging was determined to be the result of increased particle charge. It was found that as precharger electric field was raised, collection efficiency became greater. In sequence, saturation particle charge varies with the precharger electric field strength, particle migration velocity varies with the precharger and collector electric field, and collection efficiency varies with the migration velocity. Maximizing the system collection efficiency requires both a high charging electric field (provided by the E-beam precharger), and a high collecting electric field (provided by the collector wires and plates). Because increased particle collection efficiency is directly attributable to higher particle charge, the focus of research during Quarter Seven was shifted to learning more about the actual charge magnitude on the aerosol particles. Charge determinations in precipitators have traditionally been made on bulk dust samples collected from the flue gas stream, which gives an overall charge vs. mass (Q/M) ratio measurement. More recently, techniques have been developed which allow the measurement of the charge on individual particles in a rapid and repeatable fashion. One such advanced technique has been developed at FSU for use in characterizing the electron beam precharger.

  10. Electromagnetic fields from pulsed electron beam experiments in space - Spacelab-2 results

    Science.gov (United States)

    Bush, R. I.; Reeves, G. D.; Banks, P. M.; Neubert, T.; Williamson, P. R.

    1987-01-01

    During the Spacelab-2 mission a small satellite carrying various plasma diagnostic instruments was released from the Shuttle to coorbit at distances up to 300 m. During a magnetic conjunction of the Shuttle and the satellite an electron beam modulated at 1.22 kHz was emitted from the Shuttle during a 7 min period. The spatial structure of the electromagnetic fields generated by the beam was observed from the satellite out to a distance of 153 m perpendicular to the beam. The magnetic field amplitude of the strongest harmonics were comparable to the amplitude of simultaneously observed whistlers, while the electric field amplitudes were estimated to 1-10 mV/m.

  11. Halo Evolution of Hypereutectic Al-17.5Si Alloy Treated with High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    L. Hu

    2015-01-01

    Full Text Available Halo evolution of an Al-17.5Si alloy surface after treatment with increasing pulse numbers of a high-current pulsed electron beam (HCPEB was investigated. A halo is a ring microstructure resembling a bull’s eye. SEM results indicate that the nanocrystallization of halo induced by HCPEB treatment leads to gradual diffusion of the Si phase. Multiple pulses numbers cause the Si phase to be significantly refined and uniformly distributed. In addition, nanosilicon particles with a grain size of 30~100 nm were formed after HCPEB treatment, as shown by TEM observation. XRD results indicate that Si diffraction peaks broadened after HCPEB treatment. The microhardness tests demonstrate that the microhardness at the midpoint from the halo edge to center decreased sharply from 9770.7 MPa at 5 pulses to 2664.14 MPa at 25 pulses. The relative wear resistance of a 15-pulse sample is effectively improved by a factor of 6.5, exhibiting optimal wear resistance.

  12. Measurement of surface recombination velocity for silicon solar cells using a scanning electron microscope with pulsed beam

    Science.gov (United States)

    Daud, T.; Cheng, L. J.

    1981-01-01

    The role of surface recombination velocity in the design and fabrication of silicon solar cells is discussed. A scanning electron microscope with pulsed electron beam was used to measure this parameter of silicon surfaces. It is shown that the surface recombination velocity, s, increases by an order of magnitude when an etched surface degrades, probably as a result of environmental reaction. A textured front-surface-field cell with a high-low junction near the surface shows the effect of minority carrier reflection and an apparent reduction of s, whereas a tandem-junction cell shows an increasing s value. Electric fields at junction interfaces in front-surface-field and tandem-junction cells acting as minority carrier reflectors or sinks tend to alter the value of effective surface recombination velocity for different beam penetration depths. A range of values of s was calculated for different surfaces.

  13. The nature of glow arising in PETN monocrystals’ explosion initiated by a pulsed electron beam

    Science.gov (United States)

    Aduev, B. P.; Belokurov, G. M.; Grechin, S. S.; Liskov, I. Yu; Kalenskii, A. V.; Zvekov, A. A.

    2015-04-01

    The explosive decomposition of pentaerythritol tetranitrate monocrystals under the influence of a high-current electron beam (0.25 MeV, 20 ns, 15 J/cm2) was researched with the approach of high temporal resolution optic spectroscopy. We measured kinetics and emission spectra in real time scale. The thermal nature of the explosive glow was proven with the method of spectral pyrometry. The estimated temperature of the explosion is T ≈ 3000 K..

  14. Pinched Propagation of High-Power, Pulsed Electron Beams for Welding and Materials Processing Applications

    Science.gov (United States)

    1994-01-03

    D. S. Prono , J. T. Weir, and F. W. Chambers, "Status of Beam Transport with the ETA and ATA Accelerators," NTIS Document No. DE84013205, 1984...Copies may be ordered from the National Technical Information Service, Springfield, VA 22161. 34 17. D. S. Prono , et al., in Proceedings of the 1989 IEEE...Particle Accelerator Conference (Institute of Electrical and Electronics Engineers, Piscataway, NJ, 1989), p. 1441. 18. D. S. Prono , IEEE Trans. Nucl

  15. Relativistic electron beams driven by single-cycle laser pulses at kHz repetition rate (Conference Presentation)

    Science.gov (United States)

    Faure, Jérôme; Guénot, Diego; Gustas, Dominykas; Vernier, Aline; Beaurepaire, Benoît; Böhle, Frederik; López-Martens, Rodrigo; Lifschitz, Agustin

    2017-05-01

    Laser-plasma accelerators are usually driven by 100-TW class laser systems with rather low repetition rates. However, recent years have seen the emergence of laser-plasma accelerators operating with kHz lasers and energies lower than 10 mJ. The high repetition-rate is particularly interesting for applications requiring high stability and high signal-to-noise ratio but lower energy electrons. For example, our group recently demonstrated that kHz laser-driven electron beams could be used to capture ultrafast structural dynamics in Silicon nano-membranes via electron diffraction with picosecond resolution. In these first experiments, electrons were injected in the density gradients located at the plasma exit, resulting in rather low energies in the 100 keV range. The electrons being nonrelativistic, the bunch duration quickly becomes picosecond long. Relativistic energies are required to mitigate space charge effects and maintain femtosecond bunches. In this paper, we will show very recent results where electrons are accelerated in laser-driven wakefields to relativistic energies, reaching up to 5 MeV at kHz repetition rate. The electron energy was increased by nearly two orders of magnitude by using single-cycle laser pulses of 3.5 fs, with only 2.5 mJ of energy. Using such short pulses of light allowed us to resonantly excite high amplitude and nonlinear plasma waves at high plasma density, ne=1.5-2×1020 cm-3, in a regime close to the blow-out regime. Electrons had a peaked distribution around 5 MeV, with a relative energy spread of 30 %. Charges in the 100's fC/shot and up to pC/shot where measured depending on plasma density. The electron beam was fairly collimated, 20 mrad divergence at Full Width Half Maximum. The results show remarkable stability of the beam parameters in terms of beam pointing and electron distribution. 3D PIC simulations reproduce the results very well and indicate that electrons are injected by the ionization of Nitrogen atoms, N5+ to N6

  16. Formation Mechanism of Micropores on the Surface of Pure Aluminum Induced by High-Current Pulsed Electron Beam Irradiation

    Institute of Scientific and Technical Information of China (English)

    ZOU Yang; CAI Jie; WAN Ming-Zhen; LV Peng; GUAN Qing-Feng

    2011-01-01

    The mechanism of micropores formed on the surface of polycrystalline pure aluminum under high-current pulsed electron beam (HCPEB) irradiation is explained. It is discovered that dispersed micropores with sizes of 0.1-1μm on the irradiated surface of pure aluminum can be successfully fabricated after HCPEB irradiation. The dominant formation mechanism of the surface micropores should be attributed to the formation of supersaturation vacancies within the near surface during the HCPEB irradiation and the migration of vacancies along gra,in boundaries and/or dislocations towards the irradiated surface. It is expected that the HCPEB technique will become a new method for the rapid synthesis of surface porous materials.%The mechanism of micropores formed on the surface of polycrystalline pure aluminum under high-current pulsed electron beam (HCPEB) irradiation is explained.It is discovered that dispersed micropores with sizes of 0.1-1μm on the irradiated surface of pure aluminum can be successfully fabricated after HCPEB irradiation.The dominant formation mechanism of the surface micropores should be attributed to the formation of supersaturation vacancies within the near surface during the HCPEB irradiation and the migration of vacancies along grain boundaries and/or dislocations towards the irradiated surface.It is expected that the HCPEB technique will become a new method for the rapid synthesis of surface porous materials.High-current pulsed electron beams (HCPEBs)have attracted much attention in the field of material surface modification.[1-7] During the transient bombardment process a high energy (108-109 W·cm-2) is deposited only in a very thin layer (less than tens of micrometers) within a very short time (a few microseconds) and thereby causes ultrafast heating and cooling on the irradiated surface of materials.The dynamic stress fields induced in these processes can induce intense deformation on the material surface.

  17. Electron Beam Ion Sources

    CERN Document Server

    Zschornacka, G.; Thorn, A.

    2013-12-16

    Electron beam ion sources (EBISs) are ion sources that work based on the principle of electron impact ionization, allowing the production of very highly charged ions. The ions produced can be extracted as a DC ion beam as well as ion pulses of different time structures. In comparison to most of the other known ion sources, EBISs feature ion beams with very good beam emittances and a low energy spread. Furthermore, EBISs are excellent sources of photons (X-rays, ultraviolet, extreme ultraviolet, visible light) from highly charged ions. This chapter gives an overview of EBIS physics, the principle of operation, and the known technical solutions. Using examples, the performance of EBISs as well as their applications in various fields of basic research, technology and medicine are discussed.

  18. Nanostructure Formations and Improvement in Corrosion Resistance of Steels by Means of Pulsed Electron Beam Surface Treatment

    Directory of Open Access Journals (Sweden)

    K. M. Zhang

    2013-01-01

    Full Text Available The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nanostructure formations of steels by using a low energy high pulsed electron beam (LEHCPEB treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels.

  19. WC/Co composite surface structure and nano graphite precipitate induced by high current pulsed electron beam irradiation

    Science.gov (United States)

    Hao, S. Z.; Zhang, Y.; Xu, Y.; Gey, N.; Grosdidier, T.; Dong, C.

    2013-11-01

    High current pulsed electron beam (HCPEB) irradiation was conducted on a WC-6% Co hard alloy with accelerating voltage of 27 kV and pulse duration of 2.5 μs. The surface phase structure was examined by using glancing-angle X-ray diffraction (GAXRD), scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) methods. The surface tribological properties were measured. It was found that after 20 pulses of HCPEB irradiation, the surface structure of WC/Co hard alloy was modified dramatically and composed of a mixture of nano-grained WC1-x, Co3W9C4, Co3W3C phases and graphite precipitate domains ˜50 nm. The friction coefficient of modified surface decreased to ˜0.38 from 0.6 of the initial state, and the wear rate reduced from 8.4 × 10-5 mm3/min to 6.3 × 10-6 mm3/min, showing a significant self-lubricating effect.

  20. Amplification of picosecond pulse by electron-beam pumped KrF laser amplifiers. Denshi beam reiki KrF laser zofukuki ni yoru piko byo pulse no zofuku

    Energy Technology Data Exchange (ETDEWEB)

    Okuda, I.; Tomie, T.; Owadano, Y.; Yano, M. (Electrotechnical Laboratory, Tsukuba (Japan))

    1991-08-20

    Experiments on the amplification of a picosecond pulse by electron-beam pumped KrF laser amplifiers were carried out for the purpose of its application to the field such as excitation light source for soft X-ray laser which requires large energy besides peak power. The picosecond pulse was amplified by a discharge pumped KrF amplifier and two electron-beam pumped KrF amplifiers(at the middle stage and the final stage). The energy of 4J, which was the largest energy for short pulse excimer laser so far, was obtained by these devices. About 90% of the window area of the final amplifier with 29cm diameter was filled by the input beam, and energy density of the picosecond beam reached 3.9 times saturation energy density. Measured energy of amplified spontaneous emission(ASE) showed good agreement with the theoretically estimated value. Most of ASE was derived from the discharge pumped laser as the first amplifier. As for the focused power density, the power density ratio of the picosecond pulse to ASE was estimated to be as large as 10{sup 5}. 11 refs., 4 figs.

  1. Pulsed electron beam deposition of highly oriented thin films of polytetrafluoroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, Vimlesh [Materials Chemistry Laboratory, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Manoharan, Solomon S. [Materials Chemistry Laboratory, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016 (India)], E-mail: ssundar@iitk.ac.in

    2008-04-30

    Thin films of polytetrafluoroethylene (PTFE) were deposited by pulsed electron deposition (PED) technique. The transmission electron microscopy (TEM) image of the RT fabricated (20 A thick) film on carbon coated copper grid shows crystalline nature. Infrared spectra show one to one correspondence between PED ablated film and the PTFE bulk target. The asymmetrical and symmetrical -CF{sub 2}- stretching modes were observed at 1220 and 1156 cm{sup -1}, respectively. The -CF{sub 2}- wagging and bending modes occur at 644 and 512 cm{sup -1}, respectively. X-ray diffraction patterns of the film deposited at room temperature (RT) show oriented film along (1 0 0) plane of hexagonal structure and the crystalline nature is retained up to 300 deg. C on vacuum annealing. The room temperature fabricated film shows smooth and pin hole free surface whereas post-annealing brings discontinuity, roughness and pin holes.

  2. Narrow gap TIG and electron beam weld inspection in austenitic stainless steel using pulse echo, TOFD and phased array ultrasonics

    Energy Technology Data Exchange (ETDEWEB)

    Quirk, K.P.; Turner, J.L. [Phoenix Inspection Systems Limited, Warrington (United Kingdom)

    2004-07-01

    'Full-text:' Narrow gap Tungsten Inert Gas (TIG) and Electron Beam (EB) welding techniques are being considered for the splice joint welds on the austenitic stainless steel Vacuum Vessel in the next generation of experimental Fusion Power stations under the ITER programme. Under the programme there is a requirement to develop automated ultrasonic NDT techniques to inspect material up to 60 mm thick in both weld types. These narrow welds are difficult to inspect because of the steep fusion faces made more difficult in this project by the beam scattering effects of austenitic stainless steel welds and the very limited access from only one side of the vessel. The paper details the development of the combined Pulse Echo, TOFD and Phased Array techniques on behalf of ITER. The authors describe the philosophy behind the inspections, results and possible transfer of the technology to other sectors of industry. (author)

  3. Strengthening effect of nano-scaled precipitates in Ta alloying layer induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Guangze; Luo, Dian; Fan, Guohua [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin, E-mail: maxin@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2017-05-01

    Highlights: • Ta alloying layer are fabricated by magnetron sputtering and high current pulsed electron beam. • Nano-scaled TaC precipitates forms within the δ-Fe grain after tempering treatment. • The mean diameter of TaC particles is about 5–8 nm. • The hardness of alloying layer increased by over 50% after formation of nano-scaled TaC particle. - Abstract: In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6 μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823 K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5–8 nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1 GPa when the treated temperature is 823 K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.

  4. Pulsed electron beam deposition of transparent conducting Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Quang, Pham Hong, E-mail: phquang2711@yahoo.com [Hanoi University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam); Sang, Ngo Dinh [National University of Civil Engineering, 55 Giai Phong Street, Hai Ba Trung, Hanoi (Viet Nam); Ngoc, Do Quang [Hanoi University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam)

    2012-08-31

    Good quality transparent conducting Al-doped ZnO films were deposited on quartz substrates from a high purity target using pulsed electron deposition (PED). Two series of films were made, one deposited at room temperature but at four pressures, viz., 0.7, 1.3, 2.0 and 2.7 Pa of oxygen and one deposited at 1.3 Pa oxygen pressure but at the substrate temperature ranged from room temperature to 600 Degree-Sign C. In order to evaluate the effect of substrate temperature and oxygen pressure on the properties of obtained films, various characterization techniques were employed including X-ray diffraction, stylus profiler, scanning electron microscope, optical spectrophotometer and electrical resistivity. For the first series films, the optimal oxygen pressure of 1.3 Pa was found to bring about the appropriate energetic deposition atoms which results in the best crystallinity. For the second series films, the lowest resistivity was obtained in the film grown at 400 Degree-Sign C. An attempt was made to reduce the resistivity by lowering the oxygen pressure to 0.5 Pa which was the lower limit of working pressure of the PED system. The obtained results indicate that PED is a suitable technique for growing transparent conducting ZnO films. - Highlights: Black-Right-Pointing-Pointer Transparent conducting Al-doped ZnO films grown by pulsed electron deposition (PED). Black-Right-Pointing-Pointer The film properties were found to depend strongly on the deposition conditions. Black-Right-Pointing-Pointer The best film was grown at the oxygen pressure of 0.5 Pa and at 400 Degree-Sign C. Black-Right-Pointing-Pointer PED is found to be a suitable technique for growing transparent conducting ZnO films.

  5. Growth of doped silicon nanowires by pulsed laser deposition and their analysis by electron beam induced current imaging

    Energy Technology Data Exchange (ETDEWEB)

    Eisenhawer, B; Berger, A; Christiansen, S [Institute of Photonic Technology, Albert-Einstein-Strasse 9, 07745 Jena (Germany); Zhang, D; Clavel, R [Laboratory of Robotic Systems, Ecole Polytechnique Federale de Lausanne (EPFL), Station 9, CH-1015 Lausanne (Switzerland); Michler, J, E-mail: bjoern.eisenhawer@ipht-jena.de [Mechanics of Materials and Nanostructures Laboratory, EMPA-Materials Science and Technology, Feuerwerkstrasse 39, CH-3602 Thun (Switzerland)

    2011-02-18

    Doped silicon nanowires (NWs) were epitaxially grown on silicon substrates by pulsed laser deposition following a vapour-liquid-solid process, in which dopants together with silicon atoms were introduced into the gas phase by laser ablation of lightly and highly doped silicon target material. p-n or p{sup ++}-p junctions located at the NW-silicon substrate interfaces were thus realized. To detect these junctions and visualize them the electron beam induced current technique and two-point probe current-voltage measurements were used, based on nanoprobing individual silicon NWs in a scanning electron microscope. Successful silicon NW doping by pulsed laser deposition of doped target material could experimentally be demonstrated. This doping strategy compared to the commonly used doping from the gas phase during chemical vapour deposition is evaluated essentially with a view to potentially overcoming the limitations of chemical vapour deposition doping, which shows doping inhomogeneities between the top and bottom of the NW as well as between the core and shell of NWs and structural lattice defects, especially when high doping levels are envisaged. The pulsed laser deposition doping technique yields homogeneously doped NWs and the doping level can be controlled by the choice of the target material. As a further benefit, this doping procedure does not require the use of poisonous gases and may be applied to grow not only silicon NWs but also other kinds of doped semiconductor NWs, e.g. group III nitrides or arsenides.

  6. Surface Nanocrystallization of 3Cr13 Stainless Steel Induced by High-Current Pulsed Electron Beam Irradiation

    Directory of Open Access Journals (Sweden)

    Zhiyong Han

    2013-01-01

    Full Text Available The nanocrystalline surface was produced on 3Cr13 martensite stainless steel surface using high-current pulsed electron beam (HCPEB technique. The structures of the nanocrystallized surface were characterized by X-ray diffraction and electron microscopy. Two nanostructures consisting of fine austenite grains (50–150 nm and very fine carbides precipitates are formed in melted surface layer after multiple bombardments via dissolution of carbides and crater eruption. It is demonstrated that the dissolution of the carbides and the formation of the supersaturated Fe (C solid solution play a determining role on the microstructure evolution. Additionally, the formation of fine austenite structure is closely related to the thermal stresses induced by the HCPEB irradiation. The effects of both high carbon content and high value of stresses increase the stability of the austenite, which leads to the complete suppression of martensitic transformation.

  7. Transmission electron microscopy studying of structural features of NiTi B2 phase formed under pulsed electron-beam impact

    Energy Technology Data Exchange (ETDEWEB)

    Meisner, Ludmila L.; Semin, Viktor O.; Gudimova, Ekaterina Y. [Institute of Strength Physicists and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Neiman, Alexey A., E-mail: nasa@ispms.tsc.ru; Lotkov, Alexander I.; Ostapenko, Marina G. [Institute of Strength Physicists and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Koval, Nikolai N.; Teresov, Anton D. [National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Institute of High Current Electronics SB RAS, Tomsk, 634055 (Russian Federation)

    2015-10-27

    By transmission electron microscopy method the evolution of structural-phase states on a depth of close to equiatomic NiTi modified layer has been studied. Modification performed by pulse impact on its surface low-energy high-current electron beam (beam energy density 10 J/sm{sup 2}, 10 pulses, pulse duration 50mks). It is established that during the treatment in the layer thickness of 8–10 μm, the melting of primary B2 phase and contained therein as Ti2Ni phase particles occurs. The result is change in the concentration ratio of titanium and nickel in the direction of increasing titanium content, which was confirmed by X-ray analysis in the form of increased unit cell parameter B2 phase. Analysis of the electron diffraction pattern showed that the modified layer is characterized as a highly distorted structure on the basis of bcc lattice. Lattice distortions are maximal near the surface and extends to a depth of melt. In subjacent layer there is gradual decline lattice distortions is observed.

  8. Low emittance electron beam generation from a laser wakefield accelerator using two laser pulses with different wavelengths

    CERN Document Server

    Xu, X L; Zhang, C J; Li, F; Wan, Y; Hua, J F; Pai, C -H; Lu, W; Yu, P; Joshi, C; Mori, W B

    2014-01-01

    Ionization injection triggered by short wavelength laser pulses inside a nonlinear wakefield driven by a longer wavelength laser is examined via multi-dimensional particle-in-cell simulations. We find that very bright electron beams can be generated through this two-color scheme in either collinear propagating or transverse colliding geometry. For a fixed laser intensity $I$, lasers with longer/shorter wavelength $\\lambda$ have larger/smaller ponderomotive potential ($\\propto I \\lambda^2$). The two color scheme utilizes this property to separate the injection process from the wakefield excitation process. Very strong wakes can be generated at relatively low laser intensities by using a longer wavelength laser driver (e.g. a $10 \\micro\\meter$ CO$_2$ laser) due to its very large ponderomotive potential. On the other hand, short wavelength laser can produce electrons with very small residual momenta ($p_\\perp\\sim a_0\\sim \\sqrt{I}\\lambda$) inside the wake, leading to electron beams with very small normalized emit...

  9. Particle-in-cell simulation of electron trajectories and irradiation uniformity in an annular cathode high current pulsed electron beam source

    Science.gov (United States)

    Jiang, Wei; Wang, Langping; Zhou, Guangxue; Wang, Xiaofeng

    2017-02-01

    In order to study electron trajectories in an annular cathode high current pulsed electron beam (HCPEB) source based on carbon fiber bunches, the transmission process of electrons emitted from the annular cathode was simulated using a particle-in-cell model with Monte Carlo collisions (PIC-MCC). The simulation results show that the intense flow of the electrons emitted from the annular cathode are expanded during the transmission process, and the uniformity of the electron distribution is improved in the transportation process. The irradiation current decreases with the irradiation distance and the pressure, and increases with the negative voltage. In addition, when the irradiation distance and the cathode voltage are larger than 40 mm and -15 kV, respectively, a uniform irradiation current distribution along the circumference of the anode can be obtained. The simulation results show that good irradiation uniformity of circular components can be achieved by this annular cathode HCPEB source.

  10. Beams 92: Proceedings. Volume 1: Invited papers, pulsed power

    Energy Technology Data Exchange (ETDEWEB)

    Mosher, D.; Cooperstein, G. [eds.] [Naval Research Lab., Washington, DC (United States)

    1993-12-31

    This report contains papers on the following topics: Ion beam papers; electron beam, bremsstrahlung, and diagnostics papers; radiating Z- pinch papers; microwave papers; electron laser papers; advanced accelerator papers; beam and pulsed power applications papers; pulsed power papers; and these papers have been indexed separately elsewhere.

  11. Grain refinement, hardening and metastable phase formation by high current pulsed electron beam (HCPEB) treatment under heating and melting modes

    Energy Technology Data Exchange (ETDEWEB)

    Grosdidier, T., E-mail: Thierry.grosdidier@univ-metz.f [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Lab of Materials Modification by Laser, Ion and Electron Beams and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Zou, J.X. [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Bolle, B. [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), ENIM, Ile du Saulcy, 57045 Metz (France); Hao, S.Z.; Dong, C. [Lab of Materials Modification by Laser, Ion and Electron Beams and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2010-08-15

    High current pulsed electron beam is a recently developed technique for surface modification. The pulsed electron irradiation introduces concentrated energy depositions in the thin surface layer of the treated materials, giving rise to an extremely fast heating and subsequent rapid cooling of the surface together with the formation of dynamic stress waves. Improved surface properties (hardness, corrosion resistance) can be obtained under the 'melting' mode when the top surface is melted and rapidly solidified (10{sup 7} K/s). In steels, this is essentially the result of nanostructures formed from the highly undercooled melt, melt surface purification, strain hardening induced by the thermal stress waves as well as metastable phase selections in the rapidly solidified melted layers. The use of the 'heating' mode is less conventional, combining effects of the heavy deformation and recrystallization/recovery mechanisms. A detailed analysis of a FeAl alloy demonstrates grain size refinement, hardening, solid-state enhanced diffusion and texture modification without modification of the surface geometry.

  12. Improvement of Wear Resistance of Magnesium Alloy AZ91HP by High Current Pulsed Electron Beam Treatment

    Institute of Scientific and Technical Information of China (English)

    GAO Bo; HAO Sheng-zhi; ZOU Jian-xin; JIANG Li-min; ZHOU Ji-yang; DONG Chuang

    2004-01-01

    Surface modification of magnesium alloy AZ91HP (9wt%Al, 0.5wt%Zn, 0.5wt%Mn, Mg remaining percentage) by high current pulsed electron beam (HCPEB) treatment was studied in this paper. The secondary phase Mg17Al12 is nearly completely dissolved and as a result, a super-saturated solid solution forms on the re-melted surface.The microhardness is increased both in and far beyond the heat-affected zone (HAZ), reaching about 250μm.Measurements on sliding wear have shown that the wear resistance of the treated samples was improved by a factor of about 2.4 as compared to the as-received sample. It is also found that the sliding wear resistance can be further improved by surface alloying with TiN.

  13. Ultracold ordered electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Habs, D.; Kramp, J.; Krause, P.; Matl, K.; Neumann, R.; Schwalm, D.

    1988-01-01

    We have started an experimental program to develop an ultracold electron beam, which can be used together with a standard electron cooling device in the Heidelberg Test Storage Ring TSR. In contrast to the standard-type design using electron beam extraction beam extraction from a heated cathode, the ultracold beam is produced by photoemission of electrons from a cooled semiconductor crystal irradiated with an intense near-infrared laser light beam. Adiabatic acceleration is expected to provide ordering of the electron beam itself. Besides the cooling of ion beams to extremely low temperatures, with the aim of obtaining crystallization, the ultracold beam will constitute an excellent target for atomic physics experiments.

  14. Pulsed electron-beam-pumped laser based on AlGaN/InGaN/GaN quantum-well heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Gamov, N A; Zhdanova, E V; Zverev, M M; Peregudov, D V; Studenov, V B [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation); Mazalov, A V; Kureshov, V A; Sabitov, D R; Padalitsa, A A; Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

    2015-07-31

    The parameters of pulsed blue-violet (λ ≈ 430 nm at T = 300 K) lasers based on an AlGaN/InGaN/GaN structure with five InGaN quantum wells and transverse electron-beam pumping are studied. At room temperature of the active element, the minimum electron energy was 9 keV and the minimum threshold electron beam current density was 8 A cm{sup -2} at an electron energy of 18 keV. (lasers)

  15. Electron beam focusing system

    Energy Technology Data Exchange (ETDEWEB)

    Dikansky, N.; Nagaitsev, S.; Parkhomchuk, V.

    1997-09-01

    The high energy electron cooling requires a very cold electron beam. Thus, the electron beam focusing system is very important for the performance of electron cooling. A system with and without longitudinal magnetic field is presented for discussion. Interaction of electron beam with the vacuum chamber as well as with the background ions and stored antiprotons can cause the coherent electron beam instabilities. Focusing system requirements needed to suppress these instabilities are presented.

  16. Ultracold Ordered Electron Beam

    Science.gov (United States)

    Habs, D.; Kramp, J.; Krause, P.; Matl, K.; Neumann, R.; Schwalm, D.

    1988-01-01

    We have started an experimental program to develop an ultracold electron beam, which can be used together with a standard electron cooling device in the Heidelberg Test Storage Ring TSR. In contrast to the standard-type design using electron beam extraction from a heated cathode, the ultracold beam is produced by photoemission of electrons from a cooled semiconductor crystal irradiated with an intense near-infrared laser light beam. Adiabatic acceleration is expected to provide ordering of the electron beam itself. Besides the cooling of ion beams to extremely low temperatures, with the aim of obtaining crystallization, the ultracold beam will constitute an excellent target for atomic physics experiments.

  17. Characterization of pulsed x-ray beams for tests of electronic dosemeter performance; Caracterizacao de feixes de raios X pulsados para testes de desempenho de dosimetros eletronicos

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, Margarete C.; Silva, Teogenes A. da, E-mail: mcg@cdtn.br, E-mail: silvata@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Curso de Pos-Graduacao em Ciencias e Tecnologia das Radiacoes, Materiais e Minerais

    2013-10-01

    Electronic dosimeters, due to direct reading, have been increasingly used for individual or area monitoring for purposes of radiation protection in X-ray fields used in diagnostic radiology. Deficiencies of performance in pulsed beams of such dosimeters have been published, which are not detected by the calibration procedures and performance tests established by international standards only for continuous beams of radiation. In Brazil, there are no performance requirements of dosimeters in pulsed beams, or a laboratory that performs testing for reliability in the use of dosimeters. This study aims to characterize the X-ray machine Medical VMI 800 Plus in the Laboratory Calibration of Dosimeters of CDTN/CNEN - Brazilian CNEN institute - and study the feasibility of its use for performance testing of electronic dosimeters. (author)

  18. Pulsed electron beam excited transient absorption in SrTiO sub 3

    CERN Document Server

    Millers, D; Pankratov, V V; Trepakov, V A; Kapphan, S E

    2002-01-01

    Transient absorption (TA) spectra and optical density relaxation kinetics in SrTiO sub 3 (STO), STO-Nb and STO-V were studied. The electron polaron free or bound at intrinsic defect is suggested to be responsible for the TA band at approx 1.4 eV observed in STO. The band peaking below 0.75 eV in STO-Nb is proposed to be from Nb sup 4 sup +. The electron center V sup 3 sup + or electron polaron bound in the vicinity of V sup 4 sup + is responsible for the absorption band at 1.0 eV in STO-V. The absorption from hole polarons is suggested to be in the range 1.8-2.3 eV. It is shown that TA in pure STO at room temperature decays due to electron-hole polaron recombination.

  19. Transient effects in beam-plasma interactions in a space simulation chamber stimulated by a fast pulse electron gun

    Science.gov (United States)

    Raitt, W. J.; Banks, P. M.; Denig, W. F.; Anderson, H. R.

    1982-01-01

    Interest in the interaction of electron beams with plasma generated by ionization caused by the primary electron beam was stimulated by the need to develop special vacuum tubes to operate in the kMHz frequency region. The experiments of Getty and Smullin (1963) indicated that the interaction of an energetic electron beam with its self-produced plasma resulted in the emission of wave energy over a wide range of frequencies associated with cyclotron and longitudinal plasma instabilities. This enhanced the thermal plasma density in the vicinity of the beam, and the term Beam-Plasma Discharge (BPD) was employed to described this phenomenon. The present investigation is concerned with some of the transient phenomena associated with wave emission during the beam switch-on and switch-off periods. Results are presented on the changes in electron energy spectra on a time scale of tens of milliseconds following beam switch-on. The results are discussed in terms of the beam plasma discharge phenomenon.

  20. Improvement of wear resistance of AZ31 and AZ91HP by high current pulsed electron beam treatment

    Institute of Scientific and Technical Information of China (English)

    GAO Bo; HAO Sheng-zhi; DONG Chuang; TU Gan-feng

    2005-01-01

    The surface modification of magnesium alloys (AZ31 and AZ91HP) was studied by a high current pulsed electron beam(HCPEB). The results show that the cross-sectional microhardness of treated samples increases not only in the heat affected zone(HAZ), but also beyond HAZ, reaching over 250 μm. This is due to the action of quasi-static thermal stress and the shock thermal stress wave with materials, which result in its fast deformation on the surface layer and so increases microhardness. For the AZ91HP alloy, a nearly complete dissolution of the intermetallic phase Mg17Al12 is observed, and a super-saturated solid solution forms on the re-melted surface, which is due to the solute trapping effect during the fast solidification process. Measurements on sliding wear show that wear resistance is improved by approximately 5.6 and 2.4 times for the AZ31 and AZ91HP respectively, as compared with as-received samples.

  1. Enhanced thermotolerance and ethanol tolerance in Saccharomyces cerevisiae mutated by high-energy pulse electron beam and protoplast fusion.

    Science.gov (United States)

    Zhang, Min; Xiao, Yu; Zhu, Rongrong; Zhang, Qin; Wang, Shi-Long

    2012-11-01

    To increase thermotolerance and ethanol tolerance in Saccharomyces cerevisiae strain YZ1, the strategies of high-energy pulse electron beam (HEPE) and three rounds of protoplast fusion were explored. The YF31 strain had the characteristics of resistant to high-temperature, high-ethanol tolerance, rapid growth and high yield. The YF31 could grow on plate cultures up to 47 °C, containing 237.5 g L(-1) of ethanol. In particular, the mutant strain YF31 generated 94.2 ± 4.8 g L(-1) ethanol from 200 g glucose L(-1) at 42 °C, which was 2.48 times the production of the wild strain YZ1. Results demonstrated that the variant phenotypes from the strains screening by HEPE irradiation could be used as parent stock for yeast regeneration and the protoplast fusion technology is sufficiently powerful in combining suitable characteristics in a single strain for ethanol fermentation.

  2. Change of texture, microdeformation and hardness in surface layer of TiNi alloy depending on the number of pulses of electron beam effects

    Energy Technology Data Exchange (ETDEWEB)

    Meisner, L. L., E-mail: llm@ispms.tsc.ru; Meisner, S. N., E-mail: msn@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Markov, A. B., E-mail: a.markov@hq.tsc.ru; Yakovlev, E. V., E-mail: yakovev@lve.hcei.tsc.ru; Ozur, G. E., E-mail: ozur@lve.hcei.tsc.ru [Institute of High Current Electronics SB RAS, Tomsk, 634055 (Russian Federation); Rotshtein, V. P., E-mail: vrotshtein@yahoo.com [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Tomsk State Pedagogical University, Tomsk, 634050 (Russian Federation); Mironov, Yu. P., E-mail: myp@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation)

    2015-10-27

    This work comprises a study of the influence of the pulse number of low-energy high-current electron beam (LEHCEB) exposure on the value and character of distribution of residual elastic stresses, texturing effects and the relationship between structural-phase states and physical and mechanical properties of the modified surface layers of TiNi alloy. LEHCEB processing of the surface of TiNi samples was carried out using a RITM-SP [3] installation. Energy density of electron beam was constant at E{sub s} = 3.9 ± 0.5 J/cm{sup 2}; pulse duration was 2.8 ± 0.3 μs. The number of pulses in the series was changeable, (n = 2–128). It was shown that as the result of multiple LEHCEB processing of TiNi samples, hierarchically organized multilayer structure is formed in the surface layer. The residual stress field of planar type is formed in the modified surface layer as following: in the direction of the normal to the surface the strain component ε{sub ⊥} < 0 (compressing strain), and in a direction parallel to the surface, the strain component ε{sub ||} > 0 (tensile deformation). Texturing effects and the level of residual stresses after LEHCEB processing of TiNi samples with equal energy density of electron beam (∼3.8 J/cm{sup 2}) depend on the number of pulses and increase with the rise of n > 10.

  3. Pulsed electron beam precharger. Technical progress report No. 5-6, September 1, 1990--February 28, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. [ed.; Shelton, W.N.

    1991-12-31

    Electron beam precharging of a high resistivity aerosol was successfully demonstrated during this reporting period (Quarters Five and Six). The initial E-beam particle precharging experiments completed this term were designed to confirm and extend some of the work performed under the previous contract. There are several reasons for doing this: (1) to re-establish a baseline performance criterion for comparison to other runs, (2) to test several recently upgraded or repaired subsystems, and (3) to improve upon the collection efficiency of the electron beam precipitator when testing precharging effectiveness with a very high resistivity, moderate-to-high concentration dust load. In addition, these shakedown runs were used to determine a set of suitable operational parameters for the wind tunnel, the electrostatic collecting sections, and the MINACC E-beam accelerator. These parameters will generally be held constant while the precharging parameters are varied to produce an optimum particle charge.

  4. Libera Electron Beam Position Processor

    CERN Document Server

    Ursic, Rok

    2005-01-01

    Libera is a product family delivering unprecedented possibilities for either building powerful single station solutions or architecting complex feedback systems in the field of accelerator instrumentation and controls. This paper presents functionality and field performance of its first member, the electron beam position processor. It offers superior performance with multiple measurement channels delivering simultaneously position measurements in digital format with MHz kHz and Hz bandwidths. This all-in-one product, facilitating pulsed and CW measurements, is much more than simply a high performance beam position measuring device delivering micrometer level reproducibility with sub-micrometer resolution. Rich connectivity options and innate processing power make it a powerful feedback building block. By interconnecting multiple Libera electron beam position processors one can build a low-latency high throughput orbit feedback system without adding additional hardware. Libera electron beam position processor ...

  5. Structural, Optical, and Dielectric Investigations of the Relaxor PLZT 9,75/65/35 Ceramics Irradiated by High-Current Pulsed Electron Beam

    CERN Document Server

    Efimov, V V; Kalmikov, A V; Klevtsova, E A; Minashkin, V F; Novikova, N N; Sikolenko, V V; Skripnik, A V; Sternberg, A; Tiutiunnikov, S I; Yakovlev, V A

    2002-01-01

    First time comprehensive study of high-current pulsed electron irradiation effects on the structural, optical and dielectric properties of relaxor (Pb_{(1-x)}La^{x}(Zr_{0.65}Ti_{0.35})_{1-x/4}O_{3} ceramics with x=9.75% has been provided. The electron beam had the following parameters: energy E_{e}=250 keV, current density J_{e}=1000 A/cm^{2}, pulse duration tau = 300 ns, density 10^{15} electrons/cm^{2} per pulse. Infrared reflectivity spectra in the region of 100-2000 cm^{-1} were obtained in virgin, irradiated by 1500 pulses and annealed up to t=500^{circ}C ceramics. The reconstruction of perovskite ABO_{3} structure in irradiated samples has been studied by complex use of X-ray and neutron scattering and IR spectroscopy techniques revealing the changes in transverse and longitudinal phonon modes, oscillators strength and damping of modes. Radiation effects on temperature behaviour of dielectric permittivity in the region of phase transition were studied. The possible mechanisms of pulsed electron irradiat...

  6. Pulsed Electron Holography

    CERN Document Server

    Germann, Matthias; Escher, Conrad; Fink, Hans-Werner

    2013-01-01

    A technique of pulsed low-energy electron holography is introduced that allows for recording highly resolved holograms within reduced exposure times. Therefore, stacks of holograms are accumulated in a pulsed mode with individual acquisition times as short as 50 {\\mu}s. Subsequently, these holograms are aligned and finally superimposed. The resulting holographic record reveals previously latent high-order interference fringes and thereby pushing interference resolution into the sub-nanometer regime. In view of the non-damaging character of low-energy electrons, the method is of particular interest for structural analysis of fragile biomolecules.

  7. Low Emittance Electron Beam Studies

    Energy Technology Data Exchange (ETDEWEB)

    Tikhoplav, Rodion [Univ. of Rochester, NY (United States)

    2006-01-01

    We have studied the properties of a low emittance electron beam produced by laser pulses incident onto an rf gun photocathode. The experiments were carried out at the A0 photoinjector at Fermilab. Such beam studies are necessary for fixing the design of new Linear Colliders as well as for the development of Free Electron Lasers. An overview of the A0 photoinjector is given in Chapter 1. In Chapter 2 we describe the A0 photoinjector laser system. A stable laser system is imperative for reliable photoinjector operation. After the recent upgrade, we have been able to reach a new level of stability in the pulse-to-pulse fluctuations of the pulse amplitude, and of the temporal and transverse profiles. In Chapter 3 we present a study of transverse emittance versus the shape of the photo-cathode drive-laser pulse. For that purpose a special temporal profile laser shaping device called a pulse-stacker was developed. In Chapter 4 we discuss longitudinal beam dynamics studies using a two macro-particle bunch; this technique is helpful in analyzing pulse compression in the magnetic chicane, as well as velocity bunching effects in the rf-gun and the 9-cell accelerating cavity. In Chapter 5 we introduce a proposal for laser acceleration of electrons. We have developed a laser functioning on the TEM*01 mode, a mode with a longitudinal electric field component which is suitable for such a process. Using this technique at energies above 40 MeV, one would be able to observe laser-based acceleration.

  8. Stationary flow conditions in pulsed supersonic beams.

    Science.gov (United States)

    Christen, Wolfgang

    2013-10-21

    We describe a generally applicable method for the experimental determination of stationary flow conditions in pulsed supersonic beams, utilizing time-resolved electron induced fluorescence measurements of high pressure jet expansions of helium. The detection of ultraviolet photons from electronically excited helium emitted very close to the nozzle exit images the valve opening behavior-with the decided advantage that a photon signal is not affected by beam-skimmer and beam-residual gas interactions; it thus allows to conclusively determine those operation parameters of a pulsed valve that yield complete opening. The studies reveal that a "flat-top" signal, indicating constant density and commonly considered as experimental criterion for continuous flow, is insufficient. Moreover, translational temperature and mean terminal flow velocity turn out to be significantly more sensitive in testing for the equivalent behavior of a continuous nozzle source. Based on the widely distributed Even-Lavie valve we demonstrate that, in principle, it is possible to achieve quasi-continuous flow conditions even with fast-acting valves; however, the two prerequisites are a minimum pulse duration that is much longer than standard practice and previous estimates, and a suitable tagging of the appropriate beam segment.

  9. Arrays of holes fabricated by electron-beam lithography combined with image reversal process using nickel pulse reversal plating

    Science.gov (United States)

    Awad, Yousef; Lavallée, Eric; Lau, Kien Mun; Beauvais, Jacques; Drouin, Dominique; Cloutier, Melanie; Turcotte, David; Yang, Pan; Kelkar, Prasad

    2004-05-01

    A critical issue in fabricating arrays of holes is to achieve high-aspect-ratio structures. Formation of ordered arrays of nanoholes in silicon nitride was investigated by the use of ultrathin hard etch mask formed by nickel pulse reversal plating to invert the tonality of a dry e-beam resist patterned by e-beam lithography. Ni plating was carried out using a commercial plating solution based on nickel sulfamate salt without organic additives. Reactive ion etching using SF6/CH4 was found to be very effective for pattern transfer to silicon nitride. Holes array of 100 nm diam, 270 nm period, and 400 nm depth was fabricated on a 5×5 mm2 area. .

  10. High current H{sub 2}{sup +} and H{sub 3}{sup +} beam generation by pulsed 2.45 GHz electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yuan; Peng, Shixiang, E-mail: sxpeng@pku.edu.cn; Ren, Haitao; Zhao, Jie; Chen, Jia; Zhang, Tao; Guo, Zhiyu [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, Peking University, Beijing 100871 (China); Zhang, Ailin [University of Chinese Academy of Sciences, Beijing 100049 (China); Chen, Jia' er [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, Peking University, Beijing 100871 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2014-02-15

    The permanent magnet 2.45 GHz electron cyclotron resonance ion source at Peking University can produce more than 100 mA hydrogen ion beam working at pulsed mode. For the increasing requirements of cluster ions (H{sub 2}{sup +} and H{sub 3}{sup +}) in linac and cyclotron, experimental study was carried out to further understand the hydrogen plasma processes in the ion source for the generation of cluster ions. The constituents of extracted beam have been analyzed varying with the pulsed duration from 0.3 ms to 2.0 ms (repetition frequency 100 Hz) at different operation pressure. The fraction of cluster ions dramatically increased when the pulsed duration was lower than 0.6 ms, and more than 20 mA pure H{sub 3}{sup +} ions with fraction 43.2% and 40 mA H{sub 2}{sup +} ions with fraction 47.7% were obtained when the operation parameters were adequate. The dependence of extracted ion fraction on microwave power was also measured at different pressure as the energy absorbed by plasma will greatly influence electron temperature and electron density then the plasma processes in the ion source. More details will be presented in this paper.

  11. Effects of Laser Pulse Heating of Copper Photocathodes on High-brightness Electron Beam Production at Blowout Regime

    CERN Document Server

    Zheng, Lianmin; Tang, Chuanxiang; Gai, Wei

    2016-01-01

    Producing high-brightness and high-charge (>100 pC) electron bunches at blowout regime requires ultrashort laser pulse with high fluence. The effects of laser pulse heating of the copper photocathode are analyzed in this paper. The electron and lattice temperature is calculated using an improved two-temperature model, and an extended Dowell-Schmerge model is employed to calculate the thermal emittance and quantum efficiency. A time-dependent growth of the thermal emittance and the quantum efficiency is observed. For a fixed amount of charge, the projected thermal emittance increases with the decreasing laser radius, and this effect should be taken into account in the laser optimization at blowout regime. Moreover, laser damage threshold fluence is simulated, showing that the maximum local fluence should be less than 40 mJ/cm^2 to prevent damage to the cathode. The cryogenic effect on the laser pulse heating is studied, showing that the hazards caused by the laser pulse heating will be significantly mitigated ...

  12. The role of electro-explosion alloying with titanium diboride and treatment with pulsed electron beam in the surface modification of VT6 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Konovalov, Sergey, E-mail: konovserg@gmail.com; Gromov, Victor, E-mail: gromov@physics.sibsiu.ru; Kobzareva, Tatyana; Semina, Olga [Siberian State Industrial University, Novokuznetsk, 654007 (Russian Federation); Bataev, Vladimir, E-mail: vabataev@yandex.ru [Novosibirsk State Technical University, Novosibirsk, 630073 (Russian Federation); Ivanov, Yurii, E-mail: yufi55@mail.ru [Institute of High Current Electronics SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The paper presents the results of the investigation of VT6 titanium alloy subjected to electro-explosion alloying with TiB{sub 2} and irradiation with pulsed electron beam. It was established that electro-explosion alloying resulted in a high level of roughness of the surface layer with high adhesion of the modified layer and matrix. Further irradiation of the material with electron beam resulted in the smoothing of the surface of alloying and formation of a porous structure with various scale levels in the surface layer. It was also established that the energetic exposure causes the formation of a gradient structure with a changing elemental composition along the direction from the surface of alloying.

  13. Phase space distribution of an electron beam emerging from Compton/Thomson back-scattering by an intense laser pulse

    Science.gov (United States)

    Petrillo, V.; Chaikovska, I.; Ronsivalle, C.; Rossi, A. R.; Serafini, L.; Vaccarezza, C.

    2013-01-01

    We analyze the energy distribution of a relativistic electron beam after the Compton back-scattering by a counterpropagating laser field. The analysis is performed for parameters in the range of realistic X-γ sources, in the framework of the Quantum Electrodynamics, by means of the code CAIN. The results lead to the conclusion that, in the regime considered, the main effect is the initial formation of stripes, followed by the diffusion of the most energetic particles toward lower values in the longitudinal phase space, with a final increase of the electron energy bandwidth.

  14. Self-amplified spontaneous emission FEL with energy-chirped electron beam and its application for generation of attosecond x-ray pulses

    Directory of Open Access Journals (Sweden)

    E. L. Saldin

    2006-05-01

    Full Text Available Influence of a linear energy chirp in the electron beam on a self-amplified spontaneous emission (SASE Free Electron Laser (FEL operation is studied analytically and numerically using a 1D model. Analytical results are based on the theoretical background developed by Krinsky and Huang [Phys. Rev. ST Accel. Beams 6, 050702 (2003PRABFM1098-4402]. Explicit expressions for Green’s functions and for output power of a SASE FEL are obtained for the high-gain linear regime in the limits of small and large energy chirp parameters. Saturation length and power versus energy chirp parameter are calculated numerically. It is shown that the effect of linear energy chirp on FEL gain is equivalent to the linear undulator tapering (or linear energy variation along the undulator. A consequence of this fact is a possibility to perfectly compensate FEL gain degradation, caused by the energy chirp, by means of the undulator tapering independently of the value of the energy chirp parameter. An application of this effect for generation of attosecond pulses from a hard x-ray FEL is proposed. Strong energy modulation within a short slice of an electron bunch is produced by a few-cycle optical laser pulse in a short undulator, placed in front of the main undulator. Gain degradation within this slice is compensated by an appropriate undulator taper while the rest of the bunch suffers from this taper and does not lase. Three-dimensional simulations predict that short (200 attoseconds high-power (up to 100 GW pulses can be produced in Angstrom wavelength range with a high degree of contrast. A possibility to reduce pulse duration to sub-100 attosecond scale is discussed.

  15. Study on the nanostructure formation mechanism of hypereutectic Al–17.5Si alloy induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bo, E-mail: gaob@smm.neu.edu.cn [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Hu, Liang [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Li, Shi-wei [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Hao, Yi [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Zhang, Yu-dong [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France); Tu, Gan-feng [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Grosdidier, Thierry [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France)

    2015-08-15

    This work investigates the nanostructure forming mechanism of hypereutectic Al–17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1){sub Al}//(0 0 1){sub Si} with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al–Si alloys.

  16. Microstructure and property modifications of an AISI H13 (4Cr5MoSiV) steel induced by pulsed electron beam treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Kemin; Zou Jianxin; Grosdidier, Thierry; Dong Chuang [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Shanghai Engineering Research Center of Mg Materials and Applications and School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China) and Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine Metz, Ile du Saulcy, 57045 Metz (France); Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine Metz, Ile du Saulcy, 57045 Metz (France) and Laboratory of Materials Modification by Laser, Electron and Ion Beams, Dalian University of Technology, Dalian 116024 (China); Laboratory of Materials Modification by Laser, Electron and Ion Beams, Dalian University of Technology, Dalian 116024 (China)

    2010-11-15

    In the present work, surface modifications generated by the low energy high current pulsed electron beam (LEHCPEB) treatments have been investigated on an AISI H13 (4Cr5MoSiV) steel. From the observations of scanning electron microscopy, x-ray diffraction, and electron back scattering diffraction determinations, it could be established that the final structure in the melted layer is a mixture of ultrafine {delta} phase, martensite, and residual austenite. The formation of the heterogeneous microstructures on the surface layer is related to the very rapid heating, melting, solidification, and cooling induced by the LEHCPEB irradiation. After the LEHCPEB treatment, the wear resistance of the steel effectively improved. This can be mainly attributed to the higher hardness of the ultrafine structures formed on the top surface and the hardened subsurface layers after the treatment.

  17. Mechanical properties and corrosion behavior of the nitriding surface layer of Ti−6Al−7Nb using large pulsed electron beam (LPEB)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jisoo; Lee, Woo Jin; Park, Hyung Wook, E-mail: hwpark@unist.ac.kr

    2016-09-15

    Large pulsed electron beam (LPEB) irradiation was used as a single surface finishing process for Ti−Al−7Nb. Nitrogen plasma gas and cathodic apparatus have been adopted to induce nitriding effect of Ti−6Al−7Nb during the electron beam irradiation. The atomic concentration of nitrogen atoms at the re-solidified layer could be t5achieved up to ∼18% by LPEB nitriding. Nano-hardness in the re-solidified layer was improved by ∼75% following the irradiation process, as a result of a phase transformation and the formation of TiN. The re-solidified layer induced by the LPEB nitriding, consisted of TiN, TiO{sub 2}, and TiO{sub x}N{sub y}, indicated significantly modified corrosion resistance showing a nobler corrosion potential, decreased corrosion current density, and improved charge transfer resistance. The increasing fraction of TiN at the re-solidified layer, induced by LPEB nitriding, was suggested as being responsible for remarkable improvement of mechanical properties and corrosion resistance, embedding uniformly noble and stable characteristics at the top surface. The corrosion-resistant surface layer with superior mechanical properties on Ti−6Al−7Nb has been successfully demonstrated by LPEB nitriding technique. - Highlights: • The nitrogen plasma source facilitated the formation of TiN at the re-solidified layer induced by LPEB. • The negative DC bias increased TiN fraction at the re-solidified layer. • The passivation of re-solidified layer enhanced corrosion resistance of Ti−6Al−7Nb. • The formation of uniformly stable oxy-nitride layer increased corrosion resistance. • Large pulsed electron beam irradiation with N{sub 2} plasma source generated surface hardening.

  18. Beam dynamics in a long-pulse linear induction accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl [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; Mc Cuistian, 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; Rose, Chris R [Los Alamos National Laboratory; Sanchez, Manolito [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; Trainham, C [Los Alamos National Laboratory; Williams, John [Los Alamos National Laboratory; Scarpetti, Raymond [LLNL; Genoni, Thomas [VOSS; Hughes, Thomas [VOSS; Toma, Carsten [VOSS

    2010-01-01

    The second axis of the Dual Axis Radiography of Hydrodynamic Testing (DARHT) facility produces up to four radiographs within an interval of 1.6 microseconds. It accomplishes this by slicing four micro-pulses out of a long 1.8-kA, 16.5-MeV electron beam pulse and focusing them onto a bremsstrahlung converter target. The long beam pulse is created by a dispenser cathode diode and accelerated by the unique DARHT Axis-II linear induction accelerator (LIA). Beam motion in the accelerator would be a problem for radiography. High frequency motion, such as from beam breakup instability, would blur the individual spots. Low frequency motion, such as produced by pulsed power variation, would produce spot to spot differences. In this article, we describe these sources of beam motion, and the measures we have taken to minimize it.

  19. The effect of large-area pulsed electron beam melting on the corrosion and microstructure of a Ti6Al4V alloy

    Science.gov (United States)

    Walker, J. C.; Murray, J. W.; Nie, M.; Cook, R. B.; Clare, A. T.

    2014-08-01

    The use of titanium alloys in biomedical applications continues to increase due to the excellent stiffness to weight ratio and high corrosion resistance. In order to improve the surface wettability and corrosion properties of a Ti-6Al-4V alloy, the surface treatment method, large area electron beam melting technique was investigated. Polished samples were subject to pulsed treatments of 1, 15 and 25 at 1.38 J/cm2 beam energy. Surface roughness and contact wetting angles were reduced as a result of the treatment. Microstructural analysis of the surface by XRD and FIB-TEM revealed a martensitic alpha prime phase formed as a result of the high cooling rates induced by the treatment. The presence of this homogenous martensite layer was shown to facilitate a compact passive oxide layer formation during corrosion, thus improving corrosion rates by several orders of magnitude compared to an untreated sample. Large area electron beam melting of Ti-6Al-4V induced a number of changes to the near surface microstructure of the samples, all of which could be used to tailor mechanical and corrosion properties to that of a desired application, without compromising the bulk material properties. These are explored in detail in this work.

  20. Electronic regulation of the SPS extraction quadrupole current pulse shape for improved stability of the extracted beam

    CERN Document Server

    Carlier, E; Vossenberg, Eugène B; CERN. Geneva. SPS and LEP Division

    1996-01-01

    In order to minimise the event pile-up and therefore optimise the detection efficiency, Chorus and Nomad experiments ask for a long and rectangular spill profile. At present the fast-slow extractio n is generated by driving the beam into a quadrupolar-octopolar resonance by exciting a quadrupole magnet with a semi-trapezoidal current [1]. The trapezoidal pulse shape is obtained by dischargin g a capacitor into the magnet coils. After a few milliseconds of undamped discharge a fixed resistor is switched into the circuit. The attenuation is then higher and the sine wave continues with a lower gradient. The two gradients can be adjusted by varying the initial capacitor voltage and the time at which the resistor is switched into the circuit. A further degree of freedom in determini ng the spill shape has been added by allowing the possibility of changing the second slope value independently of the initial conditions. This task is achieved by means of a variable current sour ce added in parallel to the fixed resis...

  1. Numerical simulation of thermal-mechanical process of Al-Si-Pb alloy treated by high current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    L(U) Xiao-xia; LI Rong-guang; AN Jian

    2006-01-01

    The modified microstructure of Al-Si-Pb alloys irradiated by high current electron beam (HCPEB) reveals three distinct regions: a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone, and a transition zone followed by the substrate. The hardness and wear properties of the alloys were significantly improved. To better understand these changes in microstructure and properties, the physical model for the simulation of temperature and quasistatic stress fields was established. Based on experimental investigation and physical models, the temperature field and stress field were simulated for Al-Si-Pb alloy. The starting melting position, largest crater depth, melting layer thickness, and quasistatic stress distribution were obtained. These results reveal the mechanism of crater formation on the surface and improvement of hardness and wear resistance.

  2. The effect of large-area pulsed electron beam melting on the corrosion and microstructure of a Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Walker, J.C., E-mail: j.walker@soton.ac.uk [National Centre for Advanced Tribology at Southampton (nCATS), University of Southampton, Southampton SO17 1BJ (United Kingdom); Murray, J.W. [Institute for Advanced Manufacturing, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Nie, M.; Cook, R.B. [National Centre for Advanced Tribology at Southampton (nCATS), University of Southampton, Southampton SO17 1BJ (United Kingdom); Clare, A.T. [Institute for Advanced Manufacturing, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2014-08-30

    Graphical abstract: - Highlights: • Ti–6Al–4V alloy was large area electron beam melted at 1.38 J/cm{sup 2} energy density. • An alpha prime martensitic phase transformation occurred at the surface. • The surface martensite enhanced the corrosion rate by two orders of magnitude. • The treatment reduced the surface roughness and improved surface wettability. - Abstract: The use of titanium alloys in biomedical applications continues to increase due to the excellent stiffness to weight ratio and high corrosion resistance. In order to improve the surface wettability and corrosion properties of a Ti–6Al–4V alloy, the surface treatment method, large area electron beam melting technique was investigated. Polished samples were subject to pulsed treatments of 1, 15 and 25 at 1.38 J/cm{sup 2} beam energy. Surface roughness and contact wetting angles were reduced as a result of the treatment. Microstructural analysis of the surface by XRD and FIB-TEM revealed a martensitic alpha prime phase formed as a result of the high cooling rates induced by the treatment. The presence of this homogenous martensite layer was shown to facilitate a compact passive oxide layer formation during corrosion, thus improving corrosion rates by several orders of magnitude compared to an untreated sample. Large area electron beam melting of Ti–6Al–4V induced a number of changes to the near surface microstructure of the samples, all of which could be used to tailor mechanical and corrosion properties to that of a desired application, without compromising the bulk material properties. These are explored in detail in this work.

  3. Accordion effect in a laser wakefield accelerator: Generating comb-like electron beams for a tunable pulsed source of polychromatic gamma-rays

    Science.gov (United States)

    Kalmykov, Serge; Davoine, Xavier; Ghebregziabher, Isaac; Shadwick, Bradley

    2016-10-01

    Trains of synchronized, fs-length GeV-scale electron bunches with a sub-micron normalized transverse emittance, brightness up to 1017 A/m2, and controlled energy spacing may be purposely produced in both plasma channels and uniform plasmas. A cavity of electron density, driven by an optimally designed multi-color stack of 10-TW-scale laser pulses, experiences expansions and contractions, periodically injecting electrons from the ambient dense plasma, accelerating them without compromising the beam quality. This periodic injection is naturally achieved in a plasma channel. The channel, however, is not a prerequisite to this effect. The number of comb components, as well as their charge and energy spacing, can be controlled in a uniform plasma by independently varying focal spots of the laser stack components. Inverse Thomson scattering from these comb-like beams produces synchronized sequences of quasi-monochromatic, fs-length gamma-ray flashes, which may become an asset to pump-probe experiments in dense plasmas. NSF Grant PHY-1535678.

  4. The nonparaxial property of chirped pulsed beam

    Institute of Scientific and Technical Information of China (English)

    Daquan Lu(陆大全); Wei Hu(胡巍); Yizhou Zheng(郑一周); Zhenjun Yang(杨振军)

    2003-01-01

    The nonparaxial property of the chirped pulsed beam is analyzed both quantitatively and qualitatively.Through the qualitative investigation of the paraxial approximation condition, we show there are chirpinduced changes in the nonparaxial propagation of the chirped pulsed beam. A quantitative nonparaxial correction was developed by use of the perturbational technic and the Fourier transform for a few-cycle chirped pulsed beam with relative small chirp parameter. It was shown that the nonparaxial corrections were enhanced near the leading or trailing edge of pulse depending on weather the chirp parameter is positive or negative. An example for pulsed Gaussian beam driven by a chirped Gaussian pulse is shown in the numerical result to confirm our analysis.

  5. Beam Stop for Electron Accelerator Beam Characterisation

    Science.gov (United States)

    Roach, Greg; Sharp, Vic; Tickner, James; Uher, Josef

    2009-08-01

    Electron linear accelerator applications involving the generation of hard X-rays frequently require accurate knowledge of the electron beam parameters. We developed a beam stop device which houses a tungsten Bremsstrahlung target and enables the electron beam current, energy and position to be monitored. The beam stop consisted of four plates. The first was a removable aluminium (Al) transmission plate. Then followed the tungsten target. Behind the target there were four Al quadrant plates for beam position measurement. The last plate was a thick Al back-stop block. Currents from the four quadrants and the back-stop were measured and the beam lateral position, energy and current were calculated. The beam stop device was optimised using Monte-Carlo simulation, manufactured (including custom-made electronics and software) in our laboratory and tested at the ARPANSA (Australian Radiation Protection and Nuclear Safety Agency) linear accelerator in Melbourne. The electron beam energy was determined with a precision of 60 keV at beam energies between 11 and 21 MeV and the lateral beam position was controlled with a precision of 200 mum. The relative changes of the beam current were monitored as well.

  6. Propagation of an ultra intense laser pulse in an under dense plasma: production of quasi monoenergetic electron beams and development of applications; Propagation d'une impulsion laser ultra-intense dans un plasma sous-dense: generation de faisceaux d'electrons quasi monoenergetiques et developpement d'applications

    Energy Technology Data Exchange (ETDEWEB)

    Glinec, Y

    2006-09-15

    This experimental study concerns the generation of electron beams with original properties. These electrons beams originate from the interaction of an ultra-intense and short laser pulse with a gas jet. Previously, these electron beams had a large divergence and a broad spectrum. A major improvement in this field was achieved when an electron beam with low divergence (10 mrad) and a peaked spectrum (170 MeV) was observed during this thesis, using a new single shot electron spectrometer. A parametric study of the interaction allowed to observe the evolution of the electron beam. Experiments have been carried out to deepen the characterization of the electron beam. The observation of transition radiation generated by the electrons at an interface shows that the electron beam interacts with the laser pulse during the acceleration. Radial oscillations of the electron beam around the laser axis, named betatron oscillations, were also observed on the electron spectra. Such a quasi-monoenergetic spectrum is essential for many applications. In order to justify the interest of this electron beam, several applications are presented: a sub-milli-metric gamma-ray radiography of dense objects, a dose profile of the electron beam comparable to present capabilities of photon sources for radiotherapy, a very short temporal profile useful for water radiolysis and the generation of a bright X-ray source with low divergence. (author)

  7. Isothermal oxidation behaviour of thermal barrier coatings with CoCrAlY bond coat irradiated by high-current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jie [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Guan, Qingfeng, E-mail: guanqf@mail.ujs.edu.cn [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Hou, Xiuli [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Zhiping; Su, Jingxin; Han, Zhiyong [College of Science, Civil Aviation University of China, Tianjin 300300 (China)

    2014-10-30

    Highlights: • The original coarse surface was re-melted by pulsed electron beam irradiation. • Very fine grains were homogeneously dispersed on the irradiated coat surface. • A compact Al{sub 2}O{sub 3} scale was formed in irradiated TBCs at the onset of oxidation. • The selective oxidation of Al element avoided the formation of other oxides. • The irradiated coating has a much higher oxidation resistance. - Abstract: Thermal sprayed CoCrAlY bond coat irradiated by high-current pulsed electron beam (HCPEB) and thermal barrier coatings (TBCs) prepared with the irradiated bond coat and the ceramic top coat were investigated. The high temperature oxidation resistance of these specimens was tested at 1050 °C in air. Microstructure observations revealed that the original coarse surface of the as-sprayed bond coat was significantly changed as the interconnected bulged nodules with a compact appearance after HCPEB irradiation. Abundant Y-rich alumina particulates and very fine grains were dispersed on the irradiated surface. After high temperature oxidation test, the thermally grown oxide (TGO) in the initial TBCs grew rapidly and was comprised of two distinct layers: a large percentage of mixed oxides in the outer layer and a relatively small portion of Al{sub 2}O{sub 3} in the inner layer. Severe local internal oxidation and extensive cracks in the TGO layer were discovered as well. Comparatively, the irradiated TBCs exhibited thinner TGO layer, slower TGO growth rate, and homogeneous TGO composition (primarily consisting of Al{sub 2}O{sub 3}). The results indicate that TBCs with the irradiated bond coat have a much higher oxidation resistance.

  8. Tesla-transformer-type electron beam accelerator

    CERN Document Server

    Liu Jin Liang; Tan Qi Mei; Li Chuan Lu; Zhang Jian

    2002-01-01

    An electron-beam Tesla-transformer accelerator is described. It consists of the primary storage energy system. Tesla transformer, oil Blumlein pulse form line, and the vacuum diode. The experiments of initial stage showed that diode voltage rises up to about 500 kV with an input of 20 kV and the maximum electron-beam current is about 9 kA, the pulse width is about 50 ns. This device can operate stably and be set up easily

  9. Mechanisms of hardening, wear and corrosion improvement of 316 L stainless steel by low energy high current pulsed electron beam surface treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zou, J.X. [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, UMR-CNRS 7078), Universite Paul Verlaine - Metz, Ile du Saulcy, 57045 Metz (France); Shanghai Engineering Research Center of Mg Materials and Applications and School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Key Laboratory of Materials Modification by Laser, Electron and Ion beams, Dalian University of Technology, Dalian 116024 (China); Zhang, K.M. [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Hao, S.Z.; Dong, C. [Key Laboratory of Materials Modification by Laser, Electron and Ion beams, Dalian University of Technology, Dalian 116024 (China); Grosdidier, T., E-mail: thierry.grosdidier@univ-metz.f [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, UMR-CNRS 7078), Universite Paul Verlaine - Metz, Ile du Saulcy, 57045 Metz (France); Key Laboratory of Materials Modification by Laser, Electron and Ion beams, Dalian University of Technology, Dalian 116024 (China)

    2010-12-01

    The mechanisms of corrosion and wear improvements by low energy high current pulsed electron beam (LEHCPEB) have been investigated for an AISI 316 L steel. Selective purification followed by epitaxial growth occurred in the top surface melted layer (2-3 {mu}m thick) that was softened by tensile stresses and, to a much lower extent, by lower efficiency of MnS precipitation hardening. Electrochemical impedance spectroscopy and potentiodynamic polarization analyses used to model the corrosion behavior revealed that, while craters initiated at MnS inclusions initially served as pitting sites, the resistance was increased by 3 orders of magnitude after sufficient number of pulses by the formation of a homogeneous covering layer. The wear resistance was effectively improved by sub-surface (over 100 {mu}m) work hardening associated with the combine effect of the quasi-static thermal stress and the thermal stress waves. The overall results demonstrate the potential of the LEHCPEB technique for improving concomitantly the corrosion and wear performances of metallic materials.

  10. Design Study for Pulsed Proton Beam Generation

    Directory of Open Access Journals (Sweden)

    Han-Sung Kim

    2016-02-01

    Full Text Available Fast neutrons with a broad energy spectrum, with which it is possible to evaluate nuclear data for various research fields such as medical applications and the development of fusion reactors, can be generated by irradiating proton beams on target materials such as beryllium. To generate short-pulse proton beam, we adopted a deflector and slit system. In a simple deflector with slit system, most of the proton beam is blocked by the slit, especially when the beam pulse width is short. Therefore, the available beam current is very low, which results in low neutron flux. In this study, we proposed beam modulation using a buncher cavity to increase the available beam current. The ideal field pattern for the buncher cavity is sawtooth. To make the field pattern similar to a sawtooth waveform, a multiharmonic buncher was adopted. The design process for the multiharmonic buncher includes a beam dynamics calculation and three-dimensional electromagnetic simulation. In addition to the system design for pulsed proton generation, a test bench with a microwave ion source is under preparation to test the performance of the system. The design study results concerning the pulsed proton beam generation and the test bench preparation with some preliminary test results are presented in this paper.

  11. High voltage pulse electron beam control strategy and influence on weld bead shape%高压脉冲电子束的控制及其对焊缝形貌影响

    Institute of Scientific and Technical Information of China (English)

    许海鹰; 余伟; 左从进

    2011-01-01

    研制出一台150 kV/30 kW高压脉冲电子束焊机,介绍了控制脉冲束流产生的偏压脉冲电源拓扑电路结构及脉冲束流频率、占空比、束流基值、束流峰值的调节控制技术.在0~1 kHz频率范围内,该电源可输出最大幅值200 mA的脉冲电子束束流,且工艺参数调节方便.分别采用脉冲束流与连续束流电子束工艺焊接了1Cr18Ni9Ti奥氏体不锈钢,对不同工艺的焊缝形貌进行了对比分析.与连续束流电子束焊接工艺相比,采用脉冲电子束焊接工艺的焊缝熔深增加,深宽比增大;对于脉冲电子束焊接工艺,占空比给定时,随着束流频率增加,焊接缺陷减少.试验结果表明:脉冲束流频率、占空比是影响焊缝成形的关键工艺参数;脉冲调制方式控制偏压是获得高压脉冲电子束的理想控制技术之一.%A 150 kV/30 kW high voltage pulse electron beam welding power source was developed.The bias pulse power source topology and control technique about base beam current,peak beam current,pulse beam duty,pulse beam frequency were introduced.Not only the biggest peak beam current up to 200 mA has been exported by this power source at 0-1 kHz,but also weld technology parameters are expediently adjusted.The 1Cr18Ni9Ti stainless steel work pieces had been welded by electron beam welding and pulse electron beam welding.These weld bead shapes had been studied and analyzed.In contrast with electron beam welding,weld penetration will be increased by pulse electron beam welding introduced.At the immovable pulse beam duty,the weld faults will be reduced with the pulse beam frequency being increased.Through these weld tests,besides beam frequency and duty are substantiated key technique parameters for weld shapes,it also shows that pulse modulated bias power source technique is an applicable technology to achieve high voltage pulse electron beam.

  12. Development of pulsed positron beam line with compact pulsing system

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Masaki, E-mail: maekawa.masaki@jaea.go.jp [Advanced Science Research Center, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Kawasuso, Atsuo [Advanced Science Research Center, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

    2012-01-01

    We have developed a pulsed slow positron beam with a pulse width of less than 200 ps and a period of 25 ns. The beam apparatus is composed of a Munich-type pre-buncher, a chopper and a buncher. Instead of the conventional RF cavity, a simple double-cylinder electrode is used for the buncher. The beam will be used for positron lifetime measurements. The time resolution of the whole system including lifetime measurement circuits is 250 ps, which is adequate for studying semiconductors and metals.

  13. Relativistic electron beams above thunderclouds

    DEFF Research Database (Denmark)

    Füellekrug, M.; Roussel-Dupre, R.; Symbalisty, E. M. D.;

    2011-01-01

    Non-luminous relativistic electron beams above thunderclouds have been detected by the radio signals of low frequency similar to 40-400 kHz which they radiate. The electron beams occur similar to 2-9 ms after positive cloud-to-ground lightning discharges at heights between similar to 22-72 km above...... thunderclouds. Intense positive lightning discharges can also cause sprites which occur either above or prior to the electron beam. One electron beam was detected without any luminous sprite which suggests that electron beams may also occur independently of sprites. Numerical simulations show that beams...... of electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of similar to 7MeV to transport a total charge of similar to-10mC upwards. The impulsive current similar to 3 x 10(-3) Am-2 associated with relativistic electron beams above thunderclouds...

  14. Relativistic electron beams above thunderclouds

    Directory of Open Access Journals (Sweden)

    M. Füllekrug

    2011-05-01

    Full Text Available Non-luminous relativistic electron beams above thunderclouds are detected by radio remote sensing with low frequency radio signals from 40–400 kHz. The electron beams occur 2–9 ms after positive cloud-to-ground lightning discharges at heights between 22–72 km above thunderclouds. The positive lightning discharges also cause sprites which occur either above or before the electron beam. One electron beam was detected without any luminous sprite occurrence which suggests that electron beams may also occur independently. Numerical simulations show that the beamed electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of 7 MeV to transport a total charge of 10 mC upwards. The impulsive current associated with relativistic electron beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit.

  15. Research on Brightness Measurement of Intense Electron Beam

    CERN Document Server

    Wang, Yuan; Zhang, Huang; Yang, GuoJun; Li, YiDing; Li, Jin

    2015-01-01

    The mostly research fasten on high emission density of injector to study electron beam's brightness in LIA. Using the injector(2MeV) was built to research brightness of multi-pulsed high current(KA) electron beam, and researchs three measurement method (the pepper-pot method, beam collimator without magnetic field, beam collimator with magnetic field method) to detect beam's brightness with time-resolved measurement system.

  16. Compact electron beam focusing column

    Energy Technology Data Exchange (ETDEWEB)

    Persaud, Arun; Leung, Ka-Ngo; Reijonen, Jani

    2001-07-13

    A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2-D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.

  17. One nanosecond pulsed electron gun systems

    Energy Technology Data Exchange (ETDEWEB)

    Koontz, R.F.

    1979-02-01

    At SLAC there has been a continuous need for the injection of very short bunches of electrons into the accelerator. Several time-of-flight experiments have used bursts of short pulses during a normal 1.6 micro-second rf acceleration period. Single bunch beam loading experiments made use of a short pulse injection system which included high power transverse beam chopping equipment. Until the equipment described in this paper came on line, the basic grid-controlled gun pulse was limited to a rise time of 7 nanoseconds and a pulse width of 10 nanoseconds. The system described here has a grid-controlled rise time of less than 500 pico-seconds, and a minimum pulse width of less than 1 nanosecond. Pulse burst repetition rate has been demonstrated above 20 MHz during a 1.6 microsecond rf accelerating period. The order-of-magnitude increase in gun grid switching speed comes from a new gun design which minimizes lead inductance and stray capacitance, and also increases gun grid transconductance. These gun improvements coupled with a newly designed fast pulser mounted directly within the gun envelope make possible subnanosecond pulsing of the gun.

  18. Intense Pulsed Heavy Ion Beam Technology

    Science.gov (United States)

    Masugata, Katsumi; Ito, Hiroaki

    Development of intense pulsed heavy ion beam accelerator technology is described for the application of materials processing. Gas puff plasma gun and vacuum arc discharge plasma gun were developed as an active ion source for magnetically insulated pulsed ion diode. Source plasma of nitrogen and aluminum were successfully produced with the gas puff plasma gun and the vacuum arc plasma gun, respectively. The ion diode was successfully operated with gas puff plasma gun at diode voltage 190 kV, diode current 2.2 kA and nitrogen ion beam of ion current density 27 A/cm2 was obtained. The ion composition was evaluated by a Thomson parabola spectrometer and the purity of the nitrogen ion beam was estimated to be 86%. The diode also operated with aluminum ion source of vacuum arc plasma gun. The ion diode was operated at 200 kV, 12 kA, and aluminum ion beam of current density 230 A/cm2 was obtained. The beam consists of aluminum ions (Al(1-3)+) of energy 60-400 keV, and protons (90-130 keV), and the purity was estimated to be 89 %. The development of the bipolar pulse accelerator (BPA) was reported. A double coaxial type bipolar pulse generator was developed as the power supply of the BPA. The generator was tested with dummy load of 7.5 ohm, bipolar pulses of -138 kV, 72 ns (1st pulse) and +130 kV, 70 ns (2nd pulse) were succesively generated. By applying the bipolar pulse to the drift tube of the BPA, nitrogen ion beam of 2 A/cm2 was observed in the cathode, which suggests the bipolar pulse acceleration.

  19. Double carriers pulse DLTS for the characterization of electron-hole recombination process in GaAsN grown by chemical beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Bouzazi, Boussairi, E-mail: sd08503@toyota-ti.ac.j [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan); Suzuki, Hidetoshi; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

    2011-03-01

    A nitrogen-related electron trap (E1), located approximately 0.33 eV from the conduction band minimum of GaAsN grown by chemical beam epitaxy, was confirmed by investigating the dependence of its density with N concentration. This level exhibits a high capture cross section compared with that of native defects in GaAs. Its density increases significantly with N concentration, persists following post-thermal annealing, and was found to be quasi-uniformly distributed. These results indicate that E1 is a stable defect that is formed during growth to compensate for the tensile strain caused by N. Furthermore, E1 was confirmed to act as a recombination center by comparing its activation energy with that of the recombination current in the depletion region of the alloy. However, this technique cannot characterize the electron-hole (e-h) recombination process. For that, double carrier pulse deep level transient spectroscopy is used to confirm the non-radiative e-h recombination process through E1, to estimate the capture cross section of holes, and to evaluate the energy of multi-phonon emission. Furthermore, a configuration coordinate diagram is modeled based on the physical parameters of E1. -- Research Highlights: {yields} Double carrier pulse DLTS method confirms the existence of SRH center. {yields} The recombination center in GaAsN depends on nitrogen concentration. {yields} Minority carrier lifetime in GaAsN is less than 1 ns. {yields} A non-radiative recombination center exits in GaAsN.

  20. Electron beam silicon purification

    Energy Technology Data Exchange (ETDEWEB)

    Kravtsov, Anatoly [SIA ' ' KEPP EU' ' , Riga (Latvia); Kravtsov, Alexey [' ' KEPP-service' ' Ltd., Moscow (Russian Federation)

    2014-11-15

    Purification of heavily doped electronic grade silicon by evaporation of N-type impurities with electron beam heating was investigated in process with a batch weight up to 50 kilos. Effective temperature of the melt, an indicative parameter suitable for purification process characterization was calculated and appeared to be stable for different load weight processes. Purified material was successfully approbated in standard CZ processes of three different companies. Each company used its standard process and obtained CZ monocrystals applicable for photovoltaic application. These facts enable process to be successfully scaled up to commercial volumes (150-300 kg) and yield solar grade silicon. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Free Electron Lasers using `Beam by Design'

    CERN Document Server

    Henderson, J R; McNeil, B W J

    2015-01-01

    Several methods have been proposed in the literature to improve Free Electron Laser output by transforming the electron phase-space before entering the FEL interaction region. By utilising `beam by design' with novel undulators and other beam changing elements, the operating capability of FELs may be further usefully extended. This paper introduces two new such methods to improve output from electron pulses with large energy spreads and the results of simulations of these methods in the 1D limit are presented. Both methods predict orders of magnitude improvements to output radiation powers.

  2. Double carriers pulse DLTS for the characterization of electron-hole recombination process in GaAsN grown by chemical beam epitaxy

    Science.gov (United States)

    Bouzazi, Boussairi; Suzuki, Hidetoshi; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi

    2011-03-01

    A nitrogen-related electron trap (E1), located approximately 0.33 eV from the conduction band minimum of GaAsN grown by chemical beam epitaxy, was confirmed by investigating the dependence of its density with N concentration. This level exhibits a high capture cross section compared with that of native defects in GaAs. Its density increases significantly with N concentration, persists following post-thermal annealing, and was found to be quasi-uniformly distributed. These results indicate that E1 is a stable defect that is formed during growth to compensate for the tensile strain caused by N. Furthermore, E1 was confirmed to act as a recombination center by comparing its activation energy with that of the recombination current in the depletion region of the alloy. However, this technique cannot characterize the electron-hole (e-h) recombination process. For that, double carrier pulse deep level transient spectroscopy is used to confirm the non-radiative e -h recombination process through E1, to estimate the capture cross section of holes, and to evaluate the energy of multi-phonon emission. Furthermore, a configuration coordinate diagram is modeled based on the physical parameters of E1.

  3. DARHT-II Long-Pulse Beam-Dynamics Experiments

    CERN Document Server

    Ekdahl, Carl; Bartsch, Richard; Bender, Howard; Briggs, Richard J; Broste, William; Carlson, Carl; Caudill, Larry; Chan, Kwok-Chi D; Chen Yu Jiuan; Dalmas, Dale; Durtschi, Grant; Eversole, Steven; Eylon, Shmuel; Fawley, William M; Frayer, Daniel; Gallegos, Robert J; Harrison, James; Henestroza, Enrique; Holzscheiter, M H; Houck, Timothy L; Hughes, Thomas P; Jacquez, Edward; Johnson, Douglas; Johnson, Jeffrey; Jones, Kenneth; McCuistian, Brian T; Meidinger, Alfred; Montoya, Nicholas; Mostrom, Chris; Moy, Kenneth; Nath, Subrata; Nielsen, Kurt; Oro, David; Rodriguez, Leroy; Rodriguez, Patrick; Rowton, Larry J; Sanchez, Manolito; Scarpetti, Raymond; Schauer, Martin; Schulze, Martin E; Simmons, David; Studebaker, Jan; Sturgess, Ronald; Sullivan, Gary; Swinney, Charles; Tang, Yan; Temple, Rodney; Tipton, Angela; Tom, C Y; Vernon Smith, H; Yu, Simon

    2005-01-01

    When completed, the DARHT-II linear induction accelerator (LIA) will produce a 2-kA, 18-MeV electron beam with more than 1500-ns current/energy "flat-top." In initial tests DARHT-II has already accelerated beams with current pulse lengths from 500-ns to 1200-ns full-width at half maximum (FWHM) with more than1.2-kA, 12.5-MeV peak current and energy. Experiments are now underway with a ~2000-ns pulse length, but reduced current and energy. These pulse lengths are all significantly longer than any other multi-MeV LIA, and they define a novel regime for high-current beam dynamics, especially with regard to beam stability. Although the initial tests demonstrated absence of BBU, the pulse lengths were too short to test the predicted protection against ion-hose instability. The present experiments are designed to resolve these and other beam-dynamics issues with a ~2000-ns pulse length beam.

  4. Self accelerating electron Airy beams

    CERN Document Server

    Voloch-Bloch, Noa; Lilach, Yigal; Gover, Avraham; Arie, Ady

    2013-01-01

    We report the first experimental generation and observation of Airy beams of free electrons. The electron Airy beams are generated by diffraction of electrons through a nanoscale hologram, that imprints a cubic phase modulation on the beams' transverse plane. We observed the spatial evolution dynamics of an arc-shaped, self accelerating and shape preserving electron Airy beams. We directly observed the ability of electrons to self-heal, restoring their original shape after passing an obstacle. This electromagnetic method opens up new avenues for steering electrons, like their photonic counterparts, since their wave packets can be imprinted with arbitrary shapes or trajectories. Furthermore, these beams can be easily manipulated using magnetic or electric potentials. It is also possible to efficiently self mix narrow beams having opposite signs of acceleration, hence obtaining a new type of electron interferometer.

  5. Electron beam machining using rotating and shaped beam power distribution

    Science.gov (United States)

    Elmer, John W.; O'Brien, Dennis W.

    1996-01-01

    An apparatus and method for electron beam (EB) machining (drilling, cutting and welding) that uses conventional EB guns, power supplies, and welding machine technology without the need for fast bias pulsing technology. The invention involves a magnetic lensing (EB optics) system and electronic controls to: 1) concurrently bend, focus, shape, scan, and rotate the beam to protect the EB gun and to create a desired effective power-density distribution, and 2) rotate or scan this shaped beam in a controlled way. The shaped beam power-density distribution can be measured using a tomographic imaging system. For example, the EB apparatus of this invention has the ability to drill holes in metal having a diameter up to 1000 .mu.m (1 mm or larger), compared to the 250 .mu.m diameter of laser drilling.

  6. Electron Beam Simulations on the SCSS Accelerator

    CERN Document Server

    Hara, Toru; Shintake, Tsumoru

    2004-01-01

    The SPring-8 Compact SASE Source (SCSS) is a SASE-FEL project aiming at soft X-ray radiation at its first stage using 1 GeV electron beams. One of the unique features of the SCSS is the use of a pulsed high-voltage electron gun with a thermionic cathode. Main reason for this choice is its high stability and the well developed technology relating to the gun. Meanwhile, the electron bunch should be compressed properly at the injector in order to obtain sufficient peak currents. In this presentation, the results of the electron beam simulations along the accelerator and the expected parameters of the electron beam will be given.

  7. Study of performance of electronic dosemeters in continuous and pulsed X-radiation beams; Estudo de desempenho de dosimetros eletronicos em feixes de raios-X continuos e pulsados

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, Margarete Cristina

    2014-07-01

    Personal radiation monitoring is a basic procedure to verify the compliance to regulatory requirements for radiological protection. Electronic personal dosimeters (EPD) based on solid state detectors have largely been used for personnel monitoring; including for pulsed radiation beams where their responses are not well known and deficiencies have been reported. In this work, irradiation conditions for testing the response of EPDs in both continuous and pulsed X-ray beams were studied to be established in a constant potential Seifert-Pantak and in a medical Pulsar 800 Plus VMI X-ray machines. Characterization of X-ray beams was done in terms of tube voltage, half-value layer, mean energy and air kerma rate. A Xi R/F Unfors solid state dosimeter used as reference for air kerma measurements was verified against a RC-6 and 10X6-6 Radical ionization chambers as far its metrological coherence. Rad-60 RADOS, PDM- 11 Aloka and EPD MK2 Thermo electron EPDs were selected to be tested in terms of relative intrinsic error and energy response in similar to IEC RQR, IEC RQA and ISO N reference radiations. Results demonstrated the reliability of the solid state Xi R/F Unfors dosimeter to be as reference dosimeter although its response was affected by heavily filtered beams. Results also showed that relative intrinsic errors in the response of the EPDs in terms of personal dose equivalent, Hp(10), were higher than the requirement established for continuous beams. In pulsed beams, some EPDs showed inadequate response and high relative intrinsic errors. This work stressed the need of performing additional checks for EPDs, besides the limited {sup 137}Cs beam calibration, before using them in pulsed X-ray beams. (author)

  8. Intense electron and ion beams

    CERN Document Server

    Molokovsky, Sergey Ivanovich

    2005-01-01

    Intense Ion and Electron Beams treats intense charged-particle beams used in vacuum tubes, particle beam technology and experimental installations such as free electron lasers and accelerators. It addresses, among other things, the physics and basic theory of intense charged-particle beams; computation and design of charged-particle guns and focusing systems; multiple-beam charged-particle systems; and experimental methods for investigating intense particle beams. The coverage is carefully balanced between the physics of intense charged-particle beams and the design of optical systems for their formation and focusing. It can be recommended to all scientists studying or applying vacuum electronics and charged-particle beam technology, including students, engineers and researchers.

  9. Thermal Cycling Behavior of Thermal Barrier Coatings with MCrAlY Bond Coat Irradiated by High-Current Pulsed Electron Beam.

    Science.gov (United States)

    Cai, Jie; Lv, Peng; Guan, Qingfeng; Xu, Xiaojing; Lu, Jinzhong; Wang, Zhiping; Han, Zhiyong

    2016-11-30

    Microstructural modifications of a thermally sprayed MCrAlY bond coat subjected to high-current pulsed electron beam (HCPEB) and their relationships with thermal cycling behavior of thermal barrier coatings (TBCs) were investigated. Microstructural observations revealed that the rough surface of air plasma spraying (APS) samples was significantly remelted and replaced by many interconnected bulged nodules after HCPEB irradiation. Meanwhile, the parallel columnar grains with growth direction perpendicular to the coating surface were observed inside these bulged nodules. Substantial Y-rich Al2O3 bubbles and varieties of nanocrystallines were distributed evenly on the top of the modified layer. A physical model was proposed to describe the evaporation-condensation mechanism taking place at the irradiated surface for generating such surface morphologies. The results of thermal cycling test showed that HCPEB-TBCs presented higher thermal cycling resistance, the spalling area of which after 200 cycles accounted for only 1% of its total area, while it was about 34% for APS-TBCs. The resulting failure mode, i.e., in particular, a mixed delamination crack path, was shown and discussed. The irradiated effects including compact remelted surface, abundant nanoparticles, refined columnar grains, Y-rich alumina bubbles, and deformation structures contributed to the formation of a stable, continuous, slow-growing, and uniform thermally grown oxide with strong adherent ability. It appeared to be responsible for releasing stress and changing the cracking paths, and ultimately greatly improving the thermal cycling behavior of HCPEB-TBCs.

  10. Focusing Electron Beams at SLAC.

    Science.gov (United States)

    Taylor, Richard L.

    1993-01-01

    Describes the development of a set of magnets that focus high-energy electron and positron beams causing them to collide, annihilate each other, and generate new particles. Explains how dipoles bend the beam, how quadrupoles focus the beam, how the focal length is calculated, and the superconducting final focus. (MDH)

  11. A high current, high gradient, laser excited, pulsed electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Batchelor, K.; Farrell, J.P.; Dudnikova, G. [Brookhaven Technology Group, Inc., Stony Brook, NY (United States); Ben-Zvi, I.; Srinivasan-Rao, T.; Smedley, J.; Yakimenko, V. [Brookhaven National Lab., Upton, NY (United States)

    1998-06-01

    This paper describes a pulsed electron gun that can be used as an FEL, as an injector for electron linear accelerators or for rf power generation. It comprises a 1 to 5 MeV, 1 to 2 ns pulsed power supply feeding a single diode, photoexcited acceleration gap. Beam quality of a {approximately}1nC charge in {approximately}1 GV/m field was studied. Computations of the beam parameters as a function of electrode configuration and peak electron current are presented together with descriptions of the power supply, laser and beam diagnostics systems.

  12. Propagation of ultrashort pulsed beams in dispersive media

    Institute of Scientific and Technical Information of China (English)

    刘志军; 吕百达

    2003-01-01

    Starting from the Rayleigh diffraction integral, the propagation equation of ultrashort pulsed beams in dispersive media is derived without making the paraxial approximation and slowly varying envelope approximation (SVEA). The spatiotemporal properties of ultrashort pulsed beams in dispersive media, such as spectrum redshifting, narrowing and pulse distortion are illustrated with pulsed Gaussian beams. It is stressed that the "antibeam" behaviour of ultrashort pulsed beams can be avoided, if a suitable truncation function is chosen.

  13. Multiple-beam pulse shaping and preamplification

    Energy Technology Data Exchange (ETDEWEB)

    Wilcox, R.B.; VanWonterghem, B.W.; Burkhart, S.C.; Davin, J.M.

    1994-11-09

    Glass fusion laser systems typically use a master oscillator-power amplifier (MOPA) architecture, where control of the optical pulse temporal and spatial parameters is accomplished mainly in the master oscillator and low power optics. The pulses from this low power ``front end`` are amplified in the power amplifier, which modifies the pulse shape temporally and spatially. Nonlinear frequency conversion crystals following the amplifier further change the pulse before it reaches the target. To effectively control the optical pulse on target for different types of experiments, and compensate for nonlinearity in the preceding optics, the front end system must be versatile enough to easily control many pulse parameters over a large range. The front end pulse generation system described in this article represents a new approach to this problem. The proposed National Ignition Facility (NIF) has 192 beamlines, each of which requires an input pulse of up to 12 Joules in around 4 ns equivalent square pulse length. Considerations of laser architecture for supplying each of these beamlines from a central oscillator system were crucial in the design of the front end. Previous lasers have used bulk optics to split a single oscillator signal and report beams to multiple amplifier chains. A key idea in the current design is to replace bulk optic transport with fibers, eliminating large opto-mechanical subsystems. Another important concept is convenient pulse forming using low voltage integrated optic modulators. The integrated optic and fiber optic concepts resulted in the current pulse generation designs for NEF. An important advantage is that each of the beamlines can have an independently controlled temporal pulse shape, which provides for precise balance of instantaneous power on target.

  14. High-Power Microwave Switch Employing Electron Beam Triggering

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L

    2012-09-19

    A high-power active microwave pulse compressor is described that modulates the quality factor Q of the energy storage cavity by a new means involving mode conversion controlled by a triggered electron-beam discharge through a switch cavity. The electron beam is emitted from a diamond-coated molybdenum cathode. This report describes the principle of operation, the design of the switch, the configuration used for the test, and the experimental results. The pulse compressor produced output pulses with 140 - 165 MW peak power, power gain of 16 - 20, and pulse duration of 16 - 20 ns at a frequency of 11.43 GHz.

  15. Relativistic electron beams above thunderclouds

    Directory of Open Access Journals (Sweden)

    M. Füllekrug

    2011-08-01

    Full Text Available Non-luminous relativistic electron beams above thunderclouds have been detected by the radio signals of low frequency ∼40–400 kHz which they radiate. The electron beams occur ∼2–9 ms after positive cloud-to-ground lightning discharges at heights between ∼22–72 km above thunderclouds. Intense positive lightning discharges can also cause sprites which occur either above or prior to the electron beam. One electron beam was detected without any luminous sprite which suggests that electron beams may also occur independently of sprites. Numerical simulations show that beams of electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of ∼7 MeV to transport a total charge of ∼−10 mC upwards. The impulsive current ∼3 × 10−3 Am−2 associated with relativistic electron beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit.

  16. Generation of electron Airy beams.

    Science.gov (United States)

    Voloch-Bloch, Noa; Lereah, Yossi; Lilach, Yigal; Gover, Avraham; Arie, Ady

    2013-02-21

    Within the framework of quantum mechanics, a unique particle wave packet exists in the form of the Airy function. Its counterintuitive properties are revealed as it propagates in time or space: the quantum probability wave packet preserves its shape despite dispersion or diffraction and propagates along a parabolic caustic trajectory, even though no force is applied. This does not contradict Newton's laws of motion, because the wave packet centroid propagates along a straight line. Nearly 30 years later, this wave packet, known as an accelerating Airy beam, was realized in the optical domain; later it was generalized to an orthogonal and complete family of beams that propagate along parabolic trajectories, as well as to beams that propagate along arbitrary convex trajectories. Here we report the experimental generation and observation of the Airy beams of free electrons. These electron Airy beams were generated by diffraction of electrons through a nanoscale hologram, which imprinted on the electrons' wavefunction a cubic phase modulation in the transverse plane. The highest-intensity lobes of the generated beams indeed followed parabolic trajectories. We directly observed a non-spreading electron wavefunction that self-heals, restoring its original shape after passing an obstacle. This holographic generation of electron Airy beams opens up new avenues for steering electronic wave packets like their photonic counterparts, because the wave packets can be imprinted with arbitrary shapes or trajectories.

  17. Special Technologies Related to Electron Beam Welding

    Institute of Scientific and Technical Information of China (English)

    Zhao; Haiyan; Cai; Zhipeng; Wang; Xichang

    2007-01-01

    In order to improve the manufacturing quality of electron beam welding,some technologies are developed by using the special features of electron beam.Comparing with the conventional electron beam welding,the usage of multi-beam technology and micro-beam technology are introduced.In addition.the development of beam diagnostic system is also presented.

  18. Applications of electron lenses: scraping of high-power beams, beam-beam compensation, and nonlinear optics

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio

    2014-09-11

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles. At Fermilab, we are planning to install an electron lens in the Integrable Optics Test Accelerator (IOTA, a 40-m ring for 150-MeV electrons) as one of the proof-of-principle implementations of nonlinear integrable optics to achieve large tune spreads and more stable beams without loss of dynamic aperture.

  19. Grid-controlled extraction of pulsed ion beams

    Science.gov (United States)

    Humphries, S., Jr.; Burkhart, C.; Coffey, S.; Cooper, G.; Len, L. K.; Savage, M.; Woodall, D. M.; Rutkowski, H.; Oona, H.; Shurter, R.

    1986-03-01

    Experimental results are presented on a method for extracting well-focused ion beams from plasma sources with time-varying properties. An electrostatic grid was used to stop the flow of plasma electrons so that only ions entered the extraction gap. In this case, ion flow in the gap was controlled by space-charge effects as it would be with a thermionic ion source. Constant extracted current was observed even with large variations of source flux. An insulator spark source and a metal-vapor vacuum arc were used to generate pulsed ion beams. With a hydrocarbon spark, current densities of 44 mA/cm2 were achieved at 20-kV extractor voltage for an 8-μs pulse. With an aluminum-vapor arc, a current density of 15 mA/cm2 (0.3 A total) was measured for a 50-μs pulse.

  20. Grid-controlled extraction of pulsed ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Humphries, S. Jr.; Burkhart, C.; Coffey, S.; Cooper, G.; Len, L.K.; Savage, M.; Woodall, D.M.; Rutkowski, H.; Oona, H.; Shurter, R.

    1986-03-15

    Experimental results are presented on a method for extracting well-focused ion beams from plasma sources with time-varying properties. An electrostatic grid was used to stop the flow of plasma electrons so that only ions entered the extraction gap. In this case, ion flow in the gap was controlled by space-charge effects as it would be with a thermionic ion source. Constant extracted current was observed even with large variations of source flux. An insulator spark source and a metal-vapor vacuum arc were used to generate pulsed ion beams. With a hydrocarbon spark, current densities of 44 mA/cm/sup 2/ were achieved at 20-kV extractor voltage for an 8-..mu..s pulse. With an aluminum-vapor arc, a current density of 15 mA/cm/sup 2/ (0.3 A total) was measured for a 50-..mu..s pulse.

  1. All-optical three-dimensional electron pulse compression

    CERN Document Server

    Wong, Liang Jie; Rohwer, Timm; Gedik, Nuh; Johnson, Steven G

    2014-01-01

    We propose an all-optical, three-dimensional electron pulse compression scheme in which Hermite-Gaussian optical modes are used to fashion a three-dimensional optical trap in the electron pulse's rest frame. We show that the correct choices of optical incidence angles are necessary for optimal compression. We obtain analytical expressions for the net impulse imparted by Hermite-Gaussian free-space modes of arbitrary order. Although we focus on electrons, our theory applies to any charged particle and any particle with non-zero polarizability in the Rayleigh regime. We verify our theory numerically using exact solutions to Maxwell's equations for first-order Hermite-Gaussian beams, demonstrating single-electron pulse compression factors of $>10^{2}$ in both longitudinal and transverse dimensions with experimentally realizable optical pulses. The proposed scheme is useful in ultrafast electron imaging for both single- and multi-electron pulse compression, and as a means of circumventing temporal distortions in ...

  2. Simulating Transient Effects of Pulsed Beams on Beam Intercepting Devices

    CERN Document Server

    Richter, Herta; Noah Messomo, Etam

    2011-01-01

    The development in the physics community towards higher beam power through the possibilities of particle accelerators lead to challenges for the developers of elements which are exposed to effect of particle beams (beam intercepting devices = BIDs). For the design of BIDs, the increasing heat load onto these devices due to energetic and focused beams and - in most cases - their highly pulsed nature has to be taken into account. The physics requirements are sometimes opposed to the current state of the art. As one possibility of many in combining the different aspects for these ambitious demands, two highly developed computer programs, namely FLUKA and ANSYS AUTODYN, were joined for this dissertation. The former is a widely enhanced Monte-Carlo-code which specializes on the interaction of particles with static matter, while the latter is a versatile explicit code for the simulation of highly dynamic processes. Both computer programs were developed intensively over years and are still continuously enhanced in o...

  3. Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core

    Energy Technology Data Exchange (ETDEWEB)

    Fitterer, M. [Fermilab; Stancari, G. [Fermilab; Valishev, A. [Fermilab; Bruce, R. [CERN; Papotti, G [CERN; Redaelli, S. [CERN; Valentino, G. [Malta U.; Valentino, G. [CERN; Valuch, D. [CERN; Xu, C. [CERN

    2017-06-13

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.

  4. Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core

    CERN Document Server

    Fitterer, M; Valishev, A; Bruce, R; Papotti, G; Redaelli, S; Valentino, G; Valentino, G; Valuch, D; Xu, C

    2017-01-01

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.

  5. Ion beam pulse radiolysis system at HIMAC

    Energy Technology Data Exchange (ETDEWEB)

    Chitose, N.; Katsumura, Y.; Domae, M.; Ishigure, K. [Tokyo Univ. (Japan); Murakami, T.

    1997-03-01

    An ion beam pulse radiolysis system has been constructed at HIMAC facility. Ion beam of 24MeV He{sup 2+} with the duration longer than 1 {mu}s is available for irradiation. Three kinds of aqueous solutions, (C{sub 6}H{sub 5}){sub 2}CO, NaHCO{sub 3}, and KSCN, were irradiated and the absorption signals corresponding to (C{sub 6}H{sub 5}){sub 2}CO{sup -}, CO{sub 3}{sup -}, and (SCN){sub 2}{sup -} respectively were observed. Ghost signals which interfere with the measurement are also discussed. (author)

  6. Measurement of Ampère-class pulsed electron beams via field emission from carbon-nanotube cathodes in a radiofrequency gun

    Science.gov (United States)

    Mihalcea, D.; Faillace, L.; Hartzell, J.; Panuganti, H.; Boucher, S.; Murokh, A.; Piot, P.; Thangaraj, J. C. T.

    2015-07-01

    Pulsed field emission from cold carbon-nanotube cathodes placed in a radiofrequency resonant cavity was directly measured. The cathodes were located on the backplate of a conventional 1 + /1 2 -cell resonant cavity operating at 1.3-GHz and resulted in the production of bunch train with maximum average current close to 0.7 Ampère. The measured Fowler-Nordheim characteristic, transverse emittance, and pulse duration are presented and, when possible, compared to numerical simulations. The implications of our results to the promise of high-average-current electron sources are briefly discussed.

  7. Pulsed beams as field probes for precision measurement

    OpenAIRE

    Hudson, J. J.; Ashworth, H. T.; Kara, D. M.; Tarbutt, M. R.; Sauer, B.E.; Hinds, E. A.

    2007-01-01

    We describe a technique for mapping the spatial variation of static electric, static magnetic, and rf magnetic fields using a pulsed atomic or molecular beam. The method is demonstrated using a beam designed to measure the electric dipole moment of the electron. We present maps of the interaction region, showing sensitivity to (i) electric field variation of 1.5 V/cm at 3.3 kV/cm with a spatial resolution of 15 mm; (ii) magnetic field variation of 5 nT with 25 mm resolution; (iii) radio-frequ...

  8. Formation of the active medium in high-power repetitively pulsed gas lasers pumped by an electron-beam-controlled discharge

    Science.gov (United States)

    Bulaev, V. D.; Lysenko, S. L.

    2015-07-01

    A high-power repetitively pulsed e-beam-controlled discharge CO2 laser is simulated numerically; the simulation results are compared with experimental data. Optimal sizes and design of electrodes and configuration of the external magnetic field are found, which allow one to introduce no less than 90% electric pump energy into a specified volume of the active medium, including the active volume of a laser with an aperture of 110 × 110 cm. The results obtained can also be used to design other types of highpower gas lasers.

  9. Electron beam pumped semiconductor laser

    Science.gov (United States)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2009-01-01

    Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

  10. Low voltage electron beam accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Masafumi [Iwasaki Electric Co., Ltd., Tokyo (Japan)

    2003-02-01

    Widely used electron accelerators in industries are the electron beams with acceleration voltage at 300 kV or less. The typical examples are shown on manufactures in Japan, equipment configuration, operation, determination of process parameters, and basic maintenance requirement of the electron beam processors. New electron beam processors with acceleration voltage around 100 kV were introduced maintaining the relatively high dose speed capability of around 10,000 kGy x mpm at production by ESI (Energy Science Inc. USA, Iwasaki Electric Group). The application field like printing and coating for packaging requires treating thickness of 30 micron or less. It does not require high voltage over 110 kV. Also recently developed is a miniature bulb type electron beam tube with energy less than 60 kV. The new application area for this new electron beam tube is being searched. The drive force of this technology to spread in the industries would be further development of new application, process and market as well as the price reduction of the equipment, upon which further acknowledgement and acceptance of the technology to societies and industries would entirely depend. (Y. Tanaka)

  11. Transverse electron beam diagnostics at REGAE

    Energy Technology Data Exchange (ETDEWEB)

    Bayesteh, Shima

    2014-12-15

    The use of high-intensity electron and X-ray pulsed sources allows for the direct observation of atomic motions as they occur. While the production of such high coherent, brilliant, short X-ray pulses requires large-scale and costly accelerator facilities, it is feasible to employ a high-intensity source of electrons by exploiting a more compact design. The Relativistic Electron Gun for Atomic Exploration (REGAE) facility is a small linear accelerator at DESY, Hamburg, equipped with a photocathode radio frequency (RF) gun that produces relativistic ultra-short (<100 fs), low charge (<1 pC) electron bunches of high coherence. By means of time-resolved diffraction experiments, such an electron source can probe ultrafast laser-induced atomic structural changes that occur with a temporal resolution of ∝100 fs. A comprehensive characterization of the electron beam, for every pulse, is of fundamental importance to study the atomic motions with the desired resolution and quality. This thesis reports on the transversal diagnostics of the electron beam with an emphasis on a scintillator-based beam profile monitor. The diagnostics is capable of evaluating the beam parameters such as charge, energy, energy spread and transverse profile, at very low charges and on a shot-to-shot basis. A full characterization of the scintillator's emission, the optical setup and the detector (camera) of the profile monitor is presented, from which an absolute charge calibration of the system is derived. The profile monitor is specially developed to accommodate more applications, such as dark current suppression, overlapping the electron probe and the laser pump within 1 ns accuracy, as well as charge and transverse emittance measurements. For the determination of the transverse emittance two techniques were applied. The first one introduces a new method that exploits a diffraction pattern to measure the emittance, while the second one is based on a version of the Pepper-pot technique. A

  12. Applications of electron lenses: scraping of high-power beams, beam-beam compensation, and nonlinear optics

    CERN Document Server

    Stancari, Giulio

    2014-01-01

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compens...

  13. Vortex stabilized electron beam compressed fusion grade plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hershcovitch, Ady [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-03-19

    Most inertial confinement fusion schemes are comprised of highly compressed dense plasmas. Those schemes involve short, extremely high power, short pulses of beams (lasers, particles) applied to lower density plasmas or solid pellets. An alternative approach could be to shoot an intense electron beam through very dense, atmospheric pressure, vortex stabilized plasma.

  14. Generation of subnanosecond electron beams in air at atmospheric pressure

    Science.gov (United States)

    Kostyrya, I. D.; Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Lomaev, M. I.; Rybka, D. V.

    2009-11-01

    Optimum conditions for the generation of runaway electron beams with maximum current amplitudes and densities in nanosecond pulsed discharges in air at atmospheric pressure are determined. A supershort avalanche electron beam (SAEB) with a current amplitude of ˜30 A, a current density of ˜20 A/cm2, and a pulse full width at half maximum (FWHM) of ˜100 ps has been observed behind the output foil of an air-filled diode. It is shown that the position of the SAEB current maximum relative to the voltage pulse front exhibits a time shift that varies when the small-size collector is moved over the foil surface.

  15. Electron beam ion source and electron beam ion trap (invited).

    Science.gov (United States)

    Becker, Reinard; Kester, Oliver

    2010-02-01

    The electron beam ion source (EBIS) and its trap variant [electron beam ion trap (EBIT)] celebrated their 40th and 20th anniversary, respectively, at the EBIS/T Symposium 2007 in Heidelberg. These technologically challenging sources of highly charged ions have seen a broad development in many countries over the last decades. In contrast to most other ion sources the recipe of improvement was not "sorcery" but a clear understanding of the physical laws and obeying the technological constraints. This review will report important achievements of the past as well as promising developments in the future.

  16. Electron beam ion source and electron beam ion trap (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Reinard [Scientific Software Service, Kapellenweg 2a, D-63571 Gelnhausen (Germany); Kester, Oliver [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States)

    2010-02-15

    The electron beam ion source (EBIS) and its trap variant [electron beam ion trap (EBIT)] celebrated their 40th and 20th anniversary, respectively, at the EBIS/T Symposium 2007 in Heidelberg. These technologically challenging sources of highly charged ions have seen a broad development in many countries over the last decades. In contrast to most other ion sources the recipe of improvement was not ''sorcery'' but a clear understanding of the physical laws and obeying the technological constraints. This review will report important achievements of the past as well as promising developments in the future.

  17. Electron Beam Materials Irradiators

    Science.gov (United States)

    Cleland, Marshall R.

    2012-06-01

    Radiation processing is a well established method for enhancing the properties of materials and commercial products by treating them with ionizing energy in the form of high-energy electrons, X-rays, and gamma rays. Beneficial effects include polymerizing, cross-linking, grafting and degrading plastics, sterilizing single-use medical devices, disinfecting and disinfesting fresh foods, purifying drinking water, treating wastewater and other toxic waste materials that harm the environment, and many other applications that are still being evaluated. Industrial electron accelerators of several types have been developed and are being used for these applications. More than 1800 electron accelerators are presently installed in facilities worldwide for these purposes.

  18. Dielectric charging by an electron beam

    Science.gov (United States)

    Upatov, V. Y.

    1996-08-01

    Experimental discovery of a charge spot field effect (CSFE) has altered considerably our understanding of dielectric charging by an electron beam, under conditions typical for the operation of a large class of cathode ray tubes (CRT). Dielectric charging by an electron beam was studied using a specific pulse method for the measurement of the potential. The accuracy of this method is discussed. Measurements were made of the potential relief of a positively charged spot on muscovite mica (quartz, aluminum oxide). The potential at the spot center, under conditions described in the paper and at a relatively long charging time, was shown to be considerably lower than that of the collector. Potential dependence on charging time, determined under the same conditions, is shown for the charged spot center and a number of adjacent points. During creation of the charged spot charging current was measured. The results of the measurements are discussed. A new mechanism of dielectric charging by electron beam is proposed. A CSFE is formulated, and its significance for the operation of CRT is stated. Criticism is given of in-plane grid effect. The paper presents calculations of fields for grid target models determining the mechanism of dielectric charging by electron beam.

  19. Beam Studies with Electron Columns

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, V.; Valishev, A.; Kuznetsov, G.; /Fermilab; Kamerdzhiev, V.; /Julich, Forschungszentrum; Romanov, A.; /Novosibirsk, IYF

    2009-04-01

    We report preliminary results of experimental studies of 'electron columns' in the Tevatron and in a specialized test setup. In the Tevatron, a beam of 150 GeV protons ionizes residual gas and ionization electrons are stored in an electrostatic trap immersed into strong longitudinal magnetic field. Shifts of proton betatron frequencies are observed. In the test setup, we observe effects pointing to accumulation and escape of ionization electrons.

  20. Generation of pulsed ion beams by an inductive storage pulsed power generator

    Science.gov (United States)

    Katsuki, Sunao; Akiyama, Hidenori; Maeda, Sadao

    1990-10-01

    A pulsed power generator by an inductive energy storage system is extremely compact and light in comparison with a conventional pulsed power generator, which consists of a Marx bank and a water pulse forming line. A compact and light pulse power generator is applied to the generation of pulsed ion beams. A thin copper fuse is used an an opening switch, which is necessary in the inductive storage pulsed power generator. A magnetically insulated diode is used for the generation of ion beams. The pulsed ion beams are successfully generated by the inductive storage pulsed power generator for the first time.

  1. Beam distribution reconstruction simulation for electron beam probe

    CERN Document Server

    Feng, Yongchun; Li, Peng; Kang, Xincai; Yin, Yan; Liu, Tong; You, Yaoyao; Chen, Yucong; Zhao, Tiecheng; Xu, Zhiguo; Wang, Yanyu; Yuan, Youjin

    2016-01-01

    Electron beam probe (EBP) is a new principle detector, which makes use of a low-intensity and low-energy electron beam to measure the transverse profile, bunch shape, beam neutralization and beam wake field of an intense beam with small dimensions. While can be applied to many aspects, we limit our analysis to beam distribution reconstruction. This kind of detector is almost non-interceptive for all of the beam and does not disturb the machine environment. In this paper, we present the theoretical aspects behind this technique for beam distribution measurement and some simulation results of the detector involved. First, a method to obtain parallel electron beam is introduced and a simulation code is developed. And then, EBP as a profile monitor for dense beam is simulated using fast scan method under various target beam profile, such as KV distribution, waterbag distribution, parabolic distribution, Gaussian distribution and halo distribution. Profile reconstruction from the deflected electron beam trajectory...

  2. Impact of Electron Collision Mixing on the delay times of an electron beam excited Atomic Xenon laser

    NARCIS (Netherlands)

    Peters, Peter J.; Lan, Yun Fu; Ohwa, Mieko; Kushner, Mark J.

    1990-01-01

    The atomic xenon (5d¿6p) infrared laser has been experimentally and theoretically investigated using a short-pulse (30-ns), high-power (1-10-MW/cm3) coaxial electron beam excitation source. In most cases, laser oscillation is not observed during the e-beam current pulse. Laser pulses of hundreds of

  3. The Electron Beam Semiconductor (EBS) amplifier

    Science.gov (United States)

    True, R. M.; Baxendale, J. F.

    1980-07-01

    The Electron Beam Semiconductor (EBS) concept has existed for three decades; but only within the last decade has an active, well-defined program been underway to develop devices that can operate as high-power radio frequency(RF) amplifiers, fast risetime switches, and current and voltage pulse amplifiers. This report discusses the test procedures, data and results of reliability testing of RF and video pulse EBS amplifiers at Electronics Research and Development Command (ERADCOM), Fort Monmouth, New Jersey. Also, the experimental analysis of the series connected diode EBS device is described in detail. Finally, the report concludes with a discussion of the state-of-the-art of EBS and future trends of the technology.

  4. Radiation damping in pulsed Gaussian beams

    Science.gov (United States)

    Harvey, Chris; Marklund, Mattias

    2012-01-01

    We consider the effects of radiation damping on the electron dynamics in a Gaussian-beam model of a laser field. For high intensities, i.e., with dimensionless intensity a0≫1, it is found that the dynamics divides into three regimes. For low-energy electrons (low initial γ factor, γ0) the radiation damping effects are negligible. At higher energies, but still at 2γ0a0 one is in a regime of radiation-reaction-induced electron capture. This capture is found to be stable with respect to the spatial properties of the electron beam and results in a significant energy loss of the electrons. In this regime the plane-wave model of the laser field provides a good description of the dynamics, whereas for lower energies the Gaussian-beam and plane-wave models differ significantly. Finally the dynamics is considered for the case of an x-ray free-electron laser field. It is found that the significantly lower intensities of such fields inhibit the damping effects.

  5. Radiative cooling of relativistic electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhirong [Stanford Univ., CA (United States)

    1998-05-01

    Modern high-energy particle accelerators and synchrotron light sources demand smaller and smaller beam emittances in order to achieve higher luminosity or better brightness. For light particles such as electrons and positrons, radiation damping is a natural and effective way to obtain low emittance beams. However, the quantum aspect of radiation introduces random noise into the damped beams, yielding equilibrium emittances which depend upon the design of a specific machine. In this dissertation, the author attempts to make a complete analysis of the process of radiation damping and quantum excitation in various accelerator systems, such as bending magnets, focusing channels and laser fields. Because radiation is formed over a finite time and emitted in quanta of discrete energies, he invokes the quantum mechanical approach whenever the quasiclassical picture of radiation is insufficient. He shows that radiation damping in a focusing system is fundamentally different from that in a bending system. Quantum excitation to the transverse dimensions is absent in a straight, continuous focusing channel, and is exponentially suppressed in a focusing-dominated ring. Thus, the transverse normalized emittances in such systems can in principle be damped to the Compton wavelength of the electron, limited only by the Heisenberg uncertainty principle. In addition, he investigates methods of rapid damping such as radiative laser cooling. He proposes a laser-electron storage ring (LESR) where the electron beam in a compact storage ring repetitively interacts with an intense laser pulse stored in an optical resonator. The laser-electron interaction gives rise to rapid cooling of electron beams and can be used to overcome the space charge effects encountered in a medium energy circular machine. Applications to the designs of low emittance damping rings and compact x-ray sources are also explored.

  6. METHOD OF ELECTRON BEAM PROCESSING

    DEFF Research Database (Denmark)

    2003-01-01

    As a rule, electron beam welding takes place in a vacuum. However, this means that the workpieces in question have to be placed in a vacuum chamber and have to be removed therefrom after welding. This is time−consuming and a serious limitation of a process the greatest advantage of which...... is the option of welding workpieces of large thicknesses. Therefore the idea is to guide the electron beam (2) to the workpiece via a hollow wire, said wire thereby acting as a prolongation of the vacuum chamber (4) down to workpiece. Thus, a workpiece need not be placed inside the vacuum chamber, thereby...

  7. High energy electron beams for ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Turman, B.N.; Glass, S.J.; Halbleib, J.A.; Helmich, D.R.; Loehman, R.E. [Sandia National Labs., Albuquerque, NM (United States); Clifford, J.R. [Titan Corp., Albuquerque, NM (United States)

    1994-12-31

    Joining of structural ceramics is possible using high melting point metals such as Mo and Pt that are heated with a high energy electron beam, with the potential for high temperature joining. A 10 MeV electron beam can penetrate through 1 cm of ceramic, offering the possibility of buried interface joining. Because of transient heating and the lower heat capacity of the metal relative to the ceramic, a pulsed high power beam has the potential for melting the metal without decomposing or melting the ceramic. We have demonstrated the feasibility of the process with a series of 10 MeV, 1 kW electron beam experiments. Shear strengths up to 28 MPa have been measured. This strength is comparable to that reported in the literature for bonding silicon nitride to molybdenum with copper-silver-titanium braze, but weaker than that reported for Si{sub 3}N{sub 4}-Si{sub 3}N{sub 4} with gold-nickel braze. The bonding mechanism appears to be a thin silicide layer.

  8. Synchronization of Sub-Picosecond Electron and Laser Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Rosenzweig, J.B.; Le Sage G.P.

    2000-08-15

    Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is subpicosecond, with tens of femtosecond synchronization implied for next-generation experiments. Typically, an RF electron accelerator is synchronized to a short pulse laser system by detecting the repetition signal of a laser oscillator, adjusted to an exact subharmonic of the linac RF frequency, and multiplying or phase locking this signal to produce the master RF clock. Pulse-to-pulse jitter characteristic of self-mode-locked laser oscillators represents a direct contribution to the ultimate timing jitter between a high intensity laser focus and electron beam at the interaction point, or a photocathode drive laser in an RF photoinjector. This timing jitter problem has been addressed most seriously in the context of the RF photoinjector, where the electron beam properties are sensitive functions of relative timing jitter. The timing jitter achieved in synchronized photocathode drive laser systems is near, or slightly below one picosecond. The ultimate time of arrival jitter of the beam at the photoinjector exit is typically a bit smaller than the photocathode drive-laser jitter due to velocity compression effects in the first RF cell of the gun. This tendency of the timing of the electron beam arrival at a given spatial point to lock to the RF lock is strongly reinforced by use of magnetic compression.

  9. Measuring the electron beam energy in a magnetic bunch compressor

    Energy Technology Data Exchange (ETDEWEB)

    Hacker, Kirsten

    2010-09-15

    Within this thesis, work was carried out in and around the first bunch compressor chicane of the FLASH (Free-electron LASer in Hamburg) linear accelerator in which two distinct systems were developed for the measurement of an electron beams' position with sub-5 {mu}m precision over a 10 cm range. One of these two systems utilized RF techniques to measure the difference between the arrival-times of two broadband electrical pulses generated by the passage of the electron beam adjacent to a pickup antenna. The other system measured the arrival-times of the pulses from the pickup with an optical technique dependent on the delivery of laser pulses which are synchronized to the RF reference of the machine. The relative advantages and disadvantages of these two techniques are explored and compared to other available approaches to measure the same beam property, including a time-of-flight measurement with two beam arrival-time monitors and a synchrotron light monitor with two photomultiplier tubes. The electron beam position measurement is required as part of a measurement of the electron beam energy and could be used in an intra-bunch-train beam-based feedback system that would stabilize the amplitude of the accelerating field. By stabilizing the accelerating field amplitude, the arrival-time of the electron beam can be made more stable. By stabilizing the electron beam arrival-time relative to a stable reference, diagnostic, seeding, and beam-manipulation lasers can be synchronized to the beam. (orig.)

  10. Mycosis fungoides. Electron beam therapy.

    Science.gov (United States)

    Spittle, M F

    1977-01-01

    The most effective treatment of late mycosis fungoides is total skin electron beam therapy. The beam at the Hammersmith Hospital in London has been adapted to treat these patients. Patients with advanced disease who have failed more conservative methods of treatment are irradiated. The electron beam is modified by the use of carbon and copper scatterers to produce an 80 percent depth dose at 5.5, 8 and 11.5 millimeters below the skin surface. The dose achieved in most patients is between 1500 rads and 2600 rads given in 10 to 13 treatments over 5-7 weeks. Recently the higher dose range has been employed and lithium flouride studies have shown that giving these doses from each of 4 fields, the dose achieved on the skin is approximately twice the given dose. The management of patients and the effects of treatment are discussed.

  11. Optical circular deflector with attosecond resolution for ultrashort electron beam

    Directory of Open Access Journals (Sweden)

    Zhen Zhang

    2017-05-01

    Full Text Available A novel method using high-power laser as a circular deflector is proposed for the measurement of femtosecond (fs and sub-fs electron beam. In the scheme, the electron beam interacts with a laser pulse operating in a radially polarized doughnut mode (TEM_{01^{*}} in a helical undulator, generating angular kicks along the beam in two directions at the same time. The phase difference between the two angular kicks makes the beam form a ring after a propagation section with appropriate phase advance, which can reveal the current profile of the electron beam. Detailed theoretical analysis of the method and numerical results with reasonable parameters are both presented. It is shown that the temporal resolution can reach up to ∼100 attosecond, which is a significant improvement for the diagnostics of ultrashort electron beam.

  12. A Monochromatic electron neutrino beam

    CERN Document Server

    Lindroos, Mats; Burguet-Castell, J; Espinoza, C

    In the last few years spectacular results have been achieved with the demonstration of non vanishingneutrino masses and flavour mixing. Here, a novel method to create a monochromaticneutrino beam, an old dream for neutrino physics, is described based on the recent discoveryof nuclei with fast decay through electron-capture to Gamow-Teller resonances in super allowedtransitions.

  13. Pulsed Power for a Dynamic Transmission Electron Microscope

    Energy Technology Data Exchange (ETDEWEB)

    dehope, w j; browning, n; campbell, g; cook, e; king, w; lagrange, t; reed, b; stuart, b; Shuttlesworth, R; Pyke, B

    2009-06-25

    Lawrence Livermore National Laboratory (LLNL) has converted a commercial 200kV transmission electron microscope (TEM) into an ultrafast, nanoscale diagnostic tool for material science studies. The resulting Dynamic Transmission Electron Microscope (DTEM) has provided a unique tool for the study of material phase transitions, reaction front analyses, and other studies in the fields of chemistry, materials science, and biology. The TEM's thermionic electron emission source was replaced with a fast photocathode and a laser beam path was provided for ultraviolet surface illumination. The resulting photoelectron beam gives downstream images of 2 and 20 ns exposure times at 100 and 10 nm spatial resolution. A separate laser, used as a pump pulse, is used to heat, ignite, or shock samples while the photocathode electron pulses, carefully time-synchronized with the pump, function as probe in fast transient studies. The device functions in both imaging and diffraction modes. A laser upgrade is underway to make arbitrary cathode pulse trains of variable pulse width of 10-1000 ns. Along with a fast e-beam deflection scheme, a 'movie mode' capability will be added to this unique diagnostic tool. This talk will review conventional electron microscopy and its limitations, discuss the development and capabilities of DTEM, in particularly addressing the prime and pulsed power considerations in the design and fabrication of the DTEM, and conclude with the presentation of a deflector and solid-state pulser design for Movie-Mode DTEM.

  14. Laser cooling of electron beams for linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Telnov, V.

    1996-10-01

    A novel method of electron beam cooling is considered which can be used for linear colliders. The electron beam is cooled during collision with focused powerful laser pulse. With reasonable laser parameters (laser flash energy about 10 J) one can decrease transverse beam emittances by a factor about 10 per one stage. The ultimate transverse emittances are much below that given by other methods. Depolarization of a beam during the cooling is about 5--15% for one stage. This method is especially useful for photon colliders and open new possibilities for e{sup +}e{sup {minus}} colliders and x-ray FEL based on high energy linacs.

  15. Development of high current electron beam generator

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byeong Cheol; Lee, Jong Min; Kim, Sun Kook [and others

    1997-05-01

    A high-current electron beam generator has been developed. The energy and the average current of the electron beam are 2 MeV and 50 mA, respectively. The electron beam generator is composed of an electron gun, RF acceleration cavities, a 260-kW RF generator, electron beam optics components, and control system, etc. The electron beam generator will be used for the development of a millimeter-wave free-electron laser and a high average power infrared free-electron laser. The machine will also be used as a user facility in nuclear industry, environment industry, semiconductor industry, chemical industry, etc. (author). 15 tabs., 85 figs.

  16. Generation and application of pseudospark-sourced electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Cross, A W [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Yin, H [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); He, W [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Ronald, K [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Phelps, A D R [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Pitchford, L C [CAPT, Universite Paul Sabatier, 118 rte de Narbonne, 31062 Toulouse (France)

    2007-04-07

    A pseudospark (PS) discharge has been shown to be a promising source of high brightness, high intensity electron beam pulses. A PS-sourced electron beam has two phases, an initial hollow cathode phase (HCP) beam followed by a conductive phase (CP) beam. In our experiments, a 22 kV, 50 A HCP beam of brightness 10{sup 9-10} A m{sup -2} rad{sup -2} followed by a 200 V, 200 A CP beam of brightness 10{sup 11-12} A m{sup -2} rad{sup -2} were measured. Experiments have been conducted with the application of a HCP beam in a Cherenkov interaction with no input seed wave and with post-acceleration of the CP beam. In this paper, a new Cherenkov interaction experiment with an input seed wave from a 20 kW, 35 GHz pulsed magnetron has been designed using the same PS HCP beam. Simulation results of the interaction will be presented and further PS electron beam applications will be discussed.

  17. Reducing the beam current in Linac4 in pulse to pulse mode.

    CERN Document Server

    Lallement, JB; CERN. Geneva. BE Department

    2009-01-01

    In order to deliver different beam intensities to users, we studied the possibility of varying the Linac4 beam current at PS Booster injection in pulse to pulse mode. This report gives the possible configurations of Linac4 Low and Medium Energy Beam Transport lines (LEBT and MEBT) that lead to a consistent current reduction.

  18. Semi-classical beam cooling in an intense laser pulse

    CERN Document Server

    Yoffe, Samuel R; Noble, Adam; Jaroszynski, Dino A

    2014-01-01

    We present a novel technique for studying the evolution of a particle distribution using single particle dynamics such that the distribution can be accurately reconstructed using fewer particles than existing approaches. To demonstrate this, the Landau-Lifshiftz description of radiation reaction is adapted into a semi-classical model, for which the Vlasov equation is intractable. Collision between an energetic electron bunch and high-intensity laser pulses are then compared using the two theories. Reduction in beam cooling is observed for the semi-classical case.

  19. Modification of subsurface structure in TiC-(Ni-Cr) cermet composite under pulsed electron-beam irradiation of samples in plasmas of light and heavy inert gases

    Science.gov (United States)

    Ovcharenko, V. E.; Ivanov, K. V.; Baohai, Yu; Zhengkun, Li; Hua, Xu Yun; Lisheng, Zhong

    2016-11-01

    Experiments with metal ceramic alloys with various ceramic content proved that the performance degree of pulsed electron-ion-plasma irradiation as a technology of creating a surface layer multilevel structural phase condition, where particles are measured within a nano dimensional diapason, depends on ionization energy degree as well as on plasma-supporting gas atomic weight. When ionization energy falls parallel to plasma-supporting gas atomic weight growth, ceramic component particles dissolve in a metal binding melt more quickly, and an accelerated dispersion of ceramic particles to nano sized level can be observed. A multilevel structural phase condition causes friction ratio decrease, while a metal ceramic alloy surface layer wear ability increases many-folds.

  20. Electron beam control for barely separated beams

    Science.gov (United States)

    Douglas, David R.; Ament, Lucas J. P.

    2017-04-18

    A method for achieving independent control of multiple beams in close proximity to one another, such as in a multi-pass accelerator where coaxial beams are at different energies, but moving on a common axis, and need to be split into spatially separated beams for efficient recirculation transport. The method for independent control includes placing a magnet arrangement in the path of the barely separated beams with the magnet arrangement including at least two multipole magnets spaced closely together and having a multipole distribution including at least one odd multipole and one even multipole. The magnetic fields are then tuned to cancel out for a first of the barely separated beams to allow independent control of the second beam with common magnets. The magnetic fields may be tuned to cancel out either the dipole component or tuned to cancel out the quadrupole component in order to independently control the separate beams.

  1. Beam Dynamics With Electron Cooling

    CERN Document Server

    Uesugi, T; Noda, K; Shibuya, S; Syresin, E M

    2004-01-01

    Electron cooling experiments have been carried out at HIMAC in order to develop new technologies in heavy-ion therapy and related researches. The cool-stacking method, in particular, has been studied to increase the intensity of heavy-ions. The maximum stack intensity was 2 mA, above which a fast ion losses occurred simulatneously with the vertical coherent oscillations. The instability depends on the working point, the stacked ion-density and the electron-beam density. The instability was suppressed by reducing the peak ion-density with RF-knockout heating.

  2. Effect of high current pulsed electron beam treatment on wear resistance of WC-Co hard alloys%强流脉冲电子束处理对WC-Co硬质合金耐磨性的影响

    Institute of Scientific and Technical Information of China (English)

    任鑫; 曹丹凤; 徐洋; 郝胜智

    2015-01-01

    作为一种新型高效的表面改性技术,强流脉冲电子束( HCPEB)由于可以在极短时间内诱发的温度-应力耦合作用,改性层内组织细化并生成纳米新相WC1-x、Co3 W3 C、Co3 W9 C4和石墨,从而改善合金的理化性质以及力学性能等,达到表面强化的目的。本文研究了HCPEB表面改性处理后YG8、YG6X和YG6硬质合金耐磨性的变化情况。结果表明,23.4 kV、25次辐照处理后的YG8硬质合金耐磨性提高3倍;27 kV、20次辐照处理后YG6X的耐磨性提高6.4倍;27 kV、20次辐照处理后YG6硬质合金耐磨性提高4.4倍。 HCPEB处理后的WC-Co硬质合金的耐磨性均有明显提高。%High current pulsed electron beam has been proved to be an effective method for surface modification of materials in recent years. Along with the extremely high energy density deposition on the surface of material, the thermal and mechanical processes can make the rise of the non-equilibrium structure surface modification effect accompanied by the formation of a mixture of nano-grained WC1-x , Co3 W3 C, Co3 W9 C4 and graphite, and then the physical, chemical and mechanical properties were improved. The effect of high current pulsed electron beam treatment on wear resistance of WC-Co hard alloys coating such as YG8, YG6 and YG6X alloy was investigated. The results show that the YG8 hard alloy is used to modifying by 20 pulses high current pulsed electron beam under the condition of the accelerating voltage of 23. 4 kV, the wear resistance increases by a factor of 3 times compared with the original sample. After 20 pulses treatment by high current pulsed electron beam under the condition of the accelerating voltage of 27 kV, the wear resistance of the YG6 hard alloy raises by a factor of 6. 4 times, and the YG6X hard alloy’s wear resistance is increased by a factor of 4. 4 times.

  3. Laser wakefield acceleration of polarized electron beams

    Science.gov (United States)

    Pugacheva, D. V.; Andreev, N. E.; Cros, B.

    2016-11-01

    The acceleration of highly polarized electron beams are widely used in state-of-the-art high-energy physics experiments. In this work, a model for investigation of polarization dynamics of electron beams in the laser-plasma accelerator depending on the initial energy of electrons was developed and tested. To obtain the evolution of the trajectory and momentum of the electron for modeling its acceleration the wakefield structure was determined. The spin precession of the beam electron was described by Thomas-Bargman-Michel-Telegdi equations. The evolution of the electron beam polarization was investigated for zero-emittance beams with zero-energy spread.

  4. 196 Beams in a Scanning Electron Microscope

    NARCIS (Netherlands)

    Mohammadi-Gheidari, A.

    2013-01-01

    In this thesis, for the first time ever, it is demonstrated that 196 beams out of a single electron source can be finely focused onto the sample using the electron optics of a standard single beam SEM. During this PhD thesis, a multi beam scanning electron (MBSEM) was designed and built. The thesis

  5. Cooling of Relativistic Electron-Beams

    NARCIS (Netherlands)

    Bazylev, V. A.; Tulupov, A. V.

    1993-01-01

    A method of reducing the energy spread of an electron beam in a free-electron laser is suggested. The electron beam compression is based on a nonlinear mechanism of electron interactions with a ponderomotive wave in the presence of a constant and uniform magnetic field perpendicular to the electron

  6. Electron beam induced THz emissions from nanotube array

    Science.gov (United States)

    Kumar, Ashok; Kumar, Pawan

    2016-10-01

    A new scheme of terahertz radiation generation by passing an ultrashort electron bunch over a planar array of nanotube/nanorod across their lengths is proposed and analyzed. The beam pulse exerts a repulsive impulse on the free electron cylinder of each nanorod and displaces them with respect to ion cylinder. After the passage of the pulse, the electron cylinders oscillate at their natural frequency ω p / √{ 2 } (where ω p is the plasma frequency of electrons in each carbon nanotube) acting as phased array dipole antennae, emitting THz radiation.

  7. Beam accumulation with the SIS electron cooler

    CERN Document Server

    Steck, Markus; Blasche, K; Franczak, B J; Franzke, B; Winkler, T; Parkhomchuk, V V

    2000-01-01

    An electron cooling system has started operation in the heavy ion synchrotron SIS which is used to increase the intensity for highly charged ions. Fast transverse cooling of the hot ion beam after horizontal multiturn injection allows beam accumulation at the injection energy. After optimization of the accumulation process an intensity increase in a synchrotron pulse by more than one order of magnitude has been achieved. For highly charged ions the maximum number of particles has been increased from 1x10 sup 8 to 1x10 sup 9. For lighter ions intensity limitations have been encountered which are caused by the high phase space density of the cooled ion beam. Momentum spreads in the 10 sup - sup 4 range and emittances well below 10 pi mm mrad have been demonstrated. Recombination losses both in the residual gas and with the free cooler electrons determine the maximum intensity for highly charged ions. Systematic measurements of the recombination rates have been performed providing data for an optimum choice of t...

  8. Generation of Ramped Current Profiles in Relativistic Electron Beams Using Wakefields in Dielectric Structures.

    Science.gov (United States)

    Andonian, G; Barber, S; O'Shea, F H; Fedurin, M; Kusche, K; Swinson, C; Rosenzweig, J B

    2017-02-03

    Temporal pulse tailoring of charged-particle beams is essential to optimize efficiency in collinear wakefield acceleration schemes. In this Letter, we demonstrate a novel phase space manipulation method that employs a beam wakefield interaction in a dielectric structure, followed by bunch compression in a permanent magnet chicane, to longitudinally tailor the pulse shape of an electron beam. This compact, passive, approach was used to generate a nearly linearly ramped current profile in a relativistic electron beam experiment carried out at the Brookhaven National Laboratory Accelerator Test Facility. Here, we report on these experimental results including beam and wakefield diagnostics and pulse profile reconstruction techniques.

  9. Generation of Ramped Current Profiles in Relativistic Electron Beams Using Wakefields in Dielectric Structures

    Science.gov (United States)

    Andonian, G.; Barber, S.; O'Shea, F. H.; Fedurin, M.; Kusche, K.; Swinson, C.; Rosenzweig, J. B.

    2017-02-01

    Temporal pulse tailoring of charged-particle beams is essential to optimize efficiency in collinear wakefield acceleration schemes. In this Letter, we demonstrate a novel phase space manipulation method that employs a beam wakefield interaction in a dielectric structure, followed by bunch compression in a permanent magnet chicane, to longitudinally tailor the pulse shape of an electron beam. This compact, passive, approach was used to generate a nearly linearly ramped current profile in a relativistic electron beam experiment carried out at the Brookhaven National Laboratory Accelerator Test Facility. Here, we report on these experimental results including beam and wakefield diagnostics and pulse profile reconstruction techniques.

  10. Enhancement of beam pulse controllability for a single-pulse formation system of a cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Kurashima, Satoshi, E-mail: kurashima.satoshi@jaea.go.jp; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Taguchi, Mitsumasa [Quantum Beam Science Center, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Fukuda, Mitsuhiro [Research Center for Nuclear Physics, Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2015-07-15

    The single-pulse formation technique using a beam chopping system consisting of two types of high-voltage beam kickers was improved to enhance the quality and intensity of the single-pulse beam with a pulse interval over 1 μs at the Japan Atomic Energy Agency cyclotron facility. A contamination rate of neighboring beam bunches in the single-pulse beam was reduced to less than 0.1%. Long-term purification of the single pulse beam was guaranteed by the well-controlled magnetic field stabilization system for the cyclotron magnet. Reduction of the multi-turn extraction number for suppressing the neighboring beam bunch contamination was achieved by restriction of a beam phase width and precise optimization of a particle acceleration phase. In addition, the single-pulse beam intensity was increased by a factor of two or more by a combination of two types of beam bunchers using sinusoidal and saw-tooth voltage waveforms. Provision of the high quality intense single-pulse beam contributed to improve the accuracy of experiments for investigation of scintillation light time-profile and for neutron energy measurement by a time-of-flight method.

  11. Control And Transport Of Intense Electron Beams

    CERN Document Server

    Li, H

    2004-01-01

    The transport of intense beams for advanced accelerator applications with high-intensity beams such as heavy-ion inertial fusion, spallation neutron sources, and intense light sources requires tight control of beam characteristics over long distances. The University of Maryland Electron Ring (UMER), which uses low energy, high current electron beams to model the transport physics of intense space-charge-dominated beams, employs real-time beam characterization and control in order to optimize beam quality throughout the strong focusing lattice. We describe in this dissertation the main beam control techniques used in UMER, which include optimal beam steering by quadrupole scans, beam rotation correction using a skew corrector, rms envelope matching and optimization, empirical envelope matching, beam injection, and phase space reconstruction using a tomographic method. Using these control techniques, we achieved the design goals for UMER. The procedure is not only indispensable for optimum beam transport over l...

  12. Runaway electron beam control for longitudinally pumped metal vapor lasers

    Science.gov (United States)

    Kolbychev, G. V.; Kolbycheva, P. D.

    1995-08-01

    Physics and techniques for producing of the pulsed runaway electron beams are considered. The main obstacle for increasing electron energies in the beams is revealed to be a self- breakdown of the e-gun's gas-filled diode. Two methods to suppress the self-breakdown and enhance the volumetric discharge producing the e-beam are offered and examined. Each of them provides 1.5 fold increase of the ceiling potential on the gun. The methods also give the ways to control several guns simultaneously. Resulting in the possibility of realizing the powerful longitudinal pumping of metal-vapor lasers on self-terminated transitions of atoms or ions.

  13. Electron Beam Curing of Advanced Composites

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The fundamental concept of electron beam method and the application in cure of composites are elaborated in this paper. The components of electron beam curing system are introduced. The mechanisms of interaction between electron beam and polymer matrix composites are presented. Recent studies reported including work of authors themselves on electron beam curing of composites are also discussed. Moreover, the authors believe that it is necessary to do the basic research about understanding how electron beam affects cured network and the mechanical/physical properties of the composites, for establishing a quantitative or semi-quantitative formulation.

  14. Pulsed supersonic helium beams for plasma edge diagnosis

    Science.gov (United States)

    Diez-Rojo, T.; Herrero, V. J.; Tanarro, I.; Tabarés, F. L.; Tafalla, D.

    1997-03-01

    An experimental setup for the production of pulsed supersonic He beams to be used for plasma edge diagnosis in fusion devices is described. A compromise between compact design, low cost, and good quality of the probe beams has been met. The main characteristics of the generated beams, such as pulse shape, absolute flux intensity, and velocity distribution, differ in general from those expected for ideal beam performance and have been determined and optimized experimentally. A first test of this He beam source at the TJ-I UP Torsatron in Madrid is also reported.

  15. Pulsed supersonic helium beams for plasma edge diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Diez-Rojo, T.; Herrero, V.J.; Tanarro, I. [Instituto de Estructura de la Materia (CSIC), Serrano 123, 28006 Madrid (Spain); Tabares, F.L.; Tafalla, D. [Asociacion EURATOM-CIEMAT para Fusion, Avenue Complutense 22, 28040 Madrid (Spain)

    1997-03-01

    An experimental setup for the production of pulsed supersonic He beams to be used for plasma edge diagnosis in fusion devices is described. A compromise between compact design, low cost, and good quality of the probe beams has been met. The main characteristics of the generated beams, such as pulse shape, absolute flux intensity, and velocity distribution, differ in general from those expected for ideal beam performance and have been determined and optimized experimentally. A first test of this He beam source at the TJ-I UP Torsatron in Madrid is also reported. {copyright} {ital 1997 American Institute of Physics.}

  16. Scintillation of lead tungstate crystal studied with single-electron beam from KUFEL

    Energy Technology Data Exchange (ETDEWEB)

    Rizwan, Mohamad, E-mail: rizwan@nucl.kyushu-u.ac.jp; Uozumi, Yusuke; Matsuo, Kazuki [Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka (Japan); Ohgaki, Hideaki; Kii, Toshiteru; Zen, Heishun [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto (Japan); Tsamalaidze, Zviadi; Evtoukhovitch, Petr; Valentin, Samoilov [Joint Institute for Nuclear Research, JINR, Joliot-Curie Str.6, Dubna (Russian Federation)

    2015-04-29

    Lead tungstate (PWO) crystal has a very fast response, high atomic density and high radiation hardness. Therefore, they are suitable to be used for high-energy nuclear data measurements under high-background circumstances. Although a good electron-ion separation with a pulse shape analysis technique is essential, scintillation pulse shapes have not been observed with electron beams of a wide energy range. A single-electron beam technique has been developed at Kyoto University Free Electron Laser (KUFEL), and electron beams of 4-38 MeV are available. During the experiments, single electron beams bombarded a PWO crystal. By using oscilloscope we observed scintillation pulses of a PWO crystal coupled with a photomultiplier tube. Measured spectra were compared with the simulation code of EGS5 to analyze scattering effects. As the result, the pulse amplitudes show good linearity and the pulse shapes are almost constant in the observed energy range.

  17. Electron optics of microlenses with inclined beams

    NARCIS (Netherlands)

    Zhang, Y.; Barth, J.E.; Kruit, P.

    2008-01-01

    For multielectron beam systems with a single electron source, the outside beams need to be collimated before entering the individual microcolumns. As an alternative of the traditional multibeam source design where the broad beam from the source is collimated by a single lens, the broad beam can be f

  18. Production of a sub-10 fs electron beam with 107 electrons

    Science.gov (United States)

    Han, Jang-Hui

    2011-05-01

    We study the possibility to produce a 1.6 pC electron beam (107 electrons) with a bunch length of less than 10 fs and a beam energy of a few MeV. Such a short, relativistic beam will be useful for an electron diffraction experiment with a 10 fs time resolution. An electron beam with 107 electrons will allow a single-shot experiment with a laser pulse pump and an electron beam probe. In this design, an S-band photocathode gun is used for generating and accelerating a beam and a buncher consisting of two S-band four-cell cavities is used for temporally compressing the beam. Focusing solenoids control the beam transverse divergence and size at the sample. Numerical optimization is carried out to achieve a beam with a 4 fs full-width-at-half-maximum length, a 26 microradian root-mean-square divergence, and a 2 nm transverse coherence length at a 3.24 MeV beam energy. When state-of-the-art rf stability is considered, beam arrival time jitter at the sample is calculated to be about 10 fs.

  19. Definition of Beam Diameter for Electron Beam Welding

    Energy Technology Data Exchange (ETDEWEB)

    Burgardt, Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pierce, Stanley W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dvornak, Matthew John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-11

    It is useful to characterize the dimensions of the electron beam during process development for electron beam welding applications. Analysis of the behavior of electron beam welds is simplest when a single number can be assigned to the beam properties that describes the size of the beam spot; this value we generically call the “beam diameter”. This approach has worked well for most applications and electron beam welding machines with the weld dimensions (width and depth) correlating well with the beam diameter. However, in recent weld development for a refractory alloy, Ta-10W, welded with a low voltage electron beam machine (LVEB), it was found that the weld dimensions (weld penetration and weld width) did not correlate well with the beam diameter and especially with the experimentally determined sharp focus point. These data suggest that the presently used definition of beam diameter may not be optimal for all applications. The possible reasons for this discrepancy and a suggested possible alternative diameter definition is the subject of this paper.

  20. Quantum radiation reaction in laser-electron-beam collisions.

    Science.gov (United States)

    Blackburn, T G; Ridgers, C P; Kirk, J G; Bell, A R

    2014-01-10

    It is possible using current high-intensity laser facilities to reach the quantum radiation reaction regime for energetic electrons. An experiment using a wakefield accelerator to drive GeV electrons into a counterpropagating laser pulse would demonstrate the increase in the yield of high-energy photons caused by the stochastic nature of quantum synchrotron emission: we show that a beam of 10(9) 1 GeV electrons colliding with a 30 fs laser pulse of intensity 10(22)  W cm(-2) will emit 6300 photons with energy greater than 700 MeV, 60× the number predicted by classical theory.

  1. Formation of Ti-Ta-based surface alloy on TiNi SMA substrate from thin films by pulsed electron-beam melting

    Science.gov (United States)

    Meisner, L. L.; Markov, A. B.; Ozur, G. E.; Rotshtein, V. P.; Yakovlev, E. V.; Meisner, S. N.; Poletika, T. M.; Girsova, S. L.; Semin, V. O.; Mironov, Yu P.

    2017-05-01

    TiNi shape memory alloys (SMAs) are unique metallic biomaterials due to combination of superelastisity and high corrosion resistance. Important factors limiting biomedical applications of TiNi SMAs are a danger of toxic Ni release into the adjacent tissues, as well as insufficient level of X-ray visibility. In this paper, the method for fabrication of protective Ni-free surface alloy of thickness ∼1 μm of near Ti70Ta30 composition on TiNi SMA substrate has been successfully realized. The method is based on multiple alternation of magnetron co-deposition of Ti70Ta30 thin (50 nm) films and their liquid-phase mixing with the TiNi substrate by microsecond low-energy, high current electron beam (≤15 keV, ∼2 J/cm2) using setup RITM-SP (Microsplav, Russia). It was found by AES, XRD, SEM/EDS and HRTEM/EDS examinations, that Ti-Ta surface alloy has an increased X-ray visibility and gradient multiphase amorphous-nanocrystalline structure containing nanopores.

  2. Experimental Studies of Temporal Electron Beam Shaping at the DUV-FEL Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Loos, H.; Doweel, D.; /SLAC; Sheehy, B.; Shen, Y.; Tsang, T.; Wang, X.; /Brookhaven; Serafini, L.; /INFN, Milan; Boscolo, M.; Ferrario, M.; Petrarca, M.; Vicario, C.; /Frascati

    2005-09-28

    The photoinjectors for future short wavelength high brightness accelerator driven light sources need to produce an electron beam with ultra-low emittance. At the DUVFEL facility at BNL, we studied the effect of longitudinally shaping the photocathode laser pulses on the electron beam dynamics. We report on measurements of the longitudinal phase space distributions and the time-resolved transverse beam parameters for both a Gaussian and a flat-top temporal laser pulse profile.

  3. [Theoretical investigation of the saturation correction for ionization chambers irradiated with pulsed beams of arbitrary pulse length].

    Science.gov (United States)

    Karsch, Leonhard; Pawelke, Jörg

    2014-09-01

    In ionization chambers, not all released charge is collected due to the recombination of charge carriers. This effect is taken into account by the saturation correction factor kS. A physical description of the correction factor has been established for pulsed radiation. However, it is only accurate when the pulse length is short compared with the collection time of the ionization chamber. In this paper we develop a description of the saturation correction for radiation pulses of arbitrary length. For this, a system of partial differential equations is solved iteratively. The numerical solutions are verified experimentally for a Roos ionization chamber (PTW TM34001) exposed to a pulsed electron beam. The results of this iterative procedure describe the experimental data well. The calculations are also possible for beam structures which are experimentally hard to get and thereby contribute to a better understanding and correct description of the saturation correction at arbitrary pulse length. Among other things the pulse length dependent distributions of the charge carriers in the ionization chamber is calculated, inclusive of the transition to the conditions prevailing in the case of continuous irradiation. Furthermore is shown that the formula for kS established by Hochhäuser and Balk is applicable even at arbitrary pulse length, if pulse duration dependent effective values are used for the parameters a and p. These effective values have been determined for the Roos chamber at pulse lengths up to 300 μs.

  4. The experimental study of neutralized electron beams for electron cooling

    CERN Document Server

    Bosser, Jacques; MacCaferri, R; Molinari, G; Tranquille, G; Varenne, F; Korotaev, Yu V; Meshkov, I N; Polyakov, V A; Smirnov, A; Syresin, E M

    1996-01-01

    In this report we present the latest experimental results on electron beam neutralization. These experiments have been made at LEAR and on the JINR test bench. The main difficulty in obtaining neutralized beams resides in an instability which is dependent on the electron beam current. A number of methods have been developed in order to overcome this instability and have enabled us to further investigate the possibility of generating intense low energy electron beams for the cooling of Pb ions.

  5. Beam rotation and shear in a large electron beam diode

    Energy Technology Data Exchange (ETDEWEB)

    Mansfield, C.R.; Oona, H.; Shurter, R.P.

    1990-01-01

    The time averaged electron beam current distribution of one of the electron guns of the Large Aperture Module (LAM) of the Aurora laser was measured as part of a larger set of experiments designed to study the electron beam transport to and energy deposition in the LAM laser chamber. The LAM laser chamber has a 1-m {times} 1-m aperture and is pumped from two sides along a 2-m length. A 10 ga. stainless steel sheet was placed inside the laser chamber and served multiple purposes. First, it was used to convert high energy electrons into X-rays in order to make radiograms of the electron beam. Second, the sheet was used as a Faraday cup to measure the total beam current. Third, individual Faraday cups were mounted on the plate to sample the time history of the electron beam at various positions. Each of the LAM electron gun diodes produces a beam of 750 kV electrons with a total current of about 500 kA which is relatively uniform over the cathode area of 1 m {times} 2 m. An applied magnetic field of about 1300 Gauss is used to prevent pinch of the beam during beam transport.

  6. The polarized electron beam at ELSA

    Science.gov (United States)

    Hoffmann, M.; Drachenfels, W. V.; Frommberger, F.; Gowin, M.; Helbing, K.; Hillert, W.; Husmann, D.; Keil, J.; Michel, T.; Naumann, J.; Speckner, T.; Zeitler, G.

    2001-06-01

    The future medium energy physics program at the electron stretcher accelerator ELSA of Bonn University mainly relies on experiments using polarized electrons in the energy range from 1 to 3.2 GeV. To provide a polarized beam with high polarization and sufficient intensity a dedicated source has been developed and set into operation. To prevent depolarization during acceleration in the circular accelerators several depolarizing resonances have to be corrected for. Intrinsic resonances are compensated using two pulsed betatron tune jump quadrupoles. The influence of imperfection resonances is successfully reduced applying a dynamic closed orbit correction in combination with an empirical harmonic correction on the energy ramp. In order to minimize beam depolarization, both types of resonances and the correction techniques have been studied in detail. It turned out that the polarization in ELSA can be conserved up to 2.5 GeV and partially up to 3.2 GeV which is demonstrated by measurements using a Møller polarimeter installed in the external GDH1-beamline. .

  7. Beam Dynamics in an Electron Lens with the Warp Particle-in-cell Code

    CERN Document Server

    Stancari, Giulio; Redaelli, Stefano

    2014-01-01

    Electron lenses are a mature technique for beam manipulation in colliders and storage rings. In an electron lens, a pulsed, magnetically confined electron beam with a given current-density profile interacts with the circulating beam to obtain the desired effect. Electron lenses were used in the Fermilab Tevatron collider for beam-beam compensation, for abort-gap clearing, and for halo scraping. They will be used in RHIC at BNL for head-on beam-beam compensation, and their application to the Large Hadron Collider for halo control is under development. At Fermilab, electron lenses will be implemented as lattice elements for nonlinear integrable optics. The design of electron lenses requires tools to calculate the kicks and wakefields experienced by the circulating beam. We use the Warp particle-in-cell code to study generation, transport, and evolution of the electron beam. For the first time, a fully 3-dimensional code is used for this purpose.

  8. Measurement of beam energy spread in a space-charge dominated electron beam

    Directory of Open Access Journals (Sweden)

    Y. Cui

    2004-07-01

    Full Text Available Characterization of beam energy spread in a space-charge dominated beam is very important to understanding the physics of intense beams. It is believed that coupling between the transverse and longitudinal directions via Coulomb collisions will cause an increase of the beam longitudinal energy spread. At the University of Maryland, experiments have been carried out to study the energy evolution in such intense beams with a high-resolution retarding field energy analyzer. The temporal beam energy profile along the beam pulse has been characterized at the distance of 25 cm from the anode of a gridded thermionic electron gun. The mean energy of the pulsed beams including the head and tail is reported here. The measured rms energy spread is in good agreement with the predictions of the intrabeam scattering theory. As an application of the beam energy measurement, the input impedance between the cathode and the grid due to beam loading can be calculated and the impedance number is found to be a constant in the operation region of the gun.

  9. Measurement of stability of electron beam generated by laser-driven plasma-based accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, S; Miura, E; Koyama, K; Kato, S [National Institute of Advanced Industrial Science and Technology, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)], E-mail: shi-masuda@aist.go.jp

    2008-05-01

    Quasi-monoenergetic electron beams with the energy of 30-80 MeV and large number of electrons more than 10{sup 8} were produced by focusing a 8TW, 50 fs Ti:sapphire laser pulse onto 1.6-1.9 x 10{sup 19} cm{sup -3} plasmas. Stability of the quasi-monoenergetic electron beam generation was evaluated using an in-situ observation system for the electron beam diagnostics.

  10. Efficient generation of high beam-quality attosecond pulse with polarization-gating Bessel-Gauss beam from highly-ionized media.

    Science.gov (United States)

    Li, Yang; Zhang, Qingbin; Hong, Weiyi; Wang, Shaoyi; Wang, Zhe; Lu, Peixiang

    2012-07-02

    Single attosecond pulse generation with polarization gating Bessel-Gauss beam in relatively strongly-ionized media is investigated. The results show that Bessel-Gauss beam has the ability to suppress the spatial plasma dispersion effects caused by high density of free electrons, thus the laser field can maintain its spatial profile through highly-ionized medium. This indicates the use of Bessel-Gauss beam has advantages over Gaussian beam in high harmonic generation under high ionization conditions. In our scheme, significant improvement of spatiotemporal properties of harmonics is achieved and an isolated attosecond pulse with high beam quality is filtered out using polarization gating.

  11. Control on Electron Beam Scanning Track

    Institute of Scientific and Technical Information of China (English)

    王学东; 姚舜

    2004-01-01

    In order to use electron beam as a movable welding heat source and whose energy distribution along its moving trace can be controlled, a method of electron beam scanning track and scanning mode control was put forward. Based on it, the electron beam scanning track and scanning mode can be edited at will according to actual requirements, and the energy input of each point of the scanning track can be controlled. In addition, the scanning frequency and points control, real time adjusting of the scanning track etc. were explained. This method can be used in electron beam brazing, surface modification, surface heat treatment etc.

  12. Coherent excitation with short electron pulses

    Science.gov (United States)

    Guertler, Andreas; Robicheaux, Francis; Noordam, Bart

    2000-06-01

    [1pt] The probability for a transition within an atom to be driven by a collision with a long pulse of electrons is proportional to the electron flux with the proportionality factor being the cross section for this transition. Recently it was shown [1] that for electron pulses shorter than the orbit time of the electron in the atom, a contribution of coherent scattering plays a role, which is proportional to the differential cross section in forward direction and the square of the electron flux. To investigate this effect, we are developing a picosecond electron gun [2]. Collision experiments will be done with Rydberg states in lithium around n=40 with Kepler orbit times in the order of 10 ps. For picosecond electron pulses, a quadratic dependance of the transition probability on the electron flux is expected in contrast to the linear dependance expected for nanosecond electron pulses. [1pt] References [1pt] [1] F. Robicheaux and L. D. Noordam, submitted to Phys. Rev. Lett. [1pt] [2] F. Robicheaux, G. M. Lankhuijzen, and L. D. Noordam, JOSA B 15, 1 (1998)

  13. Electron Beam Diagnostic Based on a Short Seeded FEL

    CERN Document Server

    Graves, W; Kaertner, Franz X; Zwart, T

    2005-01-01

    The optical properties of an FEL amplifier are sensitively dependent on the electron beam current profile, energy spread, and transverse emittance. In this paper we consider using a short FEL amplifier operating on a low harmonic of a visible-IR input seed as a mildly destructive electron beam diagnostic able to measure these properties for sub-ps time slices. The optical methods are described as well as a planned implementation of the device for the FERMI@Elettra XUV FEL under construction at Sincrotrone Trieste, including its fiber-based seed laser closely coupled with the facility timing system, undulator parameters, and requirements on the electron and FEL pulses. This diagnostic is conveniently integrated with a "laser heater" designed to increase the very low electron beam energy spread produced by a photoinjector in order to avoid space charge and coherent synchrotron radiation instabilities.

  14. Electron photodetachment by short laser pulse

    NARCIS (Netherlands)

    Golovinski, P. A.; Drobyshev, A. A.

    2012-01-01

    Expressions are derived for calculations of the total probabilities and electron spectra for the photodetachment of electrons from negative ions with filled valence s shells by ultrashort laser pulses. Particular calculations have been performed for two negative ions (H- and Li-) and titanium-sapphi

  15. Electron photodetachment by short laser pulse

    NARCIS (Netherlands)

    Golovinski, P. A.; Drobyshev, A. A.

    2012-01-01

    Expressions are derived for calculations of the total probabilities and electron spectra for the photodetachment of electrons from negative ions with filled valence s shells by ultrashort laser pulses. Particular calculations have been performed for two negative ions (H- and Li-) and titanium-sapphi

  16. Electron-beam dynamics for an advanced flash-radiography accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl August Jr. [Los Alamos National Laboratory

    2015-06-22

    Beam dynamics issues were assessed for a new linear induction electron accelerator. Special attention was paid to equilibrium beam transport, possible emittance growth, and beam stability. Especially problematic would be high-frequency beam instabilities that could blur individual radiographic source spots, low-frequency beam motion that could cause pulse-to-pulse spot displacement, and emittance growth that could enlarge the source spots. Beam physics issues were examined through theoretical analysis and computer simulations, including particle-in cell (PIC) codes. Beam instabilities investigated included beam breakup (BBU), image displacement, diocotron, parametric envelope, ion hose, and the resistive wall instability. Beam corkscrew motion and emittance growth from beam mismatch were also studied. It was concluded that a beam with radiographic quality equivalent to the present accelerators at Los Alamos will result if the same engineering standards and construction details are upheld.

  17. A device for measuring electron beam characteristics

    Directory of Open Access Journals (Sweden)

    M. Andreev

    2017-01-01

    Full Text Available This paper presents a device intended for diagnostics of electron beams and the results obtained with this device. The device comprises a rotating double probe operating in conjunction with an automated probe signal collection and processing system. This provides for measuring and estimating the electron beam characteristics such as radius, current density, power density, convergence angle, and brightness.

  18. LHC beam-beam compensation using wires and electron lenses

    CERN Document Server

    Dorda, U; Shiltsev, V; Zimmermann, F

    2007-01-01

    We present weak-strong simulation results for a possible application of current-carrying wires and electron lenses to compensate the LHC long-range and head-on beambeam interaction, respectively, for nominal and PACMAN bunches. We show that these measures have the potential to considerably increase the beam-beam limit, allowing for a corresponding increase in peak luminosity.

  19. Emittance of short-pulsed high-current ion beams formed from the plasma of the electron cyclotron resonance discharge sustained by high-power millimeter-wave gyrotron radiation

    Science.gov (United States)

    Razin, S.; Zorin, V.; Izotov, I.; Sidorov, A.; Skalyga, V.

    2014-02-01

    We present experimental results on measuring the emittance of short-pulsed (≤100 μs) high-current (80-100 mA) ion beams of heavy gases (Nitrogen, Argon) formed from a dense plasma of an ECR source of multiply charged ions (MCI) with quasi-gas-dynamic mode of plasma confinement in a magnetic trap of simple mirror configuration. The discharge was created by a high-power (90 kW) pulsed radiation of a 37.5-GHz gyrotron. The normalized emittance of generated ion beams of 100 mA current was (1.2-1.3) π mm mrad (70% of ions in the beams). Comparing these results with those obtained using a cusp magnetic trap, it was concluded that the structure of the trap magnetic field lines does not exert a decisive influence on the emittance of ion beams in the gas-dynamic ECR source of MCI.

  20. HOLLOW ELECTRON BEAM COLLIMATION FOR HL-LHC - EFFECT ON THE BEAM CORE

    Energy Technology Data Exchange (ETDEWEB)

    Fitterer, M. [Fermilab; Stancari, G. [Fermilab; Valishev, A. [Fermilab; Bruce, R. [CERN; Papadopoulou, S. [CERN; Papotti, G. [CERN; Pellegrini, D. [CERN; Pellegrini, S. [CERN; Valuch, D. [CERN; Wagner, J. F. [CERN

    2016-10-05

    Collimation with hollow electron beams or lenses (HEL) is currently one of the most promising concepts for active halo control in HL-LHC. In previous studies it has been shown that the halo can be efficiently removed with a hollow electron lens. Equally important as an efficient removal of the halo, is also to demonstrate that the core stays unperturbed. In this paper, we present a summary of the experiment at the LHC and simulations in view of the effect of the HEL on the beam core in case of a pulsed operation.

  1. Demonstration of low-loss electron beam transport and mm-wave experiments of the fusion-FEM

    NARCIS (Netherlands)

    Urbanus, W. H.; Bongers, W. A.; van Dijk, G.; van der Geer, C. A. J.; de Kruif, R.; Manintveld, P.; Pluygers, J.; Poelman, A. J.; Schüller, F. C.; Smeets, P. H. M.; Sterk, A. B.; Verhoeven, A. G. A.; Valentini, M.; van der Wiel, M. J.

    1998-01-01

    In the Fusion-FEM electrostatic Free Electron Maser, an electron beam loss current of less than 0.2% is essential for long-pulse operation. At reduced beam current, 3 A instead of the nominal 12 A, we have demonstrated electron beam acceleration and transport through the undulator at current losses

  2. Observation of coherent transition radiation using relativistic pico second electron pulse

    Energy Technology Data Exchange (ETDEWEB)

    Jones, C.R.; Kosai, H.; Dutt, J.M. [North Carolina Central Univ., Durham, NC (United States)

    1995-12-31

    When an electron beams passes through boundaries of two different media with different dielectric constants, it generates radiation. The radiation emitted by the prebunched electron beam becomes coherent if the size of the bunch is smaller than the wavelength. Therefore, transition radiation can be considered as a possible broad band radiation source as well as a probe to the pico second and sub picosecond electron beam profiles. Using 1.2 MeV, 200 mA, macropulse electron beam, transition radiation was generated. The electron gun consists of 2.856 GHz Klystron, thermionic cathode. The emitted electron beam was bunched by passing through an alpha magnet. As a result of the combination, a pico second pulse (1.2 MeV, up to 80 A micropulse) was obtained. Experimental results, comparisons with the theory, and simulated electron beam profiles will be presented.

  3. Experimental Studies of Temporal Electron Beam Shaping at the DUV-FEL Accelerator

    CERN Document Server

    Loos, H; Doweel, D; Ferario, M; Petrarca, M; Serafini, L; Sheehy, B; Shen, Y; Tsang, Thomas; Vicario, C; Wang, X

    2005-01-01

    The photoinjectors for future short wavelength high brightness accelerator driven light sources need to produce an electron beam with ultra-low emittance. At the DUV-FEL facility at BNL, we studied the effect of longitudinally shaping the photocathode laser pulses on the electron beam dynamics. We report on measurements of transverse and longitudinal electron beam emittance and comparisons of the experimental results with simulations.

  4. Optimizing the electron beam parameters for head-on beam-beam compensation in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y.; Fischer, W.; Pikin, A.; Gu, X.

    2011-03-28

    Head-on beam-beam compensation is adopted to compensate the large beam-beam tune spread from the protonproton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC). Two e-lenses are being built and to be in stalled near IP10 in the end of 2011. In this article we perform numeric simulation to investigate the effect of the electron beam parameters on the proton dynamics. The electron beam parameters include its transverse profile, size, current, offset and random errors in them. In this article we studied the effect of the electron beam parameters on the proton dynamics. The electron beam parameters include its transverse shape, size, current, offset and their random errors. From the study, we require that the electron beam size can not be smaller than the proton beam's. And the random noise in the electron current should be better than 0.1%. The offset of electron beam w.r.t. the proton beam center is crucial to head-on beam-beam compensation. Its random errors should be below {+-}8{micro}m.

  5. Collective acceleration of ions in picosecond pinched electron beams

    Science.gov (United States)

    Baryshnikov, V. I.; Paperny, V. L.; Shipayev, I. V.

    2017-10-01

    Сharacteristics of intense electron–ion beams emitted by a high-voltage (280 kV) electron accelerator with a pulse duration of 200 ps and current 5 kA are studied. The capture phenomena and the subsequent collective acceleration of multi charged ions of the cathode material by the electric field of the electron beam are observed. It is shown that the electron–ion beam diameter does not exceed 30 µm therein in the case of lighter ions, and the decay of the pinched beam occurs at a shorter distance from the cathode. It is established that the ions of the cathode material Tin+ captured by the electron beam are accelerated up to an energy of  ⩽10 MeV, and the ion fluence reaches 1017 ion cm‑2 in the pulse. These ions are effectively embedded into the lattice sites of the irradiated substrate (sapphire crystal), forming the luminescent areas of the micron scale.

  6. Generalized Huygens principle with pulsed-beam wavelets

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Thorkild [Seknion Inc., Boston, MA (United States); Kaiser, Gerald [Signals and Waves, Austin, TX (United States)], E-mail: thorkild.hansen@att.net, E-mail: kaiser@wavelets.com

    2009-11-27

    Huygens' geometric construction explaining wave motion has a well-known problem with unphysical back-propagation due to the spherical nature of the secondary wavelets. We solve this by analytically continuing the surface of integration. If the surface is a sphere S{sub R} of radius R, this is done by complexifying R to {alpha} = R + ia. The resulting complex sphere S{sub {alpha}} is shown to be equivalent to the real tangent disk bundle with base S{sub R} consisting of all disks with radius a tangent to S{sub R}. Huygens' secondary source points are thus replaced by disks, and his secondary wavelets by well-focused pulsed beams propagating outward. This solves the back-propagation problem. The generalized Huygens principle is a completeness relation for these pulsed-beam wavelets enabling a pulsed-beam representation of all radiation fields. Furthermore, this yields a natural and extremely efficient way to compute radiation fields numerically because all pulsed beams missing a given observer can be ignored with minimal error. Increasing the disk radius a sharpens the focus of the pulsed beams, which in turn raises the compression ratio of the representation.

  7. Production of gamma rays by pulsed laser beam Compton scattering off GeV-electrons using a non-planar four-mirror optical cavity

    CERN Document Server

    Akagi, T; Bonis, J; Chaikovska, I; Chiche, R; Cizeron, R; Cohen, M; Cormier, E; Cornebise, P; Delerue, N; Flaminio, R; Funahashi, S; Jehanno, D; Honda, Y; Labaye, F; Lacroix, M; Marie, R; Miyoshi, S; Nagata, S; Omori, T; Peinaud, Y; Pinard, L; Shimizu, H; Soskov, V; Takahashi, T; Tanaka, R; Terunuma, T; Urakawa, J; Variola, A; Zomer, F

    2011-01-01

    As part of the positron source R&D for future $e^+-e^-$ colliders and Compton based compact light sources, a high finesse non-planar four-mirror Fabry-Perot cavity has recently been installed at the ATF (KEK, Tsukuba, Japan). The first measurements of the gamma ray flux produced with a such cavity using a pulsed laser is presented here. We demonstrate the production of a flux of 2.7 $\\pm$ 0.2 gamma rays per bunch crossing ($\\sim3\\times10^6$ gammas per second) during the commissioning.

  8. 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.

  9. Generation of Nondiffracting Electron Bessel Beams

    Directory of Open Access Journals (Sweden)

    Vincenzo Grillo

    2014-01-01

    Full Text Available Almost 30 years ago, Durnin discovered that an optical beam with a transverse intensity profile in the form of a Bessel function of the first order is immune to the effects of diffraction. Unlike most laser beams, which spread upon propagation, the transverse distribution of these Bessel beams remains constant. Electrons also obey a wave equation (the Schrödinger equation, and therefore Bessel beams also exist for electron waves. We generate an electron Bessel beam by diffracting electrons from a nanoscale phase hologram. The hologram imposes a conical phase structure on the electron wave-packet spectrum, thus transforming it into a conical superposition of infinite plane waves, that is, a Bessel beam. We verify experimentally that these beams can propagate for 0.6 m without measurable spreading and can also reconstruct their intensity distributions after being partially obstructed by an obstacle. Finally, we show by numerical calculations that the performance of an electron microscope can be increased dramatically through use of these beams.

  10. Chiral specific electron vortex beam spectroscopy

    CERN Document Server

    Yuan, J; Babiker, M

    2013-01-01

    Electron vortex beams carry well-defined orbital angular momentum (OAM) about the propagation axis. Such beams are thus characterised by chirality features which make them potentially useful as probes of magnetic and other chiral materials. An analysis of the inelastic processes in which electron vortex beams interact with atoms and which involve OAM exchange is outlined, leading to the multipolar selection rules governing this chiral specific electron vortex beam spectroscopy. Our results show clearly that the selection rules are dependent on the dynamical state and location of the atoms involved. In the most favorable scenario, this form of electron spectroscopy can induce magnetic sublevel transitions which are commonly probed using circularly polarized photon beams.

  11. Surface microstructure and stress characteristics in pure zirconium after high current pulsed electron beam irradiation*%强流脉冲电子束作用下金属锆的微观结构与应力状态*

    Institute of Scientific and Technical Information of China (English)

    蔡杰; 季乐; 杨盛志; 张在强; 刘世超; 李艳; 王晓彤; 关庆丰

    2013-01-01

    High-current pulsed electron beam (HCPEB) technique was applied to irradiate the samples of pure zirconium. The microstruc-tures and defects of the irradiated surface are investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD results show that the high value of stress (GPa order) is introduced within the irradiated surface layer, while the formation of {0002}, {10¯12}, {11¯20} and {10¯13} textures are present after HCPEB irradiation. Mi-crostructure observations demonstrate that the surface craters are rarer, and almost no craters are present after multiple pulses HCPEB irradiation, which is evidently different from the case of other metal materials irradiated by HCPEB. Moreover, a large number of ultrafine grains are formed on the irradiated surface. Martensitic transformation occurs and severe plastic deformation is also induced due to the superfast melting and cooling processes. After one- pulse irradiation, the dislocations are the dominant defects, while the amount of twins is less. After five pulses, the dislocation density and the number of deformation twins increase evidently, whereas dense deformation twins are the central microstructures after ten-pulse irradiation, coupled with the appearance of secondary twins occasionally. The formation of these deformed structures results in a significant effect both on the evolution of surface textures and on grain refinement. It is suggested that HCPEB technique provides an impactful approach for hardening of zirconium and zirconium alloys.%  利用强流脉冲电子束(HCPEB)技术对金属纯锆进行表面处理,采用 X 射线衍射,扫描电子显微镜及透射电子显微镜详细分析了辐照诱发的表层微观结构和缺陷. X 射线分析结果表明, HCPEB 辐照后在材料表层诱发幅值为GPa 量级的压应力,并形成{0002},{10¯12},{11¯20}及{10¯13}织构.表层微观结构观察表明,

  12. High quality electron beams from a laser wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Wiggins, S M; Issac, R C; Welsh, G H; Brunetti, E; Shanks, R P; Anania, M P; Cipiccia, S; Manahan, G G; Aniculaesei, C; Ersfeld, B; Islam, M R; Burgess, R T L; Vieux, G; Jaroszynski, D A [SUPA, Department of Physics, University of Strathclyde, Glasgow (United Kingdom); Gillespie, W A [SUPA, Division of Electronic Engineering and Physics, University of Dundee, Dundee (United Kingdom); MacLeod, A M [School of Computing and Creative Technologies, University of Abertay Dundee, Dundee (United Kingdom); Van der Geer, S B; De Loos, M J, E-mail: m.wiggins@phys.strath.ac.u [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)

    2010-12-15

    High quality electron beams have been produced in a laser-plasma accelerator driven by femtosecond laser pulses with a peak power of 26 TW. Electrons are produced with an energy up to 150 MeV from the 2 mm gas jet accelerator and the measured rms relative energy spread is less than 1%. Shot-to-shot stability in the central energy is 3%. Pepper-pot measurements have shown that the normalized transverse emittance is {approx}1{pi} mm mrad while the beam charge is in the range 2-10 pC. The generation of high quality electron beams is understood from simulations accounting for beam loading of the wakefield accelerating structure. Experiments and self-consistent simulations indicate that the beam peak current is several kiloamperes. Efficient transportation of the beam through an undulator is simulated and progress is being made towards the realization of a compact, high peak brilliance free-electron laser operating in the vacuum ultraviolet and soft x-ray wavelength ranges.

  13. Spatially modulated laser pulses for printing electronics.

    Science.gov (United States)

    Auyeung, Raymond C Y; Kim, Heungsoo; Mathews, Scott; Piqué, Alberto

    2015-11-01

    The use of a digital micromirror device (DMD) in laser-induced forward transfer (LIFT) is reviewed. Combining this technique with high-viscosity donor ink (silver nanopaste) results in laser-printed features that are highly congruent in shape and size to the incident laser beam spatial profile. The DMD empowers LIFT to become a highly parallel, rapidly reconfigurable direct-write technology. By adapting half-toning techniques to the DMD bitmap image, the laser transfer threshold fluence for 10 μm features can be reduced using an edge-enhanced beam profile. The integration of LIFT with this beam-shaping technique allows the printing of complex large-area patterns with a single laser pulse.

  14. Attainment of Electron Beam Suitable for Medium Energy Electron Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Seletskiy, Sergei M. [Univ. of Rochester, NY (United States)

    2005-01-01

    Electron cooling of charged particle beams is a well-established technique at electron energies of up to 300 keV. However, up to the present time the advance of electron cooling to the MeV-range energies has remained a purely theoretical possibility. The electron cooling project at Fermilab has recently demonstrated the ¯rst cooling of 8.9 GeV/c antiprotons in the Recycler ring, and therefore, has proved the validity of the idea of relativistic electron cool- ing. The Recycler Electron Cooler (REC) is the key component of the Teva- tron Run II luminosity upgrade project. Its performance depends critically on the quality of electron beam. A stable electron beam of 4.3 MeV car- rying 0.5 A of DC current is required. The beam suitable for the Recycler Electron Cooler must have an angular spread not exceeding 200 ¹rad. The full-scale prototype of the REC was designed, built and tested at Fermilab in the Wideband laboratory to study the feasibility of attaining the high-quality electron beam. In this thesis I describe various aspects of development of the Fermilab electron cooling system, and the techniques used to obtain the electron beam suitable for the cooling process. In particular I emphasize those aspects of the work for which I was principally responsible.

  15. Electron Beam Lithography for nano-patterning

    DEFF Research Database (Denmark)

    Greibe, Tine; Anhøj, Thomas Aarøe; Khomtchenko, Elena;

    2014-01-01

    Electron beam lithography is a versatile tool for fabrication of nano-sized patterns. The patterns are generated by scanning a focused beam of high-energy electrons onto a substrate coated with a thin layer of electron-sensitive polymer (resist), i.e. by directly writing custom-made patterns...... in a polymer. Electron beam lithography is a suitable method for nano-sized production, research, or development of semiconductor components on a low-volume level. Here, we present electron beam lithography available at DTU Danchip. We expertize a JEOL 9500FZ with electrons accelerated to an energy of 100ke......V and focused to a beam spot size down to ~5nm. The electron beam can scan across the substrate with a speed of 100MHz and can write areas of 1mm x 1mm without stitching. In order to ensure high-precision patterning, the beam position on the substrate is controlled by a two-stage deflector system and substrates...

  16. High energy electron beam joining of ceramic components

    Energy Technology Data Exchange (ETDEWEB)

    Turman, B.N.; Glass, S.J.; Halbleib, J.A. [and others

    1997-07-01

    High strength, hermetic braze joints between ceramic components have been produced using high energy electron beams. With a penetration depth into a typical ceramic of {approximately}1 cm for a 10 MeV electron beam, this method provides the capability for rapid, transient brazing operations where temperature control of critical components is essential. The method deposits energy directly into a buried joint, allowing otherwise inaccessible interfaces to be brazed. Because of transient heating, higher thermal conductivity, lower heat capacity, and lower melting temperature of braze metals relative to the ceramic materials, a pulsed high power beam can melt a braze metal without producing excessive ceramic temperatures. We have demonstrated the feasibility of this process related to ceramic coupons as well as ceramic and glass tubes. The transient thermal response was predicted, using as input the energy absorption predicted from the coupled electron-photon transport analysis. The joining experiments were conducted with an RF Linac accelerator at 10-13 MV. The repetition rate of the pulsed beam was varied between 8 and 120 Hz, the average beam current was varied between 8 and 120 microamps, and the power was varied up to 1.5 kW. These beam parameters gave a beam power density between 0.2 to 2 kW/cm{sup 2}. The duration of the joining runs varied from 5 to 600 sec. Joining experiments have provided high strength between alumina - alumina and alumina - cermet joints in cylindrical geometry. These joints provided good hermetic seals. A series of tests was conducted to determine the minimum beam power and exposure time for producing, a hermetic seal.

  17. Modeling nitrogen plasmas produced by intense electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Angus, J. R.; Swanekamp, S. B.; Schumer, J. W.; Hinshelwood, D. D. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Mosher, D.; Ottinger, P. F. [Independent contractors for NRL through Engility, Inc., Alexandria, Virginia 22314 (United States)

    2016-05-15

    A new gas–chemistry model is presented to treat the breakdown of a nitrogen gas with pressures on the order of 1 Torr from intense electron beams with current densities on the order of 10 kA/cm{sup 2} and pulse durations on the order of 100 ns. For these parameter regimes, the gas transitions from a weakly ionized molecular state to a strongly ionized atomic state on the time scale of the beam pulse. The model is coupled to a 0D–circuit model using the rigid–beam approximation that can be driven by specifying the time and spatial profiles of the beam pulse. Simulation results are in good agreement with experimental measurements of the line–integrated electron density from experiments done using the Gamble II generator at the Naval Research Laboratory. It is found that the species are mostly in the ground and metastable states during the atomic phase, but that ionization proceeds predominantly through thermal ionization of optically allowed states with excitation energies close to the ionization limit.

  18. Single photon ionization time-of-flight mass spectrometry with a pulsed electron beam pumped excimer VUV lamp for on-line gas analysis: setup and first results on cigarette smoke and human breath.

    Science.gov (United States)

    Mühlberger, F; Streibel, T; Wieser, J; Ulrich, A; Zimmermann, R

    2005-11-15

    Single-photon ionization (SPI) using vacuum ultraviolet (VUV) light produced by an electron beam pumped rare gas excimer source has been coupled to a compact and mobile time-of-flight mass spectrometer (TOFMS). The novel device enables real-time on-line monitoring of organic trace substances in complex gaseous matrixes down to the ppb range. The pulsed VUV radiation of the light source is employed for SPI in the ion source of the TOFMS. Ion extraction is also carried out in a pulsed mode with a short time delay with respect to ionization. The experimental setup of the interface VUV light source/time-of-flight mass spectrometer is described, and the novel SPI-TOFMS system is characterized by means of standard calibration gases. Limits of detection down to 50 ppb for aliphatic and aromatic hydrocarbons were achieved. First on-line applications comprised real-time measurements of aromatic and aliphatic trace compounds in mainstream cigarette smoke, which represents a highly dynamic fluctuating gaseous matrix. Time resolution was sufficient to monitor the smoking process on a puff-by-puff resolved basis. Furthermore, human breath analysis has been carried out to detect differences in the breath of a smoker and a nonsmoker, respectively. Several well-known biomarkers for smoke could be identified in the smoker's breath. The possibility for even shorter measurement times while maintaining the achieved sensitivity makes this new device a promising tool for on-line analysis of organic trace compounds in process gases or biological systems.

  19. Effects of beam velocity and density on an ion-beam pulse moving in magnetized plasmas

    CERN Document Server

    Zhao, Xiao-ying; Zhao, Yong-tao; Qi, Xin; Yang, Lei

    2016-01-01

    The wakefield and stopping power of an ion-beam pulse moving in magnetized plasmas are investigated by particle-in-cell (PIC) simulations. The effects of beam velocity and density on the wake and stopping power are discussed. In the presence of magnetic field, it is found that beside the longitudinal conversed V-shaped wakes, the strong whistler wave are observed when low-density and low-velocity pulses moving in plasmas. The corresponding stopping powers are enhanced due to the drag of these whistler waves. As beam velocities increase, the whistler waves disappear, and only are conversed V-shape wakes observed. The corresponding stopping powers are reduced compared with these in isotropic plasmas. When high-density pulses transport in the magnetized plasmas, the whistler waves are greatly inhibited for low-velocity pulses and disappear for high-velocity pulses. Additionally, the magnetic field reduces the stopping powers for all high-density cases.

  20. Optimization of compton source performance through electron beam shaping

    Science.gov (United States)

    Malyzhenkov, Alexander; Yampolsky, Nikolai

    2017-03-01

    We investigate a novel scheme for significantly increasing the brightness of x-ray light sources based on inverse Compton scattering (ICS) - scattering laser pulses off relativistic electron beams. The brightness of ICS sources is limited by the electron beam quality, since electrons traveling at different angles, and/or having different energies, produce photons with different energies. Therefore, the spectral brightness of the source is defined by the 6D electron phase space shape and size, as well as laser beam parameters. The peak brightness of the ICS source can be maximized, then, if the electron phase space is transformed in a way such that all electrons scatter off the x-ray photons of same frequency in the same direction, arriving to the observer at the same time. We describe the x-ray photon beam quality through the Wigner function (6D photon phase space distribution), and derive it for the ICS source when the electron and laser rms matrices are arbitrary.

  1. Optimization of Compton Source Performance through Electron Beam Shaping

    Energy Technology Data Exchange (ETDEWEB)

    Malyzhenkov, Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Yampolsky, Nikolai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-26

    We investigate a novel scheme for significantly increasing the brightness of x-ray light sources based on inverse Compton scattering (ICS) - scattering laser pulses off relativistic electron beams. The brightness of ICS sources is limited by the electron beam quality since electrons traveling at different angles, and/or having different energies, produce photons with different energies. Therefore, the spectral brightness of the source is defined by the 6d electron phase space shape and size, as well as laser beam parameters. The peak brightness of the ICS source can be maximized then if the electron phase space is transformed in a way so that all electrons scatter off the x-ray photons of same frequency in the same direction, arriving to the observer at the same time. We describe the x-ray photon beam quality through the Wigner function (6d photon phase space distribution) and derive it for the ICS source when the electron and laser rms matrices are arbitrary.

  2. A Pulsed Laser and Molecular Beam Apparatus for Surface Studies

    Science.gov (United States)

    1985-03-01

    PRFCAMING ORCANIZATION REPORT NuMSWIS b MONITORING ORGANIZATION RPR :6P" _________ ______._ _ I0 0 1 I &PO*R.TR. o u 1 6NAEOF PERFORMING ORGANIZATION 5.OFFICE...with a second pulsed molecular beam, and the course of the reaction may be followed using several new pulsed surface analysis techniques under...available for electrical and manipulation feedthroughs, roughing and gas inlet lines, as well as special viewports (quartz or MgF 2) for the passage of UV

  3. A pulsed electron gun for the Plane Wave Transformer Linac

    CERN Document Server

    Mahadevan, S; Nandedkar, R V

    2003-01-01

    A pulsed diode electron gun delivering 500 mA current at 40 kV is described. The gun geometry is optimized using the Electron Trajectory Program EGUN at higher scaling factors by choosing the closest converging starting surface. The effect of an annular gap between cathode and focusing electrode on beam behaviour is compensated by using a suitable focusing electrode. The estimated perveance is 0.065 mu perv and the normalized emittance is within 5 pi mm mrad. The variation in current density at the cathode has been limited to within 10% across the face of the cathode. Salient features of the pulsed power supply and an insight of its interconnection with the gun are presented. The current measured at the Faraday cup is in agreement with the designed perveance.

  4. Pulsed electron source characterization with the modified three gradient method

    CERN Document Server

    Marghitu, S; Dinca, C; Marghitu, O

    2001-01-01

    Results from the Modified Three Gradient Method (MTGM), applied to a pulsed high intensity electron source, are presented. The MTGM makes possible the non-destructive determination of beam emittance in the space charge presence [1]. We apply the MTGM to an experimental system equipped with a Pierce convergent diode, working in pulse mode, and having a directly heated cathode as electron source. This choice was mainly motivated by the availability of an analytical characterization of this source type [2], as well as the extended use of the Pierce type sources in linear accelerators. The experimental data are processed with a numerical matching program, based on the K-V equation for an axially symmetric configuration [3], to determine the emittance and object cross-over position and diameter. The variation of these parameters is further investigated with respect to both electrical and constructive characteristics of the source: cathode heating current, extraction voltage, and cathode-anode distance.

  5. Construction of a pulsed MeV positron beam line

    Energy Technology Data Exchange (ETDEWEB)

    Masuno, Shin-ichi; Okada, Sohei; Kawasuso, Atsuo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    To develop a fast (1 MeV) and short pulsed (100 ps) positron beam which enables defect behavior analysis of bulk states of materials even at high temperatures where a usual positron source would melt, we have been performing design study and construction of the beam line in a three-year program since 1994. This report describes the components, design study results and experimental results of the completed parts until now. (author)

  6. Improvement of electron beam shape control in radiation processing

    Science.gov (United States)

    Strasser, A.; Fang, R.; Kuntz, F.

    1994-05-01

    The development of radiation processing using electron accelerators requires good control of the treatment parameters to improve the dosimetry quality. Especially, the analysis of the shape of the scanned electron beam that interacts with the product, is of prime necessity. A Multiwire Beam Shape Analyser (MBSA) has been developed by the AERIAL Laboratory in order to insure good monitoring of the scanning length and uniformity. This device consists of an aluminum beam-stop covered with a mesh of individually insulated stainless steel wires, placed under the scanning cone. The current generated by the impact of the electron beam on each wire is converted into voltage. After pulse shaping and multiplexing of the different channels, the beam profile can be displayed on an oscilloscope or on a PC screen. A prototype is now operating on an experimental irradiation plant based on a 2.5 MeV /300 W Van de Graaff electron accelerator. It allows almost continuous visualization of the beam profile (between two conveyor passes) and its response was compared to classical film dosimeters (Gafchromic, FWT 60.00). Considering FWHM and homogeneous treatment regions of the profiles, MBSA and the dosimeters give similar responses and variations remain lower than ± 12%. The acquisition of an electrical signal corresponding to the beam profile in air constitutes the original aspect of the MBSA and is in keeping with the general pattern of continuous control and automation of the irradiation processes. Hereafter, much work has to be done to adapt this device to an industrial use (higher energy, high power electron beams, non-destructive measurements…).

  7. Position and size of the electron beam in the high-energy electron beam ion trap

    CERN Document Server

    Utter, S B; López-Urrutia, J R C; Widmann, K

    1999-01-01

    In the last decade, many spectroscopic studies have been performed using the electron beam ion trap. Often these measurements rely on the electron beam as an effective slit, yet until now, no systematic study of the position and size of the electron beam under various operating conditions has been made. Here, we present a thorough study of the electron beam's position and size (and thus the electron density) as affected by various operating parameters, and give optimal parameter ranges for operating the device as a spectroscopic source. It is shown that the diameter is constant as the energy is varied, which is important for accurate cross-section measurements.

  8. Characterization and control of femtosecond electron and X-ray beams at free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, Christopher

    2012-11-15

    X-ray free-electron lasers (FELs) open up new frontiers in photon science, and in order to take full advantage of these unique accelerator-based light sources, the characterization and control of the femtosecond electron and X-ray beams is essential. Within this cumulative thesis, recent results achieved within the active research field of femtosecond electron and X-ray beams at FELs are reported.The basic principles of X-ray FELs are described, and concepts of longitudinal electron beam diagnostics with femtosecond accuracy are covered. Experimental results obtained with a transverse deflecting structure (TDS) and spectroscopy of coherent terahertz radiation are presented, and the suppression of coherent optical radiation effects, required for diagnostics utilizing a TDS, is demonstrated. Control of the longitudinal phase space by using multiple radio frequencies for longitudinal electron beam tailoring is presented, and a new technique of reversible electron beam heating with two TDSs is described. For the characterization of femtosecond X-ray pulses, a novel method based on dedicated longitudinal phase space diagnostics for electron beams is introduced, and recent measurements with a streaking technique using external terahertz fields are presented.

  9. Emittance growth from electron beam modulation

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz, M.

    2009-12-01

    In linac ring colliders like MeRHIC and eRHIC a modulation of the electron bunch can lead to a modulation of the beam beam tune shift and steering errors. These modulations can lead to emittance growth. This note presents simple formulas to estimate these effects which generalize some previous results.

  10. Profile monitors for wide multiplicity range electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Buonomo, B.; Mazzitelli, G.; Quintieri, L. [Laboratori Nazionali di Frascati LNF - INFN (Italy); Bulgheroni, A.; Cappellini, C.; Prest, M. [Univ. Insubria e INFN Sez-Milano (Italy); Foggetta, L. [Consorzio Interunivesitario per la Fisica Spaziale, CIFS (Italy); Mozzanica, A. [Milano Univ., INFN Pavia (Italy); Vallazza, E. [INFN Trieste Via Valerio, Trieste (Italy); Valente, P. [INFN Sez Roma (Italy)

    2005-07-01

    The DAFNE Beam Test Facility (BTF) provides electron and positron beams in a wide range of intensity, from single particle up to 10{sup 10} particles per pulse, and energy, from a few tens of MeV up to 800 MeV. The pulse time width can be 1 or 10 ns long, and the maximum repetition rate is 50 Hz. The large range of operation of the facility requires the implementation of different beam profile and multiplicity monitors. In the single particle operation mode, and up to a few 10{sup 3} particles/pulse, the beam spot profile and position are measured by a x-y scintillating fiber system with millimeter scale resolution and multi-anode photomultiplier tube readout. From a few tens up to 10{sup 6-7} particles per pulse, a silicon chamber made of two 9.5 x 9.5 cm{sup 2} wide 400 {mu}m thick silicon strip detectors organized in a x-y configuration with a pitch of 121 {mu}m has been developed. Once calibrated, the system can be used also as an intensity monitor. The description of the devices and the results obtained during the data taking periods of several experiments at the facility are presented. The system has showed very good performance operating with very high reliability in the energy range from a few tens of MeV up to 800 MeV, in single electron/positron mode as well as in the high intensity beam.

  11. 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.

  12. The Physics and Applications of High Brightness Electron Beams

    Science.gov (United States)

    Palumbo, Luigi; Rosenzweig, J.; Serafini, Luca

    2007-09-01

    Plenary sessions. RF deflector based sub-Ps beam diagnostics: application to FEL and advanced accelerators / D. Alesini. Production of fermtosecond pulses and micron beam spots for high brightness electron beam applications / S.G. Anderson ... [et al.]. Wakefields of sub-picosecond electron bunches / K.L.F. Bane. Diamond secondary emitter / I. Ben-Zvi ... [et al.]. Parametric optimization for an X-ray free electron laser with a laser wiggler / R. Bonifacio, N. Piovella and M.M. Cola. Needle cathodes for high-brightness beams / C.H. Boulware ... [et al.]. Non linear evolution of short pulses in FEL cascaded undulators and the FEL harmonic cascade / L. Giannessi and P. Musumeci. High brightness laser induced multi-meV electron/proton sources / D. Giulietti ... [et al.]. Emittance limitation of a conditioned beam in a strong focusing FEL undulator / Z. Huang, G. Stupakov and S. Reiche. Scaled models: space-charge dominated electron storage rings / R.A. Kishek ... [et al.]. High brightness beam applications: energy recovered linacs / G.A. Krafft. Maximizing brightness in photoinjectors / C. Limborg-Deprey and H. Tomizawa. Ultracold electron sources / O.J. Luiten ... [et al.]. Scaling laws of structure-based optical accelerators / A. Mizrahi, V. Karagodsky and L. Schächter. High brightness beams-applications to free-electron lasers / S. Reiche. Conception of photo-injectors for the CTF3 experiment / R. Roux. Superconducting RF photoinjectors: an overview / J. Sekutowicz. Status and perspectives of photo injector developments for high brightness beams / F. Stephan. Results from the UCLA/FNLP underdense plasma lens experiment / M.C. Thompson ... [et al.]. Medical application of multi-beam compton scattering monochromatic tunable hard X-ray source / M. Uesaka ... [et al.]. Design of a 2 kA, 30 fs RF-photoinjector for waterbag compression / S.B. Van Der Geer, O.J. Luiten and M.J. De Loos. Proposal for a high-brightness pulsed electron source / M. Zolotorev ... [et al

  13. Scaling laws for positron production in laser-electron-beam collisions

    Science.gov (United States)

    Blackburn, T. G.; Ilderton, A.; Murphy, C. D.; Marklund, M.

    2017-08-01

    Showers of γ rays and positrons are produced when a high-energy electron beam collides with a superintense laser pulse. We present scaling laws for the electron-beam energy loss, the γ -ray spectrum, and the positron yield and energy that are valid in the nonlinear, radiation-reaction-dominated regime. As an application we demonstrate that by employing the collision of a >GeV electron beam with a laser pulse of intensity >5 ×1021W cm-2 , today's high-intensity laser facilities are capable of producing O (104) positrons per shot via light-by-light scattering.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hansson, M., E-mail: martin.hansson@fysik.lth.se; 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. - Highlights: • Compact colliding pulse injection set-up used to produce low energy spread e-beams. • Beam charge controlled by rotating the polarization of injection pulse. • Peak energy controlled by point of collision to vary the acceleration length.

  15. 强流电子束入射叠靶能量沉积计算%Simulation on distributed target material impacted by high intensity current multi-pulse electron beam

    Institute of Scientific and Technical Information of China (English)

    胡林; 雷奕安; 朱隽

    2013-01-01

    The bremsstrahlung and energy deposition of multi-pulse high intensity relativistic electron beam injecting into multi-layer tantalum-graphite target are investigated.The energy deposition is calculated by Geant4 code,and the bremsstrahlung by fundamental radiation theory and Monte-Carlo method.The calculated results show the energy deposition in the hotspot of each layer decreases.The emittance and the radial distribution of the bremsstrahlung and electron beam are mostly affected by the tantalum layers.The low energy deposition rate and high heat capacity of graphite layers can improve the thermodynamic properties of the target.For a single pulse,at the tantalum-graphite thickness ratio 1 ∶ 1,the graphite can absorb all heat deposition of the neighboring tantalum layers,and the bremsstrahlung efficiency is 35.4 %.With 4 pulses,the ratio should be 1 ∶ 13,and the total bremsstrahlung efficiency decreases to 19.9 %.Considering the requirement of bremsstrahlung X-ray quantity and quality,the total thickness of tantalum should be 1.2 mm if the Ta-C thickness ratio is 1 ∶ 5,and 0.7 mm if the ratio is 1 ∶ 10.%计算了多脉冲相对论强流电子束入射钽-石墨叠靶的能量沉积和轫致辐射谱.能量沉积采用Geant4程序计算,轫致辐射谱根据基本的辐射理论和蒙特卡罗方法计算.结果显示,各层的热区能量沉积呈由大到小的递减分布,截面轫致辐射分布和电子束径向分布主要受钽层的影响.石墨层的低能量沉积率和高热容能改善叠靶的性能.对于单脉冲,钽-石墨层厚比为1∶1时,石墨能全部吸收相邻钽层的热沉积,轫致辐射效率为35.4%;4脉冲情况下,钽-石墨层厚比应为1∶13,总轫致辐射效率降到19.9%.考虑轫致辐射剂量和质量,钽-石墨两者的厚度比为1∶5时,钽层的总厚度应为1.2 mm;当钽-石墨层厚比为1:10时,钽层的总厚应降到0.7 mm.

  16. Energy Spread Reduction of Electron Beams Produced via Laser Wake

    Energy Technology Data Exchange (ETDEWEB)

    Pollock, Bradley Bolt [Univ. of California, San Diego, CA (United States)

    2012-01-01

    Laser wakefield acceleration of electrons holds great promise for producing ultra-compact stages of GeV scale, high quality electron beams for applications such as x-ray free electron lasers and high energy colliders. Ultra-high intensity laser pulses can be self-guided by relativistic plasma waves over tens of vacuum diffraction lengths, to give >1 GeV energy in cm-scale low density plasma using ionization-induced injection to inject charge into the wake at low densities. This thesis describes a series of experiments which investigates the physics of LWFA in the self-guided blowout regime. Beginning with high density gas jet experiments the scaling of the LWFA-produced electron beam energy with plasma electron density is found to be in excellent agreement with both phenomenological theory and with 3-D PIC simulations. It is also determined that self-trapping of background electrons into the wake exhibits a threshold as a function of the electron density, and at the densities required to produce electron beams with energies exceeding 1 GeV a different mechanism is required to trap charge into low density wakes. By introducing small concentrations of high-Z gas to the nominal He background the ionization-induced injection mechanism is enabled. Electron trapping is observed at densities as low as 1.3 x 1018 cm-3 in a gas cell target, and 1.45 GeV electrons are demonstrated for the first time from LWFA. This is currently the highest electron energy ever produced from LWFA. The ionization-induced trapping mechanism is also shown to generate quasi-continuous electron beam energies, which is undesirable for accelerator applications. By limiting the region over which ionization-induced trapping occurs, the energy spread of the electron beams can be controlled. The development of a novel two-stage gas cell target provides the capability to tailor the gas composition in the longitudinal direction, and confine the trapping process to occur only in a

  17. Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kaganovich, I.D.; Davidson, R.C.; Dorf, M.A.; Startsev, E.A.; Sefkow, A.B; Friedman, A.F.; Lee, E.P.

    2009-09-03

    Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating

  18. Ion beam processing of advanced electronic materials

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, N.W.; Marwick, A.D.; Roberto, J.B. (eds.) (California Univ., Berkeley, CA (USA); International Business Machines Corp., Yorktown Heights, NY (USA). Thomas J. Watson Research Center; Oak Ridge National Lab., TN (USA))

    1989-01-01

    This report contains research programs discussed at the materials research society symposia on ion beam processing of advanced electronic materials. Major topics include: shallow implantation and solid-phase epitaxy; damage effects; focused ion beams; MeV implantation; high-dose implantation; implantation in III-V materials and multilayers; and implantation in electronic materials. Individual projects are processed separately for the data bases. (CBS)

  19. Pulsed electron-nuclear-electron triple resonance spectroscopy

    Science.gov (United States)

    Thomann, Hans; Bernardo, Marcelino

    1990-05-01

    A new experimental technique, pulsed electron-nuclear-electron triple resonance spectroscopy, is demonstrated. It is based on a modification of the pulse sequence for electron-nuclear double resonance (ENDOR) in which two EPR and one NMR transition are irradiated. The irradiation of one EPR transition is detected via a second EPR transition. The nuclear hyperfine coupling, which separates these EPR transition frequencies, is the irradiated NMR transition. The major advantages of triple resonance spectroscopy include the ability to resolve overlapping nuclear resonances in the ENDOR spectrum and a more direct quantitative assignment of nuclear hyperfine and quadrupole couplings. The triple resonance experiment is an alternative to the recently proposed method of employing rapid magnetic field jumps between microwave pulses for generating hyperfine selective ENDOR spectra.

  20. Electron vortices: Beams with orbital angular momentum

    Science.gov (United States)

    Lloyd, S. M.; Babiker, M.; Thirunavukkarasu, G.; Yuan, J.

    2017-07-01

    The recent prediction and subsequent creation of electron vortex beams in a number of laboratories occurred after almost 20 years had elapsed since the recognition of the physical significance and potential for applications of the orbital angular momentum carried by optical vortex beams. A rapid growth in interest in electron vortex beams followed, with swift theoretical and experimental developments. Much of the rapid progress can be attributed in part to the clear similarities between electron optics and photonics arising from the functional equivalence between the Helmholtz equations governing the free-space propagation of optical beams and the time-independent Schrödinger equation governing freely propagating electron vortex beams. There are, however, key differences in the properties of the two kinds of vortex beams. This review is primarily concerned with the electron type, with specific emphasis on the distinguishing vortex features: notably the spin, electric charge, current and magnetic moment, the spatial distribution, and the associated electric and magnetic fields. The physical consequences and potential applications of such properties are pointed out and analyzed, including nanoparticle manipulation and the mechanisms of orbital angular momentum transfer in the electron vortex interaction with matter.

  1. 强流脉冲电子束作用下20钢的微观结构状态%The Microstructures in 0.20%C Carbon Steel Induced by High-Current Pulsed Electron Beam

    Institute of Scientific and Technical Information of China (English)

    李艳; 蔡杰; 邹阳; 万明珍; 关庆丰

    2011-01-01

    In order to investigate superfast deformation behavior of metal, annealed 0.20%C carbon steel was irradiated with high-current pulsed electron beam (HCPEB). The microstructures of irradiated samples were investigated by using X-ray diffraction (XRD), optical microscopy and transmission electron microscopy (TEM). The experimental results showed that stress of about 1 GPa order was introduced in the irradiated surface layer, which led to severe plastic deformation on the irradiated surface. Both of the complicated configurations of tangle dislocations and dislocation cells were formed within the sublayer. Simultaneously, dislocation loops companied with the dislocations configurations were also produced. In the situation of multi-pulses, characterization by TEM also revealed that the sublayer consisting of some region with the glassy and nanocrystalline structure. It is suggested that the high-level stress and strain rate induced by HCPEB irradiation could cause the shifting of whole atomic planes synchronously. This is the more possible mechanism of the formation of the glassy and nanocrystalline structure.%为了研究金属材料的超快变形行为,利用强流脉冲电子束(HCPEB)装置对20钢进行轰击,采用X射线衍射、光学显微镜及透射电镜等技术分析了受轰击样品的变形组织与结构。实验结果表明,强流脉冲电子束能够在材料表层诱发幅值为1 GPa量级的应力,快速的加热和冷却过程在近表层诱发了强烈的塑性变形,并在材料表层内形成了复杂的位错缠结结构和位错胞结构,同时还伴随位错圈等空位簇缺陷的形成,多次轰击导致局部区域形成纳米和非晶结构。HCPBE轰击诱发的幅值极大的应力和极高的应变速率而导致的整个原子平面的位移可能是非晶结构形成的

  2. Generate Uniform Transverse Distributed Electron Beam along a Beam Line

    CERN Document Server

    Jiao, Y

    2015-01-01

    It has been reported that transverse distribution shaping can help to further enhance the energy extraction efficiency in a terawatt, tapered X-ray free-electron laser. Thus, methods of creating and keeping almost uniform transverse distributed (UTD) beam within undulators are required. This study shows that a UTD electron beam can be generated within evenly distributed drift sections where undulators can be placed, by means of octupoles and particular optics. A concrete design is presented, and numerical simulations are done to verify the proposed method.

  3. Control and manipulation of electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Piot, Philippe; /NICADD, DeKalb /Northern Illinois U. /Fermilab

    2008-09-01

    The concepts of the advanced accelerators and light source rely on the production of bright electron beams. The rms areas of the beam phase space often need to be tailored to the specific applications. Furthermore, a new class of the forefront research calls for detailed specific distribution such as the particle density in the time coordinate. Several groups are tackling these various challenges and in this report we attempt to give a review of the state-of-the-art of the control and manipulation of the electron beams.

  4. Self-effect in expanding electron beam plasma

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M

    1999-05-07

    An analytical model of plasma flow from a metal plate hit by an intense, pulsed, electron beam aims to bridge the gap between radiation-hydrodynamics simulations and experiments, and to quantify the self-effect of the electron beam penetrating the flow. Does the flow disrupt the tight focus of the initial electron bunch, or later pulses in a train? This work aims to model the spatial distribution of plasma speed, density, degree of ionization, and magnetization to inquire. The initial solid density, several eV plasma expands to 1 cm and 10{sup {minus}4} relative density by 2 {micro}s, beyond which numerical simulations are imprecise. Yet, a Faraday cup detector at the ETA-II facility is at 25 cm from the target and observes the flow after 50 {micro}s. The model helps bridge this gap. The expansion of the target plasma into vacuum is so rapid that the ionized portion of the flow departs from local thermodynamic equilibrium. When the temperature (in eV) in a parcel of fluid drops below V{sub i} x [(2{gamma} - 2)/(5{gamma} + 17)], where V{sub i} is the ionization potential of the target metal (7.8 eV for tantalum), and {gamma} is the ratio of specific heats (5/3 for atoms), then the fractional ionization and electron temperature in that parcel remain fixed during subsequent expansion. The freezing temperature as defined here is V{sub i}/19. The balance between the self-pinching force and the space charge repulsion of an electron beam changes on penetrating a flow: (i) the target plasma cancels the space-charge field, (ii) internal eddy currents arise to counter the magnetization of relativistic electrons, and (iii) electron beam heating alters the flow magnetization by changing the plasma density gradient and the magnitude of the conductivity.

  5. Profile Monitors for Wide Multiplicity Range Electron Beams

    CERN Document Server

    Buonomo, B; Quintieri, L

    2005-01-01

    The DAFNE Beam Test Facility (BTF) provides electron and positron beams in a wide range of intensity, from single particle up to 1010 particles per pulse, and energy, from a few tens of MeV up to 800 MeV. The pulse time width can be adjusted between 1 and 10 ns and the maximum repetition rate is 50 Hz. The large range of operation of the facility requires the implementation of different beam profile and multiplicity monitors. In the single particle operation mode the beam spot profile and position are measured by a x-y scintillating fiber system with millimetric resolution and multi-anode PMT readout. From a few tens up to 106-107 particles per pulse, a silicon chamber made of two 9.5x9.5 cm2 wide 400μm thick silicon strip detectors organized in a x-y configuration with a pitch of 121μm has been developed. Once calibrated, the system can be used also as an intensity monitor. The description of the devices and the results obtained during the data taking periods of several experiments at the...

  6. Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Umeda, N., E-mail: umeda.naotaka@jaea.go.jp; Kojima, A.; Kashiwagi, M.; Tobari, H.; Hiratsuka, J.; Watanabe, K.; Dairaku, M.; Yamanaka, H.; Hanada, M. [Japan Atomic Energy Agency, 801-1 Mukouyama, Naka-shi, Ibaraki 311-0193 Japan (Japan)

    2015-04-08

    R and D of high power density negative ion beam acceleration has been carried out at MeV test facility in JAEA to realize ITER neutral beam accelerator. The main target is H{sup −} ion beam acceleration up to 1 MeV with 200 A/m{sup 2} for 60 s whose pulse length is the present facility limit. For long pulse acceleration at high power density, new extraction grid (EXG) has been developed with high cooling capability, which electron suppression magnet is placed under cooling channel similar to ITER. In addition, aperture size of electron suppression grid (ESG) is enlarged from 14 mm to 16 mm to reduce direct interception on the ESG and emission of secondary electron which leads to high heat load on the upstream acceleration grid. By enlarging ESG aperture, beam current increased 10 % at high current beam and total acceleration grid heat load reduced from 13 % to 10 % of input power at long pulse beam. In addition, heat load by back stream positive ion into the EXG is measured for the first time and is estimated as 0.3 % of beam power, while heat load by back stream ion into the source chamber is estimated as 3.5 ~ 4.0 % of beam power. Beam acceleration up to 60 s which is the facility limit, has achieved at 683 keV, 100 A/m{sup 2} of negative ion beam, whose energy density increases two orders of magnitude since 2011.

  7. Pulsed rotating supersonic source used with merged molecular beams

    CERN Document Server

    Sheffield, L; Krasovitskiy, V; Rathnayaka, K D D; Lyuksyutov, I F; Herschbach, D R

    2012-01-01

    We describe a pulsed rotating supersonic beam source, evolved from an ancestral device [M. Gupta and D. Herschbach, J. Phys. Chem. A 105, 1626 (2001)]. The beam emerges from a nozzle near the tip of a hollow rotor which can be spun at high-speed to shift the molecular velocity distribution downward or upward over a wide range. Here we consider mostly the slowing mode. Introducing a pulsed gas inlet system, cryocooling, and a shutter gate eliminated the main handicap of the original device, in which continuous gas flow imposed high background pressure. The new version provides intense pulses, of duration 0.1-0.6 ms (depending on rotor speed) and containing ~10^12 molecules at lab speeds as low as 35 m/s and ~ 10^15 molecules at 400 m/s. Beams of any molecule available as a gas can be slowed (or speeded); e.g., we have produced slow and fast beams of rare gases, O2, Cl2, NO2, NH3, and SF6. For collision experiments, the ability to scan the beam speed by merely adjusting the rotor is especially advantageous when...

  8. Nonlinear images of scatterers in chirped pulsed laser beams

    Institute of Scientific and Technical Information of China (English)

    Hu Yong-Hua; Wang You-Wen; Wen Shuang-Chun; Fan Dian-Yuan

    2010-01-01

    The bandwidth and the duration of incident pulsed beam are proved to play important roles in modifying the nonlinear image of amplitude-type scatterer.It is found that the initially positive chirp-type bandwidth can suppress the nonlinear image,while the negative one can enhance it,and that both effects are inversely proportional to the incident pulse duration.Numerical simulations further demonstrate that the location of nonlinear image is at the conjugate plane of the scatterer and that,for negatively pre-chirped pulsed beam,the nonlinear image peak intensity can be higher than that in the corresponding monochromatic case under certain conditions.Moreover the effect of group velocity dispersion on nonlinear image is found to be similar to that of chirp-type bandwidth.

  9. Computational and experimental studies of the beam-target interaction for high-dose, multi-pulse radiography

    Energy Technology Data Exchange (ETDEWEB)

    DeVolder, B.G.; Kwan, T.J.T.; Fulton, R.D.; Moir, D.C.; Oro, D.M.; Prono, D.S. [Los Alamos National Lab., NM (United States)

    1997-12-31

    The conversion of an intense relativistic electron beam into x-rays for radiographic imaging is achieved through the bremsstrahlung process of electrons in a target of optimal thickness. To achieve desirable resolution for thick objects, an extremely high-brightness electron beam is used, and a significant amount of beam energy can be deposited in a small area of the target. Vaporization of the target material and expansion of the resultant plasma can occur. In a multi-pulsing design, which will resolve dynamic behavior of the object, the expanding plasma can have an effect on the quality of subsequent electron beam pulses. The evolution of the plasma was investigated using a two-dimensional Eulerian magnetohydrodynamic code. The driving, or initial, condition for the plasma is the energy deposited in the target by the electron beam. Because the spatial and temporal beam energy deposition profiles can affect the plasma dynamics several deposition models were tested. Experiments at Los Alamos` Integrated Test Stand (ITS) have characterized the expanding plasma for several target materials using a 5.25-MeV, 3.8-kA, 4-mm-diameter electron beam. Measurements such as axial expansion velocity helped benchmark the code and validate the deposition modes. Using the models that showed best agreement with the ITS experiments, calculations were done for a planned upgraded facility (20-MeV, 4.5-kA beam, spot size reduced by 1/4) to evaluate a multi-pulsing scheme in which the beam is moved to clean sections of the target for subsequent pulses. To minimize electron beam steering, means of confining the target plasma were also explored.

  10. Surface microstructure and stress characteristics in pure titanium after high-current pulsed electron beam irradiation%强流脉冲电子束诱发纯钛表面的微观结构及应力状态

    Institute of Scientific and Technical Information of China (English)

    李艳; 蔡杰; 吕鹏; 邹阳; 万明珍; 彭冬晋; 顾倩倩; 关庆丰

    2012-01-01

    利用强流脉冲电子束(HCPEB)装置对金属纯钛进行轰击,采用X射线衍射,扫描电子显微镜及透射电子显微镜技术详细分析了轰击样品表层的结构和缺陷.X射线衍射分析表明,HCPEB能够在材料表层诱发幅值为GPa量级的压应力,并在(100),(102)和(103)晶面出现择优取向.表层微观结构的观察表明:HCPEB轰击后材料表层发生了马氏体相变,形成了大量的片状马氏体组织;此外,HCPEB轰击还在辐照表面诱发了强烈的塑性变形,一次轰击后,晶粒内部的塑性变形以(100)晶面的位错滑移为主,位错密度显著提高;多次轰击后,样品变形结构发生变化,变形孪晶的数量明显增多.这些变形微结构不仅影响表层的织构演化行为,而且还能细化晶粒,进而提高材料表面硬度,为HCPEB技术进行纯钛表面强化提供了一条有效的途径.%The specimens of polycrystalline pure titanium are irradiated by high-current pulsed electron beam (HCPEB). Surface microstruc- tures and defects induced by HCPEB irradiation are investigated by using X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy technique. The XRD results show that the high value of stress (GPa order) is introduced into the irradiated surface layer, and the characteristics of preferential orientations (100), (102) and (103) are present after HCPEB treatment. The surface microstructure observations indicate that martensitic transformation occurs in the irradiated surface and a large number of plate martensite structures are formed in the irradiated surface. Moreover, strong plastic deformation is triggered by HCPEB treatment. After one pulse, (100) type slip bands are formed in the interior of grain, which leads to the increase of dislocation density. After multi- pulses, deformation microstructures change significantly, and the number of deformation twins increases evidently

  11. Ion optics of RHIC electron beam ion source

    Energy Technology Data Exchange (ETDEWEB)

    Pikin, A.; Alessi, J.; Beebe, E.; Kponou, A.; Okamura, M.; Raparia, D.; Ritter, J.; Tan, Y. [Brookhaven National Laboratory, Upton, New York 11973 (United States); Kuznetsov, G. [Budker Institute of Nuclear Physics, Novosibirsk 630090 (Russian Federation)

    2012-02-15

    RHIC electron beam ion source has been commissioned to operate as a versatile ion source on RHIC injection facility supplying ion species from He to Au for Booster. Except for light gaseous elements RHIC EBIS employs ion injection from several external primary ion sources. With electrostatic optics fast switching from one ion species to another can be done on a pulse to pulse mode. The design of an ion optical structure and the results of simulations for different ion species are presented. In the choice of optical elements special attention was paid to spherical aberrations for high-current space charge dominated ion beams. The combination of a gridded lens and a magnet lens in LEBT provides flexibility of optical control for a wide range of ion species to satisfy acceptance parameters of RFQ. The results of ion transmission measurements are presented.

  12. Electron beam direct write: shaped beam overcomes resolution concerns

    Science.gov (United States)

    Stolberg, Ines; Pain, Laurent; Kretz, Johannes; Boettcher, Monika; Doering, Hans-Joachim; Gramss, Juergen; Hahmann, Peter

    2007-02-01

    In semiconductor industry time to market is one of the key success factors. Therefore fast prototyping and low-volume production will become extremely important for developing process technologies that are well ahead of the current technological level. Electron Beam Lithography has been launched for industrial use as a direct write technology for these types of applications. However, limited throughput rates and high tool complexity have been seen as the major concerns restricting the industrial use of this technology. Nowadays this begins to change. Variable Shaped Beam (VSB) writers have been established in Electron Beam Direct Write (EBDW) on Si or GaAs. In the paper semiconductor industry requirements to EBDW will be outlined. Behind this background the Vistec SB3050 lithography system will be reviewed. The achieved resolution enhancement of the VSB system down to the 22nm node exposure capability will be discussed in detail; application examples will be given. Combining EBDW in a Mix and Match technology with optical lithography is one way to utilize the high flexibility advantage of this technology and to overcome existing throughput concerns. However, to some extend a common Single Electron Beam Technology (SBT) will always be limited in throughput. Therefore Vistec's approach of a system that is based on the massive parallelisation of beams (MBT), which was initially pursued in a European Project, will also be discussed.

  13. Compression of Electron Pulses for Femtosecond Electron Diffraction

    Science.gov (United States)

    Zandi, Omid; Yang, Jie; Centurion, Martin

    2014-05-01

    Our goal is to improve the temporal resolution in electron diffraction experiments to 100 fs by compressing the electron pulses using a time-varying electric field. The compressed pulse can be used for a better understanding of the dynamics of molecules under study. A bunch of 3 million electrons is generated at a photocathode by femtosecond UV laser pulses and accelerated to 100 keV in a static electric field. Then, the longitudinal component of the electric field of a microwave cavity is employed to compress the bunch. The cavity's frequency and phase are accurately tuned in such a way that the electric field is parallel to the bunch motion at its arrival and antiparallel to it at its exit. Compression in the transverse directions is done by magnetic lenses. Simulations have been done to predict the bunch profile at different positions and times by General Particle Tracer code. A streak camera has been built to measure the duration of the pulses. It uses the electric field of a discharging parallel plate capacitor to rotate the bunch so that angular spreading of the bunch is proportional to its duration. The capacitor is discharged by a laser pulse incident on a photo switch.

  14. Beam Instrumentation for the Single Electron DAFNE Beam Test Facility

    CERN Document Server

    Mazzitelli, G; Valente, P; Vescovi, M

    2003-01-01

    The DAΦNE Beam Test Facility (BTF) has been successfully commissioned in February 2002, and started operation in November of the same year. Although the BTF is a beam transfer line optimized for single particle production, mainly for high energy detectors calibration, it can provide electrons and positrons in a wide range of multiplicity: between 1-1010, with energies from a few tens of MeV up to 800 MeV. The large multiplicity range requires many different diagnostic devices, from high-energy calorimeters and ionization/fluorescence chambers in the few particles range, to standard beam diagnostics systems. The schemes of operation, the commissioning results, as well as the beam diagnostics are presented.

  15. VELOCITY BUNCHING OF HIGH-BRIGHTNESS ELECTRON BEAMS

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S G; Musumeci, P; Rosenzweig, J B; Brown, W J; England, R J; Ferrario, M; Jacob, J S; Thompson, M C; Travish, G; Tremaine, A M; Yoder, R

    2004-10-15

    Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS) experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly in ICS experiments

  16. Velocity bunching of high-brightness electron beams

    Directory of Open Access Journals (Sweden)

    S. G. Anderson

    2005-01-01

    Full Text Available Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly

  17. Holographic generation of highly twisted electron beams

    CERN Document Server

    Grillo, Vincenzo; Mafakheri, Erfan; Frabboni, Stefano; Karimi, Ebrahim; Boyd, Robert W

    2014-01-01

    Free electrons can possess an intrinsic orbital angular momentum, similar to those in an electron cloud, upon free-space propagation. The wavefront corresponding to the electron's wavefunction forms a helical structure with a number of twists given by the \\emph{angular speed}. Beams with a high number of twists are of particular interest because they carry a high magnetic moment about the propagation axis. Among several different techniques, electron holography seems to be a promising approach to shape a \\emph{conventional} electron beam into a helical form with large values of angular momentum. Here, we propose and manufacture a nano-fabricated phase hologram for generating a beam of this kind with an orbital angular momentum up to 200$\\hbar$. Based on a novel technique the value of orbital angular momentum of the generated beam are measured, then compared with simulations. Our work, apart from the technological achievements, may lead to a way of generating electron beams with a high quanta of magnetic momen...

  18. Feasibility of ceramic joining with high energy electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Turman, B.N.; Glass, S.J.; Halbleib, J.A.; Helmich, D.R.; Loehman, R.E. [Sandia National Labs., Albuquerque, NM (United States); Clifford, J.R. [Titan Corp., Albuquerque, NM (United States)

    1995-01-01

    Joining structural ceramics is possible using high melting point metals such as Mo and Pt that are heated with a high energy electron beam, with the potential for producing joints with high temperature capability. A 10 MeV electron beam can penetrate through 1 cm of ceramic, offering the possibility of buried interface joining. Because of transient heating and the lower heat capacity of the metal relative to the ceramic, a pulsed high power beam has the potential for melting the metal without decomposing or melting the adjacent ceramic. The authors have demonstrated the feasibility of the process with a series of 10 MeV, 1 kW electron beam experiments. Shear strengths up to 28 NTa have been measured for Si{sub 3}N{sub 4}-Mo-Si{sub 3}N{sub 4}. These modest strengths are due to beam non-uniformity and the limited area of bonding. The bonding mechanism appears to be a thin silicide reaction layer. Si{sub 3}N{sub 4}-Si{sub 3}N{sub 4} joints with no metal layer were also produced, apparently bonded an yttrium apatite grain boundary phase.

  19. Generating Picosecond X-Ray Pulses with Beam Manipulation in Synchrotron Light Sources

    CERN Document Server

    Guo, Weiming; Harkay, Katherine C; Sajaev, Vadim; Yang Bing Xin

    2005-01-01

    The length of x-ray pulses generated by storage ring light sources is usually tens of picoseconds. For example, the value is 40 ps rms at the Advanced Photon Source (APS). Methods of x-ray pulse compression are of great interest at the APS. One possible method, per Zholents et al., is to tilt the electron bunch with deflecting rf cavities.* Alternately, we found that the electron bunch can develop a tilt after application of a vertical kick in the presence of nonzero chromaticity. After slicing, the x-ray pulse length is determined by the tilt angle and the vertical beam size. In principal, sub-picosecond pulses can be obtained at APS. To date we have observed 6 ps rms visible light pulses with a streak camera. Efforts are underway to attempt further compression of the x-ray pulse and to increase the brilliance. This method can be easily applied to any storage ring light sources to generate x-ray pulses up to two orders of magnitude shorter than the electron bunch length. In this paper, we will present the th...

  20. Beam dynamics studies and parametric characterization of a standing wave electron linac

    Science.gov (United States)

    Dash, R.; Mondal, J.; Sharma, A.; Mittal, K. C.

    2013-07-01

    This paper presents the results of electron beam tracking simulations for a 30 MeV standing wave electron linac at Electron Beam Centre Kharghar, Navi Mumbai, India. For the pulsed mode operation of the present linac preferential operation parameters have been determined from the results of beam dynamics studies. This electron accelerator is a general purpose facility for generation of Bremsstrahlung X-rays and neutron scattering experiments. This electron accelerator-based experimental neutron facility will be used for measurement of neutron cross-section (n,γ), (n, xn) and (n, f) reactions at different energies for various materials and material irradiation studies.

  1. Electron Beam Dynamics in 4GLS

    CERN Document Server

    Williams, P H; Muratori, B D; Owen, H L; Smith, S L

    2007-01-01

    Studies of the electron beam dynamics for the 4GLS design are presented. 4GLS will provide three different electron bunch trains to a variety of user synchrotron sources. The 1 kHz XUV-FEL and 100 mA High Average Current branches share a common 540 MeV linac, whilst the 13 MHz IR-FEL must be well-synchronised to them. An overview of the injector designs, electron transport, and energy recovery is given, including ongoing studies of coherent synchrotron radiation, beam break-up and wakefields. This work is being pursued for the forthcoming Technical Design Report due in 2008.

  2. Green coffee decontamination by electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Nemtanu, Monica R. [National Institute for Lasers, Plasma and Radiation Physics, Department of Electron Accelerators, 409 Atomistilor St., P.O. Box MG-36, RO 76 900, Bucharest-Magurele (Romania)]. E-mail: monica@infim.ro; Brasoveanu, Mirela [National Institute for Lasers, Plasma and Radiation Physics, Department of Electron Accelerators, 409 Atomistilor St., P.O. Box MG-36, RO 76 900, Bucharest-Magurele (Romania); Grecu, Maria Nicoleta [National Institute for Materials Physics, RO 77 125, Bucharest-Magurele (Romania); Minea, R. [National Institute for Lasers, Plasma and Radiation Physics, Department of Electron Accelerators, 409 Atomistilor St., P.O. Box MG-36, RO 76 900, Bucharest-Magurele (Romania)

    2005-10-15

    Microbiological load of green coffee is a real problem considering that it is extremely sensitive to contamination. Irradiation is a decontamination method for a lot of foodstuffs, being a feasible, very effective and environment friendly one. Beans and ground green coffee were irradiated with electron beams up to 40 kGy. Microbial load, rheological behavior, electron paramagnetic resonance (EPR) and visible spectroscopy were carried out. The results show that electron beam irradiation of green coffee could decontaminate it without severe changes in its properties.

  3. Green coffee decontamination by electron beam irradiation

    Science.gov (United States)

    Nemtanu, Monica R.; Brasoveanu, Mirela; Grecu, Maria Nicoleta; Minea, R.

    2005-10-01

    Microbiological load of green coffee is a real problem considering that it is extremely sensitive to contamination. Irradiation is a decontamination method for a lot of foodstuffs, being a feasible, very effective and environment friendly one. Beans and ground green coffee were irradiated with electron beams up to 40 kGy. Microbial load, rheological behavior, electron paramagnetic resonance (EPR) and visible spectroscopy were carried out. The results show that electron beam irradiation of green coffee could decontaminate it without severe changes in its properties.

  4. A simple electron-beam lithography system

    DEFF Research Database (Denmark)

    Mølhave, Kristian; Madsen, Dorte Nørgaard; Bøggild, Peter

    2005-01-01

    A large number of applications of electron-beam lithography (EBL) systems in nanotechnology have been demonstrated in recent years. In this paper we present a simple and general-purpose EBL system constructed by insertion of an electrostatic deflector plate system at the electron-beam exit...... of the column of a scanning electron microscope (SEM). The system can easily be mounted on most standard SEM systems. The tested setup allows an area of up to about 50 x 50 pm to be scanned, if the upper limit for acceptable reduction of the SEM resolution is set to 10 run. We demonstrate how the EBL system can...

  5. Ultrafast transmission electron microscopy using a laser-driven field emitter: femtosecond resolution with a high coherence electron beam

    CERN Document Server

    Feist, Armin; da Silva, Nara Rubiano; Danz, Thomas; Möller, Marcel; Priebe, Katharina E; Domröse, Till; Gatzmann, J Gregor; Rost, Stefan; Schauss, Jakob; Strauch, Stefanie; Bormann, Reiner; Sivis, Murat; Schäfer, Sascha; Ropers, Claus

    2016-01-01

    We present the development of the first ultrafast transmission electron microscope (UTEM) driven by localized photoemission from a field emitter cathode. We describe the implementation of the instrument, the photoemitter concept and the quantitative electron beam parameters achieved. Establishing a new source for ultrafast TEM, the G\\"ottingen UTEM employs nano-localized linear photoemission from a Schottky emitter, which enables operation with freely tunable temporal structure, from continuous wave to femtosecond pulsed mode. Using this emission mechanism, we achieve record pulse properties in ultrafast electron microscopy of 9 {\\AA} focused beam diameter, 200 fs pulse duration and 0.6 eV energy width. We illustrate the possibility to conduct ultrafast imaging, diffraction, holography and spectroscopy with this instrument and also discuss opportunities to harness quantum coherent interactions between intense laser fields and free electron beams.

  6. Electron beam damage in oxides: a review.

    Science.gov (United States)

    Jiang, Nan

    2016-01-01

    This review summarizes a variety of beam damage phenomena relating to oxides in (scanning) transmission electron microscopes, and underlines the shortcomings of currently popular mechanisms. These phenomena include mass loss, valence state reduction, phase decomposition, precipitation, gas bubble formation, phase transformation, amorphization and crystallization. Moreover, beam damage is also dependent on specimen thickness, specimen orientation, beam voltage, beam current density and beam size. This article incorporates all of these damage phenomena and experimental dependences into a general description, interpreted by a unified mechanism of damage by induced electric field. The induced electric field is produced by positive charges, which are generated from excitation and ionization. The distribution of the induced electric fields inside a specimen is beam-illumination- and specimen-shape- dependent, and associated with the experimental dependence of beam damage. Broadly speaking, the mechanism operates differently in two types of material. In type I, damage increases the resistivity of the irradiated materials, and is thus divergent, resulting in phase separation. In type II, damage reduces the resistivity of the irradiated materials, and is thus convergent, resulting in phase transformation. Damage by this mechanism is dependent on electron-beam current density. The two experimental thresholds are current density and irradiation time. The mechanism comes into effect when these thresholds are exceeded, below which the conventional mechanisms of knock-on and radiolysis still dominate.

  7. Ribbon electron beam formation by a forevacuum plasma electron source

    Energy Technology Data Exchange (ETDEWEB)

    Klimov, A. S., E-mail: klimov@main.tusur.ru; Burdovitsin, V. A. [Tomsk State University of Control System and Radioelectronics (Russian Federation); Grishkov, A. A. [SB RAS, Institute of High Current Electronics (Russian Federation); Oks, E. M.; Zenin, A. A.; Yushkov, Yu. G. [Tomsk State University of Control System and Radioelectronics (Russian Federation)

    2016-01-15

    Results of the numerical analysis and experimental research on ribbon electron beam generation based on hollow cathode discharge at forevacuum gas pressure are presented. Geometry of the accelerating gap has modified. It lets us focus the ribbon electron beam and to transport it on a distance of several tens of centimeters in the absence of an axial magnetic field. The results of numerical simulations are confirmed by the experiment.

  8. Shot-noise-limited spin measurements in a pulsed molecular beam

    CERN Document Server

    Kirilov, E; Doyle, J M; Gabrielse, G; Gurevich, Y V; Hess, P W; Hutzler, N R; O'Leary, B R; Petrik, E; Spaun, B; Vutha, A C; DeMille, D

    2013-01-01

    Heavy diatomic molecules have been identified as good candidates for use in electron electric dipole moment (eEDM) searches. Suitable molecular species can be produced in pulsed beams, but with a total flux and/or temporal evolution that varies significantly from pulse to pulse. These variations can degrade the experimental sensitivity to changes in spin precession phase of an electri- cally polarized state, which is the observable of interest for an eEDM measurement. We present two methods for measurement of the phase that provide immunity to beam temporal variations, and make it possible to reach shot-noise-limited sensitivity. Each method employs rapid projection of the spin state onto both components of an orthonormal basis. We demonstrate both methods using the eEDM-sensitive H state of thorium monoxide (ThO), and use one of them to measure the magnetic moment of this state with increased accuracy relative to previous determinations.

  9. A transparent vacuum window for high-intensity pulsed beams

    CERN Document Server

    Monteil, M; Veness, R

    2011-01-01

    The HiRadMat (High-Radiation to Materials) facility Ill will allow testing of accelerator components, in particular those of the Large Hadron Collider (LHC) at CERN, under the impact of high-intensity pulsed beams. To reach this intensity range, the beam will be focused on a focal point where the target to be tested is located. A 60 mm aperture vacuum window will separate the vacuum of the beam line which is kept under high vacuum 10(-8) mbar, from the test area which is at atmospheric pressure. This window has to resist collapse due to beam passage. The high-intensity of the beam means that typical materials used for standard vacuum windows (such as stainless steel, aluminium and titanium alloy) cannot endure the energy deposition induced by the beam passage. Therefore, a vacuum window has been designed to maintain the differential pressure whilst resisting collapse due to the beam impact on the window. In this paper, we will present calculations of the energy transfer from beam to window, the design of the ...

  10. RF Phase Stability and Electron Beam Characterization for the PLEIADES Thomson X-Ray Source

    Energy Technology Data Exchange (ETDEWEB)

    Brown, W J; Hartemann, F V; Tremaine, A M; Springer, P T; Le Sage, G P; Barty, C P J; Rosenzweig, J B; Crane, J K; Cross, R R; Fittinghoff, D N; Gibson, D J; Slaughter, D R; Anderson, S

    2002-10-16

    We report on the performance of an S-band RF photocathode electron gun and accelerator for operation with the PLEIADES Thomson x-ray source at LLNL. To produce picosecond, high brightness x-ray pulses, picosecond timing, terahertz bandwidth diagnostics, and RF phase control are required. Planned optical, RF, x-ray and electron beam measurements to characterize the dependence of electron beam parameters and synchronization on RF phase stability are presented.

  11. ZnSe-based laser structures for electron-beam pumping with graded index waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Sorokin, S.V.; Sedova, I.V.; Ivanov, S.V. [Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, St. Petersburg 194021 (Russian Federation); Zdanova, E.V.; Zverev, M.M. [Moscow State Institute of Radio Engineering, Electronics and Automations, Moscow 117454 (Russian Federation); Gronin, S.V.

    2010-06-15

    Electron beam pumped (EBP) laser heterostructures with graded index waveguide (GIW) have been grown by molecular beam epitaxy and studied in detail. The maximum achieved output pulse power per facet is as high as 8.5 W at an electron beam energy of 16 kV. No saturation of output power with the increase of electron beam current as well as no suitable degradation of GIW EBP laser structures have been observed. The ways for further optimizations of GIW heterostructures are discussed. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Multi-electron beam system for high resolution electron beam induced deposition

    NARCIS (Netherlands)

    Van Bruggen, M.J.

    2008-01-01

    The development of a multi-electron beam system is described which is dedicated for electron beam induced deposition (EBID) with sub-10 nm resolution. EBID is a promising mask-less nanolithography technique which has the potential to become a viable technique for the fabrication of 20-2 nm structure

  13. Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Hastings, J.B.; /SLAC; Rudakov, F.M.; /Brown U.; Dowell, D.H.; Schmerge, J.F.; /SLAC; Cardoza, J.D.; /Brown U.; Castro, J.M.; Gierman, S.M.; Loos, H.; /SLAC; Weber, P.M.; /Brown U.

    2006-10-24

    An rf photocathode electron gun is used as an electron source for ultrafast time-resolved pump-probe electron diffraction. We observed single-shot diffraction patterns from a 160 nm Al foil using the 5.4 MeV electron beam from the Gun Test Facility at the Stanford Linear Accelerator. Excellent agreement with simulations suggests that single-shot diffraction experiments with a time resolution approaching 100 fs are possible.

  14. Beam physics in future electron hadron colliders

    CERN Document Server

    Valloni, A; Klein, M; Schulte, D; Zimmermann, F

    2013-01-01

    High-energy electron-hadron collisions could support a rich research programme in particle and nuclear physics. Several future projects are being proposed around the world, in particular eRHIC at BNL, MEIC at TJNAF in the US, and LHeC at CERN in Europe. This paper will highlight some of the accelerator physics issues, and describe related technical developments and challenges for these machines. In particular, optics design and beam dynamics studies are discussed, including longitudinal phase space manipulation, coherent synchrotron radiation, beam-beam kink instability, ion effects, as well as mitigation measures for beam break up and for space-charge induced emittance growth, all of which could limit the machine performance. Finally, first steps are presented towards an LHeC R&D facility, which should investigate relevant beam-physics processes.

  15. First test of BNL electron beam ion source with high current density electron beam

    Science.gov (United States)

    Pikin, Alexander; Alessi, James G.; Beebe, Edward N.; Shornikov, Andrey; Mertzig, Robert; Wenander, Fredrik; Scrivens, Richard

    2015-01-01

    A new electron gun with electrostatic compression has been installed at the Electron Beam Ion Source (EBIS) Test Stand at BNL. This is a collaborative effort by BNL and CERN teams with a common goal to study an EBIS with electron beam current up to 10 A, current density up to 10,000 A/cm2 and energy more than 50 keV. Intensive and pure beams of heavy highly charged ions with mass-to-charge ratio heavy ion research facilities including NASA Space Radiation Laboratory (NSRL) at BNL and HIE-ISOLDE at CERN. With a multiampere electron gun, the EBIS should be capable of delivering highly charged ions for both RHIC facility applications at BNL and for ISOLDE experiments at CERN. Details of the electron gun simulations and design, and the Test EBIS electrostatic and magnetostatic structures with the new electron gun are presented. The experimental results of the electron beam transmission are given.

  16. Adapting High Brightness Relativistic Electron Beams for Ultrafast Science

    Science.gov (United States)

    Scoby, Cheyne Matthew

    This thesis explores the use of ultrashort bunches generated by a radiofrequency electron photoinjector driven by a femtosecond laser. Rf photoinjector technology has been developed to generate ultra high brightness beams for advanced accelerators and to drive advanced light source applications. The extremely good quality of the beams generated by this source has played a key role in the development of 4th generation light sources such as the Linac Coherent Light Source, thus opening the way to studies of materials science and biological systems with high temporal and spatial resolution. At the Pegasus Photoinjector Lab, we have developed the application of a BNL/SLAC/UCLA 1.6-cell rf photoinjector as a tool for ultrafast science in its own right. It is the aim of this work to explore the generation of ultrashort electron bunches, give descriptions of the novel ultrafast diagnostics developed to be able to characterize the electron bunch and synchronize it with a pump laser, and share some of the scientific results that were obtained with this technology at the UCLA Pegasus laboratory. This dissertation explains the requirements of the drive laser source and describes the principles of rf photoinjector design and operation necessary to produce electron bunches with an rms longitudinal length < 100 femtoseconds containing 107 - 108 electrons per bunch. In this condition, when the laser intensity is sufficiently high, multiphoton photoemission is demonstrated to be more efficient in terms of charge yield than single photon photoemission. When a short laser pulse hits the cathode the resulting beam dynamics are dominated by a strong space charge driven longitudinal expansion which leads to the creation of a nearly ideal uniformly filled ellipsoidal distribution. These beam distributions are characterized by linear space charge forces and hence by high peak brightness and small transverse emittances. This regime of operation of the RF photoinjector is also termed the

  17. Pulsed beam dosimetry using fiber-coupled radioluminescence detectors

    DEFF Research Database (Denmark)

    Andersen, Claus Erik

    2012-01-01

    The objective of this work was to review and discuss the potential application of fiber-coupled radioluminescence detectors for dosimetry in pulsed MV photon beams. Two types of materials were used: carbon-doped aluminium oxide (Al2O3:C) and organic plastic scintillators. Special consideration...... was given to the discrimination between radioluminescence signals from the phosphors and unwanted light induced in the optical fiber cables during irradiation (Cerenkov and fluorescence). New instrumentation for dose-per-pulse measurements with organic plastic scintillators was developed....

  18. Microsecond pulse width, intense, light-ion beam accelerator

    Science.gov (United States)

    Rej, D. J.; Bartsch, R. R.; Davis, H. A.; Faehl, R. J.; Greenly, J. B.; Waganaar, W. J.

    1993-10-01

    A relatively long-pulse width (0.1-1 μs) intense ion beam accelerator has been built for materials processing applications. An applied Br, magnetically insulated extraction ion diode with dielectric flashover ion source is installed directly onto the output of a 1.2 MV, 300-kJ Marx generator. The diode is designed with the aid of multidimensional particle-in-cell simulations. Initial operation of the accelerator at 0.4 MV indicates satisfactory performance without the need for additional pulse shaping. The effect of a plasma opening switch on diode behavior is considered.

  19. Pulsed beam tests at the SANAEM RFQ beamline

    Science.gov (United States)

    Turemen, G.; Akgun, Y.; Alacakir, A.; Kilic, I.; Yasatekin, B.; Ergenlik, E.; Ogur, S.; Sunar, E.; Yildiz, V.; Ahiska, F.; Cicek, E.; Unel, G.

    2017-07-01

    A proton beamline consisting of an inductively coupled plasma (ICP) source, two solenoid magnets, two steerer magnets and a radio frequency quadrupole (RFQ) is developed at the Turkish Atomic Energy Authority’s (TAEA) Saraykoy Nuclear Research and Training Center (SNRTC-SANAEM) in Ankara. In Q4 of 2016, the RFQ was installed in the beamline. The high power tests of the RF power supply and the RF transmission line were done successfully. The high power RF conditioning of the RFQ was performed recently. The 13.56 MHz ICP source was tested in two different conditions, CW and pulsed. The characterization of the proton beam was done with ACCTs, Faraday cups and a pepper-pot emittance meter. Beam transverse emittance was measured in between the two solenoids of the LEBT. The measured beam is then reconstructed at the entrance of the RFQ by using computer simulations to determine the optimum solenoid currents for acceptance matching of the beam. This paper will introduce the pulsed beam test results at the SANAEM RFQ beamline. In addition, the high power RF conditioning of the RFQ will be discussed.

  20. Breakdown behavior of electronics at variable pulse repetition rates

    OpenAIRE

    Korte, S.; H. Garbe

    2006-01-01

    The breakdown behavior of electronics exposed to single transient electromagnetic pulses is subject of investigations for several years. State-of-the-art pulse generators additionally provide the possibility to generate pulse sequences with variable pulse repetition rate. In this article the influence of this repetition rate variation on the breakdown behavior of electronic systems is described. For this purpose microcontroller systems are examined during line-led exposure to pulses with repe...

  1. Electron-beam deposition of vanadium dioxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Marvel, R.E.; Appavoo, K. [Vanderbilt University, Interdisciplinary Materials Science Program, Nashville, TN (United States); Choi, B.K. [Vanderbilt University, Department of Electrical Engineering and Computer Science, Nashville, TN (United States); Nag, J. [Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States); Haglund, R.F. [Vanderbilt University, Interdisciplinary Materials Science Program, Nashville, TN (United States); Vanderbilt University, Institute for Nanoscale Science and Engineering, Nashville, TN (United States); Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States)

    2013-06-15

    Developing a reliable and efficient fabrication method for phase-transition thin-film technology is critical for electronic and photonic applications. We demonstrate a novel method for fabricating polycrystalline, switchable vanadium dioxide thin films on glass and silicon substrates and show that the optical switching contrast is not strongly affected by post-processing annealing times. The method relies on electron-beam evaporation of a nominally stoichiometric powder, followed by fast annealing. As a result of the short annealing procedure we demonstrate that films deposited on silicon substrates appear to be smoother, in comparison to pulsed laser deposition and sputtering. However, optical performance of e-beam evaporated film on silicon is affected by annealing time, in contrast to glass. (orig.)

  2. Dosimetry for Electron Beam Applications

    DEFF Research Database (Denmark)

    Miller, Arne

    1983-01-01

    This report describes two aspects of electron bean dosimetry, on one hand developaent of thin fil« dosimeters and measurements of their properties, and on the other hand developaent of calorimeters for calibration of routine dosimeters, e.g. thin films. Two types of radiochromic thin film...

  3. A high brightness electron beam for Free Electron Lasers

    NARCIS (Netherlands)

    Oerle, van Bartholomeus Mathias

    1997-01-01

    In a free electron laser, coherent radiation is generated by letting an electron beam propagate through an alternating magnetic field. The magnetic field is created by a linear array of magnets, which is called an undulator or a wiggler. The wavelength of the laser radiation depends on the amplitude

  4. Electron beam induced growth of tin whiskers

    Energy Technology Data Exchange (ETDEWEB)

    Vasko, A. C.; Karpov, V. G. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States); Warrell, G. R.; Parsai, E. I.; Shvydka, Diana, E-mail: diana.shvydka@utoledo.edu [Department of Radiation Oncology, University of Toledo Health Science Campus, Toledo, Ohio 43614 (United States)

    2015-09-28

    We have investigated the influence of electron irradiation on tin whisker growth. Sputtered tin samples exposed to electron beam of 6 MeV energy exhibited fast whisker growth, while control samples did not grow any whiskers. The statistics of e-beam induced whiskers was found to follow the log-normal distribution. The observed accelerated whisker growth is attributed to electrostatic effects due to charges trapped in an insulating substrate. These results offer promise for establishing whisker-related accelerated life testing protocols.

  5. Development of high quality electron beam accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kando, Masaki; Dewa, Hideki; Kotaki, Hideyuki; Kondo, Shuji; Hosokai, Tomonao; Kanazawa, Shuhei; Yokoyama, Takashi; Nakajima, Kazuhisa [Advanced Photon Research Center, Kansai Research Establishment, Japan Atomic Energy Research Institute, Kizu, Kyoto (Japan)

    2000-03-01

    A design study on a high quality electron beam accelerator is described. This accelerator will be used for second generation experiments of laser wakefield acceleration, short x-ray generation, and other experiments of interaction of high intensity laser with an electron beam at Advanced Photon Research Center, Kansai Research Establishment, Japan Atomic Energy Research Institute. The system consists of a photocathode rf gun and a race-track microtron (RTM). To combine these two components, injection and extraction beamlines are designed employing transfer matrix and compute codes. A present status of the accelerator system is also presented. (author)

  6. Advanced electron beam resist requirements and challenges

    Science.gov (United States)

    Jamieson, Andrew; Kim, Yong Kwan; Olson, Bennett; Lu, Maiying; Wilcox, Nathan

    2011-11-01

    As photomask minimum feature size requirements continue to shrink, resist resolution limitations and their tradeoffs with exposure dose are critical factors. Recently, nearly every node needs a new electron beam resist, customized for exposure dose requirements while simultaneously meeting resolution specifications. Intel Mask Operations has an active program focused on screening new electron beam resists and processes. We discuss the performance metrics we use to evaluate materials and discuss the relative capabilities of the latest resists. We present fundamental resist metrics (resolution, LER and dose) as well as manufacturing process sensitivities.

  7. Energy distributions of electrons in electron beam produced nitrogen plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Suhre, D.R.

    1976-01-01

    A theory was developed which predicts the equilibrium electron energy distributions resulting from the injection of an electron beam into molecular nitrogen. The results were highly non-Maxwellian with a depletion region existing near 2.5 eV. Using these distributions, fractional power transfers to various excitation processes were calculated. The theory was verified experimentally by using Langmuir probes to measure the electron energy distributions produced by a beam generated by a cold cathode discharge in low pressure nitrogen. The distributions were measured in absolute units and compared directly with theory. All of the major features of the theory were found to be present in the measurements.

  8. Facile time-of-flight methods for characterizing pulsed superfluid helium droplet beams

    Energy Technology Data Exchange (ETDEWEB)

    He, Yunteng; Zhang, Jie; Li, Yang; Freund, William M.; Kong, Wei, E-mail: wei.kong@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, Oregon 97331 (United States)

    2015-08-15

    We present two facile time-of-flight (TOF) methods of detecting superfluid helium droplets and droplets with neutral dopants. Without an electron gun and with only a heated filament and pulsed electrodes, the electron impact ionization TOF mass spectrometer can resolve ionized helium clusters such as He{sub 2}{sup +} and He{sub 4}{sup +}, which are signatures of superfluid helium droplets. Without ionizing any helium atoms, multiphoton non-resonant laser ionization of CCl{sub 4} doped in superfluid helium droplets at 266 nm generates complex cluster ions of dopant fragments with helium atoms, including (He){sub n}C{sup +}, (He){sub n}Cl{sup +}, and (He){sub n}CCl{sup +}. Using both methods, we have characterized our cryogenic pulsed valve—the Even-Lavie valve. We have observed a primary pulse with larger helium droplets traveling at a slower speed and a rebound pulse with smaller droplets at a faster speed. In addition, the pickup efficiency of dopant is higher for the primary pulse when the nozzle temperature is higher than 13 K, and the total time duration of the doped droplet pulse is only on the order of 20 μs. These results stress the importance of fast and easy characterization of the droplet beam for sensitive measurements such as electron diffraction of doped droplets.

  9. Facile time-of-flight methods for characterizing pulsed superfluid helium droplet beams.

    Science.gov (United States)

    He, Yunteng; Zhang, Jie; Li, Yang; Freund, William M; Kong, Wei

    2015-08-01

    We present two facile time-of-flight (TOF) methods of detecting superfluid helium droplets and droplets with neutral dopants. Without an electron gun and with only a heated filament and pulsed electrodes, the electron impact ionization TOF mass spectrometer can resolve ionized helium clusters such as He2(+) and He4(+), which are signatures of superfluid helium droplets. Without ionizing any helium atoms, multiphoton non-resonant laser ionization of CCl4 doped in superfluid helium droplets at 266 nm generates complex cluster ions of dopant fragments with helium atoms, including (He)(n)C(+), (He)(n)Cl(+), and (He)(n)CCl(+). Using both methods, we have characterized our cryogenic pulsed valve—the Even-Lavie valve. We have observed a primary pulse with larger helium droplets traveling at a slower speed and a rebound pulse with smaller droplets at a faster speed. In addition, the pickup efficiency of dopant is higher for the primary pulse when the nozzle temperature is higher than 13 K, and the total time duration of the doped droplet pulse is only on the order of 20 μs. These results stress the importance of fast and easy characterization of the droplet beam for sensitive measurements such as electron diffraction of doped droplets.

  10. Prebunching and electron pulse phase stability in FELIX

    Science.gov (United States)

    Oepts, D.; Weits, H. H.

    1997-06-01

    The importance of coherent spontaneous emission in a free-electron laser operating with short electron pulses is discussed. A coherent enhancement by many orders of magnitude has been observed in the far infrared with the FELIX device. The associated coherence between independent optical micropulses is used to determine the phase stability of the electron pulses. It is found that the pulse-to-pulse jitter is not more than some tens of femtoseconds on a timescale of nanoseconds.

  11. Electron optics of multi-beam scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi-Gheidari, A., E-mail: A.M.Gheidari@tudelft.nl [Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Kruit, P. [Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands)

    2011-07-21

    We have developed a multi-beam scanning electron microscope (MBSEM), which delivers a square array of 196 focused beams onto a sample with a resolution and current per beam comparable to a state of the art single beam SEM. It consists of a commercially available FEI Nova-nano 200 SEM column equipped with a novel multi-electron beam source module. The key challenge in the electron optical design of the MBSEM is to minimize the off-axial aberrations of the lenses. This article addresses the electron optical design of the system and presents the result of optics simulations for a specific setting of the system. It is shown that it is possible to design a system with a theoretical axial spot size of 1.2 nm at 15 kV with a probe current of 26 pA. The off-axial aberrations for the outermost beam add up 0.8 nm, increasing the probe size to 1.5 nm.

  12. Anomalous argon excitation in pulse supersonic flows of Ar + CH sub 4 , Ar + SiH sub 4 and Ar + CH sub 4 + SiH sub 4 mixtures, activated with an electron beam

    CERN Document Server

    Madirbaev, V Z; Korobejshchikov, N G; Sharafutdinov, R G

    2001-01-01

    The processes of energy exchange in the supersonic flows of the argon mixtures with methane and silane, activated by the electron beam, are studied. It is shown, that at the initial stage of condensation in the flux there takes place selective excitation of the argon atoms energy levels. The boundary parameters, whereby the effect of the anomalous radiation excitation is observed, are determined

  13. Propagation of Plasma Generated by Intense Pulsed Ion Beam Irradiation

    Institute of Scientific and Technical Information of China (English)

    WU Di; GONG Ye; LIU Jin-Yuan; WANG Xiao-Gang; LIU Yue; MA Teng-Cai

    2006-01-01

    @@ Taking the calculation results based on the established two-dimensional ablation model of the intense-pulsed-ion-beam (IPIB) irradiation process as initial conditions, we build a two-dimensional hydrodynamic ejection model of plasma produced by an IPIB-irradiated metal titanium target into ambient gas. We obtain the conclusions that shock waves generate when the background pressure is around 133 mTorr and also obtain the plume splitting phenomenon that has been observed in the experiments.

  14. Electron beam damage in high temperature polymers

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. (Dayton Univ., OH (USA). Research Inst.); Adams, W.W. (Air Force Materials Lab., Wright-Patterson AFB, OH (USA))

    1990-01-01

    Electron microscopic studies of polymers are limited due to beam damage. Two concerns are the damage mechanism in a particular material, and the maximum dose for a material before damage effects are observed. From the knowledge of the dose required for damage to the polymer structure, optimum parameters for electron microscopy imaging can be determined. In the present study, electron beam damage of polymers has been quantified by monitoring changes in the diffraction intensity as a function of electron dose. The beam damage characteristics of the following polymers were studied: poly(p-phenylene benzobisthiazole) (PBZT); poly(p-phenylene benzobisoxazole) (PBO); poly(benzoxazole) (ABPBO); poly(benzimidazole) (ABPBI); poly(p-phenylene terephthalamide) (PPTA); and poly(aryl ether ether ketone) (PEEK). Previously published literature results on polyethylene (PE), polyoxymethylene (POM), nylon-6, poly(ethylene oxide) (PEO), PBZT, PPTA, PPX, iPS, poly(butylene terephthalate) (PBT), and poly(phenylene sulphide) (PPS) were reviewed. This study demonstrates the strong dependence of the electron beam resistivity of a polymer on its thermal stability/melt temperature. (author).

  15. Analysis of emissions from prebunched electron beams

    Directory of Open Access Journals (Sweden)

    Jia Qika

    2017-07-01

    Full Text Available The emissions of the prebunched electron beam, including the coherent spontaneous emission and the self-amplified stimulated emission, are analyzed by using one-dimensional FEL theory. Neglecting the interaction of the electrons and the radiation field, the formula of the coherent spontaneous emission is given, the power of which is proportional to the square of the initial bunching factor and of the undulator length. For the general emission case of the prebunched electron beam, the evolution equation of the optical field is deducted. Then the analytical expression of the emission power is obtained for the resonant case; it is applicable to the regions from the low gain to the high gain. It is found that when the undulator length is shorter than four gain lengths, the emission is just the coherent spontaneous emission, and conversely, it is the self-amplified stimulated emission growing exponentially. For the nonresonant prebunched electron beam, the variations of the emission intensity with the detuning parameter for different interaction length are presented. The radiation field characters of the prebunched electron beam are discussed and compared with that of the seeded FEL amplifier.

  16. Analysis of emissions from prebunched electron beams

    Science.gov (United States)

    Jia, Qika

    2017-07-01

    The emissions of the prebunched electron beam, including the coherent spontaneous emission and the self-amplified stimulated emission, are analyzed by using one-dimensional FEL theory. Neglecting the interaction of the electrons and the radiation field, the formula of the coherent spontaneous emission is given, the power of which is proportional to the square of the initial bunching factor and of the undulator length. For the general emission case of the prebunched electron beam, the evolution equation of the optical field is deducted. Then the analytical expression of the emission power is obtained for the resonant case; it is applicable to the regions from the low gain to the high gain. It is found that when the undulator length is shorter than four gain lengths, the emission is just the coherent spontaneous emission, and conversely, it is the self-amplified stimulated emission growing exponentially. For the nonresonant prebunched electron beam, the variations of the emission intensity with the detuning parameter for different interaction length are presented. The radiation field characters of the prebunched electron beam are discussed and compared with that of the seeded FEL amplifier.

  17. Suppression of COTR in electron beam imaging diagnosis at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Minjie

    2012-05-15

    The Free-Electron Laser in Hamburg (FLASH) demands electron beams with high peak current to generate high-brilliant, coherent X-ray pulses. Magnetic chicanes are used for longitudinal compression of the electron bunches to achieve the required high peak current. During bunch compression process, microstructures with a modulation length comparable to the visible light can be induced inside the bunch. This leads to coherent emission of optical transition radiation (OTR), which may impede the widely used beam diagnostic based on OTR imaging. In this thesis, two methods of using incoherent scintillation light are proposed to circumvent the problem of coherence effects in beam imaging diagnostics. The method of temporal separation has been proved experimentally to have successfully suppressed coherence effects. The longitudinal beam profiles measured using this method are in good agreement with reference measurements, verifying further the reliability of the method. The method of spatial separation has been investigated in preparation studies, from which an improved experimental setup has been designed.

  18. Spectrum-Induced Changes in Non-Paraxial Property of Ultrashort Pulsed Beam

    Institute of Scientific and Technical Information of China (English)

    陆大全; 胡巍; 杨振军; 郑一周

    2003-01-01

    A spatiotemporal non-paraxial correction to the paraxial solution of ultrashort pulsed beam is obtained by using the Fourier transform and the Taylor expansion. By studying the propagation of an isodiffracting pulsed Gaussian beam with different pulse shapes, we find that there are spectrum-induced changes in the non-paraxial propagation of the pulsed beam. We analyse the influence of pulse spectrum on the non-paraxial property of the ultrashort pulsed beam and explain it base on the paraxial approximation condition.

  19. Ramsey-type phase control of free electron beams

    CERN Document Server

    Echternkamp, Katharina E; Schäfer, Sascha; Ropers, Claus

    2016-01-01

    Interference between multiple distinct paths is a defining property of quantum physics, where "paths" may involve actual physical trajectories, as in interferometry, or transitions between different internal (e.g. spin) states, or both. A hallmark of quantum coherent evolution is the possibility to interact with a system multiple times in a phase-preserving manner. This principle underpins powerful multi-dimensional optical and nuclear magnetic resonance spectroscopies and related techniques, including Ramsey's method of separated oscillatory fields used in atomic clocks. Previously established for atomic, molecular and quantum dot systems, recent developments in the optical quantum state preparation of free electron beams suggest a transfer of such concepts to the realm of ultrafast electron imaging and spectroscopy. Here, we demonstrate the sequential coherent interaction of free electron states with two spatially separated, phase-controlled optical near-fields. Ultrashort electron pulses are acted upon in ...

  20. Gamma Putty dosimetric studies in electron beam

    Science.gov (United States)

    Gloi, Aime M.

    2016-01-01

    Traditionally, lead has been used for field shaping in megavoltage electron beams in radiation therapy. In this study, we analyze the dosimetric parameters of a nontoxic, high atomic number (Z = 83), bismuth-loaded material called Gamma Putty that is malleable and can be easily molded to any desired shape. First, we placed an ionization chamber at different depths in a solid water phantom under a Gamma Putty shield of thickness (t = 0, 3, 5, 10, 15, 20, and 25 mm, respectively) and measured the ionizing radiation on the central axis (CAX) for electron beam ranging in energies from 6 to 20 MeV. Next, we investigated the relationship between the relative ionization (RI) measured at a fixed depth for several Gamma Putty shield at different cutout diameters ranging from 2 to 5 cm for various beam energies and derived an exponential fitting equation for clinical purposes. The dose profiles along the CAX show that bremsstrahlung dominates for Gamma Putty thickness >15 mm. For high-energy beams (12–20 MeV) and all Gamma Putty thicknesses up to 25 mm, RI below 5% could not be achieved due to the strong bremsstrahlung component. However, Gamma Putty is a very suitable material for reducing the transmission factor below 5% and protecting underlying normal tissues for low-energy electron beams (6–9 MeV). PMID:27651563

  1. Gamma Putty dosimetric studies in electron beam

    Directory of Open Access Journals (Sweden)

    Aime M Gloi

    2016-01-01

    Full Text Available Traditionally, lead has been used for field shaping in megavoltage electron beams in radiation therapy. In this study, we analyze the dosimetric parameters of a nontoxic, high atomic number (Z = 83, bismuth-loaded material called Gamma Putty that is malleable and can be easily molded to any desired shape. First, we placed an ionization chamber at different depths in a solid water phantom under a Gamma Putty shield of thickness (t = 0, 3, 5, 10, 15, 20, and 25 mm, respectively and measured the ionizing radiation on the central axis (CAX for electron beam ranging in energies from 6 to 20 MeV. Next, we investigated the relationship between the relative ionization (RI measured at a fixed depth for several Gamma Putty shield at different cutout diameters ranging from 2 to 5 cm for various beam energies and derived an exponential fitting equation for clinical purposes. The dose profiles along the CAX show that bremsstrahlung dominates for Gamma Putty thickness >15 mm. For high-energy beams (12-20 MeV and all Gamma Putty thicknesses up to 25 mm, RI below 5% could not be achieved due to the strong bremsstrahlung component. However, Gamma Putty is a very suitable material for reducing the transmission factor below 5% and protecting underlying normal tissues for low-energy electron beams (6-9 MeV.

  2. Influence of the electrode gap separation on the pseudospark-sourced electron beam generation

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J., E-mail: junping.zhao@qq.com [High Voltage Division, School of Electrical Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); State Key Laboratory of Electrical Insulation and Power Equipment, West Xianning Road, Xi' an 710049 (China); Department of Physics, SUPA, University of Strathclyde, Glasgow, G4 0NG Scotland (United Kingdom); Yin, H.; Zhang, L.; Shu, G.; He, W.; Phelps, A. D. R.; Cross, A. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow, G4 0NG Scotland (United Kingdom); Zhang, J.; Zhang, Q. [High Voltage Division, School of Electrical Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); State Key Laboratory of Electrical Insulation and Power Equipment, West Xianning Road, Xi' an 710049 (China)

    2016-07-15

    Pseudospark-sourced electron beam is a self-focused intense electron beam which can propagate without any external focusing magnetic field. This electron beam can drive a beam-wave interaction directly or after being post-accelerated. It is especially suitable for terahertz radiation generation due to the ability of a pseudospark discharge to produce small size in the micron range and very high current density and bright electron beams. In this paper, a single-gap pseudospark discharge chamber has been built and tested with several electrode gap separations to explore the dependence of the pseudospark-sourced electron beam current on the discharge voltage and the electrode gap separation. Experimental results show that the beam pulses have similar pulse width and delay time from the distinct drop of the applied voltage for smaller electrode gap separations but longer delay time for the largest gap separation used in the experiment. It has been found that the electron beam only starts to occur when the charging voltage is above a certain value, which is defined as the starting voltage of the electron beam. The starting voltage is different for different electrode gap separations and decreases with increasing electrode gap separation in our pseudospark discharge configuration. The electron beam current increases with the increasing discharge voltage following two tendencies. Under the same discharge voltage, the configuration with the larger electrode gap separation will generate higher electron beam current. When the discharge voltage is higher than 10 kV, the beam current generated at the electrode gap separation of 17.0 mm, is much higher than that generated at smaller gap separations. The ionization of the neutral gas in the main gap is inferred to contribute more to the current increase with increasing electrode gap separation.

  3. Controlling the fast electron divergence in a solid target with multiple laser pulses

    Science.gov (United States)

    Volpe, L.; Feugeas, J.-L.; Nicolai, Ph.; Santos, J. J.; Touati, M.; Breil, J.; Batani, D.; Tikhonchuk, V.

    2014-12-01

    Controlling the divergence of laser-driven fast electrons is compulsory to meet the ignition requirements in the fast ignition inertial fusion scheme. It was shown recently that using two consecutive laser pulses one can improve the electron-beam collimation. In this paper we propose an extension of this method by using a sequence of several laser pulses with a gradually increasing intensity. Profiling the laser-pulse intensity opens a possibility to transfer to the electron beam a larger energy while keeping its divergence under control. We present numerical simulations performed with a radiation hydrodynamic code coupled to a reduced kinetic module. Simulation with a sequence of three laser pulses shows that the proposed method allows one to improve the efficiency of the double pulse scheme at least by a factor of 2. This promises to provide an efficient energy transport in a dense matter by a collimated beam of fast electrons, which is relevant for many applications such as ion-beam sources and could present also an interest for fast ignition inertial fusion.

  4. Electron cloud effects in hadron beams

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Fedor; Boine-Frankenheim, Oliver; Weiland, Thomas [TU-Darmstadt, Institut fuer Theorie Elektromagnetischer Felder,Schlossgartenstr. 8 64289 Darmstadt (Germany)

    2013-07-01

    Accelerators operating with intense positively charged beams can suffer from the electron cloud phenomenon. For example, it is the intensity limiting factor in CERN LHC and SPS. In past decades a lot of progress in understanding the electron cloud effects was made worldwide. Methods to suppress or weaken the electron cloud phenomenon were proposed. Theories governing the bunch stability in presence of the electron cloud were developed. Recently the theory was introduced to describe the bunch energy loss due to the electron cloud. However, most of the publications concern the single bunch electron cloud effects. In reality bunches are packed into trains. A disturbance of the cloud caused by the bunch in the beginning of the train affects the subsequent bunches. We present a further investigation of single-bunch electron cloud effects and planned activities to study the phenomenon in case of multiple bunches.

  5. Gas Electron multipliers for low energy beams

    CERN Document Server

    Arnold, F; Ropelewski, L; Spanggaard, J; Tranquille, G

    2010-01-01

    Gas Electron Multipliers (GEM) find their way to more and more applications in beam instrumentation. Gas Electron Multiplication uses a very similar physical phenomenon to that of Multi Wire Proportional Chambers (MWPC) but for small profile monitors they are much more cost efficient both to produce and to maintain. This paper presents the new GEM profile monitors intended to replace the MWPCs currently used at CERN’s low energy Antiproton Decelerator (AD). It will be shown how GEMs overcome the documented problems of profile measurements with MWPCs for low energy beams, where the interaction of the beam with the detector has a large influence on the measured profile. Results will be shown of profile measurements performed at 5 MeV using four different GEM prototypes, with discussion on the possible use of GEMs at even lower energies needed at the AD in 2013.

  6. Parameters of a supershort avalanche electron beam generated in atmospheric-pressure air

    Science.gov (United States)

    Tarasenko, V. F.

    2011-05-01

    Conditions under which the number of runaway electrons in atmospheric-pressure air reaches ˜5 × 1010 are determined. Recommendations for creating runaway electron accelerators are given. Methods for measuring the parameters of a supershort avalanche electron beam and X-ray pulses from gas-filled diodes, as well as the discharge current and gap voltage, are described. A technique for determining the instant of runaway electron generation with respect to the voltage pulse is proposed. It is shown that the reduction in the gap voltage and the decrease in the beam current coincide in time. The mechanism of intense electron beam generation in gas-filled diodes is analyzed. It is confirmed experimentally that, in optimal regimes, the number of electrons generated in atmospheric-pressure air with energies T > eU m , where U m is the maximum gap voltage, is relatively small.

  7. Electron beam ion traps and their applications

    Institute of Scientific and Technical Information of China (English)

    ZOU Ya-Ming; Roger HUTTON

    2003-01-01

    A brief introduction to the historical background and current status of electron beam ion traps (EBITs)is presented. The structure and principles of an EBIT for producing highly charged ions are described. Finally,EBITs as a potential tool in hot-plasma diagnostics and in studying frontier problems of highly charged ion physicsare discussed.

  8. Electron beam charge diagnostics for laser plasma accelerators

    Directory of Open Access Journals (Sweden)

    K. Nakamura

    2011-06-01

    Full Text Available A comprehensive study of charge diagnostics is conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs. First, a scintillating screen (Lanex was extensively studied using subnanosecond electron beams from the Advanced Light Source booster synchrotron, at the Lawrence Berkeley National Laboratory. The Lanex was cross calibrated with an integrating current transformer (ICT for up to the electron energy of 1.5 GeV, and the linear response of the screen was confirmed for charge density and intensity up to 160  pC/mm^{2} and 0.4  pC/(ps  mm^{2}, respectively. After the radio-frequency accelerator based cross calibration, a series of measurements was conducted using electron beams from an LPA. Cross calibrations were carried out using an activation-based measurement that is immune to electromagnetic pulse noise, ICT, and Lanex. The diagnostics agreed within ±8%, showing that they all can provide accurate charge measurements for LPAs.

  9. Electron Beam Charge Diagnostics for Laser Plasma Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Smith, Alan; Rodgers, David; Donahue, Rich; Byrne, Warren; Leemans, Wim

    2011-06-27

    A comprehensive study of charge diagnostics is conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). First, a scintillating screen (Lanex) was extensively studied using subnanosecond electron beams from the Advanced Light Source booster synchrotron, at the Lawrence Berkeley National Laboratory. The Lanex was cross calibrated with an integrating current transformer (ICT) for up to the electron energy of 1.5 GeV, and the linear response of the screen was confirmed for charge density and intensity up to 160 pC/mm{sup 2} and 0.4 pC/(ps mm{sup 2}), respectively. After the radio-frequency accelerator based cross calibration, a series of measurements was conducted using electron beams from an LPA. Cross calibrations were carried out using an activation-based measurement that is immune to electromagnetic pulse noise, ICT, and Lanex. The diagnostics agreed within {+-}8%, showing that they all can provide accurate charge measurements for LPAs.

  10. Super-radiance in a prebunched beam free electron maser

    CERN Document Server

    Arbel, M; Pinhasi, Y; Lurie, Y; Tecimer, M; Abramovich, A; Kleinman, H; Yakover, I M; Gover, A

    2000-01-01

    It is well known that electrons passing through a magnetic undulator emit partially coherent radiation: 'Undulator Synchrotron Radiation'. Radiation from electrons, entering the undulator at random, adds incoherently. If the electron beam is periodically modulated (bunched) to pulses shorter than the radiation wavelength, electrons radiate in phase with each other, resulting in super-radiant emission at the bunching frequency. Introduction of a signal at the input of the prebunched beam FEL, results in stimulated super-radiant emission. The interaction between the electromagnetic wave and a synchronous modulated e-beam results in amplification of the signal wave in addition to the spontaneous super-radiant emission. We demonstrated and measured the super-radiant emission in a wide band of frequencies from 3.15 to 5.5 GHz using the mini-FEM of Tel-Aviv University, wherein pre-bunching at the radiation frequency is accomplished with the aid of a traveling-wave prebuncher. The measured upper synchronous frequenc...

  11. Spectral anomalies of diffracted pulsed Hermite-Gaussian beams in dispersive media

    Institute of Scientific and Technical Information of China (English)

    Zhao Zhi-Guo; Pan Liu-Zhan; Lü Bai-Da

    2008-01-01

    This paper derives and uses the recurrence expressions for the power spectra of diffracted pulsed Hermite-Gaussian (HG) beams in dispersive media to study the spectral anomalies of pulsed HG beams in the far field. Numerical results are given to illustrate the dependence of spectral switches on the pulse parameters, truncation parameter and dispersive property of the medium. The potential application of spectral anomalies of ultrashort pulsed beams in information encoding and transmission is discussed.

  12. Supershort avalanche electron beam in SF6 and krypton

    Science.gov (United States)

    Zhang, Cheng; Tarasenko, Victor F.; Gu, Jianwei; Baksht, Evgeni Kh.; Beloplotov, Dmitry V.; Burachenko, Alexander G.; Yan, Ping; Lomaev, Mikhail I.; Shao, Tao

    2016-03-01

    Runaway electrons play an important role in the avalanche formation in nanosecond- and subnanosecond- pulse discharges. In this paper, characteristics of a supershort avalanche electron beam (SAEB) generated at the subnanosecond and nanosecond breakdown in sulfur hexafluoride (SF6 ) in an inhomogeneous electric field were studied. One pulser operated at negative polarity with voltage pulse amplitude of ˜130 kV and rise time of 0.3 ns. The other pulser operated at negative polarity with voltage pulse amplitude of 70 kV and rise time of ˜1.6 ns . SAEB parameters in SF6 are compared with those obtained in krypton (Kr), nitrogen (N2 ), air, and mixtures of SF6 with krypton or nitrogen. Experimental results showed that SAEB currents appeared during the rise-time of the voltage pulse for both pulsers. Moreover, amplitudes of the SAEB current in SF6 and Kr approximately ranged from several to tens of milliamps at atmospheric pressure, which were smaller than those in N2 and air (ranging from hundreds of milliamps to several amperes). Furthermore, the concentration of SF6 additive could significantly reduce the SAEB current in N2-SF6 mixture, but it slightly affected the SAEB current in Kr -SF6 mixture because of the atomic/molecular ionization cross section of the gas had a much greater impact on the SAEB current rather than the electronegativity.

  13. Multifrequency pulsed electron paramagnetic resonance on metalloproteins.

    Science.gov (United States)

    Lyubenova, Sevdalina; Maly, Thorsten; Zwicker, Klaus; Brandt, Ulrich; Ludwig, Bernd; Prisner, Thomas

    2010-02-16

    Metalloproteins often contain metal centers that are paramagnetic in some functional state of the protein; hence electron paramagnetic resonance (EPR) spectroscopy can be a powerful tool for studying protein structure and function. Dipolar spectroscopy allows the determination of the dipole-dipole interactions between metal centers in protein complexes, revealing the structural arrangement of different paramagnetic centers at distances of up to 8 nm. Hyperfine spectroscopy can be used to measure the interaction between an unpaired electron spin and nuclear spins within a distance of 0.8 nm; it therefore permits the characterization of the local structure of the paramagnetic center's ligand sphere with very high precision. In this Account, we review our laboratory's recent applications of both dipolar and hyperfine pulsed EPR methods to metalloproteins. We used pulsed dipolar relaxation methods to investigate the complex of cytochrome c and cytochrome c oxidase, a noncovalent protein-protein complex involved in mitochondrial electron-transfer reactions. Hyperfine sublevel correlation spectroscopy (HYSCORE) was used to study the ligand sphere of iron-sulfur clusters in complex I of the mitochondrial respiratory chain and substrate binding to the molybdenum enzyme polysulfide reductase. These examples demonstrate the potential of the two techniques; however, they also highlight the difficulties of data interpretation when several paramagnetic species with overlapping spectra are present in the protein. In such cases, further approaches and data are very useful to enhance the information content. Relaxation filtered hyperfine spectroscopy (REFINE) can be used to separate the individual components of overlapping paramagnetic species on the basis of differences in their longitudinal relaxation rates; it is applicable to any kind of pulsed hyperfine or dipolar spectroscopy. Here, we show that the spectra of the iron-sulfur clusters in complex I can be separated by this

  14. Electron and photon beams from a 50 MeV racetrack microtron.

    Science.gov (United States)

    Brahme, A; Kraepelien, T; Svensson, H

    1980-01-01

    The quality of broad high energy photon and electron beams can be improved considerably by the scanning of elementary narrow beams. Dose distributions produced in this way have advantages with respect to improved dose gradients and therapeutic ranges for electrons and lower surface doses, increased depth doses and half value depths for photons. The possibility of giving the whole therapeutic dose in a single local pulse of short duration is discussed as a new method to protect superficial tissues.

  15. Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring

    Science.gov (United States)

    Kumar, Pradeep; Ghodke, A. D.; Karnewar, A. K.; Holikatti, A. C.; Yadav, S.; Puntambekar, T. A.; Singh, G.; Singh, P.

    2013-12-01

    In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

  16. Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring.

    Science.gov (United States)

    Kumar, Pradeep; Ghodke, A D; Karnewar, A K; Holikatti, A C; Yadav, S; Puntambekar, T A; Singh, G; Singh, P

    2013-12-01

    In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

  17. Fast Electron Beam Simulation and Dose Calculation

    CERN Document Server

    Trindade, A; Peralta, L; Lopes, M C; Alves, C; Chaves, A

    2003-01-01

    A flexible multiple source model capable of fast reconstruction of clinical electron beams is presented in this paper. A source model considers multiple virtual sources emulating the effect of accelerator head components. A reference configuration (10 MeV and 10x10 cm2 field size) for a Siemens KD2 linear accelerator was simulated in full detail using GEANT3 Monte Carlo code. Our model allows the reconstruction of other beam energies and field sizes as well as other beam configurations for similar accelerators using only the reference beam data. Electron dose calculations were performed with the reconstructed beams in a water phantom and compared with experimental data. An agreement of 1-2% / 1-2 mm was obtained, equivalent to the accuracy of full Monte Carlo accelerator simulation. The source model reduces accelerator simulation CPU time by a factor of 7500 relative to full Monte Carlo approaches. The developed model was then interfaced with DPM, a fast radiation transport Monte Carlo code for dose calculati...

  18. An electron optical theory of beam blanking

    Science.gov (United States)

    Gesley, M.

    1993-11-01

    Trajectory equations are derived in closed form for electrons in time-dependent electric fields produced by beam blankers. Simple parallel plate and double-deflection blankers with transmission delay lines are evaluated. Lens imaging of the apparent beam motion is analyzed by developing the virtual electron trajectories obtained from linear extrapolation back into the blanker region. Lens excitation effects and conjugate blanking optics can then be described. The blanker voltage is represented by a damped exponential cosine term, which satisfies a typical circuit equation for the driver-amplifier. The form of the trajectory equation is written as a 3×3 matrix, which comprises a set of conditional solutions that are determined by blanker geometry. The optimum delay line length of any double-deflection blanker can then be determined. The blanker-induced beam jitter is shown to be significantly reduced by using this configuration. The effect of the blanker beam stop on the motion at the target plane is given by combining results on the real and apparent beam trajectories.

  19. Electron beam joining of structural ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Turman, B.N.; Glass, S.J.; Halbleib, J.A.; Helmich, D.R.; Loehman, R.E.

    1995-04-01

    Feasibility of ceramic joining using a high energy (10 MeV) electron beam. The experiments used refractory metals as bonding materials in buried interfaces between Si{sub 3}N{sub 4} pieces. Because the heat capacity of the metal bonding layer is much lower than the ceramic, the metal reaches much higher temperatures than the adjoining ceramic. Using the right combination of beam parameters allows the metal to be melted without causing the adjoining ceramics to melt or decompose. Beam energy deposition and thermal simulations were performed to guide the experiments. Joints were shear tested and interfaces between the metal and the ceramic were examined to identify the bonding mechanism. Specimens joined by electron beams were compared to specimens produced by hot-pressing. Similar reactions occurred using both processes. Reactions between the metal and ceramic produced silicides that bond the metal to the ceramic. The molybdenum silicide reaction products appeared to be more brittle than the platinum silicides. Si{sub 3}N{sub 4} was also joined to Si{sub 3} N{sub 4} directly. The bonding appears to have been produced by the flow of intergranular glass into the interface. Shear strength was similar to the metal bonded specimens. Bend specimens Of Si{sub 3}N{sub 4} were exposed to electron beams with similar parameters to those used in joining experiments to determine how beam exposure degrades the strength. Damage was macroscopic in nature with craters being tonned by material ablation, and cracking occurring due to excessive thermal stresses. Si was also observed on the surface indicating the Si{sub 3}N{sub 4} was decomposing. Bend strength after exposure was 62% of the asreceived strength. No obvious microstructural differences were observed in the material close to the damaged region compared to material in regions far away from the damage.

  20. Electron Accelerators for Radioactive Ion Beams

    Energy Technology Data Exchange (ETDEWEB)

    Lia Merminga

    2007-10-10

    The summary of this paper is that to optimize the design of an electron drive, one must: (a) specify carefully the user requirements--beam energy, beam power, duty factor, and longitudinal and transverse emittance; (b) evaluate different machine options including capital cost, 10-year operating cost and delivery time. The author is convinced elegant solutions are available with existing technology. There are several design options and technology choices. Decisions will depend on system optimization, in-house infrastructure and expertise (e.g. cryogenics, SRF, lasers), synergy with other programs.

  1. Generation of electron beams from a laser-based advanced accelerator at Shanghai Jiao Tong University

    CERN Document Server

    Elsied, Ahmed M M; Li, Song; Mirzaie, Mohammad; Sokollik, Thomas; Zhang, Jie

    2014-01-01

    At Shanghai Jiao Tong University, we have established a research laboratory for advanced acceleration research based on high-power lasers and plasma technologies. In a primary experiment based on the laser wakefield acceleration (LWFA) scheme, multi-hundred MeV electron beams having a reasonable quality are generated using 20-40 TW, 30 femtosecond laser pulses interacting independently with helium, neon, nitrogen and argon gas jet targets. The laser-plasma interaction conditions are optimized for stabilizing the electron beam generation from each type of gas. The electron beam pointing angle stability and divergence angle as well as the energy spectra from each gas jet are measured and compared.

  2. Modeling of high efficiency solar cells under laser pulse for power beaming applications

    Science.gov (United States)

    Jain, Raj K.; Landis, Geoffrey A.

    1994-09-01

    Solar cells have been used to convert sunlight to electrical energy for many years and also offer great potential for non-solar energy conversion applications. Their greatly improved performance under monochromatic light compared to sunlight, makes them suitable as photovoltaic (PV) receivers in laser power beaming applications. Laser beamed power to a PV array receiver could provide power to satellites, an orbital transfer vehicle, or a lunar base. Gallium arsenide (GaAs) and indium phosphide (InP) solar cells have calculated efficiencies of more than 50 percent under continuous illumination at the optimum wavelength. Currently high power free-electron lasers are being developed which operate in pulsed conditions. Understanding cell behavior under a laser pulse is important in the selection of the solar cell material and the laser. An experiment by NAsA lewis and JPL at the AVLIS laser facility in Livermore, CA presented experimental data on cell performance under pulsed laser illumination. Reference 5 contains an overview of technical issues concerning the use of solar cells for laser power conversion, written before the experiments were performed. As the experimental results showed, the actual effects of pulsed operation are more complicated. Reference 6 discusses simulations of the output of GaAs concentrator solar cells under pulsed laser illumination. The present paper continues this work, and compares the output of Si and GaAs solar cells.

  3. Multi-electron beam system for high resolution electron beam induced deposition

    OpenAIRE

    Van Bruggen, M.J.

    2008-01-01

    The development of a multi-electron beam system is described which is dedicated for electron beam induced deposition (EBID) with sub-10 nm resolution. EBID is a promising mask-less nanolithography technique which has the potential to become a viable technique for the fabrication of 20-2 nm structures after 2013, as described by the International Technology Roadmap for Semiconductors (ITRS), or can be used for rapid prototyping in research applications. The key point is to combine the throughp...

  4. Development of High Performance Electron Beam Switching System for Swiss Free Electron Laser at PSI

    CERN Document Server

    Paraliev, M

    2012-01-01

    A compact X-ray Free Electron Laser (SwissFEL) is under development at the Paul Scherrer Institute. To increase facility efficiency the main linac will operate in two electron bunch mode. The two bunches are separated in time by 28 ns and sent to two undulator lines. The combination of two beam lines should produce short X-ray pulses covering wavelength range from 1 to 70 {\\AA} with submicron position stability. To separate the two bunches, a novel electron beam switching system is being developed. The total deflection is achieved with a combination of high Q-factor resonant deflector magnet, followed by a DC septum magnet. The shot-to-shot deflection stability of the entire switching system should be <+/-10 ppm in amplitude and +/-100 ps in time, values which present severe measurement difficulties. Deflection magnets requirements, development and results of the kicker prototype are presented.

  5. Substrate heating measurements in pulsed ion beam film deposition

    Energy Technology Data Exchange (ETDEWEB)

    Olson, J.C.; Davis, H.A.; Rej, D.J.; Waganaar, W.J. [Los Alamos National Lab., NM (United States); Tallant, D.R. [Cornell Univ., Ithaca, NY (United States). Materials Science and Engineering Dept.; Thompson, M.O. [Sandia National Labs., Albuquerque, NM (United States)

    1995-05-01

    Diamond-like Carbon (DLC) films have been deposited at Los Alamos National Laboratory by pulsed ion beam ablation of graphite targets. The targets were illuminated by an intense beam of hydrogen, carbon, and oxygen ions at a fluence of 15-45 J/cm{sup 2}. Ion energies were on the order of 350 keV, with beam current rising to 35 kA over a 400 ns ion current pulse. Raman spectra of the deposited films indicate an increasing ratio of sp{sup 3} to sp{sup 2} bonding as the substrate is moved further away from the target and further off the target normal. Using a thin film platinum resistor at varying positions, we have measured the heating of the substrate surface due to the kinetic energy and heat of condensation of the ablated material. This information is used to determine if substrate heating is responsible for the lack of DLC in positions close to the target and near the target normal. Latest data and analysis will be presented.

  6. Electron beam analysis of particulate cometary material

    Science.gov (United States)

    Bradley, John

    1989-01-01

    Electron microscopy will be useful for characterization of inorganic dust grains in returned comet nucleus samples. The choice of instrument(s) will depend primarily on the nature of the samples, but ultimately a variety of electron-beam methods could be employed. Scanning and analytical (transmission) electron microscopy are the logical choise for morphological, mineralogical, and bulk chemical analyses of dust grains removed from ices. It may also be possible to examine unmelted ice/dust mixtures using an environmental scanning electron microscope equipped with a cryo-transfer unit and a cold stage. Electron microscopic observations of comet nuclei might include: (1) porosities of dust grains; (2) morphologies and microstructures of individual mineral grains; (3) relative abundances of olivine, pyroxene, and glass; and (4) the presence of phases that might have resulted from aqueous alteration (layer silicates, carbonates, sulfates).

  7. Simulation on the Pulsed Beam Transport for Injection Line of CYCIAE-10

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    1 Introduction The development of a 40 keV, 18 mA multi-cusp H- ion source and beam pulsing system have been completed successfully at CIAE. The pulsed H- beam with a repetition rate of 4.4 MHz and a pulse length of 9.6 ns has been obtained. In order to

  8. A high current, short pulse electron source for wakefield accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Ching-Hung

    1992-12-31

    Design studies for the generation of a high current, short pulse electron source for the Argonne Wakefield Accelerator are presented. An L-band laser photocathode rf gun cavity is designed using the computer code URMEL to maximize the electric field on the cathode surface for fixed frequency and rf input power. A new technique using a curved incoming laser wavefront to minimize the space charge effect near the photocathode is studied. A preaccelerator with large iris to minimize wakefield effects is used to boost the drive beam to a useful energy of around 20 MeV for wakefield acceleration experiments. Focusing in the photocathode gun and the preaccelerator is accomplished with solenoids. Beam dynamics simulations throughout the preaccelerator are performed using particle simulation codes TBCI-SF and PARMELA. An example providing a useful set of operation parameters for the Argonne Wakefield Accelerator is given. The effects of the sagitta of the curved beam and laser amplitude and timing jitter effects are discussed. Measurement results of low rf power level bench tests and a high power test for the gun cavity are presented and discussed.

  9. A high current, short pulse electron source for wakefield accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Ching-Hung.

    1992-01-01

    Design studies for the generation of a high current, short pulse electron source for the Argonne Wakefield Accelerator are presented. An L-band laser photocathode rf gun cavity is designed using the computer code URMEL to maximize the electric field on the cathode surface for fixed frequency and rf input power. A new technique using a curved incoming laser wavefront to minimize the space charge effect near the photocathode is studied. A preaccelerator with large iris to minimize wakefield effects is used to boost the drive beam to a useful energy of around 20 MeV for wakefield acceleration experiments. Focusing in the photocathode gun and the preaccelerator is accomplished with solenoids. Beam dynamics simulations throughout the preaccelerator are performed using particle simulation codes TBCI-SF and PARMELA. An example providing a useful set of operation parameters for the Argonne Wakefield Accelerator is given. The effects of the sagitta of the curved beam and laser amplitude and timing jitter effects are discussed. Measurement results of low rf power level bench tests and a high power test for the gun cavity are presented and discussed.

  10. Experimental investigation of a 1 kA/cm² sheet beam plasma cathode electron gun.

    Science.gov (United States)

    Kumar, Niraj; Pal, Udit Narayan; Pal, Dharmendra Kumar; Prajesh, Rahul; Prakash, Ram

    2015-01-01

    In this paper, a cold cathode based sheet-beam plasma cathode electron gun is reported with achieved sheet-beam current density ∼1 kA/cm(2) from pseudospark based argon plasma for pulse length of ∼200 ns in a single shot experiment. For the qualitative assessment of the sheet-beam, an arrangement of three isolated metallic-sheets is proposed. The actual shape and size of the sheet-electron-beam are obtained through a non-conventional method by proposing a dielectric charging technique and scanning electron microscope based imaging. As distinct from the earlier developed sheet beam sources, the generated sheet-beam has been propagated more than 190 mm distance in a drift space region maintaining sheet structure without assistance of any external magnetic field.

  11. Electron beam throughput from raster to imaging

    Science.gov (United States)

    Zywno, Marek

    2016-12-01

    Two architectures of electron beam tools are presented: single beam MEBES Exara designed and built by Etec Systems for mask writing, and the Reflected E-Beam Lithography tool (REBL), designed and built by KLA-Tencor under a DARPA Agreement No. HR0011-07-9-0007. Both tools have implemented technologies not used before to achieve their goals. The MEBES X, renamed Exara for marketing purposes, used an air bearing stage running in vacuum to achieve smooth continuous scanning. The REBL used 2 dimensional imaging to distribute charge to a 4k pixel swath to achieve writing times on the order of 1 wafer per hour, scalable to throughput approaching optical projection tools. Three stage architectures were designed for continuous scanning of wafers: linear maglev, rotary maglev, and dual linear maglev.

  12. Disabling CNT Electronic Devices by Use of Electron Beams

    Science.gov (United States)

    Petkov, Mihail

    2008-01-01

    Bombardment with tightly focused electron beams has been suggested as a means of electrically disabling selected individual carbon-nanotubes (CNTs) in electronic devices. Evidence in support of the suggestion was obtained in an experiment in which a CNT field-effect transistor was disabled (see figure) by focusing a 1-keV electron beam on a CNT that served as the active channel of a field-effect transistor (FET). Such bombardment could be useful in the manufacture of nonvolatile-memory circuits containing CNT FETs. Ultimately, in order to obtain the best electronic performances in CNT FETs and other electronic devices, it will be necessary to fabricate the devices such that each one contains only a single CNT as an active element. At present, this is difficult because there is no way to grow a single CNT at a specific location and with a specific orientation. Instead, the common practice is to build CNTs into electronic devices by relying on spatial distribution to bridge contacts. This practice results in some devices containing no CNTs and some devices containing more than one CNT. Thus, CNT FETs have statistically distributed electronic characteristics (including switching voltages, gains, and mixtures of metallic and semiconducting CNTs). According to the suggestion, by using a 1-keV electron beam (e.g., a beam from a scanning electron microscope), a particular nanotube could be rendered electrically dysfunctional. This procedure could be repeated as many times as necessary on different CNTs in a device until all of the excess CNTs in the device had been disabled, leaving only one CNT as an active element (e.g., as FET channel). The physical mechanism through which a CNT becomes electrically disabled is not yet understood. On one hand, data in the literature show that electron kinetic energy >86 keV is needed to cause displacement damage in a CNT. On the other hand, inasmuch as a 1-keV beam focused on a small spot (typically a few tens of nanometers wide

  13. Electron beam generation from semiconductor photocathodes

    Science.gov (United States)

    Arneodo, F.; Cavanna, F.; De Mitri, I.; Mazza, D.; Nassisi, V.

    2001-01-01

    Several measurements on a variety of semiconductor photocathodes were performed in order to determine their photoelectric quantum efficiency. Two different excimer lasers (XeCl and KrCl) and a pulsed Xe lamp were used as light sources for electron photoextraction from doped and undoped samples of cadmiun telluride, indium antimonide, and indium phosphide. Large current densities were obtained up to the limit of the Child-Langmuir law. This suggests the use of these materials for the production of intense electron sources, which could also be used for purity measurements of noble liquids.

  14. Study on local vacuum electron beam welding of flange rim

    CERN Document Server

    He Cheng Dan; Ying Lei; Xu Qi Jin

    2002-01-01

    Local vacuum electron beam welding and its application prospect in military and civil industry are introduced. A home made local vacuum electron beam welding is completed. Its main technical parameters and key techniques are also presented

  15. Electron beam flue gas treatment process. Review

    Energy Technology Data Exchange (ETDEWEB)

    Honkonen, V.A. [Kuopio Univ. (Finland). Dept. of Physics; Chmielewski, A.G. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland)

    1996-12-31

    The basis of the process for electron beam flue gas treatment are presented in the report. In tabular form the history of the research is reviewed. Main dependences of SO{sub 2} and NO{sub x} removal efficiencies on different physico-chemical parameters are discussed. Trends concerning industrial process implementation are presented in the paper,finally. (author). 74 refs, 11 figs, 1 tab.

  16. Helical relativistic electron beam and THz radiation

    CERN Document Server

    Son, S

    2011-01-01

    A THz laser generation utilizing a helical relativistic electron beam propagating through a strong magnetic field is discussed. The initial amplification rate in this scheme is much stronger than that in the conventional free electron laser. A magnetic field of the order of Tesla can yield a radiation in the range of 0.5 to 3 THz, corresponding to the total energy of mJ and the duration of tens of pico-second, or the temporal power of the order of GW.

  17. Electron beam niobium oxide powder deposition

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, D.S. [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil); Nono, M.C.A. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil); Silva, C.R.M. [Universidade de Brasilia (UnB), Brasilia, DF (Brazil)

    2009-07-01

    Full text: Zirconium oxide applied by Electron Beam –Physical Vapor Deposition can produce high quality coatings for high temperature blades. In this work niobium, yttrium and zirconium oxides were applied on metallic substrates, using EB-PVD, aiming thermal conductivity reduction. Coating characterization has been performed by X-ray diffractometry and scanning electron microscopy. X-ray diffractometry shows only tetragonal phase for the composition range evaluated, with tetragonality increase for higher niobium oxide amounts. Higher amounts of niobium promote reduction of ceramic coating theoretical density and thermal conductivity. (author)

  18. The physics of Electron Beam Ion Sources

    Energy Technology Data Exchange (ETDEWEB)

    Stockli, M.P.; Cocke, C.L.

    1990-01-01

    There are 13 Electron Beam Ion Sources in operation which produce highly charged ions, up to Th[sup 80+] and Xe[sup 53+]. Most of the sources are used to study these ions under electron impact or when recombining with gaseous or solid targets. That provides an insight into the atomic physics of these highly charged ions and into the physics of the plasma in which such ions can be found. This paper reviews the present knowledge of atomic processes, important in the production of such ions with an EBIS.

  19. The physics of Electron Beam Ion Sources

    Energy Technology Data Exchange (ETDEWEB)

    Stockli, M.P.; Cocke, C.L.

    1990-12-31

    There are 13 Electron Beam Ion Sources in operation which produce highly charged ions, up to Th{sup 80+} and Xe{sup 53+}. Most of the sources are used to study these ions under electron impact or when recombining with gaseous or solid targets. That provides an insight into the atomic physics of these highly charged ions and into the physics of the plasma in which such ions can be found. This paper reviews the present knowledge of atomic processes, important in the production of such ions with an EBIS.

  20. Limitations of electron beam conditioning for free-electron lasers

    Directory of Open Access Journals (Sweden)

    P. Emma

    2003-03-01

    Full Text Available Several ideas have been proposed to “condition” an electron beam prior to the undulator of a free-electron laser (FEL by increasing each particle’s energy in proportion to the square of its transverse betatron amplitude. This conditioning enhances FEL gain by reducing the axial velocity spread within the electron bunch. We demonstrate that for symplectic beam lines, and independent of the method, this conditioning is always accompanied by a large head-tail focusing variation which, for short-wavelength FELs, is so severe as to make conditioning completely impractical. We furthermore find that any system added to correct the head-tail focusing variation will also remove the conditioning. As an example, a new method for conditioning is presented and shown to generate exactly the same head-tail focusing problems as in previously published work.

  1. Requirements on the LWFA electron beam for the user-oriented photon source

    Science.gov (United States)

    Molodozhentsev, Alexander; Přibyl, Lukáš; Korn, Georg; Winkler, Paul; Maier, Andreas R.

    2017-05-01

    The laser-driven Undulator X-ray source (LUX) is designed to be a user beamline providing ultra-short EUV photon pulses with a central wavelength tuneable in the range of 0.4 to 4.5 nm and a peak brilliance of up to 1021 photons/(s.mrad2.mm2.0.1% B.W.), which makes this source comparable with modern synchrotron sources. The source shall provide a focal spot size well below 10 μm and a range of auxiliary beams for complex pump-and-probe experiments and it is also an important experimental milestone towards a future laser driven Free Electron Laser. Unique femtosecond nature of the laser-plasma electron acceleration in combination with extremely small transverse emittance of the electron beam is the major advantage of the LWFA technique. Preservation of the electron beam quality is a complicated task for a dedicated electron beam line, which has to be designed to transport the electron beam from the LWFA source up to the undulator. In this report we discuss main requirements on the LWFA source and the electron beam optics of the LUX source and solutions to produce required quality photon beam in the undulator and we also discuss the effect of realistic setup parameters on the quality of the electron beam in the undulator within the range of systematic errors.

  2. Effects of electron beam irradiation on tin dioxide gas sensors

    Indian Academy of Sciences (India)

    Zheng Jiao; Xiaojuan Wan; Bing Zhao; Huijiao Guo; Tiebing Liu; Minghong Wu

    2008-02-01

    In this paper, the effects of electron beam irradiation on the gas sensing performance of tin dioxide thin films toward H2 are studied. The tin dioxide thin films were prepared by ultrasonic spray pyrolysis. The results show that the sensitivity increased after electron beam irradiation. The electron beam irradiation effects on tin dioxide thin films were simulated and the mechanism was discussed.

  3. Obtaining attosecond x-ray pulses using a self-amplified spontaneous emission free electron laser

    Directory of Open Access Journals (Sweden)

    A. A. Zholents

    2005-05-01

    Full Text Available We describe a technique for the generation of a solitary attosecond x-ray pulse in a free-electron laser (FEL, via a process of self-amplified spontaneous emission. In this method, electrons experience an energy modulation upon interacting with laser pulses having a duration of a few cycles within single-period wiggler magnets. Two consecutive modulation sections, followed by compression in a dispersive section, are used to obtain a single, subfemtosecond spike in the electron peak current. This region of the electron beam experiences an enhanced growth rate for FEL amplification. After propagation through a long undulator, this current spike emits a ∼250   attosecond x-ray pulse whose intensity dominates the x-ray emission from the rest of the electron bunch.

  4. Phase and amplitude stability of a pulsed RF system on the example of the CLIC drive beam LINAC

    CERN Document Server

    AUTHOR|(CDS)2132320; Prof. BANTEL, Michael

    The CLIC drive beam accelerator consists of the Drive Beam Injector (DBI) and two Drive Beam Linacs (DBLs). The drive beam injector is composed of a thermionic electron source, 3 Sub Harmonic Bunchers (SHBs), a pre-buncher, and several acceleration structures. In the electron source the DC electron beam is produced from a thermionic cathode. The following buncher cavities group ("bunch") the electrons to be accelerated by RF later on. Each electron bunch has an energy of 140 keV, a length of 3 mm, and a charge qb = 8.4 nC. Afterwards the electrons are accelerated in the 1 GHz accelerating structures up to 50MeV. The pulsed Radio Frequency (RF) power for this acceleration is provided by 1 GHz, 20MW modulator-klystron units, one per acceleration structure. A klystron is an RF amplifier based on a linear-beam vacuum tube. The high voltage modulator supplies the acceleration voltage to this tube. A DC electron beam gets modulated with an input signal, the modulation enhances in a drift space, and finally the powe...

  5. Electron Acceleration and the Propagation of Ultrashort High-Intensity Laser Pulses in Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaofang; Krishnan, Mohan; Saleh, Ned; Wang, Haiwen; Umstadter, Donald

    2000-06-05

    Reported are interactions of high-intensity laser pulses ({lambda}=810 nm and I{<=}3x10{sup 18} W /cm{sup 2} ) with plasmas in a new parameter regime, in which the pulse duration ({tau}=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.

  6. Energy slicing analysis for time-resolved measurement of electron-beam properties

    Directory of Open Access Journals (Sweden)

    E. Allaria

    2014-01-01

    Full Text Available We present a new diagnostic method allowing one to reconstruct certain properties of a relativistic electron beam and of a laser pulse by looking at the result of their interaction. The latter takes place within an undulator and results in energy modulation of electrons. By taking advantage of the correlation between time and electron-beam energy, measurements of the electron-beam length, current and energy spread are possible simultaneously. Moreover, the scheme allows an accurate measurement of the timing jitter between the electron beam and the external laser and also of the laser’s actual pulse length at the interaction point. Experimental demonstration of the last two measurements is reported in this paper. Finally, this diagnostic method provides an independent measure of the energy transferred from the electron beam to free-electron laser light produced when seeded electrons are injected into a long undulator. Experimental results obtained at the FERMI free-electron laser are presented after a description of the proposed technique.

  7. Electronics and Calibration system for the CMS Beam Halo Monitor

    CERN Document Server

    Tosi, Nicolo

    2014-01-01

    In the context of increasing luminosity of LHC, it will be important to accurately measure the Machine Induced Background. A new monitoring system will be installed in the CMS cavern for measuring the beam background at high radius. This detector is composed of synthetic quartz Cherenkov radiators, coupled to fast photomultiplier tubes (PMT). The readout chain of this detector will make use of many components developed for the Phase 1 upgrade to the CMS Hadron Calorimeter electronics, with a dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal will be digitized by a charge integrating ASIC (QIE10), providing both the signal rise time and the charge integrated over one bunch crossing.The backend electronics will record bunch-by-bunch histograms, which will be published to CMS and the LHC using the newly designed CMS beam instrumentation specific DAQ. A calibration monitoring system has been designed to generate triggered pulses of light to monitor the efficiency of the sys...

  8. Multi-beam-bulk model for electron transport during commutation in an optically triggered pseudospark thyratron

    Science.gov (United States)

    Pak, Hoyoung; Kushner, Mark J.

    1990-10-01

    The electron energy distribution in low-pressure pulsed power plasma switches is typically not in equilibrium with the local electric field. To simulate electron transport under these conditions a computer model has been developed and has been applied to the optically triggered pseudospark, or back-lit-thyratron (BLT). The model uses many groups of electrons divided into the ``bulk'' and the ``beam''. The bulk is represented by a fluid while the beam electrons are ballistic in nature and have not undergone significant energy-loss collisions after generation. To account for beam electrons being generated at arbitrary locations in the BLT, multiple beams are employed in the model. The commutation phase of switching in the BLT is investigated and the onset of a hollow cathode effect during switching is predicted.

  9. Effective NOx remediation from a surrogate flue gas using the US NRL Electra electron beam facility

    Science.gov (United States)

    Petrova, Tz. B.; Petrov, G. M.; Wolford, M. F.; Giuliani, J. L.; Ladouceur, H. D.; Hegeler, F.; Myers, M. C.; Sethian, J. D.

    2017-02-01

    Nitric oxide (NOx) emission is under restrictive federal regulations because of its negative impact on atmosphere, biosphere, and human health. Therefore, its removal has been a subject of extensive research to develop new efficient and cost effective techniques that can be applied on an industrial scale. In this work, we study both experimentally and theoretically an effective removal of NOx pollutants from a surrogate flue gas (SFG) using high power electron beam (e-beam) pulses. SFG is a simulant for exhaust from coal combustion power plants (82% N2, 6% O2, 12% CO2, and ˜100 ppm of NOx). The pulsed electron beam is generated using the United States Naval Research Laboratory Electra facility, which delivers e-beams with energies of ˜500 keV and a power pulse duration of ˜140 ns. During the e-beam irradiation, the energetic electrons generate a non-equilibrium plasma containing chemically active species, which then react with NOx to form harmless substances. A non-equilibrium time-dependent model is developed to describe NOx remediation from SFG. The model combines e-beam deposition rates obtained by solving the electron Boltzmann equation and extensive plasma chemistry modeling, which follows the species on a time scale from sub-nanoseconds to a few seconds. NOx decomposition as a function of electron beam parameters is studied. It is demonstrated experimentally that short (ns) pulses are the most efficient for NOx removal. A sharp reduction of NOx was measured with e-beam power deposition increasing, following the trend predicted by the model, achieving a 20 fold reduction to ˜5 ppm at energy deposition ˜20 J/l.

  10. First test of BNL electron beam ion source with high current density electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Pikin, Alexander, E-mail: pikin@bnl.gov; Alessi, James G., E-mail: pikin@bnl.gov; Beebe, Edward N., E-mail: pikin@bnl.gov [Brookhaven National Laboratory, Upton, NY 11973 (United States); Shornikov, Andrey; Mertzig, Robert; Wenander, Fredrik; Scrivens, Richard [CERN, CH-1211 Geneva 23 (Switzerland)

    2015-01-09

    A new electron gun with electrostatic compression has been installed at the Electron Beam Ion Source (EBIS) Test Stand at BNL. This is a collaborative effort by BNL and CERN teams with a common goal to study an EBIS with electron beam current up to 10 A, current density up to 10,000 A/cm{sup 2} and energy more than 50 keV. Intensive and pure beams of heavy highly charged ions with mass-to-charge ratio < 4.5 are requested by many heavy ion research facilities including NASA Space Radiation Laboratory (NSRL) at BNL and HIE-ISOLDE at CERN. With a multiampere electron gun, the EBIS should be capable of delivering highly charged ions for both RHIC facility applications at BNL and for ISOLDE experiments at CERN. Details of the electron gun simulations and design, and the Test EBIS electrostatic and magnetostatic structures with the new electron gun are presented. The experimental results of the electron beam transmission are given.

  11. Simulation of the Beam Dump for a High Intensity Electron Gun

    CERN Document Server

    Doebert, S; Lefevre, T; Pepitone, K

    2014-01-01

    The CLIC Drive Beam is a high-intensity pulsed electron beam. A test facility for the Drive Beam electron gun will soon be commissioned at CERN. In this contribution we outline the design of a beam dump / Faraday cup capable of resisting the beam’s thermal load. The test facility will operate initially up to 140 keV. At such low energies, the electrons are absorbed very close to the surface of the dump, leading to a large energy deposition density in this thin layer. In order not to damage the dump, the beam must be spread over a large surface. For this reason, a small-angled cone has been chosen. Simulations using Geant4 have been performed to estimate the distribution of energy deposition in the dump. The heat transport both within the electron pulse and between pulses has been modelled using finite element methods to check the resistance of the dump at high repetition rates. In addition, the possibility of using a moveable dump to measure the beam profile and emittance is discussed.

  12. The Electron Trajectory in a Relativistic Femtosecond Laser Pulse

    Institute of Scientific and Technical Information of China (English)

    He Feng; Yu Wei; Lu Peixiang; Xu Han; Shen Baifei; Li Ruxin; Xu Zhizhan

    2005-01-01

    In this report, we start from Lagrange equation and analyze theoretically the electron dynamics in electromagnetic field. By solving the relativistic government equations of electron,the trajectories of an electron in plane laser pulse, focused laser pulse have been given for different initial conditions. The electron trajectory is determined by its initial momentum, the amplitude,spot size and polarization of the laser pulse. The optimum initial momentum of the electron for LSS (laser synchrotron source) is obtained. Linear polarized laser is more advantaged than circular polarized laser for generating harmonic radiation.

  13. Generation of high energy and good beam quality pulses with a master oscillator power amplifier

    Institute of Scientific and Technical Information of China (English)

    Zhigang Li(李志刚); Z.Xiong; Nicholas Moore; Chen Tao; G.C.Lim; Weiling Huang(黄维玲); Dexiu Huang(黄德修)

    2004-01-01

    A high efficiency and high peak power laser system with short-pulse and good beam quality has been demonstrated by using a master oscillator power amplifier with two-pass amplification configuration. The master oscillator, end-pumped with a fiber-coupled laser diode array, provides low power but excellent beam quality pulses, and the amplifier boosts the pulse energy by orders without significant beam quality degradation. Short pulses of 8.5 ns with energy up to 130 mJ and approximately diffraction limited beam quality have been demonstrated.

  14. Nanosecond discharge in sulfur hexafluoride and the generation of an ultrashort avalanche electron beam

    Science.gov (United States)

    Baksht, E. Kh.; Burachenko, A. G.; Erofeev, M. V.; Lomaev, M. I.; Rybka, D. V.; Sorokin, D. A.; Tarasenko, V. F.

    2008-06-01

    A discharge in the presence of a nonuniform electric field and the generation of an ultrashort avalanche electron beam (UAEB) are studied in the insulating gas SF6 at the pressures 0.01 2.50 atm. High-voltage nanosecond pulses (about 150 and 250 kV) and the voltage pulses with an amplitude of 25 kV and a duration of tens of nanoseconds are applied across the gap. An electron beam is obtained behind the AlBe foil with a thickness of 45 μm at a sulfur hexafluoride pressure in a gas-filled diode of up to 2 atm. It is demonstrated that, at relatively high pressures (greater than 1 atm) and in the presence of high-voltage nanosecond pulses across the gap, the UAEB pulse FWHM increases. The spectra of the diffuse and contracted discharges in sulfur hexafluoride are measured.

  15. A two-dose-rate method for general recombination correction for liquid ionization chambers in pulsed beams

    Energy Technology Data Exchange (ETDEWEB)

    Toelli, Heikki; Sjoegren, Rickard; Wendelsten, Mikael, E-mail: heikki.tolli@radfys.umu.s [Department of Radiation Sciences, Radiation Physics, Umeaa University, SE-901 85 Umeaa (Sweden)

    2010-08-07

    The correction for general recombination losses in liquid ionization chambers (LICs) is more complex than that in air-filled ionization chambers. The reason for this is that the saturation charge in LICs, i.e. the charge that escapes initial recombination, depends on the applied voltage. This paper presents a method, based on measurements at two different dose rates in a pulsed beam, for general recombination correction in LICs. The Boag theory for pulsed beams is used and the collection efficiency is determined by numerical methods which are equivalent to the two-voltage method used in dosimetry with air-filled ionization chambers. The method has been tested in experiments in water in a 20 MeV electron beam using two LICs filled with isooctane and tetramethylsilane. The dose per pulse in the electron beam was varied between 0.1 mGy/pulse and 8 mGy/pulse. The relative standard deviations of the collection efficiencies determined with the two-dose-rate method ranged between 0.1% and 1.5%. The dose-rate variations of the general recombination corrected charge measured with the LICs are in excellent agreement with the corresponding values obtained with an air-filled plane parallel ionization chamber.

  16. Understanding the ATLAS electromagnetic barrel pulse shapes and the absolute electronic calibration

    CERN Document Server

    Neukermans, L; Zitoun, R

    2001-01-01

    We present an original method to undestand the calibration and physics pulse shapes collected in the 2000 barrel test beam runs with the prototype module. It is based on an electrical description of the calorimeter and its electronics. It allows an understanding of the physics pulse shapes and its absolute calibration (in microA/ADC) to a very good level of accuracy with a small number of parameters (capacitances and inductances). The electrical parameters found by this method agree with the direct measurements independantly performed on the prototype module. Optimal filtering coefficients can then be derived from these physics pulse shape predictions, and more crucial, an absolute electronic calibration. These coefficients are released in the official test beam software EMTB.

  17. An electromagnetically focused electron beam line source

    Science.gov (United States)

    Iqbal, Munawar; Masood, Khalid; Rafiq, Mohammad; Chaudhary, Maqbool A.; Aleem, Fazal-e.-

    2003-11-01

    A directly heated thermionic electron beam source was constructed. A tungsten wire of length 140 mm with diameter 0.9 mm was used as a cathode. An emission current of 5000 mA was achieved at an input heating power of 600 W. Cathode to anode distance of 6 mm with acceleration voltage of 10 kV was used. A uniform external magnetic field of 50 G was employed to obtain a well-focused electron beam at a deflection of 180°, with cathode to work site distance of 130 mm. Dimensions of the beam (1.25×120 mm) recorded at the work site were found to be in good agreement with the designed length of cathode. The deformation of the cathode was overcome by introducing a spring action mechanism, which gives uniform emission current density throughout the emission surface. We have achieved the saturation limit of the designed source resulting in smooth and swift operation of the gun for many hours (10-15 h continuously). The design of gun is so simple that it can accommodate longer cathodes for obtaining higher emission values. This gun has made it possible to coat large substrate surfaces at much faster evaporation rate at lower cost. It can also be useful in large-scale vacuum metallurgy plants for melting, welding and heat treatment.

  18. Control of Electron Beam Using Strong Magnetic Field for Efficient Core Heating in Fast Ignition

    CERN Document Server

    Johzaki, T; Sentoku, Y; Sunahara, A; Nagatomo, H; Sakagami, H; Mima, K; Fujioka, S; Shiraga, H

    2014-01-01

    For enhancing the core heating efficiency in electron-driven fast ignition, we proposed the fast electron beam guiding using externally applied longitudinal magnetic fields. Based on the PIC simulations for the FIREX-class experiments, we demonstrated the sufficient beam guiding performance in the collisional dense plasma by kT-class external magnetic fields for the case with moderate mirror ratio (~<10 ). Boring of the mirror field was found through the formation of magnetic pipe structure due to the resistive effects, which indicates a possibility of beam guiding in high mirror field for higher laser intensity and/or longer pulse duration.

  19. Submillimeter-resolution radiography of shielded structures with laser-accelerated electron beams

    Directory of Open Access Journals (Sweden)

    Vidya Ramanathan

    2010-10-01

    Full Text Available We investigate the use of energetic electron beams for high-resolution radiography of flaws embedded in thick solid objects. A bright, monoenergetic electron beam (with energy >100  MeV was generated by the process of laser-wakefield acceleration through the interaction of 50-TW, 30-fs laser pulses with a supersonic helium jet. The high energy, low divergence, and small source size of these beams make them ideal for high-resolution radiographic studies of cracks or voids embedded in dense materials that are placed at a large distance from the source. We report radiographic imaging of steel with submillimeter resolution.

  20. 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.

  1. Effect of electron beam on structural, linear and nonlinear properties of nanostructured Fluorine doped ZnO thin films

    Science.gov (United States)

    Antony, Albin; Pramodini, S.; Kityk, I. V.; Abd-Lefdil, M.; Douayar, A.; Cherkaoui El Moursli, F.; Sanjeev, Ganesh; Manjunatha, K. B.; Poornesh, P.

    2017-10-01

    Electron beam induced effects on Fluorine doped ZnO thin films (FZO) grown by chemical spray pyrolysis deposition technique were studied. The samples were exposed to 8 MeV electron beam at different dose rate ranging from 1 kGy to 4 kGy. All films exhibit a polycrystalline nature which shows an increase in crystallanity with irradiation dosages. The electron beam irradiation effectively controls the films surface morphology and its linear optical characteristics. Z-Scan technique was employed to evaluate the sign and magnitude of nonlinear refractive index and nonlinear absorption coefficient using a continuous wave laser at 632.8 nm as light source. Enhancement in the third order nonlinear optical properties was were noted due to electron beam irradiation. Tailoring the physical and NLO properties by electron beam, the FZO thin films becomes a promising candidate for various optoelectronic applications such as phase change memory devices, optical pulse compression, optical switching and laser pulse narrowing.

  2. An Electron-Beam Controlled Semiconductor Switch

    Science.gov (United States)

    1989-11-01

    of the Seventeenth Power Modulator Symposium, Seattle, WA, pp. 214-218. 1986. 21. Bovino , L., ’ioumans,R., Weiner, H., Burke, T . , "Optica lly... Bovino , R. Youmans, M. Weiner, and T. Burke, ’ ’Optically Co ntrolled Semiconducto r Switch for ~lulti-~legawatt Rep-Rated Pulse r s ," Conf. Record...p. 615. (II 1 W. N. Carr, IEEE Trans. Electron Devices, vol. ED-12, p. 531 , 1965. (121 T. Burke, M. Weiner. L. Bovino , and R. Youmans, in Proc

  3. Pyroelectric materials as electronic pulse detectors of ultraheavy nuclei

    Science.gov (United States)

    Simpson, J. A.; Tuzzolino, A. J.

    1984-01-01

    The design and testing of ultraheavy-nucleus pulse detectors based on pyroelectric materials are reported, extending the preliminary findings of Tuzzolino (1983) and Simpson and Tuzzolino (1983). Uranium-ion beams of about 240 MeV/u are detected by a 39.5-micron-thick Si detector, degraded to about 175 MeV/u by Al absorbers, and then strike 700-micron-thick polyvinylidene fluoride or 1000-micron-thick LiTaO3 pyroelectric samples. Both detector systems are connected to a coincidence circuit via charge-sensitive preamplifiers, shaping amplifiers with 30-microsec effective time constants, and electronic discriminators. Sample spectra are shown, and the pulse heights measured are found to agree with theoretical calculations to within a factor of about 2. The response of the pyroelectric materials is found to be unaffected by exposure to about 10 Mrad of 2-7-MeV/u heavy ion radiation. With further study and improvement of the detection sensitivity, devices of this type could be applied to large-area space measurements of low ultraheavy-ion fluxes.

  4. The CMS Beam Halo Monitor Electronics

    CERN Document Server

    AUTHOR|(CDS)2080684; Fabbri, F.; Grassi, T.; Hughes, E.; Mans, J.; Montanari, A.; Orfanelli, S.; Rusack, R.; Torromeo, G.; Stickland, D.P.; Stifter, K.

    2016-01-01

    The CMS Beam Halo Monitor has been successfully installed in the CMS cavern in LHC Long Shutdown 1 for measuring the machine induced background for LHC Run II. The system is based on 40 detector units composed of synthetic quartz Cherenkov radiators coupled to fast photomultiplier tubes. The readout electronics chain uses many components developed for the Phase 1 upgrade to the CMS Hadronic Calorimeter electronics, with dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal is digitized by a charge integrating ASIC (QIE10), providing both the signal rise time, with few ns resolution, and the charge integrated over one bunch crossing. The backend electronics uses microTCA technology and receives data via a high-speed 5 Gbps asynchronous link. It records histograms with sub-bunch crossing timing resolution and is readout by IPbus using the newly designed CMS data acquisition for non-event based data. The data is processed in real time and published to CMS and the LHC, providi...

  5. Purification of Niobium by Electron Beam Melting

    Science.gov (United States)

    Sankar, M.; Mirji, K. V.; Prasad, V. V. Satya; Baligidad, R. G.; Gokhale, A. A.

    2016-06-01

    Pure niobium metal, produced by alumino-thermic reduction of niobium oxide, contains various impurities which need to be reduced to acceptable levels to obtain aerospace grade purity. In the present work, an attempt has been made to refine niobium metals by electron beam drip melting technique to achieve purity confirming to the ASTM standard. Input power to the electron gun and melt rate were varied to observe their combined effect on extend of refining and loss of niobium. Electron beam (EB) melting is shown to reduce alkali metals, trace elements and interstitial impurities well below the specified limits. The reduction in the impurities during EB melting is attributed to evaporation and degassing due to the combined effect of high vacuum and high melt surface temperature. The % removal of interstitial impurities is essentially a function of melt rate and input power. As the melt rate decreases or input power increases, the impurity levels in the solidified niobium ingot decrease. The EB refining process is also accompanied by considerable amount of niobium loss, which is attributed to evaporation of pure niobium and niobium sub-oxide. Like other impurities, Nb loss increases with decreasing melt rate or increase in input power.

  6. Electron beam ion source and electron beam ion trap (invited)a)

    Science.gov (United States)

    Becker, Reinard; Kester, Oliver

    2010-02-01

    The electron beam ion source (EBIS) and its trap variant [electron beam ion trap (EBIT)] celebrated their 40th and 20th anniversary, respectively, at the EBIS/T Symposium 2007 in Heidelberg. These technologically challenging sources of highly charged ions have seen a broad development in many countries over the last decades. In contrast to most other ion sources the recipe of improvement was not "sorcery" but a clear understanding of the physical laws and obeying the technological constraints. This review will report important achievements of the past as well as promising developments in the future.

  7. Generation of 20 kA electron beam from a laser wakefield accelerator

    Science.gov (United States)

    Li, Y. F.; Li, D. Z.; Huang, K.; Tao, M. Z.; Li, M. H.; Zhao, J. R.; Ma, Y.; Guo, X.; Wang, J. G.; Chen, M.; Hafz, N.; Zhang, J.; Chen, L. M.

    2017-02-01

    We present the experimentally generated electron bunch from laser-wakefield acceleration (LWFA) with a charge of 620 pC and a maximum energy up to 0.6 GeV by irradiating 80 TW laser pulses at a 3 mm Helium gas jet. The charge of injected electrons is much larger than the normal scaling laws of LWFA in bubble regime. We also got a quasi-monoenergetic electron beam with energy peaked at 249 MeV and a charge of 68 pC with the similar laser conditions but lower plasma density. As confirmed by 2D particle-in-cell simulations, the boosted bunch charge is due to the continuous injection caused by the self-steepening and self-compression of a laser pulse. During the nonlinear evolution of the laser pulse, the bubble structure broadens and stretches, leading to a longer dephasing length and larger beam charge.

  8. Electron beam manipulation, injection and acceleration in plasma wakefield accelerators by optically generated plasma density spikes

    Energy Technology Data Exchange (ETDEWEB)

    Wittig, Georg; Karger, Oliver S.; Knetsch, Alexander [Institute of Experimental Physics, University of Hamburg, 22761 Hamburg (Germany); Xi, Yunfeng; Deng, Aihua; Rosenzweig, James B. [Particle Beam Physics Laboratory, UCLA, Los Angeles, CA 90095 (United States); Bruhwiler, David L. [RadiaSoft LLC, Boulder, CO 80304 (United States); RadiaBeam Technologies LLC (United States); Smith, Jonathan [Tech-X UK Ltd, Daresbury, Cheshire WA4 4FS (United Kingdom); Sheng, Zheng-Ming; Jaroszynski, Dino A.; Manahan, Grace G. [Physics Department, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Hidding, Bernhard [Institute of Experimental Physics, University of Hamburg, 22761 Hamburg (Germany); Physics Department, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2016-09-01

    We discuss considerations regarding a novel and robust scheme for optically triggered electron bunch generation in plasma wakefield accelerators [1]. In this technique, a transversely propagating focused laser pulse ignites a quasi-stationary plasma column before the arrival of the plasma wake. This localized plasma density enhancement or optical “plasma torch” distorts the blowout during the arrival of the electron drive bunch and modifies the electron trajectories, resulting in controlled injection. By changing the gas density, and the laser pulse parameters such as beam waist and intensity, and by moving the focal point of the laser pulse, the shape of the plasma torch, and therefore the generated trailing beam, can be tuned easily. The proposed method is much more flexible and faster in generating gas density transitions when compared to hydrodynamics-based methods, and it accommodates experimentalists needs as it is a purely optical process and straightforward to implement.

  9. Electron beam manipulation, injection and acceleration in plasma wakefield accelerators by optically generated plasma density spikes

    Science.gov (United States)

    Wittig, Georg; Karger, Oliver S.; Knetsch, Alexander; Xi, Yunfeng; Deng, Aihua; Rosenzweig, James B.; Bruhwiler, David L.; Smith, Jonathan; Sheng, Zheng-Ming; Jaroszynski, Dino A.; Manahan, Grace G.; Hidding, Bernhard

    2016-09-01

    We discuss considerations regarding a novel and robust scheme for optically triggered electron bunch generation in plasma wakefield accelerators [1]. In this technique, a transversely propagating focused laser pulse ignites a quasi-stationary plasma column before the arrival of the plasma wake. This localized plasma density enhancement or optical "plasma torch" distorts the blowout during the arrival of the electron drive bunch and modifies the electron trajectories, resulting in controlled injection. By changing the gas density, and the laser pulse parameters such as beam waist and intensity, and by moving the focal point of the laser pulse, the shape of the plasma torch, and therefore the generated trailing beam, can be tuned easily. The proposed method is much more flexible and faster in generating gas density transitions when compared to hydrodynamics-based methods, and it accommodates experimentalists needs as it is a purely optical process and straightforward to implement.

  10. Ultrafast imprinting of topologically protected magnetic textures via pulsed electrons

    Science.gov (United States)

    Schäffer, A. F.; Dürr, H. A.; Berakdar, J.

    2017-07-01

    Short electron pulses are demonstrated to trigger and control magnetic excitations, even at low electron current densities. We show that the tangential magnetic field surrounding a picosecond electron pulse can imprint topologically protected magnetic textures such as skyrmions in a sample with a residual Dzyaloshinskii-Moriya spin-orbital coupling. Characteristics of the created excitations such as the topological charge can be steered via the duration and the strength of the electron pulses. The study points to a possible way for a spatiotemporally controlled generation of skyrmionic excitations.

  11. Deficiencies of active electronic radiation protection dosimeters in pulsed fields.

    Science.gov (United States)

    Ankerhold, U; Hupe, O; Ambrosi, P

    2009-07-01

    Nowadays nearly all radiation fields used for X-ray diagnostics are pulsed. These fields are characterised by a high dose rate during the pulse and a short pulse duration in the range of a few milliseconds. The use of active electronic dosimeters has increased in the past few years, but these types of dosimeters might possibly not measure reliably in pulsed radiation fields. Not only personal dosimeters but also area dosimeters that are used mainly for dose rate measurements are concerned. These cannot be substituted by using passive dosimeter types. The characteristics of active electronic dosimeters determined in a continuous radiation field cannot be transferred to those in pulsed fields. Some provisional measurements with typical electronic dosimeters in pulsed radiation fields are presented to reveal this basic problem.

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

    CERN Document Server

    Hansson, Martin; Ekerfelt, Henrik; Persson, Anna; Lundh, Olle

    2016-01-01

    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 p...

  13. AREAL low energy electron beam applications in life and materials sciences

    Energy Technology Data Exchange (ETDEWEB)

    Tsakanov, V.M., E-mail: tsakanov@asls.candle.am [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Yerevan State University, 0025 Yerevan (Armenia); Aroutiounian, R.M. [Yerevan State University, 0025 Yerevan (Armenia); Amatuni, G.A. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Aloyan, L.R.; Aslanyan, L.G. [Yerevan State University, 0025 Yerevan (Armenia); Avagyan, V.Sh. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Babayan, N.S. [Yerevan State University, 0025 Yerevan (Armenia); Institute of Molecular Biology NAS, 0014 Yerevan (Armenia); Buniatyan, V.V. [State Engineering University of Armenia, 0009 Yerevan (Armenia); Dalyan, Y.B.; Davtyan, H.D. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Derdzyan, M.V. [Institute for Physical Research NAS, 0203 Ashtarak (Armenia); Grigoryan, B.A. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Grigoryan, N.E. [A.I. Alikhanyan National Science Laboratory (YerPhi), 0036 Yerevan (Armenia); Hakobyan, L.S. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Haroutyunian, S.G. [Yerevan State University, 0025 Yerevan (Armenia); Harutiunyan, V.V. [A.I. Alikhanyan National Science Laboratory (YerPhi), 0036 Yerevan (Armenia); Hovhannesyan, K.L. [Institute for Physical Research NAS, 0203 Ashtarak (Armenia); Khachatryan, V.G. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Martirosyan, N.W. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); State Engineering University of Armenia, 0009 Yerevan (Armenia); Melikyan, G.S. [State Engineering University of Armenia, 0009 Yerevan (Armenia); and others

    2016-09-01

    The AREAL laser-driven RF gun provides 2–5 MeV energy ultrashort electron pulses for experimental study in life and materials sciences. We report the first experimental results of the AREAL beam application in the study of molecular-genetic effects, silicon-dielectric structures, ferroelectric nanofilms, and single crystals for scintillators.

  14. BN coatings deposition by magnetron sputtering of B and BN targets in electron beam generated plasma

    Science.gov (United States)

    Kamenetskikh, A. S.; Gavrilov, N. V.; Koryakova, O. V.; Cholakh, S. O.

    2017-05-01

    Boron nitride coatings were deposited by reactive pulsed magnetron sputtering of B and BN targets (50 kHz, 10 µs for B; 13.56 MHz for BN) at 2-20 mA/cm2 ion current density on the substrate. The effect of electron beam generated plasma on characteristics of magnetron discharge and phase composition of coatings was studied.

  15. Space Charge Effect in the Sheet and Solid Electron Beam

    Science.gov (United States)

    Song, Ho Young; Kim, Hyoung Suk; Ahn, Saeyoung

    1998-11-01

    We analyze the space charge effect of two different types of electron beam ; sheet and solid electron beam. Electron gun simulations are carried out using shadow and control grids for high and low perveance. Rectangular and cylindrical geometries are used for sheet and solid electron beam in planar and disk type cathode. The E-gun code is used to study the limiting current and space charge loading in each geometries.

  16. Conceptual design of hollow electron lenses for beam halo control in the Large Hadron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Previtali, Valentina [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Valishev, Alexander [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Bruce, Roderik [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Redaelli, Stefano [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Rossi, Adriana [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Salvachua Ferrando, Belen [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2014-06-26

    Collimation with hollow electron beams is a technique for halo control in high-power hadron beams. It is based on an electron beam (possibly pulsed or modulated in intensity) guided by strong axial magnetic fields which overlaps with the circulating beam in a short section of the ring. The concept was tested experimentally at the Fermilab Tevatron collider using a hollow electron gun installed in one of the Tevatron electron lenses. We are proposing a conceptual design for applying this technique to the Large Hadron Collider at CERN. A prototype hollow electron gun for the LHC was built and tested. The expected performance of the hollow electron beam collimator was based on Tevatron experiments and on numerical tracking simulations. Halo removal rates and enhancements of halo diffusivity were estimated as a function of beam and lattice parameters. Proton beam core lifetimes and emittance growth rates were checked to ensure that undesired effects were suppressed. Hardware specifications were based on the Tevatron devices and on preliminary engineering integration studies in the LHC machine. Required resources and a possible timeline were also outlined, together with a brief discussion of alternative halo-removal schemes and of other possible uses of electron lenses to improve the performance of the LHC.

  17. Comparison study of in vivo dose response to laser-driven versus conventional electron beam.

    Science.gov (United States)

    Oppelt, Melanie; Baumann, Michael; Bergmann, Ralf; Beyreuther, Elke; Brüchner, Kerstin; Hartmann, Josefin; Karsch, Leonhard; Krause, Mechthild; Laschinsky, Lydia; Leßmann, Elisabeth; Nicolai, Maria; Reuter, Maria; Richter, Christian; Sävert, Alexander; Schnell, Michael; Schürer, Michael; Woithe, Julia; Kaluza, Malte; Pawelke, Jörg

    2015-05-01

    The long-term goal to integrate laser-based particle accelerators into radiotherapy clinics not only requires technological development of high-intensity lasers and new techniques for beam detection and dose delivery, but also characterization of the biological consequences of this new particle beam quality, i.e. ultra-short, ultra-intense pulses. In the present work, we describe successful in vivo experiments with laser-driven electron pulses by utilization of a small tumour model on the mouse ear for the human squamous cell carcinoma model FaDu. The already established in vitro irradiation technology at the laser system JETI was further enhanced for 3D tumour irradiation in vivo in terms of beam transport, beam monitoring, dose delivery and dosimetry in order to precisely apply a prescribed dose to each tumour in full-scale radiobiological experiments. Tumour growth delay was determined after irradiation with doses of 3 and 6 Gy by laser-accelerated electrons. Reference irradiation was performed with continuous electron beams at a clinical linear accelerator in order to both validate the dedicated dosimetry employed for laser-accelerated JETI electrons and above all review the biological results. No significant difference in radiation-induced tumour growth delay was revealed for the two investigated electron beams. These data provide evidence that the ultra-high dose rate generated by laser acceleration does not impact the biological effectiveness of the particles.

  18. Development of high current beam ns pulsed system

    CERN Document Server

    Shen Guan Ren; Gao Fu; Guan Xia Ling; LiuNaiYi

    2001-01-01

    The development of high current beam ns pulsed system of CPNG and its characteristic, main technological performance and application are introduced. Firstly, important parameters of the system are calculated using theoretical model, the design requirements of some important parts are understood. Some mistakes in physics conception are corrected. Second, the chopper is designed for parallel plate deflector, chopping aperture and sine wave voltage sweeping device. It is emphasized that the conception of parallel plate load impedance is the capacitance load, but not the 50 ohm load impedance. The dynamic capacitance value has been measured. The output emphasizes the output voltage amplitude, but not the output power for sweeping device. The display system of output sweeping voltage was set up and it is sure that the maximum output voltage(V-V) is >=4000 V. The klystron buncher are re-designed. It is emphasized to overcome difficulty of support high voltage electrode in the klystron and insulator of input sine wa...

  19. Accessing Defect Dynamics using Intense, Nanosecond Pulsed Ion Beams

    Science.gov (United States)

    Persaud, A.; Barnard, J. J.; Guo, H.; Hosemann, P.; Lidia, S.; Minor, A. M.; Seidl, P. A.; Schenkel, T.

    Gaining in-situ access to relaxation dynamics of radiation induced defects will lead to a better understanding of materials and is important for the verification of theoretical models and simulations. We show preliminary results from experiments at the new Neutralized Drift Compression Experiment (NDCX-II) at Lawrence Berkeley National Laboratory that will enable in-situ access to defect dynamics through pump-probe experiments. Here, the unique capabilities of the NDCX-II accelerator to generate intense, nanosecond pulsed ion beams are utilized. Preliminary data of channeling experiments using lithium and potassium ions and silicon membranes are shown. We compare these data to simulation results using Crystal Trim. Furthermore, we discuss the improvements to the accelerator to higher performance levels and the new diagnostics tools that are being incorporated.

  20. Electron Beam Technology for Environmental Pollution Control.

    Science.gov (United States)

    Chmielewski, Andrzej G; Han, Bumsoo

    2016-10-01

    Worldwide, there are over 1700 electron beam (EB) units in commercial use, providing an estimated added value to numerous products, amounting to 100 billion USD or more. High-current electron accelerators are used in diverse industries to enhance the physical and chemical properties of materials and to reduce undesirable contaminants such as pathogens, toxic byproducts, or emissions. Over the past few decades, EB technologies have been developed aimed at ensuring the safety of gaseous and liquid effluents discharged to the environment. It has been demonstrated that EB technologies for flue gas treatment (SO x and NO x removal), wastewater purification, and sludge hygienization can be effectively deployed to mitigate environmental degradation. Recently, extensive work has been carried out on the use of EB for environmental remediation, which also includes the removal of emerging contaminants such as VOCs, endocrine disrupting chemicals (EDCs), and potential EDCs.

  1. Focused electron beam induced deposition: A perspective

    Directory of Open Access Journals (Sweden)

    Michael Huth

    2012-08-01

    Full Text Available Background: Focused electron beam induced deposition (FEBID is a direct-writing technique with nanometer resolution, which has received strongly increasing attention within the last decade. In FEBID a precursor previously adsorbed on a substrate surface is dissociated in the focus of an electron beam. After 20 years of continuous development FEBID has reached a stage at which this technique is now particularly attractive for several areas in both, basic and applied research. The present topical review addresses selected examples that highlight this development in the areas of charge-transport regimes in nanogranular metals close to an insulator-to-metal transition, the use of these materials for strain- and magnetic-field sensing, and the prospect of extending FEBID to multicomponent systems, such as binary alloys and intermetallic compounds with cooperative ground states.Results: After a brief introduction to the technique, recent work concerning FEBID of Pt–Si alloys and (hard-magnetic Co–Pt intermetallic compounds on the nanometer scale is reviewed. The growth process in the presence of two precursors, whose flux is independently controlled, is analyzed within a continuum model of FEBID that employs rate equations. Predictions are made for the tunability of the composition of the Co–Pt system by simply changing the dwell time of the electron beam during the writing process. The charge-transport regimes of nanogranular metals are reviewed next with a focus on recent theoretical advancements in the field. As a case study the transport properties of Pt–C nanogranular FEBID structures are discussed. It is shown that by means of a post-growth electron-irradiation treatment the electronic intergrain-coupling strength can be continuously tuned over a wide range. This provides unique access to the transport properties of this material close to the insulator-to-metal transition. In the last part of the review, recent developments in mechanical

  2. Transverse and longitudinal characterization of electron beams using interaction with optical near-fields

    CERN Document Server

    Kozák, Martin; Leedle, Kenneth J; Deng, Huiyang; Schönenberger, Norbert; Ruehl, Axel; Hartl, Ingmar; Hoogland, Heinar; Holzwarth, Ronald; Harris, James S; Byer, Robert L; Hommelhoff, Peter

    2016-01-01

    We demonstrate an experimental technique for both transverse and longitudinal characterization of bunched femtosecond free electron beams. The operation principle is based on monitoring of the current of electrons that obtained an energy gain during the interaction with the synchronized optical near-field wave excited by femtosecond laser pulses. The synchronous accelerating/decelerating fields confined to the surface of a silicon nanostructure are characterized using a highly focused sub-relativistic electron beam. Here the transverse spatial resolution of 450 nm and femtosecond temporal resolution achievable by this technique are demonstrated.

  3. PERFORMANCE ANALYSIS OF AZIMUTH ELECTRONIC BEAM STEERING MODE SPACEBORNE SAR

    Institute of Scientific and Technical Information of China (English)

    Han Xiaodong; Xu Wei; Han Xiaolei

    2013-01-01

    Pointing angle and pattern of the antenna can be changed swiftly to actualize the azimuth beam scanning by using electronic beam steering,which makes the Synthetic Aperture Radar (SAR)system more flexible and achieve a high resolution or cover a long strip within short time span.When the pointing angle is steered away from boresight,some aberrations may appear on the antenna pattern,e.g.,the grating lobe appears,the main lobe gain decrease,and antenna pattern broadens,e.g.,the aberrations result in the worsening of system performance,and complicate the corresponding performance analysis method.Conventional computation methods of performance parameters do not account for the rapid change of the antenna pattern.It introduces remarkable errors when the scanning angle is large.In this paper,a method of calculating performance parameters is proposed for the beam steering mode,which achieves the parameters by the energy accumulation in time domain.Actually,the proposed method simulates the working process of SAR and obtains accurate performance parameters.Furthermore,we analyze the effects of the grating lobe on the Azimuth Ambiguity to Signal Ratio (AASR),and present the generic Pulse Repetition Frequency (PRF) choosing principle which can also prevent the ambiguous area from weighting by the grating lobe.Finally,the effect of the antenna configuration on the performance parameters is analyzed by a system example.

  4. Electron Beam Welding of Thick Copper Material

    Energy Technology Data Exchange (ETDEWEB)

    Broemssen, Bernt von [IVF Industriforskning och utveckling AB, Stockholm (Sweden)

    2002-08-01

    The purpose of this study was to review the two variants of the Electron Beam Welding (EBW) processes developed (or used) by 1- SKB, Sweden with assistance from TWI, England and 2 - POSIVA, Finland with assistance from Outokumpu, Finland. The aim was also to explain the principle properties of the EBW method: how it works, the parameters controlling the welding result but also giving rise to benefits, and differences between the EBW variants. The main conclusions are that both SKB and POSIVA will within a few years succeed to qualify their respective EBW method for welding of copper canisters. The Reduced Pressure EBW that SKB use today seems to be very promising in order to avoid root defects. If POSIVA does not succeed to avoid root defects with the high vacuum method and the beam oscillation technique it should be possible for POSIVA to incorporate the Reduced Pressure technique albeit with significant changes to the EBW equipment. POSIVA has possibly an advantage over SKB with the beam oscillation technique used, which gives an extra degree of freedom to affect the weld quality. The beam oscillation could be of importance for closing of the keyhole. Before EBW of lids, the material certification showing the alloy content (specifying min and max impurity percentages) and the mechanical properties should be checked. The welded material needs also to be tested for mechanical properties. If possible the weld should have a toughness level equal to that of the unwelded parent material. Specifically some conclusions are reported regarding the SKB equipment. Suggestions for further development are also given in the conclusion chapter.

  5. Self-amplified spontaneous emission free-electron laser with an energy-chirped electron beam and undulator tapering.

    Science.gov (United States)

    Giannessi, L; Bacci, A; Bellaveglia, M; Briquez, F; Castellano, M; Chiadroni, E; Cianchi, A; Ciocci, F; Couprie, M E; Cultrera, L; Dattoli, G; Filippetto, D; Del Franco, M; Di Pirro, G; Ferrario, M; Ficcadenti, L; Frassetto, F; Gallo, A; Gatti, G; Labat, M; Marcus, G; Moreno, M; Mostacci, A; Pace, E; Petralia, A; Petrillo, V; Poletto, L; Quattromini, M; Rau, J V; Ronsivalle, C; Rosenzweig, J; Rossi, A R; Rossi Albertini, V; Sabia, E; Serluca, M; Spampinati, S; Spassovsky, I; Spataro, B; Surrenti, V; Vaccarezza, C; Vicario, C

    2011-04-08

    We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. An increase of more than 1 order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.

  6. A pulse radiolysis study on electron affinity of piperonal

    Institute of Scientific and Technical Information of China (English)

    MA; Jianhua; LIN; Weizhen; WANG; Wenfeng; YAO; Side

    2005-01-01

    The piperonal electron affinity was studied using pulse radiolysis technique. The electron transfer reaction process between piperonal and anthraquinone-2-sulfate was observed in the pH 7 phosphoric acid salt buffer. The transient absorption spectra of electron transfer reaction between piperonal and anthraquinone-2-sulfate were obtained, and the initial proof of the electron transfer between electron donor and acceptor was provided directly. The one-electron reduction potential of piperonal was determined to be -0.457 V.

  7. Characterization of a medical X-ray machine for testing the response of electronic dosimeters in pulsed radiation fields

    Science.gov (United States)

    Guimarães, Margarete C.; Da Silva, Teógenes A.

    2014-11-01

    Electronic personal dosimeters (EPD) based on solid state detectors have been used for personnel monitoring for radiation protection purpose; their use has been extended to practices with pulsed radiation beams although their performance is not well known. Deficiencies in the EPD response in pulsed radiation fields have been reported; they were not detected before since type tests and calibrations of EPDs were established in terms of continuous X and gamma reference radiations. An ISO working group was formed to elaborate a standard for test conditions and performance requirements of EPDs in pulsed beams; the PTB/Germany implemented a special X-ray facility for generating the reference pulsed radiation beams. In this work, an 800 Plus VMI medical X-ray machine of the Dosimeter Calibration Laboratory of CDTN/CNEN was characterized to verify its feasibility to perform EPD tests. Characterization of the x-ray beam was done in terms of practical peak voltage, half-value layer, mean energy and air kerma rate. Reference dosimeters used for air kerma measurements were verified as far their metrological coherence and a procedure for testing EDPs was established. Electronic personal dosimeters (EPD) have been used for personnel monitoring. EPD use has been extended to pulsed radiation beams. Deficiencies in the EPD response in pulsed beams have been reported. The feasibility of using a medical X-ray machine to perform EPD tests was studied. Reference dosimeters were verified and EPD testing procedure was established.

  8. Electron-beam-controlled laser with a grid-controlled electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Avanesyan, V.S.; Dutov, A.I.; Lakhno, Y.V.; Malkhov, L.N.

    1977-08-01

    An experimental investigation was made of an electron-beam-controlled carbon dioxide laser with an electron gun in which the beam current was modulated by a control grid. The design features of the electron gun and laser are described and their performance is reported. Observations of instabilities of the electron beam in the gun are reported and methods for eliminating them are suggested.

  9. Dynamical fragmentation and very high speed projection of micro-particulates with a pulsed electrons generator; Fragmentation dynamique et projection a tres grande vitesse de microparticules avec un generateur d'electrons pulses

    Energy Technology Data Exchange (ETDEWEB)

    Cassany, B.; Courchinoux, R.; Bertron, I.; Malaise, F.; Hebert, D. [Centre d' Etudes Scientifiques et Techniques d' Aquitaine, 33 - Le Barp (France)

    2003-07-01

    This paper shows how to use a pulsed electrons beam to simulate the dynamical fragmentation of copper sheets and to eject diamond, tantalum and tungsten micro-particulates at very high speed ({approx}1000 m/s). These experiments were performed with the electrons generator CESAR of CEA/CESTA (France). (J.S.)

  10. Polarization of a stored electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Chao, A.W.

    1981-07-01

    Synchrotron radiation by a point charge is a familiar subject in classical electrodynamics. Perhaps less familiar are some quantum mechanical corrections to the classical results. Some of those quantum aspects of synchrotron radiation are described. One of the quantum effects leads to the expectation that electrons in a storage ring will polarize themselves to 92% - a surprisingly high value. A semi-classical derivation of the quantum effects is given. An effort has been made to minimize the need of using quantum mechanics. Results are put together to derive a final expression of beam polarization. Conditions under which the expected 92% polarization is destroyed are found and attributed to depolarization resonances. The various depolarization mechanisms are first illustrated by an idealized example and then systematically treated by a matrix formalism. It is shown that the strength of depolarization is specified by a key quantity called the spin chromaticity. Finally as an application of the obtained results, an estimate of the achievable level of beam polarization for two existing electron storage rings, SPEAR and PEP, is given.

  11. Numerical simulation of the processes of small-diameter high-current electron beam shaping and injection

    CERN Document Server

    Gordeev, V S; Myskov, G A

    2001-01-01

    With the aid of BEAM 25 program there was carried out the numerical simulation of the non-stationary process of shaping a small-diameter (<= 20mm) high-current hollow electron beam in a diode with magnetic insulation,as well as of the process of beam injection into the accelerating LIA track. The diode configuration for the purpose of eliminating the leakage of electron flux to the anode surface was update. Presented are the results of calculation of the injected beam characteristics (amplitude-time parameters of a current pulse, space-angle distributions of electrons etc.) depending on diode geometric parameters.

  12. Relativistic electron beam transport through cold and shock-heated carbon samples from aerogel to diamond

    Science.gov (United States)

    Krauland, C. M.; Wei, M.; Zhang, S.; Santos, J.; Nicolai, P.; Theobald, W.; Kim, J.; Forestier-Colleoni, P.; Beg, F.

    2016-10-01

    Understanding the transport physics of a relativistic electron beam in various plasma regimes is crucial for many high-energy-density applications, such as fast heating for advanced ICF schemes and ion sources. Most short pulse laser-matter interaction experiments for transport studies have been performed with initially cold targets where the resistivity is far from that in warm dense plasmas. We present three experiments that have been performed on OMEGA EP in order to extend fast electron transport and energy coupling studies in pre-assembled plasmas from different carbon samples. Each experiment has used one 4 ns long pulse UV beam (1014 W/cm2) to drive a shockwave through the target and a 10 ps IR beam (1019 W/cm2) to create an electron beam moving opposite the shock propagation direction. These shots were compared with initially cold target shots without the UV beam. We fielded three different samples including 340 mg/cc CRF foam, vitreous carbon at 1.4 g/cc, and high density carbon at 3.4 g/cc. Electrons were diagnosed via x-ray fluorescence measurements from a buried Cu tracer in the target, as well as bremsstrahlung emission and escaped electrons reaching an electron spectrometer. Proton radiograph was also performed in the foam shots. Details of each experiment, available data and particle-in-cell simulations will be presented. This work is supported by US DOE NLUF Program, Grant Number DE-NA0002728.

  13. Parallel plate chambers for monitoring the profiles of high-intensity pulsed antiproton beams

    CERN Document Server

    Hori, Masaki

    2004-01-01

    Two types of beam profile monitor with thin parallel-plate electrodes have been used in experiments carried out at the Low Energy Antiproton Ring (LEAR) and Antiproton Decelerator (AD) of CERN. The detectors were used to measure non-destructively the spatial profiles, absolute intensities, and time structures of 100-300-ns- long beam pulses containing between 10**7 and 10**9 antiprotons. The first of these monitors was a parallel plate ionization chamber operated at gas pressure P=65 mbar. The other was a secondary electron emission detector, and was operated in the ultra-high vacuum of the AD. Both designs may be useful in medical and commercial applications. The position-sensitive electrodes in these detectors were manufactured by a novel method in which a laser trimmer was used to cut strip patterns on metallized polyester foils.

  14. Analysis of transmission efficiency of SSRF electron beam transfer lines

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this article, the main factors which influence transmission efficiency of the SSRF electron beam transfer lines are described, including physical requirements for magnet system, vacuum system, beam diagnostic system,trajectory correction system, etc. The dynamic simulation calculation and transmission efficiency analysis of the SSRF electron beam transfer lines are presented, and the studies show that the design purpose of efficient beam transmission and injection will be achieved.

  15. Cherenkov light-based beam profiling for ultrarelativistic electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Adli, E., E-mail: Erik.Adli@fys.uio.no [Department of Physics, University of Oslo, N-0316 Oslo (Norway); SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Gessner, S.J.; Corde, S.; Hogan, M.J. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Bjerke, H.H. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim (Norway)

    2015-05-21

    We describe a beam profile monitor design based on Cherenkov light emitted from a charged particle beam in an air gap. The main components of the profile monitor are silicon wafers used to reflect Cherenkov light onto a camera lens system. The design allows for measuring large beam sizes, with large photon yield per beam charge and excellent signal linearity with beam charge. The profile monitor signal is independent of the particle energy for ultrarelativistic particles. Different design and parameter considerations are discussed. A Cherenkov light-based profile monitor has been installed at the FACET User Facility at SLAC. We report on the measured performance of this profile monitor.

  16. 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.

  17. Generation of large-bandwidth x-ray free-electron-laser pulses

    Directory of Open Access Journals (Sweden)

    Angela Saa Hernandez

    2016-09-01

    Full Text Available X-ray free-electron lasers (XFELs are modern research tools in disciplines such as biology, material science, chemistry, and physics. Besides the standard operation that aims at minimizing the bandwidth of the produced XFEL radiation, there is a strong scientific demand to produce large-bandwidth XFEL pulses for several applications such as nanocrystallography, stimulated Raman spectroscopy, and multiwavelength anomalous diffraction. We present a self-consistent method that maximizes the XFEL pulse bandwidth by systematically maximizing the energy chirp of the electron beam at the undulator entrance. This is achieved by optimizing the compression scheme and the electron distribution at the source in an iterative back-and-forward tracking. Start-to-end numerical simulations show that a relative bandwidth of 3.25% full-width can be achieved for the hard x-ray pulses in the SwissFEL case.

  18. Generation of broadband terahertz radiation using a backward wave oscillator and pseudospark-sourced electron beam

    Energy Technology Data Exchange (ETDEWEB)

    He, W.; Zhang, L.; Bowes, D.; Yin, H.; Ronald, K.; Phelps, A. D. R.; Cross, A. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow, G4 0NG Scotland (United Kingdom)

    2015-09-28

    This paper presents for the generation of a small size high current density pseudospark (PS) electron beam for a high frequency (0.2 THz) Backward Wave Oscillator (BWO) through a Doppler up-shift of the plasma frequency. An electron beam ∼1 mm diameter carrying a current of up to 10 A and current density of 10{sup 8} A m{sup −2}, with a sweeping voltage of 42 to 25 kV and pulse duration of 25 ns, was generated from the PS discharge. This beam propagated through the rippled-wall slow wave structure of a BWO beam-wave interaction region in a plasma environment without the need for a guiding magnetic field. Plasma wave assisted beam-wave interaction resulted in broadband output over a frequency range of 186–202 GHz with a maximum power of 20 W.

  19. Conceptual design of hollow electron lenses for beam halo control in the Large Hadron Collider

    CERN Document Server

    Stancari, Giulio; Valishev, Alexander; Bruce, Roderik; Redaelli, Stefano; Rossi, Adriana; Ferrando, Belen Salvachua; Salvachua Ferrando, B

    2014-01-01

    Collimation with hollow electron beams is a technique for halo control in high-power hadron beams. It is based on an electron beam (possibly pulsed or modulated in intensity) guided by strong axial magnetic fields which overlaps with the circulating beam in a short section of the ring. The concept was tested experimentally at the Fermilab Tevatron collider using a hollow electron gun installed in one of the Tevatron electron lenses. Within the US LHC Accelerator Research Program (LARP) and the European FP7 HiLumi LHC Design Study, we are proposing a conceptual design for applying this technique to the Large Hadron Collider at CERN. A prototype hollow electron gun for the LHC was built and tested. The expected performance of the hollow electron beam collimator was based on Tevatron experiments and on numerical tracking simulations. Halo removal rates and enhancements of halo diffusivity were estimated as a function of beam and lattice parameters. Proton beam core lifetimes and emittance growth rates were check...

  20. Supershort avalanche electron beams and x-ray in high-pressure nanosecond discharges

    Science.gov (United States)

    Tarasenko, V. F.; Baksht, E. H.; Kostyrya, I. D.; Lomaev, M. I.; Rybka, D. V.

    2008-10-01

    The properties of a supershort avalanche electron beam (S AEB) and X-ray radiation produced using a nanosecond volume discharge are examined. An electron beam of the runaway electrons with amplitude of ~ 50 A has been obtained in air atmospheric pressure. It is reported that S AEB is formed in the angle above 2π sr. Three groups of the runaway electrons are formed in a gas diode under atmospheric air pressure, when nanosecond voltage pulses with amplitude of hundreds of kilovolts are applied. The electron beam has been generated behind a 45 μm thick AlBe foil in SF6 and Xe under the pressure of 2 arm, and in He under the pressure of about 12 atm. The paper gives the analysis of a generation mechanism of SAEB.

  1. 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.

  2. 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.

  3. Performance of a solenoid-driven pulsed molecular-beam source

    OpenAIRE

    Abad, Luis; Bermejo, Dionisio; Herrero, Víctor J.; Santos, J.; Tanarro, Isabel

    1995-01-01

    The characteristics of a commonly used pulsed valve for the production of free jets and molecular beams are analyzed in detail. Special attention is paid to the formation of gas pulses providing a quasisteady flow during a certain time interval within the pulse duration, and to the estimation of a scaling parameter (effective diameter) for the description of the flow field. The adequacy of this effective diameter is checked by performing time-of-flight measurements on molecular beams of Ne, N...

  4. Electron beam induced oxidation of Al–Mg alloy surfaces

    NARCIS (Netherlands)

    Palasantzas, G.; Agterveld, D.T.L. van; Hosson, J.Th.M. De

    2002-01-01

    Electron beam currents of a few nanoamperes, currently used in nanometer scale scanning Auger/electron microscopy, induces severe oxidation of Al–Mg alloy surfaces at room temperature. Auger peak-to-peak oxygen curves for Al–Mg surfaces support the hypothesis that the electron beam creates

  5. Electron beam induced oxidation of Al–Mg alloy surfaces

    NARCIS (Netherlands)

    Palasantzas, G.; Agterveld, D.T.L. van; Hosson, J.Th.M. De

    2002-01-01

    Electron beam currents of a few nanoamperes, currently used in nanometer scale scanning Auger/electron microscopy, induces severe oxidation of Al–Mg alloy surfaces at room temperature. Auger peak-to-peak oxygen curves for Al–Mg surfaces support the hypothesis that the electron beam creates additiona

  6. Experimental Study of Diamond Like Carbon (DLC) Coated Electrodes for Pulsed High Gradient Electron Gun

    CERN Document Server

    Paraliev, M; Ivkovic, S; Le Pimpec, F

    2010-01-01

    For the SwissFEL Free Electron Laser project at the Paul Scherrer Institute, a pulsed High Gradient (HG) electron gun was used to study low emittance electron sources. Different metals and surface treatments for the cathode and anode were studied for their HG suitability. Diamond Like Carbon (DLC) coatings are found to perform exceptionally well for vacuum gap insulation. A set of DLC coated electrodes with different coating parameters were tested for both vacuum breakdown and photo electron emission. Surface electric fields over 250MV/m (350 - 400kV, pulsed) were achieved without breakdown. From the same surface, it was possible to photo-emit an electron beam at gradients up to 150MV/m. The test setup and the experimental results are presented

  7. A Novel Contactless Method for Characterization of Semiconductors: Surface Electron Beam Induced Voltage in Scanning Electron Microscopy

    Institute of Scientific and Technical Information of China (English)

    朱世秋; E.I.RAU; 杨富华; 郑厚植

    2002-01-01

    We present a novel contactless and nondestructive method called the surface electron beam induced voltage (SEBIV) method for characterizing semiconductor materials and devices. The SEBIV method is based on the detection of the surface potential induced by electron beams of scanning electron microscopy (SEM). The core part of the SEBIV detection set-up is a circular metal detector placed above the sample surface. The capacitance between the circular detector and whole surface of the sample is estimated to be about 0.64pf. It is large enough for the detection of the induced surface potential. The irradiation mode of electron beam (e-beam) influences the signal generation. When the e-beam irradiates on the surface of semiconductors continuously, a differential signal is obtained. The real distribution of surface potentials can be obtained when a pulsed e-beam with a fixed frequency is used for irradiation and a lock-in amplifier is employed for detection. The polarity of induced potential depends on the structure of potential barriers and surface states of samples. The contrast of SEBIV images in SEM changes with irradiation time and e-beam intensity.

  8. A comparison between spectra of runaway electron beams in SF6 and air

    Science.gov (United States)

    Zhang, Cheng; Tarasenko, Victor; Gu, Jianwei; Baksht, Evgenii; Wang, Ruexue; Yan, Ping; Shao, Tao

    2015-12-01

    Runaway electron (RAE) with extremely high-energy plays important role on the avalanche propagation, streamer formation, and ionization waves in nanosecond-pulse discharges. In this paper, the generation of a supershort avalanche electron beam (SAEB) in SF6 and air in an inhomogeneous electric field is investigated. A VPG-30-200 generator with a pulse rise time of ˜1.6 ns and a full width at half maximum of 3-5 ns is used to produce RAE beams. The SAEBs in SF6 and air are measured by using aluminum foils with different thicknesses. Furthermore, the SAEB spectra in SF6 and air at pressures of 7.5 Torr, 75 Torr, and 750 Torr are compared. The results showed that amplitude of RAE beam current generated at the breakdown in SF6 was approximately an order of magnitude less than that in air. The energy of SAEB in air was not smaller than that in SF6 in nanosecond-pulse discharges under otherwise equal conditions. Moreover, the difference between the maximum energy of the electron distributions in air and SF6 decreased when the rise time of the voltage pulse increased. It was because the difference between the breakdown voltages in air and SF6 decreased when the rise time of the voltage pulse increased.

  9. Optical Sideband Generation: a Longitudinal Electron Beam Diagnostic Beyond the Laser Bandwidth Resolution Limit

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence Berkeley National Laboratory; Tilborg, J. van; Matlis, N. H.; Plateau, G. R.; Leemans, W. P.

    2010-06-01

    Electro-optic sampling (EOS) is widely used as a technique to measure THz-domain electric field pulses such asthe self-fields of femtosecond electron beams. We present an EOS-based approach for single-shot spectral measurement that excels in simplicity (compatible with fiber integration) and bandwidth coverage (overcomes the laser bandwidth limitation), allowing few-fs electron beams or single-cycle THz pulses to be characterized with conventional picosecond probes. It is shown that the EOS-induced optical sidebands on the narrow-bandwidth optical probe are spectrally-shifted replicas of the THz pulse. An experimental demonstration on a 0-3 THz source is presented.

  10. The design and construction of a pulsed beam generation system based on high intensity cyclotron

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In order to perform the studies on a pulsed beam generation system based on a high intensity cyclotron, a test beam line with a pulsed beam generation for a 10 MeV compact cyclotron (CYCIAE-10) has been designed and constructed at China Institute of Atomic Energy (CIAE). A 70 MHz continuous H- beam can be pulsed to the pulse length of less than 10 ns with a repetition rate of 4.4 MHz. The sine waveform with a frequency of 2.2 MHz is adopted for the chopper and a mesh structure with single drift and dual gaps is used for the 70 MHz buncher. A helical resonator is designed and constructed based on simulations and experiments on the RF matching for the chopper. A helical inductance loop that is exceptionally large of its kind and equipped with water cooling for the resonator has been successfully wound and a 500 W solid RF amplifier has been manufactured. A special measuring device has been designed, which can be used to measure both the DC beam and the pulsed beam. The required pulsed beam was obtained after pulsed beam tuning.

  11. Highly efficient electron vortex beams generated by nanofabricated phase holograms

    Energy Technology Data Exchange (ETDEWEB)

    Grillo, Vincenzo, E-mail: vincenzo.grillo@nano.cnr.it [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); CNR-IMEM Parco Area delle Scienze 37/A, I-43124 Parma (Italy); Carlo Gazzadi, Gian [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Karimi, Ebrahim [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada); Mafakheri, Erfan [Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy); Boyd, Robert W. [Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada); Frabboni, Stefano [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy)

    2014-01-27

    We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science.

  12. Electron pulse shaping in the FELIX RF accelerator

    NARCIS (Netherlands)

    Weits, H. H.; van der Geer, C. A. J.; Oepts, D.; van der Meer, A. F. G.

    1999-01-01

    The FELIX free-electron laser uses short pulses of relativistic electrons produced by an RF accelerator. The design target for the duration of these electron bunches was around 3 ps. In experiments we observed that the bunches emit coherently enhanced spontaneous emission (CSE) when they travel thro

  13. Two-pulse laser control of nuclear and electronic motion

    DEFF Research Database (Denmark)

    Grønager, Michael; Henriksen, Niels Engholm

    1997-01-01

    We discuss an explicitly time-dependent two-pulse laser scheme for controlling where nuclei and electrons are going in unimolecular reactions. We focus on electronic motion and show, with HD+ as an example, that one can find non-stationary states where the electron (with some probability) oscilla...

  14. Electron pulse shaping in the FELIX RF accelerator

    NARCIS (Netherlands)

    Weits, H. H.; van der Geer, C. A. J.; Oepts, D.; van der Meer, A. F. G.

    1999-01-01

    The FELIX free-electron laser uses short pulses of relativistic electrons produced by an RF accelerator. The design target for the duration of these electron bunches was around 3 ps. In experiments we observed that the bunches emit coherently enhanced spontaneous emission (CSE) when they travel

  15. Project outline of high quality electron beam generation at Waseda University

    Energy Technology Data Exchange (ETDEWEB)

    Washio, M.; Hama, Y.; Kashiwagi, S.; Kuroda, R.; Kobuki, T. [Waseda Univ., Advanced Research Institute for Science and Engineering, Shinjuku, Tokyo (Japan); Hirose, T. [Tokyo Metropolitan Univ. (Japan). Dept. of Physics

    2000-03-01

    High quality electron beam generation project has been started at Waseda University under the grant of Ministry of Education, named High-Tech Research Center Project. In the project, we will install a laser photo-cathode RF Gun system with 1.6 accelerating structure cells of s-band and a stabilized RF power source. This RF Gun is expected to produce single electron bunch up to 1 or 2nC with around 10ps pulse duration. (author)

  16. Electron Cyclotron Maser Emissions from Evolving Fast Electron Beams

    CERN Document Server

    Tang, J F; Chen, L; Zhao, G Q; Tan, C M

    2016-01-01

    Fast electron beams (FEBs) are common products of solar active phenomena. Solar radio bursts are an important diagnostic tool in the understanding of FEBs as well as the solar plasma environment in which they are propagating along solar magnetic fields. In particular, the evolutions of the energy spectrum and velocity distribution of FEBs due to the interaction with the ambient plasma and field when propagating can significantly influence the efficiency and property of their emissions. In this paper, we discuss some possible evolutions of the energy spectrum and velocity distribution of FEBs due to the energy loss processes and the pitch-angle effect caused by the magnetic field inhomogeneity, and analyze the effects of these evolutions on electron cyclotron maser (ECM) emission, which is one of the most important mechanisms of producing solar radio bursts by FEBs. The results show that the growth rates all decrease with the energy loss factor $Q$, but increase with the magnetic mirror ratio $\\sigma$ as well ...

  17. Relativistic electron beams from cathodes at 1 GV/m gradient

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan-Rao, T.; Smedley, J.; Schill, J.

    1998-05-01

    In the past decade, there has been extensive research in the development of low emittance, high brightness electron injectors for linear collider and free electron laser applications. RF injectors with a few nC charge in a few ps, with an emittance of {approximately}1--5 {pi}mm mrad are operational in a number of facilities. In these devices, a laser beam irradiates a photocathode embedded in an RF cavity. The photoelectrons released by the laser are immediately accelerated to relativistic velocities, thereby reducing the space charge effects. The frequency of the RF and the design of the cavity are chosen to minimize the RF and space charge effects on the electron bunch so that low emittance, high brightness electron beam could be generated. Minimization of RF effects on emittnce growth require a low RF frequency while minimizing the space charge effects require high field and hence high RF frequency. The design is hence a compromise between these two conflicting requirements. Some of these limitations could be overcome by using a large pulsed electric field at the cathode rather than a RF field. The duration of the pulsed field should be chosen so that it is longer than the electron bunch length and the transit time in the accelerating region, but short enough to avoid breakdown problems. Development of a high brightness electron source using this scheme requires a pulse generator, a laser pulse of sufficient energy to trigger and synchronize the electrical pulses, and a short laser pulse to irradiate the photocathode and generate electron pulses to be accelerated. The designs of these components are described.

  18. Design and performance of the pulsed positron beam at Chalmers University of Technology

    Science.gov (United States)

    Mileshina, L.; Nordlund, A.

    2009-09-01

    A slow monoenergetic pulsed positron beam at Chalmers University of Technology has been built. The system consists mainly of chopper, buncher and accelerator. The achieved positron energy range is in range between 230 eV and 15 keV. The FWHM of the beam resolution function is around 700 ps. The beam intensity is around 103 cps.

  19. Improved accuracy in nano beam electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Beche, A; Rouviere, J-L [CEA, INAC, SP2M, LEMMA, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Clement, L, E-mail: armand.beche@cea.f, E-mail: jean-luc.rouviere@cea.f [ST Microelectronics, 850 rue Jean Monnet, F-38920 Crolles (France)

    2010-02-01

    Nano beam electron diffraction (NBD or NBED) is applied on a well controlled sample in order to evaluate the limit of the technique to measure strain. Measurements are realised on a 27nm thick Si{sub 0.7}Ge{sub 0.3} layer embedded in a silicon matrix, with a TITAN microscope working at 300kV. Using a standard condenser aperture of 50{mu}m, a probe size diameter of 2.7 nm is obtained and a strain accuracy of 6x10{sup -4} (mean root square, rms) is achieved. NBED patterns are acquired along a [110] direction and the bidimensionnal strain in the (110) plane is measured. Finite element simulations are carried out to check experimental results and reveal that strain relaxation and probe averaging in a 170nm thick TEM lamella reduces strain by 15%.

  20. Measuring the Orbital Angular Momentum of Electron Beams

    CERN Document Server

    Guzzinati, Giulio; Béché, Armand; Verbeeck, Jo

    2014-01-01

    The recent demonstration of electron vortex beams has opened up the new possibility of studying orbital angular momentum (OAM) in the interaction between electron beams and matter. To this aim, methods to analyze the OAM of an electron beam are fundamentally important and a necessary next step. We demonstrate the measurement of electron beam OAM through a variety of techniques. The use of forked holographic masks, diffraction from geometric apertures, diffraction from a knife-edge and the application of an astigmatic lens are all experimentally demonstrated. The viability and limitations of each are discussed with supporting numerical simulations.