WorldWideScience

Sample records for beam generated plasma

  1. Simulation of Electron-Beam Generating Plasma at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    OUYANG Liang; LI Hong; LI Benben; ZHOU Junqing; YAN Hong; SU Tie; WANG Huihui; LIUWandong

    2007-01-01

    As electron-beam generating plasma is widely applied,the software tool EGS4(Electron-Gamma Shower) was used to simulate the transmission and energy deposition of electron-beam in air.The simulation results indicated that the range of the electron-beam was inversely proportional to the gas pressure in a wide range of gas pressure,and the electron-beam of 200 keV could generate a plasma with a density 1011 cm-3 in air of latm.In addition,the energy distribution of the beam-electron and plasma density profile produced by the beam were achieved.

  2. dc plasma generator development for neutral-beam injectors

    International Nuclear Information System (INIS)

    Rectangular plasma generators are being developed with the capability of producing hydrogen ion beams of 60 to 100 A. Using single and double electron feed configurations of the duoPIGatron type, these generators have been operated at arc levels of 1200 A for pulse lengths of > 30 s. The plasma density and uniformity are sufficient for extracting approx. 60-A hydrogen ions using a 13 x 43 cm accelerator and approx. 100 A with an 18 x 48 cm accelerator

  3. A reflex electron beam discharge as a plasma source for electron beam generation

    International Nuclear Information System (INIS)

    A reflex electron beam glow discharge has been used as a plasma source for the generation of broad-area electron beams. An electron current of 120 A (12 A/cm/sup 2/) was extracted from the plasma in 10 μs pulses and accelerated to energies greater than 1 keV in the gap between two grids. The scaling of the scheme for the generation of multikiloamp high-energy beams is discussed

  4. Development of rf plasma generators for neutral beams

    International Nuclear Information System (INIS)

    The development of low frequency (1-2 MHz) rf plasma generators for high power neutral beam applications is summarized. Immersed couplers from one to three turns were used. Acceptable plasma profiles, less than or equal to 15% max/min, were obtained in a variety of field-free magnetic bucket and magnetic filter-bucket sources, with 10 x 10 cm or 10 x 40 cm extraction areas. Hydrogen beam properties were measured with a 7 x 10 cm accelerator operated at 80 kV. Atomic fraction and power efficiency were at least as high as with arc plasmas in similar chambers. The potential advantages of an rf plasma source are: ease of operation; reliability; and extended service lifetime

  5. Population inversions in ablation plasmas generated by intense electron beams

    Science.gov (United States)

    Gilgenbach, R. M.; Kammash, T.; Brake, M. L.

    1988-11-01

    Experiments during the past three years have concerned the generation and spectroscopic study of electron beam-driven carbon plasmas in order to explore the production of optical and ultraviolet radiation from nonequilibrium populations. The output of MELBA (Michigan Electron Long Beam Accelerator), has been connected to an electron beam diode consisting of an aluminum (or brass) cathode stalk and a carbon anode. Magnetic field coils have been designed, procured, and utilized to focus the electron beam. A side viewing port permitted spectroscopic diagnostics to view across the surface of the anode. Spectroscopic diagnosis has been performed using a 1 m spectrograph capable of operation from the vacuum ultraviolet through the visible. This spectrograph is coupled to a 1024 channel optical multichannel analyzer. Spectra taken during the initial 400 ns period of the e-beam pulse showed a low effective charge plasma with primarily molecular components (C2, CH) as well as atomic hydrogen and singly ionized carbon (CII). When the generator pulse was crowbarred after the first 400 ns, the spectra revealed a continuation of the low charge state plasma.

  6. Low-energy High-current Electron Beam Generation in Plasma System and Beam-Plasma Interaction

    International Nuclear Information System (INIS)

    The review of results of experimental investigations and computer simulations of low-energy high-current electron beam generation in a low-impedance system and dynamics of beam-plasma system are given. The system includes a long plasma-filled diode, an auxiliary thermionic cathode and an explosive emission cathode. The auxiliary cathode is used to generate the a low-current, low-voltage electron beam to form long plasma anode by means of a residual gas ionisation in an external longitudinal magnetic field. The high-current low-energy electron beam is generated from the explosive emission cathode embedded in preliminary prepared plasma. Peculiarities of the system are due to: 1) the generation of electron beams with currents exceeding Alfven's limit; 2) the charge density of the beam close to the plasma density. These peculiarities complicate beam-plasma interaction significantly due to sharp non-uniform distribution of the beam current density, dominant transverse motion of the beam electrons and redistribution of ion-plasma density under the influence of fields. Computer simulation was performed using electromagnetic PIC code KARAT for different geometry's of the system

  7. 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.

  8. Ion Beam Analysis applied to laser-generated plasmas

    International Nuclear Information System (INIS)

    This paper presents the research activity on Ion Beam Analysis methods performed at Tandetron Laboratory (LT) of the Institute of Nuclear Physics AS CR, Rez, Czech Republic. Recently, many groups are paying attention to implantation by laser generated plasma. This process allows to insert a controllable amount of energetic ions into the surface layers of different materials modifying the physical and chemical properties of the surface material. Different substrates are implanted by accelerated ions from plasma through terawatt iodine laser, at nominal intensity of 1015 W/cm2, at the PALS Research Infrastructure AS CR, in the Czech Republic. This regime of the laser matter interaction generates, multi-MeV proton beams, and multi-charged ions that are tightly confined in time (hundreds ps) and space (source radius of a few microns). These ion beams have a much lower transverse temperature, a much shorter duration and a much higher current than those obtainable from conventional accelerators. The implementation of protons and ions acceleration driven by ultra-short high intensity lasers is exhibited by adopting suitable irradiation conditions as well as tailored targets. An overview of implanted targets and their morphological and structural characterizations is presented and discussed

  9. Ion Beam Analysis applied to laser-generated plasmas

    Science.gov (United States)

    Cutroneo, M.; Macková, A.; Havranek, V.; Malinsky, P.; Torrisi, L.; Kormunda, M.; Barchuk, M.; Ullschmied, J.; Dudzak, R.

    2016-04-01

    This paper presents the research activity on Ion Beam Analysis methods performed at Tandetron Laboratory (LT) of the Institute of Nuclear Physics AS CR, Rez, Czech Republic. Recently, many groups are paying attention to implantation by laser generated plasma. This process allows to insert a controllable amount of energetic ions into the surface layers of different materials modifying the physical and chemical properties of the surface material. Different substrates are implanted by accelerated ions from plasma through terawatt iodine laser, at nominal intensity of 1015 W/cm2, at the PALS Research Infrastructure AS CR, in the Czech Republic. This regime of the laser matter interaction generates, multi-MeV proton beams, and multi-charged ions that are tightly confined in time (hundreds ps) and space (source radius of a few microns). These ion beams have a much lower transverse temperature, a much shorter duration and a much higher current than those obtainable from conventional accelerators. The implementation of protons and ions acceleration driven by ultra-short high intensity lasers is exhibited by adopting suitable irradiation conditions as well as tailored targets. An overview of implanted targets and their morphological and structural characterizations is presented and discussed.

  10. 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.

  11. Light ion beams generation in dense plasma focus

    International Nuclear Information System (INIS)

    The high energy deuterons and protons in a Mather type plasma focus device were measured by nuclear activation techniques. The radioactivity induced in graphite, aluminum and copper targets provided the deuteron intensity, energy spectra and angular dependence. High energy protons were measured by cellulose nitrate particle track detectors. The plasma focus device was operated at 30 kV for a stored energy of 18 kJ at 1.5 Torr D2 (low pressure mode), and 5 Torr D2 (high pressure mode). The yield ratio of N-13 and Al-28 showed the mean deuteron energy of 1.55 MeV under low pressure mode and of 1.44 MeV under high pressure mode. The deuteron energy spectra were measured by the stacks of 10 aluminum foils, and consisted of two components as well as the proton energy spectra measured by CN film technique. The angular spread of deuteron beam was within 30 degree under low pressure mode. Under high pressure mode, the distribution showed multi-structure, and two peaks were observed at the angle smaller than 20 degree and at 60 degree. The protons with energy more than 770 keV were directed in the angle of 10 degree. The high energy electron beam was also observed. A three-channel ruby laser holographic interferometry was used to see the spatial and temporal location of the generation of high energy ions. The ion temperature in plasma focus was estimated from D + He3 mixture gas experiment. (Kato, T.)

  12. Development of radio frequency induction plasma generators for neutral beams

    International Nuclear Information System (INIS)

    The techniques, operational aspects, and experimental results of a radio frequency induction plasma generator, with an internal rf power coupler, intended for intense neutral beam applications are described. One of the development sources suitable for 10 x 10-cm2 extraction optics was operated to a deuterium ion current density of 250 mA/cm2, uniform to 5%, over a circular extraction area 15 cm in diameter with a coupled rf power of 20 kW. Temporal fluctuation levels in the extracted ion current were measured to be typically 1% of the dc level. A second developmental source suitable for 10 x 40-cm2 grid sets was operated to 200 mA/cm2, uniform to +- 8% over a 10 x 40 cm2 area, with 40-kW coupled rf power

  13. Collimated fast electron beam generation in critical density plasma

    OpenAIRE

    Iwawaki, T.; Habara, H; Baton, S.; Morita, K.; Fuchs, J; Chen, S.; Nakatsutsumi, M.; Rousseaux, C; Filippi, F; Nazarov, W.; Tanaka, K.A.

    2014-01-01

    Significantly collimated fast electron beam with a divergence angle 10° (FWHM) is observed when an ultra-intense laser pulse (I = 1014 W/cm2, 300 fs) irradiates a uniform critical density plasma. The uniform plasma is created through the ionization of an ultra-low density (5 mg/c.c.) plastic foam by X-ray burst from the interaction of intense laser (I = 1014 W/cm2, 600 ps) with a thin Cu foil. 2D Particle-In-Cell (PIC) simulation well reproduces the collimated electron beam with a strong magn...

  14. Ion beam generation and propagation for plasma processing applications

    International Nuclear Information System (INIS)

    Intense ion beams are being employed at Los Alamos to deposit thin films. Extraction geometry magnetically-insulated ion diodes (MID) are used to generate ion beams with currents up to 35 kA at 450 kV in a one-half microsecond long pulse. Multidimensional electromagnetic particle-in-cell (PIC) simulations have been performed to model the generation, extraction, and focusing of proton beams in realistic geometries. A ballistically focused MID has been studied to achieve the high deposition rates needed to form ablation plumes that preserve stoichiometric ratios. A high density waist with a diameter less than 8 cm is calculated near the geometrical focus. Extraction efficiency, beam divergence downstream of the aperture, and neutralization issues have been studied with the simulations

  15. Spatial properties of a terahertz beam generated from a two-color air plasma

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Wang, Tianwu; Buron, Jonas Christian Due;

    2013-01-01

    We present a spatial characterization of terahertz (THz) beams generated from a two-color air plasma under different conditions by measuring full 3D beam profiles using a commercial THz camera. We compare two THz beam profiles emitted from plasmas generated by 35 fs and 100 fs laser pulses, and...... reduces the beam waist, and that the beam spot shape changes from Lorentzian to Gaussian. Finally, we observe a forward-propagating Gaussian THz beam by spatially filtering away the conical off-axis radiation with a 1 cm aperture....... show that the spatial properties of the two THz beams do not change significantly. For the THz beam profile generated by the 35 fs pulse, the spatial effect of eliminating the lower frequencies is investigated by implementing two crossed polarizers working as a high-pass filter. We show that this...

  16. Electron beam generated whistler emissions in a laboratory plasma

    International Nuclear Information System (INIS)

    Naturally occurring whistler mode emissions in the magnetosphere, are important since they are responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Recently, we reported on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced [1]. A beam of energetic electrons is launched into a cold plasma and excites both chirping whistler waves and broadband waves. Here we extend our previous analysis by comparing the properties of the broadband waves with linear theory

  17. Electron beam generated whistler emissions in a laboratory plasma

    Energy Technology Data Exchange (ETDEWEB)

    Van Compernolle, B., E-mail: bvcomper@physics.ucla.edu; Pribyl, P.; Gekelman, W. [Department of Physics, University of California, Los Angeles (United States); An, X.; Bortnik, J.; Thorne, R. M. [Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles (United States)

    2015-12-10

    Naturally occurring whistler mode emissions in the magnetosphere, are important since they are responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Recently, we reported on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced [1]. A beam of energetic electrons is launched into a cold plasma and excites both chirping whistler waves and broadband waves. Here we extend our previous analysis by comparing the properties of the broadband waves with linear theory.

  18. Numerical simulation of the ion beam generated in the diode with anode plasma column

    International Nuclear Information System (INIS)

    The ion beam generation in a high current diode with anode plasma slab was studied. The ions were extracted from the anode plasma by the strong electric field of a deep potential well (virtual cathode), arising after the propagation of relativistic electrons through the anode plasma slab. The movement of this potential well with the front part of the ion beam leads to collective ion acceleration up to the 10 MeV energy range. (author). 7 figs., 5 refs

  19. Collimated fast electron beam generation in critical density plasma

    Energy Technology Data Exchange (ETDEWEB)

    Iwawaki, T., E-mail: iwawaki-t@eie.eng.osaka-u.ac.jp; Habara, H.; Morita, K.; Tanaka, K. A. [Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan); Baton, S.; Fuchs, J.; Chen, S. [LULI, CNRS-Ecole Polytechnique-Université Pierre et Marie Curie-CEA, 91128 Palaiseau (France); Nakatsutsumi, M. [LULI, CNRS-Ecole Polytechnique-Université Pierre et Marie Curie-CEA, 91128 Palaiseau (France); European X-Ray Free-Electron Laser Facility (XFEL) GmbH (Germany); Rousseaux, C. [CEA, DAM, DIF, F-91297 Arpajon (France); Filippi, F. [La SAPIENZA, University of Rome, Dip. SBAI, 00161 Rome (Italy); Nazarov, W. [School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9ST, Scotland (United Kingdom)

    2014-11-15

    Significantly collimated fast electron beam with a divergence angle 10° (FWHM) is observed when an ultra-intense laser pulse (I = 10{sup 14 }W/cm{sup 2}, 300 fs) irradiates a uniform critical density plasma. The uniform plasma is created through the ionization of an ultra-low density (5 mg/c.c.) plastic foam by X-ray burst from the interaction of intense laser (I = 10{sup 14 }W/cm{sup 2}, 600 ps) with a thin Cu foil. 2D Particle-In-Cell (PIC) simulation well reproduces the collimated electron beam with a strong magnetic field in the region of the laser pulse propagation. To understand the physical mechanism of the collimation, we calculate energetic electron motion in the magnetic field obtained from the 2D PIC simulation. As the results, the strong magnetic field (300 MG) collimates electrons with energy over a few MeV. This collimation mechanism may attract attention in many applications such as electron acceleration, electron microscope and fast ignition of laser fusion.

  20. Collimated fast electron beam generation in critical density plasma

    International Nuclear Information System (INIS)

    Significantly collimated fast electron beam with a divergence angle 10° (FWHM) is observed when an ultra-intense laser pulse (I = 1014 W/cm2, 300 fs) irradiates a uniform critical density plasma. The uniform plasma is created through the ionization of an ultra-low density (5 mg/c.c.) plastic foam by X-ray burst from the interaction of intense laser (I = 1014 W/cm2, 600 ps) with a thin Cu foil. 2D Particle-In-Cell (PIC) simulation well reproduces the collimated electron beam with a strong magnetic field in the region of the laser pulse propagation. To understand the physical mechanism of the collimation, we calculate energetic electron motion in the magnetic field obtained from the 2D PIC simulation. As the results, the strong magnetic field (300 MG) collimates electrons with energy over a few MeV. This collimation mechanism may attract attention in many applications such as electron acceleration, electron microscope and fast ignition of laser fusion

  1. Generation of anomalously energetic suprathermal electrons by an electron beam interacting with a nonuniform plasma

    International Nuclear Information System (INIS)

    Generation of anomalously energetic suprathermal electrons was observed in simulation of a high-voltage dc discharge with electron emission from the cathode. An electron beam produced by the emission interacts with the nonuniform plasma in the discharge via a two-stream instability. The energy transfer from the beam to the plasma electrons is ensured by the plasma nonuniformity. The electron beam excites plasma waves whose wavelength and phase speed gradually decrease towards anode. The waves with short wavelength near the anode accelerate plasma bulk electrons to suprathermal energies. The sheath near the anode reflects some of the accelerated electrons back into the plasma. These electrons travel through the plasma, reflect near the cathode, and enter the accelerating area again but with a higher energy than before. Such particles are accelerated to energies much higher than after the first acceleration. This mechanism plays a role in explaining earlier experimental observations of energetic suprathermal electrons in similar discharges

  2. Generation of anomalously energetic suprathermal electrons by an electron beam interacting with a nonuniform plasma

    CERN Document Server

    Sydorenko, D; Chen, L; Ventzek, P L G

    2015-01-01

    Generation of anomalously energetic suprathermal electrons was observed in simulation of a high- voltage dc discharge with electron emission from the cathode. An electron beam produced by the emission interacts with the nonuniform plasma in the discharge via a two-stream instability. Efficient energy transfer from the beam to the plasma electrons is ensured by the plasma nonuniformity. The electron beam excites plasma waves whose wavelength and phase speed gradually decrease towards anode. The short waves near the anode accelerate plasma bulk electrons to suprathermal energies. The sheath near the anode reflects some of the accelerated electrons back into the plasma. These electrons travel through the plasma, reflect near the cathode, and enter the accelerating area again but with a higher energy than before. Such particles are accelerated to energies much higher than after the first acceleration. This mechanism plays a role in explaining earlier experimental observations of energetic suprathermal electrons i...

  3. Low energy proton beams from laser-generated plasma

    Czech Academy of Sciences Publication Activity Database

    Torrisi, L.; Giuffrida, L.; Margarone, Daniele; Caridi, F.; Di Bartolo, F.

    2011-01-01

    Roč. 653, č. 1 (2011), s. 140-144. ISSN 0168-9002 R&D Projects: GA ČR(CZ) GAP205/11/1165; GA MŠk(CZ) 7E09092; GA MŠk ED1.1.00/02.0061 Grant ostatní: ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061 Institutional research plan: CEZ:AV0Z10100523 Keywords : laser -generated plasma * proton acceleration * hydrogenated targets * proton yield * doped polymers Subject RIV: BH - Optics, Masers, Laser s Impact factor: 1.207, year: 2011

  4. Decomposition of chlorinated ethylenes and ethanes in an electron beam generated plasma reactor

    Energy Technology Data Exchange (ETDEWEB)

    Vitale, S.A.

    1996-02-01

    An electron beam generated plasma reactor (EBGPR) is used to determine the plasma chemistry kinetics, energetics and decomposition pathways of six chlorinated ethylenes and ethanes: 1,1,1-trichloroethane, 1,1-dichloroethane, ethyl chloride, trichloroethylene, 1,1-dichloroethylene, and vinyl chloride. A traditional chemical kinetic and chemical engineering analysis of the data from the EBGPR is performed, and the following hypothesis was verified: The specific energy required for chlorinated VOC decomposition in the electron beam generated plasma reactor is determined by the electron attachment coefficient of the VOC and the susceptibility of the molecule to radical attack. The technology was demonstrated at the Hanford Reservation to remove VOCs from soils.

  5. Low-impedance plasma systems for generation of high-current low-energy electron beams

    Science.gov (United States)

    Agafonov, A. V.

    2006-12-01

    The results of experimental investigation and numerical modeling of the generation of low-energy (tens of keV) high-current (up to tens of kA) electron beams in a low-impedance system consisting of a plasma-filled diode with a long plasma anode, an auxiliary hot cathode, and an explosive emission cathode. The low-current low-voltage beam from the auxiliary cathode in an external longitudinal magnetic field is used to produce a long plasma anode, which is simultaneously the channel of beam transportation by residual gas ionization. The high-current electron beam is formed from the explosive emission cathode placed in the preliminarily formed plasma. Numerical modeling is performed using the KARAT PIC code.

  6. Optical photography of the magnetically confined anode plasma source for repetitive intense ion beam generation

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.J.; Crawford, M.T.; Maenchen, J.E. [Sandia National Labs., Albuquerque, NM (United States)

    1996-12-31

    Time resolved photographs of the visible light from the Magnetically Confined Anode Plasma (MAP) source for Ion Beam Surface Treatment (IBEST) are presented. The MAP source utilizes a fast (2 {micro}s rise time) magnetic field to create a plasma in a radially injected disc shaped gas puff and subsequently inject this plasma into the accelerating gap of a 10-cm-radius high power pulsed extraction ion diode. The 600 kV, 10 kA, 100 ns duration pulse for the beam is generated by a marx generator, cable feed, and linear induction voltage adder. The application of this technology is the generation of repetitively pulsed ion beams for government and industrial treatment of metal and polymer surfaces.

  7. Anomalous electron heating and energy balance in an ion beam generated plasma

    International Nuclear Information System (INIS)

    The plasma described in this report is generated by a 15 to 34 kV ion beam, consisting primarily of protons, passing through an H2 gas cell neutralizer. Plasma ions (or ion-electron pairs) are produced by electron capture from (or ionization of) gas molecules by beam ions and atoms. An explanation is provided for the observed anomalous behavior of the electron temperature (T/sub e/): a step-lite, nearly two-fold jump in T/sub e/ as the beam current approaches that which minimizes beam angular divergence; insensitivity of T/sub e/ to gas pressure; and the linear relation of T/sub e/ to beam energy

  8. Terahertz generation by two cross focused Gaussian laser beams in magnetized plasma

    International Nuclear Information System (INIS)

    This paper presents a theoretical model for terahertz (THz) radiation generation by two cross-focused Gaussian laser beams in a collisionless magnetoplasma. The plasma is redistributed due to the ponderomotive nonlinearity which leads to the cross focusing of the laser beams. The focusing of the copropagating laser beams increases with increasing the externally applied static magnetic field which is perpendicular to the wave propagation direction. The nonlinear current at THz frequency arises on account of nonlinear ponderomotive force as a result of beating of the two lasers. The generated THz radiation amplitude increases significantly with increasing magnetic field. The cross focusing of two laser beams enhances the THz yield. Optimization of laser-plasma parameters gives the radiated normalized THz power of the order of 10 kW

  9. Electron-beam generated copper plasma: formation and cross-field propagation

    International Nuclear Information System (INIS)

    In an evaporator, when a high-energy continuous electron beam impinges a copper target, it generates an atomic beam. It is observed that plasma is formed. The primary and the backscattered electrons from the surface of the target produce copper plasma by electron-impact ionization of the atoms. The plasma is of low temperature, weakly ionized and is present in a weak transverse magnetic field. The magnetic field is used to bend the electrons from the gun. The plasma flows in a direction that is perpendicular to the target surface and transverse to the magnetic field. The plasma expansion is weakly collisional. It decays along the flow direction due to cross-field diffusion.

  10. Density and potential measurements in an intense ion beam-generated plasma

    International Nuclear Information System (INIS)

    Neutral beams are created by intense large area ion beams which are neutralized in a gas cell. The interaction of the beam with the gas cell creates a plasma. Such a plasma is studied here. The basic plasma parameters, electron temperature, density, and plasma potential, are measured as a function of beam current and neutral gas pressure. These measurements are compared to a model based on the solution of Poisson's equation. Because of the cylindrical geometry the equation cannot be solved analytically. Details of the numerical method are presented. Three refinements to existing models have been added. (1) The beam creates ions by charge exchange as well as by ionization. (2) In the ionization process most of the ions are born at rest but some of the ions are born through a molecular dissociation process which provides them with substantial energy. (3) Electrons are trapped in the potential well of the system. Their distribution will be truncated by the well and the usual Boltzmann relation for the density variation with potential will be altered slightly. Analytical expressions for these effects are obtained and included in the computer generated solution. The model and data are in good agreement only when locally determined beam current profiles are used in the solution. These profiles are broader than those determined from beam dump calorimetry

  11. Argon-dominated plasma beam generated by filtered vacuum arc and its substrate etching

    International Nuclear Information System (INIS)

    A new technique to etch a substrate as a pre-treatment prior to functional film deposition was developed using a filtered vacuum arc plasma. An Ar-dominated plasma beam was generated from filtered carbon arc plasma by introducing appropriate flow rate of Ar gas in a T-shape filtered arc deposition (T-FAD) system. The radiation spectra emitted from the filtered plasma beam in front of a substrate table were measured. The substrate was etched by the Ar-dominated plasma beam. The principal results are summarized as follows. At a high flow rate of Ar gas (50 ml/min), when the bias was applied to the substrate, the plasma was attracted toward the substrate table and the substrate was well etched without film formation on the substrate. Super hard alloy (WC), bearing steel (SUJ2), and Si wafer were etched by the Ar-dominated plasma beam. The etching rate was dependent on the kind of substrate. The roughness of the substrate increased, when the etching rate was high. A pulse bias etched the substrate without roughening the substrate surface excessively.

  12. Generation of tubular beams of negative hydrogen ions by a surface plasma source

    International Nuclear Information System (INIS)

    The results of experiments on obtaining a tubular beam of hydrogen negative ions from a surface plasma source with emission ring slit of 100 mm diameter are described in the study. Conditions of burning of a high current ring discharge generating effectively hydrogen negative ions with current density up to 2.1 A/cm2 are investigated. The possibility of generation of intensive tubular beams of hydrogen negative ions by surface plasma sources is shown, the 2.4 A ion beam is obtained. The results of preliminary experiments on accelerating tubular beam up to 135 keV are described. Azymuthally uniform current density distribution of intensive tubular beams generated by discharges with a close electron drift in a surface plasma source with emission ring slit, absence of high-frequency oscillations in optimal conditions of sources operation as well as the possibility of the most complete use of generated by the discharge negative ions flow show the prospects of development of these sources for fast atom injectors

  13. Neutron production and ion beam generation in plasma focus devices

    International Nuclear Information System (INIS)

    Concerning the physical processes leading to neutron emission, a clearer situation has been achieved compared to the state at the start of this work. The general discussion will realize that the whole experimental data cannot be described consistently by the predictions of either the beam-target model or the quasi-thermonuclear fusion model, although many questions about the neutron production properties have been solved. In particular the neutron fluence anisotropy is found to be a property basically related to the existence of fast ions escaping axially out of the pinch region. The requirements to explain broad radial neutron energy spectra, long emission times, and energetic but not spatial emission anisotropies suggest a kind of particle trapping in the main source region. (orig./HT)

  14. A reflex glow discharge as a plasma source for broad area electron beam generation

    International Nuclear Information System (INIS)

    The authors demonstrated an electron beam generation scheme in which two glow discharge electron guns are used in a reflex configuration to create a dense and cold plasma in a large volume. The thermal electrons from this plasma, created mainly by electron beam ionization, are subsequently accelerated in the gap between two grids by an externally applied electric field to produce a broad area electron beam. This electron beam current density and energy are independently controlled by the voltage applied to the glow discharge guns and by the electric field sustained between the grids respectively. They present a schematic representation of the electron gun used in the experimental demonstration of the concept reported here

  15. Second harmonic generation by self-focusing of intense hollow Gaussian laser beam in collisionless plasma

    International Nuclear Information System (INIS)

    The effect of self focused hollow Gaussian laser beam (HGLB) (carrying null intensity in center) on the excitation of electron plasma wave (EPW) and second harmonic generation (SHG) has been investigated in collisionless plasma, where relativistic-ponderomotive and only relativistic nonlinearities are operative. The relativistic change of electron mass and the modification of the background electron density due to ponderomotive nonlinearity lead to self-focusing of HGLB in plasma. Paraxial ray theory has been used to derive coupled equations for the self focusing of HGLB in plasma, generation of EPW, and second harmonic. These coupled equations are solved analytically and numerically to study the laser intensity in the plasma, electric field associated with the excited EPW, and the power of SHG. Second harmonic emission is generated due to nonlinear coupling between incident HGLB and EPW satisfying the proper phase matching conditions. The results show that the effect of including the ponderomotive nonlinearity is significant on the generation of EPW and second harmonic. The electric field associated with EPW and the power of SHG are found to be highly sensitive to the order of the hollow Gaussian beam

  16. Study of second harmonic generation by high power laser beam in magneto plasma

    International Nuclear Information System (INIS)

    This paper examines the problem of nonlinear generation of second harmonic of a high power laser pulse propagating in magnetized plasma. The propagation of strong laser beam is proposed in the direction perpendicular to a relatively weak static magnetic field. The laser pulse is taken to be linearly polarized, with the orientation of its electric field that corresponds to an ordinary electromagnetic wave. Besides the standard ponderomotive nonlinearity, the appropriate wave equation also contains the nonlinearity that arises from the relativistic electron jitter velocities. During its propagation, the laser beam gets filamented on account of relativistic and pondermotive nonlinearities present in the plasma. The generated plasma wave gets coupled into the filamentary structures of the pump beam. Due to the expected presence of the beam filamentation, the work has been carried out by considering modified paraxial approximation (i.e., beyond the standard paraxial approximation of a very broad beam). It is found that the power of the plasma wave is significantly affected by the magnetic field strength in the presence of both relativistic and pondermotive nonlinearities. It is investigated that the second harmonic generation is also considerably modified by altering the strength of magnetic field. To see the effect of static magnetic field on the harmonic generation, a key parameter, i.e., the ratio of the cyclotron frequency ωc=eB0/mc over the laser frequency ω0 has been used, where c is the velocity of light, m and e are the mass and charge of the electron and B0 is the externally applied magnetic field.

  17. Development of beam-plasma instability in systems for short-pulse microwave generation

    International Nuclear Information System (INIS)

    The development of conventional beam-plasma instability in a system penetrated by short electron bunches is considered. The fields induced by the bunches' edges increase exponentially and actually serve as initial perturbations for instability development. It is shown that superposition of the field induced by front and back edges results in a complicated configuration that can affect various aspects of operation of devices for short-pulse microwave generation, e.g. transient processes

  18. Plasma waves generated during an artificial argon-ion beam experiments in the ionosphere

    International Nuclear Information System (INIS)

    An active ion experiment was performed in the nighttime polar cap ionosphere. The active ion-beam experiment, Auroral Rocket for Controlled Studies ARC 3, was designed to perturb the ionosphere in a controlled manner. The plasma perturbations were observed by instruments on board the main payload (MPL) and subpayload (SPL). The ARCS 3 experiment was different from previous experiments in that two plasma generators, located on the SPL, were oriented so as to inject a beam approximately perpendicular and anti-parallel to the magnetic field. The ARCS 3 experiment included 9 perpendicular and 8 parallel ion beam injections. During the experiment electrostatic ion waves near the harmonics of the hydrogen, oxygen, and possibly argon gyrofrequency were excited by the perpendicular argon ion beam. An absorption feature of the vlf hiss band at the hydrogen gyrofrequency harmonics was also observed during the fourth perpendicular event. During parallel events, the sixth, and seventh perpendicular events electric field fluctuations were recorded near the lower hybrid (LH) frequency. It is suggested that the unexpected perpendicular ion flux observed during parallel events and the perpendicular ion flux observed during parallel events and the perpendicular argon ion beam generates the waves near the LH frequency. Electric-field fluctuations were observed up to and including the seventh perpendicular and parallel events

  19. Auto generation of powerful high frequency oscillations in the beam-plasma discharge with cold cathode

    International Nuclear Information System (INIS)

    As it was shown previously, under certain conditions plasma-surface interaction with floating or negatively biased electrodes exhibits enhanced emission of secondary electrons and sets unstable. Intensive and highly non-equilibrium axial plasma flows were generated by means of an electron-beam driven discharge in a mirror machine type magnetic field. Tunable RF electromagnetic oscillations can arise in the outer LC-contour coupled with biased electrode due to intrinsic instability of its emissivity. Auxiliary heating of the incident plasma flow (by electric field oscillations in the sheath and by secondary electrons accelerated in sheath potential drop) affects energy dissipation as well as particle generation and transport in discharge volume. In particular, self-maintained RF-autogenerating discharge with cold cathode can be realized. New experimental data on the phenomenon of RF auto generation indicate that the electrode surface composition and structure generated during bombardment by ionized and exitated particles can play the principal role in dynamics of the plasma sheath electrostatic drop. Provided stable thin layers of oxide dielectrics appear on the plasma facing electrode surface, effect becomes more pronounced and efficiency of RF power generation increases

  20. About generation of subharmonics and stochastic regimes arising in periodic plasma-filled waveguides excited by charged beam

    International Nuclear Information System (INIS)

    Various mechanisms for generation of subharmonics in periodic plasma-filled waveguides excited by charged beam are considered. It is shown that beam particles seized by the excited electromagnetic wave can demonstrate under certain conditions the complex dynamics that results in generation of subharmonics and cause the transition to the stochastic regime of the instability

  1. Energetic high current density electron/ion beam generation in plasma opening switches

    International Nuclear Information System (INIS)

    Experimental results on the generation of high energy ion/electron beams during operation of microsecond/nanosecond Plasma Opening Switch (POS) are presented. For the nanosecond POS, a coaxial configuration with negatively charged central electrode was used. For the microsecond POS, a strip-line geometry was investigated. Different arrays of magnetically insulated Collimated Faraday Cups (CFC) were used to observe energetic electron/ion flows towards the anode/cathode POS electrodes and towards the load. It was shown that in both nanosecond and microsecond cases, high-energy high current density axial ion flows are generated downstream towards the load at the load side edge of the plasma. The main axial ion acceleration occurs in the first few cm downstream with respect to the load side edge of the plasma at the beginning of the POS opening. Data observed by the anode CFC array show fast axial propagation of a radial electron flow along the anode electrode towards the load which is accompanied by an ion flow that first appears at the generator side of the plasma. (author). 10 figs., 10 refs

  2. Plasma generation at atmospheric pressure using a high power microwave beam and its application to rocket propulsion

    International Nuclear Information System (INIS)

    Experiments on microwave plasma generation and its application to microwave beamed energy propulsion were conducted using a 1 MW-class, 170 GHz gyrotron. The microwave beam was focused using a parabola reflector and plasma was initiated near the focal point in the ambient air. Plasma propagated upstream in the microwave beam channel while absorbing microwave. Its propagation velocity was supersonic when the microwave power density was larger than 75 kW/cm2. The propulsive impulse was measured using a cone-cylinder shaped thruster model. As a result, maximum momentum coupling coefficient was obtained at a certain plasma propagation distance. In addition, large momentum coupling coefficient was obtained when plasma was propagated at a supersonic velocity. It would be because supersonic plasma propagation forms a strong shock wave, resulting in an efficient pressure increase. (author)

  3. Experimental Beam Studies of Plasma-generated Species Interaction with Polymeric Materials and Biomolecules

    OpenAIRE

    Chung, Ting-Ying

    2012-01-01

    Low temperature plasma-based processes are used extensively in many modern technologies. It is thus very important to understand plasma and surface interactions in order to improve plasma processes and design of functional materials. Applying a high vacuum beam system, this dissertation studies the fundamental mechanisms of plasma species-induced modification of materials for two critical applications: manufacturing of semiconductor devices and surface deactivation of infectious biomolecules....

  4. Focusing of laser-generated ion beams by a plasma cylinder: similarity theory and the thick lens formula

    OpenAIRE

    Gordienko, S.; Baeva, T.; Pukhov, A.

    2005-01-01

    It is shown that plasma-based optics can be used to guide and focus highly divergent laser-generated ion beams. A hollow cylinder is considered, which initially contains a hot electron population. Plasma streaming toward the cylinder axis maintains a focusing electrostatic field due to the positive radial pressure gradient. The cylinder works as thick lens, whose parameters are obtained from similarity theory for freely expanding plasma in cylindrical geometry. Because the lens parameters are...

  5. Second harmonic generation of q-Gaussian laser beam in preformed collisional plasma channel with nonlinear absorption

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Naveen, E-mail: naveens222@rediffmail.com; Singh, Arvinder, E-mail: arvinder6@lycos.com [Department of Physics, National Institute of Technology Jalandhar (India); Singh, Navpreet, E-mail: navpreet.nit@gmail.com [Guru Nanak Dev University College, Kapurthala, Punjab (India)

    2015-11-15

    This paper presents a scheme for second harmonic generation of an intense q-Gaussian laser beam in a preformed parabolic plasma channel, where collisional nonlinearity is operative with nonlinear absorption. Due to nonuniform irradiance of intensity along the wavefront of the laser beam, nonuniform Ohmic heating of plasma electrons takes place. Due to this nonuniform heating of plasma, the laser beam gets self-focused and produces strong density gradients in the transverse direction. The generated density gradients excite an electron plasma wave at pump frequency that interacts with the pump beam to produce its second harmonics. The formulation is based on a numerical solution of the nonlinear Schrodinger wave equation in WKB approximation followed by moment theory approach. A second order nonlinear differential equation governing the propagation dynamics of the laser beam with distance of propagation has been obtained and is solved numerically by Runge Kutta fourth order technique. The effect of nonlinear absorption on self-focusing of the laser beam and conversion efficiency of its second harmonics has been investigated.

  6. Second harmonic generation of q-Gaussian laser beam in preformed collisional plasma channel with nonlinear absorption

    International Nuclear Information System (INIS)

    This paper presents a scheme for second harmonic generation of an intense q-Gaussian laser beam in a preformed parabolic plasma channel, where collisional nonlinearity is operative with nonlinear absorption. Due to nonuniform irradiance of intensity along the wavefront of the laser beam, nonuniform Ohmic heating of plasma electrons takes place. Due to this nonuniform heating of plasma, the laser beam gets self-focused and produces strong density gradients in the transverse direction. The generated density gradients excite an electron plasma wave at pump frequency that interacts with the pump beam to produce its second harmonics. The formulation is based on a numerical solution of the nonlinear Schrodinger wave equation in WKB approximation followed by moment theory approach. A second order nonlinear differential equation governing the propagation dynamics of the laser beam with distance of propagation has been obtained and is solved numerically by Runge Kutta fourth order technique. The effect of nonlinear absorption on self-focusing of the laser beam and conversion efficiency of its second harmonics has been investigated

  7. Electron beam generation in a diode with a gaseous plasma electron source II: Plasma source based on a hollow anode ignited by a hollow-cathode source

    International Nuclear Information System (INIS)

    We describe the operation of a hollow plasma anode (HPA) with a hollow cathode incorporated in it for the production of preliminary plasma. The operation of the hollow anode was studied with a discharge current amplitude up to 1 kA. It was shown that the gaseous discharge is realized without formation of plasma spots at the anode wall and the output grid. The plasma parameters inside the HPA were measured for different N2 gas pressures and discharge current amplitudes. It was found that the plasma acquires a positive potential with respect to the anode and that the plasma density and temperature are ≤5x1012 cm-3 and ≤10 eV, respectively. This plasma source was used as a cathode in a diode for the generation of high-current electron beams under an accelerating-voltage ≤250 kV and 400 ns pulse duration. The characteristics of the diode and the generated electron beam as a function of the HPA parameters are presented. It was found that at the beginning of the accelerating pulse the diode operates in a plasma prefilled mode, and further in the accelerating pulse the diode current is determined by the emission capability of the HPA. It was shown that this source allows reliable generation of a uniform electron beam with a cross-sectional area of 100 cm2 and a current amplitude up to 1 kA without the formation of explosive plasma at the HPA output grid

  8. Generation of high charge state metal ion beams by electron cyclotron resonance heating of vacuum arc plasma in cusp trap.

    Science.gov (United States)

    Nikolaev, A G; Savkin, K P; Oks, E M; Vizir, A V; Yushkov, G Yu; Vodopyanov, A V; Izotov, I V; Mansfeld, D A

    2012-02-01

    A method for generating high charge state heavy metal ion beams based on high power microwave heating of vacuum arc plasma confined in a magnetic trap under electron cyclotron resonance conditions has been developed. A feature of the work described here is the use of a cusp magnetic field with inherent "minimum-B" structure as the confinement geometry, as opposed to a simple mirror device as we have reported on previously. The cusp configuration has been successfully used for microwave heating of gas discharge plasma and extraction from the plasma of highly charged, high current, gaseous ion beams. Now we use the trap for heavy metal ion beam generation. Two different approaches were used for injecting the vacuum arc metal plasma into the trap--axial injection from a miniature arc source located on-axis near the microwave window, and radial injection from sources mounted radially at the midplane of the trap. Here, we describe preliminary results of heating vacuum arc plasma in a cusp magnetic trap by pulsed (400 μs) high power (up to 100 kW) microwave radiation at 37.5 GHz for the generation of highly charged heavy metal ion beams. PMID:22380156

  9. On Generation and Propagation of the Plasma Ion Beam for Plasma Ion Assisted Deposition (PIAD) of Optical Coatings

    Science.gov (United States)

    Harhausen, J.; Brinkmann, R. P.; Foest, R.; Ohl, A.; Schröder, B.

    2011-10-01

    PIAD is a technique employed for the production of high performance optical coatings. Here, the plasma source is a hot cathode direct current discharge with an auxiliary magnetic field (APS). Its specific design together with a low chamber pressure of p ~ 2 .10-4mbar results in the generation of energetic ions (typ. Ei = 50 . . 150eV) impinging onto the substrates. Until today, data on the plasma parameters in the coating chamber is sparse. This contribution presents details on the energy distribution functions (EDF) of electrons and ions in the strongly inhomogeneous APS plume using Langmuir probe and retarding field energy analyzer diagnostics. The IEDF is characterized by two separate populations of low and high energy. An analytical model for the evolution of the ion beam reveals that the slow ion component is due to charge exchange of fast ions with the background neutral gas. This model is indispensable for the estimation of the NEDF. Funded by the German Ministry for Education and Research (BMBF, Fkz. 13N10462).

  10. Experimental research of different plasma cathodes for generation of high-current electron beams

    International Nuclear Information System (INIS)

    The results of experimental studies of different types of cathodes—carbon-epoxy rods, carbon-epoxy capillary, edged graphite, and metal-dielectric—under the application of high-voltage pulses with an amplitude of several hundreds of kV and pulse duration of several nanoseconds are presented. The best diode performance was achieved with the edged graphite and carbon-epoxy-based cathodes characterized by uniform and fast (<1 ns) formation of explosive emission plasma spots and quasi-constant diode impedance. This result was achieved for both annular cathodes in a strong magnetic field and planar cathodes of a similar diameter (∼2 cm) with no external magnetic field. The cathodes based on carbon-epoxy rods and carbon-epoxy capillaries operating with an average current density up to 1 kA/cm2 showed insignificant erosion along 106 pulses of the generator and the generated electron beam current showed excellent reproducibility in terms of the amplitude and waveform

  11. Experimental research of different plasma cathodes for generation of high-current electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Shafir, G.; Kreif, M.; Gleizer, J. Z.; Gleizer, S.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel); Gunin, A. V.; Kutenkov, O. P.; Rostov, V. V. [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Pegel, I. V. [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Tomsk Polytechnic University, Tomsk 634034 (Russian Federation)

    2015-11-21

    The results of experimental studies of different types of cathodes—carbon-epoxy rods, carbon-epoxy capillary, edged graphite, and metal-dielectric—under the application of high-voltage pulses with an amplitude of several hundreds of kV and pulse duration of several nanoseconds are presented. The best diode performance was achieved with the edged graphite and carbon-epoxy-based cathodes characterized by uniform and fast (<1 ns) formation of explosive emission plasma spots and quasi-constant diode impedance. This result was achieved for both annular cathodes in a strong magnetic field and planar cathodes of a similar diameter (∼2 cm) with no external magnetic field. The cathodes based on carbon-epoxy rods and carbon-epoxy capillaries operating with an average current density up to 1 kA/cm{sup 2} showed insignificant erosion along 10{sup 6} pulses of the generator and the generated electron beam current showed excellent reproducibility in terms of the amplitude and waveform.

  12. Second harmonic generation by propagation of a p-polarized obliquely incident laser beam in underdense plasma

    International Nuclear Information System (INIS)

    An analytical study of second harmonic generation due to interaction an intense, p-polarized laser beam propagating obliquely in homogeneous underdense plasma, in the mildly relativistic regime, has been presented. The efficiency of the second harmonic radiation as well as its detuning length has been obtained and their variation with the angle of incidence is analyzed. It is shown that, for a given plasma electron density, the second harmonic efficiency increases with the angle of incidence while the detuning length decreases. The second harmonic amplitude vanishes at normal incidence of the laser beam

  13. Diagnostics of ion beam generated from a Mather type plasma focus device

    Energy Technology Data Exchange (ETDEWEB)

    Lim, L. K., E-mail: yapsl@um.edu.my; Ngoi, S. K., E-mail: yapsl@um.edu.my; Wong, C. S., E-mail: yapsl@um.edu.my; Yap, S. L., E-mail: yapsl@um.edu.my [Plasma Technology Research Centre, Department of Physics, Faculty of Science, University of Malaya (Malaysia)

    2014-03-05

    Diagnostics of ion beam emission from a 3 kJ Mather-type plasma focus device have been performed for deuterium discharge at low pressure regime. Deuterium plasma focus was found to be optimum at pressure of 0.2 mbar. The energy spectrum and total number of ions per shot from the pulsed ion beam are determined by using biased ion collectors, Faraday cup, and solid state nuclear track detector CR-39. Average energy of the ion beam obtained is about 60 keV. Total number of the ions has been determined to be in the order of 10{sup 11} per shot. Solid state nuclear track detectors (SSNTD) CR39 are employed to measure the particles at all angular direction from end on (0°) to side on (90°). Particle tracks are registered by SSNTD at 30° to 90°, except the one at the end-on 0°.

  14. Self focusing of laser beams and its effect in the generation of magnetic field in laser-produced plasma

    International Nuclear Information System (INIS)

    The present work deals with the generation of magnetic field in a plasma due to self focusing effects of laser beam. Spontaneously generated magnetic fields of the order of several kilogauss have been investigated and the cause for the generation of B-field has been attributed to the time dependent ponderomotive force of a self focused inhomogeneous gaussian shaped laser beam. The magnitude of the magnetic field is found to increase with self focusing effect of the laser beam. It can be shown that for high-frequency laser (viz. Nd-glass laser having the wavelength (λ) = 1.06 μm and amplitude of E-field (E00) = 3.9 x 1011 V/m), the magnitude of B-field is found to be in better agreement with the experiment. B-field varies inversely with temperature which has not been taken care in earlier reports. (author)

  15. Terahertz generation by relativistic ponderomotive focusing of two co-axial Gaussian laser beams propagating in ripple density plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Subodh; Singh, Ram Kishor, E-mail: ram007kishor@gmail.com; Sharma, R. P. [Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2015-10-15

    Terahertz (THz) generation by beating of two co-axial Gaussian laser beams, propagating in ripple density plasma, has been studied when both ponderomotive and relativistic nonlinearities are operative. When the two lasers co-propagate in rippled density plasma, electrons acquire a nonlinear velocity at beat frequency in the direction transverse to the direction of propagation. This nonlinear oscillatory velocity couples with the density ripple to generate a nonlinear current, which in turn generates THz radiation at the difference frequency. The necessary phase matching condition is provided by the density ripple. Relativistic ponderomotive focusing of the two lasers and its effects on yield of the generated THz amplitude have been discussed. Numerical results show that conversion efficiency of the order of 10{sup −3} can be achieved in the terahertz radiation generation with relativistic ponderomotive focusing.

  16. Generation of phase - matched coherent point source in plasma media by propagated X-ray laser seeded beam

    Science.gov (United States)

    Pikuz, T.; Faenov, A.; Magnitskiy, S.; Nagorskiy, N.; Tanaka, M.; Ishino, M.; Nishikino, M.; Kando, M.; Kato, Y.; Kawachi, T.

    2016-03-01

    There is a significant interest in developing the coherent table-top X-ray lasers. Advent of plasma-based transient collisional excitation x-ray laser and particular, injection of coherent seeded beam, especially high-order harmonics, has tremendously improved the spatial coherence of such lasers, what allowed them to be the same widely used as synchrotron sources. Here we report experimental founding of unknown interference structure in a spatial profile of the output beam of the two-stage plasma X-ray laser. That allowed us experimental and theoretical discovering a new phenomenon consisted in a generation of phase-matched coherent point source in a laser plasma media by propagated X-ray laser seeded beam. This phenomenon could extend the applications of such x-ray lasers. For explanation of the observed phenomenon a new method of solving the standard system of Maxwell-Bloch equations has been developed. It was found that the interference pattern in the output laser beam was formed due to an emergence of phase-matched coherent virtual point source in the XRL amplifier and could be treated as the first observation of mirage phenomenon, analogous to the optical mirage, but in X-rays. The obtained results bring new comprehension into the physical nature of amplification of X-ray radiation in laser-induced plasma amplifiers and opening new opportunities for X-ray interferometry, holography and other applications, which requiring multiple rigidly phased sources of coherent radiation.

  17. Large area ion and plasma beam sources

    International Nuclear Information System (INIS)

    In the past a number of ion beam sources utilizing different methods for plasma excitation have been developed. Nevertheless, a widespread use in industrial applications has not happened, since the sources were often not able to fulfill specific demands like: broad homogeneous ion beams, compatibility with reactive gases, low ion energies at high ion current densities or electrical neutrality of the beam. Our contribution wants to demonstrate technical capabilities of rf ion and plasma beam sources, which can overcome the above mentioned disadvantages. The physical principles and features of respective sources are presented. We report on effective low pressure plasma excitation by electron cyclotron wave resonance (ECWR) for the generation of dense homogeneous plasmas and the rf plasma beam extraction method for the generation of broad low energy plasma beams. Some applications like direct plasma beam deposition of a-C:H and ion beam assisted deposition of Al and Cu with tailored thin film properties are discussed. (orig.)

  18. Focusing of laser-generated ion beams by a plasma cylinder: Similarity theory and the thick lens formula

    International Nuclear Information System (INIS)

    It is shown that plasma-based optics can be used to guide and focus highly divergent laser-generated ion beams. A hollow cylinder is considered, which initially contains a hot electron population. Plasma streaming toward the cylinder axis maintains a focusing electrostatic field due to the positive radial pressure gradient. The cylinder works as a thick lens, whose parameters are obtained from similarity theory for freely expanding plasma in cylindrical geometry. Because the lens parameters are energy dependent, the lens focuses a selected energy range of ions and works as a monochromator. Because the focusing is due to the quasineutral part of the expanding plasma, the lens parameters depend on the hot electron temperature Te only, and not their density

  19. On the use of intense ion beams for generating magnetized target fusion plasma

    International Nuclear Information System (INIS)

    Magnetized Target Fusion (MTF) is a concept for creating a burning D-T plasma in a potentially inexpensive system. In essence, the concept involves ion heating on time scales short compared to ion transport times plus strong inhibition of thermal electron transport with a transverse magnetic field. The magnetic field is not intended to confine the ionic component. MTF is an intrinsically pulsed concept. A straightforward analysis of MTF indicates that D-T burning conditions can be achieved in compact plasma volumes with modest initial temperatures, through the use of pulsed power technology. In terms of size, density, temperature, and time scales, MTF occupies a position in phase space that is intermediate between steady MFE schemes and ICF. In terms of cost, it is one to two orders of magnitude less expensive than these. In this paper, the authors consider a possible method for creating the initial conditions adequate for the MTF concept through the use intense ion beam injection

  20. Generation and pointing stabilization of multi-GeV electron beams from a laser plasma accelerator driven in a pre-formed plasma waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Gonsalves, A. J.; Nakamura, K.; Daniels, J.; Mao, H.-S.; Benedetti, C.; Schroeder, C. B.; Tóth, Cs.; Tilborg, J. van; Vay, J.-L.; Geddes, C. G. R.; Esarey, E. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Mittelberger, D. E.; Bulanov, S. S.; Leemans, W. P., E-mail: WPLeemans@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States)

    2015-05-15

    Laser pulses with peak power 0.3 PW were used to generate electron beams with energy >4 GeV within a 9 cm-long capillary discharge waveguide operated with a plasma density of ≈7×10{sup 17} cm{sup −3}. Simulations showed that the super-Gaussian near-field laser profile that is typical of high-power femtosecond laser systems reduces the efficacy of guiding in parabolic plasma channels compared with the Gaussian laser pulses that are typically simulated. In the experiments, this was mitigated by increasing the plasma density and hence the contribution of self-guiding. This allowed for the generation of multi-GeV electron beams, but these had angular fluctuation ≳2 mrad rms. Mitigation of capillary damage and more accurate alignment allowed for stable beams to be produced with energy 2.7±0.1 GeV. The pointing fluctuation was 0.6 mrad rms, which was less than the beam divergence of ≲1 mrad full-width-half-maximum.

  1. Suppression of multiple ion bunches and generation of monoenergetic ion beams in laser foil-plasma

    Institute of Scientific and Technical Information of China (English)

    Zhang Shan; Xie Bai-Song; Hong Xue-Ren; Wu Hai-Cheng; Aimierding Aimidula; Zhao Xue-Yan; Liu Ming-Ping

    2011-01-01

    In one-dimensional particle-in-cell simulations, this paper shows that the formation of multiple ion bunches is disadvantageous to the generation of monoenergetic ion beams and can be suppressed by choosing an optimum target thickness in the radiation pressure acceleration mechanism by a circularly polarised laser pulse. As the laser pulse becomes intense, the optimum target thickness obtained by a non-relativistic treatment is no longer adequate. Considering the relativistic Doppler-shifted pressure, it proposes a relativistic formulation to determine the optimum target thickness. The theoretical predictions agree with the simulation results well. The model is also valid for two-dimensional cases. The accelerated ion beams can be compelled to be more stable by choosing the optimum target thickness when they exhibit some unstable behaviours.

  2. Educating the next generation in the science and technology of plasmas, beams and accelerators

    Science.gov (United States)

    Barletta, Wiliam

    2007-11-01

    Accelerators are essential tools for discovery in fundamental physics, biology, and chemistry. Particle beam based instruments in medicine, industry and national security constitute a multi-billion dollar per year industry. More than 55,000 peer-reviewed papers having accelerator as a keyword are available on the Web. Yet only a handful of universities offer any formal training in accelerator science. Several reasons can be cited: 1) The science and technology of non-neutral plasmas cuts across traditional academic disciplines. 2) Electrical engineering departments have evolved toward micro- and nano-technology and computing science. 3) Nuclear physics departments have atrophied. 4) With few exceptions, interest at individual universities is not extensive enough to support a strong faculty line. The United States Particle Accelerator School (USPAS) is National Graduate Educational Program that has developed an educational paradigm that, over the past twenty-years, has granted more university credit in accelerator / beam science and technology than any university in the world. Governed and supported by a consortium of nine DOE laboratories and two NSF university laboratories, USPAS offers a responsive and balanced curriculum of science, engineering, and hands-on courses. Sessions are held twice annually, hosted by major US research universities that approve course credit, certify the USPAS faculty, and grant course credit. The USPAS paradigm is readily extensible to other rapidly developing, cross-disciplinary research areas such as high energy density physics.

  3. Chemical kinetics and relaxation of non-equilibrium air plasma generated by energetic photon and electron beams

    Science.gov (United States)

    Maulois, Melissa; Ribière, Maxime; Eichwald, Olivier; Yousfi, Mohammed; Azaïs, Bruno

    2016-04-01

    The comprehension of electromagnetic perturbations of electronic devices, due to air plasma-induced electromagnetic field, requires a thorough study on air plasma. In the aim to understand the phenomena at the origin of the formation of non-equilibrium air plasma, we simulate, using a volume average chemical kinetics model (0D model), the time evolution of a non-equilibrium air plasma generated by an energetic X-ray flash. The simulation is undertaken in synthetic air (80% N2 and 20% O2) at ambient temperature and atmospheric pressure. When the X-ray flash crosses the gas, non-relativistic Compton electrons (low energy) and a relativistic Compton electron beam (high energy) are simultaneously generated and interact with the gas. The considered chemical kinetics scheme involves 26 influent species (electrons, positive ions, negative ions, and neutral atoms and molecules in their ground or metastable excited states) reacting following 164 selected reactions. The kinetics model describing the plasma chemistry was coupled to the conservation equation of the electron mean energy, in order to calculate at each time step of the non-equilibrium plasma evolution, the coefficients of reactions involving electrons while the energy of the heavy species (positive and negative ions and neutral atoms and molecules) is assumed remaining close to ambient temperature. It has been shown that it is the relativistic Compton electron beam directly created by the X-ray flash which is mainly responsible for the non-equilibrium plasma formation. Indeed, the low energy electrons (i.e., the non-relativistic ones) directly ejected from molecules by Compton collisions contribute to less than 1% on the creation of electrons in the plasma. In our simulation conditions, a non-equilibrium plasma with a low electron mean energy close to 1 eV and a concentration of charged species close to 1013 cm-3 is formed a few nanoseconds after the peak of X-ray flash intensity. 200 ns after the flash

  4. Third harmonic generation of a short pulse laser in a plasma density ripple created by a machining beam

    International Nuclear Information System (INIS)

    An intense machining laser beam, impinged on a gas jet target, causes space periodic ionization of the gas and heats the electrons. The nonuniform plasma pressure leads to atomic density redistribution. When, after a suitable time delay, a second more intense laser pulse is launched along the periodicity wave vector q-vector, a plasma density ripple nq is instantly created, leading to resonant third harmonic generation when q=4ωp2/(3ωcγ0), where ωp is the plasma frequency, ω is the laser frequency, and γ0 is the electron Lorentz factor. The third harmonic is produced through the beating of ponderomotive force induced second harmonic density oscillations and the quiver velocity of electrons at the fundamental. The relativistic mass nonlinearity plays no role in resonant coupling. The energy conversion efficiency scales as the square of plasma density and square of depth of density ripple, and is ∼0.2% for normalized laser amplitude ao∼1 in a plasma of 1% critical density with 20% density ripple. The theory explains several features of a recent experiment

  5. Plasma lenses for focusing particle beams

    International Nuclear Information System (INIS)

    The focusing of particles by a thin plasma lens is analyzed with physical, linearized fluid and particle-in-cell computational models. For parameters similar to next-generation linear colliders, the plasma lens strength can exceed 100 MG/cm, and the luminosity can be enhanced by an order of magnitude by passing each beam through an appropriate plasma slab. The plasma electrons affect the focusing by shifting so as to (partially or completely) charge neutralize the beam. Both overdense and underdense plasma lenses are described (plasma density n0 greater or less than beam density nb). The former case applies equally well to e+ and e- beams, while the latter has distinct advantages for e- beams (including smaller aberrations and background). The effects of spherical and longitudinal aberrations, emittance, plasma boundaries, and non-linear-plasma dynamics on the final spot size are discussed

  6. One-dimensional Ar-SF6 hydromodel at low-pressure in e-beam generated plasmas

    International Nuclear Information System (INIS)

    A one-dimensional steady-state hydrodynamic model of electron beam generated plasmas produced in Ar-SF6 mixtures at low pressure in a constant magnetic field was developed. Simulations were performed for a range of SF6 partial pressures at constant 30 mTorr total gas pressure to determine the spatial distribution of species densities and fluxes. With the addition of small amount of SF6 (∼1%), the confining electrostatic field sharply decreases with respect to the pure argon case. This effect is due to the applied magnetic field inhibiting electron diffusion. The hallmark of electronegative discharge plasmas, positive ion—negative ion core and positive ion—electron edge, was not observed. Instead, a plasma with large electronegativity (∼100) is formed throughout the volume, and only a small fraction (≈30%) of the parent SF6 molecules were dissociated to F2, SF2, and SF4. Importantly, F radical densities were found to be very low, on the order of the ion density. Model predictions for the electron density, ion density, and plasma electronegativity are in good agreement with experimental data over the entire range of SF6 concentrations investigated

  7. One-dimensional Ar-SF{sub 6} hydromodel at low-pressure in e-beam generated plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, George M., E-mail: george.petrov@nrl.navy.mil; Boris, David R.; Petrova, Tzvetelina B.; Walton, Scott G. [Plasma Physics Division, Naval Research Laboratory, 4555 Overlook Ave. SW, Washington DC 20375-5346 (United States)

    2016-03-15

    A one-dimensional steady-state hydrodynamic model of electron beam generated plasmas produced in Ar-SF{sub 6} mixtures at low pressure in a constant magnetic field was developed. Simulations were performed for a range of SF{sub 6} partial pressures at constant 30 mTorr total gas pressure to determine the spatial distribution of species densities and fluxes. With the addition of small amount of SF{sub 6} (∼1%), the confining electrostatic field sharply decreases with respect to the pure argon case. This effect is due to the applied magnetic field inhibiting electron diffusion. The hallmark of electronegative discharge plasmas, positive ion—negative ion core and positive ion—electron edge, was not observed. Instead, a plasma with large electronegativity (∼100) is formed throughout the volume, and only a small fraction (≈30%) of the parent SF{sub 6} molecules were dissociated to F{sub 2}, SF{sub 2}, and SF{sub 4}. Importantly, F radical densities were found to be very low, on the order of the ion density. Model predictions for the electron density, ion density, and plasma electronegativity are in good agreement with experimental data over the entire range of SF{sub 6} concentrations investigated.

  8. Runaway electron generation as possible trigger for enhancement of magnetohydrodynamic plasma activity and fast changes in runaway beam behavior

    Energy Technology Data Exchange (ETDEWEB)

    Pankratov, I. M., E-mail: pankratov@kipt.kharkov.ua, E-mail: rjzhou@ipp.ac.cn [Institute of Plasma Physics, NSC Kharkov Institute of Physics and Technology, Academicheskaya Str. 1, 61108 Kharkov (Ukraine); Zhou, R. J., E-mail: pankratov@kipt.kharkov.ua, E-mail: rjzhou@ipp.ac.cn; Hu, L. Q. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2015-07-15

    Peculiar phenomena were observed during experiments with runaway electrons: rapid changes in the synchrotron spot and its intensity that coincided with stepwise increases in the electron cyclotron emission (ECE) signal (cyclotron radiation of suprathermal electrons). These phenomena were initially observed in TEXTOR (Tokamak Experiment for Technology Oriented Research), where these events only occurred in the current decay phase or in discharges with thin stable runaway beams at a q = 1 drift surface. These rapid changes in the synchrotron spot were interpreted by the TEXTOR team as a fast pitch angle scattering event. Recently, similar rapid changes in the synchrotron spot and its intensity that coincided with stepwise increases in the non-thermal ECE signal were observed in the EAST (Experimental Advanced Superconducting Tokamak) runaway discharge. Runaway electrons were located around the q = 2 rational magnetic surface (ring-like runaway electron beam). During the EAST runaway discharge, stepwise ECE signal increases coincided with enhanced magnetohydrodynamic (MHD) activity. This behavior was peculiar to this shot. In this paper, we show that these non-thermal ECE step-like jumps were related to the abrupt growth of suprathermal electrons induced by bursting electric fields at reconnection events during this MHD plasma activity. Enhancement of the secondary runaway electron generation also occurred simultaneously. Local changes in the current-density gradient appeared because of local enhancement of the runaway electron generation process. These current-density gradient changes are considered to be a possible trigger for enhancement of the MHD plasma activity and the rapid changes in runaway beam behavior.

  9. Runaway electron generation as possible trigger for enhancement of magnetohydrodynamic plasma activity and fast changes in runaway beam behavior

    International Nuclear Information System (INIS)

    Peculiar phenomena were observed during experiments with runaway electrons: rapid changes in the synchrotron spot and its intensity that coincided with stepwise increases in the electron cyclotron emission (ECE) signal (cyclotron radiation of suprathermal electrons). These phenomena were initially observed in TEXTOR (Tokamak Experiment for Technology Oriented Research), where these events only occurred in the current decay phase or in discharges with thin stable runaway beams at a q = 1 drift surface. These rapid changes in the synchrotron spot were interpreted by the TEXTOR team as a fast pitch angle scattering event. Recently, similar rapid changes in the synchrotron spot and its intensity that coincided with stepwise increases in the non-thermal ECE signal were observed in the EAST (Experimental Advanced Superconducting Tokamak) runaway discharge. Runaway electrons were located around the q = 2 rational magnetic surface (ring-like runaway electron beam). During the EAST runaway discharge, stepwise ECE signal increases coincided with enhanced magnetohydrodynamic (MHD) activity. This behavior was peculiar to this shot. In this paper, we show that these non-thermal ECE step-like jumps were related to the abrupt growth of suprathermal electrons induced by bursting electric fields at reconnection events during this MHD plasma activity. Enhancement of the secondary runaway electron generation also occurred simultaneously. Local changes in the current-density gradient appeared because of local enhancement of the runaway electron generation process. These current-density gradient changes are considered to be a possible trigger for enhancement of the MHD plasma activity and the rapid changes in runaway beam behavior

  10. Controlled generation of comb-like electron beams in plasma channels for polychromatic inverse Thomson γ-ray sources

    Science.gov (United States)

    Kalmykov, S. Y.; Davoine, X.; Ghebregziabher, I.; Lehe, R.; Lifschitz, A. F.; Shadwick, B. A.

    2016-03-01

    Propagating a relativistically intense, negatively chirped laser pulse (the bandwidth  >150 nm) in a plasma channel makes it possible to generate background-free, comb-like electron beams—sequences of synchronized bunches with a low phase-space volume and controlled energy spacing. The tail of the pulse, confined in the accelerator cavity (an electron density ‘bubble’), experiences periodic focusing, while the head, which is the most intense portion of the pulse, steadily self-guides. Oscillations of the cavity size cause periodic injection of electrons from the ambient plasma, creating an electron energy comb with the number of components, their mean energy, and energy spacing dependent on the channel radius and pulse length. These customizable electron beams enable the design of a tunable, all-optical source of pulsed, polychromatic γ-rays using the mechanism of inverse Thomson scattering, with up to  ˜10-5 conversion efficiency from the drive pulse in the electron accelerator to the γ-ray beam. Such a source may radiate  ˜107 quasi-monochromatic photons per shot into a microsteradian-scale cone. The photon energy is distributed among several distinct bands, each having sub-30% energy spread, with a highest energy of 12.5 MeV.

  11. High-frequency oscillations of an electron beam generated by a ferroelectric cathode with anomalous plasma resistance caused by ion-acoustic instability

    International Nuclear Information System (INIS)

    Spectroscopic measurements are reported of the plasma formed inside a cathode having a ferroelectric source incorporated in it. The measurements were performed during generation of a high-frequency modulated electron beam in a planar diode with the above cathode. A qualitative model is suggested, which is based on fast periodic appearance of anomalous plasma resistance. The latter is supposed to be due to generation of ion-acoustic instability

  12. On the generation of cnoidal waves in ion beam-dusty plasma containing superthermal electrons and ions

    Science.gov (United States)

    El-Bedwehy, N. A.

    2016-07-01

    The reductive perturbation technique is used for investigating an ion beam-dusty plasma system consisting of two opposite polarity dusty grains, and superthermal electrons and ions in addition to ion beam. A two-dimensional Kadomtsev-Petviashvili equation is derived. The solution of this equation, employing Painlevé analysis, leads to cnoidal waves. The dependence of the structural features of these waves on the physical plasma parameters is investigated.

  13. Neutrino beam plasma instability

    Indian Academy of Sciences (India)

    Vishnu M Bannur

    2001-10-01

    We derive relativistic fluid set of equations for neutrinos and electrons from relativistic Vlasov equations with Fermi weak interaction force. Using these fluid equations, we obtain a dispersion relation describing neutrino beam plasma instability, which is little different from normal dispersion relation of streaming instability. It contains new, nonelectromagnetic, neutrino-plasma (or electroweak) stable and unstable modes also. The growth of the instability is weak for the highly relativistic neutrino flux, but becomes stronger for weakly relativistic neutrino flux in the case of parameters appropriate to the early universe and supernova explosions. However, this mode is dominant only for the beam velocity greater than 0.25 and in the other limit electroweak unstable mode takes over.

  14. Experimental three-dimensional beam profiling and modeling of a terahertz beam generated from a two-color air plasma

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Strikwerda, Andrew; Iwaszczuk, Krzysztof;

    2013-01-01

    shift in the focal region, and the transition from the donut profile to a central peak is consistent with propagation of a Bessel–Gauss beam, as shown by simulations based on a recent transient photocurrent model (You et al 2012 Phys. Rev. Lett. 109 183902). We combine our measurements to the first full...

  15. Simulation of beam-induced plasma for the mitigation of beam-beam effects

    Energy Technology Data Exchange (ETDEWEB)

    Ma, J.; Wang, G.; Samulyak, R.; Yu, K.; Litvinenko, V.

    2015-05-03

    One of the main challenges in the increase of luminosity of circular colliders is the control of the beam-beam effect. In the process of exploring beam-beam mitigation methods using plasma, we evaluated the possibility of plasma generation via ionization of neutral gas by proton beams, and performed highly resolved simulations of the beam-plasma interaction using SPACE, a 3D electromagnetic particle-in-cell code. The process of plasma generation is modelled using experimentally measured cross-section coefficients and a plasma recombination model that takes into account the presence of neutral gas and beam-induced electromagnetic fields. Numerically simulated plasma oscillations are consistent with theoretical analysis. In the beam-plasma interaction process, high-density neutral gas reduces the mean free path of plasma electrons and their acceleration. A numerical model for the drift speed as a limit of plasma electron velocity was developed. Simulations demonstrate a significant reduction of the beam electric field in the presence of plasma. Preliminary simulations using fully-ionized plasma have also been performed and compared with the case of beam-induced plasma.

  16. Multimodular nitrogen laser for diagnostics of a plasma formed using relativistic electron beam generators

    International Nuclear Information System (INIS)

    A four-frame system for laser diagnostics of a plasma was developed and constructed. The active medium in this system was molecular nitrogen. The system was used to study explosions of thin tungsten wires in the Triton accelerator system

  17. Imaging of Plasmas using Proton Beams Generated by Ultra-Intense Laser Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Borghesi, M,; Campbell, D.H.; Clarke, R.J.; Galimberti, M.; Gizzi, L.A.; Haines, M.G.; Mackinnon, A.J.; Schiavi, A.; Willi, O.

    2002-01-15

    Proton imaging is a diagnostic with enormous potential for the investigation of fundamental plasma physics problems which were impossible to explore up to now. By using this diagnostic, for the first time the measurement of transient electric fields in dense plasmas has been obtained, determining their evolution on a picosecond scale with micrometric spatial resolution. The data is of great relevance to Inertial Confinement Fusion both in the conventional and Fast Ignitor approach. Detailed analysis and modeling is presently undergoing.

  18. Efficient quasi-monoenergetic ion beams up to 18 MeV/nucleon via self-generated plasma fields in relativistic laser plasmas

    CERN Document Server

    Palaniyappan, Sasi; Gautier, Donald C; Hamilton, Christopher E; Santiago, Miguel A; Kreuzer, Christian; Shah, Rahul C; Fernandez, Juan C

    2015-01-01

    Table-top laser-plasma ion accelerators seldom achieve narrow energy spreads, and never without serious compromises in efficiency, particle yield, etc. Using massive computer simulations, we identify a self-organizing scheme that exploits persisting self-generated plasma electric (~TV/m) and magnetic (~10${}^{4}$ Tesla) fields to reduce the ion energy spread after the laser exits the plasma - separating the ion acceleration from the energy spread reduction. Consistent with the scheme, we experimentally demonstrate aluminum and carbon ion beams with narrow spectral peaks at energies up to 310 MeV (11.5 MeV/nucleon) and 220 MeV (18.3 MeV/nucleon), respectively, with high conversion efficiency (~5%, i.e., 4J out of 80J laser). This is achieved with 0.12 PW high-contrast Gaussian laser pulses irradiating planar foils with optimal thicknesses of up to 250 nm that scale with laser intensity. When increasing the focused laser intensity fourfold (by reducing the focusing optic f/number twofold), the spectral-peak ene...

  19. Generation of intense pulsed ion beam by a Br type magnetically insulated ion diode with carbon plasma gun

    International Nuclear Information System (INIS)

    To apply the pulsed heavy ion beam (PHIB) to an implantation process of semiconductor, purity of the ion beam is very important. To obtain a pure PHIB we have proposed a new type of accelerator using bipolar pulse. To develop the accelerator we are developing a new type of Br ion diode using a carbon plasma gun. By using the plasma gun, ion source plasma of ion current density approx. = 30 A/cm2 was obtained. The Br ion diode was successfully operated with plasma gun at diode voltage approx. = 100 kV, diode current approx. = 1 kA, pulse duration approx. = 200 ns and 3 A/cm2 of ion current density was obtained. (author)

  20. Pre-plasma effect on energy transfer from laser beam to shock wave generated in solid target

    Czech Academy of Sciences Publication Activity Database

    Pisarczyk, T.; Gus’kov, S.Yu.; Kalinowska, Z.; Badziak, J.; Batani, D.; Antonelli, L.; Folpini, G.; Maheut, Y.; Baffigi, F.; Borodziuk, S.; Chodukowski, T.; Cristoforetti, G.; Demchenko, N. N.; Gizzi, L.A.; Kasperczuk, A.; Koester, P.; Krouský, Eduard; Labate, L.; Parys, P.; Pfeifer, Miroslav; Renner, Oldřich; Šmíd, Michal; Rosinski, M.; Skála, Jiří; Dudžák, Roman; Ullschmied, Jiří; Pisarczyk, P.

    2014-01-01

    Roč. 21, č. 1 (2014), 012708/1-012708/7. ISSN 1070-664X R&D Projects: GA MŠk LM2010014; GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 Institutional support: RVO:61389021 ; RVO:68378271 Keywords : Energy transfer * laser ablation * shock waves * plasma waves * laser beam effects Subject RIV: BL - Plasma and Gas Discharge Physics; BL - Plasma and Gas Discharge Physics (FZU-D) Impact factor: 2.142, year: 2014 http://scitation.aip.org/content/aip/journal/pop/21/1/10.1063/1.4862784

  1. Non-ambipolar radio-frequency plasma electron source and systems and methods for generating electron beams

    Science.gov (United States)

    Hershkowitz, Noah; Longmier, Benjamin; Baalrud, Scott

    2009-03-03

    An electron generating device extracts electrons, through an electron sheath, from plasma produced using RF fields. The electron sheath is located near a grounded ring at one end of a negatively biased conducting surface, which is normally a cylinder. Extracted electrons pass through the grounded ring in the presence of a steady state axial magnetic field. Sufficiently large magnetic fields and/or RF power into the plasma allow for helicon plasma generation. The ion loss area is sufficiently large compared to the electron loss area to allow for total non-ambipolar extraction of all electrons leaving the plasma. Voids in the negatively-biased conducting surface allow the time-varying magnetic fields provided by the antenna to inductively couple to the plasma within the conducting surface. The conducting surface acts as a Faraday shield, which reduces any time-varying electric fields from entering the conductive surface, i.e. blocks capacitive coupling between the antenna and the plasma.

  2. Decomposition of gas-phase diphenylether at 473 K by electron beam generated plasma

    CERN Document Server

    Kim, H H; Kojima, T

    2003-01-01

    Decomposition of gas-phase diphenylether (DPE) in the order of several parts per million by volume (ppmv) was studied as a model compound of dioxin using a flow-type electron-beam reactor at an elevated temperature of 473 K. The ground state oxygen ( sup 3 P) atoms played an important role in the decomposition of DPE resulting in the formation of 1,4-hydroquinone (HQ) as a major ring retaining product. The high yield of hydroquinone indicated that the breakage of ether bond (C-O) is important in the initial step of DPE decomposition. Ring cleavage products were CO and CO sub 2 , and NO sub 2 was also produced from background N sub 2 -O sub 2. The sum of the yields of HQ, CO sub 2 and CO accounts for over 90% of the removed DPE. Hydroxyl radicals (OH) were less important in the dilute DPE decomposition at a high water content, and were mostly consumed by recombination reactions to form hydrogen peroxide. The smaller the initial DPE concentrations, the higher the decomposition efficiency and the lower the yield...

  3. Generation of Superponderomotive Electrons in Multipicosecond Interactions of Kilojoule Laser Beams with Solid-Density Plasmas

    Science.gov (United States)

    Sorokovikova, A.; Arefiev, A. V.; McGuffey, C.; Qiao, B.; Robinson, A. P. L.; Wei, M. S.; McLean, H. S.; Beg, F. N.

    2016-04-01

    The interaction of a multipicosecond, kilojoule laser pulse with a surface of a solid target has been shown to produce electrons with energies far beyond the free-electron ponderomotive limit mec2a02/2 . Particle-in-cell simulations indicate that an increase in the pulse duration from 1 to 10 ps leads to the formation of a low-density shelf (about 10% of the critical density). The shelf extends over 100 μ m toward the vacuum side, with a nonstationary potential barrier forming in that area. Electrons reflected from the barrier gain superponderomotive energy from the potential. Some electrons experience an even greater energy gain due to ponderomotive acceleration when their "dephasing rate" R =γ -px/mec drops well below unity, thus increasing acceleration by a factor of 1 /R . Both 1D and 2D simulations indicate that these mechanisms are responsible for the generation of extensive thermal distributions with Te>10 MeV and a high-energy cutoff of hundreds of MeV.

  4. Light Beam Generation

    DEFF Research Database (Denmark)

    2007-01-01

    The invention relates to a method and a system for synthesizing a set of controllable light beams by provision of a system for synthesizing a set of light beams, comprising a spatially modulated light source for generation of electromagnetic radiation with a set of replicas of a predetermined...... symbol, s, positioned at respective desired positions (xs, ys) in an object plane o(x, y) intersecting, preferably perpendicular to, the direction of propagation of the electromagnetic radiation, and having spatial amplitudes a(x-xs, y-ys), spatial phases f(x-xs, y-ys)> and spatial polarisation vectors p(x...... transforming lens for Inverse Fourier transforming the spatially modulated radiation, whereby a set of light beams are formed propagating through the inverse Fourier plane (x', y') at desired positions (x's, y's), and a controller for controlling the position of a replica of the symbol, s, for movement...

  5. Regimes of enhanced electromagnetic emission in beam-plasma interactions

    International Nuclear Information System (INIS)

    The ways to improve the efficiency of electromagnetic waves generation in laboratory experiments with high-current relativistic electron beams injected into a magnetized plasma are discussed. It is known that such a beam can lose, in a plasma, a significant part of its energy by exciting a high level of turbulence and heating plasma electrons. Beam-excited plasma oscillations may simultaneously participate in nonlinear processes resulting in a fundamental and second harmonic emissions. It is obvious, however, that in the developed plasma turbulence the role of these emissions in the total energy balance is always negligible. In this paper, we investigate whether electromagnetic radiation generated in the beam-plasma system can be sufficiently enhanced by the direct linear conversion of resonant beam-driven modes into electromagnetic ones on preformed regular inhomogeneities of plasma density. Due to the high power of relativistic electron beams, the mechanism discussed may become the basis for the generator of powerful sub-terahertz radiation

  6. Regimes of enhanced electromagnetic emission in beam-plasma interactions

    Energy Technology Data Exchange (ETDEWEB)

    Timofeev, I. V.; Annenkov, V. V.; Arzhannikov, A. V. [Budker Institute of Nuclear Physics, SB RAS, 630090 Novosibirsk, Russia and Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2015-11-15

    The ways to improve the efficiency of electromagnetic waves generation in laboratory experiments with high-current relativistic electron beams injected into a magnetized plasma are discussed. It is known that such a beam can lose, in a plasma, a significant part of its energy by exciting a high level of turbulence and heating plasma electrons. Beam-excited plasma oscillations may simultaneously participate in nonlinear processes resulting in a fundamental and second harmonic emissions. It is obvious, however, that in the developed plasma turbulence the role of these emissions in the total energy balance is always negligible. In this paper, we investigate whether electromagnetic radiation generated in the beam-plasma system can be sufficiently enhanced by the direct linear conversion of resonant beam-driven modes into electromagnetic ones on preformed regular inhomogeneities of plasma density. Due to the high power of relativistic electron beams, the mechanism discussed may become the basis for the generator of powerful sub-terahertz radiation.

  7. Enhancement of conversion efficiency and spatial coherence of high order harmonics generated from pre-formed plasma plumes using an apertured laser beam

    Science.gov (United States)

    Kumar, M.; Chakravarty, U.; Rathore, R.; Chakera, J. A.; Naik, P. A.; Gupta, P. D.

    2016-04-01

    The effect of laser beam aperturing (Ti: sapphire laser; 800 nm, 45 fs) on the conversion efficiency (CE), harmonic yield and spatial coherence of high order harmonics generated from a low excited plasma plume of carbon (neutral and singly charged ions) is studied. The optimization of CE by varying the aperture size in combination with different laser and plasma plume parameters was carried out. The CE of the 15th harmonic is enhanced from ˜10-7 for an unapertured laser beam to ˜10-6 for ˜¼ times the unapertured beam diameter, at same laser energy in both cases. Further, it was found that, at a given aperture size, there is an optimum prepulse intensity for maximum CE. The results are explained by taking into account the theoretical consideration of phase matching issues in plasma plumes. The study shows that tuning the prepulse intensity and aperture size gives an easy handle to increase the harmonic conversion along with its coherence properties. The study will be useful for producing an intense source of harmonics with high spatial coherence from plasmas plumes for applications.

  8. The effect of plasma inhomogeneities on (i) radio emission generation by non-gyrotropic electron beams and (ii) particle acceleration by Langmuir waves

    Science.gov (United States)

    Tsiklauri, David

    2015-04-01

    Extensive particle-in-cell simulations of fast electron beams injected in a background magnetised plasma with a decreasing density profile were carried out. These simulations were intended to further shed light on a newly proposed mechanism for the generation of electromagnetic waves in type III solar radio bursts [1]. Here recent progress in an alternative to the plasma emission model using Particle-In-Cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts will be presented. In particular, (i) Fourier space drift (refraction) of non-gyrotropic electron beam-generated wave packets, caused by the density gradient [1,2], (ii) parameter space investigation of numerical runs [3], (iii) concurrent generation of whistler waves [4] and a separate problem of (iv) electron acceleration by Langmuir waves in a background magnetised plasma with an increasing density profile [5] will be discussed. In all considered cases the density inhomogeneity-induced wave refraction plays a crucial role. In the case of non-gyrotropic electron beam, the wave refraction transforms the generated wave packets from standing into freely escaping EM radiation. In the case of electron acceleration by Langmuir waves, a positive density gradient in the direction of wave propagation causes a decrease in the wavenumber, and hence a higher phase velocity vph = ω/k. The k-shifted wave is then subject to absorption by a faster electron by wave-particle interaction. The overall effect is an increased number of high energy electrons in the energy spectrum. [1] D. Tsiklauri, Phys. Plasmas 18, 052903 (2011); http://dx.doi.org/10.1063/1.3590928 [2] H. Schmitz, D. Tsiklauri, Phys. Plasmas 20, 062903 (2013); http://dx.doi.org/10.1063/1.4812453 [3] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 19, 112903 (2012); http://dx.doi.org/10.1063/1.4768429 [4] M. Skender, D. Tsiklauri, Phys. Plasmas 21, 042904 (2014); http://dx.doi.org/10.1063/1.4871723 [5] R. Pechhacker, D. Tsiklauri

  9. Experimental studies on beam-plasma interaction

    International Nuclear Information System (INIS)

    Beam-handling technology has reached now at such a level as to enable highly controlled experiments of beam-plasma interaction. Varieties of hypotheses and suppositions about the beam propagation and interaction in space plasma can be proved and often be corrected by examining the specific processes in laboratory plasma. The experiments performed in this way by the author are briefed: ion beam instability in unmagnetized plasma; ion beam instability perpendicular to magnetic field; and electron beam instability. (Mori, K.)

  10. Ultra-low emittance beam generation using two-color ionization injection in a CO2 laser-driven plasma accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Carl [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Benedetti, Carlo [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bulanov, Stepan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chen, Min [Shanghai Jiao Tong Univ. (China); Esarey, Eric [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Geddes, Cameron [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Vay, J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yu, Lule [Shanghai Jiao Tong Univ. (China); Leemans, Wim [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-05-21

    Ultra-low emittance (tens of nm) beams can be generated in a plasma accelerator using ionization injection of electrons into a wakefield. An all-optical method of beam generation uses two laser pulses of different colors. A long-wavelength drive laser pulse (with a large ponderomotive force and small peak electric field) is used to excite a large wakefield without fully ionizing a gas, and a short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the pump laser, to ionize a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wake. The trapping condition, the ionized electron distribution, and the trapped bunch dynamics are discussed. Expressions for the beam transverse emittance, parallel and orthogonal to the ionization laser polarization, are presented. An example is shown using a 10-micron CO2 laser to drive the wake and a frequency-doubled Ti:Al2O3 laser for ionization injection.

  11. Ultra-low emittance beam generation using two-color ionization injection in a CO2 laser-driven plasma accelerator

    International Nuclear Information System (INIS)

    Ultra-low emittance (tens of nm) beams can be generated in a plasma accelerator using ionization injection of electrons into a wakefield. An all-optical method of beam generation uses two laser pulses of different colors. A long-wavelength drive laser pulse (with a large ponderomotive force and small peak electric field) is used to excite a large wakefield without fully ionizing a gas, and a short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the pump laser, to ionize a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wake. The trapping condition, the ionized electron distribution, and the trapped bunch dynamics are discussed. Expressions for the beam transverse emittance, parallel and orthogonal to the ionization laser polarization, are presented. An example is shown using a 10-micron CO2 laser to drive the wake and a frequency-doubled Ti:Al2O3 laser for ionization injection.

  12. Ultra-low emittance beam generation using two-color ionization injection in a CO2 laser-driven plasma accelerator

    CERN Document Server

    Schroeder, C B; Bulanov, S S; Chen, M; Esarey, E; Geddes, C G R; Vay, J -L; Yu, L -L; Leemans, W P

    2015-01-01

    Ultra-low emittance (tens of nm) beams can be generated in a plasma accelerator using ionization injection of electrons into a wakefield. An all-optical method of beam generation uses two laser pulses of different colors. A long-wavelength drive laser pulse (with a large ponderomotive force and small peak electric field) is used to excite a large wakefield without fully ionizing a gas, and a short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the pump laser, to ionize a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wake. The trapping condition, the ionized electron distribution, and the trapped bunch dynamics are discussed. Expressions for the beam transverse emittance, parallel and orthogonal to the ionization laser polarization, are presented. An example is shown using a 10-micron CO2 laser to drive the wake and a frequency-doubled Ti:Al2...

  13. Ion Beam Plasma Interactions in the ASTRAL Helicon Plasma Source.

    Science.gov (United States)

    Boivin, R. F.; Kesterson, A.; Kamar, O.; Lin, Y.; Munoz, J.; Wang, X.

    2008-11-01

    A 100 KeV NEC duoplasmatron is used to produce an energetic ion beam (10 KeV ASTRAL helicon plasma source. The beam current and beam size are measured by a device combining Retarding Field Analyzer (RFA) and Faraday Cup (FC) features. ASTRAL produces bright intense He/Ne/Ar plasmas with the following parameters: ne = 1E11 -- 1E13 cm-3 and Te = 2 - 10 eV, B-field < 1.3 kGauss, rf power <= 2 kWatt. RF compensated Langmuir probes are used to measure Te and ne. Depending on the ion beam energy and the ratio of beam density over plasma density different wave instabilities will be generated within the plasmas. A real-time spectrum analyzer will be used to identify the wave instabilities and their evolution in the plasma. We will present early experimental results together with some preliminary theoretical simulation using 2D and 3D hybrid simulation codes. In these codes, ions are treated as fully kinetic particles while electrons are treated as a fluid. Both species are moving in a self-consistent electromagnetic field.

  14. Generation and study of relativistic electron beam

    International Nuclear Information System (INIS)

    Pulsed Electron Beam (REB) technology has progressed rapidly in recent years because of applications in various fields like radiation sources, high power laser development, plasma heating and fusion research. The REB development programme at the Plasma Physics Section of Bhabha Atomic Research Centre, Bombay, has been described. The design features of the 375 KV, 3500 A, 75 Joule REB generator are discussed. The diagnostic equipment developed for the studies is described. The present experimental studies and some preliminary results on beam characterisation are presented. (author)

  15. Laser beam plasma pinch x-ray system

    International Nuclear Information System (INIS)

    A system is provided for producing plasma pinch X-rays usable in X-ray lithography. Ionized heated plasma vapor is repeatably generated directly from solid material by impingement of a plurality of circumferentially spaced laser beams to generate an annulus of plasma. X-rays are generated by passing high current through the annular plasma in an axial gap between the solid material target electrode and another electrode, causing magnetic field radial inward plasma pinching to a central constricted area further heating the plasma and emitting X-rays. A central axially directed laser may further heat the plasma in the pinched area

  16. Evolution of the THz Beam Profile from a Two-Color Air Plasma Through a Beam Waist

    DEFF Research Database (Denmark)

    Strikwerda, Andrew; Pedersen, Pernille Klarskov; Jepsen, Peter Uhd

    2013-01-01

    We experimentally measure the profile of a THz beam generated by a two-color air plasma as it passes through a beam waist, and show that it can be approximated as a Bessel-Gauss beam.......We experimentally measure the profile of a THz beam generated by a two-color air plasma as it passes through a beam waist, and show that it can be approximated as a Bessel-Gauss beam....

  17. Generation of High Brightness Electron Beams via Ionization Induced Injection by Transverse Colliding Lasers in a Beam-Driven Plasma Wakefield Accelerator

    CERN Document Server

    Li, F; Xu, X L; Zhang, C J; Yan, L X; Du, Y C; Huang, W H; Cheng, H B; Tang, C X; Lu, W; Joshi, C; Mori, W B; Gu, Y Q

    2013-01-01

    The production of ultra-bright electron bunches using ionization injection triggered by two transversely colliding laser pulses inside a beam-driven plasma wake is examined via three-dimensional (3D) particle-in-cell (PIC) simulations. The relatively low intensity lasers are polarized along the wake axis and overlap with the wake for a very short time. The result is that the residual momentum of the ionized electrons in the transverse plane of the wake is much reduced and the injection is localized along the propagation axis of the wake. This minimizes both the initial 'thermal' emittance and the emittance growth due to transverse phase mixing. 3D PIC simulations show that ultra-short (around 8 fs) high-current (0.4 kA) electron bunches with a normalized emittance of 8.5 and 6 nm in the two planes respectively and a brightness greater than 1.7*10e19 A rad-2 m-2 can be obtained for realistic parameters.

  18. Pulsed electron beams in transient plasmas

    International Nuclear Information System (INIS)

    In the present work a large variety of experimental investigation is reviewed, having in common pulsed electron beams in transient plasmas. The simulation of nuclear pumping of plasma recombination lasers using pulsed electron beams led to the optimization of a coaxial discharge geometry which allowed lasing at the 585.3 nm transition in Ne I, Ne-H2 mixtures. In a detailed investigation of the cathode sheaths by superposition of two discharges, a simple and accurate method to measure the sheath width has been worked out and a new way of pulsed electron beam generation has been discovered. The electron beam (280 A peak current, 10 ns pulse duration, diameter less than 100 μm over a few centimeters length) is produced in a pseudospark-like discharge without inner diaphragms by the synergy of two discharges. Its parameters can be efficiently controlled by the preionization discharge. The exceptional radial stability of this beam along the discharge tube access opens the possibility to use the device as a pulsed high-density ion trap. The extension of this research helped to discover and to explain the (Cruise) effect, namely the capture and guiding of the electron beam by dielectric fibres. (author) 10 figs., 64 refs

  19. Plasma Heating and Burnout in Beam-Plasma Interaction

    International Nuclear Information System (INIS)

    Experiments using beam-plasma interaction to generate fully ionized plasma and enhance the temperature of the components are in progress at Oak Ridge National Laboratory. Previous experimental work demonstrated that an electron beam of 5 keV could heat plasma electrons in a magnetic mirror machine to a temperature over 100 keV. In this extension of the earlier work the electron beam is directed through higher pressure gas. Such a dense cloud of electrons is produced that neutral gas streaming inward from the walls is almost completely ionized or burned out before reaching the center of the apparatus. The most spectacular feature of the burnout transition is the sudden decrease of spectral light by a factor about 1000. Several neutral beam transmission experiments give electron densities greater than 1012 cm-3. Microwave cut-off measurements agree with this lower limit. Direct measurements of the electron plasma frequency and the ion plasma frequency give a density of 5 x 1012 cm-3. Once the neutral gas in the plasma is ionized, the electron cooling by excitation processes and the ion cooling by charge-exchange phenomena disappear; therefore, any electron and ion heating caused by the electron beam should have time to take effect. Pin-hole camera images formed by 50-keV X-rays give evidence of electron heating. Ion heating is limited by wall proximity to 20-keV deuterons in the Burnout IV device and 200-keV deuterons in the larger Burnout V device. Magnetic and electrostatic analysis give evidence for the existence of some deuterons at 20 keV in Burnout IV; similar analysis is in progress on Burnout V. In Burnout V the electron beam traverses the central 300 cm3 of the 10-liter volume between the mirrors of a 40-20-40-kG mirror machine. Injection and multiple reflection of the 45-kW electron beam occur outside the mirrors in a region of 10-5 Torr ambient pressure. The lifetime of the plasma is difficult both to measure and to predict on theoretical grounds. The

  20. 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. PMID:23426323

  1. Underdense plasma lenses for focusing particle beams

    International Nuclear Information System (INIS)

    Plasma lenses are of interest for providing ultra-strong focusing of particle beams in order to enhance the luminosity of a high-energy linear collider. Previous work has explored the selfpinch of e+ or e- beams as they pass through an overdense slab of passive plasma (i.e., plasma density much greater than the beam density). Here the authors examine the focusing of beams in an underdense plasma through physical and particle simulation models. In this regime the plasma dynamics becomes highly non-linear and differs for e+ and e- beams. For e- beams the plasma electrons are almost completely expelled by the beam's space charge leaving a uniform column of ion charge that provides the focusing force. Compared to the overdense lens, the underdense lens has the advantages that spherical aberrations, longitudinal aberrations, and plasma contribution to background in the detectors are all greatly reduced. 10 refs., 4 figs., 1 tab

  2. Extreme hydrogen plasma densities achieved in a linear plasma generator

    International Nuclear Information System (INIS)

    A magnetized hydrogen plasma beam was generated with a cascaded arc, expanding in a vacuum vessel at an axial magnetic field of up to 1.6 T. Its characteristics were measured at a distance of 4 cm from the nozzle: up to a 2 cm beam diameter, 7.5x1020 m-3 electron density, ∼2 eV electron and ion temperatures, and 3.5 km/s axial plasma velocity. This gives a 2.6x1024 H+ m-2 s-1 peak ion flux density, which is unprecedented in linear plasma generators. The high efficiency of the source is obtained by the combined action of the magnetic field and an optimized nozzle geometry. This is interpreted as a cross-field return current that leads to power dissipation in the beam just outside the source

  3. Theory for beam-plasma millimeter-wave radiation source experiments

    International Nuclear Information System (INIS)

    This paper reports on theoretical studies for millimeter-wave plasma source experiments. In the device, millimeter-wave radiation is generated in a plasma-filled waveguide driven by counter-streaming electron beams. The beams excite electron plasma waves which couple to produce radiation at twice the plasma frequency. Physics topics relevant to the high electron beam current regime are discussed

  4. Plasma/Neutral-Beam Etching Apparatus

    Science.gov (United States)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  5. On plasma ion beam formation in the Advanced Plasma Source

    International Nuclear Information System (INIS)

    The Advanced Plasma Source (APS) is employed for plasma ion-assisted deposition (PIAD) of optical coatings. The APS is a hot cathode dc glow discharge which emits a plasma ion beam to the deposition chamber at high vacuum (p ≲ 2 × 10−4 mbar). It is established as an industrial tool but to date no detailed information is available on plasma parameters in the process chamber. As a consequence, the details of the generation of the plasma ion beam and the reasons for variations of the properties of the deposited films are barely understood. In this paper the results obtained from Langmuir probe and retarding field energy analyzer diagnostics operated in the plasma plume of the APS are presented, where the source was operated with argon. With increasing distance to the source exit the electron density (ne) is found to drop by two orders of magnitude and the effective electron temperature (Te,eff) drops by a factor of five. The parameters close to the source region read ne ≳ 1011 cm−3 and Te,eff ≳ 10 eV. The electron distribution function exhibits a concave shape and can be described in the framework of the non-local approximation. It is revealed that an energetic ion population leaves the source region and a cold ion population in the plume is build up by charge exchange collisions with the background neutral gas. Based on the experimental data a scaling law for ion beam power is deduced, which links the control parameters of the source to the plasma parameters in the process chamber. (paper)

  6. Generation of particle beams and X-ray pulses in ultra-relativistic laser-plasma interactions

    Energy Technology Data Exchange (ETDEWEB)

    Pukhov, A.; Gordienko, S.; Baeva, T.; Kiselev, S.; Shorokhov, O.; Kostyukov, I.

    2005-07-01

    A similarity theory is developed for ultra-relativistic laser-plasma interactions. It is shown that the laser-plasma dynamics is similar if the dimensionless number S ne/a0nc is kept constant, where a0 = eA0/mc2 is the initial laser amplitude, ne ia the electron density, nc = ?2 0 m/4 ?e2 is the critical plasma density for the laser pulse with the carrier frequency ?0. The S?number reflects the fundamental symmetry of the laser-plasma dynamics described by the Vlasov Eq. and the Maxwell Eqs. in the ultrarelativistic regime a0 ? 1. The similarity theory allows us to derive simple scalings for the energy and the number of laser-accelerated electrons as well as for the density of the electron bunch. We are particularly interested in the so-called Bubble acceleration [1, 2]. The S?similarity is valid both for under- and overdense plasmas. In the case of overdense plasmas the S?similarity leads to the scalability of high harmonics from sharp plasma surfaces. We show that the high harmonics are phase-locked and coherent. They appear in the form of (sub-)atto second pulses of X-rays [3]. Employing concave plasma surfaces one can focus these harmonics. The coherent harmonic focusing opens a new way to the extremely high intensities reaching the vacuum breakdown limit at 1029 W/cm2. The ion acceleration in laser-plasma interactions has its own similarity group that is also discussed in the present work. (Author)

  7. Plasma beam discharge in carbon dioxide

    International Nuclear Information System (INIS)

    The paper deals with the dissociation of carbon dioxide in nonequilibrium plasma of a stationary plasma-beam discharge. Experimental results of spectroscopic and probe measurements of plasma parameters are given. Moreover, a mass-spectrometric analysis of gaseous products of the chemical reactions is presented. In addition the measurement of the deposition rate of solid products by means of a quartz oscillator is described. The results show that plasma beam discharge is an effective tool for inducing plasma-chemical reactions. (author)

  8. Plasma lens experiments at the Final Focus Test Beam

    Energy Technology Data Exchange (ETDEWEB)

    Barletta, B. [California Univ., Los Angeles, CA (United States)]|[Lawrence Berkeley Lab., CA (United States); Chattopadhyay, S. [Lawrence Berkeley Lab., CA (United States); Chen, P. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)] [and others

    1993-04-01

    We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. We will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam ionization of a working gas. At an increased bunch population of 2.5 {times} 10{sup 10}, tunneling ionization of a gas target by an electron beam -- an effect which has never been observed before -- should be significant. The compactness of our device should prove to be of interest for applications at the SLC and the next generation linear colliders.

  9. Shunting arc plasma source for pure carbon ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y. [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2012-02-15

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

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

    Science.gov (United States)

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

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse. PMID:22380206

  11. EUV Generation by High Density Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Y. S.; Lee, H. S.; Kim, K. H.; Seo, K. S.; Rhim, K. H. [Korea Electrotechnology Research Institute (Korea)

    2000-07-01

    As a next generation lithography (NGL) technology for VLSI semiconductor fabrication, electron beam, ion beam, X-ray and extreme ultraviolet(EUV) are considered as possible candidates. Among these methods, EUV lithography(EUVL) is thought to be the most probable because it is easily realized by improving current optical lithography technology. In order to get EUV radiation which can be applied to EUVL, it is essential to generate very high density and high temperature plasma stably. The method using a pulse power laser and a high voltage pulse discharge is commonly used to accomplish such a high density and high temperature plasma. In this paper, we review the recent trends of the EUV generation technique by high density and high temperature plasma. (author). 6 refs., 4 figs.

  12. Electron acceleration experiment using a plasma wave generated by two beating laser pulses. Study of the 3 MeV electron beam monitor using optical transition radiation and magnetic spectrograph

    International Nuclear Information System (INIS)

    This thesis presents my contributions to the electron acceleration experiment using a plasma wave generated by two beating laser pulses at Ecole Polytechnique, Palaiseau, France. The first chapter describes the principle of particle acceleration by laser generated plasma waves. In order to estimate the energy gain, I examine the influence of the plasma wave's longitudinal profile and I obtain a gain of about 1 MeV over an acceleration length of 3 mm. In the second chapter, I present the beam monitor for the injected 3 MeV electron beam. This beam monitor uses optical transition radiation and has a spatial resolution of 10 μm. It is used to align of the laser beam and the electron beam and thus to control the injection of the electrons into the plasma. The third chapter describes the design of the magnetic spectrograph used to analyze the energy spectrum of the accelerated electrons. The study of the class of stigmatic dipole magnets leads to the selection of a quadrupole-dipole combination. This spectrograph is stigmatic at injection energy (3 MeV) and has a large energy range as well as a high angular acceptance. (author)

  13. Plasma heating by a relativistic electron beam

    International Nuclear Information System (INIS)

    This thesis is devoted to the interaction of a Relativistic Electron Beam (REB) with a plasma. The goal of the experiment described herein is to study in detail the mechanism of energy transfer from the beam to the plasma. The beam particles have an energy of 800 keV, a current of 6 kA, a diameter of 3 cm and an adjustable pulse length of 50-150 ns. This beam is injected into cold hydrogen and helium plasmas with densities ranging from 1018 to 1020 m-3. First, the technical aspects of the experiment are described. Then measurements on the hf fields excited by the REB-plasma are presented (optical line profiles and spectra of beam electrons). The final section is devoted to plasma heating. (Auth.)

  14. Theoretical and Experimental Beam Plasma Physics (TEBPP)

    Science.gov (United States)

    Roberts, B.

    1986-01-01

    The theoretical and experimental beam plasma physics (TEBPP) consists of a package of five instruments to measure electric and magnetic fields, plasma density and temperature, neutral density, photometric emissions, and energetic particle spectra during firings of the particle injector (SEPAC) electron beam. The package is developed on a maneuverable boom (or RMS) and is used to measure beam characteristics and induced perturbations field ( 10 m) and mid field ( 10 m to 100 m) along the electron beam. The TEBPP package will be designed to investigate induced oscillations and induced electromagnetic mode waves, neutral and ion density and temperature effects, and beam characteristics as a function of axial distance.

  15. Nonlinear plasma and beam physics in plasma wake-fields

    International Nuclear Information System (INIS)

    In experimental studies of the Plasma Wake-field Accelerator performed to date at the Argonne Advanced Accelerator Test Facility, significant nonlinearities in both plasma and beam behavior have been observed. The plasma waves driven in the wake of the intense driving beam in these experiments exhibit three-dimensional nonlinear behavior which has as yet no quantitative theoretical explanation. This nonlinearity is due in part to the self-pinching of the driving beam in the plasma, as the denser self-focused beam can excite larger amplitude plasma waves. The self-pinching is a process with interesting nonlinear aspects: the initial evolution of the beam envelope and the subsequent approach to Bennett equilibrium through phase mixing. 35 refs., 10 figs

  16. Laser beam-plasma coupling in laser solenoid plasmas

    International Nuclear Information System (INIS)

    A model has been constructed to analyze the gross beam-plasma interaction in a laser solenoid plasma. The model includes a simple solution for a slab plasma response to a given laser beam, and a solution for axial beam size variations in response to arbitrary axial plasma structure. The two solutions are combined to determine the coupled behavior. Trapping of the focused laser beam where it enters the plasma is a significant problem, but can be achieved by a minimum level of imbedded field in the plasma. If the beam is trapped, it first focuses and then defocuses near the front of the bleaching wave (front of the laser heated plasma). In order to avoid divergence of the beam near the front, it is essential to have a pre-formed favorable density profile in the plasma. Such a condition is probably achieved automatically in the early stages of plasma heating. Several techniques are discussed which can be used to avert unfavorable refractive behavior (catastrophic self-focusing and defocusing)

  17. Atmospheric pressure plasma analysis by modulated molecular beam mass spectrometry

    International Nuclear Information System (INIS)

    Fractional number density measurements for a rf plasma 'needle' operating at atmospheric pressure have been obtained using a molecular beam mass spectrometer (MBMS) system designed for diagnostics of atmospheric plasmas. The MBMS system comprises three differentially pumped stages and a mass/energy analyzer and includes an automated beam-to-background measurement facility in the form of a software-controlled chopper mechanism. The automation of the beam modulation allows the neutral components in the plasma to be rapidly and accurately measured using the mass spectrometer by threshold ionization techniques. Data are reported for plasma generated by a needle plasma source operated using a helium/air mixture. In particular, data for the conversion of atmospheric oxygen and nitrogen into nitric oxide are discussed with reference to its significance for medical applications such as disinfecting wounds and dental cavities and for microsurgery

  18. Propagation of realistic beams in underdense plasma

    International Nuclear Information System (INIS)

    The effect of beam structure on propagation through underdense plasma is examined in two different examples. First, it is shown that the distribution of intensities within a laser beam affects how the beam deflects in the presence of transverse plasma flow. A detailed analysis of beam deflection shows that the rate scales linearly with intensity and plasma density, and inversely with plasma temperature. When the plasma flow is subsonic, the deflection rate is proportional to the ion damping decrement, and scales as M/(1 - M2)3/2, where M is the transverse flow Mach number. When the plasma flow is supersonic, the deflection rate scales as 1/[M(M2 - 1)1/2]. Next, the effect of beam structure on channel formation by very intense laser beer is studied. A diffraction-limited beam with 40 TW of input power forms a channel through 4OOpm of plasma, whereas when this beam is phase aberrated, channel formation does not occur

  19. Plasma-Based Ion Beam Sources

    International Nuclear Information System (INIS)

    Ion beam sources cover a broad spectrum of scientific and technical applications delivering ion currents between less than 1 mA and about 100 A at acceleration voltages between 100 V and 100 kV. The ions are mostly generated by electron collisions in a gas discharge and then extracted from the discharge plasma, focused and post-accelerated by single- or multi-aperture electrode systems. Some important applications require the neutralization of the exhausted beam either by charge exchange or by admixture of electrons. In the first part of the paper, the theory of ionization by electron impact, the energy and carrier balances in the plasma, and the extraction and focusing mechanisms will be outlined. The principles of the preferred gas discharges and of the ion beam sources based on them are discussed; i.e. of the Penning, bombardment, arc, duoplasmatron, radio frequency, and microwave types. In the second part of the paper, the special requirements of the different applications are described together with the related source hardware. One distinguishes: 1. Single-aperture ion sources producing protons, heavy ions, isotope ions, etc. for particle accelerators, ion microprobes, mass spectrometers, isotope separators, etc.; quality determinative quantities are brightness, emittance, energy width, etc. 2. Broad-beam multi-aperture injector sources for fusion machines with positive or negative deuterium ions; very high beam densities, small portions of molecular ions, flat beam profiles with small divergence angles, etc. are required. 3. Broad-beam multi-aperture ion thrusters for space propulsion operated with singly charged xenon ions; high efficiencies, reliable operation, and long lifetimes are most important. Spin-offs are applied in industry for material processing. Referring to these applications, the following sources will be described in some detail: 1. Cold cathode and filament driven sources, capillary arc and plasmatron types, microwave and ECR-sources. 2

  20. Surface plasma source with saddle antenna radio frequency plasma generator.

    Science.gov (United States)

    Dudnikov, V; Johnson, R P; Murray, S; Pennisi, T; Piller, C; Santana, M; Stockli, M; Welton, R

    2012-02-01

    A prototype RF H(-) surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA∕kW. Control experiments with H(-) beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing. PMID:22380221

  1. Propagation and beam-plasma interactions of the EDI beam

    International Nuclear Information System (INIS)

    An electron drift instrument (EDI), proposed for the Cluster mission, would measure electric fields, magnetic field gradients, and magnetic field strengths in the magnetospheric plasma. The experiments involve injecting two beams of test electrons into the magnetosphere perpendicular to the ambient magnetic field. Forces due to the ambient electric and magnetic fields return the beams to two dedicated detectors on the spacecraft. For typical magnetospheric electric and magnetic fields and a beam energy of 1 keV, the electron gyroradius is on the order of kilometers, the gyroperiod is milliseconds, and the drift distance in one gyroperiod is a few meters. This paper reports on analyses of electron beam propagation and beam-plasma interaction for the EDI beams. 27 refs

  2. Beam-plasma instability in charged plasma in the absence of ions

    Science.gov (United States)

    Dubinov, Alexander E.; Petrik, Alexey G.; Kurkin, Semen A.; Frolov, Nikita S.; Koronovskii, Alexey A.; Hramov, Alexander E.

    2016-04-01

    We report on the possibility of the beam-plasma instability development in the system with electron beam interacting with the single-component hot electron plasma without ions. As considered system, we analyse the interaction of the low-current relativistic electron beam (REB) with squeezed state in the high-current REB formed in the relativistic magnetically insulated two-section vircator drift space. The numerical analysis is provided by means of 3D electromagnetic simulation in CST Particle Studio. We have conducted an extensive study of characteristic regimes of REB dynamics determined by the beam-plasma instability development in the absence of ions. As a result, the dependencies of instability increment and wavelength on the REB current value have been obtained. The considered process brings the new mechanism of controlled microwave amplification and generation to the device with a virtual cathode. This mechanism is similar to the action of the beam-plasma amplifiers and oscillators.

  3. Whittaker functions in beam driven plasma wakefield acceleration for a plasma with a parabolic density profile

    Energy Technology Data Exchange (ETDEWEB)

    Golian, Y.; Dorranian, D., E-mail: d.dorranian@gmail.com [Laser Laboratory, Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Aslaninejad, M., E-mail: m.aslaninejad@ipm.ir [Institute for Research in Fundamental Sciences (IPM), School of Particles and Accelerators, P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)

    2016-01-15

    A model for the interaction of charged particle beams and plasma for a linear wakefield generation in a parabolic plasma channel is presented. The density profile has the maximum on the axis. A Gaussian proton beam is employed to excite the plasma wakefield in the channel. We have built a thorough analytical model and solved the governing equations for the wakefield acceleration of a charged particle beam. The longitudinal and radial wakefields are expressed by Whittaker functions, and for certain parameters of plasma and the beam, their behaviours in longitudinal and radial directions are investigated. It is observed that the radial electric field generated by the bunch increases with the distance behind the bunch.

  4. Whittaker functions in beam driven plasma wakefield acceleration for a plasma with a parabolic density profile

    International Nuclear Information System (INIS)

    A model for the interaction of charged particle beams and plasma for a linear wakefield generation in a parabolic plasma channel is presented. The density profile has the maximum on the axis. A Gaussian proton beam is employed to excite the plasma wakefield in the channel. We have built a thorough analytical model and solved the governing equations for the wakefield acceleration of a charged particle beam. The longitudinal and radial wakefields are expressed by Whittaker functions, and for certain parameters of plasma and the beam, their behaviours in longitudinal and radial directions are investigated. It is observed that the radial electric field generated by the bunch increases with the distance behind the bunch

  5. Contribution of Beam-Driven Fusion in Pure Deuterium Plasma

    International Nuclear Information System (INIS)

    The urgent and ultimate goal of the fusion research is to accomplish a fusion reactor functioning practically. Though the first fusion reactor is expected to use a DT fuel, most fusion researchers have studied H or D plasmas instead of DT plasma because of radioactivity and resource problems. DD plasma experiments, now a usual trend, can give useful information on the fusion plasma physics, tritium retention, alpha particle transport, neutronics, and so on at a safe controlled radiation level. The KSTAR tokamak, all-superconductor world level fusion research device, has been operated with pure deuterium plasmas since the 2010 campaign, however, the thermal fusion reaction rate is still far below significant because of low plasma temperature. The NBI system equipped on the KSTAR tokamak can deliver more than 1.5 MW input power of deuterium neutral beam at 100 keV with one ion source, which have contributed to making H-mode plasmas for several seconds. The next goal of the NBI input power at the 2012 campaign is 3.5 MW with two ion sources. Hot ions generated from the deuterium neutral beam injected into the D plasma can produce beam-driven fusion reactions at a much more notable level than thermal ones. Contribution of deuterium neutral beam injection on the fusion reactions in a D plasma is preliminarily assessed here

  6. Electron beam generation in the fore-vacuum pressure range

    CERN Document Server

    Burachevskij, Y A; Kuzemchenko, M N; Mytnikov, A V; Oks, E M

    2001-01-01

    One presents the results of investigations to generate electron beams within 0.01-0.1 Torr gas pressure range. To generate a beam one used a plasma source based on a hollow cathode discharge in combination with a plane accelerating gap. Peculiar features of electron emission and acceleration within the mentioned pressure range are associated with high probability of gas ionization in an accelerating gap and with generation of ion flow meeting electron beam. It results in reduction of discharge combustion intensification, as well as, in plasma concentration range. The developed design of an electron source enables to generate cylindrical beams with up to 1 A current and with up to 10 keV energy

  7. Low energy, high power hydrogen neutral beam for plasma heating

    Science.gov (United States)

    Deichuli, P.; Davydenko, V.; Ivanov, A.; Korepanov, S.; Mishagin, V.; Smirnov, A.; Sorokin, A.; Stupishin, N.

    2015-11-01

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  8. Low energy, high power hydrogen neutral beam for plasma heating.

    Science.gov (United States)

    Deichuli, P; Davydenko, V; Ivanov, A; Korepanov, S; Mishagin, V; Smirnov, A; Sorokin, A; Stupishin, N

    2015-11-01

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction. PMID:26628137

  9. Anomalous resistivity effect on multiple ion beam emission and hard x-ray generation in a Mather type plasma focus device

    International Nuclear Information System (INIS)

    Multi ion beam and hard x-ray emissions were detected in a high inductance (more than 100 nH) Mather type plasma focus (PF) device at different filling gas pressures and charging voltages. The signal analysis was performed through the current trace, as it is the fundamental signal from which all of the phenomena in a PF device can be extracted. Two different fitting processes were carried out according to Lee's computational (snow-plow) model. In the first process, only plasma dynamics and classical (Spitzer) resistances were considered as energy consumer parameters for plasma. This led to an unsuccessful fitting and did not answer the energy transfer mechanism into plasma. A second fitting process was considered through the addition of anomalous resistance, which provided the best fit. Anomalous resistance was the source of long decrease in current trace, and multi dips and multi peaks of high voltage probe. Multi-peak features were interpreted considering the second fitting process along with the mechanisms for ion beam production and hard x-ray emission. To show the important role of the anomalous resistance, the duration of the current drop was discussed.

  10. NSPEC - A neutron spectrum code for beam-heated fusion plasmas

    International Nuclear Information System (INIS)

    A 3-dimensional computer code is described, which computes neutron spectra due to beam heating of fusion plasmas. Three types of interactions are considered; thermonuclear of plasma-plasma, beam-plasma and beam-beam interactions. Beam deposition is modelled by the NFREYA code. The applied steady state beam distribution as a function of pitch angle and velocity contains the effects of energy diffusion, friction, angular scattering, charge exchange, electric field and source pitch angle distribution. The neutron spectra, generated by Monte-Carlo methods, are computed with respect to given lines of sight. This enables the code to be used for neutron diagnostics. (author)

  11. Plasma neutralization models for intense ion beam transport in plasma

    International Nuclear Information System (INIS)

    Plasma neutralization of an intense ion pulse is of interest for many applications, including plasma lenses, heavy ion fusion, cosmic ray propagation, etc. An analytical electron fluid model has been developed based on the assumption of long charge bunches (lb >> rb). Theoretical predictions are compared with the results of calculations utilizing a particle-in-cell (PIC) code. The cold electron fluid results agree well with the PIC simulations for ion beam propagation through a background plasma. The analytical predictions for the degree of ion beam charge and current neutralization also agree well with the results of the numerical simulations. The model predicts very good charge neutralization (>99%) during quasi-steady-state propagation, provided the beam pulse duration τb is much longer than the electron plasma period 2π/ωp, where ωp = (4πe2np/m)1/2 is the electron plasma frequency, and np is the background plasma density. In the opposite limit, the beam pulse excites large-amplitude plasma waves. The analytical formulas derived in this paper can provide an important benchmark for numerical codes, and provide scaling relations for different beam and plasma parameters

  12. Plasma heating with crossing relativistic electron beams

    Science.gov (United States)

    Ratan, Naren; Sircombe, Nathan; Ceurvorst, Luke; Kasim, Muhammad; Sadler, James; Bingham, Robert; Trines, Raoul; Norreys, Peter

    2015-11-01

    Plasma heating by relativistic electron beams is a powerful tool with applications including the heating of inertial confinement fusion targets and the study of matter in extreme conditions. We discuss the use of two relativistic electron beams to efficiently heat the plasma ions where the beams cross by using beam-plasma instabilities and non-linear wave coupling between Langmuir and ion-acoustic waves. Energy from the electron beams is coupled to the plasma ions as the beams become unstable and drive Langmuir waves which couple non-linearly to ion-acoustic waves which are then damped . Results of linear growth rate calculations are presented for the system of two crossing electron beams demonstrating a broad spectrum of unstable modes. Relativistic Vlasov-Maxwell simulations in two space and two momentum dimensions have been performed which demonstrate the non-linear coupling of the electron beam energy into ion-acoustic waves and the energy cascade to the background ions. Time-frequency analysis is applied to analyze the non-linear coupling between Langmuir and ion-acoustic waves in wave phase space. Structural properties of the strong turbulence produced at late times are analyzed.

  13. Intense relativistic electron beam: generation and propagation

    International Nuclear Information System (INIS)

    A general review of relativistic electron beam extracted from explosive field emission diode has been presented here. The beam current in the diode gap taking into account cathode and anode plasma expansion velocity and excluding the self magnetic field effect is directly proportional to gap voltage V3/2 and inversely proportional to the square of the effective diode gap (d-vt). In the limit of high current, self magnetic field focusing effect comes into play and results in a critical current at which pinching will take place. When the diode current exceeds the critical current, the electron flow is in the para-potential regime. Different diode geometries such as planner, coaxial, rod-pinched, reflex triode are discussed qualitatively. When the beam is injected into a vacuum drift tube the propagation of the beam is only possible in presence of a strong axial magnetic field which prevents the beam expansion in the radial direction. If the beam is injected in the drift tube filled with dense plasma, then the redistribution of the plasma electrons effectively neutralizes the beam space charge, resulting subsequent propagation of the beam along the drift tube. The beam propagation through neutral gas is similar to the plasma filled drift tube. In this case both the neutral gas pressure and the beam current regulate the transmission of the REB. (author)

  14. COUNTER PROPAGATION OF ELECTRON AND CO2 LASER BEAMS IN A PLASMA CHANNEL

    International Nuclear Information System (INIS)

    A high-energy CO2 laser is channeled in a capillary discharge. Occurrence of guiding conditions at a relatively low plasma density (18 cm-3) is confirmed by MHD simulations. Divergence of relativistic electron beam changes depending on the plasma density. Counter-propagation of the electron and laser beams inside the plasma channel results in intense x-ray generation

  15. Particle in cell simulations of beam plasma system

    International Nuclear Information System (INIS)

    The propagation of relativistic electron beam in dense plasma is studied with the help of Particle in Cell simulations for both 2D and 3D configurations. The background plasma system provides for the return currents balancing the beam current. These two current systems are unstable to Weibel destabilization as a result of which the forward and return currents separate spatially. This leads to the generation of magnetic fields. The present paper focuses on the study of the spatial and temporal profiles of the generated magnetic fields. In the normal case of infinite and/or periodic simulation box with homogeneous plasma density the observed magnetic field dominates at the scale length of skin depth. The role of plasma density inhomogeneity and the finite transverse width of the beam electrons are investigated in the work. It is shown that when the plasma density inhomogeneity with scales sharper than the skin depth is chosen, the magnetic field structures with similar short scales form. It is also observed that when the beam width is finite magnetic fields with structures at the scale length of beam width form. (author)

  16. Conditional eddies, or clumps, in ion-beam-generated turbulence

    DEFF Research Database (Denmark)

    Johnsen, Helene; Pecseli, H. L.; Trulsen, J.

    1985-01-01

    Low-frequency electrostatic fluctuations are investigated experimentally in an unmagnetized plasma. The turbulence is generated by ion-ion-beam instabilities. Real-time signals are recorded and investigated statistically on a conditional basis. The formation and propagation of structures with a r......Low-frequency electrostatic fluctuations are investigated experimentally in an unmagnetized plasma. The turbulence is generated by ion-ion-beam instabilities. Real-time signals are recorded and investigated statistically on a conditional basis. The formation and propagation of structures...

  17. Foil-less plasma-filled diode for HPM generator

    Science.gov (United States)

    Eltchaninov, A. A.; Kovalchuk, B. M.; Kurkan, I. K.; Zherlitsyn, A. A.

    2014-11-01

    Plasma-filled diode regarded as perspective source of electron beam feeding HPM generator of GW power level, comparing to conventional explosive emission vacuum diode. Electron beam generation occurs in plasma double layer, where plasma boundary plays as an anode. It allows cancelling the usage of anode foils or grids in HPM generators with the virtual cathode, which could limit its life time to few shots. The presence of ions in the e-beam drift space could raise the limiting current for a drift space, but it could affect to microwave generation also. Sectioned plasma-filled diode with beam current of about 100 kA, electron beam energy of about 0.5 MV and beam current density of 1-10 kA/cm2 was realized. Cylindrical transport channel with the diameter of 200 mm and the length of about 30 cm was attached to the diode. Beam current measurements in a drift space were performed. Computer simulations of electron beam transport with the presence of ions were carried out with the 2.5D axisymmetric version of PiC-code KARAT. Obtained results would help optimizing electrodynamic system of HPM generator subjected to the presence of ions.

  18. Foil-less plasma-filled diode for HPM generator

    International Nuclear Information System (INIS)

    Plasma-filled diode regarded as perspective source of electron beam feeding HPM generator of GW power level, comparing to conventional explosive emission vacuum diode. Electron beam generation occurs in plasma double layer, where plasma boundary plays as an anode. It allows cancelling the usage of anode foils or grids in HPM generators with the virtual cathode, which could limit its life time to few shots. The presence of ions in the e-beam drift space could raise the limiting current for a drift space, but it could affect to microwave generation also. Sectioned plasma-filled diode with beam current of about 100 kA, electron beam energy of about 0.5 MV and beam current density of 1-10 kA/cm2 was realized. Cylindrical transport channel with the diameter of 200 mm and the length of about 30 cm was attached to the diode. Beam current measurements in a drift space were performed. Computer simulations of electron beam transport with the presence of ions were carried out with the 2.5D axisymmetric version of PiC-code KARAT. Obtained results would help optimizing electrodynamic system of HPM generator subjected to the presence of ions

  19. Generating stable tractor beams with dielectric metasurfaces

    Science.gov (United States)

    Pfeiffer, Carl; Grbic, Anthony

    2015-03-01

    Propagation-invariant beams that pull objects towards a light source are commonly known as tractor beams. Here, an efficient, linearly polarized tractor beam with improved stability is introduced. The beam consists of a superposition of transverse-electric and transverse-magnetic polarized Bessel beams of orders m =+1 and m =-1 . It is shown that this beam can stably pull a wide range of dielectric microparticles arbitrarily long distances, independent of ambient conditions. Next, a straightforward method of generating these high-performance beams is proposed. A Si metasurface transforms an incident linearly polarized Gaussian beam into the desired tractor beam. Full-wave simulations demonstrate that it is possible for this simple geometry to pull a polystyrene sphere a distance equal to the nondiffracting range of the Bessel beam. The simplicity of the setup and the robust performance of the proposed tractor beam significantly enhance the ability to manipulate matter with light.

  20. OAM beams from incomplete computer generated holograms

    CERN Document Server

    Zambale, Niña Angelica F; Hermosa, Nathaniel

    2016-01-01

    In this letter we show that optical beams with orbital angular momentum (OAM) can be generated even with incomplete computer generated holograms (CGH). These holograms are made such that random portions of it do not contain any information. We observe that although the beams produced with these holograms are less intense, these beams maintain their shape and that their topological charges are not affected. Furthermore, we show that superposition of two or more beams can be created using separate incomplete CGHs interspersed together. Our result is significant especially since most method to generate beams with OAM for various applications rely on pixelated devices or optical elements with imperfections.

  1. Use of molecular beams to support microspheres during plasma coating

    International Nuclear Information System (INIS)

    Spherical targets can be levitated on beams of Ar or other gas atoms. This is an especially useful technique for supporting microspheres during plasma coating and processing. Measurements of gas flow and pressure indicate that the levitation device operates in the regime of Knudsen's flow. This device is currently being used in the development of future generation laser targets

  2. Ions beams and ferroelectric plasma sources

    Science.gov (United States)

    Stepanov, Anton

    Near-perfect space-charge neutralization is required for the transverse compression of high perveance ion beams for ion-beam-driven warm dense matter experiments, such as the Neutralized Drift Compression eXperiment (NDCX). Neutralization can be accomplished by introducing a plasma in the beam path, which provides free electrons that compensate the positive space charge of the ion beam. In this thesis, charge neutralization of a 40 keV, perveance-dominated Ar+ beam by a Ferroelectric Plasma Source (FEPS) is investigated. First, the parameters of the ion beam, such as divergence due to the extraction optics, charge neutralization fraction, and emittance were measured. The ion beam was propagated through the FEPS plasma, and the effects of charge neutralization were inferred from time-resolved measurements of the transverse beam profile. In addition, the dependence of FEPS plasma parameters on the configuration of the driving pulser circuit was studied to optimize pulser design. An ion accelerator was constructed that produced a 30-50 keV Ar + beam with pulse duration ion source showed that the dependence of beam radius on Q was consistent with space charge expansion. It was concluded that the beam was perveance-dominated with a charge neutralization fraction of approximately zero in the absence of neutralizing plasma. Since beam expansion occurred primarily due to space charge, the decrease in effective perveance due to neutralization by FEPS plasma can be inferred from the reduction in beam radius. Results on propagation of the ion beam through FEPS plasma demonstrate that after the FEPS is triggered, the beam radius decreases to its neutralized value in about 5 mus. The duration of neutralization was about 10 mus at a charging voltage VFEPS = 5.5 kV and 35 mus at VFEPS = 6.5 kV. With VFEPS = 6.5 kV, the transverse current density profile 33 cm downstream of the source had a Gaussian shape with xrms =5 mm, which corresponds to a half-angle divergence of 0.87°. The

  3. Gaussian beam evolution in nonlinear inhomogeneous plasma

    Science.gov (United States)

    Berczynski, P.; Kravtsov, Yu. A.; Tikhonchuk, V.; Tikhonchuk

    2014-04-01

    The method of nonlinear complex geometrical optics (NCGO) is proposed in this paper for description of the evolution of a spatially narrow Gaussian beam (GB) in an inhomogeneous nonlinear plasma. NCGO method deals with first-order ordinary differential equations for the complex curvature of the wave front and for GB amplitude and for second-order ordinary differential equation for GB width. Thus, NCGO simplifies the description of GB diffraction and self-focusing effects as compared to the known methods of plasma physics and this way it can be assumed to be attractive and comprehensive approach in problems of plasma heating by electromagnetic waves. Moreover, we demonstrate in this paper some regularity for nonlinear inhomogeneous plasma in the framework of which central ray of a GB is not subjected to nonlinear refraction within NCGO method boundary applicability. On the contrary, the beam width, wave front curvature, and GB amplitude are modified by diffraction and self-focusing processes. General properties of the beam propagation are illustrated with results of numerical modeling for two particular cases: GB diffraction and self-focusing along curvilinear trajectory with torsion in axially symmetric plasma column and GB reflection from nonlinear inhomogeneous plasma layer. We prove in this paper that NCGO is new effective method of plasma physics, which can be applied for improvement of ray tracing techniques and plasma diagnostics.

  4. 2-D studies of Relativistic electron beam plasma instabilities in an inhomogeneous plasma

    CERN Document Server

    Shukla, Chandrashekhar; Patel, Kartik

    2015-01-01

    Relativistic electron beam propagation in plasma is fraught with several micro instabilities like two stream, filamentation etc., in plasma. This results in severe limitation of the electron transport through a plasma medium. Recently, however, there has been an experimental demonstration of improved transport of Mega Ampere of electron currents (generated by the interaction of intense laser with solid target) in a carbon nanotube structured solid target [Phys. Rev Letts. 108, 235005 (2012)]. This then suggests that the inhomogeneous plasma (created by the ionization of carbon nano tube structured target) helps in containing the growth of the beam plasma instabilities. This manuscript addresses this issue with the help of a detailed analytical study and simulations with the help of 2-D Particle - In - Cell code. The study conclusively demonstrates that the growth rate of the dominant instability in the 2-D geometry decreases when the plasma density is chosen to be inhomogeneous, provided the scale length 1/ks...

  5. Electron beam parallel X-ray generator

    Science.gov (United States)

    Payne, P.

    1967-01-01

    Broad X ray source produces a highly collimated beam of low energy X rays - a beam with 2 to 5 arc minutes of divergence at energies between 1 and 6 keV in less than 5 feet. The X ray beam is generated by electron bombardment of a target from a large area electron gun.

  6. Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction

    Science.gov (United States)

    Scisciò, M.; Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Papaphilippou, Y.; Antici, P.

    2016-03-01

    In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.

  7. Plasma Heating under Beam Instability Conditions

    International Nuclear Information System (INIS)

    Results are discussed of the interaction of electron beams with a plasma in mirror magnetic fields and the heating of the electron and ion components of the plasma under beam instability conditions. The experiments were carried out in a mirror device with mirror ratio 1.5 and a maximum field of 1500 Oe at the centre. An electron beam of 200 to 300 mA and energy up to 4 keV was injected continuously. Plasma was formed by the ionization of the gas (hydrogen or helium) filling the vessel at pressures of 10-4 to 10-5 Torr. As a result of the interaction of the electron beam with the plasma, a broad spectrum of plasma and electromagnetic waves is excited in the system. The spectra of the high- and of the low-frequency oscillations in beam instability conditions were experimentally investigated. A broad spectrum of oscillations in the region of the plasma and cyclotron frequencies was observed. The results are described of the investigations of the systematic low-frequency oscillations excited in the region from 10 to 50 kc/s, and possible mechanisms responsible for the excitation of the oscillations are discussed. The observed absorption of the energy of the high-frequency oscillations in the region of the electroncyclotron frequency and its harmonics is also considered. The interaction between the plasma particles and the fields of the oscillations excited in the system cause the directed energy of the beam to be transformed into thermal plasma energy. Intense X-radiation from the plasma region was recorded; from its energy distribution, the plasma electron temperature was determined of the order of 20 to 40 keV. The plasma density determined from the X-radiation power was (1 to 2) x 1011 cm-3. According to microwave measurements one obtains ne ∼(0.7 to 1) x 10-12 cm-3. The heating of the plasma is also confirmed by spectrometric measurements of the electron temperature from the relative intensity of the helium lines. The ion temperature measured from the Doppler

  8. Dynamics of ion beam charge neutralization by ferroelectric plasma sources

    Science.gov (United States)

    Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C.

    2016-04-01

    Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar+ beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15 V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established ˜5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-μs surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of μs after the high voltage pulse is applied. It is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.

  9. High order harmonic generation from plasma mirror

    International Nuclear Information System (INIS)

    When an intense laser beam is focused on a solid target, its surface is rapidly ionized and forms a dense plasma that reflects the incident field. For laser intensities above few 1015 W/cm2, high order harmonics of the laser frequency, associated in the time domain to a train of atto-second pulses (1 as = 1018 s), can be generated upon this reflection. Because such a plasma mirror can be used with arbitrarily high laser intensities, this process should eventually lead to the production of very intense pulses in the X-ray domain. In this thesis, we demonstrate that for laser intensities about 1019 W/cm2, two mechanisms can contribute to the generation of high order harmonics: the coherent wake emission and the relativistic emission. These two mechanisms are studied both theoretically and experimentally. In particular, we show that, thanks to very different properties, the harmonics generated by these two processes can be unambiguously distinguished experimentally. We then investigate the phase properties of the harmonic, in the spectral and in the spatial domain. Finally, we illustrate how to exploit the coherence of the generation mechanisms to get information on the dynamics of the plasma electrons. (author)

  10. Beam-Generated Detector Backgrounds at CESR

    OpenAIRE

    Henderson, Stuart; Cinabro, David

    2000-01-01

    The CESR/CLEO Phase II interaction region is described. The operational experience with beam-generated detector backgrounds is reviewed. The status of our understanding of beam-generated detector backgrounds at CESR is described and comparisons of background measurements with simulation predictions are presented.

  11. Propagation of a nonrelativistic electron beam in a plasma in a magnetic field

    International Nuclear Information System (INIS)

    Propagation of a nonrelativistic electron beam in a plasma in a strong magnetic field has been studied using electrostatic one-dimensional particle simulation models. Electron beams of finite pulse length and of continuous injection are followed in time to study the effects of beam-plasma interaction on the beam propagation. For the case of pulsed beam propagation, it is found that the beam distribution rapidly spreads in velocity space generating a plateaulike distribution with a high energy tail extending beyond the initial beam velocity

  12. Generation of monoenergetic ion beams with a laser accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Pfotenhauer, Sebastian M.

    2009-01-29

    A method for the generation of monoenergetic proton and ion beams from a laser-based particle accelerator is presented. This method utilizes the unique space-charge effects occurring during relativistic laser-plasma interactions on solid targets in combination with a dot-like particle source. Due to this unique interaction geometry, MeV proton beams with an intrinsically narrow energy spectrum were obtained, for the first time, from a micrometer-scale laser accelerator. Over the past three years, the acceleration scheme has been consistently improved to enhance both the maximum particle energy and the reliability of the setup. The achieved degree of reliability allowed to derive the first scaling laws specifically for monoenergetic proton beams. Furthermore, the acceleration scheme was expanded on other target materials, enabling the generation of monoenergetic carbon beams. The experimental work was strongly supported by the parallel development of a complex theoretical model, which fully accounts for the observations and is in excellent agreement with numerical simulations. The presented results have an extraordinarily broad scope way beyond the current thesis: The availability of monoenergetic ion beams from a compact laser-plasma beam source - in conjunction with the unique properties of laser-produced particle beams - addresses a number of outstanding applications in fundamental research, material science and medical physics, and will help to shape a new generation of accelerators. (orig.)

  13. Generation of monoenergetic ion beams with a laser accelerator

    International Nuclear Information System (INIS)

    A method for the generation of monoenergetic proton and ion beams from a laser-based particle accelerator is presented. This method utilizes the unique space-charge effects occurring during relativistic laser-plasma interactions on solid targets in combination with a dot-like particle source. Due to this unique interaction geometry, MeV proton beams with an intrinsically narrow energy spectrum were obtained, for the first time, from a micrometer-scale laser accelerator. Over the past three years, the acceleration scheme has been consistently improved to enhance both the maximum particle energy and the reliability of the setup. The achieved degree of reliability allowed to derive the first scaling laws specifically for monoenergetic proton beams. Furthermore, the acceleration scheme was expanded on other target materials, enabling the generation of monoenergetic carbon beams. The experimental work was strongly supported by the parallel development of a complex theoretical model, which fully accounts for the observations and is in excellent agreement with numerical simulations. The presented results have an extraordinarily broad scope way beyond the current thesis: The availability of monoenergetic ion beams from a compact laser-plasma beam source - in conjunction with the unique properties of laser-produced particle beams - addresses a number of outstanding applications in fundamental research, material science and medical physics, and will help to shape a new generation of accelerators. (orig.)

  14. Nonlinear beam plasma interaction in plasma with a superthermal electrons

    International Nuclear Information System (INIS)

    The study of plasmas containing superthermal particles is very important to the understanding of space and astrophysical phenomena. The non-Maxwellian plasmas are also crucial to the understanding of space and astrophyisical plasma dynamics. The kappa-type distribution is used to model a high energy tail in the electron/ion distribution function. We have investigated the dynamics of small amplitude electrostatic solitary structures in a plasma consisting of superthermal electrons, ions and an electron beam. Solitary structures is investigated. The effect(s) of ion beam characteristics, as well as of superthermality of the background, have been studied numerically to trace their influence on solitary structures. The results of this investigation may be important for understanding the nonlinear structures in astrophysical and space environments. (author)

  15. Miniature Coaxial Plasma injector Diagnostics by Beam Plasma Interaction

    International Nuclear Information System (INIS)

    A miniature coaxial gun has been used to study the interaction between plasma beam and low density plasma formed in glow discharge. The peak discharge current flow between the coaxial electrodes was 5.25 kA as a single pulse with pulse width of 60 mu. Investigations are carried out with argon gas at pressure 0.4 Torr. The plasma stream ejected from the coaxial discharge propagates in the neutral argon atoms with mean velocity of 1.2x105cm/s. The plasma stream temperature and density were 4.2 eV and 2.4x1013 cm-3respectively. An argon negative glow has been used as base plasma where its electron temperature and density were 2.2 eV and 6.2x107 cm-3 respectively. When the plasma stream propagates through the negative glow discharge region its velocity decreased to 8.8 x 104 cm/s and also the plasma electron temperature decreased to 3.1 eV, while the stream density remained the same. An excited wave appeared on the electric probe having frequency equal to the plasma frequency of the plasma under consideration. Simulation of the problem showed that this method could be applied for plasma diagnostics within the region of investigation. Those further studies for high temperature, dense, and magnetized plasma will be considered

  16. Strategies for mitigating the ionization-induced beam head erosion problem in an electron-beam-driven plasma wakefield accelerator

    Science.gov (United States)

    An, W.; Zhou, M.; Vafaei-Najafabadi, N.; Marsh, K. A.; Clayton, C. E.; Joshi, C.; Mori, W. B.; Lu, W.; Adli, E.; Corde, S.; Litos, M.; Li, S.; Gessner, S.; Frederico, J.; Hogan, M. J.; Walz, D.; England, J.; Delahaye, J. P.; Muggli, P.

    2013-10-01

    Strategies for mitigating ionization-induced beam head erosion in an electron-beam-driven plasma wakefield accelerator (PWFA) are explored when the plasma and the wake are both formed by the transverse electric field of the beam itself. Beam head erosion can occur in a preformed plasma because of a lack of focusing force from the wake at the rising edge (head) of the beam due to the finite inertia of the electrons. When the plasma is produced by field ionization from the space charge field of the beam, the head erosion is significantly exacerbated due to the gradual recession (in the beam frame) of the 100% ionization contour. Beam particles in front of the ionization front cannot be focused (guided) causing them to expand as in vacuum. When they expand, the location of the ionization front recedes such that even more beam particles are completely unguided. Eventually this process terminates the wake formation prematurely, i.e., well before the beam is depleted of its energy. Ionization-induced head erosion can be mitigated by controlling the beam parameters (emittance, charge, and energy) and/or the plasma conditions. In this paper we explore how the latter can be optimized so as to extend the beam propagation distance and thereby increase the energy gain. In particular we show that, by using a combination of the alkali atoms of the lowest practical ionization potential (Cs) for plasma formation and a precursor laser pulse to generate a narrow plasma filament in front of the beam, the head erosion rate can be dramatically reduced. Simulation results show that in the upcoming “two-bunch PWFA experiments” on the FACET facility at SLAC national accelerator laboratory the energy gain of the trailing beam can be up to 10 times larger for the given parameters when employing these techniques. Comparison of the effect of beam head erosion in preformed and ionization produced plasmas is also presented.

  17. Particle Simulations for Electron Beam-Plasma Interactions

    Science.gov (United States)

    Zhou, Guo-cheng; G, Zhou C.; Li, Yang; Cao, Jin-bin; J, Cao B.; Wang, Xue-yi; X, Wang Y.

    1998-12-01

    The computer simulations of high-frequency instabilities excited by the high density electron beam and their nonlinear effect are presented. One-dimensional electromagnetic particle simulations are performed with different values of the electron beam-to-plasma density ratio. The results show that for the high electron beam-to-background plasma density ratio, all the Langmuir waves and two electromagnetic waves with left-hand and right-hand circular polarizations (i.e., the "L-O mode" and the "R-X mode") propagating parallel to the magnetic field can be generated and the maximum values of wave electric fields are nearly the same. The electron beam and background plasma are diffused and a part of energetic background electrons are obviously accelerated by the wave-particle interactions. The heating of the beam and background plasma is mainly due to the electrostatic (Langmuir) wave-particle interactions, but the accelerations of a part of energetic background electrons may be mainly due to the electromagnetic wave-particle interactions.

  18. Development of an x-ray Talbot-Lau moire deflectometer for fast density profile measurements of dense plasmas generated by beam-target interactions

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, Dan [National Security Technol., LLC, Los Alamos, NM (United States); Berninger, M; Meidinger, A; Stutman, Dan; Valdivia, Maria Pia

    2015-05-01

    For the first time an x-ray Talbot-Lau moire deflectometer is being developed that will use a flash tube source and fast detector for dynamic density gradient measurements. In Talbot-Lau moire deflectometry, an x-ray grating makes an image of itself on a second grating (the Talbot effect) to produce a moire pattern on a detector. The test object is placed between these gratings, with variations in index of refraction changing the pattern. A third grating in front of an incoherent x-ray source produces an array of coherent sources. With a 150 kV x-ray flash tube as the source, the gratings are placed in a glancing angle setup for performance at ~60 keV. The detector is a gated CCD with a fast scintillator for x-ray conversion. This diagnostic, designed for the Dual-Axis Radiographic Hydrodynamic Test facility (DARHT) at Los Alamos National Laboratory, measures the density profile of dense plasma plumes ejected from beam-target interactions. DARHT has two high-current, pulsed, inductive linear electron accelerators with bremsstrahlung targets at the end of each beam line to create 2-D radiographic images of hydrodynamic tests. One multi-pulse accelerator has up to four beam pulses striking the same target within 2 μs. Computer simulations that model target evolution and ejected material between pulses are used to design these targets for optimal radiographic performance; the x-ray deflectometer will directly measure density gradients in the ejected plumes and provide the first experimental constraints to these models. During the first year, currently underway, the diagnostic systems are being designed. In year two, the flash tube and fast detector will be deployed at DARHT for radiographic imaging while the deflectometer is built and tested on the bench with a continuous source. Finally, in year three, the fast deflectometer will be installed on DARHT and density measurements will be performed.

  19. Pulsed metallic-plasma generators.

    Science.gov (United States)

    Gilmour, A. S., Jr.; Lockwood, D. L.

    1972-01-01

    A pulsed metallic-plasma generator is described which utilizes a vacuum arc as the plasma source. The arc is initiated on the surface of a consumable cathode which can be any electrically conductive material. Ignition is accomplished by using a current pulse to vaporize a portion of a conductive film on the surface of an insulator separating the cathode from the ignition electrode. The film is regenerated during the ensuing arc. Over 100 million ignition cycles have been accomplished by using four 0.125-in. diameter zinc cathodes operating in parallel and high-density aluminum-oxide insulators. Among the applications being investigated for the generator are metal deposition, vacuum pumping, electric propulsion, and high-power dc arc interruption.

  20. Cluster beam sources. Part 1. Methods of cluster beams generation

    Directory of Open Access Journals (Sweden)

    A.Ju. Karpenko

    2012-10-01

    Full Text Available The short review on cluster beams generation is proposed. The basic types of cluster sources are considered and the processes leading to cluster formation are analyzed. The parameters, that affects the work of cluster sources are presented.

  1. Cluster beam sources. Part 1. Methods of cluster beams generation

    OpenAIRE

    A.Ju. Karpenko; V.A. Baturin

    2012-01-01

    The short review on cluster beams generation is proposed. The basic types of cluster sources are considered and the processes leading to cluster formation are analyzed. The parameters, that affects the work of cluster sources are presented.

  2. Relativistic electron beam plasma heating experiment

    International Nuclear Information System (INIS)

    An intense (5 x 105 Amp/cm2), relativistic (5 MeV), electron beam will be used to investigate the heating of small volumes (approx. 5 to 10 cm3) of dense plasma (1017 to 1018 electrons/cm3) to kilovolt temperatures via the electrostatic two-stream instability

  3. Laser Plasmas : Optical guiding of laser beam in nonuniform plasma

    Indian Academy of Sciences (India)

    Tarsem Singh Gill

    2000-11-01

    A plasma channel produced by a short ionising laser pulse is axially nonuniform resulting from the self-defocusing. Through such preformed plasma channel, when a delayed pulse propagates, the phenomena of diffraction, refraction and self-phase modulation come into play. We have solved the nonlinear parabolic partial differential equation governing the propagation characteristics for an approximate analytical solution using variational approach. Results are compared with the theoretical model of Liu and Tripathi (Phys. Plasmas 1, 3100 (1994)) based on paraxial ray approximation. Particular emphasis is on both beam width and longitudinal phase delay which are crucial to many applications.

  4. Monte Carlo simulation of electron beam air plasma characteristics

    Institute of Scientific and Technical Information of China (English)

    Deng Yong-Feng; Han Xian-Wei; Tan Chang

    2009-01-01

    A high-energy electron beam generator is used to generate a plasma in atmosphere. Based on a Monte Carlo toolkit named GEANT4,a model including complete physics processes is established to simulate the passage of the electron beam in air. Based on the model,the characteristics of the electron beam air plasma are calculated. The energy distribution of beam electrons (BEs) indicates that high-energy electrons almost reside in the centre region of the beam,but low-energy electrons always live in the fringe area. The energy deposition is calculated in two cases,i.e.,with and without secondary electrons (SEs). Analysis indicates that the energy deposition of Ses accounts for a large part of the total energy deposition. The results of the energy spectrum show that the electrons in the inlet layer of the low-pressure chamber (LPC) are monoenergetic,but the energy spectrum of the electrons in the outlet layer is not pure. The SEs are largely generated at the outlet of the LPC. Moreover,both the energy distribution of Bes and the magnitude of the density of SEs are closely related to the pressure of LPC. Thus,a conclusion is drawn that a low magnitude of LPC pressure is helpful for reducing the energy loss in the LPC and also useful for greatly increasing the secondary electron density in dense air.

  5. Electron beam time-of-flight plasma potential diagnostic

    International Nuclear Information System (INIS)

    A time-of-flight method for measuring electrostatic potentials in plasmas using a modulated electron beam has been developed. The beam is injected along the magnetic field in a cylindrical plasma geometry. The phase of the electron beam modulation is detected using a Rogowski loop which encircles the beam and plasma, and the phase information is in turn related to the electrostatic potential. Measurements in vacuum and in plasma have been performed

  6. Generation of Solution Plasma for Surface Treatment

    OpenAIRE

    Akaki, Kazuhiko; Matsuda, Masanorix; Matsuda, Yoshinobu; Fujiyama, Hiroshi

    2008-01-01

    Solution plasma has been generated in ultrasonic bubbles with new-type electrodes by supplying alternative power. We found solution plasma can be generated in various solvents by applying this technique. Now we try establishing the plasma generation and its application for surface treatment

  7. High order harmonic generation from plasma mirrors

    International Nuclear Information System (INIS)

    When an intense laser beam is focused on a solid target, the target's surface is rapidly ionized and forms dense plasma that reflects the incident field. For laser intensities above few 10 to the power of 15 Wcm-2, high order harmonics of the laser frequency, associated in the time domain to a train of atto-second pulses (1 as 10-18 s), can be generated upon this reflection. In this thesis, we developed numerical tools to reveal original aspects of harmonic generation mechanisms in three different interaction regime: the coherent wake emission, the relativistic emission and the resonant absorption. In particular, we established the role of these mechanisms when the target is a very thin foil (thickness of the order of 100 nm). Then we study experimentally the spectral, spatial and coherence properties of the emitted light. We illustrate how to exploit these measurements to get information on the plasma mirror dynamics on the femtosecond and atto-second time scales. Last, we propose a technique for the single-shot complete characterization of the temporal structure of the harmonic light emission from the laser-plasma mirror interaction. (author)

  8. Recent advances in plasma devices based on plasma lens configuration for manipulating high-current heavy ion beams

    International Nuclear Information System (INIS)

    We describe new results of development of novel generation cylindrical plasma devices based on the electrostatic plasma lens configuration and concept of electrons magnetic insulation. The crossed electric and magnetic fields plasma lens configuration provides us with the attractive and suitable method for establishing a stable plasma discharge at low pressure. Using plasma lens configuration in this way some cost-effective plasma devices were developed for ion treatment and deposition of exotic coatings and the effective lens was first proposed for manipulating high-current beams of negatively charged particles. Here we describe operation and features of these plasma devices, and results of theoretical consideration of mechanisms determining their optimal operation conditions.

  9. Compressed beam directed particle nuclear energy generator

    International Nuclear Information System (INIS)

    This invention relates to the generation of energy from the fusion of atomic nuclei which are caused to travel towards each other along collision courses, orbiting in common paths having common axes and equal radii. High velocity fusible ion beams are directed along head-on circumferential collision paths in an annular zone wherein beam compression by electrostatic focusing greatly enhances head-on fusion-producing collisions. In one embodiment, a steady radial electric field is imposed on the beams to compress the beams and reduce the radius of the spiral paths for enhancing the particle density. Beam compression is achieved through electrostatic focusing to establish and maintain two opposing beams in a reaction zone

  10. Proton Beam Fast Ignition Fusion: Nonlinear Generation of Bθ-Fields by Knock-on Electrons

    Science.gov (United States)

    Stefan, V. Alexander

    2011-10-01

    The knock-on electrons, generated by the fast proton beam in interaction with the free and bound electrons in a precompressed DT fusion pellet, outrun the proton beam, generating the Bθ-fields ahead of the beam, which may lead to the defocusing of the beam, if Bθ Tabak et al, Phys. Plasmas 1 (5), 1626 (1994); H. L. Buchanan, F. W. Chambers, E. P. Lee, S. S. Yu, R. J. Briggs, and M. N. Rosenbluth, LLNL, UCRL Report 82586, 1979.

  11. Plasma focus ion beam-scaling laws

    International Nuclear Information System (INIS)

    Measurements on plasma focus ion beams include various advanced techniques producing a variety of data which has yet to produce benchmark numbers. Recent numerical experiments using an extended version of the Lee Code has produced reference numbers and scaling trends for number and energy fluence of deuteron beams as functions of stored energy E0. At the pinch exit the ion number fluence (ions m-2) and energy fluence (J m-2) computed as 2.4-7.8×1020 and 2.2-33×106 respectively were found to be independent of E0 from 0.4 – 486 kJ. This work was extended to the ion beams for various gases. The results show that, for a given plasma focus, the fluence, flux, ion number and ion current decrease from the lightest to the heaviest gas except for trend-breaking higher values for Ar fluence and flux. The energy fluence, energy flux, power flow and damage factors are relatively constant from H2 to N2 but increase for Ne, Ar, Kr and Xe due to radiative cooling and collapse effects. This paper reviews this work and in a concluding section attempts to put the accumulating large amounts of data into the form of a scaling law of beam energy Ebeam versus storage energy E0 taking the form for deuteron as: Ebeam = 18.2E01.23; where Ebeam is in J and E0 is in kJ. It is hoped that the establishment of such scaling laws places on a firm footing the reference quantitative ideas for plasma focus ion beams. (author)

  12. Development of beam-plasma instability during the injection a low-energy electron beam into the ionospheric plasma

    International Nuclear Information System (INIS)

    Results are presented from an active experiment on the injection of charged particle beams into the ionospheric plasma. The experiment was carried out in 1992 onboard the Intercosmos-25 satellite and the Magion-3 daughter satellite (APEX). A specific feature of this experiment was that both the ion and electron beams were injected upward, in the same direction along the magnetic field. The most interesting results are the excitation of HF and VLF-LF waves and the generation of fast charged particle flows, which were recorded on both satellites

  13. Plasma Beam Interaction with Negative glow discharge

    International Nuclear Information System (INIS)

    A miniature coaxial gun has been used to study the effect of the energy spectrum of the ejected plasma on the interaction with negative glow region in a normal glow discharge. The peak discharge current flow between the coaxial electrodes was 5.25 K A as a single pulse with pulse duration of 60 MUs. Investigations are carried out with argon gas at pressure 0.4 Torr. The sheath thickness of the ejected plasma from the coaxial discharge was 6 cm with different densities and energies. The spectrum of electron energy varies between 6 eV and 1 eV, while the electron density varies between 5 x 1012 cm -3 and 4x1013 cm -3. The peak velocity of the ejected plasma was 0. 8 x 105 cm sec-1 in the neutral argon atoms. Argon negative glow region used as base plasma has an electron temperature of 2.2 eV and electron density of 6.2 x107 cm-3. It had been found that the velocity of the ejected plasma decreased when it moves in the negative glow region and its mean electron temperature decreased. The results are compared with the theory of beam interaction with cold plasma

  14. Plasma wakefield excitation with a 24 GeV proton beam

    CERN Document Server

    A Caldwell, A; A Pukhov, A; Xia, G

    2011-01-01

    Proton driven plasma wakefield acceleration has recently been proposed as a means of generating high energy electron beams. In this paper, different options for a demonstration experiment with the CERN PS beam are considered. We review a possible magnetic compression of the PS bunches and resulting electric fields in the plasma. Results are then presented for self-modulation of the proton bunch for different plasma densities and lengths. It is found that the latter option offers interesting possibilities for a first experiment.

  15. Plasma wakefield excitation with a 24 GeV proton beam

    International Nuclear Information System (INIS)

    Proton driven plasma wakefield acceleration has recently been proposed as a means of generating high energy electron beams. In this paper, different options for a demonstration experiment with the CERN PS beam are considered. We review a possible magnetic compression of the PS bunches and resulting electric fields in the plasma. Results are then presented for self-modulation of the proton bunch for different plasma densities and lengths. It is found that the latter option offers interesting possibilities for a first experiment.

  16. 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

  17. Beat wave excitation of electron plasma wave by relativistic cross focusing of cosh-Gaussian laser beams in plasma

    Science.gov (United States)

    Singh, Arvinder; Gupta, Naveen

    2015-06-01

    A scheme for beat wave excitation of electron plasma wave (EPW) is proposed by relativistic cross-focusing of two coaxial Cosh-Gaussian (ChG) laser beams in an under dense plasma. The plasma wave is generated on account of beating of two coaxial laser beams of frequencies ω1 and ω2 . The mechanism for laser produced nonlinearity is assumed to be relativistic nonlinearity in electron mass. Following moment theory approach in Wentzel Kramers Brillouin (W.K.B) approximation, the coupled differential equations governing the evolution of spot size of laser beams with distance of propagation have been derived. The relativistic nonlinearity depends not only on the intensity of first laser beam but also on the intensity of second laser beam. Therefore, propagation dynamics of one laser beam affect that of second beam and hence cross-focusing of the two laser beams takes place. Due to non uniform intensity distribution of pump laser beams, the background electron concentration gets modified. The amplitude of EPW, which depends on the background electron concentration, thus gets nonlinearly coupled with the laser beams. The effects of relativistic electron mass nonlinearity and the cross-focusing of pump beams on excitation of EPW have been incorporated. Numerical simulations have been carried out to investigate the effect of laser as well as plasma parameters on cross-focusing of laser beams and further its effect on power of excited EPW.

  18. Production of intense light ion beams from a superpower generator

    International Nuclear Information System (INIS)

    The operation of a pinch-reflex diode as an intense pulsed ion-beam source has been scaled up to the multiterawatt PITHON generator. Ion beams with currents of 1 MA at 1.8 MeV have been extracted in a 130 kJ, 100-ns (FWHM) pulse. The corresponding ion production efficiency is 60%. Power losses were observed in interfacing the coaxial diode to the biconic vacuum feed of the generator. By using smaller area diodes, the average current density at the anode source has been increased to 20 kA/cm2. Proton and deuteron beams were studied in both planar and spherical diode geometries. The focusing of ion beams is predominately by self-magnetic fields for planar diodes and predominately by electrode shaping for spherical diodes. Current densities of at least 150 kA/cm2 were achieved with spherical diodes. The spatial evolution of the anode and cathode plasmas was studied by laser interferometric holography. As the peak of the power pulse is approached, plasmas were observed to expand from the electrodes in fairly uniform profiles with steep density gradients and to accelerate across the vacuum gap. After peak power, anode plasma fluctuations and a high velocity (30 cm/μs) axial plume develop; the latter expands radially coincident with collapse of the power pulse

  19. Anomalous x-ray radiation of beam plasma

    International Nuclear Information System (INIS)

    The properties of non-equilibrium stationary plasma under the conditions of the planned plasma-chemical reactors based on beam-plasma discharge were investigated. The x-ray spectrum of the beam-plasma was measured and anomalous spectral properties were analyzed. Starting with some critical pressure the anomalous radiation was added to the classical bremsstrahlung spectrum. The occurrence of anomalous radiation can be used to diagnose the condition of beam transportation in such systems. (D.Gy.)

  20. Two-dimensional studies of relativistic electron beam plasma instabilities in an inhomogeneous plasma

    International Nuclear Information System (INIS)

    Relativistic electron beam propagation in plasma is fraught with several micro instabilities like two stream, filamentation, etc., in plasma. This results in severe limitation of the electron transport through a plasma medium. Recently, however, there has been an experimental demonstration of improved transport of Mega Ampere of electron currents (generated by the interaction of intense laser with solid target) in a carbon nanotube structured solid target [G. Chatterjee et al., Phys. Rev. Lett. 108, 235005 (2012)]. This then suggests that the inhomogeneous plasma (created by the ionization of carbon nanotube structured target) helps in containing the growth of the beam plasma instabilities. This manuscript addresses this issue with the help of a detailed analytical study and 2-D Particle-In-Cell simulations. The study conclusively demonstrates that the growth rate of the dominant instability in the 2-D geometry decreases when the plasma density is chosen to be inhomogeneous, provided the scale length 1/ks of the inhomogeneous plasma is less than the typical plasma skin depth (c/ω0) scale. At such small scale lengths channelization of currents is also observed in simulation

  1. Two-dimensional studies of relativistic electron beam plasma instabilities in an inhomogeneous plasma

    Science.gov (United States)

    Shukla, Chandrasekhar; Das, Amita; Patel, Kartik

    2015-11-01

    Relativistic electron beam propagation in plasma is fraught with several micro instabilities like two stream, filamentation, etc., in plasma. This results in severe limitation of the electron transport through a plasma medium. Recently, however, there has been an experimental demonstration of improved transport of Mega Ampere of electron currents (generated by the interaction of intense laser with solid target) in a carbon nanotube structured solid target [G. Chatterjee et al., Phys. Rev. Lett. 108, 235005 (2012)]. This then suggests that the inhomogeneous plasma (created by the ionization of carbon nanotube structured target) helps in containing the growth of the beam plasma instabilities. This manuscript addresses this issue with the help of a detailed analytical study and 2-D Particle-In-Cell simulations. The study conclusively demonstrates that the growth rate of the dominant instability in the 2-D geometry decreases when the plasma density is chosen to be inhomogeneous, provided the scale length 1/ks of the inhomogeneous plasma is less than the typical plasma skin depth (c/ω0) scale. At such small scale lengths channelization of currents is also observed in simulation.

  2. Two-dimensional studies of relativistic electron beam plasma instabilities in an inhomogeneous plasma

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Chandrasekhar; Das, Amita, E-mail: amita@ipr.res.in [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Patel, Kartik [Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2015-11-15

    Relativistic electron beam propagation in plasma is fraught with several micro instabilities like two stream, filamentation, etc., in plasma. This results in severe limitation of the electron transport through a plasma medium. Recently, however, there has been an experimental demonstration of improved transport of Mega Ampere of electron currents (generated by the interaction of intense laser with solid target) in a carbon nanotube structured solid target [G. Chatterjee et al., Phys. Rev. Lett. 108, 235005 (2012)]. This then suggests that the inhomogeneous plasma (created by the ionization of carbon nanotube structured target) helps in containing the growth of the beam plasma instabilities. This manuscript addresses this issue with the help of a detailed analytical study and 2-D Particle-In-Cell simulations. The study conclusively demonstrates that the growth rate of the dominant instability in the 2-D geometry decreases when the plasma density is chosen to be inhomogeneous, provided the scale length 1/k{sub s} of the inhomogeneous plasma is less than the typical plasma skin depth (c/ω{sub 0}) scale. At such small scale lengths channelization of currents is also observed in simulation.

  3. Electron beam generation in high voltage glow discharges

    International Nuclear Information System (INIS)

    The generation of intense CW and pulsed electron beams in glow discharges in reviewed. Glow discharge electron guns operate at a pressure of the order of 1 Torr and often have an advantage in applications that require a broad area electron beam in a gaseous atmosphere, such as laser excitation and some aspects of materials processing. Aspects of electron gun design are covered. Diagnostics of the high voltage glow discharges including the electric field distribution mapped by Doppler free laser spectroscopy, and plasma density and electron temperature measurements of the electron yield of different cathode materials under glow discharge conditions are presented

  4. Colliding ionization injection in a beam driven plasma accelerator

    CERN Document Server

    Wan, Y; Li, F; Wu, Y P; Hua, J F; Pai, C -H; Lu, W; Joshi, C; Mori, W B; Gu, Y Q

    2015-01-01

    The proposal of generating high quality electron bunches via ionization injection triggered by an counter propagating laser pulse inside a beam driven plasma wake is examined via two-dimensional particle-in-cell simulations. It is shown that electron bunches obtained using this technique can have extremely small slice energy spread, because each slice is mainly composed of electrons ionized at the same time. Another remarkable advantage is that the injection distance is changeable. A bunch with normalized emittance of 3.3 nm, slice energy spread of 15 keV and brightness of 7.2 A m$^{-2}$ rad$^{-2}$ is obtained with an optimal injection length which is achieved by adjusting the launch time of the drive beam or by changing the laser focal position. This makes the scheme a promising approach to generate high quality electron bunches for the fifth generation light source.

  5. Operational characteristics of the high flux plasma generator Magnum-PSI

    NARCIS (Netherlands)

    van Eck, H. J. N.; Abrams, T.; van den Berg, M. A.; Brons, S.; van Eden, G. G.; Jaworski, M. A.; Kaita, R.; van der Meiden, H. J.; Morgan, T. W.; van de Pol, M.J.; Scholten, J.; Smeets, P. H. M.; De Temmerman, G.; de Vries, P. C.; van Emmichoven, P. A. Zeijlma

    2014-01-01

    Abstract In Magnum-PSI (MAgnetized plasma Generator and \\{NUMerical\\} modeling for Plasma Surface Interactions), the high density, low temperature plasma of a wall stabilized dc cascaded arc is confined to a magnetized plasma beam by a quasi-steady state axial magnetic field up to 1.3 T. It

  6. Charged particle acceleration by electron beam in corrugated plasma waveguide

    International Nuclear Information System (INIS)

    A two-beam charged particle acceleration scheme in a plasma waveguide with corrugated conducting walls is considered. The guiding heavy-current relativistic electron beam is in synchronism with the first plasma wave space harmonics and the accelerated beam is synchronism with a quicker plasma wave. In this case under weak corrugation of the wall the accelerating resonance field effecting the accelerated particles notably increases the field braking the guiding beam. The process of plasma wave excitation with regard to the guiding beam space charge and the relativistic particle acceleration dynamics are investigated by numeric methods. Optimal acceleration modes are found. 19 refs.; 12 figs

  7. Whistler wave generation by non-gyrotropic, relativistic, electron beams

    International Nuclear Information System (INIS)

    Particle-in-cell code, EPOCH, is used for studying features of the wave component evident to propagate backwards from the front of the non-gyrotropic, relativistic beam of electrons injected in the Maxwellian, magnetised background plasma with decreasing density profile. According to recent findings presented in Tsiklauri [Phys. Plasmas 18, 052903 (2011)], Schmitz and Tsiklauri [Phys. Plasmas 20, 062903 (2013)], and Pechhacker and Tsiklauri [Phys. Plasmas 19, 112903 (2012)], in a 1.5-dimensional magnetised plasma system, the non-gyrotropic beam generates freely escaping electromagnetic radiation with properties similar to the Type-III solar radio bursts. In this study, the backwards propagating wave component evident in the perpendicular components of the electromagnetic field in such a system is presented for the first time. Background magnetic field strength in the system is varied in order to prove that the backwards propagating wave's frequency, prescribed by the whistler wave dispersion relation, is proportional to the specified magnetic field. Moreover, the identified whistlers are shown to be generated by the normal Doppler-shifted relativistic resonance. Large fraction of the energy of the perpendicular electromagnetic field components is found to be carried away by the whistler waves, while a small but sufficient fraction is going into L- and R-electromagnetic modes

  8. Microwave bessel beams generation using guided modes

    KAUST Repository

    Salem, Mohamed

    2011-06-01

    A novel method is devised for Bessel beams generation in the microwave regime. The beam is decomposed in terms of a number of guided transverse electric modes of a metallic waveguide. Modal expansion coefficients are computed from the modal power orthogonality relation. Excitation is achieved by means of a number of inserted coaxial loop antennas, whose currents are calculated from the excitation coefficients of the guided modes. The efficiency of the method is evaluated and its feasibility is discussed. Obtained results can be utilized to practically realize microwave Bessel beam launchers. © 2006 IEEE.

  9. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator.

    Science.gov (United States)

    Gessner, Spencer; Adli, Erik; Allen, James M; An, Weiming; Clarke, Christine I; Clayton, Chris E; Corde, Sebastien; Delahaye, J P; Frederico, Joel; Green, Selina Z; Hast, Carsten; Hogan, Mark J; Joshi, Chan; Lindstrøm, Carl A; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A; Mori, Warren B; O'Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-01-01

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m(-1) is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations. PMID:27250570

  10. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    Science.gov (United States)

    Gessner, Spencer; Adli, Erik; Allen, James M.; An, Weiming; Clarke, Christine I.; Clayton, Chris E.; Corde, Sebastien; Delahaye, J. P.; Frederico, Joel; Green, Selina Z.; Hast, Carsten; Hogan, Mark J.; Joshi, Chan; Lindstrøm, Carl A.; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; O'Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-06-01

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m-1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.

  11. Vortex stabilized electron beam compressed fusion grade plasma

    International Nuclear Information System (INIS)

    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.

  12. Digital generation of partially coherent vortex beams.

    Science.gov (United States)

    Perez-Garcia, Benjamin; Yepiz, Adad; Hernandez-Aranda, Raul I; Forbes, Andrew; Swartzlander, Grover A

    2016-08-01

    We present an experimental technique to generate partially coherent vortex beams with an arbitrary azimuthal index using only a spatial light modulator. Our approach is based on digitally simulating the intrinsic randomness of broadband light passing through a spiral phase plate. We illustrate the versatility of the technique by generating partially coherent beams with different coherence lengths and orbital angular momentum content, without any moving optical device. Consequently, we study its cross-correlation function in a wavefront folding interferometer. The comparison with theoretical predictions yields excellent agreement. PMID:27472596

  13. Generation of single plasma channel in air

    International Nuclear Information System (INIS)

    The conditions of generating a single plasma channel in air are studied by using picosecond and femtosecond laser pulse. A stable and single plasma channel can be generated by a picosecond laser pulse with energy of 8-12 mJ and focusing length of 15 cm. The self-generated light emission is observed to be confined in the plasma channel and propagates in the channel. When using short focal length lenses it is easy to generate a single plasma channel in air with femtosecond laser with energy less than 10 mJ. (authors)

  14. Optical plasma torch electron bunch generation in plasma wakefield accelerators

    Science.gov (United States)

    Wittig, G.; Karger, O.; Knetsch, A.; Xi, Y.; Deng, A.; Rosenzweig, J. B.; Bruhwiler, D. L.; Smith, J.; Manahan, G. G.; Sheng, Z.-M.; Jaroszynski, D. A.; Hidding, B.

    2015-08-01

    A novel, flexible method of witness electron bunch generation in plasma wakefield accelerators is described. A quasistationary plasma region is ignited by a focused laser pulse prior to the arrival of the plasma wave. This localized, shapeable optical plasma torch causes a strong distortion of the plasma blowout during passage of the electron driver bunch, leading to collective alteration of plasma electron trajectories and to controlled injection. This optically steered injection is more flexible and faster when compared to hydrodynamically controlled gas density transition injection methods.

  15. 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...

  16. Research on EBEP (Electron Beam Excited Plasma) applications; EBEP (denshi beam reiki plasma) no tekiyo gijutsu ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Yanase, E.; Ryoji, M.; Mori, Y.; Tokai, M. [Kawasaki Heavy Industries, Ltd., Kobe (Japan)

    1996-04-20

    Research and development is actively conducted on machining technologies using plasma in various fields, with studies energetically pursued on etching techniques or those of forming a thin film by the use of high frequency and microwave plasma. The EBEP system jointly developed by Kawasaki Heavy Industries Ltd. and Institute of Physical and Chemical Research is a plasma source for forming a high density plasma by implanting into a plasma chamber from the outside a high-current electron beam accelerated to an energy of approximately 60 to 100eV where the collision cross-section of gas ionization is maximized. The characteristics of the system are such as (1) it enables electron energy distribution to be controlled from outside by varying acceleration voltage, (2) it excels in the controllability of ion energy and (3) it allows to form a steady high-density plasma in a nonmagnetic field. This paper presents the generating principle of EBEP, its plasma characteristics, etching technique using EBEP, thin film forming technique by EBEP-CVD method, and multipurpose apparatus for research and development. 6 refs., 7 figs., 1 tab.

  17. Catenary nanostructures as compact Bessel beam generators

    Science.gov (United States)

    Li, Xiong; Pu, Mingbo; Zhao, Zeyu; Ma, Xiaoliang; Jin, Jinjin; Wang, Yanqin; Gao, Ping; Luo, Xiangang

    2016-02-01

    Non-diffracting Bessel beams, including zero-order and high-order Bessel Beams which carry orbital angular momentum (OAM), enable a variety of important applications in optical micromanipulation, sub-diffraction imaging, high speed photonics/quantum communication, etc. The commonly used ways to create Bessel beams, including an axicon or a digital hologram written to a spatial light modulator (SLM), have great challenges to operate at the nanoscale. Here we theoretically design and experimentally demonstrate one kind of planar Bessel beam generators based on metasurfaces with analytical structures perforated in ultra-thin metallic screens. Continuous phase modulation between 0 to 2π is realized with a single element. In addition, due to the dispersionless phase shift stemming from spin-orbit interaction, the proposed device can work in a wide wavelength range. The results may find applications in future optical communication, nanofabrication and super-resolution imaging, etc.

  18. Catenary nanostructures as compact Bessel beam generators.

    Science.gov (United States)

    Li, Xiong; Pu, Mingbo; Zhao, Zeyu; Ma, Xiaoliang; Jin, Jinjin; Wang, Yanqin; Gao, Ping; Luo, Xiangang

    2016-01-01

    Non-diffracting Bessel beams, including zero-order and high-order Bessel Beams which carry orbital angular momentum (OAM), enable a variety of important applications in optical micromanipulation, sub-diffraction imaging, high speed photonics/quantum communication, etc. The commonly used ways to create Bessel beams, including an axicon or a digital hologram written to a spatial light modulator (SLM), have great challenges to operate at the nanoscale. Here we theoretically design and experimentally demonstrate one kind of planar Bessel beam generators based on metasurfaces with analytical structures perforated in ultra-thin metallic screens. Continuous phase modulation between 0 to 2π is realized with a single element. In addition, due to the dispersionless phase shift stemming from spin-orbit interaction, the proposed device can work in a wide wavelength range. The results may find applications in future optical communication, nanofabrication and super-resolution imaging, etc. PMID:26843142

  19. Diagnostic neutral beams for plasma studies in magnetic fusion devices

    International Nuclear Information System (INIS)

    Nowadays, low-divergent, quasi-stationary neutral beams are widely used in magnetic fusion devices as a diagnostic tool providing unique information about plasma parameters. Essentially, a diagnostic determines the requirements for the beams, which in many cases consist in sufficiently large current density and energy of the particles so that the beam can penetrate to the plasma core. At the same time, the duration of the beams should overlap that of a plasma shot (∼10 s or longer for large machines). We have developed a number of diagnostic hydrogen beams with a maximum beam energy of 55kV, extracted ion current varying up to 6 A, and pulse duration from several milliseconds to 10 s. The beams are formed by a four electrode ion optical system which makes it possible to provide a low divergent (0.5-0.7 deg.) beam. Additionally, a beam can be focused onto a desired point by proper choice of the curvature radius of the grids. The beams can be modulated with a frequency variable up to 500 Hz. The plasma emitter in the injector is provided by a radiofrequency discharge in hydrogen (deuterium) for long duration beams and, alternatively, by an arc-discharge plasma box for the beams with a duration of up to ∼0.5 s. The arc discharge plasma box provides a higher proton fraction (∼90%) than the RF discharge version (∼60%). The parameters for the different beams developed are presented. (author)

  20. Study of a plasma produced in a neutral gas chamber by the injection of a beam generated by a coaxial gun

    International Nuclear Information System (INIS)

    The design and operation of a plasma coaxial gun is described. The penetration and characteristics of the plasma emitted by the gun propagating in a expansion chamber with helium at 40 feBar is analyzed. The diagnostics is made with a double Langmuir probe observing the time variation of the electronic density along the propagation axis. Optical spectroscopy is used to measure one of the emission lines of the plasma radiation propaganting in the medium. The space-time description of the ion distribution function in a free-force field is made by the fit of an analytical model. (L.C.)

  1. Investigation of plasma–surface interaction at plasma beam facilities

    Energy Technology Data Exchange (ETDEWEB)

    Kurnaev, V., E-mail: kurnaev@plasma.mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe sh. 31, 115409 Moscow (Russian Federation); Vizgalov, I.; Gutorov, K. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe sh. 31, 115409 Moscow (Russian Federation); Tulenbergenov, T.; Sokolov, I.; Kolodeshnikov, A.; Ignashev, V.; Zuev, V.; Bogomolova, I. [Institute of Atomic Energy, National Nuclear Center the Republic of Kazakhstan, Street Krasnoarmejsky, 10, 071100 Kurchatov (Kazakhstan); Klimov, N. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, Troitsk, 142190 Moscow (Russian Federation)

    2015-08-15

    The new Plasma Beam Facility (PBF) has been put into operation for assistance in testing of plasma faced components at Material Science Kazakhstan Tokamak (KTM). PBF includes a powerful electron gun (up to 30 kV, 1 A) and a high vacuum chamber with longitudinal magnetic field coils (up to 0.2 T). The regime of high vacuum electron beam transportation is used for thermal tests with power density at the target surface up to 10 GW/m{sup 2}. The beam plasma discharge (BPD) regime with a gas-puff is used for generation of intensive ion fluxes up to 3 ⋅ 10{sup 22} m{sup −2} s{sup −1}. Initial tests of the KTM PBF’s capabilities were carried out: various discharge regimes, carbon deposits cleaning, simultaneous thermal and ion impacts on radiation cooled refractory targets. With a water-cooled target the KTM PBF could be used for high heat flux tests of materials (validated by the experiment with W mock-up at the PR-2 PBF)

  2. Plasma effects in attosecond pulse generation

    Energy Technology Data Exchange (ETDEWEB)

    Boyd, T.J.M. [Centre for Theoretical Physics, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Ondarza-Rovira, R., E-mail: ricardo.ondarza@inin.gob.m [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico 11801, Distrito Federal (Mexico)

    2010-03-29

    Particle-in-cell simulations have been used to explore further the role of plasma effects on the high harmonic spectrum generated in intense ultrarelativistic (UR) laser-plasma interactions. From a study of the electron dynamics during the laser-plasma interaction a strong correlation was established between the reflected laser pulses and plasma effects. The sources of intense attosecond pulses were found to originate within the plasma at sites of high electron density concentrations at which there is a correspondingly strong generation of electrostatic fields.

  3. Structured Beam Generation with a Single Metasurface

    OpenAIRE

    Yue, Fuyong; Wen, Dandan; Xin, Jingtao; Gerardot, Brian; Li, Jensen; Chen, Xianzhong

    2016-01-01

    Despite a plethora of applications ranging from quantum memories to high-resolution lithography, the current technologies to generate vector vortex beams (VVBs) suffer from less efficient energy use, poor resolution, low damage threshold, bulky size and complicated experimental setup, preventing further practical applications. We propose and experimentally demonstrate an approach to generate VVBs with a single metasurface by locally tailoring phase and transverse polarization distribution. Th...

  4. Six beam spherical compression of plasma focus guns

    International Nuclear Information System (INIS)

    A preliminary experiment with a one beam plasma focus is carried out to confirm plasma formation with the lowest input energy of 0.2 kJ for six beam spherical compression of plasma focus guns. The plasma front of this cableless gun can be used for compression and for the coupling of six guns situated along three rectangular axes, providing a good plasma focus pinch instantaneously or many plasma focus pinches continuously. The whole device with the energy bank is mounted on a sphere, and the minimum requirement for the plasma chamber of this sphere is a diameter of ∼ 22 cm. (author). 4 refs, 3 figs

  5. Guiding of Laser Beams in Plasmas by Radiation Cascade Compression

    International Nuclear Information System (INIS)

    The near-resonant heatwave excitation of an electron plasma wave (EPW) can be employed for generating trains of few-fs electromagnetic pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the beat frequency. Consequently, the cascade of sidebands red- and blue-shifted from the fundamental by integer multiples of the beat frequency is generated in the laser spectrum. When the beat frequency is lower than the electron plasma frequency, the phase chirp enables laser beatnote compression by the group velocity dispersion [S. Kalmykov and G. Shvets, Phys. Rev. E 73, 046403 (2006)]. In the 3D cylindrical geometry, the frequency-downshifted EPW not only modulates the laser frequency, but also causes the pulse to self-focus [P. Gibbon, Phys. Fluids B 2, 2196 (1990)]. After self-focusing, the multi-frequency laser beam inevitably diverges. Remarkably, the longitudinal beatnote compression can compensate the intensity drop due to diffraction. A train of high-intensity radiation spikes with continually evolving longitudinal profile can be self-guided over several Rayleigh lengths in homogeneous plasmas. High amplitude of the EPW is maintained over the entire propagation length. Numerical experiments on the electron acceleration in the cascade-driven (cascade-guided) EPW [using the code WAKE by P. Mora and T. M. Antonsen Jr., Phys. Plasmas 4, 217 (1997)] show that achieving GeV electron energy is possible under realistic experimental parameters

  6. Toroidal equilibrium of plasma with concentrated relativistic electron beam

    International Nuclear Information System (INIS)

    A simplified model has been given for toroidal equilibrium of a tokamak-type plasma with high-current concentrated electron beam. The plasma has a thermal pressure, and the electron beam has effective inertial pressure. Strong deformations of tokamak equilibria have been simulated by numerical calculations. Toroidal equilibria with relatively large vertical field are obtained when we consider high-energy intense electron beam. The beam orbit, which is shifted outward from the magnetic axis of the plasma, is closed by the sum of the externally applied relatively large vertical field and the poloidal magnetic field of the plasma. (author)

  7. Modelling of new generation plasma optical devices

    Directory of Open Access Journals (Sweden)

    Litovko Irina V.

    2016-06-01

    Full Text Available The paper presents new generation plasma optical devices based on the electrostatic plasma lens configuration that opens a novel attractive possibility for effective high-tech practical applications. Original approaches to use of plasma accelerators with closed electron drift and open walls for the creation of a cost-effective low-maintenance plasma lens with positive space charge and possible application for low-cost, low-energy rocket engine are described. The preliminary experimental, theoretical and simulation results are presented. It is noted that the presented plasma devices are attractive for many different applications in the state-of-the-art vacuum-plasma processing.

  8. Generation of a hollow laser beam by a multimode fiber

    Institute of Scientific and Technical Information of China (English)

    Hongyu Ma; Huadong Cheng; Wenzhuo Zhang; Liang Liu; Yuzhu Wang

    2007-01-01

    A simple method to generate a hollow laser beam by multimode fiber is reported. A dark hollow laser beam is generated from a multimode fiber and the dependence of the output beam profile on the incident angle of laser beam is analyzed. The results show that this hollow laser beam can be used to trap and guide cold atoms.

  9. Plasma ion sources and ion beam technology inmicrofabrications

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Lili

    2007-09-01

    For over decades, focused ion beam (FIB) has been playing a very important role in microscale technology and research, among which, semiconductor microfabrication is one of its biggest application area. As the dimensions of IC devices are scaled down, it has shown the need for new ion beam tools and new approaches to the fabrication of small-scale devices. In the meanwhile, nanotechnology has also deeply involved in material science research and bioresearch in recent years. The conventional FIB systems which utilize liquid gallium ion sources to achieve nanometer scale resolution can no longer meet the various requirements raised from such a wide application area such as low contamination, high throughput and so on. The drive towards controlling materials properties at nanometer length scales relies on the availability of efficient tools. In this thesis, three novel ion beam tools have been developed and investigated as the alternatives for the conventional FIB systems in some particular applications. An integrated focused ion beam (FIB) and scanning electron microscope (SEM) system has been developed for direct doping or surface modification. This new instrument employs a mini-RF driven plasma source to generate focused ion beam with various ion species, a FEI two-lens electron (2LE) column for SEM imaging, and a five-axis manipulator system for sample positioning. An all-electrostatic two-lens column has been designed to focus the ion beam extracted from the source. Based on the Munro ion optics simulation, beam spot sizes as small as 100 nm can be achieved at beam energies between 5 to 35 keV if a 5 {micro}m-diameter extraction aperture is used. Smaller beam spot sizes can be obtained with smaller apertures at sacrifice of some beam current. The FEI 2LE column, which utilizes Schottky emission, electrostatic focusing optics, and stacked-disk column construction, can provide high-resolution (as small as 20 nm) imaging capability, with fairly long working distance

  10. Plasma ion sources and ion beam technology in microfabrications

    International Nuclear Information System (INIS)

    For over decades, focused ion beam (FIB) has been playing a very important role in microscale technology and research, among which, semiconductor microfabrication is one of its biggest application area. As the dimensions of IC devices are scaled down, it has shown the need for new ion beam tools and new approaches to the fabrication of small-scale devices. In the meanwhile, nanotechnology has also deeply involved in material science research and bioresearch in recent years. The conventional FIB systems which utilize liquid gallium ion sources to achieve nanometer scale resolution can no longer meet the various requirements raised from such a wide application area such as low contamination, high throughput and so on. The drive towards controlling materials properties at nanometer length scales relies on the availability of efficient tools. In this thesis, three novel ion beam tools have been developed and investigated as the alternatives for the conventional FIB systems in some particular applications. An integrated focused ion beam (FIB) and scanning electron microscope (SEM) system has been developed for direct doping or surface modification. This new instrument employs a mini-RF driven plasma source to generate focused ion beam with various ion species, a FEI two-lens electron (2LE) column for SEM imaging, and a five-axis manipulator system for sample positioning. An all-electrostatic two-lens column has been designed to focus the ion beam extracted from the source. Based on the Munro ion optics simulation, beam spot sizes as small as 100 nm can be achieved at beam energies between 5 to 35 keV if a 5 (micro)m-diameter extraction aperture is used. Smaller beam spot sizes can be obtained with smaller apertures at sacrifice of some beam current. The FEI 2LE column, which utilizes Schottky emission, electrostatic focusing optics, and stacked-disk column construction, can provide high-resolution (as small as 20 nm) imaging capability, with fairly long working distance

  11. Relativistic electron beam driven Wake-field excitation in a cold magnetized plasma

    International Nuclear Information System (INIS)

    Excitation of nonlinear Wake-fields by an intense, short, ultra relativistic electron beam in a cold, magnetized plasma is studied analytically, in the electrostatic limit, following the method discussed. From the analytical solution of one dimensional fluid equations, together with Maxwell's equations, in the limit of βph (ratio of wave phase velocity and speed of light) ∼ 1, it is found that under certain conditions of beam density to plasma density ratio, a large amplitude accelerating gradient is generated in the beam's wake. Further the structure of the excited Wake field is compared with Akhiezer-Polovin like wave for a magnetized plasma. (author)

  12. Generation of atto-second pulses on relativistic mirror plasma

    International Nuclear Information System (INIS)

    When an ultra intense femtosecond laser (I > 1016 W.cm-2) with high contrast is focused on a solid target, the laser field at focus is high enough to completely ionize the target surface during the rising edge of the laser pulse and form a plasma. This plasma is so dense (the electron density is of the order of hundred times the critical density) that it completely reflects the incident laser beam in the specular direction: this is the so-called 'plasma mirror'. When laser intensity becomes very high, the non-linear response of the plasma mirror to the laser field periodically deforms the incident electric field leading to high harmonic generation in the reflected beam. In the temporal domain this harmonic spectrum is associated to a train of atto-second pulses. The goals of my work were to get a better comprehension of the properties of harmonic beams produced on plasma mirrors and design new methods to control theses properties, notably in order to produce isolated atto-second pulses instead of trains. Initially, we imagined and modeled the first realistic technique to generate isolated atto-second on plasma mirrors. This brand new approach is based on a totally new physical effect: 'the atto-second lighthouse effect'. Its principle consists in sending the atto-second pulses of the train in different directions and selects one of these pulses by putting a slit in the far field. Despite its simplicity, this technique is very general and applies to any high harmonic generation mechanism. Moreover, the atto-second lighthouse effect has many other applications (e.g in metrology). In particular, it paves the way to atto-second pump-probe experiments. Then, we studied the spatial properties of these harmonics, whose control and characterization are crucial if one wants to use this source in future application experiments. For instance, we need to control very precisely the harmonic beam divergence in order to achieve the atto-second lighthouse effect and get isolated

  13. Physical principles of the surface plasma method for producing beams of negative ions

    International Nuclear Information System (INIS)

    The processes which are important for the production of intense beams of negative ions from surface plasma sources (SPS) are examined. The formation of negative ions when atomic particles interact with a surface is analyzed on the basis of both experimental results obtained when a surface was bombarded with beams and recently developed theoretical considerations of reflection, scattering, and electron exchange. The characteristic features of these processes in SPS, when a surface is bombarded with intense fluxes of plasma particles, are revealed in special experiments. The characteristics of generation and acceleration of the bombarding particles in a gas discharge SPS plasma, the characteristics of transportation of negative ions through the plasma toward the beam forming system, the role of cesium in SPS, and the characteristics of formation of the intense negative ion beams as well as the removal of parasite electrons from the beam

  14. Generation of perfect vectorial vortex beams.

    Science.gov (United States)

    Li, Peng; Zhang, Yi; Liu, Sheng; Ma, Chaojie; Han, Lei; Cheng, Huachao; Zhao, Jianlin

    2016-05-15

    We propose the concept of perfect vectorial vortex beams (VVBs), which not merely have intensity profile independent of the polarization order and the topological charge of spiral phase, but also have stable intensity profile and state of polarization (SoP) upon propagation. Utilizing a Sagnac interferometer, we approximately generate perfect VVBs with locally linear and elliptical polarizations, and demonstrate that such beams can keep their intensity profile and SoP at a certain propagation distance. These proposed VVBs can be expanded to encode information and quantum cryptography, as well as to enrich the conversion of spin and orbital angular momenta. PMID:27176963

  15. Acoustic source for generating an acoustic beam

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian

    2016-05-31

    An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.

  16. Transport and Non-Invasive Position Detection of Electron Beams from Laser-Plasma Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Osterhoff, Jens; Sokollik, Thomas; Nakamura, Kei; Bakeman, Michael; Weingartner, R; Gonsalves, Anthony; Shiraishi, Satomi; Lin, Chen; vanTilborg, Jeroen; Geddes, Cameron; Schroeder, Carl; Esarey, Eric; Toth, Csaba; DeSantis, Stefano; Byrd, John; Gruner, F; Leemans, Wim

    2011-07-20

    The controlled imaging and transport of ultra-relativistic electrons from laser-plasma accelerators is of crucial importance to further use of these beams, e.g. in high peak-brightness light sources. We present our plans to realize beam transport with miniature permanent quadrupole magnets from the electron source through our THUNDER undulator. Simulation results demonstrate the importance of beam imaging by investigating the generated XUV-photon flux. In addition, first experimental findings of utilizing cavity-based monitors for non-invasive beam-position measurements in a noisy electromagnetic laser-plasma environment are discussed.

  17. INTERACTION OF MUON BEAM WITH PLASMA DEVELOPED DURING IONIZATION COOLING

    Energy Technology Data Exchange (ETDEWEB)

    S. Ahmed, D. Kaplan, T. Roberts, L. Spentzouris, K. Beard

    2012-07-01

    Particle-in-cell simulations involving the interaction of muon beam (peak density 10{sup 18} m{sup 3}) with Li plasma (ionized medium) of density 10{sup 16}-10{sup 22} m{sup -3} have been performed. This study aimed to understand the effects of plasma on an incoming beam in order to explore scenario developed during the process of ionization cooling. The computer code takes into account the self-consistent electromagnetic effects of beam interacting with plasma. This study shows that the beam can pass through the plasma of densities four order of magnitude higher than its peak density. The low density plasmas are wiped out by the beam, however, the resonance is observed for densities of similar order. Study reveals the signature of plasma wakefield acceleration.

  18. Beam loading in a laser-plasma accelerator using a near-hollow plasma channel

    OpenAIRE

    Schroeder, Carl

    2014-01-01

    Beam loading in laser-plasma accelerators using a near-hollow plasma channel is examined in the linear wake regime. It is shown that, by properly shaping and phasing the witness particle beam, high-gradient acceleration can be achieved with high-efficiency, and without induced energy spread or emittance growth. Both electron and positron beams can be accelerated in this plasma channel geometry. Matched propagation of electron beams can be achieved by the focusing force provided by the chan...

  19. Obtaining of hot electron plasma in two-stage beam-plasma system

    International Nuclear Information System (INIS)

    The space region of plasma formation and heating one are separated by pressure gradient in two-stage beam-plasma system. It is shown, that the temperature of plasma electron most part can reach some hundreds electronvolt when beam of some unit kiloelectronvolt energy is injected in system. The range of basic macroscopic parameters of system (current and energy of beam, operating gas pressure, plasma column length, magnetic field strength) corresponding to electron maximum heating is determined

  20. Fast fall-time ion beam in neutron generators

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Q.; Kwan, J.; Regis, M.; Wu, Y.; Wilde, S.B.; Wallig, J.

    2008-08-10

    Ion beam with a fast fall time is useful in building neutron generators for the application of detecting hidden, gamma-shielded SNM using differential die-away (DDA) technique. Typically a fall time of less than 1 {micro}s can't be achieved by just turning off the power to the ion source due to the slow decay of plasma density (partly determined by the fall time of the RF power in the circuit). In this paper, we discuss the method of using an array of mini-apertures (instead of one large aperture beam) such that gating the beamlets can be done with low voltage and a small gap. This geometry minimizes the problem of voltage breakdown as well as reducing the time of flight to produce fast gating. We have designed and fabricated an array of 16 apertures (4 x 4) for a beam extraction experiment. Using a gating voltage of 1400 V and a gap distance of 1 mm, the fall time of extracted ion beam pulses is less than 1 {micro}s at various beam energies ranging between 400 eV to 800 eV. Usually merging an array of beamlets suffers the loss of beam brightness, i.e., emittance growth, but that is not an important issue for neutron source applications.

  1. Modified quadrupole mass analyzer RGA-100 for beam plasma research in forevacuum pressure range

    Science.gov (United States)

    Zolotukhin, D. B.; Tyunkov, A. V.; Yushkov, Yu. G.; Oks, E. M.

    2015-12-01

    The industrial quadrupole RGA-100 residual gas analyzer was modified for the research of electron beam-generated plasma at forevacuum pressure range. The standard ionizer of the RGA-100 was replaced by three electrode extracting unit. We made the optimization of operation parameters in order to provide the maximum values of measured currents of any ion species. The modified analyzer was successfully tested with beam plasma of argon, nitrogen, oxygen, and hydrocarbons.

  2. Modeling of plasma heating with neutral beam injection in T-11 machine

    International Nuclear Information System (INIS)

    Computations of energy balance are presented for a tokamak with hot atom beam injection. Atom ionization, trapping of generated ions and energy transfer to plasma are examined. Energy loss in charge exchange is considered. Relationships are presented between the temperature and the injection power, the plasma density and other parameters. Possibilities are discussed for obtaining a collisionless ion regime

  3. Beam-generated upper hybrid noise in Jupiter's outer magnetosphere

    International Nuclear Information System (INIS)

    Upper hybrid waves in Jupiter's outer magnetosphere are the subject of this paper which proposes a new theoretical model for their generation. Energetic electrons are assumed to be accelerated in the high-latitude auroral zone and stream away from the planet to the outer magnetosphere. The electrons travel along magnetic field lines located at the edges of the plasma sheet through a region which has the properties of a plasma sheet boundary layer similar to the terrestrial entity. The kinematic evolution of the electron beam results in a highly collimated field-aligned distribution which excites quasi-perpendicular upper hybrid waves through a so-called beam-anisotropic heat flux instability. The instability is dominated by anomalous cyclotron harmonic resonances in a parameter regime where the gyroradius of the beam electrons is comparable to the wavelength of the wave. Propagation of the upper hybrid waves across the magnetic field into a plasma density gradient produces a spectrum of z mode waves which then undergo a linear mode conversion to ordinary mode electromagnetic radiation. The model successfully accounts for the observations of upper hybrid noise, Z mode emissions, and continuum radiation in the Jovian magnetosphere in a self-consistent coherent manner

  4. Ultrashort high quality electron beam from laser wakefield accelerator using two-step plasma density profile

    International Nuclear Information System (INIS)

    In this paper, we first use the rf linac injector mechanism to generate ultrashort high quality electron beam from laser wakefield accelerator (LWFA) with two-step plasma density profile successfully. We incorporate the physics principle in the conventional rf linac injector into the LWFA by using two-step plasma density to decrease the wavelength of the wakefield in plasma. Using this mechanism, we observe a ultrashort high quality electron beam (the rms energy spread is 1.9%, and the rms bunch length is 2 fs) in the simulation. The ultrashort intense terahertz coherent radiation (200 MW, 2 fs) can be generated with the proposed laser wakefield accelerator.

  5. Hollow-Cathode Source Generates Plasma

    Science.gov (United States)

    Deininger, W. D.; Aston, G.; Pless, L. C.

    1989-01-01

    Device generates argon, krypton, or xenon plasma via thermionic emission and electrical discharge within hollow cathode and ejects plasma into surrounding vacuum. Goes from cold start up to full operation in less than 5 s after initial application of power. Exposed to moist air between operations without significant degradation of starting and running characteristics. Plasma generated by electrical discharge in cathode barrel sustained and aided by thermionic emission from emitter tube. Emitter tube does not depend on rare-earth oxides, making it vulnerable to contamination by exposure to atmosphere. Device modified for use as source of plasma in laboratory experiments or industrial processes.

  6. Optical vortex beam generator at nanoscale level.

    Science.gov (United States)

    Garoli, Denis; Zilio, Pierfrancesco; Gorodetski, Yuri; Tantussi, Francesco; De Angelis, Francesco

    2016-01-01

    Optical beams carrying orbital angular momentum (OAM) can find tremendous applications in several fields. In order to apply these particular beams in photonic integrated devices innovative optical elements have been proposed. Here we are interested in the generation of OAM-carrying beams at the nanoscale level. We design and experimentally demonstrate a plasmonic optical vortex emitter, based on a metal-insulator-metal holey plasmonic vortex lens. Our plasmonic element is shown to convert impinging circularly polarized light to an orbital angular momentum state capable of propagating to the far-field. Moreover, the emerging OAM can be externally adjusted by switching the handedness of the incident light polarization. The device has a radius of few micrometers and the OAM beam is generated from subwavelength aperture. The fabrication of integrated arrays of PVLs and the possible simultaneous emission of multiple optical vortices provide an easy way to the large-scale integration of optical vortex emitters for wide-ranging applications. PMID:27404659

  7. Second-harmonic generation with Bessel beams

    Science.gov (United States)

    Shatrovoy, Oleg

    We present the results of a numerical simulation tool for modeling the second-harmonic generation (SHG) interaction experienced by a diffracting beam. This code is used to study the simultaneous frequency and spatial profile conversion of a truncated Bessel beam that closely resembles a higher-order mode (HOM) of an optical fiber. SHG with Bessel beams has been investigated in the past and was determined have limited value because it is less efficient than SHG with a Gaussian beam in the undepleted pump regime. This thesis considers, for the first time to the best of our knowledge, whether most of the power from a Bessel-like beam could be converted into a second-harmonic beam (full depletion), as is the case with a Gaussian beam. We study this problem because using HOMs for fiber lasers and amplifiers allows reduced optical intensities, which mitigates nonlinearities, and is one possible way to increase the available output powers of fiber laser systems. The chief disadvantage of using HOM fiber amplifiers is the spatial profile of the output, but this can be transformed as part of the SHG interaction, most notably to a quasi-Gaussian profile when the phase mismatch meets the noncollinear criteria. We predict, based on numerical simulation, that noncollinear SHG (NC-SHG) can simultaneously perform highly efficient (90%) wavelength conversion from 1064 nm to 532 nm, as well as concurrent mode transformation from a truncated Bessel beam to a Gaussian-like beam (94% overlap with a Gaussian) at modest input powers (250 W, peak power or continuous-wave operation). These simulated results reveal two attractive features -- the feasibility of efficiently converting HOMs of fibers into Gaussian-like beams, and the ability to simultaneously perform frequency conversion. Combining the high powers that are possible with HOM fiber amplifiers with access to non-traditional wavelengths may offer significant advantages over the state of the art for many important applications

  8. Plasma-parameter measurements using neutral-particle-beam attenuation

    International Nuclear Information System (INIS)

    Intense and energetic neutral-particle-beam injection used for fueling or heating magnetically confined, controlled-fusion experimental plasmas can also provide diagnostic measurements of the plasmas. The attenuation of an atomic beam (mainly from charge-exchange and ionization interactions) when passing through a plasma gives the plasma line density. Orthogonal arrays of highly collimated detectors of the secondary-electron-emission type have been used in magnetic-mirror experiments to measure neutral-beam attenuation along chords through the plasma volume at different radial and axial positions. The radial array is used to infer the radial plasma-density profile; the axial array, to infer the axial plasma-density profile and the ion angular distribution at the plasma midplane

  9. Beam-driven, Plasma-based Particle Accelerators

    CERN Document Server

    Muggli, P

    2016-01-01

    We briefly give some of the characteristics of the beam-driven, plasma-based particle accelerator known as the plasma wakefield accelerator (PWFA). We also mention some of the major results that have been obtained since the birth of the concept. We focus on high-energy particle beams where possible.

  10. Structured Beam Generation with a Single Metasurface

    CERN Document Server

    Yue, Fuyong; Xin, Jingtao; Gerardot, Brian; Li, Jensen; Chen, Xianzhong

    2016-01-01

    Despite a plethora of applications ranging from quantum memories to high-resolution lithography, the current technologies to generate vector vortex beams (VVBs) suffer from less efficient energy use, poor resolution, low damage threshold, bulky size and complicated experimental setup, preventing further practical applications. We propose and experimentally demonstrate an approach to generate VVBs with a single metasurface by locally tailoring phase and transverse polarization distribution. This method features the spin-orbit coupling and the superposition of the converted part with an additional phase pickup and the residual part without a phase change. By maintaining the equal components for the converted part and the residual part, the cylindrically polarized vortex beams carrying orbital angular momentum are experimentally demonstrated based on a single metasurface at subwavelength scale. The proposed approach provides unprecedented freedom in engineering the properties of optical waves with the high-effic...

  11. Integrated multi vector vortex beam generator

    CERN Document Server

    Schulz, Sebastian A; Karimi, Ebrahim; Boyd, Robert W

    2013-01-01

    A novel method to generate and manipulate vector vortex beams in an integrated, ring resonator based geometry is proposed. We show numerically that a ring resonator, with an appropriate grating, addressed by a vertically displaced access waveguide emits a complex optical field. The emitted beam possesses a specific polarization topology, and consequently a transverse intensity profile and orbital angular momentum. We propose a combination of several concentric ring resonators, addressed with different bus guides, to generate arbitrary orbital angular momentum qudit states, which could potentially be used for classical and quantum communications. Finally, we demonstrate numerically that this device works as an orbital angular momentum sorter with an average cross-talk of -10 dB between different orbital angular momentum channels.

  12. Experimental generation of amplitude squeezed vector beams

    CERN Document Server

    Chille, Vanessa; Semmler, Marion; Banzer, Peter; Aiello, Andrea; Leuchs, Gerd; Marquardt, Christoph

    2016-01-01

    We present an experimental method for the generation of amplitude squeezed high-order vector beams. The light is modified twice by a spatial light modulator such that the vector beam is created by means of a collinear interferometric technique. A major advantage of this approach is that it avoids systematic losses, which are detrimental as they cause decoherence in continuous-variable quantum systems. The utilisation of a spatial light modulator (SLM) gives the flexibility to switch between arbitrary mode orders. The conversion efficiency with our setup is only limited by the efficiency of the SLM. We show the experimental generation of Laguerre-Gauss (LG) modes with radial indices up to 1 and azimuthal indices up to 3 with complex polarization structures and a quantum noise reduction up to -0.9dB$\\pm$0.1dB. The corresponding polarization structures are studied in detail by measuring the spatial distribution of the Stokes parameters.

  13. Laser-generated plasma by carbon nanoparticles embedded into polyethylene

    Science.gov (United States)

    Torrisi, L.; Ceccio, G.; Cutroneo, M.

    2016-05-01

    Carbon nanoparticles have been embedded into polyethylene at different concentrations by using chemical-physical processes. The synthesized material was characterized in terms of physical modifications concerning the mechanical, compositional and optical properties. Obtained flat targets have been irradiated by Nd:YAG laser at intensities of the order of 1010 W/cm2 in order to generate non-equilibrium plasma in vacuum. The laser-matter interaction produces charge separation effects with consequent acceleration of protons and carbon ions. Plasma was characterized using time-of-flight measurements of the accelerated ions. Applications of the produced targets in order to generate carbon ion beams from laser-generated plasma are presented and discussed.

  14. Ignition Features of Plasma-Beam Discharge in Gas-Discharge Electron Gun Operation

    Directory of Open Access Journals (Sweden)

    Valery A. Tutyk

    2013-01-01

    Full Text Available The current paper presents the results of experimental researches to determine the mode features of plasma-beam discharge (PBD generation by an electron beam injected by a low-vacuum gasdischarge electron gun (LGEG with the cold cathode and hollow anode on the basis of the high-voltage glow discharge and in the range of helium pressure of P ? 10 ÷ 130 Pa. The PBD boundaries and their dependences on parameters of an electron beam are found. The influence of PBD on parameters of low-vacuum gas-discharge electron gun is revealed. It causes an avalanche increase of electron beam current and burning of plasma-beam discharge in the whole space of the vacuum chamber volume and generation of electromagnetic radiation is revealed. Achieved results will be used for implementation of various vacuum technologies in the medium of reaction gas and generated electromagnetic radiation.

  15. 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.

  16. Heating of electron plasma in two-stage beam-plasma system

    International Nuclear Information System (INIS)

    The regions of plasma production in two-stage beam-plasma system is separated from that of plasma heating by a density gradient. The temperature of bulk plasma electrons in this system is shown to reach several hundred electron volts under the injection of electron beam with the energy in the units of kiloelectronvolt. The range of optimal plasma electron heating is determined with respect to basic macroscopic parameters of the system (beam energy and current, pressure of neutral gas, length of a plasma column, strength of a magnetic field)

  17. Light emission from particle beam induced plasma - An overview

    CERN Document Server

    Ulrich, A

    2015-01-01

    Experiments to study the light emission from plasma produced by particle beams are presented. Fundamental aspects in comparison with discharge plasma formation are discussed. It is shown that the formation of excimer molecules is an important process. This paper summarizes various studies of particle beam induced light emission and presents first results of a direct comparison of light emission induced by electron- and ion beam excitation. Both high energy heavy ion beam and low energy electron beam experiments are described and an overview over applications in the form of light sources, lasers, and ionization devices is given.

  18. TEBPP: Theoretical and Experimental study of Beam-Plasma-Physics

    Science.gov (United States)

    Anderson, H. R.; Bernstein, W.; Linson, L. M.; Papadopoulos, K.; Kellogg, P. J.; Szuszczewicz, E. P.; Hallinan, T. J.; Leinbach, H.

    1980-01-01

    The interaction of an electron beam (0 to 10 keV, 0 to 1.5 Amp) with the plasma and neutral atmospheres at 200 to 400 km altitude is studied with emphasis on applications to near Earth and cosmical plasmas. The interaction occurs in four space time regions: (1) near electron gun, beam coming into equilibrium with medium; (2) equilibrium propagation in ionosphere; (3) ahead of beam pulse, temporal and spatial precursors; (4) behind a beam pulse. While region 2 is of the greatest interest, it is essential to study Region 1 because it determines the characteristics of the beam as it enters 2 through 4.

  19. Neutral Beam Current Drive in Spheromak plasma and plasma stability

    Science.gov (United States)

    Pearlstein, L. D.; Jayakumar, R. J.; Hudson, B.; Hill, D. N.; Lodestro, L. L.; McLean, H. S.; Fowler, T. K.; Casper, T. A.

    2007-11-01

    A key question for the Sustained Spheromak Physics Experiment (SSPX) is understanding how spheromaks can be sustained by other current drive tools such as neutral beam current drive. Another question is whether the present relationship between current and maximum spheromak magnetic field (plasma beta) is related to Alcator-like ohmic confinement limit or is a stability limit. Using the code CORSICA, the fraction of neutral beam current drive that can be achieved has been calculated for different injection angles with a fixed equilibrium. It is seen that relaxing the equilibrium with this drive simply drives the core safety factor to low values. Other equilibria where the NBI may give aligned current drive are being explored. Free-boundary equilibria calculations are underway to see what hyper-resistivity model gives the observed sustained SSPX performance and include that in the NBI calculations. Work performed under the auspices of the US DOE by University of California Lawrence Livermore National Laboratory under contract W-7405-ENG-48.

  20. 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.

  1. Study of electron beam production by a plasma focus

    International Nuclear Information System (INIS)

    A preliminary investigation of the electron beam produced by a plasma focus device using a current charged transmission line is described. Electron beam currents as high as 10 kA were measured. Interaction of the extracted beam and the filling gas was studied using open shutter photography

  2. Plasma generation induced by triboelectrification

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Michelsen, Poul

    2009-01-01

    A gas discharge plasma can be induced by triboelectrification around a sliding contact. The detailed physical mechanism of triboelectrification is unknown, but an empirical classification scheme can be referred to in practice. It is reported that intense ultra-violet emission from a plasma is...... observed adjacent to the sliding contact, of which the location has a gap ranging from approximately 1 μm to 11 μm. When the gap is short enough, a theory predicts that the breakdown voltage can monotonically decrease with a decrease in the gap. However, when the gap is comparable to electron’s mean free...

  3. Physics of beam self-modulation in plasma wakefield accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Lotov, K. V. [Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation)

    2015-10-15

    The self-modulation instability is a key effect that makes possible the usage of nowadays proton beams as drivers for plasma wakefield acceleration. Development of the instability in uniform plasmas and in plasmas with a small density up-step is numerically studied with the focus at nonlinear stages of beam evolution. The step parameters providing the strongest established wakefield are found, and the mechanism of stable bunch train formation is identified.

  4. Radio frequency induction plasma generator 80-kV test stand operation

    International Nuclear Information System (INIS)

    Beam extraction tests at energies up to 80 kV were performed using a radio frequency induction (RFI) plasma generator hydrogen ion source. A 7 x 10-cm2, long pulse accelerator was operated with a 10 x 10-cm2 axial magnetic cusp bucket and a magnetic-filter bucket. Atomic fractions (up to 85% H+), plasma production efficiencies (roughly-equal0.6 A of beam per kW rf power), and beam divergence were at least as good as with arc plasmas in similar chambers. Potential advantages of the RFI plasma sources for large-scale applications are ease of operation, reliability, and extended service life

  5. Magnetic field generation during intense laser channelling in underdense plasma

    Science.gov (United States)

    Smyth, A. G.; Sarri, G.; Vranic, M.; Amano, Y.; Doria, D.; Guillaume, E.; Habara, H.; Heathcote, R.; Hicks, G.; Najmudin, Z.; Nakamura, H.; Norreys, P. A.; Kar, S.; Silva, L. O.; Tanaka, K. A.; Vieira, J.; Borghesi, M.

    2016-06-01

    Channel formation during the propagation of a high-energy (120 J) and long duration (30 ps) laser pulse through an underdense deuterium plasma has been spatially and temporally resolved via means of a proton imaging technique, with intrinsic resolutions of a few μm and a few ps, respectively. Conclusive proof is provided that strong azimuthally symmetric magnetic fields with a strength of around 0.5 MG are created inside the channel, consistent with the generation of a collimated beam of relativistic electrons. The inferred electron beam characteristics may have implications for the cone-free fast-ignition scheme of inertial confinement fusion.

  6. Numerical simulation of nonlinear processes in a beam-plasma system

    Energy Technology Data Exchange (ETDEWEB)

    Efimova, A. A., E-mail: anna.an.efimova@gmail.com; Berendeev, E. A.; Vshivkov, V. A. [Institute of Computational Mathematics and Mathematical Geophysics SB RAS 6 Acad. Lavrentyev Ave., Novosibirsk 630090 (Russian Federation); Dudnikova, G. I. [University of Maryland, College Park, MD 20742 (United States); Institute of Computational Technologies SB RAS, 6 Acad. Lavrentyev Ave., Novosibirsk 630090 (Russian Federation)

    2015-10-28

    In the present paper we consider the efficiency of the electromagnetic radiation generation due to various nonlinear processes in the beam-plasma system. The beam and plasma parameters were chosen close to the parameters in the experiment on the GOL-3 facility (BINP SB RAS). The model of the collisionless plasma is described by system of the Vlasov-Maxwell equations with periodic boundary conditions. The parallel numerical algorithm is based on the particles-in-cell method (PIC) with mixed Euler-Lagrangian domain decomposition. Various scenarios of nonlinear evolution in the beam-plasma system under the influence of an external magnetic field in case of a low density beam were studied. The energy transfer from one unstable mode to the others modes was observed.

  7. Numerical simulation of nonlinear processes in a beam-plasma system

    International Nuclear Information System (INIS)

    In the present paper we consider the efficiency of the electromagnetic radiation generation due to various nonlinear processes in the beam-plasma system. The beam and plasma parameters were chosen close to the parameters in the experiment on the GOL-3 facility (BINP SB RAS). The model of the collisionless plasma is described by system of the Vlasov-Maxwell equations with periodic boundary conditions. The parallel numerical algorithm is based on the particles-in-cell method (PIC) with mixed Euler-Lagrangian domain decomposition. Various scenarios of nonlinear evolution in the beam-plasma system under the influence of an external magnetic field in case of a low density beam were studied. The energy transfer from one unstable mode to the others modes was observed

  8. Proton beam generation of oblique whistler waves

    Science.gov (United States)

    Wong, H. K.; Goldstein, M. L.

    1988-01-01

    It is known that ion beams are capable of generating whistler waves that propagate parallel to the mean magnetic field. Such waves may have been observed both upstream of the earth's bow shock and in the vicinity of comets. Previous analyses are extended to include propagation oblique to the mean magnetic field. The instability is generated by the perpendicular component of free energy in the ions, which can arise either via a temperature anisotropy or via a gyrating distribution. In the former case, the generation of whistler waves is confined to a fairly narrow cone of propagation directions centered about parallel propagation; in the latter case, the maximum growth of the instability can occur at fairly large obliquities (theta equal to about 50 deg).

  9. Intense ion beams from laser plasma : production and application

    International Nuclear Information System (INIS)

    The production of intense ion beams from plasma injectors using laser-induced plasma bundles are considered. Laser plasma bundles with quantity of ions about 10 sup 1 sup 5 - 10 sup 1 sup 6 imp sup -1 are created by interaction of laser irradiation ( q = 10 sup 9 - 10 sup 1 sup 3 W / cm sup 2, less than 'thermonuclear' intensities, lambda - 0.53 - 10.6 micro, E 0.1 - 10 J/ imp )with various solid targets in vacuum. By changing laser parameters and focusing conditions it is able to produce ions from very wide spectrum of chemical elements and of different charge. High density moving plasma gives the possibility to extract and to form in time up to 1 - 3 microsecond ion current equal 10-10 sup 3 A. Some types of such injector for radiation physics arrangements were elaborated. The main goals of the application of these equipment are the following : - acceleration of multiply charged ions in big accelerators; - ion implantation and material modification; - generation of intense pulse neutron fluxes; - vaporization of material and special layers creation. 4 refs., (author)

  10. Tracing the plasma interactions for pulsed reactive crossed-beam laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jikun; Stender, Dieter; Pichler, Markus; Pergolesi, Daniele; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas, E-mail: thomas.lippert@psi.ch [General Energy Research Department, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Döbeli, Max [Ion Beam Physics, ETH Zurich, CH-8093 Zurich (Switzerland)

    2015-10-28

    Pulsed reactive crossed-beam laser ablation is an effective technique to govern the chemical activity of plasma species and background molecules during pulsed laser deposition. Instead of using a constant background pressure, a gas pulse with a reactive gas, synchronized with the laser beam, is injected into vacuum or a low background pressure near the ablated area of the target. It intercepts the initially generated plasma plume, thereby enhancing the physicochemical interactions between the gaseous environment and the plasma species. For this study, kinetic energy resolved mass-spectrometry and time-resolved plasma imaging were used to study the physicochemical processes occurring during the reactive crossed beam laser ablation of a partially {sup 18}O substituted La{sub 0.6}Sr{sub 0.4}MnO{sub 3} target using oxygen as gas pulse. The characteristics of the ablated plasma are compared with those observed during pulsed laser deposition in different oxygen background pressures.

  11. Tracing the plasma interactions for pulsed reactive crossed-beam laser ablation

    International Nuclear Information System (INIS)

    Pulsed reactive crossed-beam laser ablation is an effective technique to govern the chemical activity of plasma species and background molecules during pulsed laser deposition. Instead of using a constant background pressure, a gas pulse with a reactive gas, synchronized with the laser beam, is injected into vacuum or a low background pressure near the ablated area of the target. It intercepts the initially generated plasma plume, thereby enhancing the physicochemical interactions between the gaseous environment and the plasma species. For this study, kinetic energy resolved mass-spectrometry and time-resolved plasma imaging were used to study the physicochemical processes occurring during the reactive crossed beam laser ablation of a partially 18O substituted La0.6Sr0.4MnO3 target using oxygen as gas pulse. The characteristics of the ablated plasma are compared with those observed during pulsed laser deposition in different oxygen background pressures

  12. Investigation and applications of a plasma generator

    International Nuclear Information System (INIS)

    This work describes the experimental study of a plasma generator: a cylindrical or parallelepipedic rectangle cathode. A permanent magnet creates an axial magnetic field of a few hundred Gauss. A cold and abnormal glow discharge plasma is obtained. The experimental research on the correlation between the discharge parameters (electrode geometry, gas pressure, discharge voltage and current, magnetic field) of the discharge is presented. Another part of the text mentions some generator applications to surface treatment: evaporation, sputtering, surface modification of polymers by exposure to plasma. (author)

  13. Generation of radiation by intense plasma and electromagnetic undulators

    International Nuclear Information System (INIS)

    We examine the characteristics of the classical radiation emission resulting from the interaction of a relativistic electron beam that propagates perpendicularly through a large amplitude relativistic plasma wave. Such a study is useful for evaluating the feasibility of using relativistic plasma waves as extremely short wavelength undulators for generating short wavelength radiation. The electron trajectories in a plasma wave undulator and in an ac FEL undulator are obtained using perturbation techniques. The spontaneous radiation frequency spectrum and angular distribution emitted by a single electron oscillating in these two undulators are then calculated. The radiation gain of a copropagating electromagnetic wave is calculated. The approximate analytic results for the trajectories, spontaneous radiation and gain are compared with 3-D simulation results. The characteristics of the plasma wave undulator are compared with the ac FEL undulator and linearly polarized magnetic undulator. 50 refs., 26 figs., 3 tabs

  14. Stopping Power for Strong Beam-Plasma Coupling

    Science.gov (United States)

    Gericke, Dirk O.

    2001-10-01

    The slowing down process of charged particles in plasma targets is investigated for the case of strong beam-plasma coupling. Strong beam-plasma correlations can be considered using the collision operator of the quantum Boltzmann equation. As a first step, dynamic screening is included in the first Born approximation. This approach gives good results for moderate beam-plasma coupling (Zb Γ^3/2 Bethe-formula, the standard model of the stopping power (Bethe plus Bloch corrections and Barkas terms), the Li & Petrasso formula and simulation data (MD and PIC), is given. This comparison clearly shows the advantage of the proposed model: it smoothly interpolates between the classical low velocity regime, where strong coupling effects occur, and the high velocity quantum regime, where collective modes are important. In the latter case, the experimentally proven Bethe-formula is obtained. Furthermore, it matches the simulation data for moderate as well as strong beam-plasma coupling.

  15. Laser ion source: A direct plasma injection scheme for two-beam type interdigital-H radio frequency quadrupole linac

    International Nuclear Information System (INIS)

    We developed a laser ion source using a direct plasma injection scheme (DPIS) as an injection system for a two-beam type radio frequency quadrupole (RFQ) linac with an interdigital-H (IH) type cavity. The laser ion source in the DPIS is directly connected to the RFQ cavity without the low energy beam transport system. We achieved a high current C2+ beam above 60 mA per beam channel from the ion source. The beam will be injected to the two-beam type IH-RFQ linac, and the linac will generate a beam current of approximately 44 mA per beam channel.

  16. Beam Matching to a Plasma Wakefield Accelerator Using a Ramped Density Profile at the Plasma Boundary

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, K.A.; Clayton, C.E.; Huang, C.; Johnson, D.K.; Joshi, C.; Lu, W.; Mori, W.B.; Zhou, M.; /UCLA; Barnes, C.D.; Decker, F.J.; Hogan, M.J.; Iverson, R.H.; Krejcik, P.; O' Connell, C.L.; Siemann, R.; Walz, D.R.; /SLAC; Deng, S.; Katsouleas, T.C.; Muggli, P.; Oz, E.; /Southern California U.

    2006-02-17

    An important aspect of plasma wake field accelerators (PWFA) is stable propagation of the drive beam. In the under dense plasma regime, the drive beam creates an ion channel which acts on the beam as a strong thick focusing lens. The ion channel causes the beam to undergo multiple betatron oscillations along the length of the plasma. There are several advantages if the beam size can be matched to a constant radius. First, simulations have shown that instabilities such as hosing are reduced when the beam is matched [1]. Second, synchrotron radiation losses are minimized when the beam is matched. Third, an initially matched beam will propagate with no significant change in beam size in spite of large energy loss or gain. Coupling to the plasma with a matched radius can be difficult in some cases. This paper shows how an appropriate density ramp at the plasma entrance can be useful for achieving a matched beam. Additionally, the density ramp is helpful in bringing a misaligned trailing beam onto the drive beam axis. A plasma source with boundary profiles useful for matching has been created for the E-164X PWFA experiments at SLAC.

  17. Experimental investigation of a 1 kA/cm2 sheet beam plasma cathode electron gun

    International Nuclear Information System (INIS)

    In this paper, a cold cathode based sheet-beam plasma cathode electron gun is reported with achieved sheet-beam current density ∼1 kA/cm2 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

  18. Experimental investigation of a 1 kA/cm2 sheet beam plasma cathode electron gun

    Science.gov (United States)

    Kumar, Niraj; Narayan Pal, Udit; Kumar Pal, Dharmendra; 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/cm2 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.

  19. 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. PMID:25638082

  20. Workshop on the use of atomic beams in plasma experiments

    International Nuclear Information System (INIS)

    The material of the workshop entitled 'Use of Atomic Beams in Plasma Experiments', which was organized to summarize the results of the joint research and to give an outlook to the future trends of development in the field is presented. Different topics on plasma diagnostics, plasma impurities, impurity injection, transport theory in plasma and their use in tokamak devices are covered. 18 items are separately indexed for INIS database. (K.A.)

  1. Objective specific beam generation for image guided robotic radiosurgery

    International Nuclear Information System (INIS)

    Robotic radiosurgery enables precise dose delivery throughout the body. Planning for robotic radiosurgery comprises of finding a suitable set of beams and beam weights. The problem can be addressed by generating a large set of candidate beams, and selection of beams with nonzero weight by mathematical programming. We propose to use different randomized beam generation methods depending on the type of lesion and the clinical objective. Results for three patient cases indicate that this can improve the plan quality. (orig.)

  2. Study on electron beam in a low energy plasma focus

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Muhammad Zubair, E-mail: mzubairkhan-um76@yahoo.com [Plasma Technology Research Center, Department of Physics, Faculty of Science, University Malaya, 50603 Kuala Lumpur, Malaysia and Department of Physics, Federal Urdu University of Arts, Science and Technology, 45320 Islamabad (Pakistan); Ling, Yap Seong; San, Wong Chiow [Plasma Technology Research Center, Department of Physics, Faculty of Science, University Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-03-05

    Electron beam emission was investigated in a low energy plasma focus device (2.2 kJ) using copper hollow anode. Faraday cup was used to estimate the energy of the electron beam. XR100CR X-ray spectrometer was used to explore the impact of the electron beam on the target observed from top-on and side-on position. Experiments were carried out at optimized pressure of argon gas. The impact of electron beam is exceptionally notable with two different approaches using lead target inside hollow anode in our plasma focus device.

  3. Study on electron beam in a low energy plasma focus

    International Nuclear Information System (INIS)

    Electron beam emission was investigated in a low energy plasma focus device (2.2 kJ) using copper hollow anode. Faraday cup was used to estimate the energy of the electron beam. XR100CR X-ray spectrometer was used to explore the impact of the electron beam on the target observed from top-on and side-on position. Experiments were carried out at optimized pressure of argon gas. The impact of electron beam is exceptionally notable with two different approaches using lead target inside hollow anode in our plasma focus device

  4. A Space-Charge-Neutralizing Plasma for Beam Drift Compression

    Energy Technology Data Exchange (ETDEWEB)

    Roy, P.K.; Seidl, P.A.; Anders, A.; Bieniosek, F.M.; Coleman, J.E.; Gilson, E.P.; Greenway, W.; Grote, D.P.; Jung, J.Y.; Leitner, M.; Lidia, S.M.; Logan, B.G.; Sefkow, A.B.; Waldron, W.L.; Welch, D.R.

    2008-08-01

    Simultaneous radial focusing and longitudinal compression of intense ion beams are being studied to heat matter to the warm dense matter, or strongly coupled plasma regime. Higher compression ratios can be achieved if the beam compression takes place in a plasma-filled drift region in which the space-charge forces of the ion beam are neutralized. Recently, a system of four cathodic arc plasma sources has been fabricated and the axial plasma density has been measured. A movable plasma probe array has been developed to measure the radial and axial plasma distribution inside and outside of a {approx} 10 cm long final focus solenoid (FFS). Measured data show that the plasma forms a thin column of diameter {approx} 5 mm along the solenoid axis when the FFS is powered with an 8T field. Measured plasma density of {ge} 1 x 10{sup 13} cm{sup -3} meets the challenge of n{sub p}/Zn{sub b} > 1, where n{sub p} and n{sub b} are the plasma and ion beam density, respectively, and Z is the mean ion charge state of the plasma ions.

  5. Power supply controlled for plasma torch generation

    International Nuclear Information System (INIS)

    The high density of energy furnished by thermal plasma is profited in a wide range of applications, such as those related with welding fusion, spray coating and at the present in waste destruction. The waste destruction by plasma is a very attractive process because the remaining products are formed by inert glassy grains and non-toxic gases. The main characteristics of thermal plasmas are presented in this work. Techniques based on power electronics are utilized to achieve a good performance in thermal plasma generation. This work shown the design and construction of three phase control system for electric supply of thermal plasma torch, with 250 kw of capacity, as a part of the project named 'Destruction of hazard wastes by thermal plasma' actually working in the Instituto Nacional de Investigaciones Nucleares (ININ). The characteristics of thermal plasma and its generation are treated in the first chapter. The A C controllers by thyristors applied in three phase arrays are described in the chapter II, talking into account the power transformer, rectifiers bank and aliasing coil. The chapter III is dedicated in the design of the trigger module which controls the plasma current by varying the trigger angle of the SCR's; the protection and isolating unit are also presented in this chapter. The results and conclusions are discussed in chapter IV. (Author)

  6. Intense ion beam produced plasmas on TIT-RFQ linac

    International Nuclear Information System (INIS)

    Intense ion beams from an RFQ linac can be used to investigate the plasma experiments. At present, a 4He+ beam with the mean current of 2 mA in a macropulse is focused to about 1.1 mm2 on the target surface. The output-beam is switched from a beam dump to the target within 50 ns by using a fast electrostatic beam kicker. This kicker synchronizes to the RF-pulse, and it is used to control the timing between the beam-target interaction and the diagnostic equipment. The experiments were performed with a gas target. The behavior of the ion beam-produced plasma was observed. (orig.)

  7. An RF excited plasma cathode electron beam gun design

    OpenAIRE

    Del Pozo, S.; Ribton, C; Smith, DR

    2014-01-01

    A plasma cathode electron beam (EB) gun is presented in this work. A radio frequency (RF) excited plasma at 84 MHz was used as the electron source to produce a beam power of up to 3.2 kW at -60 kV accelerating voltage. The pressure in the plasma chamber is approximately 1 mbar. The electrons are extracted from the plasma chamber to the vacuum chamber (at 10-5 mbar) through a diaphragm with a 0.5 mm diameter nozzle. Advantages over thermionic cathode guns were demonstrated empirically. Mainten...

  8. 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

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

    International Nuclear Information System (INIS)

    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

  10. On neutral-beam injection counter to the plasma current

    Science.gov (United States)

    Helander, P.; Akers, R. J.; Eriksson, L.-G.

    2005-11-01

    It is well known that when neutral beams inject ions into trapped orbits in a tokamak, the transfer of momentum between the beam and the plasma occurs through the torque exerted by a radial return current. It is shown that this implies that the angular momentum transferred to the plasma can be larger than the angular momentum of the beam, if the injection is in the opposite direction to the plasma current and the beam ions suffer orbit losses. On the Mega-Ampere Spherical Tokamak (MAST) [R. J. Akers, J. W. Ahn, G. Y. Antar, L. C. Appel, D. Applegate, C. Brickley et al., Plasma Phys. Controlled Fusion 45, A175 (2003)], this results in up to 30% larger momentum deposition with counterinjection than with co-injection, with substantially increased plasma rotation as a result. It is also shown that heating of the plasma (most probably of the ions) can occur even when the beam ions are lost before they have had time to slow down in the plasma. This is the dominant heating mechanism in the outer 40% of the MAST plasma during counterinjection.

  11. New electron beam facility for irradiated plasma facing materials testing in hot cell

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, N.; Kawamura, H. [Oarai Research Establishment, Ibaraki-ken (Japan); Akiba, M. [Naka Research Establishment, Ibaraki-ken (Japan)

    1995-09-01

    Since plasma facing components such as the first wall and the divertor for the next step fusion reactors are exposed to high heat loads and high energy neutron flux generated by the plasma, it is urgent to develop of plasma facing components which can resist these. Then, we have established electron beam heat facility ({open_quotes}OHBIS{close_quotes}, Oarai Hot-cell electron Beam Irradiating System) at a hot cell in JMTR (Japan Materials Testing Reactor) hot laboratory in order to estimate thermal shock resistivity of plasma facing materials and heat removal capabilities of divertor elements under steady state heating. In this facility, irradiated plasma facing materials (beryllium, carbon based materials and so on) and divertor elements can be treated. This facility consists of an electron beam unit with the maximum beam power of 50kW and the vacuum vessel. The acceleration voltage and the maximum beam current are 30kV (constant) and 1.7A, respectively. The loading time of electron beam is more than 0.1ms. The shape of vacuum vessel is cylindrical, and the mainly dimensions are 500mm in inner diameter, 1000mm in height. The ultimate vacuum of this vessel is 1 x 10{sup -4}Pa. At present, the facility for thermal shock test has been established in a hot cell. And performance estimation on the electron beam is being conducted. Presently, the devices for heat loading tests under steady state will be added to this facility.

  12. Refraction of $e^-$ beams due to plasma lensing at a plasma-vacuum interface -- applied to beam deflection in a Copper cell with electrical RF-breakdown plasma

    CERN Document Server

    Sahai, Aakash A

    2014-01-01

    We formulate a possible description of the deflection of a relativistic $e^-$ beam in an inhomogeneous copper plasma, encountered by the beam when propagating through a accelerating cell that has undergone a high electric-field RF-breakdown. It is well known that an inhomogeneous plasma forms and may last for up to a few micro-seconds, until recombination in an accelerating structure where a field-emission triggers melting and ionization of RF-cell wall deformity. We present a preliminary model for the beam deflection due to collective plasma response based upon the beam density, plasma density and interaction length.

  13. Editorial: Focus on Laser- and Beam-Driven Plasma Accelerators

    Science.gov (United States)

    Joshi, Chan; Malka, Victor

    2010-04-01

    The ability of short but intense laser pulses to generate high-energy electrons and ions from gaseous and solid targets has been well known since the early days of the laser fusion program. However, during the past decade there has been an explosion of experimental and theoretical activity in this area of laser-matter interaction, driven by the prospect of realizing table-top plasma accelerators for research, medical and industrial uses, and also relatively small and inexpensive plasma accelerators for high-energy physics at the frontier of particle physics. In this focus issue on laser- and beam-driven plasma accelerators, the latest advances in this field are described. Focus on Laser- and Beam-Driven Plasma Accelerators Contents Slow wave plasma structures for direct electron acceleration B D Layer, J P Palastro, A G York, T M Antonsen and H M Milchberg Cold injection for electron wakefield acceleration X Davoine, A Beck, A Lifschitz, V Malka and E Lefebvre Enhanced proton flux in the MeV range by defocused laser irradiation J S Green, D C Carroll, C Brenner, B Dromey, P S Foster, S Kar, Y T Li, K Markey, P McKenna, D Neely, A P L Robinson, M J V Streeter, M Tolley, C-G Wahlström, M H Xu and M Zepf Dose-dependent biological damage of tumour cells by laser-accelerated proton beams S D Kraft, C Richter, K Zeil, M Baumann, E Beyreuther, S Bock, M Bussmann, T E Cowan, Y Dammene, W Enghardt, U Helbig, L Karsch, T Kluge, L Laschinsky, E Lessmann, J Metzkes, D Naumburger, R Sauerbrey, M. Scḧrer, M Sobiella, J Woithe, U Schramm and J Pawelke The optimum plasma density for plasma wakefield excitation in the blowout regime W Lu, W An, M Zhou, C Joshi, C Huang and W B Mori Plasma wakefield acceleration experiments at FACET M J Hogan, T O Raubenheimer, A Seryi, P Muggli, T Katsouleas, C Huang, W Lu, W An, K A Marsh, W B Mori, C E Clayton and C Joshi Electron trapping and acceleration on a downward density ramp: a two-stage approach R M G M Trines, R Bingham, Z Najmudin

  14. Optical generation of non-diffracting beams via photorefractive holography

    CERN Document Server

    Vieira, Tarcio A; Gesualdi, Marcos R R; Zamboni-Rached, Michel

    2015-01-01

    This work presents, for the first time the optical generation of non-diffracting beams via photorefractive holography. Optical generation of non-diffracting beams using conventional optics components is difficult and, in some instances, unfeasible, as it is wave fields given by superposition of non-diffracting beams. It is known that computer generated holograms and spatial light modulators (SLMs) successfully generate such beams. With photorefractive holography technique, the hologram of a non-diffracting beam is constructed (recorded) and reconstructed (reading) optically in a nonlinear photorefractive medium. The experimental realization of a non-diffracting beam was made in a photorefractive holography setup using a photorefractive Bi12SiO20 (BSO) crystal as the holographic recording medium, where the non-diffracting beams, the Bessel beam arrays and superposition of co-propagating Bessel beams (Frozen Waves) were obtained experimentally. The experimental results are in agreement with the theoretically pr...

  15. Nonlinear stabilization of an electron beam instability in a plasma with high level of sound turbulence

    International Nuclear Information System (INIS)

    Investigated is the stabilization of an electron beam instability due to the process of nonlinear conversion of the Langmuir oscillations into ion-acoustic ones at scattering on plasma electrons. The scheme of an experimental installation is presented. Magnetic field of a mirror configuration has been developed by a system of coils. Field strength in the centre of the magnetic mirror amounts 2 kOe, strength in the mirrors being 8 kOe. The parameters of the electron beam are as follows: current of 10 A, energy of 40 keV, diameter of the beam in the magnetic mirror centre of 2.0 cm. Plasma injector of a hydride-titanium type has been placed in the region of the magnetic mirror. A hydrogen plasma jet with the mean concentration of (5-7)x1012cm-3 has been injected. Observed is the effect of beam stabilization in a turbulent plasma of a direct discharge, in a multi-flow plasma formed at the injector operation in a periodical regime, and with the highest efficiency at the oncoming injection of two plasma bunches. It is noted that, as far as the generation of a high level of sound turbulence does not exhibit any technological difficulties, the results obtained are noteworthy for the problem on beam transport in a plasma

  16. Observations of underdense plasma lens focusing of relativistic electron beams

    International Nuclear Information System (INIS)

    Focusing of a 15 MeV, 19 nC electron bunch by an underdense plasma lens operated just beyond the threshold of the underdense condition has been demonstrated in experiments at the Fermilab NICADD Photoinjector Laboratory (FNPL). The strong 1.9 cm focal-length plasma-lens focused both transverse directions simultaneously and reduced the minimum area of the beam spot by a factor of 23. Analysis of the beam-envelope evolution observed near the beam waist shows that the spherical aberrations of this underdense lens are lower than those of an overdense plasma lens, as predicted by theory. Correlations between the beam charge and the properties of the beam focus corroborate this conclusion

  17. Harmonic generation from indium-rich plasmas

    International Nuclear Information System (INIS)

    An experimental study of high-order harmonic generation in In, InSb, InP, and InGaP plasmas using femtosecond laser radiation with variable chirp is presented. Intensity enhancement of the 13th and 21st harmonics compared to the neighboring harmonics by a factor of 200 and 10, respectively, is observed. It is shown that the harmonic spectrum from indium-containing plasma plumes can be considerably modified by controlling the chirp of the driving laser pulse

  18. Optical trapping with Bessel beams generated from semiconductor lasers

    International Nuclear Information System (INIS)

    In this paper, we study generation of Bessel beams from semiconductor lasers with high beam propagation parameter M2 and their utilization for optical trapping and manipulation of microscopic particles including living cells. The demonstrated optical tweezing with diodegenerated Bessel beams paves the way to replace their vibronic-generated counterparts for a range of applications towards novel lab-on-a-chip configurations

  19. Two-Dimensional Hybrid Model for High-Current Electron Beam Transport in a Dense Plasma

    Institute of Scientific and Technical Information of China (English)

    CAO Lihua; WANG Huan; ZHANG Hua; LIU Zhanjun; WU Junfeng; LI Baiwen

    2014-01-01

    A two-dimensional hybrid code is developed to model the transport of a high-current electron beam in a dense plasma target.The beam electrons are treated as particles and described by particle-in-cell simulation including collisions with the target plasma particles.The background target plasma is assumed to be a stationary fluid with temperature variations.The return current and the self-generated electric and magnetic fields are obtained by combining Ampère's law without the displacement current,the resistive Ohm's law and Faraday's law.The equations are solved in two-dimensional cylindrical geometry with rotational symmetry on a regular grid,with centered spatial differencing and first-order implicit time differencing.The algorithms implemented in the code are described,and a numerical experiment is performed for an electron beam with Maxwellian distribution ejected into a uniform deuterium-tritium plasma target.

  20. High-current runaway electron beam in a tokamak plasma

    International Nuclear Information System (INIS)

    An equilibrium of toroidal plasma with a large electron-beam current has been realized using the runaway effect in a tokamak. Reproducible runaway-mode discharges are obtained with pure hydrogen gas by the help of intense titanium flashing which results in a low electron density. The beam current is estimated to be more than a half of the total toroidal current. The equilibrium of this discharge is maintained by a strong vertical field because the beam pressure gives rise to an additional increase in Shafranov Λ. The beam pressure is estimated to be more than 80% of the total pressure. The kinetic energy and the spatial distributions of beam electrons are studied by seeing X-ray emission from a tungsten wire inserted into the plasma. The increase of Shafranov Λ due to beam pressure is enhanced by puffing gas into the discharge. (author)

  1. Faraday Cup Measurements of Ions Backstreaming into a Electron Beam Impinging on a Plasma Plume

    CERN Document Server

    Guethlein, G; McCarrick, J F; Sampayan, S E

    2000-01-01

    The next generation of radiographic machines based on induction accelerators is expected to generate multiple, small diameter x-ray spots of high intensity. Experiments to study the interaction of the electron beam with plasmas generated at the x-ray converter and at beamline septa are being performed at the Lawrence Livermore National Laboratory (LLNL) using the 6-MeV, 2-kA Experimental Test Accelerator (ETA) electron beam. The physics issues of concern can be separated into two categories. The interaction of subsequent beam pulses with the expanding plasma plume generated by earlier pulses striking the x-ray converter or a septum, and the more subtle effect involving the extraction of light ions from a plasma by the head of the beam pulse. These light ions may be due to contaminants on the surface of the beam pipe or converter, or, for subsequent pulses, in the material of the converter. The space charge depression of the beam could accelerate the light ions to velocities of several mm/ns. As the ions moved...

  2. Dense monoenergetic proton beams from chirped laser-plasma interaction

    CERN Document Server

    Galow, Benjamin J; Liseykina, Tatyana V; Harman, Zoltan; Keitel, Christoph H

    2011-01-01

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen plasma cell is studied analytically and by means of particle-in-cell simulations, respectively. Feasibility of generating ultra-intense (10^7 particles per bunch) and phase-space collimated beams of protons (energy spread of about 1 %) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 10^21 W/cm^2.

  3. Resonant terahertz radiation from warm collisional inhomogeneous plasma irradiated by two Gaussian laser beams

    Science.gov (United States)

    Niknam, A. R.; Banjafar, M. R.; Jahangiri, F.; Barzegar, S.; Massudi, R.

    2016-05-01

    Terahertz (THz) radiation generation by the interaction of two co-propagating high intensity laser beams with a warm collisional inhomogeneous plasma is analytically investigated. By presenting the dielectric permittivity of plasma and taking into account the ponderomotive force, the nonlinear current at THz frequency is obtained. A secondary resonant enhancement of THz radiation is observed, in addition to that occurs at the plasma frequency, which can be tuned by plasma density and temperature. Moreover, we show that for each beat frequency, there exists an optimum temperature at which THz radiation is maximized. It is also shown that the power and efficiency of THz radiation decrease by increasing the collision frequency.

  4. Dense Metal Plasma in a Solenoid for Ion Beam Neutralization

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre; Kauffeldt, Marina; Oks, Efim M.; Roy, Prabir K.

    2010-10-30

    Space-charge neutralization is required to compress and focus a pulsed, high-current ion beam on a target for warm dense matter physics or heavy ion fusion experiments. We described approaches to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary space-charge compensating electrons. Among the options are plasma injection from pulsed vacuum arc sources located outside the solenoid, and using a high current (> 4 kA) pulsed vacuum arc plasma from a ring cathode near the edge of the solenoid. The plasma distribution is characterized by photographic means, by an array of movable Langmuir probes, by a small single probe, and by evaluating Stark broadening of the Balmer H beta spectral line. In the main approach described here, the plasma is produced at several cathode spots distributed azimuthally on the ring cathode. It is shown that the plasma is essentially hollow, as determined by the structure of the magnetic field, though the plasma density exceeds 1014 cm-3 in practically all zones of the solenoid volume if the ring electrode is placed a few centimeters off the center of the solenoid. The plasma is non-uniform and fluctuating, however, since its density exceeds the ion beam density it is believed that this approach could provide a practical solution to the space charge neutralization challenge.

  5. Control of power characteristics of ion flow in plasma-etching reactor based on beam-plasma discharge

    International Nuclear Information System (INIS)

    It is shown that on the basis of the earlier revealed effect of generating the ion flow in the beam-plasma discharge from the discharge axis, a plasma processing reactor can be created for low-energy etching of semiconductor structures. The possibility of easily controlling the density and energy of ion flow by means of varying the potential of the discharge collector is demonstrated. The charge compensation of the ion flow incident on the nonconducting surface is implemented using the modulation of the potential of the substrate holder as well as the plasma-potential modulation.

  6. Absorption of focused laser beams by a nonspherical plasma

    International Nuclear Information System (INIS)

    The interaction of a high intensity axially symmetric beam with a nonspherical plasma is studied numerically. The high frequency plasma response is calculated using a linearized fluid approximation. The full three dimensional Maxwell's equations are solved in spherical coordinates. A method for selectively damping the longitudinal electric fields is included to model thermal, kinetic, or nonlinear effects near the critical density. The low frequency response of the plasma to the ponderomotive force is followed with an isothermal hydrodynamic description. The incident laser beam is circularly polarized so that the plasma remains azimuthally symmetric to first order. Detailed descriptions of several representative calculations are given. It is found that the absorption of an initially spherical plasma can be significantly increased by induced aspherical plasma density profile modifications. A simple physical explanation for the observed absorption increase is proposed. Finally, the validity of the approximations made is analyzed briefly

  7. Electron beam, laser beam and plasma arc welding studies

    Science.gov (United States)

    Banas, C. M.

    1974-01-01

    This program was undertaken as an initial step in establishing an evaluation framework which would permit a priori selection of advanced welding processes for specific applications. To this end, a direct comparison of laser beam, electron beam and arc welding of Ti-6Al-4V alloy was undertaken. Ti-6Al-4V was selected for use in view of its established welding characteristics and its importance in aerospace applications.

  8. Effect of beam emittance on self-modulation of long beams in plasma wakefield accelerators

    CERN Document Server

    Lotov, K V

    2015-01-01

    The initial beam emittance determines the maximum wakefield amplitude that can be reached as a result of beam self-modulation in the plasma. The wakefield excited by the fully self-modulated beam decreases linearly with the increase of the beam emittance. There is a value of initial emittance beyond which the self-modulation does not develop even if the instability is initiated by a strong seed perturbation. The emittance scale at which the wakefield is twice suppressed with respect to the zero-emittance case (the so called critical emittance) is determined by inability of the excited wave to confine beam particles radially and is related to beam and plasma parameters by a simple formula. The effect of beam emittance can be observed in several discussed self-modulation experiments.

  9. High current ion beam generation by nonlinear ponderomotive force of high intensity UV laser

    International Nuclear Information System (INIS)

    Using the anomaly at plasma interaction of petawatt-picosecond laser pulses with very high contrast ratio to generate plane geometry highly directed plasma blocks for laser fusion, the details of the block generation were studied. The aim was to produce plasma blocks with dielectrically generated highest possible initial thicknesses. One of the goals in laser-plasma interaction studies is to convert as much laser energy as possible into energetic particles. Most laser ion accelerations have only been done using infrared lasers. In this work, dependency of the laser energy absorption to laser wave-Length for a given laser intensity is investigated numerically. High intensity UV laser absorption by Raleigh plasma density is examined. High current ion beams generated by nonlinear ponderomotive force of intense UV laser with Hydrodynamics computation based on a genuine two-fluid code are presented. (author)

  10. Electron trajectory evaluation in laser-plasma interaction for effective output beam

    International Nuclear Information System (INIS)

    Using the ellipsoidal cavity model, the quasi-monoenergetic electron output beam in laser-plasma interaction is described. By the cavity regime the quality of electron beam is improved in comparison with those generated from other methods such as periodic plasma wave field, spheroidal cavity regime and plasma channel guided acceleration. Trajectory of electron motion is described as hyperbolic, parabolic or elliptic paths. We find that the self-generated electron bunch has a smaller energy width and more effective gain in energy spectrum. Initial condition for the ellipsoidal cavity is determined by laser-plasma parameters. The electron trajectory is influenced by its position, energy and cavity electrostatic potential. (classical areas of phenomenology)

  11. The beam-plasma interaction in the symmetrically opened plasma system with contrastreaming electron flows

    International Nuclear Information System (INIS)

    The beam-plasma interaction in the symmetrically opened plasma system with the plasma penetrating in vacuum along magnetic field in presence of the contratreaming electron flow is investigated. It is found that the contrastreaming electron flow component, that is formed by secondary electron-electron emissions from the collector, effects substantially on the oscillations in the system. 20 refs.; 31 figs

  12. Plasma focus experiments powered by explosive generators

    International Nuclear Information System (INIS)

    The plasma focus project began as an effort to develop an intense, pulsed, expendable neutron radiographic source. Since previous efforts to power a plasma focus with explosive generators had been successful, we proposed to couple our plate generators to a coaxial-geometry plasma focus to achieve this goal. Utilizing a small capacitor bank and a selected set of diagnostics, the explosive experiments were successfully conducted with maximum currents of 1.5 MA to 2.4 MA. A maximum neutron yield of approx. 3 x 1011 (DD) neutrons was achieved at the 2.4 MA level. Since the neutron yield did scale as a power of the maximum delivered current, and the neutron-producing source region was small, we conclude that this approach is an attractive option to achieve a neutron radiographic source. The need for a reliable open-circuiting switch at several megamperes has resulted in postponement of the project

  13. Electron beam interactions with ions in a warm plasma

    Energy Technology Data Exchange (ETDEWEB)

    Briggs, R. J.; Bers, A.

    1963-04-15

    Conditions are determined for which the ions of a plasma might gain appreciable energy from the interaction with an electron beam. The waves along the magnetic field in a one-dimensional beam-plasma system are examined. For a cold plasma, the transverse waves exhibit a convective instability near the ion cyclotron frequency and a nonconvective instability at very low frequencies. The convective instability is greatly altered by a finite ion temperature, whereas the low frequency instability is relatively unaffected by temperature. For a weak beam, the longitudinal interaction occurs above the electron plasma frequency unless V/sub o/ < T/sub e/, where V/sub o/ is the d-c beam voltage and T/sub e/ is the electron temperature. A very strong interaction at the ion plasma frequency arises if (n/sub b//n) (T/sub e//V/sub o/)> 1, where n/sub b/ and n/sub p/ are the beam and plasma densities. For both transverse and longitudinal interactions it is shown that the presence of damping (cyclotron or Landau) can give rise to resistive medium type instabilities. Some brief results will also be given on the interactions in finite geometries which include the electron temperature. (auth)

  14. Collaborative Research: Instability and transport of laser beam in plasma

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Harvey Arnold [New Mexico Consortium; Lushnikov, Pavel [University of New Mexico

    2014-11-18

    Our goal was to determine the onset of laser light scattering due to plasma wave instabilities. Such scatter is usually regarded as deleterious since laser beam strength is thereby diminished. While this kind of laser-plasma-instability (LPI) has long been understood for the case of coherent laser light, the theory of LPI onset for a laser beam with degraded coherence is recent. Such a laser beam fills plasma with a mottled intensity distribution, which has large fluctuations. The key question is: do the exceptionally large fluctuations control LPI onset or is it controlled by the relatively quiescent background laser intensity? We have answered this question. This is significant because LPI onset power in the former case is typically small compared to that of the latter. In addition, if large laser intensity fluctuations control LPI onset, then nonlinear effects become significant for less powerful laser beams than otherwise estimated.

  15. Inverse time-of-flight spectrometer for beam plasma research

    International Nuclear Information System (INIS)

    The paper describes the design and principle of operation of an inverse time-of-flight spectrometer for research in the plasma produced by an electron beam in the forevacuum pressure range (5–20 Pa). In the spectrometer, the deflecting plates as well as the drift tube and the primary ion beam measuring system are at high potential with respect to ground. This provides the possibility to measure the mass-charge constitution of the plasma created by a continuous electron beam with a current of up to 300 mA and electron energy of up to 20 keV at forevacuum pressures in the chamber placed at ground potential. Research results on the mass-charge state of the beam plasma are presented and analyzed

  16. Inverse time-of-flight spectrometer for beam plasma research

    Energy Technology Data Exchange (ETDEWEB)

    Yushkov, Yu. G., E-mail: yuyushkov@gmail.com; Zolotukhin, D. B.; Tyunkov, A. V. [Tomsk State University of Control Systems and Radioelectronics, 40 Lenin Ave., Tomsk 634050 (Russian Federation); Oks, E. M. [Tomsk State University of Control Systems and Radioelectronics, 40 Lenin Ave., Tomsk 634050 (Russian Federation); Institute of High Current Electronics SB RAS, 2/3, Akademichesky Ave., Tomsk 634055 (Russian Federation); Savkin, K. P. [Institute of High Current Electronics SB RAS, 2/3, Akademichesky Ave., Tomsk 634055 (Russian Federation)

    2014-08-15

    The paper describes the design and principle of operation of an inverse time-of-flight spectrometer for research in the plasma produced by an electron beam in the forevacuum pressure range (5–20 Pa). In the spectrometer, the deflecting plates as well as the drift tube and the primary ion beam measuring system are at high potential with respect to ground. This provides the possibility to measure the mass-charge constitution of the plasma created by a continuous electron beam with a current of up to 300 mA and electron energy of up to 20 keV at forevacuum pressures in the chamber placed at ground potential. Research results on the mass-charge state of the beam plasma are presented and analyzed.

  17. High Power Hydrogen Injector with Beam Focusing for Plasma Heating

    International Nuclear Information System (INIS)

    High power neutral beam injector has been developed with the atom energy of 25 keV, a current of 60 A, and several milliseconds pulse duration. Six of these injectors will be used for upgrade of the atomic injection system at central cell of a Gas Dynamic Trap (GDT) device and 2 injectors are planned for SHIP experiment.The injector ion source is based on an arc discharge plasma box. The plasma emitter is produced by a 1 kA arc discharge in hydrogen. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase its efficiency and improve homogeneity of the plasma emitter. The ion beam is extracted by a 4-electrodes ion optical system (IOS). Initial beam diameter is 200 mm. The grids of the IOS have a spherical curvature for geometrical focusing of the beam. The optimal IOS geometry and grid potentials were found with the numerical simulation to provide precise beam formation. The measured angular divergence of the beam is 0.02 rad, which corresponds to the 2.5 cm Gaussian radius of the beam profile measured at focal point

  18. Plasma plume MHD power generator and method

    Science.gov (United States)

    Hammer, J.H.

    1993-08-10

    A method is described of generating power at a situs exposed to the solar wind which comprises creating at separate sources at the situs discrete plasma plumes extending in opposed directions, providing electrical communication between the plumes at their source and interposing a desired electrical load in the said electrical communication between the plumes.

  19. Auroral ion beams and ion acoustic wave generation by fan instability

    International Nuclear Information System (INIS)

    Satellite observations indicate that efficient energy transport among various plasma particles and between plasma waves and plasma particles is taking place in auroral ion beam regions. These observations show that two characteristic wave types are associated with the auroral ion beam regions: electrostatic hydrogen cyclotron waves with frequencies above hydrogen gyrofrequency, and low frequency waves with frequencies below hydrogen gyrofrequency. We speculate that the low frequency waves can be ion acoustic waves generated through the fan instability. The presence of a cold background ion component is necessary for the onset of this instability. A cold ion component has been directly observed and has been indirectly suggested from observations of solitary wave structures. The wave-particle interaction during the development of the fan instability results in an efficient ion beam heating in the direction perpendicular to the ambient magnetic field. The fan instability development and the ion beam heating is demonstrated in a numerical particle simulation. 23 refs, 16 figs

  20. Determination of self generated magnetic field and the plasma density using Cotton Mouton polarimetry with two color probes

    Directory of Open Access Journals (Sweden)

    Joshi A.S.

    2013-11-01

    Full Text Available Self generated magnetic fields (SGMF in laser produced plasmas are conventionally determined by measuring the Faraday rotation angle of a linearly polarized laser probe beam passing through the plasma along with the interferogram for obtaining plasma density. In this paper, we propose a new method to obtain the plasma density and the SGMF distribution from two simultaneous measurements of Cotton Mouton polarimetry of two linearly polarized probe beams of different colors that pass through plasma in a direction normal to the planar target. It is shown that this technique allows us to determine the distribution of SGMF and the plasma density without doing interferometry of laser produced plasmas.

  1. A theory of two-beam acceleration of charged particles in a plasma waveguide

    International Nuclear Information System (INIS)

    The progress made in recent years in the field of high-current relativistic electron beam (REB) generation has aroused a considerable interest in studying REB potentialities for charged particle acceleration with a high acceleration rate T = 100MeV/m. It was proposed, in particular, to employ high-current REB in two-beam acceleration schemes (TBA). In these schemes high current REB (driving beam) excites intense electromagnetic waves in the electrodynamic structure which, in their turn, accelerate particles of the other beam (driven beam). The TBA schemes can be divided into two groups. The first group includes the schemes, where the two beams (driving and driven) propagate in different electrodynamic structures coupled with each other through the waveguides which ensure the microwave power transmission to accelerate driven beam particles. The second group includes the TBA schemes, where the driving and driven beams propagate in one electrodynamic structure. The main aim of this work is to demonstrate by theory the possibility of realizing effectively the TBA scheme in the plasma waveguide. The physical model of the TBA scheme under study is formulated. A set of equations describing the excitation of RF fields by a high-current REB and the acceleration of driven beam electrons is also derived. Results are presented on the the linear theory of plasma wave amplification by the driving beam. The range of system parameters, at which the plasma-beam instability develops, is defined. Results of numerical simulation of the TBA scheme under study are also presented. The same section gives the description of the dynamics of accelerated particle bunching in the high-current REB-excited field. Estimates are given for the accelerating field intensities in the plasma and electron acceleration rates

  2. Simulative research on the anode plasma dynamics in the high-power electron beam diode

    International Nuclear Information System (INIS)

    Anode plasma generated by electron beams could limit the electrical pulse-length, modify the impedance and stability of diode, and affect the generator to diode power coupling. In this paper, a particle-in-cell code is used to study the dynamics of anode plasma in the high-power electron beam diode. The effect of gas type, dynamic characteristic of ions on the diode operation with bipolar flow model are presented. With anode plasma appearing, the amplitude of diode current is increased due to charge neutralizations of electron flow. The lever of neutralization can be expressed using saturation factor. At same pressure of the anode gas layer, the saturation factor of CO2 is bigger than the H2O vapor, namely, the generation rate of C+ ions is larger than the H+ ions at the same pressure. The transition time of ions in the anode-cathode gap could be used to estimate the time of diode current maximum

  3. Hollow Gaussian beam generation through nonlinear interaction of photons with orbital-angular-momemtum

    CERN Document Server

    Chaitanya, N Apurv; Banerji, J; Samanta, G K

    2016-01-01

    Hollow Gaussian beams (HGB) are a special class of doughnut shaped beams that do not carry orbital angular momentum (OAM). Such beams have a wide range of applications in many fields including atomic optics, bio-photonics, atmospheric science, and plasma physics. Till date, these beams have been generated using linear optical elements. Here, we show a new way of generating HGBs by three-wave mixing in a nonlinear crystal. Based on nonlinear interaction of photons having OAM and conservation of OAM in nonlinear processes, we experimentally generated ultrafast HGBs of order as high as 6 and power >180 mW at 355 nm. This generic concept can be extended to any wavelength, timescales (continuous-wave and ultrafast) and any orders. We show that the removal of azimuthal phase of vortices does not produce Gaussian beam. We also propose a new and only method to characterize the order of the HGBs.

  4. Hollow Gaussian beam generation through nonlinear interaction of photons with orbital angular momentum.

    Science.gov (United States)

    Chaitanya, N Apurv; Jabir, M V; Banerji, J; Samanta, G K

    2016-01-01

    Hollow Gaussian beams (HGB) are a special class of doughnut shaped beams that do not carry orbital angular momentum (OAM). Such beams have a wide range of applications in many fields including atomic optics, bio-photonics, atmospheric science, and plasma physics. Till date, these beams have been generated using linear optical elements. Here, we show a new way of generating HGBs by three-wave mixing in a nonlinear crystal. Based on nonlinear interaction of photons having OAM and conservation of OAM in nonlinear processes, we experimentally generated ultrafast HGBs of order as high as 6 and power >180 mW at 355 nm. This generic concept can be extended to any wavelength, timescales (continuous-wave and ultrafast) and any orders. We show that the removal of azimuthal phase of vortices does not produce Gaussian beam. We also propose a new and only method to characterize the order of the HGBs. PMID:27581625

  5. Plasma heating in a long solenoid by a laser or a relativistic electron beam

    International Nuclear Information System (INIS)

    Advances in the technology of a large energy laser and/or relativistic electron beam (REB) generator have made it possible to seriously consider a long solenoid reactor concept. This concept has been reviewed. The physical problems in the plasma heating of the long solenoid by a laser or a REB are studied

  6. GeV electron beams from a laser-plasma accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, C.B.; Toth, Cs.; Nagler, B.; Gonsalves, A.J.; Nakamura, K.; Geddes, C.G.R.; Esarey, E.; Hooker, S.M.; Leemans, W.P.

    2006-10-01

    High-quality electron beams with up to 1 GeV energy havebeen generated by a laser-driven plasma-based accelerator by guiding a 40TW peak power laser pulse in a 3.3 cm long gas-filled capillary dischargewaveguide.

  7. Nanomaterial Synthesis Using Plasma Generation in Liquid

    Directory of Open Access Journals (Sweden)

    Genki Saito

    2015-01-01

    Full Text Available Over the past few decades, the research field of nanomaterials (NMs has developed rapidly because of the unique electrical, optical, magnetic, and catalytic properties of these materials. Among the various methods available today for NM synthesis, techniques for plasma generation in liquid are relatively new. Various types of plasma such as arc discharge and glow discharge can be applied to produce metal, alloy, oxide, inorganic, carbonaceous, and composite NMs. Many experimental setups have been reported, in which various parameters such as the liquid, electrode material, electrode configuration, and electric power source are varied. By examining the various electrode configurations and power sources available in the literature, this review classifies all available plasma in liquid setups into four main groups: (i gas discharge between an electrode and the electrolyte surface, (ii direct discharge between two electrodes, (iii contact discharge between an electrode and the surface of surrounding electrolyte, and (iv radio frequency and microwave plasma in liquid. After discussion of the techniques, NMs of metal, alloy, oxide, silicon, carbon, and composite produced by techniques for plasma generation in liquid are presented, where the source materials, reaction media, and electrode configurations are discussed in detail.

  8. Plasma driven neutron/gamma generator

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Ka-Ngo; Antolak, Arlyn

    2015-03-03

    An apparatus for the generation of neutron/gamma rays is described including a chamber which defines an ion source, said apparatus including an RF antenna positioned outside of or within the chamber. Positioned within the chamber is a target material. One or more sets of confining magnets are also provided to create a cross B magnetic field directly above the target. To generate neutrons/gamma rays, the appropriate source gas is first introduced into the chamber, the RF antenna energized and a plasma formed. A series of high voltage pulses are then applied to the target. A plasma sheath, which serves as an accelerating gap, is formed upon application of the high voltage pulse to the target. Depending upon the selected combination of source gas and target material, either neutrons or gamma rays are generated, which may be used for cargo inspection, and the like.

  9. Electron Beam Generation in Tevatron Electron Lenses

    International Nuclear Information System (INIS)

    New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near cathode. We present the designs of the guns and report results of beam measurements on the test bench. Because of their high current density and low transverse temperature of electrons, electron guns of this type can be used in electron cooling and beam-beam compensation devices

  10. Electron beam generation in Tevatron electron lenses

    International Nuclear Information System (INIS)

    New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near cathode. We present the designs of the guns and report results of beam measurements on the test bench. Because of their high current density and low transverse temperature of electrons, electron guns of this type can be used in electron cooling and beam-beam compensation devices

  11. A reduced model for relativistic electron beam transport in solids and dense plasmas

    Science.gov (United States)

    Touati, M.; Feugeas, J.-L.; Nicolaï, Ph; Santos, J. J.; Gremillet, L.; Tikhonchuk, V. T.

    2014-07-01

    A hybrid reduced model for relativistic electron beam transport based on the angular moments of the relativistic kinetic equation with a special closure is presented. It takes into account collective effects with the self-generated electromagnetic fields as well as collisional effects with the slowing down of the relativistic electrons by plasmons, bound and free electrons and their angular scattering on both ions and electrons. This model allows for fast computations of relativistic electron beam transport while describing their energy distribution evolution. Despite the loss of information concerning the angular distribution of the electron beam, the model reproduces analytical estimates in the academic case of a monodirectional and monoenergetic electron beam propagating through a warm and dense plasma and hybrid particle-in-cell simulation results in a realistic laser-generated electron beam transport case.

  12. Electric-arc steam plasma generator

    Science.gov (United States)

    Anshakov, A. S.; Urbakh, E. K.; Radko, S. I.; Urbakh, A. E.; Faleev, V. A.

    2015-01-01

    Investigation results on the arc plasmatorch for water-steam heating are presented. The construction arrangement of steam plasma generator with copper electrodes of the stepped geometry was firstly implemented. The energy characteristics of plasmatorch and erosion of electrodes reflect the features of their behavior at arc glow in the plasma-forming environment of steam. The results of numerical study of the thermal state of the composite copper-steel electrodes had a significant influence on optimization of anode water-cooling aimed at improvement of its operation life.

  13. PLASMA DIAGNOSTICS IN THE HEAVY ION BEAM-DENSE PLASMA INTERACTION EXPERIMENT AT ORSAY

    OpenAIRE

    Fleurier, C.; Sanba, A.; Hong, D; Mathias, J; Pellicer, J.

    1988-01-01

    We describe the plasma source used for interaction experiments between heavy ion beams (C4+ S7+) at energies of 2 Mev per nucleon and a plasma. The purpose of these experiments was to measure the ion energy loss in the plasma. The plasma diagnostics methods by emission spectroscopy, by laser interferometry and two-wavelength laser absorption are presented as well as the results.

  14. Robust Collimation Control of Laser-Generated Ion Beam

    CERN Document Server

    Kawata, S; Kamiyama, D; Nagashima, T; Barada, D; Gu, Y J; Li, X; Yu, Q; Kong, Q; Wang, P X

    2015-01-01

    The robustness of a structured collimation device is discussed for an intense-laser-produced ion beam. In this paper the ion beam collimation is realized by the solid structured collimation device, which produces the transverse electric field; the electric field contributes to reduce the ion beam transverse velocity and collimate the ion beam. Our 2.5 dimensional particle-in cell simulations demonstrate that the collimation device is rather robust against the changes in the laser parameters and the collimation target sizes. The intense short-pulse lasers are now available, and are used to generate an ion beam. The issues in the laser ion acceleration include an ion beam collimation, ion energy spectrum control, ion production efficiency, ion energy control, ion beam bunching, etc. The laser-produced ion beam tends to expand in the transverse and longitudinal directions during the ion beam propagation. The ion beam collimation is focused in this paper.

  15. Sustainable Power Generation by Plasma Physics

    Directory of Open Access Journals (Sweden)

    Anyaegbunam F. N. C. (Ph.D.

    2013-08-01

    Full Text Available One of the greatest challenges of developing countries today is electric power generation. The demand for Electric power is far above generation and distribution capacities. For instance, only about 4000MW of electricity is available for nearly 170 million people in Nigeria today. On the other hand, the cities are littered with municipal solid wastes in open dumps which are dangerous to health and environment. Sustainable and successful waste management should be safe, effective, environmentally friendly and economically viable.Application of plasma Physics in waste to energy can be one of the novel ways of sustainable power generation. In plasma gasifying cupola, the organic waste materials are gasified to generate a syngas and steam which can be used to generate electricity by integrated gasification combine circle. The inorganic part of the waste is vitrified to a benign residue used for construction. This paper describes the physics and technology involved, reviews the power situation in Nigeria and the benefits of implementation of this technology in waste to electric power generation. This might be an environmentally Safe and sustainable economic solution for waste management and alternative clean power generation

  16. Repetitive plasma opening switch for powerful high-voltage pulse generators

    International Nuclear Information System (INIS)

    Results are presented of experimental studies of plasma opening switches that serve to sharpen the pulses of inductive microsecond high-voltage pulse generators. It is demonstrated that repetitive plasma opening switches can be used to create super-powerful generators operating in a quasi-continuous regime. An erosion switching mechanism and the problem of magnetic insulation in repetitive switches are considered. Achieving super-high peak power in plasma switches makes it possible to develop new types of high-power generators of electron beams and X radiation. Possible implementations and the efficiency of these generators are discussed

  17. Beam-beam disruption and the case for a plasma lens in e-e- collisions

    International Nuclear Information System (INIS)

    In an e-e- collider, the mutual disruption of the beams will significantly decrease the luminosity, different from the case of e+e- colliders, where the mutual attraction of the oppositely-charged beams leads to a self-focusing effect. In this paper the authors estimate the beam disruption at SLC and NLC energies using ABEL simulations. They then give estimates of how a plasma lens might improve the luminosity in e-e- collisions

  18. An electron beam-heater with a broad-area plasma cathode

    International Nuclear Information System (INIS)

    An electron-beam heater with a broad-area plasma cathode was designed for thermal treatment of large surfaces in vacuum. Using the plasma electron source of broad cross-section beams instead of a hot-cathode gun generating thin scanning beams allows simultaneous heating all the surface as well as lengthening the service life and raising the reliability of the heater. A broad-area emitting plasma surface is produced in a special electrode cavity by injection into it, through a small hole, of charged particles from a reflex discharge with cold electrodes. Such a principle of design of the plasma cathode allows to obtain an electron beam of the required current density in the pressure range of 10-2 to 1 Pa. The heater can be operated with He, Ar, air and other gases. Using a multiaperture accelerating system comprising emitting and accelerating electrodes, an electron beam up to 150 mm in diameter with an energy up to 15 keV, a current up to 0.5 A, and a nonuniformity of the cross-sectional distribution of the current density not more than +- 6% on the area of 100 cm2 could be generated. The efficiency of the heater at the accelerating voltage of 11 to 13 kV equals to about 90%. (author)

  19. Generation of the Stigmatic Beam with Orbital Angular Momentum

    Institute of Scientific and Technical Information of China (English)

    高春清; 魏光辉; Horst WEBER

    2001-01-01

    The stigmatic beam with orbital angular momentum is generated by transforming the Hermite-Gaussian beamof a diode-pumped Nd:YAG laser through a rotated cylindrical optical system. Behind the transformation optics,the output beam has an intensity distribution of ring shape and a twist phase. The beam transformation istheoretically calculated and the result has been confirmed in the experiments.

  20. Efficient Generation of Truncated Bessel Beams using Cylindrical Waveguides

    Science.gov (United States)

    Ilchenko, Vladimir S.; Mohageg, Makan; Savchenkov, Anatoliy A.; Matsko, Andrey B.; Maleki, Lute

    2007-01-01

    In this paper we address efficient conversion between a Gaussian beam (a truncated plane wave) and a truncated Bessel beam of agiven order, using cylindrical optical waveguides and whispering gallery mode resonators. Utilizing a generator based on waveguides combined with whispering gallery mode resonators, we have realized Bessel beams of the order of 200 with a conversion efficiency exceeding 10 %.

  1. Resonant excitation of waves by a spiraling ion beam on the large plasma device

    Science.gov (United States)

    Tripathi, Shreekrishna

    2015-11-01

    The resonant interaction between energetic-ions and plasma waves is a fundamental topic of importance in the space, controlled magnetic-fusion, and laboratory plasma physics. We report new results on the spontaneous generation of traveling shear Alfvén waves and high-harmonic beam-modes in the lower-hybrid range of frequencies by an intense ion beam. In particular, the role of Landau and Doppler-shifted ion-cyclotron resonances (DICR) in extracting the free-energy from the ion-beam and destabilizing Alfvén waves was explored on the Large Plasma Device (LAPD). In these experiments, single and dual-species magnetized plasmas (n ~1010 -1012 cm-3, Te ~ 5.0-10.0 eV, B = 0.6-1.8 kG, He+ and H+ ions, 19.0 m long, 0.6 m diameter) were produced and a spiraling hydrogen ion beam (5-15 keV, 2-10 A, beam-speed/Alfvén-speed = 0.2-1.5, J ~ 50-150 mA/cm2, pitch-angle ~53°) was injected into the plasma. The interaction of the beam with the plasma was diagnosed using a retarding-field energy analyzer, three-axis magnetic-loop, and Langmuir probes. The resonance conditions for the growth of shear Alfvén waves were examined by varying the parameters of the ion-beam and ambient plasma. The experimental results demonstrate that the DICR process is particularly effective in exciting left-handed polarized shear Alfvén waves that propagate in the direction opposite to the ion beam. The high-harmonic beam modes were detected in the vicinity of the spiraling ion beam and contained more than 80 harmonics of Doppler-shifted gyro-frequency of the beam. Work jointly supported by US DOE and NSF and performed at the Basic Plasma Science Facility, UCLA.

  2. Generation of electron beams from a laser-based advanced accelerator at Shanghai Jiao Tong University

    OpenAIRE

    Elsied, Ahmed M. M.; Hafz, Nasr A. M.; Li, Song; Mirzaie, Mohammad; Sokollik, Thomas; Jie ZHANG

    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...

  3. Opacity of Shock-Generated Argon Plasmas

    Institute of Scientific and Technical Information of China (English)

    王藩侯; 陈敬平; 周显明; 李西军; 经福谦; 孟续军; 孙永盛

    2001-01-01

    Argon plasmas with uniform density and temperature are generated by a planar shock wave through argon gas. The opacities of argon plasma, covering the thermodynamic states at temperatures of 1.4-2.2eV and in densities of 0.0083- 0.015 g/cm3, are investigated by measuring the emitted radiance versus time at several visible wavelengths. Comparison of the measured opacities with those calculated demonstrates that the average atom model can be used well to describe the essential transport behaviour of photons in argon plasma under the abovementioned thermodynamic condition. A simplified and self-consistent method to deduce the reflectivity R(λ) at the baseplate surface is applied. It demonstrates that the values of R(λ) are all around 0.4 in the experiments, which are basically in agreement with those given by Erskine previously (1994 J. Quant. Spectrosc. Radiat.Transfer 51 97).

  4. Wakefields generated by collisional neutrinos in neutral-electron-positron-ion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Tinakiche, Nouara [Faculty of Sciences, Department of Physics, University of Boumeredes U.M.B.B., Boumerdes 35000 (Algeria)

    2015-12-15

    A classical fluid description is adopted to investigate nonlinear interaction between an electron-type neutrino beam and a relativistic collisionless unmagnetized neutral-electron-positron-ion plasma. In this work, we consider the collisions of the neutrinos with neutrals in the plasma and study their effect on the generation of wakefields in presence of a fraction of ions in a neutral-electron-positron plasma. The results obtained in the present work are interpreted and compared with previous studies.

  5. Wakefields generated by collisional neutrinos in neutral-electron-positron-ion plasma

    International Nuclear Information System (INIS)

    A classical fluid description is adopted to investigate nonlinear interaction between an electron-type neutrino beam and a relativistic collisionless unmagnetized neutral-electron-positron-ion plasma. In this work, we consider the collisions of the neutrinos with neutrals in the plasma and study their effect on the generation of wakefields in presence of a fraction of ions in a neutral-electron-positron plasma. The results obtained in the present work are interpreted and compared with previous studies

  6. Collective Interaction of Modulated and Unmodulated Electron Beams with Plasma

    International Nuclear Information System (INIS)

    Results are presented of experimental investigations of collective interactions of charged particle beams with a plasma. (Beam current 5 to 35 A, energy of beam electrons 8 to 20 keV, pulse length 3.6 to 100 μs, longitudinal magnetic field 600 to 1300 Oe). The plasma was produced by the electron beam. By experiments with initially unmodulated beams we determined the elementary mechanisms responsible for exciting the instability, the conditions of excitation, the frequency spectra and phase velocities of the excited waves, the oscillation growth rates, the electric field strengths, the absolute values and spectral.distribution of the power of the excited oscillations, and the electron temperatures. The power lost by the electron beam as a result of collective interaction with the plasma was determined by a calorimetric method, and it is shown that it coincides with the power of the high-frequency oscillations set up by the interaction of the beam with the plasma. The experimental measurements of the frequencies, oscillation growth rates and phase velocities of the oscillations excited in the plasma show good agreement with the calculated values. Modulation of the beam increases the efficiency of its interaction with the plasma. The power of the oscillations excited at the modulation frequency increases by the factor 50; that of the oscillations at other frequencies decreases considerably over a wide range of frequencies. A possibility is therefore presented of eliminating instabilities over a wide range of frequencies. Experiments were carried out to study the transition of the plasma to a turbulent state as a result of the development of beam instabilities. The variations with time of the frequency spectra during the .development of instabilities were investigated (from 100 kc/s to 10 000 Mc/s), the correlation functions were determined and the discontinuities in the phase of the excited oscillations were investigated. These measurements, as well as investigations

  7. Explosive emission cathode plasmas in intense relativistic electron beam diodes

    International Nuclear Information System (INIS)

    An experimental study of cathode plasmas in planar diodes driven by a Sandia Nereus accelerator (270 kV, 60 kA, 70 ns), with particular attention devoted to plasma uniformity and expansion velocity, has been carried out. This diode current density was varied over a factor of ten and the rate of rise of the applied field dE/dt was varied over a factor of six. Different cathode materials, coatings, and surface roughnesses were used and the effects of glow discharge cleaning and in situ heating of the cathode were examined. Framing photography, electron beam dosimetry, perveance measurements, optical interferometry, and (spatially and temporally resolved) spectroscopy were used to diagnose the plasma uniformity, electron beam uniformity, plasma front motion, electron density, plasma composition, motion of distinct species, electron temperature, and ion (and neutral) densities. Electron beam uniformity is seen to be related to cathode plasma uniformity; this uniformity is enhanced by a high value of (the microscopic) dE/dt, which is determined both by the rise time of the applied field and by the cathode surface roughness. The significance of dE/dt is believed to be related to the screening effect of emitted electrons. The motion of the plasma front is seen to be affected by two phenomena. To begin with, all species of the cathode plasma are seen to expand at the same rate. The ions are believed to be accelerated to velocities on the order of 2 to 3 cm/μs in dense cathode spot regions at the cathode surface. Plasma expansion is also influenced by electric pressure effects, which are determined by the shape of the driving power pulse. A simple cathode plasma model, which explains the similarity of plasmas in diodes with greatly differing parameters, is proposed. The relevance of these results to inductively driven diodes, repetitively pulsed diodes, and magnetically insulated transmission lines is also discussed

  8. Ferroelectric Plasma Source for Heavy Ion Beam Charge Neutralization

    CERN Document Server

    Efthimion, Philip; Gilson, Erik P; Grisham, Larry; Logan, B G; Waldron, William; Yu, Simon

    2005-01-01

    Plasmas are employed as a medium for charge neutralizing heavy ion beams to allow them to focus to a small spot size. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length ~ 0.1-1 m would be suitable. To produce 1 meter plasma, large-volume plasma sources based upon ferroelectric ceramics are being considered. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. The source will utilize the ferroelectric ceramic BaTiO3 to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) will be covered with ceramic. High voltage (~ 1-5 kV) is applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. A prototype ferroelectric source 20 cm long produced plasma densities ~ 5x1011 cm-3. The source was integrated into the experiment and successfully charge neutralized the K ion beam. Presently, the 1 meter source ...

  9. Ferroelectric Plasma Source for Heavy Ion Beam Charge Neutralization

    International Nuclear Information System (INIS)

    Plasmas are employed as a source of unbound electrons for charge neutralizing heavy ion beams to allow them to focus to a small spot size. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length ∼ 0.1-1 m would be suitable. To produce one-meter plasma, large-volume plasma sources based upon ferroelectric ceramics are being developed. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. The source utilizes the ferroelectric ceramic BaTiO3 to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) will be covered with ceramic, and high voltage (∼ 1-5 kV) applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. A prototype ferroelectric source 20 cm long has produced plasma densities of 5 x 1011 cm-3. The source was integrated into the previous Neutralized Transport Experiment (NTX), and successfully charge neutralized the K+ ion beam. Presently, the one-meter source is being fabricated. The source is being characterized and will be integrated into NDCX for charge neutralization experiments

  10. Generation and application of bessel beams in electron microscopy.

    Science.gov (United States)

    Grillo, Vincenzo; Harris, Jérémie; Gazzadi, Gian Carlo; Balboni, Roberto; Mafakheri, Erfan; Dennis, Mark R; Frabboni, Stefano; Boyd, Robert W; Karimi, Ebrahim

    2016-07-01

    We report a systematic treatment of the holographic generation of electron Bessel beams, with a view to applications in electron microscopy. We describe in detail the theory underlying hologram patterning, as well as the actual electron-optical configuration used experimentally. We show that by optimizing our nanofabrication recipe, electron Bessel beams can be generated with relative efficiencies reaching 37±3%. We also demonstrate by tuning various hologram parameters that electron Bessel beams can be produced with many visible rings, making them ideal for interferometric applications, or in more highly localized forms with fewer rings, more suitable for imaging. We describe the settings required to tune beam localization in this way, and explore beam and hologram configurations that allow the convergences and topological charges of electron Bessel beams to be controlled. We also characterize the phase structure of the Bessel beams generated with our technique, using a simulation procedure that accounts for imperfections in the hologram manufacturing process. PMID:27203186

  11. Determination of the electron parameters in plasma edge layers using a thermal helium beam

    International Nuclear Information System (INIS)

    For the reported study on He beam diagnostics in the plasma generator, techniques of molecular beam physics have been applied for plasma diagnosis. Various beam sources have been experimentally tested and compared for their beam divergence and rate distribution. Single nozzles of various shape and diameter have been examined. A great number of radiative transitions in the visible range of the spectrum have been experimentally examined, and the self-consistency of the model calculations has been verified by comparing the measured intensity relations with the calculated values. Subsequently, a new evaluation of the data available in the literature has been made on the basis of the results obtained by the study. (orig./CB)

  12. Staging laser plasma accelerators for increased beam energy

    International Nuclear Information System (INIS)

    Staging laser plasma accelerators is an efficient way of mitigating laser pump depletion in laser driven accelerators and necessary for reaching high energies with compact laser systems. The concept of staging includes coupling of additional laser energy and transporting the electron beam from one accelerating module to another. Due to laser damage threshold constraints, in-coupling laser energy with conventional optics requires distances between the accelerating modules of the order of 10m, resulting in decreased average accelerating gradient and complicated e-beam transport. In this paper we use basic scaling laws to show that the total length of future laser plasma accelerators will be determined by staging technology. We also propose using a liquid jet plasma mirror for in-coupling the laser beam and show that it has the potential to reduce distance between stages to the cm-scale.

  13. Staging laser plasma accelerators for increased beam energy

    Energy Technology Data Exchange (ETDEWEB)

    Panasenko, Dmitriy; Shu, Anthony; Schroeder, Carl; Gonsalves, Anthony; Nakamura, Kei; Matlis, Nicholas; Cormier-Michel, Estelle; Plateau, Guillaume; Lin, Chen; Toth, Csaba; Geddes, Cameron; Esarey, Eric; Leemans, Wim

    2008-09-29

    Staging laser plasma accelerators is an efficient way of mitigating laser pump depletion in laser driven accelerators and necessary for reaching high energies with compact laser systems. The concept of staging includes coupling of additional laser energy and transporting the electron beam from one accelerating module to another. Due to laser damage threshold constraints, in-coupling laser energy with conventional optics requires distances between the accelerating modules of the order of 10m, resulting in decreased average accelerating gradient and complicated e-beam transport. In this paper we use basic scaling laws to show that the total length of future laser plasma accelerators will be determined by staging technology. We also propose using a liquid jet plasma mirror for in-coupling the laser beam and show that it has the potential to reduce distance between stages to the cm-scale.

  14. System for transporting an electron beam to the atmosphere for a gun with a plasma emitter

    Science.gov (United States)

    Kornilov, S. Yu.; Rempe, N. G.; Shidlovskiy, S. V.

    2016-06-01

    We report on the results of simulation of the gas flow in a gun with a plasma emitter and in the system for extracting the electron beam to the atmosphere, constructed on the basis of standard gasdynamic windows (GDWs). The design of the gun and GDWs is described. Calculations are performed for a pressure of about 10-3 Torr in the electron beam generation range. It is shown that the pressure drop to the atmospheric pressure in the system of electron beam extraction to the atmosphere can be ensured by two GDW stages evacuated by pumps with optimal performance.

  15. The instability of an electron beam with a finite radius in a boundless plasma

    Directory of Open Access Journals (Sweden)

    G. V. Lizunov

    Full Text Available Within the framework of a linear theory, the instability of an electron beam with a finite radius in a cold magnetised boundless plasma is considered. It is shown that a finite beam dimension influences the generation of quasi-potential waves in two aspects: the perpendicular wave number is quantised so that the frequencies of the waves are subjected to strong selection; a new kind of instability appears due to wave energy losses by emission into surrounding space. Growth rate dependence of wave numbers and frequencies is investigated for typical parameters of experiments with electron beams in space.

  16. Ignition Features of Plasma-Beam Discharge in Gas-Discharge Electron Gun Operation

    OpenAIRE

    Valery A. Tutyk; Anatoliy N. Ovcharuk; Michail I. Gasik; Dmitriy V. Maslenikov

    2013-01-01

    The current paper presents the results of experimental researches to determine the mode features of plasma-beam discharge (PBD) generation by an electron beam injected by a low-vacuum gasdischarge electron gun (LGEG) with the cold cathode and hollow anode on the basis of the high-voltage glow discharge and in the range of helium pressure of P ? 10 ÷ 130 Pa. The PBD boundaries and their dependences on parameters of an electron beam are found. The influence of PBD on parameters of low-vacuum ga...

  17. Propagation characters of Gaussian laser beams in collisionless plasma: Effect of plasma temperature

    International Nuclear Information System (INIS)

    This paper presents an investigation of the propagation characters of Gaussian laser beam in cold collisionless plasma by considering the plasma temperature variation. The ponderomotive nonlinearity is involved and induces the nonlinear self-focusing against spatial diffraction. The second-order differential equation of dimensionless beam width parameter f(ξ) in terms of plasma temperature is established from Maxwell's equations with paraxial approximation. The initial (P0,ρ0) plane, behaviors of f(ξ) parameter, and perturbed density n/nn0n0 of different plasma temperatures are plotted and analyzed. The plasma temperature is divided into four regions, which leads to different propagation characters including oscillatory divergence, self-trapping, self-focusing, and steady divergence. The plasma density distribution modified by the electric field intensity and plasma temperature is discussed.

  18. Simulation studies of plasma waves in the electron foreshock - The generation of downshifted oscillations

    Science.gov (United States)

    Dum, C. T.

    1990-01-01

    The generation of waves with frequencies downshifted from the plasma frequency, as observed in the electron foreshock, is analyzed by particle simulation. Wave excitation differs fundamentally from the familiar excitation of the plasma eigenmodes by a gentle bump-on-tail electron distribution. Beam modes are destabilized by resonant interaction with bulk electrons, provided the beam velocity spread is very small. These modes are stabilized, starting with the higher frequencies, as the beam is broadened and slowed down by the interaction with the wave spectrum. Initially a very cold beam is also capable of exciting frequencies considerably above the plasma frequency, but such oscillations are quickly stabilized. Low-frequency modes persist for a long time, until the bump in the electron distribution is completely 'ironed' out. This diffusion process also is quite different from the familiar case of well-separated beam and bulk electrons. A quantitative analysis of these processes is carried out.

  19. Gaussian laser beam in a magnetized plasma. 2

    International Nuclear Information System (INIS)

    Properties of a laser beam propagating perpendicular to the external magnetic field in a plasma are investigated theoretically. The beam is represented by a Helmholtz equation in almost all plasma parameter space. For the upper hybrid wave region the wave equation turns to a hyperbolic partial differential equation. It is shown that both equations can be exactly solved by using a method of separation of variables and that solutions having Gaussian profiles lateral to the propagation direction are obtained. An appreciable difference between two solutions appears in their phase factors. Owing to the asymmetry of the configuration around the axis of wave propagation the cross sections of beams take shapes of ellipse and each beam has two different focus points. (author)

  20. 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.

  1. On the generation and disruption of a picosecond runaway electron beam during the breakdown of an atmospheric-pressure gas gap

    Energy Technology Data Exchange (ETDEWEB)

    Barengolts, S. A. [Prokhorov General Physics Institute, RAS, 38 Vavilov St., 119991 Moscow (Russian Federation); Mesyats, G. A.; Tsventoukh, M. M. [Lebedev Physical Institute, RAS, 53 Leninsky Ave., 119991 Moscow (Russian Federation); Uimanov, I. V. [Institute of Electrophysics, RAS, 106 Amundsen St., 620016 Ekaterinburg (Russian Federation)

    2012-03-26

    The generation and disruption of the picosecond runaway electron beam in atmospheric pressure strongly overvolted gas gap is considered with emphasis on the runaway kinetics, the increase in emission current and plasma density, and beam instabilities. It has been shown that a few-nanosecond ten-kV prepulse gives rise to a streamer. Application of the main pulse ({approx}2 MV/ns) results in the runaway electron beam generation with the streamer electrons involved in the acceleration, and in increase of the electron emission from the cathode and the plasma density. At the high enough plasma density, fast beam instability disrupts the runaway electron beam.

  2. Modulational instability of intense laser beam in magnetized plasma

    International Nuclear Information System (INIS)

    The nonlinear dispersion relation is derived for an intense left-hand elliptically polarized laser beam propagating through magnetized plasma by means of the Lorentz transformation. In terms of the Karpman method, the nonlinear governing equation for the envelope of the laser field is obtained. The modulational instability of the intense left-hand elliptically polarized laser beam in magnetized plasma is analyzed and the temporal growth rate of modulational instability is found. The analysis shows that the maximum growth rate of self-modulation instability is obviously smaller for magnetized plasma compared to the unmagnetized case. It is also shown that the temporal growth rate of modulational instability is increased significantly near the critical surface in a laser-plasma. (authors)

  3. Component composition of the SPD-100 stationary plasma engine beam

    International Nuclear Information System (INIS)

    Measurements of the particle-charge composition in a plasma jet of an SPT-100 stationary plasma thruster during its operation on xenon in the range of discharge voltages 150-750 V have been performed with an MX-7303 mass spectrometer. The measured angular distributions of singly, doubly, and triply charged xenon ions over the beam cross section and their energy spectra are presented. The changes in the beam composition due to its interaction with neutral xenon atoms during its transport to the measurement point are estimated

  4. The design of a plasma generator used in ships

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The process and condition of arc starting and discharge and heat balance rela-tionship in a plasma generator that takes water as propellant are analyzed. Two questions that must be paid attention to arise, when designing the plasma gen-erator. Water resistance in a plasma generator should be as big as possible, and inductive reactance of electric source should be equal to capacity reactance of plasma generator so that resonance is generated in electric circuit, voltage be-tween two electrodes in the plasma generator reaches the highest value, and arc starting and discharge also occur between electrodes in the plasma generator. When energy that electric source supplies is greater than or equal to the energy required when water becomes plasma, a mixture of plasma and steam ejects from the generator outlet. So it is necessary that cavity between electrodes in the plasma generator should be as big as possible, time that water stays in the plasma gen-erator should be long enough so that water obtains enough energy from the electric source, but resistance of water becomes small and arc starting is not easy to occur. Through manufacturing and experimentes on four kinds of plasma generators as well as the contrast between experimental results, the plasma generator model is established and the plasma generator is manufactured.

  5. Strong self-focusing of a cosh-Gaussian laser beam in collisionless magneto-plasma under plasma density ramp

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Vikas; Kant, Niti, E-mail: nitikant@yahoo.com [Department of Physics, Lovely Professional University, G. T. Road, Phagwara, Punjab 144411 (India)

    2014-07-15

    The effect of plasma density ramp on self-focusing of cosh-Gaussian laser beam considering ponderomotive nonlinearity is analyzed using WKB and paraxial approximation. It is noticed that cosh-Gaussian laser beam focused earlier than Gaussian beam. The focusing and de-focusing nature of the cosh-Gaussian laser beam with decentered parameter, intensity parameter, magnetic field, and relative density parameter has been studied and strong self-focusing is reported. It is investigated that decentered parameter “b” plays a significant role for the self-focusing of the laser beam as for b=2.12, strong self-focusing is seen. Further, it is observed that extraordinary mode is more prominent toward self-focusing rather than ordinary mode of propagation. For b=2.12, with the increase in the value of magnetic field self-focusing effect, in case of extraordinary mode, becomes very strong under plasma density ramp. Present study may be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, and x-ray lasers. Moreover, plasma density ramp plays a vital role to enhance the self-focusing effect.

  6. Strong self-focusing of a cosh-Gaussian laser beam in collisionless magneto-plasma under plasma density ramp

    International Nuclear Information System (INIS)

    The effect of plasma density ramp on self-focusing of cosh-Gaussian laser beam considering ponderomotive nonlinearity is analyzed using WKB and paraxial approximation. It is noticed that cosh-Gaussian laser beam focused earlier than Gaussian beam. The focusing and de-focusing nature of the cosh-Gaussian laser beam with decentered parameter, intensity parameter, magnetic field, and relative density parameter has been studied and strong self-focusing is reported. It is investigated that decentered parameter “b” plays a significant role for the self-focusing of the laser beam as for b=2.12, strong self-focusing is seen. Further, it is observed that extraordinary mode is more prominent toward self-focusing rather than ordinary mode of propagation. For b=2.12, with the increase in the value of magnetic field self-focusing effect, in case of extraordinary mode, becomes very strong under plasma density ramp. Present study may be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, and x-ray lasers. Moreover, plasma density ramp plays a vital role to enhance the self-focusing effect

  7. Shining a Gluon Beam Through Quark-Gluon Plasma

    CERN Document Server

    Chesler, Paul M; Rajagopal, Krishna

    2011-01-01

    We compute the energy density radiated by a quark undergoing circular motion in strongly coupled $\\mathcal N = 4$ supersymmetric Yang-Mills plasma. If it were in vacuum, this quark would radiate a beam of strongly coupled radiation whose angular distribution has been characterized and is very similar to that of synchrotron radiation produced by an electron in circular motion in electrodynamics. Here, we watch this beam of gluons getting quenched by the strongly coupled plasma. We find that a beam of gluons of momenta $\\sim q \\gg \\pi T$ is attenuated rapidly, over a distance $\\sim q^{1/3} (\\pi T)^{-4/3}$ in a plasma with temperature $T$. As the beam propagates through the plasma at the speed of light, it sheds trailing sound waves with momenta $\\lesssim \\pi T$. Presumably these sound waves would thermalize in the plasma if they were not hit soon after their production by the next pulse of gluons from the lighthouse-like rotating quark. At larger and larger $q$, the trailing sound wave becomes less and less pro...

  8. Dynamics of electron beams in the solar corona plasma with density fluctuations

    OpenAIRE

    Kontar, E. P.

    2001-01-01

    The problem of beam propagation in a plasma with small scale and low intensity inhomogeneities is investigated. It is shown that the electron beam propagates in a plasma as a beam-plasma structure and is a source of Langmuir waves. The plasma inhomogeneity changes the spatial distribution of the waves. The spatial distribution of the waves is fully determined by the distribution of plasma inhomogeneities. The possible applications to the theory of radio emission associated with electron beams...

  9. Thomson scattering measurement of a collimated plasma jet generated by a high-power laser system

    Science.gov (United States)

    Ishikawa, T.; Sakawa, Y.; Morita, T.; Yamaura, Y.; Kuramitsu, Y.; Moritaka, T.; Sano, T.; Shimoda, R.; Tomita, K.; Uchino, K.; Matsukiyo, S.; Mizuta, A.; Ohnishi, N.; Crowston, R.; Woolsey, N.; Doyle, H.; Gregori, G.; Koenig, M.; Michaut, C.; Pelka, A.; Yuan, D.; Li, Y.; Zhang, K.; Zhong, J.; Wang, F.; Takabe, H.

    2016-03-01

    One of the important and interesting problems in astrophysics and plasma physics is collimation of plasma jets. The collimation mechanism, which causes a plasma flow to propagate a long distance, has not been understood in detail. We have been investigating a model experiment to simulate astrophysical plasma jets with an external magnetic field [Nishio et al., EPJ. Web of Conferences 59, 15005 (2013)]. The experiment was performed by using Gekko XII HIPER laser system at Institute of Laser Engineering, Osaka University. We shot CH plane targets (3 mm × 3 mm × 10 μm) and observed rear-side plasma flows. A collimated plasma flow or plasma jet was generated by separating focal spots of laser beams. In this report, we measured plasma jet structure without an external magnetic field with shadowgraphy, and simultaneously measured the local parameters of the plasma jet, i.e., electron density, electron and ion temperatures, charge state, and drift velocity, with collective Thomson scattering.

  10. Magnetic field generation by short ultraintense laser pulse in underdense plasmas

    International Nuclear Information System (INIS)

    The theory of magnetic field generation due to the interaction of short relativistic laser pulses with underdense plasmas has been developed. The magnetic field is generated due to the inverse Faraday effect occurring with a circularly polarized laser pulse. The spatial distribution of the magnetic field is investigated. It is shown that the magnetic field magnitude depends on the relationship between the laser beam radius and the plasma skin-depth. (Author)

  11. The design of a plasma generator used in ships

    Institute of Scientific and Technical Information of China (English)

    WANG XinZhang; YANG JiaXiang; LAN Bo; XU ZuoMing; GAO Ying

    2008-01-01

    The process and condition of arc starting and discharge and heat balance rela-tionship in a plasma generator that takes water as propellant are analyzed.Two questions that must be paid attention to arise,when designing the plasma gen-erator.Water resistance in a plasma generator should be as big as possible,and inductive reactance of electric source should be equal to capacity reactance of plasma generator so that resonance is generated in electric circuit,voltage be-tween two electrodes in the plasma generator reaches the highest value,and arc starting and discharge also occur between electrodes in the plasma generator.When energy that electric source supplies is greater than or equal to the energy required when water becomes plasma,a mixture of plasma and steam ejects from the generator outlet.So it is necessary that cavity between electrodes in the plasma generator should be as big as possible,time that water stays in the plasma gen-erator should be long enough so that water obtains enough energy from the electric source,but resistance of water becomes small and arc starting is not easy to occur.Through manufacturing and experimentes on four kinds of plasma generators as well as the contrast between experimental results,the plasma generator model is established and the plasma generator is manufactured.

  12. Wave Propagation in an Ion Beam-Plasma System

    DEFF Research Database (Denmark)

    Jensen, T. D.; Michelsen, Poul; Juul Rasmussen, Jens

    1979-01-01

    The spatial evolution of a velocity- or density-modulated ion beam is calculated for stable and unstable ion beam plasma systems, using the linearized Vlasov-Poisson equations. The propagation properties are found to be strongly dependent on the form of modulation. In the case of velocity...... modulation, the perturbation grows initially and then shows a periodic change of amplitude along the beam, while in the case of a density modulation only an instability causes growth. The findings are in agreement with experimental results obtained by SATO et al. (1977)....

  13. Characterisation of an RF excited argon plasma cathode electron beam gun

    OpenAIRE

    Del Pozo, S.; Ribton, C; Smith, DR

    2014-01-01

    This work describes the experimental set up used for carrying out spectroscopic measurements in a plasma cathode electron beam (EB) gun. Advantages of plasma cathode guns over thermionic guns are described. The factors affecting electron beam power such as plasma pressure, excitation power and plasma chamber geometry are discussed. The maximum beam current extracted was 53 mA from a 0.5 mm diameter aperture in the plasma chamber. In this work, the electron source is an argon plasma excited at...

  14. Modeling of discharges generated by electron beams in dense gases: Fountain and thunderstorm regimes

    International Nuclear Information System (INIS)

    In this paper we present an analysis of the predicted dynamics of plasmas generated in air and other gases by injecting beams of high-energy electrons. Two distinct regimes are found, differing in the way that the excess negative charge brought in by the ionizing electron beam is removed. In the first regime, called a fountain, the charge is removed by the back current of plasma electrons toward the injection foil. In the second, called a thunderstorm, a substantial cloud of negative charge accumulates, and the increased electric field near the cloud causes a streamer to strike between the cloud and a positive or grounded electrode, or between two clouds created by two different beams. A quantitative analysis, including electron beam propagation, electrodynamics, charge particle kinetics, and a simplified heat balance, is performed in a one-dimensional approximation

  15. Hydrogen Plasma Generation with 200 MHz RF Ion Source

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeongtae; Park, Kwangmook; Seo, Dong Hyuk; Kim, Han-Sung; Kwon, Hyeok-Jung; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    The ion source for the system is required to be rugged with 2000 hours maintenance free operation time because it is installed in the vessel filled with SF6 gas at the pressure of 10 bar. A 200 MHz RF ion source is considered as an ion source. It is a simple construction and provides long life operation. The specifications of the ion source are 5 kV extraction voltage and 1 mA beam current referenced to the proton. RF ion source has been developed and undergone a performance test. Results of the test are presented. 200 MHz RF ion source is designated and manufactured. First of all test stand test of ion source are set up for a performance test of ion source. It includes a RF ion source, a 200-MHz RF system, beam extraction system, vacuum system, beam extraction system, and beam diagnostic system. At pressure of 1.2E-5 torr, hydrogen plasma is generated with net RF power 70 W. Pyrex tube surrounded by an inductive coil takes the role of vessel and discharge is enhanced with field of permanent magnets.

  16. The LICPA accelerator of dense plasma and ion beams

    Czech Academy of Sciences Publication Activity Database

    Badziak, J.; Jabłoński, S.; Pisarczyk, T.; Chodukowski, T.; Parys, P.; Rączka, P.; Rosiński, M.; Krouský, Eduard; Ullschmied, Jiří; Liska, R.; Kucharik, M.; Torrisi, L.

    Vol. 508. Bristol: IOP Publishing, 2014, 012006-012006. (IOPscience. 508). ISSN 1742-6588. [Plasma Physics by Laser and Applications 2013 Conference (PPLA2013). Lecce (IT), 02.10.2013-04.10.2013] R&D Projects: GA MŠk LM2010014 Institutional support: RVO:61389021 ; RVO:68378271 Keywords : LICPA accelerator * ion beams * macroparticle acceleration * PALS laser * PIC simulations Subject RIV: BL - Plasma and Gas Discharge Physics; BL - Plasma and Gas Discharge Physics (FZU-D) http://iopscience.iop.org/1742-6596/508/1/012006/pdf/1742-6596_508_1_012006.pdf

  17. 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)

  18. Chirp mitigation of plasma-accelerated beams using a modulated plasma density

    CERN Document Server

    Brinkmann, R; Dornmair, I; Assmann, R; Behrens, C; Floettmann, K; Grebenyuk, J; Gross, M; Jalas, S; Kirchen, M; Mehrling, T; de la Ossa, A Martinez; Osterhoff, J; Schmidt, B; Wacker, V; Maier, A R

    2016-01-01

    Plasma-based accelerators offer the possibility to drive future compact light sources and high-energy physics applications. Achieving good beam quality, especially a small beam energy spread, is still one of the major challenges. For stable transport, the beam is located in the focusing region of the wakefield which covers only the slope of the accelerating field. This, however, imprints a longitudinal energy correlation (chirp) along the bunch. Here, we propose an alternating focusing scheme in the plasma to mitigate the development of this chirp and thus maintain a small energy spread.

  19. Controllable high-quality electron beam generation by phase slippage effect in layered targets

    International Nuclear Information System (INIS)

    The bubble structure generated by laser-plasma interactions changes in size depending on the local plasma density. The self-injection electrons' position with respect to wakefield can be controlled by tailoring the longitudinal plasma density. A regime to enhance the energy of the wakefield accelerated electrons and to improve the beam quality is proposed and achieved using layered plasmas with increasing densities. Both the wakefield size and the electron bunch duration are significantly contracted in this regime. The electrons remain in the strong acceleration phase of the wakefield, while their energy spread decreases because of their tight spatial distribution. An electron beam of 0.5 GeV with less than 1% energy spread is obtained through 2.5D particle-in-cell simulations

  20. Aluminum multicharged ion generation from laser plasma

    International Nuclear Information System (INIS)

    Highlights: • Multicharged Al ions are generated by a ns laser pulse ablation of an Al target in UHV. • Time-of-flight and electrostatic retarding field ion energy analyzers are used to detect the laser-generated MCIs. • For 5 kV accelerating voltage, laser energy of 90 mJ, up to Al+4 with ∼0.65 nC total ion charge is detected. • Raising accelerating voltage increases the charge extraction from the laser plasma and the energy of MCIs. • Ion extraction is dependent on electric field between Al target and extraction mesh. - Abstract: Multicharged aluminum ions are generated by a ns Q-switched Nd:YAG laser pulse ablation of an aluminum target in an ultrahigh vacuum. Time-of-flight and electrostatic retarding field ion energy analyzers are used to detect the laser-generated multicharged ions. The experiments are conducted using laser pulse energies of 45–90 mJ focused on the Al target surface by a lens with an 80-cm focal length to 0.0024 cm2 spot area and incident at 45° with the Al target surface. With the increase in the laser pulse energy, a slow increase in the number of ions generated is observed. The generation of ions with a higher charge state is also observed with the increase in the laser pulse energy. For 5 kV accelerating voltage applied to the Al target and using laser energy of 90 mJ, up to Al+4 with ∼0.65 nC total ion charge is delivered to the detector which is located 140 cm away from the Al target. Raising accelerating voltage increases the charge extraction from the laser plasma and the energy of multicharged ions

  1. Necklace Beam Generation in Nonlinear Colloidal Engineered Media

    CERN Document Server

    Silahli, Salih Z; Litchinitser, Natalia M

    2015-01-01

    Modulational instability is a phenomenon that reveals itself as the exponential growth of weak perturbations in the presence of an intense pump beam propagating in a nonlinear medium. It plays a key role in such nonlinear optical processes as supercontinuum generation, light filamentation, and rogue waves. However, practical realization of these phenomena in the majority of available nonlinear media still relies on high-intensity optical beams. Here, we analytically and numerically show the possibility of necklace beam generation originating from low-intensity spatial modulational instability of vortex beams in engineered soft-matter nonlinear media.

  2. Mono-Energetic Beams from Laser Plasma Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Geddes, C.G.R.; Esarey, E.; Leemans, W.P.; Schroeder, C.B.; Toth,Cs.; van Tilborg, J.; Cary, John R.; Bruhwiler, David L.; Nieter, Chet

    2005-05-09

    A laser driven wakefield accelerator has been tuned to produce high energy electron bunches with low emittance and energy spread by extending the interaction length using a plasma channel. Wakefield accelerators support gradients thousands of times those achievable in RF accelerators, but short acceleration distance, limited by diffraction, has resulted in low energy beams with 100 percent electron energy spread. In the present experiments on the L'OASIS laser, the relativistically intense drive pulse was guided over 10 diffraction ranges by a plasma channel. At a drive pulse power of 9 TW, electrons were trapped from the plasma and beams of percent energy spread containing > 200 pC charge above 80 MeV and with normalized emittance estimated at< 2pi-mm-mrad were produced. Data and simulations (VORPAL code) show the high quality bunch was formed when beam loading turned off injection after initial trapping, and when the particles were extracted as they dephased from the wake. Up to 4TW was guided without trapping, potentially providing a platform for controlled injection. The plasma channel technique forms the basis of a new class of accelerators, with high gradients and high beam quality.

  3. Formation and sustainment of field reversed configuration (FRC) plasmas by spheromak merging and neutral beam injection

    Science.gov (United States)

    Yamada, Masaaki

    2016-03-01

    This paper briefly reviews a compact toroid reactor concept that addresses critical issues for forming, stabilizing and sustaining a field reversed configuration (FRC) with the use of plasma merging, plasma shaping, conducting shells, neutral beam injection (NBI). In this concept, an FRC plasma is generated by the merging of counter-helicity spheromaks produced by inductive discharges and sustained by the use of neutral beam injection (NBI). Plasma shaping, conducting shells, and the NBI would provide stabilization to global MHD modes. Although a specific FRC reactor design is outside the scope of the present paper, an example of a promising FRC reactor program is summarized based on the previously developed SPIRIT (Self-organized Plasmas by Induction, Reconnection and Injection Techniques) concept in order to connect this concept to the recently achieved the High Performance FRC plasmas obtained by Tri Alpha Energy [Binderbauer et al, Phys. Plasmas 22,056110, (2015)]. This paper includes a brief summary of the previous concept paper by M. Yamada et al, Plasma Fusion Res. 2, 004 (2007) and the recent experimental results from MRX.

  4. Solid state generator for powerful radio frequency ion sources in neutral beam injection systems

    International Nuclear Information System (INIS)

    Radio frequency ion sources used in neutral beam injection systems (NBI) of fusion machines are currently supplied by self-excited RF generators. These generators have both a low power efficiency and a limited frequency stability, therefore transistorized amplifiers are being considered for the power supply of the next generation of RF sources. A 75 kW generator, originally designed for broadcasting, has been tested with a negative ion source. High operational reliability and a very good matching to the plasma load has been demonstrated. These results make this generator type a very promising candidate for future NBI systems

  5. Solid state generator for powerful radio frequency ion sources in neutral beam injection systems

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, W.; Fantz, U.; Heinemann, B.; Franzen, P.

    2015-02-15

    Radio frequency ion sources used in neutral beam injection systems (NBI) of fusion machines are currently supplied by self-excited RF generators. These generators have both a low power efficiency and a limited frequency stability, therefore transistorized amplifiers are being considered for the power supply of the next generation of RF sources. A 75 kW generator, originally designed for broadcasting, has been tested with a negative ion source. High operational reliability and a very good matching to the plasma load has been demonstrated. These results make this generator type a very promising candidate for future NBI systems.

  6. Long Plasma Source for Heavy Ion Beam Charge Neutralization

    Energy Technology Data Exchange (ETDEWEB)

    Efthimion, P.C.; Gilson, E.P.; Grisham, L.; Davidson, R.C.; Logan, B.G.; Seidl, P.A.; Waldron, W.

    2008-06-01

    Plasmas are a source of unbound electrons for charge neutralizing intense heavy ion beams to focus them to a small spot size and compress their axial length. The plasma source should operate at low neutral pressures and without strong externally-applied fields. To produce long plasma columns, sources based upon ferroelectric ceramics with large dielectric coefficients have been developed. The source utilizes the ferroelectric ceramic BaTiO{sub 3} to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) is covered with ceramic material. High voltage ({approx} 8 kV) is applied between the drift tube and the front surface of the ceramics. A BaTiO{sub 3} source comprised of five 20-cm-long sources has been tested and characterized, producing relatively uniform plasma in the 5 x 10{sup 10} cm{sup -3} density range. The source was integrated into the NDCX device for charge neutralization and beam compression experiments, and yielded current compression ratios {approx} 120. Present research is developing multi-meter-long and higher density sources to support beam compression experiments for high energy density physics applications.

  7. Plasma-wall interaction in an electrostatic sheath of plasma containing a monoenergetic electron beam

    Science.gov (United States)

    Ou, Jing; Zhao, Xiaoyun; Gan, Chunyun

    2016-04-01

    The plasma-wall interaction in the presence of a monoenergetic electron beam has been studied by taking into account the self-consistency among plasma transport in a collisionless electrostatic sheath, deposited energy flux at the wall and material thermal response for carbon and tungsten as wall materials. The variations of the potential drop across the sheath, ion velocity at the sheath edge, and surface temperature of material as a function of electron beam flux are explored in the presence of the electron emission. It is found that when electron beam does not dominate the sheath, potential drop across the sheath depends strongly on the material properties due to the impact of electron emission while the surface temperature of material shows monotonic variation. In the case of carbon wall, the electron beam may dominate the sheath at a certain electron beam concentration or energy. Under this circumstance, both the potential drop across the sheath and surface temperature of material demonstrate the sharp increasing transition. The development of local hot spot on the plasma facing material is caused by the enhanced ion energy flux instead of the electron beam energy flux. If the electron emission is not taken into account, as a smaller electron beam flux, both the potential drop across the sheath and surface temperature of material display the significant change and then it may be easier to develop for the local hot spot on the plasma facing material.

  8. Particle beam. Cancer treatment in next generation

    International Nuclear Information System (INIS)

    This feature article summarizes the present and future aspects of particle therapy of cancers in Japan. It contains the Interview article for carbon particle therapy by HIMAC (Heavy Ion Medical Accelerator in Chiba); Facilities for the therapy-present and future for diffusion; History of the carbon beam treatment in NIRS (National Institute of Radiological Sciences, Chiba); Plans for a facility unit for proton beam therapy of cancer in Fukui Pref. for the regional diffusion; a Center of Excellence program in Gunma University for forefront cancer therapy; and Technology of equipments supporting the particle beam therapy in manufacturers of Sumitomo Heavy Industries, Ltd., Toshiba Japan, Hitachi, and Mitsubishi Electric Corp. There are 6 facilities in total for the particle beam therapy of cancer in Japan. Although the diffusion of radiation therapy in Japan is as low as less than 30% in the whole cancer treatments, the particle beam therapy, an advanced form of radiotherapy, is on the top of the world. (T.I.)

  9. Return Current Electron Beams and Their Generation of "Raman" Scattering

    Science.gov (United States)

    Simon, A.

    1998-11-01

    For some years, we(A. Simon and R. W. Short, Phys. Rev. Lett. 53), 1912 (1984). have proposed that the only reasonable explanation for many of the observations of "Raman" scattering is the presence of an electron beam in the plasma. (The beam creates a bump-on-tail instability.) Two major objections to this picture have been observation of Raman when no n_c/4 surface was present, with no likely source for the electron beam, and the necessity for the initially outward directed beam to bounce once to create the proper waves. Now new observations on LLE's OMEGA(R. Petrasso et al), this conference. and at LULI(C. Labaune et al)., Phys. Plasma 5, 234 (1998). have suggested a new origin for the electron beam. This new scenario answers the previous objections, maintains electron beams as the explanation of the older experiments, and may clear up puzzling observations that have remained unexplained. The new scenario is based on two assumptions: (1) High positive potentials develop in target plasmas during their creation. (2) A high-intensity laser beam initiates spark discharges from nearby surfaces to the target plasma. The resulting return current of electrons should be much more delta-like, is initially inwardly directed, and no longer requires the continued presence of a n_c/4 surface. Scattering of the interaction beam from the BOT waves yields the observed Raman signal. Experimental observations that support this picture will be cited. ``Pulsation'' of the scattering and broadband ``flashes'' are a natural part of this scenario. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  10. Modeling and control of plasma rotation for NSTX using neoclassical toroidal viscosity and neutral beam injection

    Energy Technology Data Exchange (ETDEWEB)

    Goumiri, I. R. [Princeton Univ., NJ (United States). Mechanical and Aerospace Dept.; Rowley, C. W. [Princeton Univ., NJ (United States). Mechanical and Aerospace Dept.; Sabbagh, S. A. [Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics; Gates, D. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gerhardt, S. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Boyer, M. D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Andre, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Kolemen, E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Taira, K. [Florida State Univ, Dept Mech Engn, Tallahassee, FL USA.

    2016-02-19

    A model-based feedback system is presented to control plasma rotation in a magnetically confined toroidal fusion device, to maintain plasma stability for long-pulse operation. This research uses experimental measurements from the National Spherical Torus Experiment (NSTX) and is aimed at controlling plasma rotation using two different types of actuation: momentum from injected neutral beams and neoclassical toroidal viscosity generated by three-dimensional applied magnetic fields. Based on the data-driven model obtained, a feedback controller is designed, and predictive simulations using the TRANSP plasma transport code show that the controller is able to attain desired plasma rotation profiles given practical constraints on the actuators and the available measurements of rotation.

  11. Modeling and control of plasma rotation for NSTX using neoclassical toroidal viscosity and neutral beam injection

    Science.gov (United States)

    Goumiri, I. R.; Rowley, C. W.; Sabbagh, S. A.; Gates, D. A.; Gerhardt, S. P.; Boyer, M. D.; Andre, R.; Kolemen, E.; Taira, K.

    2016-03-01

    A model-based feedback system is presented to control plasma rotation in a magnetically confined toroidal fusion device, to maintain plasma stability for long-pulse operation. This research uses experimental measurements from the National Spherical Torus Experiment (NSTX) and is aimed at controlling plasma rotation using two different types of actuation: momentum from injected neutral beams and neoclassical toroidal viscosity generated by three-dimensional applied magnetic fields. Based on the data-driven model obtained, a feedback controller is designed, and predictive simulations using the TRANSP plasma transport code show that the controller is able to attain desired plasma rotation profiles given practical constraints on the actuators and the available measurements of rotation.

  12. Wave heating of an ion beam in a tokamak plasma

    International Nuclear Information System (INIS)

    Heating of a 26-keV trapped-ion beam by interaction with incident lower-hybrid RF power (as low as 5kW) was observed in the ATC plasma. We suggest that ion-cyclotron damping of lower hybrid waves by beam ions can account for the increase in beam energy. This process can explain the main features of the experiment: (1) preferential absorption in the perpendicular direction, (2) lack of absorption by the background plasma ions, and (3) low power requirement for absorption. Theory requires ksub(perpendicular)rhosub(i) approximately > (ω/ωsub(ci))sup(1/2). The relatively high perpendicular temperature of the beam ions (approximately 1keV), combined with one of several possibilities for RF energy at large ksub(perpendicular), allows the condition on ksub(perpendicular)rhosub(i) to be satisfied. Moreover, the large parallel energy of the beam ions plays a major role in broadening the harmonic resonances, thus making it possible for a large number of beam ions to resonate with the wave. Though the primary process is perpendicular absorption, there is also a net gain in parallel energy during a collision time due to pitch-angle scattering. The importance of this heating mechanism for large machines such as TFTR is discussed. For these machines, ions will be injected with large rhosub(i), making ion heating possible even with moderate values of ksub(perpendicular). (author)

  13. Electron acceleration by electron plasma wave excited by beating two cross-focused Cosh-Gaussian laser beams in collisionless plasma

    International Nuclear Information System (INIS)

    This paper presents a scheme for electron acceleration by excitation of an electron plasma wave (EPW) by beating two cross focused Cosh-Gaussian (ChG) laser beams in an underdense plasma where ponderomotive nonlinearity is operative. The ponderomotive nonlinearity depends not only on the intensity of first laser beam but also on that of second laser beam. Therefore, the propagation dynamics of one laser beam affects that of other and hence, cross-focusing of the two laser beams takes place. Virial theorem technique has been invoked to study the propagation dynamics of the laser beams. Due to nonuniform intensity distribution along the wavefronts of the laser beams, the background electron concentration gets modified. The amplitude of EPW, which depends on the background electron concentration, is thus nonlinearly coupled with the laser beams. The effects of ponderomotive nonlinearity and cross-focusing of the laser beams on excitation of EPW have been incorporated. The generated plasma wave produces regions of positive and negative charges and thus establishes an electric field that travels along with the plasma wave. If a charged particle is injected into the plasma at approximately the same velocity as plasma wave, it will stay in phase with the field, absorb energy from the field and accelerate steadily. It has been found that by changing the decentered parameter the peak intensity of ChG laser beam can be shifted in the transverse direction and hence, optimum acceleration of the electrons can be obtained. The plasma based electron accelerators can adieu to the era of gargantuan mega-accelerators. (author)

  14. Experimental investigations of plasma lens focusing and plasma channel transport of heavy ion beams

    International Nuclear Information System (INIS)

    Final focusing of ion beams and propagation in a reactor chamber are crucial questions for heavy ion beam driven Fusion. An alternative solution to ballistic quadrupole focusing, as it is proposed in most reactor studies today, is the utilization of the magnetic field produced by a high current plasma discharge. This plasma lens focusing concept relaxes the requirements for low emittance and energy spread of the driver beam significantly and allows to separate the issues of focusing, which can be accomplished outside the reactor chamber, and of beam transport inside the reactor. For focusing a tapered wall-stabilized discharge is proposed, a concept successfully demonstrated at GSI, Germany. For beam transport a laser pre-ionized channel can be used

  15. Ion beams in the plasma sheet boundary layer

    Science.gov (United States)

    Birn, J.; Hesse, M.; Runov, A.; Zhou, X.-Z.

    2015-09-01

    We explore characteristics of energetic particles in the plasma sheet boundary layer associated with dipolarization events, based on simulations and observations. The simulations use the electromagnetic fields of an MHD simulation of magnetotail reconnection and flow bursts as basis for test particle tracing. They are complemented by self-consistent fully electrodynamic particle-in-cell (PIC) simulations. The test particle simulations confirm that crescent-shaped earthward flowing ion velocity distributions with strong perpendicular anisotropy can be generated as a consequence of near-tail reconnection, associated with earthward flows and propagating magnetic field dipolarization fronts. Both PIC and test particle simulations show that the ion distribution in the outflow region close to the reconnection site also consist of a beam superposed on an undisturbed population, which, however, does not show strong perpendicular anisotropy. This suggests that the crescent shape is created by quasi-adiabatic deformation from ion motion along the magnetic field toward higher field strength. The simulation results compare favorably with "Time History of Events and Macroscale Interactions during Substorms" observations.

  16. Sagnac Interferometer Based Generation of Controllable Cylindrical Vector Beams

    Directory of Open Access Journals (Sweden)

    Cristian Acevedo

    2016-01-01

    Full Text Available We report on a novel experimental geometry to generate cylindrical vector beams in a very robust manner. Continuous control of beams’ properties is obtained using an optically addressable spatial light modulator incorporated into a Sagnac interferometer. Forked computer-generated holograms allow introducing different topological charges while orthogonally polarized beams within the interferometer permit encoding the spatial distribution of polarization. We also demonstrate the generation of complex waveforms obtained by combining two orthogonal beams having both radial modulations and azimuthal dislocations.

  17. Second-Harmonic Generation of Bessel Beams in Lossy Media

    Institute of Scientific and Technical Information of China (English)

    丁德胜; 许坚毅; 王耀俊

    2002-01-01

    We present a further analysis for the second-harmonic generation of Bessel beams in lossy media. The emphasis is put on the effect of absorption to the radial pattern of the second-harmonic beam. It is shown that within the absorption length of the second harmonic, the Bessel second-harmonic beam approaches limited diffraction in the radial direction and behaves as in the case of lossless media.

  18. 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.

  19. Second- and third-harmonic generation with vector Gaussian beams

    Science.gov (United States)

    Carrasco, Silvia; Saleh, Bahaa E. A.; Teich, Malvin C.; Fourkas, John T.

    2006-10-01

    We consider second-harmonic generation (SHG) and third-harmonic generation (THG) in a nonlinear optical crystal illuminated by a vector Gaussian beam, i.e., a Gaussian beam in which the axial component of the excitation field is considered. This component exhibits twice the Gouy phase shift of the transverse component and vanishes at points on the beam axis. Harmonic generation stemming from this component exhibits a unique dependence on geometrical factors associated with the location and focusing of the beam relative to the location of the crystal. Using the first Born approximation (undepleted fundamental beam), we derive analytical formulas for the quantities that characterize these geometrical factors for a nonlinear optical crystal described by an arbitrary nonlinear susceptibility tensor, for both SHG and THG and for all polarization components. We also determine the efficiencies of these processes as functions of the geometry of the experimental arrangement for phase-matched crystals as well as for crystals of infinite length.

  20. Novel methods of ozone generation by micro-plasma concept

    Energy Technology Data Exchange (ETDEWEB)

    Fateev, A.; Chiper, A.; Chen, W.; Stamate, E.

    2008-02-15

    The project objective was to study the possibilities for new and cheaper methods of generating ozone by means of different types of micro-plasma generators: DBD (Dielectric Barrier Discharge), MHCD (Micro-Hollow Cathode Discharge) and CPED (Capillary Plasma Electrode Discharge). This project supplements another current project where plasma-based DeNOx is being studied and optimised. The results show potentials for reducing ozone generation costs by means of micro-plasmas but that further development is needed. (ln)

  1. Transformer ratio improvement for beam based plasma accelerators

    International Nuclear Information System (INIS)

    Increasing the transformer ratio of wakefield accelerating systems improves the viability of present novel accelerating schemes. The use of asymmetric bunches to improve the transformer ratio of beam based plasma systems has been proposed for some time[1, 2] but suffered from lack appropriate beam creation systems. Recently these impediments have been overcome [3, 4] and the ability now exists to create bunches with current profiles shaped to overcome the symmetric beam limit of R ≤ 2. We present here work towards experiments designed to measure the transformer ratio of such beams, including theoretical models and simulations using VORPAL (a 3D capable PIC code) [5]. Specifically we discuss projects to be carried out in the quasi-nonlinear regime [6] at the UCLA Neptune Laboratory and the Accelerator Test Facility at Brookhaven National Lab.

  2. Modifications of the laser beam coherence inertial confinement fusion plasmas

    International Nuclear Information System (INIS)

    Inertial confinement fusion by laser requires smoothed laser beam with well-controlled coherence properties. Such beams are made of many randomly distributed intensity maxima: the so-called speckles. As the laser beam propagates through plasma its temporal and spatial coherence can be reduced. This phenomenon is called plasma induced smoothing. For high laser intensities, instabilities developing independently inside the speckles are responsible for the coherence loss. At lower intensities, only collective effects, involving many speckles, can lead to induced smoothing. This thesis is a theoretical, numerical and experimental study of these mechanisms. Accounting for the partially incoherent behavior of the laser beams requires the use of statistical description of the laser-plasma interaction. A model is developed for the multiple scattering of the laser light on the self-induced density perturbations that is responsible for a spreading of the temporal and spatial spectra of the transmitted light. It also serves as a strong seed for the instability of forward stimulated Brillouin scattering that induces both, angular spreading and red-shift of the transmitted light. A statistical model is developed for this instability. A criterion is obtained that gives a laser power (below the critical power for filamentation) above which the instability growth is important. Numerical simulations with the interaction code PARAX and an experiment performed on the ALISE laser facility confirm the importance of these forward scattering mechanisms in the modification of the laser coherence properties. (author)

  3. Theoretical and numerical studies on the transport of transverse beam quality in plasma-based accelerators

    OpenAIRE

    Mehrling, Timon

    2014-01-01

    This work examines effects, which impact the transverse quality of electron-beams in plasma-based accelerators, by means of theoretical and numerical methods. Plasma-based acceleration is a promising candidate for future particle accelerator technologies. In plasma-based acceleration, highly intense laser beams or high-current relativistic particle beams are focused into a plasma to excite plasma-waves with extreme transverse and longitudinal electric fields. The amplitude of these fields exc...

  4. Hollow structure formation of intense ion beams with sharp edge in background plasmas

    International Nuclear Information System (INIS)

    The transport of intense ion beams with sharp radial beam edge in plasmas has been studied with two-dimensional electromagnetic particle simulations. The initial solid beam evolves into a hollow beam due to the nonlinear sharp transverse force peak in the regions of beam edge. The magnitude and nonlinearity of this peak are enhanced as the ion beam travels further into the plasma, due to the self-consistent interactions between the beam ions and the plasma electrons. This structure formation is shown to be independent on the beam radius

  5. A microwave plasma cathode electron gun for ion beam neutralization

    Science.gov (United States)

    Fusellier, C.; Wartski, L.; Aubert, J.; Schwebel, C.; Coste, Ph.; Chabrier, A.

    1998-02-01

    It is well known that there exist two distinct types of ion beam neutralization, viz., charge and current neutralization. We have designed and studied a versatile and compact microwave plasma (MP) cathode electron gun dedicated to charge as well as current neutralization. Unlike the conventional hot cathode neutralizer, this MP cathode allows operation of the electron gun in a reactive gaseous environment when it is eventually associated with an electron cyclotron resonance (ECR) ion gun. Charge neutralization can be easily carried out by extracting from the MP cathode through a 1 mm diameter hole, a 35 mA electron beam under a 20 V voltage; the MP cathode being fed with a 75 W microwave power at 2.45 GHz. Higher beam intensities could be obtained using a multiaperture thin plate. Electron beam intensities as high as 300 mA and energies of 2 keV needed for current neutralization, e.g., when an ion beam impinges onto a thick dielectric surface, are obtained via a two-stage arrangement including an anodic chamber associated with a set of three monoaperture plates for the electron beam extraction. Transport of 200-2000 eV electron beams is ensured using focusing optics composed of three aligned tubes 6 cm in diameter and unsymmetrically polarized.

  6. High and low frequency instabilities driven by counter-streaming electron beams in space plasmas

    International Nuclear Information System (INIS)

    A four-component plasma composed of a drifting (parallel to ambient magnetic field) population of warm electrons, drifting (anti-parallel to ambient magnetic field) cool electrons, stationary hot electrons, and thermal ions is studied in an attempt to further our understanding of the excitation mechanisms of broadband electrostatic noise (BEN) in the Earth's magnetospheric regions such as the magnetosheath, plasmasphere, and plasma sheet boundary layer (PSBL). Using kinetic theory, beam-driven electrostatic instabilities such as the ion-acoustic, electron-acoustic instabilities are found to be supported in our multi-component model. The dependence of the instability growth rates and real frequencies on various plasma parameters such as beam speed, number density, temperature, and temperature anisotropy of the counter-streaming (relative to ambient magnetic field) cool electron beam are investigated. It is found that the number density of the anti-field aligned cool electron beam and drift speed play a central role in determining which instability is excited. Using plasma parameters which are closely correlated with the measurements made by the Cluster satellites in the PSBL region, we find that the electron-acoustic and ion-acoustic instabilities could account for the generation of BEN in this region

  7. Proton emission from laser-generated plasmas at different intensities

    Czech Academy of Sciences Publication Activity Database

    Torrisi, L.; Cutroneo, M.; Cavallaro, S.; Giuffrida, L.; Margarone, Daniele

    2012-01-01

    Roč. 57, č. 2 (2012), s. 237-240. ISSN 0029-5922. [International Conference on Research and Applications of Plasmas (PLASMA). Warsaw, 12.09.2011-16.09.2011] Institutional support: RVO:68378271 Keywords : laser-generated plasma * hydrogenated targets * proton acceleration Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.507, year: 2012

  8. Generator of steam plasma for gasification of solid fuels

    Science.gov (United States)

    An'shakov, A. S.; Urbakh, E. K.; Rad'ko, S. I.; Urbakh, A. E.; Faleev, V. A.

    2013-12-01

    A structural design of an electric-arc steam plasma torch (plasmatron) with copper tubular electrodes has been proposed and implemented. Operational parameters are determined for the stable generation of steam plasma. Experimental data are presented on the energy characteristics of the plasma generator with the capacity up to 100 kW.

  9. Quasi-monoenergetic Electron Beams from Laser-plasma Acceleration by Ionization-induced Injection in Low- density Pure Nitrogen

    OpenAIRE

    Tao, Mengze; Hafz, Nasr A. M.; Li, Song; Mirzaie, Mohammad; Chen, Liming; He, Fei; Cheng, Ya; Jie ZHANG

    2014-01-01

    We report a laser wakefield acceleration of electron beams up to 130 MeV from laser-driven 4-mm long nitrogen gas jet. By using a moderate laser intensity (3.5*10^18 W.cm^(-2)) and relatively low plasma densities (0.8*10^18 cm^(-3) to 2.7*10^18 cm^(-3)) we have achieved a stable regime for laser propagation and consequently a stable generation of electron beams. We experimentally studied the dependence of the drive laser energy on the laser-plasma channel and electron beam parameters. The qua...

  10. Effect of transverse magnetic field on generation of electron beam in gas diode

    International Nuclear Information System (INIS)

    One studied experimentally the effect of the transverse magnetic field (0.08 and 0.016 T) on the generation of an electron beam within a gas diode. At U=25 kV gas diode voltage and helium low pressure (45 Torr) the transverse magnetic field is shown to affect the beam current amplitude outside the foil and on its foil cross section distribution. Under the increased pressure values and at generation of an ultra short-time avalanche electron beam (UAEB) in helium, nitrogen and in air the transverse magnetic field is shown to affect negligibly the UAEB amplitude and duration outside the foil. At the generator voltage equal to hundreds of kilovolts a portion of the escaping electrons was found to arrive to the gas diode lateral walls including those from the discharge plasma in the vicinity of a cathode

  11. Investigation of plasma critical surface rippling by harmonics generation in laser plasmas

    International Nuclear Information System (INIS)

    One of the important applications of high intensity short pulse lasers is the generation of high harmonics. High harmonics are generated on the steep density gradients of plasmas by ultra-short laser pulses. Electron oscillations across the gradient generated at the critical surface serve as a source of high harmonics. In the last ten years experiments were carried out using different laser parameters by various wavelengths and pulse durations. In case of the laser pulse of less than 100 fs, the harmonics were found to be generated in the specular directions. Most of the experiments carried out by ultrahigh intensities (>1019 W/cm2) used laser pulses >500 fs duration. In these cases pre-plasmas were generated by the strong pre-pulses. Diffuse propagation of harmonics was observed, probably caused by the rippling of the critical surface. In our early experiments with a pre-pulse-free KrF laser of modest, 5·1015 W/cm2 intensities of 600 fs pulse duration, the propagation of harmonics was specular. Herewith we investigate harmonics generation with tightly focused KrF pulses of intensities up to 3·1017 W/cm2. Our experiments were carried out using a hybrid KrF-dye excimer laser system (15 mJ pulse energy, 600 fs pulse duration, 248 nm wavelength). Important to note that the amplification process of the system is a direct amplification (3-off-axis-pass KrF amplifier). Thus the only source of pre-pulses is the amplified spontaneous emission (ASE) of the amplifier. The beam was focused by an F/2 off-axis parabolic mirror to a 2.5 μm spot. The maximum intensity was 3·1017 W/cm2 on the target surface, with ASE pre-pulses below 107 W/cm2 intensity. The ASE did not generate a pre-plasma. Our targets were 500 nm thick Al and B or 270 nm thick C layers evaporated on glass plates. A Jobin-Yvon toroidal holographic grating and MCP assembly provided single shot spectra in the VUV. Intense 2ω, 3ω and near-threshold 4ω generation was observed in specular direction both for p

  12. Evaluation of two-beam spectroscopy as a plasma diagnostic

    International Nuclear Information System (INIS)

    A two-beam spectroscopy (TBS) system is evaluated theoretically and experimentally. This new spectroscopic technique uses correlations between components of emitted light separated by a small difference in angle of propagation. It is thus a non-perturbing plasma diagnostic which is shown to provide local (as opposed to line-of-sight averaged) information about fluctuations in the density of light sources within a plasma - information not obtainable by the usual spectroscopic methods. The present design is an improvement on earlier systems proposed in a thesis by Rostler

  13. Target momentum measurement in laser plasma propulsion using two probe beams

    International Nuclear Information System (INIS)

    A new method to measure the target velocity in laser plasma propulsion is proposed. By this method, the target velocity can be directly measured. The target thickness and the probe beam have no effects on measurement results. Compared with theoretical result, the error of experimental result is less than 2%. Furthermore, using this method, target momentum generation in laser-ablation water under different ambient temperatures is measured. Results show that the target momentum increases as the temperature decreases. (authors)

  14. Two-color beam generation based on wakefield excitation

    Science.gov (United States)

    Bettoni, S.; Prat, E.; Reiche, S.

    2016-05-01

    Several beam manipulation methods have been studied and experimentally tested to generate two-color photon beams in free electron laser facilities to accommodate the user requests. We propose to use the interaction of the beam with an oscillating longitudinal wakefield source to obtain a suitable electron beam structure. The bunch generates two subpulses with different energies and delayed in time passing through a magnetic chicane after its longitudinal phase space has been modulated by the wakefield source. According to this approach the power of the emitted radiation is not degraded compared to the monochromatic beam, and the setup in the machine is quite simple because the bunch is manipulated only in the high energy section, where it is more rigid. We present the design applied to SwissFEL. We identified the parameters and the corresponding range of tunability of the time and energy separation among the two subbunches.

  15. 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.

  16. Intense ion beams accelerated by relativistic laser plasmas

    Science.gov (United States)

    Roth, Markus; Cowan, Thomas E.; Gauthier, Jean-Claude J.; Allen, Matthew; Audebert, Patrick; Blazevic, Abel; Fuchs, Julien; Geissel, Matthias; Hegelich, Manuel; Karsch, S.; Meyer-ter-Vehn, Jurgen; Pukhov, Alexander; Schlegel, Theodor

    2001-12-01

    We have studied the influence of the target properties on laser-accelerated proton and ion beams generated by the LULI multi-terawatt laser. A strong dependence of the ion emission on the surface conditions, conductivity, shape and material of the thin foil targets were observed. We have performed a full characterization of the ion beam using magnetic spectrometers, Thompson parabolas, radiochromic film and nuclear activation techniques. The strong dependence of the ion beam acceleration on the conditions on the target back surface was found in agreement with theoretical predictions based on the target normal sheath acceleration (TNSA) mechanism. Proton kinetic energies up to 25 MeV have been observed.

  17. Metastable argon beam source using a surface wave sustained plasma

    International Nuclear Information System (INIS)

    A new source of metastable argon atoms in the thermal energy range is reported. The source is based on expanding a plasma sustained by electromagnetic surface waves in a quartz tube through a converging nozzle and extracting a beam from the supersonic free-expansion jet. The beam was characterized by time-of-flight measurements which yielded the absolute intensity and velocity distribution of the argon metastables. The source produced a maximum intensity of 6.2x1014 metastables per second per steradian, the highest time-averaged intensity of thermal argon metastables of any source reported to date. A simple picture of an expanding plasma in a recombination regime is used to explain the dependence of the metastable intensity on absorbed power

  18. Thermal Transport in NCS Plasmas with Counter Neutral Beam Injection

    Science.gov (United States)

    Stallard, B. W.; Casper, T. A.; Greenfield, C. M.; Burrell, K. H.; Gohil, P.; Lohr, J.; Petty, C. C.; Synakowski, E.; Austin, M. E.; McKee, G. R.; Rettig, C. L.; Rhodes, T. L.; Zeng, L.

    1999-11-01

    Recent experiments in DIII-D have investigated internal transport barrier (ITB) formation with neutral beams injected in the counter-current direction, assisted by early ECH during current ramp up. For counter injection the v_torBT term for radial force balance adds to the nabla p term to determine E× B flow shear. Compared to ITB plasmas with co-current injection, characteristics with counter injection at similar beam power are: (a) broader profiles of T_I, T_e, n_e, and ω_tor within a larger barrier radius, (b) reduced profile gradients in the barrier region, and (c) about a factor of 2 higher Z_eff ( ~4) from the carbon impurity. In this paper profile evolution and results of transport analysis will be compared with co-injection plasmas.

  19. Plasma opening switch experiments on the Particle Beam Accelerator II

    International Nuclear Information System (INIS)

    Plasma opening switch (POS) experiments have been done since 1986 on the PBFA-II ion beam accelerator to develop a rugged POS that will open rapidly (80%) into a high impedance (> 10 ohm) load. In a recent series of experiments on PBFA II, the authors have developed and tested three different switch designs that use magnetic fields to control and confine the injected plasma. All three configurations couple current efficiently to a 5-ohm electron beam diode. In this experimental series, the PBFA-II Delta Series, more extensive diagnostics were used than in previous switch experiments on PBFA II or on the Blackjack 5 accelerator at Maxwell Laboratories. Data from the experiments with these three switch designs is presented

  20. Application of electron beam plasma for biopolymers modification

    International Nuclear Information System (INIS)

    The effects of the Electron Beam Plasma treatment on natural polysaccharide chitosan were studied experimentally. Low molecular water-soluble products of chitosan and chitooligosaccharides were obtained by treating the original polymers in the Electron Beam Plasma of oxygen and water vapor. The molecular mass of the products varied from 18 kDa to monomeric fragments. The degradation of the original polymers was due to the action of active oxygen particles (atomic and singlet oxygen) and the particles of the water plasmolysis (hydroxyl radicals, hydrogen peroxides). The 95% yield of low molecular weight chitosans was attained by optimizing the treatment conditions. The studies of the antimicrobial activity of low molecular products showed that they strongly inhibit the multiplication of colon bacillus, aurococcus and yeast-like fungi. The EBP-stimulated degradation of polysaccharides and proteins were found to result from breaking β-1,4 glycosidic bounds and peptide bonds, respectively.

  1. Beam-plasma instabilities and their impact on D-D reactivity

    Science.gov (United States)

    Necas, Ales; Magee, R.; Tajima, T.; Nicks, B.; Seggebruch, M.; Garate, E.; Allfrey, I.; Valentine, T.; entire TAE Team

    2015-11-01

    The goal of the C-2U program is to achieve 5 +ms steady state FRC sustainment via beam injection. In support, we simulate possible beam driven instabilities that are non-destructive, but transfer energy from fast ions to the plasma, causing phase space bunching. Such a mechanism may explain an experimentally observed anomalous neutron signal (10-100 × greater than the predicted thermonuclear component and peaking between 1-2 ms, correlated with a 1 ms beam slowing down time), as other explanations have been eliminated (D in the beams, fast-thermal ion head-on collisions, and miscalculation of Ti). We propose that the hydrogen beam generates an energetic ion population that then drives collective modes in the plasma, giving rise to an instability and increased fusion rate. A two-body correlation function is employed to determine DD reactivity enhancements. The instability changes character from electrostatic (ES; phase velocity is 70% of the beam velocity) in the low beta edge to fully electromagnetic (EM; at magnetosonic speeds) in the core, with an associated reduction in growth rates. A 1D ES analytical dispersion relation will be compared with a 1D3V PIC code (full EM study only performed with PIC code). Results from simulations are consistent with the observed neutron yield.

  2. Ion probe beam experiments and kinetic modeling in a dense plasma focus Z-pinch

    Science.gov (United States)

    Schmidt, A.; Ellsworth, J.; Falabella, S.; Link, A.; McLean, H.; Rusnak, B.; Sears, J.; Tang, V.; Welch, D.

    2014-12-01

    The Z-pinch phase of a dense plasma focus (DPF) emits multiple-MeV ions in a ˜cm length. The mechanisms through which these physically simple devices generate such high energy beams in a relatively short distance are not fully understood. We are exploring the origins of these large gradients using measurements of an ion probe beam injected into a DPF during the pinch phase and the first kinetic simulations of a DPF Z-pinch. To probe the accelerating fields in our table top experiment, we inject a 4 MeV deuteron beam along the z-axis and then sample the beam energy distribution after it passes through the pinch region. Using this technique, we have directly measured for the first time the acceleration of an injected ion beam. Our particle-in-cell simulations have been benchmarked on both a kJ-scale DPF and a MJ-scale DPF. They have reproduced experimentally measured neutron yields as well as ion beams and EM oscillations which fluid simulations do not exhibit. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability for accelerator and neutron source applications.

  3. Ion probe beam experiments and kinetic modeling in a dense plasma focus Z-pinch

    International Nuclear Information System (INIS)

    The Z-pinch phase of a dense plasma focus (DPF) emits multiple-MeV ions in a ∼cm length. The mechanisms through which these physically simple devices generate such high energy beams in a relatively short distance are not fully understood. We are exploring the origins of these large gradients using measurements of an ion probe beam injected into a DPF during the pinch phase and the first kinetic simulations of a DPF Z-pinch. To probe the accelerating fields in our table top experiment, we inject a 4 MeV deuteron beam along the z-axis and then sample the beam energy distribution after it passes through the pinch region. Using this technique, we have directly measured for the first time the acceleration of an injected ion beam. Our particle-in-cell simulations have been benchmarked on both a kJ-scale DPF and a MJ-scale DPF. They have reproduced experimentally measured neutron yields as well as ion beams and EM oscillations which fluid simulations do not exhibit. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability for accelerator and neutron source applications

  4. Improved beam spot measurements in the 2nd generation proton beam writing system

    International Nuclear Information System (INIS)

    Nanosized ion beams (especially proton and helium) play a pivotal role in the field of ion beam lithography and ion beam analysis. Proton beam writing has shown lithographic details down to the 20 nm level, limited by the proton beam spot size. Introducing a smaller spot size will allow smaller lithographic features. Smaller probe sizes, will also drastically improve the spatial resolution for ion beam analysis techniques. Among many other requirements, having an ideal resolution standard, used for beam focusing and a reliable focusing method, is an important pre-requisite for sub-10 nm beam spot focusing. In this paper we present the fabrication processes of a free-standing resolution standard with reduced side-wall projection and high side-wall verticality. The resulting grid is orthogonal (90.0° ± 0.1), has smooth edges with better than 6 nm side-wall projection. The new resolution standard has been used in focusing a 2 MeV H2+ beam in the 2nd generation PBW system at Center for Ion Beam Applications, NUS. The beam size has been characterized using on- and off-axis scanning transmission ion microscopy (STIM) and ion induced secondary electron detection, carried out with a newly installed micro channel plate electron detector. The latter has been shown to be a realistic alternative to STIM measurements, as the drawback of PIN diode detector damage is alleviated. With these improvements we show reproducible beam focusing down to 14 nm

  5. Geometric Metasurface Fork Gratings for Vortex Beam Generation and Manipulation

    CERN Document Server

    Chen, Shumei; Li, Guixin; Zhang, Shuang; Cheah, Kok Wai

    2016-01-01

    In recent years, optical vortex beams possessing orbital angular momentum have caught much attention due to their potential for high capacity optical communications. This capability arises from the unbounded topological charges of orbital angular momentum (OAM) that provides infinite freedoms for encoding information. The two most common approaches for generating vortex beams are through fork diffraction gratings and spiral phase plates. While realization of conventional spiral phase plate requires complicated 3D fabrication, the emerging field of metasurfaces has provided a planar and facile solution for generating vortex beams of arbitrary orbit angular momentum. Here we realize a novel type of geometric metasurface fork grating that seamlessly combine the functionality of a metasurface phase plate for vortex beam generation, and that of a linear phase gradient metasurface for controlling the wave propagation direction. The metasurface fork grating is therefore capable of simultaneously controlling both the...

  6. Generation and transport of laser accelerated ion beams

    International Nuclear Information System (INIS)

    Currently the LIGHT- Project (Laser Ion Generation, Handling and Transport) is performed at the GSI Helmholtzzentrum fuer Schwerionenforschung GmbH Darmstadt. Within this project, intense proton beams are generated by laser acceleration, using the TNSA mechanism. After the laser acceleration the protons are transported through the beam pipe by a pulsed power solenoid. To study the transport a VORPAL 3D simulation is compared with CST simulation. A criterion as a function of beam parameters was worked out, to rate the importance of space charge. Furthermore, an exemplary comparison of the solenoid with a magnetic quadrupole-triplet was carried out. In the further course of the LIGHT-Project, it is planned to generate ion beams with higher kinetic energies, using ultra-thin targets. The acceleration processes that can appear are: RPA (Radiation Pressure Acceleration) and BOA (Break-Out Afterburner). Therefore the transport of an ion distribution will be studied, as it emerges from a RPA acceleration.

  7. Plasma Charge Current for Controlling and Monitoring Electron Beam Welding with Beam Oscillation

    Science.gov (United States)

    Trushnikov, Dmitriy; Belenkiy, Vladimir; Shchavlev, Valeriy; Piskunov, Anatoliy; Abdullin, Aleksandr; Mladenov, Georgy

    2012-01-01

    Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process. PMID:23242276

  8. Modeling and control of plasma rotation for NSTX using Neoclassical Toroidal Viscosity (NTV) and Neutral Beam Injection (NBI)

    Science.gov (United States)

    Goumiri, Imene; Rowley, Clarence; Sabbagh, Steven; Gates, David; Gerhardt, Stefan

    2014-10-01

    A model-based system to control plasma rotation in a magnetically confined toroidal fusion device is developed to maintain plasma stability for long pulse operation. This research uses experimental measurements from the National Spherical Torus Experiment (NSTX) and is aimed to control plasma rotation by using momentum from injected neutral beams and viscosity generated by three-dimensional applied magnetic fields as actuators. Based on the data driven model obtained, a feedback controller is designed to theoretically sustain the toroidal momentum of the plasma in a stable fashion and to achieve desired plasma rotation profiles. On going work includes extending this method to NSTX Upgrade which has more complete radial coverage of the neutral beams momentum sources which enable simultaneous control of plasma stored energy (Beta control).

  9. Staging laser plasma accelerators for increased beam energy

    OpenAIRE

    Panasenko, Dmitriy

    2010-01-01

    Staging laser plasma accelerators is an efficient way of mitigating laser pump depletion in laser driven accelerators and necessary for reaching high energies with compact laser systems. The concept of staging includes coupling of additional laser energy and transporting the electron beam from one accelerating module to another. Due to laser damage threshold constraints, in-coupling laser energy with conventional optics requires distances between the accelerating modules of the order of 10m, ...

  10. Heavy Neutral Beam Probe for Edge Plasma Analysis in Tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Castracane, J.

    2001-01-04

    The Heavy Neutral Beam Probe (HNBP) developed initially with DOE funding under the Small Business Innovation Research (SBIR) program was installed on the Tokamak de Varennes (TdeV) at the CCFM. This diagnostic was designed to perform fundamental measurements of edge plasma properties. The hardware was capable of measuring electron density and potential profiles with high spatial and temporal resolution. Fluctuation spectra for these parameters were obtained with HNBP for transport studies.

  11. Heavy Neutral Beam Probe for Edge Plasma Analysis in Tokamaks

    International Nuclear Information System (INIS)

    The Heavy Neutral Beam Probe (HNBP) developed initially with DOE funding under the Small Business Innovation Research (SBIR) program was installed on the Tokamak de Varennes (TdeV) at the CCFM. This diagnostic was designed to perform fundamental measurements of edge plasma properties. The hardware was capable of measuring electron density and potential profiles with high spatial and temporal resolution. Fluctuation spectra for these parameters were obtained with HNBP for transport studies

  12. Study on nanosecond pulsed electron beam generation

    Science.gov (United States)

    Ponomarev, D.; Kholodnaya, G.; Remnev, G.; Kaikanov, M.; Sazonov, R.

    2014-11-01

    The paper presents the findings of an investigation on volt-ampere characteristics of the diode with explosive emission cathodes of different constructions (blade metal-dielectric (MD-cathode) and solid graphite cathodes) under the change of the anode-cathode gap in wide ranges. The investigations were carried out using the TEA-500 pulsed electron accelerator. The total current of the electron beam was measured using the Faraday cup (FC). A 0.5-mm foiled glass fiber laminate was used as an emitting edge of the cathode in the experimental study with the explosive emission blade MD-cathode. Based on the obtained results, the conclusion was made that the graphite cathode has the most effective efficiency factor.

  13. Study on nanosecond pulsed electron beam generation

    International Nuclear Information System (INIS)

    The paper presents the findings of an investigation on volt-ampere characteristics of the diode with explosive emission cathodes of different constructions (blade metal-dielectric (MD-cathode) and solid graphite cathodes) under the change of the anode-cathode gap in wide ranges. The investigations were carried out using the TEA-500 pulsed electron accelerator. The total current of the electron beam was measured using the Faraday cup (FC). A 0.5-mm foiled glass fiber laminate was used as an emitting edge of the cathode in the experimental study with the explosive emission blade MD-cathode. Based on the obtained results, the conclusion was made that the graphite cathode has the most effective efficiency factor

  14. Energy characteristics of beam-plasma interaction in a closed volume

    Energy Technology Data Exchange (ETDEWEB)

    Klykov, I. L. [Russian Academy of Sciences, Kotel' nikov Institute of Radio Engineering and Electronics (Fryazino Branch) (Russian Federation); Tarakanov, V. P. [Russian Academy of Sciences, Institute for High Energy Densities, Joint Institute for High Temperatures (Russian Federation); Shustin, E. G. [Russian Academy of Sciences, Kotel' nikov Institute of Radio Engineering and Electronics (Fryazino Branch) (Russian Federation)

    2012-03-15

    Energy exchange between an electron beam and plasma during a beam-plasma discharge in a closed cavity excited by the electron beam is analyzed using computer simulations by the KARAT code. A method allowing one to analyze the beam-plasma interaction in the quasi-steady stage of the discharge is proposed. Qualitative characteristics of energy exchange (such as beam energy losses and the energy distributions of beam electrons and plasma particles leaving the discharge) both during spontaneous discharge excitation and in the presence of initial beam modulation by regular or noiselike signals are determined. The results obtained enable one to estimate the energy characteristics of a plasma processing reactor based on a beam-plasma discharge.

  15. Energy characteristics of beam-plasma interaction in a closed volume

    Science.gov (United States)

    Klykov, I. L.; Tarakanov, V. P.; Shustin, E. G.

    2012-03-01

    Energy exchange between an electron beam and plasma during a beam-plasma discharge in a closed cavity excited by the electron beam is analyzed using computer simulations by the KARAT code. A method allowing one to analyze the beam-plasma interaction in the quasi-steady stage of the discharge is proposed. Qualitative characteristics of energy exchange (such as beam energy losses and the energy distributions of beam electrons and plasma particles leaving the discharge) both during spontaneous discharge excitation and in the presence of initial beam modulation by regular or noiselike signals are determined. The results obtained enable one to estimate the energy characteristics of a plasma processing reactor based on a beam-plasma discharge.

  16. Electron Production and Collective Field Generation in Intense Particle Beams

    Energy Technology Data Exchange (ETDEWEB)

    Molvik, A W; Vay, J; Cohen, R; Friedman, A; Lee, E; Verboncoeur, J; Covo, M K

    2006-02-09

    Electron cloud effects (ECEs) are increasingly recognized as important, but incompletely understood, dynamical phenomena, which can severely limit the performance of present electron colliders, the next generation of high-intensity rings, such as PEP-II upgrade, LHC, and the SNS, the SIS 100/200, or future high-intensity heavy ion accelerators such as envisioned in Heavy Ion Inertial Fusion (HIF). Deleterious effects include ion-electron instabilities, emittance growth, particle loss, increase in vacuum pressure, added heat load at the vacuum chamber walls, and interference with certain beam diagnostics. Extrapolation of present experience to significantly higher beam intensities is uncertain given the present level of understanding. With coordinated LDRD projects at LLNL and LBNL, we undertook a comprehensive R&D program including experiments, theory and simulations to better understand the phenomena, establish the essential parameters, and develop mitigating mechanisms. This LDRD project laid the essential groundwork for such a program. We developed insights into the essential processes, modeled the relevant physics, and implemented these models in computational production tools that can be used for self-consistent study of the effect on ion beams. We validated the models and tools through comparison with experimental data, including data from new diagnostics that we developed as part of this work and validated on the High-Current Experiment (HCX) at LBNL. We applied these models to High-Energy Physics (HEP) and other advanced accelerators. This project was highly successful, as evidenced by the two paragraphs above, and six paragraphs following that are taken from our 2003 proposal with minor editing that mostly consisted of changing the tense. Further benchmarks of outstanding performance are: we had 13 publications with 8 of them in refereed journals, our work was recognized by the accelerator and plasma physics communities by 8 invited papers and we have 5

  17. Absolute power scaling measurements of Electromagnetic radiation at 2ω /sub uh/ generated by steady state colliding electron beams

    International Nuclear Information System (INIS)

    Space physics data indicate Electromagnetic (EM) emission correlated with the existence of electron beams in solar and planetary sources. The EM power is too large to be produced by linear plasma production mechanisms, suggesting that non-linear beam processes can coherently, enhance the generation of EM radiation. Steady state counterstreaming electron beams are produced in a triple plasma device, where they collide in a filament discharge target plasma. Neutral pressure is low (5 x 10-5 Torr), with background target density, n /sub e/ less than or equal to 1010 cm-3 and electron temperature T /sub e/ less than or equal to 4 eV . Beams are grid extracted from sources and collimated with a small axial magnetic field (B /sub o/ less than or equal to 10 Gauss). Beam density is n /sub b/ less than or equal to 108 cm-3 and beam energy is E /sub b/ < 150 eV. Plasma ions with varying masses such as He+, Ar+, Xe+ are used. Diagnostics are carried out with electrostatic probes and absolutely calibrated single turn Faraday shielded loop antennae. When counterstreaming electron beams are allowed to collide in the target, steady state electrostatic and electromagnetic disturbances are observed respectively at the upper hybrid frequency and the first harmonic. The colliding beam EM radiation power is seen to be greatly enhanced over that of the single beam case

  18. Spectroscopic Diagnostic of Thermal Plasma Generated in DC Plasma Torch

    Czech Academy of Sciences Publication Activity Database

    Mašláni, Alan; Sember, Viktor

    Kudowa Zdroj, 2005. s. 24-25. [Fifth International Workshop and Summer School „Towards Fusion Energy – Plasma Physics, Diagnostics, Spin-offs“. 6.6.2005-10.6.2005, Kudowa Zdroj] Institutional research plan: CEZ:AV0Z20430508 Keywords : thermal plasma jet * optical emission spectroscopy * nonequilibrium Subject RIV: BL - Plasma and Gas Discharge Physics

  19. Plasmas generated in bubbles immersed in liquids: direct current streamers versus microwave plasma

    Science.gov (United States)

    Levko, Dmitry; Sharma, Ashish; Raja, Laxminarayan L.

    2016-07-01

    Two approaches to generate non-equilibrium atmospheric-pressure plasma in bubbles immersed in liquids are compared using high-fidelity 2D fluid simulations. In the first approach, corona/streamer like plasma is generated using high-voltage negative and positive pulses applied between two electrodes (pin-to-plane geometry) immersed in liquid. In the second, the plasma is generated using a remote microwave source (frequency 2.45 GHz). We find that the microwave approach requires less energy, while generating a denser, more chemically reactive and more uniform plasma within the bubble volume, as compared to the plasma generated using high-voltage pulsing.

  20. Experiments on high-power ion beam generation in self-insulated diodes

    International Nuclear Information System (INIS)

    Experimental results are given on high-power ion beams (HPIB) generation in a vacuum spherical focusing diode with self-magnetic insulation, obtained from the nanosecond accelerator PARUS with 0.2-TW power and 60-ns pulse duration for a matched load. When the passive plasma source of the ions was used, the efficiency of the HPIB generation was measured to be as high as 20% for 700-kV diode voltage and 10-kA/cm2 beam density in the focal plane. The application of a coaxial plasma opening switch (POS) prior to the diode resulted in a factor-of-1.8 increase in the diode power in comparison with a match operation in the absence of a POS. (author)

  1. GeV electron beams from table-top laser-plasma accelerator using capillary waveguides

    International Nuclear Information System (INIS)

    Complete test of publication follows. Conventional particle accelerators for radiation sources, high-energy physics, and other applications are typically limited to accelerating gradients ∼ 50 MV/m to avoid material breakdown, resulting in bulky, expensive machines. A new technology for generating intense energetic electron beam and synchronized femtosecond radiation sources is plasma acceleration using high-peak power, ultrashort-pulse, high energy lasers. The physics, research status, and challenges of laser-plasma accelerators and future radiation sources based on these advanced particle accelerators will be discussed. The radiation pressure of an intense laser pulse drives a space charge wave in fully ionized plasma, producing acceleration gradients on the order of 100 GV/m and micron-wavelength accelerating structures for femtosecond beams. To drive such structures, short pulse lasers are used (40 fs, 40 TW, I = 1018-1019 W/cm2), so that the ponderomotive force resonantly drives the plasma wave (Llaser ∼ c/ωp) in cold, low-density plasmas (Tc ∼ 10 eV, nc ∼ 1018 cm-3). Structured plasmas (channels) are used to guide this drive pulse, maintaining the accelerating field beyond the laser diffraction range. Electron beams of narrow energy spread and good emittance have been produced at several facilities by extending the acceleration distance to match the dephasing length over which the particles outrun the wave. Recently, the acceleration distance has been extended again to cm-scale at LBNL, using channels in a capillary discharge, developed at University of Oxford, and resulting in energies up to 1 GeV. Challenges of applications of laser accelerators include control and reproducibility of the electron beam, scaling to higher energies, and detailed modelling to understand what optimization are available. In particular, injection of particles into the wave must be accurately controlled, and shot to shot variation must be reduced.

  2. Numerical model of the plasma formation at electron beam welding

    International Nuclear Information System (INIS)

    The model of plasma formation in the keyhole in liquid metal as well as above the electron beam welding zone is described. The model is based on solution of two equations for the density of electrons and the mean electron energy. The mass transfer of heavy plasma particles (neutral atoms, excited atoms, and ions) is taken into account in the analysis by the diffusion equation for a multicomponent mixture. The electrostatic field is calculated using the Poisson equation. Thermionic electron emission is calculated for the keyhole wall. The ionization intensity of the vapors due to beam electrons and high-energy secondary and backscattered electrons is calibrated using the plasma parameters when there is no polarized collector electrode above the welding zone. The calculated data are in good agreement with experimental data. Results for the plasma parameters for excitation of a non-independent discharge are given. It is shown that there is a need to take into account the effect of a strong electric field near the keyhole walls on electron emission (the Schottky effect) in the calculation of the current for a non-independent discharge (hot cathode gas discharge). The calculated electron drift velocities are much bigger than the velocity at which current instabilities arise. This confirms the hypothesis for ion-acoustic instabilities, observed experimentally in previous research

  3. Numerical model of the plasma formation at electron beam welding

    Energy Technology Data Exchange (ETDEWEB)

    Trushnikov, D. N., E-mail: trdimitr@yandex.ru [The Department for Applied Physics, Perm National Research Polytechnic University, Perm 614990 (Russian Federation); The Department for Welding Production and Technology of Constructional Materials, Perm National Research Polytechnic University, Perm 614990 (Russian Federation); Mladenov, G. M., E-mail: gmmladenov@abv.bg [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Shose, 1784 Sofia (Bulgaria); Technology Centre of Electron Beam and Plasma Technologies and Techniques, 68-70 Vrania, ap.10, Banishora, 1309 Sofia (Bulgaria)

    2015-01-07

    The model of plasma formation in the keyhole in liquid metal as well as above the electron beam welding zone is described. The model is based on solution of two equations for the density of electrons and the mean electron energy. The mass transfer of heavy plasma particles (neutral atoms, excited atoms, and ions) is taken into account in the analysis by the diffusion equation for a multicomponent mixture. The electrostatic field is calculated using the Poisson equation. Thermionic electron emission is calculated for the keyhole wall. The ionization intensity of the vapors due to beam electrons and high-energy secondary and backscattered electrons is calibrated using the plasma parameters when there is no polarized collector electrode above the welding zone. The calculated data are in good agreement with experimental data. Results for the plasma parameters for excitation of a non-independent discharge are given. It is shown that there is a need to take into account the effect of a strong electric field near the keyhole walls on electron emission (the Schottky effect) in the calculation of the current for a non-independent discharge (hot cathode gas discharge). The calculated electron drift velocities are much bigger than the velocity at which current instabilities arise. This confirms the hypothesis for ion-acoustic instabilities, observed experimentally in previous research.

  4. Microstrip Antenna Generates Circularly Polarized Beam

    Science.gov (United States)

    Huang, J.

    1986-01-01

    Circular microstrip antenna excited with higher order transverse magnetic (TM) modes generates circularly polarized, conical radiation patterns. Found both theoretically and experimentally that peak direction of radiation pattern is varied within wide angular range by combination of mode selection and loading substrate with materials of different dielectric constants.

  5. Helicon waves in uniform plasmas. IV. Bessel beams, Gendrin beams, and helicons

    Science.gov (United States)

    Urrutia, J. M.; Stenzel, R. L.

    2016-05-01

    Electromagnetic waves in the low frequency whistler mode regime are investigated experimentally and by digital data superposition. The radiation from a novel circular antenna array is shown to produce highly collimated helicon beams in a uniform unbounded plasma. The differences to Bessel beams in free space are remarked upon. Low divergence beams arise from the parallel group velocity of whistlers with phase velocity either along the guide field or at the Gendrin angle. Waves with angular momentum are produced by phasing the array in the circular direction. The differences in the field topologies for positive and negative modes numbers are shown. It is also shown that in uniform plasmas, the radial amplitude profile of the waves depends on the antenna field topology. Thus, there are no helicon "eigenmodes" with radial Bessel function profiles in uniform plasmas. It is pointed out that phase measurements in helicon devices indicate radial wave propagation which is inconsistent with helicon eigenmode theory based on paraxial wave propagation. Trivelpiece-Gould modes also exist in uniform unbounded plasmas.

  6. Wave generation and particle transport in the plasma sheet and boundary layer. Semiannual report

    International Nuclear Information System (INIS)

    The one and two ion beam instability was considered as a possible explanation for the observations of broadband electrostatic noise in the plasma sheet region of the geomagnetic tail. When only hot streaming plasma sheet boundary layer ions were present, no broadband waves were excited. Cold, streaming ionospheric ions can generate electrostatic broadband waves propagating in the slow beam-acoustic mode, but the growth rates of the waves were significantly enhanced when warm boundary layer ions were presented. (Both the slow and fast beam-acoustic modes can be excited, depending on the relative ion drift.) This mode predicted that the wave intensity of the broadband noise should peak in the plasma sheet boundary layer (PSBL). Observations of less intense electrostatic waves in the lobes and plasma sheet were likely a result of the absence of warm ion beams or large ion temperatures, respectively, which resulted in smaller growth rates. The model dependence of the ion beam instability has also been studied. For cold and warm ions streaming in the same direction, researchers found wave growth peaked for wave normal angles theta = 0 deg. and wave frequencies approx. 0.1 x the electron plasma frequency. However, for anti-parallel streaming cold and warm ions, wave growth peaks near theta = 90 deg. and wave frequencies were an order of magnitude smaller

  7. Wave generation and particle transport in the plasma sheet and boundary layer

    Science.gov (United States)

    Dusenbery, P. B.

    1987-01-01

    The one and two ion beam instability was considered as a possible explanation for the observations of broadband electrostatic noise in the plasma sheet region of the geomagnetic tail. When only hot streaming plasma sheet boundary layer ions were present, no broadband waves were excited. Cold, streaming ionospheric ions can generate electrostatic broadband waves propagating in the slow beam-acoustic mode, but the growth rates of the waves were significantly enhanced when warm boundary layer ions were presented. (Both the slow and fast beam-acoustic modes can be excited, depending on the relative ion drift.) This mode predicted that the wave intensity of the broadband noise should peak in the plasma sheet boundary layer (PSBL). Observations of less intense electrostatic waves in the lobes and plasma sheet were likely a result of the absence of warm ion beams or large ion temperatures, respectively, which resulted in smaller growth rates. The model dependence of the ion beam instability has also been studied. For cold and warm ions streaming in the same direction, researchers found wave growth peaked for wave normal angles theta = 0 deg. and wave frequencies approx. 0.1 x the electron plasma frequency. However, for anti-parallel streaming cold and warm ions, wave growth peaks near theta = 90 deg. and wave frequencies were an order of magnitude smaller.

  8. Review of neutral beam heating on JET for physics experiments and the production of high fusion performance plasmas

    International Nuclear Information System (INIS)

    The JET neutral beam injection system has proved to be both effective and reliable as a plasma heating device. The ion heating and plasma fuelling characteristics of the system are ideally suited to the production of high fusion performance plasmas while the flexibility in the choice of beam species (H, D, T, 3He or 4He) and the ability to inject into almost any JET plasma configuration allows a wide variety of related physics experiments to be carried out. The capability to inject (for the first time) tritium beams was essential to the successful execution of the first tritium experiments in which 1.7MW of power from D-T fusion reactions was generated. ((orig.))

  9. Necklace beam generation in nonlinear colloidal engineered media.

    Science.gov (United States)

    Silahli, Salih Z; Walasik, Wiktor; Litchinitser, Natalia M

    2015-12-15

    Modulational instability is a phenomenon that reveals itself as the exponential growth of weak perturbations in the presence of an intense pump beam propagating in a nonlinear medium. It plays a key role in such nonlinear optical processes as supercontinuum generation, light filamentation, rogue waves, and ring (or necklace) beam formation. To date, a majority of studies of these phenomena have focused on light-matter interactions in self-focusing Kerr media existing in nature. However, a large and tunable nonlinear response of a colloidal suspension can be tailored at will by judiciously engineering the optical polarizability. Here, we analytically and numerically show the possibility of necklace beam generation originating from spatial modulational instability of vortex beams in engineered soft-matter nonlinear media with different types of exponential nonlinearity. PMID:26670494

  10. Study of plasma natural convection induced by electron beam in atmosphere [

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yongfeng, E-mail: yfdeng@mail.dlut.edu.cn; Han, Xianwei [Shaanxi Power Machine Design and Research Institute, Xi' an 710100 (China); Tan, Yonghua [Academy of Aerospace Propulsion Technology, Xi' an 710100 (China)

    2014-06-15

    Using high-energy electron beams to ionize air is an effective way to produce a large-size plasma in the atmosphere. In particular, with a steady-state high power generator, some unique phenomena can be achieved, including natural convection of the plasma. The characteristics of this convection are studied both experimentally and numerically. The results show that an asymmetrical temperature field develops with magnitudes that vary from 295 K to 389 K at a pressure of 100 Torr. Natural convection is greatly enhanced under 760 Torr. Nevertheless, plasma transport is negligible in this convection flow field and only the plasma core tends to move upward. Parameter analysis is performed to discern influencing factors on this phenomenon. The beam current, reflecting the Rayleigh number Ra effect, correlates with convection intensity, which indicates that energy deposition is the underlying key factor in determining such convections. Finally, natural convection is concluded to be an intrinsic property of the electron beam when focused into dense air, and can be achieved by carefully adjusting equipment operations parameters.

  11. Electron-beam plasma in the production of bioactive agents and drugs

    International Nuclear Information System (INIS)

    The modification of some biopolymers and amino-acids by the Electron-Beam Plasma was studied experimentally. The plasma was generated by injecting the continuous electron beam in gaseous or vapor media. The powders of the substances under consideration were found to change their physical-chemical and biological properties due to the treatment. The aggregation degree of human blood platelets in vitro was chosen as the quantitative characteristics of the biological effect. The untreated compounds were not dissolvable in distilled water at room temperature and did not inhibit the human platelet aggregation. The modified by the Electron-Beam Plasma synthetic derivative of 2-aminopropanoic acid (alanine) was proved to acquire the anti-aggregation activity for platelets. Products of the plasma modified fibrin-monomer were found to be soluble in water at room temperature and reduced the aggregation degree up to ∼ 33-35 % in vitro, treatment in the water EBP being more effective than the treatment in helium

  12. Electron-beam plasma in the production of bioactive agents and drugs

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, M [Moscow Institute of Physics and Technology, Moscow region (Russian Federation); Vasilieva, T [Hematological Scientific Center, Moscow (Russian Federation)

    2006-07-15

    The modification of some biopolymers and amino-acids by the Electron-Beam Plasma was studied experimentally. The plasma was generated by injecting the continuous electron beam in gaseous or vapor media. The powders of the substances under consideration were found to change their physical-chemical and biological properties due to the treatment. The aggregation degree of human blood platelets in vitro was chosen as the quantitative characteristics of the biological effect. The untreated compounds were not dissolvable in distilled water at room temperature and did not inhibit the human platelet aggregation. The modified by the Electron-Beam Plasma synthetic derivative of 2-aminopropanoic acid (alanine) was proved to acquire the anti-aggregation activity for platelets. Products of the plasma modified fibrin-monomer were found to be soluble in water at room temperature and reduced the aggregation degree up to {approx} 33-35 % in vitro, treatment in the water EBP being more effective than the treatment in helium.

  13. Generation and Beaming of Early Hot Electrons onto the Capsule in Laser-Driven Ignition Hohlraums

    Science.gov (United States)

    Dewald, E. L.; Hartemann, F.; Michel, P.; Milovich, J.; Hohenberger, M.; Pak, A.; Landen, O. L.; Divol, L.; Robey, H. F.; Hurricane, O. A.; Döppner, T.; Albert, F.; Bachmann, B.; Meezan, N. B.; MacKinnon, A. J.; Callahan, D.; Edwards, M. J.

    2016-02-01

    In hohlraums for inertial confinement fusion (ICF) implosions on the National Ignition Facility, suprathermal hot electrons, generated by laser plasma instabilities early in the laser pulse ("picket") while blowing down the laser entrance hole (LEH) windows, can preheat the capsule fuel. Hard x-ray imaging of a Bi capsule surrogate and of the hohlraum emissions, in conjunction with the measurement of time-resolved bremsstrahlung spectra, allows us to uncover for the first time the directionality of these hot electrons and infer the capsule preheat. Data and Monte Carlo calculations indicate that for most experiments the hot electrons are emitted nearly isotropically from the LEH. However, we have found cases where a significant fraction of the generated electrons are emitted in a collimated beam directly towards the capsule poles, where their local energy deposition is up to 10 × higher than the average preheat value and acceptable levels for ICF implosions. The observed "beaming" is consistent with a recently unveiled multibeam stimulated Raman scattering model [P. Michel et al., Phys. Rev. Lett. 115, 055003 (2015)], where laser beams in a cone drive a common plasma wave on axis. Finally, we demonstrate that we can control the amount of generated hot electrons by changing the laser pulse shape and hohlraum plasma.

  14. Geometric Metasurface Fork Gratings for Vortex Beam Generation and Manipulation

    OpenAIRE

    Chen, Shumei; Cai, Yuan; Li, Guixin; Shuang ZHANG; Cheah, Kok Wai

    2016-01-01

    In recent years, optical vortex beams possessing orbital angular momentum have caught much attention due to their potential for high capacity optical communications. This capability arises from the unbounded topological charges of orbital angular momentum (OAM) that provides infinite freedoms for encoding information. The two most common approaches for generating vortex beams are through fork diffraction gratings and spiral phase plates. While realization of conventional spiral phase plate re...

  15. Electron Beam Collimation for the Next Generation Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Steier, C.; Emma, P.; Nishimura, H.; Papadopoulos, C.; Sannibale, F.

    2013-05-20

    The Next Generation Light Source will deliver high (MHz) repetition rate electron beams to an array of free electron lasers. Because of the significant average current in such a facility, effective beam collimation is extremely important to minimize radiation damage to undulators, prevent quenches of superconducting cavities, limit dose rates outside of the accelerator tunnel and prevent equipment damage. This paper describes the early conceptual design of a collimation system, as well as initial results of simulations to test its effectiveness.

  16. Thermal Plasma Generators with Water Stabilized Arc

    Czech Academy of Sciences Publication Activity Database

    Hrabovský, Milan

    2009-01-01

    Roč. 2, č. 1 (2009), s. 99-104. ISSN 1876-5343 R&D Projects: GA ČR GA202/08/1084 Institutional research plan: CEZ:AV0Z20430508 Keywords : Thermal plasma * plasma torch * Gerdien arc Subject RIV: BL - Plasma and Gas Discharge Physics http://www.bentham.org/open/toppj/openaccess2.htm

  17. Overview of laser-driven generation of electron-positron beams

    Science.gov (United States)

    Sarri, G.; Dieckmann, M. E.; Kourakis, I.; di Piazza, A.; Reville, B.; Keitel, C. H.; Zepf, M.

    2015-08-01

    Electron-positron (e-p) plasmas are widely thought to be emitted, in the form of ultra-relativistic winds or collimated jets, by some of the most energetic or powerful objects in the Universe, such as black-holes, pulsars, and quasars. These phenomena represent an unmatched astrophysical laboratory to test physics at its limit and, given their immense distance from Earth (some even farther than several billion light years), they also provide a unique window on the very early stages of our Universe. However, due to such gigantic distances, their properties are only inferred from the indirect interpretation of their radiative signatures and from matching numerical models: their generation mechanism and dynamics still pose complicated enigmas to the scientific community. Small-scale reproductions in the laboratory would represent a fundamental step towards a deeper understanding of this exotic state of matter. Here we present recent experimental results concerning the laser-driven production of ultra-relativistic e-p beams. In particular, we focus on the possibility of generating beams that present charge neutrality and that allow for collective effects in their dynamics, necessary ingredients for the testing pair-plasma physics in the laboratory. A brief discussion of the analytical and numerical modelling of the dynamics of these plasmas is also presented in order to provide a summary of the novel plasma physics that can be accessed with these objects. Finally, general considerations on the scalability of laboratory plasmas up to astrophysical scenarios are given.

  18. Bunch beam production and microwave generation in reditrons

    International Nuclear Information System (INIS)

    The authors have discovered in our two-dimensional particle-in-cell simulations that the oscillation of virtual cathodes in reditrons can produce a highly modulated electron beam. Full (100%) current modulation of the leakage electron beam was observed in our simulations. The modulation is at the frequency of the oscillating virtual cathode and the transverse magnetic mode generated by the reditron. The authors have further incorporated an inverse diode with a line impedance of 50 ohms in the reditron and showed that 28% of the kinetic energy of the modulated electron beam was converted into transverse electromagnetic waves with peak power of 1 GW

  19. Bunch beam production and microwave generation in reditrons

    Energy Technology Data Exchange (ETDEWEB)

    Kwan, T.J.T.; Davis, H.A.; Fulton, R.D.; Sherwood, E.G.

    1989-01-01

    We have discovered in our two-dimensional particle-in-cell simulations that the oscillation of virtual cathodes in reditrons can produce a highly modulated electron beam. Full (100%) current modulation of the leakage electron beam was observed in our simulations. The modulation is at the frequency of the oscillating virtual cathode and the transverse magnetic mode generated by the reditron. We had further incorporated an inverse diode in the reditron and showed that the kinetic energy of the modulated electron beam was efficiently converted into transverse electromagnetic waves. Our simulations showed an efficiency of 26% and the time averaged microwave power was about 6 GW. 7 refs., 8 figs.

  20. Bunch Beam Production And Microwave Generation In Reditrons

    Science.gov (United States)

    Kwan, Thomas J. T.; Davis, Harold A.; Fulton, Robert D.; Sherwood, Eugene G.

    1989-07-01

    We have discovered in our two-dimensional particle-in-cell simulations that the oscillation of virtual cathodes in reditrons can produce a highly modulated electron beam. Full (100%) current modulation of the leakage electron beam was observed in our simulations. The modulation is at the frequency of the oscillating virtual cathode and the transverse magnetic mode generated by the reditron. We had further incorporated an inverse diode with a line impedance of 50 ohms in the reditron and showed that 28% of the kinetic energy of the modulated electron beam was converted into transverse electromagnetic waves with peak power of 1 GW.

  1. Characterization of the equilibrium configuration for modulated beams in a plasma wakefield accelerator

    CERN Document Server

    Martorelli, Roberto

    2016-01-01

    We analyze the equilibrium configuration for a modulated beam with sharp boundaries exposed to the fields self-generated by the interaction with a plasma. Through a semi-analytical approach we show the presence of multiple equilibrium configurations and we determine the one more suitable for wakefield excitation. Once pointed out the absence of confinement for the front of the beam and the consequently divergence driven by the emittance, we study the evolution of the equilibrium configuration while propagating in the plasma, discarding all the others time-dependencies. We show the onset of a rigid backward drift of the equilibrium configuration and we provide an explanation in the increasing length of the first bunch.

  2. Modeling of energy transfer between two crossing smoothed laser beams in a plasma with flow profile

    Science.gov (United States)

    Colaitis, A.; Hüller, S.; Tikhonchuk, V. T.; Pesme, D.; Duchateau, G.; Porzio, A.

    2016-05-01

    We study the crossed beam energy transfer (CBET) between laser fields generated by optical smoothing methods. The energy transfer, as well as the angular distribution of the outgoing light fields are investigated for two incident smoothed laser beams in a plasma with a flow gradient, allowing for resonant transfer close to the sonic point. Simulations with the code HARMONY based on time-dependent paraxial light propagation are compared to simulations using a new approach based on paraxial complex geometrical optics (PCGO). Both approaches show good agreement for the average energy transfer past a short transient period, which is a promising result for the use of the PCGO method as a module within a hydrodynamics code to efficiently compute CBET in mm-scale plasma configurations. Statistical aspects related to role of laser speckles in CBET are considered via an ensemble of different phase plate realizations.

  3. Factors responsible for biomaterials modification in the electron-beam plasma

    International Nuclear Information System (INIS)

    The modification of some biomaterials by the Electron-Beam Plasma was studied experimentally. The powder of the fibrin-monomer (the natural protein which is contained in the blood of mammalians) was treated in the plasma generated by injecting the continuous electron beam in gaseous or vapor media. The fibrin-monomer was found to change its physical-chemical and biological properties due to the treatment. In particular, being modified the fibrin-monomer reduced the human platelet aggregation degree in vitro to ∼ 33-35 %, whereas the untreated compound did not inhibit the aggregation. Both experiments and computer simulation were carried out to separate plasmachemical effects from other factors acting on the sample during thee treatment (β-irradiation, UV- and X-ray radiation, heating). The study showed the fibrin-monomer to acquire the anti-aggregation activity due to combined action of all factors mentioned above but the plasmachemical processes are predominant

  4. Factors responsible for biomaterials modification in the electron-beam plasma

    Energy Technology Data Exchange (ETDEWEB)

    Vasilieva, T; Lysenko, S [Moscow Institute of Physics and Technology, Moscow region (Russian Federation)

    2007-04-15

    The modification of some biomaterials by the Electron-Beam Plasma was studied experimentally. The powder of the fibrin-monomer (the natural protein which is contained in the blood of mammalians) was treated in the plasma generated by injecting the continuous electron beam in gaseous or vapor media. The fibrin-monomer was found to change its physical-chemical and biological properties due to the treatment. In particular, being modified the fibrin-monomer reduced the human platelet aggregation degree in vitro to {approx} 33-35 %, whereas the untreated compound did not inhibit the aggregation. Both experiments and computer simulation were carried out to separate plasmachemical effects from other factors acting on the sample during thee treatment ({beta}-irradiation, UV- and X-ray radiation, heating). The study showed the fibrin-monomer to acquire the anti-aggregation activity due to combined action of all factors mentioned above but the plasmachemical processes are predominant.

  5. Fusion reactions initiated by laser-accelerated particle beams in a laser-produced plasma

    CERN Document Server

    Labaune, C; Depierreux, S; Goyon, C; Loisel, G; Yahia, V; Rafelski, J

    2013-01-01

    The advent of high-intensity pulsed laser technology enables the generation of extreme states of matter under conditions that are far from thermal equilibrium. This in turn could enable different approaches to generating energy from nuclear fusion. Relaxing the equilibrium requirement could widen the range of isotopes used in fusion fuels permitting cleaner and less hazardous reactions that do not produce high energy neutrons. Here we propose and implement a means to drive fusion reactions between protons and boron-11 nuclei, by colliding a laser-accelerated proton beam with a laser-generated boron plasma. We report proton-boron reaction rates that are orders of magnitude higher than those reported previously. Beyond fusion, our approach demonstrates a new means for exploring low-energy nuclear reactions such as those that occur in astrophysical plasmas and related environments.

  6. Fusion reactions initiated by laser-accelerated particle beams in a laser-produced plasma

    International Nuclear Information System (INIS)

    The advent of high-intensity-pulsed laser technology enables the generation of extreme states of matter under conditions that are far from thermal equilibrium. This in turn could enable different approaches to generating energy from nuclear fusion. Relaxing the equilibrium requirement could widen the range of isotopes used in fusion fuels permitting cleaner and less hazardous reactions that do not produce high-energy neutrons. Here we propose and implement a means to drive fusion reactions between protons and boron-11 nuclei by colliding a laser-accelerated proton beam with a laser-generated boron plasma. We report proton-boron reaction rates that are orders of magnitude higher than those reported previously. Beyond fusion, our approach demonstrates a new means for exploring low-energy nuclear reactions such as those that occur in astrophysical plasmas and related environments. (authors)

  7. Characterization of a channel spark discharge and the generated electron beam

    International Nuclear Information System (INIS)

    We report on an experimental study of a channel spark discharge (CSD) and the generated electron beam. The CSD was operated at a discharge voltage Ud≤30 kV and a discharge current Id≤3.5 kA. The CSD system consists of a glass tube placed between a hollow cathode and a grounded anode electrode. The parameters of the CSD operation, the potential distribution along the glass tube, and the generated beam were studied by electrical, optical, and spectroscopic diagnostics in the Ar gas pressure range of P=0.005-2 Pa. At P≥0.5 Pa, electrons with energy ∼eUd appeared prior to the start of the main CSD with a current amplitude ≤10-4Id. These high-energy electrons are responsible for the initiation of the CSD inside the glass tube. The generation of the electron beam which was composed of low-energy electrons with a current amplitude up to 3 kA occurred during a fast fall in the discharge voltage. Decreasing the Ar gas pressure below 0.1 Pa allows one to increase significantly the beam duration and the part of the high-energy electrons in the beam, and to increase the efficiency of the electron beam generation up to 75%. The high-current CSD inside the glass tube is accompanied by the formation of a plasma consisting of protons, Ar II, Ar III, C II-IV, and O II-IV ions. The plasma electron density and temperature were found to be in the ranges of 1015-1016 cm-3 and 10-15 eV, respectively

  8. Collective acceleration of protons by the plasma waves in a counterstreaming electron beam

    International Nuclear Information System (INIS)

    A novel advanced accelerator is proposed. The counterstreaming electron beam accelerator relies on the same physical mechanism as that of the plasma accelerator but replaces the stationary plasma in the plasma accelerator by a magnetized relativistic electron beam, drifting antiparallel to the driving source and the driven particles, as the wave supporting medium. The plasma wave in a counterstreaming electron beam can be excited either by a density-ramped driving electron beam or by properly beating two laser beams. The fundamental advantages of the counterstreaming electron beam accelerator over the plasma accelerator are a longer and tunable plasma wavelength, a longer pump depletion length or a larger transformer ratio, and easier pulse shaping for the driving source and the driven beam. Thus the energy gain of the driven particles can be greatly enhanced whereas the trapping threshold can be dramatically reduced so as to admit the possibility for proton acceleration

  9. Growth and phase velocity of self-modulated beam-driven plasma waves

    Energy Technology Data Exchange (ETDEWEB)

    Benedetti, Carlo; Esarey, Eric; Gruener, Florian; Leemans, Wim

    2011-09-20

    A long, relativistic particle beam propagating in an overdense plasma is subject to the self-modulation instability. This instability is analyzed and the growth rate is calculated, including the phase relation. The phase velocity of the wake is shown to be significantly less than the beam velocity. These results indicate that the energy gain of a plasma accelerator driven by a self-modulated beam will be severely limited by dephasing. In the long-beam, strongly-coupled regime, dephasing is reached in a homogeneous plasma in less than four e-foldings, independent of beam-plasma parameters.

  10. Three-Dimensional PIC-MC Modeling for Relativistic Electron Beam Transport Through Dense Plasma

    Institute of Scientific and Technical Information of China (English)

    CAO Lihua; CHANG Tieqiang; PEI Wenbing; LIU Zhanjun; LI Meng; ZHENG Chunyang

    2008-01-01

    We have developed a three dimensional (3D) PIC (particle-in-cell)-MC (Monte Carlo) code in order to simulate an electron beam transported into the dense matter based on our previous two dimensional code. The relativistic motion of fast electrons is treated by the particle-in-cell method under the influence of both a self-generated transverse magnetic field and an axial electric field, as well as collisions. The electric field generated by return current is ex-pressed by Ohm's law and the magnetic field is calculated from Faraday's law. The slowing down of monoenergy electrons in DT plasma is calculated and discussed.

  11. Heavy Neutral Beam Probe for edge plasma analysis in Tokamaks

    International Nuclear Information System (INIS)

    The contents of this report present the progress achieved to date on the Heavy Neutral Beam Probe project. This effort is an international collaboration in magnetic confinement fusion energy research sponsored by the US Department of Energy, Office of Energy Research (Confinement Systems Division) and the Centre Canadien de Fusion Magnetique (CCFM). The overall objective of the effort is to develop and apply a neutral particle beam to the study of edge plasma dynamics in discharges on the Tokamak de Varennes (TdeV) facility in Montreal, Canada. To achieve this goal, a research and development project was established to produce the necessary hardware to make such measurements and meet the scheduling requirements of the program. At present the project is in the middle of its second budget period with the instrumentation on-site at TdeV. The first half of this budget period was used to complete total system tests at InterScience, Inc., dismantle and ship the hardware to TdeV, re-assemble and install the HNBP on the tokamak. Integration of the diagnostic into the TdeV facility has progressed to the point of first beam production and measurement on the plasma. At this time, the HNBP system is undergoing final de-bugging prior to re-start of machine operation in early Fall of this year

  12. Propagation of a beam of hot electrons through solar wind plasma with generalized (r,q) distribution function

    Science.gov (United States)

    Khalilpour, H.

    2016-08-01

    The background plasma is assumed to have generalized (r, q) distribution for the electrons in the solar wind. The propagation of a beam of hot electrons through solar wind plasma with generalized (r,q) distribution and the generation of Langmuir waves are simulated using quasilinear equations. It is shown that spectral indices r and q affect the quasilinear dynamics of the beam and Langmuir waves. The damping of beam generated waves increases in (r,q) distributed plasma. As indices r and q increase the system shows quasilinear behavior which is more similar to the Maxwellian distribution function. The value of average velocity of the beam increases in a plasma with (r, q) distribution function and as the values of r and q increase, the average velocity of the beam decreases. It is also shown that the gas-dynamical parameters of the beam are functions of spectral indices r and q. The upper boundary of the plateau, and local velocity spread are increasing functions while the lower boundary and height of plateau are decreasing functions of r and q. The local velocity shows smooth behavior with respect to spectral indices r and q, and for all indices at given time and position has approximately same values.

  13. The sputter generation of negative ion beams

    International Nuclear Information System (INIS)

    A brief review is given of recent progress toward a quantitative understanding of negative ion formation by sputtering from surfaces covered with fractional layers of highly electropositive adsorbates. Practical models developed for estimating changes in work functions Δφ by electropositive adsorbates are described. The secondary negative ion generation process is examined through the use of composite energy/velocity dependent analytical models. These models are used to illustrate the effect of work function on the energy distributions of negative ions sputter ejected from a polycrystalline molybdenum surface covered with fractional layers of cesium. Predictions are also made of the functional dependence of the probability for negative ion formation on cesium coverage. The models predict energy distributions which are in basic disagreement with experimental observations, implying their inappropriateness for describing the sputter negative ion generation process. We have also developed a model for calculating sputter ratios based on the use of simple scaling procedures to bring Sigmund theory into close agreement with experimental observation accounting for the threshold effect. Scaling factors for projectile energies E > 1000 eV are found to be independent of energy while those for projectile energies Eth < E < 1000 eV were found to be energy dependent. In this study, the model and scaling techniques utilized to bring Sigmund theory into agreement with experiment are discussed in detail and several examples provided which illustrate the versatility, accuracy and utility of the model. In the present report, we describe the model and apply it to the case of sputtering a selected number of metals with energetic cesium ions. In particular, we present sputter ratio information for a number of Cs-projectile/metal-target combinations; the targets are bombarded at normal incidence to the surface

  14. Focused neutral beams with low chaotic divergence for plasma heating and diagnostics in magnetic fusion devices

    International Nuclear Information System (INIS)

    A series of neutral beam injectors has been developed in the Budker Institute of Nuclear Physics for plasma heating and diagnostics in modern fusion devices. Ion optical system of these injectors is optimized to produce ion beams with low angular divergence. In order to provide beam focusing, the grids are formed to be spherical segments. Such geometrically focused neutral beams are particularly advantageous for plasma diagnostics when high spatial resolution is required. Another application of these beams is plasma heating in the machines with narrow ports through which only small size, high power density beams can be transported. (author)

  15. Development of Raman-shifted probe laser beam for plasma diagnosis using polaro-interferometer

    Indian Academy of Sciences (India)

    M P Kamath; A P Kulkarni; S Jain; P K Tripathi; A S Joshi; P A Naik; P D Gupta

    2010-11-01

    Optical diagnostics of laser-produced plasma requires a coherent, polarized probe beam synchronized with the pump beam. The probe beam should have energy above the background emission of plasma. Though the second harmonic probe beam satisfies most of the requirements, the plasma emission is larger at the harmonic frequencies of the pump. Hence, at high intensities we need a probe beam at non-harmonic frequencies. We have set up a Raman frequency shifted probe beam using a pressurized hydrogen cell that is pumped by the second harmonic of the Nd glass laser that operates at only one Stokes line of 673.75 nm.

  16. Nonlinear Interaction of Elliptical Laser Beam with Collisional Plasma: Effect of Linear Absorption

    Science.gov (United States)

    Keshav, Walia; Sarabjit, Kaur

    2016-01-01

    In the present work, nonlinear interaction of elliptical laser beam with collisional plasma is studied by using paraxial ray approximation. Nonlinear differential equations for the beam width parameters of semi-major axis and semi-minor axis of elliptical laser beam have been set up and solved numerically to study the variation of beam width parameters with normalized distance of propagation. Effects of variation in absorption coefficient and plasma density on the beam width parameters are also analyzed. It is observed from the analysis that extent of self-focusing of beam increases with increase/decrease in plasma density/absorption coefficient.

  17. Impact of the thermal lens effect in atmospheric pressure DBD-plasma columns on coaxially guided laser beams

    Science.gov (United States)

    Hoffmeister, J.; Brückner, S.; Gerhard, C.; Wieneke, S.; Viöl, W.

    2014-12-01

    The combination of laser and low-temperature plasmas is of growing interest for micro-structuring purposes for a wide range of materials. This combination can be used for a reduction of the ablation threshold as well as an improvement of the machining quality in various laser material processing applications. The plasma involved in such combination, however, leads to a thermally generated influence on the laser beam quality. In this paper, a DBD-based argon plasma as typically used in low-temperature laser plasma hybrid arrangements was investigated by interferometric and beam profile measurements. The radial temperature profile as well as the beam propagation characteristics in terms of focal shift and effective pointing stability was determined. Due to the argon plasma, a temperature increase ΔT by up to 25 K, and thus a thermal lens was observed within the light path of the laser beam featuring an increase in refractive index Δn by maximum 2.86 × 10-5. In the given setup, the plasma-induced thermal lens caused a focal shift by up to 4 mm. Further, the lateral focus position was deviated by a maximum of about 30 µm, which is in the order of magnitude of the beam waist radius.

  18. First Optical Observation of Intensity Dependent Laser Beam Deflection in a Flowing Plasma

    International Nuclear Information System (INIS)

    The intensity dependent deflection of a laser beam traversing an exploding foil plasma is measured for the first time. An incident f/8 probe beam exhibits deflection of up to 6 degree and angular spreading of as much as a 17 degree cone angle (f/3.3) as it exits a preformed plasma with significant plasma flow. copyright 1996 The American Physical Society

  19. Angular-momentum-dominated electron beams and flat-beam generation

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yin-e

    2005-06-01

    In the absence of external forces, if the dynamics within an electron beam is dominated by its angular momentum rather than other effects such as random thermal motion or self Coulomb-repulsive force (i.e., space-charge force), the beam is said to be angular-momentum-dominated. Such a beam can be directly applied to the field of electron-cooling of heavy ions; or it can be manipulated into an electron beam with large transverse emittance ratio, i.e., a flat beam. A flat beam is of interest for high-energy electron-positron colliders or accelerator-based light sources. An angular-momentum-dominated beam is generated at the Fermilab/NICADD photoinjector Laboratory (FNPL) and is accelerated to an energy of 16 MeV. The properties of such a beam is investigated systematically in experiment. The experimental results are in very good agreement with analytical expectations and simulation results. This lays a good foundation for the transformation of an angular-momentum-dominated beam into a flat beam. The round-to-flat beam transformer is composed of three skew quadrupoles. Based on a good knowledge of the angular-momentum-dominated beam, the quadrupoles are set to the proper strengths in order to apply a total torque which removes the angular momentum, resulting in a flat beam. For bunch charge around 0.5 nC, an emittance ratio of 100 {+-} 5 was measured, with the smaller normalized root-mean-square emittance around 0.4 mm-mrad. Effects limiting the flat-beam emittance ratio are investigated, such as the chromatic effects in the round-to-flat beam transformer, asymmetry in the initial angular-momentum-dominated beam, and space-charge effects. The most important limiting factor turns out to be the uncorrelated emittance growth caused by space charge when the beam energy is low, for example, in the rf gun area. As a result of such emittance growth prior to the round-to-flat beam transformer, the emittance ratio achievable in simulation decreases from orders of thousands to

  20. Plasma-filled rippled wall rectangular backward wave oscillator driven by sheet electron beam

    Indian Academy of Sciences (India)

    A Hadap; J Mondal; K C Mittal; K P Maheshwari

    2011-03-01

    Performance of the backward wave oscillator (BWO) is greatly enhanced with the introduction of plasma. Linear theory of the dispersion relation and the growth rate have been derived and analysed numerically for plasma-filled rippled wall rectangular waveguide driven by sheet electron beam. To see the effect of plasma on the TM01 cold wave structure mode and on the generated frequency, the parameters used are: relativistic factor = 1.5 (i.e. / = 0.741), average waveguide height 0 = 1.445 cm, axial corrugation period 0 = 1.67 cm, and corrugation amplitude = 0.225 cm. The plasma density is varied from zero to 2 × 1012 cm-3. The presence of plasma tends to raise the TM01 mode cut-off frequency (14 GH at 2 × 1012 cm-3 plasma density) relative to the vacuum cut-off frequency (5 GH) which also causes a decrease in the group velocity everywhere, resulting in a flattening of the dispersion relation. With the introduction of plasma, an enhancement in absolute instability was observed.

  1. Study on the transport of a relativistic electron beam in plasmas

    Science.gov (United States)

    Cai, Hong-bo; Zhu, Shao-ping; He, X. T.

    2016-03-01

    In the fast ignition scheme, in order to deliver enough energy (10kJ) into the pellet in 10ps, the ignition laser beam should reach the intensity of I 0 ∼ 1020 W/cm 2 if the coupling from the laser to the core plasma is about 20% for a well-collimated beam. However, studies have shown that the electron divergence increases with the laser intensity. Of particular importance is the possibility of collimating the fast electron beams with the size of the compressed core. In this work, we will introduce two ways to obtain the collimated electrons: 1) collimate fast electrons in specially engineered targets with the spontaneously generated magnetic field during its transportation; 2) collimate fast electrons with imposed magnetic field.

  2. Simulative research on the anode plasma dynamics in the high-power electron beam diode

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Dan; Liu, Lie; Ju, Jin-Chuan; Zhang, Tian-Yang; Zhao, Xue-Long; Zhou, Hong-Yu [College of Optoelectric Science and Engineering, National University of Defense Technology, Hunan 410073 (China)

    2015-07-15

    Anode plasma generated by electron beams could limit the electrical pulse-length, modify the impedance and stability of diode, and affect the generator to diode power coupling. In this paper, a particle-in-cell code is used to study the dynamics of anode plasma in the high-power electron beam diode. The effect of gas type, dynamic characteristic of ions on the diode operation with bipolar flow model are presented. With anode plasma appearing, the amplitude of diode current is increased due to charge neutralizations of electron flow. The lever of neutralization can be expressed using saturation factor. At same pressure of the anode gas layer, the saturation factor of CO{sub 2} is bigger than the H{sub 2}O vapor, namely, the generation rate of C{sup +} ions is larger than the H{sup +} ions at the same pressure. The transition time of ions in the anode-cathode gap could be used to estimate the time of diode current maximum.

  3. Towards Spectral Control of Laser-Driven Ion Beams Generated in the Relativistic Transparency Regime

    Science.gov (United States)

    Fernandez, Juan C.; Gautier, D. C.; Hamilton, C.; Huang, C.; Palaniyappan, S.

    2014-10-01

    Until recently, experiments on the LANL Trident laser in the relativistic transparency regime have demonstrated efficient, volumetric acceleration of the bulk target ions to high energies by the laser-plasma interaction, but with broad ion-energy distributions. That ion acceleration mechanism (Breakout Afterburner) is intrinsically capable of producing quasi-monoenergetic ion-energy distributions. However, there are processes responsible for energy spread, both during the laser-plasma interaction with present-day experimental conditions, as well as during the subsequent transport of the beam, driven by expansion of the co-moving hot-electron population. Strategies to counter such spread are discussed. Furthermore, our work to understand the recent observation of efficiently-generated, quasi-monoenergetic, ~150 MeV Al-ion beams indicates that the dynamics immediately following the laser-plasma interaction can be quite important and beneficial. It has uncovered a new strategy, i.e., using plasma-electron dynamics to increase the ion energy and to decrease its spread. This presentation thus motivates and frames two companion talks on these laser-driven Al-ion beams by Palaniyappan et al. and Huang et al. in this conference. This work is sponsored by the LANL LDRD Program.

  4. Collective Modes in Neutrino `Beam' Electron-Positron Plasma Interactions

    CERN Document Server

    Elze, H T; Opher, R

    2001-01-01

    We derive semiclassical neutrino-electron transport equations in the collisionless (Vlasov) limit from the coupled Dirac equations, incorporating the charged and neutral weak current-current as well as electromagnetic interactions. A corresponding linear response theory is derived. In particular, we calculate the response functions for a variety of beam-plasma geometries, which are of interest in a supernova scenario. We apply this to the study of plasmons and to a new class of collective {\\it pharon} resonance modes, which are characterized by $\\omega < q$. We find that the growth rates of the unstable modes correspond to a strongly temperature ($\\propto T_\

  5. Axial magnetic field generation by intense circularly polarized laser pulses in underdense plasmas

    International Nuclear Information System (INIS)

    Axial magnetic field generation by intense circularly polarized laser beams in underdense plasmas has been studied with three-dimensional particle-in-cell simulations and by means of theoretical analysis. Comparisons between analytical models and simulation results have identified an inverse Faraday effect as the main mechanism of the magnetic field generation in inhomogeneous plasmas. The source of azimuthal nonlinear currents and of the axial magnetic field depends on the transverse inhomogeneities of the electron density and laser intensity. The fields reach a maximum strength of several tens of megagauss for laser pulses undergoing relativistic self-focusing and channeling in moderately relativistic regime. Ultrarelativistic laser conditions inhibit magnetic field generation by directly reducing a source term and by generating fully evacuated plasma channels.

  6. Research progress on ionic plasmas generated in an intense hydrogen negative ion source

    Energy Technology Data Exchange (ETDEWEB)

    Takeiri, Y., E-mail: takeiri@nifs.ac.jp; Tsumori, K.; Nagaoka, K.; Kaneko, O. [National Institute for Fusion Science, Toki 509-5292 (Japan); School of Physical Sciences, The Graduate University for Advanced Studies, Toki 509-5292 (Japan); Ikeda, K.; Nakano, H.; Kisaki, M.; Tokuzawa, T.; Osakabe, M.; Kondo, T.; Sato, M.; Shibuya, M.; Komada, S.; Sekiguchi, H. [National Institute for Fusion Science, Toki 509-5292 (Japan); Geng, S. [School of Physical Sciences, The Graduate University for Advanced Studies, Toki 509-5292 (Japan)

    2015-04-08

    Characteristics of ionic plasmas, observed in a high-density hydrogen negative ion source, are investigated with a multi-diagnostics system. The ionic plasma, which consists of hydrogen positive- and negative-ions with a significantly low-density of electrons, is generated in the ion extraction region, from which the negative ions are extracted through the plasma grid. The negative ion density, i.e., the ionic plasma density, as high as the order of 1×10{sup 17}m{sup −3}, is measured with cavity ring-down spectroscopy, while the electron density is lower than 1×10{sup 16}m{sup −3}, which is confirmed with millimeter-wave interferometer. Reduction of the negative ion density is observed at the negative ion extraction, and at that time the electron flow into the ionic plasma region is observed to conserve the charge neutrality. Distribution of the plasma potential is measured in the extraction region in the direction normal to the plasma grid surface with a Langmuir probe, and the results suggest that the sheath is formed at the plasma boundary to the plasma grid to which the bias voltage is applied. The beam extraction should drive the negative ion transport in the ionic plasma across the sheath formed on the extraction surface. Larger reduction of the negative ions at the beam extraction is observed in a region above the extraction aperture on the plasma grid, which is confirmed with 2D image measurement of the Hα emission and cavity ring-down spectroscopy. The electron distribution is also measured near the plasma grid surface. These various properties observed in the ionic plasma are discussed.

  7. Modelling the spatial shape of nondiffracting beams: Experimental generation of Frozen Waves via computer generated holograms

    CERN Document Server

    Vieira, Tárcio A; Gesualdi, Marcos R R

    2013-01-01

    In this paper we implement experimentally the spatial shape modelling of nondiffracting optical beams via computer generated holograms. The results reported here are the experimental confirmation of the so called Frozen Wave method, developed few years ago. Optical beams of this type can possess potential applications in optical tweezers, medicine, atom guiding, remote sensing, etc..

  8. High-current lanthanum-hexaboride electron emitter for a quasi-stationary arc plasma generator

    Energy Technology Data Exchange (ETDEWEB)

    Davydenko, V. I., E-mail: V.I.Davydenko@inp.nsk.su; Ivanov, A. A., E-mail: A.A.Ivanov@inp.nsk.su; Shul’zhenko, G. I. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

    2015-11-15

    A high-current electron emitter on the basis of lanthanum hexaboride is developed for quasi-stationary arc plasma generators of ion sources. The emitter consists of a set of LaB{sub 6} washers interleaved with washers made of thermally extended graphite. The emitter is heated by the current flowing through the graphite washers. The thermal regime of emitter operation during plasma generation is considered. The emitter has been successfully used in the ion sources of the diagnostic injectors of fast hydrogen atomic beams.

  9. Early hot electrons generation and beaming in ICF gas filled hohlraums at the National Ignition Facility

    Science.gov (United States)

    Dewald, Eduard; Michel, Pierre; Hartemann, Fred; Milovich, Jose; Hohenberger, Matthias; Divol, Laurent; Landen, Otto; Pak, Arthur; Thomas, Cliff; Doeppner, Tilo; Bachmann, Benjamin; Meezan, Nathan; MacKinnon, Andrew; Hurricane, Omar; Callahan, Debbie; Hinkel, Denise; Edwards, John

    2015-11-01

    In laser driven hohlraum capsule implosions on the National Ignition Facility, supra-thermal hot electrons generated by laser plasma instabilities can preheat the capsule. Time resolved hot electron Bremsstrahlung spectra combined with 30 keV x-ray imaging uncover for the first time the directionality of hot electrons onto a high-Z surrogate capsule located at the hohlraum center. In the most extreme case, we observed a collimated beaming of hot electrons onto the capsule poles, reaching 50x higher localized energy deposition than for isotropic electrons. A collective SRS model where all laser beams in a cone drive a common plasma wave provides a physical interpretation for the observed beaming. Imaging data are used to distinguish between this mechanism and 2ωp instability. The amount of hot electrons generated can be controlled by the laser pulse shape and hohlraum plasma conditions. This work performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

  10. The analysis and calculation of H0 neutral beam attenuation due to penetration into tokamak plasma

    International Nuclear Information System (INIS)

    The physical processes of the neutral beam heated plasma is described. The penetration attenuation of the neutral beam in the plasma has been calculated, analysed and compared by means of two kinds of calculation methods based on different physics models. The dependence of neutral beam decay in the plasma on the beam energy, plasma parameters and impurity has been investigated. The calculation results of the beam attenuation for HL-1M typical plasma parameters also have been given. In numerical calculation taking multistep collision processes of the interaction between the beam and the plasma into account, its physics model includes excitation, collisional and radiative de-excitation, ionization, charge exchange and Lorentz field ionization of excited atoms. In the analytical calculation using the simple physics model, the ionization of the neutral beam and the charge exchange between the beam and the particles of the plasma and impurity are only taken into account. Both calculation results show that the penetration coefficient of the neutral beam entering the plasma increases with the neutral beam energy E0, and decreases with the plasma density ne, and show that comparing the analytical calculation using simple physics model with the numerical calculation taking multistep processes into account in the range of ne≤1014 cm-3 and 20≤E0 (keV/u)≤100, the effective stopping cross-section of the former is ≤20% less than that of the latter. (7 refs., 4 figs., 5 tabs.)

  11. Propagation model for vector beams generated by metasurfaces.

    Science.gov (United States)

    Shu, Weixing; Liu, Yachao; Ke, Yougang; Ling, Xiaohui; Liu, Zhenxing; Huang, Bin; Luo, Hailu; Yin, Xiaobo

    2016-09-01

    A propagation model of vector beams generated by metasurfaces based on vector diffraction theory is established theoretically and verified experimentally. Considering the Pancharatnam-Berry phase introduced by the metasurface, analytical forms of vector beams for arbitrary incident polarization and topological charge of metasurfaces are found in the Fresnel and Fraunhofer diffraction regions, respectively. The complex amplitude of the resultant vector beam can be described in terms of a confluent hypergeometric function, with an intensity profile that manifests concentric rings in the Fresnel region and a single ring in the Fraunhofer one. Fraunhofer diffraction provides a method to create vector beams with simultaneously high purity and modal power. Further experiments verify the theoretical results. PMID:27607720

  12. Development of compact quantum beam generation system and the application

    International Nuclear Information System (INIS)

    After the approval of the project as the 'High-Tech Research Center Project' conducted by MEXT at Waseda University, the laser driven photo-cathode RF-Gun (RF-Gun) has been developed very extensively. The system was developed to obtain the stable and high quality (i.e. very low emittance) electron beam in conjunction with the system stabilization such as RF power source and laser system for the electron emission. The high quality electron beams have been applied for the development of novel beam diagnostic system. At the same time, the beams (electron and laser) are applied for the inverse Compton scattering experiment for the generation of soft-X-ray with quasi-monochromatic energy and short time structure, and for the pump probe experiment (the pico-second pulse radiolysis) as the very compact system. (author)

  13. Effects of a low work function cathode on electron beam generation in a hollow cathode discharge

    International Nuclear Information System (INIS)

    Recent simulations reveal that a large contribution to the formation of the hollow cathode discharge comes from secondary electron emission due to ion bombardment of the hollow cathode surface. The simulations suggest that a decrease in work function of the hollow cathode surface will lead to enhanced plasma formation during the initial and latter phases of the discharge. The use of this enhanced plasma to more efficiently generate beams (both ion and electron) was studied. A pulsed hollow cathode discharge was constructed using low work function dispenser cathode material as the hollow cathode. The electron beam characteristics of the discharge were investigated. Other hollow cathodes constructed with various materials (molybdenum, copper) were constructed and the results will be compared. Applications of the new source are discussed

  14. Study of fast electron generation using multi beam of LFEX-class laser

    Science.gov (United States)

    Hata, M.; Sakagami, H.; Johzaki, T.; Sentoku, Y.; Nagatomo, H.

    2016-05-01

    Fast Ignition Realization Experiment project phase-I (FIREX-I) is being performed at Institute of Laser Engineering, Osaka University. In this project, the four-beam bundled high-energy Petawatt laser (LFEX) is being operated. LFEX laser provides great multi-beam irradiation flexibility, with the possibility of arrange the pulses in temporal sequence, spatially separate them in distinct spots of focus them in a single spot. In this paper, we study the two- beam interference effects on high-intensity picosecond laser-plasma interaction (LPI) by twodimensional relativistic Particle-In-Cell simulations. The interference causes surface perturbation, which enhances laser absorption and underdense plasma generation, increasing the accelerated electron number and their slope temperature. The laser-to-electron energy conversion efficiency for two-beam interference case is suitable for Fast Ignition (FI) compared to the single beam case, but the increment of fast electron divergence leads to lower energy coupling. To optimize the target design for FI, these interference effects should be taken into consideration.

  15. Upconversion of whistler waves by gyrating ion beams in a plasma

    Indian Academy of Sciences (India)

    Harsha Jalori; Sunil K Singh; A K Gwal

    2004-09-01

    A gyrating ion beam, with a ring-shaped distribution in velocity, supports negative energy beam modes near the harmonics of beam gyro-frequency. An investigation of the non-linear interaction of high-frequency whistler waves with the negative energy beam cyclotron mode is made. A non-linear dispersion relation is derived for the coupled modes. It is shown that a gyrating ion-beam frequency upconverts the whistler waves separated by harmonics of beam gyro-frequency. The expression for the growth rate of whistler mode waves has been derived. In Case 1, a high-amplitude whistler wave decays into two lower frequency waves, called a low-frequency mode and a side band of frequency lower than that of pump wave. In Case 2 a high-amplitude whistler wave decays into two lower frequency daughter waves, called the low-frequency mode and whistler waves. Generation mechanism of these waves has application in space and laboratory plasmas.

  16. Electron beam transport in weak plasma and plasma heating by electron beams

    International Nuclear Information System (INIS)

    Today, the earth's intrinsic magnetic field prevents the streaming solar wind plasma from directly interacting with the terrestrial atmosphere. Periodically the geomagnetic field reverses direction, and during the transition period, the earth's magnetic barrier is thought to disappear. In the past, studies about the atmospheric-solar wind interaction dynamics were hindered by a scarcity of observational data. However, since December 1978, the Pioneer-Venus Orbiter has been providing daily observations of the atmospheric dynamics produced by the direct solar wind interaction with the atmosphere of Venus (the only planet known to lack an intrinsic magnetic field). This thesis develops the first three dimensional magnetohydrodynamic (MHD) theory of this interaction. Within the ionosphere of Venus analytic solutions to the MHD equations are possible because of a favorable geometry between the induced ionospheric magnetic fields and the ionospheric plasma motions. It is shown that variations in the solar wind speed and interplanetary magnetic vector direction cause variations in the dayside ionospheric plasma flows and the induced magnetic field configuration, and that these changes can account for the variety of magnetic structures observed by Pioneer-Venus. Portions of the Venus ionosphere are shown to be susceptible to the Kelvin-Helmholtz shear instability. The unusual shape of the computed region of stability is shown to be an important key to understanding the highly variable Pioneer-Venus observations

  17. Operational characteristics of the high flux plasma generator Magnum-PSI

    International Nuclear Information System (INIS)

    Highlights: •We have described the design and capabilities of the plasma experiment Magnum-PSI. •The plasma conditions are well suited for PSI studies in support of ITER. •Quasi steady state heat fluxes over 10 MW m−2 have been achieved. •Transient heat and particle loads can be generated to simulate ELM instabilities. •Lithium coating can be applied to the surfaces of samples under vacuum. -- Abstract: In Magnum-PSI (MAgnetized plasma Generator and NUMerical modeling for Plasma Surface Interactions), the high density, low temperature plasma of a wall stabilized dc cascaded arc is confined to a magnetized plasma beam by a quasi-steady state axial magnetic field up to 1.3 T. It aims at conditions that enable fundamental studies of plasma–surface interactions in the regime relevant for fusion reactors such as ITER: 1023–1025 m−2 s−1 hydrogen plasma flux densities at 1–5 eV. To study the effects of transient heat loads on a plasma-facing surface, a high power pulsed magnetized arc discharge has been developed. Additionally, the target surface can be transiently heated with a pulsed laser system during plasma exposure. In this contribution, the current status, capabilities and performance of Magnum-PSI are presented

  18. Laser-driven electron beamlines generated by coupling laser-plasma sources with conventional transport systems

    Energy Technology Data Exchange (ETDEWEB)

    Antici, P. [Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Frascati, Via E. Fermi, 40, 00044 Frascati (Italy); SAPIENZA, University of Rome, Dip. SBAI, Via A. Scarpa 14, 00161 Rome (Italy); INFN - Sezione di Roma, c/o Dipartimento di Fisica - SAPIENZA, University of Rome, P.le Aldo Moro, 2 - 00185 Rome (Italy); Bacci, A.; Chiadroni, E.; Ferrario, M.; Rossi, A. R. [Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Frascati, Via E. Fermi, 40, 00044 Frascati (Italy); Benedetti, C. [University of Bologna and INFN - Bologna (Italy); Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L. [SAPIENZA, University of Rome, Dip. SBAI, Via A. Scarpa 14, 00161 Rome (Italy); INFN - Sezione di Roma, c/o Dipartimento di Fisica - SAPIENZA, University of Rome, P.le Aldo Moro, 2 - 00185 Rome (Italy); Serafini, L. [INFN-Milan and Department of Physics, University of Milan, Via Celoria 16, 20133 Milan (Italy)

    2012-08-15

    Laser-driven electron beamlines are receiving increasing interest from the particle accelerator community. In particular, the high initial energy, low emittance, and high beam current of the plasma based electron source potentially allow generating much more compact and bright particle accelerators than what conventional accelerator technology can achieve. Using laser-generated particles as injectors for generating beamlines could significantly reduce the size and cost of accelerator facilities. Unfortunately, several features of laser-based particle beams need still to be improved before considering them for particle beamlines and thus enable the use of plasma-driven accelerators for the multiple applications of traditional accelerators. Besides working on the plasma source itself, a promising approach to shape the laser-generated beams is coupling them with conventional accelerator elements in order to benefit from both a versatile electron source and a controllable beam. In this paper, we perform start-to-end simulations to generate laser-driven beamlines using conventional accelerator codes and methodologies. Starting with laser-generated electrons that can be obtained with established multi-hundred TW laser systems, we compare different options to capture and transport the beams. This is performed with the aim of providing beamlines suitable for potential applications, such as free electron lasers. In our approach, we have analyzed which parameters are critical at the source and from there evaluated different ways to overcome these issues using conventional accelerator elements and methods. We show that electron driven beamlines are potentially feasible, but exploiting their full potential requires extensive improvement of the source parameters or innovative technological devices for their transport and capture.

  19. Self-modulated dynamics of a relativistic charged particle beam in plasma wake field excitation

    Science.gov (United States)

    Akhter, T.; Fedele, R.; Nicola, S. De; Tanjia, F.; Jovanović, D.; Mannan, A.

    2016-09-01

    The self-modulated dynamics of a relativistic charged particle beam is provided within the context of the theory of plasma wake field excitation. The self-consistent description of the beam dynamics is provided by coupling the Vlasov equation with a Poisson-type equation relating the plasma wake potential to the beam density. An analysis of the beam envelope self-modulation is then carried out and the criteria for the occurrence of the instability are discussed thereby.

  20. Self-Focusing of Hermite-Cosh-Gaussian Laser Beams in Plasma under Density Transition

    OpenAIRE

    Manzoor Ahmad Wani; Niti Kant

    2014-01-01

    Self-focusing of Hermite-Cosh-Gaussian (HChG) laser beam in plasma under density transition has been discussed here. The field distribution in the medium is expressed in terms of beam-width parameters and decentered parameter. The differential equations for the beam-width parameters are established by a parabolic wave equation approach under paraxial approximation. To overcome the defocusing, localized upward plasma density ramp is considered, so that the laser beam is focused on a small spot...

  1. Self modulated dynamics of a relativistic charged particle beam in plasma wake field excitation

    CERN Document Server

    Akhter, T; De Nicola, S; Tanjia, F; Jovanovic, D; Mannan, A

    2015-01-01

    Self modulated dynamics of a relativistic charged particle beam is reviewed within the context of the theory of plasma wake field excitation. The self-consistent description of the beam dynamics is provided by coupling the Vlasov equation with a Poisson-type equation relating the plasma wake potential to the beam density. An analysis of the beam envelope self-modulation is then carried out and the criteria for the occurrence of the instability are discussed thereby.

  2. Generation of intense ion beams and their application to controlled fusion research

    International Nuclear Information System (INIS)

    Successful generation of pulsed multi-kA proton beams in the energy range 0.2 to 1.7 MeV using existing pulsed power technology has been achieved by three different techniques: reflex triodes, pinched electron-beam diodes and magnetically insulated diodes. Peak current densities in excess of 10 kAcm-2 have been observed on the NRL Gamble II machine and over 1.0 kAcm-2 on the Cornell Neptune machine. Peak total ion currents above 200 kA are produced by Gamble II. The potential applications of intense ion beams to magnetic confinement include (i) plasma heating and (ii) ion rings. A summary of continuous theoretical and experimental investigations on these applications is presented. (author)

  3. The linear plasma generator Magnum-PSI

    OpenAIRE

    Eck, van, M.

    2013-01-01

    Numerical simulations form an indispensable tool to understand the behavior of a hot plasma that is created inside a tokamak for providing nuclear fusion energy. Various aspects of tokamak plasmas have been successfully studied through the reduced magnetohydrodynamic (MHD) model. The need for more complete modeling through the full MHD equations is addressed here. Our computational method is presented along with measures against possible problems regarding pollution, stability, and regularity...

  4. Design Considerations for Plasma Accelerators Driven by Lasers or Particle Beams

    OpenAIRE

    Schroeder, C. B.

    2011-01-01

    Plasma accelerators may be driven by the ponderomotive force of an intense laser or the space-charge force of a charged particle beam. The implications for accelerator design and the different physical mechanisms of laser-driven and beam-driven plasma acceleration are discussed. Driver propagation is examined, as well as the effects of the excited plasma wave phase velocity. The driver coupling to subsequent plasma accelerator stages for high-energy physics applications is addressed.

  5. 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.

  6. Plasma-Based Studies on 4th Generation Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Lee, R W; Baldis, H A; Cauble, R C; Landen, O L; Wark, J S; Ng, A; Rose, S J; Lewis, C; Riley, D; Gauthier, J-C; Audebert, P

    2000-11-28

    The construction of a short pulse tunable x-ray laser source will be a watershed for plasma-based and warm dense matter research. The areas we will discuss below can be separated broadly into warn dense matter (WDM) research, laser probing of near solid density plasmas, and laser-plasma spectroscopy of ions in plasmas. The area of WDM refers to that part of the density-temperature phase space where the standard theories of condensed matter physics and/or plasma statistical physics are invalid. Warm dense matter, therefore, defines a region between solids and plasmas, a regime that is found in planetary interiors, cool dense stars, and in every plasma device where one starts from a solid, e.g., laser-solid matter produced plasma as well as all inertial fusion schemes. The study of dense plasmas has been severely hampered by the fact that laser-based methods have been unavailable. The single most useful diagnostic of local plasma conditions, e.g., the temperature (T{sub e}), the density (n{sub e}), and the ionization (Z), has been Thomson scattering. However, due to the fact that visible light will not propagate at electron densities, n{sub e}, {ge} 10{sup 22} cm{sup -3} implies dense plasmas can not be probed. The 4th generation sources, LCLS and Tesla will remove these restrictions. Laser-based plasma spectroscopic techniques have been used with great success to determine the line shapes of atomic transitions in plasmas, study the population kinetics of atomic systems embedded in plasmas, and look at redistribution of radiation. However. the possibilities end for plasmas with n{sub e} {ge} 10{sup 22} since light propagation through the medium is severely altered by the plasma. The entire field of high Z plasma kinetics from laser produced plasma will then be available to study with the tunable source.

  7. Transverse Dynamics and Energy Tuning of Fast Electrons Generated in Sub-Relativistic Intensity Laser Pulse Interaction with Plasmas

    CERN Document Server

    Mori, M; Daito, I; Kotaki, H; Hayashi, Y; Yamazaki, A; Ogura, K; Sagisaka, A; Koga, J; Nakajima, K; Daido, H; Bulanov, S V; Kimura, T

    2006-01-01

    The regimes of quasi-mono-energetic electron beam generation were experimentally studied in the sub-relativistic intensity laser plasma interaction. The observed electron acceleration regime is unfolded with two-dimensional-particle-in-cell simulations of laser-wakefield generation in the self-modulation regime.

  8. Angular momentum transfer of Laguerre - Gaussian laser pulses and quasi-static magnetic field generation in plasma channels

    International Nuclear Information System (INIS)

    To generate a strong axial and azimuthal quasi-static magnetic field, we propose to study the interaction of Laguerre-Gaussian laser beams in a parabolic plasma channel. Our study shows that the higher-order modes with orbital angular momentum generate a stronger magnetic field in comparison to the lower-order modes of the laser beam. The contribution of the effective mass of photon on the orbital angular momentum and the polarization state of the beam are analyzed analytically and with 2D Particle in Cell (PIC) simulation. These effects have been put forwarded in analyzing the magnetic field generation. (author)

  9. Controlled self-modulation of high energy beams in a plasma

    International Nuclear Information System (INIS)

    A high energy particle beam propagating in a uniform plasma is subject to the transverse two-stream instability that first transforms the beam into the train of microbunches and then quickly destroys that train by transverse wakefields. By the proper longitudinal inhomogeneity of the plasma density, it is possible to stop the instability action at the stage of microbunches and form the bunch train that can resonantly excite plasma wakefields over a long distance. The latter feature is vital for proton beam driven plasma wakefield acceleration that was recently proposed as a way to bring electrons to TeV energy range in a single plasma section.

  10. 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.

  11. Generation of high brightness ion beam from insulated anode PED

    International Nuclear Information System (INIS)

    Generation and focusing of a high density ion beam with high brightness from a organic center part of anode of a PED was reported previously. Mass, charge and energy distribution of this beam were analyzed. Three kind of anode were tried. Many highly ionized medium mass ions (up to C4+, O6+) accelarated to several times of voltage difference between anode and cathode were observed. In the case of all insulator anode the current carried by the medium mass ions is about half of that carried by protons. (author)

  12. QED effects and radiation generation in relativistic laser plasma

    Science.gov (United States)

    Kostyukov, I. Yu.; Nerush, E. N.; Bashmakov, V. F.

    2011-06-01

    The radiative and quantum effects in laser plasmas are discussed. The self-consistent numerical model based on particle-in-cell and Monte-Carlo methods are developed. First we analyze the spectra of Compton backscattered photons and betatron radiation in the classical and quantum regimes. Then we address an interaction between intense laser pulse and relativistic electron beam. Finally we discuss the electron-positron pair plasma production in extremely-intense laser field. It is shown that such plasma can be an efficient source of energetic gammaquanta.

  13. Numerical Approach of Interactions of Proton Beams and Dense Plasmas with Quantum-Hydrodynamic/Particle-in-Cell Model

    Science.gov (United States)

    Zhang, Ya; Li, Lian; Jiang, Wei; Yi, Lin

    2016-07-01

    A one dimensional quantum-hydrodynamic/particle-in-cell (QHD/PIC) model is used to study the interaction process of an intense proton beam (injection density of 1017 cm‑3) with a dense plasma (initial density of ~ 1021 cm‑3), with the PIC method for simulating the beam particle dynamics and the QHD model for considering the quantum effects including the quantum statistical and quantum diffraction effects. By means of the QHD theory, the wake electron density and wakefields are calculated, while the proton beam density is calculated by the PIC method and compared to hydrodynamic results to justify that the PIC method is a more suitable way to simulate the beam particle dynamics. The calculation results show that the incident continuous proton beam when propagating in the plasma generates electron perturbations as well as wakefields oscillations with negative valleys and positive peaks where the proton beams are repelled by the positive wakefields and accelerated by the negative wakefields. Moreover, the quantum correction obviously hinders the electron perturbations as well as the wakefields. Therefore, it is necessary to consider the quantum effects in the interaction of a proton beam with cold dense plasmas, such as in the metal films. supported by National Natural Science Foundation of China (Nos. 11405067, 11105057, 11275007)

  14. Energy spread of ion beams generated in multicusp ion sources

    International Nuclear Information System (INIS)

    For the production of future microelectronics devices, various alternate methods are currently being considered to replace the presently used method of lithography with ion beam lithography. One of these methods is the Ion Projection Lithography (IPL), which aims at the possibility of projecting sub-0.25 μm patterns of a stencil mask onto a wafer substrate. In order to keep the chromatic aberrations below 25 nm, an ion source which delivers a beam with energy spread of less than 3 eV is desired. For this application, multicusp ion sources are being considered. We measure the longitudinal energy spread of the plasma ions by using a two-grid electrostatic energy analyzer. The energy spread of the extracted beam is measured by a high-voltage retarding-field energy analyzer. In order to obtain the transverse ion temperature, a parallel-plate scanner is being set up to study the beam emittance. In this paper, comparisons are made for different ion source configurations

  15. RF generation in the DARHT Axis-II beam dump

    International Nuclear Information System (INIS)

    We have occasionally observed radio-frequency (RF) electromagnetic signals in the downstream transport (DST) of the second axis linear induction accelerator (LIA) at the dual-axis radiographic hydrodynamic testing (DARHT) facility. We have identified and eliminated some of the sources by eliminating the offending cavities. However, we still observe strong RF in the range 1 GHz t0 2 GHz occurring late in the ∼2-(micro)s pulse that can be excited or prevented by varying the downstream tune. The narrow frequency width (<0.5%) and near exponential growth at the dominant frequency is indicative of a beam-cavity interaction, and electro-magnetic simulations of cavity structure show a spectrum rich in resonances in the observed frequency range. However, the source of beam produced RF in the cavity resonance frequency range has not been identified, and it has been the subject of much speculation, ranging from beam-plasma or beam-ion instabilities to unstable cavity coupling.

  16. Propagation of Gaussian laser beam in cold plasma of Drude model

    International Nuclear Information System (INIS)

    The propagation characters of Gaussian laser beam in plasmas of Drude model have been investigated by complex eikonal function assumption. The dielectric constant of Drude model is representative and applicable in describing the cold unmagnetized plasmas. The dynamics of ponderomotive nonlinearity, spatial diffraction, and collision attenuation is considered. The derived coupling equations determine the variations of laser beam and irradiation attenuation. The modified laser beam-width parameter F, the dimensionless axis irradiation intensity I, and the spatial electron density distribution n/n0 have been studied in connection with collision frequency, initial laser intensity and beam-width, and electron temperature of plasma. The variations of laser beam and plasma density due to different selections of parameters are reasonably explained, and results indicate the feasible modification of the propagating characters of laser beam in plasmas, which possesses significance to fast ignition, extended propagation, and other applications.

  17. MeV Argon ion beam generation with narrow energy spread

    CERN Document Server

    Xu, Jiancai; Shen, Baifei; Zhang, Hui; Li, Shun; Yu, Yong; Li, Jinfeng; Lu, Xiaoming; Wang, Cheng; Wang, Xinliang; Liang, Xiaoyan; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2016-01-01

    Laser driven particle acceleration has shown remarkable progresses in generating multi-GeV electron bunches and 10s of MeV ion beams based on high-power laser facilities. Intense laser pulse offers the acceleration field of 1012 Volt per meter, several orders of magnitude larger than that in conventional accelerators, enabling compact devices. Here we report that a highly-collimated argon ion beam with narrow energy spread is produced by irradiating a 45-fs fully-relativistic laser pulse onto an argon cluster target. The highly-charged (Argon ion with charge state of 16+) heavy ion beam has a minimum absolute energy spread of 0.19 MeV per nucleon at the energy peak of 0.39 MeV per nucleon. we identify a novel scheme from particle-in-cell simulations that greatly reduces the beam energy spread. The laser-driven intense plasma wakefield has a strong modulation on the ion beam in a way that the low energy part is cut off. The pre-accelerated argon ion beam from Coulomb explosion thus becomes more mono-energetic ...

  18. An exact solution to paraxial propagation of laser beams in longitudinal inhomogeneous plasmas

    Institute of Scientific and Technical Information of China (English)

    Zhou Bing-Ju; Huang Zheng; Liu Ming-Wei; Liu Xiao-Juan

    2007-01-01

    An exact, general solution for laser beams propagating in longitudinally inhomogeneous plasmas is obtained in the form of the diffraction integral. The Gaussian beam and the Hermite-Gaussian beam are taken for example. In the case of an increasing plasma density along the propagation distance, natural diffraction of the Gaussian beam is retarded. This retardance has a less effect on the central part of the Hermite-Gaussian beam while a considerable rise of the power in bucket (PIB) occurs in the surrounding part of the beam.

  19. Modeling nitrogen plasmas produced by intense electron beams

    Science.gov (United States)

    Angus, J. R.; Mosher, D.; Swanekamp, S. B.; Ottinger, P. F.; Schumer, J. W.; Hinshelwood, D. D.

    2016-05-01

    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/cm2 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.

  20. Investigations of Interaction of Laser Radiation and Plasma Beams with Materials of Reactor Chamber for Inertial Confinement Fusion

    International Nuclear Information System (INIS)

    The main purpose of the project was to experimentally analyze some the processes which take place during the interaction of laser radiation and plasma beams with the materials of reactor chamber for the Inertial Confinement Fusion. First, we studied the effect of target nature on the laser ablation process and on the properties of laser-generated plasma ions. As an example we considered porous targets having different densities and showed how the charge state, the energy and the intensity of the plasma ions depend on the target density. We also studied the effect of laser frequency on the properties of plasma ions generated at the surface of such porous targets. We considered possibilities of controlling the intensity and the energy of the ions by changing the frequency of the laser and the density of the target because of the change in laser ablation process. Then we investigated the changes in the properties of laser-produced plasma ions after the ablation process, during the plasma expansion, due to the mutual interaction between the ions of different mass. For this purpose we studied two- element plasma ions generated from (Sc2O3, Ce2O3, Lu2O3) targets. Experiments have shown that structural defects caused by the neutron irradiation, influence not only on the efficiency of the process of material evaporation and emission of plasma, but also on the ionization and recombination processes taking place at the initial stage of the plasma formation and expansion. (author)