Science.gov

Sample records for accelerating plasma wave

  1. Plasma Beat-Wave Acceleration

    NASA Astrophysics Data System (ADS)

    Clayton, Christopher E.

    2002-04-01

    Among all the advanced accelerator concepts that use lasers as the power source, most of the effort to date has been with the idea of using a laser pulse to excite a accelerating mode in a plasma. Within this area, there are a variety of approaches for creating the accelerating mode, as indicated by the other talks in this session. What is common to these approaches is the physics of how a laser pulse pushes on plasma electrons to organize electron-density perturbations, the sources of the ultra-high (> GeV/M) accelerating gradients. It is the "ponderomotive force", proportional to the local gradient of the of the laser intensity, that pushes plasma electrons forward (on the leading edge of the pulse) and backwards (on the trailing edge) which leads to harmonic motion of the electrons. As the laser pulse moves through the plasma at group velocity Vg c, the oscillating electrons show up macroscopically as a plasma mode or wave with frequency w equal to the plasma frequency and k = w/Vg. For short laser pulses, this is the Laser Wakefield Accelerator (LWFA) concept. Closely related is the Plasma Beat-Wave Acceleration (PBWA) concept. Here, the laser pulse that perturbs the plasma is composed of two closely-spaced frequencies that "beat", i.e., periodically constructively and destructively interfere, forming an electromagnetic beat wave. One can visualize this as a train of short pulses. If this beating frequency is set to the plasma frequency, then each pulse in the train will reinforce the density perturbation caused by the previous pulse. The principal advantage of multiple pulses driving up the plasma wave as opposed to a single pulse is in efficiency, allowing for the production of relatively large diameter (more 1-D like) accelerating modes. In this talk I will discuss past, current and planned PBWA experiments which are taking place at UCLA, RAL in England, and LULI in France.

  2. Photon acceleration in plasma wake wave

    SciTech Connect

    Bu, Zhigang; Shen, Baifei Yi, Longqing; Zhang, Hao; Huang, Shan; Li, Shun

    2015-04-15

    The photon acceleration effect in a laser wake field is investigated based on photon Hamiltonian dynamics. A test laser pulse is injected into a plasma wave at an incident angle θ{sub i}, which could slow down the photon velocity along the propagating direction of the wake wave so as to increase the acceleration distance for the photons. The photon trapping condition is analyzed in detail, and the maximum frequency shift of the trapped photon is obtained. The acceleration gradient and dephasing length are emphatically studied. The compression of the test laser pulse is examined and used to interpret the acceleration process. The limit of finite transverse width of the wake wave on photon acceleration is also discussed.

  3. Channeled particle acceleration by plasma waves in metals

    SciTech Connect

    Chen, P.; Noble, R.J.

    1987-01-01

    A solid state accelerator concept utilizing particle acceleration along crystal channels by longitudinal electron plasma waves in a metal is presented. Acceleration gradients of order 100 GV/cm are theoretically possible. Particle dechanneling due to electron multiple scattering can be eliminated with a sufficiently high acceleration gradient. Plasma wave dissipation and generation in metals are also discussed.

  4. Plasma production for electron acceleration by resonant plasma wave

    NASA Astrophysics Data System (ADS)

    Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Croia, M.; Curcio, A.; Di Giovenale, D.; Di Pirro, G. P.; Filippi, F.; Ghigo, A.; Lollo, V.; Pella, S.; Pompili, R.; Romeo, S.; Ferrario, M.

    2016-09-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV/m), enabling acceleration of electrons to GeV energy in few centimeter. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators (large energy spread, low repetition rate, and large emittance); radiofrequency-based accelerators, in fact, are limited in accelerating field (10-100 MV/m) requiring therefore hundred of meters of distances to reach the GeV energies, but can provide very bright electron bunches. To combine high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC_LAB (Ferrario et al., 2013 [1]). In particular here we focus on hydrogen plasma discharge, and in particular on the theoretical and numerical estimates of the ionization process which are very useful to design the discharge circuit and to evaluate the current needed to be supplied to the gas in order to have full ionization. Eventually, the current supplied to the gas simulated will be compared to that measured experimentally.

  5. Method of accelerating photons by a relativistic plasma wave

    DOEpatents

    Dawson, John M.; Wilks, Scott C.

    1990-01-01

    Photons of a laser pulse have their group velocity accelerated in a plasma as they are placed on a downward density gradient of a plasma wave of which the phase velocity nearly matches the group velocity of the photons. This acceleration results in a frequency upshift. If the unperturbed plasma has a slight density gradient in the direction of propagation, the photon frequencies can be continuously upshifted to significantly greater values.

  6. Electron Beam Transport in Advanced Plasma Wave Accelerators

    SciTech Connect

    Williams, Ronald L

    2013-01-31

    The primary goal of this grant was to develop a diagnostic for relativistic plasma wave accelerators based on injecting a low energy electron beam (5-50keV) perpendicular to the plasma wave and observing the distortion of the electron beam's cross section due to the plasma wave's electrostatic fields. The amount of distortion would be proportional to the plasma wave amplitude, and is the basis for the diagnostic. The beat-wave scheme for producing plasma waves, using two CO2 laser beam, was modeled using a leap-frog integration scheme to solve the equations of motion. Single electron trajectories and corresponding phase space diagrams were generated in order to study and understand the details of the interaction dynamics. The electron beam was simulated by combining thousands of single electrons, whose initial positions and momenta were selected by random number generators. The model was extended by including the interactions of the electrons with the CO2 laser fields of the beat wave, superimposed with the plasma wave fields. The results of the model were used to guide the design and construction of a small laboratory experiment that may be used to test the diagnostic idea.

  7. Plasma accelerators

    SciTech Connect

    Ruth, R.D.; Chen, P.

    1986-03-01

    In this paper we discuss plasma accelerators which might provide high gradient accelerating fields suitable for TeV linear colliders. In particular we discuss two types of plasma accelerators which have been proposed, the Plasma Beat Wave Accelerator and the Plasma Wake Field Accelerator. We show that the electric fields in the plasma for both schemes are very similar, and thus the dynamics of the driven beams are very similar. The differences appear in the parameters associated with the driving beams. In particular to obtain a given accelerating gradient, the Plasma Wake Field Accelerator has a higher efficiency and a lower total energy for the driving beam. Finally, we show for the Plasma Wake Field Accelerator that one can accelerate high quality low emittance beams and, in principle, obtain efficiencies and energy spreads comparable to those obtained with conventional techniques.

  8. Method for generating a plasma wave to accelerate electrons

    DOEpatents

    Umstadter, D.; Esarey, E.; Kim, J.K.

    1997-06-10

    The invention provides a method and apparatus for generating large amplitude nonlinear plasma waves, driven by an optimized train of independently adjustable, intense laser pulses. In the method, optimal pulse widths, interpulse spacing, and intensity profiles of each pulse are determined for each pulse in a series of pulses. A resonant region of the plasma wave phase space is found where the plasma wave is driven most efficiently by the laser pulses. The accelerator system of the invention comprises several parts: the laser system, with its pulse-shaping subsystem; the electron gun system, also called beam source, which preferably comprises photo cathode electron source and RF-LINAC accelerator; electron photo-cathode triggering system; the electron diagnostics; and the feedback system between the electron diagnostics and the laser system. The system also includes plasma source including vacuum chamber, magnetic lens, and magnetic field means. The laser system produces a train of pulses that has been optimized to maximize the axial electric field amplitude of the plasma wave, and thus the electron acceleration, using the method of the invention. 21 figs.

  9. Method for generating a plasma wave to accelerate electrons

    DOEpatents

    Umstadter, Donald; Esarey, Eric; Kim, Joon K.

    1997-01-01

    The invention provides a method and apparatus for generating large amplitude nonlinear plasma waves, driven by an optimized train of independently adjustable, intense laser pulses. In the method, optimal pulse widths, interpulse spacing, and intensity profiles of each pulse are determined for each pulse in a series of pulses. A resonant region of the plasma wave phase space is found where the plasma wave is driven most efficiently by the laser pulses. The accelerator system of the invention comprises several parts: the laser system, with its pulse-shaping subsystem; the electron gun system, also called beam source, which preferably comprises photo cathode electron source and RF-LINAC accelerator; electron photo-cathode triggering system; the electron diagnostics; and the feedback system between the electron diagnostics and the laser system. The system also includes plasma source including vacuum chamber, magnetic lens, and magnetic field means. The laser system produces a train of pulses that has been optimized to maximize the axial electric field amplitude of the plasma wave, and thus the electron acceleration, using the method of the invention.

  10. Measurements of beat wave accelerated electrons in a toroidal plasma

    SciTech Connect

    Rogers, J.H.; Hwang, D.W. |

    1992-06-01

    Electrons are accelerated by large amplitude electron plasma waves driven by counter-propagating microwaves with a difference frequency approximately equal to the electron plasma frequency. Energetic electrons are observed only when the phase velocity of the wave is in the range 3v{sub e} < v{sub ph} < 7v{sub e} (v{sub ph} was varied 2v{sub e} < v{sub ph} < 10v{sub e}), where v{sub e} is the electron thermal velocity, (kT{sub e}/m{sub e}){sup {1/2}}. As the phase velocity increases, fewer electrons are accelerated to higher velocities. The measured current contained in these accelerated electrons has the power dependence predicted by theory, but the magnitude is lower than predicted.

  11. Improved ion acceleration via laser surface plasma waves excitation

    SciTech Connect

    Bigongiari, A.

    2013-05-15

    The possibility of enhancing the emission of the ions accelerated in the interaction of a high intensity ultra-short (<100 fs) laser pulse with a thin target (<10λ{sub 0}), via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed for laser intensities ranging from 10{sup 19} to 10{sup 20} Wcm{sup −2}μm{sup 2}. The surface wave is resonantly excited by the laser via the coupling with a modulation at the target surface. In the cases where the surface wave is excited, we find an enhancement of the maximum ion energy of a factor ∼2 compared to the cases where the target surface is flat.

  12. Progress on plasma accelerators

    SciTech Connect

    Chen, P.

    1986-05-01

    Several plasma accelerator concepts are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA) and the Plasma Wake Field Accelerator (PWFA). Various accelerator physics issues regarding these schemes are discussed, and numerical examples on laboratory scale experiments are given. The efficiency of plasma accelerators is then revealed with suggestions on improvements. Sources that cause emittance growth are discussed briefly.

  13. Excitation of Accelerating Plasma Waves by Counter-propagating Laser Beams

    SciTech Connect

    Gennady Shvets; Nathaniel J. Fisch; and Alexander Pukhov

    2001-08-30

    Generation of accelerating plasma waves using two counter-propagating laser beams is considered. Colliding-beam accelerator requires two laser pulses: the long pump and the short timing beam. We emphasize the similarities and differences between the conventional laser wakefield accelerator and the colliding-beam accelerator (CBA). The highly nonlinear nature of the wake excitation is explained using both nonlinear optics and plasma physics concepts. Two regimes of CBA are considered: (i) the short-pulse regime, where the timing beam is shorter than the plasma period, and (ii) the parametric excitation regime, where the timing beam is longer than the plasma period. Possible future experiments are also outlined.

  14. Simple scalings for various regimes of electron acceleration in surface plasma waves

    SciTech Connect

    Riconda, C.; Vialis, T.; Raynaud, M.; Grech, M.

    2015-07-15

    Different electron acceleration regimes in the evanescent field of a surface plasma wave are studied by considering the interaction of a test electron with the high-frequency electromagnetic field of a surface wave. The non-relativistic and relativistic limits are investigated. Simple scalings are found demonstrating the possibility to achieve an efficient conversion of the surface wave field energy into electron kinetic energy. This mechanism of electron acceleration can provide a high-frequency pulsed source of relativistic electrons with a well defined energy. In the relativistic limit, the most energetic electrons are obtained in the so-called electromagnetic regime for surface waves. In this regime, the particles are accelerated to velocities larger than the wave phase velocity, mainly in the direction parallel to the plasma-vacuum interface.

  15. Laser-wakefield acceleration of monoenergetic electron beams in the first plasma-wave period.

    PubMed

    Mangles, S P D; Thomas, A G R; Kaluza, M C; Lundh, O; Lindau, F; Persson, A; Tsung, F S; Najmudin, Z; Mori, W B; Wahlström, C-G; Krushelnick, K

    2006-06-01

    Beam profile measurements of laser-wakefield accelerated electron bunches reveal that in the monoenergetic regime the electrons are injected and accelerated at the back of the first period of the plasma wave. With pulse durations ctau >or= lambda(p), we observe an elliptical beam profile with the axis of the ellipse parallel to the axis of the laser polarization. This increase in divergence in the laser polarization direction indicates that the electrons are accelerated within the laser pulse. Reducing the plasma density (decreasing ctau/lambda(p)) leads to a beam profile with less ellipticity, implying that the self-injection occurs at the rear of the first period of the plasma wave. This also demonstrates that the electron bunches are less than a plasma wavelength long, i.e., have a duration <25 fs. This interpretation is supported by 3D particle-in-cell simulations. PMID:16803242

  16. Non-linear interactions of plasma waves in the context of solar particle acceleration

    NASA Astrophysics Data System (ADS)

    Gallegos-Cruz, A.; Perez-Peraza, J.

    2001-08-01

    Stochastic particle acceleration in plasmas by means of MHD turbulence in-volves a wide range of alternatives according to, the specific wave mode, the frequency regime of the turbulence, the kind of particles to be accelerated, the assumed plasma model and so on. At present most of the alternatives have been studied with relatively deepness, though some features are not yet com-pletely understood. One of them is the delimitation of the real importance of non-lineal effects of turbulence waves in the process of particle acceleration. In this work we analyse such effects taking into account the temporal evolution of the turbulence. For illustration we exemplify our analysis with the fast MHD mode. Our results show that in some specific stages of the turbulence evolu-tion, non-linear interactions have important effects in the process of particle acceleration.

  17. Pulse evolution and plasma-wave phase velocity in channel-guided laser-plasma accelerators.

    PubMed

    Benedetti, C; Rossi, F; Schroeder, C B; Esarey, E; Leemans, W P

    2015-08-01

    The self-consistent laser evolution of an intense, short-pulse laser exciting a plasma wave and propagating in a preformed plasma channel is investigated, including the effects of pulse steepening and energy depletion. In the weakly relativistic laser intensity regime, analytical expressions for the laser energy depletion, pulse self-steepening rate, laser intensity centroid velocity, and phase velocity of the plasma wave are derived and validated numerically. PMID:26382537

  18. Plasma accelerator

    DOEpatents

    Wang, Zhehui; Barnes, Cris W.

    2002-01-01

    There has been invented an apparatus for acceleration of a plasma having coaxially positioned, constant diameter, cylindrical electrodes which are modified to converge (for a positive polarity inner electrode and a negatively charged outer electrode) at the plasma output end of the annulus between the electrodes to achieve improved particle flux per unit of power.

  19. Heating and acceleration of solar wind ions by turbulent wave spectrum in inhomogeneous expanding plasma

    NASA Astrophysics Data System (ADS)

    Ofman, Leon; Ozak, Nataly; Viñas, Adolfo F.

    2016-03-01

    Near the Sun (< 10Rs) the acceleration, heating, and propagation of the solar wind are likely affected by the background inhomogeneities of the magnetized plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super-Alfvénic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.

  20. Excitation of Accelerating Plasma Waves by Counter-Propagating Laser Beams

    SciTech Connect

    Shvets, Gennady; Fisch, Nathaniel J; Pukhov, Alexander

    2002-04-05

    The conventional approach to exciting high phase velocity waves in plasmas is to employ a laser pulse moving in the direction of the desired particle acceleration. Photon downshifting then causes momentum transfer to the plasma and wave excitation. Novel approaches to plasma wake excitation, colliding-beam accelerator (CBA), which involve photon exchange between the long and short counter-propagating laser beams, are described. Depending on the frequency detuning Dw between beams and duration tL of the short pulse, there are two approaches to CBA. The first approach assumes tL ª 2/wp. Photons exchanged between the beams deposit their recoil momentum in the plasma driving the plasma wake. Frequency detuning between the beams determines the direction of the photon exchange, thereby controlling the phase of the plasma wake. This phase control can be used for reversing the slippage of the accelerated particles with respect to the wake. A variation on the same theme, super-beatwave accelerator, is also described. In the second approach, a short pulse with tL >> 2/wp1 detuned by Dw ~ 2wp from the counter-propagating beam is employed. While parametric excitation of plasma waves by the electromagnetic beatwave at 2wp of two co-propagating lasers was first predicted by Rosenbluth and Liu [M.N. Rosenbluth, C.S. Liu, Phys. Rev. Lett. 29 (1972) 701], it is demonstrated that the two excitation beams can be counter-propagating. The advantages of using this geometry (higher instability growth rate, insensitivity to plasma inhomogeneity) are explained, and supporting numerical simulations presented.

  1. Current-driven plasma acceleration versus current-driven energy dissipation. I - Wave stability theory

    NASA Technical Reports Server (NTRS)

    Kelly, A. J.; Jahn, R. G.; Choueiri, E. Y.

    1990-01-01

    The dominant unstable electrostatic wave modes of an electromagnetically accelerated plasma are investigated. The study is the first part of a three-phase program aimed at characterizing the current-driven turbulent dissipation degrading the efficiency of Lorentz force plasma accelerators such as the MPD thruster. The analysis uses a kinetic theory that includes magnetic and thermal effects as well as those of an electron current transverse to the magnetic field and collisions, thus combining all the features of previous models. Analytical and numerical solutions allow a detailed description of threshold criteria, finite growth behavior, destabilization mechanisms and maximized-growth characteristics of the dominant unstable modes. The lower hybrid current-driven instability is implicated as dominant and was found to preserve its character in the collisional plasma regime.

  2. Experimental Validation of a Branched Solution Model for Magnetosonic Ionization Waves in Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Underwood, Thomas; Loebner, Keith; Cappelli, Mark

    2015-11-01

    Detailed measurements of the thermodynamic and electrodynamic plasma state variables within the plume of a pulsed plasma accelerator are presented. A quadruple Langmuir probe operating in current-saturation mode is used to obtain time resolved measurements of the plasma density, temperature, potential, and velocity along the central axis of the accelerator. This data is used in conjunction with a fast-framing, intensified CCD camera to develop and validate a model predicting the existence of two distinct types of ionization waves corresponding to the upper and lower solution branches of the Hugoniot curve. A deviation of less than 8% is observed between the quasi-steady, one-dimensional theoretical model and the experimentally measured plume velocity. This work is supported by the U.S. Department of Energy Stewardship Science Academic Program in addition to the National Defense Science Engineering Graduate Fellowship.

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

    SciTech Connect

    Lecz, Zs.; Andreev, A.

    2015-04-15

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

  4. Nonlinear surface plasma wave induced target normal sheath acceleration of protons

    SciTech Connect

    Liu, C. S.; Tripathi, V. K. Shao, Xi; Liu, T. C.

    2015-02-15

    The mode structure of a large amplitude surface plasma wave (SPW) over a vacuum–plasma interface, including relativistic and ponderomotive nonlinearities, is deduced. It is shown that the SPW excited by a p-polarized laser on a rippled thin foil target can have larger amplitude than the transmitted laser amplitude and cause stronger target normal sheath acceleration of protons as reported in a recent experiment. Substantial enhancement in proton number also occurs due to the larger surface area covered by the SPW.

  5. Progress on laser plasma accelerators

    SciTech Connect

    Chen, P.

    1986-04-01

    Several laser plasma accelerator schemes are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA). Theory indicates that a very high acceleration gradient, of order 1 GeV/m, can exist in the plasma wave driven by the beating lasers. Experimental results obtained on the PBWA experiment at UCLA confirms this. Parameters related to the PBWA as an accelerator system are derived, among them issues concerning the efficiency and the laser power and energy requirements are discussed.

  6. Electron acceleration in relativistic plasma waves generated by a single frequency short-pulse laser

    SciTech Connect

    Coverdale, C.A.; Darrow, C.B.; Decker, C.D.; Mori, W.B.; Tzeng, K.C., Clayton, C.E.; Marsh, K.A.; Joshi, C.

    1995-04-27

    Experimental evidence for the acceleration of electrons in a relativistic plasma wave generated by Raman forward scattering (SRS-F) of a single-frequency short pulse laser are presented. A 1.053 {mu}m, 600 fsec, 5 TW laser was focused into a gas jet with a peak intensity of 8{times}10{sup 17} W/cm{sup 2}. At a plasma density of 2{times}10{sup 19} cm{sup {minus}3}, 2 MeV electrons were detected and their appearance was correlated with the anti-Stokes laser sideband generated by SRS-F. The results are in good agreement with 2-D PIC simulations. The use of short pulse lasers for making ultra-high gradient accelerators is explored.

  7. Blast Wave Formation by Laser-Sustained Nonequilibrium Plasma in the Laser-Driven In-Tube Accelerator Operation

    SciTech Connect

    Ogino, Yousuke; Ohnishi, Naofumi; Sawada, Keisuke; Sasoh, Akihiro

    2006-05-02

    Understanding the dynamics of laser-produced plasma is essentially important for increasing available thrust force in a gas-driven laser propulsion system such as laser-driven in-tube accelerator. A computer code is developed to explore the formation of expanding nonequilibrium plasma produced by laser irradiation. Various properties of the blast wave driven by the nonequilibrium plasma are examined. It is found that the blast wave propagation is substantially affected by radiative cooling effect for lower density case.

  8. High energy plasma accelerators

    SciTech Connect

    Tajima, T.

    1985-05-01

    Colinear intense laser beams ..omega../sub 0/, kappa/sub 0/ and ..omega../sub 1/, kappa/sub 1/ shone on a plasma with frequency separation equal to the electron plasma frequency ..omega../sub pe/ are capable of creating a coherent large longitudinal electric field E/sub L/ = mc ..omega../sub pe//e of the order of 1GeV/cm for a plasma density of 10/sup 18/ cm/sup -3/ through the laser beat excitation of plasma oscillations. Accompanying favorable and deleterious physical effects using this process for a high energy beat-wave accelerator are discussed: the longitudinal dephasing, pump depletion, the transverse laser diffraction, plasma turbulence effects, self-steepening, self-focusing, etc. The basic equation, the driven nonlinear Schroedinger equation, is derived to describe this system. Advanced accelerator concepts to overcome some of these problems are proposed, including the plasma fiber accelerator of various variations. An advanced laser architecture suitable for the beat-wave accelerator is suggested. Accelerator physics issues such as the luminosity are discussed. Applications of the present process to the current drive in a plasma and to the excitation of collective oscillations within nuclei are also discussed.

  9. Ion wave breaking acceleration

    NASA Astrophysics Data System (ADS)

    Liu, B.; Meyer-ter-Vehn, J.; Bamberg, K.-U.; Ma, W. J.; Liu, J.; He, X. T.; Yan, X. Q.; Ruhl, H.

    2016-07-01

    Laser driven ion wave breaking acceleration (IWBA) in plasma wakefields is investigated by means of a one-dimensional (1D) model and 1D/3D particle-in-cell (PIC) simulations. IWBA operates in relativistic transparent plasma for laser intensities in the range of 1020- 1023 W /cm2 . The threshold for IWBA is identified in the plane of plasma density and laser amplitude. In the region just beyond the threshold, self-injection takes place only for a fraction of ions and in a limited time period. This leads to well collimated ion pulses with peaked energy spectra, in particular for 3D geometry.

  10. High-power, kilojoule class laser channeling, surface wave generation and particle acceleration from underdense plasma

    NASA Astrophysics Data System (ADS)

    Willingale, L.; Krushelnick, K.; Thomas, A. G. R.; Maksimchuk, A.; Zulick, C.; Nilson, P. M.; Craxton, R. S.; Stoeckl, C.; Sangster, T. C.; Chen, H.; Cobble, J.; Norreys, P. A.; Scott, R. H. H.

    2011-10-01

    Experiments performed on the Omega EP laser facility (750 J of energy in 8.4 ps or 55 J - 300 J of energy in 0.9 ps), provide extreme conditions relevant to fast ignition studies. A CH plasma plume is used as the underdense target and the interaction of the laser pulse channeling through the plasma is imaged using proton radiography. Early time expansion, channel evolution, filamentation and self-correction is measured on a single shot via this method. Structures observed along the channel walls are interpreted as having developed from surface waves, and are a likely injection mechanism of electrons into the cavitated channel for acceleration. High-energy electron and proton spectra are measured and compared for the different pulse lengths from the experiment. Two dimensional particle-in-cell simulations give good agreement to these phenomenon. This work was supported by the National Laser Users' Facility (NLUF) and the DOE (Grant No. DE-NA000874).

  11. Ultra-short electron bunches by Velocity Bunching as required for plasma wave accelerations

    NASA Astrophysics Data System (ADS)

    Bacci, A.; Rossi, A. R.

    2014-03-01

    The generation of ultra-short bunches is nowadays a critical requirement for plasma wave accelerators, on which many laboratories world-wide are investigating or are close to starting with experimental activities. This requirement is true for both: external injection into "laser wake field accelerators", where injected beams need lengths around or shorter than 10 fs; and the "plasma wake field accelerators", where the wake field intensity scales like the driver bunch charge over the square of the rms bunch length (Qb / σz2). This work presents beam dynamic simulations, which show how to use the Velocity Bunching (VB) technique to obtain ultra-short bunches. The VB technique is applied to small bunch charges (0.5-15 pc) and it is driven with a proper control of the bunch density versus the bunch energy gain, which permits one to control the transverse beam emittance, the bunch length and the correlated longitudinal energy spread, in a peculiar manner. The compression optimizations by VB, shown in this work, are obtained using a layout very similar to SPARC's Linac one, which is a Linac designed to maximize VB performances.

  12. Electron acceleration during the decay of nonlinear Whistler waves in low-beta electron-ion plasma

    SciTech Connect

    Umeda, Takayuki; Saito, Shinji; Nariyuki, Yasuhiro E-mail: saito@stelab.nagoya-u.ac.jp

    2014-10-10

    Relativistic electron acceleration through dissipation of a nonlinear, short-wavelength, and monochromatic electromagnetic whistler wave in low-beta plasma is investigated by utilizing a one-dimensional fully relativistic electromagnetic particle-in-cell code. The nonlinear (large-amplitude) parent whistler wave decays through the parametric instability which enhances electrostatic ion acoustic waves and electromagnetic whistler waves. These waves satisfy the condition of three-wave coupling. Through the decay instability, the energy of electron bulk velocity supporting the parent wave is converted to the thermal energy perpendicular to the background magnetic field. Increase of the perpendicular temperature triggers the electron temperature anisotropy instability which generates broadband whistler waves and heats electrons in the parallel direction. The broadband whistler waves are inverse-cascaded during the relaxation of the electron temperature anisotropy. In lower-beta conditions, electrons with a pitch angle of about 90° are successively accelerated by inverse-cascaded whistler waves, and selected electrons are accelerated to over a Lorentz factor of 10. The result implies that the nonlinear dissipation of a finite-amplitude and short-wavelength whistler wave plays an important role in producing relativistic nonthermal electrons over a few MeV especially at lower beta plasmas.

  13. Acceleration gradient of a plasma wakefield accelerator

    SciTech Connect

    Uhm, Han S.

    2008-02-25

    The phase velocity of the wakefield waves is identical to the electron beam velocity. A theoretical analysis indicates that the acceleration gradient of the wakefield accelerator normalized by the wave breaking amplitude is K{sub 0}({xi})/K{sub 1}({xi}), where K{sub 0}({xi}) and K{sub 1}({xi}) are the modified Bessel functions of the second kind of order zero and one, respectively and {xi} is the beam parameter representing the beam intensity. It is also shown that the beam density must be considerably higher than the diffuse plasma density for the large radial velocity of plasma electrons that are required for a high acceleration gradient.

  14. Enhanced acceleration of injected electrons in a laser-beat-wave-induced plasma channel.

    PubMed

    Tochitsky, S Ya; Narang, R; Filip, C V; Musumeci, P; Clayton, C E; Yoder, R B; Marsh, K A; Rosenzweig, J B; Pellegrini, C; Joshi, C

    2004-03-01

    Enhanced energy gain of externally injected electrons by a approximately 3 cm long, high-gradient relativistic plasma wave (RPW) is demonstrated. Using a CO2 laser beat wave of duration longer than the ion motion time across the laser spot size, a laser self-guiding process is initiated in a plasma channel. Guiding compensates for ionization-induced defocusing (IID) creating a longer plasma, which extends the interaction length between electrons and the RPW. In contrast to a maximum energy gain of 10 MeV when IID is dominant, the electrons gain up to 38 MeV energy in a laser-beat-wave-induced plasma channel. PMID:15089478

  15. Plasma inverse transition acceleration

    SciTech Connect

    Xie, Ming

    2001-06-18

    It can be proved fundamentally from the reciprocity theorem with which the electromagnetism is endowed that corresponding to each spontaneous process of radiation by a charged particle there is an inverse process which defines a unique acceleration mechanism, from Cherenkov radiation to inverse Cherenkov acceleration (ICA) [1], from Smith-Purcell radiation to inverse Smith-Purcell acceleration (ISPA) [2], and from undulator radiation to inverse undulator acceleration (IUA) [3]. There is no exception. Yet, for nearly 30 years after each of the aforementioned inverse processes has been clarified for laser acceleration, inverse transition acceleration (ITA), despite speculation [4], has remained the least understood, and above all, no practical implementation of ITA has been found, until now. Unlike all its counterparts in which phase synchronism is established one way or the other such that a particle can continuously gain energy from an acceleration wave, the ITA to be discussed here, termed plasma inverse transition acceleration (PITA), operates under fundamentally different principle. As a result, the discovery of PITA has been delayed for decades, waiting for a conceptual breakthrough in accelerator physics: the principle of alternating gradient acceleration [5, 6, 7, 8, 9, 10]. In fact, PITA was invented [7, 8] as one of several realizations of the new principle.

  16. Improved plasma accelerator

    NASA Technical Reports Server (NTRS)

    Cheng, D. Y.

    1971-01-01

    Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

  17. Recent Advances in Plasma Acceleration

    SciTech Connect

    Hogan, Mark

    2007-03-19

    The costs and the time scales of colliders intended to reach the energy frontier are such that it is important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators a drive beam, either laser or particle, produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultra-high accelerating fields over a substantial length to achieve a significant energy gain. More than 42 GeV energy gain was achieved in an 85 cm long plasma wakefield accelerator driven by a 42 GeV electron drive beam in the Final Focus Test Beam (FFTB) Facility at SLAC. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of {approx}52 GV/m. This effectively doubles their energy, producing the energy gain of the 3 km long SLAC accelerator in less than a meter for a small fraction of the electrons in the injected bunch. Prospects for a drive-witness bunch configuration and high-gradient positron acceleration experiments planned for the SABER facility will be discussed.

  18. Large amplitude inertial compressional Alfvénic shock and solitary waves, and acceleration of ions in magnetohydrodynamic plasmas

    SciTech Connect

    Panwar, Anuraj; Rizvi, H.; Ryu, C. M.

    2013-05-15

    Large amplitude inertial compressional Alfvénic shock and solitary waves in magnetohydrodynamic plasmas are investigated. Dispersive effect caused by non-ideal electron inertia currents perpendicular to the ambient magnetic field can balance the nonlinear steepening of waves leading to the formation of a soliton. A Sagdeev-potential formalism is employed to derive an energy-balance like equation. The range of allowed values of the soliton speed, M (Mach number), plasma β (ratio of the plasma thermal pressure to the pressure in the confining magnetic field), and electron inertia, wherein solitary waves may exist, are determined. Depth of the potential increases with increasing the Mach number and plasma β, however decreases with the increasing electron inertia. The height of soliton increases with increasing in Mach number and decreases with plasma β. And with increasing electron inertial length, the width of soliton increases. The electron-ion collisional dissipation results a dissipative inertial compressional Alfvén wave, which can produce a shock like structure and can efficiently accelerate ions to the order of the local Alfvén velocity. The shock height increases with the increasing collision frequency, but shock height decreases with increasing plasma β.

  19. The heating and acceleration actions of the solar plasma wave by QFT

    NASA Astrophysics Data System (ADS)

    Chen, Shao-Guang

    solar plasma will left-right separate by Lorentz force and by the feedback mechanism of Lorentz force the positive - negative charge will left-right vibrate. The plasma on the move will accompany with up-down and left-right vibrating and become the wave. Though the frequent of the plasma wave is not high, but its heating and acceleration actions will be not less then that of the microwave and laser because of its mass and energy far large then that of the microwave and laser.

  20. Generation of the cosmic rays flux variations due to surfatron acceleration of charges by electromagnetic waves in space plasma

    NASA Astrophysics Data System (ADS)

    Erokhin, Nikolay; Loznikov, Vladimir; Shkevov, Rumen; Zolnikova, Nadezhda; Mikhailovskaya, Ludmila

    2016-07-01

    The analysis of experimental data on the spectra of cosmic rays (CR) has shown their variability on time scales of a few years, in particular, CR variations observed in E / Z range from TeV to 10000 TeV, where E is the energy of the particle, Z is its charge number. Consequently, the source of these variations must be located at a distance of no more than 1 parsec from the sun in the closest local interstellar clouds. As a mechanism of such variations appearance it is considered the surfatron acceleration of CR particles by electromagnetic wave in a relatively quiet space plasma. On the basis of developed model the numerical calculations were performed for particle capture dynamics (electrons, protons, helium and iron nuclei) in the wave effective potential well with a following growth their energy by 3-6 orders of magnitude. Optimal conditions for the implementation of charged particles surfatron acceleration in space plasma, the rate of trapped particles energy growth, the dynamics of wave phase on the captured particle trajectory, a temporal dynamics of components for charge impulse momentum and speed were studied. It is indicated that the capture of a small fraction of particles by wave for energies about TeV and less followed by their surfatron acceleration to an energy of about 10000 TeV will lead to a significant increase in the CR flux at such high energies. Thus CL flow variations are conditioned by changes in the space weather parameters

  1. Basic concepts in plasma accelerators.

    PubMed

    Bingham, Robert

    2006-03-15

    In this article, we present the underlying physics and the present status of high gradient and high-energy plasma accelerators. With the development of compact short pulse high-brightness lasers and electron and positron beams, new areas of studies for laser/particle beam-matter interactions is opening up. A number of methods are being pursued vigorously to achieve ultra-high-acceleration gradients. These include the plasma beat wave accelerator (PBWA) mechanism which uses conventional long pulse ( approximately 100 ps) modest intensity lasers (I approximately 10(14)-10(16) W cm(-2)), the laser wakefield accelerator (LWFA) which uses the new breed of compact high-brightness lasers (<1 ps) and intensities >10(18) W cm(-2), self-modulated laser wakefield accelerator (SMLWFA) concept which combines elements of stimulated Raman forward scattering (SRFS) and electron acceleration by nonlinear plasma waves excited by relativistic electron and positron bunches the plasma wakefield accelerator. In the ultra-high intensity regime, laser/particle beam-plasma interactions are highly nonlinear and relativistic, leading to new phenomenon such as the plasma wakefield excitation for particle acceleration, relativistic self-focusing and guiding of laser beams, high-harmonic generation, acceleration of electrons, positrons, protons and photons. Fields greater than 1 GV cm(-1) have been generated with monoenergetic particle beams accelerated to about 100 MeV in millimetre distances recorded. Plasma wakefields driven by both electron and positron beams at the Stanford linear accelerator centre (SLAC) facility have accelerated the tail of the beams. PMID:16483948

  2. Trapping of high-energy electrons into regime of surfatron acceleration by electromagnetic waves in space plasma

    SciTech Connect

    Erokhin, A. N.; Erokhin, N. S.; Milant'ev, V. P.

    2012-05-15

    The phenomenon of trapping of weakly relativistic charged particles (with kinetic energies on the order of mc{sup 2}) into a regime of surfatron acceleration by an electromagnetic wave that propagates in plasma across a weak external magnetic field has been studied using nonlinear numerical calculations based on a solution of the relativistic equations of motion. Analysis showed that, for the wave amplitude above a certain threshold value and the initial wave phase outside the interval favorable for the surfing regime, the trajectory of a charged particle initially corresponds to its cyclotron rotation in the external magnetic field. For the initial particle energies studied, the period of this rotation is relatively short. After a certain number (from several dozen to several thousand and above) of periods of rotation, the wave phase takes a value that is favorable for trapping of the charged particle on its trajectory by the electromagnetic wave, provided the Cherenkov resonance conditions are satisfied. As a result, the wave traps the charged particle and imparts it an ultrarelativistic acceleration. In momentum space, the region of trapping into the regime of surfing on an electromagnetic wave turns out to be rather large.

  3. Solar system plasma waves

    NASA Technical Reports Server (NTRS)

    Gurnett, Donald A.

    1995-01-01

    An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation.

  4. Plasma physics. Stochastic electron acceleration during spontaneous turbulent reconnection in a strong shock wave.

    PubMed

    Matsumoto, Y; Amano, T; Kato, T N; Hoshino, M

    2015-02-27

    Explosive phenomena such as supernova remnant shocks and solar flares have demonstrated evidence for the production of relativistic particles. Interest has therefore been renewed in collisionless shock waves and magnetic reconnection as a means to achieve such energies. Although ions can be energized during such phenomena, the relativistic energy of the electrons remains a puzzle for theory. We present supercomputer simulations showing that efficient electron energization can occur during turbulent magnetic reconnection arising from a strong collisionless shock. Upstream electrons undergo first-order Fermi acceleration by colliding with reconnection jets and magnetic islands, giving rise to a nonthermal relativistic population downstream. These results shed new light on magnetic reconnection as an agent of energy dissipation and particle acceleration in strong shock waves. PMID:25722406

  5. Development of a GPU-Accelerated 3-D Full-Wave Code for Electromagnetic Wave Propagation in a Cold Plasma

    NASA Astrophysics Data System (ADS)

    Woodbury, D.; Kubota, S.; Johnson, I.

    2014-10-01

    Computer simulations of electromagnetic wave propagation in magnetized plasmas are an important tool for both plasma heating and diagnostics. For active millimeter-wave and microwave diagnostics, accurately modeling the evolution of the beam parameters for launched, reflected or scattered waves in a toroidal plasma requires that calculations be done using the full 3-D geometry. Previously, we reported on the application of GPGPU (General-Purpose computing on Graphics Processing Units) to a 3-D vacuum Maxwell code using the FDTD (Finite-Difference Time-Domain) method. Tests were done for Gaussian beam propagation with a hard source antenna, utilizing the parallel processing capabilities of the NVIDIA K20M. In the current study, we have modified the 3-D code to include a soft source antenna and an induced current density based on the cold plasma approximation. Results from Gaussian beam propagation in an inhomogeneous anisotropic plasma, along with comparisons to ray- and beam-tracing calculations will be presented. Additional enhancements, such as advanced coding techniques for improved speedup, will also be investigated. Supported by U.S. DoE Grant DE-FG02-99-ER54527 and in part by the U.S. DoE, Office of Science, WDTS under the Science Undergraduate Laboratory Internship program.

  6. Near-GeV acceleration of electrons by a nonlinear plasma wave driven by a self-guided laser pulse.

    PubMed

    Kneip, S; Nagel, S R; Martins, S F; Mangles, S P D; Bellei, C; Chekhlov, O; Clarke, R J; Delerue, N; Divall, E J; Doucas, G; Ertel, K; Fiuza, F; Fonseca, R; Foster, P; Hawkes, S J; Hooker, C J; Krushelnick, K; Mori, W B; Palmer, C A J; Phuoc, K Ta; Rajeev, P P; Schreiber, J; Streeter, M J V; Urner, D; Vieira, J; Silva, L O; Najmudin, Z

    2009-07-17

    The acceleration of electrons to approximately 0.8 GeV has been observed in a self-injecting laser wakefield accelerator driven at a plasma density of 5.5x10(18) cm(-3) by a 10 J, 55 fs, 800 nm laser pulse in the blowout regime. The laser pulse is found to be self-guided for 1 cm (>10zR), by measurement of a single filament containing >30% of the initial laser energy at this distance. Three-dimensional particle in cell simulations show that the intensity within the guided filament is amplified beyond its initial focused value to a normalized vector potential of a0>6, thus driving a highly nonlinear plasma wave. PMID:19659287

  7. Accelerating Particles with Plasma

    SciTech Connect

    Litos, Michael; Hogan, Mark

    2014-11-05

    Researchers at SLAC explain how they use plasma wakefields to accelerate bunches of electrons to very high energies over only a short distance. Their experiments offer a possible path for the future of particle accelerators.

  8. Plasma-based Accelerator with Magnetic Compression

    SciTech Connect

    Paul F. Schmit and Nathaniel J. Fisch

    2012-06-28

    Electron dephasing is a major gain-inhibiting effect in plasma-based accelerators. A novel method is proposed to overcome dephasing, in which the modulation of a modest (#24; O(10 kG)), axial, uniform magnetic field in the acceleration channel leads to densification of the plasma through magnetic compression, enabling direct, time-resolved control of the plasma wave properties. The methodology is broadly applicable and can be optimized to improve the leading acceleration approaches, including plasma beat-wave, plasma wakefield, and laser wakefield acceleration. The advantages of magnetic compression compared to other proposed schemes to overcome dephasing are identified.

  9. Plasma-based accelerator with magnetic compression.

    PubMed

    Schmit, P F; Fisch, N J

    2012-12-21

    Electron dephasing is a major gain-inhibiting effect in plasma-based accelerators. A novel method is proposed to overcome dephasing, in which the modulation of a modest [~O(10 kG)], axial, uniform magnetic field in the acceleration channel leads to densification of the plasma through magnetic compression, enabling direct, time-resolved control of the plasma wave properties. The methodology is broadly applicable and can be optimized to improve the leading acceleration approaches, including plasma beat wave, plasma wakefield, and laser wakefield acceleration. The advantages of magnetic compression are compared to other proposed techniques to overcome dephasing. PMID:23368475

  10. Plasma-Based Accelerator with Magnetic Compression

    NASA Astrophysics Data System (ADS)

    Schmit, P. F.; Fisch, N. J.

    2012-12-01

    Electron dephasing is a major gain-inhibiting effect in plasma-based accelerators. A novel method is proposed to overcome dephasing, in which the modulation of a modest [˜O(10kG)], axial, uniform magnetic field in the acceleration channel leads to densification of the plasma through magnetic compression, enabling direct, time-resolved control of the plasma wave properties. The methodology is broadly applicable and can be optimized to improve the leading acceleration approaches, including plasma beat wave, plasma wakefield, and laser wakefield acceleration. The advantages of magnetic compression are compared to other proposed techniques to overcome dephasing.

  11. Nonlinear mixing of electromagnetic waves in plasmas.

    PubMed

    Stefan, V; Cohen, B I; Joshi, C

    1989-01-27

    Recently, a strong research effort has been focused on applications of beat waves in plasma interactions. This research has important implications for various aspects of plasma physics and plasma technology. This article reviews the present status of the field and comments on plasma probing, heating of magnetically confined and laser plasmas, ionospheric plasma modification, beat-wave particle acceleration, beat-wave current drive in toroidal devices, beat wave-driven free-electron lasers, and phase conjugation with beat waves. PMID:17799185

  12. Amplification of Beam Acceleration in a Plasma by Plasma Instability

    SciTech Connect

    Valeri Lebedev

    1998-09-01

    Although achieving of high accelerating field in a plasma has been demonstrated experimentally, a practical use of such a scheme for building a large accelerator is questionable. A novel scheme of beam acceleration by a plasma wave is considered in this article. The scheme is based on an initial excitation of a plasma wave by a probe beam with comparatively modest intensity. This seed excitation is then amplified by plasma instability, so that the test beam which follows the probe beam with a small delay will be accelerated by the plasma wave with an amplitude significantly exceeding the initial amplitude of the wave. Because of small interaction between the synchronization beam and the plasma, such a scheme allows one to excite a plasma over large length and, consequently, to build a large accelerator.

  13. Stochastic gyroresonant electron acceleration in a low-beta plasma. I - Interaction with parallel transverse cold plasma waves

    NASA Technical Reports Server (NTRS)

    Steinacker, Juergen; Miller, James A.

    1992-01-01

    The gyroresonance of electrons with parallel transverse cold plasma waves is considered, and the Fokker-Planck equation describing the evolution of the electron distribution function in the presence of a spectrum of turbulence is derived. A new resonance which produces a divergence in the Fokker-Planck coefficients is identified; it results when the electron is in gyroresonance with a wave that has a group velocity equal to the velocity of the electron along the magnetic field. Under the assumption of a power-law spectral density, the Fokker-Planck coefficients are calculated numerically, and their complicated momentum and pitch-angle dependence, as well as the influence of various approximations to the dispersion relation, gyroresonance condition, and spectral density are discussed. It is found that there is no resonance gap at any pitch angle as long as the full gyroresonance condition is used and waves propagating on both directions are present.

  14. Charged Particle Acceleration by Lasers in Plasmas

    SciTech Connect

    Liu, C. S.; Tripathi, V. K.

    2007-07-11

    Several physical processes of laser electron acceleration in plasmas are revisited. A laser beam can drive plasma waves which in turn can accelerate resonant electrons. If these plasma waves can reach amplitude limited only by wave breaking alone, then the corresponding accelerating gradient in the plasma wave is of the order of electron rest mass energy per plasma skin depth, typically about GEV per centimeter. This is several orders of magnitudes higher than the conventional RF field gradient, giving rise to the possibility of compact accelerators needed for high energy physics research as well as medical and other applications. The chirped short pulse laser, with intensity exceeding the threshold for relativistic self focusing, can generate ion bubble in its wake by expelling electrons. The electrons at the bubble boundary, surge toward the stagnation point and pile up there. As the pile acquires a critical size, these electrons are injected into the bubble and accelerated by the combined fields of ion space charge and the plasma wave to Gev in energy. Most remarkably these electrons are bunched in phase space while being accelerated to high energy, resulting in near mono-energetic electron beam of high beam quality, with narrow energy spread. We review also other processes related to laser electron acceleration, such as acceleration in plasma wave assisted by ponderomotive force and betatron acceleration.

  15. Quasi-monoenergetic ion beam acceleration by laser-driven shock and solitary waves in near-critical plasmas

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    Ion acceleration in near-critical plasmas driven by intense laser pulses is investigated theoretically and numerically. A theoretical model has been given for clarification of the ion acceleration dynamics in relation to different laser and target parameters. Two distinct regimes have been identified, where ions are accelerated by, respectively, the laser-induced shock wave in the weakly driven regime (comparatively low laser intensity) and the nonlinear solitary wave in the strongly driven regime (comparatively high laser intensity). Two-dimensional particle-in-cell simulations show that quasi-monoenergetic proton beams with a peak energy of 94.6 MeV and an energy spread 15.8% are obtained by intense laser pulses at intensity I0 = 3 × 1020 W/cm2 and pulse duration τ = 0.5 ps in the strongly driven regime, which is more advantageous than that got in the weakly driven regime. In addition, 233 MeV proton beams with narrow spread can be produced by extending τ to 1.0 ps in the strongly driven regime.

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

    NASA Astrophysics Data System (ADS)

    Tsiklauri, D.

    2014-12-01

    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 refaction 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) [2] H. Schmitz, D. Tsiklauri, Phys. Plasmas 20, 062903 (2013) [3] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 19, 112903 (2012) [4] M. Skender, D. Tsiklauri, Phys. Plasmas 21, 042904 (2014) [5] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 21, 012903 (2014)

  17. A side-injected-laser plasma accelerator

    SciTech Connect

    Katsouleas, T.; Dawson, J.M.; Sultana, D.; Yun, Y.T.

    1985-10-01

    A new method for driving relativistic plasma waves capable of ultra-high acceleration gradients (order 1GeV/cm) is presented. By injecting a single laser frequency from the side, rather than colinearly with the accelerated particles, both pump depletion and particle dephasing may be avoidable. The coupling of the side injected laser to the relativistic plasma wave via a pre-formed density ripple in the plasma is modelled analytically and with computer simulation.

  18. Compact Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2004-01-01

    A plasma accelerator has been conceived for both material-processing and spacecraft-propulsion applications. This accelerator generates and accelerates ions within a very small volume. Because of its compactness, this accelerator could be nearly ideal for primary or station-keeping propulsion for spacecraft having masses between 1 and 20 kg. Because this accelerator is designed to generate beams of ions having energies between 50 and 200 eV, it could also be used for surface modification or activation of thin films.

  19. Waves in Space Plasmas

    NASA Astrophysics Data System (ADS)

    Gurnett, Donald

    2008-11-01

    Although low-frequency radio waves of extra-terrestrial origin were known over a century ago, it wasn't until the beginning of the space era fifty years ago that the origin of these waves could be adequately investigated. Since then spacecraft-borne instruments have shown that space plasmas exhibit an almost bewildering variety of wave phenomena, sometimes referred to as the plasma wave zoo. In this talk I will focus on two types of waves that occur in the magnetospheres of the strongly magnetized planets. They are whistler mode emissions and cyclotron maser radiation. Whistler mode emissions are generated in the now famous plasma wave mode known as the whistler mode, and cyclotron maser radiation is emitted mainly in the right-hand polarized free space mode. Both involve a cyclotron resonant interaction and require a perpendicular anisotropy to achieve wave growth. However, the origin of the anisotropy is different in the two cases. Whistler mode emissions occur in planetary radiation belts and are driven by the loss-cone anisotropy imposed by the planet. The resulting waves play a major role in the scattering and loss of radiation belt electrons. In contrast, the cyclotron maser radiation is generated in the auroral regions where parallel electric fields accelerate down-going electrons to high energies. The wave growth is driven by the shell distribution that arises from a combination of the parallel electric field and the magnetic mirror force. The resulting radiation is extremely intense and can be detected at great distances as an escaping radio emission. Both the whistler mode emissions and the cyclotron maser radiation display an amazing amount of fine structure. This structure is thought to be due to nonlinear trapping of the resonant electrons. The exact nonlinear mechanisms involved are still a topic of current study.

  20. Plasma-based accelerator structures

    SciTech Connect

    Schroeder, Carl B.

    1999-12-01

    Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating structure, the generation of ultrashort electron bunches, and the propagation of laser pulses is underdense plasmas.

  1. Argonne plasma wake-field acceleration experiments

    SciTech Connect

    Rosenzweig, J.B.; Cole, B.; Gai, W.; Konecny, R.; Norem, J.; Schoessow, P.; Simpson, J.

    1989-03-14

    Four years after the initial proposal of the Plasma Wake-field Accelerator (PWFA), it continues to be the object of much investigation, due to the promise of the ultra-high accelerating gradients that can exist in relativistic plasma waves driven in the wake of charged particle beams. These wake-fields are of interest both in the laboratory, for acceleration and focusing of electrons and positrons in future linear colliders, and in nature as a possible cosmic ray acceleration mechanism. The purpose of the present work is to review the recent experimental advances made in PWFA research at Argonne National Laboratory. Some of the topics discussed are: the Argonne Advanced Accelerator Test Facility; linear plasma wake-field theory; measurement of linear plasma wake-fields; review of nonlinear plasma wave theory; and experimental measurement of nonlinear plasma wake-fields. 25 refs., 11 figs.

  2. Tapered plasma channels to phase-lock accelerating and focusing forces in laser-plasma accelerators

    SciTech Connect

    Rittershofer, W.; Schroeder, C.B.; Esarey, E.; Gruner, F.J.; Leemans, W.P.

    2010-05-17

    Tapered plasma channels are considered for controlling dephasing of a beam with respect to a plasma wave driven by a weakly-relativistic, short-pulse laser. Tapering allows for enhanced energy gain in a single laser plasma accelerator stage. Expressions are derived for the taper, or longitudinal plasma density variation, required to maintain a beam at a constant phase in the longitudinal and/or transverse fields of the plasma wave. In a plasma channel, the phase velocities of the longitudinal and transverse fields differ, and, hence, the required tapering differs. The length over which the tapered plasma density becomes singular is calculated. Linear plasma tapering as well as discontinuous plasma tapering, which moves beams to adjacent plasma wave buckets, are also considered. The energy gain of an accelerated electron in a tapered laser-plasma accelerator is calculated and the laser pulse length to optimize the energy gain is determined.

  3. Laser Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Malka, Victor

    The continuing development of powerful laser systems has permitted to extend the interaction of laser beams with matter far into the relativistic domain, and to demonstrate new approaches for producing energetic particle beams. The extremely large electric fields, with amplitudes exceeding the TV/m level, that are produced in plasma medium are of relevance particle acceleration. Since the value of this longitudinal electric field, 10,000 times larger than those produced in conventional radio-frequency cavities, plasma accelerators appear to be very promising for the development of compact accelerators. The incredible progresses in the understanding of laser plasma interaction physic, allows an excellent control of electron injection and acceleration. Thanks to these recent achievements, laser plasma accelerators deliver today high quality beams of energetic radiation and particles. These beams have a number of interesting properties such as shortness, brightness and spatial quality, and could lend themselves to applications in many fields, including medicine, radio-biology, chemistry, physics and material science,security (material inspection), and of course in accelerator science.

  4. Wave and particle dynamics of the beat-wave accelerator

    SciTech Connect

    Gibbon, P. )

    1989-10-15

    We present two-dimensional wave-envelope studies of the interaction between a plasma beat-wave and the laser pumps which drive it. A new method of focusing is demonstrated which requires the plasma wave to be driven slightly below its resonant frequency. Test particles are employed to investigate possible means of extending the accelerator stage length. {copyright} 1989 American Institute of Physics

  5. Physics of Laser-driven plasma-based acceleration

    SciTech Connect

    Esarey, Eric; Schroeder, Carl B.

    2003-06-30

    The physics of plasma-based accelerators driven by short-pulse lasers is reviewed. This includes the laser wake-field accelerator, the plasma beat wave accelerator, the self-modulated laser wake-field accelerator, and plasma waves driven by multiple laser pulses. The properties of linear and nonlinear plasma waves are discussed, as well as electron acceleration in plasma waves. Methods for injecting and trapping plasma electrons in plasma waves are also discussed. Limits to the electron energy gain are summarized, including laser pulse direction, electron dephasing, laser pulse energy depletion, as well as beam loading limitations. The basic physics of laser pulse evolution in underdense plasmas is also reviewed. This includes the propagation, self-focusing, and guiding of laser pulses in uniform plasmas and plasmas with preformed density channels. Instabilities relevant to intense short-pulse laser-plasma interactions, such as Raman, self-modulation, and hose instabilities, are discussed. Recent experimental results are summarized.

  6. Wave guided laser wake-field acceleration in splash plasma channels

    NASA Astrophysics Data System (ADS)

    MIZUTA, Yoshio; HOSOKAI, Tomonao; MASUDA, Shinichi; ZHIDKOV, Alexei; NAKANII, Nobuhiko; JIN, Zhan; NAKAHARA, Hiroki; KOHARA, Tomohiro; IWASA, Kenta; KANDO, Masaki; BULANOV, Sergei; KODAMA, Ryosuke

    2016-03-01

    A transient plasma micro optics (plasma channel and focusing plasma optics- TPMO) in the LWFA provides controllable electron self-injections that result in production of higher quality bunches. In recent study of the TPMO, the deep, straight and short-lived plasma channels [splash plasma channel] were produced by picosecond and sub-picosecond laser pulses in the ponderomotive force dominant regime. Various techniques were used to characterize those channels in argon gas jets irradiated by moderate intensity, ∼1015-16 W/cm2, laser pulses with their durations from sub-picoseconds.

  7. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1989-01-01

    The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass. The goal of the present program is to demonstrate feasibility of the EPA thruster concept through experimental and theoretical investigations of the EPA acceleration mechanism and discharge chamber performance. Experimental investigations will include operating the test bed ion (TBI) engine as an EPA thruster and parametrically varying the thruster geometry and operating conditions to quantify the electrostatic plasma acceleration effect. The theoretical investigations will include the development of a discharge chamber model which describes the relationships between the engine size, plasma properties, and overall performance. For the EPA thruster to be a viable propulsion concept, overall thruster efficiencies approaching 30% with specific impulses approaching 1000 s must be achieved.

  8. Auroral plasma acceleration processes at Mars

    NASA Astrophysics Data System (ADS)

    Lundin, R.; Barabash, S.; Winningham, D.

    2012-09-01

    Following the first Mars Express (MEX) findings of auroral plasma acceleration above Martian magnetic anomalies[1, 2], a more detailed analysis is carried out regarding the physical processes that leads to plasma acceleration, and how they connect to the dynamo-, and energy source regions. The ultimate energy source for Martian plasma acceleration is the solar wind. The question is, by what mechanisms is solar wind energy and momentum transferred into the magnetic flux tubes that connect to Martian magnetic anomalies? What are the key plasma acceleration processes that lead to aurora and the associated ionospheric plasma outflow from Mars? The experimental setup on MEX limits our capability to carry out "auroral physics" at Mars. However, with knowledge acquired from the Earth, we may draw some analogies with terrestrial auroral physics. Using the limited data set available, consisting of primarily ASPERA and MARSIS data, an interesting picture of aurora at Mars emerges. There are some strong similarities between accelerated/heated electrons and ions in the nightside high altitude region above Mars and the electron/ion acceleration above Terrestrial discrete aurora. Nearly monoenergetic downgoing electrons are observed in conjunction with nearly monoenergetic upgoing ions. Monoenergetic counterstreaming ions and electrons is the signature of plasma acceleration in quasi-static electric fields. However, compared to the Earth's aurora, with auroral process guided by a dipole field, aurora at Mars is expected to form complex patterns in the multipole environment governed by the Martian crustal magnetic field regions. Moreover, temporal/spatial scales are different at Mars. It is therefore of interest to mention another common characteristics that exist for Earth and Mars, plasma acceleration by waves. Low-frequency, Alfvén, waves is a very powerful means of plasma acceleration in the Earth's magnetosphere. Low-frequency waves associated with plasma acceleration

  9. Ion acceleration by electro-magnetic plasma waves in the vicinity of SLAMS boundary observed in the front of the Earth's quasi-parallel bow shock

    NASA Astrophysics Data System (ADS)

    Kis, A.; Agapitov, O.; Krasnoselskikh, V.; Dandouras, I.; Lucek, E. A.

    2012-04-01

    A well known feature of collisionless shocks which are formed in space plasmas is their capability to accelerate particles to high energies. On the other hand, the exact mechanism how this acceleration takes place is still unknown. This is especially true in the case of the so-called seed particle population, i.e. those particles which are being injected into the process of acceleration. In our study we present a case study of Gyroresonant Surfing Acceleration (GSA) observed on the quasi-parallel side of the Earth's bow shock. For our analysis we use simultaneous multi-spacecraft measurement data provided by the Cluster spacecraft ion (CIS), magnetic (FGM) and electric field and wave instrument (EFW) during a time period of large inter-spacecraft separation distance. Our results show evidence that the gyroresonance surfing acceleration takes place as a consequence of interaction between monochromatic (or quasi-monochromatic) electromagnetic plasma waves and short large amplitude magnetic structures (SLAMS). The magnetic field inhomogenity mirror force keeps the ions trapped by the wave in resonant condition which results in effective particle velocity increase and thus energy gain. Since monochromatic wave packets with circular polarization and various magnetic structures are very commonly observed in the front of the Earth's quasi-parallel bow shock, the gyroresonant surfing acceleration proves to be an effective particle injection mechanism resulting in the formation of the seed particle population.

  10. EDITORIAL: Laser and plasma accelerators Laser and plasma accelerators

    NASA Astrophysics Data System (ADS)

    Bingham, Robert

    2009-02-01

    This special issue on laser and plasma accelerators illustrates the rapid advancement and diverse applications of laser and plasma accelerators. Plasma is an attractive medium for particle acceleration because of the high electric field it can sustain, with studies of acceleration processes remaining one of the most important areas of research in both laboratory and astrophysical plasmas. The rapid advance in laser and accelerator technology has led to the development of terawatt and petawatt laser systems with ultra-high intensities and short sub-picosecond pulses, which are used to generate wakefields in plasma. Recent successes include the demonstration by several groups in 2004 of quasi-monoenergetic electron beams by wakefields in the bubble regime with the GeV energy barrier being reached in 2006, and the energy doubling of the SLAC high-energy electron beam from 42 to 85 GeV. The electron beams generated by the laser plasma driven wakefields have good spatial quality with energies ranging from MeV to GeV. A unique feature is that they are ultra-short bunches with simulations showing that they can be as short as a few femtoseconds with low-energy spread, making these beams ideal for a variety of applications ranging from novel high-brightness radiation sources for medicine, material science and ultrafast time-resolved radiobiology or chemistry. Laser driven ion acceleration experiments have also made significant advances over the last few years with applications in laser fusion, nuclear physics and medicine. Attention is focused on the possibility of producing quasi-mono-energetic ions with energies ranging from hundreds of MeV to GeV per nucleon. New acceleration mechanisms are being studied, including ion acceleration from ultra-thin foils and direct laser acceleration. The application of wakefields or beat waves in other areas of science such as astrophysics and particle physics is beginning to take off, such as the study of cosmic accelerators considered

  11. Cosmic Plasma Wakefield Acceleration

    NASA Astrophysics Data System (ADS)

    Chen, Pisin; Tajima, Toshiki; Takahashi, Yoshiyuki

    2002-10-01

    A cosmic acceleration mechanism is introduced which is based on the wakefields excited by the Alfven shocks in a relativistically flowing plasma. We show that there exists a threshold condition for transparency below which the accelerating particle is collision-free and suffers little energy loss in the plasma medium. The stochastic encounters of the random accelerating-decelerating phases results in a power-law energy spectrum: f([epsilon]) [is proportional to] 1/[epsilon]2. As an example, we discuss the possible production of super-GZK ultra high energy cosmic rays (UHECR) in the atmosphere of gamma ray bursts. The estimated event rate in our model agrees with that from UHECR observations. [copyright] 2002 American Institute of Physics

  12. The heating and acceleration actions of the solar plasma wave by QFT

    NASA Astrophysics Data System (ADS)

    Chen, Shao-Guang

    measuring value of one-way velocity of light (H05-0006-08) to replace the infinity value of light speed measured by Galileo in 1607, thereby the mass m in NM will become variable m. Or else, the energy of electron in accelerator should not larger than 0.51Mev which conflict with the experimental fact. According to the variable mass and the definition of force we again get Eq.(1) from NM without hypothesis, i.e., NM is generalized in which Galileo coordinates transformation and the action at a distance will be of no effect. Eq.(1) has more reliable experimental base and generalized NM may be applied to the high-speed and the microscopic conditions. Because of the result of a test of GR with use of a hydrogen-maser frequency standard in a spacecraft launched nearly vertically upward to 10000 km (R. F. C. Vessot et.al., Phys. Rev. Lett. 45, 2081 (1980)), the isotropy of one-way velocity of light had been validated at the 1*10 (-10) level (D2.4-0030-12, H0.1-0009-12, H0.2-0008-12). Again from the Lorentz transformation (H01-0006-08) and the uncertainty principle (H05-0036-10) deduced from the metrical results of Doppler effects, SR and QM, thereby QFT and GR, all become the inferential theorems from generalized NM. Eq.(1) is as a bridge to join the modern physics and classical physics. In my paper ‘Basal electric and magnetic fields of celestial bodies come from positive-negative charge separation caused by gravitation of quasi-Casimir pressure in weak interaction’ (D31-0054-10): According to QFT the gravitation is the statistic average pressure collided by net virtual neutrinos nuν _{0} flux, the net nuν _{0} flux can press a part freedom electrons in plasma of ionosphere into the surface of celestial bodies, the static electric force of redundant positive ions prevents electrons further falling and till reach the equilibrium of stable spatial charge distribution, which is just the cause of the geomagnetic field and the geo-electric field. In the solar surface plasma add

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

    NASA Astrophysics Data System (ADS)

    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

  14. Induced emission of Alfvén waves in inhomogeneous streaming plasma: implications for solar corona heating and solar wind acceleration.

    PubMed

    Galinsky, V L; Shevchenko, V I

    2013-07-01

    The results of a self-consistent kinetic model of heating the solar corona and accelerating the fast solar wind are presented for plasma flowing in a nonuniform magnetic field configuration of near-Sun conditions. The model is based on a scale separation between the large transit or inhomogeneity scales and the small dissipation scales. The macroscale instability of the marginally stable particle distribution function compliments the resonant frequency sweeping dissipation of transient Alfvén waves by their induced emission in inhomogeneous streaming plasma that provides enough energy for keeping the plasma temperature decaying not faster than r(-1) in close agreement with in situ heliospheric observations. PMID:23863008

  15. Thermal effects in plasma-based accelerators

    SciTech Connect

    Esarey, E.; Leemans, W. P.; Schroeder, C. B.; Geddes, C. G. R.; Cormier-Michel, E.; Shadwick, B. A.

    2007-05-15

    Finite plasma temperature can modify the structure of the wake field, reduce the wave-breaking field, and lead to self-trapped electrons, which can degrade the electron bunch quality in a plasma-based accelerator. A relativistic warm fluid theory is used to describe the plasma temperature evolution and alterations to the structure of a nonlinear periodic wave exited in a warm plasma. The trapping threshold for a plasma electron and the fraction of electrons trapped from a thermal distribution are examined using a single-particle model. Numerical artifacts in particle-in-cell models that can mimic the physics associated with finite momentum spread are discussed.

  16. Pulsed Plasma Accelerator Modeling

    NASA Technical Reports Server (NTRS)

    Goodman, M.; Kazeminezhad, F.; Owens, T.

    2009-01-01

    This report presents the main results of the modeling task of the PPA project. The objective of this task is to make major progress towards developing a new computational tool with new capabilities for simulating cylindrically symmetric 2.5 dimensional (2.5 D) PPA's. This tool may be used for designing, optimizing, and understanding the operation of PPA s and other pulsed power devices. The foundation for this task is the 2-D, cylindrically symmetric, magnetohydrodynamic (MHD) code PCAPPS (Princeton Code for Advanced Plasma Propulsion Simulation). PCAPPS was originally developed by Sankaran (2001, 2005) to model Lithium Lorentz Force Accelerators (LLFA's), which are electrode based devices, and are typically operated in continuous magnetic field to the model, and implementing a first principles, self-consistent algorithm to couple the plasma and power circuit that drives the plasma dynamics.

  17. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1995-01-01

    The application of electric propulsion to communications satellites, however, has been limited to the use of hydrazine thrusters with electric heaters for thrust and specific impulse augmentation. These electrothermal thrusters operate at specific impulse levels of approximately 300 s with heater powers of about 500 W. Low power arcjets (1-3 kW) are currently being investigated as a way to increase specific impulse levels to approximately 500 s. Ion propulsion systems can easily produce specific impulses of 3000 s or greater, but have yet to be applied to communications satellites. The reasons most often given for not using ion propulsion systems are their high level of overall complexity, low thrust with long burn times, and the difficulty of integrating the propulsion system into existing commercial spacecraft busses. The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass.

  18. Identifying Kinetic Plasma Wave Modes Observed in the Acceleration Regions in the Low-Latitude Boundary Layer.

    NASA Astrophysics Data System (ADS)

    Moore, T.; Nykyri, K.; Dimmock, A. P.

    2015-12-01

    Understanding plasma heating and transport across fluid, ion and electron scales is currently not well understood in astrophysical plasmas. We have recently identified (by determining the observational dispersion relation using multi-point spacecraft measurements) an ion-scale, large amplitude fast mode wave observed inside a fluid-scale Kelvin-Helmholtz vortex. The Poyinting flux of the fast mode wave packet was sufficient to produce the observed ~5 keV energy increase of ions of magnetosheath origin. In this followup work, we analyze in detail the other intervals with similar characteristics, where the cold magnetosheath population becomes significantly energized. We identify the plasma wave modes present and discuss whether their energy budget is sufficient for the observed level of energization.

  19. Trapping and dark current in plasma-based accelerators

    SciTech Connect

    Schroder, C.B.; Esarey, E.; Shadwick, B.A.; Leemans, W.P.

    2004-06-01

    The trapping of thermal electrons in a nonlinear plasma wave of arbitrary phase velocity is investigated. The threshold plasma wave amplitude for trapping plasma electrons is calculated, thereby determining the fraction trapped and the expected dark current in a plasma-based accelerator. It is shown that the presence of a laser field (e.g., trapping in the self-modulated regime of the laser wakefield accelerator) increases the trapping threshold. Implications for experimental and numerical laser-plasma studies are discussed.

  20. Electron cyclotron harmonic wave acceleration

    NASA Technical Reports Server (NTRS)

    Karimabadi, H.; Menyuk, C. R.; Sprangle, P.; Vlahos, L.

    1987-01-01

    A nonlinear analysis of particle acceleration in a finite bandwidth, obliquely propagating electromagnetic cyclotron wave is presented. It has been suggested by Sprangle and Vlahos in 1983 that the narrow bandwidth cyclotron radiation emitted by the unstable electron distribution inside a flaring solar loop can accelerate electrons outside the loop by the interaction of a monochromatic wave propagating along the ambient magnetic field with the ambient electrons. It is shown here that electrons gyrating and streaming along a uniform, static magnetic field can be accelerated by interacting with the fundamental or second harmonic of a monochromatic, obliquely propagating cyclotron wave. It is also shown that the acceleration is virtually unchanged when a wave with finite bandwidth is considered. This acceleration mechanism can explain the observed high-energy electrons in type III bursts.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Ion acceleration from thin foil and extended plasma targets by slow electromagnetic wave and related ion-ion beam instability

    SciTech Connect

    Bulanov, S. V.; Esirkepov, T. Zh.; Kando, M.; Pegoraro, F.; Bulanov, S. S.; Geddes, C. G. R.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2012-10-15

    When ions are accelerated by the radiation pressure of a laser pulse, their velocity cannot exceed the pulse group velocity which can be considerably smaller than the speed of light in vacuum. This is demonstrated in two cases corresponding to a thin foil target irradiated by high intensity laser light and to the hole boring produced in an extended plasma by the laser pulse. It is found that the beams of accelerated ions are unstable against Buneman-like and Weibel-like instabilities which results in the broadening of the ion energy spectrum.

  3. Laser Plasma Particle Accelerators: Large Fields for Smaller Facility Sources

    SciTech Connect

    Geddes, Cameron G.R.; Cormier-Michel, Estelle; Esarey, Eric H.; Schroeder, Carl B.; Vay, Jean-Luc; Leemans, Wim P.; Bruhwiler, David L.; Cary, John R.; Cowan, Ben; Durant, Marc; Hamill, Paul; Messmer, Peter; Mullowney, Paul; Nieter, Chet; Paul, Kevin; Shasharina, Svetlana; Veitzer, Seth; Weber, Gunther; Rubel, Oliver; Ushizima, Daniela; Bethel, Wes; Wu, John

    2009-03-20

    Compared to conventional particle accelerators, plasmas can sustain accelerating fields that are thousands of times higher. To exploit this ability, massively parallel SciDAC particle simulations provide physical insight into the development of next-generation accelerators that use laser-driven plasma waves. These plasma-based accelerators offer a path to more compact, ultra-fast particle and radiation sources for probing the subatomic world, for studying new materials and new technologies, and for medical applications.

  4. Critical Issues in Plasma Accelerator

    NASA Astrophysics Data System (ADS)

    Uesaka, M.; Hosokai, T.

    2004-10-01

    Updated achievements and critical issues in plasma accelerators are summarized. As to laser plasma accelerators, we cover the results of plasma cathodes by U.Michigan, LBNL, LOA and U.Tokyo. Although many new results of accelerated electrons have been reported, the electrons do not yet form a bunch with narrow energy spread. Several injection schemes and measurements to verify ultrashort bunch (tens fs) with narrow energy spread, low emittance and many charges are planned. E-162 experiments by UCLA / USC / SLAC and a newly proposed experiment on density transition trapping are introduced for electron beam driven plasma accelerators. Their main purpose is realization of GeV plasma accelerator, but application to pump-and-probe analysis for investigation of ultrafast quantum phenomena is also promising.

  5. Compact plasma accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E. (Inventor)

    2004-01-01

    A compact plasma accelerator having components including a cathode electron source, an anodic ionizing gas source, and a magnetic field that is cusped. The components are held by an electrically insulating body having a central axis, a top axial end, and a bottom axial end. The cusped magnetic field is formed by a cylindrical magnet having an axis of rotation that is the same as the axis of rotation of the insulating body, and magnetized with opposite poles at its two axial ends; and an annular magnet coaxially surrounding the cylindrical magnet, magnetized with opposite poles at its two axial ends such that a top axial end has a magnetic polarity that is opposite to the magnetic polarity of a top axial end of the cylindrical magnet. The ionizing gas source is a tubular plenum that has been curved into a substantially annular shape, positioned above the top axial end of the annular magnet such that the plenum is centered in a ring-shaped cusp of the magnetic field generated by the magnets. The plenum has one or more capillary-like orifices spaced around its top such that an ionizing gas supplied through the plenum is sprayed through the one or more orifices. The plenum is electrically conductive and is positively charged relative to the cathode electron source such that the plenum functions as the anode; and the cathode is positioned above and radially outward relative to the plenum.

  6. Plasma Wakefield Acceleration of Positrons

    NASA Astrophysics Data System (ADS)

    Gessner, Spencer

    2016-03-01

    Recent particle beam and laser-driven plasma wakefield experiments have produced high-quality electron beams accelerated by a GeV or more in less than a meter. Efforts are underway to put these beams to work as sources for free-electron lasers. By contrast, little work has been done to demonstrate the tractability of plasma wakefield acceleration (PWFA) of positrons beams. The reasons for this are threefold: 1) positron beams are only useful for high-energy physics experiments, whereas electron beams are also useful as light sources, 2) there is a dearth of positron sources for PWFA experiments, and 3) the dynamics of accelerating positron beams in plasma is fundamentally different than that of electron beams. This talk will focus on the physics of accelerating positrons in plasma and contrast the dynamics of electron and positron beam-driven nonlinear plasma wakes. We describe recent experiments at the FACET test facility at SLAC National Accelerator Laboratory that for the first time demonstrate high-gradient acceleration of a positron beams in plasma. We also discuss an alternative acceleration technique called hollow channel acceleration that aims to symmetrize the dynamics of electron and positron beam-driven wakes.

  7. Sequentially pulsed traveling wave accelerator

    DOEpatents

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

    2009-08-18

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

  8. Acceleration of nonmonoenergetic electron bunches injected into a wake wave

    SciTech Connect

    Kuznetsov, S. V.

    2012-07-15

    The trapping and acceleration of nonmonoenergetic electron bunches in a wake field wave excited by a laser pulse in a plasma channel is studied. Electrons are injected into the region of the wake wave potential maximum at a velocity lower than the phase velocity of the wave. The paper analyzes the grouping of bunch electrons in the energy space emerging in the course of acceleration under certain conditions of their injection into the wake wave and minimizing the energy spread for such electrons. The factors determining the minimal energy spread between bunch electrons are analyzed. The possibility of monoenergetic acceleration of electron bunches generated by modern injectors in a wake wave is analyzed.

  9. Plasma channel guided laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Geddes, Cameron Guy Robinson

    2005-11-01

    High quality electron beams (several 109 electrons above 80 MeV energy with percent energy spread and low divergence) have been produced for the first time in a compact, high gradient, all-optical laser accelerator by extending the interaction distance using a pre-formed plasma density channel to guide the drive laser pulse. Laser-driven accelerators, in which particles are accelerated by the electric field of a plasma wave (wake) driven by the radiation pressure of an intense laser, have over the past decade demonstrated accelerating fields thousands of times greater than those achievable in conventional radio-frequency accelerators. This has spurred interest in them as compact next-generation sources of energetic electrons and radiation. To date, however, acceleration distances have been severely limited by the lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance resulted in low-energy beams with 100 percent electron energy spread, which has limited potential applications. Optical guiding of relativistically intense (>1018 W/cm 2) laser pulses over distances greater than 10 diffraction lengths is demonstrated herein using plasma channels, which have a density minimum on the axis of propagation, formed by hydrodynamic shock. Laser modes with peak powers of up to 4 TW---twice the self-guiding threshold---were guided without aberration by tuning the plasma density profile. The transmitted optical spectrum showed that the pulse remained in the channel over the entire length, and no accelerated electrons were observed at these powers. Simulations indicated that a large plasma wave was driven by the 4 TW pulse, indicating a possible dark current free structure for a laser wakefield accelerator using controlled injection. The presence of a large plasma wave was verified by increasing laser power and observing electron acceleration. At a guided drive pulse power of 9 TW (500 mJ in 50 fs

  10. Dusty-Plasma Particle Accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2005-01-01

    A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the

  11. New wave effects in nonstationary plasma

    NASA Astrophysics Data System (ADS)

    Schmit, Paul

    2012-10-01

    In plasma undergoing compression, embedded waves can have very unusual and possibly useful properties. For example, part of the mechanical energy of compressing plasma can be transferred controllably to hot electrons by seeding the plasma with plasma waves. Under compression, wherein wave action is conserved, the wave energy grows as its frequency and wavenumber change adiabatically, until, suddenly, the wave damps, resulting in switch-like production not only of heat [1], but also voltage and current [2]. These bursts can be controlled precisely in time by prescribing the compression script. Several classic problems in wave physics, including the bump-on-tail instability, exhibit new effects under compression [3]. In addition, the waves undergoing compression or expansion affect fundamental properties of plasma, such as the plasma compressibility; moreover, and rather remarkably, nonlinear waves, such as BGK modes, affect the plasma compressibility differently [4]. Wave-particle interactions mediated by plasma compression also can enhance the performance of plasma-based particle accelerators. To describe numerically all these effects, novel particle-in-cell simulations were developed. These findings point towards potentially beneficial applications, including in inertial confinement fusion and high energy density plasma physics, where extreme compression is exercised on dense plasma, which could be seeded with waves. [4pt] [1] P. F. Schmit, I. Y. Dodin, and N. J. Fisch, PRL 105, 175003 (2010).[0pt] [2] P. F. Schmit and N. J. Fisch, PRL 108, 215003 (2012).[0pt] [3] P. F. Schmit et al., J. Plasma Phys. 77, 629 (2011).[0pt] [4] P. F. Schmit, I. Y. Dodin, and N. J. Fisch, Phys. Plasmas 18, 042103 (2011).[0pt] [5] P. F. Schmit and N. J. Fisch, Phys. Plasmas 18, 102102 (2011).

  12. Undamped electrostatic plasma waves

    SciTech Connect

    Valentini, F.; Perrone, D.; Veltri, P.; Califano, F.; Pegoraro, F.; Morrison, P. J.; O'Neil, T. M.

    2012-09-15

    Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named corner modes. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the (k,{omega}{sub R}) plane ({omega}{sub R} being the real part of the wave frequency and k the wavenumber), away from the well-known 'thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existence of these modes are described. It is also shown that deviations caused by fattening the tail of the distribution shift roots off of the thumb curve toward lower k-values and chopping the tail shifts them toward higher k-values. In addition, a rule of thumb is obtained for assessing how the existence of a plateau shifts roots off of the thumb curve. Suggestions are made for interpreting experimental observations of electrostatic waves, such as recent ones in nonneutral plasmas.

  13. Physics of laser-driven plasma-based electron accelerators

    SciTech Connect

    Esarey, E.; Schroeder, C. B.; Leemans, W. P.

    2009-07-15

    Laser-driven plasma-based accelerators, which are capable of supporting fields in excess of 100 GV/m, are reviewed. This includes the laser wakefield accelerator, the plasma beat wave accelerator, the self-modulated laser wakefield accelerator, plasma waves driven by multiple laser pulses, and highly nonlinear regimes. The properties of linear and nonlinear plasma waves are discussed, as well as electron acceleration in plasma waves. Methods for injecting and trapping plasma electrons in plasma waves are also discussed. Limits to the electron energy gain are summarized, including laser pulse diffraction, electron dephasing, laser pulse energy depletion, and beam loading limitations. The basic physics of laser pulse evolution in underdense plasmas is also reviewed. This includes the propagation, self-focusing, and guiding of laser pulses in uniform plasmas and with preformed density channels. Instabilities relevant to intense short-pulse laser-plasma interactions, such as Raman, self-modulation, and hose instabilities, are discussed. Experiments demonstrating key physics, such as the production of high-quality electron bunches at energies of 0.1-1 GeV, are summarized.

  14. Pulsed Electromagnetic Acceleration of Plasmas

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Cassibry, Jason T.; Markusic, Tom E.; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    A major shift in paradigm in driving pulsed plasma thruster is necessary if the original goal of accelerating a plasma sheet efficiently to high velocities as a plasma "slug" is to be realized. Firstly, the plasma interior needs to be highly collisional so that it can be dammed by the plasma edge layer not (upstream) adjacent to the driving 'vacuum' magnetic field. Secondly, the plasma edge layer needs to be strongly magnetized so that its Hall parameter is of the order of unity in this region to ensure excellent coupling of the Lorentz force to the plasma. Thirdly, to prevent and/or suppress the occurrence of secondary arcs or restrike behind the plasma, the region behind the plasma needs to be collisionless and extremely magnetized with sufficiently large Hall parameter. This places a vacuum requirement on the bore conditions prior to the shot. These requirements are quantified in the paper and lead to the introduction of three new design parameters corresponding to these three plasma requirements. The first parameter, labeled in the paper as gamma (sub 1), pertains to the permissible ratio of the diffusive excursion of the plasma during the course of the acceleration to the plasma longitudinal dimension. The second parameter is the required Hall parameter of the edge plasma region, and the third parameter the required Hall parameter of the region behind the plasma. Experimental research is required to quantify the values of these design parameters. Based upon fundamental theory of the transport processes in plasma, some theoretical guidance on the choice of these parameters are provided to help designing the necessary experiments to acquire these data.

  15. Three dimensional particle-in-cell simulation of particle acceleration by circularly polarised inertial Alfven waves in a transversely inhomogeneous plasma

    SciTech Connect

    Tsiklauri, D.

    2012-08-15

    The process of particle acceleration by left-hand, circularly polarised inertial Alfven waves (IAW) in a transversely inhomogeneous plasma is studied using 3D particle-in-cell simulation. A cylindrical tube with, transverse to the background magnetic field, inhomogeneity scale of the order of ion inertial length is considered on which IAWs with frequency 0.3{omega}{sub ci} are launched that are allowed to develop three wavelength. As a result time-varying parallel electric fields are generated in the density gradient regions which accelerate electrons in the parallel to magnetic field direction. Driven perpendicular electric field of IAWs also heats ions in the transverse direction. Such numerical setup is relevant for solar flaring loops and earth auroral zone. This first, 3D, fully kinetic simulation demonstrates electron acceleration efficiency in the density inhomogeneity regions, along the magnetic field, of the order of 45% and ion heating, in the transverse to the magnetic field direction, of 75%. The latter is a factor of two times higher than the previous 2.5D analogous study and is in accordance with solar flare particle acceleration observations. We find that the generated parallel electric field is localised in the density inhomogeneity region and rotates in the same direction and with the same angular frequency as the initially launched IAW. Our numerical simulations seem also to suggest that the 'knee' often found in the solar flare electron spectra can alternatively be interpreted as the Landau damping (Cerenkov resonance effect) of IAWs due to the wave-particle interactions.

  16. Chaotic ion motion in magnetosonic plasma waves

    NASA Technical Reports Server (NTRS)

    Varvoglis, H.

    1984-01-01

    The motion of test ions in a magnetosonic plasma wave is considered, and the 'stochasticity threshold' of the wave's amplitude for the onset of chaotic motion is estimated. It is shown that for wave amplitudes above the stochasticity threshold, the evolution of an ion distribution can be described by a diffusion equation with a diffusion coefficient D approximately equal to 1/v. Possible applications of this process to ion acceleration in flares and ion beam thermalization are discussed.

  17. Investigations of the plasma and structure based accelerators

    SciTech Connect

    Shvets, Gennady

    2012-08-30

    The objective of our research during the reported period was three-fold: (a) theoretical investigation of novel mechanisms of injection into laser wake field accelerators; (b) theoretical investigation of single-shot frequency domain diagnostics of relativistic plasma wakes, specifically in the context of spatio-temporal evolution of the plasma bubble;(c) experimental and theoretical investigation of laser-driven accelerating structure, specifically in the context of the Surface Wave Accelerator Based on SiC (SWABSIC).

  18. Wave Detection in Acceleration Plethysmogram

    PubMed Central

    2015-01-01

    Objectives Acceleration plethysmogram (APG) obtained from the second derivative of photoplethysmography (PPG) is used to predict risk factors for atherosclerosis with age. This technique is promising for early screening of atherosclerotic pathologies. However, extraction of the wave indices of APG signals measured from the fingertip is challenging. In this paper, the development of a wave detection algorithm including a preamplifier based on a microcontroller that can detect the a, b, c, and d wave indices is proposed. Methods The 4th order derivative of a PPG under real measurements of an APG waveform was introduced to clearly separate the components of the waveform, and to improve the rate of successful wave detection. A preamplifier with a Sallen-Key low pass filter and a wave detection algorithm with programmable gain control, mathematical differentials, and a digital IIR notch filter were designed. Results The frequency response of the digital IIR filter was evaluated, and a pulse train consisting of a specific area in which the wave indices existed was generated. The programmable gain control maintained a constant APG amplitude at the output for varying PPG amplitudes. For 164 subjects, the mean values and standard deviation of the a wave index corresponding to the magnitude of the APG signal were 1,106.45 and ±47.75, respectively. Conclusions We conclude that the proposed algorithm and preamplifier designed to extract the wave indices of an APG in real-time are useful for evaluating vascular aging in the cardiovascular system in a simple healthcare device. PMID:25995963

  19. Laser acceleration in vacuum, gases, and plasmas withcapillary waveguide

    SciTech Connect

    Xie, Ming

    1998-07-01

    I propose a new method for laser acceleration of relativistic electrons using the leaky modes of a hollow dielectric waveguide. The hollow core of the waveguide can be either in vacuum or filled with uniform gases or plasmas. In case of vacuum and gases, TM01 mode is used for direct acceleration. In case of plasmas, EH11 mode is used to drive longitudinal plasma wave for acceleration. Structure damage due to high power laser can be avoided by choosing a core radius sufficiently larger than laser wavelength. Effect of nonuniform plasma density on waveguide performance is also analyzed.

  20. Plasma laser accelerator: longitudinal dynamics, the plasma/laser interaction, and a qualitative design

    SciTech Connect

    Ruth, R.D.; Chao, A.W.

    1982-04-01

    In this paper we present our studies on a plasma laser accelerator. First we look at the longitudinal dynamics and the trapping of particles in the potential well due to the longitudinal electric field in a plasma density wave. Next we study the plasma/laser interaction to obtain power requirements. Lastly, we qualitatively design a plasma/laser accelerator with parameters somewhat more modest than existing suggestions.

  1. Theoretical Investigations of Plasma-Based Accelerators and Other Advanced Accelerator Concepts

    SciTech Connect

    Shuets, G.

    2004-05-21

    Theoretical investigations of plasma-based accelerators and other advanced accelerator concepts. The focus of the work was on the development of plasma based and structure based accelerating concepts, including laser-plasma, plasma channel, and microwave driven plasma accelerators.

  2. Energy Measurement in a Plasma Wakefield Accelerator

    SciTech Connect

    Ischebeck, R

    2007-07-06

    In the E-167 plasma wakefield acceleration experiment, electrons with an initial energy of 42GeV are accelerated in a meter-scale lithium plasma. Particles are leaving plasma with a large energy spread. To determine the spectrum of the accelerated particles, a two-plane spectrometer has been set up.

  3. Current driven instabilities of an electromagnetically accelerated plasma

    NASA Technical Reports Server (NTRS)

    Chouetri, E. Y.; Kelly, A. J.; Jahn, R. G.

    1988-01-01

    A plasma instability that strongly influences the efficiency and lifetime of electromagnetic plasma accelerators was quantitatively measured. Experimental measurements of dispersion relations (wave phase velocities), spatial growth rates, and stability boundaries are reported. The measured critical wave parameters are in excellent agreement with theoretical instability boundary predictions. The instability is current driven and affects a wide spectrum of longitudinal (electrostatic) oscillations. Current driven instabilities, which are intrinsic to the high-current-carrying magnetized plasma of the magnetoplasmadynmic (MPD) accelerator, were investigated with a kinetic theoretical model based on first principles. Analytical limits of the appropriate dispersion relation yield unstable ion acoustic waves for T(i)/T(e) much less than 1 and electron acoustic waves for T(i)/T(e) much greater than 1. The resulting set of nonlinear equations for the case of T(i)/T(e) = 1, of most interest to the MPD thruster Plasma Wave Experiment, was numerically solved to yield a multiparameter set of stability boundaries. Under certain conditions, marginally stable waves traveling almost perpendicular to the magnetic field would travel at a velocity equal to that of the electron current. Such waves were termed current waves. Unstable current waves near the upper stability boundary were observed experimentally and are in accordance with theoretical predictions. This provides unambiguous proof of the existence of such instabilites in electromagnetic plasma accelerators.

  4. Resonances and surface waves in bounded plasmas

    SciTech Connect

    Bowers, K.J.; Qui, D.W.; Smith, H.B.; Birdsall, C.K.

    1999-07-01

    Surface waves provide a promising means of creating large, area plasmas. These waves can uniformly distribute the excitation energy and while presenting a small resistance and zero reactance to the driving source. Experimentally and in the simulations, the electron temperature is low (like 1--3 eV) as is the plasma potential (like 10 Te). The use of surface waves experimentally, and now industrially, to sustain large area plasma sources with device size is comparable to free space wavelength have motivated the authors to refine the theories of [1] and [2] to be fully electromagnetic. The wave dispersion predicted by the electromagnetic theory differs from the predictions of the prior theories and the results illuminate limitations of the electrostatic model. The use of surface waves have also motivated them to explore the mechanisms by which surface waves heat the plasma. In the 1d electrostatic simulations high velocity electron bunches are formed in the sheaths and are alternatively accelerated from each sheath into the bulk plasma each RF cycle. They speculate similar mechanisms provide the ionization in surface wave discharges. They also see in these simulations the plasma makes an abrupt transition from capacitively coupled to resistively coupled and the series resonance locks onto the drive frequency; these abrupt transitions resemble mode-jumping seen experimentally in large area sources. Furthermore, the density profile of the plasma tracks the drive frequency while in the resonant mode giving a new mechanism by which the plasma parameters can be controlled. They are currently investigating the effect of the driving electrode shape has on these resonances and conducting 2d simulations of a large area surface wave source to explore the ignition of surface wave devices and how the plasma fills in the device.

  5. Warm wavebreaking of nonlinear plasma waves with arbitrary phasevelocities

    SciTech Connect

    Schroeder, C.B.; Esarey, E.; Shadwick, B.A.

    2004-11-12

    A warm, relativistic fluid theory of a nonequilibrium, collisionless plasma is developed to analyze nonlinear plasma waves excited by intense drive beams. The maximum amplitude and wavelength are calculated for nonrelativistic plasma temperatures and arbitrary plasma wave phase velocities. The maximum amplitude is shown to increase in the presence of a laser field. These results set a limit to the achievable gradient in plasma-based accelerators.

  6. Quasi-steady plasma acceleration.

    NASA Technical Reports Server (NTRS)

    Jahn, R. G.; Von Jaskowsky, W. F.; Clark, K. E.

    1973-01-01

    A coaxial plasma accelerator driven by protracted pulses of current in the range of 10,000 to 100,000 A and synchronized mass flows from 1.0 to 36 g/sec argon attains, after some tens of microseconds, a stable magnetoplasmadynamic acceleration mode. This 'quasi-steady' discharge form is characterized by constant terminal voltage and current, a diffuse, fixed current distribution within the discharge, and a steady plasma efflux at velocities of approximately 20 km/sec. Measured potential distributions reveal that the bulk of the arc voltage gradient, exclusive of the electrode falls, occurs within two diameters of the cathode, and is normal to it. The anode fall voltage varies inversely with local current density, implying substantially lower anode losses at higher power arc operation. Spectroscopic, potential, and velocity measurements indicate the existence of a characteristic mass flow rate for a given current, below which arc operation becomes erratic.

  7. Nondiffracting accelerating wave packets of Maxwell's equations.

    PubMed

    Kaminer, Ido; Bekenstein, Rivka; Nemirovsky, Jonathan; Segev, Mordechai

    2012-04-20

    We present the nondiffracting spatially accelerating solutions of the Maxwell equations. Such beams accelerate in a circular trajectory, thus generalizing the concept of Airy beams to the full domain of the wave equation. For both TE and TM polarizations, the beams exhibit shape-preserving bending which can have subwavelength features, and the Poynting vector of the main lobe displays a turn of more than 90°. We show that these accelerating beams are self-healing, analyze their properties, and find the new class of accelerating breathers: self-bending beams of periodically oscillating shapes. Finally, we emphasize that in their scalar form, these beams are the exact solutions for nondispersive accelerating wave packets of the most common wave equation describing time-harmonic waves. As such, this work has profound implications to many linear wave systems in nature, ranging from acoustic and elastic waves to surface waves in fluids and membranes. PMID:22680719

  8. Design of a plasma discharge circuit for particle wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Anania, M. P.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Ferrario, M.; Flora, F.; Gallerano, G. P.; Ghigo, A.; Marocchino, A.; Massimo, F.; Mostacci, A.; Mezi, L.; Musumeci, P.; Serio, M.

    2014-03-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV m-1), enabling acceleration of electrons to GeV energy in few centimetres. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators; radiofrequency-based accelerators, in fact, are limited in the accelerating field (10-100 MV m-1) requiring therefore kilometric distances to reach the GeV energies, but can provide very bright electron bunches. Combining high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC-LAB [1,2]. In particular, here we focus on the ionization process; we show a simplified model to study the evolution of plasma induced by discharge, very useful to design the discharge circuit able to fully ionize the gas and bring the plasma at the needed temperature and density.

  9. Laser-and Beam-Driven Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Joshi, Chandrashekhar

    2006-10-01

    Scientists have been trying to use the tremendous electric fields in relativistic plasma waves to accelerate charged particles, and are now making substantial progress. If they succeed, future high energy accelerators will use plasma waves rather than microwave cavities as accelerating structures.Some accelerators, such as those used for radiation therapy will fit on a tabletop. Research on using plasma waves to accelerate particles began in earnest following the suggestion by John Dawson and his colleagues [1-3] that a relativistically propagating plasma wave or a wake field could be excited by using a powerful but short laser -or electron -beam as a driver pulse.Since their original suggestion the research on plasma --based accelerators has spread worldwide A series of experiments by the UCLA/USC/SLAC collaboration ,using the 30 GeV beam of the Stanford Linear Accelerator Center (SLAC), has demonstrated high-gradient acceleration of electrons and positrons using the the wake left by the SLAC beam as it passes through a lithium plasma. Electrons have been accelerated by more than 30 GeV in less than one meter. This acceleration gradient is about a thousand times larger than in conventional microwave-driven accelerators. It is a first step toward a ``plasma afterburner,'' which would be placed at the end of a kilometers-long conventional accelerator and double its beam energy in a few tens of meters. In addition to the acceleration of particle beams, these experiments have demonstrated the rich physics bounty to be reaped from relativistic beam-plasma interactions. This includes the generation of intense and narrowly collimated x-ray beams, refraction of particles at a plasma interface, and the creation of intense beams of positrons. These results are leading the way to similar tabletop accelerators based on plasma wakes excited by lasers rather than electron beams. Applications for tabletop accelerators include gamma radiography, radiation therapy, and ultra

  10. Efficient accelerator afterburner design based on plasma wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Huang, Chengkun; Blumenfeld, I.; Clayton, C. E.; Decker, F.-J.; Hogan, M. J.; Iverson, R.; Joshi, C.; Katsouleas, T.; Kirby, N.; Lu, W.; Marsh, K. A.; Mori, W. B.; Muggli, P.; Siemann, R.; Walz, D.; Ischebeck, R.; Tzoufras, M.

    2008-11-01

    Recent plasma wakefield acceleration (PWFA) experiment using short (˜100fs), high peak current (>10KA) electron beam as wakefield driver has demonstrated sustained acceleration gradient of ˜50GeV/m over 85 cm. The rapid progress of PWFA experiments has attracted interests regarding the possibility of making an ``afterburner'' for a linear collider. In the ``afterburner'' concept, electron acceleration is achieved by placing a trailing electron beam into the wakefield (either by beam splitting or external injection) to extract energy deposited in the plasma wave wake. Several important aspects of the ``afterburner'' design in the blow-out regime, such as wakefield generation, efficient beam loading and hosing instability have been investigated theoretically. These relevant physics will have great impact on the beam quality of a possible ``afterburner'' design. A multi-stage ``afterburner'' design with 25GeV energy gain in each stage is explored numerically with a 3D quasi-static code QuickPIC. Parameters are suggested for a 0.5 TeV PWFA afterburner with this design and simulation result will be presented.

  11. Acceleration of electron bunches injected into a wake wave

    SciTech Connect

    Kuznetsov, S. V.

    2012-02-15

    The process of trapping and acceleration of nonmonoenergetic electron bunches by a wake wave excited by a laser pulse in a plasma channel is investigated. The electrons are injected into the vicinity of the maximum of the wakefield potential with a velocity lower than the wave phase velocity. The study is aimed at utilizing specific features of a wakefield with substantially overlapped focusing and accelerating phases for achieving monoenergetic electron acceleration. Conditions are found under which electrons in a finite-length nonmonoenergetic bunch are accelerated to high energies, while the energy spread between them is minimal. The effect of energy grouping of electrons makes it possible to obtain compact high-energy electron bunches with a small energy spread during laser plasma acceleration.

  12. Capillary waveguide for laser acceleration in vacuum, gases and plasmas

    SciTech Connect

    Xie, Ming

    1998-06-01

    The authors propose a new method for laser acceleration of relativistic electrons using the leaky modes of a hollow dielectric waveguide. The hollow core of the waveguide can be either in vacuum or filled with uniform gases or plasmas. In of vacuum and gases, TM{sub 01} mode is used for direct acceleration. In case of plasmas, EH{sub 11} mode is used to drive longitudinal plasma wave for acceleration. Structure damage by high power laser is avoided by choosing a core radius much larger than laser wavelength.

  13. Plasma waves near the magnetopause

    NASA Technical Reports Server (NTRS)

    Anderson, R. R.; Eastman, T. E.; Harvey, C. C.; Hoppe, M. M.; Tsurutani, B. T.; Etcheto, J.

    1982-01-01

    Plasma waves associated with the magnetosphere from the magnetosheath to the outer magnetosphere are investigated to obtain a clear definition of the boundaries and regions, to characterize the waves observed in these regions, to determine which wave modes are present, and to determine their origin. Emphasis is on high time resolution data and a comparison between measurements by different antenna systems. It is shown that the magnetosheath flux transfer events, the magnetopause current layer, the outer magnetosphere, and the boundary layer can be identified by their magnetic field and plasma wave characteristics, as well as by their plasma and energetic particle signatures. The plasma wave characteristics in the current layer and in the boundary layer are very similar to the features in the flux transfer events, and upon entry into their outer magnetosphere, the plasma wave spectra are dominated by intense electromagnetic chorus bursts and electrostatic emissions.

  14. Probing electron acceleration and x-ray emission in laser-plasma accelerators

    SciTech Connect

    Thaury, C.; Ta Phuoc, K.; Corde, S.; Brijesh, P.; Lambert, G.; Malka, V.; Mangles, S. P. D.; Bloom, M. S.; Kneip, S.

    2013-06-15

    While laser-plasma accelerators have demonstrated a strong potential in the acceleration of electrons up to giga-electronvolt energies, few experimental tools for studying the acceleration physics have been developed. In this paper, we demonstrate a method for probing the acceleration process. A second laser beam, propagating perpendicular to the main beam, is focused on the gas jet few nanosecond before the main beam creates the accelerating plasma wave. This second beam is intense enough to ionize the gas and form a density depletion, which will locally inhibit the acceleration. The position of the density depletion is scanned along the interaction length to probe the electron injection and acceleration, and the betatron X-ray emission. To illustrate the potential of the method, the variation of the injection position with the plasma density is studied.

  15. Probing electron acceleration and x-ray emission in laser-plasma accelerators

    NASA Astrophysics Data System (ADS)

    Thaury, C.; Ta Phuoc, K.; Corde, S.; Brijesh, P.; Lambert, G.; Mangles, S. P. D.; Bloom, M. S.; Kneip, S.; Malka, V.

    2013-06-01

    While laser-plasma accelerators have demonstrated a strong potential in the acceleration of electrons up to giga-electronvolt energies, few experimental tools for studying the acceleration physics have been developed. In this paper, we demonstrate a method for probing the acceleration process. A second laser beam, propagating perpendicular to the main beam, is focused on the gas jet few nanosecond before the main beam creates the accelerating plasma wave. This second beam is intense enough to ionize the gas and form a density depletion, which will locally inhibit the acceleration. The position of the density depletion is scanned along the interaction length to probe the electron injection and acceleration, and the betatron X-ray emission. To illustrate the potential of the method, the variation of the injection position with the plasma density is studied.

  16. Consequences of wave-particle interactions on chaotic acceleration

    NASA Technical Reports Server (NTRS)

    Schriver, David; Ashour-Abdalla, Maha

    1991-01-01

    The recent model of Ashour-Abdalla et al. (1991) has proposed that the earth's plasma sheet can be formed by chaotic acceleration in a magnetotail-like field configuration. The ion velocity distributions created by chaotic acceleration have unstable features and represent robust free energy sources for kinetic plasma waves that can modify the original distributions. In the plasma sheet boundary layer, field-aligned ion beamlets are formed which drive a host of instabilities creating a broadbanded noise spectrum and cause thermal spreading of the beamlets. In addition, there is strong heating of any cold background plasma that may be present. In the central plasma sheet, ion antiloss cone distributions are created which are unstable to very low frequency waves that saturate by filling the antiloss cone.

  17. Charged particle acceleration in nonuniform plasmas

    SciTech Connect

    Bulanov, S.V.; Naumova, N.M.; Dudnikova, G.I.; Vshivkov, V.A.; Pegoraro, F.; Pogorelsky, I.V.

    1996-11-01

    The high-gradient electron acceleration schemes that have been demonstrated using LWFA appear promising for the development of plasma-based laser accelerators into practical devices. However, a question still exists: how to avoid the wake field deterioration and the loss of the phase synchronism between the plasma wave and the electrons that prevent them from being accelerated up to the theoretical limit. In order to obtain the highest possible values of the wake electric field one must use as intense laser pulses as possible i.e., pulses with dimensionless amplitudes a {much_gt} 1. Pulses that have a dimensionless amplitude larger than one tend to be subject to a host of instabilities, such as relativistic self-focusing, self modulation and stimulated Raman scattering, that affect their propagation in the plasma. Such processes could be beneficial, in so far as they increase the pulse energy density, enhance the wake field generation, and provide the mechanism for transporting the laser radiation over several Rayleigh lengths without diffraction spreading. However, it is still far from certain that these processes can be exploited in a controlled form and can lead to regular, stationary wake fields. It is known that, in order to create good quality wake fields, it would be preferable to use laser pulses with steep fronts of order {lambda}{sub p}. The present paper aims at analyzing the influence of the laser pulse shape and of the plasma nonuniformity on the charged particle acceleration. This study is based on the results obtained with one dimensional PIC simulations.

  18. Warm wave breaking of nonlinear plasma waves with arbitrary phase velocities

    SciTech Connect

    Schroeder, C.B.; Esarey, E.; Shadwick, B.A.

    2005-11-01

    A warm, relativistic fluid theory of a nonequilibrium, collisionless plasma is developed to analyze nonlinear plasma waves excited by intense drive beams. The maximum amplitude and wavelength are calculated for nonrelativistic plasma temperatures and arbitrary plasma wave phase velocities. The maximum amplitude is shown to increase in the presence of a laser field. These results set a limit to the achievable gradient in plasma-based accelerators.

  19. Warm wave breaking of nonlinear plasma waves with arbitrary phase velocities.

    PubMed

    Schroeder, C B; Esarey, E; Shadwick, B A

    2005-11-01

    A warm, relativistic fluid theory of a nonequilibrium, collisionless plasma is developed to analyze nonlinear plasma waves excited by intense drive beams. The maximum amplitude and wavelength are calculated for nonrelativistic plasma temperatures and arbitrary plasma wave phase velocities. The maximum amplitude is shown to increase in the presence of a laser field. These results set a limit to the achievable gradient in plasma-based accelerators. PMID:16383678

  20. Tunable Laser Plasma Accelerator based on Longitudinal Density Tailoring

    SciTech Connect

    Gonsalves, Anthony; Nakamura, Kei; Lin, Chen; Panasenko, Dmitriy; Shiraishi, Satomi; Sokollik, Thomas; Benedetti, Carlo; Schroeder, Carl; Geddes, Cameron; Tilborg, Jeroen van; Osterhoff, Jens; Esarey, Eric; Toth, Csaba; Leemans, Wim

    2011-07-15

    Laser plasma accelerators have produced high-quality electron beams with GeV energies from cm-scale devices and are being investigated as hyperspectral fs light sources producing THz to {gamma}-ray radiation and as drivers for future high-energy colliders. These applications require a high degree of stability, beam quality and tunability. Here we report on a technique to inject electrons into the accelerating field of a laser-driven plasma wave and coupling of this injector to a lower-density, separately tunable plasma for further acceleration. The technique relies on a single laser pulse powering a plasma structure with a tailored longitudinal density profile, to produce beams that can be tuned in the range of 100-400 MeV with percent-level stability, using laser pulses of less than 40 TW. The resulting device is a simple stand-alone accelerator or the front end for a multistage higher-energy accelerator.

  1. Drift waves in rotating plasmas

    SciTech Connect

    Horton, W.; Liu, J.

    1983-09-01

    The stability of the electron drift wave is investigated in the presence of E x B plasma rotation typical of the central cell plasma in tandem mirrors. It is shown that a rotationally-driven drift wave may occur at low azimuthal mode numbers. Conditions for rotational instabilities are derived. Quasilinear formulas are given for the anomalous transport associated with the unstable fluctuations.

  2. Increasing energy coupling into plasma waves by tailoring the laser radial focal spot distribution in a laser wakefield accelerator

    SciTech Connect

    Genoud, G.; Burza, M.; Persson, A.; Svensson, K.; Wahlström, C.-G.; Bloom, M. S.; Najmudin, Z.; Mangles, S. P. D.; Vieira, J.; Silva, L. O.

    2013-06-15

    By controlling the focal spot quality with a deformable mirror, we are able to show that increasing the fraction of pulse energy contained within the central part of the focal spot, while keeping the total energy and central spot size constant, significantly increases the amount of energy transferred to the wakefield: Our measurements show that the laser loses significantly more laser energy and undergoes greater redshifting and that more charge is produced in the accelerated beam. Three dimensional particle in cell simulations performed with accurate representations of the measured focal spot intensity distribution confirm that energy in the wings of the focal spot is effectively wasted. Even though self-focusing occurs, energy in the wings of the focal spot distribution is not coupled into the wakefield, emphasising the vital importance of high quality focal spot profiles in experiments.

  3. Particle Acceleration in Superluminal Strong Waves

    NASA Astrophysics Data System (ADS)

    Teraki, Yuto; Ito, Hirotaka; Nagataki, Shigehiro

    2015-06-01

    We calculate the electron acceleration in random superluminal strong waves (SLSWs) and radiation from them using numerical methods in the context of the termination shocks of pulsar wind nebulae. We pursue the orbit of electrons by solving the equation of motion in the analytically expressed electromagnetic turbulences. These consist of a primary SLS and isotropically distributed secondary electromagnetic waves. Under the dominance of the secondary waves, all electrons gain nearly equal energy. On the other hand, when the primary wave is dominant, selective acceleration occurs. The phase of the primary wave for electrons moving nearly along the wavevector changes very slowly compared with the oscillation of the wave, which is “phase-locked,” and such electrons are continuously accelerated. This acceleration by SLSWs may play a crucial role in pre-shock acceleration. In general, the radiation from the phase-locked population is different from the synchro-Compton radiation. However, when the amplitude of the secondary waves is not extremely weaker than that of the primary wave, the typical frequency can be estimated from synchro-Compton theory using the secondary waves. The primary wave does not contribute to the radiation because the SLSW accelerates electrons almost linearly. This radiation can be observed as a radio knot at the upstream of the termination shocks of the pulsar wind nebulae without counterparts in higher frequency ranges.

  4. Design Considerations for Plasma Accelerators Driven by Lasers or Particle Beams

    SciTech Connect

    Schroeder, C. B.; Esarey, E.; Benedetti, C.; Toth, Cs.; Geddes, C. G. R.; Leemans, W. P.

    2010-11-04

    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. Design Considerations for Plasma Accelerators Driven by Lasers or Particle Beams

    SciTech Connect

    Schroeder, C. B.; Esarey, E.; Benedetti, C.; Toth, Cs.; Geddes, C. G. R.; Leemans, W.P.

    2010-06-01

    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.

  6. Waves in non-Maxwellian plasmas with excess superthermal particles

    NASA Astrophysics Data System (ADS)

    Hellberg, M. A.; Mace, R. L.; Verheest, F.

    2000-10-01

    Many space plasmas have an excess of superthermal particles and can be modelled by a κ-distribution. While κ-->∞ yields the Maxwellian, a low value of κ describes a power-law distribution with a strongly accelerated, hard spectrum. Wave studies require the generalized plasma dispersion function, which may be expressed in terms of a hypergeometric function, making it easily usable. We review studies of waves in κ-distribution plasmas, focusing inter alia on applications to space plasmas. Wave behavior for low-κ plasmas is significantly different from that found for Maxwellian plasmas. .

  7. Preliminary tests of the electrostatic plasma accelerator

    NASA Technical Reports Server (NTRS)

    Aston, G.; Acker, T.

    1990-01-01

    This report describes the results of a program to verify an electrostatic plasma acceleration concept and to identify those parameters most important in optimizing an Electrostatic Plasma Accelerator (EPA) thruster based upon this thrust mechanism. Preliminary performance measurements of thrust, specific impulse and efficiency were obtained using a unique plasma exhaust momentum probe. Reliable EPA thruster operation was achieved using one power supply.

  8. Nonlinear slow magnetoacoustic waves in coronal plasma structures

    NASA Astrophysics Data System (ADS)

    Afanasyev, A. N.; Nakariakov, V. M.

    2015-01-01

    Context. There is abundant observational evidence of longitudinal waves in the plasma structures of the solar corona. These essentially compressive waves are confidently interpreted as slow magnetoacoustic waves. The use of the slow waves in plasma diagnostics and estimating their possible contribution to plasma heating and acceleration require detailed theoretical modelling. Aims: We investigate the role of obliqueness and magnetic effects in the evolution of slow magnetoacoustic waves, also called tube waves, in field-aligned plasma structures. Special attention is paid to the wave damping caused by nonlinear steepening. Methods: We considered an untwisted straight axisymmetric field-aligned plasma cylinder and analysed the behaviour of the slow magnetoacoustic waves that are guided by this plasma structure. We adopted a thin flux tube approximation. We took into account dissipation caused by viscosity, resistivity and thermal conduction, and nonlinearity. Effects of stratification and dispersion caused by the finite radius of the flux tube were neglected. Results: We derive the Burgers-type evolutionary equation for tube waves in a uniform plasma cylinder. Compared with a plane acoustic wave, the formation of shock fronts in tube waves is found to occur at a larger distance from the source. In addition, tube waves experience stronger damping. These effects are most pronounced in plasmas with the parameter β at about or greater than unity. In a low-β plasma, the evolution of tube waves can satisfactorily be described with the Burgers equation for plane acoustic waves. Conclusions:

  9. Progress of Laser-Driven Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuhisa

    2007-07-01

    There is a great interest worldwide in plasma accelerators driven by ultra-intense lasers which make it possible to generate ultra-high gradient acceleration and high quality particle beams in a much more compact size compared with conventional accelerators. A frontier research on laser and plasma accelerators is focused on high energy electron acceleration and ultra-short X-ray and Tera Hertz radiations as their applications. These achievements will provide not only a wide range of sciences with benefits of a table-top accelerator but also a basic science with a tool of ultrahigh energy accelerators probing an unknown extremely microscopic world. Harnessing the recent advance of ultra-intense ultra-short pulse lasers, the worldwide research has made a tremendous breakthrough in demonstrating high-energy high-quality particle beams in a compact scale, so called "dream beams on a table top", which represents monoenergetic electron beams from laser wakefield accelerators and GeV acceleration by capillary plasma-channel laser wakefield accelerators. This lecture reviews recent progress of results on laser-driven plasma based accelerator experiments to quest for particle acceleration physics in intense laser-plasma interactions and to present new outlook for the GeV-range high-energy laser plasma accelerators.

  10. Progress of Laser-Driven Plasma Accelerators

    SciTech Connect

    Nakajima, Kazuhisa

    2007-07-11

    There is a great interest worldwide in plasma accelerators driven by ultra-intense lasers which make it possible to generate ultra-high gradient acceleration and high quality particle beams in a much more compact size compared with conventional accelerators. A frontier research on laser and plasma accelerators is focused on high energy electron acceleration and ultra-short X-ray and Tera Hertz radiations as their applications. These achievements will provide not only a wide range of sciences with benefits of a table-top accelerator but also a basic science with a tool of ultrahigh energy accelerators probing an unknown extremely microscopic world.Harnessing the recent advance of ultra-intense ultra-short pulse lasers, the worldwide research has made a tremendous breakthrough in demonstrating high-energy high-quality particle beams in a compact scale, so called ''dream beams on a table top'', which represents monoenergetic electron beams from laser wakefield accelerators and GeV acceleration by capillary plasma-channel laser wakefield accelerators. This lecture reviews recent progress of results on laser-driven plasma based accelerator experiments to quest for particle acceleration physics in intense laser-plasma interactions and to present new outlook for the GeV-range high-energy laser plasma accelerators.

  11. Experimental studies of plasma wake-field acceleration and focusing

    SciTech Connect

    Rosenzweig, J.B.; Cole, B.; Ho, C.; Gai, W.; Konecny, R.; Mtingwa, S.; Norem, J.; Rosing, M.; Schoessow, P.; Simpson, J.

    1989-07-18

    More than four years after the initial proposal of the Plasma Wake-field Accelerator (PWFA), it continues to be the object of much investigation, due to the promise of the ultra-high accelerating gradients that can exist in relativistic plasma waves driven in the wake of charged particle beams. These large amplitude plasma wake-fields are of interest in the laboratory, both for the wealth of basic nonlinear plasma wave phenomena which can be studied, as well as for the applications of acceleration of focusing of electrons and positrons in future linear colliders. Plasma wake-field waves are also of importance in nature, due to their possible role in direct cosmic ray acceleration. The purpose of the present work is to review the recent experimental advances made in PWFA research at Argonne National Laboratory, in which many interesting beam and plasma phenomena have been observed. Emphasis is given to discussion of the nonlinear aspects of the PWFA beam-plasma interaction. 29 refs., 13 figs.

  12. Relativistic electron acceleration by oblique whistler waves

    SciTech Connect

    Yoon, Peter H.; Pandey, Vinay S.; Lee, Dong-Hun

    2013-11-15

    Test-particle simulations of electrons interacting with finite-amplitude, obliquely propagating whistler waves are carried out in order to investigate the acceleration of relativistic electrons by these waves. According to the present findings, an efficient acceleration of relativistic electrons requires a narrow range of oblique propagation angles, close to the whistler resonance cone angle, when the wave amplitude is held constant at relatively low value. For a constant wave propagation angle, it is found that a range of oblique whistler wave amplitudes permits the acceleration of relativistic electrons to O(MeV) energies. An initial distribution of test electrons is shown to form a power-law distribution when plotted in energy space. It is also found that the acceleration is largely uniform in electron pitch-angle space.

  13. Millimeter Wave Communication through Plasma

    NASA Technical Reports Server (NTRS)

    Bastin, Gary L.

    2008-01-01

    Millimeter wave communication through plasma at frequencies of 35 GHz or higher shows promise in maintaining communications connectivity during rocket launch and re-entry, critical events which are typically plagued with communication dropouts. Extensive prior research into plasmas has characterized the plasma frequency at these events, and research at the Kennedy Space Center is investigating the feasibility of millimeter communication through these plasma frequencies.

  14. The Potential for Ambient Plasma Wave Propulsion

    NASA Technical Reports Server (NTRS)

    Gilland, James H.; Williams, George J.

    2016-01-01

    A truly robust space exploration program will need to make use of in-situ resources as much as possible to make the endeavor affordable. Most space propulsion concepts are saddled with one fundamental burden; the propellant needed to produce momentum. The most advanced propulsion systems currently in use utilize electric and/or magnetic fields to accelerate ionized propellant. However, significant planetary exploration missions in the coming decades, such as the now canceled Jupiter Icy Moons Orbiter, are restricted by propellant mass and propulsion system lifetimes, using even the most optimistic projections of performance. These electric propulsion vehicles are inherently limited in flexibility at their final destination, due to propulsion system wear, propellant requirements, and the relatively low acceleration of the vehicle. A few concepts are able to utilize the environment around them to produce thrust: Solar or magnetic sails and, with certain restrictions, electrodynamic tethers. These concepts focus primarily on using the solar wind or ambient magnetic fields to generate thrust. Technically immature, quasi-propellantless alternatives lack either the sensitivity or the power to provide significant maneuvering. An additional resource to be considered is the ambient plasma and magnetic fields in solar and planetary magnetospheres. These environments, such as those around the Sun or Jupiter, have been shown to host a variety of plasma waves. Plasma wave propulsion takes advantage of an observed astrophysical and terrestrial phenomenon: Alfven waves. These are waves that propagate in the plasma and magnetic fields around and between planets and stars. The generation of Alfven waves in ambient magnetic and plasma fields to generate thrust is proposed as a truly propellantless propulsion system which may enable an entirely new matrix of exploration missions. Alfven waves are well known, transverse electromagnetic waves that propagate in magnetized plasmas at

  15. Stochastic acceleration of ions driven by Pc1 wave packets

    SciTech Connect

    Khazanov, G. V. Sibeck, D. G.; Tel'nikhin, A. A.; Kronberg, T. K.

    2015-07-15

    The stochastic motion of protons and He{sup +} ions driven by Pc1 wave packets is studied in the context of resonant particle heating. Resonant ion cyclotron heating typically occurs when wave powers exceed 10{sup −4} nT{sup 2}/Hz. Gyroresonance breaks the first adiabatic invariant and energizes keV ions. Cherenkov resonances with the electrostatic component of wave packets can also accelerate ions. The main effect of this interaction is to accelerate thermal protons to the local Alfven speed. The dependencies of observable quantities on the wave power and plasma parameters are determined, and estimates for the heating extent and rate of particle heating in these wave-particle interactions are shown to be in reasonable agreement with known empirical data.

  16. EXPERIMENTAL STUDY OF SHOCK WAVE DYNAMICS IN MAGNETIZED PLASMAS

    SciTech Connect

    Nirmol K. Podder

    2009-03-17

    In this four-year project (including one-year extension), the project director and his research team built a shock-wave-plasma apparatus to study shock wave dynamics in glow discharge plasmas in nitrogen and argon at medium pressure (1–20 Torr), carried out various plasma and shock diagnostics and measurements that lead to increased understanding of the shock wave acceleration phenomena in plasmas. The measurements clearly show that in the steady-state dc glow discharge plasma, at fixed gas pressure the shock wave velocity increases, its amplitude decreases, and the shock wave disperses non-linearly as a function of the plasma current. In the pulsed discharge plasma, at fixed gas pressure the shock wave dispersion width and velocity increase as a function of the delay between the switch-on of the plasma and shock-launch. In the afterglow plasma, at fixed gas pressure the shock wave dispersion width and velocity decrease as a function of the delay between the plasma switch-off and shock-launch. These changes are found to be opposite and reversing towards the room temperature value which is the initial condition for plasma ignition case. The observed shock wave properties in both igniting and afterglow plasmas correlate well with the inferred temperature changes in the two plasmas.

  17. Magnetized Plasma-filled Waveguide: A New High-Gradient Accelerating Structure

    SciTech Connect

    Avitzour, Yoav; Shvets, Gennady

    2009-01-22

    Electromagnetic waves confined between the metal plates of a plasma-filled waveguide are investigated. It is demonstrated that when the plasma is magnetized along the metallic plates, there exists a luminous accelerating wave propagating with a very slow group velocity. It is shown that the magnetized plasma 'isolates' the metal wall from the transverse electric field, thereby reducing potential breakdown problems. Applications of the metallic plasma-filled waveguide to particle accelerations and microwave pulse manipulation are described.

  18. A New Type of Plasma Wakefield Accelerator Driven By Magnetowaves

    SciTech Connect

    Chen, Pisin; Chang, Feng-Yin; Lin, Guey-Lin; Noble, Robert J.; Sydora, Richard; /Alberta U.

    2011-09-12

    We present a new concept for a plasma wakefield accelerator driven by magnetowaves (MPWA). This concept was originally proposed as a viable mechanism for the 'cosmic accelerator' that would accelerate cosmic particles to ultra-high energies in the astrophysical setting. Unlike the more familiar plasma wakefield accelerator (PWFA) and the laser wakefield accelerator (LWFA) where the drivers, the charged-particle beam and the laser, are independently existing entities, MPWA invokes the high-frequency and high-speed whistler mode as the driver, which is a medium wave that cannot exist outside of the plasma. Aside from the difference in drivers, the underlying mechanism that excites the plasma wakefield via the ponderomotive potential is common. Our computer simulations show that under appropriate conditions, the plasma wakefield maintains very high coherence and can sustain high-gradient acceleration over many plasma wavelengths. We suggest that in addition to its celestial application, the MPWA concept can also be of terrestrial utility. A proof-of-principle experiment on MPWA would benefit both terrestrial and celestial accelerator concepts.

  19. ACCELERATION OF THE SOLAR WIND BY ALFVEN WAVE PACKETS

    SciTech Connect

    Galinsky, V. L.; Shevchenko, V. I.

    2013-01-20

    A scale separation kinetic model of the solar wind acceleration is presented. The model assumes an isotropic Maxwellian distribution of protons and a constant influx of outward propagating Alfven waves with a single exponent Kolmogorov-type spectrum at the base of a coronal acceleration region ({approx}2 R {sub Sun }). Our results indicate that nonlinear cyclotron resonant interaction taking energy from Alfven waves and depositing it into mostly perpendicular heating of protons in initially weakly expanding plasma in a spherically non-uniform magnetic field is able to produce the typical fast solar wind velocities for the typical plasma and wave conditions after expansion to about 5-10 solar radii R {sub Sun }. The acceleration model takes into account the gravity force and the ambipolar electric field, as well as the mirror force, which plays the most important role in driving the solar wind acceleration. Contrary to the recent claims of Isenberg, the cold plasma dispersion only slightly slows down the acceleration and actually helps in obtaining the more realistic fast solar wind speeds.

  20. Acceleration of energetic particles. [in collisionless shock waves in interstellar space

    NASA Technical Reports Server (NTRS)

    Forman, M. A.; Webb, G. M.

    1985-01-01

    Acceleration of some particles from the background plasma to highly superthermal energies is a common feature of collisionless shocks in interplanetary space. The complete in situ measurements of bulk flows, thermal plasma, electromagnetic waves and energetic particles available for interplanetary shocks both suggest and test the models of shock acceleration in the solar system and the rest of the universe. This tutorial will review the present state of shock acceleration theory. Scatter-free acceleration by grad B drift in the plasma electric field E = -V x B/c, and diffusive acceleration resulting from scattering by Alfven waves in the plasma on both sides of the shock are discussed. The diffusive theory in simple steady state gives power-law spectra, but also shows the effects of time-dependent shocks and injection rates, escape and other losses, the self-consistent Alfven wave spectra, and plasma flow fields affected by diffusive energetic particle acceleration.

  1. MHD Simulations of Thermal Plasma Jets in Coaxial Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Subramaniam, Vivek; Raja, Laxminarayan

    2015-09-01

    The development of a magneto-hydrodynamics (MHD) numerical tool to study high energy density thermal plasma in coaxial plasma accelerators is presented. The coaxial plasma accelerator is a device used simulate the conditions created at the confining wall of a thermonuclear fusion reactor during an edge localized mode (ELM) disruption event. This is achieved by creating magnetized thermal plasma in a coaxial volume which is then accelerated by the Lorentz force to form a high velocity plasma jet. The simulation tool developed solves the resistive MHD equation using a finite volume method (FVM) framework. The acceleration and subsequent demagnetization of the plasma as it travels down the length of the accelerator is simulated and shows good agreement with experiments. Additionally, a model to study the thermalization of the plasma at the inlet is being developed in order to give self-consistent initial conditions to the MHD solver.

  2. Calculation of Electromagnetic Quasistatic Plasma Waves*

    NASA Astrophysics Data System (ADS)

    Cooley, J.; Antonsen, T. M., Jr.; Mori, W.

    2001-10-01

    Plasma based particle acceleration requires the generation of plasma wave wakes which maintain their coherence over long distances. For example in Laser Wake Field Acceleration (LWFA) schemes the laser pulse must propagate tens of centimeters, which coresponds to many Rayleigh lengths, and in Plasma Wake Field Acceleration (PWFA) the particle beam must be propagated many meters. These wakes, and their effect on the driver (Laser or particle beam) can be simulated efficiently in the quasistatic approximation [1]. In this approximation the driver does not evolve during the time a plasma electron spends in the driver. We discuss here various numerical algorithms for determining the full electromagnetic wake in this case. The problem is complicated in that the particle trajectories and wake fields must be determined iteratively when the wake becomes electromagnetic. The effect of different choices for the gauge will be presented. [1] "Kinetic Modeling of Intense, Short Laser Pulses Propagating in Tenuous Plasma", P. Mora and T. M. Antonsen Jr., Phys Plasma 4, 217 (1997) *Work supported by NSF and DOE

  3. Waves and instabilities in plasmas

    SciTech Connect

    Chen, L.

    1987-01-01

    The contents of this book are: Plasma as a Dielectric Medium; Nyquist Technique; Absolute and Convective Instabilities; Landau Damping and Phase Mixing; Particle Trapping and Breakdown of Linear Theory; Solution of Viasov Equation via Guilding-Center Transformation; Kinetic Theory of Magnetohydrodynamic Waves; Geometric Optics; Wave-Kinetic Equation; Cutoff and Resonance; Resonant Absorption; Mode Conversion; Gyrokinetic Equation; Drift Waves; Quasi-Linear Theory; Ponderomotive Force; Parametric Instabilities; Problem Sets for Homework, Midterm and Final Examinations.

  4. Hybrid Laser-Plasma Wakefield Acceleration

    SciTech Connect

    Hidding, B.; Koenigstein, T.; Willi, O.; Pretzler, G.; Karsch, S.; Rosenzweig, J. B.

    2010-11-04

    The concept of driving a driver/witness-type plasma wakefield accelerator (PWFA) with quasimonoenergetic double electron bunches from a laser wakefield accelerator (LWFA) is studied. In the quasimonoenergetic LWFA/SMLWFA (self-modulated LWFA) regime, it is possible to generate multiple quasimonoenergetic electron bunches with durations of only a few fs and distances of only a few tens of fs with a comparably simple experimental setup. In a subsequent high-density plasma afterburner stage the witness bunch energy can be boosted in the plasma wakefield generated by the driver. Such a hybrid system can increase the maximum energy output of a laser wakefield accelerator and is well suited to study driver/witness plasma accelerator phenomena and can be used as a cost-effective test-bed for future high-energy plasma-based accelerators.

  5. Hybrid Laser-Plasma Wakefield Acceleration

    NASA Astrophysics Data System (ADS)

    Hidding, B.; Königstein, T.; Karsch, S.; Willi, O.; Pretzler, G.; Rosenzweig, J. B.

    2010-11-01

    The concept of driving a driver/witness-type plasma wakefield accelerator (PWFA) with quasimonoenergetic double electron bunches from a laser wakefield accelerator (LWFA) is studied. In the quasimonoenergetic LWFA/SMLWFA (self-modulated LWFA) regime, it is possible to generate multiple quasimonoenergetic electron bunches with durations of only a few fs and distances of only a few tens of fs with a comparably simple experimental setup. In a subsequent high-density plasma afterburner stage the witness bunch energy can be boosted in the plasma wakefield generated by the driver. Such a hybrid system can increase the maximum energy output of a laser wakefield accelerator and is well suited to study driver/witness plasma accelerator phenomena and can be used as a cost-effective test-bed for future high-energy plasma-based accelerators.

  6. Channeling of relativistic laser pulses, surface waves, and electron acceleration.

    PubMed

    Naseri, N; Pesme, D; Rozmus, W; Popov, K

    2012-03-01

    The interaction of a high-energy relativistic laser pulse with an underdense plasma is studied by means of 3-dimensional particle in cell simulations and theoretical analysis. For powers above the threshold for channeling, the laser pulse propagates as a single mode in an electron-free channel during a time of the order of 1 picosecond. The steep laser front gives rise to the excitation of a surface wave along the sharp boundaries of the ion channel. The surface wave first traps electrons at the channel wall and preaccelerates them to relativistic energies. These particles then have enough energy to be further accelerated in a second stage through an interplay between the acceleration due to the betatron resonance and the acceleration caused by the longitudinal part of the surface wave electric field. It is necessary to introduce this two-stage process to explain the large number of high-energy electrons observed in the simulations. PMID:22463415

  7. Electron Acceleration by Langmuir Waves Produced by a Decay Cascade

    NASA Astrophysics Data System (ADS)

    Krafft, C.; Volokitin, A. S.

    2016-04-01

    It was recently reported that a significant part of the Langmuir waveforms observed by the STEREO satellite during type III solar radio bursts are likely consistent with the occurrence of electrostatic decay instabilities, when a Langmuir wave { L } resonantly interacts with another Langmuir wave { L }\\prime and an ion sound wave { S }\\prime through the decay channel { L }\\to { L }\\prime +{ S }\\prime . Usually such wave–wave interactions occur in regions of the solar wind where the presence of electron beams can drive Langmuir turbulence to levels allowing waves { L } to decay. Moreover, such solar wind plasmas can present long-wavelength, randomly fluctuating density inhomogeneities or monotonic density gradients which can significantly modify the development of such resonant instabilities. If some conditions are met, the waves can encounter a second decay cascade (SDC) according to { L }\\prime \\to { L }\\prime\\prime +{ S }\\prime\\prime . Analytical estimates and observations based on numerical simulations show that the Langmuir waves { L }\\prime\\prime produced by this SDC can accelerate beam particles up to velocities and kinetic energies exceeding two times the beam drift velocity vb and half the initial beam energy, respectively. Moreover, this process can be particularly efficient if the scattering effects of waves on the background plasma inhomogeneities have already accelerated a sufficient amount of beam electrons up to the velocity range where the phase velocities of the { L }\\prime\\prime waves are lying. The paper shows that the conditions necessary for such process to occur can be easily met in solar wind plasmas if the beam velocities do not exceed around 35 times the plasma thermal velocity.

  8. Stochastic electron acceleration during turbulent reconnection in strong shock waves

    NASA Astrophysics Data System (ADS)

    Matsumoto, Yosuke

    2016-04-01

    Acceleration of charged particles is a fundamental topic in astrophysical, space and laboratory plasmas. Very high energy particles are commonly found in the astrophysical and planetary shocks, and in the energy releases of solar flares and terrestrial substorms. Evidence for relativistic particle production during such phenomena has attracted much attention concerning collisionless shock waves and magnetic reconnection, respectively, as ultimate plasma energization mechanisms. While the energy conversion proceeds macroscopically, and therefore the energy mostly flows to ions, plasma kinetic instabilities excited in a localized region have been considered to be the main electron heating and acceleration mechanisms. We present that efficient electron energization can occur in a much larger area during turbulent magnetic reconnection from the intrinsic nature of a strong collisionless shock wave. Supercomputer simulations have revealed a multiscale shock structure comprising current sheets created via an ion-scale Weibel instability and resulting energy dissipation through magnetic reconnection. A part of the upstream electrons undergoes first-order Fermi acceleration by colliding with reconnection jets and magnetic islands, giving rise to a nonthermal relativistic population downstream. The dynamics has shed new light on magnetic reconnection as an agent of energy dissipation and particle acceleration in strong shock waves.

  9. Plasma wakefield acceleration in self-ionized gas or plasmas.

    PubMed

    Deng, S; Barnes, C D; Clayton, C E; O'Connell, C; Decker, F J; Erdem, O; Fonseca, R A; Huang, C; Hogan, M J; Iverson, R; Johnson, D K; Joshi, C; Katsouleas, T; Krejcik, P; Lu, W; Marsh, K A; Mori, W B; Muggli, P; Tsung, F

    2003-10-01

    Tunnel ionizing neutral gas with the self-field of a charged particle beam is explored as a possible way of creating plasma sources for a plasma wakefield accelerator [Bruhwiler et al., Phys. Plasmas (to be published)]. The optimal gas density for maximizing the plasma wakefield without preionized plasma is studied using the PIC simulation code OSIRIS [R. Hemker et al., in Proceeding of the Fifth IEEE Particle Accelerator Conference (IEEE, 1999), pp. 3672-3674]. To obtain wakefields comparable to the optimal preionized case, the gas density needs to be seven times higher than the plasma density in a typical preionized case. A physical explanation is given. PMID:14683089

  10. Plasma waves in parametric interactions

    NASA Astrophysics Data System (ADS)

    Yampolsky, Nikolai Andreevich

    The nonlinear laser-plasma interaction is widely discussed in the modern plasma literature with applications to inertial confinement fusion, generation of fast electrons, and amplification of high power radiation. Among nonlinear wave phenomena in plasma, the parametric wave coupling often plays the dominant role in laser-plasma interaction at moderate laser intensities since it is the lowest order nonlinear effect. The plasma wave can mediate the parametric laser coupling with high efficiency. We study the interplay of the parametric laser-plasma interaction and other physical effects which may affect this interaction. We study this interplay with an emphasis on the plasma-based backward Raman amplifier (BRA) based on the three-wave coupling. Three major types of physical effects in the parametric wave coupling are studied. In the first part of the thesis, we find the longitudinal profiles of the interacting waves in cases of interest for pulse compression. We find the solution for the output pulse in backward Raman amplification seeded by a laser pulse of finite duration. We also propose a new scheme for high-power amplification for pulses in the terahertz frequency range. For this scheme, based on the four-wave mixing in a capillary filled with plasma, we find the profile of the output pulse. The second part of this thesis is devoted to transverse effects, which may reduce the focusability of the output pulse in backward Raman amplification. We find that the transverse modulations of the pump can be averaged and do not reduce the amplified pulse focusability if the longitudinal length of these modulations is much smaller than the amplification length. In the third part, we study the kinetic effects. We propose a simplified fluid model for the nonlinear Landau damping of a parametrically driven plasma wave and study the effect of nonlinear Landau damping in backward Raman amplification. This simplified model can be useful not only for understanding complex

  11. Radiation from accelerated Alfven solitons in inhomogeneous plasmas

    NASA Technical Reports Server (NTRS)

    Lakhina, G. S.; Buti, B.; Tsintsadze, N. L.

    1990-01-01

    In a weakly inhomogeneous plasma, the large-amplitude Alfven waves propagating parallel to the ambient magnetic field are shown to evolve into accelerated Alfven solitons. Nonlinear interaction of the accelerated Alfven solitons with the Langmuir waves results in the emission of coherent radiations. Analytical expression for the power radiated per unit solid angle from a soliton is derived for two inhomogeneity profiles, namely the linear profile and the parabolic profile. For the case of uniform plasmas, the emission occurs via a decay-type process or resonant modes. In the presence of inhomogeneity, nonresonant modes provide a new channel for the emission of radiation. The power radiated per unit solid angle is computed for the parameters relevant to Comet Halley's plasma environment. For the nonresonant modes it is found to be several orders of magnitude higher than that for the case of resonant modes.

  12. Plasma waves in the inhomogeneous auroral ionosphere

    NASA Astrophysics Data System (ADS)

    Kintner, Paul

    1999-11-01

    Detailed observations of plasma waves in the auroral ionosphere during the past decade have revealed the existence of modes which depend on inhomogeneities the order of or somewhat larger than the ion gyroradius. The auroral ionosphere is the most strongly driven region of space which is conveniently accessible to space probes. The region is filled with currents, electric fields, electron beams and transversely accelerated ions. During the past decade improved instrumentation has permitted investigation of the ionospheric plasma properties down to spatial scales including the ion gyroradius. These investigations have revealed at least two novel wave modes not previously anticipated. The first wave mode is associated with cylindrical density cavities aligned along the geomagnetic field. The cavities act like resonant structures near the lower hybrid frequency and admit two classes of waves near the lower hybrid frequency. Below the lower hybrid frequency the modes are trapped and rotate in a left-hand sense. Above the lower hybrid frequency waves the modes are not trapped but rotate in a right-hand sense. The symmetry in rotation is broken by the Hall current and the sense of rotation has been confirmed with sounding rocket interferometers. The cavity wave fields also accelerate ions transversely which maintain and expand the cavity dimensions. The second wave mode is less well understood and has the phenomenological name of broad band ELF (BBELF) electric fields. The bandwidth of this mode covers the ion cyclotron frequencies (O+ and H+) and it is also associated with transversely accelerated ions but not with ionospheric density structuring. Instead these modes are associated with electron flow in field-aligned currents although the flows are sub-critical for either the ion acoustic or electrostatic ion cyclotron modes. Furthermore the frequency spectrum shows no structure at the ion cyclotron frequencies. Limited evidence suggests that these modes are shear

  13. The Polar Plasma Wave Instrument

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Persoon, A. M.; Randall, R. F.; Odem, D. L.; Remington, S. L.; Averkamp, T. F.; Debower, M. M.; Hospodarsky, G. B.; Huff, R. L.; Kirchner, D. L.

    1995-01-01

    The Plasma Wave Instrument on the Polar spacecraft is designed to provide measurements of plasma waves in the Earth's polar regions over the frequency range from 0.1 Hz to 800 kHz. Three orthogonal electric dipole antennas are used to detect electric fields, two in the spin plane and one aligned along the spacecraft spin axis. A magnetic loop antenna and a triaxial magnetic search coil antenna are used to detect magnetic fields. Signals from these antennas are processed by five receiver systems: a wideband receiver, a high-frequency waveform receiver, a low-frequency waveform receiver, two multichannel analyzers; and a pair of sweep frequency receivers. Compared to previous plasma wave instruments, the Polar plasma wave instrument has several new capabilities. These include (1) an expanded frequency range to improve coverage of both low- and high-frequency wave phenomena, (2) the ability to simultaneously capture signals from six orthogonal electric and magnetic field sensors, and (3) a digital wideband receiver with up to 8-bit resolution and sample rates as high as 249k samples s(exp -1).

  14. The Polar Plasma Wave Instrument

    NASA Astrophysics Data System (ADS)

    Gurnett, D. A.; Persoon, A. M.; Randall, R. F.; Odem, D. L.; Remington, S. L.; Averkamp, T. F.; Debower, M. M.; Hospodarsky, G. B.; Huff, R. L.; Kirchner, D. L.; Mitchell, M. A.; Pham, B. T.; Phillips, J. R.; Schintler, W. J.; Sheyko, P.; Tomash, D. R.

    1995-02-01

    The Plasma Wave Instrument on the Polar spacecraft is designed to provide measurements of plasma waves in the Earth's polar regions over the frequency range from 0.1 Hz to 800 kHz. Three orthogonal electric dipole antennas are used to detect electric fields, two in the spin plane and one aligned along the spacecraft spin axis. A magnetic loop antenna and a triaxial magnetic search coil antenna are used to detect magnetic fields. Signals from these antennas are processed by five receiver systems: a wideband receiver, a high-frequency waveform receiver, a low-frequency waveform receiver, two multichannel analyzers; and a pair of sweep frequency receivers. Compared to previous plasma wave instruments, the Polar plasma wave instrument has several new capabilities. These include (1) an expanded frequency range to improve coverage of both low- and high-frequency wave phenomena, (2) the ability to simultaneously capture signals from six orthogonal electric and magnetic field sensors, and (3) a digital wideband receiver with up to 8-bit resolution and sample rates as high as 249k samples s-1.

  15. Large-amplitude plasma wave generation with a high-intensity short-pulse beat wave.

    PubMed

    Walton, B; Najmudin, Z; Wei, M S; Marle, C; Kingham, R J; Krushelnick, K; Dangor, A E; Clarke, R J; Poulter, M J; Hernandez-Gomez, C; Hawkes, S; Neely, D; Collier, J L; Danson, C N; Fritzler, S; Malka, V

    2002-12-15

    A short-pulse laser beat wave scheme for advanced particle accelerator applications is examined. A short, intense (3-ps, >10(18)-W cm(-2)) two-frequency laser pulse is produced by use of a modified chirped-pulse amplification scheme and is shown to produce relativistic plasma waves during interactions with low-density plasmas. The generation of plasma waves was observed by measurement of forward Raman scattering. Resonance was found to occur at an electron density many times that expected, owing to ponderomotive displacement of plasma within the focal region. PMID:18033483

  16. Strong turbulence of plasma waves

    NASA Technical Reports Server (NTRS)

    Goldman, M. V.

    1984-01-01

    This paper reviews recent work related to modulational instability and wave envelope self-focusing in dynamical and statistical systems. After introductory remarks pertinent to nonlinear optics realizations of these effects, the author summarizes the status of the subject in plasma physics, where it has come to be called 'strong Langmuir turbulence'. The paper treats the historical development of pertinent concepts, analytical theory, numerical simulations, laboratory experiments, and spacecraft observations. The role of self-similar self-focusing Langmuir envelope wave packets is emphasized, both in the Zakharov equation model for the wave dynamics and in a statistical theory based on this dynamical model.

  17. Non-dispersive, accelerated matter-waves

    NASA Astrophysics Data System (ADS)

    Saif, Farhan; Naseer, Khalid; Ayub, Muhammad

    2014-04-01

    It is shown that under certain dynamical conditions a material wave packet displays coherent, non-dispersive accelerated evolution in gravitational field over a modulated atomic mirror. The phenomenon takes place as a consequence of simultaneous presence of the dynamical localization and the coherent Fermi acceleration for the same modulation amplitude. It is purely a quantum mechanical effect as the windows of modulation strengths supporting dynamical localization and Fermi acceleration overlap for larger effective Planck constant. Present day experimental techniques make it feasible to realize the system in laboratory.

  18. Chaotic waves in Hall thruster plasma

    SciTech Connect

    Peradzynski, Zbigniew; Barral, S.; Kurzyna, J.; Makowski, K.; Dudeck, M.

    2006-01-15

    The set of hyperbolic equations of the fluid model describing the acceleration of plasma in a Hall thruster is analyzed. The characteristic feature of the flow is the existence of a trapped characteristic; i.e. there exists a characteristic line, which never intersects the boundary of the flow region in the thruster. To study the propagation of short wave perturbations, the approach of geometrical optics (like WKB) can be applied. This can be done in a linear as well as in a nonlinear version. The nonlinear version describes the waves of small but finite amplitude. As a result of such an approach one obtains so called transport equation, which are governing the wave amplitude. Due to the existence of trapped characteristics this transport equation appears to have chaotic (turbulent) solutions in both, linear and nonlinear versions.

  19. Waves in Plasmas

    SciTech Connect

    Tracy, Eugene R

    2009-09-21

    Quadratic corrections to the metaplectic formulation of mode conversions. In this work we showed how to systematically deal with quadratic corrections beyond the usual linearization of the dispersion matrix at a conversion. The linearization leads to parabolic cylinder functions as the local approximation to the full-wave behavior, but these do not include the variation in amplitude associated with ray refraction in the neighborhood of the conversion. Hence, the region over which they give a good fit to the incoming and outgoing WKB solutions is small. By including higher order corrections it is possible to provide a much more robust matching. We also showed that it was possible, in principle, to extend these methods to arbitrary order. A new normal form for mode conversion. This is based upon our earlier NSF-DOE-funded work on ray helicity. We have begun efforts to apply these new ideas in practical ray tracing algorithms. Group theoretical foundation of path integrals and phase space representations of wave problems. Using the symbol theory of N. Zobin, we developed a new understanding of path integrals on phase space. The initial goal was to find practical computational tools for dealing with non-standard mode conversions. Along the way we uncovered a new way to represent wave functions directly on phase space without the intermediary of a Wigner function. We are exploring the use of these ideas for numerical studies of conversion, with the goal of eventually incorporating kinetic effects. Wave packet studies of gyroresonance crossing. In earlier work, Huanchun Ye and Allan Kaufman -- building upon ideas due to Lazar Friedland -- had shown that gyroresonance crossings could be treated as a double conversion. This perspective is one we have used for many of our papers since then. We are now performing a detailed numerical comparison between full-wave and ray tracing approaches in the study of minority-ion gyroresonance crossing. In this study, a fast magnetosonic

  20. Thermal effects in plasma-based accelerators

    SciTech Connect

    Esarey, E.; Schroeder, C.B.; Michel, E.; Shadwick, B.A.; Geddes,C.G.R.; Leemans, W.P.

    2007-01-09

    Finite plasma temperature can modify the structure of thewake field, reduce the wave-breaking field, and lead to self-trappedelectrons, which can degrade the electron bunch quality in a plasma-basedaccelerator. A relativistic warm fluid theory is used to describe theplasma temperature evolution and alterations to the structure of anonlinear periodic wave exited in a warm plasma. The trapping thresholdfor a plasma electron and the fraction of electrons trapped from athermal distribution are examined using a single-particle model.Numerical artifacts in particle-in-cell models that can mimic the physicsassociated with finite momentum spread are discussed.

  1. Plasma Dark Current in Self-Ionized Plasma Wakefield Accelerators

    SciTech Connect

    Oz, E.; Deng, S.; Katsouleas, T.; Muggli, P.; Iverson, R.; Johnson, D.K.; Krejcik, P.; O'Connell, C.; Siemann, R.H.; Walz, D.; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; /UCLA

    2006-01-30

    Evidence of particle trapping has been observed in a beam driven Plasma Wake Field Accelerator (PWFA) experiment, E164X, conducted at the Stanford Linear Accelerator Center by a collaboration which includes USC, UCLA and SLAC. Such trapping produces plasma dark current when the wakefield amplitude is above a threshold value and may place a limit on the maximum acceleration gradient in a PWFA. Trapping and dark current are enhanced when in an ionizing plasma, that is self-ionized by the beam. Here we present experimental results.

  2. Waves in Space Plasmas (WISP)

    NASA Technical Reports Server (NTRS)

    Calvert, Wynne

    1994-01-01

    Activities under this project have included participation in the Waves in Space Plasmas (WISP) program, a study of the data processing requirements for WISP, and theoretical studies of radio sounding, ducting, and magnetoionic theory. An analysis of radio sounding in the magnetosphere was prepared.

  3. Current in wave driven plasmas

    SciTech Connect

    Karney, C.F.F.; Fisch, N.J.

    1985-06-01

    A theory for the generation of current in a toroidal plasma by radio-frequency waves is presented. The effect of an opposing electric field is included, allowing the case of time varying currents to be studied. The key quantities that characterize this regime are identified and numerically calculated. Circuit equations suitable for use in ray-tracing and transport codes are given.

  4. On the breaking of a plasma wave in a thermal plasma. II. Electromagnetic wave interaction with the breaking plasma wave

    SciTech Connect

    Bulanov, Sergei V.; Esirkepov, Timur Zh.; Kando, Masaki; Koga, James K.; Pirozhkov, Alexander S.; Nakamura, Tatsufumi; Bulanov, Stepan S.; Schroeder, Carl B.; Esarey, Eric; Califano, Francesco; Pegoraro, Francesco

    2012-11-15

    In thermal plasma, the structure of the density singularity formed in a relativistically large amplitude plasma wave close to the wavebreaking limit leads to a refraction coefficient with discontinuous spatial derivatives. This results in a non-exponentially small above-barrier reflection of an electromagnetic wave interacting with the nonlinear plasma wave.

  5. The ETA-II linear induction accelerator and IMP wiggler: A high-average-power millimeter-wave free-electron-laser for plasma heating

    SciTech Connect

    Allen, S.L.; Scharlemann, E.T.

    1992-05-01

    We have constructed a 140-GHz free-electron laser to generate high-average-power microwaves for heating the MTX tokamak plasma. A 5.5-m steady-state wiggler (intense Microwave Prototype-IMP) has been installed at the end of the upgraded 60-cell ETA-II accelerator, and is configured as an FEL amplifier for the output of a 140-GHz long-pulse gyrotron. Improvements in the ETA-II accelerator include a multicable-feed power distribution network, better magnetic alignment using a stretched-wire alignment technique (SWAT). and a computerized tuning algorithm that directly minimizes the transverse sweep (corkscrew motion) of the electron beam. The upgrades were first tested on the 20-cell, 3-MeV front end of ETA-II and resulted in greatly improved energy flatness and reduced corkscrew motion. The upgrades were then incorporated into the full 60-cell configuration of ETA-II, along with modifications to allow operation in 50-pulse bursts at pulse repetition frequencies up to 5 kHz. The pulse power modifications were developed and tested on the High Average Power Test Stand (HAPTS), and have significantly reduced the voltage and timing jitter of the MAG 1D magnetic pulse compressors. The 2-3 kA. 6-7 MeV beam from ETA-II is transported to the IMP wiggler, which has been reconfigured as a laced wiggler, with both permanent magnets and electromagnets, for high magnetic field operation. Tapering of the wiggler magnetic field is completely computer controlled and can be optimized based on the output power. The microwaves from the FEL are transmitted to the MTX tokamak by a windowless quasi-optical microwave transmission system. Experiments at MTX are focused on studies of electron-cyclotron-resonance heating (ECRH) of the plasma. We summarize here the accelerator and pulse power modifications, and describe the status of ETA-II, IMP, and MTX operations.

  6. A Plasma Algorithm for Plasmoid Accelerator Modeling

    NASA Astrophysics Data System (ADS)

    Loverich, John

    2006-10-01

    In this paper we present a discontinuous Galerkin approach to resistive/ideal MHD and Hall MHD plasma models. Divergence cleaning is used to ensure that divergence errors are contained. Results of typical plasma physics benchmarks and axisymmetric simulations of FRC accelerators for high powered spacecraft propulsion will be presented.

  7. The plasma physics of shock acceleration

    NASA Technical Reports Server (NTRS)

    Jones, Frank C.; Ellison, Donald C.

    1991-01-01

    The history and theory of shock acceleration is reviewed, paying particular attention to theories of parallel shocks which include the backreaction of accelerated particles on the shock structure. The work that computer simulations, both plasma and Monte Carlo, are playing in revealing how thermal ions interact with shocks and how particle acceleration appears to be an inevitable and necessary part of the basic plasma physics that governs collisionless shocks is discussed. Some of the outstanding problems that still confront theorists and observers in this field are described.

  8. Surface plasma source with anode layer plasma accelerator

    SciTech Connect

    Dudnikov, Vadim

    2012-02-15

    Proposed plasma generation system can be used for high current negative ion beam production and for directed deposition by flux of sputtered neutrals and negative ions. The main mechanism of negative ion formation in surface plasma sources is the secondary emission from low work function surface bombarded by a flux of positive ion or neutrals. The emission of negative ions is enhanced significantly by introducing a small amount of cesium or other substance with low ionization potential. In the proposed source are used positive ions generated by Hall drift plasma accelerator (anode layer plasma accelerator or plasma accelerator with insulated channel, with cylindrical or race track configuration of emission slit). The target-emitter is bombarded by the ion beam accelerated in crossed ExB fields. Negative ions are extracted from the target surface with geometrical focusing and are accelerated by negative voltage applied between emitter and plasma, contacting with the plasma accelerator. Hall drift ion source has a special design with a space for passing of the emitted negative ions and sputtered particles through the positive ion source.

  9. Ion acceleration in expanding ionospheric plasmas

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Schunk, R. W.

    1986-01-01

    Plasma expansion along the ambient magnetic field in regions of density gradients provides a mechanism for accelerating ions. A brief review of the basic phenomenon of plasma expansion is given. Estimates of the energies of the accelerated ions in an expanding ionospheric plasma along geomagnetic flux tubes are obtained by solving the time-dependent hydrodynamic equations. It is found that, over certain altitude ranges, each ion species can be the most energetic; the maximum energies of the different ions are found to be limited to less than about 10 eV for H(+), 5 eV for He(+), and less than about 1.5 eV for O(+).

  10. Application of Plasma Waveguides to High Energy Accelerators

    SciTech Connect

    Milchberg, Howard M

    2013-03-30

    The eventual success of laser-plasma based acceleration schemes for high-energy particle physics will require the focusing and stable guiding of short intense laser pulses in reproducible plasma channels. For this goal to be realized, many scientific issues need to be addressed. These issues include an understanding of the basic physics of, and an exploration of various schemes for, plasma channel formation. In addition, the coupling of intense laser pulses to these channels and the stable propagation of pulses in the channels require study. Finally, new theoretical and computational tools need to be developed to aid in the design and analysis of experiments and future accelerators. Here we propose a 3-year renewal of our combined theoretical and experimental program on the applications of plasma waveguides to high-energy accelerators. During the past grant period we have made a number of significant advances in the science of laser-plasma based acceleration. We pioneered the development of clustered gases as a new highly efficient medium for plasma channel formation. Our contributions here include theoretical and experimental studies of the physics of cluster ionization, heating, explosion, and channel formation. We have demonstrated for the first time the generation of and guiding in a corrugated plasma waveguide. The fine structure demonstrated in these guides is only possible with cluster jet heating by lasers. The corrugated guide is a slow wave structure operable at arbitrarily high laser intensities, allowing direct laser acceleration, a process we have explored in detail with simulations. The development of these guides opens the possibility of direct laser acceleration, a true miniature analogue of the SLAC RF-based accelerator. Our theoretical studies during this period have also contributed to the further development of the simulation codes, Wake and QuickPIC, which can be used for both laser driven and beam driven plasma based acceleration schemes. We

  11. Plasma acceleration processes in an ablative pulsed plasma thruster

    SciTech Connect

    Koizumi, Hiroyuki; Noji, Ryosuke; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2007-03-15

    Plasma acceleration processes in an ablative pulsed plasma thruster (APPT) were investigated. APPTs are space propulsion options suitable for microspacecraft, and have recently attracted much attention because of their low electric power requirements and simple, compact propellant system. The plasma acceleration mechanism, however, has not been well understood. In the present work, emission spectroscopy, high speed photography, and magnetic field measurements are conducted inside the electrode channel of an APPT with rectangular geometry. The successive images of neutral particles and ions give us a comprehensive understanding of their behavior under electromagnetic acceleration. The magnetic field profile clarifies the location where the electromagnetic force takes effect. As a result, it is shown that high density, ablated neutral gas stays near the propellant surface, and only a fraction of the neutrals is converted into plasma and electromagnetically accelerated, leaving the residual neutrals behind.

  12. Inverse mirror plasma experimental device (IMPED) - a magnetized linear plasma device for wave studies

    NASA Astrophysics Data System (ADS)

    Bose, Sayak; Chattopadhyay, P. K.; Ghosh, J.; Sengupta, S.; Saxena, Y. C.; Pal, R.

    2015-04-01

    In a quasineutral plasma, electrons undergo collective oscillations, known as plasma oscillations, when perturbed locally. The oscillations propagate due to finite temperature effects. However, the wave can lose the phase coherence between constituting oscillators in an inhomogeneous plasma (phase mixing) because of the dependence of plasma oscillation frequency on plasma density. The longitudinal electric field associated with the wave may be used to accelerate electrons to high energies by exciting large amplitude wave. However when the maximum amplitude of the wave is reached that plasma can sustain, the wave breaks. The phenomena of wave breaking and phase mixing have applications in plasma heating and particle acceleration. For detailed experimental investigation of these phenomena a new device, inverse mirror plasma experimental device (IMPED), has been designed and fabricated. The detailed considerations taken before designing the device, so that different aspects of these phenomena can be studied in a controlled manner, are described. Specifications of different components of the IMPED machine and their flexibility aspects in upgrading, if necessary, are discussed. Initial results meeting the prerequisite condition of the plasma for such study, such as a quiescent, collisionless and uniform plasma, are presented. The machine produces δnnoise/n <= 1%, Luniform ~ 120 cm at argon filling pressure of ~10-4 mbar and axial magnetic field of B = 1090 G.

  13. Pulse Power Supply for Plasma Dynamic Accelerator

    NASA Astrophysics Data System (ADS)

    Yang, Xuanzong; Liu, Jian; Feng, Chunhua; Wang, Long

    2008-06-01

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

  14. The Galileo plasma wave investigation

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Kurth, W. S.; Shaw, R. R.; Roux, A.; Gendrin, R.; Kennel, C. F.; Scarf, F. L.; Shawhan, S. D.

    1992-01-01

    The purpose of the Galileo plasma wave investigation is to study plasma waves and radio emissions in the magnetosphere of Jupiter. The plasma wave instrument uses an electric dipole antenna to detect electric fields, and two search coil magnetic antennas to detect magnetic fields. The frequency range covered is 5 Hz to 5.6 MHz for electric fields and 5 Hz to 160 kHz for magnetic fields. Low time-resolution survey spectrums are provided by three on-board spectrum analyzers. In the normal mode of operation the frequency resolution is about 10 percent, and the time resolution for a complete set of electric and magnetic field measurements is 37.33 s. High time-resolution spectrums are provided by a wideband receiver. The wideband receiver provides waveform measurements over bandwidths of 1, 10, and 80 kHz. Compared to previous measurements at Jupiter this instrument has several new capabilities. These new capabilities include (1) both electric and magnetic field measurements to distinguish electrostatic and electromagnetic waves, (2) direction finding measurements to determine source locations, and (3) increased bandwidth for the wideband measurements.

  15. High-Frequency Electrostatic Wave Generation and Transverse Ion Acceleration by Low Alfvenic Wave Components of BBELF Turbulence

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Khazanov, George; Mukhter, Ali

    2006-01-01

    Satellite observations in the auroral plasma have revealed that extremely low frequency (ELF) waves play a dominant role in the acceleration of electrons and ions in the auroral plasma. The electromagnetic components of the ELF (EMELF) waves are the electromagnetic ion cyclotron (EMIC) waves below the cyclotron frequency of the lightest ion species in a multi-ion plasma. Shear Alfv6n waves (SAWS) constitute the lowest frequency components of the ELF waves below the ion cyclotron frequency of the heaviest ion. The -2 mechanism for the transfer of energy from such EMELF waves to ions affecting transverse ion heating still remains a matter of debate. A very ubiquitous fe8ture of ELF waves now observed in several rocket and satellite experiments is that they occur in conjunction with high-frequency electrostatic waves. The frequency spectrum of the composite wave turbulence extends from the low frequency of the Alfvenic waves to the high frequency of proton plasma frequency and/or the lower hybrid frequency. The spectrum does not show any feature organized by the ion cyclotron frequencies and their harmonics. Such broadband waves consisting of both the EM and ES waves are now popularly referred as BBELF waves. We present results here from 2.5-D particle-in-cell simulations showing that the ES components are directly generated by cross- field plasma instabilities driven by the drifts of the ions and electrons in the EM component of the BBELF waves.

  16. New wave effects in nonstationary plasma

    SciTech Connect

    Schmit, P. F.; Fisch, N. J.

    2013-05-15

    Through particle-in-cell simulations and analytics, a host of interesting and novel wave effects in nonstationary plasma are examined. In particular, Langmuir waves serve as a model system to explore wave dynamics in plasmas undergoing compression, expansion, and charge recombination. The entire wave life-cycle is explored, including wave excitation, adiabatic evolution and action conservation, nonadiabatic evolution and resonant wave-particle effects, collisional dissipation, and potential laboratory applications of the aforementioned phenomenology.

  17. Linear and Nonlinear MHD Wave Processes in Plasmas. Final Report

    SciTech Connect

    Tataronis, J. A.

    2004-06-01

    This program treats theoretically low frequency linear and nonlinear wave processes in magnetized plasmas. A primary objective has been to evaluate the effectiveness of MHD waves to heat plasma and drive current in toroidal configurations. The research covers the following topics: (1) the existence and properties of the MHD continua in plasma equilibria without spatial symmetry; (2) low frequency nonresonant current drive and nonlinear Alfven wave effects; and (3) nonlinear electron acceleration by rf and random plasma waves. Results have contributed to the fundamental knowledge base of MHD activity in symmetric and asymmetric toroidal plasmas. Among the accomplishments of this research effort, the following are highlighted: Identification of the MHD continuum mode singularities in toroidal geometry. Derivation of a third order ordinary differential equation that governs nonlinear current drive in the singular layers of the Alfvkn continuum modes in axisymmetric toroidal geometry. Bounded solutions of this ODE implies a net average current parallel to the toroidal equilibrium magnetic field. Discovery of a new unstable continuum of the linearized MHD equation in axially periodic circular plasma cylinders with shear and incompressibility. This continuum, which we named “accumulation continuum” and which is related to ballooning modes, arises as discrete unstable eigenfrequency accumulate on the imaginary frequency axis in the limit of large mode numbers. Development of techniques to control nonlinear electron acceleration through the action of multiple coherent and random plasmas waves. Two important elements of this program aye student participation and student training in plasma theory.

  18. Laser-driven Acceleration in Clustered Plasmas

    SciTech Connect

    Gao, X.; Wang, X.; Shim, B.; Downer, M. C.

    2009-01-22

    We propose a new approach to avoid dephasing limitation of laser wakefield acceleration by manipulating the group velocity of the driving pulse using clustered plasmas. We demonstrated the control of phase velocity in clustered plasmas by third harmonic generation and frequency domain interferometry experiments. The results agree with a numerical model. Based on this model, the group velocity of the driving pulse in clustered plasmas was calculated and the result shows the group velocity can approach the speed of light c in clustered plasmas.

  19. Inductive and Electrostatic Acceleration in Relativistic Jet-Plasma Interactions

    SciTech Connect

    Ng, Johnny S.T.; Noble, Robert J.; /SLAC

    2005-07-13

    We report on the observation of rapid particle acceleration in numerical simulations of relativistic jet-plasma interactions and discuss the underlying mechanisms. The dynamics of a charge-neutral, narrow, electron-positron jet propagating through an unmagnetized electron-ion plasma was investigated using a three-dimensional, electromagnetic, particle-in-cell computer code. The interaction excited magnetic filamentation as well as electrostatic (longitudinal) plasma instabilities. In some cases, the longitudinal electric fields generated inductively and electrostatically reached the cold plasma wave-breaking limit, and the longitudinal momentum of about half the positrons increased by 50% with a maximum gain exceeding a factor of two. The results are relevant to understanding the micro-physics at the interface region of an astrophysical jet with the interstellar plasma, for example, the edge of a wide jet or the jet-termination point.

  20. Generalized acceleration theorem for spatiotemporal Bloch waves

    SciTech Connect

    Arlinghaus, Stephan; Holthaus, Martin

    2011-08-01

    A representation is put forward for wave functions of quantum particles in periodic lattice potentials subjected to homogeneous time-periodic forcing, based on an expansion with respect to Bloch-like states which embody both the spatial and the temporal periodicity. It is shown that there exists a generalization of Bloch's famous acceleration theorem which grows out of this representation and captures the effect of a weak probe force applied in addition to a strong dressing force. Taken together, these elements point at a ''dressing and probing'' strategy for coherent wave-packet manipulation, which could be implemented in present experiments with optical lattices.

  1. Plasma acceleration in the Martian magnetotail

    NASA Astrophysics Data System (ADS)

    Esteban Hernandez, Rosa; Modolo, Ronan; Leblanc, François; Chaufray, Jean-Yves; Curry, Shannon M.; Steckiewicz, Morgane; Connerney, John E. P.; McFadden, James P.; Jakosky, Bruce M.; Brain, David A.; DiBraccio, Gina A.; Romanelli, Norberto; Halekas, Jasper S.; Mitchell, David L.

    2016-04-01

    Since November 2014, the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has been collecting data from Mars's upper atmosphere and induced magnetosphere (Jakosky et al., 2015). Evidences of escaping planetary ions have been reported from earlier missions as Mars-Express (Barabash et al., 2007) and more recently from MAVEN (e.g. Dong et al., 2015, Brain et al., 2015). Our goal is to determine the acceleration mechanism responsible for the energization of planetary ions in the Martian plasma sheet. MAVEN has a full plasma package with a magnetometer and plasma particles instruments, which allow to address the question of plasma particle acceleration. According to Dubinin et al. (2011), the j x B force due to magnetic shear stresses of the draped field lines is expected to play a major role in such energization process. On MAVEN data, we have first identified and characterized current sheet crossings taking place in Mars' magnetotail and then tested the Walén relation to infer the significance of the j x B force in the particle's energization. To characterize the plasma sheet crossing we have worked with MAVEN magnetometer (MAG, Connerney et al., SSR, 2015) and mass spectrometer (STATIC, McFadden et al., SSR, 2015) data, focusing on a particular event. We have performed a minimum variance analysis, on the magnetic field observations which allows to characterize the current sheet. We present results of the Walén test and our conclusions on planetary plasma acceleration in the plasma sheet region.

  2. Pulsed Inductive Plasma Acceleration: Performance Optimization Criteria

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.

    2014-01-01

    Optimization criteria for pulsed inductive plasma acceleration are developed using an acceleration model consisting of a set of coupled circuit equations describing the time-varying current in the thruster and a one-dimensional momentum equation. The model is nondimensionalized, resulting in the identification of several scaling parameters that are varied to optimize the performance of the thruster. The analysis reveals the benefits of underdamped current waveforms and leads to a performance optimization criterion that requires the matching of the natural period of the discharge and the acceleration timescale imposed by the inertia of the working gas. In addition, the performance increases when a greater fraction of the propellant is initially located nearer to the inductive acceleration coil. While the dimensionless model uses a constant temperature formulation in calculating performance, the scaling parameters that yield the optimum performance are shown to be relatively invariant if a self-consistent description of energy in the plasma is instead used.

  3. Summary report: Working Group 2 on 'Plasma Based Acceleration Concepts'

    SciTech Connect

    Leemans, W. P.; Esarey, E.

    1999-07-12

    A summary of the talks, papers and discussion sessions presented in the Working Group on Plasma Based Acceleration Concepts is given within the context of the progress towards a 1 GeV laser driven accelerator module. The topics covered within the Working Group were self-modulated laser wakefield acceleration, standard laser wakefield acceleration, plasma beatwave acceleration, laser guiding and wake excitation in plasma channels, plasma wakefield acceleration, plasma lenses and optical injection techniques for laser wakefield accelerators. An overview will be given of the present status of experimental and theoretical progress as well as an outlook towards the future physics and technological challenges for the development of an optimized accelerator module.

  4. Some Considerations on the Pulsed Electromagnetic Acceleration of Plasma

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. F.; Markusic, T. E.; Cassibry, J. T.; Sommers, J. C.; Turchi, P. J.; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    In applying pulsed electromagnetic acceleration of plasma to space propulsion (known as pulsed plasma thrusters in the community), the mode of acceleration used has been mostly in the collisionless or near-collisionless regime. The preparation of the initial plasma is given scant attention. Collisional regime of accelerating the plasma, however, have been encountered in a variety of plasma accelerating devices. Both of these modes of acceleration are reviewed in a companion paper. In this paper, we discuss the considerations governing the controlled introduction and preparation of the initial plasma, so that the collisional mode of accelerating the plasma may be suitably enhanced.

  5. Electron acceleration by inertial Alfven waves

    SciTech Connect

    Thompson, B.J.; Lysak, R.L.

    1996-03-01

    Alfven waves reflected by the ionosphere and by inhomogeneities in the Alfven speed can develop an oscillating parallel electric field when electron inertial effects are included. These waves, which have wavelengths of the order of an Earth radius, can develop a coherent structure spanning distances of several Earth radii along geomagnetic field lines. This system has characteristic frequencies in the range of 1 Hz and can exhibit electric fields capable of accelerating electrons in several senses: via Landua resonance, bounce or transit time resonance as discussed by Andre and Eliasson or through the effective potential drop which appears when the transit time of the electrons is much smaller than the wave period, so that the electric fields appear effectively static. A time-dependent model of wave propagation is developed which represents inertial Alfven wave propagation along auroral field lines. The disturbance is modeled as it travels earthward, experiences partial reflections in regions of rapid variation, and finally reflects off a conducting ionosphere to continue propagating antiearthward. The wave experiences partial trapping by the ionospheric and the Alfven speed peaks discussed earlier by Polyakov and Rapoport and Trakhtengerts and Feldstein and later by Lysak. Results of the wave simulation and an accompanying test particle simulation are presented, which indicate that inertial Alfven waves are a possible mechanism for generating electron conic distributions and field-aligned particle precipitation. The model incorporates conservation of energy by allowing electrons to affect the wave via Landau damping, which appears to enhance the effect of the interactions which heat electron populations. 22 refs., 14 figs.

  6. Energy distribution in parallel plate plasma accelerators

    NASA Technical Reports Server (NTRS)

    Dicapua, M. S.

    1973-01-01

    A parallel plate accelerator operated in the quasi-steady regime of argon mass flow discharges permits, on account of its geometry, the appraisal of the initial ratio of energy disposition into the kinetic and thermal modes of the plasma while retaining the essential features of coaxial high power self-field MPD accelerators. The energy disposition ratio, calculated as the ratio of kinetic energy to enthalpy in the exhaust flow, shows reasonable agreement with the ratio of the induced emf in the accelerator to resistive voltage drop. Both these ratios indicate that the discharge imparts more energy to the flow by resistive heating than by direct body force acceleration. This is turn suggests that other acceleration mechanisms must be responsible for the high performance of conventional MPD arcs.

  7. Multiple pulse resonantly enhanced laser plasma wakefield acceleration

    SciTech Connect

    Corner, L.; Walczak, R.; Nevay, L. J.; Dann, S.; Hooker, S. M.; Bourgeois, N.; Cowley, J.

    2012-12-21

    We present an outline of experiments being conducted at Oxford University on multiple-pulse, resonantly-enhanced laser plasma wakefield acceleration. This method of laser plasma acceleration uses trains of optimally spaced low energy short pulses to drive plasma oscillations and may enable laser plasma accelerators to be driven by compact and efficient fibre laser sources operating at high repetition rates.

  8. Plasma cell adaptation to enhance particle acceleration

    SciTech Connect

    Ragheb, M. S.

    2008-06-15

    A plasma study is performed in order to construct a cell for plasma acceleration purpose. As well, a multicell design is introduced for the injection of beam driver application. The suggested idea is experimentally demonstrated for two plasma cell configuration. The preformed plasma is obtained by a symmetrically driven capacitive audio frequency discharge. It is featured by its moderate pressure of 0.1-0.2 Torr, low consumption power of 130 W maximum, low discharge voltage and frequency up to 950 V and 20 kHz, respectively, and high plasma density from 10{sup 11} to 10{sup 15} cm{sup -3}. The electron temperature obtained by Langmuir double probe varies from 1 up to 16 eV. It is observed that the increases of the discharge voltage and frequency enlarge the plasma parameters to their maximum values. The plasma cell filled with different gases demonstrates that the Ar and He gases manifest the highest ionization efficiency exceeding 100% at 950 V and 20 kHz. The formed plasma is cold; its density is uniform and stable along the positive column for long competitive lifetime. Showing that it follows the conditions to enhance particle acceleration and in conjunction with its periphery devices form a plasma cell that could be extended to serve this purpose. Demonstrating that an injected electron beam into the extended preformed plasma could follow, to long distance, a continuous trajectory of uniform density. Such plasma generated by H{sub 2} or Ar gases is suggested to be used, respectively, for low-density or higher density beam driver.

  9. High-gradient plasma-wakefield acceleration with two subpicosecond electron bunches.

    PubMed

    Kallos, Efthymios; Katsouleas, Tom; Kimura, Wayne D; Kusche, Karl; Muggli, Patric; Pavlishin, Igor; Pogorelsky, Igor; Stolyarov, Daniil; Yakimenko, Vitaly

    2008-02-22

    A plasma-wakefield experiment is presented where two 60 MeV subpicosecond electron bunches are sent into a plasma produced by a capillary discharge. Both bunches are shorter than the plasma wavelength, and the phase of the second bunch relative to the plasma wave is adjusted by tuning the plasma density. It is shown that the second bunch experiences a 150 MeV/m loaded accelerating gradient in the wakefield driven by the first bunch. This is the first experiment to directly demonstrate high-gradient, controlled acceleration of a short-pulse trailing electron bunch in a high-density plasma. PMID:18352561

  10. Compact Plasma Accelerator for Micropropulsion Applications

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2001-01-01

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

  11. Relativistic electron beam acceleration by Compton scattering of extraordinary waves

    SciTech Connect

    Sugaya, R.

    2006-05-15

    Relativistic transport equations, which demonstrate that relativistic and nonrelativistic particle acceleration along and across a magnetic field and the generation of an electric field transverse to the magnetic field, are induced by nonlinear wave-particle scattering (nonlinear Landau and cyclotron damping) of almost perpendicularly propagating electromagnetic waves in a relativistic magnetized plasma were derived from the relativistic Vlasov-Maxwell equations. The relativistic transport equations show that electromagnetic waves can accelerate particles in the k{sup ''} direction (k{sup ''}=k-k{sup '}). Simultaneously, an intense cross-field electric field, E{sub 0}=B{sub 0}xv{sub d}/c, is generated via the dynamo effect owing to perpendicular particle drift to satisfy the generalized Ohm's law, which means that this cross-field particle drift is identical to the ExB drift. On the basis of these equations, acceleration and heating of a relativistic electron beam due to nonlinear wave-particle scattering of electromagnetic waves in a magnetized plasma were investigated theoretically and numerically. Two electromagnetic waves interact nonlinearly with the relativistic electron beam, satisfying the resonance condition of {omega}{sub k}-{omega}{sub k{sup '}}-(k{sub perpendicular}-k{sub perpendicula=} r{sup '})v{sub d}-(k{sub parallel}-k{sub parallel}{sup '})v{sub b}{approx_equal}m{omega}{sub ce}, where v{sub b} and v{sub d} are the parallel and perpendicular velocities of the relativistic electron beam, respectively, and {omega}{sub ce} is the relativistic electron cyclotron frequency. The relativistic transport equations using the relativistic drifted Maxwellian momentum distribution function of the relativistic electron beam were derived and analyzed. It was verified numerically that extraordinary waves can accelerate the highly relativistic electron beam efficiently with {beta}m{sub e}c{sup 2} < or approx. 1 GeV, where {beta}=(1-v{sub b}{sup 2}/c{sup 2}){sup -1/2}.

  12. PRECISE CHARGE MEASUREMENT FOR LASER PLASMA ACCELERATORS

    SciTech Connect

    Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Sokollik, Thomas; Shiraishi, Satomi; Tilborg, Jeroen van; Osterhoff, Jens; Donahue, Rich; Rodgers, David; Smith, Alan; Byrne, Warren; Leemans, Wim

    2011-07-19

    Cross-calibrations of charge diagnostics are conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). Employed diagnostics are a scintillating screen, activation based measurement, and integrating current transformer. The diagnostics agreed within {+-}8 %, showing that they can provide accurate charge measurements for LPAs provided they are used properly.

  13. PARTS: (Plasma Accelerated Reusable Transport System)

    NASA Astrophysics Data System (ADS)

    Aherne, Michael; Davis, Phil; England, Matt; Gustavsson, Jake; Pankow, Steve; Sampaio, Chere; Savella, Phil

    2002-01-01

    The Plasma Accelerated Reusable Transport System (PARTS) is an unmanned cargo shuttle intended to ferry large payloads to and from Martian orbit using a highly efficient VAriable Specific Impulse Magnetoplasma Rocket (VASIMR). The design of PARTS focuses on balancing cost and minimizing transit time for a chosen payload consisting of vehicles, satellites, and other components provided by interested parties.

  14. On plasma rotation induced by waves in tokamaks

    SciTech Connect

    Guan, Xiaoyin; Dodin, I. Y.; Fisch, N. J.; Qin, Hong; Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 ; Liu, Jian

    2013-10-15

    The momentum conservation for resonant wave-particle interactions, now proven rigorously and for general settings, is applied to explain in simple terms how tokamak plasma is spun up by the wave momentum perpendicular to the dc magnetic field. The perpendicular momentum is passed through resonant particles to the dc field and, giving rise to the radial electric field, is accumulated as a Poynting flux; the bulk plasma is then accelerated up to the electric drift velocity proportional to that flux, independently of collisions. The presence of this collisionless acceleration mechanism permits varying the ratio of the average kinetic momentum absorbed by the resonant-particle and bulk distributions depending on the orientation of the wave vector. Both toroidal and poloidal forces are calculated, and a fluid model is presented that yields the plasma velocity at equilibrium.

  15. EIDOSCOPE: particle acceleration at plasma boundaries

    NASA Astrophysics Data System (ADS)

    Vaivads, A.; Andersson, G.; Bale, S. D.; Cully, C. M.; De Keyser, J.; Fujimoto, M.; Grahn, S.; Haaland, S.; Ji, H.; Khotyaintsev, Yu. V.; Lazarian, A.; Lavraud, B.; Mann, I. R.; Nakamura, R.; Nakamura, T. K. M.; Narita, Y.; Retinò, A.; Sahraoui, F.; Schekochihin, A.; Schwartz, S. J.; Shinohara, I.; Sorriso-Valvo, L.

    2012-04-01

    We describe the mission concept of how ESA can make a major contribution to the Japanese Canadian multi-spacecraft mission SCOPE by adding one cost-effective spacecraft EIDO (Electron and Ion Dynamics Observatory), which has a comprehensive and optimized plasma payload to address the physics of particle acceleration. The combined mission EIDOSCOPE will distinguish amongst and quantify the governing processes of particle acceleration at several important plasma boundaries and their associated boundary layers: collisionless shocks, plasma jet fronts, thin current sheets and turbulent boundary layers. Particle acceleration and associated cross-scale coupling is one of the key outstanding topics to be addressed in the Plasma Universe. The very important science questions that only the combined EIDOSCOPE mission will be able to tackle are: 1) Quantitatively, what are the processes and efficiencies with which both electrons and ions are selectively injected and subsequently accelerated by collisionless shocks? 2) How does small-scale electron and ion acceleration at jet fronts due to kinetic processes couple simultaneously to large scale acceleration due to fluid (MHD) mechanisms? 3) How does multi-scale coupling govern acceleration mechanisms at electron, ion and fluid scales in thin current sheets? 4) How do particle acceleration processes inside turbulent boundary layers depend on turbulence properties at ion/electron scales? EIDO particle instruments are capable of resolving full 3D particle distribution functions in both thermal and suprathermal regimes and at high enough temporal resolution to resolve the relevant scales even in very dynamic plasma processes. The EIDO spin axis is designed to be sun-pointing, allowing EIDO to carry out the most sensitive electric field measurements ever accomplished in the outer magnetosphere. Combined with a nearby SCOPE Far Daughter satellite, EIDO will form a second pair (in addition to SCOPE Mother-Near Daughter) of closely

  16. Demonstrations that the Solar Wind Is Not Accelerated by Waves

    NASA Technical Reports Server (NTRS)

    Roberts, Aaron

    2008-01-01

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

  17. Geotail MCA Plasma Wave Investigation Data Analysis

    NASA Technical Reports Server (NTRS)

    Anderson, Roger R.

    1997-01-01

    The primary goals of the International Solar Terrestrial Physics/Global Geospace Science (ISTP/GGS) program are identifying, studying, and understanding the source, movement, and dissipation of plasma mass, momentum, and energy between the Sun and the Earth. The GEOTAIL spacecraft was built by the Japanese Institute of Space and Astronautical Science and has provided extensive measurements of entry, storage, acceleration, and transport in the geomagnetic tail and throughout the Earth's outer magnetosphere. GEOTAIL was launched on July 24, 1992, and began its scientific mission with eighteen extensions into the deep-tail region with apogees ranging from around 60 R(sub e) to more than 208 R(sub e) in the period up to late 1994. Due to the nature of the GEOTAIL trajectory which kept the spacecraft passing into the deep tail, GEOTAIL also made 'magnetopause skimming passes' which allowed measurements in the outer magnetosphere, magnetopause, magnetosheath, bow shock, and upstream solar wind regions as well as in the lobe, magnetosheath, boundary layers, and central plasma sheet regions of the tail. In late 1994, after spending nearly 30 months primarily traversing the deep tail region, GEOTAIL began its near-Earth phase. Perigee was reduced to 10 R(sub e) and apogee first to 50 R(sub e) and finally to 30 R(sub e) in early 1995. This orbit provides many more opportunities for GEOTAIL to explore the upstream solar wind, bow shock, magnetosheath, magnetopause, and outer magnetosphere as well as the near-Earth tail regions. The WIND spacecraft was launched on November 1, 1994 and the POLAR spacecraft was launched on February 24, 1996. These successful launches have dramatically increased the opportunities for GEOTAIL and the GGS spacecraft to be used to conduct the global research for which the ISTP program was designed. The measurement and study of plasma waves have made and will continue to make important contributions to reaching the ISTP/GGS goals and solving the

  18. Magnetically accelerated foils for shock wave experiments

    NASA Astrophysics Data System (ADS)

    Neff, Stephan; Ford, Jessica; Martinez, David; Plechaty, Christopher; Wright, Sandra; Presura, Radu

    2008-04-01

    The interaction of shock waves with inhomogeneous media is important in many astrophysical problems, e.g. the role of shock compression in star formation. Using scaled experiments with inhomogeneous foam targets makes it possible to study relevant physics in the laboratory, to better understand the mechanisms of shock compression and to benchmark astrophysical simulation codes. Experiments with flyer-generated shock waves have been performed on the Z machine in Sandia. The Zebra accelerator at the Nevada Terawatt Facility (NTF) allows for complementary experiments with high repetition rate. First experiments on Zebra demonstrated flyer acceleration to sufficiently high velocities (around 2 km/s) and that laser shadowgraphy can image sound fronts in transparent targets. Based on this, we designed an optimized setup to improve the flyer parameters (higher speed and mass) to create shock waves in transparent media. Once x-ray backlighting with the Leopard laser at NTF is operational, we will switch to foam targets with parameters relevant for laboratory astrophysics.

  19. Optimal Distributed Excitation of Surface Wave Plasmas

    NASA Astrophysics Data System (ADS)

    Bowers, K. J.; Birdsall, C. K.

    2000-10-01

    Surface wave sustained plasmas are an emerging technology for next generation sources for material processing. There is promise of producing high density, uniform sheath plasmas at low neutral pressures over large target surface areas. Such plasmas are being produced by distributed arrays of slot antennas by numerous groups. However, work remains to obtain the optimal surface wave frequency and wave vector for sustaining a plasma. In this work, the optimal phase shift between slot antennas in a surface wave plasma is being sought using 2d3v PIC-MCC simulation. A long plasma loaded planar metal waveguide with a distributed exciting structure along one wall is modeled in these simulations. Of particular interest is the wave-particle interaction of electrons in the high energy tail of the velocity distribution (responsible for ionization in low pressure discharges) with driven low phase velocity (v << c) surface waves.

  20. Developments in Laser and Plasma-Based Accelerators

    NASA Astrophysics Data System (ADS)

    Downer, Michael

    2001-04-01

    The explosive growth of multiterawatt laser technology combined with the increasing size and cost of conventional RF particle accelerators has driven intense research into more compact laser-driven and/or plasma based acceleration concepts. Although schemes for direct laser acceleration without plasmas or, conversely, plasma acceleration without lasers have been studied, the greatest recent progress has been made with concepts that combine lasers and plasmas [1]. Tajima and Dawson [2] proposed in 1979 that a sufficiently intense single laser pulse of duration t ω_p-1, or a pair of laser pulses with Δω ω_p, could be efficiently drive a longitudinal electron plasma wave with phase velocity approaching c via the ponderomotive force. Charged particles that "surf" such waves experience accelerating gradients (E 10^9 V/cm) as much as a thousand times greater than conventional RF accelerators. Numerous experiments have now demonstrated acceleration of up to 10^9 electrons per laser pulse to energies exceeding 100 MeV, with wide energy spread, but competitive beam emittance. Such sources have proven useful for nuclear activation analysis in their current form. However for such accelerators to be useful to a wider community, including high energy physics, key challenges must be addressed. These include: 1) Guiding terawatt laser pulses. Achieving useful laser intensities requires focusing, thus limiting interaction length to < 1 mm, whereas interaction lengths of several cm are needed to use laser energy efficiently and reach GeV acceleration in a single stage. Several groups are now developing high-throughput plasma "fibers" that have supported peak powers near a terawatt over > 1 cm without distortion [3]. 2) Phased injection. Since plasma waves with useful gradients have wavelengths of micron dimensions, charged particles must be injected with unprecedented spatial and temporal precision to achieve a monochromatic output beam. Several groups are developing new laser

  1. Plasma Wakefield Acceleration and FACET - Facilities for Accelerator Science and Experimental Test Beams at SLAC

    ScienceCinema

    Andrei Seryi

    2010-01-08

    Plasma wakefield acceleration is one of the most promising approaches to advancing accelerator technology. This approach offers a potential 1,000-fold or more increase in acceleration over a given distance, compared to existing accelerators.  FACET, enabled by the Recovery Act funds, will study plasma acceleration, using short, intense pulses of electrons and positrons. In this lecture, the physics of plasma acceleration and features of FACET will be presented.  

  2. Plasma Wakefield Acceleration and FACET - Facilities for Accelerator Science and Experimental Test Beams at SLAC

    SciTech Connect

    Andrei Seryi

    2009-09-09

    Plasma wakefield acceleration is one of the most promising approaches to advancing accelerator technology. This approach offers a potential 1,000-fold or more increase in acceleration over a given distance, compared to existing accelerators.  FACET, enabled by the Recovery Act funds, will study plasma acceleration, using short, intense pulses of electrons and positrons. In this lecture, the physics of plasma acceleration and features of FACET will be presented.  

  3. Laser plasma acceleration of electrons: Towards the production of monoenergetic beams

    SciTech Connect

    Krushelnick, K.; Najmudin, Z.; Mangles, S.P.D.; Thomas, A.G.R.; Wei, M.S.; Walton, B.; Gopal, A.; Clark, E.L.; Dangor, A.E.; Fritzler, S.; Murphy, C.D.; Norreys, P.A.; Mori, W.B.; Gallacher, J.; Jaroszynski, D.; Viskup, R.

    2005-05-15

    The interaction of high intensity laser pulses with underdense plasma is investigated experimentally using a range of laser parameters and energetic electron production mechanisms are compared. It is clear that the physics of these interactions changes significantly depending not only on the interaction intensity but also on the laser pulse length. For high intensity laser interactions in the picosecond pulse duration regime the production of energetic electrons is highly correlated with the production of plasma waves. However as intensities are increased the peak electron acceleration increases beyond that which can be produced from single stage plasma wave acceleration and direct laser acceleration mechanisms must be invoked. If, alternatively, the pulse length is reduced such that it approaches the plasma period of a relativistic electron plasma wave, high power interactions can be shown to enable the generation of quasimonoenergetic beams of relativistic electrons.

  4. Dichromatic Langmuir waves in degenerate quantum plasma

    SciTech Connect

    Dubinov, A. E. Kitayev, I. N.

    2015-06-15

    Langmuir waves in fully degenerate quantum plasma are considered. It is shown that, in the linear approximation, Langmuir waves are always dichromatic. The low-frequency component of the waves corresponds to classical Langmuir waves, while the high-frequency component, to free-electron quantum oscillations. The nonlinear problem on the profile of dichromatic Langmuir waves is solved. Solutions in the form of a superposition of waves and in the form of beatings of its components are obtained.

  5. Electron trapping and acceleration by kinetic Alfvén waves in solar flares

    NASA Astrophysics Data System (ADS)

    Artemyev, A. V.; Zimovets, I. V.; Rankin, R.

    2016-05-01

    Context. Theoretical models and spacecraft observations of solar flares highlight the role of wave-particle interaction for non-local electron acceleration. In one scenario, the acceleration of a large electron population up to high energies is due to the transport of electromagnetic energy from the loop-top region down to the footpoints, which is then followed by the energy being released in dense plasma in the lower atmosphere. Aims: We consider one particular mechanism of non-linear electron acceleration by kinetic Alfvén waves. Here, waves are generated by plasma flows in the energy release region near the loop top. We estimate the efficiency of this mechanism and the energies of accelerated electrons. Methods: We use analytical estimates and test-particle modelling to investigate the effects of electron trapping and acceleration by kinetic Alfvén waves in the inhomogeneous plasma of the solar corona. Results: We demonstrate that, for realistic wave amplitudes, electrons can be accelerated up to 10-1000 keV during their propagation along magnetic field lines. Here the electric field that is parallel to the direction of the background magnetic field is about 10 to 103 times the amplitude of the Dreicer electric field. The acceleration mechanism strongly depends on electron scattering which is due to collisions that only take place near the loop footpoints. Conclusions: The non-linear wave-particle interaction can play an important role in the generation of relativistic electrons within flare loops. Electron trapping and coherent acceleration by kinetic Alfvén waves represent the energy cascade from large-scale plasma flows that originate at the loop-top region down to the electron scale. The non-diffusive character of the non-linear electron acceleration may be responsible for the fast generation of high-energy particles.

  6. Advanced concepts for acceleration

    SciTech Connect

    Keefe, D.

    1986-07-01

    Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations. (LEW)

  7. Strongly nonlinear magnetosonic waves and ion acceleration

    SciTech Connect

    Rau, B.; Tajima, T.

    1997-11-01

    The electromagnetic fields associated with a nonlinear compressional Alfven wave propagating perpendicular to an external magnetic field of arbitrary strength are derived. For the strongly magnetized and high phase velocity case relevant for ion acceleration to high energies, we show that the electric field increases proportionally only to the external magnetic field O (B{sub ext}[in T] MV/cm) and the electrostatic potential increases with the square root of the ion-to-electron mass ratio {radical}M{sub i}/m{sub e}.

  8. Magnetically accelerated foils for shock wave experiments

    NASA Astrophysics Data System (ADS)

    Neff, S.; Ford, J.; Wright, S.; Martinez, D.; Plechaty, C.; Presura, R.

    2009-08-01

    Many astrophysical phenomena involve the interaction of a shock wave with an inhomogeneous background medium. Using scaled experiments with inhomogeneous foam targets makes it possible to study relevant physics in the laboratory to better understand the mechanisms of shock compression and to benchmark astrophysical simulation codes. First experiments on Zebra at the Nevada Terawatt Facility (NTF) have demonstrated flyer acceleration to sufficiently high velocities (up to 5 km/s) and that laser shadowgraphy can image sound fronts in transparent targets. Based on this, we designed an optimized setup to improve the flyer parameters (higher speed and mass) to create shock waves in transparent media. Once x-ray backlighting with the Leopard laser at NTF is operational, we will switch to foam targets with parameters relevant for laboratory astrophysics.

  9. Plasma Waves in the Magnetosheath of Venus

    NASA Technical Reports Server (NTRS)

    Strangeway, Robert J.

    1996-01-01

    Research supported by this grant is divided into three basic topics of investigation. These are: (1) Plasma waves in the Venus magnetosheath, (2) Plasma waves in the Venus foreshock and solar wind, (3) plasma waves in the Venus nightside ionosphere and ionotail. The main issues addressed in the first area - Plasma waves in the Venus magnetosheath - dealt with the wave modes observed in the magnetosheath and upper ionosphere, and whether these waves are a significant source of heating for the topside ionosphere. The source of the waves was also investigated. In the second area - Plasma waves in the Venus foreshock and solar wind, we carried out some research on waves observed upstream of the planetary bow shock known as the foreshock. The foreshock and bow shock modify the ambient magnetic field and plasma, and need to be understood if we are to understand the magnetosheath. Although most of the research was directed to wave observations on the dayside of the planet, in the last of the three basic areas studied, we also analyzed data from the nightside. The plasma waves observed by the Pioneer Venus Orbiter on the nightside continue to be of considerable interest since they have been cited as evidence for lightning on Venus.

  10. Plasma acceleration above martian magnetic anomalies.

    PubMed

    Lundin, R; Winningham, D; Barabash, S; Frahm, R; Holmström, M; Sauvaud, J-A; Fedorov, A; Asamura, K; Coates, A J; Soobiah, Y; Hsieh, K C; Grande, M; Koskinen, H; Kallio, E; Kozyra, J; Woch, J; Fraenz, M; Brain, D; Luhmann, J; McKenna-Lawler, S; Orsini, R S; Brandt, P; Wurz, P

    2006-02-17

    Auroras are caused by accelerated charged particles precipitating along magnetic field lines into a planetary atmosphere, the auroral brightness being roughly proportional to the precipitating particle energy flux. The Analyzer of Space Plasma and Energetic Atoms experiment on the Mars Express spacecraft has made a detailed study of acceleration processes on the nightside of Mars. We observed accelerated electrons and ions in the deep nightside high-altitude region of Mars that map geographically to interface/cleft regions associated with martian crustal magnetization regions. By integrating electron and ion acceleration energy down to the upper atmosphere, we saw energy fluxes in the range of 1 to 50 milliwatts per square meter per second. These conditions are similar to those producing bright discrete auroras above Earth. Discrete auroras at Mars are therefore expected to be associated with plasma acceleration in diverging magnetic flux tubes above crustal magnetization regions, the auroras being distributed geographically in a complex pattern by the many multipole magnetic field lines extending into space. PMID:16484488

  11. Staging of laser-plasma accelerators

    NASA Astrophysics Data System (ADS)

    Steinke, S.; van Tilborg, J.; Benedetti, C.; Geddes, C. G. R.; Daniels, J.; Swanson, K. K.; Gonsalves, A. J.; Nakamura, K.; Shaw, B. H.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2016-05-01

    We present results of an experiment where two laser-plasma-accelerator stages are coupled at a short distance by a plasma mirror. Stable electron beams from the first stage were used to longitudinally probe the dark-current-free, quasi-linear wakefield excited by the laser of the second stage. Changing the arrival time of the electron beam with respect to the second stage laser pulse allowed reconstruction of the temporal wakefield structure, determination of the plasma density, and inference of the length of the electron beam. The first stage electron beam could be focused by an active plasma lens to a spot size smaller than the transverse wake size at the entrance of the second stage. This permitted electron beam trapping, verified by a 100 MeV energy gain.

  12. Electron acceleration by Z-mode and whistler-mode waves

    SciTech Connect

    Lee, K. H.; Omura, Y.; Lee, L. C.

    2013-11-15

    We carried out a series of particle simulations to study electron acceleration by Z-mode and whistler-mode waves generated by an electron ring distribution. The electron ring distribution leads to excitations of X-mode waves mainly in the perpendicular direction, Z-mode waves in the perpendicular and parallel directions, and whistler-mode waves mainly in the parallel direction. The parallel Z- and whistler-mode waves can lead to an effective acceleration of ring electrons. The electron acceleration is mainly determined by the wave amplitude and phase velocity, which in turn is affected by the ratio of electron plasma to cyclotron frequencies. For the initial kinetic energy ranging from 100 to 500 keV, the peak energy of the accelerated electrons is found to reach 2–8 times the initial kinetic energy. We further study the acceleration process by test-particle calculations in which electrons interact with one, two, or four waves. The electron trajectories in the one-wave case are simple diffusion curves. In the multi-wave cases, electrons are accelerated simultaneously by counter-propagating waves and can have a higher final energy.

  13. Electron acceleration by Z-mode and whistler-mode waves

    NASA Astrophysics Data System (ADS)

    Lee, K. H.; Omura, Y.; Lee, L. C.

    2013-11-01

    We carried out a series of particle simulations to study electron acceleration by Z-mode and whistler-mode waves generated by an electron ring distribution. The electron ring distribution leads to excitations of X-mode waves mainly in the perpendicular direction, Z-mode waves in the perpendicular and parallel directions, and whistler-mode waves mainly in the parallel direction. The parallel Z- and whistler-mode waves can lead to an effective acceleration of ring electrons. The electron acceleration is mainly determined by the wave amplitude and phase velocity, which in turn is affected by the ratio of electron plasma to cyclotron frequencies. For the initial kinetic energy ranging from 100 to 500 keV, the peak energy of the accelerated electrons is found to reach 2-8 times the initial kinetic energy. We further study the acceleration process by test-particle calculations in which electrons interact with one, two, or four waves. The electron trajectories in the one-wave case are simple diffusion curves. In the multi-wave cases, electrons are accelerated simultaneously by counter-propagating waves and can have a higher final energy.

  14. Low-Frequency Waves in Space Plasmas

    NASA Astrophysics Data System (ADS)

    Keiling, Andreas; Lee, Dong-Hun; Nakariakov, Valery

    2016-02-01

    Low-frequency waves in space plasmas have been studied for several decades, and our knowledge gain has been incremental with several paradigm-changing leaps forward. In our solar system, such waves occur in the ionospheres and magnetospheres of planets, and around our Moon. They occur in the solar wind, and more recently, they have been confirmed in the Sun's atmosphere as well. The goal of wave research is to understand their generation, their propagation, and their interaction with the surrounding plasma. Low-frequency Waves in Space Plasmas presents a concise and authoritative up-to-date look on where wave research stands: What have we learned in the last decade? What are unanswered questions? While in the past waves in different astrophysical plasmas have been largely treated in separate books, the unique feature of this monograph is that it covers waves in many plasma regions, including: Waves in geospace, including ionosphere and magnetosphere Waves in planetary magnetospheres Waves at the Moon Waves in the solar wind Waves in the solar atmosphere Because of the breadth of topics covered, this volume should appeal to a broad community of space scientists and students, and it should also be of interest to astronomers/astrophysicists who are studying space plasmas beyond our Solar System.

  15. Pulsed Electromagnetic Acceleration of Plasma: A Review

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

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

    SciTech Connect

    Plateau, Guillaume; Matlis, Nicholas; Geddes, Cameron; Gonsalves, Anthony; Shiraishi, Satomi; Lin, Chen; van Mourik, Reinier; Leemans, Wim

    2010-02-20

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

  17. LASER-PLASMA-ACCELERATOR-BASED GAMMA GAMMA COLLIDERS

    SciTech Connect

    Schroeder, C. B.; Esarey, E.; Toth, Cs.; Geddes, C. G. R.; Leemans, W. P.

    2009-05-04

    Design considerations for a next-generation linear collider based on laser-plasma-accelerators are discussed, and a laser-plasma-accelerator-based gamma-gamma collider is considered. An example of the parameters for a 0.5 TeV laser-plasma-accelerator gamma gamma collider is presented.

  18. High latitude electromagnetic plasma wave emissions

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.

    1983-01-01

    The principal types of electromagnetic plasma wave emission produced in the high latitude auroral regions are reviewed. Three types of radiation are described: auroral kilometric radiation, auroral hiss, and Z mode radiation. Auroral kilometric radiation is a very intense radio emission generated in the free space R-X mode by electrons associated with the formation of discrete auroral arcs in the local evening. Theories suggest that this radiation is an electron cyclotron resonance instability driven by an enhanced loss cone in the auroral acceleration region at altitudes of about 1 to 2 R sub E. Auroral hiss is a somewhat weaker whistler mode emission generated by low energy (100 eV to 10 keV) auroral electrons. The auroral hiss usually has a V shaped frequency time spectrum caused by a freqency dependent beaming of the whistler mode into a conical beam directed upward or downward along the magnetic field.

  19. Laser-driven electron acceleration in an inhomogeneous plasma channel

    SciTech Connect

    Zhang, Rong; Cheng, Li-Hong; Xue, Ju-Kui

    2015-12-15

    We study the laser-driven electron acceleration in a transversely inhomogeneous plasma channel. We find that, in inhomogeneous plasma channel, the developing of instability for electron acceleration and the electron energy gain can be controlled by adjusting the laser polarization angle and inhomogeneity of plasma channel. That is, we can short the accelerating length and enhance the energy gain in inhomogeneous plasma channel by adjusting the laser polarization angle and inhomogeneity of the plasma channel.

  20. Electromagnetic waves in a strong Schwarzschild plasma

    SciTech Connect

    Daniel, J.; Tajima, T.

    1996-11-01

    The physics of high frequency electromagnetic waves in a general relativistic plasma with the Schwarzschild metric is studied. Based on the 3 + 1 formalism, we conformalize Maxwell`s equations. The derived dispersion relations for waves in the plasma contain the lapse function in the plasma parameters such as in the plasma frequency and cyclotron frequency, but otherwise look {open_quotes}flat.{close_quotes} Because of this property this formulation is ideal for nonlinear self-consistent particle (PIC) simulation. Some of the physical consequences arising from the general relativistic lapse function as well as from the effects specific to the plasma background distribution (such as density and magnetic field) give rise to nonuniform wave equations and their associated phenomena, such as wave resonance, cutoff, and mode-conversion. These phenomena are expected to characterize the spectroscopy of radiation emitted by the plasma around the black hole. PIC simulation results of electron-positron plasma are also presented.

  1. Millimeter-wave generation via plasma three-wave mixing

    NASA Astrophysics Data System (ADS)

    Schumacher, Robert W.; Santoru, Joseph

    1988-06-01

    Plasma three-wave mixing is a collective phenomena whereby electron-beam-driven electron plasma waves (EPWs) are nonlinearly coupled to an electromagnetic (EM) radiation field. The basic physics of three-wave mixing is investigated in the mm-wave regime and the scaling of mm-wave characteristics established with beam and plasma parameters. Our approach is to employ two counterinjected electron beams in a plasma-loaded circular waveguide to drive counterstreaming EPWs. The nonlinear coupling of these waves generates an EM waveguide mode which oscillates at twice the plasma frequency and is coupled out into rectangular waveguides. Independent control of the waveguide plasma, beam voltage, and beam current is exercised to allow a careful parametric investigation of beam transport, EPW dynamics and three-wave-mixing physics. The beam-plasma experiment, which employs a wire-anode discharge to generate high-density plasma in a 3.8 cm-diameter waveguide, has been used to generate radiation at frequencies from 7 to 60 GHz. Two cold-cathode, secondary-emission electron guns are used to excite the EPWs. Output radiation is observed only when both beams are injected, and the total beam current exceeds a threshold value of 3 A. The threshold is related to the self-magnetic pinch of each beam which increases the beam density and growth rate of the EPWs.

  2. Shock-Wave Acceleration of Protons on OMEGA EP

    NASA Astrophysics Data System (ADS)

    Haberberger, D.; Froula, D. H.; Pak, A.; Link, A.; Patel, P.; Fiuza, F.; Tochitsky, S.; Joshi, C.

    2015-11-01

    Recent experimental results using shock-wave acceleration (SWA) driven by a CO2 laser in a H2 gas-jet plasma have shown the possibility of producing proton beams with energy spreads <10% and with energies of up to 20 MeV using a modest peak laser power of 4 TW. Here we propose the investigation of the scaling of the SWA mechanism to higher laser powers using the 1- μm OMEGA EP Laser System at the Laboratory for Laser Energetics. The required tailored plasma profile is created by expanding a CH target using the thermal x-ray emission from a UV ablated material. The desired characteristics optimal for SWA are met: (a) peak plasma density is overcritical for the 1- μm main pulse and (b) the plasma profile exponentially decays over a long scale length on the rear side. Results will be shown using a 4 ω probe to experimentally characterize the plasma density profile. Scaling from simulations of the SWA mechanism shows that ion energies in the range of 100 MeV/amu are achievable with a focused a0 of 5 from the OMEGA EP Laser System. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  3. Fundamental plasma emission involving ion sound waves

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1987-01-01

    The theory for fundamental plasma emission by the three-wave processes L + or - S to T (where L, S and T denote Langmuir, ion sound and transverse waves, respectively) is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes are identified. In addition the rates, path-integrated wave temperatures, and limits on the brightness temperature of the radiation are derived.

  4. Magnetic field and plasma wave observations in a plasma cloud at Venus

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Luhmann, J. G.; Elphic, R. C.; Scarf, F. L.; Brace, L. H.

    1982-01-01

    Pioneer Venus magnetic field and plasma wave data are examined in a particularly clear example of a plasma cloud above the Venus ionosphere. The magnetic configuration is suggestive of acceleration of the plasma cloud by magnetic tension. If the plasma is at rest at the subsolar point, it could be accelerated to approximately 90 km/sec by the observed stress at the location of the measurement. This far exceeds the escape velocity and suggests that plasma clouds do form a significant loss mechanism for the Venus ionosphere but does not necessarily indicate that the plasma cloud is detached from the ionosphere proper. The plasma cloud is accompanied by strong plasma wave activity and is significantly hotter than the ionospheric plasma encountered later on the same pass. A loss rate of the order of 2 x 10 to the 25th ions/sec is estimated during this event. The geometry suggested by these observations is one of a ridge of dense cold plasma starting in the subsolar regions and flowing over the poles of the planet. Thus, these plasma clouds may be the planetary analog of cometary tail rays.

  5. Wave-breaking limits for nonquasistatic oscillations in a warm one-dimensional electron plasma.

    PubMed

    Trines, R M G M

    2009-05-01

    In this work, wave breaking for general non-quasi-static oscillations in warm plasma is investigated using Lagrangian methods. In particular, the effects of secular behavior on wave-breaking limits are explored, and it is shown that thermal effects can sometimes prevent wave breaking by curbing secular behavior. The oscillation equations for fully relativistic warm plasma are cast into Lagrangian form, and wave-breaking limits are derived for waves in warm plasma having nonconstant density. These results have important applications in electron acceleration schemes that employ a wakefield or a slow beat wave propagating down a density gradient. PMID:19518575

  6. Superconducting travelling wave ring with high gradient accelerating section

    SciTech Connect

    Avrakhov, P.; Solyak, N.; /Fermilab

    2007-06-01

    Use of a superconducting traveling wave accelerating (STWA) structure instead of a standing wave cavity has major advantages in increasing the accelerating gradient in the ILC. In contrast with standing wave cavity STWA requires feedback loop, which sends wave from the structure output to input, making a superconducting traveling wave ring (STWR). One or few input couplers need to excite STWR and compensate power dissipations due to beam loading. To control traveling wave regime in the structure two independent knobs can be used for tuning both resonant ring frequency and backward wave. We discuss two variants of the STWR with one and two feed couplers.

  7. Ion plasma wave and its instability in interpenetrating plasmas

    SciTech Connect

    Vranjes, J.; Kono, M.

    2014-04-15

    Some essential features of the ion plasma wave in both kinetic and fluid descriptions are presented. The wave develops at wavelengths shorter than the electron Debye radius. Thermal motion of electrons at this scale is such that they overshoot the electrostatic potential perturbation caused by ion bunching, which consequently propagates as an unshielded wave, completely unaffected by electron dynamics. So in the simplest fluid description, the electrons can be taken as a fixed background. However, in the presence of magnetic field and for the electron gyro-radius shorter than the Debye radius, electrons can participate in the wave and can increase its damping rate. This is determined by the ratio of the electron gyro-radius and the Debye radius. In interpenetrating plasmas (when one plasma drifts through another), the ion plasma wave can easily become growing and this growth rate is quantitatively presented for the case of an argon plasma.

  8. Acceleration and Focusing of Plasma Flows

    NASA Astrophysics Data System (ADS)

    Griswold, Martin E.

    The acceleration of flowing plasmas is a fundamental problem that is useful in a wide variety of technological applications. We consider the problem from the perspective of plasma propulsion. Gridded ion thrusters and Hall thrusters are the most commonly used devices to create flowing plasma for space propulsion, but both suffer from fundamental limitations. Gridded ion sources create good quality beams in terms of energy spread and spatial divergence, but the Child-Langmuir law in the non-neutral acceleration region limits the maximum achievable current density. Hall thrusters avoid this limitation by accelerating ions in quasi-neutral plasma but, as a result, produce plumes with high spatial divergence and large energy spread. In addition the more complicated magnetized plasma in the Hall Thruster produces oscillations that can reduce the efficiency of the thruster by increasing electron transport to the anode. We present investigations of three techniques to address the fundamental limitations on the performance of each thruster. First, we propose a method to increase the time-averaged current density (and thus thrust density) produced by a gridded ion source above the Child-Langmuir limit by introducing time-varying boundary conditions. Next, we use an electrostatic plasma lens to focus the Hall thruster plume, and finally we develop a technique to suppress a prominent oscillation that degrades the performance of Hall thrusters. The technique to loosen the constraints on current density from gridded ion thrusters actually applies much more broadly to any space charge limited flow. We investigate the technique with a numerical simulation and by proving a theoretical upper bound. While we ultimately conclude that the approach is not suitable for space propulsion, our results proved useful in another area, providing a benchmark for research into the spontaneously time-dependent current that arises in microdiodes. Next, we experimentally demonstrate a novel

  9. Alfven Wave Propagation in Inhomogeneous Plasmas

    NASA Astrophysics Data System (ADS)

    Sears, Stephanie

    Damping of Alfven waves is one of the most likely mechanisms for ion heating in the solar corona. Density gradients have significant but poorly-understood effects on energy transfer and Alfven wave propagation in partially ionized plasmas, such as those found in the solar chromosphere. Reflection of Alfven waves at density and magnetic field gradients can give rise to turbulence which sustains particle heating. The density profile in the Hot hELIcon eXperiment (HELIX) varies strongly with radius, giving access to a wide range of Alfven dynamics across the plasma column and providing an ideal environment to observe Alfven wave-driven particle heating. A new internal wave-launching antenna, situated at the edge of the high-density core and the density-gradient region of HELIX has been used to excite low-frequency waves in argon plasma. The propagation behavior of the launched waves was measured with a small-scale (smaller than the ion gyroradius) magnetic sense coil at multiple radial locations across the plasma column (from the high-density core through the density gradient region). Time-resolved laser induced fluorescence (LIF) and Langmuir probe measurements also yield insight into the plasma response to the perturbation. This dissertation presents cross-spectral and wavelet analysis of low-frequency waves in a helicon plasma with a strong density gradient. Building on the work of Houshmandyar, shear Alfven waves were launched in a helicon plasma source with a strong density gradient. Alfven wave turbulence is suggested from phase angle and wavelet analysis of magnetic sense coil probe measurements. The perturbation wavelength derived from phase angle measurements is consistent with predictions from the full Alfven wave dispersion relation (taking electron Landua damping, electron-ion collisions, and finite frequency effects into account). Time-resolved LIF measurements across the plasma column suggest ion heating where the turbulence is strongest. Time

  10. Electrostatic Wave Generation and Transverse Ion Acceleration by Alfvenic Wave Components of BBELF Turbulence

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Khazanov, George; Mukhter, Ali

    2007-01-01

    We present results here from 2.5-D particle-in-cell simulations showing that the electrostatic (ES) components of broadband extremely low frequency (BBELF) waves could possibly be generated by cross-field plasma instabilities driven by the relative drifts between the heavy and light ion species in the electromagnetic (EM) Alfvenic component of the BBELF waves in a multi-ion plasma. The ES components consist of ion cyclotron as well as lower hybrid modes. We also demonstrate that the ES wave generation is directly involved in the transverse acceleration of ions (TAI) as commonly measured with the BBELF wave events. The heating is affected by ion cyclotron resonance in the cyclotron modes and Landau resonance in the lower hybrid waves. In the simulation we drive the plasma by the transverse electric field, E(sub y), of the EM waves; the frequency of E(sub y), omega(sub d), is varied from a frequency below the heavy ion cyclotron frequency, OMEGA(sub h), to below the light ion cyclotron frequency, OMEGA(sub i). We have also performed simulations for E(sub y) having a continuous spectrum given by a power law, namely, |Ey| approx. omega(sub d) (exp -alpha), where the exponent alpha = _, 1, and 2 in three different simulations. The driving electric field generates polarization and ExB drifts of the ions and electrons. When the interspecies relative drifts are sufficiently large, they drive electrostatic waves, which cause perpendicular heating of both light and heavy ions. The transverse ion heating found here is discussed in relation to observations from Cluster, FAST and Freja.

  11. EDITORIAL: Laser and Plasma Accelerators Workshop, Kardamyli, Greece, 2009 Laser and Plasma Accelerators Workshop, Kardamyli, Greece, 2009

    NASA Astrophysics Data System (ADS)

    Bingham, Bob; Muggli, Patric

    2011-01-01

    -resolved radiobiology or chemistry. Such laser-generated beams will form the basis of the fifth generation light sources and will be compact versions of the much more expensive fourth generation XFEL, such as LCLS light sources. Laser-driven ion acceleration is also making rapid headway; one of the goals in these experiments is to produce protons and carbon ions of hundreds of MeV for oncology. These experiments are carried out using solid-target-laser interactions. There is still a number of issues to be resolved in these experiments including the origin of light ions. The paper by Willingale et al addresses this issue and demonstrates that deuteron ions originating from the front surface can gain comparable energies as those from the rear surface. Furthermore, from two-dimensional simulations they show that a proton-rich contamination layer over the surface is detrimental to deuteron ion acceleration from the rear surface but not detrimental to the front surface acceleration mechanism. Studies of different laser polarizations on ion acceleration at the rear surface were reported by Antici et al. It was shown that no real enhancement using a particular polarization was found. At higher radiation intensities, especially with the multi-petawatt lasers being planned, radiation reaction becomes important. This was reported by Chen et al who found that radiation reaction effects on ion acceleration in laser-foil interactions impeded the backward moving electrons, which enhanced the ion acceleration. An interesting new development is the use of ultra-relativistic proton beams to drive plasma wakefields. This is similar to the SLAC electron-beam-driven wakefields. However, unlike the SLAC electron beam, which is of the order of 30 fs long and matches the period of the plasma wave necessary to create the blowout or bubble regime, the ion beam is very much longer. To create shorter ion beams a magnetic compression scheme is investigated in the paper by Caldwell et al, and results for proton

  12. Particle Acceleration in SN1006 Shock Waves

    NASA Technical Reports Server (NTRS)

    Raymond, John C.; Ghavamian, Parviz; Sonneborn, George (Technical Monitor)

    2003-01-01

    This grant is for the analysis of FUSE observations of particle acceleration in supernova remnant SN1006 shock waves. We have performed quick look analysis of the data, but because the source is faint and because the O VI emission lines on SN1006 are extremely broad, extreme care is needed for background subtraction and profile fitting. Moreover, the bulk of the analysis in will consist of model calculations. The Ly beta and O VI lines are clearly detected at the position in the NW filament of SN1006, but not in the NE position where non-thermal X-rays are strong. The lack of O VI emission in the NE places an upper limit on the pre-shock density there.

  13. MHD plasma acceleration in plasma thrusters: a variational approach

    SciTech Connect

    Andreussi, T.; Pegoraro, F.

    2010-12-14

    A Hamiltonian formulation of the MHD plasma flow equations in terms of noncanonical variables is briefly discussed for the case of stationary axisymmetric configurations. This formulation makes it possible to cast these flow equations in a variational form with mixed (closed and/or open) boundary conditions. Within this framework the modelling of the acceleration channel of an applied-field Magneto-Plasma-Dynamic (MPD) thruster for space propulsion is discussed and shown to provide general relationships between the flow features and the thruster performance.

  14. Excitation of Plasma Waves in Aurora by Electron Beams

    NASA Technical Reports Server (NTRS)

    daSilva, C. E.; Vinas, A. F.; deAssis, A. S.; deAzevedo, C. A.

    1996-01-01

    In this paper, we study numerically the excitation of plasma waves by electron beams, in the auroral region above 2000 km of altitude. We have solved the fully kinetic dispersion relation, using numerical method and found the real frequency and the growth rate of the plasma wave modes. We have examined the instability properties of low-frequency waves such as the Electromagnetic Ion Cyclotron (EMIC) wave as well as Lower-Hybrid (LH) wave in the range of high-frequency. In all cases, the source of free energy are electron beams propagating parallel to the geomagnetic field. We present some features of the growth rate modes, when the cold plasma parameters are changed, such as background electrons and ions species (H(+) and O(+)) temperature, density or the electron beam density and/or drift velocity. These results can be used in a test-particle simulation code, to investigate the ion acceleration and their implication in the auroral acceleration processes, by wave-particle interaction.

  15. Alfven Wave Tomography for Cold MHD Plasmas

    SciTech Connect

    I.Y. Dodin; N.J. Fisch

    2001-09-07

    Alfven waves propagation in slightly nonuniform cold plasmas is studied by means of ideal magnetohydrodynamics (MHD) nonlinear equations. The evolution of the MHD spectrum is shown to be governed by a matrix linear differential equation with constant coefficients determined by the spectrum of quasi-static plasma density perturbations. The Alfven waves are shown not to affect the plasma density inhomogeneities, as they scatter off of them. The application of the MHD spectrum evolution equation to the inverse scattering problem allows tomographic measurements of the plasma density profile by scanning the plasma volume with Alfven radiation.

  16. Excitation of Chirping Whistler Waves in a Laboratory Plasma.

    PubMed

    Van Compernolle, B; An, X; Bortnik, J; Thorne, R M; Pribyl, P; Gekelman, W

    2015-06-19

    Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Here, we report on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced using a beam of energetic electrons launched into a cold plasma. Frequency chirps are only observed for a narrow range of plasma and beam parameters, and show a strong dependence on beam density, plasma density, and magnetic field gradient. Broadband whistler waves similar to magnetospheric hiss are also observed, and the parameter ranges for each emission are quantified. PMID:26196981

  17. Excitation of Chirping Whistler Waves in a Laboratory Plasma

    NASA Astrophysics Data System (ADS)

    Van Compernolle, B.; An, X.; Bortnik, J.; Thorne, R. M.; Pribyl, P.; Gekelman, W.

    2015-06-01

    Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Here, we report on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced using a beam of energetic electrons launched into a cold plasma. Frequency chirps are only observed for a narrow range of plasma and beam parameters, and show a strong dependence on beam density, plasma density, and magnetic field gradient. Broadband whistler waves similar to magnetospheric hiss are also observed, and the parameter ranges for each emission are quantified.

  18. Numerical Simulation of Waves Driven by Plasma Currents Generated by Low-Frequency Alfven Waves in a Multi-Ion Plasma

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Khazanov, George

    2004-01-01

    When multi-ion plasma consisting of heavy and light ions is permeated by a low-frequency Alfven (LFA) wave, the crossed-electric-and-magnetic field (E x B), and the polarization drifts of the different ion species and the electrons could be quite different. The relative drifts between the charged-particle species drive waves, which energize the plasma. Using 2.5-dimensional (2.5-D) particle-in-cell simulations, we study this process of wave generation and its nonlinear consequences in terms of acceleration and heating plasma. Specifically, we study the situation for LFA wave frequency being lower than the heavy-ion cyclotron frequency in a multi-ion plasma. We impose such a wave to the plasma assuming that its wavelength is much larger than that of the waves generated by the relative drifts. For better understanding, the LFA-wave driven simulations are augmented by those driven by initialized ion beams. The driven high-frequency (HF) wave modes critically depend on the heavy ion density nh; for small values of nh, the lower hybrid (LH) waves dominate. On the other hand, for large nh a significantly enhanced level of waves occurs over a much broader frequency spectrum below the LH frequency and such waves are interpreted here as the ion Bernstein (IB) mode near the light ion cyclotron harmonics. Irrespective of the driven wave modes, both the light and heavy ions undergo significant transverse acceleration, but for the large heavy-ion densities, even the electrons are significantly accelerated in the parallel direction by the waves below the LH frequency. Even when the LFA wave drive is maintained, the ion heating leads to the cessation of HF wave excitation just after a few cycles of the former wave. On the basis of marginal stability seen in the simulations, an empirical relation for LFA wave amplitude, frequency and ion temperature is given.

  19. Electron acceleration in preformed plasma channels with terawatt CO{sub 2} laser

    SciTech Connect

    Pogorelsky, I.V.

    1995-02-01

    Extended cylindrical plasma channels produced under gas breakdown by axicon-focused laser beams may be used as optical waveguides in laser-driven electron accelerators. Plasma channeling of the laser beams will help to maintain a high acceleration gradient over many Rayleigh lengths. In addition, the rarefied gas density channel produced after the optical gas breakdown, and followed by a plasma column expansion, reduces multiple scattering of the electron beam. A high-power picosecond C0{sub 2}laser operational at the ATF and being further upgraded to the 1 TW level is considered as the source for a plasma channel formation and as the laser accelerator driver. We show how various laser accelerator schemes including beat wave, wake field, and Inverse Cherenkov accelerator benefit from using a channeled short-pulse C0{sub 2}laser as a driver.

  20. Plasma wave aided two photon decay of an electromagnetic wave in a plasma

    SciTech Connect

    Kumar, K. K. Magesh; Singh, Rohtash; Krishan, Vinod

    2014-11-15

    The presence of a Langmuir wave in an unmagnetized plasma is shown to allow parametric decay of an electromagnetic wave into two electromagnetic waves, which is otherwise not allowed due to wave number mismatch. The decay occurs at plasma densities below one ninth the critical density and the decay waves propagate at finite angles to the pump laser. Above the threshold, the growth rate scales linearly with the amplitude of the Langmuir wave and the amplitude of the pump electromagnetic wave. The frequency ω of the lower frequency decay wave increases with the angle its propagation vector makes with that of the pump. The growth rate, however, decreases with ω.

  1. Electron beam manipulation, injection and acceleration in plasma wakefield accelerators by optically generated plasma density spikes

    NASA Astrophysics Data System (ADS)

    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.

  2. Charge Diagnostics for Laser Plasma Accelerators

    SciTech Connect

    Nakamura, K.; Gonsalves, A. J.; Lin, C.; Sokollik, T.; Smith, A.; Rodgers, D.; Donahue, R.; Bryne, W.; Leemans, W. P.

    2010-06-01

    The electron energy dependence of a scintillating screen (Lanex Fast) was studied with sub-nanosecond electron beams ranging from 106 MeV to 1522 MeV at the Lawrence Berkeley National Laboratory Advanced Light Source (ALS) synchrotron booster accelerator. The sensitivity of the Lanex Fast decreased by 1percent per 100 MeV increase of the energy. The linear response of the screen against the charge was verified with charge density and intensity up to 160 pC/mm2 and 0.4 pC/ps/mm2, respectively. For electron beams from the laser plasma accelerator, a comprehensive study of charge diagnostics has been performed using a Lanex screen, an integrating current transformer, and an activation based measurement. The charge measured by each diagnostic was found to be within +/-10 percent.

  3. Charge Diagnostics for Laser Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Gonsalves, A. J.; Lin, C.; Sokollik, T.; Smith, A.; Rodgers, D.; Donahue, R.; Bryne, W.; Leemans, W. P.

    2010-11-01

    The electron energy dependence of a scintillating screen (Lanex Fast) was studied with sub-nanosecond electron beams ranging from 106 MeV to 1522 MeV at the Lawrence Berkeley National Laboratory Advanced Light Source (ALS) synchrotron booster accelerator. The sensitivity of the Lanex Fast decreased by 1% per 100 MeV increase of the energy. The linear response of the screen against the charge was verified with charge density and intensity up to 160 pC/mm2 and 0.4 pC/ps/mm2, respectively. For electron beams from the laser plasma accelerator, a comprehensive study of charge diagnostics has been performed using a Lanex screen, an integrating current transformer, and an activation based measurement. The charge measured by each diagnostic was found to be within ±10%.

  4. Charge Diagnostics for Laser Plasma Accelerators

    SciTech Connect

    Nakamura, K.; Gonsalves, A. J.; Lin, C.; Sokollik, T.; Smith, A.; Rodgers, D.; Donahue, R.; Bryne, W.; Leemans, W. P.

    2010-11-04

    The electron energy dependence of a scintillating screen (Lanex Fast) was studied with sub-nanosecond electron beams ranging from 106 MeV to 1522 MeV at the Lawrence Berkeley National Laboratory Advanced Light Source (ALS) synchrotron booster accelerator. The sensitivity of the Lanex Fast decreased by 1% per 100 MeV increase of the energy. The linear response of the screen against the charge was verified with charge density and intensity up to 160 pC/mm{sup 2} and 0.4 pC/ps/mm{sup 2}, respectively. For electron beams from the laser plasma accelerator, a comprehensive study of charge diagnostics has been performed using a Lanex screen, an integrating current transformer, and an activation based measurement. The charge measured by each diagnostic was found to be within {+-}10%.

  5. Wave-driven Countercurrent Plasma Centrifuge

    SciTech Connect

    A.J. Fetterman and N.J. Fisch

    2009-03-20

    A method for driving rotation and a countercurrent flow in a fully ionized plasma centrifuge is described. The rotation is produced by radiofrequency waves near the cyclotron resonance. The wave energy is transferred into potential energy in a manner similar to the α channeling effect. The countercurrent flow may also be driven by radiofrequency waves. By driving both the rotation and the flow pattern using waves instead of electrodes, physical and engineering issues may be avoided.

  6. Plasma wakefield acceleration at CLARA facility in Daresbury Laboratory

    NASA Astrophysics Data System (ADS)

    Xia, G.; Nie, Y.; Mete, O.; Hanahoe, K.; Dover, M.; Wigram, M.; Wright, J.; Zhang, J.; Smith, J.; Pacey, T.; Li, Y.; Wei, Y.; Welsch, C.

    2016-09-01

    A plasma accelerator research station (PARS) has been proposed to study the key issues in electron driven plasma wakefield acceleration at CLARA facility in Daresbury Laboratory. In this paper, the quasi-nonlinear regime of beam driven plasma wakefield acceleration is analysed. The wakefield excited by various CLARA beam settings are simulated by using a 2D particle-in-cell (PIC) code. For a single drive beam, an accelerating gradient up to 3 GV/m can be achieved. For a two bunch acceleration scenario, simulation shows that a witness bunch can achieve a significant energy gain in a 10-50 cm long plasma cell.

  7. Pulse-discharge plasmas for plasma-accelerator applications

    SciTech Connect

    Clayton, C. E.; Joshi, C.; Lopes, N. C.

    2012-12-21

    For particle-beam-driven plasma wakefield accelerators, a long and fully-ionized plasma is desirable. We describe an experiment at UCLA to develop a prototype of such plasma using a pulsed-current discharge. Scaling of the plasma density with glass-tube diameter and with discharge-circuit parameters is currently underway. We have found that 4 Torr of Argon can be fully ionized to a density of about 1.3 Multiplication-Sign 10{sup 17} cm{sup -3} when the current density in the 1 inch diameter, 1.2 meter-long tube is around 2 kA/cm{sup 2}, at least at one point along the discharge. The homogeneity of the plasma density in the longitudinal direction is crucial to prevent slippage of the driven plasma structures with the particles. Equally important are the transverse gradients since any dipole asymmetry in the transverse direction can lead to 'steering' of the particle beam. The longitudinal and transverse gradients may be a function of time into the discharge, the shape of the electrodes, the tube size, and the fractional ionization for a given fill pressure. These issues are currently under investigation.

  8. Full Wave Modeling of Wave -- Plasma Interactions in NSTX.

    NASA Astrophysics Data System (ADS)

    Phillips, C. K.; Bernabei, S.; Fredrickson, E.; Gorelenkov, N.; Hosea, J. C.; Leblanc, B.; Valeo, E. J.; Wilson, J. R.; Bonoli, P. T.; Wright, J. C.; Ryan, P. M.; Wilgen, J. B.

    2006-10-01

    Wave plasma interactions play an important role in the dynamics of NSTX plasmas in a wide range of frequencies. High harmonic fast waves (HHFW), with frequencies significantly above the fundamental ion cyclotron frequency, are used to heat and drive noninductive currents in NSTX plasmas. Fast ions from neutral beam injection can excite compressional and / or global Alfven eigenmodes (CAE/GAE) with frequencies near the fundamental ion cyclotron frequency. Simulations of power deposition profiles obtained with the full wave code, TORIC, will be compared to the observations from recent HHFW experiments that show that the wave propagation and absorption depend strongly on the antenna phasing and plasma conditions [i]. The issue of mode conversion of the HHFWs to shorter wavelength modes will be revisited. Initial simulations of driven eigenmodes in the CAE / GAE frequency range will also be discussed. [i] See contributed Oral Talk by J. C. Hosea et al this conference

  9. Stimulated Electromagnetic Emission Indicator of Glow Plasma Discharges from Ionospheric HF Wave Transmissions with HAARP

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Scales, W.; Briczinski, S. J.; Fu, H.; Mahmoudian, A.; Samimi, A.

    2012-12-01

    High power radio waves resonantly interact with to accelerate electrons for production of artificial aurora and plasma clouds. These plasma clouds are formed when the HF frequency is tuned near a harmonic of the electron cyclotron frequency. At a narrow band resonance, large electrostatic fields are produced below the F-layer and the neutral atmosphere breaks down with a glow plasma discharge. The conditions for this resonance are given by matching the pump wave frequency and wave-number with the sum of daughter frequencies and wave-numbers for several plasma modes. The most likely plasma mode that accelerates the electrons is the electron Bernstein wave in conjunction with an ion acoustic wave. Both upper hybrid and whistler mode waves are also possible sources of electron acceleration. To determine the plasma process for electron acceleration, stimulated electromagnetic emissions are measured using ground receivers in a north-south chain from the HAARP site. Recent observations have shown that broad band spectral lines downshifted from the HF pump frequency are observed when artificial plasma clouds are formed. For HF transmissions are the 2nd, 3rd, and 4th gyro harmonic, the downshifted indicators are found 500 Hz, 20 kHz, and 140 kHz, respectively, from the pump frequency. This Indicator Mode (IM) anticipates that a plasma layer will be formed before it is recorded with an ionosonde or optical imager.

  10. Self-mode-transition from laser wakefield accelerator to plasma wakefield accelerator of laser-driven plasma-based electron acceleration

    SciTech Connect

    Pae, K. H.; Choi, I. W.; Lee, J.

    2010-12-15

    Via three-dimensional particle-in-cell simulations, the self-mode-transition of a laser-driven electron acceleration from laser wakefield to plasma-wakefield acceleration is studied. In laser wakefield accelerator (LWFA) mode, an intense laser pulse creates a large amplitude wakefield resulting in high-energy electrons. Along with the laser pulse depletion, the electron bunch accelerated in the LWFA mode drives a plasma wakefield. Then, after the plasma wakefield accelerator mode is established, electrons are trapped and accelerated in the plasma wakefield. The mode transition process and the characteristics of the accelerated electron beam are presented.

  11. Computational study of nonlinear plasma waves. [plasma simulation model applied to electrostatic waves in collisionless plasma

    NASA Technical Reports Server (NTRS)

    Matsuda, Y.

    1974-01-01

    A low-noise plasma simulation model is developed and applied to a series of linear and nonlinear problems associated with electrostatic wave propagation in a one-dimensional, collisionless, Maxwellian plasma, in the absence of magnetic field. It is demonstrated that use of the hybrid simulation model allows economical studies to be carried out in both the linear and nonlinear regimes with better quantitative results, for comparable computing time, than can be obtained by conventional particle simulation models, or direct solution of the Vlasov equation. The characteristics of the hybrid simulation model itself are first investigated, and it is shown to be capable of verifying the theoretical linear dispersion relation at wave energy levels as low as .000001 of the plasma thermal energy. Having established the validity of the hybrid simulation model, it is then used to study the nonlinear dynamics of monochromatic wave, sideband instability due to trapped particles, and satellite growth.

  12. Energy Doubling of 42 GeV Electrons in a Meter-scale Plasma Wakefield Accelerator

    SciTech Connect

    Blumenfeld, Ian; Clayton, Christopher E.; Decker, Franz-Josef; Hogan, Mark J.; Huang, Chengkun; Ischebeck, Rasmus; Iverson, Richard; Joshi, Chandrashekhar; Katsouleas, Thomas; Kirby, Neil; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; Muggli, Patric; Oz, Erdem; Siemann, Robert H.; Walz, Dieter; Zhou, Miaomiao; /SLAC /UCLA /Southern California U.

    2007-03-14

    The energy frontier of particle physics is several trillion electron volts, but colliders capable of reaching this regime (such as the Large Hadron Collider and the International Linear Collider) are costly and time-consuming to build; it is therefore important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators, a drive beam (either laser or particle) produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultrahigh accelerating fields over a substantial length to achieve a significant energy gain. Here we show that an energy gain of more than 42 GeV is achieved in a plasma wakefield accelerator of 85 cm length, driven by a 42 GeV electron beam at the Stanford Linear Accelerator Center (SLAC). The results are in excellent agreement with the predictions of three-dimensional particle-in-cell simulations. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of {approx} 52GV m{sup -1}. This effectively doubles their energy, producing the energy gain of the 3-km-long SLAC accelerator in less than a meter for a small fraction of the electrons in the injected bunch. This is an important step towards demonstrating the viability of plasma accelerators for high-energy physics applications.

  13. Dependence of Initial Plasma Size on Laser-driven In-Tube Accelerator (LITA) Performance

    SciTech Connect

    Kim, Sukyum; Jeung, In-Seuck; Ohtani, Toshiro; Sasoh, Akihiro; Choi, Jeong-Yeol

    2004-03-30

    At Tohoku University, experiments of Laser-driven In-Tube Accelerator (LITA) have been carried out. In order to observe the initial state of plasma and blast wave, the visualization experiment was carried out using the shadowgraph method. In this paper, dependency of initial plasma size on LITA performance is investigated numerically. The plasma size is estimated using shadowgraph images and the numerical results are compared with the experimental data of pressure measurement and results of previous modeling.

  14. Dependence of Initial Plasma Size on Laser-driven In-Tube Accelerator (LITA) Performance

    NASA Astrophysics Data System (ADS)

    Kim, Sukyum; Ohtani, Toshiro; Sasoh, Akihiro; Jeung, In-Seuck; Choi, Jeong-Yeol

    2004-03-01

    At Tohoku University, experiments of Laser-driven In-Tube Accelerator (LITA) have been carried out. In order to observe the initial state of plasma and blast wave, the visualization experiment was carried out using the shadowgraph method. In this paper, dependency of initial plasma size on LITA performance is investigated numerically. The plasma size is estimated using shadowgraph images and the numerical results are compared with the experimental data of pressure measurement and results of previous modeling.

  15. Evolution Of Nonlinear Waves in Compressing Plasma

    SciTech Connect

    P.F. Schmit, I.Y. Dodin, and N.J. Fisch

    2011-05-27

    Through particle-in-cell simulations, the evolution of nonlinear plasma waves is examined in one-dimensional collisionless plasma undergoing mechanical compression. Unlike linear waves, whose wavelength decreases proportionally to the system length L(t), nonlinear waves, such as solitary electron holes, conserve their characteristic size {Delta} during slow compression. This leads to a substantially stronger adiabatic amplification as well as rapid collisionless damping when L approaches {Delta}. On the other hand, cessation of compression halts the wave evolution, yielding a stable mode.

  16. Surface plasma wave excitation via laser irradiated overdense plasma foil

    SciTech Connect

    Kumar, Pawan; Tripathi, V. K.

    2012-04-09

    A laser irradiated overdense plasma foil is seen to be susceptible to parametric excitation of surface plasma wave (SPW) and ion acoustic wave (IAW) on the ion plasma period time scale. The SPW is localised near the front surface of the foil while IAW extends upto the rear. The evanescent laser field and the SPW exert a ponderomotive force on electrons driving the IAW. The density perturbation associated with the latter beats with the laser induced oscillatory electron velocity to drive the SPW. At relativistic laser intensity, the growth rate is of the order of ion plasma frequency.

  17. Electromagnetic waves in a polydisperse dusty plasma

    SciTech Connect

    Prudskikh, V. V.; Shchekinov, Yu. A.

    2013-10-15

    The properties of low-frequency electromagnetic waves in a polydisperse dusty plasma are studied. The dispersion relation for the waves propagating at an arbitrary angle to the external magnetic field is derived, with the coefficients explicitly determined by the dust-size distribution function. The dependence of wave dispersion on properties of the dust-size distribution function is analysed. It is shown that the cutoff for an oblique propagation in plasma with a wide scatter of dust sizes takes place at a much lower frequency than in a plasma with monosized dust particles. It is found that dispersion properties of a transversal magnetosonic wave mode around dust–cyclotron frequencies considerably differ from those in a plasma with monosized dust. In a plasma with low mass fraction of dust particles, the dispersion is smooth without the cutoff and the resonance intrinsic for a plasma with monosized dust. Increase of the dust fraction results in splitting of the dispersion curve on to two branches. Further increase of the dust fraction leads to emergence of the third branch located between the cutoffs and restricted from the lower and higher frequencies by two resonances. The dependence of the frequencies of cutoffs and resonances on the width of the dust-size distribution, its slope and the dust mass fraction are analysed. It is shown that the transparency frequency windows in a plasma with polydisperse dust are wider for transversal elecromagnetic waves, but narrower for longitudinal or oblique waves.

  18. Method for generating extreme ultraviolet with mather-type plasma accelerators for use in Extreme Ultraviolet Lithography

    DOEpatents

    Hassanein, Ahmed; Konkashbaev, Isak

    2006-10-03

    A device and method for generating extremely short-wave ultraviolet electromagnetic wave uses two intersecting plasma beams generated by two plasma accelerators. The intersection of the two plasma beams emits electromagnetic radiation and in particular radiation in the extreme ultraviolet wavelength. In the preferred orientation two axially aligned counter streaming plasmas collide to produce an intense source of electromagnetic radiation at the 13.5 nm wavelength. The Mather type plasma accelerators can utilize tin, or lithium covered electrodes. Tin, lithium or xenon can be used as the photon emitting gas source.

  19. Fast wave evanescence in filamentary boundary plasmas

    SciTech Connect

    Myra, J. R.

    2014-02-15

    Radio frequency waves for heating and current drive of plasmas in tokamaks and other magnetic confinement devices must first traverse the scrape-off-layer (SOL) before they can be put to their intended use. The SOL plasma is strongly turbulent and intermittent in space and time. These turbulent properties of the SOL, which are not routinely taken into account in wave propagation codes, can have an important effect on the coupling of waves through an evanescent SOL or edge plasma region. The effective scale length for fast wave (FW) evanescence in the presence of short-scale field-aligned filamentary plasma turbulence is addressed in this paper. It is shown that although the FW wavelength or evanescent scale length is long compared with the dimensions of the turbulence, the FW does not simply average over the turbulent density; rather, the average is over the exponentiation rate. Implications for practical situations are discussed.

  20. Temperature Diffusion Waves in Magnetized Plasmas

    NASA Astrophysics Data System (ADS)

    Reynolds, M. A.; Morales, G. J.; Maggs, J. E.

    2002-11-01

    Fluctuations of localized heat sources manifest themselves as temperature diffusion waves throughout the plasma surrounding the source, with anisotropic propagation characteristics due to the anisotropic nature of the thermal conductivity. In fact, fluctuations in electron temperature have been observed experimentally in studies of heat transport in magnetized temperature filaments (Burke et al., Phys. Plasmas, 7, 1397, 2000) where the anisotropic nature was of paramount interest. Here, the theory of temperature diffusion waves in a magnetized plasma is presented, and the properties of these waves are investigated both analytically and numerically. Results from the one-dimensional (parallel), linear theory of diffusion waves are used to shed light on the results obtained by a two-dimensional (parallel and perpendicular) transport code. Features that are investigated include the spatial structure of wave amplitude and phase, the effect that the size of the source region has on the spatial structure (i.e., radial localization), and the strongly nonlinear (large amplitude source fluctuations) limit.

  1. Simulations of auroral plasma processes - Electric fields, waves and particles

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Thiemann, H.; Schunk, R. W.

    1987-01-01

    Plasma processes driven by current sheets of finite thicknesses in an ambient magnetized plasma are studied using a 2 1/2 dimensional particle-in-cell code, and similarities are found between simulated plasma processes and those observed in the auroral plasma. Current sheets are shown to be bounded by large perpendicular electric fields occurring near their edges above the conducting boundary. Shaped potential structures form when the current sheets are narrow, and when the current sheets are wide, potential structures develop a significant parallel potential drop such that the electrons are accelerated upwards. Downward parallel electric fields of variable strength are noted in the downward current region, and double layer formation is seen in both narrow and wide current sheets. High frequency oscillations near the electron plasma frequency and its harmonic are seen, and low frequency waves are observed.

  2. Magnetoacoustic shock waves in dissipative degenerate plasmas

    SciTech Connect

    Hussain, S.; Mahmood, S.

    2011-11-15

    Quantum magnetoacoustic shock waves are studied in homogenous, magnetized, dissipative dense electron-ion plasma by using two fluid quantum magneto-hydrodynamic (QMHD) model. The weak dissipation effects in the system are taken into account through kinematic viscosity of the ions. The reductive perturbation method is employed to derive Korteweg-de Vries Burgers (KdVB) equation for magnetoacoustic wave propagating in the perpendicular direction to the external magnetic field in dense plasmas. The strength of magnetoacoustic shock is investigated with the variations in plasma density, magnetic field intensity, and ion kinematic viscosity of dense plasma system. The necessary condition for the existence of monotonic and oscillatory shock waves is also discussed. The numerical results are presented for illustration by using the data of astrophysical dense plasma situations such as neutron stars exist in the literature.

  3. Plasma Density Tapering for Laser Wakefield Acceleration of Electrons and Protons

    SciTech Connect

    Ting, A.; Gordon, D.; Kaganovich, D.; Sprangle, P.; Helle, M.; Hafizi, B.

    2010-11-04

    Extended acceleration in a Laser Wakefield Accelerator can be achieved by tailoring the phase velocity of the accelerating plasma wave, either through profiling of the density of the plasma or direct manipulation of the phase velocity. Laser wakefield acceleration has also reached a maturity that proton acceleration by wakefield could be entertained provided we begin with protons that are substantially relativistic, {approx}1 GeV. Several plasma density tapering schemes are discussed. The first scheme is called ''bucket jumping'' where the plasma density is abruptly returned to the original density after a conventional tapering to move the accelerating particles to a neighboring wakefield period (bucket). The second scheme is designed to specifically accelerate low energy protons by generating a nonlinear wakefield in a plasma region with close to critical density. The third scheme creates a periodic variation in the phase velocity by beating two intense laser beams with laser frequency difference equal to the plasma frequency. Discussions and case examples with simulations are presented where substantial acceleration of electrons or protons could be obtained.

  4. Miniature plasma accelerating detonator and method of detonating insensitive materials

    SciTech Connect

    Bickes, R.W. Jr.; Kopczewski, M.R.; Schwarz, A.C.

    1986-11-11

    This patent describes a detonator assembly for initiating insensitive explosives or energetic materials. In the improvement described here the detonator assembly comprises: railgun accelerating means of a size sufficient to be used as a detonator for insensitive explosives or energetic materials in an amount of about 100 mg of explosives or less and capable of accelerating a plasma to detonation initiating velocities; and power supply means for supplying the power necessary to the railgun accelerating means to generate and accelerate the plasma.

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

    NASA Astrophysics Data System (ADS)

    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

  6. Experimental evidence for the acceleration of thermal electrons by ion cyclotron waves in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Norris, A. J.; Sojka, J. J.; Wrenn, G. L.; Johnson, J. F. E.; Cornilleau-Wehrlin, N.; Perraut, S.; Roux, A.

    1983-01-01

    Experimental evidence is presented for the acceleration of thermal electrons by large amplitude ion cyclotron waves (ICWs). The wave power in the ULF range near the helium gyrofrequency is compared with the distribution function of low energy electrons measured by GEOS satellite instruments. This comparison shows that electrons are accelerated near the geomagnetic equator along field lines, at times when the ICW energy is large and the cold plasma density is below a threshold value. It is suggested that these accelerated electrons can account for the ELF emissions, modulated at the ICW frequency, observed by Wehrlin (1981). A very efficient acceleration of thermal electrons along field lines results from other ULF events having frequencies close to the proton gyrofrequency. Evidence for this lies in the fact that medium energy protons having large temperature anisotropies in the 100-500 eV range are responsible for the ICW wave generation.

  7. Summary Report of Working Group 6: Laser-Plasma Acceleration

    SciTech Connect

    Leemans, Wim P.; Downer, Michael; Siders, Craig

    2006-07-01

    A summary is given of presentations and discussions in theLaser-Plasma Acceleration Working Group at the 2006 Advanced AcceleratorConcepts Workshop. Presentation highlights include: widespreadobservation of quasi-monoenergetic electrons; good agreement betweenmeasured and simulated beam properties; the first demonstration oflaser-plasma acceleration up to 1 GeV; single-shot visualization of laserwakefield structure; new methods for measuring<100 fs electronbunches; and new methods for "machining" laser-plasma acceleratorstructures. Discussion of future direction includes: developing a roadmapfor laser-plasma acceleration beyond 1 GeV; a debate over injection andguiding; benchmarking simulations with improved wake diagnostics;petawatt laser technology for future laser-plasmaaccelerators.

  8. PREFACE: Acceleration and radiation generation in space and laboratory plasmas

    NASA Astrophysics Data System (ADS)

    Bingham, R.; Katsouleas, T.; Dawson, J. M.; Stenflo, L.

    1994-01-01

    and radiation generation in plasmas. The next section includes state-of-the-art papers on laboratory accelerators driven by lasers (Nakajima et al., Shukla, Johnson et al.), microwaves (Nishida et al., Bogomolov et al.) and by particle beams (Ogata et al.). Also in this section are theoretical papers presenting new work on synchrotron like oscillations in plasma waves (Fedele) and two types of laboratory radiation sources, FEL's (Marshall et al.) and ionization fronts (Lai et al.), and Frantzeskakis et al. described the Hamiltonian analysis of a slow-wave autonomous cyclotron buncher. Section 3 contains papers on astrophysical plasmas, with the general presentations of Colgate and Krishnan. Kazanas and Krishnan address active galactic nuclei (AGNs). Thielheim discusses general acceleration mech anisms in rotating magnetized systems. Asseo discussed Langmuir solitons in pulsars and Blackman et al. treat magnetic reconnection relativistically. Su et al. analyze the possibility of plasma wave excitation and particle acceleration by neu trinos from supernovae. Dogiel et al. on cosmic ray scattering by MHD fluctuations. The papers in Section 4 treat fusion plasmas (Dendy et al. and Lashmore-Davies et al.). Section 5, space plasmas, includes papers on acceleration processes in the magnetosphere (Anagnostopoulos and Marshall et al.) and the sun (Barletta et al.). It is evident from the Workshop and the papers collected here that this is indeed a rich field of investigations and that both the natural and laboratory plasma communities can benefit from the cross-fertilization of ideas between them. We wish to thank the authors and attendees for their contributions to the success of this workshop, Dr Philip Debenham and Dr David Sutter of the U.S. D.o.E. and Dr Charles Roberson of the U.S. O.N.R. for their financial support (Grants DE-FGO3-93ER40776 and N00014-93-1-0814), and the ECC Twinning Grant SC1*-CT92-0773. We appreciate the considerable local support from Mr Glegles and

  9. Nonlinear inertial Alfven wave in dusty plasmas

    SciTech Connect

    Mahmood, S.; Saleem, H.

    2011-11-29

    Solitary inertial Alfven wave in the presence of positively and negatively charged dust particles is studied. It is found that electron density dips are formed in the super Alfvenic region and wave amplitude is increased for the case of negatively charged dust particles in comparison with positively charged dust particles in electron-ion plasmas.

  10. Ion Acoustic Waves in Ultracold Neutral Plasmas

    SciTech Connect

    Castro, J.; McQuillen, P.; Killian, T. C.

    2010-08-06

    We photoionize laser-cooled atoms with a laser beam possessing spatially periodic intensity modulations to create ultracold neutral plasmas with controlled density perturbations. Laser-induced fluorescence imaging reveals that the density perturbations oscillate in space and time, and the dispersion relation of the oscillations matches that of ion acoustic waves, which are long-wavelength, electrostatic, density waves.

  11. Plasma waves associated with the space shuttle

    NASA Technical Reports Server (NTRS)

    Cairns, I. H.; Gurnett, D. A.

    1990-01-01

    Water molecules outgassed from the Space Shuttle suffer collisional charge-exchange with ionospheric oxygen ions, thereby forming unstable distributions of pick-up water ions and leading to high levels of plasma waves near the Shuttle. Liouville's equation with a charge-exchange source term is solved for the water ion distribution function as a function of position relative to the Shuttle. The observational characteristics of the near zone Shuttle waves are summarized. A linear theory in which beam like distributions of water ions drive Doppler shifted lower hybrid waves via the modified two stream instability is developed. This theory explains many characteristics of the near zone waves. Further work on the effects of wave nonlinearities and spatial inhomogeneity is required to explain the detailed frequency spectrum of the waves. The observed wave levels apparently satisfy the threshold condition for modulational instability of lower hybrid waves.

  12. Cross focusing of two laser beams and plasma wave excitation

    SciTech Connect

    Gupta, M.K.; Sharma, R.P.; Gupta, V.L.

    2005-12-15

    This article presents the cross focusing of two high power laser beams in a plasma when relativistic and ponderomotive nonlinearities are operative. The effect of electron density modification changes the critical power significantly in contrast to (only) relativistic case. The plasma wave generation at the difference frequency and particle acceleration has also been studied. In a typical case when laser wavelengths are 1047 and 1064 nm and electron density 1.9x10{sup 19} cm{sup -3}, the maximum electron plasma wave power flux comes out to be 6x10{sup 17} W/cm{sup 2} (laser power P{sub 1}=3.6x10{sup 18} W/cm{sup 2} and P{sub 2}=3.2x10{sup 18} W/cm{sup 2})

  13. BOOK REVIEW: Kinetic theory of plasma waves, homogeneous plasmas

    NASA Astrophysics Data System (ADS)

    Porkolab, Miklos

    1998-11-01

    The linear theory of plasma waves in homogeneous plasma is arguably the most mature and best understood branch of plasma physics. Given the recently revised version of Stix's excellent Waves in Plasmas (1992), one might ask whether another book on this subject is necessary only a few years later. The answer lies in the scope of this volume; it is somewhat more detailed in certain topics than, and complementary in many fusion research relevant areas to, Stix's book. (I am restricting these comments to the homogeneous plasma theory only, since the author promises a second volume on wave propagation in inhomogeneous plasmas.) This book is also much more of a theorist's approach to waves in plasmas, with the aim of developing the subject within the logical framework of kinetic theory. This may indeed be pleasing to the expert and to the specialist, but may be too difficult to the graduate student as an `introduction' to the subject (which the author explicitly states in the Preface). On the other hand, it may be entirely appropriate for a second course on plasma waves, after the student has mastered fluid theory and an introductory kinetic treatment of waves in a hot magnetized `Vlasov' plasma. For teaching purposes, my personal preference is to review the cold plasma wave treatment using the unified Stix formalism and notation (which the author wisely adopts in the present book, but only in Chapter 5). Such an approach allows one to deal with CMA diagrams early on, as well as to provide a framework to discuss electromagnetic wave propagation and accessibility in inhomogeneous plasmas (for which the cold plasma wave treatment is perfectly adequate). Such an approach does lack some of the rigour, however, that the author achieves with the present approach. As the author correctly shows, the fluid theory treatment of waves follows logically from kinetic theory in the cold plasma limit. I only question the pedagogical value of this approach. Otherwise, I welcome this

  14. Helicon Plasma Injector and Ion Cyclotron Acceleration Development in the VASIMR Experiment

    NASA Technical Reports Server (NTRS)

    Squire, Jared P.; Chang, Franklin R.; Jacobson, Verlin T.; McCaskill, Greg E.; Bengtson, Roger D.; Goulding, Richard H.

    2000-01-01

    In the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) radio frequency (rf) waves both produce the plasma and then accelerate the ions. The plasma production is done by action of helicon waves. These waves are circular polarized waves in the direction of the electron gyromotion. The ion acceleration is performed by ion cyclotron resonant frequency (ICRF) acceleration. The Advanced Space Propulsion Laboratory (ASPL) is actively developing efficient helicon plasma production and ICRF acceleration. The VASIMR experimental device at the ASPL is called VX-10. It is configured to demonstrate the plasma production and acceleration at the 10kW level to support a space flight demonstration design. The VX-10 consists of three electromagnets integrated into a vacuum chamber that produce magnetic fields up to 0.5 Tesla. Magnetic field shaping is achieved by independent magnet current control and placement of the magnets. We have generated both helium and hydrogen high density (>10(exp 18) cu m) discharges with the helicon source. ICRF experiments are underway. This paper describes the VX-10 device, presents recent results and discusses future plans.

  15. Theories of radio emissions and plasma waves. [in Jupiter magnetosphere

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.; Goertz, C. K.

    1983-01-01

    The complex region of Jupiter's radio emissions at decameter wavelengths, the so-called DAM, is considered, taking into account the basic theoretical ideas which underly both the older and newer theories and models. Linear theories are examined, giving attention to direct emission mechanisms, parallel propagation, perpendicular propagation, and indirect emission mechanisms. An investigation of nonlinear theories is also conducted. Three-wave interactions are discussed along with decay instabilities, and three-wave up-conversio. Aspects of the Io and plasma torus interaction are studied, and a mechanism by which Io can accelerate electrons is reviewed.

  16. Ions Gyroresonant Surfing Acceleration by Alfven Waves in the Vicinity of SLAMS Boundary

    NASA Astrophysics Data System (ADS)

    Agapitov, Oleksiy; Kis, Arpad; Krasnoselskikh, Vladimir

    2012-07-01

    A well known feature of collisionless shocks which are formed in space plasmas is their capability to accelerate particles to high energies. On the other hand, the exact mechanism how this acceleration takes place is still unknown. This is especially true in the case of the so-called seed particle population, i.e. those particles which are being injected into the process of acceleration. In our study we present a case study of gyroresonant surfing acceleration observed on the quasi-parallel side of the Earth's bow shock. For our analysis we use simultaneous multi-spacecraft measurement data provided by the Cluster spacecraft ion (CIS), magnetic (FGM) and electric field and wave instrument (EFW) during a time period of large inter-spacecraft separation distance. Our results show evidence that the gyroresonance surfing acceleration takes place as a consequence of interaction between monochromatic (or quasi-monochromatic) electromagnetic plasma waves and short large amplitude magnetic structures (SLAMS). The magnetic field inhomogeneity mirror force allows to keep the resonant conditions for the ions trapped by wave and thus to increase effectively the particle velocity. Since monochromatic wave packets with circular polarization and different kinds of magnetic structures are very commonly observed in the front of the Earth's quasi-parallel bow shock, thus the gyroresonant surfing acceleration can be an effective particle injection mechanism resulting in the formation of the seed particle population.

  17. Hot spots and dark current in advanced plasma wakefield accelerators

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    Dark current can spoil witness bunch beam quality and acceleration efficiency in particle beam-driven plasma wakefield accelerators. In advanced schemes, hot spots generated by the drive beam or the wakefield can release electrons from higher ionization threshold levels in the plasma media. These electrons may be trapped inside the plasma wake and will then accumulate dark current, which is generally detrimental for a clear and unspoiled plasma acceleration process. Strategies for generating clean and robust, dark current free plasma wake cavities are devised and analyzed, and crucial aspects for experimental realization of such optimized scenarios are discussed.

  18. Gabor Wave Packet Method to Solve Plasma Wave Equations

    SciTech Connect

    A. Pletzer; C.K. Phillips; D.N. Smithe

    2003-06-18

    A numerical method for solving plasma wave equations arising in the context of mode conversion between the fast magnetosonic and the slow (e.g ion Bernstein) wave is presented. The numerical algorithm relies on the expansion of the solution in Gaussian wave packets known as Gabor functions, which have good resolution properties in both real and Fourier space. The wave packets are ideally suited to capture both the large and small wavelength features that characterize mode conversion problems. The accuracy of the scheme is compared with a standard finite element approach.

  19. Summary Report of Working Group 1: Laser-Plasma Acceleration

    SciTech Connect

    Geddes, C.G.R.; Clayton, C.; Lu, W.; Thomas, A.G.R.

    2010-06-01

    Advances in and physics of the acceleration of particles using underdense plasma structures driven by lasers were the topics of presentations and discussions in Working Group 1 of the 2010 Advanced Accelerator Concepts Workshop. Such accelerators have demonstrated gradients several orders beyond conventional machines, with quasi-monoenergetic beams at MeV-GeV energies, making them attractive candidates for next generation accelerators. Workshop discussions included advances in control over injection and laser propagation to further improve beam quality and stability, detailed diagnostics and physics models of the acceleration process, radiation generation as a source and diagnostic, and technological tools and upcoming facilities to extend the reach of laser-plasma accelerators.

  20. Theory and simulation of plasma sheath waves

    SciTech Connect

    Xu, X.Q.; DiPeso, G.; Vahedi, V.; Birdsall, C.K.

    1992-12-15

    Sheath waves have been investigated analytically and with particle simulation for an unmagnetized two dimensional plasma slab with periodic boundary conditions in y and conducting walls at x = 0, L{sub x}. Analytically treating the sheath as a vacuum layer, the sheath wave bears a resemblance to plasma vacuum surface waves. The simulations are in agreement with the theory for both bulk Bohm Grow waves and edge sheath waves, with some unanswered questions. Some waves that were expected did not show up, at least, where we thought they should be. Hence, improvements were made in the initialization (a better quiet start), in the diagnostics (especially the spectra in frequency), and in the excitation (ability to pulse). It has become clear that this problem, seeking both sheath (or surface) and body waves in a bounded system, needs far more attention, in analysis (non-uniform density included) and in simulation, especially in diagnostics. Hence, this report is to be treated as a start on the problem. The problem is not dropped, as the understanding of such waves (in 2d and 3d) is very important, for both basic sheath understanding and for applications, such as plasma control via excitation of sheath or pre-sheath waves.

  1. Arrayed Diagnostic Development on the HyperV Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Brockington, Samuel; Case, Andrew; Messer, Sarah; Bomgardner, Richard; Witherspoon, F. D.

    2008-11-01

    The sparkgap injected plasma accelerator is one of several coaxial railguns constructed at HyperV to accelerate dense plasmas to high velocities. A circumferential array of 112 high voltage tungsten electrodes ablates polyethylene to form and inject a toroidally shaped plasma into the annular breech at the rear of the accelerator. A pulse forming network then applies several hundred kiloamps to the coaxial electrodes to accelerate the plasma. A 4-chord laser deflectometer and a 32-sensor fast photodiode array are being developed to help resolve the structure, density, and velocity of the accelerated plasma jet for different accelerator parameters. We present details of the diagnostic designs and initial data. Work supported by the U.S. DOE Office of Fusion Energy Sciences.

  2. Ion acoustic shock waves in degenerate plasmas

    SciTech Connect

    Akhtar, N.; Hussain, S.

    2011-07-15

    Korteweg de Vries Burgers equation for negative ion degenerate dissipative plasma has been derived using reductive perturbation technique. The quantum hydrodynamic model is used to study the quantum ion acoustic shock waves. The effects of different parameters on quantum ion acoustic shock waves are studied. It is found that quantum parameter, electrons Fermi temperature, temperature of positive and negative ions, mass ratio of positive to negative ions, viscosity, and density ratio have significant impact on the shock wave structure in negative ion degenerate plasma.

  3. Laser Guiding for GeV Laser-Plasma Accelerators

    SciTech Connect

    Leemans, Wim; Esarey, Eric; Geddes, Cameron; Schroeder, C.B.; Toth, Csaba

    2005-06-06

    Guiding of relativistically intense laser beams in preformed plasma channels is discussed for development of GeV-class laser accelerators. Experiments using a channel guided laser wakefield accelerator (LWFA) at LBNL have demonstrated that near mono-energetic 100 MeV-class electron beams can be produced with a 10 TW laser system. Analysis, aided by particle-in-cell simulations, as well as experiments with various plasma lengths and densities, indicate that tailoring the length of the accelerator, together with loading of the accelerating structure with beam, is the key to production of mono-energetic electron beams. Increasing the energy towards a GeV and beyond will require reducing the plasma density and design criteria are discussed for an optimized accelerator module. The current progress and future directions are summarized through comparison with conventional accelerators, highlighting the unique short term prospects for intense radiation sources based on laser-driven plasma accelerators.

  4. Laser guiding for GeV laser-plasma accelerators.

    PubMed

    Leemans, Wim; Esarey, Eric; Geddes, Cameron; Schroeder, Carl; Tóth, Csaba

    2006-03-15

    Guiding of relativistically intense laser beams in preformed plasma channels is discussed for development of GeV-class laser accelerators. Experiments using a channel guided laser wakefield accelerator at Lawrence Berkeley National Laboratory (LBNL) have demonstrated that near mono-energetic 100 MeV-class electron beams can be produced with a 10 TW laser system. Analysis, aided by particle-in-cell simulations, as well as experiments with various plasma lengths and densities, indicate that tailoring the length of the accelerator, together with loading of the accelerating structure with beam, is the key to production of mono-energetic electron beams. Increasing the energy towards a GeV and beyond will require reducing the plasma density and design criteria are discussed for an optimized accelerator module. The current progress and future directions are summarized through comparison with conventional accelerators, highlighting the unique short-term prospects for intense radiation sources based on laser-driven plasma accelerators. PMID:16483950

  5. Control of laser-wakefield acceleration by the plasma-density profile.

    PubMed

    Pukhov, A; Kostyukov, I

    2008-02-01

    We show that both the maximum energy gain and the accelerated beam quality can be efficiently controlled by the plasma-density profile. Choosing a proper density gradient one can uplift the dephasing limitation and keep the phase synchronism between the bunch of relativistic particles and the plasma wave over extended distances. Putting electrons into the n th wake period behind the driving laser pulse, the maximum energy gain is increased by the factor, which is proportional to n, over that in the case of uniform plasma. Layered plasma is suggested to keep the resonant condition for laser-wakefield excitation. The acceleration is limited then by laser depletion rather than by dephasing. Further, we show that the natural energy spread of the particle bunch acquired at the acceleration stage can be effectively removed by a matched deceleration stage, where a larger plasma density is used. PMID:18352081

  6. Observations of cometary plasma wave phenomena

    NASA Technical Reports Server (NTRS)

    Scarf, F. L.; Coroniti, F. V.; Kennel, C. F.; Gurnett, D. A.; Ip, W.-H.; Smith, E. J.

    1986-01-01

    The ICE plasma wave investigation utilized very long electric antennas (100 m tip-to-tip) and a very high sensitivity magnetic search coil to obtain significant local information on plasma physics phenomena occurring in the distant pickup regions of Comet Giacobini-Zinner and Comet Halley; and information on the processes that developed in the coma and tail of Giacobini-Zinner. The ICE plasma wave measurements associated with both comet encounters are summarized, and high sensitivity ICE observations are related to corresponding measurements from the other Halley spacecraft.

  7. Magnetic circuit for hall effect plasma accelerator

    NASA Technical Reports Server (NTRS)

    Manzella, David H. (Inventor); Jacobson, David T. (Inventor); Jankovsky, Robert S. (Inventor); Hofer, Richard (Inventor); Peterson, Peter (Inventor)

    2009-01-01

    A Hall effect plasma accelerator includes inner and outer electromagnets, circumferentially surrounding the inner electromagnet along a thruster centerline axis and separated therefrom, inner and outer magnetic conductors, in physical connection with their respective inner and outer electromagnets, with the inner magnetic conductor having a mostly circular shape and the outer magnetic conductor having a mostly annular shape, a discharge chamber, located between the inner and outer magnetic conductors, a magnetically conducting back plate, in magnetic contact with the inner and outer magnetic conductors, and a combined anode electrode/gaseous propellant distributor, located at a bottom portion of the discharge chamber. The inner and outer electromagnets, the inner and outer magnetic conductors and the magnetically conducting back plate form a magnetic circuit that produces a magnetic field that is largely axial and radially symmetric with respect to the thruster centerline.

  8. On the propagation of acceleration waves in incompressible hyperelastic solids

    NASA Astrophysics Data System (ADS)

    Gültop, T.

    2003-07-01

    The conditions for the propagation of acceleration waves (sound waves) in incompressible elastic media undergoing finite deformation are investigated. The incompressible hyperelastic solid media is considered in accordance with the general constitutive theory of materials subject to internal mechanical constraints. The equation of motion of acceleration waves is obtained using the theory of singular surfaces. A general comparison is made between the magnitudes of the propagation speeds of waves in incompressible and unconstrained solid media by the use of Mandel's inequalities. The magnitudes of the speeds of propagation of acceleration waves in the incompressible hyperelastic material classes of neo-Hookean, Mooney-Rivlin, and St. Venant-Kirchhoff solids are determined. Comparisons are made of the specific results concerning the magnitudes of wave propagation speeds making use of the corresponding material parameters.

  9. Electron acceleration by femtosecond laser interaction with micro-structured plasmas

    NASA Astrophysics Data System (ADS)

    Goers, Andy James

    Laser-driven accelerators are a promising and compact alternative to RF accelerator technology for generating relativistic electron bunches for medical, scientific, and security applications. This dissertation presents three experiments using structured plasmas designed to advance the state of the art in laser-based electron accelerators, with the goal of reducing the energy of the drive laser pulse and enabling higher repetition rate operation with current laser technology. First, electron acceleration by intense femtosecond laser pulses in He-like nitrogen plasma waveguides is demonstrated. Second, significant progress toward a proof of concept realization of quasi-phasematched direct acceleration (QPM-DLA) is presented. Finally, a laser wakefield accelerator at very high plasma density is studied, enabling relativistic electron beam generation with ˜10 mJ pulse energies. Major results from these experiments include: • Acceleration of electrons up to 120 MeV from an ionization injected wakefield accelerator driven in a 1.5 mm long He-like nitrogen plasma waveguide • Guiding of an intense, quasi-radially polarized femtosecond laser pulse in a 1 cm plasma waveguide. This pulse provides a strong drive field for the QPM-DLA concept. • Wakefield acceleration of electrons up to ˜10 MeV with sub-terawatt, ˜10 mJ pulses interacting with a thin (˜200 mum), high density (>1020 cm-3) plasma. • Observation of an intense, coherent, broadband wave breaking radiation flash from a high plasma density laser wakefield accelerator. The flash radiates > 1% of the drive laser pulse energy in a bandwidth consistent with half-cycle (˜1 fs) emission from violent unidirectional acceleration of electron bunches from rest. These results open the way to high repetition rate (>˜kHz) laser-driven generation of relativistic electron beams with existing laser technology.

  10. Precise charge measurement for laser plasma accelerators

    NASA Astrophysics Data System (ADS)

    Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Sokollik, Thomas; Shiraishi, Satomi; van Tilborg, Jeroen; Smith, Alan; Rodgers, Dave; Donahue, Rick; Byrne, Warren; Leemans, Wim

    2011-10-01

    A comprehensive study of charge diagnostics was conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). The electron energy dependence of a scintillating screen (Lanex Fast) was studied with sub-nanosecond electron beams ranging from 106 MeV to 1522 MeV at the Lawrence Berkeley National Laboratory Advanced Light Source (ALS) synchrotron booster accelerator. Using an integrating current transformer as a calibration reference, the sensitivity of the Lanex Fast was found to decrease by 1% per 100 MeV increase of the energy. By using electron beams from LPA, cross calibrations of the charge were carried out with an integrating current transformer, scintillating screen (Lanex from Kodak), and activation based measurement. The diagnostics agreed within ~8%, showing that they all can provide accurate charge measurements for LPAs provided necessary cares. Work supported by the Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  11. Electrical Coupling Efficiency of Inductive Plasma Accelerators

    NASA Technical Reports Server (NTRS)

    Martin, Adam K.; Eskridge, Richard H.

    2005-01-01

    A single-stage pulsed inductive plasma accelerator is modeled as an inductive mass-driver. The plasma is treated as a rigid slug, which acts as the armature. The system is a transformer, with the drive coil serving as the primary and the slug as the secondary. We derive a set of coupled dynamic-circuit equations, which depend on five dimensionless coefficients, and on the functional form of the mutual inductance profile, M (z). For a given coil geometry, M (z) was determined experimentally and compared to the results of calculations carried out with QuickField. The equations are solved with various coefficient values, in order to determine the conditions that yield high efficiencies. It was found that the coupling efficiency can be quite high and likely scales with power, although this does not preclude operation at lower power with acceptable efficiency. The effect of an imbedded magnetic bias flux, as for the case of a plasmoid thruster, was also included in the calculations.

  12. Plasma acceleration using a radio frequency self-bias effect

    NASA Astrophysics Data System (ADS)

    Rafalskyi, D.; Aanesland, A.

    2015-06-01

    In this work plasma acceleration using a RF self-bias effect is experimentally studied. The experiments are conducted using a novel plasma accelerator system, called Neptune, consisting of an inductively coupled plasma source and a RF-biased set of grids. The plasma accelerator can operate in a steady state mode, producing a plasma flow with separately controlled plasma flux and velocity without any magnetic configuration. The operating pressure at the source output is as low as 0.2 mTorr and can further be decreased. The ion and electron flows are investigated by measuring the ion and electron energy distribution functions both space resolved and with different orientations with respect to the flow direction. It is found that the flow of electrons from the source is highly anisotropic and directed along the ion flow and this global flow of accelerated plasma is well localized in the plasma transport chamber. The maximum flux is about 7.5.1015 ions s-1 m-2 (at standard conditions) on the axis and decreasing to almost zero at a radial distances of more than 15 cm from the flow axis. Varying the RF acceleration voltage in the range 20-350 V, the plasma flow velocity can be changed between 10 and 35 km/s. The system is prospective for different technology such as space propulsion and surface modification and also interesting for fundamental studies for space-related plasma simulations and investigation of the dynamo effect using accelerated rotating plasmas.

  13. Interaction of High Intensity Electromagnetic Waves with Plasmas

    SciTech Connect

    G. Shvets

    2008-10-03

    The focus of our work during the duration of this grant was on the following areas: (a) the fundamental plasma physics of intense laser-plasma interactions, including the nonlinear excitation of plasma waves for accelerator applications, as well as the recently discovered by us phenomenon of the relativistic bi-stability of relativistic plasma waves driven by a laser beatwave; (b) interaction of high power microwave beams with magnetized plasma, including some of the recently discovered by us phenomena such as the Undulator Induced Transparency (UIT) as well as the new approaches to dynamic manipulation of microwave pulses; (c) investigations of the multi-color laser pulse interactions in the plasma, including the recently discovered by us phenomenon of Electromagnetic Cascading (EC) and the effect of the EC of three-dimensional dynamics of laser pulses (enhanced/suppressed selffocusing etc.); (d) interaction of high-current electron beams with the ambient plasma in the context of Fast Ignitor (FI) physics, with the emphasis on the nonlinear dynamics of the Weibel instability and beam filamentation.

  14. STOCHASTIC PARTICLE ACCELERATION AND THE PROBLEM OF BACKGROUND PLASMA OVERHEATING

    SciTech Connect

    Chernyshov, D. O.; Dogiel, V. A.; Ko, C. M.

    2012-11-10

    The origin of hard X-ray (HXR) excess emission from clusters of galaxies is still an enigma, whose nature is debated. One of the possible mechanisms to produce this emission is the bremsstrahlung model. However, previous analytical and numerical calculations showed that in this case the intracluster plasma had to be overheated very fast because suprathermal electrons emitting the HXR excess lose their energy mainly by Coulomb losses, i.e., they heat the background plasma. It was concluded also from these investigations that it is problematic to produce emitting electrons from a background plasma by stochastic (Fermi) acceleration because the energy supplied by external sources in the form of Fermi acceleration is quickly absorbed by the background plasma. In other words, the Fermi acceleration is ineffective for particle acceleration. We revisited this problem and found that at some parameter of acceleration the rate of plasma heating is rather low and the acceleration tails of nonthermal particles can be generated and exist for a long time while the plasma temperature is almost constant. We showed also that for some regime of acceleration the plasma cools down instead of being heated up, even though external sources (in the form of external acceleration) supply energy to the system. The reason is that the acceleration withdraws effectively high-energy particles from the thermal pool (analog of Maxwell demon).

  15. Stochastic ion acceleration by beating electrostatic waves.

    PubMed

    Jorns, B; Choueiri, E Y

    2013-01-01

    A study is presented of the stochasticity in the orbit of a single, magnetized ion produced by the particle's interaction with two beating electrostatic waves whose frequencies differ by the ion cyclotron frequency. A second-order Lie transform perturbation theory is employed in conjunction with a numerical analysis of the maximum Lyapunov exponent to determine the velocity conditions under which stochasticity occurs in this dynamical system. Upper and lower bounds in ion velocity are found for stochastic orbits with the lower bound approximately equal to the phase velocity of the slower wave. A threshold condition for the onset of stochasticity that is linear with respect to the wave amplitudes is also derived. It is shown that the onset of stochasticity occurs for beating electrostatic waves at lower total wave energy densities than for the case of a single electrostatic wave or two nonbeating electrostatic waves. PMID:23410446

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

    NASA Technical Reports Server (NTRS)

    Ofman, Leon

    2001-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Ofman, Leon

    2000-01-01

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

  18. Excitation of chirping whistler waves in a laboratory plasma

    NASA Astrophysics Data System (ADS)

    An, Xin

    2015-11-01

    Whistler mode chorus emissions with a characteristic frequency chirp largely control the dynamic variability of the Earth's outer radiation belt. 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. Here, we report on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced using a gyrating beam of energetic electrons injected into a cold plasma. It is shown that there is an optimal beam density for frequency chirps, which indicates the existence of optimum wave amplitude for the generation of chirps. Also, frequency chirps only occur for a very narrow range of ratio of fpe /fce , similar to that observed in space. Strong magnetic field gradient, which prohibits the formation of phase space electron hole, disrupts frequency chirps as expected. Broadband whistler waves similar to magnetospheric hiss are also observed at relatively high plasma density. Their mode structures are identified by the phase-correlation technique. It is demonstrated that broadband whistlers are excited through Landau resonance, cyclotron resonance and anomalous cyclotron resonance. Wave growth rate and wave normal angle given by linear theory are consistent with experimental results in general. Preliminary particle-in-cell simulation captures the linear theory prediction of broadband whistlers and also gives important information on the evolution of electron distribution function. Supported by NSF/DOE Plasma Partnership grant DE-SC0010578.

  19. High quality electron beams from a plasma channel guided laser wakefield accelerator

    SciTech Connect

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

    2004-07-08

    Laser driven accelerators, in which particles are accelerated by the electric field of a plasma wave driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV/m. These fields are thousands of times those achievable in conventional radiofrequency (RF) accelerators, spurring interest in laser accelerators as compact next generation sources of energetic electrons and radiation. To date however, acceleration distances have been severely limited by lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance results in low energy beams with 100% electron energy spread, limiting applications. Here we demonstrate that a relativistically intense laser can be guided by a preformed plasma density channel and that the longer propagation distance can result in electron beams of percent energy spread with low emittance and increased energy, containing >10{sup 9} electrons above 80 MeV. The preformed plasma channel technique forms the basis of a new class of accelerators, combining beam quality comparable to RF accelerators with the high gradients of laser accelerators to produce compact tunable high brightness electron and radiation sources.

  20. Laboratory simulation of ion acceleration in the presence of lower hybrid waves

    NASA Astrophysics Data System (ADS)

    McWilliams, R.; Koslover, R.; Boehmer, H.; Rynn, N.

    Ion acceleration perpendicular to the geomagnetic field has been observed by satellites and rockets in the suprauroral region. Also found are broadband lower-hybrid waves, and, at higher altitudes, conical upward-flowing ion distributions. The UCI Q-machine has been used to simulate the effect of lower hybrid waves on ion acceleration. Laser induced fluorescence was used for high resolution, non-perturbing measurements of the ion velocity distribution function. The plasma consisted of a 1 m long, 5 cm diameter barium plasma of densities on the order of 1010 per cm3 contained by a 3 kG magnetic field. Substantial changes in the perpendicular ion distribution were found. Main-body ion heating occurred along with non-maxwellian tail production. Over a 10 dB change in input wave power we observed up to a factor of 3 enhancement in main-body ion temperature.

  1. Nonlinear whistler wave scattering in space plasmas

    SciTech Connect

    Yukhimuk, V.; Roussel-Dupre, R.

    1997-04-01

    In this paper the evolution of nonlinear scattering of whistler mode waves by kinetic Alfven waves (KAW) in time and two spatial dimensions is studied analytically. The authors suggest this nonlinear process as a mechanism of kinetic Alfven wave generation in space plasmas. This mechanism can explain the dependence of Alfven wave generation on whistler waves observed in magnetospheric and ionospheric plasmas. The observational data show a dependence for the generation of long periodic pulsations Pc5 on whistler wave excitation in the auroral and subauroral zone of the magnetosphere. This dependence was first observed by Ondoh T.I. For 79 cases of VLF wave excitation registered by Ondoh at College Observatory (L=64.6 N), 52 of them were followed by Pc5 geomagnetic pulsation generation. Similar results were obtained at the Loparskaia Observatory (L=64 N) for auroral and subauroral zone of the magnetosphere. Thus, in 95% of the cases when VLF wave excitation occurred the generation of long periodic geomagnetic pulsations Pc5 were observed. The observations also show that geomagnetic pulsations Pc5 are excited simultaneously or insignificantly later than VLF waves. In fact these two phenomena are associated genetically: the excitation of VLF waves leads to the generation of geomagnetic pulsations Pc5. The observations show intensive generation of geomagnetic pulsations during thunderstorms. Using an electromagnetic noise monitoring system covering the ULF range (0.01-10 Hz) A.S. Fraser-Smith observed intensive ULF electromagnetic wave during a large thunderstorm near the San-Francisco Bay area on September 23, 1990. According to this data the most significant amplification in ULF wave activity was observed for waves with a frequency of 0.01 Hz and it is entirely possible that stronger enhancements would have been measured at lower frequencies.

  2. Laser-seeded modulation instability in a proton driver plasma wakefield accelerator

    SciTech Connect

    Siemon, Carl; Khudik, Vladimir; Austin Yi, S.; Shvets, Gennady; Pukhov, Alexander

    2013-10-15

    A new method for initiating the modulation instability (MI) of a proton beam in a proton driver plasma wakefield accelerator using a short laser pulse preceding the beam is presented. A diffracting laser pulse is used to produce a plasma wave that provides a seeding modulation of the proton bunch with the period equal to that of the plasma wave. Using the envelope description of the proton beam, this method of seeding the MI is analytically compared with the earlier suggested seeding technique that involves an abrupt truncation of the proton bunch. The full kinetic simulation of a realistic proton bunch is used to validate the analytic results. It is further used to demonstrate that a plasma density ramp placed in the early stages of the laser-seeded MI leads to its stabilization, resulting in sustained accelerating electric fields (of order several hundred MV/m) over long propagation distances (∼100–1000 m)

  3. Ion acceleration by Alfvén waves on auroral field lines

    NASA Astrophysics Data System (ADS)

    Bingham, Robert; Eliasson, Bengt; Tito Mendonça, José; Stenflo, Lennart

    2013-05-01

    Observations of ion acceleration along auroral field lines at the boundary of the plasma sheet and tail lobe of the Earth show that the energy of the ions increases with decreasing density. The observations can be explained by ion acceleration through Landau resonance with kinetic Alfvén waves (KAWs) such that kA·vi = ωA, where kA is the wave vector, vi is the ion resonance velocity and ωA is the Alfvén wave frequency. The ion resonance velocities are proportional to the Alfvén velocity which increases with decreasing density. This is in agreement with the data if the process is occurring at the plasma sheet tail lobe boundary. A quasi-linear theory of ion acceleration by KAWs is presented. These ions propagate both down towards and away from the Earth. The paths of the Freja and Polar satellites indicate that the acceleration takes place between the two satellites, between 1Re and 5Re. The downward propagating ions develop a horseshoe-type of distribution which has a positive slope in the perpendicular direction. This type of distribution can produce intense lower hybrid wave activity, which is also observed. Finally, the filamentation of shear Alfvén waves is considered. It may be responsible for large-scale density striations. In memory of Padma Kant Shukla, a great scientist and a good friend.

  4. Whistler Wave Turbulence in Solar Wind Plasma

    NASA Astrophysics Data System (ADS)

    Shaikh, Dastgeer; Zank, G. P.

    2010-03-01

    Whistler waves are present in solar wind plasma. These waves possess characteristic turbulent fluctuations that are characterized typically by the frequency and length scales that are respectively bigger than ion gyro frequency and smaller than ion gyro radius. The electron inertial length is an intrinsic length scale in whistler wave turbulence that distinguishably divides the high frequency solar wind turbulent spectra into scales smaller and bigger than the electron inertial length. We present nonlinear three dimensional, time dependent, fluid simulations of whistler wave turbulence to investigate their role in solar wind plasma. Our simulations find that the dispersive whistler modes evolve entirely differently in the two regimes. While the dispersive whistler wave effects are stronger in the large scale regime, they do not influence the spectral cascades which are describable by a Kolmogorov-like k-7/3 spectrum. By contrast, the small scale turbulent fluctuations exhibit a Navier-Stokes like evolution where characteristic turbulent eddies exhibit a typical k-5/3 hydrodynamic turbulent spectrum. By virtue of equipartition between the wave velocity and magnetic fields, we quantify the role of whistler waves in the solar wind plasma fluctuations.

  5. Nonlinear pulse propagation and phase velocity of laser-driven plasma waves

    SciTech Connect

    Schroeder, Carl B.; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2011-03-25

    Laser evolution and plasma wave excitation by a relativistically-intense short-pulse laser in underdense plasma are investigated in the broad pulse limit, including the effects of pulse steepening, frequency red-shifting, and energy depletion. The nonlinear plasma wave phase velocity is shown to be significantly lower than the laser group velocity and further decreases as the pulse propagates owing to laser evolution. This lowers the thresholds for trapping and wavebreaking, and reduces the energy gain and efficiency of laser-plasma accelerators that use a uniform plasma profile.

  6. Beat wave injection of electrons into plasma waves using two interfering laser pulses

    SciTech Connect

    Fubiani, G.; Esarey, E.; Schroeder, C.B.; Leemans, W.P.

    2004-03-04

    An electron injector concept that uses a single injection laser pulse colliding with a pump laser pulse in a plasma is analyzed. The pump pulse generates a large amplitude laser wakefield (plasma wave). The counter propagating injection pulse collides with the pump laser pulse to generate a beat wave with a slow phase velocity. The ponderomotive force of the slow beat wave is responsible for injecting plasma electrons into the wakefield near the back of the pump pulse. Test particle simulations indicate that significant amounts of charge can be trapped and accelerated ({approx} 10 pC). For higher charge, beam loading limits the validity of the simulations. The accelerated bunches are ultrashort ({approx} 1 fs) with good beam quality (relative energy spread of a few percent at a mean energy of {approx} 10 MeV and a normalized rms emittance on the order 0.4 mm.mrad). The effects of interaction angle and polarization are also explored, e.g., efficient trapping can occur for near-collinear geometries. Beat wave injection using a single injection pulse has the advantages of simplicity, ease of experimental implementation, and requires modest laser intensity I {approx_equal} 8.8 x 10{sup 17} W/cm{sup 2}.

  7. Beat wave injection of electrons into plasma waves using two interfering laser pulses.

    PubMed

    Fubiani, G; Esarey, E; Schroeder, C B; Leemans, W P

    2004-01-01

    An electron injector concept that uses a single injection laser pulse colliding with a pump laser pulse in a plasma is analyzed. The pump pulse generates a large amplitude laser wakefield (plasma wave). The counterpropagating injection pulse collides with the pump laser pulse to generate a beat wave with a slow phase velocity. The ponderomotive force of the slow beat wave is responsible for injecting plasma electrons into the wakefield near the back of the pump pulse. Test particle simulations indicate that significant amounts of charge can be trapped and accelerated ( approximately 10 pC). For higher charge, beam loading limits the validity of the simulations. The accelerated bunches are ultrashort ( approximately 1 fs) with good beam quality (relative energy spread of a few percent at a mean energy of approximately 10 MeV and a normalized root-mean-square emittance on the order 0.4 mm mrad). The effects of interaction angle and polarization are also explored, e.g., efficient trapping can occur for near-collinear geometries. Beat wave injection using a single injection pulse has the advantages of simplicity, ease of experimental implementation, and requires modest laser intensity < 10(18) W/cm(2). PMID:15324173

  8. Quasi-linear heating and acceleration in bi-Maxwellian plasmas

    SciTech Connect

    Hellinger, Petr; Trávníček, Pavel M.

    2013-12-15

    Quasi-linear acceleration and heating rates are derived for drifting bi-Maxwellian distribution functions in a general nonrelativistic case for arbitrary wave vectors, propagation angles, and growth/damping rates. The heating rates in a proton-electron plasma due to ion-cyclotron/kinetic Alfvén and mirror waves for a wide range of wavelengths, directions of propagation, and growth or damping rates are explicitly computed.

  9. Cascade focusing in the beat-wave accelerator

    SciTech Connect

    Gibbon, P.; Bell, A.R.

    1988-10-03

    The 2D wave-envelope equationf for the beat-wave--cascade system are studied analytically and numerically. An expression for the mean square width of the cascade envelope is obtained, and is used to predict the long-term behavior of the waves. The amplitude or a resonantly driven plasma wave falls significantly over a stage length due to enhanced diffraction of the cascade envelope. Conversely, detuning the pumps from the plasma frequency can lead to focusing of the envelope and a corresponding increase in plasmon amplitude of up to 200% over the same distance.

  10. Assessment of thermodynamic parameters of plasma shock wave

    NASA Astrophysics Data System (ADS)

    Vasileva, O. V.; Isaev, Yu N.; Budko, A. A.; Filkov, A. I.

    2014-11-01

    The work is devoted to the solution of the one-dimensional equation of hydraulic gas dynamics for the coaxial magneto plasma accelerator by means of Lax-Wendroff modified algorithm with optimum choice of the regularization parameter artificial viscosity. Replacement of the differential equations containing private derivatives is made by finite difference method. Optimum parameter of regularization artificial viscosity is added using the exact known decision of Soda problem. The developed algorithm of thermodynamic parameter calculation in a braking point is proved. Thermodynamic parameters of a shock wave in front of the plasma piston of the coaxial magneto plasma accelerator are calculated on the basis of the offered algorithm. Unstable high-frequency fluctuations are smoothed using modeling and that allows narrowing the ambiguity area. Results of calculation of gas dynamic parameters in a point of braking coincide with literary data. The chart 3 shows the dynamics of change of speed and thermodynamic parameters of a shock wave such as pressure, density and temperature just before the plasma piston.

  11. Accelerated Bone Repair After Plasma Laser Corticotomies

    PubMed Central

    Leucht, Philipp; Lam, Kentson; Kim, Jae-Beom; Mackanos, Mark A.; Simanovskii, Dmitrii M.; Longaker, Michael T.; Contag, Christopher H.; Schwettman, H Alan; Helms, Jill A.

    2007-01-01

    Objective: To reveal, on a cellular and molecular level, how skeletal regeneration of a corticotomy is enhanced when using laser-plasma mediated ablation compared with conventional mechanical tissue removal. Summary Background Data: Osteotomies are well-known for their most detrimental side effect: thermal damage. This thermal and mechanical trauma to adjacent bone tissue can result in the untoward consequences of cell death and eventually in a delay in healing. Methods: Murine tibial corticotomies were performed using a conventional saw and a Ti:Sapphire plasma-generated laser that removes tissue with minimal thermal damage. Our analyses began 24 hours after injury and proceeded to postsurgical day 6. We investigated aspects of wound repair ranging from vascularization, inflammation, cell proliferation, differentiation, and bone remodeling. Results: Histology of mouse corticotomy sites uncovered a significant difference in the onset of bone healing; whereas laser corticotomies showed abundant bone matrix deposition at postsurgical day 6, saw corticotomies only exhibited undifferentiated tissue. Our analyses uncovered that cutting bone with a saw caused denaturation of the collagen matrix due to thermal effects. This denatured collagen represented an unfavorable scaffold for subsequent osteoblast attachment, which in turn impeded deposition of a new bony matrix. The matrix degradation induced a prolonged inflammatory reaction at the cut edge to create a surface favorable for osteochondroprogenitor cell attachment. Laser corticotomies were absent of collagen denaturation, therefore osteochondroprogenitor cell attachment was enabled shortly after surgery. Conclusion: In summary, these data demonstrate that corticotomies performed with Ti:Sapphire lasers are associated with a reduced initial inflammatory response at the injury site leading to accelerated osteochondroprogenitor cell migration, attachment, differentiation, and eventually matrix deposition. PMID:17592303

  12. Shock Wave Dynamics in Weakly Ionized Plasmas

    NASA Technical Reports Server (NTRS)

    Johnson, Joseph A., III

    1999-01-01

    An investigation of the dynamics of shock waves in weakly ionized argon plasmas has been performed using a pressure ruptured shock tube. The velocity of the shock is observed to increase when the shock traverses the plasma. The observed increases cannot be accounted for by thermal effects alone. Possible mechanisms that could explain the anomalous behavior include a vibrational/translational relaxation in the nonequilibrium plasma, electron diffusion across the shock front resulting from high electron mobility, and the propagation of ion-acoustic waves generated at the shock front. Using a turbulence model based on reduced kinetic theory, analysis of the observed results suggest a role for turbulence in anomalous shock dynamics in weakly ionized media and plasma-induced hypersonic drag reduction.

  13. Nonplanar waves with electronegative dusty plasma

    SciTech Connect

    Zobaer, M. S.; Mukta, K. N.; Nahar, L.; Mamun, A. A.; Roy, N.

    2013-04-15

    A rigorous theoretical investigation has been made of basic characteristics of the nonplanar dust-ion-acoustic shock and solitary waves in electronegative dusty plasma containing Boltzmann electrons, Boltzmann negative ions, inertial positive ions, and charge fluctuating (negatively charged) stationary dust. The Burgers' and Korteweg-de Vries (K-dV) equations, which is derived by reductive perturbation technique, is numerically solved to examine the effects of nonplanar geometry on the basic features of the DIA shock and solitary waves formed in the electronegative dusty plasma. The implications of the results (obtained from this investigation) in space and laboratory experiments are briefly discussed.

  14. Modulation of whistler waves in nonthermal plasmas

    SciTech Connect

    Rios, L. A.; Galvao, R. M. O.

    2011-02-15

    The modulation of whistler waves in nonthermal plasmas is investigated. The dynamics of the magnetized plasma is described by the fluid equations and the electron velocity distribution function is modeled via a nonthermal {kappa} distribution. A multiscale perturbation analysis based on the Krylov-Bogoliubov-Mitropolsky method is carried out and the nonlinear Schroedinger equation governing the modulation of the high-frequency whistler is obtained. The effect of the superthermal electrons on the stability of the wave envelope and soliton formation is discussed and a comparison with previous results is presented.

  15. The Unified Radio and Plasma wave investigation

    NASA Technical Reports Server (NTRS)

    Stone, R. G.; Bougeret, J. L.; Caldwell, J.; Canu, P.; De Conchy, Y.; Cornilleau-Wehrlin, N.; Desch, M. D.; Fainberg, J.; Goetz, K.; Goldstein, M. L.

    1992-01-01

    The scientific objectives of the Ulysses Unified Radio and Plasma wave (URAP) experiment are twofold: (1) the determination of the direction, angular size, and polarization of radio sources for remote sensing of the heliosphere and the Jovian magnetosphere and (2) the detailed study of local wave phenomena, which determine the transport coefficients of the ambient plasma. A brief discussion of the scientific goals of the experiment is followed by a comprehensive description of the instrument. The URAP sensors consist of a 72.5 m electric field antenna in the spin plane, a 7.5-m electric field monopole along the spin axis of a pair of orthogonal search coil magnetic antennas. The various receivers, designed to encompass specific needs of the investigation, cover the frequency range from dc to 1 MHz. A relaxation sounder provides very accurate electron density measurements. Radio and plasma wave observations are shown to demonstrate the capabilities and limitations of the URAP instruments: radio observations include solar bursts, auroral kilometric radiation, and Jovian bursts; plasma waves include Langmuir waves, ion acousticlike noise, and whistlers.

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

    NASA Astrophysics Data System (ADS)

    Howard, Stephen James

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

  17. CO2 Laser Beat-Wave Experiment in an Unmagnetized Plasma

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Hwang, David; Horton, Robert; Hong, Sean; Evans, Russell

    2012-10-01

    The ability to remotely generate plasma current in dense plasmas is a basic yet important investigation in experimental plasma physics and fusion energy research. It is even more advantageous if the wave penetration is independent of the electron acceleration process. Plasma current can be generated through beat-wave mixing process by launching two intense electromagnetic waves (φ>>φpe) into plasma. The beat wave formation process can be efficient if the difference frequency of the two pump waves is matched to a local resonant frequency of the medium, i.e. in this case the local plasma frequency. Beat wave can accelerate plasma electrons via quasi-linear Landau process, which has been demonstrated in a low-density plasma using microwaves.footnotetextRogers, J. H. and Hwang, D. Q., Phys. Rev. Lett. v68 p3877 (1992). The CO2 lasers provide the high tunability for the wave-particle interaction experiment at a variety of plasma densities with plasma frequency in THz range. Two sections of Lumonics TEA CO2 lasers have been modified to serve as the two pump wave sources with peak power over 100MW. The development of the tunable CO2 lasers, a high-density plasma target source and diagnostics system will be presented. The initial results of unbalanced beat-wave experiment using one high-power pulsed and one low-power CW CO2 lasers will be presented and discussed using the independent plasma source to control the φpe of the interaction region. This work is supported by U.S. DOE under Contract No. DE-FG02-10ER55083.

  18. Quasi-phasematched acceleration of electrons in a density modulated plasma waveguide

    NASA Astrophysics Data System (ADS)

    Yoon, Sung Jun

    Two quasi-phasematching schemes are proposed for efficient acceleration of electrons to relativistic energies using moderate intensity laser pulses. In the first scheme, Direct Laser Acceleration (DLA) in a corrugated plasma waveguide is proposed for acceleration of relativistic electrons with sub-terawatt laser systems, using the laser field directly as the accelerating field. The second scheme uses the fact that a plasma wakefield generated by an intense guided pulse in a corrugated plasma waveguide can accelerate relativistic electrons significantly beyond the well-known dephasing limit. In each case, particle-in-cell (PIC) simulations are used to validate the acceleration concept, demonstrating linear acceleration by either the phase matched laser field or phase-matched wakefield. In the phase matched wakefield case, theory and PIC simulations demonstrate a significant increase in energy gain compared to the standard laser wakefield acceleration (LWFA) scheme. Corrugated plasma waveguides can be generated by the interaction between an ionizing laser pulse and an atomic cluster flow interrupted by an array of thin wires,. When the collisional mean free path of the clusters is greater than the wire diameter, shadows of the periodically located wires are imparted on the cluster flow, leading to the production of axially modulated plasma waveguides after laser heating of the flow. This occurs when the population ratio of clusters to monomers in the gas is high. At other limit, dominated by gas monomer flow, shock waves generated off the wires by the supersonic gas flow disrupts modulated waveguide generation. Lastly, we experimentally demonstrate LWFA with ionization injection in a N5+ plasma waveguide. It is first shown that the plasma waveguide is almost completely composed of He-like nitrogen (N5+). It is then shown that intense pulse channeling in the plasma waveguide drives stronger wakefields, while the ionization injection process is critical to lowering the

  19. Wave Acceleration Induced Sediment Transport in the Surf Zone

    NASA Astrophysics Data System (ADS)

    Hoefel, F.; Elgar, S.

    2002-12-01

    A bedload sediment transport formulation (Drake and Calantoni, 2001) that accounts for the effects of near-bottom wave-orbital velocity acceleration skewness predicts onshore sandbar migration observed near Duck, NC. Including acceleration effects in an energetics sediment transport model results in improved skill in reproducing cross-shore sandbar migration patterns observed over a 40 day period during which the bar moved both offshore in storms and onshore between storms. These results suggest that skewed acceleration time series, associated with the pitched forward shapes of nearly breaking and broken waves, play an important role in wave-induced sediment transport in the surf zone. The passage of steep wave fronts results in spikes in acceleration when orbital velocities are directed onshore, producing strong horizontal pressure gradient forces that act on the sediment. In contrast to velocity skewness, which remains approximately constant across the surf zone, acceleration skewness is observed to increase from small values offshore to a maximum near the bar crest, and then to decrease toward the shoreline, producing cross-shore spatial gradients in acceleration-driven transport that are consistent with erosion offshore and accretion onshore of the bar crest. As the sandbar migrates shoreward, the maximum of acceleration skewness also moves onshore, causing a positive feedback mechanism that promotes continued onshore sediment transport motion provided the forcing remains constant. Funded by ARO, ONR, and NOPP.

  20. Remote sensing of plasma injection and acceleration phenomena

    SciTech Connect

    Burch, J.L.

    1985-01-01

    Dynamics Explorer-1 High Altitude Plasma Instrument data have been used to investigate the injection of magnetosheath plasma into the polar cusp, the injection of auroral ion beams into the magnetosphere, and the acceleration of electrons transverse to the magnetic field direction, and the results are discussed. In the case of polar cusp plasmas, it is found that injection occurs at the high-latitude magnetopause, at geocentric distances near eight earth radii. In the case of auroral ion beams it is determined that ion bands are not produced by equatorial injection from the plasma sheet, but by the upward acceleration of ions from auroral acceleration regions. Finally, conical electron distributions are found to be consistent with transverse acceleration at altitudes of a thousand or more km, within or below the magnetic-field-aligned potential drops of the auroral acceleration regions.

  1. Operational plasma density and laser parameters for future colliders based on laser-plasma accelerators

    SciTech Connect

    Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2012-12-21

    The operational plasma density and laser parameters for future colliders based on laser-plasma accelerators are discussed. Beamstrahlung limits the charge per bunch at low plasma densities. Reduced laser intensity is examined to improve accelerator efficiency in the beamstrahlung-limited regime.

  2. Influence of electromagnetic oscillating two-stream instability on the evolution of laser-driven plasma beat-wave

    SciTech Connect

    Gupta, D. N.; Singh, K. P.; Suk, H.

    2007-01-15

    The electrostatic oscillating two-stream instability of laser-driven plasma beat-wave was studied recently by Gupta et al. [Phys. Plasmas 11, 5250 (2004)], who applied their theory to limit the amplitude level of a plasma wave in the beat-wave accelerator. As a self-generated magnetic field is observed in laser-produced plasma, hence, the electromagnetic oscillating two-stream instability may be another possible mechanism for the saturation of laser-driven plasma beat-wave. The efficiency of this scheme is higher than the former.

  3. Thin current sheets in collisionless plasma: Equilibrium structure, plasma instabilities, and particle acceleration

    SciTech Connect

    Zelenyi, L. M.; Malova, H. V.; Artemyev, A. V.; Popov, V. Yu.; Petrukovich, A. A.

    2011-02-15

    The review is devoted to plasma structures with an extremely small transverse size, namely, thin current sheets that have been discovered and investigated by spacecraft observations in the Earth's magnetotail in the last few decades. The formation of current sheets is attributed to complicated dynamic processes occurring in a collisionless space plasma during geomagnetic perturbations and near the magnetic reconnection regions. The models that describe thin current structures in the Earth's magnetotail are reviewed. They are based on the assumption of the quasi-adiabatic ion dynamics in a relatively weak magnetic field of the magnetotail neutral sheet, where the ions can become unmagnetized. It is shown that the ion distribution can be represented as a function of the integrals of particle motion-the total energy and quasi-adiabatic invariant. Various modifications of the initial equilibrium are considered that are obtained with allowance for the currents of magnetized electrons, the contribution of oxygen ions, the asymmetry of plasma sources, and the effects related to the non-Maxwellian particle distributions. The theoretical results are compared with the observational data from the Cluster spacecraft mission. Various plasma instabilities developing in thin current sheets are investigated. The evolution of the tearing mode is analyzed, and the parameter range in which the mode can grow are determined. The paradox of complete stabilization of the tearing mode in current sheets with a nonzero normal magnetic field component is thereby resolved based on the quasi-adiabatic model. It is shown that, over a wide range of current sheet parameters and the propagation directions of large-scale unstable waves, various modified drift instabilities-kink and sausage modes-can develop in the system. Based on the concept of a turbulent electromagnetic field excited as a result of the development and saturation of unstable waves, a mechanism for charged particle acceleration in

  4. Staging Laser Plasma Accelerators for Increased Beam Energy

    SciTech Connect

    Panasenko, D.; Shu, A. J.; Schroeder, C. B.; Gonsalves, A. J.; Nakamura, K.; Matlis, N. H.; Cormier-Michel, E.; Plateau, G.; Lin, C.; Toth, C.; Geddes, C. G. R.; Esarey, E.; Leemans, W. P.

    2009-01-22

    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 10 m, 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.

  5. Staging laser plasma accelerators for increased beam energy

    SciTech Connect

    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.

  6. Collisional Drift Waves in Stellarator Plasmas

    SciTech Connect

    J.L.V. Lewandowski

    2003-10-07

    A computational study of resistive drift waves in the edge plasma of a stellarator with an helical magnetic axis is presented. Three coupled field equations, describing the collisional drift wave dynamics in the linear approximation, are solved as an initial-value problem along the magnetic field line. The magnetohydrodynamic equilibrium is obtained from a three-dimensional local equilibrium model. The use of a local magnetohydrodynamic equilibrium model allows for a computationally efficient systematic study of the impact of the magnetic field structure on drift wave stability.

  7. Stochastic gyroresonant electron acceleration on a low-beta plasma. II - Implications of thermal effects in a solar flare plasma

    NASA Technical Reports Server (NTRS)

    Miller, James A.; Steinacker, Juergen

    1992-01-01

    We consider the thermal damping of R and L waves under typical solar flare conditions. We find that the thermal particles cause rapid dissipation of the cyclotron waves, but do not affect whistlers and Alfven waves. The dissipation of electron cyclotron waves in particular leads to a threshold energy for acceleration which is about 10 times the thermal energy. Therefore, in the absence of an instability that excites these HF waves, a second mechanism is required in order to inject a sufficient number of electrons above the threshold energy and account for solar flare gamma-ray bremsstrahlung emission. We also find that the comoving gyroresonance, which occurs when the electron is in gyroresonance with an R wave whose group velocity equals the parallel electron velocity, can be realized by relativistic electrons if the plasma temperature is less than or approximately equal to 5,000,000 K.

  8. CO2 Laser Beat-Wave Current Drive in an Unmagnetized Plasma

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Hwang, David; Horton, Robert; Evans, Russell; Huang, Zhuo Fan; Hong, Sean

    2011-10-01

    The ability to remotely generate plasma current in dense plasmas is a basic yet important investigation in experimental plasma physics. Plasma current can be generated through nonlinear beat-wave mixing process by launching two intense electromagnetic waves into an unmagnetized plasma. The beat wave formation process is efficient if the difference frequency of the two pump waves corresponds to the local plasma frequency. Beat wave can accelerate plasma electrons via quasi-linear Landau process, which has been demonstrated in low-density plasma using micro-waves. The high tunability of the CO2 lasers provides many options for the wave-particle interaction experiment at a variety of CTIX plasma densities. Two sections of Lumonics TEA CO2 lasers have been modified at power over 100MW. The development of the tunable CO2 lasers and diagnostics system will be described. A high-density plasma test source and density diagnostics system will also be presented. This line of research will impact experiment such as the PLX facility under initial operation at Los Alamos National Lab. Supported by U.S. DOE Grant DE-FG02-10ER55083.

  9. Summary Report of Working Group 4: Plasma Wakefield Acceleration

    SciTech Connect

    Rosenzweig, J.B.; Seryi, A.; /SLAC

    2012-06-11

    This report gives a guide to the discussions of Working Group 4 of the 2010 Advanced Accelerator Concepts Workshop, which was devoted to theory, simulation and experimental issues associated with plasma wakefield acceleration (PWFA). Sessions were organized thematically in this group, concentrating on broad issues of: exploitation of future facilities such as FACET; pushing the accelerating gradient beyond the current frontier, to over a TeV/m; use of positively charged beams to drive plasma wakes; resonant excitation of the PWFA with pulse trains; beam-plasma instabilities; and injection and capture of electron beams into PWFA systems.

  10. Summary Report of Working Group 4: Plasma Wakefield Acceleration

    SciTech Connect

    Rosenzweig, J. B.; Seryi, A.

    2010-11-04

    This report gives a guide to the discussions of Working Group 4 of the 2010 Advanced Accelerator Concepts Workshop, which was devoted to theory, simulation and experimental issues associated with plasma wakefield acceleration (PWFA). Sessions were organized thematically in this group, concentrating on broad issues of: exploitation of future facilities such as FACET; pushing the accelerating gradient beyond the current frontier, to over a TeV/m; use of positively charged beams to drive plasma wakes; resonant excitation of the PWFA with pulse trains; beam-plasma instabilities; and injection and capture of electron beams into PWFA systems.

  11. The status and evolution of plasma Wakefield particle accelerators.

    PubMed

    Joshi, C; Mori, W B

    2006-03-15

    The status and evolution of the electron beam-driven Plasma Wakefield Acceleration scheme is described. In particular, the effects of the radial electric field of the wake on the drive beam such as multiple envelope oscillations, hosing instability and emission of betatron radiation are described. Using ultra-short electron bunches, high-density plasmas can be produced by field ionization by the electric field of the bunch itself. Wakes excited in such plasmas have accelerated electrons in the back of the drive beam to greater that 4 G eV in just 10 cm in experiments carried out at the Stanford Linear Accelerator Centre. PMID:16483949

  12. Study of a THz IFEL prebuncher for laser-plasma accelerators

    SciTech Connect

    Sung, C.; Tochitsky, S.Ya.; Ralph, J.; Joshi, C.; Musumeci, P.; Rosenzweig, J.B.; Pellegrini, C.

    2004-12-07

    For monoenergetic acceleration of electrons, the injected particles need to be bunched with the same periodicity as the accelerating structure. In a laser-driven plasma beatwave accelerator, the accelerating structure (plasma wave) is phase-locked to the CO2 beat-wave used to drive it. Using the same beat-wave to generate high power FIR radiation via difference frequency mixing in GaAs ensures that the radiation has the same phase relationship as the plasma wave before it saturates and detunes from the pump. Therefore, this radiation can be used to prebunch an existing electron beam based on an Inverse Free Electron Laser (IFEL) concept. Here we report the progress on the proposed THz microbunching experiment in the Neptune laboratory. A 50 cm long prebuncher is optimized using simulation codes for minimum FIR power required. The injected 5ps long electron beam is expected to form a series of 45 {mu}m long microbunches containing over 40% of the injected current after 1.6 m drift space following the undulator. Preliminary experimental results on THz generation are also presented.

  13. ISEE/ICE plasma wave data analysis

    NASA Technical Reports Server (NTRS)

    Greenstadt, E. W.

    1989-01-01

    The work performed for the period 1 Jan. 1985 to 30 Oct. 1989 is presented. The objective was to provide reduction and analysis of data from a scientific instrument designed to study solar wind and plasma wave phenomena on the International Sun Earth Explorer 3 (ISEE-3)/International Cometary Explorer (ICE) missions.

  14. Bounce harmonic Landau damping of plasma waves

    NASA Astrophysics Data System (ADS)

    Anderegg, F.; Affolter, M.; Kabantsev, A. A.; Dubin, D. H. E.; Ashourvan, A.; Driscoll, C. F.

    2016-05-01

    We present measurements of bounce harmonic Landau damping due to z-variations in the plasma potential, created by an azimuthally symmetric "squeeze" voltage Vs applied to the cylindrical wall. Traditional Landau damping on spatially uniform plasma is weak in regimes where the wave phase velocity vp h≡ω/k is large compared to the thermal velocity. However, z-variations in plasma density and potential create higher spatial harmonics, which enable resonant wave damping by particles with bounce-averaged velocities vp h/n , where n is an integer. In our geometry, the applied squeeze predominantly generates a resonance at vp h/3 . Wave-coherent laser induced fluorescence measurements of particle velocities show a distinctive Landau damping signature at vp h/3 , with amplitude proportional to the applied Vs. The measured (small amplitude) wave damping is then proportional to Vs2 , in quantitative agreement with theory over a range of 20 in temperature. Significant questions remain regarding "background" bounce harmonic damping due to ubiquitous confinement fields and regarding the saturation of this damping at large wave amplitudes.

  15. Relationship between Alfvén Wave and Quasi-Static Acceleration in Earth's Auroral Zone

    NASA Astrophysics Data System (ADS)

    Mottez, Fabrice

    2016-02-01

    There are two main categories of acceleration processes in the Earth's auroral zone: those based on quasi-static structures, and those based on Alfvén wave (AW). AWs play a nonnegligible role in the global energy budget of the plasma surrounding the Earth because they participate in auroral acceleration, and because auroral acceleration conveys a large portion of the energy flux across the magnetosphere. Acceleration events by double layers (DLs) and by AW have mostly been investigated separately, but many studies cited in this chapter show that they are not independent: these processes can occur simultaneously, and one process can be the cause of the other. The quasi-simultaneous occurrences of acceleration by AW and by quasi-static structures have been observed predominantly at the polar cap boundary of auroral arc systems, where often new bright arcs develop or intensify.

  16. Acceleration of soliton by nonlinear Landau damping of dust-helical waves

    SciTech Connect

    Ehsan, Zahida; Tsintsadze, Nodar L.; Vranjes, J.; Poedts, S.

    2009-05-15

    The problem of nonlinear Landau damping of helicon waves in dusty plasma in particular emphasis to the acceleration of soliton is presented here. This in the framework of a collisionless, anisotropic homogeneous dusty plasma in one dimension, can be well described by two coupled dynamical equations of the generalized Zakharov type, with one extra nonlocal term coming from Landau damping. Nonlinear-nonlocal term gives rise to essential contributions relative to the local term. Then under different conditions, kinetic nonlinear Schroedinger equation is constructed and nonlinear decrement is obtained for two cases. It is noticed that the time dependant term in the ponderomotive force plays a significant role for this kind of damping. Additionally, it is shown that nonlinear Landau damping leads to the amplitude modulation of dust helicon waves, further modulational instability, and maximal growth rate is obtained when the group velocity of the helicon wave reaches the dust-acoustic speed. It is demonstrated that how the nonlinear Landau damping leads to the acceleration of soliton, which is eventually slowed down after transferring some of its energy to the wave. Emission of dust-acoustic wave by accelerated soliton is discussed briefly.

  17. High-gradient acceleration of electrons in a plasma loaded wiggler

    SciTech Connect

    Maroli, C.; Petrillo, V.

    1995-12-31

    The interaction of an electron beam with a transverse electromagnetic field and an electrostatic wave in a plasma loaded wiggler is described by means of system of self-consistent nonlinear equations. We demonstrate that the system is able to sustain resonantly high-amplitude electrostatic waves with phase velocity c, which gives rise to high gradient acceleration of the electron beam. Both gradient and saturation value of the average gamma factor of the beam increase considerably with increasing magnetic field of the wiggler and plasma density.

  18. Electron Bernstein waves in spherical torus plasmas

    SciTech Connect

    Saveliev, A. N.

    2006-11-30

    Propagation and absorption of the electron Bernstein waves (EBWs) in spherical tokamaks (STs) have been intensively discussed in recent years because the EBWs coupled with an externally launched electromagnetic beam seem to be the only opportunity for microwave plasma heating and current drive in the electron cyclotron (EC) frequency range in the STs. The whole problem of the electron Bernstein heating and current drive (EBWHCD) in spherical plasmas is naturally divided into three major parts: coupling of incident electromagnetic waves (EMWs) to the EBWs near the upper hybrid resonance (UHR) surface, propagation and absorption of the EBWs in the plasma interior and generation of noninductive current driven by the EBWs. The present paper is a brief survey of the most important theoretical and numerical results on the issue of EBWs.

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

    SciTech Connect

    Ostrovsky, A.O.

    1993-11-01

    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.

  20. Electron trapping and acceleration by the plasma wakefield of a self-modulating proton beam

    SciTech Connect

    Lotov, K. V.; Sosedkin, A. P.; Petrenko, A. V.; Amorim, L. D.; Vieira, J.; Fonseca, R. A.; Silva, L. O.; Gschwendtner, E.; Muggli, P.

    2014-12-15

    It is shown that co-linear injection of electrons or positrons into the wakefield of the self-modulating particle beam is possible and ensures high energy gain. The witness beam must co-propagate with the tail part of the driver, since the plasma wave phase velocity there can exceed the light velocity, which is necessary for efficient acceleration. If the witness beam is many wakefield periods long, then the trapped charge is limited by beam loading effects. The initial trapping is better for positrons, but at the acceleration stage a considerable fraction of positrons is lost from the wave. For efficient trapping of electrons, the plasma boundary must be sharp, with the density transition region shorter than several centimeters. Positrons are not susceptible to the initial plasma density gradient.

  1. Particle Acceleration by Cme-driven Shock Waves

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1999-01-01

    In the largest solar energetic particle (SEP) events, acceleration occurs at shock waves driven out from the Sun by coronal mass ejections (CMEs). Peak particle intensities are a strong function of CME speed, although the intensities, spectra, and angular distributions of particles escaping the shock are highly modified by scattering on Alfven waves produced by the streaming particles themselves. Element abundances vary in complex ways because ions with different values of Q/A resonate with different parts of the wave spectrum, which varies with space and time. Just recently, we have begun to model these systematic variations theoretically and to explore other consequences of proton-generated waves.

  2. Constraints on Solar Wind Acceleration Mechanisms from Ulysses Plasma Observations: The First Polar Pass

    NASA Technical Reports Server (NTRS)

    Barnes, Aaron; Gazis, Paul R.; Phillips, John L.

    1995-01-01

    The mass flux density and velocity of the solar wind at polar latitudes can provide strong constraints on solar wind acceleration mechanisms. We use plasma observations from the first polar passage of the Ulysses spacecraft to investigate this question. We find that the mass flux density and velocity are too high to reconcile with acceleration of the solar wind by classical thermal conduction alone. Therefore acceleration of the high-speed must involve extended deposition of energy by some other mechanism, either as heat or as a direct effective pressure, due possibly to waves and/or turbulence, or completely non-classical heat transport.

  3. Pulse propagation and electron acceleration in a corrugated plasma channel.

    PubMed

    Palastro, J P; Antonsen, T M; Morshed, S; York, A G; Milchberg, H M

    2008-03-01

    A preformed plasma channel provides a guiding structure for laser pulses unbound by the intensity thresholds of standard waveguides. The recently realized corrugated plasma channel [Layer, Phys. Rev. Lett. 99, 035001 (2007)] allows for the guiding of laser pulses with subluminal spatial harmonics. These spatial harmonics can be phase matched to high energy electrons, making the corrugated plasma channel ideal for the acceleration of electrons. We present a simple analytic model of pulse propagation in a corrugated plasma channel and examine the laser-electron beam interaction. Simulations show accelerating gradients of several hundred MeV/cm for laser powers much lower than required by standard laser wakefield schemes. PMID:18517531

  4. Wave-particle interaction and peculiarities of propagation and emission of accelerated particles in solar flares

    NASA Astrophysics Data System (ADS)

    Stepanov, A. V.; Tsap, Yu. T.

    2006-08-01

    Consequences of wave-particle interaction in the propagation and emission of accelerated particles in solar flares are considered. i. Strong diffusion energetic particles on small-scale waves (Trakhtengerts 1984) gives time delays of gamma ray line emission vs hard X-ray emission when electron and protons are accelerated simultaneously. ii. Anomalous propagation of relativistic electrons along the flare loop with velocity of 30 times less compared with light velocity (Yokoyama et al 2002) is explained in terms of the collective effects of interaction of electrons with plasma turbulence. A cloud of high-energetic electrons responsible for microwave emission generates whistler waves and a turbulent "wall" in the loop is formed. The electrons undergo strong resonant scattering and the emission front propagates with the wave phase velocity, which is much lower than particle velocity. iii. Absence of linear polarization (≤ 0.07%) in Hα emission of some flares (Bianda et al 2005) is interpreted in terms of pitch-angle scattering of proton beams on small-scale Alfven waves. References Bianda M., Benz F.O., Stenflo J.O. et al 2005, A&A, 434, 1183 Trakhtengerts V.Yu. 1984, Relaxation of Plasma with Anisotropic Velocity Distribution, in A.A.Galeev and R.N.Sudan (eds.) Basic Plasma Physics II, North-Holland Physics Publishing Yokoyama T., Nakajima H., Shibasaki K, et al. 2002, ApJ, 576, L87

  5. Effects of the relative motion of different particles on the wave instability in dusty plasmas

    SciTech Connect

    Gao, Dong-Ning; Hong, Xue-Ren; Lin, Mai-mai; Han, Juan-fang; Duan, Wen-shan; Yang, Lei

    2014-06-15

    Theoretical study is carried out for the dust acoustic waves in a dusty plasma. The dispersion relation is obtained from the fluid dynamical model. It is found that the wave frequency depends on the electron number density, wave number, and the speed of electrons or ions. The dependencies of the instability on the system parameters are also discussed. It is found that the long wavelength wave is usually unstable, which may be useful in the plasma physics, especially in the magnetic confined fusion system or the charged beam dynamics in the accelerated driven system.

  6. Plasma acceleration using a radio frequency self-bias effect

    SciTech Connect

    Rafalskyi, D.; Aanesland, A.

    2015-06-15

    In this work plasma acceleration using a RF self-bias effect is experimentally studied. The experiments are conducted using a novel plasma accelerator system, called Neptune, consisting of an inductively coupled plasma source and a RF-biased set of grids. The plasma accelerator can operate in a steady state mode, producing a plasma flow with separately controlled plasma flux and velocity without any magnetic configuration. The operating pressure at the source output is as low as 0.2 mTorr and can further be decreased. The ion and electron flows are investigated by measuring the ion and electron energy distribution functions both space resolved and with different orientations with respect to the flow direction. It is found that the flow of electrons from the source is highly anisotropic and directed along the ion flow and this global flow of accelerated plasma is well localized in the plasma transport chamber. The maximum flux is about 7.5·10{sup 15} ions s{sup −1} m{sup −2} (at standard conditions) on the axis and decreasing to almost zero at a radial distances of more than 15 cm from the flow axis. Varying the RF acceleration voltage in the range 20–350 V, the plasma flow velocity can be changed between 10 and 35 km/s. The system is prospective for different technology such as space propulsion and surface modification and also interesting for fundamental studies for space-related plasma simulations and investigation of the dynamo effect using accelerated rotating plasmas.

  7. Design of a Microwave Assisted Discharge Inductive Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley K.; Polzin, Kurt A.

    2010-01-01

    A new plasma accelerator concept that employs electrodeless plasma preionization and pulsed inductive acceleration is presented. Preionization is achieved through an electron cyclotron resonance discharge that produces a weakly-ionized plasma at the face of a conical theta pinch-shaped inductive coil. The presence of the preionized plasma allows for current sheet formation at lower discharge voltages than those found in other pulsed inductive accelerators. The location of an electron cyclotron resonance discharge can be controlled through the design of the applied magnetic field in the thruster. A finite-element model of the magnetic field was used as a design tool, allowing for the implementation of an arrangement of permanent magnets that yields a small volume of preionized propellant at the coil face. This allows for current sheet formation at the face of the inductive coil, minimizing the initial inductance of the pulse circuit and maximizing the potential efficiency of the new accelerator.

  8. Dust accelerators and their applications in high-temperature plasmas

    SciTech Connect

    Wang, Zhehui; Ticos, Catakin M

    2010-01-01

    The perennial presence of dust in high-temperature plasma and fusion devices has been firmly established. Dust inventory must be controlled, in particular in the next-generation steady-state fusion machines like ITER, as it can pose significant safety hazards and potentially interfere with fusion energy production. Much effort has been devoted to gening rid of the dust nuisance. We have recognized a number of dust-accelerators applications in magnetic fusion, including in plasma diagnostics, in studying dust-plasma interactions, and more recently in edge localized mode (ELM)'s pacing. With the applications in mind, we will compare various acceleration methods, including electrostatic, gas-drag, and plasma-drag acceleration. We will also describe laboratory experiments and results on dust acceleration.

  9. Dust Accelerators And Their Applications In High-Temperature Plasmas

    NASA Astrophysics Data System (ADS)

    Ticoş, Cǎtǎlin M.; Wang, Zhehui

    2011-06-01

    The perennial presence of dust in high-temperature plasma and fusion devices has been firmly established. Dust inventory must be controlled, in particular in the next-generation steady-state fusion machines like ITER, as it can pose significant safety hazards and potentially interfere with fusion energy production. Although much effort has been devoted to getting rid of the dust nuisance, there are instances where a controlled use of dust can be beneficial. We have recognized a number of dust-accelerators applications in magnetic fusion, including in plasma diagnostics, in studying dust-plasma interactions, and more recently in edge localized mode (ELM)'s pacing. With the applications in mind, we will compare various acceleration methods, including electrostatic, gas-drag, and plasma-drag acceleration. We will also describe laboratory experiments and results on dust acceleration.

  10. Controlling electron injection in laser plasma accelerators using multiple pulses

    SciTech Connect

    Matlis, N. H.; Geddes, C. G. R.; Plateau, G. R.; Esarey, E.; Schroeder, C.; Bruhwiler, D.; Cormier-Michel, E.; Chen, M.; Yu, L.; Leemans, W. P.

    2012-12-21

    Use of counter-propagating pulses to control electron injection in laser-plasma accelerators promises to be an important ingredient in the development of stable devices. We discuss the colliding pulse scheme and associated diagnostics.

  11. Particle acceleration and wave emissions associated with the formation of auroral cavities and enhancements

    NASA Technical Reports Server (NTRS)

    Winglee, R. M.; Dusenbery, P. B.; Pritchett, P. L.; Persoon, A. M.; Waite, J. H., Jr.; Moore, T. E.; Burch, J. L.; Collin, H. L.; Slavin, J. A.

    1988-01-01

    A unified model is presented which interrelates the various processes involved in auroral particle acceleration and the associated wave emissions, and it is shown how energy is coupled from the magnetosphere into the ionosphere. The phenomena in the magnetotail which can provide the source of free energy for the perpendicular electrostatic shocks are identified along with the associated potential structures in the nightside auroral region. The characteristics of the particle acceleration produced by the shock are described, including efficiency and energy transport between magnetospheric and ionospheric plasmas, the properties of the particle distributions throughout the shock region and return current regions, and the associated wave emissions. The source of free energy for the generation of ion conics is identified, as are the signatures for the formation of plasma cavities and/or enhancements.

  12. Influence of emittance on transverse dynamics of accelerated bunches in the plasma-dielectric wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Kniaziev, R. R.; Sotnikov, G. V.

    2016-09-01

    We study theoretically transverse dynamics of the bunch of charged particles with the finite emittance in the plasma-dielectric wakefield accelerator. Parameters of bunches are chosen the same as available from the 15 MeV Argonne Wakefield Accelerator beamline. The goal of the paper is to study the behavior of bunches of charged particles with different emittances while accelerating these bunches by wakefields in plasma-dielectric structures. Obtained results allow us to determine the limits of the emittance of the bunch where dynamics of the accelerated particles remains stable.

  13. Wave-breaking amplitudes of relativistic upper-hybrid oscillations in a cold magnetized plasma

    NASA Astrophysics Data System (ADS)

    Karmakar, Mithun; Maity, Chandan; Chakrabarti, Nikhil

    2016-06-01

    A travelling wave solution is presented for relativistic upper-hybrid oscillations (RUHOs) in a cold magnetized plasma. An expression for the wave-breaking amplitudes of RUHOs is derived. The wave-breaking amplitudes of RUHOs are found to decrease with the increase of the strength of an ambient magnetic field. These results will be of relevance to the laboratory context of particle acceleration by wake-fields in which magnetic field plays a central role.

  14. Laser driven electron acceleration in vacuum, gases and plasmas

    SciTech Connect

    Sprangle, P.; Esarey, E.; Krall, J.

    1996-04-19

    This paper discusses some of the important issues pertaining to laser acceleration in vacuum, neutral gases and plasmas. The limitations of laser vacuum acceleration as they relate to electron slippage, laser diffraction, material damage and electron aperture effects, are discussed. An inverse Cherenkov laser acceleration configuration is presented in which a laser beam is self guided in a partially ionized gas. Optical self guiding is the result of a balance between the nonlinear self focusing properties of neutral gases and the diffraction effects of ionization. The stability of self guided beams is analyzed and discussed. In addition, aspects of the laser wakefield accelerator are presented and laser driven accelerator experiments are briefly discussed.

  15. Concepts and limitations of macroparticle accelerators using travelling magnetic waves

    SciTech Connect

    Wipf, S.L.

    1980-01-01

    The concept of an accelerator using a travelling magnetic wave acting on magnetized projectiles is discussed. Although superconductors have a high potential as projectile material, their low critical temperature makes them unsuitable. Among ferromagnetic materials dysprosium seems to be superior. For stable suspension and guidance a high conductivity, preferably superconducting, guide sheet is necessary. Magnetic field gradients of 10/sup 9/ A/m/sup 2/ travelling at 10/sup 6/ m/s should be achievable using present state-of-the-art components; resulting accelerations are greater than or equal to 500 km/s/sup 2/. A linear accelerator for final speeds of 50 km/s needs a length of 2.5 km. Guidance forces sufficient to produce acceleration of 2 x 10/sup 6/ m/s/sup 2/ allow circular accelerators of reasonable size to achieve hypervelocities for small (50 to 100 mg) projectiles. An accelerator of 170 m diameter would surpass the best results from light gas guns. Travelling waves suitable for accelerations of the order of 10/sup 4/ m/s/sup 2/ can be produced without switching, by means of flux displacing rotors, easily adapted to circular accelerators.

  16. Influence of Reverse Expansion of Laser Plasma on Ions Acceleration

    NASA Astrophysics Data System (ADS)

    Sysoev, Alexander A.; Gracheva, O. I.; Karpov, A. V.

    Effect of laser plasma reverse extension is described in this paper. Influence of the effect on ion acceleration in a laser ion source is researched. This effect leads to sedimentation of ions on metal target, which significantly impacts acceleration time of other ions. In this case, the ions also tend to travel major part of their path with constant velocity. This allows one to consider movement of the ions in plasma drift space, when optimizing time focusing ability of the TOF analyzer.

  17. Miniature plasma accelerating detonator and method of detonating insensitive materials

    DOEpatents

    Bickes, R.W. Jr.; Kopczewski, M.R.; Schwarz, A.C.

    1985-01-04

    The invention is a detonator for use with high explosives. The detonator comprises a pair of parallel rail electrodes connected to a power supply. By shorting the electrodes at one end, a plasma is generated and accelerated toward the other end to impact against explosives. A projectile can be arranged between the rails to be accelerated by the plasma. An alternative arrangement is to a coaxial electrode construction. The invention also relates to a method of detonating explosives. 3 figs.

  18. Miniature plasma accelerating detonator and method of detonating insensitive materials

    DOEpatents

    Bickes, Jr., Robert W.; Kopczewski, Michael R.; Schwarz, Alfred C.

    1986-01-01

    The invention is a detonator for use with high explosives. The detonator comprises a pair of parallel rail electrodes connected to a power supply. By shorting the electrodes at one end, a plasma is generated and accelerated toward the other end to impact against explosives. A projectile can be arranged between the rails to be accelerated by the plasma. An alternative arrangement is to a coaxial electrode construction. The invention also relates to a method of detonating explosives.

  19. Plasma wave experiment for the ISEE-3 mission

    NASA Technical Reports Server (NTRS)

    Scarf, F. L.

    1983-01-01

    Sensitive, high resolution plasma probes for analysis of the distribution functions and plasma wave instruments for measurements of electromagnetic and electrostatic wave modes are commonly flown together to provide information on plasma instabilities and wave particle interactions. Analysis of the data for the ISEE 3 mission is provided.

  20. Traveling wave linear accelerator with RF power flow outside of accelerating cavities

    DOEpatents

    Dolgashev, Valery A.

    2016-06-28

    A high power RF traveling wave accelerator structure includes a symmetric RF feed, an input matching cell coupled to the symmetric RF feed, a sequence of regular accelerating cavities coupled to the input matching cell at an input beam pipe end of the sequence, one or more waveguides parallel to and coupled to the sequence of regular accelerating cavities, an output matching cell coupled to the sequence of regular accelerating cavities at an output beam pipe end of the sequence, and output waveguide circuit or RF loads coupled to the output matching cell. Each of the regular accelerating cavities has a nose cone that cuts off field propagating into the beam pipe and therefore all power flows in a traveling wave along the structure in the waveguide.

  1. GeV plasma accelerators driven in waveguides

    SciTech Connect

    Hooker, S.M.; Brunetti, E.; Esarey, E.; Gallacher, J.G.; Geddes,C.G.R.; Gonsalves, A.J.; Jaroszynski, D.A.; Kamperidis, C.; Kneip, S.; Krushelnick, K.; Leemans, W.P.; Mangles, S.P.D.; Murphy, C.D.; Nagler,B.; Najmudin, Z.; Nakamura, K.; Norreys, P.A.; Panasenko, D.; Rowlands-Rees, T.P.; Schroeder, C.B.; Toth, Cs.; Trines, R.

    2007-11-01

    During the last few years laser-driven plasma acceleratorshave been shown to generate quasi-monoenergetic electron beams withenergies up to several hundred MeV. Extending the output energy oflaser-driven plasma accelerators to the GeV range requires operation atplasma densities an order of magnitude lower, i.e. 1018 cm-3, andincreasing the distance over which acceleration is maintained from a fewmillimetres to a few tens of millimetres. One approach for achieving thisis to guide the driving laser pulse in the plasma channel formed in agas-filled capillary discharge waveguide. We present transverseinterferometric measurements of the evolution of the plasma channelformed and compare these measurements with models of the capillarydischarge. We describe in detail experiments performed at LawrenceBerkeley National Laboratory and at Rutherford Appleton Laboratory inwhich plasma accelerators were driven within this type of waveguide togenerate quasimonoenergetic electron beams with energies up to 1GeV.

  2. Localized Ionospheric Particle Acceleration and Wave Acceleration of Auroral Ions: Amicist Data Set

    NASA Technical Reports Server (NTRS)

    Lynch, Kristina A.

    1999-01-01

    Research supported by this grant covered two main topics: auroral ion acceleration from ELF-band wave activity, and from VLF-spikelet (lower hybrid solitary structure) wave activity. Recent auroral sounding rocket data illustrate the relative significance of various mechanisms for initiating auroral ion outflow. Two nightside mechanisms are shown in detail. The first mechanism is ion acceleration within lower hybrid solitary wave events. The new data from this two payload mission show clearly that: (1) these individual events are spatially localized to scales approximately 100 m wide perpendicular to B, in agreement with previous investigations of these structures, and (2) that the probability of occurrence of the events is greatest at times of maximum VLF wave intensity. The second mechanism is ion acceleration by broadband, low frequency electrostatic waves, observed in a 30 km wide region at the poleward edge of the arc. The ion fluxes from the two mechanisms are compared and it is shown that while lower hybrid solitary structures do indeed accelerate ions in regions of intense VLF waves, the outflow from the electrostatic ion wave acceleration region is dominant for the aurora investigated by this sounding rocket, AMICIST. The fluxes are shown to be consistent with DE-1 and Freja outflow measurements, indicating that the AMICIST observations show the low altitude, microphysical signatures of nightside auroral outflow. In this paper, we present a review of sounding rocket observations of the ion acceleration seen nightside auroral zone lower hybrid solitary structures. Observations from Topaz3, Amicist, and Phaze2 are presented on various spatial scales, including the two-point measurements of the Amicist mission. From this collection of observations, we will demonstrate the following characteristics of transverse ion acceleration (TAI) in LHSS. The ion acceleration process is narrowly confined to 90 degrees pitch angle, in spatially confined regions of up to a

  3. High frequency single mode traveling wave structure for particle acceleration

    NASA Astrophysics Data System (ADS)

    Ivanyan, M. I.; Danielyan, V. A.; Grigoryan, B. A.; Grigoryan, A. H.; Tsakanian, A. V.; Tsakanov, V. M.; Vardanyan, A. S.; Zakaryan, S. V.

    2016-09-01

    The development of the new high frequency slow traveling wave structures is one of the promising directions in accomplishment of charged particles high acceleration gradient. The disc and dielectric loaded structures are the most known structures with slowly propagating modes. In this paper a large aperture high frequency metallic two-layer accelerating structure is studied. The electrodynamical properties of the slowly propagating TM01 mode in a metallic tube with internally coated low conductive thin layer are examined.

  4. Accelerating Airy-Gauss-Kummer localized wave packets

    NASA Astrophysics Data System (ADS)

    Zhong, Wei-Ping; Belić, Milivoj; Zhang, Yiqi; Huang, Tingwen

    2014-01-01

    A general approach to generating three-dimensional nondiffracting spatiotemporal solutions of the linear Schrödinger equation with an Airy-beam time-dependence is reported. A class of accelerating optical pulses with the structure of Airy-Gauss-Kummer vortex beams is obtained. Our results demonstrate that the optical field contributions to the Airy-Gauss-Kummer accelerating optical wave packets of the cylindrical symmetry can be characterized by the radial and angular mode numbers.

  5. Dispersion relation of electrostatic ion cyclotron waves in multi-component magneto-plasma

    SciTech Connect

    Khaira, Vibhooti Ahirwar, G.

    2015-07-31

    Electrostatic ion cyclotron waves in multi component plasma composed of electrons (denoted by e{sup −}), hydrogen ions (denoted by H{sup +}), helium ions (denoted by He{sup +}) and positively charged oxygen ions (denoted by O{sup +})in magnetized cold plasma. The wave is assumed to propagate perpendicular to the static magnetic field. It is found that the addition of heavy ions in the plasma dispersion modified the lower hybrid mode and also allowed an ion-ion mode. The frequencies of the lower hybrid and ion- ion hybrid modes are derived using cold plasma theory. It is observed that the effect of multi-ionfor different plasma densities on electrostatic ion cyclotron waves is to enhance the wave frequencies. The results are interpreted for the magnetosphere has been applied parameters by auroral acceleration region.

  6. On the mechanism of acceleration behavior of plasma bullet

    SciTech Connect

    Wu, S.; Lu, X. Pan, Y.

    2014-07-15

    Two special experiments are designed to study the mechanism of the acceleration behavior of a plasma bullet when it exits a nozzle. First, a T-shape device is used to simulate the air diffusion when a plasma plume exits the nozzle. It is found that adding just 1% of N{sub 2}, O{sub 2}, or air to the main working gas He results in the acceleration of the plasma bullet. Second, materials of different permittivity are added to the left part of the outside of the tube. The experimental results show that the plasma bullet accelerates at the moment when it enters into the right part of the tube where there is no extra material on the outside of the tube. These two experiments confirm that the acceleration behavior of the plasma bullet when it exits the nozzle is due to the air diffusion, hence Penning ionization, and the permittivity change when the bullet exits the nozzle, for example, from a tube with high permittivity to air with low permittivity. Besides, electric field measurements show that the electric field in the bullet head increases when the plasma bullet accelerates. This confirms the electric field driven nature of the plasma bullet propagation.

  7. LOADED WAVE GUIDES FOR LINEAR ACCELERATORS

    DOEpatents

    Walkinshaw, W.; Mullett, L.B.

    1959-12-01

    A periodically loaded waveguide having substantially coaxially arranged elements which provide an axial field for the acceleration of electrons is described. Radiofrequency energy will flow in the space between the inner wall of an outer guide and the peripheries of equally spaced irises or washes arranged coaxially with each other and with the outer guide, where the loading due to the geometry of the irises is such as to reduce the phase velocity of the r-f energy flowing in the guide from a value greater than that of light to the velocity of light or less.

  8. Beat-wave generation of plasmons in semiconductor plasmas

    SciTech Connect

    Berezhiani, V.I.; Mahajan, S.M. |

    1995-08-01

    It is shown that in semiconductor plasmas, it is possible to generate large amplitude plasma waves by the beating of two laser beams with frequency difference close to the plasma frequency. For narrow gap seimconductors (for example n-type InSb), the system can simulate the physics underlying beat wave generation in relativistic gaseous plasmas.

  9. Electron acceleration by parametrically excited Langmuir waves. [in ionospheric modification

    NASA Technical Reports Server (NTRS)

    Fejer, J. A.; Graham, K. N.

    1974-01-01

    Simple physical arguments are used to estimate the downward-going energetic electron flux due to parametrically excited Langmuir waves in ionospheric modification experiments. The acceleration mechanism is a single velocity reversal as seen in the frame of the Langmuir wave. The flux is sufficient to produce the observed ionospheric airglow if focusing-type instabilities are invoked to produce moderate local enhancements of the pump field.

  10. Modeling Extreme Solar Energetic Particle Acceleration with Self-Consistent Wave Generation

    NASA Astrophysics Data System (ADS)

    Arthur, A. D.; le Roux, J. A.

    2015-12-01

    Observations of extreme solar energetic particle (SEP) events associated with coronal mass ejection driven shocks have detected particle energies up to a few GeV at 1 AU within the first ~10 minutes to 1 hour of shock acceleration. Whether or not acceleration by a single shock is sufficient in these events or if some combination of multiple shocks or solar flares is required is currently not well understood. Furthermore, the observed onset times of the extreme SEP events place the shock in the corona when the particles escape upstream. We have updated our focused transport theory model that has successfully been applied to the termination shock and traveling interplanetary shocks in the past to investigate extreme SEP acceleration in the solar corona. This model solves the time-dependent Focused Transport Equation including particle preheating due to the cross shock electric field and the divergence, adiabatic compression, and acceleration of the solar wind flow. Diffusive shock acceleration of SEPs is included via the first-order Fermi mechanism for parallel shocks. To investigate the effects of the solar corona on the acceleration of SEPs, we have included an empirical model for the plasma number density, temperature, and velocity. The shock acceleration process becomes highly time-dependent due to the rapid variation of these coronal properties with heliocentric distance. Additionally, particle interaction with MHD wave turbulence is modeled in terms of gyroresonant interactions with parallel propagating Alfven waves. However, previous modeling efforts suggest that the background amplitude of the solar wind turbulence is not sufficient to accelerate SEPs to extreme energies over the short time scales observed. To account for this, we have included the transport and self-consistent amplification of MHD waves by the SEPs through wave-particle gyroresonance. We will present the results of this extended model for a single fast quasi-parallel CME driven shock in the

  11. High-field plasma acceleration in a high-ionization-potential gas

    NASA Astrophysics Data System (ADS)

    Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.

    2016-06-01

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ~150 GV m-1, over ~20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources.

  12. High-field plasma acceleration in a high-ionization-potential gas

    PubMed Central

    Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.

    2016-01-01

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ∼150 GV m−1, over ∼20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources. PMID:27312720

  13. High-field plasma acceleration in a high-ionization-potential gas.

    PubMed

    Corde, S; Adli, E; Allen, J M; An, W; Clarke, C I; Clausse, B; Clayton, C E; Delahaye, J P; Frederico, J; Gessner, S; Green, S Z; Hogan, M J; Joshi, C; Litos, M; Lu, W; Marsh, K A; Mori, W B; Vafaei-Najafabadi, N; Walz, D; Yakimenko, V

    2016-01-01

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ∼150 GV m(-1), over ∼20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources. PMID:27312720

  14. High-field plasma acceleration in a high-ionization-potential gas

    DOE PAGESBeta

    Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; et al

    2016-06-17

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. In our research, we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by upmore » to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ~150 GV m-1, over ~20 cm. Lastly, the results open new possibilities for the design of particle beam drivers and plasma sources.« less

  15. Damping of Plasma Waves in Multi-species Ion Plasmas

    NASA Astrophysics Data System (ADS)

    Anderegg, Francois; Affolter, Matthew; Driscoll, C. Fred

    2015-11-01

    The damping of Langmuir waves in multi-species pure ion plasmas is measured over four decades in temperature covering regimes of Landau, bounce harmonics, and interspecies drag damping. Thermal cyclotron spectroscopy determines the plasma composition. The plasma is predominantly Mg+ resulting from a Mg electrode arc, with roughly 5-30% other ions, typically H3O+ and O2+,arising from ionization and chemical reactions with the residual background gas. The plasma temperature is controlled with laser cooling of the Mg24 ions over the range 10-4 <= T <= 1 eV. For T >= 0 .1 eV, the damping rates agree closely with Landau theory for θ-symmetric standing waves, with discrete wavenumber k1 = π /Lp . At lower temperature 10-2 <= T <= 0 . 1 eV the damping is not fully understood, but is most likely a result of Landau damping on higher kz bounce harmonics produced by the rounded plasma ends. For T <=10-2 eV, damping rates 10 <= γ <=103 s-1 are proportional to the ion-ion collisionality νii ~T - 3 / 2 , consistent with a theory prediction that includes interspecies drag. A decrease in γ is observed at T <=10-3 eV, presumably due to strong magnetization, centrifugal separation of the species, and the collisionality approaching the mode frequencyf1 ~20 kHz. Supported by DOE grant DE-SC0002451.

  16. The LICPA accelerator of dense plasma and ion beams

    NASA Astrophysics Data System (ADS)

    Badziak, J.; Jabloński, S.; Pisarczyk, T.; Chodukowski, T.; Parys, P.; Raczka, P.; Rosiński, M.; Krousky, E.; Ullschmied, J.; Liska, R.; Kucharik, M.; Torrisi, L.

    2014-04-01

    Laser-induced cavity pressure acceleration (LICPA) is a novel scheme of acceleration of dense matter having a potential to accelerate plasma projectiles with the energetic efficiency much higher than the achieved so far with other methods. In this scheme, a projectile placed in a cavity is irradiated by a laser beam introduced into the cavity through a hole and accelerated along a guiding channel by the thermal pressure created in the cavity by the laser-produced plasma or by the photon pressure of the ultraintense laser radiation trapped in the cavity. This paper summarizes briefly the main results of our recent LICPA studies, in particular, experimental investigations of ion beam generation and heavy macroparticle acceleration in the hydrodynamic LICPA regime (at moderate laser intensities ~ 1015W/cm2) and numerical, particle-in-cell (PIC) studies of production of ultraintense ion beams and fast macroparticles using the photon pressure LICPA regime (at high laser intensities > 1020 W/cm2). It is shown that in both LICPA regimes the macroparticles and ion beams can be accelerated much more efficiently than in other laser-based acceleration scheme commonly used and the accelerated plasma/ion bunches can have a wide variety of parameters. It creates a prospect for a broad range of applications of the LICPA accelerator, in particular in such domains as high energy density physics, ICF research (ion fast ignition, impact ignition) or nuclear physics.

  17. Waves in space plasma dipole antenna subsystem

    NASA Technical Reports Server (NTRS)

    Thomson, Mark

    1993-01-01

    The Waves In Space Plasma (WISP) flight experiment requires a 50-meter-long deployable dipole antenna subsystem (DASS) to radiate radio frequencies from the STS Orbiter cargo bay. The transmissions are to excite outer ionospheric plasma between the dipole and a free-flying receiver (Spartan) for scientific purposes. This report describes the singular DASS design requirements and how the resulting design satisfies them. A jettison latch is described in some detail. The latch releases the antenna in case of any problems which might prevent the bay doors from closing for re-entry and landing of the Orbiter.

  18. Waves in plasmas: some historical highlights

    SciTech Connect

    Stix, T.H.

    1984-08-01

    To illustrate the development of some fundamental concepts in plasma waves, a number of experimental observations, going back over half a century, are reviewed. Particular attention is paid to the phenomena of dispersion, collisionfree damping, finite-Larmor-radius and cyclotron and cyclotron-harmonic effects, nonlocal response, and stochasticity. One may note not only the constructive interplay between observation and theory and experiment but also that major advances have come from each of the many disciplines that invoke plasma physics as a tool, including radio communication, astrophysics, controlled fusion, space physics, and basic research.

  19. Relativistic Bernstein waves in a degenerate plasma

    SciTech Connect

    Ali, Muddasir; Hussain, Azhar; Murtaza, G.

    2011-09-15

    Bernstein mode for a relativistic degenerate electron plasma is investigated. Using relativistic Vlasov-Maxwell equations, a general expression for the conductivity tensor is derived and then employing Fermi-Dirac distribution function a generalized dispersion relation for the Bernstein mode is obtained. Two limiting cases, i.e., non-relativistic and ultra-relativistic are discussed. The dispersion relations obtained are also graphically presented for some specific values of the parameters depicting how the propagation characteristics of Bernstein waves as well as the Upper Hybrid oscillations are modified with the increase in plasma number density.

  20. Blowout regimes of plasma wakefield acceleration.

    PubMed

    Lotov, K V

    2004-04-01

    A wide region of beam parameters is numerically scanned and the dependence of wakefield properties on the beam length and current is clarified for the blowout regime of beam-plasma interaction. The main regimes of the plasma response are found, which qualitatively differ in the plasma behavior. To characterize the efficiency of the energy exchange between the beam and the plasma, the energy flux through the comoving window is introduced. Scalings of the energy flux for the linear plasma response and the main blowout regimes are studied. The most efficient energy transfer occurs in the so-called "strong beam" regime of interaction. For this regime, analytical approximations for various aspects of the plasma response are obtained. PMID:15169104

  1. Electron acceleration by a laser pulse in a plasma

    SciTech Connect

    McKinstrie, C.J.; Startsev, E.A.

    1996-08-01

    The acceleration of an electron by a circularly polarized laser pulse in a plasma is studied. It appears possible to increase significantly the energy of a preaccelerated electron. Although the pulse tends to generate a plasma wake, to which it loses energy, one can eliminate the wake by choosing the duration of the pulse judiciously. {copyright} {ital 1996 The American Physical Society.}

  2. Proton shock acceleration in laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Marti, M.; Davies, J.; Fonseca, R. A.; Silva, L. O.; Fahlen, J.; Ren, C.; Tsung, F.; Mori, W. B.

    2003-10-01

    The formation of strong, high Mach number (2--3), electrostatic shocks by laser pulses incident on overdense plasma slabs is observed in 1 and 2-dimensional particle-in-cell simulations, for a wide range of intensities, pulse durations, target thicknesses and densities. The shocks propagate undisturbed across the plasma, accelerating the ions (protons). For dimensionless field strength parameter a_0=16 (Iλ^2 ≈ 3 × 10^20 W cm-2 μm^2, where I is intensity and λ wavelength) the highest energy protons are accelerated by the shock. A plateau in the ion spectrum provides a direct signature for shock acceleration.

  3. Staging optics considerations for a plasma wakefield acceleration linear collider

    NASA Astrophysics Data System (ADS)

    Lindstrøm, C. A.; Adli, E.; Allen, J. M.; Delahaye, J. P.; Hogan, M. J.; Joshi, C.; Muggli, P.; Raubenheimer, T. O.; Yakimenko, V.

    2016-09-01

    Plasma wakefield acceleration offers acceleration gradients of several GeV/m, ideal for a next-generation linear collider. The beam optics requirements between plasma cells include injection and extraction of drive beams, matching the main beam beta functions into the next cell, canceling dispersion as well as constraining bunch lengthening and chromaticity. To maintain a high effective acceleration gradient, this must be accomplished in the shortest distance possible. A working example is presented, using novel methods to correct chromaticity, as well as scaling laws for a high energy regime.

  4. A HIGH REPETITION PLASMA MIRROR FOR STAGED ELECTRON ACCELERATION

    SciTech Connect

    Sokollik, Thomas; Shiraishi, Satomi; Osterhoff, Jens; Evans, Eugene; Gonsalves, Anthony; Nakamura, Kei; vanTilborg, Jeroen; Lin, Chen; Toth, Csaba; Leemans, Wim

    2011-07-22

    In order to build a compact, staged laser plasma accelerator the in-coupling of the laser beam to the different stages represents one of the key issues. To limit the spatial foot print and thus to realize a high overall acceleration gradient, a concept has to be found which realizes this in-coupling within a few centimeters. We present experiments on a tape-drive based plasma mirror which could be used to reflect the focused laser beam into the acceleration stage.

  5. Controlled Electron Injection into Plasma Accelerators and SpaceCharge Estimates

    SciTech Connect

    Fubiani, Gwenael J.

    2005-09-01

    Plasma based accelerators are capable of producing electron sources which are ultra-compact (a few microns) and high energies (up to hundreds of MeVs) in much shorter distances than conventional accelerators. This is due to the large longitudinal electric field that can be excited without the limitation of breakdown as in RF structures.The characteristic scale length of the accelerating field is the plasma wavelength and for typical densities ranging from 1018 - 1019 cm-3, the accelerating fields and scale length can hence be on the order of 10-100GV/m and 10-40 mu m, respectively. The production of quasimonoenergetic beams was recently obtained in a regime relying on self-trapping of background plasma electrons, using a single laser pulse for wakefield generation. In this dissertation, we study the controlled injection via the beating of two lasers (the pump laser pulse creating the plasma wave and a second beam being propagated in opposite direction) which induce a localized injection of background plasma electrons. The aim of this dissertation is to describe in detail the physics of optical injection using two lasers, the characteristics of the electron beams produced (the micrometer scale plasma wavelength can result in femtosecond and even attosecond bunches) as well as a concise estimate of the effects of space charge on the dynamics of an ultra-dense electron bunch with a large energy spread.

  6. Mitigation of Ion Motion in future Plasma Wakefield Accelerators

    NASA Astrophysics Data System (ADS)

    Gholizadeh, Reza; Katsouleas, Tom; Muggli, Patric; Mori, Warren

    2007-11-01

    Simulation and analysis of the ion motion in a plasma wakefield accelerator is presented for the parameters required for a future ILC afterburner. We Show that although ion motion leads to substantial emittance growth for extreme parameters of future colliders in the sub-micron transverse beam Size regime, several factors that can mitigate the effect are explored. These include synchrotron radiation damping, plasma density gradients and hot plasmas.

  7. Transverse effects in plasma wakefield acceleration at FACET - Simulation studies

    SciTech Connect

    Adli, E.; Hogan, M.; Frederico, J.; Litos, M. D.; An, W.; Mori, W.

    2012-12-21

    We investigate transverse effects in the plasma-wakefield acceleration experiments planned and ongoing at FACET. We use PIC simulation tools, mainly QuickPIC, to simulate the interaction of the drive electron beam and the plasma. In FACET a number of beam dynamics knobs, including dispersion and bunch length knobs, can be used to vary the beam transverse characteristics in the plasma. We present simulation results and the status of the FACET experimental searches.

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

    SciTech Connect

    Lotov, K. V.

    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.

  9. Energy Measurements of Trapped Electrons from a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, Neal; Auerbach, David; Berry, Melissa; Blumenfeld, Ian; Clayton, Christopher E.; Decer, Franz-Josef; Hogan, Mark J.; Huang, Chengkun; Ischebeck, Rasmus; Iverson, Richard; Johnson, Devon; Joshi, Chadrashekhar; Katsouleas, Thomas; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; Muggli, Patric; Oz, Erdem; Siemann, Robert H.; Walz, Dieter; Zhou, Miaomiao; /SLAC /UCLA /Southern California U.

    2007-01-03

    Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC indicate trapping of plasma electrons. More charge came out of than went into the plasma. Most of this extra charge had energies at or below the 10 MeV level. In addition, there were trapped electron streaks that extended from a few GeV to tens of GeV, and there were mono-energetic trapped electron bunches with tens of GeV in energy.

  10. Laboratory Measurements of Linear Electron Acceleration by Inertial Alfvén Waves

    NASA Astrophysics Data System (ADS)

    Schroeder, J. W. R.

    2015-11-01

    Alfvén waves occur in conjunction with a significant fraction of auroral electron acceleration. Inertial mode Alfvén waves (vA >vte) in the auroral magnetosphere (2 - 4RE) with perpendicular scales on the order of the electron skin depth (c /ωpe) have a parallel electric field that, according to theory, is capable of nonlinearly accelerating suprathermal electrons to auroral energies. Unfortunately, due to space-time ambiguities of rocket and satellite measurements, it has not yet been possible to fully verify how Alfvén waves contribute to the production of accelerated electrons. To overcome the limitations of in situ spacecraft data, laboratory experiments have been carried out using the Large Plasma Device (LaPD), an NSF/DOE user facility at UCLA. An Electron Cyclotron Absorption (ECA) diagnostic has been developed to record the suprathermal parallel electron distribution function with 0.1% precision. The diagnostic records the electron distribution while inertial Alfvén waves simultaneously propagate through the plasma. Recent measurements have isolated oscillations of suprathermal electrons at the Alfvén wave frequency. Despite complications from boundary effects and the finite size of the experiment, a linear kinetic model has been produced that describes the experimental results. To our knowledge this is the first quantitative agreement between the measured and modeled linear response of suprathermal electrons to an inertial Alfvén wave. This verification of the linear physics is a necessary step before the nonlinear acceleration process can be isolated in future experiments. Presently, nonlinear effects cannot be detected because of limited Alfvén wave amplitudes. Ongoing work is focused on designing a higher-power antenna capable of efficiently launching larger-amplitude Alfvén waves with tunable perpendicular wavenumber and developing a theoretical understanding of the nonlinear acceleration process in LaPD plasma conditions. This material is

  11. Beam-driven acceleration in ultra-dense plasma media

    SciTech Connect

    Shin, Young-Min

    2014-09-15

    Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 10{sup 25 }m{sup −3} and 1.6 × 10{sup 28 }m{sup −3} plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers ∼20% higher acceleration gradient by enlarging the channel radius (r) from 0.2 λ{sub p} to 0.6 λ{sub p} in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g., nanotubes) of high electron plasma density.

  12. Beam-driven acceleration in ultra-dense plasma media

    DOE PAGESBeta

    Shin, Young-Min

    2014-09-15

    Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 1025 m-3 and 1.6 x 1028 m-3 plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers 20 % higher acceleration gradient by enlarging the channel radius (r)more » from 0.2 Ap to 0.6 .Ap in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g. nanotubes) of high electron plasma density.« less

  13. Beam-driven acceleration in ultra-dense plasma media

    SciTech Connect

    Shin, Young-Min

    2014-09-15

    Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 1025 m-3 and 1.6 x 1028 m-3 plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers 20 % higher acceleration gradient by enlarging the channel radius (r) from 0.2 Ap to 0.6 .Ap in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g. nanotubes) of high electron plasma density.

  14. Singular waves in a magnetized pair-ion plasma

    SciTech Connect

    Samanta, Sukanta; Misra, Amar P.

    2009-07-15

    The existence of singular waves along the boundary of a magnetized pair-ion plasma is proved for both plasma-metal and plasma-vacuum interfaces. Such waves are shown to propagate at the points of intersection of the complex-zone boundary and the surface wave dispersion curve in a weakly magnetized plasma. The results could be relevant for negative ion plasmas in the laboratory and space as well as for the modeling of a plasma sustained by a traveling surface wave.

  15. Plasma waves near Venus - Initial observations

    NASA Technical Reports Server (NTRS)

    Scarf, F. L.; Taylor, W. W. L.; Green, I. M.

    1979-01-01

    The Pioneer Venus electric field detector was used to observe significant effects of the interaction of the solar wind with the ionosphere of Venus all along the orbiter trajectory. Information on sharp and diffuse shock structures and on plasma oscillations emitted by suprathermal electrons beyond the bow shock is considered, and wave particle interaction phenomena important near the boundary of the dayside ionosphere are noted.

  16. Modeling laser-plasma acceleration in the laboratory frame

    SciTech Connect

    2011-01-01

    A simulation of laser-plasma acceleration in the laboratory frame. Both the laser and the wakefield buckets must be resolved over the entire domain of the plasma, requiring many cells and many time steps. While researchers often use a simulation window that moves with the pulse, this reduces only the multitude of cells, not the multitude of time steps. For an artistic impression of how to solve the simulation by using the boosted-frame method, watch the video "Modeling laser-plasma acceleration in the wakefield frame."

  17. Laboratory simulation of ion acceleration in the presence of lower hybrid waves

    NASA Astrophysics Data System (ADS)

    McWilliams, R.; Koslover, R.; Boehmer, H.; Rynn, N.

    The UCI Q-machine has been used to simulate the effect of lower hybrid waves on ion acceleration. Laser induced fluorescence was used for high resolution, nonperturbing measurements of the ion velocity distribution function. The plasma consisted of a 1 m long, 5 cm diameter barium plasma of densities on the order of 10 to the 10th per cu cm contained by a 3 kG magnetic field. Substantial changes in the perpendicular ion distribution were found. Main-body ion heating occurred along with non-Maxwellian tail production.

  18. Relativistic laser piston model: Ponderomotive ion acceleration in dense plasmas using ultraintense laser pulses

    NASA Astrophysics Data System (ADS)

    Schlegel, T.; Naumova, N.; Tikhonchuk, V. T.; Labaune, C.; Sokolov, I. V.; Mourou, G.

    2009-08-01

    Laser ponderomotive force at superhigh intensities provides an efficient ion acceleration in bulk dense targets and evacuates a channel enabling further laser beam propagation. The developed quasistationary model of a laser piston—a double layer structure supported by the radiation pressure—predicts the general parameters of the acceleration process in homogeneous and inhomogeneous overdense plasmas. Particle-in-cell simulations confirm the estimated characteristics in a wide range of laser intensities and ion densities and show advantages of circularly polarized laser pulses. Two nonstationary effects are identified in the simulations. First, oscillations of the piston velocity and of the thickness of the ion charge separation layer broaden the energy spectrum of accelerated ions. Second, the electrons accelerated toward the incoming laser wave emit strong high-frequency radiation, enabling a cooling effect, which helps to sustain high charge neutrality in the piston and to maintain an efficient ion acceleration.

  19. Electron Acoustic Waves in Pure Ion Plasmas

    NASA Astrophysics Data System (ADS)

    Anderegg, F.; Affolter, M.; Driscoll, C. F.; O'Neil, T. M.; Valentini, F.

    2012-10-01

    Electron Acoustic Waves (EAWs) are the low-frequency branch of near-linear Langmuir (plasma) waves: the frequency is such that the complex dielectric function (Dr, Di) has Dr= 0; and ``flattening'' of f(v) near the wave phase velocity vph gives Di=0 and eliminates Landau damping. Here, we observe standing axisymmetric EAWs in a pure ion column.footnotetextF. Anderegg, et al., Phys. Rev. Lett. 102, 095001 (2009). At low excitation amplitudes, the EAWs have vph˜1.4 v, in close agreement with near-linear theory. At moderate excitation strengths, EAW waves are observed over a range of frequencies, with 1.3 v < vph< 2.1 v. Here, the final wave frequency may differ from the excitation frequency since the excitation modifies f (v); and recent theory analyzes frequency shifts from ``corners'' of a plateau at vph.footnotetextF. Valentini et al., arXiv:1206.3500v1. Large amplitude EAWs have strong phase-locked harmonic content, and experiments will be compared to same-geometry simulations, and to simulations of KEENfootnotetextB. Afeyan et al., Proc. Inertial Fusion Sci. and Applications 2003, A.N.S. Monterey (2004), p. 213. waves in HEDLP geometries.

  20. First plasma wave observations at uranus

    SciTech Connect

    Gurnett, D.A.; Kurth, W.S.; Scarf, F.L.; Poynter, R.L.

    1986-07-04

    Radio emissions from Uranus were detected by the Voyager 2 plasma wave instrument about 5 days before closest approach at frequencies of 31.1 and 56.2 kilohertz. About 10 hours before closest approach the bow shock was identified by an abrupt broadband burst of electrostatic turbulence at a radial distance of 23.5 Uranus radii. Once Voyager was inside the magnetosphere, strong whistler-mode hiss and chorus emissions were observed at radial distances less than about 8 Uranus radii, in the same region where the energetic-particle instruments detected intense fluxes of energetic electrons. Various other plasma waves were also observed in this same region. At the ring plane crossing, the plasma-wave instrument detected a large number of impulsive events that are interpreted as impacts of micrometer-sized dust particles on the spacecraft. The maximum impact rate was about 30 to 50 impacts per second, and the north south thickness of the impact region was about 4000 kilometers.

  1. Magnetowave induced plasma wakefield acceleration for ultrahigh energy cosmic rays.

    PubMed

    Chang, Feng-Yin; Chen, Pisin; Lin, Guey-Lin; Noble, Robert; Sydora, Richard

    2009-03-20

    Magnetowave induced plasma wakefield acceleration (MPWA) in a relativistic astrophysical outflow has been proposed as a viable mechanism for the acceleration of cosmic particles to ultrahigh energies. Here we present simulation results that clearly demonstrate the viability of this mechanism for the first time. We invoke the high frequency and high speed whistler mode for the driving pulse. The plasma wakefield obtained in the simulations compares favorably with our newly developed relativistic theory of the MPWA. We show that, under appropriate conditions, the plasma wakefield maintains very high coherence and can sustain high-gradient acceleration over hundreds of plasma skin depths. Invoking active galactic nuclei as the site, we show that MPWA production of ultrahigh energy cosmic rays beyond ZeV (10{21} eV) is possible. PMID:19392185

  2. Ponderomotive Acceleration of Hot Electrons in Tenuous Plasmas

    SciTech Connect

    V. I. Geyko; Fraiman, G. M.; Dodin, I. Y.; Fisch, N. J.

    2009-02-01

    The oscillation-center Hamiltonian is derived for a relativistic electron injected with an arbitrary momentum in a linearly polarized laser pulse propagating in tenuous plasma, assuming that the pulse length is smaller than the plasma wavelength. For hot electrons generated at collisions with ions under intense laser drive, multiple regimes of ponderomotive acceleration are identified and the laser dispersion is shown to affect the process at plasma densities down to 1017 cm-3. Assuming a/Υg << 1, which prevents net acceleration of the cold plasma, it is also shown that the normalized energy Υ of hot electrons accelerated from the initial energy Υo < , Γ does not exceed Γ ~ aΥg, where a is the normalized laser field, and Υg is the group velocity Lorentz factor. Yet Υ ~ Γ is attained within a wide range of initial conditions; hence a cutoff in the hot electron distribution is predicted.

  3. Cyclotron maser and plasma wave growth in magnetic loops

    NASA Technical Reports Server (NTRS)

    Hamilton, Russell J.; Petrosian, Vahe

    1990-01-01

    Cyclotron maser and plasma wave growth which results from electrons accelerated in magnetic loops are studied. The evolution of the accelerated electron distribution is determined by solving the kinetic equation including Coulomb collisions and magnetic convergence. It is found that for modest values of the column depth of the loop the growth rates of instabilities are significantly reduced and that the reduction is much larger for the cyclotron modes than for the plasma wave modes. The large decrease in the growth rate with column depth suggests that solar coronal densities must be much lower than commonly accepted in order for the cyclotron maser to operate. The density depletion has to be similar to that which occurs during auroral kilometric radiation events in the magnetosphere. The resulting distributions are much more complicated than the idealized distributions used in many theoretical studies, but the fastest growing mode can still simply be determined by the ratio of electron plasma to gyrofrequency, U=omega(sub p)/Omega(sub e). However, the dominant modes are different than for the idealized situations with growth of the z-mode largest for U approximately less than 0.5, and second harmonic x-mode (s=2) or fundamental o-mode (s=1) the dominant modes for 0.5 approximately less than U approximately less than 1. The electron distributions typically contain more than one inverted feature which could give rise to wave growth. It is shown that this can result in simultaneous amplification of more than one mode with each mode driven by a different feature and can be observed, for example, by differences in the rise times of the right and left circularly polarized components of the associated spike bursts.

  4. Ducted kinetic Alfven waves in plasma with steep density gradients

    SciTech Connect

    Houshmandyar, Saeid; Scime, Earl E.

    2011-11-15

    Given their high plasma density (n {approx} 10{sup 13} cm{sup -3}), it is theoretically possible to excite Alfven waves in a conventional, moderate length (L {approx} 2 m) helicon plasma source. However, helicon plasmas are decidedly inhomogeneous, having a steep radial density gradient, and typically have a significant background neutral pressure. The inhomogeneity introduces regions of kinetic and inertial Alfven wave propagation. Ion-neutral and electron-neutral collisions alter the Alfven wave dispersion characteristics. Here, we present the measurements of propagating kinetic Alfven waves in helium helicon plasma. The measured wave dispersion is well fit with a kinetic model that includes the effects of ion-neutral damping and that assumes the high density plasma core defines the radial extent of the wave propagation region. The measured wave amplitude versus plasma radius is consistent with the pile up of wave magnetic energy at the boundary between the kinetic and inertial regime regions.

  5. Direct Acceleration of Electrons in a Corrugated Plasma Channel

    SciTech Connect

    Palastro, J. P.; Antonsen, T. M.; Morshed, S.; York, A. G.; Layer, B.; Aubuchon, M.; Milchberg, H. M.; Froula, D. H.

    2009-01-22

    Direct laser acceleration of electrons provides a low power tabletop alternative to laser wakefield accelerators. Until recently, however, direct acceleration has been limited by diffraction, phase matching, and material damage thresholds. The development of the corrugated plasma channel [B. Layer et al., Phys. Rev. Lett. 99, 035001 (2007)] has removed all of these limitations and promises to allow direct acceleration of electrons over many centimeters at high gradients using femtosecond lasers [A. G. York et al., Phys Rev. Lett 100, 195001 (2008), J. P. Palastro et al., Phys. Rev. E 77, 036405 (2008)]. We present a simple analytic model of laser propagation in a corrugated plasma channel and examine the laser-electron beam interaction. Simulations show accelerating gradients of several hundred MeV/cm for laser powers much lower than required by standard laser wakefield schemes. In addition, the laser provides a transverse force that confines the high energy electrons on axis, while expelling low energy electrons.

  6. Gravity Wave Seeding of Equatorial Plasma Bubbles

    NASA Technical Reports Server (NTRS)

    Singh, Sardul; Johnson, F. S.; Power, R. A.

    1997-01-01

    Some examples from the Atmosphere Explorer E data showing plasma bubble development from wavy ion density structures in the bottomside F layer are described. The wavy structures mostly had east-west wavelengths of 150-800 km, in one example it was about 3000 km. The ionization troughs in the wavy structures later broke up into either a multiple-bubble patch or a single bubble, depending upon whether, in the precursor wavy structure, shorter wavelengths were superimposed on the larger scale wavelengths. In the multiple bubble patches, intrabubble spacings vaned from 55 km to 140 km. In a fully developed equatorial spread F case, east-west wavelengths from 690 km down to about 0.5 km were present simultaneously. The spacings between bubble patches or between bubbles in a patch appear to be determined by the wavelengths present in the precursor wave structure. In some cases, deeper bubbles developed on the western edge of a bubble patch, suggesting an east-west asymmetry. Simultaneous horizontal neutral wind measurements showed wavelike perturbations that were closely associated with perturbations in the plasma horizontal drift velocity. We argue that the wave structures observed here that served as the initial seed ion density perturbations were caused by gravity waves, strengthening the view that gravity waves seed equatorial spread F irregularities.

  7. High-efficiency acceleration of an electron beam in a plasma wakefield accelerator.

    PubMed

    Litos, M; Adli, E; An, W; Clarke, C I; Clayton, C E; Corde, S; Delahaye, J P; England, R J; Fisher, A S; Frederico, J; Gessner, S; Green, S Z; Hogan, M J; Joshi, C; Lu, W; Marsh, K A; Mori, W B; Muggli, P; Vafaei-Najafabadi, N; Walz, D; White, G; Wu, Z; Yakimenko, V; Yocky, G

    2014-11-01

    High-efficiency acceleration of charged particle beams at high gradients of energy gain per unit length is necessary to achieve an affordable and compact high-energy collider. The plasma wakefield accelerator is one concept being developed for this purpose. In plasma wakefield acceleration, a charge-density wake with high accelerating fields is driven by the passage of an ultra-relativistic bunch of charged particles (the drive bunch) through a plasma. If a second bunch of relativistic electrons (the trailing bunch) with sufficient charge follows in the wake of the drive bunch at an appropriate distance, it can be efficiently accelerated to high energy. Previous experiments using just a single 42-gigaelectronvolt drive bunch have accelerated electrons with a continuous energy spectrum and a maximum energy of up to 85 gigaelectronvolts from the tail of the same bunch in less than a metre of plasma. However, the total charge of these accelerated electrons was insufficient to extract a substantial amount of energy from the wake. Here we report high-efficiency acceleration of a discrete trailing bunch of electrons that contains sufficient charge to extract a substantial amount of energy from the high-gradient, nonlinear plasma wakefield accelerator. Specifically, we show the acceleration of about 74 picocoulombs of charge contained in the core of the trailing bunch in an accelerating gradient of about 4.4 gigavolts per metre. These core particles gain about 1.6 gigaelectronvolts of energy per particle, with a final energy spread as low as 0.7 per cent (2.0 per cent on average), and an energy-transfer efficiency from the wake to the bunch that can exceed 30 per cent (17.7 per cent on average). This acceleration of a distinct bunch of electrons containing a substantial charge and having a small energy spread with both a high accelerating gradient and a high energy-transfer efficiency represents a milestone in the development of plasma wakefield acceleration into a

  8. Collisional damping rates for plasma waves

    NASA Astrophysics Data System (ADS)

    Tigik, S. F.; Ziebell, L. F.; Yoon, P. H.

    2016-06-01

    The distinction between the plasma dynamics dominated by collisional transport versus collective processes has never been rigorously addressed until recently. A recent paper [P. H. Yoon et al., Phys. Rev. E 93, 033203 (2016)] formulates for the first time, a unified kinetic theory in which collective processes and collisional dynamics are systematically incorporated from first principles. One of the outcomes of such a formalism is the rigorous derivation of collisional damping rates for Langmuir and ion-acoustic waves, which can be contrasted to the heuristic customary approach. However, the results are given only in formal mathematical expressions. The present brief communication numerically evaluates the rigorous collisional damping rates by considering the case of plasma particles with Maxwellian velocity distribution function so as to assess the consequence of the rigorous formalism in a quantitative manner. Comparison with the heuristic ("Spitzer") formula shows that the accurate damping rates are much lower in magnitude than the conventional expression, which implies that the traditional approach over-estimates the importance of attenuation of plasma waves by collisional relaxation process. Such a finding may have a wide applicability ranging from laboratory to space and astrophysical plasmas.

  9. High-quality electron beams from a laser wakefield accelerator using plasma-channel guiding.

    PubMed

    Geddes, C G R; Toth, C S; Van Tilborg, J; Esarey, E; Schroeder, C B; Bruhwiler, D; Nieter, C; Cary, J; Leemans, W P

    2004-09-30

    Laser-driven accelerators, in which particles are accelerated by the electric field of a plasma wave (the wakefield) driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV m(-1) (refs 1-3). These fields are thousands of times greater than those achievable in conventional radio-frequency accelerators, spurring interest in laser accelerators as compact next-generation sources of energetic electrons and radiation. To date, however, acceleration distances have been severely limited by the lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance results in low-energy beams with 100 per cent electron energy spread, which limits potential applications. Here we demonstrate a laser accelerator that produces electron beams with an energy spread of a few per cent, low emittance and increased energy (more than 10(9) electrons above 80 MeV). Our technique involves the use of a preformed plasma density channel to guide a relativistically intense laser, resulting in a longer propagation distance. The results open the way for compact and tunable high-brightness sources of electrons and radiation. PMID:15457252

  10. Open questions on particle acceleration in strongly magnetized plasmas and how to answer them

    NASA Astrophysics Data System (ADS)

    Berthomier, Matthieu; Fazakerley, Andrew

    2016-04-01

    Particle acceleration mechanisms in solar system plasmas usually imply the conversion of electromagnetic energy into particle kinetic energy. These processes may take different forms depending on plasma magnetization but in most cases they involve multi-scale phenomena that cannot be described by ideal MHD. Little evidence has been gathered on how particle acceleration works in strongly magnetized plasmas. We will show how Earth's auroral regions provide the unique opportunity to address the open questions on particle acceleration in low beta plasmas. Single point observations in the auroral regions have suggested that acceleration by Alfvén waves would be responsible for filamentary acceleration along magnetic field lines. In the auroral regions, this mechanism would be associated with the generation of the sub-km scale auroral arcs. However single spacecraft measurements cannot evaluate the energy exchanged over a large volume of space between waves and particles. They cannot assess the efficiency of this mechanism, nor can they tell us where and when it is effective and how it relates to the evolving boundary conditions of the system. Numerical simulations alone cannot fully describe this multi-scale and non-local process in the inhomogeneous auroral plasma. Alternatively, it has been proposed from high-time resolution particle measurements in the auroral regions that localized parallel electric fields would explain the larger scale arcs that can be observed by onboard imagers. Single spacecraft measurements cannot follow the formation and evolution of these transient structures or the complex transport phenomena associated with the strong plasma turbulence that develop along magnetic field lines around these structures. Multi-point CLUSTER observations have shown how these potential acceleration structures were distributed in space and time. However we still miss the dynamic picture of how these structures are created on how they can be maintained in space and

  11. Particle Acceleration in SN1006 Shock Waves

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Technical Monitor); Raymond, John C.

    2004-01-01

    The FUSE data have been reduced, and a paper on the results is in progress. The main results have been presented in a poster at the January 2004 AAS meeting and an ApJ paper in press. The primary result is that the widths of the 0 VI lines in the NW filament are a bit less than the width expected if the oxygen kinetic temperature is 16 times the proton temperature (mass proportional heating). This is at variance with measurements of shocks in the heliosphere, where preferential heating of oxygen and other heavy species is observed. The paper discusses the theoretical implications for collisionless shock wave physics. A secondary result is that no O VI emission was observed from the NE filament. While the very different particle distribution in that region can partially account for the weakness of the O VI lines, the simplest interpretation is that the pre-shock density in the NE is less than 0.22 times the density in the NW.

  12. Wakefield generation and GeV acceleration in tapered plasma channels

    NASA Astrophysics Data System (ADS)

    Sprangle, P.; Hafizi, B.; Peñano, J. R.; Hubbard, R. F.; Ting, A.; Moore, C. I.; Gordon, D. F.; Zigler, A.; Kaganovich, D.; Antonsen, T. M.

    2001-05-01

    To achieve multi-GeV electron energies in the laser wakefield accelerator (LWFA), it is necessary to propagate an intense laser pulse long distances in a plasma without disruption. One of the purposes of this paper is to evaluate the stability properties of intense laser pulses propagating extended distances (many tens of Rayleigh ranges) in plasma channels. A three-dimensional envelope equation for the laser field is derived that includes nonparaxial effects such as group velocity dispersion, as well as wakefield and relativistic nonlinearities. It is shown that in the broad beam, short pulse limit the nonlinear terms in the wave equation that lead to Raman and modulation instabilities cancel. This cancellation can result in pulse propagation over extended distances, limited only by dispersion. Since relativistic focusing is not effective for short pulses, the plasma channel provides the guiding necessary for long distance propagation. Long pulses (greater than several plasma wavelengths), on the other hand, experience substantial modification due to Raman and modulation instabilities. For both short and long pulses the seed for instability growth is inherently determined by the pulse shape and not by background noise. These results would indicate that the self-modulated LWFA is not the optimal configuration for achieving high energies. The standard LWFA, although having smaller accelerating fields, can provide acceleration for longer distances. It is shown that by increasing the plasma density as a function of distance, the phase velocity of the accelerating field behind the laser pulse can be made equal to the speed of light. Thus electron dephasing in the accelerating wakefield can be avoided and energy gain increased by spatially tapering the plasma channel. Depending on the tapering gradient, this luminous wakefield phase velocity is obtained several plasma wavelengths behind the laser pulse. Simulations of laser pulses propagating in a tapered plasma channel

  13. Startup performance of the traveling wave versus standing wave linear accelerator.

    PubMed

    Buchgeister, M; Nüsslin, F

    1998-04-01

    The startup performance of medical linear accelerators is of increasing importance for modern radiotherapy techniques. The traveling wave-type linear accelerator of the SL series of Philips (now Elekta Oncology Systems) has been modified in its flight tube design to meet this goal of a fast rise time of the radiation field. The new slitless flight tube combined with a redesigned gun servo electronic now achieves start up times of the radiation comparable with those of a standing wave linear accelerator (Siemens Mevatron) according to our measurements. PMID:9571616

  14. The effect of external magnetic field on plasma acceleration in electromagnetic railgun channel

    NASA Astrophysics Data System (ADS)

    Bobashev, S. V.; Zhukov, B. G.; Kurakin, R. O.; Ponyaev, S. A.; Reznikov, B. I.

    2016-03-01

    We have studied the effect of an external magnetic field on the dynamics of a free plasma piston (PP) accelerated without solid striker armature in an electromagnetic railgun channel filled with various gases (argon or helium). It is established that, as the applied magnetic field grows, the velocity of a shock wave generated by PP in the channel increases. The experimental results are compared to a theoretical model that takes into account the gas pressure force behind the shock wave and the drag force that arises when erosion mass entering the channel is partly entrained by the accelerated plasma. The results of model calculations are in satisfactory agreement with experimental data. The discrepancy somewhat increases with the applied field, but the maximum deviation still does not exceed 20%.

  15. Wave-CAIPI for Highly Accelerated 3D Imaging

    PubMed Central

    Bilgic, Berkin; Gagoski, Borjan A.; Cauley, Stephen F.; Fan, Audrey P.; Polimeni, Jonathan R.; Grant, P. Ellen; Wald, Lawrence L.; Setsompop, Kawin

    2014-01-01

    Purpose To introduce the Wave-CAIPI (Controlled Aliasing in Parallel Imaging) acquisition and reconstruction technique for highly accelerated 3D imaging with negligible g-factor and artifact penalties. Methods The Wave-CAIPI 3D acquisition involves playing sinusoidal gy and gz gradients during the readout of each kx encoding line, while modifying the 3D phase encoding strategy to incur inter-slice shifts as in 2D-CAIPI acquisitions. The resulting acquisition spreads the aliasing evenly in all spatial directions, thereby taking full advantage of 3D coil sensitivity distribution. By expressing the voxel spreading effect as a convolution in image space, an efficient reconstruction scheme that does not require data gridding is proposed. Rapid acquisition and high quality image reconstruction with Wave-CAIPI is demonstrated for high-resolution magnitude and phase imaging and Quantitative Susceptibility Mapping (QSM). Results Wave-CAIPI enables full-brain gradient echo (GRE) acquisition at 1 mm isotropic voxel size and R=3×3 acceleration with maximum g-factors of 1.08 at 3T, and 1.05 at 7T. Relative to the other advanced Cartesian encoding strategies 2D-CAIPI and Bunched Phase Encoding, Wave-CAIPI yields up to 2-fold reduction in maximum g-factor for 9-fold acceleration at both field strengths. Conclusion Wave-CAIPI allows highly accelerated 3D acquisitions with low artifact and negligible g-factor penalties, and may facilitate clinical application of high-resolution volumetric imaging. PMID:24986223

  16. Measurement of acceleration in femtosecond laser-plasmas

    SciTech Connect

    Haessner, R.; Theobald, W.; Niedermeier, S.; Michelmann, K.; Feurer, T.; Schillinger, H.; Sauerbrey, R.

    1998-02-20

    Accelerations up to 4x10{sup 19} m/s{sup 2} are measured in femtosecond laser-produced plasmas at intensities of 10{sup 18} W/cm{sup 2} using the Frequency Resolved Optical Gating (FROG) technique. A high density plasma is formed by focusing an ultrashort unchirped laser pulse on a plane carbon target and part of the reflected pulse is eventually detected by a FROG autocorrelator. Radiation pressure and thermal pressure accelerate the plasma which causes a chirp in the reflected laser pulse. The retrieved phase and amplitude information reveal that the plasma motion is dominated by the large light pressure which pushes the plasma into the target. This is supported by theoretical estimates and by the results of independently measured time integrated spectra of the reflected pulse.

  17. Electron acceleration in long scale laser - plasma interactions

    NASA Astrophysics Data System (ADS)

    Kamperidis, Christos; Mangles, Stuart P. D.; Nagel, Sabrina R.; Bellei, Claudio; Krushelnick, Karl; Najmudin, Zulfikar; Bourgeois, Nicola; Marques, Jean Raphael; Kaluza, Malte C.

    2006-10-01

    Broad energy electron bunches are produced through the Self-Modulated Laser Wakefield Acceleration scheme at the 30J, 300 fsec laser, LULI, France, with long scale underdense plasmas, created in a He filled gas cell and in He gas jet nozzles of various lengths. With c.τlaser>>λplasma, electrons reached Emax ˜ 200MeV. By carefully controlling the dynamics of the interaction and by simultaneous observations of the electron energy spectra and the forward emitted optical spectrum, we found that a plasma density threshold (˜5.10^18 cm-3) exists for quasi-monoenergetic (˜30MeV) features to appear. The overall plasma channel size was inferred from the collected Thomson scattered light. 2D PIC simulations indicate that the main long laser pulse breaks up into small pulselets that eventually get compressed and tightly focused inside the first few plasma periods, leading to a bubble like acceleration of electron bunches.

  18. Weakly nonlinear dust ion-acoustic shock waves in a dusty plasma with nonthermal electrons

    SciTech Connect

    Berbri, Abderrezak; Tribeche, Mouloud

    2009-05-15

    Weakly nonlinear dust ion-acoustic (DIA) shock waves are investigated in a dusty plasma with nonthermal electrons. A modified Korteweg-de Vries equation with a cubic nonlinearity is derived. Due to the net negative dust charge {mu}Z{sub d} and electron nonthermality, the present plasma model can admit compressive and rarefactive weak DIA shock waves. The effect of increasing {mu}Z{sub d} is to lower the critical nonthermal parameter {beta}{sub c} above which only rarefactive DIA shock waves are admitted. Our investigation may help to understand the nonlinear structures observed in the auroral acceleration regions.

  19. Multistage coupling of independent laser-plasma accelerators.

    PubMed

    Steinke, S; van Tilborg, J; Benedetti, C; Geddes, C G R; Schroeder, C B; Daniels, J; Swanson, K K; Gonsalves, A J; Nakamura, K; Matlis, N H; Shaw, B H; Esarey, E; Leemans, W P

    2016-02-11

    Laser-plasma accelerators (LPAs) are capable of accelerating charged particles to very high energies in very compact structures. In theory, therefore, they offer advantages over conventional, large-scale particle accelerators. However, the energy gain in a single-stage LPA can be limited by laser diffraction, dephasing, electron-beam loading and laser-energy depletion. The problem of laser diffraction can be addressed by using laser-pulse guiding and preformed plasma waveguides to maintain the required laser intensity over distances of many Rayleigh lengths; dephasing can be mitigated by longitudinal tailoring of the plasma density; and beam loading can be controlled by proper shaping of the electron beam. To increase the beam energy further, it is necessary to tackle the problem of the depletion of laser energy, by sequencing the accelerator into stages, each powered by a separate laser pulse. Here, we present results from an experiment that demonstrates such staging. Two LPA stages were coupled over a short distance (as is needed to preserve the average acceleration gradient) by a plasma mirror. Stable electron beams from a first LPA were focused to a twenty-micrometre radius--by a discharge capillary-based active plasma lens--into a second LPA, such that the beams interacted with the wakefield excited by a separate laser. Staged acceleration by the wakefield of the second stage is detected via an energy gain of 100 megaelectronvolts for a subset of the electron beam. Changing the arrival time of the electron beam with respect to the second-stage laser pulse allowed us to reconstruct the temporal wakefield structure and to determine the plasma density. Our results indicate that the fundamental limitation to energy gain presented by laser depletion can be overcome by using staged acceleration, suggesting a way of reaching the electron energies required for collider applications. PMID:26829223

  20. Alfvén wave collisions, the fundamental building block of plasma turbulence. IV. Laboratory experiment

    SciTech Connect

    Drake, D. J.; Schroeder, J. W. R.; Howes, G. G.; Kletzing, C. A.; Skiff, F.; Carter, T. A.; Auerbach, D. W.

    2013-07-15

    Turbulence is a phenomenon found throughout space and astrophysical plasmas. It plays an important role in solar coronal heating, acceleration of the solar wind, and heating of the interstellar medium. Turbulence in these regimes is dominated by Alfvén waves. Most turbulence theories have been established using ideal plasma models, such as incompressible MHD. However, there has been no experimental evidence to support the use of such models for weakly to moderately collisional plasmas which are relevant to various space and astrophysical plasma environments. We present the first experiment to measure the nonlinear interaction between two counterpropagating Alfvén waves, which is the building block for astrophysical turbulence theories. We present here four distinct tests that demonstrate conclusively that we have indeed measured the daughter Alfvén wave generated nonlinearly by a collision between counterpropagating Alfvén waves.

  1. Nonlinear Electromagnetic Waves and Spherical Arc-Polarized Waves in Space Plasmas

    NASA Technical Reports Server (NTRS)

    Tsurutani, B.; Ho, Christian M.; Arballo, John K.; Lakhina, Gurbax S.; Glassmeier, Karl-Heinz; Neubauer, Fritz M.

    1997-01-01

    We review observations of nonlinear plasma waves detected by interplanetary spacecraft. For this paper we will focus primarily on the phase-steepened properties of such waves. Plasma waves at comet Giacobini-Zinner measured by the International Cometary Explorer (ICE), at comets Halley and Grigg-Skjellerup measured by Giotto, and interplanetary Alfven waves measured by Ulysses, will be discussed and intercompared.

  2. Simple model of plasma acceleration in a magnetic nozzle

    NASA Technical Reports Server (NTRS)

    Sercel, Joel C.

    1990-01-01

    A collisionless, steady-state, cold-plasma model is used to calculate the three-dimensional trajectory of a plasma as it is accelerated through a diverging magnetic field. The magnetic field is assumed to be axisymmetric with nonzero radial and axial components and zero azimuthal component. Although random thermal motion of plasma species is neglected in the cold plasma approximation, an important effect of plasma thermal energy is accounted for in the model as the kinetic energy of electrons in their Larmor motion about magnetic field lines. Calculations based on this model confirm previous studies which suggested that plasma separation from the field of a magnetic nozzle can take place even in the absence of collisional diffusion. It is shown that plasma divergence in a magnetic nozzle can be controlled by tailoring the field geometry.

  3. Cut-off period for slow magnetoacoustic waves in coronal plasma structures

    NASA Astrophysics Data System (ADS)

    Afanasyev, A. N.; Nakariakov, V. M.

    2015-10-01

    Context. There is abundant observational evidence of longitudinal compressive waves in plasma structures of the solar corona, which are confidently interpreted in terms of slow magnetoacoustic waves. The uses of coronal slow waves in plasma diagnostics, as well as analysis of their possible contribution to coronal heating and the solar wind acceleration, require detailed theoretical modelling. Aims: We investigate the effects of obliqueness, magnetic field, and non-uniformity of the medium on the evolution of long-wavelength slow magnetoacoustic waves guided by field-aligned plasma non-uniformities, also called tube waves. Special attention is paid to the cut-off effect due to the gravity stratification of the coronal plasma. Methods: We study the behaviour of linear tube waves in a vertical untwisted straight field-aligned isothermal plasma cylinder. We apply the thin flux tube approximation, taking into account effects of stratification caused by gravity. The dispersion due to the finite radius of the flux tube is neglected. We analyse the behaviour of the cut-off period for an exponentially divergent magnetic flux tube filled in with a stratified plasma. The results obtained are compared with the known cases of the constant Alfven speed and the pure acoustic wave. Results: We derive the wave equation for tube waves and reduce it to the form of the Klein-Gordon equation with varying coefficients, which explicitly contains the cut-off frequency. The cut-off period is found to vary with height, decreasing significantly in the low-beta plasma and in the plasma with the beta of the order of unity. The depressions in the cut-off period profiles can affect the propagation of longitudinal waves along coronal plasma structures towards the higher corona and can form coronal resonators.

  4. First results of the plasma wakefield acceleration experiment at PITZ

    NASA Astrophysics Data System (ADS)

    Lishilin, O.; Gross, M.; Brinkmann, R.; Engel, J.; Grüner, F.; Koss, G.; Krasilnikov, M.; Martinez de la Ossa, A.; Mehrling, T.; Osterhoff, J.; Pathak, G.; Philipp, S.; Renier, Y.; Richter, D.; Schroeder, C.; Schütze, R.; Stephan, F.

    2016-09-01

    The self-modulation instability of long particle beams was proposed as a new mechanism to produce driver beams for proton driven plasma wakefield acceleration (PWFA). The PWFA experiment at the Photo Injector Test facility at DESY, Zeuthen site (PITZ) was launched to experimentally demonstrate and study the self-modulation of long electron beams in plasma. Key aspects for the experiment are the very flexible photocathode laser system, a plasma cell and well-developed beam diagnostics. In this contribution we report about the plasma cell design, preparatory experiments and the results of the first PWFA experiment at PITZ.

  5. Electron Acceleration in Cavitated Channels Formed by a Petawatt Laser in Low-Density Plasma

    SciTech Connect

    Mangles, S.P.D.; Walton, B.R.; Najmudin, Z.; Dangor, A.E.; Gopal, A.; Rozmus, W.; Tatarakis, M.; Thomas, A.G.R.; Wei, M.S.; Krushelnick, K.; Tzoufras, M.; Mori, W.B.; Tsung, F.S.; Clarke, R.J.; Hernandez-Gomez, C.; Evans, R.G.; Fritzler, S.

    2005-06-24

    The spectra of energetic electrons produced by a laser interaction with underdense plasma have been measured at intensities >3x10{sup 20} W cm{sup -2}. Electron energies in excess of 300 MeV have been observed. Measurements of the transmitted laser spectrum indicate that there is no correlation between the acceleration of electrons and plasma wave production. Particle-in-cell simulations show that the laser ponderomotive force produces an ion channel. The interaction of the laser field with the nonlinear focusing force of the channel leads to electron acceleration. The majority of the electrons never reach the betatron resonance but those which gain the highest energies do so. The acceleration process exhibits a strong sensitivity to initial conditions with particles that start within a fraction of a laser wavelength following completely different trajectories and gaining markedly different energies.

  6. Nonlinear wave interactions in shallow water magnetohydrodynamics of astrophysical plasma

    NASA Astrophysics Data System (ADS)

    Klimachkov, D. A.; Petrosyan, A. S.

    2016-05-01

    The rotating magnetohydrodynamic flows of a thin layer of astrophysical and space plasmas with a free surface in a vertical external magnetic field are considered in the shallow water approximation. The presence of a vertical external magnetic field changes significantly the dynamics of wave processes in an astrophysical plasma, in contrast to a neutral fluid and a plasma layer in an external toroidal magnetic field. There are three-wave nonlinear interactions in the case under consideration. Using the asymptotic method of multiscale expansions, we have derived nonlinear equations for the interaction of wave packets: three magneto- Poincare waves, three magnetostrophic waves, two magneto-Poincare and one magnetostrophic waves, and two magnetostrophic and one magneto-Poincare waves. The existence of decay instabilities and parametric amplification is predicted. We show that a magneto-Poincare wave decays into two magneto-Poincare waves, a magnetostrophic wave decays into two magnetostrophic waves, a magneto-Poincare wave decays into one magneto-Poincare and one magnetostrophic waves, and a magnetostrophic wave decays into one magnetostrophic and one magneto-Poincare waves. There are the following parametric amplification mechanisms: the parametric amplification of magneto-Poincare waves, the parametric amplification of magnetostrophic waves, the amplification of a magneto-Poincare wave in the field of a magnetostrophic wave, and the amplification of a magnetostrophic wave in the field of a magneto-Poincare wave. The instability growth rates and parametric amplification factors have been found for the corresponding processes.

  7. On the theory of Langmuir waves in a quantum plasma

    SciTech Connect

    Kuzelev, M. V.

    2010-04-15

    Nonlinear quantum-mechanical equations are derived for Langmuir waves in an isotropic electron collisionless plasma. A general analysis of dispersion relations is carried out for complex spectra of Langmuir waves and van Kampen waves in a quantum plasma with an arbitrary electron momentum distribution. Quantum nonlinear collisionless Landau damping in Maxwellian and degenerate plasmas is studied. It is shown that collisionless damping of Langmuir waves (including zero sound) occurs in collisionless plasmas due to quantum correction in the Cherenkov absorption condition, which is a purely quantum effect. Solutions to the quantum dispersion equation are obtained for a degenerate plasma.

  8. Ion Acceleration in a Solitary Wave by Laser Pulse with Ramping-up Amplitude

    NASA Astrophysics Data System (ADS)

    He, Min-Qing; Tripathi, Vipin; Liu, Chuan-Sheng; Shao, Xi; Liu, Tung-Chang; Su, Jao-Jang; Sheng, Zheng-Ming

    2012-10-01

    Recent work by Jung et al. demonstrated experimentally the acceleration of mono-energetic ion beam by solitary waves generated and maintained by laser light with ramping-up amplitude.footnotetextD. Jung, L. Yin, B.J. Albright, D.C. Gautier, R. H"orlein, D. Kiefer, A. Henig, R. Johnson, S. Letzring, S. Palaniyappan, R. Shah, T. Shimada, X.Q. Yan, K.J. Bowers, T. Tajima, J.C. Fern'andez, D. Habs, and B.M. Hegelich, Phys. Rev. Lett. 107,115002(2011). Theoretical model is developed in this work to study the formation of the solitary wave and effects of the radiation pressure force on a soliton in the accelerating plasma. 2D Particle-In-Cell (PIC) simulations are performed to compare and validate the theory. Differences in generating and maintaining solitary wave for laser with and without ramping-up amplitude are also investigated. We will also investigate effects of radiation pressure acceleration of plasma with near critical density.

  9. Scaling of Energy Gain with Plasma Parameters in a Plasma Wakefield Accelerator

    SciTech Connect

    Blumenfeld, I.; Decker, F.J.; Hogan, M.J.; Ischebeck, R.; Iverson, R.H.; Kirby, N.A.; Siemann, Robert H.; Walz, D.R.; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; Katsouleas, T.C.; Muggli, P.; Oz, E.; /Southern California U.

    2008-01-28

    We have recently demonstrating the doubling of the energy of particles of the ultra-short, ultra-relativistic electron bunches of the Stanford Linear Accelerator Center [1]. This energy doubling occurred in a plasma only 85 cm-long with a density of {approx} 2.6 x 10{sup 17} e{sup -}/cm{sup -3}. This milestone is the result of systematic measurements that show the scaling of the energy gain with plasma length and density, and show the reproducibility and the stability of the acceleration process. We show that the energy gain increases linearly with plasma length from 13 to 31 cm. These are key steps toward the application of beam-driven plasma accelerators or plasma wakefield accelerators (PWFA) to doubling the energy of a future linear collider without doubling its length.

  10. Electron trapping and acceleration across a parabolic plasma density profile.

    PubMed

    Kim, J U; Hafz, N; Suk, H

    2004-02-01

    It is known that as a laser wakefield passes through a downward density transition in a plasma some portion of the background electrons are trapped in the laser wakefield and the trapped electrons are accelerated to relativistic high energies over a very short distance. In this study, by using a two-dimensional (2D) particle-in-cell (PIC) simulation, we suggest an experimental scheme that can manipulate electron trapping and acceleration across a parabolic plasma density channel, which is easier to produce and more feasible to apply to the laser wakefield acceleration experiments. In this study, 2D PIC simulation results for the physical characteristics of the electron bunches that are emitted from the parabolic density plasma channel are reported in great detail. PMID:14995568

  11. Intense tera-hertz laser driven proton acceleration in plasmas

    NASA Astrophysics Data System (ADS)

    Sharma, A.; Tibai, Z.; Hebling, J.

    2016-06-01

    We investigate the acceleration of a proton beam driven by intense tera-hertz (THz) laser field from a near critical density hydrogen plasma. Two-dimension-in-space and three-dimension-in-velocity particle-in-cell simulation results show that a relatively long wavelength and an intense THz laser can be employed for proton acceleration to high energies from near critical density plasmas. We adopt here the electromagnetic field in a long wavelength (0.33 THz) regime in contrast to the optical and/or near infrared wavelength regime, which offers distinct advantages due to their long wavelength ( λ = 350 μ m ), such as the λ 2 scaling of the electron ponderomotive energy. Simulation study delineates the evolution of THz laser field in a near critical plasma reflecting the enhancement in the electric field of laser, which can be of high relevance for staged or post ion acceleration.

  12. Characterising the acceleration phase of blast wave formation

    SciTech Connect

    Fox, T. E. Pasley, J.; Robinson, A. P. L.; Schmitz, H.

    2014-10-15

    Intensely heated, localised regions in uniform fluids will rapidly expand and generate an outwardly propagating blast wave. The Sedov-Taylor self-similar solution for such blast waves has long been studied and applied to a variety of scenarios. A characteristic time for their formation has also long been identified using dimensional analysis, which by its very nature, can offer several interpretations. We propose that, rather than simply being a characteristic time, it may be interpreted as the definitive time taken for a blast wave resulting from an intense explosion in a uniform media to contain its maximum kinetic energy. A scaling relation for this measure of the acceleration phase, preceding the establishment of the blast wave, is presented and confirmed using a 1D planar hydrodynamic model.

  13. Simulations of a meter-long plasma wakefield accelerator

    SciTech Connect

    Lee, S.; Katsouleas, T.; Hemker, R.; Mori, W. B.

    2000-06-01

    Full-scale particle-in-cell simulations of a meter-long plasma wakefield accelerator (PWFA) are presented in two dimensions. The results support the design of a current PWFA experiment in the nonlinear blowout regime where analytic solutions are intractable. A relativistic electron bunch excites a plasma wake that accelerates trailing particles at rates of several hundred MeV/m. A comparison is made of various simulation codes, and a parallel object-oriented code OSIRIS is used to model a full meter of acceleration. Excellent agreement is obtained between the simulations and analytic expressions for the transverse betatron oscillations of the beam. The simulations are used to develop scaling laws for designing future multi-GeV accelerator experiments. (c) 2000 The American Physical Society.

  14. Summary report: working group 2 on 'Plasma Based AccelerationConcepts'

    SciTech Connect

    Esarey, E.; Leemans, Wim

    1998-09-01

    A summary of the talks, papers and discussion sessions presented in the Working Group on Plasma Based Acceleration Concepts is given within the context of the progress towards a 1 GeV laser driven accelerator module. The topics covered within the Working Group were self-modulated laser wakefield acceleration, standard laser wakefield acceleration, plasma beatwave acceleration, laser guiding and wake excitation in plasma channels, plasma wakefield acceleration, plasma lenses and optical injection techniques for laser wakefield accelerators. An overview will be given of the present status of experimental and theoretical progress as well as an outlook towards the future physics and technological challenges for the development of an optimized accelerator module.

  15. Stochastic Acceleration of Galactic Cosmic Rays by Compressible Plasma Fluctuations in Supernova Shells

    NASA Astrophysics Data System (ADS)

    Zhang, Ming

    2015-10-01

    A theory of 2-stage acceleration of Galactic cosmic rays in supernova remnants is proposed. The first stage is accomplished by the supernova shock front, where a power-law spectrum is established up to a certain cutoff energy. It is followed by stochastic acceleration with compressible waves/turbulence in the downstream medium. With a broad \\propto {k}-2 spectrum for the compressible plasma fluctuations, the rate of stochastic acceleration is constant over a wide range of particle momentum. In this case, the stochastic acceleration process extends the power-law spectrum cutoff energy of Galactic cosmic rays to the knee without changing the spectral slope. This situation happens as long as the rate of stochastic acceleration is faster than 1/5 of the adiabatic cooling rate. A steeper spectrum of compressible plasma fluctuations that concentrate their power in long wavelengths will accelerate cosmic rays to the knee with a small bump before its cutoff in the comic-ray energy spectrum. This theory does not require a strong amplification of the magnetic field in the upstream interstellar medium in order to accelerate cosmic rays to the knee energy.

  16. Laser acceleration of electrons in two-dimensionally inhomogeneous plasma at the boundary of a metal foil

    SciTech Connect

    Pugachev, L. P. Andreev, N. E. Levashov, P. R.; Malkov, Yu. A. Stepanov, A. N. Yashunin, D. A.

    2015-07-15

    The electron acceleration mechanism associated with the generation of a plasma wave due to self-modulation instability of laser radiation in a subcritical plasma produced by a laser prepulse coming 10 ns before the arrival of the main intense femtosecond pulse is considered. Three-dimensional particle-in-cell simulations of the interaction of laser radiation with two-dimensionally inhomogeneous subcritical plasma have shown that, for a sufficiently strong plasma inhomogeneity and a sharp front of the laser pulse, efficient plasma wave excitation, electron trapping, and generation of collimated electron beams with energies on the order of 0.2–0.5 MeV can occur. The simulation results agree with experiments on the generation of collimated beams of accelerated electrons from metal targets irradiated by intense femtosecond laser pulses.

  17. Mercury ion thruster research, 1977. [plasma acceleration

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1977-01-01

    The measured ion beam divergence characteristics of two and three-grid, multiaperture accelerator systems are presented. The effects of perveance, geometry, net-to-total accelerating voltage, discharge voltage and propellant are examined. The applicability of a model describing doubly-charged ion densities in mercury thrusters is demonstrated for an 8-cm diameter thruster. The results of detailed Langmuir probing of the interior of an operating cathode are given and used to determine the ionization fraction as a function of position upstream of the cathode orifice. A mathematical model of discharge chamber electron diffusion and collection processes is presented along with scaling laws useful in estimating performance of large diameter and/or high specific impluse thrusters. A model describing the production of ionized molecular nitrogen in ion thrusters is included.

  18. Coherent kilo-electron-volt backscattering from plasma-wave boosted relativistic electron mirrors

    SciTech Connect

    Li, F. Y.; Chen, M. Liu, Y.; Zhang, J.; Sheng, Z. M. E-mail: zmsheng@sjtu.edu.cn; Wu, H. C.; Meyer-ter-Vehn, J.; Mori, W. B.

    2014-10-20

    A different parameter regime of laser wakefield acceleration driven by sub-petawatt femtosecond lasers is proposed, which enables the generation of relativistic electron mirrors further accelerated by the plasma wave. Integrated particle-in-cell simulation, including both the mirror formation and Thomson scattering, demonstrates that efficient coherent backscattering up to keV photon energy can be obtained with moderate driving laser intensities and high density gas targets.

  19. Plasma wakefield acceleration with a modulated proton bunch

    SciTech Connect

    Caldwell, A.; Lotov, K. V.

    2011-10-15

    The plasma wakefield amplitudes which could be achieved via the modulation of a long proton bunch are investigated. We find that in the limit of long bunches compared to the plasma wavelength, the strength of the accelerating fields is directly proportional to the number of particles in the drive bunch and inversely proportional to the square of the transverse bunch size. The scaling laws were tested and verified in detailed simulations using parameters of existing proton accelerators, and large electric fields were achieved, reaching 1 GV/m for LHC bunches. Energy gains for test electrons beyond 6 TeV were found in this case.

  20. Thermal emittance from ionization-induced trapping in plasma accelerators

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    The minimum obtainable transverse emittance (thermal emittance) of electron beams generated and trapped in plasma-based accelerators using laser ionization injection is examined. The initial transverse phase space distribution following ionization and passage through the laser is derived, and expressions for the normalized transverse beam emittance, both along and orthogonal to the laser polarization, are presented. Results are compared to particle-in-cell simulations. Ultralow emittance beams can be generated using laser ionization injection into plasma accelerators, and examples are presented showing normalized emittances on the order of tens of nm.

  1. Nonplanar Shock Waves in Dusty Plasmas

    SciTech Connect

    Mamun, A. A.; Shukla, P. K.

    2011-11-29

    Nonplanar (viz. cylindrical and spherical) electro-acoustic [dust-ion-acoustic (DIA) and dust-acoustic (DA)] shock waves have been investigated by employing the reductive perturbation method. The dust charge fluctuation (strong correlation among highly charged dust) is the source of dissipation, and is responsible for the formation of the DIA (DA) shock structures. The effects of cylindrical and spherical geometries on the time evolution of DIA and DA shock structures are examined and identified. The combined effects of vortex-like electron distribution and dust charge fluctuation (dust-correlation and effective dust-temperature) on the basic features of nonplanar DIA (DA) shock waves are pinpointed. The implications of our results in laboratory dusty plasma experiments are briefly discussed.

  2. Nonplanar Shock Waves in Dusty Plasmas

    NASA Astrophysics Data System (ADS)

    Mamun, A. A.; Shukla, P. K.

    2011-11-01

    Nonplanar (viz. cylindrical and spherical) electro-acoustic [dust-ion-acoustic (DIA) and dust-acoustic (DA)] shock waves have been investigated by employing the reductive perturbation method. The dust charge fluctuation (strong correlation among highly charged dust) is the source of dissipation, and is responsible for the formation of the DIA (DA) shock structures. The effects of cylindrical and spherical geometries on the time evolution of DIA and DA shock structures are examined and identified. The combined effects of vortex-like electron distribution and dust charge fluctuation (dust-correlation and effective dust-temperature) on the basic features of nonplanar DIA (DA) shock waves are pinpointed. The implications of our results in laboratory dusty plasma experiments are briefly discussed.

  3. Plasma waves and jets from moving conductors

    NASA Astrophysics Data System (ADS)

    Gralla, Samuel E.; Zimmerman, Peter

    2016-06-01

    We consider force-free plasma waves launched by the motion of conducting material through a magnetic field. We develop a spacetime-covariant formalism for perturbations of a uniform magnetic field and show how the transverse motion of a conducting fluid acts as a source. We show that fast-mode waves are sourced by the compressibility of the fluid, with incompressible fluids launching a pure-Alfvén outflow. Remarkably, this outflow can be written down in closed form for an arbitrary time-dependent, nonaxisymmetric incompressible flow. The instantaneous flow velocity is imprinted on the magnetic field and transmitted away at the speed of light, carrying detailed information about the conducting source at the time of emission. These results can be applied to transients in pulsar outflows and to jets from neutron stars orbiting in the magnetosphere of another compact object. We discuss jets from moving conductors in some detail.

  4. Front acceleration by dynamic selection in Fisher population waves

    NASA Astrophysics Data System (ADS)

    Bénichou, O.; Calvez, V.; Meunier, N.; Voituriez, R.

    2012-10-01

    We introduce a minimal model of population range expansion in which the phenotypes of individuals present no selective advantage and differ only in their diffusion rate. We show that such neutral phenotypic variability (i.e., that does not modify the growth rate) alone can yield phenotype segregation at the front edge, even in absence of genetic noise, and significantly impact the dynamical properties of the expansion wave. We present an exact asymptotic traveling wave solution and show analytically that phenotype segregation accelerates the front propagation. The results are compatible with field observations such as invasions of cane toads in Australia or bush crickets in Britain.

  5. Revisiting the thermal effect on shock wave propagation in weakly ionized plasmas

    NASA Astrophysics Data System (ADS)

    Zhou, Qianhong; Dong, Zhiwei; Yang, Wei

    2016-07-01

    Many researchers have investigated shock propagation in weakly ionized plasmas and observed the following anomalous effects: shock acceleration, shock recovery, shock weakening, shock spreading, and splitting. It was generally accepted that the thermal effect can explain most of the experimental results. However, little attention was paid to the shock recovery. In this paper, the shock wave propagation in weakly ionized plasmas is studied by fluid simulation. It is found that the shock acceleration, weakening, and splitting appear after it enters the plasma (thermal) region. The shock splits into two parts right after it leaves the thermal region. The distance between the splitted shocks keeps decreasing until they recover to one. This paper can explain a whole set of features of the shock wave propagation in weakly ionized plasmas. It is also found that both the shock curvature and the splitting present the same photoacoustic deflection (PAD) signals, so they cannot be distinguished by the PAD experiments.

  6. Effect of plasma inhomogeneity on plasma wakefield acceleration driven by long bunches

    SciTech Connect

    Lotov, K. V.; Pukhov, A.; Caldwell, A.

    2013-01-15

    Effects of plasma inhomogeneity on self-modulating proton bunches and accelerated electrons were studied numerically. The main effect is the change of the wakefield wavelength which results in phase shifts and loss of accelerated particles. This effect imposes severe constraints on density uniformity in plasma wakefield accelerators driven by long particle bunches. The transverse two stream instability that transforms the long bunch into a train of micro-bunches is less sensitive to density inhomogeneity than are the accelerated particles. The bunch freely passes through increased density regions and interacts with reduced density regions.

  7. Enhanced efficiency of plasma acceleration in the laser-induced cavity pressure acceleration scheme

    NASA Astrophysics Data System (ADS)

    Badziak, J.; Rosiński, M.; Jabłoński, S.; Pisarczyk, T.; Chodukowski, T.; Parys, P.; Rączka, P.; Krousky, E.; Ullschmied, J.; Liska, R.; Kucharik, M.

    2015-01-01

    Among various methods for the acceleration of dense plasmas the mechanism called laser-induced cavity pressure acceleration (LICPA) is capable of achieving the highest energetic efficiency. In the LICPA scheme, a projectile placed in a cavity is accelerated along a guiding channel by the laser-induced thermal plasma pressure or by the radiation pressure of an intense laser radiation trapped in the cavity. This arrangement leads to a significant enhancement of the hydrodynamic or electromagnetic forces driving the projectile, relative to standard laser acceleration schemes. The aim of this paper is to review recent experimental and numerical works on LICPA with the emphasis on the acceleration of heavy plasma macroparticles and dense ion beams. The main experimental part concerns the research carried out at the kilojoule sub-nanosecond PALS laser facility in Prague. Our measurements performed at this facility, supported by advanced two-dimensional hydrodynamic simulations, have demonstrated that the LICPA accelerator working in the long-pulse hydrodynamic regime can be a highly efficient tool for the acceleration of heavy plasma macroparticles to hyper-velocities and the generation of ultra-high-pressure (>100 Mbar) shocks through the collision of the macroparticle with a solid target. The energetic efficiency of the macroparticle acceleration and the shock generation has been found to be significantly higher than that for other laser-based methods used so far. Using particle-in-cell simulations it is shown that the LICPA scheme is highly efficient also in the short-pulse high-intensity regime and, in particular, may be used for production of intense ion beams of multi-MeV to GeV ion energies with the energetic efficiency of tens of per cent, much higher than for conventional laser acceleration schemes.

  8. Diffusion of an annular plasma in positron acceleration

    SciTech Connect

    Chen, Francis F.

    2007-12-15

    Electron acceleration to multi-GeV energies has been demonstrated using plasma wakefields in a tunnel-ionized plasma. However, coherent wakefields for positron acceleration may require hollow plasmas pre-ionized by a laser beam. The lifetime of such a plasma is determined by an unusual diffusion problem in which the diffusion rate varies by an order of magnitude inside the hole. The problem is solved by numerical differentiation without using a particle-in-cell code. The densities assumed in this work match those in existing positron experiments and are low compared with those in electron experiments. Future positron experiments at higher densities will not exhibit the nonlinear diffusion treated here because they will be dominated by recombination and tunneling ionization by the beam.

  9. Electrostatic acceleration of helicon plasma using a cusped magnetic field

    NASA Astrophysics Data System (ADS)

    Harada, S.; Baba, T.; Uchigashima, A.; Yokota, S.; Iwakawa, A.; Sasoh, A.; Yamazaki, T.; Shimizu, H.

    2014-11-01

    The electrostatic acceleration of helicon plasma is investigated using an electrostatic potential exerted between the ring anode at the helicon source exit and an off-axis hollow cathode in the downstream region. In the downstream region, the magnetic field for the helicon source, which is generated by a solenoid coil, is modified using permanent magnets and a yoke, forming an almost magnetic field-free region surrounded by an annular cusp field. Using a retarding potential analyzer, two primary ion energy peaks, where the lower peak corresponds to the space potential and the higher one to the ion beam, are detected in the field-free region. Using argon as the working gas with a helicon power of 1.5 kW and a mass flow rate of 0.21 mg/s, the ion beam energy is on the order of the applied acceleration voltage. In particular, with an acceleration voltage lower than 150 V, the ion beam energy even exceeds the applied acceleration voltage by an amount on the order of the electron thermal energy at the exit of the helicon plasma source. The ion beam energy profile strongly depends on the helicon power and the applied acceleration voltage. Since by this method the whole working gas from the helicon plasma source can, in principle, be accelerated, this device can be applied as a noble electrostatic thruster for space propulsion.

  10. Electrostatic acceleration of helicon plasma using a cusped magnetic field

    SciTech Connect

    Harada, S.; Baba, T.; Uchigashima, A.; Iwakawa, A.; Sasoh, A.; Yokota, S.; Yamazaki, T.; Shimizu, H.

    2014-11-10

    The electrostatic acceleration of helicon plasma is investigated using an electrostatic potential exerted between the ring anode at the helicon source exit and an off-axis hollow cathode in the downstream region. In the downstream region, the magnetic field for the helicon source, which is generated by a solenoid coil, is modified using permanent magnets and a yoke, forming an almost magnetic field-free region surrounded by an annular cusp field. Using a retarding potential analyzer, two primary ion energy peaks, where the lower peak corresponds to the space potential and the higher one to the ion beam, are detected in the field-free region. Using argon as the working gas with a helicon power of 1.5 kW and a mass flow rate of 0.21 mg/s, the ion beam energy is on the order of the applied acceleration voltage. In particular, with an acceleration voltage lower than 150 V, the ion beam energy even exceeds the applied acceleration voltage by an amount on the order of the electron thermal energy at the exit of the helicon plasma source. The ion beam energy profile strongly depends on the helicon power and the applied acceleration voltage. Since by this method the whole working gas from the helicon plasma source can, in principle, be accelerated, this device can be applied as a noble electrostatic thruster for space propulsion.

  11. Holography with standing surface plasma waves

    NASA Technical Reports Server (NTRS)

    Cowan, J. J.

    1974-01-01

    Holography with standing surface plasma waves, where both reference and object beams propagate in opposite directions, has been investigated using an Al reflection grating coated with evaporated As2S3 layers. The image, which appears only for p-polarization and at certain critical angles, is enhanced by the Lippman-Bragg effect and by an increase in intensity over ordinary holography approximately equal to the absolute value of the real part of the dielectric constant for Al. Also considered is holography with object light alone in photoresist layers, using the beam-splitting properties of the grating.

  12. On nonlinear Alfvén-cyclotron waves in multi-species plasma

    NASA Astrophysics Data System (ADS)

    Marsch, Eckart; Verscharen, Daniel

    2011-06-01

    Large-amplitude Alfvén waves are ubiquitous in space plasmas and a main component of magnetohydrodynamic (MHD) turbulence in the heliosphere. As pump waves, they are prone to parametric instability by which they can generate cyclotron and acoustic daughter waves. Here, we revisit a related process within the framework of the multi-fluid equations for a plasma consisting of many species. The nonlinear coupling of the Alfvén wave to acoustic waves is studied, and a set of compressive and coupled-wave equations for the transverse magnetic field and longitudinal electric field is derived for waves propagating along the mean-field direction. It turns out that slightly compressive Alfvén waves exert, through induced gyro-radius and kinetic-energy modulations, an electromotive force on the particles in association with a longitudinal electric field, which has a potential that is given by the gradient of the transverse kinetic energy of the particles gyrating about the mean field. This in turn drives electric fluctuations (sound and ion-acoustic waves) along the mean magnetic field, which can nonlinearly react back on the transverse magnetic field. Mutually coupled Alfvén-cyclotron-acoustic waves are thus excited, a nonlinear process that can drive a cascade of wave energy in the plasma, and may generate compressive microturbulence. These driven electric fluctuations might have consequences for the dissipation of an MHD turbulence and, thus, for the heating and acceleration of particles in the solar wind.

  13. Particle physicist's dreams about PetaelectronVolt laser plasma accelerators

    SciTech Connect

    Vesztergombi, G.

    2012-07-09

    Present day accelerators are working well in the multi TeV energy scale and one is expecting exciting results in the coming years. Conventional technologies, however, can offer only incremental (factor 2 or 3) increase in beam energies which does not follow the usual speed of progress in the frontiers of high energy physics. Laser plasma accelerators theoretically provide unique possibilities to achieve orders of magnitude increases entering the PetaelectronVolt (PeV) energy range. It will be discussed what kind of new perspectives could be opened for the physics at this new energy scale. What type of accelerators would be required?.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  15. Plasma jet accelerator optimization with supple membrane model

    NASA Astrophysics Data System (ADS)

    Galkin, S. A.; Bogatu, I. N.; Kim, J. S.

    2006-10-01

    High density (>=3x10^17cm-3) and high Mach number (M>10) plasma jets have important applications such as plasma rotation, refueling and disruption mitigation in tokamaks. The most deleterious blow-by instability occurs in coaxial plasma accelerators; hence electrode shape optimization is required to accelerate plasmas to ˜200 km/s [1]. A full 3D particle simulation takes a huge computational time. We have developed a membrane model to provide a good starting point and further physical insight for a full 3D optimization. Our model approximates the axisymmetrical plasma by a thin supple conducting membrane with a distributed mass, located between the electrodes, and connects them to model dynamics of the blow-by instability and to conduct the optimization. The supple membrane is allowed to slip along the conductors freely or with some friction as affected by Lorenz force, generated by magnetic field inside the chamber and current on membrane. The total mass and the density distribution represent the initial plasma. The density is redistributed adiabatically during the acceleration. An external electrical circuit with capacitance, inductance and resistivity is a part of the model. The membrane model simulation results will be compared to the 2D fluid MACH2 results and then will be used to guide a full 3D optimization by the LSP code. 1. http://hyperv.com/projects/pic/

  16. Dynamics of a current bridge in a coaxial plasma accelerator

    NASA Astrophysics Data System (ADS)

    Voronin, A. V.; Gusev, V. K.; Kobyakov, S. V.

    2011-07-01

    The pioneering investigation of the behavior of a current bridge in a coaxial accelerator with pulsed delivery of a working gas liberated from titanium hydride by an electrical discharge is reported. A new method to trace the motion of the current bridge using LEDs is suggested. The behavior of the current bridge in accelerators with axial and radial gas injection is studied. The parameters of an accelerator generating a pure plasma jet with a high kinetic energy (such as the size and polarity of electrodes, gas flow direction, and time delay between the delivery of the gas to the accelerator and its ionization) are optimized. The applicability of an electrodynamic model to this type of accelerator is discussed. Good agreement between experimental data and calculation results is obtained.

  17. Antenna excitation of drift wave in a toroidal plasma

    SciTech Connect

    Diallo, A.; Ricci, P.; Fasoli, A.; Furno, I.; Labit, B.; Mueller, S. H.; Podesta, M.; Poli, F. M.; Skiff, F.

    2007-10-15

    In a magnetized toroidal plasma, an antenna tunable in vertical wave number is used to excite density perturbations. Coherent detection is performed by means of Langmuir probes to directly determine both the wave vector and the plasma response induced by the antenna. Comparison between the theoretical density response predicted by the generalized Hasegawa-Wakatani model, and the experimentally determined density response enables us the identification of one peak of the plasma response as a drift wave.

  18. Proposed method for high-speed plasma density measurement in proton-driven plasma wakefield acceleration

    SciTech Connect

    Tarkeshian, R.; Reimann, O.; Muggli, P.

    2012-12-21

    Recently a proton-bunch-driven plasma wakefield acceleration experiment using the CERN-SPS beam was proposed. Different types of plasma cells are under study, especially laser ionization, plasma discharge, and helicon sources. One of the key parameters is the spatial uniformity of the plasma density profile along the cell that has to be within < 1% of the nominal density (6 Multiplication-Sign 10{sup 14} cm{sup -3}). Here a setup based on a photomixing concept is proposed to measure the plasma cut-off frequency and determine the plasma density.

  19. Solid-particle jet formation under shock-wave acceleration.

    PubMed

    Rodriguez, V; Saurel, R; Jourdan, G; Houas, L

    2013-12-01

    When solid particles are impulsively dispersed by a shock wave, they develop a spatial distribution which takes the form of particle jets whose selection mechanism is still unidentified. The aim of the present experimental work is to study particle dispersal with fingering effects in an original quasi-two-dimensional experiment facility in order to accurately extract information. Shock and blast waves are generated in the carrier gas at the center of a granular medium ring initially confined inside a Hele-Shaw cell and impulsively accelerated. With the present experimental setup, the particle jet formation is clearly observed. From fast flow visualizations, we notice, in all instances, that the jets are initially generated inside the particle ring and thereafter expelled outward. This point has not been observed in three-dimensional experiments. We highlight that the number of jets is unsteady and decreases with time. For a fixed configuration, considering the very early times following the initial acceleration, the jet size selection is independent of the particle diameter. Moreover, the influence of the initial overpressure and the material density on the particle jet formation have been studied. It is shown that the wave number of particle jets increases with the overpressure and with the decrease of the material density. The normalized number of jets as a function of the initial ring acceleration shows a power law valid for all studied configurations involving various initial pressure ratios, particle sizes, and particle materials. PMID:24483561

  20. Effects of positron concentration, ion temperature, and plasma {beta} value on linear and nonlinear two-dimensional magnetosonic waves in electron-positron-ion plasmas

    SciTech Connect

    Mushtaq, A.; Shah, H.A.

    2005-01-01

    Magnetosonic waves are intensively studied due to their importance in space plasmas and also in fusion plasmas where they are used in particle acceleration and heating experiments. This work considers magnetosonic waves propagating obliquely at an angle {theta} to an external magnetic field in an electron-positron-ion plasma, using the effective one-fluid magnetohydrodynamic model. Two separate modes (fast and slow) for the waves are discussed in the linear approximation, and the Kadomstev-Petviashvilli soliton equation is derived by using reductive perturbation scheme for these modes in the nonlinear regime. It is observed that for both the modes the angle {theta}, positron concentration, ion temperature, and plasma {beta}-value affect the propagation properties of solitary waves and behave differently from the simple electron-ion plasmas. Likewise, current density, electric field, and magnetic field for these waves are investigated, for their dependence on the above mentioned parameters.

  1. Solitary and shock waves in magnetized electron-positron plasma

    SciTech Connect

    Lu, Ding; Li, Zi-Liang; Abdukerim, Nuriman; Xie, Bai-Song

    2014-02-15

    An Ohm's law for electron-positron (EP) plasma is obtained. In the framework of EP magnetohydrodynamics, we investigate nonrelativistic nonlinear waves' solutions in a magnetized EP plasma. In the collisionless limit, quasistationary propagating solitary wave structures for the magnetic field and the plasma density are obtained. It is found that the wave amplitude increases with the Mach number and the Alfvén speed. However, the dependence on the plasma temperature is just the opposite. Moreover, for a cold EP plasma, the existence range of the solitary waves depends only on the Alfvén speed. For a hot EP plasma, the existence range depends on the Alfvén speed as well as the plasma temperature. In the presence of collision, the electromagnetic fields and the plasma density can appear as oscillatory shock structures because of the dissipation caused by the collisions. As the collision frequency increases, the oscillatory shock structure becomes more and more monotonic.

  2. Cassini Radio and Plasma Wave Observations at Saturn

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Kurth, W. S.; Hospodarsky, G. B.; Persoon, A. M.; Averkamp, T. F.; Ceccni, B.; Lecacheux, A.; Zarka, P.; Canu, P.; Cornilleau-Wehrlin, N.

    2005-01-01

    Results are presented from the Cassini radio and plasma wave instrument during the approach and first few orbits around Saturn. During the approach the intensity modulation of Saturn Kilometric Radiation (SKR) showed that the radio rotation period of Saturn has increased to 10 hr 45 min plus or minus 36 sec, about 6 min longer than measured by Voyager in 1980-81. Also, many intense impulsive radio signals called Saturn Electrostatic Discharges (SEDs) were detected from saturnian lightning, starting as far as 1.08 AU from Saturn, much farther than terrestrial lightning can be detected from Earth. Some of the SED episodes have been linked to cloud systems observed in Saturn s atmosphere by the Cassini imaging system. Within the magnetosphere plasma wave emissions have been used to construct an electron density profile through the inner region of the magnetosphere. With decreasing radial distance the electron density increases gradually to a peak of about 100 per cubic centimeter near the outer edge of the A ring, and then drops precipitously to values as low as .03 per cubic centimeter over the rings. Numerous nearly monochromatic whistler-mode emissions were observed as the spacecraft passed over the rings that are believed to be produced by meteoroid impacts on the rings. Whistlermode emissions, similar to terrestrial auroral hiss were also observed over the rings, indicating that an electrodynamic interaction, similar to auroral particle acceleration, may be occurring in or near the rings. During the Titan flybys Langmuir probe and plasma wave measurements provided observations of the density and temperature in Titan's ionosphere.

  3. Properties of Trapped Electron Bunches in a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, Neil; /SLAC

    2009-10-30

    Plasma-based accelerators use the propagation of a drive bunch through plasma to create large electric fields. Recent plasma wakefield accelerator (PWFA) experiments, carried out at the Stanford Linear Accelerator Center (SLAC), successfully doubled the energy for some of the 42 GeV drive bunch electrons in less than a meter; this feat would have required 3 km in the SLAC linac. This dissertation covers one phenomenon associated with the PWFA, electron trapping. Recently it was shown that PWFAs, operated in the nonlinear bubble regime, can trap electrons that are released by ionization inside the plasma wake and accelerate them to high energies. These trapped electrons occupy and can degrade the accelerating portion of the plasma wake, so it is important to understand their origins and how to remove them. Here, the onset of electron trapping is connected to the drive bunch properties. Additionally, the trapped electron bunches are observed with normalized transverse emittance divided by peak current, {epsilon}{sub N,x}/I{sub t}, below the level of 0.2 {micro}m/kA. A theoretical model of the trapped electron emittance, developed here, indicates that the emittance scales inversely with the square root of the plasma density in the non-linear 'bubble' regime of the PWFA. This model and simulations indicate that the observed values of {epsilon}{sub N,x}/I{sub t} result from multi-GeV trapped electron bunches with emittances of a few {micro}m and multi-kA peak currents. These properties make the trapped electrons a possible particle source for next generation light sources. This dissertation is organized as follows. The first chapter is an overview of the PWFA, which includes a review of the accelerating and focusing fields and a survey of the remaining issues for a plasma-based particle collider. Then, the second chapter examines the physics of electron trapping in the PWFA. The third chapter uses theory and simulations to analyze the properties of the trapped electron

  4. Magnetospheric radio and plasma wave research - 1987-1990

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.

    1991-01-01

    This review covers research performed in the area of magnetospheric plasma waves and wave-particle interactions as well as magnetospheric radio emissions. The report focuses on the near-completion of the discovery phase of radio and plasma wave phenomena in the planetary magnetospheres with the successful completion of the Voyager 2 encounters of Neptune and Uranus. Consideration is given to the advances made in detailed studies and theoretical investigations of radio and plasma wave phenomena in the terrestrial magnetosphere or in magnetospheric plasmas in general.

  5. Magnetohydrodynamic waves in fusion and astrophysical plasmas.

    NASA Astrophysics Data System (ADS)

    Goedbloed, J. P.

    Macroscopic plasma dynamics in both controlled thermonuclear confinement machines and in the atmospheres of X-ray emitting stars is described by the equations of magnetohydrodynamics. This provides a vast area of overlapping research activities which is presently actively pursued. In this lecture the author concentrates on some important differences in the dynamics of the two confined plasma systems related to the very different geometries that are encountered and, thus, the role of the different boundary conditions that have to be posed. As a result, the basic MHD waves in a tokamak are quite different from those found in a solar magnetic flux tube. The result is that, whereas the three well-known MHD waves can be traced stepwise in the curved geometry of a tokamak, their separate existence is eliminated right from the start in a line-tied coronal loop because line-tying in general conflicts with the phase relationships between the vector components of the three velocity fields. The consequences are far-reaching, viz. completely different resonant frequencies and continuous spectra, absence of rational magnetic surfaces, and irrelevance of local marginal stability theory for coronal magnetic loops.

  6. Shock-wave proton acceleration from a hydrogen gas jet

    NASA Astrophysics Data System (ADS)

    Cook, Nathan; Pogorelsky, Igor; Polyanskiy, Mikhail; Babzien, Marcus; Tresca, Olivier; Maharjan, Chakra; Shkolnikov, Peter; Yakimenko, Vitaly

    2013-04-01

    Typical laser acceleration experiments probe the interaction of intense linearly-polarized solid state laser pulses with dense metal targets. This interaction generates strong electric fields via Transverse Normal Sheath Acceleration and can accelerate protons to high peak energies but with a large thermal spectrum. Recently, the advancement of high pressure amplified CO2 laser technology has allowed for the creation of intense (10^16 Wcm^2) pulses at λ˜10 μm. These pulses may interact with reproducible, high rep. rate gas jet targets and still produce plasmas of critical density (nc˜10^19 cm-3), leading to the transference of laser energy via radiation pressure. This acceleration mode has the advantage of producing narrow energy spectra while scaling well with pulse intensity. We observe the interaction of an intense CO2 laser pulse with an overdense hydrogen gas jet. Using two pulse optical probing in conjunction with interferometry, we are able to obtain density profiles of the plasma. Proton energy spectra are obtained using a magnetic spectrometer and scintillating screen.

  7. Electromagnetic Safety of Spacecraft During Active Experiments with the Use of Plasma Accelerators and Ion Injectors

    NASA Astrophysics Data System (ADS)

    Plokhikh, Andrey; Popov, Garri; Shishkin, Gennady; Antropov, Nikolay; Vazhenin, Nikolay; Soganova, Galina

    Works under the development and application of stationary and pulsed plasma accelerators of charged particles conducted at the Moscow Aviation Institute and Research Institute of Applied Mechanics and Electrodynamics during over 40 years, active experiments on board meteorological rockets, artificial Earth satellites and "Mir" orbital station including [1], allowed to obtain data on the influence of pulsed and continuous plasma injection with the given parameters on the drop of energetic particles out of the radiation belts, efficiency of artificial excitation and propagation of electromagnetic waves in ELF and VLF ranges, and evolution of artificial plasma formations in different regions of ionosphere. Variation of the near-spacecraft electromagnetic environment related to the operation of plasma injectors was registered during active experiments along with the global electrodynamic processes. The measured electromagnetic fields are of rather high intensity and occupy frequency spectrum from some Hz to tens of GHz that may be of definite danger for the operation of spacecraft and its onboard systems. Analysis for the known test data is presented in the paper and methods are discussed for the diagnostics and modeling under laboratory conditions of radiative processes proceeding at the operation of plasma accelerators and ion injectors used while making active space experiments. Great attention is paid to the methodological and metrological bases for making radio measurements in vacuum chambers, design concept and hardware configuration of ground special-purpose instrumentation scientific complexes [2]. Basic requirements are formulated for the measurements and analysis of electromagnetic fields originating during the operation of plasma accelerators, including the radiative induced and conductive components inside the spacecraft, as well as the wave emission and excitation outside the spacecraft, in the ionosphere including. Measurement results for the intrinsic

  8. Relativistic nonlinear plasma waves in a magnetic field

    NASA Technical Reports Server (NTRS)

    Kennel, C. F.; Pellat, R.

    1975-01-01

    Five relativistic plane nonlinear waves were investigated: circularly polarized waves and electrostatic plasma oscillations propagating parallel to the magnetic field, relativistic Alfven waves, linearly polarized transverse waves propagating in zero magnetic field, and the relativistic analog of the extraordinary mode propagating at an arbitrary angle to the magnetic field. When the ions are driven relativistic, they behave like electrons, and the assumption of an 'electron-positron' plasma leads to equations which have the form of a one-dimensional potential well. The solutions indicate that a large-amplitude superluminous wave determines the average plasma properties.

  9. Whistler wave-induced ionospheric plasma turbulence: Source mechanisms and remote sensing

    NASA Astrophysics Data System (ADS)

    Pradipta, R.; Rooker, L. A.; Whitehurst, L. N.; Lee, M. C.; Ross, L. M.; Sulzer, M. P.; Gonzalez, S.; Tepley, C.; Aponte, N.; See, B. Z.; Hu, K. P.

    2013-10-01

    We report a series of experiments conducted at Arecibo Observatory in the past, aimed at the investigation of 40.75 kHz whistler wave interactions with ionospheric plasmas and the inner radiation belts at L=1.35. The whistler waves are launched from a Naval transmitter (code-named NAU) operating in Aguadilla, Puerto Rico at the frequency and power of 40.75 kHz and 100 kW, respectively. Arecibo radar, CADI, and optical instruments were used to monitor the background ionospheric conditions and detect the induced ionospheric plasma effects. Four-wave interaction processes produced by whistler waves in the ionosphere can excite lower hybrid waves, which can accelerate ionospheric electrons. Furthermore, whistler waves propagating into the magnetosphere can trigger precipitation of energetic electrons from the radiation belts. Radar and optical measurements can distinguish wave-wave and wave-particle interaction processes occurring at different altitudes. Electron acceleration by different mechanisms can be verified from the radar measurements of plasma lines. To facilitate the coupling of NAU-launched 40.75 kHz whistler waves into the ionosphere, we can rely on naturally occurring spread F irregularities to serve as ionospheric ducts. We can also use HF wave-created ducts/artificial waveguides, as demonstrated in our earlier Arecibo experiments and recent Gakona experiments at HAARP. The newly constructed Arecibo HF heater will be employed in our future experiments, which can extend the study of whistler wave interactions with the ionosphere and the magnetosphere/radiation belts as well as the whistler wave conjugate propagation between Arecibo and Puerto Madryn, Argentina.

  10. Surface wave propagation characteristics in atmospheric pressure plasma column

    NASA Astrophysics Data System (ADS)

    Pencheva, M.; Benova, E.; Zhelyazkov, I.

    2007-04-01

    In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency (ν/ω) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption ν/ω = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary ν/ω. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance.

  11. Beyond injection: Trojan horse underdense photocathode plasma wakefield acceleration

    SciTech Connect

    Hidding, B.; Rosenzweig, J. B.; Xi, Y.; O'Shea, B.; Andonian, G.; Schiller, D.; Barber, S.; Williams, O.; Pretzler, G.; Koenigstein, T.; Kleeschulte, F.; Hogan, M. J.; Litos, M.; Corde, S.; White, W. W.; Muggli, P.; Bruhwiler, D. L.; Lotov, K.

    2012-12-21

    An overview on the underlying principles of the hybrid plasma wakefield acceleration scheme dubbed 'Trojan Horse' acceleration is given. The concept is based on laser-controlled release of electrons directly into a particle-beam-driven plasma blowout, paving the way for controlled, shapeable electron bunches with ultralow emittance and ultrahigh brightness. Combining the virtues of a low-ionization-threshold underdense photocathode with the GV/m-scale electric fields of a practically dephasing-free beam-driven plasma blowout, this constitutes a 4th generation electron acceleration scheme. It is applicable as a beam brightness transformer for electron bunches from LWFA and PWFA systems alike. At FACET, the proof-of-concept experiment 'E-210: Trojan Horse Plasma Wakefield Acceleration' has recently been approved and is in preparation. At the same time, various LWFA facilities are currently considered to host experiments aiming at stabilizing and boosting the electron bunch output quality via a trojan horse afterburner stage. Since normalized emittance and brightness can be improved by many orders of magnitude, the scheme is an ideal candidate for light sources such as free-electron-lasers and those based on Thomson scattering and betatron radiation alike.

  12. Beyond injection: Trojan horse underdense photocathode plasma wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Hidding, B.; Rosenzweig, J. B.; Xi, Y.; O'Shea, B.; Andonian, G.; Schiller, D.; Barber, S.; Williams, O.; Pretzler, G.; Königstein, T.; Kleeschulte, F.; Hogan, M. J.; Litos, M.; Corde, S.; White, W. W.; Muggli, P.; Bruhwiler, D. L.; Lotov, K.

    2012-12-01

    An overview on the underlying principles of the hybrid plasma wakefield acceleration scheme dubbed "Trojan Horse" acceleration is given. The concept is based on laser-controlled release of electrons directly into a particle-beam-driven plasma blowout, paving the way for controlled, shapeable electron bunches with ultralow emittance and ultrahigh brightness. Combining the virtues of a low-ionization-threshold underdense photocathode with the GV/m-scale electric fields of a practically dephasing-free beam-driven plasma blowout, this constitutes a 4th generation electron acceleration scheme. It is applicable as a beam brightness transformer for electron bunches from LWFA and PWFA systems alike. At FACET, the proof-of-concept experiment "E-210: Trojan Horse Plasma Wakefield Acceleration" has recently been approved and is in preparation. At the same time, various LWFA facilities are currently considered to host experiments aiming at stabilizing and boosting the electron bunch output quality via a trojan horse afterburner stage. Since normalized emittance and brightness can be improved by many orders of magnitude, the scheme is an ideal candidate for light sources such as free-electron-lasers and those based on Thomson scattering and betatron radiation alike.

  13. Modeling laser-plasma acceleration in the wakefield frame

    SciTech Connect

    2011-01-01

    A simulation of laser-plasma acceleration in the boosted frame of the wake, moving at near lightspeed. Space has contracted and time has stretched, separating events in time. Relatively few time steps are needed to model them, requiring less computer time.

  14. Flexible magnetic design of the MITICA plasma source and accelerator

    NASA Astrophysics Data System (ADS)

    Chitarin, G.; Marconato, N.; Agostinetti, P.; Serianni, G.; Sonato, P.

    2013-02-01

    MITICA is a negative-Ion-based 1 MeV Neutral Beam Injector. The transverse magnetic field in the plasma source and in the accelerator are crucial for preventing the electrons in the plasma source from entering the accelerator and deflecting the secondary electrons, generated inside the accelerator by stripping reactions with background gas, before they are accelerated at higher energy. The scientific objective of MITICA is essentially the experimental validation of the ITER 1 MeV Neutral Beam injector design and indeed a flexible solution is necessary in order to allow an independent variation of the magnetic field in the plasma source and in the accelerator during the experimental campaign. To this purpose a specific magnetic design has been developed and optimized, essentially based on current-carrying busbars with the possible addition of external coils or magnets. The validated magnetic field configuration will then be replicated in the ITER HNB, using only a current-carrying busbar system. The paper presents the rationale of the various steps of this process and the final design obtained.

  15. Laser guiding at relativistic intensities and wakefield particle acceleration in plasma channels

    SciTech Connect

    Geddes, C.G.R.; Toth, Cs.; van Tilborg, J.; Esarey, E.; Schroeder, C.B.; Bruhwiler, D.; Cary, J.; Leemans, W.P.

    2004-08-01

    Electron beams with hundreds of picoCoulombs of charge in percent energy spread at above 80 MeV, and with few milliradian divergence, have been produced for the first time in a high gradient laser wakefield accelerator by guiding the drive laser pulse. Channels formed by hydrodynamic shock were used to guide acceleration relevant laser intensities of at least 1E18W/cm2 at the guide output over more than 10 Rayleigh lengths at LBNL's l'OASIS facility (10TW, 2E19W/cm2). The pondermotive force of the laser pulse drove an intense plasma wave, producing acceleration gradients on the order of 100 GV/m. Electrons were trapped from the background plasma and accelerated. By extending the acceleration length using the guiding channel, the energy of the electron beam was greatly increased, and bunches of small energy spread and low emittance were formed. Experiments varying gas jet length as well assimilations indicate that the high quality beams were formed when beam loading turned off injection after an initial load, producing an isolated bunch, and when that bunch was subsequently accelerated to the dephasing length at which point it rotated in phase space to produce low energy spread.

  16. Beam head erosion in self-ionized plasma wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Zhou, Miaomiao; Clayton, Chris; Huang, Chengkun; Joshi, Chan; Lu, Wei; Marsh, Ken; Mori, Warren; Katsouleas, Tom; Muggli, Patric; Oz, Erdem; Berry, Melissa; Blumenfeld, Ian; Decker, Franz-Josef; Hogan, Mark; Ischebeck, Rasmus; Iverson, Richard; Kirby, Neil; Siemman, Robert; Walz, Dieter

    2007-11-01

    In the recent plasma wakefield accelerator experiments at SLAC, the energy of the particles in the tail of the 42 GeV electron beam were doubled in less than one meter [1]. Simulations suggest that the acceleration length was limited by a new phenomenon -- beam head erosion in self-ionized plasmas. In vacuum, a particle beam expands transversely in a distance given by beta*. In the blowout regime of a plasma wakefield [2], the majority of the beam is focused by the ion channel, while the beam head slowly spreads since it takes a finite time for the ion channel to form. Beam/plasma parameter scan in a large range using simulations shows that in self-ionized plasmas, the head spreading is exacerbated compared to that in pre-ionized plasmas, causing the ionization front to move backward (erode). A theoretical analysis on the erosion rate dependence on beam/plasma parameters and its implications on future afterburner relevant experiments will be provided. [1] I. Blumenfeld et al., Nature 445, 741(2007) [2] J. B. Rosenzweig et al., Phys. Rev. A 44, R6189 (1991)

  17. Turbulent magnetized plasmas from ionizing shock waves

    NASA Astrophysics Data System (ADS)

    Liang, Zuohua

    Turbulent argon plasmas produced behind hypersonic shock waves (10 less than M less than 60) are studied in the presence of weak magnetic fields at various strengths between 0 and 600 gauss, parallel and antiparallel to the shock tube's axis. The experiment is performed in a cylindrical arc discharge shock tube of 5 cm diameter and 210 cm overall length. Laser induced fluorescence and an electric probe are used as diagnostics of the ion density. Turbulent fluctuations behind the shock front are observed which persist for a time in the order of 10 msec. Using standard turbulent and chaotic analytical procedures, the influence of the magnetic field on the characterizing parameters is determined under circumstances of changing Mach number and pressure. These parameters include spectral index, correlation time scales, turbulent intensity and chaotic dimensionality. The parameters of turbulence obtained from the two diagnostics are quite consistent. Fluctuation power spectra follow a P approx. f(sup -n) behavior with 1.3 less than n less than 2.8; this agrees with theoretical predictions as well as the results of other investigators. An increasing magnetic field increases the characterizing correlation time, the turbulent intensity, and the chaotic dimension but decreases the small correlation time. Therefore the magnetic field decreases the order (increases the dimensionality) in the turbulent plasma, independent of the direction of the field parallel or antiparallel to the direction of the shock wave. A turbulent velocity-field-coupling model is proposed. A dispersion relation shows that, in the presence of an external magnetic field, varieties of new modes in a turbulent plasma are generated. The model predicts an increasing complexity of the turbulent system with increasing strength of the field and is in very good qualitative agreement with our experiment results.

  18. Turbulent magnetized plasmas from ionizing shock waves

    SciTech Connect

    Liang, Zuohua.

    1992-01-01

    Turbulent argon plasmas produced behind hypersonic shock waves (10 less than M less than 60) are studied in the presence of weak magnetic fields at various strengths between 0 and 600 gauss, parallel and antiparallel to the shock tube's axis. The experiment is performed in a cylindrical arc discharge shock tube of 5 cm diameter and 210 cm overall length. Laser induced fluorescence and an electric probe are used as diagnostics of the ion density. Turbulent fluctuations behind the shock front are observed which persist for a time in the order of 10 msec. Using standard turbulent and chaotic analytical procedures, the influence of the magnetic field on the characterizing parameters is determined under circumstances of changing Mach number and pressure. These parameters include spectral index, correlation time scales, turbulent intensity and chaotic dimensionality. The parameters of turbulence obtained from the two diagnostics are quite consistent. Fluctuation power spectra follow a P approx. f(sup -n) behavior with 1.3 less than n less than 2.8; this agrees with theoretical predictions as well as the results of other investigators. An increasing magnetic field increases the characterizing correlation time, the turbulent intensity, and the chaotic dimension but decreases the small correlation time. Therefore the magnetic field decreases the order (increases the dimensionality) in the turbulent plasma, independent of the direction of the field parallel or antiparallel to the direction of the shock wave. A turbulent velocity-field-coupling model is proposed. A dispersion relation shows that, in the presence of an external magnetic field, varieties of new modes in a turbulent plasma are generated. The model predicts an increasing complexity of the turbulent system with increasing strength of the field and is in very good qualitative agreement with our experiment results.

  19. Trans-Relativistic Particle Acceleration in Astrophysical Plasmas

    NASA Astrophysics Data System (ADS)

    Becker, Peter A.; Subramanian, P.

    2014-01-01

    Trans-relativistic particle acceleration due to Fermi interactions between charged particles and MHD waves helps to power the observed high-energy emission in AGN transients and solar flares. The trans-relativistic acceleration process is challenging to treat analytically due to the complicated momentum dependence of the momentum diffusion coefficient. For this reason, most existing analytical treatments of particle acceleration assume that the injected seed particles are already relativistic, and therefore they are not suited to study trans-relativistic acceleration. The lack of an analytical model has forced workers to rely on numerical simulations to obtain particle spectra describing the trans-relativistic case. In this work we present the first analytical solution to the global, trans-relativistic problem describing the acceleration of seed particles due to hard-sphere collisions with MHD waves. The new results include the exact solution for the steady-state Green's function resulting from the continual injection of monoenergetic seed particles with an arbitrary energy. We also introduce an approximate treatment of the trans-relativistic acceleration process based on a hybrid form for the momentum diffusion coefficient, given by the sum of the two asymptotic forms. We refer to this process as "quasi hard-sphere scattering." The main advantage of the hybrid approximation is that it allows the extension of the physical model to include (i) the effects of synchrotron and inverse-Compton losses and (ii) time dependence. The new analytical results can be used to model the trans-relativistic acceleration of particles in AGN and solar environments, and can also be used to compute the spectra of the associated synchrotron and inverse-Compton emission. Applications of both types are discussed. We highlight (i) relativistic ion acceleration in black hole accretion coronae, and (ii) the production of gyrosynchrotron microwave emission due to relativistic electron

  20. Plasma waves downstream of weak collisionless shocks

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.; Greenstadt, E. W.; Moses, S. L.; Smith, E. J.; Tsurutani, B. T.

    1993-01-01

    In September 1983 the International Sun Earth Explorer 3 (ISEE 3) International Cometary Explorer (ICE) spacecraft made a long traversal of the distant dawnside flank region of the Earth's magnetosphere and had many encounters with the low Mach number bow shock. These weak shocks excite plasma wave electric field turbulence with amplitudes comparable to those detected in the much stronger bow shock near the nose region. Downstream of quasi-perpendicular (quasi-parallel) shocks, the E field spectra exhibit a strong peak (plateau) at midfrequencies (1 - 3 kHz); the plateau shape is produced by a low-frequency (100 - 300 Hz) emission which is more intense behind downstream of two quasi-perpendicular shocks show that the low frequency signals are polarized parallel to the magnetic field, whereas the midfrequency emissions are unpolarized or only weakly polarized. A new high frequency (10 - 30 kHz) emission which is above the maximum Doppler shift exhibit a distinct peak at high frequencies; this peak is often blurred by the large amplitude fluctuations of the midfrequency waves. The high-frequency component is strongly polarized along the magnetic field and varies independently of the lower-frequency waves.

  1. RFQ (radio-frequency quadrupole) accelerators for heating thermonuclear plasmas

    SciTech Connect

    Stokes, R.H.; Wangler, T.P.; Crandall, K.R.

    1987-01-01

    The radio-frequency quadrupole (RFQ) accelerator has been developed to generate high-current ion beams for a wide variety of applications. It has also been suggested that this type of accelerator could be used to produce megawatt ion beams to heat thermonuclear reactor plasmas. For a tokamak reactor, an RFQ accelerator can be designed to provide negative deuterium ions that are neutralized before injection through the tokamak magentic field. Also, it may be possible to use singly charged, positive, heavier ions that trasverse the magnetic field with minimal deflection and then become multiply ionized upon striking the tokamak plasma. We present preliminary RFQ beam-dynamics designs for both deuterium and oxygen ions.

  2. An Experimental Study of a Pulsed Electromagnetic Plasma Accelerator

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  3. Relativistic electromagnetic waves in an electron-ion plasma

    NASA Technical Reports Server (NTRS)

    Chian, Abraham C.-L.; Kennel, Charles F.

    1987-01-01

    High power laser beams can drive plasma particles to relativistic energies. An accurate description of strong waves requires the inclusion of ion dynamics in the analysis. The equations governing the propagation of relativistic electromagnetic waves in a cold electron-ion plasma can be reduced to two equations expressing conservation of energy-momentum of the system. The two conservation constants are functions of the plasma stream velocity, the wave velocity, the wave amplitude, and the electron-ion mass ratio. The dynamic parameter, expressing electron-ion momentum conversation in the laboratory frame, can be regarded as an adjustable quantity, a suitable choice of which will yield self-consistent solutions when other plasma parameters were specified. Circularly polarized electromagnetic waves and electrostatic plasma waves are used as illustrations.

  4. Kr II laser-induced fluorescence for measuring plasma acceleration.

    PubMed

    Hargus, W A; Azarnia, G M; Nakles, M R

    2012-10-01

    We present the application of laser-induced fluorescence of singly ionized krypton as a diagnostic technique for quantifying the electrostatic acceleration within the discharge of a laboratory cross-field plasma accelerator also known as a Hall effect thruster, which has heritage as spacecraft propulsion. The 728.98 nm Kr II transition from the metastable 5d(4)D(7/2) to the 5p(4)P(5/2)(∘) state was used for the measurement of laser-induced fluorescence within the plasma discharge. From these measurements, it is possible to measure velocity as krypton ions are accelerated from near rest to approximately 21 km/s (190 eV). Ion temperature and the ion velocity distributions may also be extracted from the fluorescence data since available hyperfine splitting data allow for the Kr II 5d(4)D(7/2)-5p(4)P(5/2)(∘) transition lineshape to be modeled. From the analysis, the fluorescence lineshape appears to be a reasonable estimate for the relatively broad ion velocity distributions. However, due to an apparent overlap of the ion creation and acceleration regions within the discharge, the distributed velocity distributions increase ion temperature determination uncertainty significantly. Using the most probable ion velocity as a representative, or characteristic, measure of the ion acceleration, overall propellant energy deposition, and effective electric fields may be calculated. With this diagnostic technique, it is possible to nonintrusively characterize the ion acceleration both within the discharge and in the plume. PMID:23126755

  5. Solitary waves in asymmetric electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Lu, Ding; Li, Zi-Liang; Xie, Bai-Song

    2015-10-01

    > By solving the coupled equations of the electromagnetic field and electrostatic potential, we investigate solitary waves in an asymmetric electron-positron plasma and/or electron-positron-ion plasmas with delicate features. It is found that the solutions of the coupled equations can capture multipeak structures of solitary waves in the case of cold plasma, which are left out by using the long-wavelength approximation. By considering the effect of ion motion with respect to non-relativistic and ultra-relativistic temperature plasmas, we find that the ions' mobility can lead to larger-amplitude solitary waves; especially, this becomes more obvious for a high-temperature plasma. The effects of asymmetric temperature between electrons and positrons and the ion fraction on the solitary waves are also studied and presented. It is shown that the amplitudes of solitary waves decrease with positron temperature in asymmetric temperature electron-positron plasmas and decrease also with ion concentration.

  6. Plasma Wakefield Acceleration Simulations with Multiple Electron Bunches

    NASA Astrophysics Data System (ADS)

    Kallos, Efthymios; Muggli, Patric; Yakimenko, Vitaly; Kusche, Karl; Park, Jangho; Babzien, Marcus; Lichtl, Adam

    2008-11-01

    In the multibunch plasma wakefield accelerator, a train of electron bunches is utilized to excite a high gradient wakefield in a plasma which can be sampled by a trailing short witness bunch. We show that for five drive bunches with 150 pC total charge which can be generated in the Accelerator Test Facility of the Brookhaven National Lab, a wakefield of 140 MV/m can be generated if the plasma density is matched to the bunch train period. In addition, the possibility of ramping the charge per bunch in order to achieve high transformer ratios (>5) is examined, a scenario that is of great interest for a future afterburner collider. The work was supported by the US Department of Energy.

  7. Primary simulation and experimental results of a coaxial plasma accelerator

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Huang, J.; Han, J.; Zhang, Z.; Quan, R.; Wang, L.; Yang, X.; Feng, C.

    A coaxial plasma accelerator with a compressing coil is developed to simulate the impacting and erosion effect of space debris on exposed materials of spacecrafts During its adjustment operation some measurements are conducted including discharging current by Rogowski coil average plasma speed in the coaxial gun by magnetic coils and ejected particle speed by piezoelectric sensor etc In concert with the experiment a primary physical model is constructed in which only the coaxial gun is taken into account with the compressor coil not considered for its unimportant contribution to the plasma ejection speed The calculation results by the model agree well with the diagnostic results considering some assumptions for simplification Based on the simulation result some important suggestions for optimum design and adjustment of the accelerator are obtained for its later operation

  8. Acceleration of electrons in strong beam-plasma interactions

    NASA Technical Reports Server (NTRS)

    Wilhelm, K.; Bernstein, W.; Kellogg, P. J.; Whalen, B. A.

    1984-01-01

    The effects of strong beam-plasma interactions on the electron population of the upper atmosphere have been investigated in an electron acceleration experiment performed with a sounding rocket. The rocket carried the Several Complex Experiments (SCEX) payload which included an electron accelerator, three disposable 'throwaway' detectors (TADs), and a stepped electron energy analyzer. The payload was launched in an auroral arc over the rocket at altitudes of 157 and 178 km, respectively. The performance characteristics of the instruments are discussed in detail. The data are combined with the results of laboratory measurements and show that electrons with energies of at least two and probably four times the injection energy of 2 keV were observed during strong beam-plasma interaction events. The interaction events occurred at pitch angles of 54 and 126 degrees. On the basis of the data it is proposed that the superenergization of the electrons is correlated with the length of the beam-plasma interaction region.

  9. Langmuir wave decay in turbulent inhomogeneous solar wind plasmas

    NASA Astrophysics Data System (ADS)

    Krafft, C.; Volokitin, A.

    2016-03-01

    Langmuir wave decay in solar wind plasmas typical of type III bursts' source regions near 1 AU have been reported by several spacecraft observations. In such plasmas, due to the presence of random density fluctuations, wave decay occurs usually simultaneously and compete with other coupling effects between the fields and the density irregularities, as reflection, scattering and/or refraction processes. Numerical simulations show that resonant three-wave coupling processes including several cascades of Langmuir wave decay can occur in such plasmas, leading to wave energy transfer to smaller wavenumbers k, as shown in the frame of weak turbulence theory. However, in such conditions, and contrary to what occurs in homogeneous plasmas, the decay process is localized in space at a given time. Moreover, wave-wave coupling plays a significant role in the modulation of the Langmuir waveforms, in agreement with recent space observations.

  10. Lower Hybrid Oscillations in Multicomponent Space Plasmas Subjected to Ion Cyclotron Waves

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Krivorutsky, E. N.; Moore, T. E.; Liemohn, M. W.; Horwitz, J. L.

    1997-01-01

    It is found that in multicomponent plasmas subjected to Alfven or fast magnetosonic waves, such as are observed in regions of the outer plasmasphere and ring current-plasmapause overlap, lower hybrid oscillations are generated. The addition of a minor heavy ion component to a proton-electron plasma significantly lowers the low-frequency electric wave amplitude needed for lower hybrid wave excitation. It is found that the lower hybrid wave energy density level is determined by the nonlinear process of induced scattering by ions and electrons; hydrogen ions in the region of resonant velocities are accelerated; and nonresonant particles are weakly heated due to the induced scattering. For a given example, the light resonant ions have an energy gain factor of 20, leading to the development of a high-energy tail in the H(+) distribution function due to low-frequency waves.

  11. Solitary electrostatic waves are possible in unmagnetized symmetric pair plasmas

    SciTech Connect

    Dubinov, Alexander E.; Dubinova, Irina D.; Gordienko, Victor A.

    2006-08-15

    A possibility of stationary solitary electrostatic waves with large amplitude in symmetric unmagnetized symmetric pair plasmas (e{sup -}e{sup +} plasma, C{sub 60}{sup -}C{sub 60}{sup +} plasma or e{sup -}h{sup +} plasma) is proven. The main idea of the work is a thermodynamic unequilibrium of plasma species which may be created in low-density ideal pair plasmas. Ranges of parameters (Mach number M and a nonequilibrium degree {tau}=T{sub +}/T{sub -}) which lead to the possibility of solitary waves are found.

  12. Studies of laser wakefield structures and electron acceleration in underdense plasmas

    SciTech Connect

    Maksimchuk, A.; Reed, S.; Bulanov, S. S.; Chvykov, V.; Kalintchenko, G.; Matsuoka, T.; McGuffey, C.; Mourou, G.; Naumova, N.; Nees, J.; Rousseau, P.; Yanovsky, V.; Krushelnick, K.; Matlis, N. H.; Kalmykov, S.; Shvets, G.; Downer, M. C.; Vane, C. R.; Beene, J. R.; Stracener, D.

    2008-05-15

    Experiments on electron acceleration and optical diagnostics of laser wakes were performed on the HERCULES facility in a wide range of laser and plasma parameters. Using frequency domain holography we demonstrated single shot visualization of individual plasma waves, produced by 40 TW, 30 fs laser pulses focused to the intensity of 10{sup 19} W/cm{sup 2} onto a supersonic He gas jet with plasma densities n{sub e}<10{sup 19} cm{sup -3}. These holographic 'snapshots' capture the variation in shape of the plasma wave with distance behind the driver, and resolve wave front curvature seen previously only in simulations. High-energy quasimonoenergetic electron beams were generated using plasma density in the range 1.5x10{sup 19}{<=}n{sub e}{<=}3.5x10{sup 19} cm{sup -3}. These experiments demonstrated that the energy, charge, divergence, and pointing stability of the beam can be controlled by changing n{sub e}, and that higher electron energies and more stable beams are produced for lower densities. An optimized quasimonoenergetic beam of over 300 MeV and 10 mrad angular divergence is demonstrated at a plasma density of n{sub e}{approx_equal}1.5x10{sup 19} cm{sup -3}. The resultant relativistic electron beams have been used to perform photo-fission of {sup 238}U with a record high reaction yields of {approx}3x10{sup 5}/J. The results of initial experiments on electron acceleration at 70 TW are discussed.

  13. On the physics of waves in the solar atmosphere: Wave heating and wind acceleration

    NASA Technical Reports Server (NTRS)

    Musielak, Z. E.

    1993-01-01

    This paper presents work performed on the generation and physics of acoustic waves in the solar atmosphere. The investigators have incorporated spatial and temporal turbulent energy spectra in a newly corrected version of the Lighthill-Stein theory of acoustic wave generation in order to calculate the acoustic wave energy fluxes generated in the solar convective zone. The investigators have also revised and improved the treatment of the generation of magnetic flux tube waves, which can carry energy along the tubes far away from the region of their origin, and have calculated the tube energy fluxes for the sun. They also examine the transfer of the wave energy originated in the solar convective zone to the outer atmospheric layers through computation of wave propagation and dissipation in highly nonhomogeneous solar atmosphere. These waves may efficiently heat the solar atmosphere and the heating will be especially significant in the chromospheric network. It is also shown that the role played by Alfven waves in solar wind acceleration and coronal hole heating is dominant. The second part of the project concerned investigation of wave propagation in highly inhomogeneous stellar atmospheres using an approach based on an analytic tool developed by Musielak, Fontenla, and Moore. In addition, a new technique based on Dirac equations has been developed to investigate coupling between different MHD waves propagating in stratified stellar atmospheres.

  14. Vacuum laser acceleration of relativistic electrons using plasma mirror injectors

    NASA Astrophysics Data System (ADS)

    Thévenet, M.; Leblanc, A.; Kahaly, S.; Vincenti, H.; Vernier, A.; Quéré, F.; Faure, J.

    2016-04-01

    Accelerating particles to relativistic energies over very short distances using lasers has been a long-standing goal in physics. Among the various schemes proposed for electrons, vacuum laser acceleration has attracted considerable interest and has been extensively studied theoretically because of its appealing simplicity: electrons interact with an intense laser field in vacuum and can be continuously accelerated, provided they remain at a given phase of the field until they escape the laser beam. But demonstrating this effect experimentally has proved extremely challenging, as it imposes stringent requirements on the conditions of injection of electrons in the laser field. Here, we solve this long-standing experimental problem by using a plasma mirror to inject electrons in an ultraintense laser field, and obtain clear evidence of vacuum laser acceleration. With the advent of petawatt lasers, this scheme could provide a competitive source of very high charge (nC) and ultrashort relativistic electron beams.

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

    SciTech Connect

    Plateau, G. R.; Geddes, C. G. R.; Matlis, N. H.; Mittelberger, D. E.; Nakamura, K.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.; Cormier-Michel, E.

    2010-11-04

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

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

    NASA Astrophysics Data System (ADS)

    Plateau, G. R.; Geddes, C. G. R.; Matlis, N. H.; Cormier-Michel, E.; Mittelberger, D. E.; Nakamura, K.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2010-11-01

    Decoupling injection from acceleration is a key challenge to achieve compact, reliable, tunable laser-plasma accelerators (LPA) [1, 2]. In colliding pulse injection the beat between multiple laser pulses can be used to control energy, energy spread, and emittance of the electron beam by injecting electrons in momentum and phase into the accelerating phase of the wake trailing the driver laser pulse [3, 4, 5, 6, 7]. At LBNL, using automated control of spatiotemporal overlap of laser pulses, two-pulse experiments showed stable operation and reproducibility over hours of operation. Arrival time of the colliding beam was scanned, and the measured timing window and density of optimal operation agree with simulations [8]. The accelerator length was mapped by scanning the collision point.

  17. Neutrino-driven wakefield plasma accelerator

    NASA Astrophysics Data System (ADS)

    Rios, L. A.; Serbeto, A.

    2003-08-01

    Processos envolvendo neutrinos são importantes em uma grande variedade de fenômenos astrofísicos, como as explosões de supernovas. Estes objetos, assim como os pulsares e as galáxias starburst, têm sido propostos como aceleradores cósmicos de partículas de altas energias. Neste trabalho, um modelo clássico de fluidos é utilizado para estudar a interação não-linear entre um feixe de neutrinos e um plasma não-colisional relativístico de pósitrons e elétrons na presença de um campo magnético. Durante a interação, uma onda híbrida superior de grande amplitude é excitada. Para parâmetros típicos de supernovas, verificamos que partículas carregadas "capturadas" por essa onda podem ser aceleradas a altas energias. Este resultado pode ser importante no estudo de mecanismos aceleradores de partículas em ambientes astrofísicos.

  18. Progress In Plasma Accelerator Development for Dynamic Formation of Plasma Liners

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    An experimental plasma accelerator for magnetic target fusion (MTF) applications under development at the NASA Marshall Space Flight Center is described. The accelerator is a coaxial pulsed plasma thruster (Figure 1). It has been tested experimentally and plasma jet velocities of approx.50 km/sec have been obtained. The plasma jet has been photographed with 10-ns exposure times to reveal a stable and repeatable plasma structure (Figure 2). Data for velocity profile information has been obtained using light pipes and magnetic probes embedded in the gun walls to record the plasma and current transit respectively at various barrel locations. Preliminary spatially resolved spectral data and magnetic field probe data are also presented. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter is being characterized and future work for second generation "ultra-low jitter" gun development is being identified.

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

    NASA Technical Reports Server (NTRS)

    Roberts, D. Aaron

    2008-01-01

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

  20. DEVELOPMENT OF WATER JET PLASMA MIRROR FOR STAGING OF LASER PLASMA ACCELERATORS

    SciTech Connect

    Panasenko, Dmitriy; Gonsalves, Anthony J.; Leemans, Wim; Nakamura, Kei; Shu, Anthony; Toth, Csaba

    2009-05-04

    Staging Laser Plasma Accelerators (LPAs) is necessary in order to reach beam energies of 100 GeV and above. This requires incoupling of additional laser beams into accelerating stages. In order to maintain the high average accelerating gradient of a staged LPA, it is imperative to minimize the distance that is needed for laser incoupling. A plasma mirror is proposed as the final coupling optic reducing the coupling distance from tens of meters, using a conventional optic, to as small as a few cm. Both a planar water jet and a nitrocellulose foil are used as reflecting surfacesand characterized. A maximum reflectivity of 70percent was obtained using both surfaces.