WorldWideScience

Sample records for large underdense plasmas

  1. Intense ion beam neutralization using underdense background plasma

    Energy Technology Data Exchange (ETDEWEB)

    Berdanier, William [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States); Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Roy, Prabir K. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kaganovich, Igor [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

    2015-01-15

    Producing an overdense background plasma for neutralization purposes with a density that is high compared to the beam density is not always experimentally possible. We show that even an underdense background plasma with a small relative density can achieve high neutralization of intense ion beam pulses. Using particle-in-cell simulations, we show that if the total plasma electron charge is not sufficient to neutralize the beam charge, electron emitters are necessary for effective neutralization but are not needed if the plasma volume is so large that the total available charge in the electrons exceeds that of the ion beam. Several regimes of possible underdense/tenuous neutralization plasma densities are investigated with and without electron emitters or dense plasma at periphery regions, including the case of electron emitters without plasma, which does not effectively neutralize the beam. Over 95% neutralization is achieved for even very underdense background plasma with plasma density 1/15th the beam density. We compare results of particle-in-cell simulations with an analytic model of neutralization and find close agreement with the particle-in-cell simulations. Further, we show experimental data from the National Drift Compression experiment-II group that verifies the result that underdense plasma can neutralize intense heavy ion beams effectively.

  2. Nonlinear behavior of stimulated scatter in large underdense plasmas

    International Nuclear Information System (INIS)

    Kruer, W.L.; Estabrook, K.G.

    1979-01-01

    Several nonlinear effects which limit Brillouin and Raman scatter of intense light in large underdense plasmas are examined. After briefly considering ion trapping and harmonic generation, we focus on the self-consistent ion heating which occurs as an integral part of the Brillouin scattering process. In the long-term nonlinear state, the ion wave amplitude is determined by damping on the heated ion tail which self-consistently forms. A simple model of the scatter is presented and compared with particle simulations. A similar model is also applied to Raman scatter and compared with simulations. Our calculations emphasize that modest tails on the electron distribution function can significantly limit instabilities involving electron plasma waves

  3. Ignition of an overheated, underdense, fusioning tokamak plasma

    International Nuclear Information System (INIS)

    Singer, C.E.; Jassby, D.L.; Hovey, J.

    1979-08-01

    Methods of igniting an overheated but underdense D-T plasma core with a cold plasma blanket are investigated using a simple two-zone model with a variety of transport scaling laws, and also using a one-dimensional transport code. The power consumption of neutral-beam injectors required to produce ignition can be reduced significantly if the underdense core plasma is heated to temperatures much higher than the final equilibrium ignition values, followed by fueling from a cold plasma blanket. It is also found that the allowed impurity concentration in the initial hot core can be greater than normally permitted for ignition provided that the blanket is free from impurities

  4. Relativistic harmonic content of nonlinear electromagnetic waves in underdense plasmas

    International Nuclear Information System (INIS)

    Mori, W.B.; Decker, C.D.; Leemans, W.P.

    1993-01-01

    The relativistic harmonic content of large amplitude electromagnetic waves propagating in underdense plasmas is investigated. The steady state harmonic content of nonlinear linearly polarized waves is calculated for both the very underdense (w p /w o ) much-lt 1 and critical density (w p /w o ) ≅ 1 limits. For weak nonlinearities, eE o /mcw o p /w o . Arguments are given for extending these results for arbitrary wave amplitudes. The authors also show that the use of the variable x-ct and the quasi-static approximation leads to errors in both magnitude and sign when calculating the third harmonic. In the absence of damping or density gradients the third harmonic's amplitude is found to oscillate between zero and twice the steady state value. Preliminary PIC simulation results are presented. The simulation results are in basic agreement with the uniform plasma predictions for the third harmonic amplitude. However, the higher harmonics are orders of magnitude larger than expected and the presence of density ramps significantly modifies the results

  5. PIC simulation of electron acceleration in an underdense plasma

    Directory of Open Access Journals (Sweden)

    S Darvish Molla

    2011-06-01

    Full Text Available One of the interesting Laser-Plasma phenomena, when the laser power is high and ultra intense, is the generation of large amplitude plasma waves (Wakefield and electron acceleration. An intense electromagnetic laser pulse can create plasma oscillations through the action of the nonlinear pondermotive force. electrons trapped in the wake can be accelerated to high energies, more than 1 TW. Of the wide variety of methods for generating a regular electric field in plasmas with strong laser radiation, the most attractive one at the present time is the scheme of the Laser Wake Field Accelerator (LWFA. In this method, a strong Langmuir wave is excited in the plasma. In such a wave, electrons are trapped and can acquire relativistic energies, accelerated to high energies. In this paper the PIC simulation of wakefield generation and electron acceleration in an underdense plasma with a short ultra intense laser pulse is discussed. 2D electromagnetic PIC code is written by FORTRAN 90, are developed, and the propagation of different electromagnetic waves in vacuum and plasma is shown. Next, the accuracy of implementation of 2D electromagnetic code is verified, making it relativistic and simulating the generating of wakefield and electron acceleration in an underdense plasma. It is shown that when a symmetric electromagnetic pulse passes through the plasma, the longitudinal field generated in plasma, at the back of the pulse, is weaker than the one due to an asymmetric electromagnetic pulse, and thus the electrons acquire less energy. About the asymmetric pulse, when front part of the pulse has smaller time rise than the back part of the pulse, a stronger wakefield generates, in plasma, at the back of the pulse, and consequently the electrons acquire more energy. In an inverse case, when the rise time of the back part of the pulse is bigger in comparison with that of the back part, a weaker wakefield generates and this leads to the fact that the electrons

  6. Numerical simulation of laser filamentation in underdense plasma

    International Nuclear Information System (INIS)

    Yu Lichun; Chen Zhihua; Tu Qinfen

    2000-01-01

    Developing process of filamentation and effect of characteristic parameters in underdense plasma have been studied using numerical simulation method. Production and development of two-dimensional cylinder filamentation instability were presented clearly. The results indicate incidence laser intensity and plasma background density are important factors affecting convergent intensity. At the same time, it was showed that different laser wavelength or different electron background density could affect filamentation process. The results are consistent with theory and experiments of alien reports. It can provide reference for restraining filamentation

  7. Trojan horse underdense plasma photocathode acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Karger, Oliver [Hamburg Univ. (Germany). Inst. fuer Experimentalphysik; DESY, FLA Arbeitsbereich Beschleunigerphysik, Hamburg (Germany); Koenigstein, Thomas; Pretzler, Georg [Duesseldorf Univ. (Germany). Inst. fuer Laser- und Plasmaphysik; Rosenzweig, James B. [California Univ., Los Angeles, CA (United States). Dept. of Physics and Astronomy; Hidding, Bernhard [Hamburg Univ. (Germany). Inst. fuer Experimentalphysik; DESY, FLA Arbeitsbereich Beschleunigerphysik, Hamburg (Germany); California Univ., Los Angeles, CA (United States). Dept. of Physics and Astronomy

    2013-07-01

    Relativistic electron beams with small emittance and size are needed for advanced applications such as free electron lasers (FEL) and other coherent light sources in the X-ray regime. Present laser plasma acceleration schemes are hardly able to provide electron beams of sufficient quality on a stable level. The concept of underdense plasma photocathode acceleration uses a beam-driven plasma wave in a two component gas mixture consisting a low ionisation threshold medium (LIT) and a high ionisation threshold medium (HIT) and a low-energy laser pulse. Shapeable electron bunches with sub-fs-length and unprecedented normalized emittance down to 10{sup -9} m rad can be produced. Based on this method, laboratory-sized-experimental setups may enable performance much better than today's conventional coherent hard X-ray sources. The presentation discusses the basic concept, shows recent numero-analytical results and the R and D towards experimental realization.

  8. Propagation of intense laser pulses in an underdense plasma

    International Nuclear Information System (INIS)

    Monot, P.; Auguste, T.; Gibbon, P.; Jakober, F.; Mainfray, G.

    1994-01-01

    Experiments carried out with a laser beam focused into a vacuum chamber onto a 3-mm long, pulsed hydrogen jet, at powers close to the critical power required for relativistic self focusing, have shown that an underdense plasma is able to significantly reduce the divergence of an intense laser pulse. The propagation mode is in good agreement with theoretical predictions of relativistic self focusing. 2 figs., 8 refs

  9. GigaGauss solenoidal magnetic field inside bubbles excited in under-dense plasma

    Science.gov (United States)

    Lécz, Zs.; Konoplev, I. V.; Seryi, A.; Andreev, A.

    2016-10-01

    This paper proposes a novel and effective method for generating GigaGauss level, solenoidal quasi-static magnetic fields in under-dense plasma using screw-shaped high intensity laser pulses. This method produces large solenoidal fields that move with the driving laser pulse and are collinear with the accelerated electrons. This is in contrast with already known techniques which rely on interactions with over-dense or solid targets and generates radial or toroidal magnetic field localized at the stationary target. The solenoidal field is quasi-stationary in the reference frame of the laser pulse and can be used for guiding electron beams. It can also provide synchrotron radiation beam emittance cooling for laser-plasma accelerated electron and positron beams, opening up novel opportunities for designs of the light sources, free electron lasers, and high energy colliders based on laser plasma acceleration.

  10. Spectral modeling of laser-produced underdense titanium plasmas

    Science.gov (United States)

    Chung, Hyun-Kyung; Back, Christina A.; Scott, Howard A.; Constantin, Carmen; Lee, Richard W.

    2004-11-01

    Experiments were performed at the NIKE laser to create underdense low-Z plasmas with a small amount of high-Z dopant in order to study non-LTE population kinetics. An absolutely calibrated spectra in 470-3000 eV was measured in time-resolved and time-averaged fashion from SiO2 aerogel target with 3% Ti dopant. K-shell Ti emission was observed as well as L-shell Ti emission. Time-resolved emission show that lower energy photons peak later than higher energy photons due to plasma cooling. In this work, we compare the measured spectra with non-LTE spectral calculations of titanium emission at relatively low temperatures distributions dominated by L-shell ions will be discussed.

  11. Dielectric constant and laser beam propagation in an underdense collisional plasma: effects of electron temperature

    International Nuclear Information System (INIS)

    Xia Xiongping; Qin Zhen; Xu Bin; Cai Zebin

    2011-01-01

    Dielectric constant and laser beam propagation in an underdense collisional plasma are investigated, using the wave and dielectric function equations, for their dependence on the electron temperature. Simulation results show that, due to the influence of the ponderomotive force there is a nonlinear variation of electron temperature in an underdense collisional plasma, and this leads to a complicated and interesting nonlinear variation of dielectric constant; this nonlinear variation of dielectric constant directly affects the beam propagation and gives rise to laser beam self-focusing in some spatial-temporal regions; in particular, the beam width and the beam intensity present an oscillatory variation in the self-focusing region. The influence of several parameters on the dielectric function and beam self-focusing is discussed.

  12. Stimulated Raman scattering in the presence of filamentation in underdense plasmas

    International Nuclear Information System (INIS)

    Barr, H.C.; Boyd, T.J.M.; Coutts, G.A.

    1986-01-01

    A model of stimulated Raman scattering from underdense plasmas in which the laser intensity profile and plasma density have been corrupted by the filamentation instability is described. The model accounts in a unified way for inhomogeneity in the density, for Landau damping, and for local enhancements in lightwave intensities. In shallow filaments the concentration of the light gives rise to modest increases in growth. On the other hand, for deeper filaments the inhomogeneity and Landau damping dominate to suppress the instability. In addition, backscatter is enhanced relative to sidescatter

  13. Interactions of two co-propagating laser beams in underdense plasmas using a generalized Peaceman-Rachford ADI form

    International Nuclear Information System (INIS)

    Mahdy, A.I.

    2005-12-01

    A generalized Peaceman-Rachford (P-R) ADI form based on the regularized finite difference scheme is employed in order to study the interactions of two co-propagating laser beams in underdense plasmas. A numerical algorithm using the P-R ADI form is constructed for solution of coupled 2D time-dependent non-linear Schroedinger equations for quasineutral plasmas in paraxial approximation. The ability of the form to solve the equations is discussed, and its performance in simulating phenomena associated with the interactions in the presence of pondermotive nonlinearity and relativistic nonlinearity is examined. It is shown that the generalized P-R ADI form can accurately solve the coupled NLS equations. With simulation results, the form is shown to be suitable to simulate the interactions of two co-propagating laser beams with underdense plasma, and it can successively simulate the associated phenomena at varying conditions. (author)

  14. Dynamics of intense laser channel formation in an underdense plasma

    International Nuclear Information System (INIS)

    Davis, J.; Petrov, G.M.; Velikovich, A.L.

    2005-01-01

    Efficient guiding and propagation of multi-keV x-rays in plasmas can be achieved by dynamically modifying the media through plasma channel formation. The dynamics of plasma channel formation is studied in preformed underdense plasma irradiated by a high intensity laser. This is done by a two-dimensional model coupling laser propagation to a relativistic particle-in-cell model. For laser intensity of 10 20 W/cm 2 and a laser beam width of 5 μm the channel formation proceeds on a time scale of 60-70 fs in uniform plasma with density 10 18 cm -3 . The channel closes shortly after the rear of the laser pulse has passed due to Coulomb attraction from the ion core. Electron cavitation occurs only if the laser intensity is above a certain threshold intensity and the laser pulse duration exceeds 100 fs. X-ray generation and propagation is feasible for ultrarelativistic laser pulses with small beam width, less than ∼20 μm, and duration of more than 100 fs

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

    Energy Technology Data Exchange (ETDEWEB)

    Smyth, A. G.; Sarri, G.; Doria, D.; Kar, S.; Borghesi, M. [School of Mathematics and Physics, The Queen' s University of Belfast, University Road, Belfast BT7 1NN (United Kingdom); Vranic, M.; Guillaume, E.; Silva, L. O.; Vieira, J. [GoLP/IPFN, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon (Portugal); Amano, Y.; Habara, H.; Tanaka, K. A. [Graduate School of Engineering Osaka University. Suita, Osaka 5650871 (Japan); Heathcote, R.; Norreys, P. A. [STFC Rutherford Appleton Laboratory, Didcot, Oxon OX1 0Qx (United Kingdom); Hicks, G.; Najmudin, Z.; Nakamura, H. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BZ (United Kingdom)

    2016-06-15

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

  16. Beyond injection: Trojan horse underdense photocathode plasma wakefield acceleration

    Energy Technology Data Exchange (ETDEWEB)

    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. [Institut fuer Laser- und Plasmaphysik, Heinrich-Heine-Universitaet Duesseldorf 40225 Duesseldorf (Germany) and Particle Beam Physics Laboratory, Department for Physics and Astronomy, UCLA (United States); Particle Beam Physics Laboratory, Department for Physics and Astronomy, UCLA (United States); Institut fuer Laser- und Plasmaphysik, Heinrich-Heine-Universitaet Duesseldorf 40225 Duesseldorf (Germany); Stanford Linear Accelerator Center (United States); Max-Planck-Institut fuer Physik, Muenchen (Germany); Tech-X Corporation, Boulder, Colorado (United States) and 1348 Redwood Ave., Boulder, Colorado 80304 (United States); Budker Institute of Nuclear Physics SB RAS, 630090, Novosibirsk (Russian Federation) and Novosibirsk State University, 630090, Novosibirsk (Russian Federation)

    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.

  17. effect of the plasma ion channel on self-focusing of a Gaussian laser pulse in underdense plasma

    Directory of Open Access Journals (Sweden)

    Sh Irani

    2013-09-01

    Full Text Available  We have considered the self-focusing of a Gaussian laser pulse in unmagnetized plasma. High-intensity electromagnetic fields cause the variation of electron density in plasma. These changes in the special conditions cause the acceleration of electrons to the higher energy and velocities. Thus the equation of plasma density evolution was obtained considering the electrons ponderomotive force. Then, an equation for the width of laser pulse with a relativistic mass correction term and the effect of ion channel were derived and the propagation of high-intensity laser pulse in an underdense plasma with weak relativistic approximation was investigated. It is shown that the ratio of ion channel radius to spot size could result in different forms of self focusing for the laser pulse in plasma.

  18. Fluid simulation for two laser beams co-propagating in underdense plasma

    International Nuclear Information System (INIS)

    Mahdy, A.I.

    2004-09-01

    2D simulations code was constructed in order simulate the interactions of two co-propagating laser beams with underdense plasma. Simulations results at different laser intensities and separation-distances between the beams centroids were presented. In the results the effects of the laser intensities on the self-focusing and merging of the propagating beams were shown. In addition, the influence of increasing the separation-distance on the beams stability and trajectories were studied. A comparison with previous simulations at similar conditions was carried out in order to evaluate the numerical technique used to solve the basic equations. (author)

  19. Large amplitude waves and fields in plasmas

    International Nuclear Information System (INIS)

    Angelis, U. de; Naples Univ.

    1990-02-01

    In this review, based mostly on the results of the recent workshop on ''Large Amplitude Waves and Fields in Plasmas'' held at ICTP (Trieste, Italy) in May 1989 during the Spring College on Plasma Physics, I will mostly concentrate on underdense, cold, homogeneous plasmas, discussing some of the alternative (to fusion) uses of laser-plasma interaction. In Part I an outline of some basic non-linear processes is given, together with some recent experimental results. The processes are chosen because of their relevance to the applications or because new interesting developments have been reported at the ICTP workshop (or both). In Part II the excitation mechanisms and uses of large amplitude plasma waves are presented: these include phase-conjugation in plasmas, plasma based accelerators (beat-wave, plasma wake-field and laser wake-field), plasma lenses and plasma wigglers for Free Electron Lasers. (author)

  20. Particle-in-cell simulations of high energy electron production by intense laser pulses in underdense plasmas

    International Nuclear Information System (INIS)

    Susumu, Kato; Eisuke, Miura; Kazuyoshi, Koyama; Mitsumori, Tanimoto; Masahiro, Adachi

    2004-01-01

    The propagation of intense laser pulses and the generation of high energy electrons from underdense plasmas are investigated using two dimensional particle-in-cell simulations. When the ratio of the laser power to the critical power of relativistic self-focusing gets the optimal value, the laser pulse propagates in a steady way and electrons have maximum energies. (author)

  1. Particle-in-cell simulations of high energy electron production by intense laser pulses in underdense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Susumu, Kato; Eisuke, Miura; Kazuyoshi, Koyama [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki (Japan); Mitsumori, Tanimoto [Meisei Univ., Dept. of Electrical Engineering, Hino, Tokyo (Japan); Masahiro, Adachi [Hiroshima Univ., Graduate school of Advanced Science of Matter, Higashi-Hiroshima, Hiroshima (Japan)

    2004-07-01

    The propagation of intense laser pulses and the generation of high energy electrons from underdense plasmas are investigated using two dimensional particle-in-cell simulations. When the ratio of the laser power to the critical power of relativistic self-focusing gets the optimal value, the laser pulse propagates in a steady way and electrons have maximum energies. (author)

  2. The interaction of intense subpicosecond laser pulses with underdense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Coverdale, Christine Ann [Univ. of California, Davis, CA (United States)

    1995-05-11

    Laser-plasma interactions have been of interest for many years not only from a basic physics standpoint, but also for their relevance to numerous applications. Advances in laser technology in recent years have resulted in compact laser systems capable of generating (psec), 1016 W/cm2 laser pulses. These lasers have provided a new regime in which to study laser-plasma interactions, a regime characterized by Lplasma ≥ 2LRayleigh > cτ. The goal of this dissertation is to experimentally characterize the interaction of a short pulse, high intensity laser with an underdense plasma (no ≤ 0.05ncr). Specifically, the parametric instability known as stimulated Raman scatter (SRS) is investigated to determine its behavior when driven by a short, intense laser pulse. Both the forward Raman scatter instability and backscattered Raman instability are studied. The coupled partial differential equations which describe the growth of SRS are reviewed and solved for typical experimental laser and plasma parameters. This solution shows the growth of the waves (electron plasma and scattered light) generated via stimulated Raman scatter. The dispersion relation is also derived and solved for experimentally accessible parameters. The solution of the dispersion relation is used to predict where (in k-space) and at what frequency (in ω-space) the instability will grow. Both the nonrelativistic and relativistic regimes of the instability are considered.

  3. Investigation of nonlinear processes associated with stimulated Brillouin scattering in an underdense and extended plasma

    International Nuclear Information System (INIS)

    Rizvi, S.A.H.

    1983-01-01

    In our experiment, the plasma was performed by means of a Z-pinch. Although a plasma near or above the critical density could have been produced, our experiment was deliberately restricted to underdense plasma as a) our interest was to investigate similar situations as encountered in the large extended coronal region of laser-pellet interaction which may endanger the prospects of laser fusion, b) it is readily accessible to various diagnostic methods, and, c) there is sufficient experimental data and theory availabe for comparison. After a brief introduction of the subject, the theory of laser-induced parametric instabilities, as well as various saturation mechanisms are discussed in the second chapter. The third Chapter contains the experimental details of the complete CO 2 laser system, the Z-pinch, and the laser plasma interaction experiment. Experimental results are reported in the next Chapter and are analyzed in the light of predictions discussed in the second Chapter. A comparison of our results with other experiments is made in Chapter 5, and the discrepancies are explained on the basis of a simple model. The last Chapter sums up the entire work. For a better understanding of the subject, the physics of the laser has been given in Appendix. (orig./HT)

  4. Three-dimensional electromagnetic solitary waves in an underdense plasma in PIC simulations

    International Nuclear Information System (INIS)

    Bulanov, Sergei; Esirkepov, Timur; Nishihara, Katsunobu; Pegoraro, Francesco

    2002-01-01

    A three-dimensional sub-cycle relativistic electromagnetic soliton has been observed for the first time in a 3D Particle-in-Cell simulation of the propagation of an intense short laser pulse in an underdense plasma. The structure of the 3D soliton is identified. It resembles an oscillating electric dipole and has a strong charge separation and toroidal magnetic field component. We call this structure a TM-soliton (transverse magnetic). The 3D TM-soliton resembles a 2D P-soliton in the plane of electric field polarization, and a 2D S-soliton in the perpendicular plane. The core of the soliton is positively charged on average in time, and this results in its Coulomb explosion and in ion heating. Then the soliton evolves into a post-soliton, which is a slowly expanding quasi-neutral cavity in the plasma

  5. The effects of microstructure on propagation of laser-driven radiative heat waves in under-dense high-Z plasma

    Science.gov (United States)

    Colvin, J. D.; Matsukuma, H.; Brown, K. C.; Davis, J. F.; Kemp, G. E.; Koga, K.; Tanaka, N.; Yogo, A.; Zhang, Z.; Nishimura, H.; Fournier, K. B.

    2018-03-01

    This work was motivated by previous findings that the measured laser-driven heat front propagation velocity in under-dense TiO2/SiO2 foams is slower than the simulated one [Pérez et al., Phys. Plasmas 21, 023102 (2014)]. In attempting to test the hypothesis that these differences result from effects of the foam microstructure, we designed and conducted an experiment on the GEKKO laser using an x-ray streak camera to compare the heat front propagation velocity in "equivalent" gas and foam targets, that is, targets that have the same initial density, atomic weight, and average ionization state. We first discuss the design and the results of this comparison experiment. To supplement the x-ray streak camera data, we designed and conducted an experiment on the Trident laser using a new high-resolution, time-integrated, spatially resolved crystal spectrometer to image the Ti K-shell spectrum along the laser-propagation axis in an under-dense TiO2/SiO2 foam cylinder. We discuss the details of the design of this experiment, and present the measured Ti K-shell spectra compared to the spectra simulated with a detailed superconfiguration non-LTE atomic model for Ti incorporated into a 2D radiation hydrodynamic code. We show that there is indeed a microstructure effect on heat front propagation in under-dense foams, and that the measured heat front velocities in the TiO2/SiO2 foams are consistent with the analytical model of Gus'kov et al. [Phys. Plasmas 18, 103114 (2011)].

  6. The effect of high intensity laser propagation instabilities on channel formation in underdense plasmas

    International Nuclear Information System (INIS)

    Najmudin, Z.; Krushelnick, K.; Tatarakis, M.; Clark, E.L.; Danson, C.N.; Malka, V.; Neely, D.; Santala, M.I.K.; Dangor, A.E.

    2003-01-01

    Experiments have been performed using high power laser pulses (up to 50 TW) focused into underdense helium plasmas (n e ≤5x10 19 cm -3 ). Using shadowgraphy, it is observed that the laser pulse can produce irregular density channels, which exhibit features such as long wavelength hosing and 'sausage-like' self-focusing instabilities. This phenomenon is a high intensity effect and the characteristic period of oscillation of these instabilities is typically found to correspond to the time required for ions to move radially out of the region of highest intensity

  7. Measurements of magnetic fields generated in underdense plasmas by intense lasers

    International Nuclear Information System (INIS)

    Najmudin, Z.; Walton, B. R.; Mangles, S. P. D.; Dangor, A. E.; Krushelnick, K.; Fritzler, S.; Malka, V.; Faure, J.; Tatarakis, M.

    2006-01-01

    Measurements have been made of the magnetic field generated by the passage of high intensity short laser pulses through underdense plasmas. For a 30 fs, 1 J, 800 nm linearly-polarised laser pulse, an azimuthal magnetic field is observed at a radial extent of approximately 200 μm. The field is found to exceed 2.8 MG. For a 1 ps, 40 J, 1054 nm circularly-polarised laser pulse, a solenoidal field is observed that can exceed 7 MG. This solenoidal field is absent with linear polarised light, and hence can be considered as an Inverse Faraday effect. Both types of field are found to decay on the picosecond timescale. For both the azimuthal and solenoidal fields produced by such intense lasers, the production of energetic electrons by the interaction is thought to be vital for magnetic field generation

  8. Interaction of ultra-short ultra-intense laser pulses with under-dense plasmas

    International Nuclear Information System (INIS)

    Solodov, A.

    2000-12-01

    Different aspects of interaction of ultra-short ultra-intense laser pulses with underdense plasmas are studied analytically and numerically. These studies can be interesting for laser-driven electron acceleration in plasma, X-ray lasers, high-order harmonic generation, initial confinement fusion with fast ignition. For numerical simulations a fully-relativistic particle code WAKE was used, developed earlier at Ecole Polytechnique. It was modified during the work on the thesis in the part of simulation of ion motion, test electron motion, diagnostics for the field and plasma. The studies in the thesis cover the problems of photon acceleration in the plasma wake of a short intense laser pulse, phase velocity of the plasma wave in the Self-Modulated Laser Wake-Field Accelerator (SM LWFA), relativistic channeling of laser pulses with duration of the order of a plasma period, ion dynamics in the wake of a short intense laser pulse, plasma wave breaking. Simulation of three experiments on the laser pulse propagation in plasma and electron acceleration were performed. Among the main results of the thesis, it was found that reduction of the plasma wave phase velocity in the SM LWFA is crucial for electron acceleration, only if a plasma channel is used for the laser pulse guiding. Self-similar structures describing relativistic guiding of short laser pulses in plasmas were found and relativistic channeling of initially Gaussian laser pulses of a few plasma periods in duration was demonstrated. It was shown that ponderomotive force of a plasma wake excited by a short laser pulse forms a channel in plasma and plasma wave breaking in the channel was analyzed in detail. Effectiveness of electron acceleration by the laser field and plasma wave was compared and frequency shift of probe laser pulses by the plasma waves was found in conditions relevant to the current experiments. (author)

  9. Terahertz Pulse Generation in Underdense Relativistic Plasmas: From Photoionization-Induced Radiation to Coherent Transition Radiation

    Science.gov (United States)

    Déchard, J.; Debayle, A.; Davoine, X.; Gremillet, L.; Bergé, L.

    2018-04-01

    Terahertz to far-infrared emission by two-color, ultrashort optical pulses interacting with underdense helium gases at ultrahigh intensities (>1019 W /cm2 ) is investigated by means of 3D particle-in-cell simulations. The terahertz field is shown to be produced by two mechanisms occurring sequentially, namely, photoionization-induced radiation (PIR) by the two-color pulse, and coherent transition radiation (CTR) by the wakefield-accelerated electrons escaping the plasma. We exhibit laser-plasma parameters for which CTR proves to be the dominant process, providing terahertz bursts with field strength as high as 100 GV /m and energy in excess of 10 mJ. Analytical models are developed for both the PIR and CTR processes, which correctly reproduce the simulation data.

  10. Suprathermal Electron Generation and Channel Formation by an Ultrarelativistic Laser Pulse in an Underdense Preformed Plasma

    International Nuclear Information System (INIS)

    Malka, G.; Gaillard, R.; Miquel, J.L.; Rousseaux, C.; Bonnaud, G.; Busquet, M.; Lours, L.; Fuchs, J.; Pepin, H.; Fuchs, J.; Amiranoff, F.; Baton, S.D.

    1997-01-01

    Relativistic electrons are produced, with energies up to 20MeV, by the interaction of a high-intensity subpicosecond laser pulse (1 μm , 300 fs , 10 19 W/cm 2 ) with an underdense plasma. Two suprathermal electron populations appear with temperatures of 1 and 3MeV. In the same conditions, the laser beam transmission is increased up to 20% 30%. We observe both features along with the evidence of laser pulse channeling. A fluid model predicts a strong self-focusing of the pulse. Acceleration in the enhanced laser field seems the most likely mechanism leading to the second electron population. copyright 1997 The American Physical Society

  11. Hosing, sausaging, filamentation and side-scatter of a high-intensity short-pulse laser in an under-dense plasma

    International Nuclear Information System (INIS)

    Najmudin, Z.; Krushelnick, K.; Clark, E.L.; Salvati, M.; Santala, M.I.K.; Tatarakis, M.; Dangor, A.E.

    2000-01-01

    Previous studies of high-intensity short-pulse laser beams propagating in under-dense plasma have relied on spectrally integrated Thomson scattering images. Though interesting, many significant features of the interaction cannot be diagnosed by this method. We report on shadow-graphy and spectrally resolved Thomson scattering of such an interaction. These images reveal many processes previously predicted but unseen, such as the Raman side-scatter and filamentation instabilities. Also the interaction is shown to clearly demonstrate many propagation instabilities such as 'sausaging' and 'hosing' for the first time. (authors)

  12. Plasma-based accelerator structures

    International Nuclear Information System (INIS)

    Schroeder, Carl B.

    1999-01-01

    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

  13. Gas-filled targets for large scalelength plasma interaction experiments on Nova

    International Nuclear Information System (INIS)

    Powers, L.V.; Berger, R.L.; Munro, D.H.

    1994-11-01

    Stimulated Brillouin backscatter from large scale length gas-filled targets has been measured on Nova. These targets were designed to approximate conditions in indirect drive ignition target designs in underdense plasma electron density (n e ∼10 21 /cm 3 ), temperature (T e >3 keV), and gradient scale lengths (L n ∼ mm, L v >6 mm) as well as calculated gain for stimulated Brillouin scattering (SBS). The targets used in these experiments were gas-filled balloons with polyimide walls (gasbags) and gas-filled hohlraums. Detailed characterization using x-ray imaging and x-ray and optical spectroscopy verifies that the calculated plasma conditions are achieved. Time-resolved SBS backscatter from these targets is <3% for conditions similar to ignition target designs

  14. Dynamics of the spectrum of a self-modulated powerful laser pulse in an underdense plasma

    International Nuclear Information System (INIS)

    Andreev, N.E.; Kirsanov, V.I.; Sakharov, A.S.

    1997-01-01

    The evolution of the spectrum of a powerful laser pulse during its self-modulation in an underdense plasma is studied analytically and numerically. It is shown that, in the early stages of the self-modulation instability, the linear theory gives a qualitatively correct description of the dynamics of the pulse spectrum in most cases. Depending on the parameters of the laser pulse and of the plasma, this spectrum contains either Stocks satellites (downshifted from the fundamental frequency to a value equal to the plasma frequency), or both Stocks and anti-Stocks satellites of the fundamental frequency. When the three-dimensional mechanism for the instability is dominant and the pulse power is close to the critical power for relativistic self-focusing, the numerical calculations show that the intensity of the blue satellite exceeds the intensity of the red one. This specific feature of the spectrum, which does not arise when the instability is one-dimensional, cannot be explained in terms of the linear para-axial theory, and can be used to identify the three-dimensional mechanism for the instability in experiments on the self-modulation of powerful laser pulses. It is shown that the transition to the nonlinear stage of the instability is accompanied by the occurrence of cascades (at frequencies separated from the laser carrier frequency by intervals equal to an integer number of plasma frequencies) in the spectrum of the laser pulse

  15. Plasma lenses for focusing relativistic electron beams

    International Nuclear Information System (INIS)

    Govil, R.; Wheeler, S.; Leemans, W.

    1997-01-01

    The next generation of colliders require tightly focused beams with high luminosity. To focus charged particle beams for such applications, a plasma focusing scheme has been proposed. Plasma lenses can be overdense (plasma density, n p much greater than electron beam density, n b ) or underdense (n p less than 2 n b ). In overdense lenses the space-charge force of the electron beam is canceled by the plasma and the remaining magnetic force causes the electron beam to self-pinch. The focusing gradient is nonlinear, resulting in spherical aberrations. In underdense lenses, the self-forces of the electron beam cancel, allowing the plasma ions to focus the beam. Although for a given beam density, a uniform underdense lens produces smaller focusing gradients than an overdense lens, it produces better beam quality since the focusing is done by plasma ions. The underdense lens can be improved by tapering the density of the plasma for optimal focusing. The underdense lens performance can be enhanced further by producing adiabatic plasma lenses to avoid the Oide limit on spot size due to synchrotron radiation by the electron beam. The plasma lens experiment at the Beam Test Facility (BTF) is designed to study the properties of plasma lenses in both overdense and underdense regimes. In particular, important issues such as electron beam matching, time response of the lens, lens aberrations and shot-to-shot reproducibility are being investigated

  16. Properties of spectra of the reflected and transmitted radiation during propagation of relativistically strong laser pulses in underdense plasmas

    International Nuclear Information System (INIS)

    Bulanov, S.V.; Esirkepov, T.Z.; Naumova, N.M.

    1996-01-01

    Particle-in-cell simulation has been performed to study the spatial-temporal evolution of the pulse propagating in an underdense plasma. The spectra both of the reflected and transmitted radiation are investigated. The spectrum structure of the reflected radiation is due to the backward stimulated Raman scattering meanwhile the transmitted radiation structure is mainly due to the nonlinear self-phase-modulation. The influence of the pulse shape on the transmitted radiation spectrum is revealed. The dependence of the main features of the spectrum and the self-consistent pulse distortion is found. The pulse distortion is accompanied by the relativistic electrons generation. copyright 1996 American Institute of Physics

  17. The splitted laser beam filamentation in interaction of laser and an exponential decay inhomogeneous underdense plasma

    International Nuclear Information System (INIS)

    Xia Xiongping; Yi Lin; Xu Bin; Lu Jianduo

    2011-01-01

    The splitted beam filamentation in interaction of laser and an exponential decay inhomogeneous underdense plasma is investigated. Based on Wentzel-Kramers-Brillouin (WKB) approximation and paraxial/nonparaxial ray theory, simulation results show that the steady beam width and single beam filamentation along the propagation distance in paraxial case is due to the influence of ponderomotive nonlinearity. In nonparaxial case, the influence of the off-axial of α 00 and α 02 (the departure of the beam from the Gaussian nature) and S 02 (the departure from the spherical nature) results in more complicated ponderomotive nonlinearity and changing of the channel density and refractive index, which led to the formation of two/three splitted beam filamentation and the self-distortion of beam width. In addition, influence of several parameters on two/three splitted beam filamentation is discussed.

  18. Observation of large-amplitude ion acoustic wave in microwave-plasma interaction experiments

    International Nuclear Information System (INIS)

    Yugami, Noboru; Nishida, Yasushi

    1997-01-01

    Large amplitude ion acoustic wave, which is not satisfied with a linear dispersion relationship of ion acoustic wave, is observed in microwave-plasma interaction experiments. This ion acoustic wave is excited around critical density layer and begins to propagate to underdense region with a phase velocity one order faster than sound velocity C s , which is predicted by the linear theory, the phase velocity and the wave length of the wave decreases as it propagates. Finally, it converges to C s and strongly dumps. Diagnostic by the Faraday cup indicates that this ion acoustic wave is accompanied with a hot ion beam. (author)

  19. Propagation of an intense laser pulse in an under-dense plasma: channeling and stimulated Raman scattering

    International Nuclear Information System (INIS)

    Friou, A.

    2012-01-01

    This thesis is divided in two parts: i) the laser channeling in hundreds of microns long under-dense plasmas (0.1 nc ≤ n ≤ nc, nc being the critical density) of a laser pulse of intensity 10 18-20 W/cm 2 and duration 1-10 ps; ii) the saturation mechanisms of stimulated Raman back-scattering of a laser pulse of intensity 10 14 to 10 16 W/cm 2 and duration of about 1 ps. A parametric study was performed to study the channeling of a very intense laser pulse, using a 2D PIC (Particle In Cell) code. Various kinds of channels were obtained depending on the laser and plasma parameters, thereby reproducing and enlarging previous studies. Moreover, the channeling velocity was measured and scaling laws were established for homogeneous plasmas. They are then applied to inhomogeneous plasmas, similar to those encountered in inertial confinement fusion (ICF). It is then possible to estimate the energy necessary to channel to the critical density, an important step for the fast ignition scheme of ICF. Raman saturation was studied using numerical simulations, in order to determine if it is due to dephasing or to the growth of sidebands, using different approaches. The first is to study Raman simulations (electromagnetic) performed with kinetic PIC and Vlasov codes. The second, is to study the evolution of a plasma initialized with a distribution function after the adiabatic theory, using a Vlasov code (electrostatic). In this case, we observe the growth of a sideband, with dominant wave number and growth rate in good agreement with kinetic simulations. The saturation of the plasma wave can be caused by both saturation mechanisms. [fr

  20. Underdense radiation sources: Moving towards longer wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Back, C.A.; Kilkenny, J.D. [General Atomics, San Diego, California (United States); Seely, J.F.; Weaver, J.L. [Naval Research Laboratory, Washington, DC (United States); Feldman, U. [Artep Inc., Ellicott City, MD (United States); Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A. [Lawrence Livermore National Laboratory, California (United States); Tillack, M. [U. C. San Diego, La Jolla, CA (United States)

    2006-06-15

    Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO{sub 2} aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

  1. Underdense radiation sources: Moving towards longer wavelengths

    International Nuclear Information System (INIS)

    Back, C.A.; Kilkenny, J.D.; Seely, J.F.; Weaver, J.L.; Feldman, U.; Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A.; Tillack, M.

    2006-01-01

    Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO 2 aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

  2. Interaction of ultra-short ultra-intense laser pulses with under-dense plasmas; Interaction d'impulsions laser ultra-courtes et ultra-intenses avec des plasmas sous denses

    Energy Technology Data Exchange (ETDEWEB)

    Solodov, A

    2000-12-15

    Different aspects of interaction of ultra-short ultra-intense laser pulses with underdense plasmas are studied analytically and numerically. These studies can be interesting for laser-driven electron acceleration in plasma, X-ray lasers, high-order harmonic generation, initial confinement fusion with fast ignition. For numerical simulations a fully-relativistic particle code WAKE was used, developed earlier at Ecole Polytechnique. It was modified during the work on the thesis in the part of simulation of ion motion, test electron motion, diagnostics for the field and plasma. The studies in the thesis cover the problems of photon acceleration in the plasma wake of a short intense laser pulse, phase velocity of the plasma wave in the Self-Modulated Laser Wake-Field Accelerator (SM LWFA), relativistic channeling of laser pulses with duration of the order of a plasma period, ion dynamics in the wake of a short intense laser pulse, plasma wave breaking. Simulation of three experiments on the laser pulse propagation in plasma and electron acceleration were performed. Among the main results of the thesis, it was found that reduction of the plasma wave phase velocity in the SM LWFA is crucial for electron acceleration, only if a plasma channel is used for the laser pulse guiding. Self-similar structures describing relativistic guiding of short laser pulses in plasmas were found and relativistic channeling of initially Gaussian laser pulses of a few plasma periods in duration was demonstrated. It was shown that ponderomotive force of a plasma wake excited by a short laser pulse forms a channel in plasma and plasma wave breaking in the channel was analyzed in detail. Effectiveness of electron acceleration by the laser field and plasma wave was compared and frequency shift of probe laser pulses by the plasma waves was found in conditions relevant to the current experiments. (author)

  3. Electron temperature anisotropy modeling and its effect on anisotropy-magnetic field coupling in an underdense laser heated plasma

    Energy Technology Data Exchange (ETDEWEB)

    Morreeuw, J.P.; Dubroca, B. [CEA Centre d' Etudes Scientifiques et Techniques d' Aquitaine, 33 - Le Barp (France); Sangam, A.; Dubroca, B.; Charrier, P.; Tikhonchuk, V.T. [Bordeaux-1 Univ., CELIA, 33 - Talence (France); Sangam, A.; Dubroca, B.; Charrier, P. [Bordeaux-1 Univ., MAB, 33 - Talence (France)

    2006-06-15

    The laser interaction with an underdense plasma leads to an anisotropic laser heating of electrons. This temperature anisotropy gradient in turn is the source of an early magnetic field, which has an important effect on the plasma evolution, due to the thermal flux reduction. We describe the temperature anisotropy by an evolution equation including the anisotropy-magnetic field coupling and observe a rather efficient magnetic field generation. However at high anisotropy levels, a small-scale instability emerges, leading to a serious problem in numerical calculations. We introduce the kinetics effects, which fix the problem by the anisotropy diffusion through the heat flux tensor. A constant-coefficient Fokker-Planck model in the 2-dimensional geometry allows us to derive an anisotropy diffusion term. The diffusion coefficient is fitted from the kinetic theory of the collisional anisotropic (Weibel) instability growth rate. Such an anisotropy diffusion term wipes out the unphysical instability without any undesirable smoothing. This diffusion along with the viscosity term leads also to a quite good restitution of the Weibel instability growth rate and to the short wavelength cutoff, even in a weakly collisional situation. This allows us to use such a model to predict the emergence of the Weibel instability as well as its saturation. (authors)

  4. Time-resolved x-ray line diagnostics of laser-produced plasmas

    International Nuclear Information System (INIS)

    Kauffman, R.L.; Matthews, D.L.; Kilkenny, J.D.; Lee, R.W.

    1982-01-01

    We have examined the underdense plasma conditions of laser irradiated disks using K x-rays from highly ionized ions. A 900 ps laser pulse of 0.532 μm light is used to irradiate various Z disks which have been doped with low concentrations of tracer materials. The tracers whose Z's range from 13 to 22 are chosen so that their K x-ray spectrum is sensitive to typical underdense plasma temperatures and densities. Spectra are measured using a time-resolved crystal spectrograph recording the time history of the x-ray spectrum. A spatially-resolved, time-integrated crystal spectrograph also monitors the x-ray lines. Large differences in Al spectra are observed when the host plasma is changed from SiO 2 to PbO or In. Spectra will be presented along with preliminary analysis of the data

  5. Experimental, theoretical and computational study of frequency upshift of electromagnetic radiation using plasma techniques. Final technical report, January 14, 1991--January 14, 1995

    International Nuclear Information System (INIS)

    Joshi, C.

    1997-01-01

    The final report for the project is comprised of the PhD thesis of Richard L. Savage, Jr entitled: 'Frequency Upshifting of Electromagnetic Radiation via an Underdense Relativistic Ionization Front.' An underdense, relativistically propagating ionization front has been utilized to upshift the frequency of an impinging electromagnetic wave from 35 GHz to more than 173 GHz in a continuously tunable fashion. The source radiation interacted with the ionization front inside a metallic waveguide. The front, simply a moving boundary between ionized and neutral gas, was created as a short, intense pulse of ionizing laser radiation propagated through the gas-filled waveguide. In 1991, W.B. Mori showed theoretically that large upshifts are possible using underdense ionization fronts (underdense implies that the plasma density is lower than that required to reflect the source radiation), where the source wave is transmitted through the plasma/neutral boundary. The authors have extrapolated Mori's analysis to interactions within a waveguide. This is a new technique for generating high-power, short-pulse, tunable radiation, and has potential applications in areas such as time-resolved microwave spectroscopy, plasma diagnostics, and remote sensing

  6. Plasma focusing and diagnosis of high energy particle beams

    International Nuclear Information System (INIS)

    Chen, Pisin.

    1990-09-01

    Various novel concepts of focusing and diagnosis of high energy charged particle beams, based on the interaction between the relativistic particle beam and the plasma, are reviewed. This includes overdense thin plasma lenses, and (underdense) adiabatic plasma lens, and two beam size monitor concepts. In addition, we introduce another mechanism for measuring flat beams based on the impulse received by heavy ions in an underdense plasma. Theoretical investigations show promise of focusing and diagnosing beams down to sizes where conventional methods are not possible to provide. 21 refs

  7. Time-resolved x-ray line diagnostics of laser-produced plasmas

    International Nuclear Information System (INIS)

    Kauffman, R.L.; Matthews, D.L.; Kilkenny, J.D.; Lee, R.W.

    1982-11-01

    We have examined the underdense plasma conditions of laser irradiated disks using K x-rays from highly ionized ions. A 900 ps laser pulse of 0.532 μm light is used to irradiate various Z disks which have been doped with low concentrations of tracer materials. The tracers, whose Z's range from 13 to 22, are chosen so that their K x-ray spectrum is sensitive to typical underdense plasma temperatures and densities. Spectra are measured using a time-resolved crystal spectrograph recording the time history of the x-ray spectrum. A spatially-resolved, time-integrated crystal spectrograph also monitors the x-ray lines. Large differences in Al spectra are observed when the host plasms is changed from SiO 2 to PbO or In. Spectra will be presented along with preliminary analysis of the data

  8. Brillouin scatter in laser-produced plasmas

    International Nuclear Information System (INIS)

    Phillion, D.W.; Kruer, W.L.; Rupert, V.C.

    1977-01-01

    The absorption of intense laser light is found to be reduced when targets are irradiated by 1.06 μm light with long pulse widths (150-400 psec) and large focal spots (100-250 μm). Estimates of Brillouin scatter which account for the finite heat capacity of the underdense plasma predict this reduction. Spectra of the back reflected light show red shifts indicative of Brillouin scattering

  9. Laser-plasma interaction physics in the context of fusion

    International Nuclear Information System (INIS)

    Labaune, C.; Fuchs, J.; Depierreux, S.; Tikhonchuk, V.T.; Baldis, H.A.; Pesme, D.; Myatt, J.; Huller, S.; Laval, G.; Tikhonchuk, V.T.

    2000-01-01

    Of vital importance for Inertial Confinement Fusion (ICF) are the understanding and control of the nonlinear processes which can occur during the propagation of the laser pulses through the underdense plasma surrounding the fusion capsule. The control of parametric instabilities has been studied experimentally, using LULI six-beam laser facility, and also theoretically and numerically. New results based on the direct observation of plasma waves with Thomson scattering of a short wavelength probe beam have revealed the occurrence of the Langmuir decay instability. This secondary instability may play an important role in the saturation of stimulated Raman scattering. Another mechanism for inducing the growth of the scattering instabilities is the so-called 'plasma-induced incoherence'. Namely, recent theoretical studies have shown that the propagation of laser beams through the underdense plasma can increase their spatial and temporal incoherence. This plasma-induced beam smoothing can reduce the levels of parametric instabilities. One signature of this process is a large increase of the spectral width of the laser light after propagation through the plasma. Comparison of the experimental results with numerical propagation through the plasma. Comparison of the experimental results with numerical simulations shows an excellent agreement between the observed and calculated time-resolved spectra of the transmitted laser light at various laser intensities. (authors)

  10. Intensity limits for propagation of 0.527 μm laser beams through large-scale-length plasmas for inertial confinement fusion

    International Nuclear Information System (INIS)

    Niemann, C.; Divol, L.; Froula, D.H.; Gregori, G.; Jones, O.; Kirkwood, R.K.; MacKinnon, A.J.; Meezan, N.B.; Moody, J.D.; Sorce, C.; Suter, L.J.; Glenzer, S.H.; Bahr, R.; Seka, W.

    2005-01-01

    We have established the intensity limits for propagation of a frequency-doubled (2ω, 527 nm) high intensity interaction beam through an underdense large-scale-length plasma. We observe good beam transmission at laser intensities at or below 2x10 14 W/cm 2 and a strong reduction at intensities up to 10 15 W/cm 2 due to the onset of parametric scattering instabilities. We show that temporal beam smoothing by spectral dispersion allows a factor of 2 higher intensities while keeping the beam spray constant, which establishes frequency-doubled light as an option for ignition and burn in inertial confinement fusion experiments

  11. Heating of underdense plasmas by intense lasers

    International Nuclear Information System (INIS)

    Kruer, W.L.

    1972-08-01

    In this note we show that two intense driving fields with frequency much greater than the electron plasma frequency (ω/sub pe/), but with a frequency separation of nearly ω/sub pe/, will couple electron and ion plasma waves and drive them unstable. 6 refs

  12. Two-dimensional Simulations of Correlation Reflectometry in Fusion Plasmas

    International Nuclear Information System (INIS)

    Valeo, E.J.; Kramer, G.J.; Nazikian, R.

    2001-01-01

    A two-dimensional wave propagation code, developed specifically to simulate correlation reflectometry in large-scale fusion plasmas is described. The code makes use of separate computational methods in the vacuum, underdense and reflection regions of the plasma in order to obtain the high computational efficiency necessary for correlation analysis. Simulations of Tokamak Fusion Test Reactor (TFTR) plasma with internal transport barriers are presented and compared with one-dimensional full-wave simulations. It is shown that the two-dimensional simulations are remarkably similar to the results of the one-dimensional full-wave analysis for a wide range of turbulent correlation lengths. Implications for the interpretation of correlation reflectometer measurements in fusion plasma are discussed

  13. EVIDENCE FOR A ∼300 MEGAPARSEC SCALE UNDER-DENSITY IN THE LOCAL GALAXY DISTRIBUTION

    Energy Technology Data Exchange (ETDEWEB)

    Keenan, R. C. [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Barger, A. J. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Cowie, L. L. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

    2013-09-20

    Galaxy counts and recent measurements of the luminosity density in the near-infrared have indicated the possibility that the local universe may be under-dense on scales of several hundred megaparsecs. The presence of a large-scale under-density in the local universe could introduce significant biases into the interpretation of cosmological observables, and, in particular, into the inferred effects of dark energy on the expansion rate. Here we measure the K-band luminosity density as a function of redshift to test for such a local under-density. For our primary sample in this study, we select galaxies from the UKIDSS Large Area Survey and use spectroscopy from the Sloan Digital Sky Survey (SDSS), the Two-degree Field Galaxy Redshift Survey, the Galaxy And Mass Assembly Survey (GAMA), and other redshift surveys to generate a K-selected catalog of ∼35, 000 galaxies that is ∼95% spectroscopically complete at K{sub AB} < 16.3 (K{sub AB} < 17 in the GAMA fields). To complement this sample at low redshifts, we also analyze a K-selected sample from the 2M++ catalog, which combines Two Micron All Sky Survey (2MASS) photometry with redshifts from the 2MASS redshift survey, the Six-degree Field Galaxy Redshift Survey, and the SDSS. The combination of these samples allows for a detailed measurement of the K-band luminosity density as a function of distance over the redshift range 0.01 < z < 0.2 (radial distances D ∼ 50-800 h{sub 70}{sup -1} Mpc). We find that the overall shape of the z = 0 rest-frame K-band luminosity function (M*-5log (h{sub 70}) = –22.15 ± 0.04 and α = –1.02 ± 0.03) appears to be relatively constant as a function of environment and distance from us. We find a local (z < 0.07, D < 300 h{sub 70}{sup -1} Mpc) luminosity density that is in good agreement with previous studies. Beyond z ∼ 0.07, we detect a rising luminosity density that reaches a value of roughly ∼1.5 times higher than that measured locally at z > 0.1. This suggests that the

  14. Measurements of Electron Temperature and Density Profiles of Plasmas Produced by Nike KrF Laser for Laser Plasma Instability (LPI) Research

    Science.gov (United States)

    Oh, Jaechul; Weaver, J. L.; Obenschain, S. P.; Schmitt, A. J.; Kehne, D. M.; Karasik, M.; Chan, L.-Y.; Serlin, V.; Phillips, L.

    2012-10-01

    ExperimentsfootnotetextJ. Oh, et al, GO5.4, APS DPP (2010).^,footnotetextJ. L. Weaver, et al, GO5.3, APS DPP (2010). using Nike KrF laser observed LPI signatures from CH plasmas at the laser intensities above ˜1x10^15 W/cm^2. Knowing spatial profiles of temperature (Te) and density (ne) in the underdense coronal region (0 Nike LPI experiment, a side-on grid imaging refractometer (GIR)footnotetextR. S. Craxton, et al, Phys. Fluids B 5, 4419 (1993). is being deployed for measuring the underdense plasma profiles. The GIR will resolve Te and ne in space taking a 2D snapshot of probe laser (λ= 263 nm, δt = 10 psec) beamlets (50μm spacing) refracted by the plasma at a selected time during the laser illumination. Time-resolved spectrometers with an absolute-intensity-calibrated photodiode array and a streak camera will simultaneously monitor light emission from the plasma in spectral ranges relevant to Raman (SRS) and two plasmon decay (TDP) instabilities. The experimental study of effects of the plasma profiles on the LPI initiation will be presented.

  15. Three-dimensional analysis of nonlinear plasma oscillation

    International Nuclear Information System (INIS)

    Miano, G.

    1990-01-01

    In an underdense plasma a large-amplitude plasma oscillation may be produced by the beating of two external and colinear electromagnetic waves with a frequency difference approximately equal to the plasma frequency - plasma beat wave (PBW) resonant mechanism. The plasma oscillations are driven by the ponderomotive force arising from the beating of the two imposed electromagnetic waves. In this paper two pump electromagnetic waves with arbitrary transverse profiles have been considered. The plasma is described by using the three dimensinal weakly relativistic fluid equations. The nonlinear plasma oscillation dynamics is studied by using the eulerian description, the averaging and the multiple time scale methods. Unlike the linear theory a strong cross field coupling between longitudinal ans transverse electric field components of the plasma oscillation comes out, resulting in a nonlinear phase change and energy transfer between the two components. Unlike the one-dimensional nonlinear theory, the nonlinear frequency shift is caused by relativistic effects as well as by convective effects and electromagnetic field generated from the three dimensional plasma oscillation. The large amplitude plasma oscillation dynamics produced by a bunched relativistic electron beam with arbitrary transverse profile - plasma wave field (PWF) - or by a high power single frequency short electromagnetic pulse with arbitrary transverse profile - electromagnetic plasma wake field (EPWF) - may be described by means of the present theory. (orig.)

  16. Measurements of Electron Density Profiles of Plasmas Produced by Nike KrF Laser for Laser Plasma Instability (LPI) Research

    Science.gov (United States)

    Oh, Jaechul; Weaver, J. L.; Obenschain, S. P.; Schmitt, A. J.; Kehne, D. M.; Karasik, M.; Chan, L.-Y.; Serlin, V.; Phillips, L.

    2013-10-01

    Knowing spatial profiles of electron density (ne) in the underdense coronal region (n Nike LPI experiment, a side-on grid imaging refractometer (GIR) was deployed for measuring the underdense plasma profiles. Plasmas were produced from flat CH targets illuminated by Nike KrF laser with total energies up to 1 kJ of 0.5 ~ 1 nsec FWHM pulses. The GIR resolved ne up to 3 ×1021 /cm3 in space taking 2D snapshot images of probe laser (λ = 263 nm, Δt = 10 ps) beamlets (50 μm spacing) refracted by the plasma at a selected time during the laser illumination. The individual beamlet transmittances were also measured for Te estimation. Time-resolved spectrometers with an absolute-intensity-calibrated photodiode array and a streak camera simultaneously detected light emission from the plasma in spectral ranges relevant to Raman (SRS) and two plasmon decay instabilities. The measured spatial profiles are compared with simulation results from the FAST3D radiation hydrocode and their effects on the LPI observations are investigated. Work supported by DoE/NNSA and performed at Naval Research Laboratory.

  17. Ion Acceleration by Ultra-intense Laser Pulse Interacting with Double-layer Near-critical Density Plasma

    International Nuclear Information System (INIS)

    Gu, Y. J.; Kong, Q.; Li, X. F.; Yu, Q.; Wang, P. X.; Kawata, S.; Izumiyama, T.; Nagashima, T.; Takano, M.; Barada, D.; Ma, Y. Y.

    2016-01-01

    A collimated ion beam is generated through the interaction between ultra-intense laser pulse and a double layer plasma. The maximum energy is above 1 GeV and the total charge of high energy protons is about several tens of nC/μm. The double layer plasma is combined with an underdense plasma and a thin overdense one. The wakefield traps and accelerates a bunch of electrons to high energy in the first underdense slab. When the well collimated electron beam accelerated by the wakefield penetrates through the second overdense slab, it enhances target normal sheath acceleration (TNSA) and breakout after-burner (BOA) regimes. The mechanism is simulated and analyzed by 2.5 dimensional Particle-in-cell code. Compared with single target TNSA or BOA, both the acceleration gradient and energy transfer efficiency are higher in the double layer regime. (paper)

  18. Amplification of magnetic modes in laser-created plasmas

    International Nuclear Information System (INIS)

    Matte, J.P.; Bendib, A.; Luciani, J.F.

    1987-01-01

    The amplification of magnetic (Weibel) modes in laser-plasma interaction is investigated by use of unperturbed distribution functions given by Fokker-Planck simulations and a dispersion relation valid for all collisionality regimes. In the five cases studied, a strongly growing mode is found in the underdense plasma, where v-bar/sub x/ 2 2 , and the usual slowly growing one in the overdense plasma. The first mode grows convectively outwards by more than 10 4 . The convection velocities are found to be very different from Nernst values

  19. Continuation of the Application of Parallel PIC Simulations to Laser and Electron Transport Through Plasmas Under Conditions Relevant to ICF and SBSS

    International Nuclear Information System (INIS)

    Warren B Mori

    2007-01-01

    In 2006/2007 we continued to study several issues related to underdense laser-plasma interactions. We have been studying the onset and saturation of Raman backscatter for NIF conditions, nonlinear plasma oscillations, and the two-plasmon decay instability

  20. Characterization of a gamma-ray source based on a laser-plasma accelerator with applications to radiography

    International Nuclear Information System (INIS)

    Edwards, R.D.; Sinclair, M.A.; Goldsack, T.J.; Krushelnick, K.; Beg, F.N.; Clark, E.L.; Dangor, A.E.; Najmudin, Z.; Tatarakis, M.; Walton, B.; Zepf, M.; Ledingham, K.W.D.; Spencer, I.; Norreys, P.A.; Clarke, R.J.; Kodama, R.; Toyama, Y.; Tampo, M.

    2002-01-01

    The application of high intensity laser-produced gamma rays is discussed with regard to picosecond resolution deep-penetration radiography. The spectrum and angular distribution of these gamma rays is measured using an array of thermoluminescent detectors for both an underdense (gas) target and an overdense (solid) target. It is found that the use of an underdense target in a laser plasma accelerator configuration produces a much more intense and directional source. The peak dose is also increased significantly. Radiography is demonstrated in these experiments and the source size is also estimated

  1. Temperature dependence of underdense nanostructure formation in tungsten under helium irradiation

    International Nuclear Information System (INIS)

    Valles, G.; Martin-Bragado, I.; Nordlund, K.; Lasa, A.; Björkas, C.; Safi, E.; Perlado, J.M.; Rivera, A.

    2017-01-01

    Recently, tungsten has been found to form a highly underdense nanostructured morphology (“W fuzz”) when bombarded by an intense flux of He ions, but only in the temperature window 900–2000 K. Using object kinetic Monte Carlo simulations (pseudo-3D simulations) parameterized from first principles, we show that this temperature dependence can be understood based on He and point defect clustering, cluster growth, and detrapping reactions. At low temperatures (<900 K), fuzz does not grow because almost all He is trapped in very small He-vacancy clusters. At high temperatures (>2300 K), all He is detrapped from clusters, preventing the formation of the large clusters that lead to fuzz growth in the intermediate temperature range. - Highlights: •OKMC simulation of temperature window for fuzz formation. •Stable He-V clusters prevent fuzz formation at low temperatures. •Dissociation of He-V clusters prevent fuzz formation at high temperatures. •Fuzz formation rate increases with increasing temperature. •An incubation fluence observed in the simulations, similar to experimental observations.

  2. Temperature dependence of underdense nanostructure formation in tungsten under helium irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Valles, G., E-mail: gonzalovallesalberdi@hotmail.com [Instituto de Fusión Nuclear, Universidad Politécnica de Madrid, C/ José Gutiérrez Abascal 2, 28006, Madrid (Spain); Martin-Bragado, I. [UCAM, Universidad Católica de Murcia, Campus de los Jerónimos, Guadalupe, 30107, Murcia (Spain); Nordlund, K. [Department of Physics, University of Helsinki, P.O. Box 43, Helsinki, FI-00014 (Finland); National Research Nuclear University MEPhI, 115409, Moscow (Russian Federation); Lasa, A. [Department of Physics, University of Helsinki, P.O. Box 43, Helsinki, FI-00014 (Finland); Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6169 (United States); Björkas, C.; Safi, E. [Department of Physics, University of Helsinki, P.O. Box 43, Helsinki, FI-00014 (Finland); Perlado, J.M.; Rivera, A. [Instituto de Fusión Nuclear, Universidad Politécnica de Madrid, C/ José Gutiérrez Abascal 2, 28006, Madrid (Spain)

    2017-07-15

    Recently, tungsten has been found to form a highly underdense nanostructured morphology (“W fuzz”) when bombarded by an intense flux of He ions, but only in the temperature window 900–2000 K. Using object kinetic Monte Carlo simulations (pseudo-3D simulations) parameterized from first principles, we show that this temperature dependence can be understood based on He and point defect clustering, cluster growth, and detrapping reactions. At low temperatures (<900 K), fuzz does not grow because almost all He is trapped in very small He-vacancy clusters. At high temperatures (>2300 K), all He is detrapped from clusters, preventing the formation of the large clusters that lead to fuzz growth in the intermediate temperature range. - Highlights: •OKMC simulation of temperature window for fuzz formation. •Stable He-V clusters prevent fuzz formation at low temperatures. •Dissociation of He-V clusters prevent fuzz formation at high temperatures. •Fuzz formation rate increases with increasing temperature. •An incubation fluence observed in the simulations, similar to experimental observations.

  3. Study of short wavelength turbulence in dense plasmas. Final technical report, September 8, 1981-August 7, 1983

    International Nuclear Information System (INIS)

    Chen, F.F.; Joshi, C.

    1983-10-01

    The work includes studies of four topics: (1) Thomson scattering from short wavelength density fluctuations from laser excited plasmas from solid targets; (2) studies of SBS driven ion acoustic waves and it's harmonics in underdense plasmas; (3) studies of optical mixing excitation of electron plasma waves (high frequency density fluctuations) in theta pinch plasma; and (4) computational studies of high frequency wave excitation by intense laser beams in plasmas

  4. Electron Parametric Instabilities Driven by Relativistically Intense Laser Light in Plasma

    Science.gov (United States)

    Barr, H. C.; Mason, P.; Parr, D. M.

    1999-08-01

    A unified treatment of electron parametric instabilities driven by ultraintense laser light in plasma is described. It is valid for any intensity, polarization, plasma density, and scattering geometry. The method is applied to linearly polarized light in both underdense plasma and overdense plasma accessible by self-induced transparency. New options arise which are hybrids of stimulated Raman scattering, the two plasmon decay, the relativistic modulational and filamentation instabilities, and stimulated harmonic generation. There is vigorous growth over a wide range of wave numbers and harmonics.

  5. Plasma production for the 50 MeV plasma lens experiment at LBL

    International Nuclear Information System (INIS)

    Leemans, W.; van der Geer, B.; de Loos, M.; Conde, M.; Govil, R.; Chattopadhyay, S.

    1994-06-01

    The Center for Beam Physics at LBL has constructed a Beam Test Facility (BTF) housing a 50 MeV electron beam transport line, which uses the linac injector from the Advanced Light Source, and a terawatt Ti:Al 2 O 3 laser system. The linac operates at 50 MeV and generates 15 ps long electron bunches containing a charge of up to 2 nC. The measured unnormalized beam emittance is 0.33 mm-mrad. These parameters allow for a comprehensive study of focusing of relativistic electron beams with plasma columns, in both the overdense and underdense regime (adiabatic and tapered lenses). A study of adiabatic and/or tapered lenses requires careful control of plasma density and scale lengths of the plasma. We present experimental results on the production of plasmas through resonant two-photon ionization, with parameters relevant to an upcoming plasma lens experiment

  6. Positron Source from Betatron X-rays Emitted in a Plasma Wiggler

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-04-21

    In the E-167 plasma wakefield accelerator (PWFA) experiments in the Final Focus Test Beam (FFTB) at the Stanford Linear Accelerator Center (SLAC), an ultra-short, 28.5 GeV electron beam field ionizes a neutral column of Lithium vapor. In the underdense regime, all plasma electrons are expelled creating an ion column. The beam electrons undergo multiple betatron oscillations leading to a large flux of broadband synchrotron radiation. With a plasma density of 3 x 10{sup 17}cm{sup -3}, the effective focusing gradient is near 9 MT/m with critical photon energies exceeding 50 MeV for on-axis radiation. A positron source is the initial application being explored for these X-rays, as photo-production of positrons eliminates many of the thermal stress and shock wave issues associated with traditional Bremsstrahlung sources. Photo-production of positrons has been well-studied; however, the brightness of plasma X-ray sources provides certain advantages. In this paper, we present results of the simulated radiation spectra for the E-167 experiments, and compute the expected positron yield.

  7. UV laser ionization and electron beam diagnostics for plasma lenses

    International Nuclear Information System (INIS)

    Govil, R.; Volfbeyn, P.; Leemans, W.

    1995-04-01

    A comprehensive study of focusing of relativistic electron beams with overdense and underdense plasma lenses requires careful control of plasma density and scale lengths. Plasma lens experiments are planned at the Beam Test Facility of the LBL Center for Beam Physics, using the 50 MeV electron beam delivered by the linac injector from the Advanced Light Source. Here we present results from an interferometric study of plasmas produced in tri-propylamine vapor with a frequency quadrupled Nd:YAG laser at 266 nm. To study temporal dynamics of plasma lenses we have developed an electron beam diagnostic using optical transition radiation to time resolve beam size and divergence. Electron beam ionization of the plasma has also been investigated

  8. Large-scale numerical simulations of plasmas

    International Nuclear Information System (INIS)

    Hamaguchi, Satoshi

    2004-01-01

    The recent trend of large scales simulations of fusion plasma and processing plasmas is briefly summarized. Many advanced simulation techniques have been developed for fusion plasmas and some of these techniques are now applied to analyses of processing plasmas. (author)

  9. Raman sidescatter instability in a nonuniform plasma

    International Nuclear Information System (INIS)

    Mostrom, M.A.

    1977-01-01

    In the various laser-fusion concepts, an intense electromagnetic wave (the laser) must propagate through an underdense plasma region where it could decay, via the stimulated Raman instability, into a Langmuir plasma wave and a scattered electromagnetic wave. Results are obtained by evaluating the ''Green's function'' response in time and space for the scattered electromagnetic waves assuming they are initiated by a ''delta-function'' source. We consider the case where the temporal growth dominates the plasma wave convection. Then the scattered electromagnetic waves are governed by a single second-order Helmholtz differential equation, in the position variable along the density gradient, with a complex potential having two simple zeros (turning points) and one simple pole

  10. Experimental demonstration of laser imprint reduction using underdense foams

    International Nuclear Information System (INIS)

    Delorme, B.; Casner, A.; Olazabal-Loumé, M.; Nicolaï, Ph.; Breil, J.; Tikhonchuk, V. T.; Michel, D. T.; Seka, W.; Froula, D. H.; Goncharov, V.; Riazuelo, G.; Borisenko, N.; Orekhov, A.; Fujioka, S.; Sunahara, A.; Grech, M.

    2016-01-01

    Reducing the detrimental effect of the Rayleigh-Taylor (RT) instability on the target performance is a critical challenge. In this purpose, the use of targets coated with low density foams is a promising approach to reduce the laser imprint. This article presents results of ablative RT instability growth measurements, performed on the OMEGA laser facility in direct-drive for plastic foils coated with underdense foams. The laser beam smoothing is explained by the parametric instabilities developing in the foam and reducing the laser imprint on the plastic (CH) foil. The initial perturbation pre-imposed by the means of a specific phase plate was shown to be smoothed using different foam characteristics. Numerical simulations of the laser beam smoothing in the foam and of the RT growth are performed with a suite of paraxial electromagnetic and radiation hydrodynamic codes. They confirmed the foam smoothing effect in the experimental conditions.

  11. Experimental demonstration of laser imprint reduction using underdense foams

    Energy Technology Data Exchange (ETDEWEB)

    Delorme, B.; Casner, A. [CEA, DAM, DIF, F-91297 Arpajon (France); CELIA, University of Bordeaux-CNRS-CEA, F-33400 Talence (France); Olazabal-Loumé, M. [CEA, DAM, CESTA, 15 Avenue des Sablières, F-33114 Le Barp (France); CELIA, University of Bordeaux-CNRS-CEA, F-33400 Talence (France); Nicolaï, Ph.; Breil, J.; Tikhonchuk, V. T. [CELIA, University of Bordeaux-CNRS-CEA, F-33400 Talence (France); Michel, D. T.; Seka, W.; Froula, D. H.; Goncharov, V. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Riazuelo, G. [CEA, DAM, DIF, F-91297 Arpajon (France); Borisenko, N.; Orekhov, A. [P. N. Lebedev Physical Institute, RAS, 53 Leninskii Prospect, Moscow 119991 (Russian Federation); Fujioka, S.; Sunahara, A. [Institute of Laser Engineering, Osaka University, Suita, Osaka 565 (Japan); Grech, M. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France)

    2016-04-15

    Reducing the detrimental effect of the Rayleigh-Taylor (RT) instability on the target performance is a critical challenge. In this purpose, the use of targets coated with low density foams is a promising approach to reduce the laser imprint. This article presents results of ablative RT instability growth measurements, performed on the OMEGA laser facility in direct-drive for plastic foils coated with underdense foams. The laser beam smoothing is explained by the parametric instabilities developing in the foam and reducing the laser imprint on the plastic (CH) foil. The initial perturbation pre-imposed by the means of a specific phase plate was shown to be smoothed using different foam characteristics. Numerical simulations of the laser beam smoothing in the foam and of the RT growth are performed with a suite of paraxial electromagnetic and radiation hydrodynamic codes. They confirmed the foam smoothing effect in the experimental conditions.

  12. A new large-scale plasma source with plasma cathode

    International Nuclear Information System (INIS)

    Yamauchi, K.; Hirokawa, K.; Suzuki, H.; Satake, T.

    1996-01-01

    A new large-scale plasma source (200 mm diameter) with a plasma cathode has been investigated. The plasma has a good spatial uniformity, operates at low electron temperature, and is highly ionized under relatively low gas pressure of about 10 -4 Torr. The plasma source consists of a plasma chamber and a plasma cathode generator. The plasma chamber has an anode which is 200 mm in diameter, 150 mm in length, is made of 304 stainless steel, and acts as a plasma expansion cup. A filament-cathode-like plasma ''plasma cathode'' is placed on the central axis of this source. To improve the plasma spatial uniformity in the plasma chamber, a disk-shaped, floating electrode is placed between the plasma chamber and the plasma cathode. The 200 mm diameter plasma is measure by using Langmuir probes. As a result, the discharge voltage is relatively low (30-120 V), the plasma space potential is almost equal to the discharge voltage and can be easily controlled, the electron temperature is several electron volts, the plasma density is about 10 10 cm -3 , and the plasma density is about 10% variance in over a 100 mm diameter. (Author)

  13. Raman sidescatter instability in a nonuniform plasma

    Energy Technology Data Exchange (ETDEWEB)

    Mostrom, M.A.

    1977-07-15

    In the various laser-fusion concepts, an intense electromagnetic wave (the laser) must propagate through an underdense plasma region where it could decay, via the stimulated Raman instability, into a Langmuir plasma wave and a scattered electromagnetic wave. Results are obtained by evaluating the ''Green's function'' response in time and space for the scattered electromagnetic waves assuming they are initiated by a ''delta-function'' source. We consider the case where the temporal growth dominates the plasma wave convection. Then the scattered electromagnetic waves are governed by a single second-order Helmholtz differential equation, in the position variable along the density gradient, with a complex potential having two simple zeros (turning points) and one simple pole.

  14. Anisotropic instability in a laser heated plasma

    International Nuclear Information System (INIS)

    Sangam, A.; Morreeuw, J.-P.; Tikhonchuk, V. T.

    2007-01-01

    The theory of the Weibel instability induced by the inverse Bremsstrahlung absorption of a laser light in an underdense plasma is revisited. It is shown that previous analyses have strongly overestimated the effect by neglecting the stabilizing term related to the interaction of the generated quasistatic magnetic field with the laser-heated electrons. The revised model leads to a reduction of the growth rate by more than a factor of 10, to strong reduction of the domain of unstable modes and to inversion of the direction of the unstable wave vectors in the long wavelength limit. The consequences of this instability on the laser plasma interaction are also discussed

  15. Ultrarelativistic electromagnetic pulses in plasmas

    Science.gov (United States)

    Ashour-Abdalla, M.; Leboeuf, J. N.; Tajima, T.; Dawson, J. M.; Kennel, C. F.

    1981-01-01

    The physical processes of a linearly polarized electromagnetic pulse of highly relativistic amplitude in an underdense plasma accelerating particles to very high energies are studied through computer simulation. An electron-positron plasma is considered first. The maximum momenta achieved scale as the square of the wave amplitude. This acceleration stops when the bulk of the wave energy is converted to particle energy. The pulse leaves behind as a wake a vacuum region whose length scales as the amplitude of the wave. The results can be explained in terms of a snow plow or piston-like action of the radiation on the plasma. When a mass ratio other than unity is chosen and electrostatic effects begin to play a role, first the ion energy increases faster than the electron energy and then the electron energy catches up later, eventually reaching the same value.

  16. Plasma diagnostics on large tokamaks

    International Nuclear Information System (INIS)

    Orlinskij, D.V.; Magyar, G.

    1988-01-01

    The main tasks of the large tokamaks which are under construction (T-15 and Tore Supra) and of those which have already been built (TFTR, JET, JT-60 and DIII-D) together with their design features which are relevant to plasma diagnostics are briefly discussed. The structural features and principal characteristics of the diagnostic systems being developed or already being used on these devices are also examined. The different diagnostic methods are described according to the physical quantities to be measured: electric and magnetic diagnostics, measurements of electron density, electron temperature, the ion components of the plasma, radiation loss measurements, spectroscopy of impurities, edge diagnostics and study of plasma stability. The main parameters of the various diagnostic systems used on the six large tokamaks are summarized in tables. (author). 351 refs, 44 figs, 22 tabs

  17. Calculating the radiation characteristics of accelerated electrons in laser-plasma interactions

    International Nuclear Information System (INIS)

    Li, X. F.; Yu, Q.; Qu, J. F.; Kong, Q.; Gu, Y. J.; Ma, Y. Y.; Kawata, S.

    2016-01-01

    In this paper, we studied the characteristics of radiation emitted by electrons accelerated in a laser–plasma interaction by using the Lienard–Wiechert field. In the interaction of a laser pulse with a underdense plasma, electrons are accelerated by two mechanisms: direct laser acceleration (DLA) and laser wakefield acceleration (LWFA). At the beginning of the process, the DLA electrons emit most of the radiation, and the DLA electrons emit a much higher peak photon energy than the LWFA electrons. As the laser–plasma interaction progresses, the LWFA electrons become the major radiation emitter; however, even at this stage, the contribution from DLA electrons is significant, especially to the peak photon energy.

  18. Electromagnetic surface waves for large-area RF plasma productions between large-area planar electrodes

    International Nuclear Information System (INIS)

    Nonaka, S.

    1992-01-01

    Recently, large-area plasma production has been tested by means of a 13.56 MHz radio-frequency (RF) discharge between a pair of large-area planar electrodes, approximately 0.5 m x 1.4 m, as one of the semiconductor technologies for fabrication of large-area amorphous silicon solar cells in the ''Sunshine Project'' of the Agency of Industrial Science and Technology in Japan. We also confirmed long plasma production between a pair of long electrodes. In this paper, normal electromagnetic (EM) waves propagating in a region between a planar waveguide with one plasma and two dielectric layers are analyzed in order to study the feasibility of large-area plasma productions by EM wave-discharges between a pair of large-area RF electrodes larger than the half-wavelength of RF wave. In conclusion, plasmas higher than an electron plasma frequency will be produced by an odd TMoo surface mode. (author) 4 refs., 3 figs

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

    Energy Technology Data Exchange (ETDEWEB)

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

    International Nuclear Information System (INIS)

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

    2010-01-01

    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.

  1. Production of a large, quiescent, magnetized plasma

    Science.gov (United States)

    Landt, D. L.; Ajmera, R. C.

    1976-01-01

    An experimental device is described which produces a large homogeneous quiescent magnetized plasma. In this device, the plasma is created in an evacuated brass cylinder by ionizing collisions between electrons emitted from a large-diameter electron gun and argon atoms in the chamber. Typical experimentally measured values of the electron temperature and density are presented which were obtained with a glass-insulated planar Langmuir probe. It is noted that the present device facilitates the study of phenomena such as waves and diffusion in magnetized plasmas.

  2. Dynamics of electron bunches at the laser–plasma interaction in the bubble regime

    Energy Technology Data Exchange (ETDEWEB)

    Maslov, V.I., E-mail: vmaslov@kipt.kharkov.ua; Svystun, O.M., E-mail: svistun_elena@mail.ru; Onishchenko, I.N.; Tkachenko, V.I.

    2016-09-01

    The multi-bunches self-injection, observed in laser–plasma accelerators in the bubble regime, affects the energy gain of electrons accelerated by laser wakefield. However, understanding of dynamics of the electron bunches formed at laser–plasma interaction may be challenging. We present here the results of fully relativistic electromagnetic particle-in-cell (PIC) simulation of laser wakefield acceleration driven by a short laser pulse in an underdense plasma. The trapping and acceleration of three witness electron bunches by the bubble-like structures were observed. It has been shown that with time the first two witness bunches turn into drivers and contribute to acceleration of the last witness bunch.

  3. A plasma solenoid driven by an Orbital Angular Momentum laser beam

    OpenAIRE

    Nuter, R.; Korneev, Ph.; Thiele, I.; Tikhonchuk, V.

    2018-01-01

    A tens of Tesla quasi-static axial magnetic field can be produced in the interaction of a short intense laser beam carrying an Orbital Angular Momentum with an underdense plasma. Three-dimensional "Particle In Cell" simulations and analytical model demonstrate that orbital angular momentum is transfered from a tightly focused radially polarized laser beam to electrons without any dissipative effect. A theoretical model describing the balistic interaction of electrons with laser shows that par...

  4. Atmospheric Gaseous Plasma with Large Dimensions

    Science.gov (United States)

    Korenev, Sergey

    2012-10-01

    The forming of atmospheric plasma with large dimensions using electrical discharge typically uses the Dielectric Barrier Discharge (DBD). The study of atmospheric DBD was shown some problems related to homogeneous volume plasma. The volume of this plasma determines by cross section and gas gap between electrode and dielectric. The using of electron beam for volume ionization of air molecules by CW relativistic electron beams was shown the high efficiency of this process [1, 2]. The main advantage of this approach consists in the ionization of gas molecules by electrons in longitudinal direction determines by their kinetic energy. A novel method for forming of atmospheric homogeneous plasma with large volume dimensions using ionization of gas molecules by pulsed non-relativistic electron beams is presented in the paper. The results of computer modeling for delivered doses of electron beams in gases and ionization are discussed. The structure of experimental bench with plasma diagnostics is considered. The preliminary results of forming atmospheric plasma with ionization gas molecules by pulsed nanosecond non-relativistic electron beam are given. The analysis of potential applications for atmospheric volume plasma is presented. Reference: [1] S. Korenev. ``The ionization of air by scanning relativistic high power CW electron beam,'' 2002 IEEE International Conference on Plasma Science. May 2002, Alberta, Canada. [2] S. Korenev, I. Korenev. ``The propagation of high power CW scanning electron beam in air.'' BEAMS 2002: 14th International Conference on High-Power Particle Beams, Albuquerque, New Mexico (USA), June 2002, AIP Conference Proceedings Vol. 650(1), pp. 373-376. December 17.

  5. Intense EM filamentation in relativistic hot plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Qiang-Lin [Department of Physics, Jinggangshan University, Ji' an, Jiangxi 343009 (China); Chen, Zhong-Ping [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, TX 78712 (United States); Mahajan, Swadesh M., E-mail: mahajan@mail.utexas.edu [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, TX 78712 (United States); Department of Physics, School of Natural Sciences, Shiv Nadar University, Uttar Pradesh 201314 (India)

    2017-03-03

    Highlights: • Breaking up of an intense EM pulse into filaments is a spectacular demonstration of the nonlinear wave-plasma interaction. • Filaments are spectacularly sharper, highly extended and longer lived at relativistic temperatures. • EM energy concentration can trigger new nonlinear phenomena with absolute consequences for high energy density matter. - Abstract: Through 2D particle-in-cell (PIC) simulations, we demonstrate that the nature of filamentation of a high intensity electromagnetic (EM) pulse propagating in an underdense plasma, is profoundly affected at relativistically high temperatures. The “relativistic” filaments are sharper, are dramatically extended (along the direction of propagation), and live much longer than their lower temperature counterparts. The thermally boosted electron inertia is invoked to understand this very interesting and powerful phenomenon.

  6. Effects of external magnetic field on harmonics generated in laser interaction with underdense plasma

    International Nuclear Information System (INIS)

    Faghihi-Nik, M.; Ghorbanalilu, M.; Shokri, B.

    2010-01-01

    Complete text of publication follows. Generation of harmonic radiation is an important subject of laser plasma interaction and attracts great attention due to a wide range of applications. It has been seen that intense electromagnetic and quasi-static transverse magnetic fields are generated in laser plasma interaction. An extremely intense magnetic field (up to hundreds of MG) has been observed by experimental measurements in interaction of short laser pulses with plasma. These self-generated or applied magnetic fields affect the propagation of the laser pulses. In most laser interactions with homogeneous plasma, odd harmonics of laser frequency are generated. In this paper, we point out the possibility of even harmonics generation when a linearly polarized laser beam propagates in homogeneous plasma in the presence of a transverse magnetic field. It is shown that applying external field induces a transverse current density oscillating twice of the laser field which leds to generation of second harmonic radiation. This current density is derived using the perturbation method, and the steady state amplitude of the second harmonic obtained by solution of the wave equation. By the same procedure the current density and then the steady state amplitude of higher order harmonics are calculated. The efficiency of harmonic generation (the ratio of harmonic power to incident power) is a drastically function of the strength of external magnetic field. It is found that the efficiency of even harmonics is zero in the absence of magnetic field and increases as the magnetic field is increased. For odd harmonics, applying the external magnetic field enhances the generated harmonics as well. The conversion efficiency also increases with increase in plasma density and intensity of the laser beam.

  7. Coupling of RF antennas to large volume helicon plasma

    Directory of Open Access Journals (Sweden)

    Lei Chang

    2018-04-01

    Full Text Available Large volume helicon plasma sources are of particular interest for large scale semiconductor processing, high power plasma propulsion and recently plasma-material interaction under fusion conditions. This work is devoted to studying the coupling of four typical RF antennas to helicon plasma with infinite length and diameter of 0.5 m, and exploring its frequency dependence in the range of 13.56-70 MHz for coupling optimization. It is found that loop antenna is more efficient than half helix, Boswell and Nagoya III antennas for power absorption; radially parabolic density profile overwhelms Gaussian density profile in terms of antenna coupling for low-density plasma, but the superiority reverses for high-density plasma. Increasing the driving frequency results in power absorption more near plasma edge, but the overall power absorption increases with frequency. Perpendicular stream plots of wave magnetic field, wave electric field and perturbed current are also presented. This work can serve as an important reference for the experimental design of large volume helicon plasma source with high RF power.

  8. Nonlinear dynamics of intense EM pulses in plasma

    International Nuclear Information System (INIS)

    Mahajan, Ranju; Gill, Tarsem Singh; Kaur, Ravinder

    2010-01-01

    The evolution of laser beam in underdense/overdense plasma medium which is key to understanding of several nonlinear processes and underlying physics is governed by nonlinear parabolic equation. The nonlinearity considered here is of relativistic as well as of ponderomotive type. We have set Lagrangian for the problem and reduced Lagrangian problem is solved using appropriate trial function. Equation for the beam width and phase are derived. Further, these equations are used to solve eigenvalue problem for the stability of laser beam evolution and Hurwitz condition is satisfied.

  9. Measurements of electron density and temperature profiles in plasma produced by Nike KrF laser for laser plasma instability research

    Science.gov (United States)

    Oh, Jaechul; Weaver, J. L.; Karasik, M.; Chan, L. Y.

    2015-08-01

    A grid image refractometer (GIR) has been implemented at the Nike krypton fluoride laser facility of the Naval Research Laboratory. This instrument simultaneously measures propagation angles and transmissions of UV probe rays (λ = 263 nm, Δt = 10 ps) refracted through plasma. We report results of the first Nike-GIR measurement on a CH plasma produced by the Nike laser pulse (˜1 ns FWHM) with the intensity of 1.1 × 1015 W/cm2. The measured angles and transmissions were processed to construct spatial profiles of electron density (ne) and temperature (Te) in the underdense coronal region of the plasma. Using an inversion algorithm developed for the strongly refracted rays, the deployed GIR system probed electron densities up to 4 × 1021 cm-3 with the density scale length of 120 μm along the plasma symmetry axis. The resulting ne and Te profiles are verified to be self-consistent with the measured quantities of the refracted probe light.

  10. Supersonic propagation of ionization waves in an underdense, laser-produced plasma

    International Nuclear Information System (INIS)

    Constantin, C.; Back, C.A.; Fournier, K.B.; Gregori, G.; Landen, O.L.; Glenzer, S.H.; Dewald, E.L.; Miller, M.C.

    2005-01-01

    A laser-driven supersonic ionization wave propagating through a millimeter-scale plasma of subcritical density up to 2-3 keV electron temperatures was observed. Propagation velocities initially ten times the sound speed were measured by means of time-resolved x-ray imaging diagnostics. The measured ionization wave trajectory is modeled analytically and by a two-dimensional radiation-hydrodynamics code. The comparison to the modeling suggests that nonlocal heat transport effects may contribute to the attenuation of the heat-wave propagation

  11. Performance of large electron energy filter in large volume plasma device

    International Nuclear Information System (INIS)

    Singh, S. K.; Srivastava, P. K.; Awasthi, L. M.; Mattoo, S. K.; Sanyasi, A. K.; Kaw, P. K.; Singh, R.

    2014-01-01

    This paper describes an in-house designed large Electron Energy Filter (EEF) utilized in the Large Volume Plasma Device (LVPD) [S. K. Mattoo, V. P. Anita, L. M. Awasthi, and G. Ravi, Rev. Sci. Instrum. 72, 3864 (2001)] to secure objectives of (a) removing the presence of remnant primary ionizing energetic electrons and the non-thermal electrons, (b) introducing a radial gradient in plasma electron temperature without greatly affecting the radial profile of plasma density, and (c) providing a control on the scale length of gradient in electron temperature. A set of 19 independent coils of EEF make a variable aspect ratio, rectangular solenoid producing a magnetic field (B x ) of 100 G along its axis and transverse to the ambient axial field (B z ∼ 6.2 G) of LVPD, when all its coils are used. Outside the EEF, magnetic field reduces rapidly to 1 G at a distance of 20 cm from the center of the solenoid on either side of target and source plasma. The EEF divides LVPD plasma into three distinct regions of source, EEF and target plasma. We report that the target plasma (n e ∼ 2 × 10 11  cm −3 and T e ∼ 2 eV) has no detectable energetic electrons and the radial gradients in its electron temperature can be established with scale length between 50 and 600 cm by controlling EEF magnetic field. Our observations reveal that the role of the EEF magnetic field is manifested by the energy dependence of transverse electron transport and enhanced transport caused by the plasma turbulence in the EEF plasma

  12. Propagation of an asymmetric relativistic laser pulse in plasma

    International Nuclear Information System (INIS)

    Garuchava, D.P.; Murusidze, I.G.; Suramlishvili, G.I.; Tsintsadze, N.L.; Tskhakaya, D.D.

    1997-01-01

    The interaction of a relativistically intense asymmetric laser pulse with a plasma has been studied. The asymmetric shape of the pulse implies that the rise time of the leading edge of the pulse is much greater than the fall time of the trailing edge. The numerical simulation of the propagation of such a pulse through an underdense plasma has shown that relativistic self-focusing enhances the effect of ponderomotive self-channeling. The radial ponderomotive force totally expels the electrons from the axis creating a density channel, that is, cavitation occurs. A very short fall time of the trailing edge (τ l ω p <1) causes a rapid increase in the amplitude of a laser driven longitudinal electric field to values of a few GV/cm at the back of the pulse. The numerical simulation also has shown that the channel as well as the large-amplitude longitudinal field can be sustained in the range immediately behind the pulse, thus creating favorable conditions to accelerate a trailing bunch of electrons to extremely high energies. According to our model, the accelerating electric field can reach the value 10 GV/cm. copyright 1997 The American Physical Society

  13. On stimulated scattering of laser light in inertial fusion energy targets

    International Nuclear Information System (INIS)

    Nikolic, Lj; Skoric, M.M.; Ishiguro, S.; Sato, T.

    2002-11-01

    Propagation of a laser light through regions of an underdense plasma is an active research topic in laser fusion. In particular, a large effort has been invested in studies of stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) which can reflect laser energy and produce energetic particles to preheat a fusion energy target. Experiments, theory and simulations agree on a complex interplay between various laser-plasma instabilities. By particle-in-cell simulations of an underdense electron-plasma, we have found, apart from the standard SRS, a strong backscattering near the electron plasma frequency at densities beyond the quarter critical. This novel instability, recognized in recent experiments as stimulated laser scattering on a trapped electron-acoustic mode (SEAS), is absent from a classical theory of laser-parametric instabilities. A parametric excitation of SEAS instability, is explained by a three-wave resonant decay of the incident laser light into a standing backscattered wave and a slow trapped electron acoustic wave (ω p ). Large SEAS pulsations, eventually suppressed by relativistic heating of electrons, are observed in our simulations. This phenomenon seems relevant to future hohlraum target and fast ignition experiments. (author)

  14. Efficient Modeling of Laser-Plasma Accelerators with INF&RNO

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-01

    The numerical modeling code INF&RNO (INtegrated Fluid& paRticle simulatioN cOde, pronounced"inferno") is presented. INF&RNO is an efficient 2D cylindrical code to model the interaction of a short laser pulse with an underdense plasma. The code is based on an envelope model for the laser while either a PIC or a fluid description can be used for the plasma. The effect of the laser pulse on the plasma is modeled with the time-averaged poderomotive force. These and other features allow for a speedup of 2-4 orders of magnitude compared to standard full PIC simulations while still retaining physical fidelity. The code has been benchmarked against analytical solutions and 3D PIC simulations and here a set of validation tests together with a discussion of the performances are presented.

  15. Heating by the Raman instability

    International Nuclear Information System (INIS)

    Estabrook, K.G.; Kruer, W.L.

    1980-01-01

    Computer simulations are presented of the reflection and heating due to stimulated Raman backscatter of intense laser light in large regions of underdense plasma. The heated electron distribution is found to be approximately a Maxwellian of temperature (m/sub e//2)v/sub p/ 2 , where v/sub p/ is the phase velocity of the electron plasma wave. A simple model of the reflection is presented. Raman may cause a pre-heat problem with large laser fusion reactor targets

  16. Ultra High Intensity laser produced fast electron transport in under-dense and over-dense matter

    International Nuclear Information System (INIS)

    Manclossi, Mauro

    2006-01-01

    This thesis is related to inertial fusion research, and particularly concerns the approach to fast ignition, which is based on the use of ultra-intense laser pulses to ignite the thermonuclear fuel. Until now, the feasibility of this scheme has not been proven and depends on many fundamental aspects of the underlying physics, which are not yet fully understood and which are also very far from controls. The main purpose of this thesis is the experimental study of transport processes in the material over-dense (solid) and under-dense (gas jet) of a beam of fast electrons produced by pulse laser at a intensity of some 10 19 Wcm -2 . (author)

  17. Honeycomblike large area LaB6 plasma source for Multi-Purpose Plasma facility

    International Nuclear Information System (INIS)

    Woo, Hyun-Jong; Chung, Kyu-Sun; You, Hyun-Jong; Lee, Myoung-Jae; Lho, Taihyeop; Choh, Kwon Kook; Yoon, Jung-Sik; Jung, Yong Ho; Lee, Bongju; Yoo, Suk Jae; Kwon, Myeon

    2007-01-01

    A Multi-Purpose Plasma (MP 2 ) facility has been renovated from Hanbit mirror device [Kwon et al., Nucl. Fusion 43, 686 (2003)] by adopting the same philosophy of diversified plasma simulator (DiPS) [Chung et al., Contrib. Plasma Phys. 46, 354 (2006)] by installing two plasma sources: LaB 6 (dc) and helicon (rf) plasma sources; and making three distinct simulators: divertor plasma simulator, space propulsion simulator, and astrophysics simulator. During the first renovation stage, a honeycomblike large area LaB 6 (HLA-LaB 6 ) cathode was developed for the divertor plasma simulator to improve the resistance against the thermal shock fragility for large and high density plasma generation. A HLA-LaB 6 cathode is composed of the one inner cathode with 4 in. diameter and the six outer cathodes with 2 in. diameter along with separate graphite heaters. The first plasma is generated with Ar gas and its properties are measured by the electric probes with various discharge currents and magnetic field configurations. Plasma density at the middle of central cell reaches up to 2.6x10 12 cm -3 , while the electron temperature remains around 3-3.5 eV at the low discharge current of less than 45 A, and the magnetic field intensity of 870 G. Unique features of electric property of heaters, plasma density profiles, is explained comparing with those of single LaB 6 cathode with 4 in. diameter in DiPS

  18. Interplay between parametric instabilities in fusion - relevant laser plasmas

    International Nuclear Information System (INIS)

    Huller, St.

    2003-01-01

    The control of parametric instabilities plays an important role in laser fusion. They are driven by the incident laser beams in the underdense plasma surrounding a fusion capsule and hinder the absorption process of incident laser light which is necessary to heat the fusion target. Due to its high intensity and power, the laser light modifies the plasma density dynamically, such that two or more parametric instabilities compete, in particular stimulated Brillouin scattering and the filamentation instability. The complicated interplay between these parametric instabilities is studied in detail by developing an adequate model accompanied by numerical simulations with multidimensional codes. The model is applied to generic and to smoothed laser beams, which are necessary to limit parametric instabilities, with parameters close to experimental conditions. (author)

  19. Guiding of short, intense laser pulses through solid guides and preformed plasma channels

    International Nuclear Information System (INIS)

    Borghesi, M.; Mackinnon, A.J.; Gaillard, R.; Malka, G.; Vickers, C.; Willi, O.; Blanchot, N.; Miquel, J.L.; Canaud, B.; Davies, J.R.; Malka, G.; Offenberger, A.A.

    2000-01-01

    In a series of experiments carried out at the Rutherford Appleton Laboratory, Chilton (UK) and at the Commissariat a l'Energie Atomique, Limeil (France), various techniques of guiding ultra-intense laser pulses over distances exceeding the natural diffraction length were investigated. Efficient guiding was demonstrated both through density channels formed in an underdense plasma by an intense prepulse and through solid guides (hollow capillary tubes). Indication of collimated fast electron propagation though solid targets has also been obtained. (authors)

  20. Plasma response to electron energy filter in large volume plasma device

    International Nuclear Information System (INIS)

    Sanyasi, A. K.; Awasthi, L. M.; Mattoo, S. K.; Srivastava, P. K.; Singh, S. K.; Singh, R.; Kaw, P. K.

    2013-01-01

    An electron energy filter (EEF) is embedded in the Large Volume Plasma Device plasma for carrying out studies on excitation of plasma turbulence by a gradient in electron temperature (ETG) described in the paper of Mattoo et al. [S. K. Mattoo et al., Phys. Rev. Lett. 108, 255007 (2012)]. In this paper, we report results on the response of the plasma to the EEF. It is shown that inhomogeneity in the magnetic field of the EEF switches on several physical phenomena resulting in plasma regions with different characteristics, including a plasma region free from energetic electrons, suitable for the study of ETG turbulence. Specifically, we report that localized structures of plasma density, potential, electron temperature, and plasma turbulence are excited in the EEF plasma. It is shown that structures of electron temperature and potential are created due to energy dependence of the electron transport in the filter region. On the other hand, although structure of plasma density has origin in the particle transport but two distinct steps of the density structure emerge from dominance of collisionality in the source-EEF region and of the Bohm diffusion in the EEF-target region. It is argued and experimental evidence is provided for existence of drift like flute Rayleigh-Taylor in the EEF plasma

  1. Large area atmospheric-pressure plasma jet

    Science.gov (United States)

    Selwyn, Gary S.; Henins, Ivars; Babayan, Steve E.; Hicks, Robert F.

    2001-01-01

    Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

  2. Space-time evolution of the power absorbed by creating and heating a hydrogen plasma column by a pulsed laser beam

    International Nuclear Information System (INIS)

    Pincosy, Philip; Dufresne, Daniel; Bournot, Philippe; Caressa, J.-P.; Autric, Michel

    1976-01-01

    Space-time measurements of light intensity are presented for the analysis of the processes involved in the creation and heating of an under-dense hydrogen plasma column by a pulsed CO 2 laser beam. The laser beam trapping due to the rapid development of a radial electron density gradient is specifically demonstrated. Time measurements of the changes in the laser power longitudinally transmitted through the plasma give evidence for a significant absorption of the incident power during the first 150 nanoseconds of the interaction [fr

  3. Laser propagation and soliton generation in strongly magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Feng, W.; Li, J. Q.; Kishimoto, Y. [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2016-03-15

    The propagation characteristics of various laser modes with different polarization, as well as the soliton generation in strongly magnetized plasmas are studied numerically through one-dimensional (1D) particle-in-cell (PIC) simulations and analytically by solving the laser wave equation. PIC simulations show that the laser heating efficiency substantially depends on the magnetic field strength, the propagation modes of the laser pulse and their intensities. Generally, large amplitude laser can efficiently heat the plasma with strong magnetic field. Theoretical analyses on the linear propagation of the laser pulse in both under-dense and over-dense magnetized plasmas are well confirmed by the numerical observations. Most interestingly, it is found that a standing or moving soliton with frequency lower than the laser frequency is generated in certain magnetic field strength and laser intensity range, which can greatly enhance the laser heating efficiency. The range of magnetic field strength for the right-hand circularly polarized (RCP) soliton formation with high and low frequencies is identified by solving the soliton equations including the contribution of ion's motion and the finite temperature effects under the quasi-neutral approximation. In the limit of immobile ions, the RCP soliton tends to be peaked and stronger as the magnetic field increases, while the enhanced soliton becomes broader as the temperature increases. These findings in 1D model are well validated by 2D simulations.

  4. Measurements of laser-hole boring into overdense plasmas using x-ray laser refractometry (invited)

    International Nuclear Information System (INIS)

    Kodama, R.; Takahashi, K.; Tanaka, K.A.; Kato, Y.; Murai, K.; Weber, F.; Barbee, T.W.; DaSilva, L.B.

    1999-01-01

    We developed a 19.6 nm laser x-ray laser grid-image refractometer (XRL-GIR) to diagnose laser-hole boring into overdense plasmas. The XRL-GIR was optimized to measure two-dimensional electron density perturbation on a scale of a few tens of μm in underdense plasmas. Electron density profiles of laser-produced plasmas were obtained for 10 20 - 10 22 cm -3 with the XRL-GIR and for 10 19 - 10 20 cm -3 from an ultraviolet interferometer, the profiles of which were compared with those from hydrodynamic simulation. By using this XRL-GIR, we directly observed laser channeling into overdense plasmas accompanied by a bow shock wave showing a Mach cone ascribed to supersonic propagation of the channel front. copyright 1999 American Institute of Physics

  5. Parametric instabilities in large plasmas

    International Nuclear Information System (INIS)

    Brambilla, Marco; Liberman, Bernardo.

    1979-01-01

    Parametric decay processes in large plasmas are considered as the linear stage of a three wave interaction (pump, sideband and beat wave) in which the amplitude of the externally excited pump is sufficiently large to neglect pump depletion to first order, yet sufficiently small to allow a linearized treatment of the pump propagation to zeroth order. The coupling coefficients are then obtained from an iterative solution of Vlasov equation, and a compact expression is derived, in which the multiple series over Bessel functions is explicitly summed. Even in the limit of a very long wavelength pump, the dispersion relation obtained in this way does not coincide with the one obtained using the well-known ''dipole'' approximation, unless both the sideband and beat wave are resonant modes of the plasma. An analysis of the origin of this discrepancy allows us to conclude that ''quasimodes'' (evanescent waves driven absolutely unstable by the pump) are more correctly described by the iterative approach

  6. Multispecies Weibel Instability for Intense Ion Beam Propagation Through Background Plasma

    CERN Document Server

    Davidson, Ronald C; Kaganovich, Igor D; Qin, Hong; Startsev, Edward

    2005-01-01

    In application of heavy ion beams to high energy density physics and fusion, background plasma is utilized to neutralize the beam space charge during drift compression and/or final focus of the ion beam. It is important to minimize the deleterious effects of collective instabilities on beam quality associated with beam-plasma interactions. Plasma electrons tend to neutralize both the space charge and current of the beam ions. It is shown that the presence of the return current greatly modifies the electromagnetic Weibel instability (also called the filamentation instability), i.e., the growth rate of the filamentation instability greatly increases if the background ions are much lighter than the beam ions and the plasma density is comparable to the ion beam density. This may preclude using underdense plasma of light gases in heavy ion beam applications. It is also shown that the return current may be subject to the fast electrostatic two-stream instability.

  7. The Interaction of C-Band Microwaves with Large Plasma Sheets

    International Nuclear Information System (INIS)

    Ding Liang; Huo Wenqing; Yang Xinjie; Xu Yuemin

    2012-01-01

    A large plasma sheet 60 cm×60 cm×2 cm in size was generated using a hollow cathode, and measurements were conducted for interactions including transmission, reflection and absorption. With different discharge parameters, plasma sheets can vary and influence microwave strength. Microwave reflection decreases when the discharge current rises, and the opposite occurs in transmission. The C-band microwave is absorbed when it is propagated through large plasma sheets at higher pressure. When plasma density and collision frequency are fitted with incident microwave frequency, a large amount of microwave energy is consumed. Reflection, transmission and absorption all exist simultaneously. Plasma sheets are an attractive alternative to microwave steering at low pressure, and the microwave reflection used in receiving radar can be altered by changing the discharge parameters.

  8. X-ray spectroscopy from fusion plasmas

    International Nuclear Information System (INIS)

    Glenzer, S H.

    1998-01-01

    Our understanding of laser energy coupling into laser-driven inertial confinement fusion targets largely depends on our ability to accurately measure and simulate the plasma conditions in the underdense corona and in high density capsule implosions. X-ray spectroscopy is an important technique which has been applied to measure the total absorption of laser energy into the fusion target, the fraction of laser energy absorbed by hot electrons, and the conditions in the fusion capsule in terms of density and temperature. These parameters provide critical benchmarking data for performance studies of the fusion target and for radiation-hydrodynamic and laser-plasma interaction simulations. Using x-ray spectroscopic techniques for these tasks has required its application to non-standard conditions where kinetics models have not been extensively tested. In particular, for the conditions in high density implosions, where electron temperatures achieve 1 - 2 keV and electron densities reach 10 24 cm -3 evolving on time scales of 21 cm -3 and which am independently diagnosed with Thomson scattering and stimulated Raman scattering. We find that kinetics modeling is in good agreement with measured intensities of the dielectronic satellites of the He-β line (n= l-3) of Ar XVII. Applying these findings to the experimental results of capsule implosions provides additional evidence of temperature gradients at peak compression

  9. Large-scale structuring of a rotating plasma due to plasma macroinstabilities

    International Nuclear Information System (INIS)

    Kikuchi, Toshinori; Ikehata, Takashi; Sato, Naoyuki; Watahiki, Takeshi; Tanabe, Toshio; Mase, Hiroshi

    1995-01-01

    The formation of coherent structures during plasma macroinstabilities have been of interest in view of the nonlinear plasma physics. In the present paper, we have investigated in detail, the mechanism and specific features of large-scale structuring of a rotating plasma. In the case of weak magnetic field, the plasma ejected from a plasma gun has a high beta value (β > 1) so that it expands rapidly across the magnetic field excluding a magnetic flux from its interior. Then, the boundary between the expanding plasma and the magnetic field becomes unstable against Rayleigh-Taylor instability. This instability has the higher growth rate at the shorter wavelength and the mode appears as flute. These features of the instability are confirmed by the observation of radial plasma jets with the azimuthal mode number m=20-40 in the early time of the plasma expansion. In the case of strong magnetic field, on the other hand, the plasma little expands and rotates at two times the ion sound speed. Especially, we observe spiral jets of m=2 instead of short-wavelength radial jets. This mode appears only when a glass target is installed or a dense neutral gas is introduced around the plasma to give the plasma a frictional force. From these results and with reference to the theory of plasma instabilities, the centrifugal instability caused by a combination of the velocity shear and centrifugal force is concluded to be responsible for the formation of spiral jets. (author)

  10. 5. Laser plasma interaction

    International Nuclear Information System (INIS)

    Labaune, C.; Fuchs, J.; Bandulet, H.

    2002-01-01

    Imprint elimination, smoothing and preheat control are considerable problems in inertial fusion and their possible solution can be achieved by using low-density porous materials as a buffer in target design. The articles gathered in this document present various aspects of the laser-plasma interaction, among which we have noticed: -) numerical algorithmic improvements of the Vlasov solver toward the simulation of the laser-plasma interaction are proposed, -) the dependence of radiation temperatures and X-ray conversion efficiencies of hohlraum on the target structures and laser irradiation conditions are investigated, -) a study of laser interaction with ultra low-density (0,5 - 20 mg/cm 3 ) porous media analyzing backscattered light at incident laser frequency ω 0 and its harmonics 3*ω 0 /2 and 2*ω 0 is presented, -) investigations of laser interaction with solid targets and crater formation are carried out with the objective to determine the ablation loading efficiency, -) a self organization in an intense laser-driven plasma and the measure of the relative degree of order of the states in an open system based on the S-theorem are investigated, and -) the existence and stability of electromagnetic solitons generated in a relativistic interaction of an intense laser light with uniform under-dense cold plasma are studied

  11. Dwell time considerations for large area cold plasma decontamination

    Science.gov (United States)

    Konesky, Gregory

    2009-05-01

    Atmospheric discharge cold plasmas have been shown to be effective in the reduction of pathogenic bacteria and spores and in the decontamination of simulated chemical warfare agents, without the generation of toxic or harmful by-products. Cold plasmas may also be useful in assisting cleanup of radiological "dirty bombs." For practical applications in realistic scenarios, the plasma applicator must have both a large area of coverage, and a reasonably short dwell time. However, the literature contains a wide range of reported dwell times, from a few seconds to several minutes, needed to achieve a given level of reduction. This is largely due to different experimental conditions, and especially, different methods of generating the decontaminating plasma. We consider these different approaches and attempt to draw equivalencies among them, and use this to develop requirements for a practical, field-deployable plasma decontamination system. A plasma applicator with 12 square inches area and integral high voltage, high frequency generator is described.

  12. LLNL large-area inductively coupled plasma (ICP) source: Experiments

    International Nuclear Information System (INIS)

    Richardson, R.A.; Egan, P.O.; Benjamin, R.D.

    1995-05-01

    We describe initial experiments with a large (76-cm diameter) plasma source chamber to explore the problems associated with large-area inductively coupled plasma (ICP) sources to produce high density plasmas useful for processing 400-mm semiconductor wafers. Our experiments typically use a 640-nun diameter planar ICP coil driven at 13.56 MHz. Plasma and system data are taken in Ar and N 2 over the pressure range 3-50 mtorr. RF inductive power was run up to 2000W, but typically data were taken over the range 100-1000W. Diagnostics include optical emission spectroscopy, Langmuir probes, and B probes as well as electrical circuit measurements. The B and E-M measurements are compared with models based on commercial E-M codes. Initial indications are that uniform plasmas suitable for 400-mm processing are attainable

  13. Analysis of plasma instabilities and verification of the BOUT code for the Large Plasma Device

    International Nuclear Information System (INIS)

    Popovich, P.; Carter, T. A.; Friedman, B.; Umansky, M. V.

    2010-01-01

    The properties of linear instabilities in the Large Plasma Device [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] are studied both through analytic calculations and solving numerically a system of linearized collisional plasma fluid equations using the three-dimensional fluid code BOUT[M. Umansky et al., Contrib. Plasma Phys. 180, 887 (2009)], which has been successfully modified to treat cylindrical geometry. Instability drive from plasma pressure gradients and flows is considered, focusing on resistive drift waves and the Kelvin-Helmholtz and rotational interchange instabilities. A general linear dispersion relation for partially ionized collisional plasmas including these modes is derived and analyzed. For Large Plasma Device relevant profiles including strongly driven flows, it is found that all three modes can have comparable growth rates and frequencies. Detailed comparison with solutions of the analytic dispersion relation demonstrates that BOUT accurately reproduces all characteristics of linear modes in this system.

  14. On interaction of large dust grains with fusion plasma

    International Nuclear Information System (INIS)

    Krasheninnikov, S. I.; Smirnov, R. D.

    2009-01-01

    So far the models used to study dust grain-plasma interactions in fusion plasmas neglect the effects of dust material vapor, which is always present around dust in rather hot and dense edge plasma environment in fusion devices. However, when the vapor density and/or the amount of ionized vapor atoms become large enough, they can alter the grain-plasma interactions. Somewhat similar processes occur during pellet injection in fusion plasma. In this brief communication the applicability limits of the models ignoring vapor effects in grain-plasma interactions are obtained.

  15. Development of very large helicon plasma source

    International Nuclear Information System (INIS)

    Shinohara, Shunjiro; Tanikawa, Takao

    2004-01-01

    We have developed a very large volume, high-density helicon plasma source, 75 cm in diameter and 486 cm in axial length; full width at half maximum of the plasma density is up to ∼42 cm with good plasma uniformity along the z axis. By the use of a spiral antenna located just outside the end of the vacuum chamber through a quartz-glass window, plasma can be initiated with a very low value of radio frequency (rf) power ( 12 cm -3 is successfully produced with less than several hundred Watt; achieving excellent discharge efficiency. It is possible to control the radial density profile in this device by changing the magnetic field configurations near the antenna and/or the antenna radiation-field patterns

  16. On the control of filamentation of intense laser beams propagating in underdense plasma

    International Nuclear Information System (INIS)

    Williams, E.A.

    2006-01-01

    In indirect drive inertial confinement fusion ignition designs, the laser energy is delivered into the hohlraum through the laser entrance holes (LEHs), which are sized as small as practicable to minimize x-ray radiation losses. On the other hand, deleterious laser plasma processes, such as filamentation and stimulated backscatter, typically increase with laser intensity. Ideally, therefore, the laser spot shape should be a close fit to the LEH, with uniform (envelope) intensity in the spot and minimal energy at larger radii spilling onto the LEH material. This keeps the laser intensity as low as possible, consistent with the area of the LEH aperture and the power requirements of the design. This can be achieved (at least for apertures significantly larger than the laser's aberrated focal spot) by the use of custom-designed phase plates. However, outfitting the 192-beam National Ignition Facility [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Tech. 26, 755 1994)] laser with multiple sets of phase plates optimized for a variety of different LEH aperture sizes is an expensive proposition. It is thus important to assess the impact on laser-plasma interaction processes of using phase plates with a smaller than optimum focal spot (or even no phase plates at all!) and then defocusing the beam to expand it to fill the LEH and lower its intensity. Significant effects are found from changes in the characteristic sizes of the laser speckle, from the lack of uniformity of the laser envelope out of the focal plane and on the efficacy of additional polarization smoothing and/or smoothing by spectral dispersion (SSD). These effects are quantified with analytic estimates and simulations using PF3D, our laser-plasma interaction code

  17. Time-resolved electron thermal conduction by probing of plasma formation in transparent solids with high power subpicosecond laser pulses

    International Nuclear Information System (INIS)

    Vu, B.T.V.

    1994-02-01

    This dissertation work includes a series of experimental measurements in a search for better understanding of high temperature (10 4 -10 6 K) and high density plasmas (10 22 -10 24 cm -3 ) produced by irradiating a transparent solid target with high intensity (10 13 - 10 15 W/cm 2 ) and subpicosecond (10 -12 -10 -13 s) laser pulses. Experimentally, pump and probe schemes with both frontside (vacuum-plasma side) and backside (plasma-bulk material side) probes are used to excite and interrogate or probe the plasma evolution, thereby providing useful insights into the plasma formation mechanisms. A series of different experiments has been carried out so as to characterize plasma parameters and the importance of various nonlinear processes. Experimental evidence shows that electron thermal conduction is supersonic in a time scale of the first picosecond after laser irradiation, so fast that it was often left unresolved in the past. The experimental results from frontside probing demonstrate that upon irradiation with a strong (pump) laser pulse, a thin high temperature (∼40eV) super-critical density (∼10 23 /cm 3 ) plasma layer is quickly formed at the target surface which in turn becomes strongly reflective and prevents further transmission of the remainder of the laser pulse. In the bulk region behind the surface, it is also found that a large sub-critical (∼10 18 /cm 3 ) plasma is produced by inverse Bremsstrahlung absorption and collisional ionization. The bulk underdense plasma is evidenced by large absorption of the backside probe light. A simple and analytical model, modified from the avalanche model, for plasma evolution in transparent materials is proposed to explain the experimental results. Elimination of the bulk plasma is then experimentally illustrated by using targets overcoated with highly absorptive films

  18. Effects of ponderomotive forces and space-charge field on laser plasma hydrodynamics

    International Nuclear Information System (INIS)

    Cang Yu; Lu Xin; Wu Huichun; Zhang Jie

    2005-01-01

    Using a two-fluid two-temperature hydrodynamic code, authors studied the hydrodynamics in the interaction of intense (10 15 W/cm 2 ) ultrashort (150 fs) laser pulses and linear density plasmas. The simulation results show the ponderomotive force effect on the formation of the electron density ripples in under-dense region, such ripples increase the reflection of the laser pulse, and on the separation of the plasma in critical surface. Quasi-electroneutrality is not suitable in this case because of the different ponderomotive force and the gradient of thermal-pressure for ions and electrons. Ions are moved by the electrostatic force. Comparing with the simulation results from one-fluid two-temperature code, authors find that under strong ponderomotive force and gradient of thermo-pressure, two-fluid code is more suitable to simulate the hydrodynamics of plasmas. (authors)

  19. Particle sources with high-intensity lasers: a tool for plasma diagnostics and an innovative source for applications; Sources de particules avec des lasers de haute intensite: un outil pour les diagnostics plasma et une source innovante pour les applications

    Energy Technology Data Exchange (ETDEWEB)

    Fritzler, S

    2003-09-15

    This work is an experimental study on particle generation with high-intensity lasers. This document is divided into 4 parts, whereas the first is dedicated to theoretical basics of particle generation and acceleration mechanisms during relativistic laser plasma interactions, the 3 other parts cover experimental studies on neutron, electron as well as proton generation. In the first part basic laser and plasma characteristics will be introduced as well as physical processes of interest during the interaction of a relativistic high-intensity laser with an underdense / overdense plasma. In the second part we introduce methodological basics of neutron generation by D(d,n)He{sup 3} reactions since this can reveal information about ion kinetics and possible ion heating mechanisms in plasmas. Subsequently the set-up for this experiment, pursued in the underdense regime, will be described in detail. The experimental results will be discussed for the gas jet interaction as well as for the beam target model since it was deduced that plasma ions are heated during the interaction to fusion temperatures of about 1 keV. The third part describes the generation of an electron beam with an energy up to 200 MeV in a new regime termed 'forced laser Wakefield'. Here, the presented experimental results were for the first time fully explained and even extended by the numerical modelling of this interaction in terms of energy, yield, angular divergence, emittance as well as bunch length of this electron beam. In the last part we present a 10 MeV proton beam generation using foil targets and a 10 Hz laser. Again the kinematic simulation of this experiment is in agreement with the experimental results by means of yield and angular divergence.

  20. Laser beam accelerator

    International Nuclear Information System (INIS)

    Tajima, T.; Dawson, J.M.

    1981-01-01

    Parallel intense photon (laser, microwave, etc.) beams /omega/sub //0, k/sub 0/ and /omega/sub //1, k/sub 1/ shone on a plasma with frequency separation equal to the plasma frequency /omega/sub //p is capable of accelerating plasma electrons to high energies in large flux. The photon beat excites through the forward Raman scattering large amplitude plasmons whose phase velocity is equal to (/omega/ /sub 0/-/omega/sub //1)/(k/sub 0/-k/sub 1/), close to c in an underdense plasma. The multiple forward Raman instability produces smaller and smaller frequency and group velocity of photons; thus the photons slow down in the plasma by emitting accelerated electrons (inverse Cherenkov process). 6 refs

  1. Light absorption and scattering mechanisms in laser fusion plasmas

    International Nuclear Information System (INIS)

    Barnes, C.; Estabrook, K.G.; Kruer, W.L.; Langdon, A.B.; Lasinski, B.F.; Max, C.E.; Randall, C.; Thomson, J.J.

    1977-01-01

    The picture of laser light absorption and scattering which is emerging from theory and computer simulation studies of laser-plasma interactions is described. On the subject of absorption, we discuss theoretical and experimental evidence that resonance absorption in a steepened density profile is a dominant absorption mechanism. Recent work also indicates the presence of critical surface ripples, which we study using two and three dimensional computer simulations. Predictions of hot electron spectra due to resonance absorption are described, as are effects of plasma outflow. We then discuss two regimes where stimulated scattering may occur. Brillouin scattering is expected in the underdense target blow-off, for long laser pulses, and is limited by ion heating. Raman scattering in the background gas of a reactor target chamber is predicted to be at most a 10 percent effect for 1 μm lasers

  2. Obliquely propagating large amplitude solitary waves in charge neutral plasmas

    Directory of Open Access Journals (Sweden)

    F. Verheest

    2007-01-01

    Full Text Available This paper deals in a consistent way with the implications, for the existence of large amplitude stationary structures in general plasmas, of assuming strict charge neutrality between electrons and ions. With the limit of pair plasmas in mind, electron inertia is retained. Combining in a fluid dynamic treatment the conservation of mass, momentum and energy with strict charge neutrality has indicated that nonlinear solitary waves (as e.g. oscillitons cannot exist in electron-ion plasmas, at no angle of propagation with respect to the static magnetic field. Specifically for oblique propagation, the proof has turned out to be more involved than for parallel or perpendicular modes. The only exception is pair plasmas that are able to support large charge neutral solitons, owing to the high degree of symmetry naturally inherent in such plasmas. The nonexistence, in particular, of oscillitons is attributed to the breakdown of the plasma approximation in dealing with Poisson's law, rather than to relativistic effects. It is hoped that future space observations will allow to discriminate between oscillitons and large wave packets, by focusing on the time variability (or not of the phase, since the amplitude or envelope graphs look very similar.

  3. Stable long range proton acceleration driven by intense laser pulse with underdense plasmas

    Czech Academy of Sciences Publication Activity Database

    Gu, Yanjun; Zhu, Z.; Li, F.X.; Yu, Q.; Huang, S.; Zhang, F.; Kong, Q.; Kawata, S.

    2014-01-01

    Roč. 21, č. 6 (2014), "063104-1"-"063104-6" ISSN 1070-664X R&D Projects: GA MŠk ED1.1.00/02.0061 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 Keywords : ion-acceleration * fast ignition * generation * beams * targets Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.142, year: 2014

  4. Frequency Upconversion and Parametric Surface Instabilities in Microwave Plasma Interactions.

    Science.gov (United States)

    Rappaport, Harold Lee

    In this thesis the interaction of radiation with plasmas whose density profiles are nearly step functions of space and/or time are studied. The wavelengths of radiation discussed are large compared with plasma density gradient scale lengths. The frequency spectra are evaluated and the energy balance investigated for the transmitted and reflected transient electromagnetic waves that are generated when a monochromatic source drives a finite width plasma in which a temporal step increase in density occurs. Transmission resonances associated with the abrupt boundaries manifest themselves as previously unreported multiple frequency peaks in the transmitted electromagnetic spectrum. A tunneling effect is described in which a burst of energy is transmitted from the plasma immediately following a temporal density transition. Stability of an abruptly bounded plasma, one for which the incident radiation wavelength is large compared with the plasma density gradient scale length, is investigated for both s and p polarized radiation types. For s-polarized radiation a new formalism is introduced in which pump induced perturbations are expressed as an explicit superposition of linear and non-linear plasma half-space modes. Results for a particular regime and a summary of relevant literature is presented. We conclude that when s-polarized radiation acts alone on an abrupt diffusely bounded underdense plasma stimulated excitation of electron surface modes is suppressed. For p-polarized radiation the recently proposed Lagrangian Frame Two-Plasmon Decay mode (LFTPD) ^dag is investigated in the regime in which the instability is not resonantly coupled to surface waves propagating along the boundary region. In this case, spatially dependent growth rate profiles and spatially dependent transit layer magnetic fields are reported. The regime is of interest because we have found that when the perturbation wavenumber parallel to the boundary is less than the pump frequency divided by twice

  5. Application-oriented research on plasma channeling of a large pulsed current

    International Nuclear Information System (INIS)

    Liu Jingye

    2000-01-01

    Utilizing the avalanche effect of plasma produced by the collision of energetic primary electrons with hydrogen molecules in a plasma, channeling of a large pulsed current is achieved, with the plasma acting as the carrier

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

    Science.gov (United States)

    Audebert, P.

    2007-11-01

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

  7. Plasma balls in large-N gauge theories and localized black holes

    International Nuclear Information System (INIS)

    Aharony, Ofer; Minwalla, Shiraz; Wiseman, Toby

    2006-01-01

    We argue for the existence of plasma balls-metastable, nearly homogeneous lumps of gluon plasma at just above the deconfinement energy density-in a class of large-N confining gauge theories that undergo first-order deconfinement transitions. Plasma balls decay over a time scale of order N 2 by thermally radiating hadrons at the deconfinement temperature. In gauge theories that have a dual description that is well approximated by a theory of gravity in a warped geometry, we propose that plasma balls map to a family of classically stable finite-energy black holes localized in the IR. We present a conjecture for the qualitative nature of large-mass black holes in such backgrounds and numerically construct these black holes in a particular class of warped geometries. These black holes have novel properties; in particular, their temperature approaches a nonzero constant value at large mass. Black holes dual to plasma balls shrink as they decay by Hawking radiation; towards the end of this process, they resemble ten-dimensional Schwarzschild black holes, which we propose are dual to small plasma balls. Our work may find practical applications in the study of the physics of localized black holes from a dual viewpoint

  8. Large amplitude ion-acoustic solitons in dusty plasmas

    International Nuclear Information System (INIS)

    Tiwari, R. S.; Jain, S. L.; Mishra, M. K.

    2011-01-01

    Characteristics of ion-acoustic soliton in dusty plasma, including the dynamics of heavily charged massive dust grains, are investigated following the Sagdeev Potential formalism. Retaining fourth order nonlinearities of electric potential in the expansion of the Sagdeev Potential in the energy equation for a pseudo particle and integrating the resulting energy equation, large amplitude soliton solution is determined. Variation of amplitude (A), half width (W) at half maxima and the product P = AW 2 of the Korteweg-deVries (KdV), dressed and large amplitude soliton as a function of wide range of dust concentration are numerically studied for recently observed parameters of dusty plasmas. We have also presented the region of existence of large amplitude ion-acoustic soliton in the dusty plasma by analyzing the structure of the pseudo potential. It is found that in the presence of positively charged dust grains, system supports only compressive solitons, on the other hand, in the presence of negatively charged dust grains, the system supports compressive solitons up to certain critical concentration of dust grains and above this critical concentration, the system can support rarefactive solitons also. The effects of dust concentration, charge, and mass of the dust grains, on the characteristics of KdV, dressed and large amplitude the soliton, i.e., amplitude (A), half width at half maxima (W), and product of amplitude (A) and half width at half maxima (P = AW 2 ), are discussed in detail

  9. A model for steady-state large-volume plasma generation

    International Nuclear Information System (INIS)

    Uhm, H.S.; Miller, J.D.; Schneider, R.F.

    1991-01-01

    In this paper, a simple, new scheme to generate a uniform, steady-state, large-volume plasma is presented. The weakly magnetized plasma is created by direct ionization of the background gas by low-energy electrons generated from thermionic filaments. An annular arrangement of the filaments ensures a uniform plasma density in the radial direction as predicted by theory. Experiments have been performed to characterize the plasma generated in such a configuration. In order to explain the experimental observation, we develop a bulk plasma theory based on plasma transport via cross-field diffusion. As assumed in the theoretical model, the experimental measurements indicate a uniform plasma density along the axis. Both the theory and experiment indicate that the plasma density is a function of the square of the external magnetic field. The theory also predicts the plasma density to be proportional to the neutral density to the two-thirds power in agreement with the experimental data. We also observe the experimental data to agree remarkably well with theoretical prediction for a broad range of system parameters

  10. REFLECT: a program to integrate the wave equation through a plane stratified plasma

    International Nuclear Information System (INIS)

    Greene, J.W.

    1975-01-01

    A program was developed to integrate the wave equation through a plane stratified plasma with a general density distribution. The reflection and transmission of a plane wave are computed as a function of the angle of incidence. The polarization of the electric vector is assumed to be perpendicular to the plane of incidence. The model for absorption by classical inverse bremsstrahlung avoids the improper extrapolation of underdense formulae that are singular at the plasma critical surface. Surprisingly good agreement with the geometric-optics analysis of a linear layer was found. The system of ordinary differential equations is integrated by the variable-step, variable-order Adams method in the Lawrence Livermore Laboratory Gear package. Parametric studies of the absorption are summarized, and some possibilities for further development of the code are discussed. (auth)

  11. Producing High Intense Attosecond Pulse Train by Interaction of Three-Color Pulse and Overdense Plasma

    Science.gov (United States)

    Salehi, M.; Mirzanejad, S.

    2017-05-01

    Amplifying the attosecond pulse by the chirp pulse amplification method is impossible. Furthermore, the intensity of attosecond pulse is low in the interaction of laser pulse and underdense plasma. This motivates us to propose using a multi-color pulse to produce the high intense attosecond pulse. In the present study, the relativistic interaction of a three-color linearly-polarized laser-pulse with highly overdense plasma is studied. We show that the combination of {{ω }}1, {{ω }}2 and {{ω }}3 frequencies decreases the instance full width at half maximum reflected attosecond pulse train from the overdense plasma surface. Moreover, we show that the three-color pulse increases the intensity of generated harmonics, which is explained by the relativistic oscillating mirror model. The obtained results demonstrate that if the three-color laser pulse interacts with overdense plasma, it will enhance two orders of magnitude of intensity of ultra short attosecond pulses in comparison with monochromatic pulse.

  12. Controlled elaboration of large-area plasmonic substrates by plasma process

    International Nuclear Information System (INIS)

    Pugliara, A; Despax, B; Makasheva, K; Bonafos, C; Carles, R

    2015-01-01

    Elaboration in a controlled way of large-area and efficient plasmonic substrates is achieved by combining sputtering of silver nanoparticles (AgNPs) and plasma polymerization of the embedding dielectric matrix in an axially asymmetric, capacitively coupled RF discharge maintained at low gas pressure. The plasma parameters and deposition conditions were optimized according to the optical response of these substrates. Structural and optical characterizations of the samples confirm the process efficiency. The obtained results indicate that to deposit a single layer of large and closely situated AgNPs, a high injected power and short sputtering times must be privileged. The plasma-elaborated plasmonic substrates appear to be very sensitive to any stimuli that affect their plasmonic response. (paper)

  13. Physics and technology of large plasma focus devices

    International Nuclear Information System (INIS)

    Herold, H.

    1990-01-01

    This paper reports on the plasma focus (PF) which produces a high temperature (0,5 to 1 keV), high density (5 · 10 18 cm -3 ), short living (up to 500 ns) fusion plasma in a very simple and cheap device. In the focus plasma, fusion processes take place with an energy efficiency which is not surpassed even by large Tokamak or Inertial Confinement Fusion devices. But this fusion efficiency and the high fusion neutron yield are not the only impetus to PF research. Due to the high energy density in the focus plasma (j ≥ 10 6 A/cm 2 exclamation point), many very interesting, mostly nonlinear phenomena take place which led to high intensity electron, ion and radiation emission. Micro- and macro instabilities, turbulence and selforganization processes develop. Most of these phenomena are not or only poorly understood

  14. MHD instabilities and their effects on plasma confinement in the large helical device plasmas

    International Nuclear Information System (INIS)

    Toi, K.

    2002-01-01

    MHD stability of NBI heated plasmas and impacts of MHD modes on plasma confinement are intensively studied in the Large Helical Device (LHD). Three characteristic MHD instabilities were observed, that is, (1) pressure driven modes excited in the plasma edge, (2) pressure driven mode in the plasma core, and (3) Alfven eigenmodes (AEs) driven by energetic ions. MHD mode excited in the edge region accompanies multiple satellites, and is called Edge Harmonic Modes (EHMs). EHM sometimes has a bursting character. The bursting EHM transiently decreases the stored energy by about 15 percent. In the plasma core region, m=2/n=1 pressure driven mode is typically destabilized. The mode often induces internal collapse in the higher beta regime more than 1 percent. The internal collapse appreciably affects the global confinement. Energetic ion driven AEs are often detected in NBI-heated LHD plasmas. Particular AE with the frequency 8-10 times larger than TAE-frequency was detected in high beta plasmas more than 2 percent. The AE may be related to helicity-induced AE. Excitation of these three types of MHD instabilities and their impacts on plasma confinement are discussed. (author)

  15. Time-resolved electron thermal conduction by probing of plasma formation in transparent solids with high power subpicosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Brian -Tinh Van [Univ. of California, Davis, CA (United States)

    1994-02-01

    This dissertation work includes a series of experimental measurements in a search for better understanding of high temperature (104-106K) and high density plasmas (1022-1024cm-3) produced by irradiating a transparent solid target with high intensity (1013 - 1015W/cm2) and subpicosecond (10-12-10-13s) laser pulses. Experimentally, pump and probe schemes with both frontside (vacuum-plasma side) and backside (plasma-bulk material side) probes are used to excite and interrogate or probe the plasma evolution, thereby providing useful insights into the plasma formation mechanisms. A series of different experiments has been carried out so as to characterize plasma parameters and the importance of various nonlinear processes. Experimental evidence shows that electron thermal conduction is supersonic in a time scale of the first picosecond after laser irradiation, so fast that it was often left unresolved in the past. The experimental results from frontside probing demonstrate that upon irradiation with a strong (pump) laser pulse, a thin high temperature (~40eV) super-critical density (~1023/cm3) plasma layer is quickly formed at the target surface which in turn becomes strongly reflective and prevents further transmission of the remainder of the laser pulse. In the bulk region behind the surface, it is also found that a large sub-critical (~1018/cm3) plasma is produced by inverse Bremsstrahlung absorption and collisional ionization. The bulk underdense plasma is evidenced by large absorption of the backside probe light. A simple and analytical model, modified from the avalanche model, for plasma evolution in transparent materials is proposed to explain the experimental results. Elimination of the bulk plasma is then experimentally illustrated by using targets overcoated with highly absorptive films.

  16. Production of a large area diffuse arc plasma with multiple cathode

    International Nuclear Information System (INIS)

    Wang Cheng; Cui Hai-Chao; Li Wan-Wan; Liao Meng-Ran; Xia Wei-Dong; Xia Wei-Luo

    2017-01-01

    An arc channel at atmospheric pressure tends to shrink generally. In this paper, a non-transferred DC arc plasma device with multiple cathode is introduced to produce a large area arc plasma at atmospheric pressure. This device is comprised of a 42-mm diameter tubular chamber, multiple cathode which is radially inserted into the chamber, and a tungsten anode with a nozzle in its center. In argon/helium atmosphere, a large area and circumferential homogenous diffuse arc plasma, which fills the entire cross section surrounded by the cathode tips, is observed. Results show that the uniformity and stability of diffuse arc plasma are strongly related to the plasma forming gas. Based on these experimental results, an explanation to the arc diffusion is suggested. Moreover, the electron excitation temperature and electron density measured in diffuse helium plasma are much lower than those of constricted arc column, which indicates the diffuse helium plasma probably deviates from the local thermodynamic equilibrium state. Unlike the common non-transferred arc plasma devices, this device can provide a condition for axial-fed feedstock particles. The plasma device is attempted to spheroidize alumina powders by using the central axis to send the powder. Results show that the powder produced is usually a typical hollow sphere. (paper)

  17. A large volume uniform plasma generator for the experiments of electromagnetic wave propagation in plasma

    International Nuclear Information System (INIS)

    Yang Min; Li Xiaoping; Xie Kai; Liu Donglin; Liu Yanming

    2013-01-01

    A large volume uniform plasma generator is proposed for the experiments of electromagnetic (EM) wave propagation in plasma, to reproduce a “black out” phenomenon with long duration in an environment of the ordinary laboratory. The plasma generator achieves a controllable approximate uniform plasma in volume of 260 mm× 260 mm× 180 mm without the magnetic confinement. The plasma is produced by the glow discharge, and the special discharge structure is built to bring a steady approximate uniform plasma environment in the electromagnetic wave propagation path without any other barriers. In addition, the electron density and luminosity distributions of plasma under different discharge conditions were diagnosed and experimentally investigated. Both the electron density and the plasma uniformity are directly proportional to the input power and in roughly reverse proportion to the gas pressure in the chamber. Furthermore, the experiments of electromagnetic wave propagation in plasma are conducted in this plasma generator. Blackout phenomena at GPS signal are observed under this system and the measured attenuation curve is of reasonable agreement with the theoretical one, which suggests the effectiveness of the proposed method.

  18. Effects of Large Area Liquid Lithium Limiters on Spherical Torus Plasmas

    International Nuclear Information System (INIS)

    Kaita, R.; Majeski, R.; Boaz, M.; Efthimion, P.; Gettelfinger, G.; Gray, T.; Hoffman, D.; Jardin, S.; Kugel, H.; Marfuta, P.; Munsat, T.; Neumeyer, C.; Raftopoulos, S.; Soukhanovskii, V.; Spaleta, J.; Taylor, G.; Timberlake, J.; Woolley, R.; Zakharov, L.; Finkenthal, M.; Stutman, D.; Delgado-Aparicio, L.; Seraydarian, R.P.; Antar, G.; Doerner, R.; Luckhardt, S.; Baldwin, M.; Conn, R.W.; Maingi, R.; Menon, M.; Causey, R.; Buchenauer, D.; Ulrickson, M.; Jones, B.; Rodgers, D.

    2004-01-01

    Use of a large-area liquid lithium surface as a first wall has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter

  19. Effects of large area liquid lithium limiters on spherical torus plasmas

    International Nuclear Information System (INIS)

    Kaita, R.; Majeski, R.; Boaz, M.; Efthimion, P.; Gettelfinger, G.; Gray, T.; Hoffman, D.; Jardin, S.; Kugel, H.; Marfuta, P.; Munsat, T.; Neumeyer, C.; Raftopoulos, S.; Soukhanovskii, V.; Spaleta, J.; Taylor, G.; Timberlake, J.; Woolley, R.; Zakharov, L.; Finkenthal, M.; Stutman, D.; Delgado-Aparicio, L.; Seraydarian, R.P.; Antar, G.; Doerner, R.; Luckhardt, S.; Baldwin, M.; Conn, R.W.; Maingi, R.; Menon, M.; Causey, R.; Buchenauer, D.; Ulrickson, M.; Jones, B.; Rodgers, D.

    2005-01-01

    Use of a large-area liquid lithium surface as a limiter has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter

  20. Confinement of laser plasma expansion with strong external magnetic field

    Science.gov (United States)

    Tang, Hui-bo; Hu, Guang-yue; Liang, Yi-han; Tao, Tao; Wang, Yu-lin; Hu, Peng; Zhao, Bin; Zheng, Jian

    2018-05-01

    The evolutions of laser ablation plasma, expanding in strong (∼10 T) transverse external magnetic field, were investigated in experiments and simulations. The experimental results show that the magnetic field pressure causes the plasma decelerate and accumulate at the plasma-field interface, and then form a low-density plasma bubble. The saturation size of the plasma bubble has a scaling law on laser energy and magnetic field intensity. Magnetohydrodynamic simulation results support the observation and find that the scaling law (V max ∝ E p /B 2, where V max is the maximum volume of the plasma bubble, E p is the absorbed laser energy, and B is the magnetic field intensity) is effective in a broad laser energy range from several joules to kilo-joules, since the plasma is always in the state of magnetic field frozen while expanding. About 15% absorbed laser energy converts into magnetic field energy stored in compressed and curved magnetic field lines. The duration that the plasma bubble comes to maximum size has another scaling law t max ∝ E p 1/2/B 2. The plasma expanding dynamics in external magnetic field have a similar character with that in underdense gas, which indicates that the external magnetic field may be a feasible approach to replace the gas filled in hohlraum to suppress the wall plasma expansion and mitigate the stimulated scattering process in indirect drive ignition.

  1. On the possibility of the multiple inductively coupled plasma and helicon plasma sources for large-area processes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin-Won; Lee, Yun-Seong, E-mail: leeeeys@kaist.ac.kr; Chang, Hong-Young [Low-temperature Plasma Laboratory, Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); An, Sang-Hyuk [Agency of Defense Development, Yuseong-gu, Daejeon 305-151 (Korea, Republic of)

    2014-08-15

    In this study, we attempted to determine the possibility of multiple inductively coupled plasma (ICP) and helicon plasma sources for large-area processes. Experiments were performed with the one and two coils to measure plasma and electrical parameters, and a circuit simulation was performed to measure the current at each coil in the 2-coil experiment. Based on the result, we could determine the possibility of multiple ICP sources due to a direct change of impedance due to current and saturation of impedance due to the skin-depth effect. However, a helicon plasma source is difficult to adapt to the multiple sources due to the consistent change of real impedance due to mode transition and the low uniformity of the B-field confinement. As a result, it is expected that ICP can be adapted to multiple sources for large-area processes.

  2. Towards large-scale plasma-assisted synthesis of nanowires

    Science.gov (United States)

    Cvelbar, U.

    2011-05-01

    Large quantities of nanomaterials, e.g. nanowires (NWs), are needed to overcome the high market price of nanomaterials and make nanotechnology widely available for general public use and applications to numerous devices. Therefore, there is an enormous need for new methods or routes for synthesis of those nanostructures. Here plasma technologies for synthesis of NWs, nanotubes, nanoparticles or other nanostructures might play a key role in the near future. This paper presents a three-dimensional problem of large-scale synthesis connected with the time, quantity and quality of nanostructures. Herein, four different plasma methods for NW synthesis are presented in contrast to other methods, e.g. thermal processes, chemical vapour deposition or wet chemical processes. The pros and cons are discussed in detail for the case of two metal oxides: iron oxide and zinc oxide NWs, which are important for many applications.

  3. Relativistic electron drift in overdense plasma produced by a superintense femtosecond laser pulse

    International Nuclear Information System (INIS)

    Rastunkov, V.S.; Krainov, V.P.

    2004-01-01

    The general peculiarities of electron motion in the skin layer at the irradiation of overdense plasma by a superintense linearly polarized laser pulse of femtosecond duration are considered. The quiver electron energy is assumed to be a relativistic quantity. Relativistic electron drift along the propagation of laser radiation produced by a magnetic part of a laser field remains after the end of the laser pulse, unlike the relativistic drift of a free electron in underdense plasma. As a result, the penetration depth is much larger than the classical skin depth. The conclusion has been made that the drift velocity is a nonrelativistic quantity even at the peak laser intensity of 10 21 W/cm 2 . The time at which an electron penetrates into field-free matter from the skin layer is much less than the pulse duration

  4. Large-aperture plasma-assisted deposition of inertial confinement fusion laser coatings.

    Science.gov (United States)

    Oliver, James B; Kupinski, Pete; Rigatti, Amy L; Schmid, Ansgar W; Lambropoulos, John C; Papernov, Semyon; Kozlov, Alexei; Spaulding, John; Sadowski, Daniel; Chrzan, Z Roman; Hand, Robert D; Gibson, Desmond R; Brinkley, Ian; Placido, Frank

    2011-03-20

    Plasma-assisted electron-beam evaporation leads to changes in the crystallinity, density, and stresses of thin films. A dual-source plasma system provides stress control of large-aperture, high-fluence coatings used in vacuum for substrates 1m in aperture.

  5. Abnormally large energy spread of electron beams extracted from plasma sources

    Energy Technology Data Exchange (ETDEWEB)

    Winter, H [Technische Univ., Vienna (Austria). Inst. fuer Allgemeine Physik

    1976-07-01

    Intense electron beams extracted from DUOPLASMATRON-plasma cathodes show a high degree of modulation in intensity and an abnormally large energy spread; these facts cannot be explained simply by the temperature of the plasma electrons and the discharge structure. However, an analysis of the discharge stability behaviour and the interaction of source- and extracted beam-plasma leads to an explanation for the observed effects.

  6. Plasma polarimetry for large Cotton--Mouton and Faraday effects

    International Nuclear Information System (INIS)

    Segre, S.E.

    1995-01-01

    A formalism is presented for treating plasma polarimetry when both the Cotton--Mouton and the Faraday effects are large. For this general case it is shown that, for each measuring chord, up to nine parameters related to the plasma can be determined, instead of the usual single Faraday rotation. These parameters can be measured by a convenient modulation of the polarization state of the input radiation, and they can be used in the reconstruction of the magnetohydrodynamic equilibrium. Thus, the potential of the polarimetric diagnostic can be significantly increased, and the range of plasma conditions where the latter can be used, is extended. The importance of refraction is discussed. copyright 1995 American Institute of Physics

  7. Voltage uniformity study in large-area reactors for RF plasma deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sansonnens, L.; Pletzer, A.; Magni, D.; Howling, A.A.; Hollenstein, C. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP); Schmitt, J.P.M. [Balzers Process Systems, Palaiseau (France)

    1996-09-01

    Non-uniform voltage distribution across the electrode area results in inhomogeneous thin-film RF plasma deposition in large area reactors. In this work, a two-dimensional analytic model for the calculation of the voltage distribution across the electrode area is presented. The results of this model are in good agreement with measurements performed without plasma at 13.56 MHz and 70 MHz in a large area reactor. The principal voltage inhomogeneities are caused by logarithmic singularities in the vicinity of RF connections and not by standing waves. These singularities are only described by a two-dimensional model and cannot be intuitively predicted by analogy to a one-dimensional case. Plasma light emission measurements and thickness homogeneity studies of a-Si:H films show that the plasma reproduces these voltage inhomogeneities. Improvement of the voltage uniformity is investigated by changing the number and position of the RF connections. (author) 13 figs., 20 refs.

  8. Neutral-beam deposition in large, finite-beta noncircular tokamak plasmas

    International Nuclear Information System (INIS)

    Wieland, R.M.; Houlberg, W.A.

    1982-02-01

    A parametric pencil beam model is introduced for describing the attenuation of an energetic neutral beam moving through a tokamak plasma. The nonnegligible effects of a finite beam cross section and noncircular shifted plasma cross sections are accounted for in a simple way by using a smoothing algorithm dependent linearly on beam radius and by including information on the plasma flux surface geometry explicitly. The model is benchmarked against more complete and more time-consuming two-dimensional Monte Carlo calculations for the case of a large D-shaped tokamak plasma with minor radius a = 120 cm and elongation b/a = 1.6. Deposition profiles are compared for deuterium beam energies of 120 to 150 keV, central plasma densities of 8 x 10 13 - 2 x 10 14 cm -3 , and beam orientation ranging from perpendicular to tangential to the inside wall

  9. X-ray Synchrotron Radiation in a Plasma Wiggler

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shuoquin; /UCLA /SLAC, SSRL

    2005-09-27

    A relativistic electron beam can radiate due to its betatron motion inside an ion channel. The ion channel is induced by the electron bunch as it propagates through an underdense plasma. In the theory section of this thesis the formation of the ion channel, the trajectories of beam electrons inside the ion channel, the radiation power and the radiation spectrum of the spontaneous emission are studied. The comparison between different plasma wiggler schemes is made. The difficulties in realizing stimulated emission as the beam traverses the ion channel are investigated, with particular emphasis on the bunching mechanism, which is important for the ion channel free electron laser. This thesis reports an experiment conducted at the Stanford Linear Accelerator Center (SLAC) to measure the betatron X-ray radiations for the first time. They first describe the construction and characterization of the lithium plasma source. In the experiment, the transverse oscillations of the SLAC 28.5 GeV electron beam traversing through a 1.4 meter long lithium plasma source are clearly seen. These oscillations lead to a quadratic density dependence of the spontaneously emitted betatron X-ray radiation. The divergence angle of the X-ray radiation is measured. The absolute photon yield and the spectral brightness at 14.2 KeV photon energy are estimated and seen to be in reasonable agreement with theory.

  10. Experiment on a large-diameter plasma-filled backward-wave oscillator

    International Nuclear Information System (INIS)

    Ogura, K.; Minami, K.; Kurashina, K.I.; Kim, W.; Watanabe, T.; Ishii, K.; Sugito, S.

    1995-01-01

    A large-diameter plasma-filled backward-wave oscillator (BWO) is investigated experimentally. The parameters of slow wave structure are chosen so that the oscillation frequency is about 20GHz at 60keV beam energy. Plasma is produced by the beam and has favorable effects for beam propagation and Cerenkov oscillations. The output power of the BWO with plasma is observed to be three to six times that of vacuum BWO. The power level is several kilowatts and the efficiency is about 0.01%. For Cerenkov oscillations of a large-diameter BWO, the beam energy mainly determines the starting conditions for oscillation. The output power is strongly enhanced when the guiding magnetic field approaches the fundamental electron cyclotron resonance. This mechanism is closely related to the anomalous Doppler cyclotron resonance. The maximum power of 480kW with an efficiency of 5% is achieved even for a relatively low beam energy of 60keV. ((orig.))

  11. Production of a large diameter ECR plasma with low electron temperature

    International Nuclear Information System (INIS)

    Koga, Mayuko; Hishikawa, Yasuhiro; Tsuchiya, Hayato; Kawai, Yoshinobu

    2006-01-01

    A large diameter plasma over 300 mm in diameter is produced by electron cyclotron resonance (ECR) discharges using a cylindrical vacuum chamber of 400 mm in inner diameter. It is found that the plasma uniformity is improved by adding the nitrogen gas to pure Ar plasma. The electron temperature is decreased by adding the nitrogen gas. It is considered that the electron energy is absorbed in the vibrational energy of nitrogen molecules and the electron temperature decreases. Therefore, the adjunction of the nitrogen gas is considered to be effective for producing uniform and low electron temperature plasma

  12. Large plasma pressure perturbations and radial convective transport in a tokamak

    International Nuclear Information System (INIS)

    Krasheninnikov, Sergei; Yu, Guanghui; Ryutov, Dmitri

    2004-01-01

    Strongly localized plasma structures with large pressure inhomogeneities (such as plasma blobs in the scrape-off-layer (SOL)/shadow regions, pellet clouds, Edge localized Modes (ELMs)) observed in the tokamaks, stellarators and linear plasma devices. Experimental studies of these phenomena reveal striking similarities including more convective rather than diffusive radial plasma transport. We suggest that rather simple models can describe many essentials of blobs, ELMs, and pellet clouds dynamics. The main ingredient of these models is the effective plasma gravity caused by magnetic curvature, centrifugal or friction forces effects. As a result, the equations governing plasma transport in such localized structures appear to be rather similar to that used to describe nonlinear evolution of thermal convection in the Boussinesq approximation (directly related to the Rayleigh-Taylor (RT) instability). (author)

  13. Nonlinear laser-plasma interactions

    Science.gov (United States)

    Kaw, P. K.

    2017-12-01

    Soon after lasers were invented, there was tremendous curiosity on the nonlinear phenomena which would result in their interaction with a fully ionized plasma. Apart from the basic interest, it was realized that it could be used for the achievement of nuclear fusion in the laboratory. This led us to a paper on the propagation of a laser beam into an inhomogeneous fusion plasma, where it was first demonstrated that light would go up to the critical layer (where the frequency matches the plasma frequency) and get reflected from there with a reflection coefficient of order unity. The reflection coefficient was determined by collisional effects. Since the wave was expected to slow down to near zero group speed at the reflection point, the dominant collision frequency determining the reflection coefficient was the collision frequency at the reflection point. It turned out that the absorption of light was rather small for fusion temperatures. This placed a premium on investigation of nonlinear phenomena which might contribute to the absorption and penetration of the light into high-density plasma. An early investigation showed that electron jitter with respect to ions would be responsible for the excitation of decay instabilities which convert light waves into electrostatic plasma waves and ion waves near the critical frequency. These electrostatic waves would then get absorbed into the plasma even in the collisionless case and lead to plasma heating which is nonlinear. Detailed estimates of this heating were made. Similar nonlinear processes which could lead to stimulated scattering of light in the underdense region (ω >ω _p) were investigated together with a number of other workers. All these nonlinear processes need a critical threshold power for excitation. Another important process which was discovered around the same time had to do with filamentation and trapping of light when certain thresholds were exceeded. All of this work has been extensively verified in

  14. Plasma and Ion Sources in Large Area Coatings: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2005-02-28

    Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Both semiconductortype large area (single wafer or batch processing with {approx} 1000 cm{sup 2}) and in-line web and glass-coating-type large area (> 10{sup 7} m{sup 2} annually) are considered. Characteristics and differences between plasma and ion sources are explained. The latter include gridded and gridless sources. Many examples are given, including sources based on DC, RF, and microwave discharges, some with special geometries like hollow cathodes and E x B configurations.

  15. Raman sidescatter instability in a nonuniform plasma

    International Nuclear Information System (INIS)

    Mostrom, M.A.

    1977-01-01

    In the various laser-fusion concepts, an intense electromagnetic wave (the laser) must propagate through an under-dense plasma region where it could decay, via the stimulated Raman instability, into a Langmuir plasma wave and a scattered electromagnetic wave. This process could, therefore, scatter a significant fraction of the laser energy before it could be deposited in the plasma. A density gradient, in the direction of laser incidence, localizes the instability to a narrow resonance zone where the local plasma wave frequency approximately equals the difference-frequency between the incident and scattered electromagnetic waves. The narrowness of this zone can strongly inhibit the growth of back- or oblique-scattered electromagnetic waves since they quickly propagate out of their resonance region; however, the density gradient has a much weaker effect on side-scattered waves (which propagate perpendicular to the density gradient) since they remain in their resonance zone until refraction bends them out or they exit through the side of the finite diameter laser beam. Thus, we place particular emphasis on evaluating, in a manner valid for the side scattered electromagnetic waves (which are at their turning point), the level of exponentiation at which the growth is linearly saturated due to convection of the waves out of their resonance zone. We also determine the general nature and propagation of the scattered electromagnetic waves and obtain approximate values for the resonance zone size and the time required for the above saturation

  16. Plasma Evolution within an Erupting Coronal Cavity

    Science.gov (United States)

    Long, David M.; Harra, Louise K.; Matthews, Sarah A.; Warren, Harry P.; Lee, Kyoung-Sun; Doschek, George A.; Hara, Hirohisa; Jenkins, Jack M.

    2018-03-01

    Coronal cavities have previously been observed to be associated with long-lived quiescent filaments and are thought to correspond to the associated magnetic flux rope. Although the standard flare model predicts a coronal cavity corresponding to the erupting flux rope, these have only been observed using broadband imaging data, restricting an analysis to the plane-of-sky. We present a unique set of spectroscopic observations of an active region filament seen erupting at the solar limb in the extreme ultraviolet. The cavity erupted and expanded rapidly, with the change in rise phase contemporaneous with an increase in nonthermal electron energy flux of the associated flare. Hot and cool filamentary material was observed to rise with the erupting flux rope, disappearing suddenly as the cavity appeared. Although strongly blueshifted plasma continued to be observed flowing from the apex of the erupting flux rope, this outflow soon ceased. These results indicate that the sudden injection of energy from the flare beneath forced the rapid eruption and expansion of the flux rope, driving strong plasma flows, which resulted in the eruption of an under-dense filamentary flux rope.

  17. Upper Hybrid Resonance of Microwaves with a Large Magnetized Plasma Sheet

    International Nuclear Information System (INIS)

    Huo Wenqing; Guo Shijie; Ding Liang; Xu Yuemin

    2013-01-01

    A large magnetized plasma sheet with size of 60 cm × 60 cm × 2 cm was generated by a linear hollow cathode discharge under the confinement of a uniform magnetic field generated by a Helmholtz Coil. The microwave transmission characteristic of the plasma sheet was measured for different incident frequencies, in cases with the electric field polarization of the incident microwave either perpendicular or parallel to the magnetic field. In this measurement, parameters of the plasma sheet were changed by varying the discharge current and magnetic field intensity. In the experiment, upper hybrid resonance phenomena were observed when the electric field polarization of the incident wave was perpendicular to the magnetic field. These resonance phenomena cannot be found in the case of parallel polarization incidence. This result is consistent with theoretical consideration. According to the resonance condition, the electron density values at the resonance points are calculated under various experimental conditions. This kind of resonance phenomena can be used to develop a specific method to diagnose the electron density of this magnetized plasma sheet apparatus. Moreover, it is pointed out that the operating parameters of the large plasma sheet in practical applications should be selected to keep away from the upper hybrid resonance point to prevent signals from polarization distortion

  18. Investigation of the neutron production phases of a large plasma focus device

    International Nuclear Information System (INIS)

    Hayd, A.; Maurer, M.; Meinke, P.; Herold, H.; Bertalot, L.; Deutsch, R.; Grauf, W.; Jaeger, U.; Kaeppeler, H.J.; Lepper, F.; Oppenlaender, T.; Schmidt, H.; Schmidt, R.; Schwarz, J.; Schwoerer, K.; Shakhatre, M.

    1982-09-01

    Plasma dynamic behavior and neutron production in large focus devices with pinch currents of approximately 1 MA have been studied with theoretical as well as experimental methods. For treating turbulent plasma motion, a hybrid code based on the analytical computer algorithm REDUCE was developed. Experimental diagnostics include schlieren photographs, reaction proton localization with pinhole cameras and neutron measurements with Ag-counters and scintillators. Calculated and measured data concern the 280 kJ, 60 kV operational mode of the POSEIDON plasma focus. It is shown that for large pinch currents ( > 500 kA), neutron emission also appears before m = 0 onset in the intermediate phase. This part of the neutron production becomes predominant for very large currents. The lifetime of this intermediate phase strongly increases with increasing current. According to theory, the late phase of the focus is governed by strong turbulence phenomena. The lifetime of the turbulence packets is approximately 150 ns and seems to explain the long lasting neutron emission in this phase. (orig.)

  19. Spatially and spectrally resolved filamentary structures in the (3/2)omega 0 emission from laser produced plasmas

    International Nuclear Information System (INIS)

    Lin, Z.; Willi, O.; Rumsby, P.T.

    This study was conducted to explore the problem of filamentation of laser light in the underdense plasma corona surrounding ablatively imploded spherical targets, a phenomenon which may prevent the realization of laser-driven fusion schemes. Preliminary observations were made of filamentary structures in the (3/2)(omega sub o) emission from microballoon targets irradiated in the ablative mode. Time integrated spectroscopy showed double and single peaked (3/2)(omega sub o) emission spectra. A simple model for the growth and collapse of filaments was based on the movement of the density contours at the bottom of the filament with large velocity. Here the laser intensity was high and various decay instabilities and scattering processes took place. In particular the two plasmon decay instability occurred where the electron density was nc/4, a region of (3/2)(omega sub o) emission. The model was consistent with the experimentally observed spectra and predicted the type of omega sub o and 2 omega sub o that should be observed in future experiments

  20. Large potential change induced by pellet injection in JIPP T-IIU tokamak plasmas

    International Nuclear Information System (INIS)

    Hamada, Y.; Sato, K.N.; Sakakita, H.

    1995-05-01

    A large, rapid change in the local plasma potential is found to be induced by off-axis hydrogen ice-pellet injection into a tokamak plasma. The polarity of the rapid change is reversed when the pellet is injected into the upper and lower halves of the poloidal plasma cross-section. This change can be interpreted as being due to the gradient-B drift of particles in the high-density plasmas of the pellet cloud, before the increase of the plasma density due to the ablation becomes uniform on the magnetic surface. (author)

  1. Broadband frequency ECR ion source concepts with large resonant plasma volumes

    International Nuclear Information System (INIS)

    Alton, G.D.

    1995-01-01

    New techniques are proposed for enhancing the performances of ECR ion sources. The techniques are based on the use of high-power, variable-frequency, multiple-discrete-frequency, or broadband microwave radiation, derived from standard TWT technology, to effect large resonant ''volume'' ECR sources. The creation of a large ECR plasma ''volume'' permits coupling of more power into the plasma, resulting in the heating of a much larger electron population to higher energies, the effect of which is to produce higher charge state distributions and much higher intensities within a particular charge state than possible in present forms of the ECR ion source. If successful, these developments could significantly impact future accelerator designs and accelerator-based, heavy-ion-research programs by providing multiply-charged ion beams with the energies and intensities required for nuclear physics research from existing ECR ion sources. The methods described in this article can be used to retrofit any ECR ion source predicated on B-minimum plasma confinement techniques

  2. Large amplitude ion-acoustic waves in a plasma with an electron beam

    International Nuclear Information System (INIS)

    Nejoh, Y.; Sanuki, H.

    1995-01-01

    The nonlinear wave structures of large amplitude ion-acoustic waves are studied in a plasma with an electron beam, by the pseudopotential method. The region of the existence of large amplitude ion-acoustic waves is examined, showing that the condition of the existence sensitively depends on the parameters such as the electron beam temperature, the ion temperature, the electrostatic potential, and the concentration of the electron beam density. It turns out that the region of the existence spreads as the beam temperature increases but the effect of the electron beam velocity is relatively small. New findings of large amplitude ion-acoustic waves in a plasma with an electron beam are predicted. copyright 1995 American Institute of Physics

  3. Simulation of intense short-pulse laser-plasma interaction

    International Nuclear Information System (INIS)

    Yamagiwa, Mitsuru

    2000-01-01

    We have completed the massive parallelization of a 2-dimensional giga-particle code and have achieved a 530-fold acceleration rate with 512 processing elements (PE's). Using this we have implemented a simulation of the interaction of a solid thin film and a high intensity laser and have discovered a phenomenon in which high quality short pulses from the far ultraviolet to soft X-rays are generated at the back surface of the thin layer. We have also introduced the atomic process database code (Hullac) and have the possibility for high precision simulations of X-ray laser radiation. With respect to laser acceleration we have the possibility to quantitatively evaluate relativistic self-focusing assumed to occur in higher intensity fields. Ion acceleration from a solid target and an underdense plasma irradiated by an intense and an ultra intense laser, respectively, has also been studied by particle-in-cell (PIC) simulations. (author)

  4. Electro-mechanical probe positioning system for large volume plasma device

    Science.gov (United States)

    Sanyasi, A. K.; Sugandhi, R.; Srivastava, P. K.; Srivastav, Prabhakar; Awasthi, L. M.

    2018-05-01

    An automated electro-mechanical system for the positioning of plasma diagnostics has been designed and implemented in a Large Volume Plasma Device (LVPD). The system consists of 12 electro-mechanical assemblies, which are orchestrated using the Modbus communication protocol on 4-wire RS485 communications to meet the experimental requirements. Each assembly has a lead screw-based mechanical structure, Wilson feed-through-based vacuum interface, bipolar stepper motor, micro-controller-based stepper drive, and optical encoder for online positioning correction of probes. The novelty of the system lies in the orchestration of multiple drives on a single interface, fabrication and installation of the system for a large experimental device like the LVPD, in-house developed software, and adopted architectural practices. The paper discusses the design, description of hardware and software interfaces, and performance results in LVPD.

  5. Formation of large-amplitude dust ion-acoustic shocks in dusty plasmas

    International Nuclear Information System (INIS)

    Eliasson, B.; Shukla, P.K.

    2005-01-01

    Theoretical and numerical studies of self-steepening and shock formation of large-amplitude dust ion-acoustic waves in dusty plasmas are presented. A comparison is made between the nondispersive two fluid model, which predicts the formation of large-amplitude compressive and rarefactive dust ion-acoustic shocks, Vlasov simulations, and recent laboratory experiments

  6. The effect of the novel internal-type linear inductive antenna for large area magnetized inductive plasma source

    Science.gov (United States)

    Lee, S. H.; Shulika, Olga.; Kim, K. N.; Yeom, G. Y.; Lee, J. K.

    2004-09-01

    As the technology of plasma processing progresses, there is a continuing demand for higher plasma density, uniformity over large areas and greater control over plasma parameters to optimize the processes of etching, deposition and surface treatment. Traditionally, the external planar ICP sources with low pressure high density plasma have limited scale-up capabilities due to its high impedance accompanied by the large antenna size. Also due to the cost and thickness of their dielectric material in order to generate uniform plasma. In this study the novel internal-type linear inductive antenna system (1,020mm¡¿830mm¡¿437mm) with permanent magnet arrays are investigated to improve both the plasma density and the uniformity of LAPS (Large Area Plasma Source) for FPD processing. Generally plasma discharges are enhanced because the inductance of the novel antenna (termed as the double comb antenna) is lower than that of the serpentine-type antenna and also the magnetic confinement of electron increases the power absorption efficiency. The uniformity is improved by reducing the standing wave effect. The total length of antenna is comparable to the driving rf wavelength to cause the plasma nonuniformity. To describe the discharge phenomenon we have developed a magnetized two-dimensional fluid simulation. This work was supported by National Research Laboratory (NRL) Program of the Korea Ministry of Science and Technology. [References] 1. J.K.Lee, Lin Meng, Y.K.Shin, H,J,Lee and T.H.Chung, ¡°Modeling and Simulation of a Large-Area Plasma Source¡±, Jpn. J. Appl. Phys. Vol.36(1997) pp. 5714-5723 2. S.E.Park, B.U.Cho, Y.J.Lee*, and G.Y.Yeom*, and J.K.Lee, ¡°The Characteristics of Large Area Processing Plasmas¡±, IEEE Trans. Plasma Sci., Vol.31 ,No.4(2003) pp. 628-637

  7. Behavior of plasma facing surface in the large helical device

    International Nuclear Information System (INIS)

    Hino, T.; Nobuta, Y.; Sagara, A.

    2002-10-01

    Material probes have been installed at the inner walls along poloidal direction in LHD from the first experimental campaign. After each the campaign, the impurity deposition and the gas retention have been examined to clarify the plasma surface interaction and the degree of wall cleaning. In the 2nd campaign, the entire wall was considerably cleaned by helium glow discharge conditionings. For the 3rd and 4th campaigns, graphite tiles were installed at entire divertor strike region, and then the wall condition significantly changed compared to the case of stainless steel wall. The erosion of graphite took place during the main discharges and the eroded carbon deposited on the entire wall. In particular, the deposition thickness was large at the wall far from the plasma. Since the entire wall was well carbonized, amount of retained discharge gas such as H and He became large. In particular, the helium retention was large at the position close to the anodes used for helium glow discharge cleanings. One characteristics of the LHD wall is a large retention of helium gas since the wall temperature is limited below 368 K. In order to reduce the recycling of discharge gas, the wall heating before the experimental campaign and the surface heating between the main discharge shots are planned. (author)

  8. Behavior of plasma facing surface in the large helical device

    International Nuclear Information System (INIS)

    Hino, T.; Nobuta, Y.; Sagara, A.

    2002-01-01

    Material probes have been installed at the inner walls along poloidal direction in LHD from the first experimental campaign. After each campaign, the impurity deposition and the gas retention have been examined to clarify the plasma surface interaction and the degree of wall cleaning. In the 2nd campaign, the entire wall was considerably cleaned by helium glow discharge conditionings. For the 3rd and 4th campaigns, graphite tiles were installed at entire divertor strike region, and then the wall condition significantly changed compared to the case of stainless steel wall. The erosion of graphite took place during the main discharges and the eroded carbon deposited on the entire wall. In particular, the deposition thickness was large at the wall far from the plasma. Since the entire wall was well carbonized, amount of retained discharge gas such as H and He became large. In particular, the helium retention was large at the position close to the anodes used for helium glow discharge cleanings. One characteristics of the LHD wall is a large retention of helium gas since the wall temperature is limited below 368 K. In order to reduce the recycling of discharge gas, the wall heating before the experimental campaign and the surface heating between the main discharge shots are planned. (author)

  9. Behavior of plasma facing surface in the large helical device

    Energy Technology Data Exchange (ETDEWEB)

    Hino, T.; Nobuta, Y. [Hokkaido Univ., Dept. of Nuclear Engineering, Sapporo, Hokkaido (Japan); Sagara, A. [National Inst. for Fusion Science, Toki, Gifu (Japan)] [and others

    2002-11-01

    Material probes have been installed at the inner walls along poloidal direction in LHD from the first experimental campaign. After each campaign, the impurity deposition and the gas retention have been examined to clarify the plasma surface interaction and the degree of wall cleaning. In the 2nd campaign, the entire wall was considerably cleaned by helium glow discharge conditionings. For the 3rd and 4th campaigns, graphite tiles were installed at entire divertor strike region, and then the wall condition significantly changed compared to the case of stainless steel wall. The erosion of graphite took place during the main discharges and the eroded carbon deposited on the entire wall. In particular, the deposition thickness was large at the wall far from the plasma. Since the entire wall was well carbonized, amount of retained discharge gas such as H and He became large. In particular, the helium retention was large at the position close to the anodes used for helium glow discharge cleanings. One characteristics of the LHD wall is a large retention of helium gas since the wall temperature is limited below 368 K. In order to reduce the recycling of discharge gas, the wall heating before the experimental campaign and the surface heating between the main discharge shots are planned. (author)

  10. Experimental studies of laser guiding and wake excitation in plasma channels

    International Nuclear Information System (INIS)

    Volfbeyn, P.; Lawrence Berkeley National Lab., CA

    1998-06-01

    This thesis presents results of experimental investigations of laser guiding in plasma channels. A new technique for plasma channel creation, the Ignitor-Heater scheme was proposed and experimentally tested in hydrogen and nitrogen. It made use of two laser pulses. The Ignitor, an ultrashort ( 17 W/cm 2 , 75fs laser pulse. The guiding properties and transmission and coupling efficiency were studied as a function of relative position of the channel and the injection pulse focus. Whereas entrance coupling efficiency into the channel was lower than expected, channel coupling to continuum losses were found to be in good agreement with analytical predictions. The authors speculate that increased coupling efficiency can be achieved through better mode matching into the channel. Analytic and numerical one dimensional (1-D), nonrelativistic theory of laser pulse propagation in underdense plasma was presented, in the context of laser wakefield acceleration. The relation between the laser pulse energy depletion, longitudinal laser pulse shape distortion, and changes in the group velocity and center wavelength was explored. 1-D theory was extended to treat the case of a laser exciting a wake in a hollow plasma channel, by making use of an energy conservation argument. Based on the results of this theory, a laser wakefield diagnostic was proposed where, by measuring the changes in phase or spectrum of the driving laser pulse, it is possible to infer the amplitude of the plasma wake

  11. Transient magnetized plasma as an optical element for high power laser pulses

    Directory of Open Access Journals (Sweden)

    Nobuhiko Nakanii

    2015-02-01

    Full Text Available Underdense plasma produced in gas jets by low intensity laser prepulses in the presence of a static magnetic field, B∼0.3  T, is shown experimentally to become an optical element allowing steering of tightly focused high power femtosecond laser pulses within several degrees along with essential enhancement of pulse’s focusability. Strong laser prepulses form a density ramp perpendicularly to magnetic field direction and, owing to the light refraction, main laser pulses propagate along the magnetic field even if it is tilted from the laser axis. Electrons generated in the laser pulse wake are well collimated and follow in the direction of the magnetic field; their characteristics are measured to be not sensitive to the tilt of magnetic field up to angles ±5°.

  12. Proton radiography of petawatt-driven channel formation in a plasma gradient

    Science.gov (United States)

    Hill, Matthew; Sircombe, Nathan; Ramsay, Martin; Brown, Colin; Hobbs, Lauren; Allan, Peter; James, Steven; Norreys, Peter; Ratan, Naren; Ceurvorst, Luke

    2015-11-01

    Channel formation by ultra-intense laser pulses in underdense plasmas is a challenging simulation problem with direct relevance to many areas of current research. Recent experiments at the Orion laser facility have used high-energy proton radiography (>40 MeV) driven by a 1 ω petawatt beam to directly probe the interaction of another petawatt beam with a well-characterized plasma density gradient. The interaction plasma was generated using a 3 ω long-pulse beam and diagnosed using a 2 ω optical probe, simultaneously imaged onto four gated optical imagers and two streak cameras. The unique capabilities of the Orion facility allowed a comparison of the channels generated by intense 1 ω (1 μm, 100-500 J, 0.6 ps, 1021 W/cm2, f/3 parabola) and 2 ω (0.5 μm, 100 J, 0.6 ps, 1020 W/cm2, f/6 parabola) pulses. Proton radiographs of these channels are presented along with PIC simulations performed using the EPOCH code, supported by K- α measurements of hot electron beam divergence and magnetic spectrometer data. Together these provide a solid foundation for improvements to hydrodynamic and PIC simulations, further developing the predictive capabilities required to optimize future experiments.

  13. Purification of a large molecular weight transglutaminase substrate from liver plasma membranes

    International Nuclear Information System (INIS)

    Slife, C.W.; Morris, G.S.; Tyrrell, D.J.

    1986-01-01

    Transglutaminases are enzymes which catalyze the covalent crosslinking of proteins by forming epsilon(γ-glutamyl)lysine isopeptide linkages. In earlier studies, the authors reported that a large molecular weight protein aggregate in rat liver plasma membranes served as a substrate for a plasma membrane-associated transglutaminase. The enzyme specifically incorporated a lysine analog, [ 3 H]putrescine, into a protein complex which remained at the top of an acrylamide gel upon electrophoresis in SDS and reducing agents. The complex has now been isolated by extracting the plasma membranes with detergent (octylglucoside) resuspending the detergent insoluble residues in 6 M guanidine HCl and chromatographing the residue on a 4% agarose column in 6 M guanidine HCl. Most of the radioactivity is found in the void volume fractions from the column. SDS polyacrylamide gel electrophoresis shows that these fractions contain mostly proteins that do not enter the acrylamide gel. Since this purification procedure is essentially the same as that used to isolate a rat hepatocyte adhesion factor from rat liver plasma membranes it is possible that the large molecular weight transglutaminase substrate and the adhesion factor are contained in the same protein aggregate

  14. Behavior of plasma facing surfaces in the large helical device

    International Nuclear Information System (INIS)

    Hino, T.; Nobuta, Y.; Sagara, A.

    2003-01-01

    Material probes have been installed at the inner walls along the poloidal direction in LHD from the first experimental campaign. After each campaign, the impurity deposition and the gas retention have been examined to clarify the plasma surface interaction and the degree of wall cleaning. In the 2nd campaign, the entire wall was thoroughly cleaned by helium glow discharge conditioning. For the 3rd and 4th campaigns, graphite tiles were installed over the entire divertor strike region, and then the wall condition was significantly changed compared to the case of a stainless steel wall. Graphite erosion took place during the main discharges and the eroded carbon was deposited on the entire wall. In particular, the deposition thickness was large at the wall far from the plasma. Since the entire wall was well carbonized, the amount of retained discharge gases such as H and He became large. In particular, the helium retention was large at the position close to the anodes used for helium glow discharge cleanings. One characteristic of the LHD wall is a large retention of helium gas since the wall temperature is limited to below 368 K. In order to reduce the recycling of discharge gas, wall heating before the experimental campaign and surface heating between the main discharge shots are planned. (author)

  15. Relativistic effects on large amplitude nonlinear Langmuir waves in a two-fluid plasma

    International Nuclear Information System (INIS)

    Nejoh, Yasunori

    1994-07-01

    Large amplitude relativistic nonlinear Langmuir waves are analyzed by the pseudo-potential method. The existence conditions for nonlinear Langmuir waves are confirmed by considering relativistic high-speed electrons in a two-fluid plasma. The significant feature of this investigation is that the propagation of nonlinear Langmuir waves depends on the ratio of the electron streaming velocity to the velocity of light, the normalized potential and the ion mass to electron mass ratio. The constant energy is determined by the specific range of the relativistic effect. In the non-relativistic limit, large amplitude relativistic Langmuir waves do not exist. The present investigation predicts new findings of large amplitude nonlinear Langmuir waves in space plasma phenomena in which relativistic electrons are important. (author)

  16. Process automation system for integration and operation of Large Volume Plasma Device

    International Nuclear Information System (INIS)

    Sugandhi, R.; Srivastava, P.K.; Sanyasi, A.K.; Srivastav, Prabhakar; Awasthi, L.M.; Mattoo, S.K.

    2016-01-01

    Highlights: • Analysis and design of process automation system for Large Volume Plasma Device (LVPD). • Data flow modeling for process model development. • Modbus based data communication and interfacing. • Interface software development for subsystem control in LabVIEW. - Abstract: Large Volume Plasma Device (LVPD) has been successfully contributing towards understanding of the plasma turbulence driven by Electron Temperature Gradient (ETG), considered as a major contributor for the plasma loss in the fusion devices. Large size of the device imposes certain difficulties in the operation, such as access of the diagnostics, manual control of subsystems and large number of signals monitoring etc. To achieve integrated operation of the machine, automation is essential for the enhanced performance and operational efficiency. Recently, the machine is undergoing major upgradation for the new physics experiments. The new operation and control system consists of following: (1) PXIe based fast data acquisition system for the equipped diagnostics; (2) Modbus based Process Automation System (PAS) for the subsystem controls and (3) Data Utilization System (DUS) for efficient storage, processing and retrieval of the acquired data. In the ongoing development, data flow model of the machine’s operation has been developed. As a proof of concept, following two subsystems have been successfully integrated: (1) Filament Power Supply (FPS) for the heating of W- filaments based plasma source and (2) Probe Positioning System (PPS) for control of 12 number of linear probe drives for a travel length of 100 cm. The process model of the vacuum production system has been prepared and validated against acquired pressure data. In the next upgrade, all the subsystems of the machine will be integrated in a systematic manner. The automation backbone is based on 4-wire multi-drop serial interface (RS485) using Modbus communication protocol. Software is developed on LabVIEW platform using

  17. Process automation system for integration and operation of Large Volume Plasma Device

    Energy Technology Data Exchange (ETDEWEB)

    Sugandhi, R., E-mail: ritesh@ipr.res.in; Srivastava, P.K.; Sanyasi, A.K.; Srivastav, Prabhakar; Awasthi, L.M.; Mattoo, S.K.

    2016-11-15

    Highlights: • Analysis and design of process automation system for Large Volume Plasma Device (LVPD). • Data flow modeling for process model development. • Modbus based data communication and interfacing. • Interface software development for subsystem control in LabVIEW. - Abstract: Large Volume Plasma Device (LVPD) has been successfully contributing towards understanding of the plasma turbulence driven by Electron Temperature Gradient (ETG), considered as a major contributor for the plasma loss in the fusion devices. Large size of the device imposes certain difficulties in the operation, such as access of the diagnostics, manual control of subsystems and large number of signals monitoring etc. To achieve integrated operation of the machine, automation is essential for the enhanced performance and operational efficiency. Recently, the machine is undergoing major upgradation for the new physics experiments. The new operation and control system consists of following: (1) PXIe based fast data acquisition system for the equipped diagnostics; (2) Modbus based Process Automation System (PAS) for the subsystem controls and (3) Data Utilization System (DUS) for efficient storage, processing and retrieval of the acquired data. In the ongoing development, data flow model of the machine’s operation has been developed. As a proof of concept, following two subsystems have been successfully integrated: (1) Filament Power Supply (FPS) for the heating of W- filaments based plasma source and (2) Probe Positioning System (PPS) for control of 12 number of linear probe drives for a travel length of 100 cm. The process model of the vacuum production system has been prepared and validated against acquired pressure data. In the next upgrade, all the subsystems of the machine will be integrated in a systematic manner. The automation backbone is based on 4-wire multi-drop serial interface (RS485) using Modbus communication protocol. Software is developed on LabVIEW platform using

  18. Electron acceleration in laser-plasma interaction: development and characterization of an optical injector

    International Nuclear Information System (INIS)

    Rechatin, C.

    2009-09-01

    In any particle accelerator, the injector plays a crucial role since it determines most of the characteristics of the accelerated beam. This is also true for laser-plasma accelerators, that are based on the interaction of an ultra short, ultra intense laser with an underdense plasma. However, due to the compactness of these accelerators, injection is a real challenge: to obtain a good beam quality, injected electron beams have to be ultra short and precisely synchronized with the laser. In this manuscript, the relevance of an optical injector, that relies on a second laser pulse, is experimentally demonstrated. With this injector, mono energetic electron beams have been produced in a stable manner. Moreover, this injector gives control over the electron beam parameters. Using the parameters of the second laser pulse, it has been proven that the energy, the charge and the energy spread of the accelerated beam can be simply tuned. Those additional controls make it possible to study in great details the physical phenomena at play during the acceleration. Beam loading effects, due to the interaction of the accelerated bunch with the plasma, have been identified and studied. With optimized injector parameters, the narrowest electron beams measured to date in the laser plasma interaction have been obtained, with a relative energy spread of 1%. (author)

  19. Periodic long-range transport in a large volume dc glow discharge dusty plasma

    International Nuclear Information System (INIS)

    Thomas, Edward Jr.; Amatucci, William E.; Compton, Christopher; Christy, Brian; Jackson, Jon David

    2003-01-01

    In an earlier paper, the authors reported on observations of a variety of particle transport phenomena observed in DUPLEX--the DUsty PLasma EXperiment at the Naval Research Laboratory [E. Thomas, Jr., W. E. Amatucci, C. Compton, and B. Christy, Phys. Plasmas 9, 3154 (2002)]. DUPLEX is a large, transparent polycarbonate cylinder that is 40 cm in radius and 80 cm in height. dc glow discharge argon plasmas are generated in DUPLEX. In this paper, the authors expand upon one particular feature of particle transport in DUPLEX, the long-range (i.e., greater than 15 cm), periodic (T∼2.5 min) transport of suspended alumina particles through the plasma. A detailed description of this particle motion through the plasma is presented. Finally, a qualitative model describing the phenomena that lead to this transport is also given

  20. Laser scattering in large-scale-length plasmas relevant to National Ignition Facility hohlraums

    International Nuclear Information System (INIS)

    MacGowan, B.J.; Berger, R.L.; Afeyan, B.B.

    1996-10-01

    We have used homogeneous plasmas of high density (up to 1.3 X 10 21 electrons per cm 3 ) and temperature (∼ 3 keV) with large density scale lengths (∼2 mm) to approximate conditions within National Ignition Facility (NIF) hohlraums. Within these plasmas we have studied the dependence of stimulated Raman (SRS) and Brillouin (SBS) scattering on beam smoothing and plasma conditions at the relevant laser intensity (3ω, 2 X 10 15 Wcm 2 ). Both SBS and SRS are reduced by the use of smoothing by spectral dispersion (SSD)

  1. Plasma turbulence driven by transversely large-scale standing shear Alfvén waves

    International Nuclear Information System (INIS)

    Singh, Nagendra; Rao, Sathyanarayan

    2012-01-01

    Using two-dimensional particle-in-cell simulations, we study generation of turbulence consisting of transversely small-scale dispersive Alfvén and electrostatic waves when plasma is driven by a large-scale standing shear Alfvén wave (LS-SAW). The standing wave is set up by reflecting a propagating LS-SAW. The ponderomotive force of the standing wave generates transversely large-scale density modifications consisting of density cavities and enhancements. The drifts of the charged particles driven by the ponderomotive force and those directly caused by the fields of the standing LS-SAW generate non-thermal features in the plasma. Parametric instabilities driven by the inherent plasma nonlinearities associated with the LS-SAW in combination with the non-thermal features generate small-scale electromagnetic and electrostatic waves, yielding a broad frequency spectrum ranging from below the source frequency of the LS-SAW to ion cyclotron and lower hybrid frequencies and beyond. The power spectrum of the turbulence has peaks at distinct perpendicular wave numbers (k ⊥ ) lying in the range d e −1 -6d e −1 , d e being the electron inertial length, suggesting non-local parametric decay from small to large k ⊥ . The turbulence spectrum encompassing both electromagnetic and electrostatic fluctuations is also broadband in parallel wave number (k || ). In a standing-wave supported density cavity, the ratio of the perpendicular electric to magnetic field amplitude is R(k ⊥ ) = |E ⊥ (k ⊥ )/|B ⊥ (k ⊥ )| ≪ V A for k ⊥ d e A is the Alfvén velocity. The characteristic features of the broadband plasma turbulence are compared with those available from satellite observations in space plasmas.

  2. From laser-plasma accelerators to femtosecond X-ray sources: study, development and applications

    International Nuclear Information System (INIS)

    Corde, S.

    2012-01-01

    During the relativistic interaction between a short and intense laser pulse and an underdense plasma, electrons can be injected and accelerated up to hundreds of MeV in an accelerating structure formed in the wake of the pulse: this is the so-called laser-plasma accelerator. One of the major perspectives for laser-plasma accelerators resides in the realization of compact sources of femtosecond x-ray beams. In this thesis, two x-ray sources was studied and developed. The betatron radiation, intrinsic to laser-plasma accelerators, comes from the transverse oscillations of electrons during their acceleration. Its characterization by photon counting revealed an x-ray beam containing 10"9 photons, with energies extending above 10 keV. We also developed an all-optical Compton source producing photons with energies up to hundreds of keV, based on the collision between a photon beam and an electron beam. The potential of these x-ray sources was highlighted by the realization of single shot phase contrast imaging of a biological sample. Then, we showed that the betatron x-ray radiation can be a powerful tool to study the physics of laser-plasma acceleration. We demonstrated the possibility to map the x-ray emission region, which gives a unique insight into the interaction, permitting us for example to locate the region where electrons are injected. The x-ray angular and spectral properties allow us to gain information on the transverse dynamics of electrons during their acceleration. (author)

  3. Growth of large patterned arrays of neurons using plasma methods

    International Nuclear Information System (INIS)

    Brown, I G; Bjornstad, K A; Blakely, E A; Galvin, J E; Monteiro, O R; Sangyuenyongpipat, S

    2003-01-01

    To understand how large systems of neurons communicate, we need to develop, among other things, methods for growing patterned networks of large numbers of neurons. Success with this challenge will be important to our understanding of how the brain works, as well as to the development of novel kinds of computer architecture that may parallel the organization of the brain. We have investigated the use of metal ion implantation using a vacuum-arc ion source, and plasma deposition with a filtered vacuum-arc system, as a means of forming regions of selective neuronal attachment on surfaces. Lithographic patterns created by the treating surface with ion species that enhance or inhibit neuronal cell attachment allow subsequent proliferation and/or differentiation of the neurons to form desired patterned neural arrays. In the work described here, we used glass microscope slides as substrates, and some of the experiments made use of simple masks to form patterns of ion beam or plasma deposition treated regions. PC-12 rat neurons were then cultured on the treated substrates coated with Type I Collagen, and the growth and differentiation was monitored. Particularly good selective growth was obtained using plasma deposition of diamond-like carbon films of about one hundred Angstroms thickness. Neuron proliferation and the elaboration of dendrites and axons after the addition of nerve growth factor both showed excellent contrast, with prolific growth and differentiation on the treated surfaces and very low growth on the untreated surfaces

  4. Growth of large patterned arrays of neurons using plasma methods

    Energy Technology Data Exchange (ETDEWEB)

    Brown, I G; Bjornstad, K A; Blakely, E A; Galvin, J E; Monteiro, O R; Sangyuenyongpipat, S [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2003-05-01

    To understand how large systems of neurons communicate, we need to develop, among other things, methods for growing patterned networks of large numbers of neurons. Success with this challenge will be important to our understanding of how the brain works, as well as to the development of novel kinds of computer architecture that may parallel the organization of the brain. We have investigated the use of metal ion implantation using a vacuum-arc ion source, and plasma deposition with a filtered vacuum-arc system, as a means of forming regions of selective neuronal attachment on surfaces. Lithographic patterns created by the treating surface with ion species that enhance or inhibit neuronal cell attachment allow subsequent proliferation and/or differentiation of the neurons to form desired patterned neural arrays. In the work described here, we used glass microscope slides as substrates, and some of the experiments made use of simple masks to form patterns of ion beam or plasma deposition treated regions. PC-12 rat neurons were then cultured on the treated substrates coated with Type I Collagen, and the growth and differentiation was monitored. Particularly good selective growth was obtained using plasma deposition of diamond-like carbon films of about one hundred Angstroms thickness. Neuron proliferation and the elaboration of dendrites and axons after the addition of nerve growth factor both showed excellent contrast, with prolific growth and differentiation on the treated surfaces and very low growth on the untreated surfaces.

  5. Three-dimensional two-fluid Braginskii simulations of the large plasma device

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Dustin M., E-mail: dustin.m.fisher.gr@dartmouth.edu; Rogers, Barrett N., E-mail: barrett.rogers@dartmouth.edu [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Rossi, Giovanni D.; Guice, Daniel S.; Carter, Troy A. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)

    2015-09-15

    The Large Plasma Device (LAPD) is modeled using the 3D Global Braginskii Solver code. Comparisons to experimental measurements are made in the low-bias regime in which there is an intrinsic E × B rotation of the plasma. In the simulations, this rotation is caused primarily by sheath effects and may be a likely mechanism for the intrinsic rotation seen in LAPD. Simulations show strong qualitative agreement with the data, particularly the radial dependence of the density fluctuations, cross-correlation lengths, radial flux dependence outside of the cathode edge, and camera imagery. Kelvin Helmholtz (KH) turbulence at relatively large scales is the dominant driver of cross-field transport in these simulations with smaller-scale drift waves and sheath modes playing a secondary role. Plasma holes and blobs arising from KH vortices in the simulations are consistent with the scale sizes and overall appearance of those in LAPD camera images. The addition of ion-neutral collisions in the simulations at previously theorized values reduces the radial particle flux by about a factor of two, from values that are somewhat larger than the experimentally measured flux to values that are somewhat lower than the measurements. This reduction is due to a modest stabilizing contribution of the collisions on the KH-modes driving the turbulent transport.

  6. Effect of air gap on uniformity of large-scale surface-wave plasma

    International Nuclear Information System (INIS)

    Lan Chaohui; Hu Xiwei; Jiang Zhonghe; Liu Minghai

    2009-01-01

    The effect of air gap on the uniformity of large-scale surface-wave plasma (SWP) in a rectangular chamber device is studied by using three-dimensional numerical analyses based on the finite difference time-domain (FDTD) approximation to Maxwell's equations and plasma fluid model. The spatial distributions of surface wave excited by slot-antenna array and the plasma parameters such as electron density and temperature are presented. For different air gap thicknesses, the results show that the existence of air gap would severely weaken the excitations of the surface wave and thereby the SWP. Thus the air gap should be eliminated completely in the design of the SWP source, which is opposite to the former research results. (authors)

  7. Generation of a single hot spot by use of a deformable mirror and study of its propagation in an underdense plasma

    International Nuclear Information System (INIS)

    Wattellier, Benoit; Fuchs, Julien; Zou Jiping; Chanteloup, Jean-Christophe; Bandulet, Heidi; Michel, Pierre; Labaune, Christine; Depierreux, Sylvie; Kudryashov, Alexis; Aleksandrov, Alexander

    2003-01-01

    Adaptive optics systems offer the prospect of significantly increasing the capabilities of high-power laser focusability, which is currently limited by thermal distortions. Using novel wave-front measurement techniques that improve the stability of such systems and a downstream large-aperture deformable mirror that does not bear the usual limitations associated with precompensation, we have improved the focusability of a high-power (6x100-J, 1-ns) Nd:glass laser facility by a factor of 6. Measuring the wave front and the on-target focal spot at full power, we obtained after correction focal spots with a best Strehl ratio of 0.6. The pulse peak intensity could thus be increased to ∼2x10 16 W/cm 2 , a level beyond reach of the usual focal spot shaping techniques. We then used the near-diffraction-limited focal spots produced by this system to measure the laser-plasma coupling for a single, controlled filament of light and to underline the importance of the coupling among the numerous speckles within conventional multispeckled beams

  8. Heat and momentum transport of ion internal transport barrier plasmas on Large Helical Device

    International Nuclear Information System (INIS)

    Nagaoka, K.; Ida, K.; Yoshinuma, M.

    2010-11-01

    The peaked ion-temperature profile with steep gradient so called ion internal transport barrier (ion ITB) was formed in the neutral beam heated plasmas on the Large Helical Device (LHD) and the high-ion-temperature regime of helical plasmas has been significantly extended. The ion thermal diffusivity in the ion ITB plasma decreases down to the neoclassical transport level. The heavy ion beam probe (HIBP) observed the smooth potential profile with negative radial electric field (ion root) in the core region where the ion thermal diffusivity decreases significantly. The large toroidal rotation was also observed in the ion ITB core and the transport of toroidal momentum was analyzed qualitatively. The decrease of momentum diffusivity with ion temperature increase was observed in the ion ITB core. The toroidal rotation driven by ion temperature gradient so called intrinsic rotation is also identified. (author)

  9. Interaction of Intense Lasers with Plasmas

    Science.gov (United States)

    Shvets, Gennady

    1995-01-01

    This thesis addresses two important topics in nonlinear laser plasma physics: the interaction of intense lasers with a non thermal homogeneous plasma, the excitation of laser wakefields in hollow plasma channels, and the stability of channel guided propagation of laser pulses. In the first half of this thesis a new theoretical approach to the nonlinear interaction of intense laser pulses with underdense plasmas is developed. Unlike previous treatments, this theory is three-dimensional, relativistically covariant, and does not assume that astudied. An experimental check of this calculation is suggested, based on the predicted non-linear polarization rotation (the second harmonic is emitted polarized perpendicularly to polarization of the incident signal). The concept of renormalization is applied to the plasma and electromagnetic radiation (photons and plasmons). To the lowest order, this corresponds to relativistically correcting the electron mass for its oscillation in an intense EM field and to replacing the vacuum dispersion relation by the usual relativistic plasma dispersion relation. This renormalization procedure is then carried to higher order in epsilon=omega_sp{p} {2}a^2/[(1+a^2/2)^ {3/2}omega^2]. This yields the nonlinear modification of the index of refraction of a strong electromagnetic wave and the dispersion of a weak probe in the presence of the wave. In the second part of this thesis the stability of short laser pulses propagating through parabolic channels and the wake excitation of hollow plasma channels are studied. The stability of a channel guided short laser pulse propagation is analyzed for the first time. Perturbations to the laser pulse are shown to modify the ponderomotive pressure, which distorts the dielectric properties of the plasma channel. The channel perturbation then further distorts the laser pulse. A set of coupled mode equations is derived, and a matrix dispersion relation is obtained analytically. The ponderomotive excitation

  10. Large density amplification measured on jets ejected from a magnetized plasma gun

    OpenAIRE

    Yun, Gunsu S.; You, Setthivoine; Bellan, Paul M.

    2007-01-01

    Observation of a large density amplification in the collimating plasma jet ejected from a coplanar coaxial plasma gun is reported. The jet velocity is ~30 km s^-1 and the electron density increases from ~10^20 to 10^(22–23) m^-3. In previous spheromak experiments, electron density of the order 10^(19–21) m^-3 had been measured in the flux conserver region, but no density measurement had been reported for the source gun region. The coplanar geometry of our electrodes permits direct observation...

  11. Large-amplitude double layers in a dusty plasma with an arbitrary ...

    Indian Academy of Sciences (India)

    Formation of large-amplitude double layers in a dusty plasma whose constituents are electrons, ions, warm dust grains and positive ion beam are studied using Sagdeev's pseudopotential technique. Existence of double layers is investigated. It is found that both the temperature of dust particles and ion beam temperature ...

  12. Large area ion and plasma beam sources

    Energy Technology Data Exchange (ETDEWEB)

    Waldorf, J. [IPT Ionen- und Plasmatech. GmbH, Kaiserslautern (Germany)

    1996-06-01

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

  13. Large area ion and plasma beam sources

    International Nuclear Information System (INIS)

    Waldorf, J.

    1996-01-01

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

  14. High density high performance plasma with internal diffusion barrier in Large Helical Device

    International Nuclear Information System (INIS)

    Sakamoto, R.; Kobayashi, M.; Miyazawa, J.

    2008-10-01

    A attractive high density plasma operational regime, namely an internal diffusion barrier (IDB), has been discovered in the intrinsic helical divertor configuration on the Large Helical Device (LHD). The IDB which enables core plasma to access a high density/high pressure regime has been developed. It is revealed that the IDB is reproducibly formed by pellet fueling in the magnetic configurations shifted outward in major radius. Attainable central plasma density exceeds 1x10 21 m -3 . Central pressure reaches 1.5 times atmospheric pressure and the central β value becomes fairly high even at high magnetic field, i.e. β(0)=5.5% at B t =2.57 T. (author)

  15. HIV diversity and drug resistance from plasma and non-plasma analytes in a large treatment programme in western Kenya.

    Science.gov (United States)

    Kantor, Rami; DeLong, Allison; Balamane, Maya; Schreier, Leeann; Lloyd, Robert M; Injera, Wilfred; Kamle, Lydia; Mambo, Fidelis; Muyonga, Sarah; Katzenstein, David; Hogan, Joseph; Buziba, Nathan; Diero, Lameck

    2014-01-01

    -STP discordances, one mutation was identified in plasma and 22 in STP (p<0.05). Discordance was inversely significantly related to VL for DBS. In a large treatment programme in western Kenya, we report high HIV-1 subtype diversity; low plasma transmitted resistance, increasing when multiple analytes were combined; and high-acquired resistance with unique mutation patterns. Resistance surveillance may be augmented by using non-plasma analytes for lower-cost genotyping in resource-limited settings.

  16. Pulse power requirements for large aperture optical switches based on plasma electrode Pockels cells

    International Nuclear Information System (INIS)

    Rhodes, M.A.; Taylor, J.

    1992-06-01

    We discuss very large-aperture optical switches (greater than 30 x 30 cm) as an enabling technology for inertial confinement fusion drivers based on multipass laser amplifiers. Large-scale laser fusion drivers such as the Nova laser have been based on single-pass amplifier designs in part because of the unavailability of a suitable large-aperture switch. We are developing an optical switch based on a Pockels cell employing plasma-electrodes. A plasma-electrode Pockels cell (PEPC) is a longitudinal-mode Pockels cell in which a plasma discharge is formed on each side of an electro-optic crystal (typically KDP or deuterated KDP, often designated KD*P). The plasmas formed on either side of the crystal act as transparent electrodes for a switching-pulse and are intended to allow uniform charging of the entire crystal. The switching-pulse is a nominally rectangular high-voltage pulse equal to the half-wave voltage V x ( 8 kV for KD*P or 17 kV for KDP) and is applied across the crystal via the plasma-electrodes. When the crystal is charged to V x , the polarization of an incoming, linearly polarized, laser beam is rotated by 90 degree. When used in conjunction with an appropriate, passive polarizer, an optical switch is thus realized. A switch with a clear aperture of 37 x 37 cm is now in construction for the Beamlet laser which will serve as a test bed for this switch as well as other technologies required for an advanced NOVA laser design. In this paper, we discuss the unique power electronics requirements of PEPC optical switches

  17. Suppression of fast electron leakage from large openings in a plasma neutralizer for N-NB systems

    International Nuclear Information System (INIS)

    Kashiwagi, Mieko; Hanada, Masaya; Yamana, Takashi; Inoue, Takashi; Imai, Tsuyoshi; Taniguchi, Masaki; Watanabe, Kazuhiro

    2006-01-01

    To produce highly ionized plasmas at low operating pressure in a plasma neutralizer of negative ion based neutral beam (N-NB) systems, it is a critical issue to suppress leakage of fast electrons through large openings as the beam entrance/exit. The authors propose to form weak transverse magnetic fields without a significant beam deflection, called the shield field, across the large openings of the neutralizer. A numerical study showed that the shield field of only few tens of Gauss is sufficient to suppress the fast electron leakage from the openings. By measuring of an electron energy distribution function (EEDF), it was confirmed that such a weak magnetic field is enough to repel the fast electrons back into the neutralizer plasma. As the result, the plasma density increased with the shield field strength and saturated at 30 G. The plasma density reached 50% higher value than that without the shield field. Thus it was found that reflected fast electrons by the shield field of only 30 G work effectively for the plasma generation. It was also estimated that such a weak magnetic field sufficiently suppresses the deflection of a 1 MeV beam. This weak magnetic field would be applicable to the plasma neutralizer for the fusion demonstration (DEMO) plant

  18. Large-solid-angle illuminators for extreme ultraviolet lithography with laser plasmas

    International Nuclear Information System (INIS)

    Kubiak, G.D.; Tichenor, D.A.; Sweatt, W.C.; Chow, W.W.

    1995-06-01

    Laser Plasma Sources (LPSS) of extreme ultraviolet radiation are an attractive alternative to synchrotron radiation sources for extreme ultraviolet lithography (EUVL) due to their modularity, brightness, and modest size and cost. To fully exploit the extreme ultraviolet power emitted by such sources, it is necessary to capture the largest possible fraction of the source emission half-sphere while simultaneously optimizing the illumination stationarity and uniformity on the object mask. In this LDRD project, laser plasma source illumination systems for EUVL have been designed and then theoretically and experimentally characterized. Ellipsoidal condensers have been found to be simple yet extremely efficient condensers for small-field EUVL imaging systems. The effects of aberrations in such condensers on extreme ultraviolet (EUV) imaging have been studied with physical optics modeling. Lastly, the design of an efficient large-solid-angle condenser has been completed. It collects 50% of the available laser plasma source power at 14 nm and delivers it properly to the object mask in a wide-arc-field camera

  19. Large-scale production and properties of human plasma-derived activated Factor VII concentrate.

    Science.gov (United States)

    Tomokiyo, K; Yano, H; Imamura, M; Nakano, Y; Nakagaki, T; Ogata, Y; Terano, T; Miyamoto, S; Funatsu, A

    2003-01-01

    An activated Factor VII (FVIIa) concentrate, prepared from human plasma on a large scale, has to date not been available for clinical use for haemophiliacs with antibodies against FVIII and FIX. In the present study, we attempted to establish a large-scale manufacturing process to obtain plasma-derived FVIIa concentrate with high recovery and safety, and to characterize its biochemical and biological properties. FVII was purified from human cryoprecipitate-poor plasma, by a combination of anion exchange and immunoaffinity chromatography, using Ca2+-dependent anti-FVII monoclonal antibody. To activate FVII, a FVII preparation that was nanofiltered using a Bemberg Microporous Membrane-15 nm was partially converted to FVIIa by autoactivation on an anion-exchange resin. The residual FVII in the FVII and FVIIa mixture was completely activated by further incubating the mixture in the presence of Ca2+ for 18 h at 10 degrees C, without any additional activators. For preparation of the FVIIa concentrate, after dialysis of FVIIa against 20 mm citrate, pH 6.9, containing 13 mm glycine and 240 mm NaCl, the FVIIa preparation was supplemented with 2.5% human albumin (which was first pasteurized at 60 degrees C for 10 h) and lyophilized in vials. To inactivate viruses contaminating the FVIIa concentrate, the lyophilized product was further heated at 65 degrees C for 96 h in a water bath. Total recovery of FVII from 15 000 l of plasma was approximately 40%, and the FVII preparation was fully converted to FVIIa with trace amounts of degraded products (FVIIabeta and FVIIagamma). The specific activity of the FVIIa was approximately 40 U/ micro g. Furthermore, virus-spiking tests demonstrated that immunoaffinity chromatography, nanofiltration and dry-heating effectively removed and inactivated the spiked viruses in the FVIIa. These results indicated that the FVIIa concentrate had both high specific activity and safety. We established a large-scale manufacturing process of human plasma

  20. Plasma processing of large curved surfaces for superconducting rf cavity modification

    Directory of Open Access Journals (Sweden)

    J. Upadhyay

    2014-12-01

    Full Text Available Plasma-based surface modification of niobium is a promising alternative to wet etching of superconducting radio frequency (SRF cavities. We have demonstrated surface layer removal in an asymmetric nonplanar geometry, using a simple cylindrical cavity. The etching rate is highly correlated with the shape of the inner electrode, radio-frequency (rf circuit elements, gas pressure, rf power, chlorine concentration in the Cl_{2}/Ar gas mixtures, residence time of reactive species, and temperature of the cavity. Using variable radius cylindrical electrodes, large-surface ring-shaped samples, and dc bias in the external circuit, we have measured substantial average etching rates and outlined the possibility of optimizing plasma properties with respect to maximum surface processing effect.

  1. Simple emittance measurement of H- beams from a large plasma source

    International Nuclear Information System (INIS)

    Guharay, S.K.; Tsumori, K.; Hamabe, M.; Takeiri, Y.; Kaneko, O.; Kuroda, T.

    1996-03-01

    An emittance meter is developed using pepper-pot method. Kapton foils are used to detect intensity distributions of small beamlets at the 'image' plane of the pepper-pot. Emittance of H - beams from a large plasma source for the neutral beam injector of the Large Helical Device (LHD) has been measured. The normalized emittance (95%) of a 6 mA H - beam with emission current density of about 10 mA/cm 2 is ∼0.59 mm mrad. The present system is very simple, and it eliminates many complexities of the existing schemes. (author)

  2. Large-scale interaction of the solar wind with cometary plasma tails

    International Nuclear Information System (INIS)

    Niedner, M.B. Jr.

    1979-01-01

    The study of the behavior of plasma tails in the context of their interaction with the solar wind could have important implications for the structure of the interplanetary medium in three dimensions. Comet Kohoutek 1973f exhibited a broad range of plasma tail behavior. On 1974 January 20, the tail was in a highly disturbed condition. Comet Kohoutek was encountering the leading edge of a very strong high-speed stream at the time the plasma tail disturbance started to develop. Comparison of the observed tail geometry on January 20 with the theoretical position angles generated from the wind sock theory of plasma tails and the corotated satellite observations shows that the tail disturbance was probably caused by large gradients of the polar component of the solar-wind velocity. Within hours after the disturbance of January 20, the plasma tail of comet Kohoutek became disconnected from the cometary head, and was replaced by a new plasma tail. The comet was very near an interplanetary sector boundary at the time of disconnection. The disconnection event (DE) is suggested to have resulted from the magnetic reconnection of plasma tail field lines. A similar analysis of other DEs found in original plate material and in published photographs shows the most DEs occur near corotated sector boundaries. Thus, the sector boundary model is further supported, and the finding provides the only known method of probing sector structure to high latitudes. Sector boundaries can often extend to high latitudes in a nearly North-South orientation, and this property is not restricted to times away from solar minimum. Furthermore, the boundaries are inferred to be randomly tilted with respect to the polarity sequence across the boundary and to the magnetic signs of the solar poles

  3. High-intensity subpicosecond laser pulse propagation in a 1-cm capillary tube and fast ignitor experiments

    International Nuclear Information System (INIS)

    Malka, G.; Courtois, C.; Cros, B.; Matthieussent, G.; Borghesi, M.; Gaillard, R.; Mackinnon, A.J.; Willi, O.; Danson, C.; Neely, D.; Altenberd, D.; Feurer, T.; Forster, E.; Gibbon, P.; Sauerbray, R.; Teubner, U.; Theobald, W.; Uschmann, I.; Amiranoff, F.; Baton, S.; Gremillet, L.; Fuchs, J.; Marques, J.R.; Gallant, P.; Kieffer, J.C.; Pepin, H.; Adam, J.C.; Heron, A.; Laval, G.; Mora, P.

    2000-01-01

    We present an abstract of ultra short and intense laser plasma interaction experiments which were performed with the 100 TW P102 laser facility at CEA/Limeil-Valenton. Laser interaction at relativistic regime (I>10 18 W/cm 2 ) has been investigated with different 'targets': overdense plasma, underdense plasma, free electrons and capillary tube. These experiments are of great interests for the Fast Ignitor concept and the Laser Particle Accelerator. (authors)

  4. The Large-scale Effect of Environment on Galactic Conformity

    Science.gov (United States)

    Sun, Shuangpeng; Guo, Qi; Wang, Lan; Wang, Jie; Gao, Liang; Lacey, Cedric G.; Pan, Jun

    2018-04-01

    We use a volume-limited galaxy sample from the SDSS Data Release 7 to explore the dependence of galactic conformity on the large-scale environment, measured on ˜ 4 Mpc scales. We find that the star formation activity of neighbour galaxies depends more strongly on the environment than on the activity of their primary galaxies. In under-dense regions most neighbour galaxies tend to be active, while in over-dense regions neighbour galaxies are mostly passive, regardless of the activity of their primary galaxies. At a given stellar mass, passive primary galaxies reside in higher density regions than active primary galaxies, leading to the apparently strong conformity signal. The dependence of the activity of neighbour galaxies on environment can be explained by the corresponding dependence of the fraction of satellite galaxies. Similar results are found for galaxies in a semi-analytical model, suggesting that no new physics is required to explain the observed large-scale conformity.

  5. Self-resonant wakefield excitation by intense laser pulse in plasmas

    International Nuclear Information System (INIS)

    Andreev, N.E.; Pogosova, A.A.; Gorbunov, L.M.; Ramazashvili, R.R.; Kirsanov, V.I.

    1993-01-01

    It is demonstrated by theoretical analysis and numerical calculations that in an underdense plasma the process of three-dimensional evolution of the short and strong laser pulse (with duration equal to several plasma periods) leads to compression and self-modulation of the pulse, so that during a fairly long period of time beats of pulse amplitude generates resonantly a strong and stable plasma wakefield. The intensity of the wake-field is so high that it can provide a new promising outlook for the plasma based accelerator concept. Linear analysis of dispersion relation predicts that taking into account transverse component of wavenumber considerably increases the growth rate of resonance instability of the pulse. The numerical simulations demonstrate that considered self-focusing and resonant-modulation instability are essentially three dimensional processes. Laser field evolution in each transverse cross section of the pulse is synchronized by the regular structure of plasma wave that is excited by the pulse. The considered effect of resonant modulation has a threshold. For the pulses with the intensity below the threshold the refraction dominates and no modulation appears. The studied phenomenon can be referred to as the Self-Resonant Wakefield (SRWF) excitation that is driven by self-focusing and self-modulation of laser pulse with quite a moderate initial duration. In fact, this method of excitation differs from both suggested in Ref.1 (PBWA) and in Refs.2,3 (LWFA), being even more than the combination of these concepts. Unlike the first scheme it does not require initially the two-frequency laser pulse, since the modulation here appears in the most natural way due to evolution of the pulse. In contrast with the LWFA, the considered SRWF generation scheme gives the possibility to raise the intensity of wake-excitation due to pulse self-focusing ( initial stage) and self modulation (second stage)

  6. Laser-driven, magnetized quasi-perpendicular collisionless shocks on the Large Plasma Device

    International Nuclear Information System (INIS)

    Schaeffer, D. B.; Everson, E. T.; Bondarenko, A. S.; Clark, S. E.; Constantin, C. G.; Vincena, S.; Van Compernolle, B.; Tripathi, S. K. P.; Gekelman, W.; Niemann, C.; Winske, D.

    2014-01-01

    The interaction of a laser-driven super-Alfvénic magnetic piston with a large, preformed magnetized ambient plasma has been studied by utilizing a unique experimental platform that couples the Raptor kJ-class laser system [Niemann et al., J. Instrum. 7, P03010 (2012)] to the Large Plasma Device [Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] at the University of California, Los Angeles. This platform provides experimental conditions of relevance to space and astrophysical magnetic collisionless shocks and, in particular, allows a detailed study of the microphysics of shock formation, including piston-ambient ion collisionless coupling. An overview of the platform and its capabilities is given, and recent experimental results on the coupling of energy between piston and ambient ions and the formation of collisionless shocks are presented and compared to theoretical and computational work. In particular, a magnetosonic pulse consistent with a low-Mach number collisionless shock is observed in a quasi-perpendicular geometry in both experiments and simulations

  7. Bursty fluctuation characteristics in SOL/divertor plasmas of large helical device

    International Nuclear Information System (INIS)

    Ohno, N.

    2006-01-01

    Full text: Fluctuation properties in the SOL plasmas were intensively studied to understand the crossfield plasma transport, which determines the SOL structure and heat/particle deposition onto the first wall. Recent studies in tokamaks showed that the SOL density fluctuation is highly intermittent. Convective cross-field transport associated with the intermittent events would have strong influence on recycling processes and impurity generation from the first wall. On the other hand, in helical devices, there are few systematic studies on the SOL fluctuation property focusing on the intermittent bursty fluctuations related to plasma blob transport. Recent theory predicts that the blobs propagate toward a low field side in tokamaks. On the other hand, in the Large Helical Device (LHD), the direction of the gradient in B is not uniform because the high-field and the low-field sides rotates poloidally along the torus in the helical system. Comparison between the intermittent bursty fluctuations in the edge plasma of tokamaks and helical devices makes it possible to understand the essential physics of the blob transport. Recently, fast camera observation showed the radial motion of filaments in the edge of the LHD, suggesting the convective cross-field transport. In this paper, bursty fluctuation properties in the edge of the LHD have been investigated by analyzing the ion saturation currents measured with a probe array embedded in an outboard divertor plate. Statistical analysis based on probability distribution function was employed to determine the intermittent evens in the density fluctuation. Large positive bursty events were often observed in the ion saturation current measured with a divertor probe near a divertor leg at which the magnetic line of force connected to the area of a low-field side with a short connection length. Condition averaging result of the positive bursty events indicates the intermittent feature with a rapid increase and a slow decay is

  8. Effects of large-angle Coulomb collisions on inertial confinement fusion plasmas.

    Science.gov (United States)

    Turrell, A E; Sherlock, M; Rose, S J

    2014-06-20

    Large-angle Coulomb collisions affect the rates of energy and momentum exchange in a plasma, and it is expected that their effects will be important in many plasmas of current research interest, including in inertial confinement fusion. Their inclusion is a long-standing problem, and the first fully self-consistent method for calculating their effects is presented. This method is applied to "burn" in the hot fuel in inertial confinement fusion capsules and finds that the yield increases due to an increase in the rate of temperature equilibration between electrons and ions which is not predicted by small-angle collision theories. The equilibration rate increases are 50%-100% for number densities of 10(30)  m(-3) and temperatures around 1 keV.

  9. Low-impedance internal linear inductive antenna for large-area flat panel display plasma processing

    International Nuclear Information System (INIS)

    Kim, K.N.; Jung, S.J.; Lee, Y.J.; Yeom, G.Y.; Lee, S.H.; Lee, J.K.

    2005-01-01

    An internal-type linear inductive antenna, that is, a double-comb-type antenna, was developed for a large-area plasma source having the size of 1020 mmx830 mm, and high density plasmas on the order of 2.3x10 11 cm -3 were obtained with 15 mTorr Ar at 5000 W of inductive power with good plasma stability. This is higher than that for the conventional serpentine-type antenna, possibly due to the low impedance, resulting in high efficiency of power transfer for the double-comb antenna type. In addition, due to the remarkable reduction of the antenna length, a plasma uniformity of less than 8% was obtained within the substrate area of 880 mmx660 mm at 5000 W without having a standing-wave effect

  10. Development and verification test on remote plasma cutting of large metallic waste

    International Nuclear Information System (INIS)

    Ozawa, Tamotsu; Yamada, Kunitaka; Abe, Tadashi

    1979-01-01

    Plasma cutting is the cutting method to melt and scatter cut objects by generating arc between an electrode in a nozzle and the cut objects and making working gas fed to surround it into high temperature, high speed plasma jet. In case of remote plasma cutting, a torch for the plasma cutting is operated remotely with a manipulator from the outside of a cell. At the time of planning the method of breaking up solid wastes, the type of cutting machines and the method of remote operation of the cutting machines and cut objects were examined. It was decided to adopt plasma cutting machines, because their cutting capability such as materials, thickness and cutting speed is excellent, and the construction and handling are simple. The form of the solid wastes to be cut is not uniform, accordingly the method of manipulator operation was adopted to respond to various forms flexibly. Cut objects are placed on a turntable to change the position successively. In case of remote plasma cutting, the controls of torch speed and gap must be made with a manipulator. The use of light-shielding glasses reduces largely the watchability of cut objects and becomes hindrance in the operation. As for the safety aspect, the suitable gas for cutting, which does not contain hydrogen, must be selected. The tests carried out for two years since November, 1977, are reported in this paper, and most of the problems have been solved. (Kako, I.)

  11. A simple model for the initial phase of a water plasma cloud about a large structure in space

    International Nuclear Information System (INIS)

    Hastings, D.E.; Gatsonis, N.A.; Mogstad, T.

    1988-01-01

    Large structures in the ionosphere will outgas or eject neutral water and perturb the ambient neutral environment. This water can undergo charge exchange with the ambient oxygen ions and form a water plasma cloud. Additionally, water dumps or thruster firings can create a water plasma cloud. A simple model for the evolution of a water plasma cloud about a large space structure is obtained. It is shown that if the electron density around a large space structure is substantially enhanced above the ambient density then the plasma cloud will move away from the structure. As the cloud moves away, it will become unstable and will eventually break up into filaments. A true steady state will exist only if the total electron density is unperturbed from the ambient density. When the water density is taken to be consistent with shuttle-based observations, the cloud is found to slowly drift away on a time scale of many tens of milliseconds. This time is consistent with the shuttle observations

  12. Plasma parameter estimations for the Large Helical Device based on the gyro-reduced Bohm scaling

    International Nuclear Information System (INIS)

    Okamoto, Masao; Nakajima, Noriyoshi; Sugama, Hideo.

    1991-10-01

    A model of gyro-reduced Bohm scaling law is incorporated into a one-dimensional transport code to predict plasma parameters for the Large Helical Device (LHD). The transport code calculations reproduce well the LHD empirical scaling law and basic parameters and profiles of the LHD plasma are calculated. The amounts of toroidal currents (bootstrap current and beam-driven current) are also estimated. (author)

  13. High-intensity subpicosecond laser pulse propagation in a 1-cm capillary tube and fast ignitor experiments

    Energy Technology Data Exchange (ETDEWEB)

    Malka, G.; Courtois, C.; Cros, B.; Matthieussent, G. [Paris-11 Univ., 91 - Orsay (France). Lab. de Physique des Gaz et des Plasmas; Blanchot, N.; Bonnaud, G.; Busquet, M.; Canaud, B.; Desenne, D.; Diskier, L.; Garconnet, J.P.; Louis-Jacquet, M.; Lefebvre, E.; Lours, L.; Mens, A.; Miquel, J.L.; Peyrusse, O.; Rousseaux, C. [CEA/Limeil Valenton, 94 - Villeneuve Saint Georges (France); Borghesi, M.; Gaillard, R.; Mackinnon, A.J.; Willi, O. [Imperial Coll., Plasma Physics Groups, London (United Kingdom); Danson, C.; Neely, D. [Rutherford Appleton Lab., Chilton (United Kingdom); Altenberd, D.; Feurer, T.; Forster, E.; Gibbon, P.; Sauerbray, R.; Teubner, U.; Theobald, W.; Uschmann, I. [Institut fur Optik und Quantenelektronik, Jena (Germany); Amiranoff, F.; Baton, S.; Gremillet, L.; Fuchs, J.; Marques, J.R. [Ecole Polytechnique, Lab. d' Utilisation de Lasers Intenses, CNRS-CEA, 91 - Palaiseau (France); Gallant, P.; Kieffer, J.C.; Pepin, H. [INRS Energie et Materiaux, Quebec (Canada); Adam, J.C.; Heron, A.; Laval, G.; Mora, P. [Ecole Polytechnique, 91 - Palaiseau (France). Centre de Physique Theorique

    2000-07-01

    We present an abstract of ultra short and intense laser plasma interaction experiments which were performed with the 100 TW P102 laser facility at CEA/Limeil-Valenton. Laser interaction at relativistic regime (I>10{sup 18} W/cm{sup 2}) has been investigated with different 'targets': overdense plasma, underdense plasma, free electrons and capillary tube. These experiments are of great interests for the Fast Ignitor concept and the Laser Particle Accelerator. (authors)

  14. Frequency up-conversion and spectral breaking of a high power microwave pulse propagation in a self-generated plasma

    International Nuclear Information System (INIS)

    Kuo, S.P.; Ren, A.

    1993-01-01

    The main concern of the propagation of high power microwave pulse is the energy loss of the pulse before reaching the destination. The loss is caused by self-generated plasma. There are two processes which are responsible for the energy loss (so called tail erosion). They are collisional damping and cutoff reflection. In very high power region, the cutoff reflection is much more severe than the collisional damping. A frequency up-conversion process may help to avoid the cutoff reflection of powerful electromagnetic pulse propagating in a self-generated plasma. Both chamber experiments and numerical simulation are performed. When the field amplitude only slightly exceeds the breakdown threshold field of the background gas, the result shows that the carrier frequency ω of the pulse shifts upward during the growth of local plasma frequency ωpe 2 . Thus, the self-generated plasma remains underdense to the pulse. However, the spectrum of the pulse starts to break up into two major peaks when the amplitude of the pulse is further increased. The frequency of one of the peaks is lower than the original carrier frequency and that of the other peak is higher than the original carrier frequency. These phenomena are observed both experimentally and numerically. The frequency down shift result is believed to be caused by damping mechanisms. Good agreement between the experimental results and the numerical simulation is obtained

  15. Laser-supported ionization wave in under-dense gases and foams

    International Nuclear Information System (INIS)

    Gus'kov, S. Yu.; Limpouch, J.; Nicolaie, Ph.; Tikhonchuk, V. T.

    2011-01-01

    Propagation of laser-supported ionization wave in homogeneous and porous materials with a mean density less than the critical plasma density is studied theoretically in the one-dimensional geometry. It is shown that the velocity of the ionization wave in a foam is significantly decreased in comparison with the similar wave in a homogeneous fully ionized plasma of the same density. That difference is attributed to the ionization and hydro-homogenization processes forming an under-critical density environment in the front of ionization wave. The rate of energy transfer from laser to plasma is found to be in a good agreement with available experimental data.

  16. Simulation analysis of dust-particle transport in the peripheral plasma in the Large Helical Device

    International Nuclear Information System (INIS)

    Shoji, Mamoru; Masuzaki, Suguru; Kawamura, Gakushi; Yamada, Hiroshi; Tanaka, Yasunori; Uesugi, Yoshihiko; Pigarov, Alexander Yu.; Smirnov, Roman D.

    2014-01-01

    The function of the peripheral plasma in the Large Helical Device (LHD) on transport of dusts is investigated using a dust transport simulation code (DUSTT) in a non-axisymmetric geometry. The simulation shows that the transport of the dusts is dominated by the plasma flow (mainly by ion drag force) formed in the peripheral plasma. The trajectories of dusts are investigated in two probable situations: release of spherical iron dusts from the inboard side of the torus, and drop of spherical carbon dusts from a divertor plate installed near an edge of an upper port. The trajectories in these two situations are calculated in various sized dust cases. From a viewpoint of protection of the main plasma from dust penetration, it proves that there are two functions in the LHD peripheral plasma. One is sweeping of dusts by the effect of the plasma flow in the divertor legs, and another one is evaporation/sublimation of dusts by heat load onto the dusts in the ergodic layer. (author)

  17. Impulse electron gun with plasma cathode for realization of large diameter tube-shaped beams

    International Nuclear Information System (INIS)

    Antipov, V.S.; Karpukhin, V.I.; Kornilov, E.A.

    1999-01-01

    There are presented the results of investigations of a plasma electron source based on the gas discharge in a coaxial system of electrodes with longitudinal magnetic field. The examination is fulfilled from the viewpoint of applying the source as a plasma cathode for hybrid plasma-waveguide slow-wave structures on the basis of a disk-loaded coaxial. The source is optimized in order to get a powerful (up to 100 kW) nonrelativistic electron beam with the annular cross-section of a large diameter in the regime of relatively long current pulses (up to 0.2 ms) under the gas pressure ∼ 5 centre dot 10 -4 mm Hg in the area of the discharge burning

  18. Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

    Science.gov (United States)

    Li, Lee; Liu, Lun; Liu, Yun-Long; Bin, Yu; Ge, Ya-Feng; Lin, Fo-Chang

    2014-01-01

    Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible.

  19. Design of an RF Antenna for a Large-Bore, High Power, Steady State Plasma Processing Chamber for Material Separation

    International Nuclear Information System (INIS)

    Rasmussen, D.A.; Freeman, R.L.

    2001-01-01

    The purpose of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC, (Contractor), and Archimedes Technology Group, (Participant) is to evaluate the design of an RF antenna for a large-bore, high power, steady state plasma processing chamber for material separation. Criteria for optimization will be to maximize the power deposition in the plasma while operating at acceptable voltages and currents in the antenna structure. The project objectives are to evaluate the design of an RF antenna for a large-bore, high power, steady state plasma processing chamber for material separation. Criteria for optimization will be to maximize the power deposition in the plasma while operating at acceptable voltages and currents in the antenna structure

  20. On the relativistic large-angle electron collision operator for runaway avalanches in plasmas

    Science.gov (United States)

    Embréus, O.; Stahl, A.; Fülöp, T.

    2018-02-01

    Large-angle Coulomb collisions lead to an avalanching generation of runaway electrons in a plasma. We present the first fully conservative large-angle collision operator, derived from the relativistic Boltzmann operator. The relation to previous models for large-angle collisions is investigated, and their validity assessed. We present a form of the generalized collision operator which is suitable for implementation in a numerical kinetic equation solver, and demonstrate the effect on the runaway-electron growth rate. Finally we consider the reverse avalanche effect, where runaways are slowed down by large-angle collisions, and show that the choice of operator is important if the electric field is close to the avalanche threshold.

  1. Plasma behaviour in large reversed-field pinches and reactors

    International Nuclear Information System (INIS)

    Christiansen, J.P.; Bodin, H.A.B.; Carolan, P.G.; Johnston, J.W.; Newton, A.A.; Roberts, K.V.; Robinson, D.C.; Watts, M.R.C.; Piotrowicz, V.A.

    1981-01-01

    Recent analytic and numerical results on large reversed-field-pinch (RFP) systems and RFP reactors are presented. Predictions are made of the plasma behaviour in Eta Beta II, HBTXIA (under construction) and RFX (planned). The setting-up phase of an RFP is studied by using turbulence theory in transport equilibrium calculations, and estimates are made of the volt-seconds consumption for four different modes of field control. A prescription is given for a dynamo producing self-reversal which yields finite-β configurations. Residual instabilities of these equilibria may be resistive pressure-driven g-modes, and a new study of these modes that includes parallel viscosity indicates stability for anti β approximately 10%. The sustainment phase of the RFP is examined with tokamak scaling laws assumed for the energy confinement time. Temperatures in excess of 1keV are predicted for currents of 2MA in RFX. An operating cycle for a pulsed RFP reactor including gas puffing to reach ignition is proposed following a study of the energy replacement time for an Ohmically heated plasma. The scaling of the reactor parameters with minor radius is also investigated. (author)

  2. Short wavelength laser-plasma interaction experiments in a spherical geometry

    International Nuclear Information System (INIS)

    Keck, R.L.

    1984-01-01

    Short wavelength (250 to 500 nm) lasers should provide reduced fast electron preheat and increased laser-pellet coupling efficiency when used as laser fusion drivers. As part of an ongoing effort to study short wavelength laser plasm interaction, six beams of the 24 beam OMEGA Nd-glass laser system have been converted to operation at the third harmonic. This system is capable of providing in excess of 250 Joules of 351 nm light on spherical targets at intensities up to 2 x 10/sup 15/ W/cm/sup 2/. To date, experiments have been performed to study the uniformity of irradiation, laser absorption, fast electron production and preheat, energy transport within the target and underdense plasma instabilities. Both x-ray continuum measurements and Kα line measurements indicate that the absorption is dominated by inverse bremsstrahlung. Electron energy transport has been studied using x-ray burn-through and charge collector measurements. The results show that with 351 nm irradiation ablation pressures of order 100 Mbars are generated at intensities of 10/sup 15/ W/cm/sup 2/

  3. Analytic expressions for polarimetry in plasma with large Cotton endash Mouton or Faraday effects

    International Nuclear Information System (INIS)

    Segre, S.E.

    1996-01-01

    Analytic expressions for plasma polarimetry are derived for the case when either the Cotton endash Mouton effect or the Faraday effect is large while the other effect is small. copyright 1996 American Institute of Physics

  4. An analysis of plasma ion toroidal rotation during large amplitude MHD activity in JET

    International Nuclear Information System (INIS)

    Snipes, J.A.; Esch, H.P.L. de; Lazzaro, E.; Stork, D.; Hellermann, M. von; Galvao, R.; Hender, T.C.; Zasche, D.

    1989-01-01

    A detailed study of plasma ion toroidal rotation in JET during large amplitude MHD activity has revealed a strong viscous force that couples plasma ions to MHD modes. Depending on the MHD modes present, this force can couple across all of the plasma cross section, across only the central region, roughly within the q=1 surface, or across only the outer region outside the q=1.5 surface. The force acts to flatten the ion toroidal rotation frequency profile, measured by the JET active charge exchange spectroscopy diagnostic, across the coupled region of plasma. The frequency of rotation in this region agrees with the MHD oscillation frequency measured by magnetic pick-up coils at the wall. The strength of the force between the ions and modes becomes evident during high power NBI when the mode locks and drags the ion toroidal rotation frequency to zero, within the errors of the measurements. The present theories of plasma rotation either ignore MHD effects entirely, consider only moderate n toroidal field ripple, or low n ripple effects. (author) 7 refs., 3 figs

  5. Producing x-rays

    International Nuclear Information System (INIS)

    Mallozzi, P.J.; Epstein, H.M.; Jung, R.G.; Applebaum, D.C.; Fairand, B.P.; Gallagher, W.J.

    1977-01-01

    A method of producing x-rays by directing radiant energy from a laser onto a target is described. Conversion efficiency of at least about 3 percent is obtained by providing the radiant energy in a low-power precursor pulse of approximately uniform effective intensity focused onto the surface of the target for about 1 to 30 nanoseconds so as to generate an expanding unconfined coronal plasma having less than normal solid density throughout and comprising a low-density (underdense) region wherein the plasma frequency is less than the laser radiation frequency and a higher-density (overdense) region wherein the plasma frequency is greater than the laser radiation frequency and, about 1 to 30 nanoseconds after the precursor pulse strikes the target, a higher-power main pulse focused onto the plasma for about 10 -3 to 30 nanoseconds and having such power density and total energy that the radiant energy is absorbed in the underdense region and conducted into the overdense region to heat it and thus to produce x-rays therefrom with the plasma remaining substantially below normal solid density and thus facilitating the substantial emission of x-rays in the form of spectral lines arising from nonequilibrium ionization states

  6. Applying Boundary Conditions Using a Time-Dependent Lagrangian for Modeling Laser-Plasma Interactions

    Science.gov (United States)

    Reyes, Jonathan; Shadwick, B. A.

    2016-10-01

    Modeling the evolution of a short, intense laser pulse propagating through an underdense plasma is of particular interest in the physics of laser-plasma interactions. Numerical models are typically created by first discretizing the equations of motion and then imposing boundary conditions. Using the variational principle of Chen and Sudan, we spatially discretize the Lagrangian density to obtain discrete equations of motion and a discrete energy conservation law which is exactly satisfied regardless of the spatial grid resolution. Modifying the derived equations of motion (e.g., enforcing boundary conditions) generally ruins energy conservation. However, time-dependent terms can be added to the Lagrangian which force the equations of motion to have the desired boundary conditions. Although some foresight is needed to choose these time-dependent terms, this approach provides a mechanism for energy to exit the closed system while allowing the conservation law to account for the loss. An appropriate time discretization scheme is selected based on stability analysis and resolution requirements. We present results using this variational approach in a co-moving coordinate system and compare such results to those using traditional second-order methods. This work was supported by the U. S. Department of Energy under Contract No. DE-SC0008382 and by the National Science Foundation under Contract No. PHY- 1104683.

  7. Suitability of thermal plasmas for large-area bacteria inactivation on temperature-sensitive surfaces – first results with Geobacillus stearothermophilus spores

    International Nuclear Information System (INIS)

    Szulc, M; Schein, S; Schaup, J; Zimmermann, S; Schein, J

    2017-01-01

    The application of thermal plasma for large-area bacteria inactivation on temperature-sensitive surfaces is not a common one. Nonetheless, there are thermal plasma generators which offer a high sheath homogeneity and have proven to be suitable for treatment of thermally sensitive materials in the past. To investigate the suitability of such plasmas, agar dishes plated with endospores of Geobacillus stearothermophilus have been treated with a long arc plasma generator called LARGE. The achieved results have been compared with a commercially available non-thermal plasma generator. A significant inactivation of the endospores could be observed only after 60 s of treatment with the thermal plasma source. This was not possible with the non-thermal generator. Moreover, no temperature damage or increase of the specimen could be detected. An attempt to determine the main agents responsible for the microbicidal effects have been made – the influence of plasma gas composition, discharge current and treatment time has been investigated. Significant improvements in the disinfection rates after adding small amounts of nitrogen to the plasma gas could be observed. A first discussion regarding the suitability of thermal plasmas for bacteria inactivation has been given. (paper)

  8. Measurements of plasma termination in ICRF heated long pulse discharges with fast framing cameras in the Large Helical Device

    International Nuclear Information System (INIS)

    Shoji, Mamoru; Kasahara, Hiroshi; Tanaka, Hirohiko

    2015-01-01

    The termination process of long pulse plasma discharges in the Large Helical Device (LHD) have been observed with fast framing cameras, which shows that the reason for the termination of the discharged has been changed with increased plasma heating power, improvements of plasma heating systems and change of the divertor configuration, etc. For long pulse discharges in FYs2010-2012, the main reason triggering the plasma termination was reduction of ICRF heating power with rise of iron ion emission due to electric breakdown in an ICRF antenna. In the experimental campaign in FY2013, the duration time of ICRF heated long pulse plasma discharges has been extended to about 48 minutes with a plasma heating power of ∼1.2 MW and a line-averaged electron density of ∼1.2 × 10"1"9 m"-"3. The termination of the discharges was triggered by release of large amounts of carbon dusts from closed divertor regions, indicating that the control of dust formation in the divertor regions is indispensable for extending the duration time of long pulse discharges. (author)

  9. Large Amplitude Low Frequency Waves in a Magnetized Nonuniform Electron-Positron-Ion Plasma

    Institute of Scientific and Technical Information of China (English)

    Q. Haque; H. Saleem

    2004-01-01

    @@ It is shown that the large amplitude low-frequency electromagnetic drift waves in electron-positron-ion plasmas might give rise to dipolar vortices. A linear dispersion relation of several coupled electrostatic and electromagnetic low-frequency modes is obtained. The relevance of this work to both laboratory and astrophysical situations is pointed out.

  10. Steady-state plasma and reactor parameters for elliptical cross section tokamaks with very large power ratings

    International Nuclear Information System (INIS)

    Usher, J.L.; Powell, J.R.

    1975-06-01

    In previous studies only circular cross section reactor plasmas were considered. The purpose of this research is to examine the effects of elliptical plasma cross sections. Several technological benefits have been determined. Maximum magnetic field strength requirements are 30 to 65 percent less than for 5000 MW (th) reactors and may be as much as 40 percent less than for circular cross section reactors of comparable size. Very large n tau values are found (10 15 to 10 17 sec/cm 3 ), which produce large burn-up fractions (15 to 60 percent). There is relatively little problem with impurity build-up. Long confinement times (60 to 500 seconds) are found. Finally, the elliptical cross section reactors exhibit a major toroidal radius reduction of as large as 30 percent over circular reactors operating at comparable power levels

  11. Stationary high confinement plasmas with large bootstrap current fraction in JT-60U

    International Nuclear Information System (INIS)

    Sakamoto, Y.; Fujita, T.; Ide, S.; Isayama, A.; Takechi, M.; Suzuki, T.; Takenaga, H.; Oyama, N.; Kamada, Y.

    2005-01-01

    This paper reports the results of the progress in stationary discharges with a large bootstrap current fraction in JT-60U towards steady-state tokamak operation. In the weak shear plasma regime, high-β p ELMy H-mode discharges have been optimized under nearly full non-inductive current drive conditions by the large bootstrap current fraction (f BS ∼ 45%) and the beam driven current fraction (f BD ∼ 50%), which was sustained for 5.8 s in the stationary condition. This duration corresponds to ∼26τ E and ∼2.8τ R , which was limited by the pulse length of negative-ion-based neutral beams. The high confinement enhancement factor H 89 ∼ 2.2 (HH 98y2 ∼ 1.0) was obtained and the profiles of current and pressure reached the stationary condition. In the reversed shear plasma regime, a large bootstrap current fraction (f BS ∼ 75%) has been sustained for 7.4 s under nearly full non-inductive current drive conditions. This duration corresponds to ∼16τ E and ∼2.7τ R . The high confinement enhancement factor H 89 ∼ 3.0 (HH 98y2 ∼ 1.7) was also sustained, and the profiles of current and pressure reached the stationary condition. The large bootstrap current and the off-axis beam driven current sustained this reversed q profile. This duration was limited only by the duration of the neutral beam injection

  12. A review of the findings of the plasma diagnostic package and associated laboratory experiments: Implications of large body/plasma interactions for future space technology

    Science.gov (United States)

    Murphy, Gerald B.; Lonngren, Karl E.

    1986-01-01

    The discoveries and experiments of the Plasma Diagnostic Package (PDP) on the OSS 1 and Spacelab 2 missions are reviewed, these results are compared with those of other space and laboratory experiments, and the implications for the understanding of large body interactions in a low Earth orbit (LEO) plasma environment are discussed. First a brief review of the PDP investigation, its instrumentation and experiments is presented. Next a summary of PDP results along with a comparison of those results with similar space or laboratory experiments is given. Last of all the implications of these results in terms of understanding fundamental physical processes that take place with large bodies in LEO is discussed and experiments to deal with these vital questions are suggested.

  13. Generation of ultra-short relativistic-electron-bunch by a laser wakefield

    NARCIS (Netherlands)

    Khachatryan, A.G.; Boller, Klaus J.; van Goor, F.A.

    2003-01-01

    The possibility of the generation of an ultra-short (about one micron long) relativistic (up to a few GeVs) electron-bunch in a moderately nonlinear laser wakefield excited in an underdense plasma by an intense laser pulse is investigated. The ultra-short bunch is formed by trapping, effective

  14. Aberrant methylation of cell-free circulating DNA in plasma predicts poor outcome in diffuse large B cell lymphoma

    DEFF Research Database (Denmark)

    Sommer Kristensen, Lasse; Hansen, Jakob Werner; Kristensen, Søren Sommer

    2016-01-01

    BACKGROUND: The prognostic value of aberrant DNA methylation of cell-free circulating DNA in plasma has not previously been evaluated in diffuse large B cell lymphoma (DLBCL). The aim of this study was to investigate if aberrant promoter DNA methylation can be detected in plasma from DLBCL patients...

  15. Predicting Pulsar Scintillation from Refractive Plasma Sheets

    Science.gov (United States)

    Simard, Dana; Pen, Ue-Li

    2018-05-01

    The dynamic and secondary spectra of many pulsars show evidence for long-lived, aligned images of the pulsar that are stationary on a thin scattering sheet. One explanation for this phenomenon considers the effects of wave crests along sheets in the ionized interstellar medium, such as those due to Alfvén waves propagating along current sheets. If these sheets are closely aligned to our line-of-sight to the pulsar, high bending angles arise at the wave crests and a selection effect causes alignment of images produced at different crests, similar to grazing reflection off of a lake. Using geometric optics, we develop a simple parameterized model of these corrugated sheets that can be constrained with a single observation and that makes observable predictions for variations in the scintillation of the pulsar over time and frequency. This model reveals qualitative differences between lensing from overdense and underdense corrugated sheets: Only if the sheet is overdense compared to the surrounding interstellar medium can the lensed images be brighter than the line-of-sight image to the pulsar, and the faint lensed images are closer to the pulsar at higher frequencies if the sheet is underdense, but at lower frequencies if the sheet is overdense.

  16. Vlasov simulation of the relativistic effect on the breaking of large amplitude plasma waves

    International Nuclear Information System (INIS)

    Xu Hui; Sheng Zhengming; Zhang Jie

    2007-01-01

    The influence of relativistic and thermal effects on plasma wave breaking has been studied by solving the coupled Vlasov-Poisson equations. When the relativistic effect is not considered, the wave breaking will not occur, provided the initial perturbation is less than certain value as predicted previously, and the largest amplitude of the plasma wave will decrease with the increase of the initial temperature. When the relativistic effect is considered, wave breaking always occurs during the time evolution, irrespective of the initial perturbation amplitude. Yet the smaller the initial perturbation amplitude is, the longer is the time for wave breaking to occur. With large initial perturbations, wave breaking can always occur with the without the relativistic effect. However, the results are significantly different in the two cases. The thermal effects of electrons decrease the threshold value to initial amplitude for wave breaking and large phase velocity makes the nonlinear phenomenon occur more easily. (authors)

  17. Development of Diagnostics for Large-Scale Experiments with Dense Magnetized Plasmas - MJ Plasma-focus diagnostics systems

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, M.; Karpinski, L.; Paduch, M.; Pisarczyk, T.; Zielinska, E.; Chodukowski, T. [Institute of Plasma Physics and Laser Microfusion IPPLM, 01-497 Warsaw (Poland); Sadowski, M.J. [Institute of Plasma Physics and Laser Microfusion IPPLM, 01-497 Warsaw (Poland)] [The Andrzej Soltan Institute for Nuclear Studies IPJ, 05-400 Otwock-Swiert (Poland); Skladnik-Sadowska, E.; Czaus, K.; Kwiatkowski, R.; Malinowski, K. [The Andrzej Soltan Institute for Nuclear Studies IPJ, 05-400 Otwock-Swiert (Poland); Krauz, S. [RNC Kurchatov Institute, Moscow (Russian Federation); Mitrovanov, K. [FGUP GNC RF Triniti, Troick (Russian Federation)

    2011-07-01

    This document presents the diagnostics arrangements and interesting results of research on fusion pulsed plasma, which was generated within the large PF-1000 facility operated in the Institute of Plasma Physics and Laser Microfusion (Warsaw, Poland). Experimental studies were carried out with the following diagnostic techniques: 1) Rogovski coil for current measurements; 2) Four dI/dt probes in different places around the collector of PF-1000; 3) Voltage divider; 4) Mach-Zender interferometer (16 frames); 5) Fast scintillation probes for X-ray and neutron detection; 6) Silver activation counters; 7) Specially prepared current probes; 8) Thomson spectrometer for mass- and energy-analysis of deuterium beams; 9) Ion-pinhole cameras equipped with nuclear-track detectors, etc. The studies have been carried out with the pure deuterium filling, and particular attention was paid to correlations between the fast-neutron emission and an evolution of plasma parameters. The total fusion-neutron yield, as measured with four silver-activation counters, was found to be up to 7*10{sup 11} per shot, depending on the experimental conditions. Correlations of the neutron pulses with interferometric frame-pictures of the PF pinch column were studied. From time-of-flight (ToF) measurements of the fusion neutrons it was possible to estimate a CM velocity of deuterons involved in the D-D reactions. The fast fusion-produced protons have also been recorded and analyzed by means pinhole cameras and shielded track detectors. The document is composed of an abstract followed by the slides of the presentation. (authors)

  18. Microwave heating and diagnostic of suprathermal electrons in an overdense stellarator plasma

    International Nuclear Information System (INIS)

    Stange, Torsten

    2014-01-01

    of the heating efficiencies of the different heating scenarios (overdense non-resonant heating, underdense and overdense resonant heating) a variety of diagnostic methods have been used. Based on heat wave experiments and measuring the response of the total plasma radiation, an estimate of the absorbed heating power and the energy confinement time has been achieved with an accuracy of ±10% dependent on the measurement accuracy of the radiated power.

  19. Scattering of electromagnetic waves into plasma oscillations via plasma particles

    International Nuclear Information System (INIS)

    Lin, A.T.; Dawson, J.M.

    1975-01-01

    A plasma subjected to an intense electromagnetic wave can exhibit a large number of parametric instabilities. An interesting example which has received little attention is the decay of the electromagnetic wave into a plasma oscillation with the excess energy and momentum being carried off by electrons. This process has been simulated on a one-and-two-halves dimensional electromagnetic code. The incident electromagnetic wave had a frequency near the plasma frequency so that decay into a plasma oscillation and a backscattered electromagnetic wave was excluded. As expected, the threshold for this instability was very large , so it is unlikely that this instability is competitive in most laser plasmas. Nevertheless, the physical mechanism involved provides a means for absorption of laser light and acceleration of particles in a plasma containing large amplitude plasma oscillations

  20. FORMATION OF THE INITIAL DISTRIBUTION OF PLASMA COMPONENTS ON THE PHASE PLANE OF LARGE PARTICLES METHOD IN ELECTRIC ARC SYNTHESIS CNS

    Directory of Open Access Journals (Sweden)

    G. V. Abramov

    2014-01-01

    Full Text Available The article deals with the modeling of charged particles in a multicomponent plasma of electric arc discharge with binary collisions in the synthesis of carbon nanostructures (CNS. One of the common methods of obtaining the quality of fullerenes and nanotubes is arc synthesis under inert gas (helium. The determination of the necessary conditions and the mechanism of formation of carbon clusters in the plasma forming set CNS will more effectively and efficiently manage this process. Feature of the problem is that in a plasma arc discharge is a large number of particle interactions and on the cathode surface. Due to the high temperatures and high energy concentration in plasma detailed experimental investigation difficult to carry out. With the aim of avoiding difficult and costly physical experiments developed numerical methods for the analysis of plasma processes. In this article to solve a system of equations of Maxwell - Boltzmann basis for the authors had taken the method of large particles, which reduces the amount of computation and reduce the demands on computing resources. The authors cites the general design scheme of the large particles, and the algorithm of particle distribution of a multicomponent plasma in the phase plane at the initial time. In conclusion, the author argues that the results in the future will define the zone satisfies the energy conditions, the probability of formation of a plasma cluster groups of carbon involved in the synthesis of the CNS.

  1. Collisionless magnetic reconnection in large-scale electron-positron plasmas

    International Nuclear Information System (INIS)

    Daughton, William; Karimabadi, Homa

    2007-01-01

    One of the most fundamental questions in reconnection physics is how the dynamical evolution will scale to macroscopic systems of physical relevance. This issue is examined for electron-positron plasmas using two-dimensional fully kinetic simulations with both open and periodic boundary conditions. The resulting evolution is complex and highly dynamic throughout the entire duration. The initial phase is distinguished by the coalescence of tearing islands to larger scale while the later phase is marked by the expansion of diffusion regions into elongated current layers that are intrinsically unstable to plasmoid generation. It appears that the repeated formation and ejection of plasmoids plays a key role in controlling the average structure of a diffusion region and preventing the further elongation of the layer. The reconnection rate is modulated in time as the current layers expand and new plasmoids are formed. Although the specific details of this evolution are affected by the boundary and initial conditions, the time averaged reconnection rate remains fast and is remarkably insensitive to the system size for sufficiently large systems. This dynamic scenario offers an alternative explanation for fast reconnection in large-scale systems

  2. DRAGON: a new 18 GHz RT ECRIS with a large plasma chamber

    International Nuclear Information System (INIS)

    Lu, W.; Xie, D.Z.; Zhang, X.Z.; Zhao, H.W.; Ruan, L.; Song, F.C.; Xiong, B.; Yu, S.; Yuan, J.

    2012-01-01

    Building a strong radial magnetic field with a permanent sextupole magnet for an ECRIS is extremely challenging so that the conventional wisdom recommends a small but not optimal plasma chamber that is typically of ID less or equal to 80 mm. A new 18 GHz RT ECRIS, DRAGON, with a large bore permanent sextupole has been designed and is under construction at IMP (Institute of Modern Physics, Lanzhou, China). Its plasma chamber is of ID 126 mm, the same as that of the superconducting ion source SECRAL, with maximum radial field strength reaching 1.5 T at the plasma chamber wall. The overall magnetic strengths of DRAGON, with maximum axial fields of 2.7 T at the injection and 1.3 T at the extraction, are very similar to those of SECRAL operating at 18 GHz and hopefully its performance. The source solenoid magnets are cooled by medium evaporation at about 50 C. In addition, the source is thickly insulated for beam extraction at 50 kV and higher voltage up to 100 kV can be explored. This article will present the design details and discussions of this new ion source. It is followed by the associated poster. (authors)

  3. Effect of large volume paracentesis on plasma volume--a cause of hypovolemia

    International Nuclear Information System (INIS)

    Kao, H.W.; Rakov, N.E.; Savage, E.; Reynolds, T.B.

    1985-01-01

    Large volume paracentesis, while effectively relieving symptoms in patients with tense ascites, has been generally avoided due to reports of complications attributed to an acute reduction in intravascular volume. Measurements of plasma volume in these subjects have been by indirect methods and have not uniformly confirmed hypovolemia. We have prospectively evaluated 18 patients (20 paracenteses) with tense ascites and peripheral edema due to chronic liver disease undergoing 5 liter paracentesis for relief of symptoms. Plasma volume pre- and postparacentesis was assessed by a 125 I-labeled human serum albumin dilution technique as well as by the change in hematocrit and postural blood pressure difference. No significant change in serum sodium, urea nitrogen, hematocrit or postural systolic blood pressure difference was noted at 24 or 48 hr after paracentesis. Serum creatinine at 24 hr after paracentesis was unchanged but a small but statistically significant increase in serum creatinine was noted at 48 hr postparacentesis. Plasma volume changed -2.7% (n = 6, not statistically significant) during the first 24 hr and -2.8% (n = 12, not statistically significant) during the 0- to 48-hr period. No complications from paracentesis were noted. These results suggest that 5 liter paracentesis for relief of symptoms is safe in patients with tense ascites and peripheral edema from chronic liver disease

  4. Statistics on the parameters of nonisothermal ionospheric plasma in large mesospheric electric fields

    Science.gov (United States)

    Martynenko, S.; Rozumenko, V.; Tyrnov, O.; Manson, A.; Meek, C.

    The large V/m electric fields inherent in the mesosphere play an essential role in lower ionospheric electrodynamics. They must be the cause of large variations in the electron temperature and the electron collision frequency at D region altitudes, and consequently the ionospheric plasma in the lower part of the D region undergoes a transition into a nonisothermal state. This study is based on the databases on large mesospheric electric fields collected with the 2.2-MHz radar of the Institute of Space and Atmospheric Studies, University of Saskatchewan, Canada (52°N geographic latitude, 60.4°N geomagnetic latitude) and with the 2.3-MHz radar of the Kharkiv V. Karazin National University (49.6°N geographic latitude, 45.6°N geomagnetic latitude). The statistical analysis of these data is presented in Meek, C. E., A. H. Manson, S. I. Martynenko, V. T. Rozumenko, O. F. Tyrnov, Remote sensing of mesospheric electric fields using MF radars, Journal of Atmospheric and Solar-Terrestrial Physics, in press. The large mesospheric electric fields is experimentally established to follow a Rayleigh distribution in the interval 0 plasma.

  5. Experimental results of laser wakefield acceleration using a femtosecond terawatt laser pulse

    International Nuclear Information System (INIS)

    Kando, Masaki; Ahn, Hyeyoung; Dewa, Hideki

    1999-01-01

    Laser wakefield acceleration (LWA) experiments have been carried out in an underdense plasma driven by a 2 TW, 90 fs laser pulse synchronized with a 17 MeV RF linac electron injector at 10 Hz. Around optimum plasma densities for LWA, we have observed electrons accelerated to 35 MeV. Wakefield excitation has been confirmed by measuring the electron density oscillation with a frequency domain interferometer. At plasma densities higher than the optimum density, we have also observed high energy electrons over 100 MeV up to 200 MeV. (author)

  6. Large-amplitude dust acoustic shocklets in non-Maxwellian dusty plasmas

    Science.gov (United States)

    Ali, S.; Naeem, Ismat; Mirza, Arshad M.

    2017-10-01

    The formation and propagation of fully nonlinear dust-acoustic (DA) waves and shocks are studied in a non-Maxwellian thermal dusty plasma which is composed of Maxwellian electrons and nonthermal energetic ions with a neutralizing background of negatively charged dust grains. For this purpose, we have solved dust dynamical equations along with quasineutrality equation by using a diagonalization matrix technique. A set of two characteristic wave equations is obtained, which admits both analytical and numerical solutions. Taylor expansion in the small-amplitude limit ( Φ ≪ 1 ) leads to nonlinear effective phase and shock speeds accounting for nonthermal energetic ions. It is numerically shown that DA pulses can be developed into DA shocklets involving the negative electrostatic potential, dust fluid velocity, and dust number density. These structures are significantly influenced by the ion-nonthermality, dust thermal correction, and temporal variations. However, the amplitudes of solitary and shock waves are found smaller in case of Cairns-distributed ions as compared to Kappa-distributed ions due to smaller linear and nonlinear effective phase speeds that cause smaller nonlinearity effects. The present results should be useful for understanding the nonlinear characteristics of large-amplitude DA excitations and nonstationary shocklets in a laboratory non-Maxwellian dusty plasma, where nonthermal energetic ions are present in addition to Maxwellian electrons.

  7. Modeling of large amplitude plasma blobs in three-dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Angus, Justin R. [Naval Research Laboratory, 4555 Overlook Avenue, Washington, DC 20375 (United States); Umansky, Maxim V. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

    2014-01-15

    Fluctuations in fusion boundary and similar plasmas often have the form of filamentary structures, or blobs, that convectively propagate radially. This may lead to the degradation of plasma facing components as well as plasma confinement. Theoretical analysis of plasma blobs usually takes advantage of the so-called Boussinesq approximation of the potential vorticity equation, which greatly simplifies the treatment analytically and numerically. This approximation is only strictly justified when the blob density amplitude is small with respect to that of the background plasma. However, this is not the case for typical plasma blobs in the far scrape-off layer region, where the background density is small compared to that of the blob, and results obtained based on the Boussinesq approximation are questionable. In this report, the solution of the full vorticity equation, without the usual Boussinesq approximation, is proposed via a novel numerical approach. The method is used to solve for the evolution of 2D and 3D plasma blobs in a regime where the Boussinesq approximation is not valid. The Boussinesq solution under predicts the cross field transport in 2D. However, in 3D, for parameters typical of current tokamaks, the disparity between the radial cross field transport from the Boussinesq approximation and full solution is virtually non-existent due to the effects of the drift wave instability.

  8. Modeling of large amplitude plasma blobs in three-dimensions

    International Nuclear Information System (INIS)

    Angus, Justin R.; Umansky, Maxim V.

    2014-01-01

    Fluctuations in fusion boundary and similar plasmas often have the form of filamentary structures, or blobs, that convectively propagate radially. This may lead to the degradation of plasma facing components as well as plasma confinement. Theoretical analysis of plasma blobs usually takes advantage of the so-called Boussinesq approximation of the potential vorticity equation, which greatly simplifies the treatment analytically and numerically. This approximation is only strictly justified when the blob density amplitude is small with respect to that of the background plasma. However, this is not the case for typical plasma blobs in the far scrape-off layer region, where the background density is small compared to that of the blob, and results obtained based on the Boussinesq approximation are questionable. In this report, the solution of the full vorticity equation, without the usual Boussinesq approximation, is proposed via a novel numerical approach. The method is used to solve for the evolution of 2D and 3D plasma blobs in a regime where the Boussinesq approximation is not valid. The Boussinesq solution under predicts the cross field transport in 2D. However, in 3D, for parameters typical of current tokamaks, the disparity between the radial cross field transport from the Boussinesq approximation and full solution is virtually non-existent due to the effects of the drift wave instability

  9. Optimization of the plasma parameters for the high current and uniform large-scale pulse arc ion source of the VEST-NBI system

    International Nuclear Information System (INIS)

    Jung, Bongki; Park, Min; Heo, Sung Ryul; Kim, Tae-Seong; Jeong, Seung Ho; Chang, Doo-Hee; Lee, Kwang Won; In, Sang-Ryul

    2016-01-01

    Highlights: • High power magnetic bucket-type arc plasma source for the VEST NBI system is developed with modifications based on the prototype plasma source for KSTAR. • Plasma parameters in pulse duration are measured to characterize the plasma source. • High plasma density and good uniformity is achieved at the low operating pressure below 1 Pa. • Required ion beam current density is confirmed by analysis of plasma parameters and results of a particle balance model. - Abstract: A large-scale hydrogen arc plasma source was developed at the Korea Atomic Energy Research Institute for a high power pulsed NBI system of VEST which is a compact spherical tokamak at Seoul national university. One of the research target of VEST is to study innovative tokamak operating scenarios. For this purpose, high current density and uniform large-scale pulse plasma source is required to satisfy the target ion beam power efficiently. Therefore, optimizing the plasma parameters of the ion source such as the electron density, temperature, and plasma uniformity is conducted by changing the operating conditions of the plasma source. Furthermore, ion species of the hydrogen plasma source are analyzed using a particle balance model to increase the monatomic fraction which is another essential parameter for increasing the ion beam current density. Conclusively, efficient operating conditions are presented from the results of the optimized plasma parameters and the extractable ion beam current is calculated.

  10. Development of net-current free heliotron plasmas in the Large Helical Device

    International Nuclear Information System (INIS)

    Komori, A.; Yamada, H.; Kaneko, O.; Kawahata, K.; Mutoh, T.; Ohyabu, N.; Imagawa, S.; Ida, K.; Nagayama, Y.; Shimozuma, T.; Watanabe, K.Y.; Mito, T.; Kobayashi, M.; Nagaoka, K.; Sakamoto, R.; Ohdachi, S.; Sakakibara, S.; Ashikawa, N.; Igami, H.; Kasahara, H.; Kubo, S.; Kumazawa, R.; Nishiura, M.; Masuzaki, S.; Tanaka, K.; Toi, K.; Yoshinuma, M.; Narushima, Y.; Tamura, N.; Saito, K.; Seki, T.; Sudo, S.; Tanaka, H.; Tokuzawa, T.; Yanagi, N.; Yokoyama, M.; Yoshimura, Y.; Akiyama, T.; Chikaraishi, H.; Emoto, M.; Funaba, H.; Goncharov, P.; Goto, M.; Ichiguchi, K.; Ido, T.; Ikeda, K.; Yoshida, N.; Inagaki, S.; Idei, H.; Feng, Y.; Weller, A.; Fukuda, T.; Mitarai, O.; Murakami, S.; Nakamura, Y.; Hino, T.; Ohno, N.; Okamura, T.; Iio, S.; Chowdhuri, M.; Ezumi, N.; Garcia, L.; Ichimura, M.; Irie, M.; Isayama, Akihiko; Iwamae, Atsushi; Takenaga, Hidenobu; Urano, Hajime

    2008-10-01

    Remarkable progress in the physical parameters of net-current free plasmas has been made in the Large Helical Device (LHD) since the last Fusion Energy Conference in Chengdu, 2006 (O. Motojima et al., Nucl. Fusion 47 (2007) S668). The beta value reached 5 % and a high beta state beyond 4.5% from the diamagnetic measurement has been maintained for longer than 100 times the energy confinement time. The density and temperature regimes also have been extended. The central density has exceeded 1.0x10 21 m -3 due to the formation of an Internal Diffusion Barrier (IDB). The ion temperature has reached 6.8 keV at the density of 2x10 19 m -3 , which is associated with the suppression of ion heat conduction loss. Although these parameters have been obtained in separated discharges, each fusion-reactor relevant parameter has elucidated the potential of net-current free heliotron plasmas. Diversified studies in recent LHD experiments are reviewed in this paper. (author)

  11. Electron plasma waves and plasma resonances

    International Nuclear Information System (INIS)

    Franklin, R N; Braithwaite, N St J

    2009-01-01

    In 1929 Tonks and Langmuir predicted of the existence of electron plasma waves in an infinite, uniform plasma. The more realistic laboratory environment of non-uniform and bounded plasmas frustrated early experiments. Meanwhile Landau predicted that electron plasma waves in a uniform collisionless plasma would appear to be damped. Subsequent experimental work verified this and revealed the curious phenomenon of plasma wave echoes. Electron plasma wave theory, extended to finite plasmas, has been confirmed by various experiments. Nonlinear phenomena, such as particle trapping, emerge at large amplitude. The use of electron plasma waves to determine electron density and electron temperature has not proved as convenient as other methods.

  12. EDITORIAL: Plasma jets and plasma bullets Plasma jets and plasma bullets

    Science.gov (United States)

    Kong, M. G.; Ganguly, B. N.; Hicks, R. F.

    2012-06-01

    Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma plume gives rise to a strong interaction with its surrounding environment, and the interaction alters the properties of both the plasma and the environment, often in a nonlinear and dynamic fashion. The plasma is therefore not confined by defined physical walls, thus extending opportunities for material treatment applications as well as bringing in new challenges in science and technology associated with complex open-boundary problems. Some of the most common examples may be found in dense plasmas with very high dissipation of externally supplied energy (e.g. in electrical, optical or thermal forms) and often in or close to thermal equilibrium. For these dense plasmas, their characteristics are determined predominantly by strong physical forces of different fields, such as electrical, magnetic, thermal, shock wave, and their nonlinear interactions [1]. Common to these dense plasma plumes are significant macroscopic plasma movement and considerable decomposition of solid materials (e.g. vaporization). Their applications are numerous and include detection of elemental traces, synthesis of high-temperature materials and welding, laser--plasma interactions, and relativistic jets in particle accelerators and in space [2]-[4]. Scientific challenges in the understanding of plasma jets are exciting and multidisciplinary, involving interweaving transitions of all four states of matter, and their technological applications are wide-ranging and growing rapidly. Using the Web of Science database, a search for journal papers on non-fusion plasma jets reveals that a long initial phase up

  13. Design and fabrication of a large rectangular magnetic cusp plasma source for high intensity neutral beam injectors

    International Nuclear Information System (INIS)

    Biagi, L.A.; Berkner, K.H.; Ehlers, K.W.; Paterson, J.A.; Porter, J.R.

    1979-11-01

    The design and fabrication techniques for a large, rectangular magnetic bucket plasma source are described. This source is compatible with the accelerator structures for the TFTR and DIII neutral-beam systems

  14. Bursty fluctuation characteristics in SOL/divertor plasmas of Large Helical Device

    International Nuclear Information System (INIS)

    Ohno, N.; Masuzaki, S.; Morisaki, T.; Ohyabu, N.; Komori, A.; Budaev, V.P.; Miyoshi, H.; Takamura, S.

    2006-10-01

    Bursty electrostatic fluctuation in the scrape off layer (SOL) and the divertor region of the Large Helical Device (LHD) have been investigated by using a Langmuir probe array on a divertor plate and a reciprocating Langmuir probe. Large positive bursty events were often observed in the ion saturation current measured with a divertor probe near the divertor leg at which the magnetic line of force connected to the area of a low-field side with a short connection length. Condition averaging result of the positive bursty events indicates the intermittent feature with a rapid increase and a slow decay is similar to that of plasma blobs observed in tokamaks. On the other hand, at a striking point with a long connection length, negative spikes were observed. Statistical analysis based on probability distribution function (PDF) was employed to investigate the bursty fluctuation property. The observed scaling exponents disagree with the predictions for the self-organized criticality (SOC) paradigm. (author)

  15. Large amplitude ion-acoustic solitary waves and double layers in multicomponent plasma with positrons

    International Nuclear Information System (INIS)

    Sabry, R.

    2009-01-01

    A finite amplitude theory for ion-acoustic solitary waves and double layers in multicomponent plasma consisting of hot positrons, cold ions, and electrons with two-electron temperature distributions is presented. Conditions are obtained under which large amplitude stationary ion-acoustic solitary waves and double layers can exist. For the physical parameters of interest, the ion-acoustic solitary wave (double layers) profiles and the relationship between the maximum soliton (double layers) amplitude and the Mach number are found. Also, we have presented the region of existence of the large amplitude ion-acoustic waves by analyzing the structure of the pseudopotential. For the selected range of parameters, it is found that only positive solitary waves and double layers can exist. An analysis for the small amplitude limit through the Sagdeev pseudopotential analysis and the reductive perturbation theory shows the existence of positive and negative ion-acoustic solitary waves and double layers. The effects of positron concentration and temperature ratio on the characteristics of the solitary ion-acoustic waves and double layers (namely, the amplitude and width) are discussed in detail. The relevance of this investigation to space and laboratory plasmas is pointed out.

  16. High performance imaging of relativistic soft X-ray harmonics by sub-micron resolution LiF film detectors

    Energy Technology Data Exchange (ETDEWEB)

    Pikuz, Tatiana; Faenov, Anatoly [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kizugawa, Kyoto 619-0215 (Japan); Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); Pirozhkov, Alexander; Esirkepov, Timur; Koga, James; Nakamura, Tatsufumi; Bulanov, Sergei; Fukuda, Yuji; Hayashi, Yukio; Kotaki, Hideyuki; Kando, Masaki [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kizugawa, Kyoto 619-0215 (Japan); Astapov, Artem; Pikuz, Sergey Jr. [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); Klushin, Georgy [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); International Laser Center of M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Nagorskiy, Nikolai; Magnitskiy, Sergei [International Laser Center of M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Kato, Yoshiaki [The Graduate School for the Creation of New Photonics Industries, Hamamatsu, Shizuoka (Japan)

    2012-12-15

    The spectrum variation and the coherent properties of the high-order harmonics (HOH) generated by an oscillating electron spikes formed at the joint of the boundaries of a cavity and a bow wave, which are created by a relativistically self-focusing laser in underdense gas jet plasma, are investigated. This new mechanism for HOH generation efficiently produces emission from ultraviolet up to the XUV ''water window'' spectral range. To characterize such source in the wide spectral range a diffraction imaging technique is applied. High spatial resolution EUV and soft X-ray LiF film detector have been used for precise measurements of diffraction patterns. The measurements under observation angle of 8 to the axis of laser beam propagation have been performed. The diffraction patterns were observed on the detector clearly, when the square mesh was placed at the distance of 500 mm from the output of plasma and at the distance of 27.2 mm in front of the detector. It is shown that observed experimental patterns are well consistent with modeled ones for theoretical HOH spectrum, provided by particle-in-cell simulations of a relativistic-irradiance laser pulse interaction with underdense plasma (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Plasma properties in a large-volume, cylindrical and asymmetric radio-frequency capacitively coupled industrial-prototype reactor

    International Nuclear Information System (INIS)

    Lazović, Saša; Puač, Nevena; Spasić, Kosta; Malović, Gordana; Petrović, Zoran Lj; Cvelbar, Uroš; Mozetič, Miran; Radetić, Maja

    2013-01-01

    We have developed a large-volume low-pressure cylindrical plasma reactor with a size that matches industrial reactors for treatment of textiles. It was shown that it efficiently produces plasmas with only a small increase in power as compared with a similar reactor with 50 times smaller volume. Plasma generated at 13.56 MHz was stable from transition to streamers and capable of long-term continuous operation. An industrial-scale asymmetric cylindrical reactor of simple design and construction enabled good control over a wide range of active plasma species and ion concentrations. Detailed characterization of the discharge was performed using derivative, Langmuir and catalytic probes which enabled determination of the optimal sets of plasma parameters necessary for successful industry implementation and process control. Since neutral atomic oxygen plays a major role in many of the material processing applications, its spatial profile was measured using nickel catalytic probe over a wide range of plasma parameters. The spatial profiles show diffusion profiles with particle production close to the powered electrode and significant wall losses due to surface recombination. Oxygen atom densities range from 10 19 m −3 near the powered electrode to 10 17 m −3 near the wall. The concentrations of ions at the same time are changing from 10 16 to the 10 15 m −3 at the grounded chamber wall. (paper)

  18. Large enhanced dielectric permittivity in polyaniline passivated core-shell nano magnetic iron oxide by plasma polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Joy, Lija K.; Sooraj, V.; Sethulakshmi, N.; Anantharaman, M. R., E-mail: mraiyer@yahoo.com [Department of Physics, Cochin University of Science and Technology, Cochin-682022, Kerala (India); Sajeev, U. S. [Department of Physics, Government College, Kottayam-686613, Kerala (India); Nair, Swapna S. [Department of Physics, School of Mathematical and Physical Sciences, Central University of Kerala, Kasargode-671123, Kerala (India); Narayanan, T. N. [CSIR-Central Electrochemical Research Institute, Karaikkudi-630006, Tamil Nadu (India); Ajayan, P. M. [Department of Material Science and Nano Engineering, Rice University, 6100 Main Street, Houston, Texas 7700 (United States)

    2014-03-24

    Commercial samples of Magnetite with size ranging from 25–30 nm were coated with polyaniline by using radio frequency plasma polymerization to achieve a core shell structure of magnetic nanoparticle (core)–Polyaniline (shell). High resolution transmission electron microscopy images confirm the core shell architecture of polyaniline coated iron oxide. The dielectric properties of the material were studied before and after plasma treatment. The polymer coated magnetite particles exhibited a large dielectric permittivity with respect to uncoated samples. The dielectric behavior was modeled using a Maxwell–Wagner capacitor model. A plausible mechanism for the enhancement of dielectric permittivity is proposed.

  19. Exploiting multi-scale parallelism for large scale numerical modelling of laser wakefield accelerators

    International Nuclear Information System (INIS)

    Fonseca, R A; Vieira, J; Silva, L O; Fiuza, F; Davidson, A; Tsung, F S; Mori, W B

    2013-01-01

    A new generation of laser wakefield accelerators (LWFA), supported by the extreme accelerating fields generated in the interaction of PW-Class lasers and underdense targets, promises the production of high quality electron beams in short distances for multiple applications. Achieving this goal will rely heavily on numerical modelling to further understand the underlying physics and identify optimal regimes, but large scale modelling of these scenarios is computationally heavy and requires the efficient use of state-of-the-art petascale supercomputing systems. We discuss the main difficulties involved in running these simulations and the new developments implemented in the OSIRIS framework to address these issues, ranging from multi-dimensional dynamic load balancing and hybrid distributed/shared memory parallelism to the vectorization of the PIC algorithm. We present the results of the OASCR Joule Metric program on the issue of large scale modelling of LWFA, demonstrating speedups of over 1 order of magnitude on the same hardware. Finally, scalability to over ∼10 6 cores and sustained performance over ∼2 P Flops is demonstrated, opening the way for large scale modelling of LWFA scenarios. (paper)

  20. Microwave Production of Steady State Large Volume Air Plasmas

    National Research Council Canada - National Science Library

    Brandenburg, John

    1999-01-01

    ...) and these plasmas persist for hundreds of milliseconds after power is turned off. These plasmas can be made in an inexpensive and easy to build apparatus based around a microwave oven operating at approximately 1kW and 2.45GHz...

  1. Quiescent plasma machine for plasma investigation

    International Nuclear Information System (INIS)

    Ferreira, J.L.

    1993-01-01

    A large volume quiescent plasma device is being developed at INPE to study Langmuir waves and turbulence generated by electron beams (E b ≤ 500 e V) interacting with plasma. This new quiescent plasma machine was designed to allow the performance of several experiments specially those related with laboratory space plasma simulation experiments. Current-driven instabilities and related phenomena such as double-layers along magnetic field lines are some of the many experiments planned for this machine. (author)

  2. Simulation of impurity transport in the peripheral plasma due to the emission of dust in long pulse discharges on the Large Helical Device

    Directory of Open Access Journals (Sweden)

    M. Shoji

    2017-08-01

    Full Text Available Two different plasma termination processes by dust emission were observed in long pulse discharges in the Large Helical Device. One is a plasma termination caused by large amounts of carbon dust released from a lower divertor region. The other is termination caused by stainless steel (iron dust emission from the surface of a helical coil can. The effect of the dust emission on the sustainment of the long pulse discharges are investigated using a three-dimensional edge plasma transport code (EMC3-EIRENE coupled with a dust transport code (DUSTT. The simulation shows that the plasma is more influenced by the iron dust emission from the helical coil can than by the carbon dust emission from the divertor region. The simulation revealed that the plasma flow in divertor legs is quite effective for preventing dust from terminating the long pulse discharges.

  3. Theoretical interpretations of enhanced laser light absorption

    International Nuclear Information System (INIS)

    Kruer, W.L.

    1975-01-01

    Intense laser light is not efficiently absorbed classically but can be absorbed by its conversion to electron plasma waves near the critical density. The physical mechanisms for this conversion are discussed, and some simple estimates for heating by plasma waves are applied to some recent experiments. Several effects which strongly influence the absorption of high intensity light are emphasized, including a nonlinear steepening of the plasma density profile which is demonstrated in computer simulations. Finally the possibility of an induced reflection of laser light due to instabilities in the underdense plasma before the critical density is also discussed. Such stimulated reflection can be particularly important in plasmas with very long density gradients. (U.S.)

  4. Reflectivity of stimulated back scattering in a homogeneous-slab medium in the case of negligible pump-wave damping

    International Nuclear Information System (INIS)

    Cho, G.S.; Cho, B.H.

    1981-01-01

    As to the backscatter instability which is one of nonlinear three-wave resonant interactions, the reflectivity(r) in the case of homogeneous-slab medium is calculated, assuming all the three wavepackets negligible damping caused by medium. The expression has turned out such that r = tanh 2 KAsub(p)L, where K, Asub(p), and L are the constant coupling coefficient, the constant pump-wave amplitude, and the thickness of the medium engaged in the interaction each. When this result is interpreted in terms of the stimulated Brillouin back-scattering in a so-called underdense plasma in controlled fusion, we find the reflectivity twice as large as that by others in the limit of large pump-wave damping, and unfitting to former experiments in the independence on the incident laser-light intensity. We see the incompatibility rise chiefly from neglecting the damping of pump-wave in the plasma. In contrast to the former results by others in the limit of large pump-wave damping, our result might be regarded as that for cases of negligible pump-wave damping, in general stimulated back-scattering phenomena. (author)

  5. FOREWORD: Workshop on Large Amplitude Waves and Fields in Plasmas, sponsored by the Commission of the European Communities

    Science.gov (United States)

    Bingham, R.; De Angelis, U.; Shukla, P. K.; Stenflo, L.

    1990-01-01

    During the last decade considerable progress has been made in the area of nonlinear plasma wave phenomena and their applications. In order to exhibit the present state-of-art in this field, a one-week (22-26 May) workshop on Large Amplitude Waves and Fields was organized at the International Centre for Theoretical Physics (ICTP), Trieste, Italy, during the bi-yearly activity of the Spring College on Plasma Physics (15 May-9 June, 1989). Most of the invited lectures are published in this Topical Issue of Physica Scripta so that scientists working, or who want to enter the field of nonlinear plasma wave theory, can find out what has been achieved and what are the current research trends in this area. The material included here consists of general plasma wave theory, results of computer simulations, and experimental verifications. Without going into any detail, we shall just highlight the topics and the general features of the lectures contained in these proceedings. Various aspects of the excitation, propagation and interaction of nonlinear waves in plasmas are reviewed. Their relevance to plasma-based beat wave accelerators, short pulse laser and particle beam wake-field accelerators, plasma lenses, laser fusion and ionospheric modification experiments is discussed. Some introductory lectures present the general physics of nonlinear plasma waves including the saturation mechanisms and wave breaking conditions for both non-relativistic and relativistic nonlinearities. Three wave and four wave processes which include stimulated Raman, Brillouin and Compton scattering, modulational instabilities, self-focusing and collapse of the waves are discussed, emphasizing the important effects due to the relativistic electron mass variation and ponderomotive force. Detailed numerical studies of the interaction of high frequency plasma waves with low frequency density fluctuations described by the Zakharov equations show the localization of the high frequency field in density

  6. Final report for the NSF/DOE partnership in basic plasma science grant DE-FG02-06ER54906 'Laser-driven collisionless shocks in the Large Plasma Device'™

    International Nuclear Information System (INIS)

    Niemann, Christoph; Gekelman, W.; Winske, D.; Larsen, D.

    2012-01-01

    We have performed several thousand high-energy laser shots in the LAPD to investigate the dynamics of an exploding laser-produced plasma in a large ambient magneto-plasma. Debris-ions expanding at super-Alfvenic velocity (up to MA=1.5) expel the ambient magnetic field, creating a large (> 20 cm) diamagnetic cavity. We observed field compressions of up to B/B 0 = 1.5 at the edge of the bubble, consistent with the MHD jump conditions, as well as localized electron heating at the edge of the bubble. Two-dimensional hybrid simulations reproduce these measurements well and show that the majority of the ambient ions are energized by the magnetic piston to super-Alfvenic speeds and swept outside the bubble volume. Nonlinear shear-Alfven waves (δB/B 0 > 25%) are radiated from the cavity with a coupling efficiency of 70% from magnetic energy in the bubble to the wave. While the data is consistent with a weak magneto-sonic shock, the experiments were severely limited by the low ambient plasma densities (10 12 cm -3 ). 2D hybrid simulations indicate that future experiments with the new LAPD plasma source and densities in excess of 10 13 cm -3 will drive full-blown collisionless shocks with MA>10 over several c/wpi and shocked Larmor radii. In a separate experiment at the LANL Trident laser facility we have performed a proof-of-principle experiment at higher densities to demonstrate key elements of collisionless shocks in laser-produced magnetized plasmas with important implications to NIF. Simultaneously we have upgraded the UCLA glass-laser system by adding two large amplitude disk amplifiers from the NOVA laser and boost the on-target energy from 30 J to up to 1 kJ, making this one of the world's largest university-scale laser systems. We now have the infrastructure in place to perform novel and unique high-impact experiments on collision-less shocks at the LAPD

  7. Open loop control of filament heating power supply for large volume plasma device

    Energy Technology Data Exchange (ETDEWEB)

    Sugandhi, R., E-mail: ritesh@ipr.res.in [Institute for Plasma Research, Gandhinagar, Gujarat 382428 (India); Homi Bhabha National Institute, Mumbai 400094 (India); Srivastava, P.K.; Sanyasi, A.K. [Homi Bhabha National Institute, Mumbai 400094 (India); Srivastav, Prabhakar [Institute for Plasma Research, Gandhinagar, Gujarat 382428 (India); Homi Bhabha National Institute, Mumbai 400094 (India); Awasthi, L.M., E-mail: kushagra.lalit@gmail.com [Institute for Plasma Research, Gandhinagar, Gujarat 382428 (India); Homi Bhabha National Institute, Mumbai 400094 (India); Mattoo, S.K. [Homi Bhabha National Institute, Mumbai 400094 (India)

    2017-02-15

    A power supply (20 V, 10 kA) for powering the filamentary cathode has been procured, interfaced and integrated with the centralized control system of Large Volume Plasma Device (LVPD). Software interface has been developed on the standard Modbus RTU communication protocol. It facilitates the dashboard for configuration, on line status monitoring, alarm management, data acquisition, synchronization and controls. It has been tested for stable operation of the power supply for the operational capabilities. The paper highlights the motivation, interface description, implementation and results obtained.

  8. Open loop control of filament heating power supply for large volume plasma device

    International Nuclear Information System (INIS)

    Sugandhi, R.; Srivastava, P.K.; Sanyasi, A.K.; Srivastav, Prabhakar; Awasthi, L.M.; Mattoo, S.K.

    2017-01-01

    A power supply (20 V, 10 kA) for powering the filamentary cathode has been procured, interfaced and integrated with the centralized control system of Large Volume Plasma Device (LVPD). Software interface has been developed on the standard Modbus RTU communication protocol. It facilitates the dashboard for configuration, on line status monitoring, alarm management, data acquisition, synchronization and controls. It has been tested for stable operation of the power supply for the operational capabilities. The paper highlights the motivation, interface description, implementation and results obtained.

  9. Plasma accelerators

    International Nuclear Information System (INIS)

    Bingham, R.; Angelis, U. de; Johnston, T.W.

    1991-01-01

    Recently attention has focused on charged particle acceleration in a plasma by a fast, large amplitude, longitudinal electron plasma wave. The plasma beat wave and plasma wakefield accelerators are two efficient ways of producing ultra-high accelerating gradients. Starting with the plasma beat wave accelerator (PBWA) and laser wakefield accelerator (LWFA) schemes and the plasma wakefield accelerator (PWFA) steady progress has been made in theory, simulations and experiments. Computations are presented for the study of LWFA. (author)

  10. Plasma free amino acid profiles evaluate risk of metabolic syndrome, diabetes, dyslipidemia, and hypertension in a large Asian population

    OpenAIRE

    Yamaguchi, Natsu; Mahbub, MH; Takahashi, Hidekazu; Hase, Ryosuke; Ishimaru, Yasutaka; Sunagawa, Hiroshi; Amano, Hiroki; Kobayashi- Miura, Mikiko; Kanda, Hideyuki; Fujita, Yasuyuki; Yamamoto, Hiroshi; Yamamoto, Mai; Kikuchi, Shinya; Ikeda, Atsuko; Takasu, Mariko

    2017-01-01

    Background Recently, the association of plasma free amino acid (PFAA) profile and lifestyle-related diseases has been reported. However, few studies have been reported in large Asian populations, about the usefulness of PFAAs for evaluating disease risks. We examined the ability of PFAA profiles to evaluate lifestyle-related diseases in so far the largest Asian population. Methods We examined plasma concentrations of 19 amino acids in 8589 Japanese subjects, and determined the association wit...

  11. Immunoglobulin G levels during collection of large volume plasma for fractionation.

    Science.gov (United States)

    Burkhardt, Thomas; Rothe, Remo; Moog, Rainer

    2017-06-01

    There is a need of comprehensive work dealing with the quality of plasma for fractionation with respect to the IgG content as today most plasma derivates are used to treat patients with immunodeficiencies and autoimmune disorders. Therefore, a prospective study was carried out to analyse IgG levels before plasmapheresis and every 200ml collected plasma. Fifty-four experienced plasmapheresis donors were recruited for subsequent 850ml plasmapheresis using the Aurora Plasmapheresis System. Donorś peripheral blood counts were analysed before and after plasmapheresis using an electronic counter. Total protein, IgG and citrate were measured turbidometrically before, during and after apheresis as well as in the plasma product. Furthermore, platelets, red and white blood cells were analysed as parameters of product quality. An average of 2751±247ml blood was processed in 47±6min. The collected plasma volume was 850±1mL and citrate consumption was 177±15mL. A continuous drop of donors' IgG level was observed during plasmapheresis. The drop was 13% of the IgG baseline value at 800mL collected plasma. Total protein, IgG and cell counts of the plasma product met current guidelines of plasma for fractionation. Donors' IgG levels during apheresis showed a steady decrease without compromising the quality of plasma product. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Plasma characteristics of long-pulse discharges heated by neutral beam injection in the Large Helical Device

    Science.gov (United States)

    Takeiri, Y.; Nakamura, Y.; Noda, N.; Osakabe, M.; Kawahata, K.; Oka, Y.; Kaneko, O.; Tsumori, K.; Sato, M.; Mutoh, T.; Shimozuma, T.; Goto, M.; Ida, K.; Inagaki, S.; Kado, S.; Masuzaki, S.; Morita, S.; Nagayama, Y.; Narihara, K.; Peterson, B. J.; Sakakibara, S.; Sato, K.; Shoji, M.; Tanaka, K.; de Vries, P. C.; Sudo, S.; Ohyabu, N.; Motojima, O.

    2000-02-01

    Long-pulse neutral beam injection heating has been achieved in the large helical device (LHD). Two different confinement states are observed for different averaged densities in the long-pulse plasmas. A quasi-steady-state plasma was sustained for 21 s with an injection power of 0.6 MW, where the central plasma temperature was around 1 keV with a line-averaged electron density of 0.3 × 1019 m-3 . The discharge duration can be so extended as to keep the plasma properties in the short-pulse discharge. The energy confinement time is nearly the same as that of the short-pulse discharge, which is 1.3 times as long as the international stellarator scaling ISS95. At higher densities, a relaxation oscillation phenomenon, observed as if the plasma would breathe, lasted for 20 s with a period of 1-2 s. The phenomenon is characterized with profile expansion and contraction of the electron temperature. The density oscillation is out of phase with the temperature oscillation and is related to the density clamping phenomenon. The observed plasma properties are shown in detail for the `breathing' oscillation phenomenon. Possible mechanisms for the breathing oscillation are also discussed, with a view of the screening effect near the last closed magnetic surface and the power balance between the heating and the radiation powers. The long-pulse heating results indicate unique characteristics of the LHD where no special feedback stabilization is required due to absence of disruption and no need for current drive.

  13. Early treatment with lyophilized plasma protects the brain in a large animal model of combined traumatic brain injury and hemorrhagic shock

    DEFF Research Database (Denmark)

    Imam, Ayesha M; Jin, Guang; Sillesen, Martin

    2013-01-01

    Combination of traumatic brain injury (TBI) and hemorrhagic shock (HS) can result in significant morbidity and mortality. We have previously shown that early administration of fresh frozen plasma (FFP) in a large animal model of TBI and HS reduces the size of the brain lesion as well as the assoc...... as the associated edema. However, FFP is a perishable product that is not well suited for use in the austere prehospital settings. In this study, we tested whether a shelf-stable, low-volume, lyophilized plasma (LSP) product was as effective as FFP.......Combination of traumatic brain injury (TBI) and hemorrhagic shock (HS) can result in significant morbidity and mortality. We have previously shown that early administration of fresh frozen plasma (FFP) in a large animal model of TBI and HS reduces the size of the brain lesion as well...

  14. The large-scale gravitational bias from the quasi-linear regime.

    Science.gov (United States)

    Bernardeau, F.

    1996-08-01

    It is known that in gravitational instability scenarios the nonlinear dynamics induces non-Gaussian features in cosmological density fields that can be investigated with perturbation theory. Here, I derive the expression of the joint moments of cosmological density fields taken at two different locations. The results are valid when the density fields are filtered with a top-hat filter window function, and when the distance between the two cells is large compared to the smoothing length. In particular I show that it is possible to get the generating function of the coefficients C_p,q_ defined by _c_=C_p,q_ ^p+q-2^ where δ({vec}(x)) is the local smoothed density field. It is then possible to reconstruct the joint density probability distribution function (PDF), generalizing for two points what has been obtained previously for the one-point density PDF. I discuss the validity of the large separation approximation in an explicit numerical Monte Carlo integration of the C_2,1_ parameter as a function of |{vec}(x)_1_-{vec}(x)_2_|. A straightforward application is the calculation of the large-scale ``bias'' properties of the over-dense (or under-dense) regions. The properties and the shape of the bias function are presented in details and successfully compared with numerical results obtained in an N-body simulation with CDM initial conditions.

  15. Specular Reflectivity and Hot-Electron Generation in High-Contrast Relativistic Laser-Plasma Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Gregory Elijah [The Ohio State Univ., Columbus, OH (United States)

    2013-01-01

    Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the cost of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic

  16. A novel synthesis method for large area metallic amorphous/nanocrystal films by the glow-discharge plasma technique

    International Nuclear Information System (INIS)

    Xu Jiang; Xu Zhong; Tao Jie; Liu Zili; Chen Zheyuan; Zhu Wenhui

    2007-01-01

    Two large-area metallic amorphous/nanocrystal films were prepared on AZ31 magnesium alloy and pure iron substrates by the double glow-discharge plasma technique. The formation mechanism of the novel amorphous films did not follow the established empirical rules for large glass-forming ability. The amorphous films were composed of binary alloys with a difference in the atomic diameter of alloying constituents of less than 12%, and an amorphous film of pure iron was successfully obtained

  17. Plasma physics and fusion plasma electrodynamics

    CERN Document Server

    Bers, Abraham

    2016-01-01

    Plasma is a ubiquitous state of matter at high temperatures. The electrodynamics of plasmas encompasses a large number of applications, from understanding plasmas in space and the stars, to their use in processing semiconductors, and their role in controlled energy generation by nuclear fusion. This book covers collective and single particle dynamics of plasmas for fully ionized as well as partially ionized plasmas. Many aspects of plasma physics in current fusion energy generation research are addressed both in magnetic and inertial confinement plasmas. Linear and nonlinear dynamics in hydrodynamic and kinetic descriptions are offered, making both simple and complex aspects of the subject available in nearly every chapter. The approach of dividing the basic aspects of plasma physics as "linear, hydrodynamic descriptions" to be covered first because they are "easier", and postponing the "nonlinear and kinetic descriptions" for later because they are "difficult" is abandoned in this book. For teaching purpose...

  18. Final report for the NSF/DOE partnership in basic plasma science grant DE-FG02-06ER54906 'Laser-driven collisionless shocks in the Large Plasma Device'

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, Christoph [UCLA, CA (United States); Gekelman, W. [UCLA, CA (United States); Winske, D. [LANL, NM (United States); Larsen, D. [LLNL, CA (United States)

    2012-12-14

    We have performed several thousand high-energy laser shots in the LAPD to investigate the dynamics of an exploding laser-produced plasma in a large ambient magneto-plasma. Debris-ions expanding at super-Alfvenic velocity (up to MA=1.5) expel the ambient magnetic field, creating a large (> 20 cm) diamagnetic cavity. We observed field compressions of up to B/B{sub 0} = 1.5 at the edge of the bubble, consistent with the MHD jump conditions, as well as localized electron heating at the edge of the bubble. Two-dimensional hybrid simulations reproduce these measurements well and show that the majority of the ambient ions are energized by the magnetic piston to super-Alfvenic speeds and swept outside the bubble volume. Nonlinear shear-Alfven waves ({delta}B/B{sub 0} > 25%) are radiated from the cavity with a coupling efficiency of 70% from magnetic energy in the bubble to the wave. While the data is consistent with a weak magneto-sonic shock, the experiments were severely limited by the low ambient plasma densities (10{sup 12} cm{sup -3}). 2D hybrid simulations indicate that future experiments with the new LAPD plasma source and densities in excess of 10{sup 13} cm{sup -3} will drive full-blown collisionless shocks with MA>10 over several c/wpi and shocked Larmor radii. In a separate experiment at the LANL Trident laser facility we have performed a proof-of-principle experiment at higher densities to demonstrate key elements of collisionless shocks in laser-produced magnetized plasmas with important implications to NIF. Simultaneously we have upgraded the UCLA glass-laser system by adding two large amplitude disk amplifiers from the NOVA laser and boost the on-target energy from 30 J to up to 1 kJ, making this one of the world’s largest university-scale laser systems. We now have the infrastructure in place to perform novel and unique high-impact experiments on collision-less shocks at the LAPD.

  19. Traveling magnetopause distortion related to a large-scale magnetosheath plasma jet: THEMIS and ground-based observations

    Science.gov (United States)

    Dmitriev, A. V.; Suvorova, A. V.

    2012-08-01

    Here, we present a case study of THEMIS and ground-based observations of the perturbed dayside magnetopause and the geomagnetic field in relation to the interaction of an interplanetary directional discontinuity (DD) with the magnetosphere on 16 June 2007. The interaction resulted in a large-scale local magnetopause distortion of an "expansion - compression - expansion" (ECE) sequence that lasted for ˜15 min. The compression was caused by a very dense, cold, and fast high-βmagnetosheath plasma flow, a so-called plasma jet, whose kinetic energy was approximately three times higher than the energy of the incident solar wind. The plasma jet resulted in the effective penetration of magnetosheath plasma inside the magnetosphere. A strong distortion of the Chapman-Ferraro current in the ECE sequence generated a tripolar magnetic pulse "decrease - peak- decrease" (DPD) that was observed at low and middle latitudes by some ground-based magnetometers of the INTERMAGNET network. The characteristics of the ECE sequence and the spatial-temporal dynamics of the DPD pulse were found to be very different from any reported patterns of DD interactions with the magnetosphere. The observed features only partially resembled structures such as FTE, hot flow anomalies, and transient density events. Thus, it is difficult to explain them in the context of existing models.

  20. Development of the plasma operational regime in the large helical device by the various wall conditioning methods

    International Nuclear Information System (INIS)

    Nishimura, K.; Ashikawa, N.; Masuzaki, S.; Miyazawa, J.; Sagara, A.; Goto, M.; Peterson, B.J.; Komori, A.; Noda, N.; Ida, K.; Kaneko, O.; Kawahata, K.; Kobuchi, T.; Kubo, S.; Morita, S.; Osakabe, M.; Sakakibara, S.; Sakamoto, R.; Sato, K.; Shimozuma, T.; Takeiri, Y.; Tanaka, K.; Motojima, O.

    2005-01-01

    Experiments in the large helical device have been developing since the first discharge in 1998. Baking at 95 deg C, electron cyclotron resonance discharge cleaning, glow discharge cleaning, titanium gettering and boronization were attempted for wall conditioning. Using these conditioning techniques, the partial pressures of the oxidized gases, such as H 2 O, CO and CO 2 , were reduced gradually and the plasma operational regime enlarged. The glow discharge cleaning with the various working gases, such as hydrogen, helium, neon and argon, was effective in increasing the plasma purity. By this method, we obtained a central ion temperature of 10 keV. Boronization, which was started from FY2001, was also effective in reducing the radiation losses from impurities and in enlarging the density operational regime. We obtained a plasma stored energy of 1.31 MJ and an electron density of 2.4 x 10 20 m -3

  1. Survey of high-voltage pulse technology suitable for large-scale plasma source ion implantation processes

    International Nuclear Information System (INIS)

    Reass, W.A.

    1994-01-01

    Many new plasma processes ideas are finding their way from the research lab to the manufacturing plant floor. These require high voltage (HV) pulse power equipment, which must be optimized for application, system efficiency, and reliability. Although no single HV pulse technology is suitable for all plasma processes, various classes of high voltage pulsers may offer a greater versatility and economy to the manufacturer. Technology developed for existing radar and particle accelerator modulator power systems can be utilized to develop a modern large scale plasma source ion implantation (PSII) system. The HV pulse networks can be broadly defined by two classes of systems, those that generate the voltage directly, and those that use some type of pulse forming network and step-up transformer. This article will examine these HV pulse technologies and discuss their applicability to the specific PSII process. Typical systems that will be reviewed will include high power solid state, hard tube systems such as crossed-field ''hollow beam'' switch tubes and planar tetrodes, and ''soft'' tube systems with crossatrons and thyratrons. Results will be tabulated and suggestions provided for a particular PSII process

  2. SUPPESSION OF LARGE EDGE LOCALIZED MODES IN HIGH CONFINEMENT DIII-D PLASMAS WITH A STOCHASTIC MAGNETIC BOUNDARY

    International Nuclear Information System (INIS)

    EVANS, TE; MOYER, RA; THOMAS, PR; WATKINS, JG; OSBORNE, TH; BOEDO, JA; FENSTERMACHER, ME; FINKEN, KH; GROEBNER, RJ; GROTH, M; HARRIS, JH; LAHAYE, RJ; LASNIER, CJ; MASUZAKI, S; OHYABU, N; PRETTY, D; RHODES, TL; REIMERDES, H; RUDAKOV, DL; SCHAFFER, MJ; WANG, G; ZENG, L.

    2003-01-01

    OAK-B135 A stochastic magnetic boundary, produced by an externally applied edge resonant magnetic perturbation, is used to suppress large edge localized modes (ELMs) in high confinement (H-mode) plasmas. The resulting H-mode displays rapid, small oscillations with a bursty character modulated by a coherent 130 Hz envelope. The H-mode transport barrier is unaffected by the stochastic boundary. The core confinement of these discharges is unaffected, despite a three-fold drop in the toroidal rotation in the plasma core. These results demonstrate that stochastic boundaries are compatible with H-modes and may be attractive for ELM control in next-step burning fusion tokamaks

  3. State of art data acquisition system for large volume plasma device

    International Nuclear Information System (INIS)

    Sugandhi, Ritesh; Srivastava, Pankaj; Sanyasi, Amulya Kumar; Srivastav, Prabhakar; Awasthi, Lalit Mohan; Mattoo, Shiban Krishna; Parmar, Vijay; Makadia, Keyur; Patel, Ishan; Shah, Sandeep

    2015-01-01

    The Large volume plasma device (LVPD) is a cylindrical device (ϕ = 2m, L = 3m) dedicated for carrying out investigations on plasma physics problems ranging from excitation of whistler structures to plasma turbulence especially, exploring the linear and nonlinear aspects of electron temperature gradient(ETG) driven turbulence, plasma transport over the entire cross section of LVPD. The machine operates in a pulsed mode with repetition cycle of 1 Hz and acquisition pulse length of duration of 15 ms, presently, LVPD has VXI data acquisition system but this is now in phasing out mode because of non-functioning of its various amplifier stages, expandability and unavailability of service support. The VXI system has limited capabilities to meet new experimental requirements in terms of numbers of channel (16), bit resolutions (8 bit), record length (30K points) and calibration support. Recently, integration of new acquisition system for simultaneous sampling of 40 channels of data, collected over multiple time scales with high speed is successfully demonstrated, by configuring latest available hardware and in-house developed software solutions. The operational feasibility provided by LabVIEW platform is not only for operating DAQ system but also for providing controls to various subsystems associated with the device. The new system is based on PXI express instrumentation bus and supersedes the existing VXI based data acquisition system in terms of instrumentation capabilities. This system has capability to measure 32 signals at 60 MHz sampling frequency and 8 signals with 1.25 GHz with 10 bit and 12 bit resolution capability for amplitude measurements. The PXI based system successfully addresses and demonstrate the issues concerning high channel count, high speed data streaming and multiple I/O modules synchronization. The system consists of chassis (NI 1085), 4 high sampling digitizers (NI 5105), 2 very high sampling digitizers (NI 5162), data streaming RAID drive (NI

  4. Raman scattering in a nearly resonant density ripple

    International Nuclear Information System (INIS)

    Barr, H.C.; Chen, F.F.

    1987-01-01

    Stimulated Raman scattering of light waves by an underdense plasma is affected by the presence of a density ripple caused by a simultaneously occurring stimulated Brillouin instability. The problem is treated kinetically for the particularly interesting case where the ripple has nearly the same wavelength as the plasma wave. The ripple is found to reduce the growth rate of the usual Raman instability but allows other decay modes to occur. Numerical results for the frequencies, growth rates, and k spectra of these modes are obtained. A physical explanation is given for a baffling result of the calculation. The physical picture is also of interest to particle acceleration by plasma waves

  5. A 5 kA pulsed power supply for inductive and plasma loads in large volume plasma device

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, P. K., E-mail: pkumar@ipr.res.in; Singh, S. K.; Sanyasi, A. K.; Awasthi, L. M., E-mail: kushagra.lalit@gmail.com; Mattoo, S. K. [Institute for Plasma Research, Gandhinagar (India)

    2016-07-15

    This paper describes 5 kA, 12 ms pulsed power supply for inductive load of Electron Energy Filter (EEF) in large volume plasma device. The power supply is based upon the principle of rapid sourcing of energy from the capacitor bank (2.8 F/200 V) by using a static switch, comprising of ten Insulated Gate Bipolar Transistors (IGBTs). A suitable mechanism is developed to ensure equal sharing of current and uniform power distribution during the operation of these IGBTs. Safe commutation of power to the EEF is ensured by the proper optimization of its components and by the introduction of over voltage protection (>6 kV) using an indigenously designed snubber circuit. Various time sequences relevant to different actions of power supply, viz., pulse width control and repetition rate, are realized through optically isolated computer controlled interface.

  6. Plasma technology

    International Nuclear Information System (INIS)

    Drouet, M.G.

    1984-03-01

    IREQ was contracted by the Canadian Electrical Association to review plasma technology and assess the potential for application of this technology in Canada. A team of experts in the various aspects of this technology was assembled and each team member was asked to contribute to this report on the applications of plasma pertinent to his or her particular field of expertise. The following areas were examined in detail: iron, steel and strategic-metals production; surface treatment by spraying; welding and cutting; chemical processing; drying; and low-temperature treatment. A large market for the penetration of electricity has been identified. To build up confidence in the technology, support should be provided for selected R and D projects, plasma torch demonstrations at full power, and large-scale plasma process testing

  7. X-ray line transfer in plasmas with large velocity gradients

    Czech Academy of Sciences Publication Activity Database

    Kerr, F.M.; Gouveia, A.; Lee, R. W.; Patel, P. K.; Renner, Oldřich; Rose, S. J.; Scott, H.A.; Wark, J. S.

    2005-01-01

    Roč. 298, 1-2 (2005), s. 171-178 ISSN 0004-640X Institutional research plan: CEZ:AV0Z10100523 Keywords : plasmas * radiation transport * high-power laserplasmas * high-power lasers Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.495, year: 2005

  8. TuFF3. Self-focusing in underdense ultraviolet laser-produced plasmas

    International Nuclear Information System (INIS)

    Tanaka, K.; Boswell, B.; Craxton, R.S.; Goldman, L.M.; Richardson, M.C.; Seka, W.; Short, R.W.; Soures, J.M.

    1984-01-01

    Ultraviolet laser-matter interaction processes are of considerable interest to laser fusion. Among these processes, filamentation (or self-focusing) is of particular importance, since it could prevent attainment of the illumination uniformity required for high target compression. In addition self-focusing may complicate the interpretation of target interaction experiments. Self-focusing has been studied experimentally by side-on x-ray pinhole camera photography and backscatter spectrometry. These results are compared with two-dimensional simulations using the hydro code SAGE, which is well suited to model thermal self-focusing (no ponderomotive forces are included in these simulations)

  9. Extension of operation regimes and investigation of three-dimensional current-less plasmas in the Large Helical Device

    International Nuclear Information System (INIS)

    Kaneko, O.

    2012-11-01

    The Large Helical Device (LHD) has shown the advantages of heliotron plasma for fusion reactor from operational point of view not only such as disruption free and steady state operation, but also as high density and stable high beta operation. Since the last Fusion Energy Conference in Daejon in 2010 (Yamada, 2011 Nucl. Fusion 51 094021), physical understanding as well as parameter improvement of net-current free helical plasmas has progressed successively. The current efforts are focused on optimization of plasma edge condition to extend the operation regime towards higher ion temperature and more stable high density. In LHD a part of open helical divertors are being modified to the baffle-structured closed ones to aim at active control of the edge plasma. It has been demonstrated that the neutral pressure in the closed helical divertor was more than 10 times higher than that in the open helical divertor. The central ion temperature has exceeded 7 keV. This high-T i plasma was obtained by a carbon pellet injection and the kinetic-energy confinement was improved by a factor of 1.5. Transport analysis of the high-T i plasmas has shown that the ion-thermal conductivity and the viscosity reduced after the pellet injection. Study of physics in 3-D geometry is highlighted in the topics of the response to Resonant Magnetic Perturbation such as ELM mitigation and divertor detachment. Novel approaches of non-local and non-diffusive transport have also been advanced. In this paper, highlighted results in these two years are overviewed. (author)

  10. Observation of plasma hole in a rotating plasma

    International Nuclear Information System (INIS)

    Nagaoka, Kenichi; Ishihara, Tatsuzo; Okamoto, Atsushi; Yoshimura, Shinji; Tanaka, Masayoshi Y.

    2001-01-01

    Plasma hole, a cylindrical density cavity, formed in a rotating plasma has been investigated experimentally. The plasma hole is characterized by large aspect ratio (length/radius ≥ 30), steep boundary layer between the hole and the ambient plasma (10 ion Larmor radius), and extremely high positive potential (130 V). The flow velocity field associated with plasma hole structure has been measured, and is found to have interesting features: (1) plasma rotates in azimuthal direction at a maximum velocity of order of ion sound speed, (2) plasma flows radially inward across the magnetic field line, (3) there present an axial flow reversal between core and peripheral region. It is found that the flow pattern of the plasma hole is very similar to the that of well-developed typhoon with core. (author)

  11. Structural evolution of Ti destroyable interlayer in large-size diamond film deposition by DC arc plasma jet

    Science.gov (United States)

    Guo, Jianchao; Li, Chengming; Liu, Jinlong; Wei, Junjun; Chen, Liangxian; Hua, Chenyi; Yan, Xiongbo

    2016-05-01

    The addition of titanium (Ti) interlayer was verified to reduce the residual stress of diamond films by self-fracturing and facilitate the harvest of a crack-free free-standing diamond film prepared by direct current (DC) arc plasma jet. In this study, the evolution of the Ti interlayer between large-area diamond film and substrate was studied and modeled in detail. The evolution of the interlayer was found to be relevant to the distribution of the DC arc plasma, which can be divided into three areas (arc center, arc main, and arc edge). The formation rate of titanium carbide (TiC) in the arc main was faster than in the other two areas and resulted in the preferred generation of crack in the diamond film in the arc main during cooling. Sandwich structures were formed along with the growth of TiC until the complete transformation of the Ti interlayer. The interlayer released stress via self-fracture. Avoiding uneven fragile regions that formed locally in the interlayer and achieving cooperatively released stress are crucial for the preparation of large crack-free diamond films.

  12. Large-aperture Tunable Plasma Meta-material to Interact with Electromagnetic Waves

    Science.gov (United States)

    Corke, Thomas; Matlis, Eric

    2016-11-01

    The formation of spatially periodic arrangements of glow discharge plasma resulting from charge instabilities were investigated as a tuneable plasma meta-material. The plasma was formed between two 2-D parallel dielectric covered electrodes: one consisting of an Indium-Tin-Oxide coated glass sheet, and the other consisting of a glass-covered circular electrode. The dielectric covered electrodes were separated by a gap that formed a 2-D channel. The gap spacing was adjustable. The electrodes were powered by a variable amplitude AC generator. The parallel electrode arrangement was placed in a variable pressure vacuum chamber. Various combinations of gap spacing, pressure and voltage resulted in the formation of spatially periodic arrangements (lattice) of glow discharge plasma. The lattice spacing perfectly followed 2-D packing theory, and was fully adjustable through the three governing parameters. Lattice arrangements were designed to interact with electromagnetic (EM) waves in the frequency range between 10GHz-80GHz. Its feasibility was investigate through an EM wave simulation that we adapted to allow for plasma permittivity. The results showed a clear suppression of the EM wave amplitude through the plasma gratings. Supported by AFOSR.

  13. Study of single and binary ion plasma expansion into laboratory-generated plasma wakes

    International Nuclear Information System (INIS)

    Wright, K.H. Jr.

    1988-02-01

    Plasma expansion into the wake of a large rectangular plate immersed in a collisionless, supersonic plasma was investigated in laboratory experiments. The experimental conditions address both single ion and binary ion plasma flows for the case of a body whose size is large in comparison with the Debye length, when the potential difference between the body and the plasma is relatively small. A new plasma source was developed to generate equi-velocity, binary ion plasma flows, which allows access to new parameter space that have previously been unavailable for laboratory studies. Specifically, the new parameters are the ionic mass ratio and the ionic component density ratio. In a series of experiments, a krypton-neon plasma is employed where the ambient density ratio of neon to krypton is varied more than an order of magnitude. The expansion in both the single ion and binary ion plasma cases is limited to early times, i.e., a few ion plasma periods, by the combination of plasma density, plasma drift speed, and vacuum chamber size, which prevented detailed comparison with self-similar theory

  14. Statistical properties of edge plasma turbulence in the Large Helical Device

    Science.gov (United States)

    Dewhurst, J. M.; Hnat, B.; Ohno, N.; Dendy, R. O.; Masuzaki, S.; Morisaki, T.; Komori, A.

    2008-09-01

    Ion saturation current (Isat) measurements made by three tips of a Langmuir probe array in the Large Helical Device are analysed for two plasma discharges. Absolute moment analysis is used to quantify properties on different temporal scales of the measured signals, which are bursty and intermittent. Strong coherent modes in some datasets are found to distort this analysis and are consequently removed from the time series by applying bandstop filters. Absolute moment analysis of the filtered data reveals two regions of power-law scaling, with the temporal scale τ ≈ 40 µs separating the two regimes. A comparison is made with similar results from the Mega-Amp Spherical Tokamak. The probability density function is studied and a monotonic relationship between connection length and skewness is found. Conditional averaging is used to characterize the average temporal shape of the largest intermittent bursts.

  15. Collision Time Measurements in a Sonoluminescing Microplasma with a Large Plasma Parameter

    Science.gov (United States)

    Bataller, A.; Kappus, B.; Camara, C.; Putterman, S.

    2014-07-01

    The plasma which forms inside of a micron-sized sonoluminescing bubble in water for under a nanosecond has been probed with 3 ns long laser pulses. A comparison of the response to 532 and 1064 nm light indicates that the plasma number density is about 2×1021 cm-3 and that transport properties are dominated by strong screening and correlation effects. The spherical shape, well-defined atomic density, and blackbody temperature make the sonoluminescing plasma a test bed for theories of strongly coupled plasmas. The plasma in this experiment distinguishes between competing theories of strong, intermediate, and weak effective screening.

  16. Measurement of the effective plasma ion mass in large tokamaks

    International Nuclear Information System (INIS)

    Lister, J.B.; Villard, L.; Ridder, G. de

    1997-01-01

    There is not yet a straightforward method for the measurement of the D-T ratio in the centre of a tokamak plasma. One of the simpler measurements put forward in the past is the interpretation of the MHD spectrum in the frequency range of the Global Alfven Eigenmodes (GAE). However, the frequencies of these modes do not only depend on the plasma mass, but are also quite strongly dependent on the details of the current and density profiles, creating a problem of deconvolution of the estimate of the plasma mass from an implicit relationship between several measurable plasma parameters and the detected eigenmode frequencies. This method has been revised to assess its likely precision for the JET tokamak. The low n GAE modes are sometimes too close to the continuum edge to be detectable and the interpretation of the GAE spectrum is rendered less direct than had been hoped. We present a statistical study on the precision with which the D-T ratio could be estimated from the GAE spectrum on JET. (author) 4 figs., 8 refs

  17. Introduction to burning plasma physics

    International Nuclear Information System (INIS)

    Momota, Hiromu

    1982-01-01

    The free energy of fusion-produced charged particles, the critical plasma Q-value for the thermal instability, and the Cherenkov's emission are discussed. The free energy of fusion-produced charged particles is large even in DT burning plasma. The primary role of fusion-produced energetic charged particles is the heating of fuel plasma. If the charged particle heating is large, burning may be thermally unstable. A zero dimensional analysis shows that the critical plasma Q-values for this thermal instability are nearly 5 for DT burning plasma of 14 keV and 1.6 for D-He 3 burning plasma of 60 keV. These critical plasma Q-values are small as compared to that required for commercial reactors. Then, some methods of burning-control should be introduced to fusion plasma. Another feature of energetic charged particles may be Cherenkov's emission of various waves in fusion plasma. The relationship between this micro-instability and transport phenomena may be the important problem to be clarified. The fusion-produced energetic charged particles have large Larmor radii, and they may have effects on balooning mode instability. (Kato, T.)

  18. Plasma sheath in non-Maxwellian plasma

    International Nuclear Information System (INIS)

    Shimizu, Takuo; Horigome, Takashi

    1992-01-01

    Reviewing many theoretical and experimental works on the electron-energy distributions (EEDF) of various plasmas, we point out that many plasmas have EEDF of non-Maxwellian in shape. Therefore, the recent treatment of plasma sheath using the Maxwell-Boltzmann distribution approximation should be improved. To do this, we have adopted Rutcher's standard distribution as a generalized form in place of the traditional Maxwellian, and found that the minimum energy of ions entering the sheath edge (Bohm's criterion) varies largely, and have also shown the variation of Debye length with the shape of EEDF. The length is the most important parameter to proceed with more detailed analysis on plasma-sheaths, and also to control them in the future. (author)

  19. Modeling plasma behavior in a plasma electrode Pockels cell

    International Nuclear Information System (INIS)

    Boley, C.D.; Rhodes, M.A.

    1999-01-01

    The authors present three interrelated models of plasma behavior in a plasma electrode Pockels cell (PEPC). In a PEPC, plasma discharges are formed on both sides of a thin, large-aperture electro-optic crystal (typically KDP). The plasmas act as optically transparent, highly conductive electrodes, allowing uniform application of a longitudinal field to induce birefringence in the crystal. First, they model the plasma in the thin direction, perpendicular to the crystal, via a one-dimensional fluid model. This yields the electron temperature and the density and velocity profiles in this direction as functions of the neutral pressure, the plasma channel width, and the discharge current density. Next, they model the temporal response of the crystal to the charging process, combining a circuit model with a model of the sheath which forms near the crystal boundary. This model gives the time-dependent voltage drop across the sheath as a function of electron density at the sheath entrance. Finally, they develop a two-dimensional MHD model of the planar plasma, in order to calculate the response of the plasma to magnetic fields. They show how the plasma uniformity is affected by the design of the current return, by the longitudinal field from the cathode magnetron, and by fields from other sources. This model also gives the plasma sensitivity to the boundary potential at which the top and bottom of the discharge are held. They validate these models by showing how they explain observations in three large Pockels cells built at Lawrence Livermore National Laboratory

  20. Inhibition of stimulated Raman scattering due to the excitation of stimulated Brillouin scattering

    Science.gov (United States)

    Zhao, Yao; Yu, Lu-Le; Weng, Su-Ming; Ren, Chuang; Liu, Chuan-Sheng; Sheng, Zheng-Ming

    2017-09-01

    The nonlinear coupling between stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) of intense laser in underdense plasma is studied theoretically and numerically. Based upon the fluid model, their coupling equations are derived, and a threshold condition of plasma density perturbations due to SBS for the inhibition of SRS is given. Particle-in-cell simulations show that this condition can be achieved easily by SBS in the so-called fluid regime with kLλDDebye length [Kline et al., Phys. Plasmas 13, 055906 (2006)]. SBS can reduce the saturation level of SRS and the temperature of electrons in both homogeneous and inhomogeneous plasma. Numerical simulations also show that this reduced SRS saturation is retained even if the fluid regime condition mentioned above is violated at a later time due to plasma heating.

  1. Magnesium plasma immersion ion implantation in a large straight magnetic duct

    International Nuclear Information System (INIS)

    Tan, Ing Hwie; Ueda, Mario; Dallaqua, Renato S; Rossi, Jose O; Beloto, Antonio F; Abramof, Eduardo; Inoue, Y; Takai, Osamu

    2002-01-01

    Magnesium ions were implanted on silicon wafers using a vacuum arc plasma system with a straight 1 m long magnetic duct, 0.22 m in diameter. Good macroparticle filtering was obtained in samples positioned facing the plasma stream and complete filtering was achieved in samples with surfaces parallel to the plasma stream and magnetic field. Deposition is also minimized by placing sample surfaces parallel to the plasma stream. High resolution x-ray diffraction rocking curves of implanted samples show that the changes in lattice constant are due to compressive strain, and the distortion is larger for higher voltages. Without magnetic field the implantation was a few hundred angstroms deep, as expected, but with magnetic field the depth profile was surprisingly extended to over 0.1 μm, a fact for which we do not yet have a convincing explanation, but could be related to radiation enhanced segregation. The presence of a magnetic field increases substantially the retained implantation dose due to the increase in plasma density by two orders of magnitude

  2. High-beta plasma effects in a low-pressure helicon plasma

    International Nuclear Information System (INIS)

    Corr, C. S.; Boswell, R. W.

    2007-01-01

    In this work, high-beta plasma effects are investigated in a low-pressure helicon plasma source attached to a large volume diffusion chamber. When operating above an input power of 900 W and a magnetic field of 30 G a narrow column of bright blue light (due to Ar II radiation) is observed along the axis of the diffusion chamber. With this blue mode, the plasma density is axially very uniform in the diffusion chamber; however, the radial profiles are not, suggesting that a large diamagnetic current might be induced. The diamagnetic behavior of the plasma has been investigated by measuring the temporal evolution of the magnetic field (B z ) and the plasma kinetic pressure when operating in a pulsed discharge mode. It is found that although the electron pressure can exceed the magnetic field pressure by a factor of 2, a complete expulsion of the magnetic field from the plasma interior is not observed. In fact, under our operating conditions with magnetized ions, the maximum diamagnetism observed is ∼2%. It is observed that the magnetic field displays the strongest change at the plasma centre, which corresponds to the maximum in the plasma kinetic pressure. These results suggest that the magnetic field diffuses into the plasma sufficiently quickly that on a long time scale only a slight perturbation of the magnetic field is ever observed

  3. Eosinophils may play regionally disparate roles in influencing IgA(+) plasma cell numbers during large and small intestinal inflammation.

    Science.gov (United States)

    Forman, Ruth; Bramhall, Michael; Logunova, Larisa; Svensson-Frej, Marcus; Cruickshank, Sheena M; Else, Kathryn J

    2016-05-31

    Eosinophils are innate immune cells present in the intestine during steady state conditions. An intestinal eosinophilia is a hallmark of many infections and an accumulation of eosinophils is also observed in the intestine during inflammatory disorders. Classically the function of eosinophils has been associated with tissue destruction, due to the release of cytotoxic granule contents. However, recent evidence has demonstrated that the eosinophil plays a more diverse role in the immune system than previously acknowledged, including shaping adaptive immune responses and providing plasma cell survival factors during the steady state. Importantly, it is known that there are regional differences in the underlying immunology of the small and large intestine, but whether there are differences in context of the intestinal eosinophil in the steady state or inflammation is not known. Our data demonstrates that there are fewer IgA(+) plasma cells in the small intestine of eosinophil-deficient ΔdblGATA-1 mice compared to eosinophil-sufficient wild-type mice, with the difference becoming significant post-infection with Toxoplasma gondii. Remarkably, and in complete contrast, the absence of eosinophils in the inflamed large intestine does not impact on IgA(+) cell numbers during steady state, and is associated with a significant increase in IgA(+) cells post-infection with Trichuris muris compared to wild-type mice. Thus, the intestinal eosinophil appears to be less important in sustaining the IgA(+) cell pool in the large intestine compared to the small intestine, and in fact, our data suggests eosinophils play an inhibitory role. The dichotomy in the influence of the eosinophil over small and large intestinal IgA(+) cells did not depend on differences in plasma cell growth factors, recruitment potential or proliferation within the different regions of the gastrointestinal tract (GIT). We demonstrate for the first time that there are regional differences in the requirement of

  4. Intermittent transport in edge plasma with a 3-D magnetic geometry in the Large Helical Device

    International Nuclear Information System (INIS)

    Tanaka, H.; Masuzaki, S.; Ohno, N.; Morisaki, T.; Tsuji, Y.

    2013-01-01

    Blobby plasma transport is a universally observed phenomenon in magnetic confinement devices, and it is considered to be closely related to edge plasma physics. We have investigated such an intermittent event observed inside the divertor region of the Large Helical Device by using a fast-scanning Langmuir probe with two electrodes. Ion saturation current fluctuations showed negative spikes in the divertor leg and positive spikes in the private region. Further, the time delay between the two fluctuations followed a unique trajectory in the positive-skewness region. We found common as well as different fluctuation characteristics between the LHD and tokamaks. We discuss the analysis results in relation to the blob-generation and propagation behaviors in the three-dimensional magnetic geometry around the divertor leg. In addition, we quantitatively estimated the blob propagation velocity and size based on a theoretical assumption

  5. A study of single and binary ion plasma expansion into laboratory-generated plasma wakes

    Science.gov (United States)

    Wright, Kenneth Herbert, Jr.

    1988-01-01

    Plasma expansion into the wake of a large rectangular plate immersed in a collisionless, supersonic plasma was investigated in laboratory experiments. The experimental conditions address both single ion and binary ion plasma flows for the case of a body whose size is large in comparison with the Debye length, when the potential difference between the body and the plasma is relatively small. A new plasma source was developed to generate equi-velocity, binary ion plasma flows, which allows access to new parameter space that have previously been unavailable for laboratory studies. Specifically, the new parameters are the ionic mass ratio and the ionic component density ratio. In a series of experiments, a krypton-neon plasma is employed where the ambient density ratio of neon to krypton is varied more than an order of magnitude. The expansion in both the single ion and binary ion plasma cases is limited to early times, i.e., a few ion plasma periods, by the combination of plasma density, plasma drift speed, and vacuum chamber size, which prevented detailed comparison with self-similar theory.

  6. Suppression of large edge localized modes in high confinement DIII-D plasmas with a stochastic magnetic boundary

    Energy Technology Data Exchange (ETDEWEB)

    Evans, T.E. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States)]. E-mail: evans@fusion.gat.com; Moyer, R.A. [University of California at San Diego, La Jolla, CA 92093-0417 (United States); Watkins, J.G. [Sandia National Laboratories, Albuquerque, NM 87185-1129 (United States); Thomas, P.R. [Association Euratom-CEA, CEA Cadarache, F-13108, St. Paul-lez-Durance (France); Osborne, T.H. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Boedo, J.A. [University of California at San Diego, La Jolla, CA 92093-0417 (United States); Fenstermacher, M.E. [Lawrence Livermore National Laborabory, Livermore, CA 94550 (United States); Finken, K.H. [Forschungszentrum Juelich, Institute for Plasma Physics, D52425 Juelich (Germany); Groebner, R.J. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Groth, M. [Lawrence Livermore National Laborabory, Livermore, CA 94550 (United States); Harris, J. [Australian National University, Canberra (Australia); Jackson, G.L. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Haye, R.J. La [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Lasnier, C.J. [Lawrence Livermore National Laborabory, Livermore, CA 94550 (United States); Schaffer, M.J. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Wang, G. [University of California, Los Angeles, California (United States); Zeng, L. [University of California, Los Angeles, California (United States)

    2005-03-01

    Large 70 Hz Type-I edge localized modes (ELMs) are converted into small 130 Hz oscillations using edge resonant magnetic perturbations (RMPs) from a coil with currents 0.4% I {sub p} in double null DIII-D plasmas. When the RMP is properly phased with respect to the background field errors, all but a few isolated ELM-like events are suppressed. The impulsive pedestal energy loss {delta}E {sub ELM}/{delta}t {sup 1/2} to the scrape-of layer is reduced a factor of 20 relative to the Type-I ELMs and the core confinement is unaffected by the perturbation field. Significant changes in the properties of the ELMs are also observed when edge RMPs are applied to lower single null plasmas but the nature of these changes are much more complex. Both lower single null and double null plasmas are being studied to determine how ELM control techniques based on the application of edge RMPs can be expected to scale to future devices such as ITER.

  7. Atmospheric pressure microwave plasma system with ring waveguide

    International Nuclear Information System (INIS)

    Liu Liang; Zhang Guixin; Zhu Zhijie; Luo Chengmu

    2007-01-01

    Some scientists used waveguide as the cavity to produce a plasma jet, while large volume microwave plasma was relatively hard to get in atmospheric pressure. However, a few research institutes have already developed devices to generate large volume of atmospheric pressure microwave plasma, such as CYRANNUS and SLAN series, which can be widely applied. In this paper, present a microwave plasma system with ring waveguide to excite large volume of atmospheric pressure microwave plasma, plot curves on theoretical disruption electric field of some working gases, emulate the cavity through software, measure the power density to validate and show the appearance of microwave plasma. At present, large volume of argon and helium plasma have already been generated steadily by atmospheric pressure microwave plasma system. This research can build a theoretical basis of microwave plasma excitation under atmospheric pressure and will be useful in study of the device. (authors)

  8. En Route: next-generation laser-plasma-based electron accelerators

    International Nuclear Information System (INIS)

    Hidding, Bernhard

    2008-05-01

    Accelerating electrons to relativistic energies is of fundamental interest, especially in particle physics. Today's accelerator technology, however, is limited by the maximum electric fields which can be created. This thesis presents results on various mechanisms aiming at exploiting the fields in focussed laser pulses and plasma waves for electron acceleration, which can be orders of magnitude higher than with conventional accelerators. With relativistic, underdense laser-plasma-interaction, quasimonoenergetic electron bunches with energies up to ∼50 MeV and normalized emittances of the order of 5mmmrad have been generated. This was achieved by focussing the ∼80 fs, 1 J pulses of the JETI-laser at the FSU Jena to intensities of several 10 19 W=cm 2 into gas jets. The experimental observations could be explained via ''bubble acceleration'', which is based on self-injection and acceleration of electrons in a highly nonlinear breaking plasma wave. For the rst time, this bubble acceleration was achieved explicitly in the self-modulated laser wakefield regime (SMLWFA). This quasimonoenergetic SMLWFA-regime stands out by relaxing dramatically the requirements on the driving laser pulse necessary to trigger bubble acceleration. This is due to self-modulation of the laser pulse in high-density gas jets, leading to ultrashort laser pulse fragments capable of initiating bubble acceleration. Electron bunches with durations < or similar 5 fs can thus be created, which is at least an order of magnitude shorter than with conventional accelerator technology. In addition, more than one laser pulse fragment can be powerful enough to drive a bubble. Distinct double peaks have been observed in the electron spectra, indicating that two quasimonoenergetic electron bunches separated by only few tens of fs have formed. This is backed up by PIC-Simulations (Particle-in-Cell). These results underline the feasibility of the construction of small table-top accelerators, while at the

  9. En Route: next-generation laser-plasma-based electron accelerators; En Route: Elektronenbeschleuniger der naechsten Generation auf Laser-Plasma-Basis

    Energy Technology Data Exchange (ETDEWEB)

    Hidding, Bernhard

    2008-05-15

    Accelerating electrons to relativistic energies is of fundamental interest, especially in particle physics. Today's accelerator technology, however, is limited by the maximum electric fields which can be created. This thesis presents results on various mechanisms aiming at exploiting the fields in focussed laser pulses and plasma waves for electron acceleration, which can be orders of magnitude higher than with conventional accelerators. With relativistic, underdense laser-plasma-interaction, quasimonoenergetic electron bunches with energies up to {approx}50 MeV and normalized emittances of the order of 5mmmrad have been generated. This was achieved by focussing the {approx}80 fs, 1 J pulses of the JETI-laser at the FSU Jena to intensities of several 10{sup 19}W=cm{sup 2} into gas jets. The experimental observations could be explained via 'bubble acceleration', which is based on self-injection and acceleration of electrons in a highly nonlinear breaking plasma wave. For the rst time, this bubble acceleration was achieved explicitly in the self-modulated laser wakefield regime (SMLWFA). This quasimonoenergetic SMLWFA-regime stands out by relaxing dramatically the requirements on the driving laser pulse necessary to trigger bubble acceleration. This is due to self-modulation of the laser pulse in high-density gas jets, leading to ultrashort laser pulse fragments capable of initiating bubble acceleration. Electron bunches with durations

  10. RAYIC - a numerical code for the study of ion cyclotron heating of large Tokamak plasmas

    International Nuclear Information System (INIS)

    Brambilla, M.

    1984-02-01

    The code RAYIC models coupling, propagation and absorption of e.m. waves in large axisymmetric plasmas in the ion cyclotron frequency domain. It can be used both to investigate the waves behaviour, and as a source of the power deposition profiles for use in transport codes. The present user manual, after a brief summary of the physical model, presents the structure of RAYIC, the complete list of input-output variables (calling sequence), and some examples of the output which can be obtained from the code. (orig.)

  11. Frontier of plasma physics. 'Research network on non-equilibrium and extreme state plasmas'

    International Nuclear Information System (INIS)

    Itoh, Sanae-I.; Fujisawa, Akihide; Kodama, Ryosuke; Sato, Motoyasu; Tanaka, Kazuo A.; Hatakeyama, Rikizo; Itoh, Kimitaka

    2011-01-01

    Plasma physics and fusion science have been applied to a wide variety of plasmas such as nuclear fusion plasmas, high-energy-density plasmas, processing plasmas and nanobio- plasmas. They are pioneering science and technology frontiers such as new energy sources and new functional materials. A large project 'research network on non-equilibrium and extreme state plasmas' is being proposed to reassess individual plasma researches from a common view of the non-equilibrium extreme plasma and to promote collaboration among plasma researchers all over the country. In the present review, recent collaborative works related to this project are being introduced. (T.I.)

  12. Large daily fluctuations in plasma tyrosine in treated patients with phenylketonuria

    NARCIS (Netherlands)

    vanSpronsen, FJ; vanDijk, T; Smit, GPA; vanRijn, M; Reijngoud, DJ; Berger, Ruud; Heymans, HSA

    1996-01-01

    In patients with phenylketonuria (PKU), extra tyrosine supplementation is advocated in addition to tyrosine-enriched amino acid mixtures. PKU patients have low fasting plasma tyrosine concentrations, but little is known about tyrosine fluctuations during the day. Plasma tyrosine concentrations were

  13. Computer tomography of large dust clouds in complex plasmas

    International Nuclear Information System (INIS)

    Killer, Carsten; Himpel, Michael; Melzer, André

    2014-01-01

    The dust density is a central parameter of a dusty plasma. Here, a tomography setup for the determination of the three-dimensionally resolved density distribution of spatially extended dust clouds is presented. The dust clouds consist of micron-sized particles confined in a radio frequency argon plasma, where they fill almost the entire discharge volume. First, a line-of-sight integrated dust density is obtained from extinction measurements, where the incident light from an LED panel is scattered and absorbed by the dust. Performing these extinction measurements from many different angles allows the reconstruction of the 3D dust density distribution, analogous to a computer tomography in medical applications

  14. Suppression of large edge localized modes with a stochastic magnetic boundary in high confinement DIII-D plasmas

    International Nuclear Information System (INIS)

    Evans, T.E.; Moyer, R.A.; Watkins, J.G.

    2005-01-01

    Large sub-millisecond heat pulses due to Type-I ELMs have been eliminated reproducibly in DIII.D for periods approaching 7 energy confinement times with small dc currents driven in a simple magnetic perturbation coil. The current required to eliminate all but a few isolated Type-I ELM impulses during a coil pulse is less than 0.4% of plasma current. Based on vacuum magnetic field line modeling, the perturbation fields resonate strongly with plasma flux surfaces across most of the pedestal region (0.9 ≤ Ψ N ≤ 1.0) when q 95 = 3.7±0.2 creating small remnant magnetic islands surrounded by weakly stochastic field lines. The stored energy, β N , H-mode quality factor and global energy confinement time are unaltered. Although some isolated ELM-like events typically occur, long periods free of large Type-I ELMs (Δt > 4-6 τ E ) have been reproduced numerous times, on multiple experimental run days including cases matching the ITER scenario 2 flux surface shape. Since large Type-I ELM impulses represent a severe constraint on the survivability of the divertor target plates in future fusion devices such as ITER, a proven method of eliminating these impulses is critical for the development of tokamak reactors. Results presented in this paper indicate that non-axisymmetric edge magnetic perturbations could be a promising option for controlling ELMs in future tokamaks such as ITER. (author)

  15. High plasma rotation velocity and density transitions by biased electrodes in RF produced, magnetized plasma

    International Nuclear Information System (INIS)

    Matsuyama, Shoichiro; Shinohara, Shunjiro

    2001-01-01

    A large density profile modification was successfully obtained by voltage biasing to electrodes inserted in a RF (radio frequency) produced, magnetized plasma, and formation of strong shear of azimuthal plasma rotation velocity in a supersonic regime was found. For the case of biasing to an electrode near the central plasma region, two types of density transitions were observed in the outer plasma region: one was an oscillatory transition between two states, and the other was a transition from high to low density states with a large reduction of density fluctuations. (author)

  16. High plasma rotation velocity and density transitions by biased electrodes in RF produced, magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, Shoichiro; Shinohara, Shunjiro [Kyushu Univ., Interdisciplinary Graduate School of Engineering Sciences, Fukuoka (Japan)

    2001-07-01

    A large density profile modification was successfully obtained by voltage biasing to electrodes inserted in a RF (radio frequency) produced, magnetized plasma, and formation of strong shear of azimuthal plasma rotation velocity in a supersonic regime was found. For the case of biasing to an electrode near the central plasma region, two types of density transitions were observed in the outer plasma region: one was an oscillatory transition between two states, and the other was a transition from high to low density states with a large reduction of density fluctuations. (author)

  17. The physics of megajoule, large-scale, and ultrafast short-scale laser plasmas

    International Nuclear Information System (INIS)

    Campbell, E.M.

    1992-01-01

    Recent advances in laser science and technology have opened new possibilities for the study of high energy density plasma physics. The advances include techniques to control the laser spatial and temporal coherence, and the development of laser architectures and optical materials that have led to the demonstration of compact, short pulse (τ≤10 -12 sec) high brightness lasers, capable of irradiating plasmas with intensities ≥10 18 W/cm 2 . Experiments with reduced laser coherence have shown a substantial decrease in laser-driven parametric instabilities and have extended the parameter range where inverse bremsstrahlung absorption is the dominant coupling process. Beam smoothing with short wavelength lasers should result in inverse bremsstrahlung dominated coupling in the irradiance parameter regimes of the millimeter scale-length plasmas envisioned for the megajoule class lasers for ignition and gain in inertial fusion. In addition new regimes of laser--plasma coupling will become experimentally accessible when plasmas are irradiated with I≥10 18 W/cm 2 . Relativistic effects, extreme profile modification, and electrons heated to energies exceeding 1 MeV are several of the phenomena that are expected. Numerous applications in basic and applied plasma physics will result from these new capabilities

  18. Lage-area planar RF plasma productions by surface waves

    International Nuclear Information System (INIS)

    Nonaka, S.

    1994-01-01

    Large-area rf plasmas are confirmed to be produced by means of RF discharges inside a large-area dielectric tube. The plasma space is 73 cm x 176 cm and 2.5 cm. The plasma is thought to be produced by an odd plasma-surface wave (PSW ο ) in case of using large-area electrodes and by an even plasma-surface wave (PSW ο ) in case of without the electrodes. (author). 7 refs, 4 figs

  19. A uniform laminar air plasma plume with large volume excited by an alternating current voltage

    Science.gov (United States)

    Li, Xuechen; Bao, Wenting; Chu, Jingdi; Zhang, Panpan; Jia, Pengying

    2015-12-01

    Using a plasma jet composed of two needle electrodes, a laminar plasma plume with large volume is generated in air through an alternating current voltage excitation. Based on high-speed photography, a train of filaments is observed to propagate periodically away from their birth place along the gas flow. The laminar plume is in fact a temporal superposition of the arched filament train. The filament consists of a negative glow near the real time cathode, a positive column near the real time anode, and a Faraday dark space between them. It has been found that the propagation velocity of the filament increases with increasing the gas flow rate. Furthermore, the filament lifetime tends to follow a normal distribution (Gaussian distribution). The most probable lifetime decreases with increasing the gas flow rate or decreasing the averaged peak voltage. Results also indicate that the real time peak current decreases and the real time peak voltage increases with the propagation of the filament along the gas flow. The voltage-current curve indicates that, in every discharge cycle, the filament evolves from a Townsend discharge to a glow one and then the discharge quenches. Characteristic regions including a negative glow, a Faraday dark space, and a positive column can be discerned from the discharge filament. Furthermore, the plasma parameters such as the electron density, the vibrational temperature and the gas temperature are investigated based on the optical spectrum emitted from the laminar plume.

  20. A study of fast electron energy transport in relativistically intense laser-plasma interactions with large density scalelengths

    Energy Technology Data Exchange (ETDEWEB)

    Scott, R. H. H.; Norreys, P. A. [Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Perez, F.; Baton, S. D. [LULI, Ecole Polytechnique, UMR 7605, CNRS/CEA/UPMC, Route de Saclay, 91128 Palaiseau (France); Santos, J. J.; Nicolai, Ph.; Hulin, S. [Univ. Bordeaux/CNRS/CEA, CELIA, UMR 5107, 33405 Talence (France); Ridgers, C. P. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom); Davies, J. R. [GoLP, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Lancaster, K. L.; Trines, R. M. G. M. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Bell, A. R.; Tzoufras, M. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX (United Kingdom); Rose, S. J. [Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom)

    2012-05-15

    A systematic experimental and computational investigation of the effects of three well characterized density scalelengths on fast electron energy transport in ultra-intense laser-solid interactions has been performed. Experimental evidence is presented which shows that, when the density scalelength is sufficiently large, the fast electron beam entering the solid-density plasma is best described by two distinct populations: those accelerated within the coronal plasma (the fast electron pre-beam) and those accelerated near or at the critical density surface (the fast electron main-beam). The former has considerably lower divergence and higher temperature than that of the main-beam with a half-angle of {approx}20 Degree-Sign . It contains up to 30% of the total fast electron energy absorbed into the target. The number, kinetic energy, and total energy of the fast electrons in the pre-beam are increased by an increase in density scalelength. With larger density scalelengths, the fast electrons heat a smaller cross sectional area of the target, causing the thinnest targets to reach significantly higher rear surface temperatures. Modelling indicates that the enhanced fast electron pre-beam associated with the large density scalelength interaction generates a magnetic field within the target of sufficient magnitude to partially collimate the subsequent, more divergent, fast electron main-beam.

  1. Modification of the magnetic field structure of high-beta plasmas with a perturbation field in the Large Helical Device

    International Nuclear Information System (INIS)

    Sakakibara, S; Suzuki, Y; Narushima, Y; Watanabe, K Y; Ohdachi, S; Ida, K; Yoshinuma, M; Narihara, K; Yamada, I; Tanaka, K; Tokuzawa, T; Yamada, H; Takemura, Y

    2013-01-01

    The effect of resonant magnetic perturbation (RMP) on MHD characteristics is investigated in high-beta plasmas of the Large Helical Device. The ramp-up and static m/n = 1/1 RMP field are applied in medium- (∼2%) and high- (∼4%) beta plasmas in order to find beta dependences of mode penetration, MHD activities and confinement. The results show that the threshold of mode penetration linearly increases with the beta value and/or plasma collisionality. The threshold of mode penetration in the RMP ramp-up experiments is roughly consistent with the static RMP case. The beta value gradually decreases with the RMP field strength before mode penetration, which is caused by a reduction in the pressure inside the ι/2π = 1 resonance. The width of the magnetic island after the penetration becomes larger than the given RMP field, and it is further enhanced by the increment of the beta value. (paper)

  2. Observation of large-amplitude ion acoustic solitary waves in a plasma

    International Nuclear Information System (INIS)

    Nakamura, Yoshiharu

    1987-01-01

    Propagation of nonlinear ion acoustic waves in a multi-component plasma with negative ions is investigated in a double-plasma device. When the density of negative ions is larger than a critical value, a broad negative pulse evolves to rarefactive solitons, and a positive pulse whose amplitude is less than a certain threshold value becomes a subsonic wave train. In the same plasma, a positive pulse whose amplitude is larger than the threshold develops into a solitary wave. The critical amplitude is measured as a function of the density of negative ions and compared with predictions of the pseudo-potential method. The energy distribution of electrons in the solitary wave is also measured. (author)

  3. Transition from wakefield generation to soliton formation

    Science.gov (United States)

    Holkundkar, Amol R.; Brodin, Gert

    2018-04-01

    It is well known that when a short laser pulse propagates in an underdense plasma, it induces longitudinal plasma oscillations at the plasma frequency after the pulse, typically referred to as the wakefield. However, for plasma densities approaching the critical density, wakefield generation is suppressed, and instead the EM-pulse (electromagnetic pulse) undergoes nonlinear self-modulation. In this article we have studied the transition from the wakefield generation to formation of quasi-solitons as the plasma density is increased. For this purpose we have applied a one-dimensional relativistic cold fluid model, which has also been compared with particle-in-cell simulations. A key result is that the energy loss of the EM-pulse due to wakefield generation has its maximum for a plasma density of the order 10% of the critical density, but that wakefield generation is sharply suppressed when the density is increased further.

  4. Proposed development of novel diagnostics for intense, ultrafast laser-plasma experiments at JAEA-KPSI

    International Nuclear Information System (INIS)

    Bolton, Paul R.; Tatchyn, Roman; Fukuda, Yuji; Kando, Masaki; Daito, Izuru; Ma, Jinglong; Chen, Liming; Pirozhkov, Alexander; Tajima, Toshiki

    2007-01-01

    Development of new diagnostics is critical for future laser-plasma accelerators, laser-driven light sources and for x-ray FELs. Recent laser wakefield electron acceleration developments and novel beam-based light source schemes (such as free electron lasers) obviate the need for next generation ultrafast diagnostics, capable of temporal resolution of a few femtoseconds (and in some cases attoseconds) for laser pulses (high order harmonics), x-ray pulses and electron bunches. Single shot detection capability in noninvasive and parasitic modes is also important. Alterations of laser pulse spectra and the associated dynamics can be informative diagnostics. The portion of a high intensity laser pulse that is transmitted through a self-induced underdense plasma (such as in laser wakefield acceleration LWFA schemes) carries the effects of plasma processes it has experienced. A distinction between the self-modulated laser wakefield (SMLWF) acceleration regime and the forced laser wakefield (FLWF) acceleration regime is in the spectral signature of the transmitted ir laser pulse. The former regime generates sidebands from stimulated Raman forward scattering (SRS-F) and the latter exhibits general spectral broadening that evidences ir laser pulse compression. Transmitted spectral effects can diagnose these acceleration regimes. Existing noninvasive electro-optic (EO) schemes for detection of ultrashort electron bunches are limited by material properties to temporal resolution at the 50-100 femtosecond level. While timing jitter at conventional accelerators is of this order (or greater), single bunch longitudinal profile measurements can require improvement of at least an order of magnitude. A new FO technique is described here which monitors enhancement and associated dynamics of spectral components in a probe pulse. Three correlation schemes for detecting ultrashort x-ray pulses are described. Two-photon absorption in tailored ion targets is proposed for scanning auto

  5. Plasma-wall interaction and plasma facing materials

    International Nuclear Information System (INIS)

    Tanabe, Tetsuo; Miyahara, Akira.

    1990-01-01

    The recognition that plasma-wall interaction plays the essential role from both standpoints of energy balance and particle balance for realizing nuclear fusion reactors has become to prevail. However, on how each elementary process acts and what competitive effect the synthetic action brings about, the stage of doing the qualitative discussion has just come, and the quantitative investigation is the problem for the future. In this paper, the plasma-wall interaction as seen from the research field of plasma-facing materials is discussed centering around graphite materials which have been mostly used at present, and the present status of the research and development on the problems of impurities, hydrogen recycling and heat resistance and radiation resistance is mentioned. Moreover, the problems are pointed out, and the course for the future is looked for. The recent experiment with large tokamaks adopted graphite or carbon as the plasma-facing materials, and the reduction of metallic impurities in plasma showed the clear improvement of plasma confinement characteristics. However, for the next device which requires forced cooling, the usability of graphite is doubtful. (K.I.) 51 refs

  6. Generation of mega-electron-volt electron beams by an ultrafast intense laser pulse

    International Nuclear Information System (INIS)

    Wang Xiaofang; Saleh, Ned; Krishnan, Mohan; Wang Haiwen; Backus, Sterling; Murnane, Margaret; Kapteyn, Henry; Umstadter, Donald; Wang Quandong; Shen Baifei

    2003-01-01

    Mega-electron-volt (MeV) electron emission from the interaction of an ultrafast (τ∼29 fs), intense (>10 18 W/cm 2 ) laser pulse with underdense plasmas has been studied. A beam of MeV electrons with a divergence angle as small as 1 deg. is observed in the forward direction, which is correlated with relativistic filamentation of the laser pulse in plasmas. A novel net-energy-gain mechanism is proposed for electron acceleration resulting from the relativistic filamentation and beam breakup. These results suggest an approach for generating a beam of femtosecond, MeV electrons at a kilohertz repetition rate with a compact ultrafast intense laser system

  7. Effects of fueling profiles on plasma transport

    International Nuclear Information System (INIS)

    Houlberg, W.A.; Mense, A.T.; Attenberger, S.E.; Milora, S.L.

    1977-01-01

    The effects of cold particle fueling profiles on particle and energy transport in an ignition sized tokamak plasma are investigated in this study with a one-dimensional, multifluid transport model. A density gradient driven trapped particle microinstability model for plasma transport is used to demonstrate potential effects of fueling profiles on ignition requirements. Important criteria for the development of improved transport models under the conditions of shallow particle fueling profiles are outlined. A discrete pellet fueling model indicates that large fluctuations in density and temperature may occur in the outer regions of the plasma with large, shallowly penetrating pellets, but fluctuations in the pressure profile are small. The hot central core of the plasma remains unaffected by the large fluctuations near the plasma edge

  8. Ordered one-component plasmas: Phase transitions, normal modes, large systems, and experiments in a storage ring

    International Nuclear Information System (INIS)

    Schiffer, J.P.

    1994-01-01

    The property of cold one-component plasmas, confined by external forces, to form an ordered array has been known for some time both from simulations and from experiment. The purpose of this talk is to summarize some recent work on simulations and some new experimental results. The author discusses some experimental work on real storage rings, magnetic storage devices in which partials circulate with large kinetic energies and for which laser cooling is used on partially ionized ions to attain temperatures ten or more orders of magnitude lower than their kinetic energies

  9. Large aperture optical switching devices

    International Nuclear Information System (INIS)

    Goldhar, J.; Henesian, M.A.

    1983-01-01

    We have developed a new approach to constructing large aperture optical switches for next generation inertial confinement fusion lasers. A transparent plasma electrode formed in low pressure ionized gas acts as a conductive coating to allow the uniform charging of the optical faces of an electro-optic material. In this manner large electric fields can be applied longitudinally to large aperture, high aspect ratio Pockels cells. We propose a four-electrode geometry to create the necessary high conductivity plasma sheets, and have demonstrated fast (less than 10 nsec) switching in a 5x5 cm aperture KD*P Pockels cell with such a design. Detaid modelling of Pockels cell performance with plasma electrodes has been carried out for 15 and 30 cm aperture designs

  10. Negative ion surface plasma source development for plasma trap injectors in Novosibirsk

    International Nuclear Information System (INIS)

    Bel'chenko, Yu.I.; Dimov, G.I.; Dudnikov, V.G.; Kupriyanov, A.S.

    1989-01-01

    Work on high-current ion sources carried out at the Novosibirsk Institute of Nuclear Physics (INP) is presented. The INP investigations on ''pure plasma'' planotron and ''pure surface'' secondary emission systems of H - generation, which preceded the surface-plasma concept developed in Novosibirsk, are described. The physical basis of the surface-plasma method of negative-ion production is considered. The versions and operating characteristics of different surface-plasma sources including the multi-ampere (approx-gt 10A) source are discussed. Research on efficient large-area (∼10 2 cm 2 ) negative ion surface-plasma emitters is described. The INP long-pulse multiaperture surface- plasma generators, with a current of about 1A, are described. 38 refs., 17 figs

  11. Influence of Xe and Kr impurities on x-ray yield from debris-free plasma x-ray sources with an Ar supersonic gas jet irradiated by femtosecond near-infrared-wavelength laser pulses

    Science.gov (United States)

    Kantsyrev, V. L.; Schultz, K. A.; Shlyaptseva, V. V.; Petrov, G. M.; Safronova, A. S.; Petkov, E. E.; Moschella, J. J.; Shrestha, I.; Cline, W.; Wiewior, P.; Chalyy, O.

    2016-11-01

    Many aspects of physical phenomena occurring when an intense laser pulse with subpicosecond duration and an intensity of 1018-1019W /cm2 heats an underdense plasma in a supersonic clustered gas jet are studied to determine the relative contribution of thermal and nonthermal processes to soft- and hard-x-ray emission from debris-free plasmas. Experiments were performed at the University of Nevada, Reno (UNR) Leopard laser operated with a 15-J, 350-fs pulse and different pulse contrasts (107 or 105). The supersonic linear (elongated) nozzle generated Xe cluster-monomer gas jets as well as jets with Kr-Ar or Xe-Kr-Ar mixtures with densities of 1018-1019cm-3 . Prior to laser heating experiments, all jets were probed with optical interferometry and Rayleigh scattering to measure jet density and cluster distribution parameters. The supersonic linear jet provides the capability to study the anisotropy of x-ray yield from laser plasma and also laser beam self-focusing in plasma, which leads to efficient x-ray generation. Plasma diagnostics included x-ray diodes, pinhole cameras, and spectrometers. Jet signatures of x-ray emission from pure Xe gas, as well as from a mixture with Ar and Kr, was found to be very different. The most intense x-ray emission in the 1-9 KeV spectral region was observed from gas mixtures rather than pure Xe. Also, this x-ray emission was strongly anisotropic with respect to the direction of laser beam polarization. Non-local thermodynamic equilibrium (Non-LTE) models have been implemented to analyze the x-ray spectra to determine the plasma temperature and election density. Evidence of electron beam generation in the supersonic jet plasma was found. The influence of the subpicosecond laser pulse contrast (a ratio between the laser peak intensity and pedestal pulse intensity) on the jets' x-ray emission characteristics is discussed. Surprisingly, it was found that the x-ray yield was not sensitive to the prepulse contrast ratio.

  12. Self-organizing magnetohydrodynamic plasma

    International Nuclear Information System (INIS)

    Sato, T.; Horiuchi, R.; Watanabe, K.; Hayashi, T.; Kusano, K.

    1990-09-01

    In a resistive magnetohydrodynamic (MHD) plasma, both the magnetic energy and the magnetic helicity dissipate with the resistive time scale. When sufficiently large free magnetic energy does exist, however, an ideal current driven instability is excited whereby magnetic reconnection is driven at a converging point of induced plasma flows which does exist in a bounded compressible plasma. At a reconnection point excess free energy (entropy) is rapidly dissipated by ohmic heating and lost by radiation, while magnetic helicity is completely conserved. The magnetic topology is largely changed by reconnection and a new ordered structure with the same helicity is created. It is discussed that magnetic reconnection plays a key role in the MHD self-organization process. (author)

  13. Weak Lensing by Galaxy Troughs in DES Science Verification Data

    Energy Technology Data Exchange (ETDEWEB)

    Gruen, D. [Ludwig Maximilian Univ., Munich (Germany); Max Planck Inst. for Extraterrestrial Physics, Garching (Germany). et al.

    2015-09-29

    We measure the weak lensing shear around galaxy troughs, i.e. the radial alignment of background galaxies relative to underdensities in projections of the foreground galaxy field over a wide range of redshift in Science Verification data from the Dark Energy Survey. Our detection of the shear signal is highly significant (10σ–15σ for the smallest angular scales) for troughs with the redshift range z ϵ [0.2, 0.5] of the projected galaxy field and angular diameters of 10 arcmin…1°. These measurements probe the connection between the galaxy, matter density, and convergence fields. By assuming galaxies are biased tracers of the matter density with Poissonian noise, we find agreement of our measurements with predictions in a fiducial Λ cold dark matter model. Furthermore, the prediction for the lensing signal on large trough scales is virtually independent of the details of the underlying model for the connection of galaxies and matter. Our comparison of the shear around troughs with that around cylinders with large galaxy counts is consistent with a symmetry between galaxy and matter over- and underdensities. In addition, we measure the two-point angular correlation of troughs with galaxies which, in contrast to the lensing signal, is sensitive to galaxy bias on all scales. Finally, the lensing signal of troughs and their clustering with galaxies is therefore a promising probe of the statistical properties of matter underdensities and their connection to the galaxy field.

  14. On generation of Alfvenic-like fluctuations by drift wave-zonal flow system in large plasma device experiments

    International Nuclear Information System (INIS)

    Horton, W.; Correa, C.; Chagelishvili, G. D.; Avsarkisov, V. S.; Lominadze, J. G.; Perez, J. C.; Kim, J.-H.; Carter, T. A.

    2009-01-01

    According to recent experiments, magnetically confined fusion plasmas with ''drift wave-zonal flow turbulence'' (DW-ZF) give rise to broadband electromagnetic waves. Sharapov et al. [Europhysics Conference Abstracts, 35th EPS Conference on Plasma Physics, Hersonissos, 2008, edited by P. Lalousis and S. Moustaizis (European Physical Society, Switzerland, 2008), Vol. 32D, p. 4.071] reported an abrupt change in the magnetic turbulence during L-H transitions in Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] plasmas. A broad spectrum of Alfvenic-like (electromagnetic) fluctuations appears from ExB flow driven turbulence in experiments on the large plasma device (LAPD) [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] facility at UCLA. Evidence of the existence of magnetic fluctuations in the shear flow region in the experiments is shown. We present one possible theoretical explanation of the generation of electromagnetic fluctuations in DW-ZF systems for an example of LAPD experiments. The method used is based on generalizing results on shear flow phenomena from the hydrodynamics community. In the 1990s, it was realized that fluctuation modes of spectrally stable nonuniform (sheared) flows are non-normal. That is, the linear operators of the flows modal analysis are non-normal and the corresponding eigenmodes are not orthogonal. The non-normality results in linear transient growth with bursts of the perturbations and the mode coupling, which causes the generation of electromagnetic waves from the drift wave-shear flow system. We consider shear flow that mimics tokamak zonal flow. We show that the transient growth substantially exceeds the growth of the classical dissipative trapped-particle instability of the system.

  15. Plasma processing and chemistry

    NARCIS (Netherlands)

    Schram, D.C.

    2002-01-01

    A review. Plasma deposition and plasma conversion can be characterized by five steps: prodn. by ionization, transfer of chem. to precursors, transport of radicals to the surface, surface interactions with deposition, recirculation and generation of new monomers. For very fast deposition, large flows

  16. Large vacuum system for experiences in magnetic confined plasmas

    International Nuclear Information System (INIS)

    Honda, R.Y.; Kayama, M.E.; Boeckelmann, H.K.; Aihara, S.

    1984-01-01

    It is presented the operation method of a theta-pinch system capable of generating and confine plasmas with high densities and temperatures. Some characteristics of Tupa theta-pinch, which is operating at UNICAMP, emphasizing the cleaning mode of the vacuum chamber, are also presented. (M.C.K.) [pt

  17. Studies on the propagation of relativistic plasma waves in high density plasmas produced by hypersonic ionizing shock waves

    International Nuclear Information System (INIS)

    Williams, R.L.; Johnson, J.A. III

    1993-01-01

    The feasibility of using an ionizing shock wave to produce high density plasmas suitable for the propagation large amplitude relativistic plasma waves is being investigated. A 20 kv arc driven shock tube of coaxial geometry produces a hypersonic shock wave (10 p > 10 17 cm -3 ). The shock can be made to reflect off the end of the tube, collide with its wake, and thus increase the plasma density further. After reflecting, the plasma is at rest. The shock speed is measured using piezoelectric pressure probes and the ion density is measured using laser induced fluorescence (LIF) techniques on argon 488.0 nm and 422.8 nm lines. The future plans are to excite large amplitude relativistic plasma waves in this plasma by either injecting a short pulse laser (Laser Wake Field Scheme), two beating lasers (Plasma Beat Wave Scheme), or a short bunch of relativistic electrons (Plasma Wake Field Scheme). Results of recent computational and theoretical studies, as well as initial experimental measurements on the plasma using LIF, are reported. Implications for the application of high density plasmas produced in this way to such novel schemes as the plasma wave accelerator, photon accelerator, plasma wave undulator, and also plasma lens, are discussed. The effect of plasma turbulence is also discussed

  18. Plasma processing for VLSI

    CERN Document Server

    Einspruch, Norman G

    1984-01-01

    VLSI Electronics: Microstructure Science, Volume 8: Plasma Processing for VLSI (Very Large Scale Integration) discusses the utilization of plasmas for general semiconductor processing. It also includes expositions on advanced deposition of materials for metallization, lithographic methods that use plasmas as exposure sources and for multiple resist patterning, and device structures made possible by anisotropic etching.This volume is divided into four sections. It begins with the history of plasma processing, a discussion of some of the early developments and trends for VLSI. The second section

  19. Progress in the Development of a High Power Helicon Plasma Source for the Materials Plasma Exposure Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Goulding, Richard Howell [ORNL; Caughman, John B. [ORNL; Rapp, Juergen [ORNL; Biewer, Theodore M. [ORNL; Bigelow, Tim S. [ORNL; Campbell, Ian H. [ORNL; Caneses Marin, Juan F. [ORNL; Donovan, David C. [ORNL; Kafle, Nischal [ORNL; Martin, Elijah H. [ORNL; Ray, Holly B. [ORNL; Shaw, Guinevere C. [ORNL; Showers, Melissa A. [ORNL

    2017-09-01

    Proto-MPEX is a linear plasma device being used to study a novel RF source concept for the planned Material Plasma Exposure eXperiment (MPEX), which will address plasma-materials interaction (PMI) for nuclear fusion reactors. Plasmas are produced using a large diameter helicon source operating at a frequency of 13.56 MHz at power levels up to 120 kW. In recent experiments the helicon source has produced deuterium plasmas with densities up to ~6 × 1019 m–3 measured at a location 2 m downstream from the antenna and 0.4 m from the target. Previous plasma production experiments on Proto-MPEX have generated lower density plasmas with hollow electron temperature profiles and target power deposition peaked far off axis. The latest experiments have produced flat Te profiles with a large portion of the power deposited on the target near the axis. This and other evidence points to the excitation of a helicon mode in this case.

  20. An efficient, selective collisional ejection mechanism for inner-shell population inversion in laser-driven plasmas

    Energy Technology Data Exchange (ETDEWEB)

    SCHROEDER,W. ANDREAS; NELSON,THOMAS R.; BORISOV,A.B.; LONGWORTH,J.W.; BOYER,K.; RHODES,C.K.

    2000-06-07

    A theoretical analysis of laser-driven collisional ejection of inner-shell electrons is presented to explain the previously observed anomalous kilovolt L-shell x-ray emission spectra from atomic Xe cluster targets excited by intense sub-picosecond 248nrn ultraviolet radiation. For incident ponderomotively-driven electrons photoionized by strong above threshold ionization, the collisional ejection mechanism is shown to be highly l-state and significantly n-state (i.e. radially) selective for time periods shorter than the collisional dephasing time of the photoionized electronic wavefunction. The resulting preference for the collisional ejection of 2p electrons by an ionized 4p state produces the measured anomalous Xe(L) emission which contains direct evidence for (i) the generation of Xe{sup 27+}(2p{sup 5}3d{sup 10}) and Xe{sup 28+}(2p{sup 5}3d{sup 9}) ions exhibiting inner-shell population inversion and (ii) a coherent correlated electron state collision responsible for the production of double 2p vacancies. For longer time periods, the selectivity of this coherent impact ionization mechanism is rapidly reduced by the combined effects of intrinsic quantum mechanical spreading and dephasing--in agreement with the experimentally observed and extremely strong {minus}{lambda}{sup {minus}6} pump-laser wavelength dependence of the efficiency of inner-shell (2p) vacancy production in Xe clusters excited in underdense plasmas.

  1. Application of soft x-ray laser interferometry to study large-scale-length, high-density plasmas

    International Nuclear Information System (INIS)

    Wan, A.S.; Barbee, T.W., Jr.; Cauble, R.

    1996-01-01

    We have employed a Mach-Zehnder interferometer, using a Ne-like Y x- ray laser at 155 Angstrom as the probe source, to study large-scale- length, high-density colliding plasmas and exploding foils. The measured density profile of counter-streaming high-density colliding plasmas falls in between the calculated profiles using collisionless and fluid approximations with the radiation hydrodynamic code LASNEX. We have also performed simultaneous measured the local gain and electron density of Y x-ray laser amplifier. Measured gains in the amplifier were found to be between 10 and 20 cm -1 , similar to predictions and indicating that refraction is the major cause of signal loss in long line focus lasers. Images showed that high gain was produced in spots with dimensions of ∼ 10 μm, which we believe is caused by intensity variations in the optical drive laser. Measured density variations were smooth on the 10-μm scale so that temperature variations were likely the cause of the localized gain regions. We are now using the interferometry technique as a mechanism to validate and benchmark our numerical codes used for the design and analysis of high-energy-density physics experiments. 11 refs., 6 figs

  2. Plasma production for electron acceleration by resonant plasma wave

    International Nuclear Information System (INIS)

    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.

    2016-01-01

    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.

  3. Plasma production for electron acceleration by resonant plasma wave

    Energy Technology Data Exchange (ETDEWEB)

    Anania, M.P., E-mail: maria.pia.anania@lnf.infn.it [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Biagioni, A.; Chiadroni, E. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Cianchi, A. [University of Rome Tor Vergata - INFN, via della Ricerca Scientifica, 1, 00133 Roma (Italy); INFN, Via della Ricerca Scientifica, 1, 00133 Roma (Italy); Croia, M.; Curcio, A. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); University of Rome La Sapienza, Piazzale Aldo Moro, 2, 00185 Roma (Italy); Di Giovenale, D.; Di Pirro, G.P. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Filippi, F. [University of Rome La Sapienza, Piazzale Aldo Moro, 2, 00185 Roma (Italy); Ghigo, A.; Lollo, V.; Pella, S.; Pompili, R. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Romeo, S. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); University of Rome La Sapienza, Piazzale Aldo Moro, 2, 00185 Roma (Italy); Ferrario, M. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy)

    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.

  4. Magnetic properties of nanocrystalline CoFe{sub 2}O{sub 4} synthesized by thermal plasma in large scale

    Energy Technology Data Exchange (ETDEWEB)

    Nawale, A.B.; Kanhe, N.S. [Department of Physics, University of Pune, Pune 411007 (India); Patil, K.R. [Center for Materials Characterizations, National Chemical Laboratory, Dr. Hommi Bhabha Road, Pashan, Pune 411008 (India); Reddy, V.R.; Gupta, A. [UGC-DAE Consortium for Scientific Research, Indore Centre, University Campus, Khandwa Road, Indore 452 017 (India); Kale, B.B. [Center for Materials for Electronics Technology, Department of Information Technology, Government of India, Panchawati, Off Pashan Road, Pune 411008 (India); Bhoraskar, S.V. [Department of Physics, University of Pune, Pune 411007 (India); Mathe, V.L., E-mail: vlmathe@physics.unipune.ac.in [Department of Physics, University of Pune, Pune 411007 (India); Das, A.K. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2012-12-14

    The paper reports the large scale synthesis of nanoparticles of CoFe{sub 2}O{sub 4} using thermal plasma reactor by gas phase condensation method. The yield of formation was found to be around 15 g h{sup -1}. The magnetic properties of CoFe{sub 2}O{sub 4}, synthesized at different reactor powers, were investigated in view of studying the effect of operating parameters of plasma reactor on the structural reorganization leading to the different cation distribution. The values of saturation magnetization, coercivity and remanent magnetization were found to be influenced by input power in thermal plasma. Although the increase in saturation magnetization was marginal (61 emu g{sup -1} to 70 emu g{sup -1}) with increasing plasma power; a significant increase in the coercivity (552 Oe to 849 Oe) and remanent magnetization (16 emu g{sup -1} to 26 emu g{sup -1}) were also noticed. The Moessbauer spectra showed mixed spinel structure and canted spin order for the as synthesized nanoparticles. The detailed analysis of cation distribution using the Moessbauer spectroscopy and X-ray photoelectron spectroscopy leads to the conclusion that the sample synthesized at an optimized power shows the different site selective states. -- Highlights: Black-Right-Pointing-Pointer A rapid synthesis method for synthesizing magnetic nanoparticles of cobalt ferrite. Black-Right-Pointing-Pointer The average particle size ranges between 25 and 40 nm; as revealed by the FESEM analysis. Black-Right-Pointing-Pointer Magnetic properties are influenced by different operating parameters.

  5. Scaling of laser-plasma interactions with laser wavelength and plasma size

    International Nuclear Information System (INIS)

    Max, C.E.; Campbell, E.M.; Mead, W.C.; Kruer, W.L.; Phillion, D.W.; Turner, R.E.; Lasinski, B.F.; Estabrook, K.G.

    1983-01-01

    Plasma size is an important parameter in wavelength-scaling experiments because it determines both the threshold and potential gain for a variety of laser-plasma instabilities. Most experiments to date have of necessity produced relatively small plasmas, due to laser energy and pulse-length limitations. We have discussed in detail three recent Livermore experiments which had large enough plasmas that some instability thresholds were exceeded or approached. Our evidence for Raman scatter, filamentation, and the two-plasmon decay instability needs to be confirmed in experiments which measure several instability signatures simultaneously, and which produce more quantitative information about the local density and temperature profiles than we have today

  6. Scaling of laser-plasma interactions with laser wavelength and plasma size

    Energy Technology Data Exchange (ETDEWEB)

    Max, C.E.; Campbell, E.M.; Mead, W.C.; Kruer, W.L.; Phillion, D.W.; Turner, R.E.; Lasinski, B.F.; Estabrook, K.G.

    1983-01-25

    Plasma size is an important parameter in wavelength-scaling experiments because it determines both the threshold and potential gain for a variety of laser-plasma instabilities. Most experiments to date have of necessity produced relatively small plasmas, due to laser energy and pulse-length limitations. We have discussed in detail three recent Livermore experiments which had large enough plasmas that some instability thresholds were exceeded or approached. Our evidence for Raman scatter, filamentation, and the two-plasmon decay instability needs to be confirmed in experiments which measure several instability signatures simultaneously, and which produce more quantitative information about the local density and temperature profiles than we have today.

  7. Important plasma problems in astrophysics

    International Nuclear Information System (INIS)

    Kulsrud, R.M.

    1995-01-01

    In astrophysics, plasmas occur under very extreme conditions. For example, there are ultrastrong magnetic fields in neutron stars, relativistic plasmas around black holes and in jets, extremely energetic particles such as cosmic rays in the interstellar medium, extremely dense plasmas in accretion disks, and extremely large magnetic Reynolds numbers in the interstellar medium. These extreme limits for astrophysical plasmas make plasma phenomena much simpler to analyze in astrophysics than in the laboratory. An understanding of such phenomena often results in an interesting way, by simply taking the extreme limiting case of a known plasma theory. The author will describe one of the more exciting examples and will attempt to convey the excitement he felt when he was first exposed to it. However, not all plasma astrophysical phenomena are so simple. There are certain important plasma phenomena in astrophysics that have not been so easily resolved. In fact, a resolution of them is blocking significant progress in astrophysical research. They have not yet yielded to attacks by theoretical astrophysicists nor to extensive numerical simulation. The author will attempt to describe one of the more important of these plasma--astrophysical problems, and discuss why its resolution is so important to astrophysics. This significant example is fast, magnetic reconnection. Another significant example is the large-magnetic-Reynolds number magnetohydrodynamics (MHD) dynamos

  8. Nonlinear Plasma Waves Excitation by Intense Ion Beams in Background Plasma

    International Nuclear Information System (INIS)

    Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

    2004-01-01

    Plasma neutralization of an intense ion pulse is of interest for many applications, including plasma lenses, heavy ion fusion, cosmic ray propagation, etc. An analytical electron fluid model has been developed to describe the plasma response to a propagating ion beam. The model predicts very good charge neutralization during quasi-steady-state propagation, provided the beam pulse duration τ b is much longer than the electron plasma period 2π/ω p , where ω p = (4πe 2 n p /m) 1/2 is the electron plasma frequency and n p is the background plasma density. In the opposite limit, the beam pulse excites large-amplitude plasma waves. If the beam density is larger than the background plasma density, the plasma waves break. Theoretical predictions are compared with the results of calculations utilizing a particle-in-cell (PIC) code. The cold electron fluid results agree well with the PIC simulations for ion beam propagation through a background plasma. The reduced fluid description derived in this paper can provide an important benchmark for numerical codes and yield scaling relations for different beam and plasma parameters. The visualization of numerical simulation data shows complex collective phenomena during beam entry and exit from the plasma

  9. Nonlinear plasma waves excitation by intense ion beams in background plasma

    International Nuclear Information System (INIS)

    Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

    2004-01-01

    Plasma neutralization of an intense ion pulse is of interest for many applications, including plasma lenses, heavy ion fusion, cosmic ray propagation, etc. An analytical electron fluid model has been developed to describe the plasma response to a propagating ion beam. The model predicts very good charge neutralization during quasi-steady-state propagation, provided the beam pulse duration τ b is much longer than the electron plasma period 2π/ω p , where ω p =(4πe 2 n p /m) 1/2 is the electron plasma frequency, and n p is the background plasma density. In the opposite limit, the beam pulse excites large-amplitude plasma waves. If the beam density is larger than the background plasma density, the plasma waves break. Theoretical predictions are compared with the results of calculations utilizing a particle-in-cell (PIC) code. The cold electron fluid results agree well with the PIC simulations for ion beam propagation through a background plasma. The reduced fluid description derived in this paper can provide an important benchmark for numerical codes and yield scaling relations for different beam and plasma parameters. The visualization of numerical simulation data shows complex collective phenomena during beam entry and exit from the plasma

  10. Two approaches to the reactor-relevant high-beta plasmas with profile control in the Large Helical Device

    International Nuclear Information System (INIS)

    Ohdachi, S.; Watanabe, K.Y.; Sakakibara, S.

    2008-10-01

    From detailed optimization of configuration, volume averaged beta ∼ 5% has been achieved in the Large Helical Device(LHD). While the heating efficiency was the main point to be optimized in this approach, to form a more peaked pressure profile is another promising approach towards the high beta regime. A higher electron density profile with a steeper pressure gradient has been formed by pellet injection. From the MHD stability analysis, this peaked pressure profile is stable against the ideal MHD modes. By both approaches, the central plasma β 0 reaches about 10%. (author)

  11. Suppression of large edge-localized modes in high-confinement DIII-D plasmas with a stochastic magnetic boundary.

    Science.gov (United States)

    Evans, T E; Moyer, R A; Thomas, P R; Watkins, J G; Osborne, T H; Boedo, J A; Doyle, E J; Fenstermacher, M E; Finken, K H; Groebner, R J; Groth, M; Harris, J H; La Haye, R J; Lasnier, C J; Masuzaki, S; Ohyabu, N; Pretty, D G; Rhodes, T L; Reimerdes, H; Rudakov, D L; Schaffer, M J; Wang, G; Zeng, L

    2004-06-11

    A stochastic magnetic boundary, produced by an applied edge resonant magnetic perturbation, is used to suppress most large edge-localized modes (ELMs) in high confinement (H-mode) plasmas. The resulting H mode displays rapid, small oscillations with a bursty character modulated by a coherent 130 Hz envelope. The H mode transport barrier and core confinement are unaffected by the stochastic boundary, despite a threefold drop in the toroidal rotation. These results demonstrate that stochastic boundaries are compatible with H modes and may be attractive for ELM control in next-step fusion tokamaks.

  12. Anomalous high-frequency resistivity of a plasma

    International Nuclear Information System (INIS)

    Kruer, W.L.; Dawson, J.M.

    1971-06-01

    In one- and two-dimensional computer simulations we investigate anomalous high-frequency resistivity in a plasma driven by a large electric field oscillating near the electron plasma frequency. The large field excites the oscillating two-stream and the ion-acoustic decay instabilities in agreement with the linear theory. When the ion and electron fluctuations saturate, a strong anomalous heating of the plasma sets in. This strong heating is due to an efficient coupling of the externally imposed large electric field to the plasma by ion fluctuations. We determine the anomalous collision frequency and the saturation fluctuation amplitudes as a function of the external field amplitude and frequency, and the electron-ion mass ratio. A simple nonlinear theory gives results in reasonable agreement with simulations. 24 refs., 10 figs

  13. Influence of the electron density on the characteristics of terahertz waves generated under laser–cluster interaction

    Energy Technology Data Exchange (ETDEWEB)

    Frolov, A. A., E-mail: frolov@ihed.ras.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2016-12-15

    A theory of generation of terahertz radiation under laser–cluster interaction, developed earlier for an overdense cluster plasma [A. A. Frolov, Plasma Phys. Rep. 42. 637 (2016)], is generalized for the case of arbitrary electron density. The spectral composition of radiation is shown to substantially depend on the density of free electrons in the cluster. For an underdense cluster plasma, there is a sharp peak in the terahertz spectrum at the frequency of the quadrupole mode of a plasma sphere. As the electron density increases to supercritical values, this spectral line vanishes and a broad maximum at the frequency comparable with the reciprocal of the laser pulse duration appears in the spectrum. The dependence of the total energy of terahertz radiation on the density of free electrons is analyzed. The radiation yield is shown to increase significantly under resonance conditions, when the laser frequency is close to the eigenfrequency of the dipole or quadrupole mode of a plasma sphere.

  14. Spectroscopic measurements of plasma emission light for plasma-based acceleration experiments

    International Nuclear Information System (INIS)

    Filippi, F.; Mostacci, A.; Palumbo, L.; Anania, M.P.; Biagioni, A.; Chiadroni, E.; Ferrario, M.; Cianchi, A.; Zigler, A.

    2016-01-01

    Advanced particle accelerators are based on the excitation of large amplitude plasma waves driven by either electron or laser beams. Future experiments scheduled at the SPARC-LAB test facility aim to demonstrate the acceleration of high brightness electron beams through the so-called resonant Plasma Wakefield Acceleration scheme in which a train of electron bunches (drivers) resonantly excites wakefields into a preformed hydrogen plasma; the last bunch (witness) injected at the proper accelerating phase gains energy from the wake. The quality of the accelerated beam depends strongly on plasma density and its distribution along the acceleration length. The measurements of plasma density of the order of 10 16 –10 17  cm −3 can be performed with spectroscopic measurements of the plasma-emitted light. The measured density distribution for hydrogen filled capillary discharge with both Balmer alpha and Balmer beta lines and shot-to-shot variation are here reported.

  15. Spectroscopic measurements of plasma emission light for plasma-based acceleration experiments

    Science.gov (United States)

    Filippi, F.; Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Zigler, A.

    2016-09-01

    Advanced particle accelerators are based on the excitation of large amplitude plasma waves driven by either electron or laser beams. Future experiments scheduled at the SPARC_LAB test facility aim to demonstrate the acceleration of high brightness electron beams through the so-called resonant Plasma Wakefield Acceleration scheme in which a train of electron bunches (drivers) resonantly excites wakefields into a preformed hydrogen plasma; the last bunch (witness) injected at the proper accelerating phase gains energy from the wake. The quality of the accelerated beam depends strongly on plasma density and its distribution along the acceleration length. The measurements of plasma density of the order of 1016-1017 cm-3 can be performed with spectroscopic measurements of the plasma-emitted light. The measured density distribution for hydrogen filled capillary discharge with both Balmer alpha and Balmer beta lines and shot-to-shot variation are here reported.

  16. Plasma probe characteristics in low density hydrogen pulsed plasmas

    International Nuclear Information System (INIS)

    Astakhov, D I; Lee, C J; Bijkerk, F; Goedheer, W J; Ivanov, V V; Krivtsun, V M; Zotovich, A I; Zyryanov, S M; Lopaev, D V

    2015-01-01

    Probe theories are only applicable in the regime where the probe’s perturbation of the plasma can be neglected. However, it is not always possible to know, a priori, that a particular probe theory can be successfully applied, especially in low density plasmas. This is especially difficult in the case of transient, low density plasmas. Here, we applied probe diagnostics in combination with a 2D particle-in-cell model, to an experiment with a pulsed low density hydrogen plasma. The calculations took into account the full chamber geometry, including the plasma probe as an electrode in the chamber. It was found that the simulations reproduce the time evolution of the probe IV characteristics with good accuracy. The disagreement between the simulated and probe measured plasma density is attributed to the limited applicability of probe theory to measurements of low density pulsed plasmas on a similarly short time scale as investigated here. Indeed, in the case studied here, probe measurements would lead to, either a large overestimate, or underestimate of the plasma density, depending on the chosen probe theory. In contrast, the simulations of the plasma evolution and the probe characteristics do not suffer from such strict applicability limits. These studies show that probe theory cannot be justified through probe measurements. However, limiting cases of probe theories can be used to estimate upper and lower bounds on plasma densities. These theories include and neglect orbital motion, respectively, with different collisional terms leading to intermediate estimates. (paper)

  17. Resonances and surface waves in bounded plasmas

    International Nuclear Information System (INIS)

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

    1999-01-01

    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

  18. Helium ion distributions in a 4 kJ plasma focus device by 1 mm-thick large-size polycarbonate detectors

    Science.gov (United States)

    Sohrabi, M.; Habibi, M.; Ramezani, V.

    2014-11-01

    Helium ion beam profile, angular and iso-ion beam distributions in 4 kJ Amirkabir plasma focus (APF) device were effectively observed by the unaided eyes and studied in single 1 mm-thick large-diameter (20 cm) polycarbonate track detectors (PCTD). The PCTDs were processed by 50 Hz-HV electrochemical etching using a large-size ECE chamber. The results show that helium ions produced in the APF device have a ring-shaped angular distribution peaked at an angle of ∼ ± 60 ° with respect to the top of the anode. Some information on the helium ion energy and distributions is also provided. The method is highly effective for ion beam studies.

  19. Spherical Torus Plasma Interactions with Large-area Liquid Lithium Surfaces in CDX-U

    International Nuclear Information System (INIS)

    Kaita, R.; Majeski, R.; Boaz, M.; Efthimion, P.; Jones, B.; Hoffman, D.; Kugel, H.; Menard, J.; Munsat, T.; Post-Zwicker, A.; Soukhanovskii, V.; Spaleta, J.; Taylor, G.; Timberlake, J.; Woolley, R.; Zakharov, L.; Finkenthal, M.; Stutman, D.; Antar, G.; Doerner, R.; Luckhardt, S.; Maingi, R.; Maiorano, M.; Smith, S.

    2002-01-01

    The Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory (PPPL) is a spherical torus (ST) dedicated to the exploration of liquid lithium as a potential solution to reactor first-wall problems such as heat load and erosion, neutron damage and activation, and tritium inventory and breeding. Initial lithium limiter experiments were conducted with a toroidally-local liquid lithium rail limiter (L3) from the University of California at San Diego. Spectroscopic measurements showed a clear reduction of impurities in plasmas with the L3, compared to discharges with a boron carbide limiter. The evidence for a reduction in recycling was less apparent, however. This may be attributable to the relatively small area in contact with the plasma, and the presence of high-recycling surfaces elsewhere in the vacuum chamber. This conclusion was tested in subsequent experiments with a fully toroidal lithium limiter that was installed above the floor of the vacuum vessel. The new limiter covered over ten times the area of the L3 facing the plasma. Experiments with the toroidal lithium limiter have recently begun. This paper describes the conditioning required to prepare the lithium surface for plasma operations, and effect of the toroidal liquid lithium limiter on discharge performance

  20. Spherical Torus Plasma Interactions with Large-area Liquid Lithium Surfaces in CDX-U

    Energy Technology Data Exchange (ETDEWEB)

    R. Kaita; R. Majeski; M. Boaz; P. Efthimion; B. Jones; D. Hoffman; H. Kugel; J. Menard; T. Munsat; A. Post-Zwicker; V. Soukhanovskii; J. Spaleta; G. Taylor; J. Timberlake; R. Woolley; L. Zakharov; M. Finkenthal; D. Stutman; G. Antar; R. Doerner; S. Luckhardt; R. Maingi; M. Maiorano; S. Smith

    2002-01-18

    The Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory (PPPL) is a spherical torus (ST) dedicated to the exploration of liquid lithium as a potential solution to reactor first-wall problems such as heat load and erosion, neutron damage and activation, and tritium inventory and breeding. Initial lithium limiter experiments were conducted with a toroidally-local liquid lithium rail limiter (L3) from the University of California at San Diego. Spectroscopic measurements showed a clear reduction of impurities in plasmas with the L3, compared to discharges with a boron carbide limiter. The evidence for a reduction in recycling was less apparent, however. This may be attributable to the relatively small area in contact with the plasma, and the presence of high-recycling surfaces elsewhere in the vacuum chamber. This conclusion was tested in subsequent experiments with a fully toroidal lithium limiter that was installed above the floor of the vacuum vessel. The new limiter covered over ten times the area of the L3 facing the plasma. Experiments with the toroidal lithium limiter have recently begun. This paper describes the conditioning required to prepare the lithium surface for plasma operations, and effect of the toroidal liquid lithium limiter on discharge performance.

  1. A radioimmunoassay for neurotensin in human plasma

    International Nuclear Information System (INIS)

    Blackburn, A.M.; Bloom, S.R.

    1979-01-01

    A radioimmunoassay was developed for detecting the neurotensin peptide in human plasma. The plasma was specific for neurotensin as no cross-reaction was found with any of the other gut hormones tested. Changes of 5 pmol/l could be detected with 95% confidence. Neurotensin was unstable in both blood and plasma but considerable protection was afforded by addition of aprotinin, rapid separation of plasma and immediate deep freezing. Neurotensin-like immunoreactivity was detected in human plasma in both a small and large molecular form. The mean fasting level of plasma neurotensin-like immunoreactivity in 36 healthy volunteers was 29 +- 3 pmol/l. A significant increment of 27 +- 8 pmol/l plasma neurotensin immunoreactivity was detected after a large meal in nine healthy men. In view of the present results in man and also of neurotensin's potent pharmacological actions in experimental animals, neurotensin appears to fulfil some of the criteria needed for a hormone. (UK)

  2. Diagnostics of atmospheric pressure air plasmas

    International Nuclear Information System (INIS)

    Laux, C.O.; Kruger, C.H.; Zare, R.N.

    2001-01-01

    Atmospheric pressure air plasmas are often thought to be in Local Thermodynamics Equilibrium (LTE) owing to fast interspecies collisional exchanges at high pressure. As will be seen here, this assumption cannot be relied upon, particularly with respect to optical diagnostics. Large velocity gradients in flowing plasmas and/or elevated electron temperatures created by electrical discharges can result in large departures from chemical and thermal equilibrium. Diagnostic techniques based on optical emission spectroscopy (OES) and Cavity Ring-Down Spectroscopy (CRDS) have been developed and applied at Stanford University to the investigation of atmospheric pressure plasmas under conditions ranging from thermal and chemical equilibrium to thermochemical nonequilibrium. This article presents a review of selected temperature and species concentration measurement techniques useful for the study of air and nitrogen plasmas

  3. Direct measurement of refracted trajectory of transmitting electron cyclotron beam through plasma on the Large Helical Device

    Directory of Open Access Journals (Sweden)

    Takahashi Hiromi

    2015-01-01

    Full Text Available The electron-cyclotron (EC -beam refraction due to the presence of plasma was investigated in the Large Helical Device. The transmitted-EC-beam measurement system was constructed and the beam pattern on the opposite side of the irradiated surface was measured using an IR camera. Clear dependence of the EC-beam refraction on the electron density was observed and the beam shift in the toroidal direction showed good agreement with the ray-trace calculation of TRAVIS. The influence of the peripheral density profile and the thermal effect on the beam refraction were discussed.

  4. A Method to Construct Plasma with Nonlinear Density Enhancement Effect in Multiple Internal Inductively Coupled Plasmas

    International Nuclear Information System (INIS)

    Chen Zhipeng; Li Hong; Liu Qiuyan; Luo Chen; Xie Jinlin; Liu Wandong

    2011-01-01

    A method is proposed to built up plasma based on a nonlinear enhancement phenomenon of plasma density with discharge by multiple internal antennas simultaneously. It turns out that the plasma density under multiple sources is higher than the linear summation of the density under each source. This effect is helpful to reduce the fast exponential decay of plasma density in single internal inductively coupled plasma source and generating a larger-area plasma with multiple internal inductively coupled plasma sources. After a careful study on the balance between the enhancement and the decay of plasma density in experiments, a plasma is built up by four sources, which proves the feasibility of this method. According to the method, more sources and more intensive enhancement effect can be employed to further build up a high-density, large-area plasma for different applications. (low temperature plasma)

  5. Determination of electron temperature and density at plasma edge in the Large Helical Device with opacity-incorporated helium collisional-radiative model

    International Nuclear Information System (INIS)

    Goto, M.; Sawada, K.

    2014-01-01

    Spectra of neutral helium in the visible wavelength range are measured for a discharge in the Large Helical Device (LHD). The electron temperature (T e ) and density (n e ) are derived from the intensity distribution of helium emission lines. For that purpose, a collisional-radiative model developed by Sawada et al. [Plasma and Fusion Res. 2010;5:001] which takes the reabsorption effect into account is used. It is found that incorporation of the reabsorption effect is necessary to obtain a set of T e and n e giving consistent line intensity distribution with the measurement, and that those parameters obtained vary as the line-averaged n e changes in the course of time. The position where the helium line emission dominantly takes place is located with the help of T e and n e profiles measured by the Thomson scattering system. The result indicates that the emission position is almost fixed at the place where the connection length of the magnetic field lines to the divertor plate leaps beyond 10 m. Because intense neutral atom line emission suggests the vigorous ionization of neutral atoms, the helium line emission location determined here can be regarded as the effective boundary of the plasma. - Highlights: • The reabsorption effect is included in the helium collisional-radiative model. • Electron temperature and density are derived for the Large Helical Device (LHD). • Line emission location is found to be little changed during the discharge. • This measurement method can be used to determine the position of effective plasma boundary

  6. Arbitrary electron acoustic waves in degenerate dense plasmas

    Science.gov (United States)

    Rahman, Ata-ur; Mushtaq, A.; Qamar, A.; Neelam, S.

    2017-05-01

    A theoretical investigation is carried out of the nonlinear dynamics of electron-acoustic waves in a collisionless and unmagnetized plasma whose constituents are non-degenerate cold electrons, ultra-relativistic degenerate electrons, and stationary ions. A dispersion relation is derived for linear EAWs. An energy integral equation involving the Sagdeev potential is derived, and basic properties of the large amplitude solitary structures are investigated in such a degenerate dense plasma. It is shown that only negative large amplitude EA solitary waves can exist in such a plasma system. The present analysis may be important to understand the collective interactions in degenerate dense plasmas, occurring in dense astrophysical environments as well as in laser-solid density plasma interaction experiments.

  7. Beam-plasma discharge in a Kyoto beam-plasma-ion source

    International Nuclear Information System (INIS)

    Ishikawa, J.; Takagi, T.

    1983-01-01

    A beam-plasma type ion source employing an original operating principle has been developed by the present authors. The ion source consists of an ion extraction region with an electron gun, a thin long drift tube as the plasma production chamber, and a primary electron beam collector. An electron beam is effectively utilized for the dual purpose of high density plasma production as a result of beam-plasma discharge, and high current ion beam extraction with ion space-charge compensation. A high density plasma of the order of 10 11 --10 13 cm -3 was produced by virtue of the beam-plasma discharge which was caused by the interaction between a space-charge wave on the electron beam and a high frequency plasma wave. The plasma density then produced was 10 2 --10 3 times the density produced only by collisional ionization by the electron beam. In order to obtain a stable beam-plasma discharge, a secondary electron beam emitted from the electron collector should be utilized. The mechanism of the beam-plasma discharge was analyzed by use of a linear theory in the case of the small thermal energy of the electron beam, and by use of a quasilinear theory in the case of the large thermal energy. High current ion beams of more than 0.1 A were extracted even at a low extraction voltage of 1--5 kV

  8. Beam-generated plasmas for processing applications

    Science.gov (United States)

    Meger, R. A.; Blackwell, D. D.; Fernsler, R. F.; Lampe, M.; Leonhardt, D.; Manheimer, W. M.; Murphy, D. P.; Walton, S. G.

    2001-05-01

    The use of moderate energy electron beams (e-beams) to generate plasma can provide greater control and larger area than existing techniques for processing applications. Kilovolt energy electrons have the ability to efficiently ionize low pressure neutral gas nearly independent of composition. This results in a low-temperature, high-density plasma of nearly controllable composition generated in the beam channel. By confining the electron beam magnetically the plasma generation region can be designated independent of surrounding structures. Particle fluxes to surfaces can then be controlled by the beam and gas parameters, system geometry, and the externally applied rf bias. The Large Area Plasma Processing System (LAPPS) utilizes a 1-5 kV, 2-10 mA/cm2 sheet beam of electrons to generate a 1011-1012cm-3 density, 1 eV electron temperature plasma. Plasma sheets of up to 60×60 cm2 area have been generated in a variety of molecular and atomic gases using both pulsed and cw e-beam sources. The theoretical basis for the plasma production and decay is presented along with experiments measuring the plasma density, temperature, and potential. Particle fluxes to nearby surfaces are measured along with the effects of radio frequency biasing. The LAPPS source is found to generate large-area plasmas suitable for materials processing.

  9. Magnum-PSI: A new plasma-wall interaction experiment

    International Nuclear Information System (INIS)

    Koppers, W.; Eck, H. van; Scholten, J.

    2006-01-01

    The FOM-Institute for Plasma Physics Rijnhuizen is preparing the construction of Magnum-PSI, a magnetized (3 T), steady-state, large area (diameter 10 cm), high-flux plasma (10 24 ions m -2 s -1 generator. The aim of the linear plasma device Magnum-PSI is to provide a controlled, highly accessible laboratory experiment in which the interaction of a magnetized plasma with different surfaces can be studied in detail. Plasma parameters can be varied over a wide range, in particular covering the high-density, low-temperature conditions expected for the detached divertor plasma of ITER. The target set-up will be extremely flexible allowing the investigation of different materials under a large variety of conditions (temperatures, inclination, biasing, coatings, etc.). A range of target materials will be used, including carbon, tungsten and other metals, and mixed materials. Because of the large plasma beam of 10 cm diameter and spacious vacuum tank, even the test of whole plasma-facing component mock-ups will be possible. Dedicated diagnostics will be installed to allow for detailed studies of the fundamental physics and chemistry of plasma-surface interaction, such as erosion and deposition, hydrogen recycling, retention and removal, dust and layer formation, plasma sheath physics and heat loads (steady-state or transient). Magnum-PSI will be a unique experiment to address the ITER divertor physics which will essentially differ from present day Tokamak and/or linear plasma generator physics. In this contribution, we will present the pre-design of the Magnum-PSI experiment. We will discuss the requirements on the vacuum system, 3T superconducting magnet, plasma source, target manipulator and additional plasma heating. In addition, we will briefly introduce the plasma and surface diagnostics that will be used in the Magnum-PSI experiment. (author)

  10. Pregnancy-associated plasma protein A in a large cohort of Type 1 diabetic patients with and without diabetic nephropathy-a prospective follow--up study

    DEFF Research Database (Denmark)

    Astrup, A S; Tarnow, L; Christiansen, M

    2007-01-01

    AIM: Pregnancy-associated plasma protein A (PAPP-A) has been implicated in the aetiology of acute coronary syndromes and carotid and peripheral artherosclerosis. Diabetic nephropathy is characterized by increased cardiovascular risk. We investigated the prognostic value of PAPP-A in a large cohor...

  11. Large volume serial section tomography by Xe Plasma FIB dual beam microscopy

    International Nuclear Information System (INIS)

    Burnett, T.L.; Kelley, R.; Winiarski, B.; Contreras, L.; Daly, M.; Gholinia, A.; Burke, M.G.; Withers, P.J.

    2016-01-01

    Ga + Focused Ion Beam-Scanning Electron Microscopes (FIB-SEM) have revolutionised the level of microstructural information that can be recovered in 3D by block face serial section tomography (SST), as well as enabling the site-specific removal of smaller regions for subsequent transmission electron microscope (TEM) examination. However, Ga + FIB material removal rates limit the volumes and depths that can be probed to dimensions in the tens of microns range. Emerging Xe + Plasma Focused Ion Beam-Scanning Electron Microscope (PFIB-SEM) systems promise faster removal rates. Here we examine the potential of the method for large volume serial section tomography as applied to bainitic steel and WC–Co hard metals. Our studies demonstrate that with careful control of milling parameters precise automated serial sectioning can be achieved with low levels of milling artefacts at removal rates some 60× faster. Volumes that are hundreds of microns in dimension have been collected using fully automated SST routines in feasible timescales (<24 h) showing good grain orientation contrast and capturing microstructural features at the tens of nanometres to the tens of microns scale. Accompanying electron back scattered diffraction (EBSD) maps show high indexing rates suggesting low levels of surface damage. Further, under high current Ga + FIB milling WC–Co is prone to amorphisation of WC surface layers and phase transformation of the Co phase, neither of which have been observed at PFIB currents as high as 60 nA at 30 kV. Xe + PFIB dual beam microscopes promise to radically extend our capability for 3D tomography, 3D EDX, 3D EBSD as well as correlative tomography. - Highlights: • The uptake of dual beam FIBs has been rapid but long milling times have limited imaged volumes to tens of micron dimensions. • Emerging plasma Xe + PFIB-SEM technology offers materials removal rates at least 60× greater than conventional Ga + FIB systems with comparable or less damage. • The

  12. Thermal self-focusing with multiple beams

    International Nuclear Information System (INIS)

    Craxton, R.S.; McCrory, R.L.

    1986-07-01

    Self-focusing in underdense plasmas in the presence of overlapping beams is of interest for multibeam laser-irradiation systems. The hydrodynamics/ray-tracing simulation code SAGE is used to model thermal self-focusing in two-dimensional line-focus geometry with beams incident obliquely at different angles. The conjecture that multiple overlapping beams may suppress self-focusing is investigated for parameters appropriate to reactor-sized targets; in particular, the dependence upon intensity, scale length and pulse width is examined. While the full problem is three-dimensional, insight may be gained from two-dimensional simulations

  13. International Conference on Plasma Physics ICPP 1994. Proceedings

    International Nuclear Information System (INIS)

    Sakanaka, P.H.; Tendler, M.

    1995-01-01

    These proceedings represent the papers presented at the 1994 International Conference on Plasma Physics held in Foz do Iguacu, Brazil. The scope of the conference was broad and covered all aspects of plasma physics. Some of the topics discussed include space and astrophysical plasmas,fusion plasmas, small and large Tokamak plasmas, non-Tokamak plasmas, inertial confinement fusion plasmas, plasma based neutron sources and plasma applications. There are 60 papers in these proceedings and out of these, 35 have been abstracted for the Energy Science and Technology database

  14. MAGNUM-PSI, a plasma generator for plasma-surface interaction research in ITER-like conditions

    International Nuclear Information System (INIS)

    Goedheer, W.J.; Rooij, G.J. van; Veremiyenko, V.; Ahmad, Z.; Barth, C.J.; Eck, H.J.N. van; Groot, B. de; Hellermann, M.G. von; Kruijtzer, G.L.; Wolff, J.C.; Brezinsek, S.; Philipps, V.; Pospieszczyk, A.; Samm, U.; Schweer, B.; Dahiya, R.P.; Engeln, R.A.H.; Schram, D.C.; Fantz, U.; Kleyn, A.W.; Lopes Cardozo, N.J.

    2005-01-01

    The FOM-Institute for Plasma Physics - together with its TEC partners - is preparing the construction of Magnum-psi, a magnetized (3 T), steady-state, large area (100 cm 2 ), high-flux (up to 10 24 H + ions m -2 s -1 ) plasma generator. The research programme of Magnum-psi will address the questions for the ITER divertor: erosion, redeposition and hydrogen retention with carbon substrates, melting of metal surfaces, erosion and redeposition with mixed materials. In order to explore and develop the techniques to be applied in Magnum-psi, a pilot experiment (Pilot-psi), operating at a magnetic field up to 1.6 Tesla, has been constructed. Pilot-psi produces a hydrogen plasma beam with the required parameters (T e ≤ 1eV and flux ≥ 10 23 m -2 s -1 ) over an area of 1 cm 2 . In this paper the results of extensive diagnostic measurements on Pilot-psi (a.o., Thomson Scattering and high-resolution spectroscopy), combined with numerical studies of the source and the expansion of the plasma will be presented to demonstrate the feasibility of the large Magnum-psi plasma generator. (author)

  15. Remote plasma sputtering of indium tin oxide thin films for large area flexible electronics

    International Nuclear Information System (INIS)

    Yeadon, A.D.; Wakeham, S.J.; Brown, H.L.; Thwaites, M.J.; Whiting, M.J.; Baker, M.A.

    2011-01-01

    Indium tin oxide (ITO) thin films with a specific resistivity of 3.5 × 10 −4 Ω cm and average visible light transmission (VLT) of 90% have been reactively sputtered onto A4 Polyethylene terephthalate (PET), glass and silicon substrates using a remote plasma sputtering system. This system offers independent control of the plasma density and the target power enabling the effect of the plasma on ITO properties to be studied. Characterization of ITO on glass and silicon has shown that increasing the plasma density gives rise to a decrease in the specific resistivity and an increase in the optical band gap of the ITO films. Samples deposited at plasma powers of 1.5 kW, 2.0 kW and 2.5 kW and optimized oxygen flow rates exhibited specific resistivity values of 3.8 × 10 −4 Ω cm, 3.7 × 10 −4 Ω cm and 3.5 × 10 −4 Ω cm and optical gaps of 3.48 eV, 3.51 eV and 3.78 eV respectively. The increase in plasma density also influenced the crystalline texture and the VLT increased from 70 to 95%, indicating that more oxygen is being incorporated into the growing film. It has been shown that the remote plasma sputter technique can be used in an in-line process to produce uniform ITO coatings on PET with specific resistivities of between 3.5 × 10 −4 and 4.5 × 10 −4 Ω cm and optical transmission of greater than 85% over substrate widths of up to 30 cm.

  16. The plasma position control of ITER EDA plasma

    International Nuclear Information System (INIS)

    Senda, Ikuo; Nishio, Satoshi; Tsunematsu, Toshihide; Nishino, Toru; Fujieda, Hirobumi.

    1994-09-01

    The study on the plasma position control of ITER EDA performed by Japan Home Team during the sensitivity study in 1994 is summarized. The controllabilities of plasmas in the Outline Design and elongated version are compared. The model used to describe the motion of the plasma is a rigid model. The PD feedback control is applied with respect to the displacements of the plasma from the equilibrium. Three types of fluctuations, which initiate the motion of the plasma, are examined, namely a finite horizontal fluctuation field, a small horizontal fluctuation field such that the motion of the plasma is governed by the passive structures and an abrupt change of the poloidal beta β p and internal inductance l i . In the simulations of finite horizontal fluctuation fields, controls depend on the strength of the fluctuations, for instance, 3-5V is needed for 5-10G of fluctuation fields in the Outline Design. When the fluctuation field is small and the plasma displacement grows in a characteristic time of the passive structures, a few volt of the control voltage is enough to obtain good controllability. It is shown that the control when (β p , l i ) changes simultaneously is demanding and a large control voltage is required to maintain satisfactory control. Comparing the elongated version with the Outline Design, the control voltage which is larger than the Outline Design by a factor of 2-3 is required to obtain the same controllability in the elongated version. (author)

  17. The effect of plasma minor-radius expansion in the current build-up phase of a large tokamak

    International Nuclear Information System (INIS)

    Kobayashi, Tomofumi; Tazima, Teruhiko; Tani, Keiji; Tamura, Sanae

    1977-03-01

    A plasma simulation code has been developed to study the plasma current build-up process in JT-60. Plasma simulation is made with a model which represents well overall plasma behavior of the present-day tokamaks. The external electric circuit is taken into consideration in simulation calculation. An emphasis is placed on the simulation of minor-radius expansion of the plasma and behavior of neutral particles in the plasma during current build-up. A calculation with typical parameters of JT-60 shows a week skin distribution in the current density and the electron temperature, if the minor radius of the plasma expands with build-up of the plasma current. (auth.)

  18. 2. Basis of measurement of plasma flow. 2.3 Plasma flow measurements. Spectroscopic methods

    International Nuclear Information System (INIS)

    Kado, Shinichiro

    2007-01-01

    The construction of optical system, optical fiber incident system, reciprocal linear dispersion, grating smile and astigmatism of the reflection plane diffraction grating spectrometer are explained in order to measure the plasma flow. The specification of flow measurement and evaluation of 0 point of velocity are stated. For examples of measurements, the fine structures of He II (Δn = 3 - 4) in material and plasma(MAP)-II of Tokyo University, plasma flow measurement by the charge exchange recombination spectroscopy using Large Helical Device and by Zeeman spectroscopy using TRIAM-1M tokamak plasma are stated. (S.Y.)

  19. Extended steady-state and high-beta regimes of net-current free heliotron plasmas in the Large Helical Device

    International Nuclear Information System (INIS)

    Motojima, O.; Yamada, H.; Komori, A.; Ohyabu, N.; Mutoh, T.; Kaneko, O.; Kawahata, K.; Mito, T.; Ida, K.; Imagawa, S.; Nagayama, Y.; Shimozuma, T.; Watanabe, K.Y.; Masuzaki, S.; Miyazawa, J.; Morisaki, T.; Morita, S.; Ohdachi, S.; Ohno, N.; Saito, K.; Sakakibara, S.; Takeiri, Y.; Tamura, N.; Toi, K.; Tokitani, M.; Yokoyama, M.; Yoshinuma, M.; Ikeda, K.; Isayama, A.; Ishii, K.; Kubo, S.; Murakami, S.; Nagasaki, K.; Seki, T.; Takahata, K.; Takenaga, H.

    2007-01-01

    The performance of net-current free heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fuelling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an internal diffusion barrier (IDB) by a combination of efficient pumping of the local island divertor function and core fuelling by pellet injection has realized a super dense core as high as 5 x 10 20 m -3 , which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5% and a discharge duration of 54 min with a total input energy of 1.6 GJ (490 kW on average) are also highlighted. The progress of LHD experiments in these two years is overviewed by highlighting IDB, high β and long pulse

  20. Plasma properties of a modified beam-plasma type ion source

    International Nuclear Information System (INIS)

    Ishikawa, Junzo; Sano, Fumimichi; Tsuji, Hiroshi; Ektessabi, A.M.; Takagi, Toshinori

    1978-01-01

    The properties of the plasma produced by beam-plasma discharge were experimentally investigated. The ion source used for this work consists of three parts, that is, the ion-extracting region with an electron gun, the drift space and the collector region. Primary and secondary electron beams are injected in to the drift tube. The interaction between plasma and these electron beams causes production of high density plasma by virtue of the beam-plasma discharge. The gas inlet is located in the middle of the drift tube, so that the gas conductance is high. The energy of the primary and secondary electron beams is transferred to that microwaves through beam-plasma interaction. The microwaves heat the plasma electrons by the cyclotron resonance or other mechanism. The amount of the energetic plasma electrons is much larger than that of the beam electrons, so that neutral gas is ionized. The density of the produced plasma is 10 2 or 10 3 times as large as the plasma produced by impact ionization. With a probe located in the middle of the drift tube, the plasma density and the electron temperature can be measured, and the power and spectra of the microwaves can be detected. The microwave oscillation, the primary electron beam characteristics, and the gas pressure characteristics were studied. Larger current of the high energy primary of secondary electron beam is required for the effective discharge. The ion source has to be operated at the minimum gas pressure. The length of beam-plasma interaction and the magnetic field intensity in the drift tube are also important parameters. (Kato, T.)

  1. Plasma kinetics issues in an ESA study for a plasma laboratory in space

    International Nuclear Information System (INIS)

    Annaratone, B M; Biancalani, A; Ceccherini, F; Pegoraro, F; Bruno, D; Capitelli, M; Pascale, O de; Longo, S; Daly, E; Hilgers, A; Diomede, P; D'Ammando, G; Marcuccio, S; Mendonca, J T; Nagnibeda, V; Sanmartin, J R

    2008-01-01

    A study supported by the European Space Agency (ESA), in the context of its General Studies Programme, performed an investigation of the possible use of space for studies in pure and applied plasma physics, in areas not traditionally covered by 'space plasma physics'. A set of experiments have been identified that can potentially provide access to new phenomena and to allow advances in several fields of plasma science. These experiments concern phenomena on a spatial scale (10 1 -10 4 m) intermediate between what is achievable on the ground and the usual solar system plasma observations. Detailed feasibility studies have been performed for three experiments: active magnetic experiments, large-scale discharges and long tether-plasma interactions. The perspectives opened by these experiments are discussed for magnetic reconnection, instabilities, MHD turbulence, atomic excited states kinetics, weakly ionized plasmas, plasma diagnostics, artificial auroras and atmospheric studies. The discussion is also supported by results of numerical simulations and estimates

  2. IslandFAST: A Semi-numerical Tool for Simulating the Late Epoch of Reionization

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yidong; Chen, Xuelei [Key Laboratory for Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Yue, Bin [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2017-08-01

    We present the algorithm and main results of our semi-numerical simulation, islandFAST, which was developed from 21cmFAST and designed for the late stage of reionization. The islandFAST simulation predicts the evolution and size distribution of the large-scale underdense neutral regions (neutral islands), and we find that the late Epoch of Reionization proceeds very fast, showing a characteristic scale of the neutral islands at each redshift. Using islandFAST, we compare the impact of two types of absorption systems, i.e., the large-scale underdense neutral islands versus small-scale overdense absorbers, in regulating the reionization process. The neutral islands dominate the morphology of the ionization field, while the small-scale absorbers dominate the mean-free path of ionizing photons, and also delay and prolong the reionization process. With our semi-numerical simulation, the evolution of the ionizing background can be derived self-consistently given a model for the small absorbers. The hydrogen ionization rate of the ionizing background is reduced by an order of magnitude in the presence of dense absorbers.

  3. Hot-ion Bernstein wave with large kparallel

    International Nuclear Information System (INIS)

    Ignat, D.W.; Ono, M.

    1995-01-01

    The complex roots of the hot plasma dispersion relation in the ion cyclotron range of frequencies have been surveyed. Progressing from low to high values of perpendicular wave number k perpendicular we find first the cold plasma fast wave and then the well-known Bernstein wave, which is characterized by large dispersion, or large changes in k perpendicular for small changes in frequency or magnetic field. At still higher k perpendicular there can be two hot plasma waves with relatively little dispersion. The latter waves exist only for relatively large k parallel, the wave number parallel to the magnetic field, and are strongly damped unless the electron temperature is low compared to the ion temperature. Up to three mode conversions appear to be possible, but two mode conversions are seen consistently

  4. A mechanism for large divertor plasma energy loss via lithium radiation in tokamaks

    Science.gov (United States)

    Rognlien, T. D.; Meier, E. T.; Soukhanovskii, V. A.

    2012-10-01

    Lithium has been used as a wall-conditioning element in a number of tokamaks over the years, including TFTR, FTU, and NSTX, where core plasma energy confinement and particle control are often found to improve following such conditioning. Here the possible role of Li in providing substantial energy loss for divertor plasmas via line radiation is reported. A multi-charge-state 2D UEDGE fluid model is used where the hydrogenic and Li ions and neutrals are each evolved as separate species and separate equations are solved for the electron and ion temperatures. It is shown that a sufficient level of Li neutrals evolving from the divertor surface via sputtering or evaporation can induce energy detachment of the divertor plasma, yielding a strongly radiating zone near the divertor where ionization and recombination from/to neutral Li can radiate most of the power flowing into the scrape-off layer while maintaining low core contamination. A local peaking of Li emissivity for electron temperatures near 1 eV appears to play an important role in the detachment of the mixed deuterium/Li plasma. Evidence of such behavior from NSTX discharges will be discussed.

  5. Equation of state of partially-ionized dense plasmas

    International Nuclear Information System (INIS)

    Rogers, F.J.

    1989-01-01

    This paper describes methods for calculating the equation of state of partially-ionized dense plasmas. The term dense plasma is used rather than strongly coupled plasma, since it is possible that at plasma conditions such that only a few levels can be observed spectroscopically the plasma coupling parameters are not large. Due mainly to their importance in theoretical astrophysics, the properties of partially ionized plasmas have been of interest for a long while. More recently, this interest has intensified due to the development of methods for producing partially ionized plasmas in the laboratory. This has opened up large programs of experimental investigation and of practical application. In this paper we consider detailed statistical mechanical methods that explicitly treat the distribution over ionic species and their energy level structure. These detailed approaches are generally characterized as being in the ''chemical picture'' when a free energy expression is minimized or in the ''physical picture'' when the starting point is the grand canonical ensemble. 52 refs., 2 tabs

  6. Observation of electron plasma waves in plasma of two-temperature electrons

    International Nuclear Information System (INIS)

    Ikezawa, Shunjiro; Nakamura, Yoshiharu.

    1981-01-01

    Propagation of electron plasma waves in a large and unmagnetized plasma containing two Maxwellian distributions of electrons is studied experimentally. Two kinds of plasma sources which supply electrons of different temperature are used. The temperature ratio is about 3 and the density ratio of hot to cool electrons is varied from 0 to 0.5. A small contamination of hot electrons enhances the Landau damping of the principal mode known as the Bohm-Gross mode. When the density of hot electrons is larger than about 0.2, two modes are observed. The results agree with theoretical dispersion relations when excitation efficiencies of the modes are considered. (author)

  7. Damping Measurements of Plasma Modes

    Science.gov (United States)

    Anderegg, F.; Affolter, M.; Driscoll, C. F.

    2010-11-01

    For azimuthally symmetric plasma modes in a magnesium ion plasma, confined in a 3 Tesla Penning-Malmberg trap with a density of n ˜10^7cm-3, we measure a damping rate of 2s-1plasma column, alters the frequency of the mode from 16 KHz to 192 KHz. The oscillatory fluid displacement is small compared to the wavelength of the mode; in contrast, the fluid velocity, δvf, can be large compared to v. The real part of the frequency satisfies a linear dispersion relation. In long thin plasmas (α> 10) these modes are Trivelpiece-Gould (TG) modes, and for smaller values of α they are Dubin spheroidal modes. However the damping appears to be non-linear; initially large waves have weaker exponential damping, which is not yet understood. Recent theoryootnotetextM.W. Anderson and T.M. O'Neil, Phys. Plasmas 14, 112110 (2007). calculates the damping of TG modes expected from viscosity due to ion-ion collisions; but the measured damping, while having a similar temperature and density dependence, is about 40 times larger than calculated. This discrepancy might be due to an external damping mechanism.

  8. Large acoustic solitons and double layers in plasmas with two positive ion species

    International Nuclear Information System (INIS)

    Verheest, Frank; Hellberg, Manfred A.; Saini, Nareshpal Singh; Kourakis, Ioannis

    2011-01-01

    Large nonlinear acoustic waves are discussed in a plasma made up of cold supersonic and adiabatic subsonic positive ions, in the presence of hot isothermal electrons, with the help of Sagdeev pseudopotential theory. In this model, no solitons are found at the acoustic speed, and no compositional parameter ranges exist where solutions of opposite polarities can coexist. All nonlinear modes are thus super-acoustic, but polarity changes are possible. The upper limits on admissible structure velocities come from different physical arguments, in a strict order when the fractional cool ion density is increased: infinite cold ion compression, warm ion sonic point, positive double layers, negative double layers, and finally, positive double layers again. However, not all ranges exist for all mass and temperature ratios. Whereas the cold and warm ion sonic point limitations are always present over a wide range of mass and temperature ratios, and thus positive polarity solutions can easily be obtained, double layers have a more restricted existence range, specially if polarity changes are sought.

  9. Plasma catalysis for nitrogen fixation reactions

    NARCIS (Netherlands)

    Patil, B.S.; Wang, Q.; Hessel, V.; Lang, J.; Stankiewicz, A.; Stefanidis, G.

    2016-01-01

    The preferences for localized chemicals production and changing scenarios of renewable electricity cost gives a renewed boost to plasma-assisted valuable chemicals production. Especially, plasma-assisted nitrogen fixation for fertilizer production has the potential to largely change the energy

  10. Coherent structures in two-dimensional plasma turbulence

    DEFF Research Database (Denmark)

    Huld, T.; Nielsen, A.H.; Pécseli, H.L.

    1991-01-01

    -band turbulent fluctuations is demonstrated by a conditional sampling technique. Depending on plasma parameters, the dominant structures can appear as monopole or multipole vortices, dipole vortices in particular. The importance of large structures for the turbulent plasma diffusion is discussed. A statistical...... analysis of the randomly varying plasma flux is presented....

  11. Beat-wave generation of plasmons in semiconductor plasmas

    International Nuclear Information System (INIS)

    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

  12. Ion-Ion Plasmas Produced by Electron Beams

    Science.gov (United States)

    Fernsler, R. F.; Leonhardt, D.; Walton, S. G.; Meger, R. A.

    2001-10-01

    The ability of plasmas to etch deep, small-scale features in materials is limited by localized charging of the features. The features charge because of the difference in electron and ion anisotropy, and thus one solution now being explored is to use ion-ion plasmas in place of electron-ion plasmas. Ion-ion plasmas are effectively electron-free and consist mainly of positive and negative ions. Since the two ion species behave similarly, localized charging is largely eliminated. However, the only way to produce ion-ion plasmas at low gas pressure is to convert electrons into negative ions through two-body attachment to neutrals. While the electron attachment rate is large at low electron temperatures (Te < 1 eV) in many of the halogen gases used for processing, these temperatures occur in most reactors only during the afterglow when the heating fields are turned off and the plasma is decaying. By contrast, Te is low nearly all the time in plasmas produced by electron beams, and therefore electron beams can potentially produce ion-ion plasmas continuously. The theory of ion-ion plasmas formed by pulsed electron beams is examined in this talk and compared with experimental results presented elsewhere [1]. Some general limitations of ion-ion plasmas, including relatively low flux levels, are discussed as well. [1] See the presentation by D. Leonhardt et al. at this conference.

  13. Resistive Magnetohydrodynamics Simulation of Fusion Plasmas

    International Nuclear Information System (INIS)

    Tang, X.Z.; Fu, G.Y.; Jardin, S.C.; Lowe, L.L.; Park, W.; Strauss, H.R.

    2001-01-01

    Although high-temperature plasmas in laboratory magnetic fusion confinements are sufficiently collisionless that formal fluid closures are difficult to attain, the resistive MHD model has proven, by comparison with experimental data, to be useful for describing the large scale dynamics of magnetized plasmas. Resistive MHD model consists of Faraday's law for the evolution of the magnetic field and Navier-Stokes equation for the plasma flow. These equations are closed by the Ohm's law and an equation of state for the plasma

  14. Laboratory simulation of energetic flows of magnetospheric planetary plasma

    International Nuclear Information System (INIS)

    Shaikhislamov, I F; Posukh, V G; Melekhov, A V; Boyarintsev, E L; Zakharov, Yu P; Prokopov, P A; Ponomarenko, A G

    2017-01-01

    Dynamic interaction of super-sonic counter-streaming plasmas moving in dipole magnetic dipole is studied in laboratory experiment. First, a quasi-stationary flow is produced by plasma gun which forms a magnetosphere around the magnetic dipole. Second, explosive plasma expanding from inner dipole region outward is launch by laser beams focused at the surface of the dipole cover. Laser plasma is energetic enough to disrupt magnetic field and to sweep through the background plasma for large distances. Probe measurements showed that far from the initially formed magnetosphere laser plasma carries within itself a magnetic field of the same direction but order of magnitude larger in value than the vacuum dipole field at considered distances. Because no compression of magnetic field at the front of laser plasma was observed, the realized interaction is different from previous experiments and theoretical models of laser plasma expansion into uniform magnetized background. It was deduced based on the obtained data that laser plasma while expanding through inner magnetosphere picks up a magnetized shell formed by background plasma and carries it for large distances beyond previously existing magnetosphere. (paper)

  15. Radio images of the interplanetary turbulent plasma

    International Nuclear Information System (INIS)

    Vlasov, V.I.

    1979-01-01

    The results of the interplanetary scintillation daily observations of approximately 140 radio sources are given. The observations were carried out at the radiotelescope VLPA FIAN during 24 days in October-November 1975 and 6 days in April 1976. The maps (radio images) of interplanetary turbulent plasma are presented. The analysis of the maps reveals the presence of large-scale irregularities in the interplanetary plasma. The variability in large-scale structure of the interplanetary plasma is due mainly to transport of matter from the Sun. A comparison of the scintillation with the geomagnetic activity index detected the presence of a straight connection between them

  16. Confinement of plasma along shaped open magnetic fields from the centrifugal force of supersonic plasma rotation.

    Science.gov (United States)

    Teodorescu, C; Young, W C; Swan, G W S; Ellis, R F; Hassam, A B; Romero-Talamas, C A

    2010-08-20

    Interferometric density measurements in plasmas rotating in shaped, open magnetic fields demonstrate strong confinement of plasma parallel to the magnetic field, with density drops of more than a factor of 10. Taken together with spectroscopic measurements of supersonic E × B rotation of sonic Mach 2, these measurements are in agreement with ideal MHD theory which predicts large parallel pressure drops balanced by centrifugal forces in supersonically rotating plasmas.

  17. Plasma flow in the DIII-D divertor

    International Nuclear Information System (INIS)

    Boedo, J.A.; Porter, G.D.; Schaffer, M.J.

    1998-07-01

    Indications that flows in the divertor can exhibit complex behavior have been obtained from 2-D modeling but so far remain mostly unconfirmed by experiment. An important feature of flow physics is that of flow reversal. Flow reversal has been predicted analytically and it is expected when the ionization source arising from neutral or impurity ionization in the divertor region is large, creating a high pressure zone. Plasma flows arise to equilibrate the pressure. A radiative divertor regime has been proposed in order to reduce the heat and particle fluxes to the divertor target plates. In this regime, the energy and momentum of the plasma are dissipated into neutral gas introduced in the divertor region, cooling the plasma by collisional, radiative and other atomic processes so that the plasma becomes detached from the target plates. These regimes have been the subject of extensive studies in DIII-D to evaluate their energy and particle transport properties, but only recently it has been proposed that the energy transport over large regions of the divertor must be dominated by convection instead of conduction. It is therefore important to understand the role of the plasma conditions and geometry on determining the region of convection-dominated plasma in order to properly control the heat and particle fluxes to the target plates and hence, divertor performance. The authors have observed complex structures in the deuterium ion flows in the DIII-D divertor. Features observed include reverse flow, convective flow over a large volume of the divertor and stagnant flow. They have measured large gradients in the plasma potential across the separatrix in the divertor and determined that these gradients induce poloidal flows that can potentially affect the particle balance in the divertor

  18. Effects of positron density and temperature on large amplitude ion-acoustic waves in an electron-positron-ion plasma

    International Nuclear Information System (INIS)

    Nejoh, Y.N.

    1997-01-01

    The nonlinear wave structures of large amplitude ion-acoustic waves are studied in a plasma with positrons. We have presented the region of existence of the ion-acoustic waves by analysing the structure of the pseudopotential. The region of existence sensitively depends on the positron to electron density ratio, the ion to electron mass ratio and the positron to electron temperature ratio. It is shown that the maximum Mach number increases as the positron temperature increases and the region of existence of the ion-acoustic waves spreads as the positron temperature increases. 12 refs., 6 figs

  19. Large plasma density enhancements occurring in the northern polar region during the 6 April 2000 superstorm

    Science.gov (United States)

    Horvath, Ildiko; Lovell, Brian C.

    2014-06-01

    We focus on the ionospheric response of northern high-latitude region to the 6 April 2000 superstorm and aim to investigate how the storm-enhanced density (SED) plume plasma became distributed in the regions of auroral zone and polar cap plus to study the resultant ionospheric features and their development. Multi-instrument observational results combined with model-generated, two-cell convection maps permitted identifying the high-density plasma's origin and the underlying plasma transportation processes. Results show the plasma density feature of polar cap enhancement (PCE; 600 × 103 i+/cm3) appearing for 7 h during the main phase and characterized by increases reaching up to 6 times of the quiet time values. Meanwhile, strong westward convections ( 17,500 m/s) created low plasma densities in a wider region of the dusk cell. Oppositely, small ( 750 m/s) but rigorous westward drifts drove the SED plume plasma through the auroral zone, wherein plasma densities doubled. As the SED plume plasma traveled along the convection streamlines and entered the polar cap, a continuous enhancement of the tongue of ionization (TOI) developed under steady convection conditions. However, convection changes caused slow convections and flow stagnations and thus segmented the TOI feature by locally depleting the plasma in the affected regions of the auroral zone and polar cap. From the strong correspondence of polar cap potential drop and subauroral polarization stream (SAPS), we conclude that the SAPS E-field strength remained strong, and under its prolonged influence, the SED plume provided a continuous supply of downward flowing high-density plasma for the development and maintenance of PCEs.

  20. Beat-wave generation of plasmons in semiconductor plasmas

    International Nuclear Information System (INIS)

    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 semiconductor (for example n-type InSb), the system can simulate the physics underlying beat wave generation in relativistic gaseous plasmas. (author). 7 refs

  1. Modified DLC coatings prepared in a large-scale reactor by dual microwave/pulsed-DC plasma-activated chemical vapour deposition

    International Nuclear Information System (INIS)

    Corbella, C.; Bialuch, I.; Kleinschmidt, M.; Bewilogua, K.

    2008-01-01

    Diamond-Like Carbon (DLC) films find abundant applications as hard and protective coatings due to their excellent mechanical and tribological performances. The addition of new elements to the amorphous DLC matrix tunes the properties of this material, leading to an extension of its scope of applications. In order to scale up their production to a large plasma reactor, DLC films modified by silicon and oxygen additions have been grown in an industrial plant of 1m 3 by means of pulsed-DC plasma-activated chemical vapour deposition (PACVD). The use of an additional microwave (MW) source has intensified the glow discharge, partly by electron cyclotron resonance (ECR), accelerating therefore the deposition process. Hence, acetylene, tetramethylsilane (TMS) and hexamethyldisiloxane (HMDSO) constituted the respective gas precursors for the deposition of a-C:H (DLC), a-C:H:Si and a-C:H:Si:O films by dual MW/pulsed-DC PACVD. This work presents systematic studies of the deposition rate, hardness, adhesion, abrasive wear and water contact angle aimed to optimize the technological parameters of deposition: gas pressure, relative gas flow of the monomers and input power. This study has been completed with measures of the atomic composition of the samples. Deposition rates around 1 μm/h, typical for standard processes held in the large reactor, were increased about by a factor 10 when the ionization source has been operated in ECR mode

  2. A large amount synthesis of nanopowder using modulated induction thermal plasmas synchronized with intermittent feeding of raw materials

    International Nuclear Information System (INIS)

    Tanaka, Y; Tsuke, T; Guo, W; Uesugi, Y; Ishijima, T; Watanabe, S; Nakamura, K

    2012-01-01

    A large amount synthesis method for titanium dioxide (TiO 2 ) nanopowder is proposed by direct evaporation of titanium powders using Ar-O 2 pulse-modulated induction thermal plasma (PMITP). To realize a large amount synthesis of nanopowder, the PMITP method was combined with the intermittent and heavy load feeding of raw material powder, as well as the quenching gas injection. The intermittent powder feeding was synchronized with the modulation of the coil current sustaining the PMITP for complete evaporation of the injected powder. Synthesized particles by the developed method were analyzed by FE-SEM and XRD. Results indicated that the synthesized particles by the 20-kW PMITP with a heavy loading rate of 12.3 g min −1 had a similar particle size distribution with the mean diameter about 40 nm to those with light loading of 4.2 g min −1 .

  3. Investigation of arcing on fiber-formed nanostructured tungsten by pulsed plasma during steady state plasma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yajima, M., E-mail: yajima.miyuki@LHD.nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, 509-5292 Japan (Japan); Ohno, N. [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kajita, S. [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); De Temmerman, G. [ITER Organization, Route de Vinon sur Verdon, CS 90 046-13067 St Paul Lez Durance Cedex (France); Bystrov, K.; Bardin, S.; Morgan, T.W. [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Partner in the Trilateral Euregio Cluster, 5612 AJ Eindhoven (Netherlands); Masuzaki, S. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, 509-5292 Japan (Japan)

    2016-11-15

    Arcing on fiber-formed nanostructured tungsten samples during ELM-like pulses was investigated using the superimposition of high power pulsed plasma on a steady state plasma with hydrogen gas in the linear plasma device Pilot-PSI. The ignition of arcing was observed when the floating potential of the samples was less than −75 V with sufficient heat flux. The surface observation showed that the arc spots were not in the center, but in the peripheral area of the plasma column. Considering the plasma potential profile in the Pilot-PSI, the arcing occurred at the position where the heat flux and the sheath potential drop are sufficiently large.

  4. Interaction of the electromagnetic waves and non-magnetized plasmas

    International Nuclear Information System (INIS)

    Sun Aiping; Qiu Xiaoming; Dong Yuying; Li Liqiong

    2002-01-01

    The propagation of electromagnetic waves with 0.5 - 10 GHz in a non-magnetized collisional plasma slab is studied numerically. The change in the absorbed power, reflected power and transmitted power of the electromagnetic wave with collisional frequency of electrons and neutral atoms in plasma from 0.1 - 10 GHz, is calculated, in the condition of the uniform plasma with density of 10 10 or 10 11 cm -3 and depth of 10 cm, and the non-uniform plasma with density distribution of n = n 0 exp[2(z/d-1)] and depth of 10 cm, respectively. The results show that the absorbed power in either uniform or non-uniform plasma is large when the plasma density is large and collision frequency is high, and the peak value is 90%

  5. Nonlinear neoclassical transport in toroidal edge plasmas

    International Nuclear Information System (INIS)

    Fueloep, T.; Helander, P.

    2001-01-01

    In conventional neoclassical theory, the density and temperature gradients are not allowed to be as steep as frequently observed in the tokamak edge. In this paper the theory of neoclassical transport in a collisional, impure plasma is extended to allow for steeper profiles than normally assumed. The dynamics of highly charged impurity ions then becomes nonlinear, which affects the transport of all species. As earlier found in the banana regime, when the bulk plasma gradients are large the impurity ions undergo a poloidal redistribution, which reduces their parallel friction with the bulk ions and suppresses the neoclassical ion particle flux. The neoclassical confinement is thus improved in regions with large radial gradients. When the plasma is collisional and the gradients are large, the impurities accumulate on the inboard side of the torus

  6. Computational Methods in Plasma Physics

    CERN Document Server

    Jardin, Stephen

    2010-01-01

    Assuming no prior knowledge of plasma physics or numerical methods, Computational Methods in Plasma Physics covers the computational mathematics and techniques needed to simulate magnetically confined plasmas in modern magnetic fusion experiments and future magnetic fusion reactors. Largely self-contained, the text presents the basic concepts necessary for the numerical solution of partial differential equations. Along with discussing numerical stability and accuracy, the author explores many of the algorithms used today in enough depth so that readers can analyze their stability, efficiency,

  7. The plasma focus as a large fluence neutron source

    International Nuclear Information System (INIS)

    Zucker, O.; Bostick, W.; Long, J.; Luce, J.; Sahlin, H.

    1977-01-01

    A continuously operated, 1 pps, dense-plasma-focus device capable of delivering a minimum of 10 15 neutrons per pulse for material testing purposes is described. With I 5 scaling, predicted from analysis of existing machines, yields of 10 16 -10 17 neutrons per pulse are postulated. The average power consumption, which has become a major issue as a result of the energy crisis is shown to be highly favorable. A novel approach to the capacitor bank and switch design allowing repetitive operation is discussed. (Auth.)

  8. Low temperature diamond growth by linear antenna plasma CVD over large area

    International Nuclear Information System (INIS)

    Izak, Tibor; Babchenko, Oleg; Potocky, Stepan; Kromka, Alexander; Varga, Marian

    2012-01-01

    Recently, there is a great effort to increase the deposition area and decrease the process temperature for diamond growth which will enlarge its applications including use of temperature sensitive substrates. In this work, we report on the large area (20 x 30 cm 2 ) and low temperature (250 C) polycrystalline diamond growth by pulsed linear antenna microwave plasma system. The influence of substrate temperature varied from 250 to 680 C, as controlled by the table heater and/or by microwave power, is studied. It was found that the growth rate, film morphology and diamond to non-diamond phases (sp 3 /sp 2 carbon bonds) are influenced by the growth temperature, as confirmed by SEM and Raman measurements. The surface chemistry and growth processes were studied in terms of activation energies (E a ) calculated from Arrhenius plots. The activation energies of growth processes were very low (1.7 and 7.8 kcal mol -1 ) indicating an energetically favourable growth process from the CO 2 -CH 4 -H 2 gas mixture. In addition, from activation energies two different growth regimes were observed at low and high temperatures, indicating different growth mechanism. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Plasma Electronics. Theoretical and Experimental Investigations of Plasma Nonlinearity in the Powerful Microwave Oscillators

    International Nuclear Information System (INIS)

    Bliokh, Yu.P.

    2001-01-01

    During more than 50 years of Plasma Electronics development a great number of experimental and theoretical results have been achieved. These results allow understanding of physical processes which originate under charged particles beams interaction with a plasma. However, one essential aspect of such interaction remains insufficiently studied. The question is about a correlation between conditions of microwave excitation by a beam in plasma and plasma parameters. Each of these effects, namely the influence of plasma parameters on conditions of microwave excitation by a beam and plasma parameters variations under the influence of propagating microwave radiation are well known and investigated enough. However their common action under beam-plasma instability (BPI) development were not studied systematically, although the role of such reciprocal influence on character of these processes may be very large. The aim of this report is a review of recent theoretical and experimental investigations of such plasma nonlinearity in plasma-filled trawling-wave tubes. N.M.Zemlyansky and E.A.Kornilov have done experiments in Kharkov Institute of Physics and Technology (KhPhTI). Development of the theoretical model was started in KhPhTI (Yu.P.Bliokh, Ya.B.Fainberg, M.G.Lyubarsky, and V.O.Podobinsky) and continues by author in Technion. The developed theory takes into account two main reasons of the plasma density redistribution: high frequency pressure (HFP) force which ''push out'' plasma from the regions with increased microwave amplitude, or microwave discharge, which appears in the region where amplitude is large enough. Displaced (under HFP action) or additionally originating (under (BPD) development) plasma propagates from the disturbance source in the form of slow plasma waves (for example, ion-sound or magneto-sound waves), and the BPI develops in the nonhomogeneous plasma. It changes both magnitude and longitudinal distribution of excited microwave amplitude. As a result

  10. Lipid organization of the plasma membrane

    NARCIS (Netherlands)

    Ingólfsson, Helgi I; Melo, Manuel N; van Eerden, Floris J; Arnarez, Clément; Lopez, Cesar A; Wassenaar, Tsjerk A; Periole, Xavier; de Vries, Alex H; Tieleman, D Peter; Marrink, Siewert J

    2014-01-01

    The detailed organization of cellular membranes remains rather elusive. Based on large-scale molecular dynamics simulations, we provide a high-resolution view of the lipid organization of a plasma membrane at an unprecedented level of complexity. Our plasma membrane model consists of 63 different

  11. Laboratory simulation of space plasma phenomena*

    Science.gov (United States)

    Amatucci, B.; Tejero, E. M.; Ganguli, G.; Blackwell, D.; Enloe, C. L.; Gillman, E.; Walker, D.; Gatling, G.

    2017-12-01

    Laboratory devices, such as the Naval Research Laboratory's Space Physics Simulation Chamber, are large-scale experiments dedicated to the creation of large-volume plasmas with parameters realistically scaled to those found in various regions of the near-Earth space plasma environment. Such devices make valuable contributions to the understanding of space plasmas by investigating phenomena under carefully controlled, reproducible conditions, allowing for the validation of theoretical models being applied to space data. By working in collaboration with in situ experimentalists to create realistic conditions scaled to those found during the observations of interest, the microphysics responsible for the observed events can be investigated in detail not possible in space. To date, numerous investigations of phenomena such as plasma waves, wave-particle interactions, and particle energization have been successfully performed in the laboratory. In addition to investigations such as plasma wave and instability studies, the laboratory devices can also make valuable contributions to the development and testing of space plasma diagnostics. One example is the plasma impedance probe developed at NRL. Originally developed as a laboratory diagnostic, the sensor has now been flown on a sounding rocket, is included on a CubeSat experiment, and will be included on the DoD Space Test Program's STP-H6 experiment on the International Space Station. In this presentation, we will describe several examples of the laboratory investigation of space plasma waves and instabilities and diagnostic development. *This work supported by the NRL Base Program.

  12. Plasma Reforming of Liquid Hydrocarbon Fuels in Non-Thermal Plasma-Liquid Systems

    Science.gov (United States)

    2010-04-30

    channel with liquid wall in the microporous media under the ultrasound cavitations has shown the following: · The action of the ultrasound field in the...microporous liquid which has a very large ratio of the plasma-liquid contact surface to the plasma volume. As is known the ultrasonic (US) cavitation is a very...2) and it ran over a flat dielectric surface of the magnetostrictive transmitter (5) which produced ultrasonic (US) cavitations , so the discharge

  13. Nonlinear neoclassical theory for toroidal edge plasmas

    International Nuclear Information System (INIS)

    Fueloep, T.; Helander, P.

    2001-01-01

    Edge plasma processes play a critical role for the global confinement of the plasma. In the edge region, where impurity ions are abundant and the temperature and density gradients are large, the assumptions of the standard neoclassical theory break down. We have extended the theory of neoclassical transport in an impure plasma with arbitrary cross section and aspect ratio to allow for steeper pressure and temperature gradients than are usually considered in the conventional theory. The gradients are allowed to be so large that the friction force between the bulk ions and heavy impurities is comparable to the parallel impurity pressure gradient. In this case the impurity ions are found to undergo a spontaneous rearrangement on each flux surface. This reduces their parallel friction with the bulk ions and causes the neoclassical ion flux to become a non-monotonic function of the gradients for plasma parameters typical of the tokamak edge. Thus, the neoclassical confinement is improved in regions where the gradients are large, such as in the edge pedestal. The theoretical predictions are compared with experimental data from several tokamaks. (orig.)

  14. Energetic ion driven Alfven eigenmodes in Large Helical Device plasmas with three-dimensional magnetic structure and their impact on energetic ion transport

    International Nuclear Information System (INIS)

    Toi, K; Yamamoto, S; Nakajima, N; Ohdachi, S; Sakakibara, S; Osakabe, M; Murakami, S; Watanabe, K Y; Goto, M; Kawahata, K; Kolesnichenko, Ya I; Masuzaki, S; Morita, S; Narihara, K; Narushima, Y; Takeiri, Y; Tanaka, K; Tokuzawa, T; Yamada, H; Yamada, I; Yamazaki, K

    2004-01-01

    In the Large Helical Device (LHD), energetic ion driven Alfven eigenmodes (AEs) and their impact on energetic ion transport have been studied. The magnetic configuration of the LHD is three-dimensional and has negative magnetic shear over a whole plasma radius in the low beta regime. These features introduce the characteristic structures of the shear Alfven spectrum. In particular, a core-localized type of toroidicity-induced AE (TAE) is most likely because the TAE gap frequency rapidly increases towards the plasma edge. Moreover, helicity-induced AEs (HAEs) can be generated through a toroidal mode coupling as well as poloidal one in the three-dimensional configuration. The following experimental results have been obtained in LHD plasmas heated by tangential neutral beam injection: (1) observation of core-localized TAEs having odd as well as even parity, (2) eigenmode transition of the core-localized TAE to global AEs (GAEs), which phenomenon is very similar to that in a reversed shear tokamak, (3) observation of HAEs of which the frequency is about eight times higher than the TAE gap frequency, (4) enhanced radial transport/loss of energetic ions caused by bursting TAEs in a relatively high beta regime, and (5) seed formation of internal transport barriers induced by TAE-induced energetic ion transport. These results will be important and interesting information for AE physics in toroidal plasmas

  15. Large volume serial section tomography by Xe Plasma FIB dual beam microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Burnett, T.L. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); FEI Company, Achtseweg Noord 5, Bldg, 5651 GG, Eindhoven (Netherlands); Kelley, R. [FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, OR 97124 (United States); Winiarski, B. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); FEI Company, Achtseweg Noord 5, Bldg, 5651 GG, Eindhoven (Netherlands); Contreras, L. [FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, OR 97124 (United States); Daly, M.; Gholinia, A.; Burke, M.G. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Withers, P.J., E-mail: P.J.Withers@manchester.ac.uk [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); BP International Centre for Advanced Materials, University of Manchester, Manchester M13 9PL (United Kingdom)

    2016-02-15

    Ga{sup +} Focused Ion Beam-Scanning Electron Microscopes (FIB-SEM) have revolutionised the level of microstructural information that can be recovered in 3D by block face serial section tomography (SST), as well as enabling the site-specific removal of smaller regions for subsequent transmission electron microscope (TEM) examination. However, Ga{sup +} FIB material removal rates limit the volumes and depths that can be probed to dimensions in the tens of microns range. Emerging Xe{sup +} Plasma Focused Ion Beam-Scanning Electron Microscope (PFIB-SEM) systems promise faster removal rates. Here we examine the potential of the method for large volume serial section tomography as applied to bainitic steel and WC–Co hard metals. Our studies demonstrate that with careful control of milling parameters precise automated serial sectioning can be achieved with low levels of milling artefacts at removal rates some 60× faster. Volumes that are hundreds of microns in dimension have been collected using fully automated SST routines in feasible timescales (<24 h) showing good grain orientation contrast and capturing microstructural features at the tens of nanometres to the tens of microns scale. Accompanying electron back scattered diffraction (EBSD) maps show high indexing rates suggesting low levels of surface damage. Further, under high current Ga{sup +} FIB milling WC–Co is prone to amorphisation of WC surface layers and phase transformation of the Co phase, neither of which have been observed at PFIB currents as high as 60 nA at 30 kV. Xe{sup +} PFIB dual beam microscopes promise to radically extend our capability for 3D tomography, 3D EDX, 3D EBSD as well as correlative tomography. - Highlights: • The uptake of dual beam FIBs has been rapid but long milling times have limited imaged volumes to tens of micron dimensions. • Emerging plasma Xe{sup +} PFIB-SEM technology offers materials removal rates at least 60× greater than conventional Ga{sup +} FIB systems with

  16. Control of plasma density distribution via wireless power transfer in an inductively coupled plasma

    International Nuclear Information System (INIS)

    Lee, Hee-Jin; Lee, Hyo-Chang; Kim, Young-Cheol; Chung, Chin-Wook

    2013-01-01

    With an enlargement of the wafer size, development of large-area plasma sources and control of plasma density distribution are required. To control the spatial distribution of the plasma density, wireless power transfer is applied to an inductively coupled plasma for the first time. An inner powered antenna and an outer resonant coil connected to a variable capacitor are placed on the top of the chamber. As the self-resonance frequency ω r of the resonant coil is adjusted, the power transfer rate from the inner powered coil to the outer resonant coil is changed and the dramatic evolution of the plasma density profile is measured. As ω r of the outer resonant coil changes from the non-resonant condition (where ω r is not the driving angular frequency ω rf ) to the resonant condition (where ω r = ω rf ), the plasma density profile evolves from a convex shape with maximal plasma density at the radial center into a concave shape with maximal plasma density in the vicinity of the resonant antenna coil. This result shows that the plasma density distribution can be successfully controlled via wireless resonance power transfer. (fast track communication)

  17. RELATIVISTIC CYCLOTRON INSTABILITY IN ANISOTROPIC PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    López, Rodrigo A.; Moya, Pablo S.; Muñoz, Víctor; Valdivia, J. Alejandro [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Navarro, Roberto E.; Araneda, Jaime A. [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Viñas, Adolfo F., E-mail: rlopez186@gmail.com [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, MD 20771 (United States)

    2016-11-20

    A sufficiently large temperature anisotropy can sometimes drive various types of electromagnetic plasma micro-instabilities, which can play an important role in the dynamics of relativistic pair plasmas in space, astrophysics, and laboratory environments. Here, we provide a detailed description of the cyclotron instability of parallel propagating electromagnetic waves in relativistic pair plasmas on the basis of a relativistic anisotropic distribution function. Using plasma kinetic theory and particle-in-cell simulations, we study the influence of the relativistic temperature and the temperature anisotropy on the collective and noncollective modes of these plasmas. Growth rates and dispersion curves from the linear theory show a good agreement with simulations results.

  18. A one-dimensional collisional model for plasma-immersion ion implantation

    International Nuclear Information System (INIS)

    Vahedi, V.; Lieberman, M.A.; Alves, M.V.; Verboncoeur, J.P.; Birdsall, C.K.

    1991-01-01

    Plasma-immersion ion implantation (also known as plasma-source ion implantation) is a process in which a target is immersed in a plasma and a series of large negative-voltage pulses are applied to it to extract ions from the plasma and implant them into the target. A general one-dimensional model is developed to study this process in different coordinate systems for the case in which the pressure of the neutral gas is large enough that the ion motion in the sheath can be assumed to be highly collisional

  19. Interaction physics in the context of ICF with the LIL facility

    International Nuclear Information System (INIS)

    Labaune, C.; Depierreux, S.; Riazuelo, G.; Tikhonchuk, V.T.; Stenz, C.; Nicolai, P.; Borisenko, N.G.; Hueller, S.

    2010-01-01

    Complete text of publication follows. Laser-plasma interaction physics is one of the main challenges of Inertial Confinement Fusion. Experiments in large-scale, high temperature, plasmas are needed to understand the physics of parametric instabilities, mainly the stimulated Brillouin and Raman scattering and filamentation. Experimental results obtained with well-defined interaction conditions are needed to test the numerical simulations still under development and to improve the target design. To be carried out with long length and high temperature plasmas, the experiments require multikilojoule laser beams, a careful choice of targets and sophisticated diagnostics. The LIL (Ligne d'Integration Laser) facility has been used with foam layer targets to study interaction physics in underdense plasma, in the millimeter scale, at temperature around 2 keV. The LIL facility delivers 12 kJ of 3σ light in pulses of 2.7 ns in a quadruplet. Low-density foams (3 to 10 mg/cc) with lengths in the range (300 μm, 1 mm) and very small microstructures (∼ μm) have been used. The plasma parameters, electron density, velocity, temperature profiles, were obtained from hydrodynamics simulations with the code CHIC and HERA. The numerical results were compared with the experimental measurements of longitudinal X-ray images at different times, the temporal evolution of the transmitted light through the foam, and the overall energy balance. Results will be presented on the beam propagation through the foam, plasma induced smoothing, the reduction of the imprint and stimulated Brillouin and Raman scattering. The interpretation of these results is achieved by means of various interaction codes, PARAX, HARMONY and HERA.

  20. The laser, measuring instrument for plasmas

    International Nuclear Information System (INIS)

    Anderegg, F.; Behn, R.; Paris, P.J.; Salito, S.A.; Siegrist, M.R.; Weisen, H.

    1988-06-01

    There are several different and in general complementary methods for the investigation of plasmas. All of them have different characteristics and properties covering a large spectrum of physical measuring techniques. Electromagnetic waves serving as 'thermometers' permit to detect the global behaviour of the plasma as well as that of the particles composing it. One of the advantages of these introspective methods is that it brings information on temporary and local conditions of the domain being interrogated. With the development of micro-wave sources and lasers after the war the principal tools of this type of plasma diagnostics are now available. In this paper the emphasis is on the lasers which are different according to the type of measurement. Their versatility in measuring plasma parameters is largely acknowledged. We illustrate the potential of measuring methods by lasers by means of the research work done at two experimental installations of CRPP. (author) 21 figs., 8 refs

  1. Neutral Atom Diffusion in a Partially Ionized Prominence Plasma

    Science.gov (United States)

    Gilbert, Holly

    2010-01-01

    The support of solar prominences is normally described in terms of a magnetic force on the prominence plasma that balances the solar gravitational force. Because the prominence plasma is only partially ionized. it is necessary to consider in addition the support of the neutral component of the prominence plasma. This support is accomplished through a frictional interaction between the neutral and ionized components of the plasma, and its efficacy depends strongly on the degree of ionization of the plasma. More specifically, the frictional force is proportional to the relative flow of neutral and ion species, and for a sufficiently weakly ionized plasma, this flow must be relatively large to produce a frictional force that balances gravity. A large relative flow, of course, implies significant draining of neutral particles from the prominence. We evaluate the importance of this draining effect for a hydrogen-helium plasma, and consider the observational evidence for cross-field diffusion of neutral prominence material,

  2. Design and test of a large plasma torch for environmental recycling

    International Nuclear Information System (INIS)

    Tuszewski, M.

    1996-01-01

    A 2.5-inch inductive plasma torch has been tested with up to 600 kW rf power and with argon, nitrogen, and oxygen gases. A complete power balance is obtained from electrical, thermal, and radiation measurements. These data indicate that torch efficiencies of up to 30% are obtained with molecular gases, while efficiencies around 15% are obtained with argon. The efficiencies obtained with molecular gases almost triple earlier torch efficiencies and confirm substantially the predictions of a torch model developed during a previous CRADA. Torch efficiencies of up to 50% could be obtained in future tests with an improved rf power supply, with steam gas, and with larger torch dimensions. Future applications of the Plasma Energy Recycle and Conversion (PERC) process could include the high explosives of DOE's nuclear weapons, chemical and biological remediation, and the treatment and volume reduction of radioactive mixed waste

  3. Industrial application of the decomposition of CO2 . NOx by large flow atmospheric microwave plasma LAMP employed in motorcar

    Science.gov (United States)

    Pandey, Anil; Niwa, Syunta; Morii, Yoshinari; Ikezawa, Shunjiro

    2012-10-01

    In order to decompose CO2 . NOx [1], we have developed the large flow atmospheric microwave plasma; LAMP [2]. It is very important to apply it for industrial innovation, so we have studied to apply the LAMP into motorcar. The characteristics of the developed LAMP are that the price is cheap and the decomposition efficiencies of CO2 . NOx are high. The mechanism was shown as the vertical configuration between the exhaust gas pipe and the waveguide was suitable [2]. The system was set up in the car body with a battery and an inverter. The battery is common between the engine and the inverter. In the application of motorcar, the flow is large, so the LAMP which has the merits of large flow, high efficient decomposition, and cheap apparatus will be superior.[4pt] [1] H. Barankova, L. Bardos, ISSP 2011, Kyoto.[0pt] [2] S. Ikezawa, S. Parajulee, S. Sharma, A. Pandey, ISSP 2011, Kyoto (2011) pp. 28-31; S. Ikezawa, S. Niwa, Y. Morii, JJAP meeting 2012, March 16, Waseda U. (2012).

  4. Resonant transducers for solid-state plasma density modulation

    Energy Technology Data Exchange (ETDEWEB)

    Hallock, Gary A., E-mail: hallock@ece.utexas.edu [The University of Texas at Austin, Austin, Texas 78701 (United States); Meier, Mark A., E-mail: mark.a.meier@exxonmobil.com [ExxonMobil Upstream Research Company, Houston, Texas 77389 (United States)

    2016-04-15

    We have developed transducers capable of modulating the plasma density and plasma density gradients in indium antimonide. These transducers make use of piezoelectric drivers to excite acoustic pressure resonance at 3λ/2, generating large amplitude standing waves and plasma density modulations. The plasma density has been directly measured using a laser diagnostic. A layered media model shows good agreement with the experimental measurements.

  5. Sheared-flow induced confinement transition in a linear magnetized plasma

    Science.gov (United States)

    Zhou, S.; Heidbrink, W. W.; Boehmer, H.; McWilliams, R.; Carter, T. A.; Vincena, S.; Friedman, B.; Schaffner, D.

    2012-01-01

    A magnetized plasma cylinder (12 cm in diameter) is induced by an annular shape obstacle at the Large Plasma Device [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)]. Sheared azimuthal flow is driven at the edge of the plasma cylinder through edge biasing. Strong fluctuations of density and potential (δn /n~eδφ/kTe~0.5) are observed at the plasma edge, accompanied by a large density gradient (Ln=|∇lnn |-1~2cm) and shearing rate (γ ~300kHz). Edge turbulence and cross-field transport are modified by changing the bias voltage (Vbias) on the obstacle and the axial magnetic field (Bz) strength. In cases with low Vbias and large Bz, improved plasma confinement is observed, along with steeper edge density gradients. The radially sheared flow induced by E ×B drift dramatically changes the cross-phase between density and potential fluctuations, which causes the wave-induced particle flux to reverse its direction across the shear layer. In cases with higher bias voltage or smaller Bz, large radial transport and rapid depletion of the central plasma density are observed. Two-dimensional cross-correlation measurement shows that a mode with azimuthal mode number m =1 and large radial correlation length dominates the outward transport in these cases. Linear analysis based on a two-fluid Braginskii model suggests that the fluctuations are driven by both density gradient (drift wave like) and flow shear (Kelvin-Helmholtz like) at the plasma edge.

  6. Sheared-flow induced confinement transition in a linear magnetized plasma

    International Nuclear Information System (INIS)

    Zhou, S.; Heidbrink, W. W.; Boehmer, H.; McWilliams, R.; Carter, T. A.; Vincena, S.; Friedman, B.; Schaffner, D.

    2012-01-01

    A magnetized plasma cylinder (12 cm in diameter) is induced by an annular shape obstacle at the Large Plasma Device [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)]. Sheared azimuthal flow is driven at the edge of the plasma cylinder through edge biasing. Strong fluctuations of density and potential (δn/n∼eδφ/kT e ∼0.5) are observed at the plasma edge, accompanied by a large density gradient (L n =∇lnn -1 ∼2cm) and shearing rate (γ∼300kHz). Edge turbulence and cross-field transport are modified by changing the bias voltage (V bias ) on the obstacle and the axial magnetic field (B z ) strength. In cases with low V bias and large B z , improved plasma confinement is observed, along with steeper edge density gradients. The radially sheared flow induced by ExB drift dramatically changes the cross-phase between density and potential fluctuations, which causes the wave-induced particle flux to reverse its direction across the shear layer. In cases with higher bias voltage or smaller B z , large radial transport and rapid depletion of the central plasma density are observed. Two-dimensional cross-correlation measurement shows that a mode with azimuthal mode number m=1 and large radial correlation length dominates the outward transport in these cases. Linear analysis based on a two-fluid Braginskii model suggests that the fluctuations are driven by both density gradient (drift wave like) and flow shear (Kelvin-Helmholtz like) at the plasma edge.

  7. Numerical simulation of electrostatic waves in plasmas

    International Nuclear Information System (INIS)

    Erz, U.

    1981-08-01

    In this paper the propagation of electrostatic waves in plasmas and the non-linear interactions, which occur in the case of large wave amplitudes, are studied using a new numerical method for plasma simulation. This mathematical description is based on the Vlasov-model. Changes in the distribution-function are taken into account and thus plasma kinetic effects can be treated. (orig./HT) [de

  8. Characterization of laser-induced plasmas as a complement to high-explosive large-scale detonations

    Directory of Open Access Journals (Sweden)

    Clare Kimblin

    2017-09-01

    Full Text Available Experimental investigations into the characteristics of laser-induced plasmas indicate that LIBS provides a relatively inexpensive and easily replicable laboratory technique to isolate and measure reactions germane to understanding aspects of high-explosive detonations under controlled conditions. Spectral signatures and derived physical parameters following laser ablation of aluminum, graphite and laser-sparked air are examined as they relate to those observed following detonation of high explosives and as they relate to shocked air. Laser-induced breakdown spectroscopy (LIBS reliably correlates reactions involving atomic Al and aluminum monoxide (AlO with respect to both emission spectra and temperatures, as compared to small- and large-scale high-explosive detonations. Atomic Al and AlO resulting from laser ablation and a cited small-scale study, decay within ∼10-5 s, roughly 100 times faster than the Al and AlO decay rates (∼10-3 s observed following the large-scale detonation of an Al-encased explosive. Temperatures and species produced in laser-sparked air are compared to those produced with laser ablated graphite in air. With graphite present, CN is dominant relative to N2+. In studies where the height of the ablating laser’s focus was altered relative to the surface of the graphite substrate, CN concentration was found to decrease with laser focus below the graphite surface, indicating that laser intensity is a critical factor in the production of CN, via reactive nitrogen.

  9. Complete plasma dropouts at Vela satellites during thinning of the plasma sheet

    International Nuclear Information System (INIS)

    Lui, A.T.Y.; Hones, E.W. Jr.; Venkatesan, D.; Akasofu, S.; Bame, S.J.

    1975-01-01

    Five satellite years of Vela data are examined for plasma sheet thinnings. Complete proton disappearances (plasma dropouts) are the main subject here. During such times, the Vela satellite is temporarily in the high-latitude tail lobe. The distribution of such plasma dropouts within the magnetotail suggests that the semithickness of the plasma sheet near midnight seldom reaches less than 1 R/sub E/ during substorms and that the dawn and dusk portions of the plasma sheet remain thicker than the midnight portion. But it is also shown that the plasma sheet occasionally becomes very thin near the dusk magnetopause. No such severe thinnings of the plasma sheet are found near the dawn magnetopause. Plasma dropouts can occur regardless of the sign of the Z component of the IMF, but their frequency of occurrence seems to be greater when the Z component is negative.Three plasma dropouts which occurred in the midnight sector at unusually large distances from the estimated position of the neutral sheet were observed during geomagnetic storms. It is likely that the midnight sector of the plasma sheet can become very thick (approx.18 R/sub E/) at certain times during the main phase of storms. Detailed measurements in the plasma sheet were obtained near the beginning of a geomagnetic storm whose sc triggered a substorm. A compression of the plasma sheet at X/sub SM/approx. =-15 R/sub E/ occurred about 10 min after the sc onset at the earth and about 5 min after the start of plasma sheet thinning associated with the sc-related substorm. If compression-thinning of the plasma sheet initiated this substorm, the triggering action must have occurred earthward of X/sub SM/approx. =-15 R/sub E/

  10. A periodic plasma waveguide accelerator

    International Nuclear Information System (INIS)

    Cole, F.T.

    1985-01-01

    The increasing cost of synchrotrons and storage rings has given new interest in the search for new methods of acceleration. The primary goal of this search is very large accelerating fields, because the cost of an accelerator to reach TeV energies is dominated by costs that scale with length. Very large electric fields are possible in plasmas and in lasers and many geometries are being studied that make use of plasmas, lasers, or combinations of them. In a plasma accelerator, the plasma can have several different functions. It may act as a medium for the propagation of accelerating electric-field waves. In addition, these waves may also act as a source of the energy needed to accelerate particles. Accelerators using various waves in plasmas have been built and studied in many laboratories. The device proposed here is an attempt to separate the two functions of providing a medium and providing an energy source. A relatively low-energy electron beam is used as a non-neutral plasma only to make a slow-wave medium for the propagation of an externally generated wave. The wave is a TM electromagnetic wave and the device may be thought of as a conventional electron linear accelerator with the evacuated volume and metallic envelope replaced by the electron beam. A separate second beam, which may be electrons or heavier particles, is accelerated. The application in mind here is a single-pass collider

  11. Tokamak plasma variations under rapid compression

    International Nuclear Information System (INIS)

    Holmes, J.A.; Peng, Y.K.M.; Lynch, S.J.

    1980-04-01

    Changes in plasmas undergoing large, rapid compressions are examined numerically over the following range of aspect ratios A:3 greater than or equal to A greater than or equal to 1.5 for major radius compressions of circular, elliptical, and D-shaped cross sections; and 3 less than or equal to A less than or equal to 6 for minor radius compressions of circular and D-shaped cross sections. The numerical approach combines the computation of fixed boundary MHD equilibria with single-fluid, flux-surface-averaged energy balance, particle balance, and magnetic flux diffusion equations. It is found that the dependences of plasma current I/sub p/ and poloidal beta anti β/sub p/ on the compression ratio C differ significantly in major radius compressions from those proposed by Furth and Yoshikawa. The present interpretation is that compression to small A dramatically increases the plasma current, which lowers anti β/sub p/ and makes the plasma more paramagnetic. Despite large values of toroidal beta anti β/sub T/ (greater than or equal to 30% with q/sub axis/ approx. = 1, q/sub edge/ approx. = 3), this tends to concentrate more toroidal flux near the magnetic axis, which means that a reduced minor radius is required to preserve the continuity of the toroidal flux function F at the plasma edge. Minor radius compressions to large aspect ratio agree well with the Furth-Yoshikawa scaling laws

  12. High energy plasma accelerators

    International Nuclear Information System (INIS)

    Tajima, T.

    1985-05-01

    Colinear intense laser beams ω 0 , kappa 0 and ω 1 , kappa 1 shone on a plasma with frequency separation equal to the electron plasma frequency ω/sub pe/ are capable of creating a coherent large longitudinal electric field E/sub L/ = mc ω/sub pe//e of the order of 1GeV/cm for a plasma density of 10 18 cm -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

  13. Plasma Equilibrium Control in Nuclear Fusion Devices 2. Plasma Control in Magnetic Confinement Devices 2.1 Plasma Control in Tokamaks

    Science.gov (United States)

    Fukuda, Takeshi

    The plasma control technique for use in large tokamak devices has made great developmental strides in the last decade, concomitantly with progress in the understanding of tokamak physics and in part facilitated by the substantial advancement in the computing environment. Equilibrium control procedures have thereby been established, and it has been pervasively recognized in recent years that the real-time feedback control of physical quantities is indispensable for the improvement and sustainment of plasma performance in a quasi-steady-state. Further development is presently undertaken to realize the “advanced plasma control” concept, where integrated fusion performance is achieved by the simultaneous feedback control of multiple physical quantities, combined with equilibrium control.

  14. Discontinuities in Jovian sulphur plasma

    Energy Technology Data Exchange (ETDEWEB)

    Mekler, Y [Jet Propulsion Lab., Pasadena, CA (USA); Eviatar, A; Siscoe, G L

    1979-10-01

    In recent years, the Jovian sulphur nebula, which is the only component of the thermal plasma in the magnetosphere of Jupiter which emits in the visible, has been the subject of considerable study. A large number of investigators have come up with widely differing models for the density, composition and temperature of the Jovian magnetospheric plasma. In this paper a different characteristic of the sulphur emission, namely its radial distribution is discussed and an attempt is made to assess its implications for the plasma and magnetic field configuration of the inner magnetosphere of Jupiter.

  15. NRL Fact Book 2010

    Science.gov (United States)

    2010-01-01

    Energetic materials/explosives Aerogels and underdense materials Nanoscale materials Nondestructive evaluation Ceramics and composite materials Thin...facility with high spatial density near field acoustic holography and 3D laser vibrometry for diagnosing large structures, including aircraft interiors...especially impact of organic matter Map data formatting facility compresses map infor- mation onto CD-ROM media for masters for use in aircraft digital

  16. On the refuelling of large divertor experiments

    International Nuclear Information System (INIS)

    Staebler, A.; Haas, G.; Ott, W.; Speth, E.

    1976-01-01

    The use of fast hydrogen atoms, molecules and clusters for refuelling large divertor-experiments like ASDEX is investigated. Three criteria for the choice among the various methods are discussed. It is shown that clusters suffer from lack of penetration. Molecules, created by fragmentation of clusters, offer the advantage of plasma-like energy combined with appreciable penetration. Large penetration and high ionization efficiency can only be achieved at energies for above the plasma temperature with H 0 -atoms of several tens of keV

  17. Instabilities observed at the bubble edge of a laser produced plasma during its expansion in an ambient tenuous plasma

    Science.gov (United States)

    Lee, Bo Ram; Clark, S. E.; Hoffmann, D. H. H.; Niemann, C.

    2014-10-01

    The Raptor kJ class 1053 nm Nd:Glass laser in the Phoenix laser laboratory at University of California, Los Angeles, is used to ablate a dense debris plasma from a graphite or plastic target embedded in a tenuous, uniform, and quiescent ambient magnetized plasma in the Large Plasma Device (LAPD) which provides a peak plasma density of ni ~ 1013 cm-3. Its background magnetic field can vary between 200 and 1200 G. Debris ions from laser produced plasma expand out conically with super-Alfvénic speed (MA ~ 2) and expel the background magnetic field and ambient ions to form a diamagnetic bubble. The debris plasma interacts with the ambient plasma and the magnetic field and acts as a piston which can create collisionless shocks. Flute-type instabilities, which are probably large Larmor radius Rayleigh Taylor instabilities or lower hybrid drift instabilities, are developed at the bubble edge and also observed in the experiment. The amplitude and wavelength dependence of the instabilities, which might be a strong function of debris to ambient mass to charge ratio, is studied and the experimental results are compared to the two dimensional hybrid simulations. the Deutsche Forschungsgemeinschaft in the framework of the Excellence Initiative Darmstadt Graduate School of Energy Science and Engineering (GSC1070).

  18. Effects of plasma treatment on wounds

    NARCIS (Netherlands)

    Tipa, R.S.; Stoffels - Adamowicz, E.; Lim, C.T.; Goh, J.C.H.

    2009-01-01

    Cold plasma treatment of wounds is gaining much interest, because it will offer a non-contact, painless and harmless therapy to manage large-area lesions (burn wounds, chronic ulcerations). One of the important issues in plasma wound healing is the safety of the method. In this work we study in

  19. Coherent vortical structures in two-dimensional plasma turbulence

    DEFF Research Database (Denmark)

    Pécseli, H.L.; Coutsias, E.A.; Huld, T.

    1992-01-01

    A laboratory experiment was carried out in order to study the nonlinear saturated stage of the cross-field electrostatic Kelvin-Helmholtz instability in a strongly magnetized plasma. The presence of large vortex-like structures in a background of wide-band turbulent fluctuations was demonstrated...... simulations. The importance of the large scale structures for the turbulent plasma transport across magnetic field lines was analyzed in detail....

  20. Population inversion in recombining hydrogen plasma

    International Nuclear Information System (INIS)

    Furukane, Utaro; Yokota, Toshiaki; Oda, Toshiatsu.

    1978-11-01

    The collisional-radiative model is applied to a recombining hydrogen plasma in order to investigate the plasma condition in which the population inversion between the energy levels of hydrogen can be generated. The population inversion is expected in a plasma where the three body recombination has a large contribution to the recombining processes and the effective recombination rate is beyond a certain value for a given electron density and temperature. Calculated results are presented in figures and tables. (author)

  1. Thermal stability of the tokamak plasma edge

    International Nuclear Information System (INIS)

    Stacey, W.M.

    1997-01-01

    The general linear, fluid, thermal instability theory for the plasma edge has been extended. An analysis of a two-dimensional fluid model of the plasma edge has identified the importance of many previously unappreciated phenomena associated with parallel and gyroviscous forces in the presence of large radial gradients, with large radial or parallel flows, with the temperature dependence of transport coefficients, and with the coupling of temperature, flow and density perturbations. The radiative condensation effect is generalized to include a further destabilizing condensation effect associated with radial heat conduction. Representative plasma edge neutral and impurity densities are found to be capable of driving thermal instabilities in the edge transport barrier and radiative mantle, respectively. (author)

  2. Localization of waves in a fluctuating plasma

    International Nuclear Information System (INIS)

    Escande, D.F.; Souillard, B.

    1984-01-01

    We present the first application of localization theory to plasma physics: Density fluctuations induce exponential localization of longitudinal and transverse electron plasma waves, i.e., the eigenmodes have an amplitude decreasing exponentially for large distances without any dissipative mechanism in the plasma. This introduces a new mechanism for converting a convective instability into an absolute one. Localization should be observable in clear-cut experiments

  3. ''Heavy light bullets'' in electron-positron plasma

    International Nuclear Information System (INIS)

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

    1995-03-01

    The nonlinear propagation of circularly polarized electromagnetic waves with relativistically strong amplitudes in an unmagnetized hot electron-positron plasma with a small fraction of ions is investigated. The possibility of finding localized solutions in such a plasma is explored. It is shown that these plasmas support the propagation of ''heavy light bullets''; nondiffracting and nondispersive electromagnetic (EM) pulses with large density bunching. (author). 24 refs, 12 figs

  4. Supersonic Heat Wave Propagation in Laser-Produced Underdense Plasma for Efficient X-Ray Generation

    International Nuclear Information System (INIS)

    Tanabe, M.; Nishimura, H.; Fujioka, S.; Nagai, K.; Iwamae, A.; Ohnishi, N.; Fournier, K.B.; Girard, F.; Primout, M.; Villette, B.; Tobin, M.; Mima, K.

    2008-01-01

    We have observed supersonic heat wave propagation in a low-density aerogel target (ρ ∼ 3.2 mg/cc) irradiated at the intensity of 4 x 10 14 W/cm 2 . The heat wave propagation was measured with a time-resolved x-ray imaging diagnostics, and the results were compared with simulations made with the two-dimensional radiation-hydrodynamic code, RAICHO. Propagation velocity of the ionization front gradually decreased as the wave propagates into the target. The reason of decrease is due to increase of laser absorption region as the front propagates and interplay of hydrodynamic motion and reflection of laser propagation. These features are well reported with the simulation

  5. Investigation of radiofrequency plasma sources for space travel

    International Nuclear Information System (INIS)

    Charles, C; Boswell, R W; Takahashi, K

    2012-01-01

    Optimization of radiofrequency (RF) plasma sources for the development of space thrusters differs from other applications such as plasma processing of materials since power efficiency, propellant usage, particle acceleration or heating become driving parameters. The development of two RF (13.56 MHz) plasma sources, the high-pressure (∼1 Torr) capacitively coupled ‘pocket rocket’ plasma micro-thruster and the low-pressure (∼1 mTorr) inductively coupled helicon double layer thruster (HDLT), is discussed within the context of mature and emerging electric propulsion devices. The density gradient in low-pressure expanding RF plasmas creates an electric field that accelerates positive ions out of the plasma. Generally, the total potential drop is similar to that of a wall sheath allowing the plasma electrons to neutralize the ion beam. A high-pressure expansion with no applied magnetic field can result in large dissociation rates and/or a collimated beam of ions of small area and a flowing heated neutral beam (‘pocket rocket’). A low-pressure expansion dominated by a magnetic field can result in the formation of electric double layers which produce a very directed neutralized beam of ions of large area (HDLT). (paper)

  6. Investigation of radiofrequency plasma sources for space travel

    Science.gov (United States)

    Charles, C.; Boswell, R. W.; Takahashi, K.

    2012-12-01

    Optimization of radiofrequency (RF) plasma sources for the development of space thrusters differs from other applications such as plasma processing of materials since power efficiency, propellant usage, particle acceleration or heating become driving parameters. The development of two RF (13.56 MHz) plasma sources, the high-pressure (˜1 Torr) capacitively coupled ‘pocket rocket’ plasma micro-thruster and the low-pressure (˜1 mTorr) inductively coupled helicon double layer thruster (HDLT), is discussed within the context of mature and emerging electric propulsion devices. The density gradient in low-pressure expanding RF plasmas creates an electric field that accelerates positive ions out of the plasma. Generally, the total potential drop is similar to that of a wall sheath allowing the plasma electrons to neutralize the ion beam. A high-pressure expansion with no applied magnetic field can result in large dissociation rates and/or a collimated beam of ions of small area and a flowing heated neutral beam (‘pocket rocket’). A low-pressure expansion dominated by a magnetic field can result in the formation of electric double layers which produce a very directed neutralized beam of ions of large area (HDLT).

  7. Parametric interaction of waves in the plasma with random large-scale inhomogeneities

    International Nuclear Information System (INIS)

    Abramovich, B.S.; Tamojkin, V.V.

    1980-01-01

    Parametric processes of the decay and fusion of three waves in a weakly turbulent plasma with random inhomogeneities, the size of which is too big as compared with wave-lengths are considered. Under the diffusive approximation applicability closed equations are obtained, which determine the behaviour of all the intensity moments of parametrically bound waves. It is shown that under the conditions when the characteristic length of the multiple scattering is considerably less than the nonlinear interaction, length the effective increment of average intensity increase and its moments at dissociation processes is too small as compared with the homogeneous plasma case. At fusion processes the same increment (decrement) determines the distance at which all intensity moments are in the saturation regime

  8. Experience with high heat flux components in large tokamaks

    International Nuclear Information System (INIS)

    Chappuis, P.; Dietz, K.J.; Ulrickson, M.

    1991-01-01

    The large present day tokamaks. i.e.JET, TFTR, JT-60, DIII-D and Tore Supra are machines capable of sustaining plasma currents of several million amperes. Pulse durations range from a few seconds up to a minute. These large machines have been in operation for several years and there exists wide experience with materials for plasma facing components. Bare and coated metals, bare and coated graphites and beryllium were used for walls, limiters and divertors. High heat flux components are mainly radiation cooled, but stationary cooling for long pulse duration is also employed. This paper summarizes the experience gained in the large machines with respect to material selection, component design, problem areas, and plasma performance. 2 tabs., 26 figs., 50 refs

  9. Radiation sources based on laser-plasma interactions

    NARCIS (Netherlands)

    Jaroszynski, D.A.; Bingham, R.; Brunetti, E.; Ersfeld, B.; Gallacher, J.G.; Geer, van der S.B.; Issac, R.; Jamison, S.P.; Jones, D.; Loos, de M.J.; Lyachev, A.; Pavlov, V.M.; Reitsma, A.J.W.; Saveliev, Y.M.; Vieux, G.; Wiggins, S.M.

    2006-01-01

    Plasma waves excited by intense laser beams can be harnessed to produce femtosecond duration bunches of electrons with relativistic energies. The very large electrostatic forces of plasma density wakes trailing behind an intense laser pulse provide field potentials capable of accelerating charged

  10. Suppression of large edge localized modes with edge resonant magnetic fields in high confinement DIII-D plasmas

    International Nuclear Information System (INIS)

    Thomas, P.R.; Becoulet, M.; Evans, T.E.; Osborne, T.H.; Groebner, R.J.; Jackson, G.L.; Haye, R.J. La; Schaffer, M.J.; West, W.P.; Moyer, R.A.; Rhodes, T.L.; Rudakov, D.L.; Watkins, J.G.; Boedo, J.A.; Doyle, E.J.; Wang, G.; Zeng, L.; Fenstermacher, M.E.; Groth, M.; Lasnier, C.J.; Finken, K.H.; Harris, J.H.; Pretty, D.G.; Masuzaki, S.; Ohyabu, N.; Reimerdes, H.; Wade, M.R.

    2005-01-01

    Large divertor heat pulses due to Type-I edge localized modes (ELMs) have been eliminated reproducibly in DIII-D with small dc currents driven in a simple magnetic perturbation coil. The current required to eliminate all but a few isolated Type-I ELMs, during a coil pulse, is less than 0.4% of plasma current. Modelling shows that the perturbation fields resonate with plasma flux surfaces across most of the pedestal region (0.9 ≤ N ≤ 1.0), when q95 = 3.7±0.2 creating small remnant magnetic islands surrounded by weakly stochastic field lines. The stored energy, N , H-mode quality factor and global energy confinement time are unaltered by the magnetic perturbation. At high collisionality (ν* ∼0.5-1), there is no obvious effect of the perturbation on the edge profiles and yet ELMs are suppressed, nearly completely, for up to 9τ E . At low collisionality (ν* <0.1), there is a density pump-out and complete ELM suppression, reminiscent of the DIIID QH- mode. Other differences, specifically in the resonance condition and the magnetic fluctuations, suggest that different mechanisms are at play in the different collisionality regimes. In addition to a description and interpretation of the DIIID data, the application of this method to ELM control on other machines, such as JET and ITER will be discussed. (author)

  11. Super-high magnetic fields in spatially inhomogeneous plasma

    International Nuclear Information System (INIS)

    Nastoyashchiy, Anatoly F.

    2012-01-01

    The new phenomenon of a spontaneous magnetic field in spatially inhomogeneous plasma is found. The criteria for instability are determined, and both the linear and nonlinear stages of the magnetic field growth are considered; it is shown that the magnetic field can reach a considerable magnitude, namely, its pressure can be comparable with the plasma pressure. Especially large magnetic fields can arise in hot plasma with a high electron density, for example, in laser-heated plasma. In steady-state plasma, the magnetic field can be self-sustaining. The considered magnetic fields may play an important role in thermal insulation of the plasma. (author)

  12. 21 CFR 862.2720 - Plasma oncometer for clinical use.

    Science.gov (United States)

    2010-04-01

    ... use is a device intended to measure plasma oncotic pressure, which is that portion of the total plasma osmotic pressure contributed by protein and other molecules too large to pass through a specified semipermeable membrane. Because variations in plasma oncotic pressure are indications of certain disorders...

  13. Non-modal analysis in plasmas

    International Nuclear Information System (INIS)

    Mahajan, S.M.; Rogava, A.D.; Berezhiani, V.

    1996-01-01

    The techniques of non-modal analysis are applied to investigate the time evolution of a variety of plasma flows with velocity shear. It is shown that large transient amplifications may result for appropriate initial perturbations. The role of this amplification in determining the nonlinear dynamics of these systems (when all the normal modes are stable) is discussed. Examples are taken from Laboratory, astrophysical and cosmic plasmas

  14. Trajectory effect on the properties of large area ZnO thin films deposited by atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    Juang, Jia-Yang; Chou, Tung-Sheng; Lin, Hsin-Tien; Chou, Yuan-Fang; Weng, Chih-Chiang

    2014-01-01

    Highlights: • We develop a cost-effective technique, atmosphere pressure plasma jet (APPJ), to deposit gallium-doped zinc oxide (GZO) films on large area glass substrates in atmosphere. • Scanning trajectory has a significant impact on the pattern of sheet resistance distribution. • The primary root cause of the nonuniformity is the annealing effect of the deposited films in air while the nozzle scans over the rest of the substrate. • Equivalent circuits models considering only the resistance increase due to air annealing cannot explain the unexpected rise of resistance in the center of the substrate for multiple-pass samples. • Measurements of residual stress, carrier concentration and Hall mobility reveal that the residual stress is another factor that results in nonuniform resistance distribution. - Abstract: Large area (117 mm × 185 mm) gallium-doped zinc oxide (GZO) films are prepared on glass substrates by atmospheric pressure plasma jet (APPJ) technique. The uniformity of material properties, in particular the electrical resistivity, of the deposited film is of great importance in reducing design complexity of the electron devices. We investigate the effects of scanning trajectory recipe (speed, pitch and number of passes) on structural and electrical properties of GZO thin films. We find that the trajectory has significant effects on the magnitude and uniformity of sheet resistance over the glass substrates. For single pass, the resistance appears higher at the starting part of spray, whereas, for cases of multiple passes, the highest resistance appears in the central part of the substrate. XRD, SEM, Hall measurement and residual stress are used to study the film properties and identify root causes of the nonuniform distribution of sheet resistance. We conclude that annealing time is the dominant root cause of the nonuniform resistance distribution, and other factors such as residual stress and structural characteristics may also have

  15. Multi-fluid Approach to High-frequency Waves in Plasmas. III. Nonlinear Regime and Plasma Heating

    Science.gov (United States)

    Martínez-Gómez, David; Soler, Roberto; Terradas, Jaume

    2018-03-01

    The multi-fluid modeling of high-frequency waves in partially ionized plasmas has shown that the behavior of magnetohydrodynamic waves in the linear regime is heavily influenced by the collisional interaction between the different species that form the plasma. Here, we go beyond linear theory and study large-amplitude waves in partially ionized plasmas using a nonlinear multi-fluid code. It is known that in fully ionized plasmas, nonlinear Alfvén waves generate density and pressure perturbations. Those nonlinear effects are more pronounced for standing oscillations than for propagating waves. By means of numerical simulations and analytical approximations, we examine how the collisional interaction between ions and neutrals affects the nonlinear evolution. The friction due to collisions dissipates a fraction of the wave energy, which is transformed into heat and consequently raises the temperature of the plasma. As an application, we investigate frictional heating in a plasma with physical conditions akin to those in a quiescent solar prominence.

  16. Plasma cleaning of ITER first mirrors

    Science.gov (United States)

    Moser, L.; Marot, L.; Steiner, R.; Reichle, R.; Leipold, F.; Vorpahl, C.; Le Guern, F.; Walach, U.; Alberti, S.; Furno, I.; Yan, R.; Peng, J.; Ben Yaala, M.; Meyer, E.

    2017-12-01

    Nuclear fusion is an extremely attractive option for future generations to compete with the strong increase in energy consumption. Proper control of the fusion plasma is mandatory to reach the ambitious objectives set while preserving the machine’s integrity, which requests a large number of plasma diagnostic systems. Due to the large neutron flux expected in the International Thermonuclear Experimental Reactor (ITER), regular windows or fibre optics are unusable and were replaced by so-called metallic first mirrors (FMs) embedded in the neutron shielding, forming an optical labyrinth. Materials eroded from the first wall reactor through physical or chemical sputtering will migrate and will be deposited onto mirrors. Mirrors subject to net deposition will suffer from reflectivity losses due to the deposition of impurities. Cleaning systems of metallic FMs are required in more than 20 optical diagnostic systems in ITER. Plasma cleaning using radio frequency (RF) generated plasmas is currently being considered the most promising in situ cleaning technique. An update of recent results obtained with this technique will be presented. These include the demonstration of cleaning of several deposit types (beryllium, tungsten and beryllium proxy, i.e. aluminium) at 13.56 or 60 MHz as well as large scale cleaning (mirror size: 200 × 300 mm2). Tests under a strong magnetic field up to 3.5 T in laboratory and first experiments of RF plasma cleaning in EAST tokamak will also be discussed. A specific focus will be given on repetitive cleaning experiments performed on several FM material candidates.

  17. On the origin of plasma density blobs

    Energy Technology Data Exchange (ETDEWEB)

    Krasheninnikov, S.I., E-mail: skrash@mae.ucsd.edu

    2016-12-01

    By keeping nonlinear Boltzmann factor in electron density dependence on electrostatic potential it is demonstrated that large plasma density blobs, often seen in experiment inside separatrix, can exist within the framework of drift wave dynamics. The estimates show that plasma density in a blob can be ∼3 times higher that average plasma density, but hardly exceeds this limit, which in a ball park is in agreement with experimental observations.

  18. X-ray lasing in colliding plasmas

    International Nuclear Information System (INIS)

    Clark, R.W.; Davis, J.; Velikovich, A.L.; Whitney, K.G.

    1997-01-01

    Conditions favorable for the achievement of population inversion and large gains in short-pulse laser-heated selenium have been reported on previously [K. G. Whitney et al., Phys. Rev. E 50, 468 (1994)]. However, the required density profiles to minimize refraction and amplification losses can be difficult to achieve in conventional laser heated blowoff plasmas. The feasibility of accelerating plasma with a laser, and letting it collide with a solid density wall plasma has been explored. The density of the resulting shocked plasma can be controlled and refraction can be reduced in this design. A radiation hydrodynamics model is used to simulate the collision of the laser produced selenium plasma with the wall plasma. The heating of the stagnated plasma with a short-pulse laser is then simulated, providing the hydrodynamic response of the selenium plasma and detailed configuration nonequilibrium atomic populations. From the results of these calculations, it appears feasible to create an x-ray lasing selenium plasma with gains in the J=0 endash 1 line at 182 Angstrom in excess of 100cm -1 . copyright 1997 American Institute of Physics

  19. Hydrogen Plasma Processing of Iron Ore

    Science.gov (United States)

    Sabat, Kali Charan; Murphy, Anthony B.

    2017-06-01

    Iron is currently produced by carbothermic reduction of oxide ores. This is a multiple-stage process that requires large-scale equipment and high capital investment, and produces large amounts of CO2. An alternative to carbothermic reduction is reduction using a hydrogen plasma, which comprises vibrationally excited molecular, atomic, and ionic states of hydrogen, all of which can reduce iron oxides, even at low temperatures. Besides the thermodynamic and kinetic advantages of a hydrogen plasma, the byproduct of the reaction is water, which does not pose any environmental problems. A review of the theory and practice of iron ore reduction using a hydrogen plasma is presented. The thermodynamic and kinetic aspects are considered, with molecular, atomic and ionic hydrogen considered separately. The importance of vibrationally excited hydrogen molecules in overcoming the activation energy barriers, and in transferring energy to the iron oxide, is emphasized. Both thermal and nonthermal plasmas are considered. The thermophysical properties of hydrogen and argon-hydrogen plasmas are discussed, and their influence on the constriction and flow in the of arc plasmas is considered. The published R&D on hydrogen plasma reduction of iron oxide is reviewed, with both the reduction of molten iron ore and in-flight reduction of iron ore particles being considered. Finally, the technical and economic feasibility of the process are discussed. It is shown that hydrogen plasma processing requires less energy than carbothermic reduction, mainly because pelletization, sintering, and cokemaking are not required. Moreover, the formation of the greenhouse gas CO2 as a byproduct is avoided. In-flight reduction has the potential for a throughput at least equivalent to the blast furnace process. It is concluded that hydrogen plasma reduction of iron ore is a potentially attractive alternative to standard methods.

  20. The application of the large particles method of numerical modeling of the process of carbonic nanostructures synthesis in plasma

    Science.gov (United States)

    Abramov, G. V.; Gavrilov, A. N.

    2018-03-01

    The article deals with the numerical solution of the mathematical model of the particles motion and interaction in multicomponent plasma by the example of electric arc synthesis of carbon nanostructures. The high order of the particles and the number of their interactions requires a significant input of machine resources and time for calculations. Application of the large particles method makes it possible to reduce the amount of computation and the requirements for hardware resources without affecting the accuracy of numerical calculations. The use of technology of GPGPU parallel computing using the Nvidia CUDA technology allows organizing all General purpose computation on the basis of the graphical processor graphics card. The comparative analysis of different approaches to parallelization of computations to speed up calculations with the choice of the algorithm in which to calculate the accuracy of the solution shared memory is used. Numerical study of the influence of particles density in the macro particle on the motion parameters and the total number of particle collisions in the plasma for different modes of synthesis has been carried out. The rational range of the coherence coefficient of particle in the macro particle is computed.

  1. Plasma acceleration by means of microwave radiation pressure

    International Nuclear Information System (INIS)

    Fukumura, Takashi; Takamoto, Teruo

    1977-01-01

    In the electric discharge of gas with microwaves, intense reflection waves occur simultaneously with the discharge, so the plasma ionized and formed by the microwaves is accelerated due to large radiation pressure. The basic experiment made, aiming at plasma gun, is described. In the gas electric discharge, the plasma flow velocity proportional to the reflected power is obtained. For 550 W microwave input power, the plasma velocity of 1 x 10 4 m/s was obtained. The accelerated plasma is bunched; its front as mass travels, recombines and disappears. (Mori, K.)

  2. Influence of large dust particles on plasma performance in the HL-2A tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z.H., E-mail: huangzh@swip.ac.cn; Yan, L.W.; Feng, Z.; Cheng, J.; Tomita, Y.; Liu, L.; Gao, J.M.; Zhong, W.L.; Jiang, M.; Yang, Q.W.; Xu, Y.; Duan, X.R.

    2015-08-15

    Visible dust particles generated from plasma-facing components (PFCs) and the impact of the dusts on plasma performance as a source of impurities have been studied in the HL-2A tokamak by means of a fast framing camera together with other diagnostics. The camera images display that during a steady state discharge the dusts are accelerated toriodally by the ion drag force and radially by the centrifugal force. The first experimental evidence shows that dust particles originating from the high field side (HFS) lead to a significant reduction of central electron temperature and divertor heat flux, a considerable rise of total radiated power and effective charge, and a slight growth of local electron density. The results reveal that the dusts at the HFS have much stronger effects on plasma performance than those at the low field side (LFS)

  3. Plasma surface interaction studies in Japan

    International Nuclear Information System (INIS)

    Hino, T.; Hirohata, Y.; Yamashina, T.

    1994-01-01

    In order to achieve a long burning time period in a fusion reactor, the interactions between the plasma facing materials and the fusion plasma have to be well controlled. Namely, the radiation loss due to impurities and deterioration of the energy confinement time due to fuel particle recyclings have to be suppressed, in addition to the requirement of heat removal based on a high heat flux component. Recently, in Japan, the plasma facing material/component has been very actively developed for ITER and Large Helical Device (LHD). In this review paper, we briefly introduce the following issues, (1) progress of plasma surface interactions in tokamaks and helical devices, (2) development of plasma facing materials, (3) divertor development, (4) boronization, (5) selective pumping of helium ash, (6) tritium retention, and (7) neutron damage of graphite plasma facing material. (author)

  4. Investigation of plasma potential and pulsed discharge characteristics in enhanced glow discharge plasma immersion ion implantation and deposition

    International Nuclear Information System (INIS)

    Li Liuhe; Lu Qiuyuan; Fu, Ricky K.Y.; Chu, Paul K.

    2009-01-01

    Enhanced glow discharge plasma immersion ion implantation and deposition (EGD-PII and D) does not require external plasma sources. In this technique, the plasma is produced by self-glow discharge when a high negative voltage is applied to the sample. The small-area, pointed-shape hollow anode and large area tabular cathode form an electron-focused electric field. Using a special electric field design, the electrons from either the plasma or target (secondary electrons) are focused to a special hollow anode. As a result of the special electron-focusing field, the self-glow discharge process can be enhanced to achieve effective ion implantation into the substrate. In this work, the plasma potential distribution is investigated in details and the possible pulse discharge mechanism is discussed. The unique characteristics of the pulsed plasma and plasma extinction are studied.

  5. Filamentary magnetohydrodynamic plasmas

    International Nuclear Information System (INIS)

    Kinney, R.; Tajima, T.; McWilliams, J.C.; Petviashvili, N.

    1994-01-01

    A filamentary construct of magnetohydrodynamical plasma dynamics based on the Elsaesser variables is developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to those based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected, the plasma vortex system is described by a Hamiltonian. A statistical treatment of a collection of discrete current-vorticity concentrations is given. Canonical and microcanonical statistical calculations show that both the vorticity and the current spectra are peaked at long wavelengths, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories, but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low-temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is presented as well, which is also Hamiltonian when the inductive force is neglected. A statistical calculation in the canonical ensemble and numerical simulations show that a nonzero large-scale magnetic field is statistically favored, and that the preferred shape of this field is a long, thin tube of flux. Possible applications to a variety of physical phenomena are suggested

  6. Helium ion distributions in a 4 kJ plasma focus device by 1 mm-thick large-size polycarbonate detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sohrabi, M., E-mail: dr_msohrabi@yahoo.com; Habibi, M.; Ramezani, V.

    2014-11-14

    Helium ion beam profile, angular and iso-ion beam distributions in 4 kJ Amirkabir plasma focus (APF) device were effectively observed by the unaided eyes and studied in single 1 mm-thick large-diameter (20 cm) polycarbonate track detectors (PCTD). The PCTDs were processed by 50 Hz–HV electrochemical etching using a large-size ECE chamber. The results show that helium ions produced in the APF device have a ring-shaped angular distribution peaked at an angle of ∼±60° with respect to the top of the anode. Some information on the helium ion energy and distributions is also provided. The method is highly effective for ion beam studies. - Highlights: • Helium iso-ion beam profile and angular distributions were studied in the 4 kJ APF device. • Large-area 1 mm-thick polycarbonate detectors were processed by 50 Hz-HV ECE. • Helium ion beam profile and distributions were observed by unaided eyes in a single detector. • Helium ion profile has ring-shaped distributions with energies lower at the ring location. • Helium iso-ion track density, diameter and energy distributions are estimated.

  7. A large stellarator based on modular coils

    International Nuclear Information System (INIS)

    Hamberger, S.M.; Sharp, L.E.; Petersen, L.F.

    1979-06-01

    Although stellarators offer some considerable advantages over tokamaks, difficulties arise in designing large devices due, for instance, to poor plasma access as well as to constructional electromechanical and maintenance problems associated with continous helical windings. This paper describes a design for a fairly large device (major radius 2.1m), based on a set of discrete coil modules arranged in a toroidal configuration to provide the required closed magnetic surfaces, having gaps for unobstructed access to the plasma for diagnostics, etc, and allowing for easy removal for maintenance

  8. Electron-beam generated plasmas for processing applications

    Science.gov (United States)

    Meger, Robert; Leonhardt, Darrin; Murphy, Donald; Walton, Scott; Blackwell, David; Fernsler, Richard; Lampe, Martin; Manheimer, Wallace

    2001-10-01

    NRL's Large Area Plasma Processing System (LAPPS) utilizes a 5-10 mA/cm^2, 2-4 kV, 1 cm x 30-60 cm cross section beam of electrons guided by a magnetic field to ionize a low density (10-100 mTorr) gas.[1] Beam ionization allows large area, high density, low temperature plasmas to be generated in an arbitrary gas mixture at a well defined location. Energy and composition of particle fluxes to surfaces on both sides of the plasma can be controlled by gas mixture, location, rf bias, and other factors. Experiments have been performed using both pulsed and cw beams. Extensive diagnostics (Langmuir probes, mass and ion energy analyzers, optical emissions, microwave interferometry, etc.) have been fielded to measure the plasma properties and neutral particle fluxes (ions, neutrals, free radicals) with and without rf bias on nearby surfaces both with the beam on and off. Uniform, cold (Te < 1eV), dense (ne 10^13 cm-3) plasmas in molecular and atomic gases and mixtures thereof have been produced in agreement with theoretical expectations. Initial tests of LAPPS application such as ashing, etching, sputtering, and diamond growth have been performed. Program status will be presented. [1]R.A. Meger, et al, Phys. of Plasmas 8(5), p. 2558 (2001)

  9. On the theory of magnetic field generation by relativistically strong laser radiation

    International Nuclear Information System (INIS)

    Berezhiani, V.I.; Shatashvili, N.L.; Mahajan, S.M.

    1996-07-01

    The authors consider the interaction of subpicosecond relativistically strong short laser pulses with an underdense cold unmagnetized electron plasma. It is shown that the strong plasma inhomogeneity caused by laser pulses results in the generation of a low frequency (quasistatic) magnetic field. Since the electron density distribution is determined completely by the pump wave intensity, the generated magnetic field is negligibly small for nonrelativistic laser pulses but increases rapidly in the ultrarelativistic case. Due to the possibility of electron cavitation (complete expulsion of electrons from the central region) for narrow and intense beams, the increase in the generated magnetic field slows down as the beam intensity is increased. The structure of the magnetic field closely resembles that of the field produced by a solenoid; the field is maximum and uniform in the cavitation region, then it falls, changes polarity and vanishes. In extremely dense plasmas, highly intense laser pulses in the self-channeling regime can generate magnetic fields ∼ 100 Mg and greater

  10. Optical spectroscopy using gas-phase femtosecond laser filamentation.

    Science.gov (United States)

    Odhner, Johanan; Levis, Robert

    2014-01-01

    Femtosecond laser filamentation occurs as a dynamic balance between the self-focusing and plasma defocusing of a laser pulse to produce ultrashort radiation as brief as a few optical cycles. This unique source has many properties that make it attractive as a nonlinear optical tool for spectroscopy, such as propagation at high intensities over extended distances, self-shortening, white-light generation, and the formation of an underdense plasma. The plasma channel that constitutes a single filament and whose position in space can be controlled by its input parameters can span meters-long distances, whereas multifilamentation of a laser beam can be sustained up to hundreds of meters in the atmosphere. In this review, we briefly summarize the current understanding and use of laser filaments for spectroscopic investigations of molecules. A theoretical framework of filamentation is presented, along with recent experimental evidence supporting the established understanding of filamentation. Investigations carried out on vibrational and rotational spectroscopy, filament-induced breakdown, fluorescence spectroscopy, and backward lasing are discussed.

  11. Theoretical investigations on plasma centrifuges

    International Nuclear Information System (INIS)

    Hong, S.H.

    1978-01-01

    The theoretical analysis of the steady-state dynamics of plasma centrifuges is dealt with to understand the physics of rotating plasmas and their feasibility for isotope separation. The centrifuge systems under consideration employ cylindrical gas discharge chambers with externally-applied axial magnetic fields. The cathode and anode are symmetric about the cylinder axis and arranged in such a way for each system, i.e., (1) two ring electrodes of different radii in the chamber end plates or (2) two ring electrodes embedded in the mantle of the cylinder. They produce converging and/or diverging current density field lines, which intersect the external magnetic field under a nonvanishing angle. The associated Lorentz forces set the plasma, which is produced through an electrical discharge, into rotation around the cylinder axis. Three boundary-value problems for the coupled partial differential equations of the centrifuge fields are formulated, respectively, on the basis of the magnetogasdynamic equations. The electric field, electrostatic potential, current density, induced magnetic field, and velocity distributions are discussed in terms of the Hartmann number, the Hall coefficient, and the magnetic Reynolds number. The plasma centrifuge analyses presented show that the speeds of plasma rotation up to the order of 10 4 m/sec are achievable at typical conditions. The associated centrifugal forces produce a significant spatial isotope separation, which is somewhat reduced in the viscous boundary layers at the centrifuge walls. The speeds of plasma rotation increase with increasing Hartmann number and Hall coefficient. For small Hall coefficient, the induced azimuthal magnetic field does not affect the plasma rotation. For large volumes of rotating isotope mixtures, a multidischarge centrifuge can be constructed by setting up a large number of centrifuge systems in series

  12. Diagnostics for the Plasma Liner Experiment

    International Nuclear Information System (INIS)

    Lynn, A. G.; Merritt, E.; Gilmore, M.; Hsu, S. C.; Witherspoon, F. D.; Cassibry, J. T.

    2010-01-01

    The goal of the Plasma Liner Experiment (PLX) is to explore and demonstrate the feasibility of forming imploding spherical ''plasma liners'' via merging high Mach number plasma jets to reach peak liner pressures of ∼0.1 Mbar using ∼1.5 MJ of initial stored energy. Such a system would provide HED plasmas for a variety of fundamental HEDLP, laboratory astrophysics, and materials science studies, as well as a platform for experimental validation of rad-hydro and rad-MHD simulations. It could also prove attractive as a potential standoff driver for magnetoinertial fusion. Predicted parameters from jet formation to liner stagnation cover a large range of plasma density and temperature, varying from n i ∼10 16 cm -3 , T e ≅T i ∼1 eV at the plasma gun mouth to n i >10 19 cm -3 , T e ≅T i ∼0.5 keV at stagnation. This presents a challenging problem for the plasma diagnostics suite which will be discussed.

  13. Turbulent transport in low-beta plasmas

    DEFF Research Database (Denmark)

    Nielsen, A.H.; Pécseli, H.L.; Juul Rasmussen, J.

    1996-01-01

    Low-frequency electrostatic fluctuations are studied experimentally in a low-P plasma, with particular attention to their importance for the anomalous plasma transport across magnetic field lines. The presence of large coherent structures in a turbulent background at the edge of the plasma column...... is demonstrated by a statistical analysis. The importance of these structures for the turbulent transport is investigated. The study is extended by a multichannel conditional analysis to illustrate detailed properties and parameter dependences of the turbulent transport. (C) 1996 American Institute of Physics....

  14. Plasma fractionation issues.

    Science.gov (United States)

    Farrugia, Albert; Evers, Theo; Falcou, Pierre-Francois; Burnouf, Thierry; Amorim, Luiz; Thomas, Sylvia

    2009-04-01

    Procurement and processing of human plasma for fractionation of therapeutic proteins or biological medicines used in clinical practice is a multi-billion dollar international trade. Together the private sector and public sector (non-profit) provide large amounts of safe and effective therapeutic plasma proteins needed worldwide. The principal therapeutic proteins produced by the dichotomous industry include gamma globulins or immunoglobulins (including pathogen-specific hyperimmune globulins, such as hepatitis B immune globulins) albumin, factor VIII and Factor IX concentrates. Viral inactivation, principally by solvent detergent and other processes, has proven highly effective in preventing transmission of enveloped viruses, viz. HBV, HIV, and HCV.

  15. Simulated performance of the optical Thomson scattering diagnostic designed for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Ross, J. S., E-mail: ross36@llnl.gov; Datte, P.; Divol, L.; Galbraith, J.; Hatch, B.; Landen, O.; Manuel, A. M.; Molander, W.; Moody, J. D.; Swadling, G. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Froula, D. H.; Katz, J. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Glenzer, S. H. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Kilkenny, J. [General Atomics, San Diego, California 92186 (United States); Montgomery, D. S. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Weaver, J. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-11-15

    An optical Thomson scattering diagnostic has been designed for the National Ignition Facility to characterize under-dense plasmas. We report on the design of the system and the expected performance for different target configurations. The diagnostic is designed to spatially and temporally resolve the Thomson scattered light from laser driven targets. The diagnostic will collect scattered light from a 50 × 50 × 200 μm volume. The optical design allows operation with different probe laser wavelengths. A deep-UV probe beam (λ{sub 0} = 210 nm) will be used to Thomson scatter from electron plasma densities of ∼5 × 10{sup 20} cm{sup −3} while a 3ω probe will be used for plasma densities of ∼1 × 10{sup 19} cm{sup −3}. The diagnostic package contains two spectrometers: the first to resolve Thomson scattering from ion acoustic wave fluctuations and the second to resolve scattering from electron plasma wave fluctuations. Expected signal levels relative to background will be presented for typical target configurations (hohlraums and a planar foil).

  16. Membrane-based, sedimentation-assisted plasma separator for point-of-care applications.

    Science.gov (United States)

    Liu, Changchun; Mauk, Michael; Gross, Robert; Bushman, Frederic D; Edelstein, Paul H; Collman, Ronald G; Bau, Haim H

    2013-11-05

    Often, high-sensitivity, point-of-care (POC) clinical tests, such as HIV viral load, require large volumes of plasma. Although centrifuges are ubiquitously used in clinical laboratories to separate plasma from whole blood, centrifugation is generally inappropriate for on-site testing. Suitable alternatives are not readily available to separate the relatively large volumes of plasma from milliliters of blood that may be needed to meet stringent limit-of-detection specifications for low-abundance target molecules. We report on a simple-to-use, low-cost, pump-free, membrane-based, sedimentation-assisted plasma separator capable of separating a relatively large volume of plasma from undiluted whole blood within minutes. This plasma separator consists of an asymmetric, porous, polysulfone membrane housed in a disposable chamber. The separation process takes advantage of both gravitational sedimentation of blood cells and size exclusion-based filtration. The plasma separator demonstrated a "blood in-plasma out" capability, consistently extracting 275 ± 33.5 μL of plasma from 1.8 mL of undiluted whole blood within less than 7 min. The device was used to separate plasma laden with HIV viruses from HIV virus-spiked whole blood with recovery efficiencies of 95.5% ± 3.5%, 88.0% ± 9.5%, and 81.5% ± 12.1% for viral loads of 35,000, 3500, and 350 copies/mL, respectively. The separation process is self-terminating to prevent excessive hemolysis. The HIV-laden plasma was then injected into our custom-made microfluidic chip for nucleic acid testing and was successfully subjected to reverse-transcriptase loop-mediated isothermal amplification (RT-LAMP), demonstrating that the plasma is sufficiently pure to support high-efficiency nucleic acid amplification.

  17. Complex plasmas scientific challenges and technological opportunities

    CERN Document Server

    Lopez, Jose; Becker, Kurt; Thomsen, Hauke

    2014-01-01

    This book provides the reader with an introduction to the physics of complex plasmas, a discussion of the specific scientific and technical challenges they present, and an overview of their potential technological applications. Complex plasmas differ from conventional high-temperature plasmas in several ways: they may contain additional species, including nanometer- to micrometer-sized particles, negative ions, molecules and radicals, and they may exhibit strong correlations or quantum effects. This book introduces the classical and quantum mechanical approaches used to describe and simulate complex plasmas. It also covers some key experimental techniques used in the analysis of these plasmas, including calorimetric probe methods, IR absorption techniques and X-ray absorption spectroscopy. The final part of the book reviews the emerging applications of microcavity and microchannel plasmas, the synthesis and assembly of nanomaterials through plasma electrochemistry, the large-scale generation of ozone using mi...

  18. Increased plasma fibronectin concentrations in obesity

    DEFF Research Database (Denmark)

    Andersen, T; Dejgaard, A; Astrup, A

    1987-01-01

    In 23 morbidly obese patients we investigated the influence of a large weight loss (30.6 kg, range 17.5-90.8) on the plasma fibronectin concentrations. Further, changes in plasma fibronectin were related to serum insulin levels and to liver biochemistry. Between the measurements patients had been...... treated with an intermittent very-low-calorie formula diet sufficient in respect to protein, minerals and vitamins. They were investigated in weight-stable states. Before weight reduction, 14 patients (61%, 95% confidence limits 39-80%) had elevated plasma fibronectin levels. Plasma fibronectin decreased...... (medians 1.22 and 0.59 mumol/l before and after weight loss, p less than 0.01) and was after weight loss within the normal range in 14 patients. The change in plasma fibronectin was unassociated with the magnitude of the weight loss as well as with the reduction of overweight. The resulting plasma...

  19. CAS course on Plasma Wake Acceleration

    CERN Multimedia

    CERN Accelerator School

    2015-01-01

    The CERN Accelerator School (CAS) recently organised a specialised course on Plasma Wake Acceleration, held at CERN, Geneva, Switzerland, from 23 to 29 November 2014.    Following a number of introductory lectures on laser and plasma physics, as well as an overview of conventional accelerators and their limitations, the course covered a large number of aspects of plasma wake acceleration schemes: the creation of plasma by high power lasers or particle beams, a description of the plasma creation process through simulations and the characteristics of the accelerated particle beams, including results of the latest achievements. Lectures on beam diagnostics, the applications of plasma accelerated beams, and topical seminars completed the programme.  The course was very successful, with 109 students of 26 nationalities attending; most participants coming from European counties, but also from the US, Israel, India, South Korea, Russia and Ukraine. Feedback from the participants was...

  20. Plasma-surface interactions

    International Nuclear Information System (INIS)

    Goeckner, M J; Nelson, C T; Sant, S P; Jindal, A K; Joseph, E A; Zhou, B S; Padron-Wells, G; Jarvis, B; Pierce, R; Overzet, L J

    2008-01-01

    Materials processing is at a crossroads. Currently a large fraction of industrially viable materials processing is via plasmas. Until recently it has been economical to just examine the influence the plasma properties on the desired surface processes and through this ultimately optimize manufacturing. For example, it is well known that the surface processes (etch or deposition), occur in the top few mono-layers of the surface. Thus, in film growth one requires that molecules from the gas-phase land and bond on the surface. However as processing has reached the nano-scale, development of viable processes has become more and more difficult. In part, this is because of all of the free parameters that exist in plasmas. To overcome this economic issue, tool vendors and semiconductor companies have turned to complex computational models of processing plasmas. For those models to work, one requires a through understanding of all of the gas-phase and surface-phase processes that are exhibited in plasmas. Unfortunately, these processes, particularly those at the surface, are not well understood. In this article we describe a viable model of the surface-phase based on cross sections for processes that occur. While originally developed of fluorocarbon systems, the model also appears to be applicable to hydrocarbon systems.

  1. Plasma-surface interactions

    Energy Technology Data Exchange (ETDEWEB)

    Goeckner, M J; Nelson, C T; Sant, S P; Jindal, A K; Joseph, E A; Zhou, B S; Padron-Wells, G; Jarvis, B; Pierce, R; Overzet, L J [Department of Electrical Engineering, University of Texas at Dallas (United States)], E-mail: goeckner@utdallas.edu

    2008-10-01

    Materials processing is at a crossroads. Currently a large fraction of industrially viable materials processing is via plasmas. Until recently it has been economical to just examine the influence the plasma properties on the desired surface processes and through this ultimately optimize manufacturing. For example, it is well known that the surface processes (etch or deposition), occur in the top few mono-layers of the surface. Thus, in film growth one requires that molecules from the gas-phase land and bond on the surface. However as processing has reached the nano-scale, development of viable processes has become more and more difficult. In part, this is because of all of the free parameters that exist in plasmas. To overcome this economic issue, tool vendors and semiconductor companies have turned to complex computational models of processing plasmas. For those models to work, one requires a through understanding of all of the gas-phase and surface-phase processes that are exhibited in plasmas. Unfortunately, these processes, particularly those at the surface, are not well understood. In this article we describe a viable model of the surface-phase based on cross sections for processes that occur. While originally developed of fluorocarbon systems, the model also appears to be applicable to hydrocarbon systems.

  2. Plasma-column instabilities in a reversed-field pinch without a shell

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, P.G.

    1988-01-01

    Plasma column instabilities in a Reversed Field Pinch (RFP) without a shell were investigated in the Colorado Reversatron RFP. The Reversatron RFP (aspect ration R/a = 50 cm/8cm) is a toroidal plasma containment device consisting of a vacuum chamber, a thick conducting shell, modular shells, magnetic field producing coils and diagnostics to characterize the plasma. RFP discharges were set up in the Reversatron in three different experimental configurations: with a thick conducting shell, with a modular shell and with no shell. In two of the configurations, a shell enclosed the plasma column to provide some plasma stability. A vertical magnetic field provided equilibrium in experiments without a shell. Data from discharges without a shell indicated that the plasma duration was greatly reduced and the plasma resistance increased compared to the discharges with a thick shell. Plasma position probes indicated large plasma centriod displacements corresponding to a n = 1 and a n = 3 kink coincident with the peak of the plasma current and the start of a discharge termination phase. The modular shell lengthened the discharge duration and lowered the plasma resistance to values intermediate between the plasma with a thick shell and the plasma with no shell. The modular shell suppressed the large plasma column displacements observed in the RFP plasma without a shell.

  3. Plasma-column instabilities in a reversed-field pinch without a shell

    International Nuclear Information System (INIS)

    Schmid, P.G.

    1988-01-01

    Plasma column instabilities in a Reversed Field Pinch (RFP) without a shell were investigated in the Colorado Reversatron RFP. The Reversatron RFP (aspect ration R/a = 50 cm/8cm) is a toroidal plasma containment device consisting of a vacuum chamber, a thick conducting shell, modular shells, magnetic field producing coils and diagnostics to characterize the plasma. RFP discharges were set up in the Reversatron in three different experimental configurations: with a thick conducting shell, with a modular shell and with no shell. In two of the configurations, a shell enclosed the plasma column to provide some plasma stability. A vertical magnetic field provided equilibrium in experiments without a shell. Data from discharges without a shell indicated that the plasma duration was greatly reduced and the plasma resistance increased compared to the discharges with a thick shell. Plasma position probes indicated large plasma centriod displacements corresponding to a n = 1 and a n = 3 kink coincident with the peak of the plasma current and the start of a discharge termination phase. The modular shell lengthened the discharge duration and lowered the plasma resistance to values intermediate between the plasma with a thick shell and the plasma with no shell. The modular shell suppressed the large plasma column displacements observed in the RFP plasma without a shell

  4. Interchange Instability and Transport in Matter-Antimatter Plasmas

    Science.gov (United States)

    Kendl, Alexander; Danler, Gregor; Wiesenberger, Matthias; Held, Markus

    2017-06-01

    Symmetric electron-positron plasmas in inhomogeneous magnetic fields are intrinsically subject to interchange instability and transport. Scaling relations for the propagation velocity of density perturbations relevant to transport in isothermal magnetically confined electron-positron plasmas are deduced, including damping effects when Debye lengths are large compared to Larmor radii. The relations are verified by nonlinear full-F gyrofluid computations. Results are analyzed with respect to planned magnetically confined electron-positron plasma experiments. The model is generalized to other matter-antimatter plasmas. Magnetized electron-positron-proton-antiproton plasmas are susceptible to interchange-driven local matter-antimatter separation, which can impede sustained laboratory magnetic confinement.

  5. Interchange Instability and Transport in Matter-Antimatter Plasmas.

    Science.gov (United States)

    Kendl, Alexander; Danler, Gregor; Wiesenberger, Matthias; Held, Markus

    2017-06-09

    Symmetric electron-positron plasmas in inhomogeneous magnetic fields are intrinsically subject to interchange instability and transport. Scaling relations for the propagation velocity of density perturbations relevant to transport in isothermal magnetically confined electron-positron plasmas are deduced, including damping effects when Debye lengths are large compared to Larmor radii. The relations are verified by nonlinear full-F gyrofluid computations. Results are analyzed with respect to planned magnetically confined electron-positron plasma experiments. The model is generalized to other matter-antimatter plasmas. Magnetized electron-positron-proton-antiproton plasmas are susceptible to interchange-driven local matter-antimatter separation, which can impede sustained laboratory magnetic confinement.

  6. Plasma transport near material boundaries

    International Nuclear Information System (INIS)

    Singer, C.E.

    1985-06-01

    The fluid theory of two-dimensional (2-d) plasma transport in axisymmetric devices is reviewed. The forces which produce flow across the magnetic field in a collisional plasma are described. These flows may lead to up-down asymmetries in the poloidal rotation and radial fluxes. Emphasis is placed on understanding the conditions under which the known 2-d plasma fluid equations provide a valid description of these processes. Attempts to extend the fluid treatment to less collisional, turbulent plasmas are discussed. A reduction to the 1-d fluid equations used in many computer simulations is possible when sources or boundary conditions provide a large enough radial scale length. The complete 1-d fluid equations are given in the text, and 2-d fluid equations are given in the Appendix

  7. Engaging high school students as plasma science outreach ambassadors

    Science.gov (United States)

    Wendt, Amy; Boffard, John

    2017-10-01

    Exposure to plasma science among future scientists and engineers is haphazard. In the U.S., plasma science is rare (or absent) in mainstream high school and introductory college physics curricula. As a result, talented students may be drawn to other careers simply due to a lack of awareness of the stimulating science and wide array of fulfilling career opportunities involving plasmas. In the interest of enabling informed decisions about career options, we have initiated an outreach collaboration with the Madison West High School Rocket Club. Rocket Club members regularly exhibit their activities at public venues, including large-scale expos that draw large audiences of all ages. Building on their historical emphasis on small scale rockets with chemical motors, we worked with the group to add a new feature to their exhibit that highlights plasma-based spacecraft propulsion for interplanetary probes. This new exhibit includes a model satellite with a working (low power) plasma thruster. The participating high school students led the development process, to be described, and enthusiastically learned to articulate concepts related to plasma thruster operation and to compare the relative advantages of chemical vs. plasma/electrical propulsion systems for different scenarios. Supported by NSF Grant PHY-1617602.

  8. Relativistic plasma dispersion functions

    International Nuclear Information System (INIS)

    Robinson, P.A.

    1986-01-01

    The known properties of plasma dispersion functions (PDF's) for waves in weakly relativistic, magnetized, thermal plasmas are reviewed and a large number of new results are presented. The PDF's required for the description of waves with small wave number perpendicular to the magnetic field (Dnestrovskii and Shkarofsky functions) are considered in detail; these functions also arise in certain quantum electrodynamical calculations involving strongly magnetized plasmas. Series, asymptotic series, recursion relations, integral forms, derivatives, differential equations, and approximations for these functions are discussed as are their analytic properties and connections with standard transcendental functions. In addition a more general class of PDF's relevant to waves of arbitrary perpendicular wave number is introduced and a range of properties of these functions are derived

  9. Conceptual design of a permanent ring magnet based helicon plasma source module intended to be used in a large size fusion grade ion source

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Arun; Sudhir, Dass; Bandyopadhyay, M., E-mail: mainak@iter-india.org; Chakraborty, A.

    2016-02-15

    A conceptual design of a permanent magnet based single driver helicon plasma source module along with its design approach is described in this paper. The module unit is intended to be used in a large size ion source. The conceptual design of the helicon source module has been carried out using a computer code, HELIC. The magnetic field topology for the ring magnet is simulated with another code, BFieldM and the magnetic field values obtained from the calculation are further used as input in HELIC calculation for the conceptual design. The module is conceptualized based on a cylindrical glass vessel to produce plasma of diameter ∼50 mm, height ∼50 mm. The inner diameter of the permanent ring magnets is also of the same dimension with thickness ∼10 mm each, placed slightly above the backplate to maintain the required magnetic field. The simulated results show that for hydrogen gas, expected plasma density can be achieved as high as ∼10{sup 12}–10{sup 13} cm{sup −3} in the proposed helicon source configuration using 1 kW 13.56 MHz RF generator. An experimental setup to characterize a Helicon source module unit, consisting of a cylindrical glass (plasma) chamber along with the vacuum system, RF power supplies, probes and data acquisition system is being installed.

  10. Simple microwave plasma source at atmospheric pressure

    International Nuclear Information System (INIS)

    Kim, Jeong H.; Hong, Yong C.; Kim, Hyoung S.; Uhm, Han S.

    2003-01-01

    We have developed a thermal plasma source operating without electrodes. One electrodeless torch is the microwave plasma-torch, which can produce plasmas in large quantities. We can generate plasma at an atmospheric pressure by marking use of the same magnetrons used as commercial microwave ovens. Most of the magnetrons are operated at the frequency of 2.45 GHz; the magnetron power microwave is about 1kW. Electromagnetic waves from the magnetrons propagate through a shorted waveguide. Plasma was generated under a resonant condition, by an auxiliary ignition system. The plasma is stabilized by vortex stabilization. Also, a high-power and high-efficiency microwave plasma-torch has been operated in air by combining two microwave plasma sources with 1kW, 2.45 GHz. They are arranged in series to generate a high-power plasma flame. The second torch adds all its power to the plasma flame of the first torch. Basically, electromagnetic waves in the waveguide were studied by a High Frequency Structure Simulator (HFSS) code and preliminary experiments were conducted

  11. Nuclear Fusion Research Understanding Plasma-Surface Interactions

    CERN Document Server

    Clark, Robert E.H

    2005-01-01

    It became clear in the early days of fusion research that the effects of the containment vessel (erosion of "impurities") degrade the overall fusion plasma performance. Progress in controlled nuclear fusion research over the last decade has led to magnetically confined plasmas that, in turn, are sufficiently powerful to damage the vessel structures over its lifetime. This book reviews current understanding and concepts to deal with this remaining critical design issue for fusion reactors. It reviews both progress and open questions, largely in terms of available and sought-after plasma-surface interaction data and atomic/molecular data related to these "plasma edge" issues.

  12. Laser plasma interactions in hohlraums

    Energy Technology Data Exchange (ETDEWEB)

    Kruer, W.L.

    1994-10-05

    Lasers plasma instabilities are an important constraint in x-ray driven inertial confinement fusion. In hohlraums irradiated with 1.06 {mu}m light on the Shiva laser, plasma instabilities were extremely deleterious, driving the program to the use of shorter wavelength light. Excellent coupling has been achieved in hohlraums driven with 0.35 {mu}m light on the Nova laser. Considerable attention is being given to the scaling of this excellent coupling to the larger hohlraums for an ignition target. Various instability control mechanisms such as large plasma wave damping and laser beam incoherence are discussed, as well as scaling experiments to check the instability levels.

  13. Plasma resonance in anisotropic layered high-Tc superconductors

    DEFF Research Database (Denmark)

    Sakai, Shigeki; Pedersen, Niels Falsig

    1999-01-01

    The plasma resonance is described theoretically by the inductive coupling model for a large stacked Josephson-junction system such as the intrinsic Josephson-junction array in anisotropic high- T-c superconductors. Eigenmodes of the plasma oscillation are analytically described and a numerical...

  14. Tokamak nonmaxwellian plasma dynamics in thermonuclear regime

    International Nuclear Information System (INIS)

    Cotsaftis, M.

    1987-01-01

    To reach ignition in a Tokamak plasma, large additional power P aux has to be injected in the device on top of the Joule heating P OH =VI r , V the plasma loop voltage, I r the resistive port of plasma current. Typi-cally JH ∼ 1 KeV, whereas ignition would requi- re IG ∼ 7-10 KeV. To gain this factor 7, one at least should inject additional power P aux ∼ 7P OH , supposing that nothing, especially the heat transport, is modified. This is by far not the case, with the so-called energy lifetime degradation, largely observed in oil experiments (but less dramatic with divertors), where energy lifetime tau E behaves like P tot -b with b∼1/2. In large machines where ignition temperature is the target to be imperiously reached, this implies to inject a very large power, typically P aux ∼ 50 to 100 MW, depending on size and parameters and on actual transport. So it is of importance with such figures, or even larger ones owing to uncertain ties, to optimize at best injected power by increasing its efficiency, both with respect to possible transport laws, and to physical phenomena governing heat flow in the system from the sources. This leads to the concept of scenarios, as time sequences of power input, where physical properties of the plasma system are used to build up ion temperature so that ignition is reached with minimum P tot = P OH + P aux and with fixed Q = Q o > 1. Elements for this study are given. The method is outlined. The resulting system of equations describing the evolution of a thermonuclear plasma is given

  15. Treatment failure of nelfinavir-containing triple therapy can largely be explained by low nelfinavir plasma concentrations

    NARCIS (Netherlands)

    Burger, David M.; Hugen, Patricia W. H.; Aarnoutse, Rob E.; Hoetelmans, Richard M. W.; Jambroes, Marielle; Nieuwkerk, Pythia T.; Schreij, Gerrit; Schneider, Margriet M. E.; van der Ende, Marchina E.; Lange, Joep M. A.

    2003-01-01

    The relationship between plasma concentrations of nelfinavir and virologic treatment failure was investigated to determine the minimum effective concentration of nelfinavir. Plasma samples were prospectively collected from treatment-naive patients who began taking nelfinavir, 1,250 mg BID + two

  16. On improved understanding of plasma-chemical processes in complex low-temperature plasmas

    Science.gov (United States)

    Röpcke, Jürgen; Loffhagen, Detlef; von Wahl, Eric; Nave, Andy S. C.; Hamann, Stephan; van Helden, Jean-Piere H.; Lang, Norbert; Kersten, Holger

    2018-05-01

    Over the last years, chemical sensing using optical emission spectroscopy (OES) in the visible spectral range has been combined with methods of mid infrared laser absorption spectroscopy (MIR-LAS) in the molecular fingerprint region from 3 to 20 μm, which contains strong rotational-vibrational absorption bands of a large variety of gaseous species. This optical approach established powerful in situ diagnostic tools to study plasma-chemical processes of complex low-temperature plasmas. The methods of MIR-LAS enable to detect stable and transient molecular species in ground and excited states and to measure the concentrations and temperatures of reactive species in plasmas. Since kinetic processes are inherent to discharges ignited in molecular gases, high time resolution on sub-second timescales is frequently desired for fundamental studies as well as for process monitoring in applied research and industry. In addition to high sensitivity and good temporal resolution, the capacity for broad spectral coverage enabling multicomponent detection is further expanding the use of OES and MIR-LAS techniques. Based on selected examples, this paper reports on recent achievements in the understanding of complex low-temperature plasmas. Recently, a link with chemical modeling of the plasma has been provided, which is the ultimate objective for a better understanding of the chemical and reaction kinetic processes occurring in the plasma. Contribution to the Topical Issue "Fundamentals of Complex Plasmas", edited by Jürgen Meichsner, Michael Bonitz, Holger Fehske, Alexander Piel.

  17. Cross-tail velocity component in the plasma sheet fast flows

    Directory of Open Access Journals (Sweden)

    N. P. Dmitrieva

    2008-06-01

    Full Text Available The flux transfer in the magnetotail plasma sheet is mainly provided by the tail-aligned fast plasma flows (Bursty Bulk Flows – BBFs. In this paper we study the events with a large cross-tail velocity component, including their occurrence and relationship to the standard BBFs. We found out that a significant part of large Vy events are a subgroup connected with the BBFs propagation. The maximal deviation of the velocity vector from the X direction (about 40–50 degrees, on average is observed near the BBFs' leading front in the sheath, where the fast flow interacts with surrounding plasma. The average variation of the velocity direction in the vicinity of the BBF resembles a plasma vortex. Our results support the model, in which the BBF represents a polarized, bubble-like flux tube, propagating through the plasma sheet.

  18. Plasma Edge Control in Tore Supra

    International Nuclear Information System (INIS)

    Evans, T.E.; Mioduszewski, P.K.; Foster, C.; Haste, G.; Horton, L.; Grosman, A.; Ghendrih, P.; Chatelier, M.; Capes, H.; Michelis, C. De; Fall, T.; Geraud, A.; Grisolia, C.; Guilhem, D.; Hutter, T.

    1990-01-01

    TORE SUPRA is a large superconducting tokamak designed for sustaining long inductive pulses (t∼ 30 s). In particular, all the first wall components have been designed for steady-state heat and particle exhaust, particle injection, and additional heating. In addition to these technological assets, a strict control of the plasma-wall interactions is required. This has been done at low power: experiments with ohmic heating have been mainly devoted to the pump limiter, ergodic divertor and pellet injection experiments. Some specific problems arising in large tokamaks are encountered; the pump limiter and the ergodic divertor yield the expected effects on the plasma edge. The effects on the bulk are discussed

  19. An adiabatic focuser

    International Nuclear Information System (INIS)

    Chen, P.; Oide, K.; Sessler, A.M.; Yu, S.S.

    1989-08-01

    Theoretical analysis is made of an intense relativistic electron beam, such as would be available from a linear collider, moving through a plasma of increasing density, but density always less than that of the beam (underdense). In this situation, the plasma electrons are expelled from the beam channel and the electrons are subject to an ever-increasing focusing force provided by the channel ions. Analysis is made on the beam radiation energy loss in the classical, the transition, and the quantum regimes. It is shown that the focuser is insensitive to the beam energy spread behaviors in the nonclassical regimes, the radiation limit on lenses (the Oide limit) can be exceeded. The sensitivity of the system to the topic mismatch and the nonlinearity is also analyzed. Examples are given with SLC-type and TLC-type parameters. 9 refs., 1 tab

  20. Plasma heating by adiabatic compression

    International Nuclear Information System (INIS)

    Ellis, R.A. Jr.

    1972-01-01

    These two lectures will cover the following three topics: (i) The application of adiabatic compression to toroidal devices is reviewed. The special case of adiabatic compression in tokamaks is considered in more detail, including a discussion of the equilibrium, scaling laws, and heating effects. (ii) The ATC (Adiabatic Toroidal Compressor) device which was completed in May 1972, is described in detail. Compression of a tokamak plasma across a static toroidal field is studied in this device. The device is designed to produce a pre-compression plasma with a major radius of 17 cm, toroidal field of 20 kG, and current of 90 kA. The compression leads to a plasma with major radius of 38 cm and minor radius of 10 cm. Scaling laws imply a density increase of a factor 6, temperature increase of a factor 3, and current increase of a factor 2.4. An additional feature of ATC is that it is a large tokamak which operates without a copper shell. (iii) Data which show that the expected MHD behavior is largely observed is presented and discussed. (U.S.)