WAVE SCATTERING AND RELATIVISTIC ELECTRON BEAM ACCELERATION AND HEATING INDUCED BY NONLINEAR LANDAU DAMPING
Project/Area Number  08680508 
Research Category 
GrantinAid for Scientific Research (C)

Allocation Type  Singleyear Grants 
Section  一般 
Research Field 
プラズマ理工学

Research Institution  EHIME UNIVERSITY 
Principal Investigator 
SUGAYA Reiji EHIME UNIVERSITY,FACULTY OF SCIENCE, DEPARTMENT OF PHYSICS PROFESSOR, 理学部, 教授 (30036397)

CoInvestigator(Kenkyūbuntansha) 
MAEHARA Tsunehiro EHIME UNIVERSITY,FACULTY OF SCIENCE,DEPARTMENT OF PHYSICS ASSISTANT, 理学部, 助手 (40274302)

Project Period (FY) 
1996 – 1997

Project Status 
Completed(Fiscal Year 1997)

Budget Amount *help 
¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1997 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1996 : ¥1,300,000 (Direct Cost : ¥1,300,000)

Keywords  nonlinear Landau damping / cascade process / Compton scattering / relativistic electron bean / particle acceleration / perpendicular ion acceleration / Potential formation / anomalous transport / ビト波 / 電磁波 / 静電波 / 異常輸送現象 
Research Abstract 
(1) Acceleration and heating of a relativistic electron beam by cascading nonlinear Landau damping involving three or four (ten) intense electromagnetic waves in a plasma were studied theoretically based on kinetic wave equations derived from relativistic VlasovMaxwell equations. Three or four (ten) electromagnetic waves exite successively two or three (nine) nonresonant beatwavedriven relativistic electron plasma waves with a phase velocity near the speed of light[nu_p=c(1gamma_P^<2>)^<1/2>, gamma_p=omega/omega_<pe>]. Three (nine) beatwaves interact nonlinearly with the electron beam and accelerate it to a highly relativistic energy gamma_pm_ec^2 more effectively than by the usual nonlinear Landau damping of two electromagnetic waves. (2) We used a testparticle to investigate numerically relativistic electron acceleration by the beatwave excited by nonlinear Landau damping of two electromagnetic wave in plasma. It suggests that some electrons can be accelerated to the energy of
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2gamma_pm_ec^2, as has been predicted theoretically. (3) The momentumspace diffusion equation and the kinetic wave equation for resonant wavewave scattering of electromagnetic and electrostatic waves in relativistic magnetized plasma were derived from the relativistic VlasovMaxwell equations. The pdependent diffusion coefficient and the nonlinear wavewave coupling coefficient are given in terns of thirdorder tensors which are amenable to analysis. The transport equations describing energy and momentum transfer between waves and particles were obtained by momentum space integration of the momentumspace diffusion equation, and are expressed in terms of nonlinear wavewave coupling coefficient in the kinetic wave equation. The conservation laws for total energy and momentum densities of waves and particles are verified from the kinetic wave equation and the transport equations. These equations are very usuful for the theoretical analysis of transport phenomena or the acceleration and generation of highenergy or relativistic particles caused by quasilinear and resonant wavewave scattering. (4) Acceleration and heating of a relativistic electron beam induced by nonlinear Landau damping of lowerhybrid waves in a magnetized plasma ware investigated theoretically based on kinetic wave equations and transport equations derived from relativistic VlasovMaxwell equations. It was proved that a relativistic electron beam can be efficiently by two lowerhybrid waves. (5) Acceleration and heating of a highenergy or relativistic electron beam due to Compton scattering induced by nonlinear Landau damping of extraordinary waves propagating almost perpendicularly to the magnetic field were investgated theoretically by numerical analysis of the nonlinear waveparticle coupling coefficients. It is verified that the efficient acceleration occurs when the phase velocity of the beatwave exceeds the velocity of the electron beam and the frequency of the extraordinary wave is larger than the righthand cutoff frequency. The same results were derived from the singleparticle theory. (6) In an electron beamplasma system, we observed experimentally that the electron heating occurs via Landau damping by electrostatic waves excited by nonlinear Landau damping and that the hollow radial profile of the electron density and the radial and axial electric field are produced. This is induced by the acceleration of plasma electrons due to quasilinear Landau damping of electrostatic waves and is thought to be phenomena of the anomalous transport which is observed in a fusion plasma. (7) Particle transport along and across a magnetic field and an electric field across a magnetic field which are induced by almost perpendicularly propagating electrostatic waves in a magnetized plasma have been investigated theoretically based on quasilinear transport equations derived from ValsovMaxwell equations. This theory is capable of explaining the fluctuationinduced anomalous transport occuring in sawtooth crashes or edge plasmas in tokamaks and the perpendicular ion acceleration in tokamaks and space plasmas as well as the anomalous electron transport observed in an electron beamplasma system. Less

Report
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Research Products
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