Nonlinear interaction between a resonance-mode (k∥=0) wave and energetic plasma particles (original) (raw)
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Theory of resonant and stimulated excitation of magnetic-moment fields in wave-plasma interactions
Physical Review E, 1993
Theories of two nonlinear processes of magnetic-moment-field generation in wave-plasma interactions are presented here. These processes are (i) resonant excitation of a moment field (REMF) and (ii) stimulated excitation of a moment field (SEMF). This field generally evolves from the wave-induced bending of the direction of motion of constituents of a plasma. It is important when it has a large value, and when it grows to large values with time, because then it eftectively controls the wave-induced features of a plasma. Specifically, this growing field gives rise to a strong anisotropy of the plasma in the region of the common direction of propagation of the involved waves, which leads to enhancement of synchrotron and bremmsstrahlung losses, and filamentation. The REMF is a static field of resonance when the beat frequency of two waves equals the frequency of another wave, all propagating in the same direction. The three possible cases of such interaction, involving waves of only high frequencies, with unmagnetized plasmas, for which the REMF formula has been calculated, are (a) two transverse waves and one longitudinal wave, (b) two longitudinal waves and one transverse wave, and (c) three transverse waves. The SEMF is a parametrically stimulated nonoscillating, exponentially temporally growing field of stimulated Brillouin scattering from a signal Alfven wave, a pump Alfven wave, and a signal sound wave. A second simultaneous resonance occurs only for weak nonlinearity and finite electrical conductivity, when the signal Alfven wave frequency equals the parametric frequency shift. This, being a slow process of transfer of plasma kinetic energy to field energy, can be a strong candidate for evolution of the field in plasma configurations of outer space.
Nonlinear excitations in a relativistic plasma with non-Maxwellian electrons
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Parametric Cyclotron Resonance in Space Plasmas
Journal of Geophysical Research, 1993
The parametric interaction of waves with particle cyclotron motion has been studied. A wave with a compressional magnetic field component modifies the cyclotron motion of the particles, which enables them to resonate with other waves which have perpendicular electric fields. Resonance occurs when the frequency difference of the two wave modes (compressional and perpendicular) matches the cyclotron frequency. This so-called parametric cyclotron resonance mechanism can provide a means to exchange energy between particles and low-frequency waves. We discuss the specific example of energy exchange between an Alfv6n wave and ion Larmor motion. Harada and G. K. Crawford for their useful comments.
The European Physical Journal D, 2014
In this communication, the combined effect of relativistic and ponderomotive nonlinearities on the generation of electron plasma wave by cross focusing of two intense laser beams at difference frequency (Δω ≈ ω1 − ω2 ≈ ωp) and acceleration of electrons in laser produced homogeneous plasma is analysed in the non-paraxial region. On account of these nonlinearities, two laser beams affect the dynamics of each other, and cross focusing takes place. It is observed that the focusing of laser beams becomes fast in the non-paraxial region by expanding the eikonal and other relevant quantities up to the fourth power of the radial distance (r). Modified coupled equations for the beam width of laser beams, electric field amplitude of the excited electron plasma wave and energy gain at beat wave frequency are derived, when relativistic and ponderomotive nonlinearities are operative. These coupled equations are solved analytically and numerically to study the cross focusing of two intense laser beams in plasma and its effect on the variation of the amplitude of the electron plasma wave and energy gain. It is observed from the results that both nonlinearities significantly affect the amplitude of plasma wave excitation and particle acceleration in the non-paraxial region in comparison to the paraxial region.
Nonlinear-wave propagation in a proton-electron plasma coupled with a strong radiation field
Il Nuovo Cimento B, 1979
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Nonlinear propagation of Electron-acoustic waves in a nonextensive electron-positron-ion plasma
Journal of the Korean Physical Society, 2015
Electron-acoustic shock waves (EASWs) in an unmagnetized electron-positron-ion plasma system (consisting of a cold mobile viscous electron fluid, hot electrons and positrons following the q-nonextensive distribution, and immobile positive ions) are studied analytically. The Burgers equation is derived by using the well-known reductive perturbation method. The basic features (viz. polarity, amplitude, width, phase speed, etc.) of EASWs are briefly addressed. The basic features of EASWs are found to be significantly modified by the effects of nonextensivity of the hot electrons and positrons, the relative number density and temperature ratios, and the kinematic viscosity of the cold electrons. The present investigation can be useful in understanding the fundamental characteristics of EASWs in various space plasmas.