Strong Langmuir turbulence in Kappa distributed plasmas

Abstract

Superthermal electrons are often observed in space and astrophysics and can be appropriate modeled by the family of Kappa distribution functions. Taking the nonlinear wave-wave, wave-particle interactions and the effect of superthermal electrons into account, the strong Langmuir turbulence is investigated in kinetic regime. The modified Zakharov equations are obtained for the case of no damping or driving terms. On the basis of these equations, dynamics of collapse have been studied by the means of the general virial theorem, and the collapse thresholds which are strong modified by superthermal index j e are given.

Magneto-modulational instability in Kappa distributed plasmas with self-generated magnetic fields

“…Linearizing Eqs. (41), (42), and (43) with respect to the perturbation, it yields @ 2 @s 2 À a j r 2…”

“…(41), (42), and (43) are a generalization of the Zakharov equations by taking into account the selfgenerated magnetic field and the effect of the superthermal particles. Equation (41) is the driven ion-acoustic equation.…”

“…From kinetic theory, the modified dispersion function was obtained by Summers and Throne, 30 32 Since then, extensive wave studies using Kappa models were carried out. [33][34][35][36][37][38][39][40][41][42] It was shown that the presence of a high-energy tail component in a Kappa distribution considerably changes the rate of resonant energy transfer between particles and plasma waves, so that the dispersion relations, the conditions for Landau damping and plasma instabilities may be substantially different for Lorentzian from Maxwellian plasmas. The characteristics of the low frequency acoustic waves are different in the two distributions, for instance, the dispersion of acoustic waves is strongly modified by the spectral index j.…”

Stimulated Raman scattering in nonextensive statistics

“…For q 1, it gives nonextensive q-distribution functions only when the parameter q → 1 Maxwellian distribution is recovered. This nonextensive qdistribution function has been employed successfully in a wide range of systems characterized by nonextensivity for studying the dispersion property in plasmas [16][17][18][19][20][21][22][23][24][25][26][27][28].…”

Modulational instability of a Langmuir wave in plasmas with energetic tails of superthermal electrons

“…In our paper, we study the dispersion properties of much hotter plasma that is typical to the laboratory beam-plasma experiments, and we focus on the validity of various widely used approximations. Investigations of modulational instability in relativistic plasmas with the Maxwell-Jüttner distribution [16,17] or in the kappa-distributed plasmas with nonrelativistic superthermal tails [18,19] are also of interest in last years. In contrast to these papers, we consider the modulational instability of a Langmuir wave in an unmagnetized plasma with the relativistic power-law momentum distribution of plasma electrons.…”