On The Nonlinear Localized Structures In Non-Magnetized Kappa Distributed Plasmas

Plasma, which is called the fourth state of matter, has been applied widely in thermal nuclear fusion science, space exploration, military research and development, as well as manufacturing production, et al. As a typical electromagnetic medium, one of the significant characters of the plasmas is that plasmas can support a large number of wave modes. The properties of plasma waves as well as the nonlinear effects are the key research areas and the foundation for technical applying in the plasma physics. Various observations of charged particles in the space environment frequently showed that they featured superthermal components, characterized by power-law non-Maxwelllian distributions, and can be well parameterized by the Kappa or the generalized Lorentzian functions. The superthermal particles in the Kappa distributed plasmas modified the wave-wave, wave-particle nonlinear interaction significantly, so it is can be expected that in many aspect the theoretical results given by the Kappa distribution will different from the Maxwellian’s. Focusing on the nonlinear effects of the plasma waves, in this paper, we study the Langmuir turbulence structures, self-generated small-scale magnetic turbulence structures, acoustic-type solitons, as well as the double layer and Rouge wave in the strong Langmuir turbulence regimes, both from plasma kinetic theory and fluid dynamics, respectively. Our results show that the physical pictures of nonlinear evolutions of electromagnetic modes and electrostatic modes, and will provide the theoretical supports for the interpretation of space and laboratory observations.Firstly, we give a brief introduction about the basic content of plasma physics, such as plasma concepts, fundamental research methods, plasma waves, as well as Langmuir turbulence structures, self-generated small-scale magnetic turbulence structures and plasma soltions; the superthermal electrons and Kappa distribution, and it’s applications in the plasma physics, as well as its physical mechanism. In the second chapter, the wave dispersions and Landau dampings or instabilities in the Kappa distributed plasma are introduced, and the modifications of the superthermal index k on it are discussed.Secondly, based on the plasma kinetic theory, the nonlinear effects associated with the wave-wave, wave-particle interactions in the Kappa distributed plasmas are studied carefully, and then the modified Zakharov equations which describe the Langmuir turbulence, as well as the generalized Zakharov equations that are the nonlinear evolution equation for low-frequency self-generated magnetic field induced by the interactions of transverse plasmons between plasmas are derived. Based on the modified Zakharov equation, the modulational instabilities of the Langmuir wave and ion-acoustic wave are studied, and the Viral theorem is applied to study the collapse dynamics of Langmuir turbulence. In the one-dimensional case, the Zakharov equations degenerate to nonlinear SchroÇ'dinger equation, and then the Langmuir solitons are studied. The results show that the superthermal index k has significant impacts on the Langmuir turbulence characters. On the other hand, based on the the generalized Zakharov equations, the magneto-modulational instabilities and the self-similar collapse solutions are studied, and the character scales and strength are given. The results are compared with the Maxwellian case, and the effects of the superthermal index k on the low-frequency self-generated magnetic field are discussed.Finally, after the brief introduction for theory of plasma fluid soliton structures, the acoustic-type solitons in the two-electron-temperature plasmas with superthemal electron are studied; then in the strong Langmuir turbulence regimes, based on the nonlinear Schrodinger equation, the solutions of double layer structures and Rouge waves are given.