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The magnetic reconnection (MR) configuration was constructed by using two approaching laser-produced plasma bubbles. The characteristics of the MR current sheet were investigated. The driving energy of the laser pulse affects the type of the current sheet. The experiments present “Y-type” and “X-type” current sheets for larger and smaller driving energy, respectively. The energetic electrons were found to be well-collimated. The formation and ejection of plasmoid from the “Y-type” current sheet was expected to enhance the number of accelerated electrons.

Nonlinear coupling of the motion in the three spatial degrees of freedom of a cold fluid electron-positron plasma is investigated. Exact, solutions describing expanding flows with oscillations are obtained. It is found that the energy in the irrotational flow component is in general transferred to the rotational components, but not in the reversed direction. Furthermore, since the density evolution need not be related to all the three flow components, oscillations in one or two of the flow fields can be purely electromagnetic and are not accompanied by density oscillations. Original Publication:Wenmin Zhang, M Y Yu, A R Karimov and Lennart Stenflo, Energy coupling among the degrees of freedom in an electron-positron plasma, 2010, JOURNAL OF PLASMA PHYSICS, (76), 329-335.http://dx.doi.org/10.1017/S0022377809990523Copyright: Cambridge University Presshttp://www.cambridge.org/uk/Postprint available at: Linköping University Electronic Presshttp://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57398

The effect of density and size of dust grains on the electron energy distribution function (EEDF) in low-temperature complex plasmas is studied. It is found that the EEDF depends strongly on the dust density and size. The behavior of the electron temperature can differ significantly from that of a pristine plasma. For low-pressure argon glow discharge, the Druyvesteyn-like EEDF often found in pristine plasmas can become nearly Maxwellian if the dust density and/or sizes are large. One can thus control the plasma parameters by the dust grains.

Ordered structures as well as chaotic motion of the magnetic electron drift vortex (MEDV) mode in a unmagnetized nonuniform plasma are discussed. In the collisionless limit, the nonlinear MEDV waves can self-organize into dipolar vortices or vortex chains. The latter exist in the regime where dipolar vortices are forbidden. When dissipation is included, the governing equations for the MEDV mode can be cast into the form of the Lorenz equations, so that chaotic solutions can exist.

The radially symmetric self-similar expansion of a dusty plasma is investigated in cylindrical and spherical geometries. The electrons and ions are assumed to be in Boltzmann equilibria, while the dynamics of the dust particles is governed by the fluid equations. The effects of finite dust pressure as well as dust-charge variation are included.

Mathematically exact solutions describing propagating waves are constructed for a cold magnetized plasma bounded by a rigid cylindrical dielectric. Possible particle sources and sinks due to chemical reactions are allowed. It is found that the volume waves can be either amplified or damped because of their density dependence; while the surface waves are unaffected by the sources and sinks.

Wave mixing resulting from the resonance of electromagnetic waves with ion acoustic waves modified by dust charge fluctuations is investigated. The corresponding nonlinear susceptibilities are derived and applied to the study of phase conjugation by four-wave mixing. It is shown that dust charge fluctuations can lead to a filling-up of the resonance-induced splitting of the phase-conjugate reflectivity, making the latter a useful tool for the diagnostics of dusty plasmas.

Ion-acoustic surface waves in a highly collisional plasma are considered. It is shown that the dispersion and damping of these waves differ considerably from those for a weakly collisional plasma.

The convection mode in a collisional plasma is investigated, with the inclusion of electromagnetic effects. It is shown that a dissipative instability can occur. The relationship to several well-known modes as well as applications to typical low-temperature plasmas are discussed.

Neutron production from a thin deuterium-tritium (D-T) foil irradiated by two intense femtosecond laser pulses from opposite sides with zero phase difference is studied analytically and numerically. For the interaction of a laser pulse of amplitude a = 7, focal area 100 mu m(2) and areal density 4.4 x 10(18) cm(-2) with a D-T plasma foil, about 1.17 x 10(21) neutron s(-1) can be obtained, much more than from other methods. The profiles of the ion and electron densities are also calculated.

This paper presents a formulation of the nonlinear coupling of the electron whistler mode radiation with generalized (including higher frequencies than allowed by the magnetohydrodynamic model) magnetosonic fluctuations. A coupled set of nonlinear equations describing the interaction of the whistler wave electric field with the density and the field-aligned magnetic fluctuations of the generalized magnetosonic waves is derived and the problem of modula-tional instability is discussed. Our results have relevance to the non-thermal magnetic field fluctuations which lead to supplementary plasma heating.

We investigate the problem of spatial depletion of propagating lower-hybrid waves in an inhomogeneous plasma. In particular, we consider the nonlinear evolution of a lower-hybrid pump which is coupled to a daughter lower-hybrid decay wave excited by low-frequency density perturbations. Our results show that pump depletion occurs when three-dimensional effects are included. This phenomenon competes with the filamentation of the pump caused by self- interaction. Implications to lower-hybrid heating experiments are discussed.

We consider the propagation of a large-amplitude lower-hybrid wave. Modulational instabilities arising from its interaction with low-frequency electrostatic perturbations are investigated. The growth lengths of the convective instabilities are obtained and compared with previous results for adiabatic perturbations.

This paper presents a derivation of the nonlinear equations governing the space–time evolution of magnetic electron drift waves in an inhomogeneous magnetoplasma. The equilibrium electron pressure gradient is maintained by the gradient of an external magnetic field. An oscillatory instability is shown to arise. The existence of magnetic electron drift vortices is discussed and the limitation on the vortex speed due to the external magnetic field is pointed out.

It is shown that drift dissipative instabilities can occur in the frequency regime Ωi ≪ ω ≪ Ωe. These instabilities are associated with the electron-acoustic and lower-hybrid waves.

Nonlinear excitation of electrostatic and magnetostatic zero-frequency modes by finite-amplitude lower-hybrid waves is considered. It is found that modulational instabilities can give rise to enhanced plasma vortices. Dispersion relations, as well as analytical expressions for the growth rates, are obtained. The enhanced vortices may cause anomalous cross-field diffusion which can affect plasma confinement in tokamak devices when lower-hybrid waves are used for plasma heating or current drive. We found that magnetic fluctuations associated with the parametrically driven magnetostatic mode are of particular importance in tokamak plasmas.

It is shown that a modified electron-acoustic wave exists in a plasma with distinct hot and cold electron components. The frequency of this wave depends strongly on the cold electron number density. Solitons associated with the modified electron-acoustic waves are also discussed.

The scattering of an ordinary electromagnetic wave into a circularly polarized wave by electron-acoustic oscillations is considered.In this paper, we consider a parametric instability involving electron-acoustic waves which does not have a counterpart in a hot electron plasma, namely the scattering of an ordinary electromagnetic wave into a circularly polarized wave by electron-acoustic waves.

The propagation of nonlinear high-frequency TM antisymmetric surface waves on a thin un magnetized plasma slab bounded by vacuum has been studied. It is found that smooth surface wave solitons due to the modulation of finite-amplitude electron surface waves by slow ion-acoustic motion exist. When the high-frequency wave propagation is modified by a purely electronic slow motion, the governing equation is a derivative nonlinear Schröd inger equation with a cusped-soliton solution.

We consider nonlinear surface waves on a cold plasma half-space. It is found that for a certain region of the wavenumber spectrum, supersonic envelope surface wave solitons exist.

The problem concerning the appropriate form for the nonlinear frequency shift arising from slow density modulations of electrostatic surface waves in a semi-infinite unmagnetized plasma is reconsidered. The spatial dependence of the wave amplitude normal to the surface is kept general in order to allow for possible nonlinear attenuation behaviour of the surface waves. It is found that if the frequency shift is expressed as a function of the density and its gradient then the result is identical with that of Zhelyazkov (1987b), who assumed a linear exponential attenuation behaviour.

Linear and nonlinear mechanisms for generating convective cells with finite but small parallel (to the external magnetic field B0) wavelength are presented. The problems of mode-coupling as well as quasi-steady nonlinear mode structures are analytically studied. Possible applications in space plasmas are discussed.

It is shown that convective cells can be excited by large-amplitude propagating upper-hybrid waves in a plasma. Using the two-fluid model, we obtain a coupled set of differential equations. A nonlinear dispersion relation for the modulational instability is then derived. This relation is investigated for two parameter regimes and expressions for the growth rates are obtained analytically. The limiting case of a dipole pump field is also considered. The relevance of our work in laser-produced, as well as magnetically confined, plasmas is discussed.

An analysis of profile modifications in laser-plasma interactions in the presence of an externally applied constant d.c. magnetic field is presented. By considering the case of circular polarization for the incident laser light, the flow velocities and the shelf densities in the incident as well as the evanescent regions are calculated. For left-handed circular polarization, the flow velocity in the incident region is enhanced by the magnetic field, whereas the opposite occurs for right-handed circular polarization. On the other hand, the shelf density in the evanescent region is always supercritical for the former case, and for the latter case it can be either subcriticai or supercritical, depending on the strengths of the incident laser intensity as well as the external magnetic field.

The existence of finite-amplitude Langnwir solitary waves in a two-electron-temperature plastia is investigated. A now type of soliton, in which the density depression and the electric field amplitude scale in the same manner, and which travels at the effective sound speed, has been found.

The effect of weak collisions on ion-acoustic wave instabifities in a plasma with large ratios of electron to ion temperatures is investigated. The critical current for instability is shown to be signfficantly reduced by collisions. At the critical current the instability first occurs at non-zero values of kλe. As kλe increases the collisional effects become less and less significant.

The propagation and stability of ion and electron drift waves in a non-homogeneous plasma containing impurity ions is considered. It is shown that the presence of impurities in the plasma may significantly affect the stability criteria of these low frequency waves. Furthermore, perturbations at frequencies which are multiples of the impurity ion cyclotron frequency may also be unstable when ½K2u R21 > 1.

The influence of collisions on the universal instability in a fully ionized in- homogeneous plasma is investigated by means of a simplified Fokker-Planck kinetic equation. For the Fokker-Planck model yields results qualitatively similar to the Bhatnagar-Gross-Krook model, but the two models give different collisional effects in the case where b ≥ 1. Further it is shown that collisions in general enhance the temperature gradient instability in a plasma when b ≪ 1 and reduce it when b ≥ 1.