The quantum effect on the Weibel instability in an unmagnetized plasma is presented. Our analysis shows that the quantum effect tends to stabilize the Weibel instability in the hydrodynamic regime, whereas it produces a new oscillatory instability in the kinetic regime. A novel effect called the quantum damping, which is associated with the Landau damping, is disclosed. The new quantum Weibel instability may be responsible for the generation of non-stationary magnetic fields in compact astrophysical objects as well as in the forthcoming intense laser–solid density plasma interaction experiments.

Large-amplitude electron plasma oscillations in a one-dimensional, cold electron plasma are investigated for a spatially varying, immobile ion density. The Eulerian variables are transformed to Lagrangian variables. The problem is then treated as an effective one-dimensional particle in a potential. Two examples of spatially varying ion densities that lead to analytic functions for the electron position, velocity and electric field are found by Gauss' law to have zero electron density, an unphysical result. A generic solution that includes the two examples is shown to have a spatially homogeneous ion density. A nonlinear ordinary differential equation is the condition for the appropriate form of the electron density and is solved by Lie group symmetries. A more general form of a solution is presented that possesses a spatially varying ion density, but when the necessary conditions are specified it has either zero electron density or secular terms in the electron density.

Plasma was first obtained successfully on the EAST Tokamak in the autumn of 2006. This was an ohmically heated plasma with rf-assisted pre-ionization for plasma startup. Many diagnostics systems were set up to satisfy the requirement for the description of basic plasma performance. Three hard X-ray detectors have been installed to monitor the runaway electrons with a tangential view into the plasma on the equatorial plane. A BGO (Bi4Ge3O12) scintillator installed in the forward direction was used to detect the hard X-ray emission in the energy range 0.5–7 MeV while two CdTe detectors in the backward and forward directions are used to detect the hard X-ray emission in the energy range 0.3-1.2 MeV. Phenomena observed with these detectors in different discharge conditions are presented here.

A two-dimensional double simple wave solution is given for both weakly and highly magnetized non-relativistic plasmas moving across the magnetic field. The dependence of the density and the magnetic field on the two independent phases, namely, components of the fluid velocity, is derived. It is shown that initial spatial distributions must satisfy a definite equation whose solution determines a special category for initial conditions. The time of blow up for any fixed value of the pair phase is found. A large general class of solutions for initial distributions is obtained. For any chosen initial distribution, the physical plane of flow at any instant of time splits into two regions, one forbidden and the other permitted. These regions are obtained numerically at a typical time for a special initial distribution. For this double wave solution, differential equations for streamlines and fluid trajectories are derived. Only for the simplest cases can the corresponding curves be completely integrated and these are given in this paper. The results are qualitatively similar to the one-dimensional case derived by Stenflo and Shukla.

In this paper the focusing/defocusing of (i) a single Gaussian electromagnetic beam and (ii) a number of coaxial Gaussian electromagnetic beams, propagating in the extraordinary mode along the Earth's magnetic field in the ionosphere has been investigated in the paraxial approximation. The growth of a sinusoidal instability on account of self-focusing has also been studied. The nonlinearity in the dielectric function, responsible for the focusing/defocusing arises from the redistribution of the electron density, caused by the non-uniform distribution of the electron temperature. The electron temperature is determined by the energy balance for electrons/ions taking into account the Ohmic heating, the collisions and the radiation from the sun. The wave frequency has been assumed to be greater than the plasma frequency. The electron cyclotron frequency due to the Earth's magnetic field in the ionosphere is much larger than the electron collision frequency. This is specifically true for a height of 150 km. Numerical results have been presented for a range of parameters and a discussion of the same has been presented.

We present the results of three-dimensional self-consistent multi-fluid simulations of magnetic reconnection in a dusty plasma. We ballistically relax a Harris-like current sheet into a fluid pseudo-equilibrium. We then perturb the current sheet with typical inflow and outflow velocities associated with classical models of reconnection. We find a 20% decrease in magnetic energy for the case of a locally enhanced resistivity. For a parameter-dependent resistivity we find a 26% decrease in magnetic energy in the current sheet. We find dust-neutral relative flow velocities that are a factor of two greater than the dust Alfvén velocity. We then explore the implications of these flows on aerodynamic drag heating of the dust particles.

The conventional Jeans model is modified by the addition of electric charging. The standard procedure of kinetic treatment results in a dispersion relation which describes both the Jeans instability and Langmuir oscillations, with the analog of Landau damping. Coulomb interactions tend to stabilize the Jeans instability diminishing the growth rate whereas the gravitational field tends to destabilize Langmuir oscillations. Collisions between particles are taken into account.

Solitary waves are investigated in a magnetized electron–positron plasma consisting of equal hot and cool components of each species. The hot components have a Boltzmann distribution and the cool components are described by the fluid equations. A modified Korteweg–de Vries–Zakharov–Kuznetsov equation governing the oblique propagation of nonlinear electrostatic modes is derived using the reductive-perturbation technique. Soliton amplitudes are studied as a function of plasma parameters such as the particle number densities and the temperatures. Such results may be of relevance to the magnetosphere of pulsars.

We consider the possibility of self-similar solutions describing the implosion of hollow cylindrical annuli driven by an azimuthal magnetic field, in essence a self-similar imploding liner z-pinch. We construct such solutions for gasdynamics, for ideal ‘β=0’ plasma and for ideal magnetogasdynamics (MGD). In the latter two cases some quantities are singular at the annular boundaries. Numerical solutions of the full ideal MGD initial value problem indicate that the self-similar solutions are not attractive for arbitrary initial conditions, possibly as a result of flux-freezing.

Small-amplitude electrostatic solitary waves are investigated in an unmagnetized dusty plasma with hot variable charge non-thermal dust grains. These nonlinear localized structures are small-amplitude self-consistent solutions of the Vlasov equation in which the dust response is non-Maxwellian. Localized solitary structures that may possibly occur are discussed and the dependence of their characteristics on physical parameters is traced. Our investigation may be taken as a prerequisite for the understanding of the electrostatic solitary waves that may occur in space dusty plasmas.

Large amplitude plasma oscillations are studied in a cold electron plasma. Using Lagrangian variables, a new class of exact analytical solutions is found. It turns out that the electric field amplitude is limited either by wave breaking or by the condition that the electron density always has to stay positive. The range of possible amplitudes is determined analytically.