TEMPORAL EVOLUTION OF THE LOWER HYBRID CAVITIES IN THE IONOSPHERE PLASMA DUE TO TURBULENT DIFFUSION

The problem of evolution and disappearance of the lower hybrid cavities that are observed in the plasma of the Earth’s ionosphere is solved. It is assumed that the destruction of the cavity is caused by turbulent diffusion of plasma, which arises due to the drift instability of radially inhomogeneous plasma. The initial plasma density distribution on the radius in the cavity is considered to be the inverse Gaussian distribution. A solution of the diffusion equation is obtained, which at any time determines the radial dependence of the plasma density in the cavity. In the asymptotic limit t →∞ the plasma density in the cavity becomes equal to the density of the surrounding plasma.

Sensitiveness of light absorption for self-focusing at laser–plasma interaction with weakly relativistic and ponderomotive regime

In the present paper, we have examined the sensitiveness of light absorption for self-focusing of Gaussian laser beam in plasma. By introducing dielectric function of plasma under ponderomotive and weakly relativistic regime, we have established the differential equation for beam-width parameter by using parabolic equation approach under Wentzel-Kramers-Brillouin and paraxial approximations and solved it numerically. In order to incorporate the sensitiveness of light absorption for self-focusing, behavior of normalized beam-width parameter; plasma density distribution with dimensionless distance of propagation is presented graphically and discussed. Numerical analysis shows that light absorption plays a vital role in self-focusing of laser beam in plasma under weakly relativistic and ponderomotive regime and gives reasonably interesting results.

On the galactic distributions of radio pulsars and plasma density

A brief review of distance measurement methods for some astronomical sources is presented. Galactic plasma density distribution as related to the distribution of radio pulsars is discussed and a method for constructing relations between dispersion measure and distance for Galactic radio pulsars in small solid angle intervals is described. Dispersion measure - distance relations for radio pulsars based on this approach in the Galactic longitude and latitude intervals of ?l=0??2? and ?b = 0?? 2? are displayed and comparisons are made with the predictions of the two commonly used models.