Carlos A. de Azevedo

Discrete Alfvén waves in solar loop prominences

It is shown that a discrete Alfvén wave can explain the natural oscillations of solar loop prominences by considering the existence of a current flow. Discrete Alfvén waves are a new class of Alfvén waves which is described by the inclusion of the finite ion cyclotron frequency (ω/ωcl≠0) and/or the equilibrium plasma current. In this paper we consider only the effect of the current since in solar prominences (ω/ωcl≈0). We have modeled the solar prominences as a cylindrical plasma, surrounded by vacuum (corona), with L ≫ a where L and a are the plasma column, length, and radius, respectively. We have calculated the spectrum of the discrete Alfvén waves as function of the magnitude and shape of the plasma current.

Temperature relaxation in collisional nonequilibrium plasmas

The relaxation process of a space uniform plasma composed of cold electrons and one species of hot ions is studied numerically. The process is investigated on the basis of the nonlinear kinetic Fokker–Planck equation. Special attention has been paid to the deviation from the classical picture.