Role of anisotropy of the initial particle distribution in the acceleration in collapsing solar-flare traps

We consider the behavior of charged particles with an anisotropic initial velocity distribution in a magnetic trap with approaching mirrors in connection with the problem of particle acceleration in solar flares. We show that, irrespective of the charge sign, the efficiency of confinement and acceleration increases with increasing anisotropy factor of the initial distribution alpha = (Tperpendicular to/Tparallel to)(1/2). For a positive electric potential of the trap plasma relative to the mirrors, the emerging additional effect of ion expulsion form the trap increases with alpha(i). The derived estimate of the electric potential suggests an amplification of the initial perturbation and the development of instability. (C) 2003 MAIK Nauka/Interperiodica.