Instability effects caused by conducting end walls in a plasma on open field lines

Two new mechanisms on how a conducting wall can affect plasma stability are presented. The instability mechanisms are of interest to the general problem of plasma stability on open field lines and they are particularly relevant to the concept of the gas dynamic trap (GDT). It is shown that the stabilizing effect of ion momentum flow through expanders with favorable field line curvature onto an insulating wall disappears in the presence of a conducting wall. With an electron temperature gradient present, a rapidly growing (compared with MHD growth rates) instability arises with end conducting plates present, while this instability is completely absent with insulating end plates. (author). 19 refs, 3 figs