On drift instabilities in magnetized target fusion devices

Abstract

Some versions of magnetized target fusion (MTF) devices will be using a high beta plasma, with local beta exceeding 1. Drift instabilities in such a plasma are electromagnetic and are quite different from the analogous instabilities in a low beta plasma. In a collisionless limit they have been analyzed by El Nadi and Rosenbluth [Phys. Fluids 16, 2036 (1973)] who have shown that the cross-field transport coefficients in such a plasma may exceed a Bohm value. On the other hand, high-density plasma in MTF systems is usually strongly collisional in the sense that the drift frequency for the most dangerous large-scale perturbations is smaller than the ion–ion collision frequency, and the particle mean free path is shorter than the parallel wavelength. This regime is studied in the present paper. It is shown that transport coefficients in the MTF plasma are usually smaller than the Bohm diffusion coefficient.