Corona plasma instabilities in heavy ion fusion targets

Several plasma instabilities driven by a heavy ion beam impinging on a target are considered. Potential instabilities include longitudinal electrostatic (two-stream) instabilities and transverse electromagnetic (filamentation or Weibel) instabilities. Since the ion beam may be accompanied by electrons, both electron beam and ion beam instabilities are considered. The electrostatic beam instabilities saturate by formation of an electron tail. In this paper the filamentation instability driven by this electron energy anisotropy is shown to be benign; this confirms the results of earlier studies in which the slower ion filamentation instability was shown to be unimportant. The beam ion, target electron instability is found to be suppressed by the gradient in the target density. Moreover, even if it were to grow, it would saturate at a benign level. In conclusion, no significant problem due to corona plasma instabilities in heavy ion fusion applications has been found.