Analytic Scaling Laws Related to Beam and Return-Current Stability in Particle-Beam-Driven ICF Target Regions

摘要

Using a simplified model of a homogeneous, unbounded, time-independent background plasma and an unbounded, charge- and current-neutralized ion beam, the linear stability of beam- and return-current-driven modes has been analyzed in parameter regimes appropriate to both light- and heavy-ion-driven inertial-confinement-fusion target regions. The purpose of this report is to derive analytic scaling laws which reveal those regions in parameter space and those modes of interaction, both electrostatic and electromagnetic, which could present problems. It is found that instabilities are typically not a concern until the density of background ions drops below about 0.01% of solid density. Growth rates are presented, and the stabilizing influences of beam overlap and plasma-density gradients are discussed quantitatively and qualitatively. (ERA citation 08:030925)