Nonlocal Hybrid-kinetic Stability Analysis of the Drift-cone Instability

A hybrid-kinetic model (Vlasov ions and cold-fluid electrons) is used to develop a fully nonlocal theory of the mirror-drift-cone instability. The stability analysis assumes electrostatic flute perturbations about a 0 cylindrical ion equilibrium f (HwiPe, v ), where w = const.=angular velocity of mean rotation. The radial eigenvalue equation for the potential amplitude $(r) is solved 0 exactly for the particular choice of f. corresponding to a sharp-boundary (rectangular) density profile. The resulting dispersion relation for the complex eigenfrequency w is investigated numerically for a broad range of system parameters including the important influence of large ion orbits and ion thermal effects. It is found that the instability growth rate is typically more severe for fast rotational equilibria (w.=i.) with axis encircling orbits 1 2. than for slow rotational equilibria (w.=G.). Stability 2. 1 behavior is investigated for the entire range of jLi P allowed by the equilibrium model (0<2t Li/R < 1). Also at Naval Surface Weapons Center, Silver Spring, Md. 20910 V