NONLOCAL HYBRID-KINETIC STABILITY ANALYSIS OF THE MIRROR-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 cylindrical ion equilibrium fi0(Hl - ω iPθ, υz), where ωi = const is the angular velocity of mean rotation. The radial eigenvalue equation for the potential amplitude φ̂(r) is solved exactly for the particular choice of fi0 corresponding to a sharp-boundary (rectangular) density profile. The resulting dispersion relation for the complex eigenfrequency ω 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 (ωi = ω̂ i+) with axis encircling orbits than for slow rotational equilibria (ωi = ω̂i-). Stability behavior is investigated for the entire range of r̂Li/ Rp allowed by the equiibrium model (0 < 2r̂Li/ Rp < 1). © 1979 American Institute of Physics.