"Absolute Universal Instability" Is Not Universal

Abstract

The roots of an improved analytic eigenvalue equation for the absolute universal or collisionless drift instability in a sheared magnetic field are found numerically and compared with the eigenvalues obtained from a numerical solution of the exact differential equation. The startling result is that both techniques predict stability, no matter how weak the shear or how large the transverse wave number, in contradiction to all previous work. Stability is due primarily to the stabilizing influence of the nonresonant electrons.