ELECTROMAGNETIC INSTABILITIES ATTRIBUTED TO A CROSS-FIELD ION DRIFT

Instabilities due to a cross-field ion flow are reexamined by including the electromagnetic response of the ions, which has been ignored in existing discussions. It is found that this effect can lead to significant enhancement of the growth rates. Among the new results, we find a purely growing, electromagnetic unstable mode with a wave vector k parallel to the ambient magnetic field. The plasma configuration under consideration is similar to that used in the discussion of the well-known modified-two-stream instability. This instability has a growth rate faster than the ion cyclotron frequency, and is not susceptible to high-plasma stabilization. © 1990 The American Physical Society.