Excitation of Electrostatic Ion Cyclotron Oscillations

Abstract

It has been observed that an electron current drawn to an electrode immersed in a magnetized plasma can excite oscillation near the ion cyclotron frequency. A theory is derived which predicts such oscillation due to a destabilizing influence of the sheath voltage drop at the electrode on the plasma column. Experimental evidence is presented which shows that the present theory is more compatible with observations than an earlier explanation in terms of resonantly drifting electrons.