Suppression of precessional drift wave by external inhomogeneous high frequency field

The effect of a high frequency field on a flute like mode is investigated. The experiment has been made on a plasma produced by means of the molecular ion injection into a simple mirror. The flute like mode arises from the plasma rotation due to a static electric field, which is controlable by means of potential applied to the end plates. The strength of the high frequency field increases with radius and the frequency is near to the ion cyclotron frequency. It is confirmed from the relation between the hf field strength needed to suppress the wave and the plasma potential giving a rise in the wave that the hf electric field parallel to a confining steady state magnetic field reveals major effect on the suppression of the flute like mode and that the perpendicular one has minor effect. (auth.)