Effects of Controlled Flow-Shear on Low-Frequency Instabilities in Magnetized Plasmas

Abstract

Abstract:The external and independent control of parallel and perpendicular flow shears in collisionless magnetized plasmas are realized using two newly-developed plasma sources. The ion flow velocity shears parallel to the magnetic-field lines are then observed to destabilize not only the D'Angelo mode but also the drift-wave instability depending on the sign of the parallel shear in the absence of field-aligned electron drift flow in laboratory experiments. On the other hand, perpendicular ion flow velocity shears are demonstrated to suppress the drift-wave and the ion-cyclotron instabilities, and furthermore, these suppressions are found to take place independently of the sign of the perpendicular shear.

Study of Fluctuation Suppression during Potential Formation in the Tandem Mirror GAMMA 10

“…The relationships between the suppression of potential fluctuation and the potential and the suppression of fluctuation by the positive electric field are clearly observed. The threshold of the drift-type fluctuation sup-pression by the electric field is about 2 V/cm according to Hatakeyama's study [13][14][15]; our results are comparable to his. The E × B drift shear may suppress drift-type fluctuations.…”