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

摘要

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.