The slow collisional ExB ion drift characterized as the major instability mechanism of a poorly magnetized plasma column with an inward-directed radial electric field

摘要

The low-frequency instability of a cylindrical poorly magnetized plasma withan inward-directed radial electric field is studied changing the gas pressureand the ion cyclotron frequency. The unstable frequency always decreases whenthe gas pressure is increased indicating collisional effects. At a fixedpressure, the unstable frequency increases with the magnetic field when theB-field is low and decreases at larger magnetic field strength. We find thatthe transition between these two regimes is obtained when the ion cyclotronfrequency equals the ion-neutrals collision frequency. This is in agreementwith the theory of the slow-ion drift instability induced by the collisionalslowing of the electric ion drift (A. Simon, Phys. Fluids 6, 382, (1963).