Electric potential in partially magnetized E × B discharges

Abstract

Ability to control the electric potential inside the plasma is promising for various applications of E × B plasma because the trajectory of particles, which meets the desired purpose, is mainly determined by the drift motions in the external electric and magnetic fields. In the E × B source, it is well known that the equilibrium states and plasma density and temperature gradient can be sources of plasma instability, which, in turn, affects global plasma parameters. However, the effect of instability on the electric potential has not been verified so far. In this work, correlation of the plasma potential and instability is investigated through simplified-circuit modeling. The consideration of the transverse conductivity of electrons across the magnetic field reflecting the turbulence collision frequency well explains the plasma potential closer to the anode potential despite the presence of negatively biased cathodes. Eventually, this result indicates that the instability can restrict the variation of plasma potential in partially magnetized plasma.