Potential formation due to ECR under mirror configurations of magnetic field

Abstract

Plasma potential formation is investigated in a fully ionized collisionless plasma flow in the presence of an electron cyclotron resonance (ECR) point under simple mirror configurations of magnetic field. When ECR takes place at the magnetic-well bottom, a potential structure is observed to consist of a negative potential depression around the ECR point and a subsequent positive potential peak. This potential structure gradually collapses in the timescale determined by the ion-flow speed. In the case of a converging magnetic field, such a potential structure is observed to persist in the steady state, when the ECR point is located in the region of good magnetic-field curvature. However, this structure is formed only transiently when the ECR point is located in the region of bad magnetic-field curvature. When ECR takes place in a diverging magnetic field, on the other hand, there appears a strong potential drop along the field lines, which results from a field-aligned electron acceleration, being accompanied by an effective ion acceleration.