Effects of Collision Velocity and Mirror Ratio on Collision/Merging Processes of Field-Reversed Configurations

The effects of collision velocity and mirror ratio on the collision/merging processes of field-reversed configurations (FRCs) were experimentally evaluated. In the collisional merging experiment, the reversal field structure is reformed despite experiencing destructive perturbations resulting from collisions at supersonic/Alfvenic velocity. However, reformation of the reversal field structure was not observed under some experimental conditions, such as slow collision velocity or low mirror ratio. The radial profile of the reversal field structure and its time evolution were observed using an internal magnetic probe array. Collisional merging of FRCs was attempted by adjusting the external field profile. Experimental results suggest the dependence of the trapped poloidal flux of the formed FRC after merging on collision velocity and external magnetic boundary. (C) 2022 The Japan Society of Plasma Science and Nuclear Fusion Research