Improvement of plasmoid acceleration performance by increased magnetic pressure gradient for high-Mach number shock generation

The field-reversed configuration (FRC) collisional merging experiment in the FAT-CM device at Nihon University has been conducted for the generation of collisionless shock waves that are considered to cause the generation of nonthermal particles. Two FRC-like plasmoids with extremely high-beta formed by field-reversed theta-pinch are translated directly toward each other and collide at super-sonic/Alfvenic velocity. The acceleration performance is improved to generate high-Mach number shocks by generating the high-magnetic pressure gradient at the boundary between the formation and confinement sections. In this study, an increase in the translation velocity in the shortened coil geometry is presented. Changing of coil geometry may affect not only the velocity but also other parameters. (author)