Shape control of field-reversed configuration plasma by axial compression

We propose and carry out an axial magnetic compression experiment to control the separatrix shape of a Field-Reversed Configuration (FRC) plasma. The axial compression is done in a manner as decreasing the mirror distance. By this compression, the separatrix shape will become short and fat. According to the empirical scaling law, the particle confinement time is expected to lengthen. An additional compression coil is installed into the chamber to raise the strength of the magnetic field at a certain section next to one of the mirrors. The coil with the crowbarred capacitor bank produces the compression field with the rise time of 34μs to change the mirror distance from 3.4m to 2.4m. The shape profile of the FRC becomes short and fat with the extension of plasma lifetime. (author)