Motion of magnetically injected plasma in the PBFA-II plasma opening switch during the accelerator pulse

Summary form only given. In the magnetically injected plasma (MIP) plasma opening switch (POS) under study for use on the Particle Beam Fusion Accelerator II (PBFA II), the plasma distribution, is controlled by injection along an imposed poloidal field. In experiments performed to date, the strength of the poloidal field at the cathode has been a few tenths of a tesla, while that of the toroidal magnetic field caused by the accelerator pulse has reached peak values of one or two tesla at comparable locations. Simulations of the plasma injection, supported by the experimental measurements, show that the MIP switch plasma is larger and more diffuse than the previous switch plasma. Hence, the region in which significant motion occurs is also larger. The interaction of the embedded poloidal field with this plasma motion has been investigated using MACH2. The plasma mass distribution at the time of arrival of the accelerator power pulse was determined by comparing results of simulation and experiment. Enhancement of the poloidal field was found to occur because of compression of the plasma in which it is embedded, resulting in large toroidal currents