Driver optimization for a rotating magnetic field system

We measured amplifier characteristics and developed coil hardware for a rotating magnetic field (RMF) system to be tested on the Big Red Ball (BRB) device at the Wisconsin Plasma Physics Laboratory. Two orthogonal pairs of Helmholtz-like coils, which will be driven by quadrature-phased AC power supplies to produce a rotating dipole field, are to be constructed. The supplies use Class-C tube amplifiers, requiring less than 1 kW input for approximately 150 kW average power output per channel. Each channel's RMF coil will consist of 6 turns of 18 mm diameter litz wire, formed into a series pair. Our measurements have shown that the unloaded Q factor of this coil is larger than 100, permitting the necessary resonant current of 5kA in the coil given available power. However, the shape, size, and position of the coils are still in the process of optimization. The coils will be placed tightly and symmetrically in a dielectric pressure vessel at atmosphere inserted to the center of BRB, supported by a pedestal pipe.