Development of a rotating magnetic field system to emulate a pulsar magnetosphere in BRB*

A rotating magnetic dipole experiment is being readied for the BRB device at the Wisconsin Plasma Physics Laboratory (WiPPL).  The experiment will attempt to emulate the magnetosphere of an obliquely rotating pulsar and to demonstrate the production of an outgoing plasma wind.  The driver consists of an orthogonal pair of Helmholtz-like drive coils resonated at ~6 kHz and two tube-based amplifiers for generation of sine and cosine coil currents of amplitude 30 kA-turns.  The in-air coils will be placed in a dielectric pressure vessel at the center of BRB.  Power will be fed to the drive coils and an additional DC obliquity-adjustment coil from transmission lines running through a support pedestal coaxial with BRB.  Magnetic shielding of the pedestal surface will be attempted by arranging the transmission lines to form a rotating separatrix with the dipole field.  The amplifier's average power limit of ~150 kW poses a significant challenge in producing the targeted driver performance.  Circuit simulations and ring-down experiments at full power have demonstrated feasibility for a single coil channel.  These will be followed by an integrated test of a sustained 10 to 20 ms burst for both channels.  The pressure vessel is currently undergoing tests for vacuum compatibility and mounting in BRB.