Initial Design of the 60 Megawatt Rotating Magnetic Field (RMF) Oscillator System211 for the University of Washington 'TCS' Field Reversed Configuration Experiment

摘要

This paper presents the initial electrical and mechanical design of two phase-211u001elocked 30 Megawatt RMS, 150 kHz oscillator systems used for current drive and 211u001eplasma sustainment of the Translation, Confinement, and Sustainment (TCS) field 211u001ereversed configuration (FRC) plasma. By the application of orthogonally-placed 211u001esaddle coils on the surface of the glass vacuum vessel, the phase-controlled 211u001erotating magnetic field perturbation will induce an electric field in the plasma 211u001ewhich should counter the intrinsic ohmic decay of the plasma, and maintain the 211u001eFRC. Each system utilizes a bank of 6 parallel magnetically beamed ML8618 211u001etriodes. These devices are rated at 250 Amperes cathode current and a 45 kV plate 211u001evoltage. An advantage of the magnetically beamed triode is their extreme 211u001eefficiency, requiring only 2.5 kW of filament and a few amps and a few kV of grid 211u001edrive. Each 3.5 uH saddle coil is configured with an adjustable tank circuit (for 211u001etuning). Assuming no losses and a nominal 18 kV plate voltage, the tubes can 211u001ecirculate about 30 kV and 9 kA (pk to pk) in the saddle coil antenna, a 211u001ecirculating power of over 33 megawatts RMS. On each cycle the tubes can kick in 211u001eup to 1500 Amperes, providing a robust phase control. DC high-voltage from the 211u001etubes is isolated from the saddle coil antennas and tank circuits by a 1:1 211u001ecoaxial air-core balun transformer. To control the ML8618's phase and amplitude, 211u001efast 150 Ampere totem-pole grid drivers, a hot-deck and an off hot-deck are 211u001eutilized. The hot-decks use up to 6 each 3CPX1500A7 slotted radial beam triodes. 211u001eBy adjusting the conduction angle, amplitude may be regulated, with inter-pulse 211u001etiming, phase angle can be controlled. A central feedback timing chassis monitors 211u001eeach systems saddle coil antenna and appropriately derives each systems timing 211u001esignals. Fiber-optic cables are used to isolate between the control room timing 211u001echassis and the remote power oscillator system. Complete system design detail 211u001ewill be presented in addition to anticipated (computer generated) performance 211u001echaracteristics. Initial design and construction began in FY97, and will continue 211u001ethrough FY98, with delivery to the experiment in FY99, for commencement of 211u001ephysics experiments on sustaining the FRC.