Multi-megawatt solid state RF source

An RF system using solid-state switching has been designed and constructed that is capable of driving a pair of loop antennas with a circulating power of 60 MW for millisecond pulses. The primary application of this system is to produce an oscillating magnetic field in the frequency range of 0.2 to 0.7 MHz, to generate and sustain large plasma currents. The maximum power transfer from the RF source was measured to be greater than 10 MW. The driver consisted of 12 insulated gate bipolar transistor (IGBT) modules driven in parallel, and was capable of switching 20 kA at 1600 V. A sinusoidal current waveform with large circulating currents was obtained on the antenna by incorporating the antenna in both parallel LCR and series LCR resonant circuits. Other switch configurations such as the H bridge are being evaluated for a much larger driver that would deliver enough power (several hundred MW) to bring the plasma to fusion conditions.