A Repetitive Pre-ionizer Using Semiconductor Marx Generator for Compact Toroid Injector

The C-2W device (also known as 'Norman') at TAE Technologies has proven suc- cessful at generating stable, long-lived field-reversed configuration plasmas (FRCs) with record temperatures. A multi-pulse magnetized coaxial plasma gun has been developed to inject spheromak-like compact toroids to refuel the FRC's core. To minimize excess neutral gas and to improve breakdown characteristics of the compact toroid injector a pre-ionization system has been developed. The pre-ionization plasma is formed by high voltage discharge between two coaxial electrodes and accelerated by the Lorentz force. The discharge can operate at up to 1 kHz rate using the repetitive Marx generator composed of pulsed capacitors, which are charged in parallel and discharged in series by IGBT switches. The Marx generator output is -10 kV operating at a peak power in excess of 1 MW, which is consistent with the design requirements.