Single shot and burst repetitive operation of involute gate 125 mm symmetric thyristors up to 221 kA with a di/dt of 2.0 kA//spl mu/s

An involute gate design 125-mm thyristor has been developed that provides a significant increase in ability to handle higher peak currents and di/dt's, All tests were performed with a 2.5-kV thyristor, using an essentially shorted load in order to achieve 200-kA operation and to apply a full voltage reversal in less than 3 /spl mu/s. Reliable operation was demonstrated at 2.6-kV forward voltage with a reverse voltage of 2.3 kV. The peak current was 203 kA with a pulse width of 465 /spl mu/s (FWHM) and a di/dt of 1.8 kA//spl mu/s. The charge was 82 C, and the action was 13.8 MA/sup 2/s. The reverse charge was 0.19 C. The PFN was modified to reduce the impedance and simulate a sinusoidal pulse in excess of 1 kHz. Reliable operation was obtained at 221 kA with a di/dt at 2.0 kA//spl mu/s. The pulse width (FWHM) was 301 /spl mu/s with a base width of 455 /spl mu/s. Forward voltage was 2.4 kV with a reverse voltage of 2.3 kV. The forward charge, reverse charge and action were 63 C, 0.51 C, and 10.9 MA/sup 2/s, respectively. Reliable repetitive operation was performed at 151 kA with a burst of 10 pulses at a 3 ppm repetition rate.