Fast high-power thyristors triggered in impact-ionization wave mode

GTO-like thyristors 5STH-2045H0002 (4.5 kV, 18 kA/μ s) developed by ABB semiconductors are currently used at CERN in LHC Beam Dumping System (LBDS): high-power switches with high dI/dt capability and low turn-on delay time are required. Implementation of the impact-ionization triggering in GTO-like thyristor enhances its switching performance and gives new information about semiconductor physics. In this work thyristors of 5STH-2045H0002 type triggered in impact-ionization wave mode are investigated. A semiconductor opening switch (SOS) generator providing a dV/dt of several kV/ns was used as a source of triggering pulses. A thyristor switching time of approximately 200–300 ps was observed. Maximum discharge parameters were obtained for two series connected thyristors at a charging voltage of 10 kV, and a capacitor stored energy of 300 J: peak current of 43 kA, dI/dt of 120 kA/μs (limited by the discharge circuit), Full Width at Half Maximum (FWHM) of 1.5 μs. A single thyristor was tested in the repetitive mode at the charging voltage of 4.2 kV, and the stored energy of 18 J: peak current of 5.5 kA, dI/dt of 40 kA/μs, FWHM of 1.5 μs were obtained. No thyristor degradation was observed after more than one million pulses at a PRF up to 1 kHz in burst mode. Thyristor recovery time was 250 μs. The switching efficiency was up to 98% depending on dV/dt and stored energy.