DESIGN CONCEPT AND PERFORMANCE CONSIDERATIONS FOR FAST HIGH-POWER SEMICONDUCTOR SWITCHING FOR HIGH-REPETITION-RATE AND HIGH-POWER EXCIMER-LASER

A semiconductor switching power supply has been developed, in which a novel structure semiconductor device, metal-oxide-semiconductor assist ed gate-triggered thyristor (MAGT) was incorporated with a single stag e magnetic pulse compression circuit (MPC). The MAGT was specially des igned to directly replace thyratrons in a power supply for a high repe tition rate laser, Compared with conventional high power semiconductor switching devices, it was designed to enable a fast switching, retain ing a high blocking voltage and to extremely reduce the transient turn -on power losses, enduring a higher peak current. A maximum peak curre nt density of 32 kA/cm(2) and a current density risetime rate di/dt of 142 kA/(cm(2) x mu s) were obtained at the chip area with an applied anode voltage of 1.5 kV. A MAGT switching unit connecting 32 MAGTs in series was capable of switching on more than 25 kV-300 A at a repetiti on rate of 5 kHz, which, coupled with the MPC, was equivalent to the c apability of a high power thyratron. A high repetition rate and high p ower XeCl excimer laser was excited by the power supply. The results c onfirmed the stable laser operation of a repetition rate of up to 5 kH z, the world record to our knowledge, An average output power of 0.56 kW was obtained at 5 kHz where the shortage of the total discharge cur rent was subjoined by a conventional power supply with seven parallel switching thyratrons, simultaneously working, for the MAGT power suppl y could not switch a greater current than that switched by one thyratr on. It was confirmed by those excitations that the MAGT unit with the MPC could replace: a high power commercial thyratron directly for exci mer lasers. The switching stability was significantly superior to that of the thyratron in a high repetition rate region, judging from the d ischarge current wave forms, It should be possible for the MAGT unit, in the future, to directly switch the discharge current within a rise time of 0.1 mu s with a magnetic assist. (C) 1997 American Institute o f Physics.