High peak current burst repetitive operation of a 125 mm thyristor

Repetitive operation of symmetric 125 mm thyristors has been demonstrated under burst conditions consistent with some electric gun applications. The thyristor utilizes a unique compact package that provides for double-sided cooling with a thermal resistance from junction to sink of 0.0033 K/W. Single shot testing was performed using a 10-m/spl Omega/ pulse-forming network with a total capacitance of 21 mF into a matched load to determine operational limits. Computer simulations of the temporal behavior of the device using actual current pulse shapes were consistent with the experimental results. The device operated in a satisfactory manner at 120 kA peak current. Repetition rate testing was performed under burst conditions with large voltage reversals at the end of the pulse. A 26-m/spl Omega/ PFN with total capacitance of 14 mF charged to 3 kV with a stored energy of 63 kJ was initially operated into a mismatched load of 13 m/spl Omega/. This provided a peak forward current of 75 kA and transferred charge of 45.4 C and a peak reverse current of 2.5 kA and 0.029 C residual charge. At the end of the pulse a negative voltage spike of -1.8 kV of 12 /spl mu/s duration was generated with -0.86 kV remaining on the network. Since no deleterious effects were observed, all additional tests were performed with a shorted load. A device design with involute gate structure has been developed and reliable operation with di/dt´s in excess of 1 kA//spl mu/s and higher current levels is anticipated.