Non-destructive examination of impulse generator pulses

To produce a single-shot impulse waveform with a peak voltage of 600 kV, having 15 kJ of energy, a Marx Bank was used which had six 100 kV, 0.5 /spl mu/F capacitors arranged in six stages, charged in parallel and discharged in series. The overall performance and reliability of this Marx Bank was improved by inserting new high power, noninductive resistors in the discharge circuit to dissipate excess energy resulting from switch misfires and load faults. Among the specific technical design issues addressed is the development of a new nondestructive examination technique (NDET) for different modes of Marx Bank operation, which determines if output load faults or switch misfires will be safely tolerated by the resistors used in the charge/discharge circuits. Initial results, including computer simulations and laboratory measurements, using a new fault protecting, energy-absorbing resistor placed in series with the Marx output load are presented. Also, circuit design recommendations for further reduction in fault energies dissipated in the tail resistors of a misfired stage are discussed. As well as the elimination of current ringing from the fault-protecting resistor under fault conditions is described.