Effect of charge, feed, and test cable lengths on R2SPG waveforms

The random repetitive squarewave pulse generator (R²SPG) was developed for in situ upset testing of cable connected equipment. This pulser uses a charge line and a vacuum switch to produce a broadband transient that approximates a damped squarewave with a risetime of the order of a few nanoseconds, determined by the impedance discontinuities of the switch, and a ringing frequency that is related to the electrical length of the charge and feed lines. In order to better understand the relationships between the lengths of the charge, feed, and test cables, a controlled experiment was performed that varied each of these independently. The currents induced on the test cable were consistent with a simple transmission line model. The ringing frequency of the pulser, determined by the electrical length of the charge and feed lines, was generally discernible, as was the resonant frequency of the test cable. The peak amplitude of the transient and the decay rate of the pulse spectrum were unaffected by changes in the charge and feed lines