Electric field sensors effect on pulsed power measurements

A coaxial pulse generator was designed and constructed for an experimental study on a sub-millimeter spark-gap. D-dot sensors, used to register the waveforms in both the Pulse Forming Line - PFL and Transmission Line - TL, are not located exactly on the spark-gap. To determine the effect of sensor position on voltage measurements, simulations were carried out. The PFL voltage (V1) and TL voltage (V2) recorded in different places along the lines are analyzed by using distributed parameter models of the corresponding coaxial transmission lines and also including the electric-arc non-linear model in the spark-gap switch. When comparing the voltage signal recorded just before the spark-gap (V1) with the signal recorded some tens of millimeters backward (V1´), two differences can be observed. The former is the delay in the onset of the two signals. The second difference is a variation in the waveform of the signals. A hypothesis was formulated claiming that this is because the sensor does not record all the charge moving along the transmission line.