Voltage and current measurement in pulsed power circuits

The performance of high voltage probes at fast risetimes demonstrates an immediate conflict of voltages exceeding 10 kV and risetimes of a few nanoseconds. The problem of risetime can easily be illustrated by the performance of a good quality oscilloscope probe (Tektronix P6131). The risetime of the basic probe can be improved to achieve the maker´s specification (1-2 ns) by using specially shortened leads and pins supplied with it. But, to achieve this specification it can be seen that the probe slightly distorts the input pulse. The probe is attached to a high quality coaxial attenuator which is used to display the fast input pulse on the left hand side of each waveform in fig 1. The reason for distortion is simply circuit loading caused by the probe. It is axiomatic that best risetime performance is achieved by closer coupling, i.e. matching to the circuit, which in turn will distort the waveform