Ground isolation with common mode inductance for high voltage pulse measurement

When pulse power device discharge, the voltage to ground rises. It leads to a common mode current from probe’s ground to oscilloscope’s. The output waveform can be affected, and the oscilloscope can be destroyed sometimes. A common mode inductance(CM inductance) made by coaxial cable which enwinds a ferromagnetic core was designed between the probe and oscilloscope. The voltage to ground was calculated based on the equivalent circuit with inductance and resistance of grounded connector. The CM inductance reduced the common mode current and isolated the ground of probe to oscilloscope. The output voltage was measured using a square waveform source with the rise time of 4.8 ns, the rise time of CM inductance output is 7.2 ns. A circuit for testing the isolating impact was designed: The out