Nanosecond - Current Probe for High Voltage Experiments

A current probe has been designed which allows measurement of ns;pulsed currents in high voltage environments. The probe consists of a current transformer and an optical transducer. The transformer coil in a metallic torus is considered as a slow-wave transmission line and is terminated with its wave impedance. In this mode of operation current pulses shorter than twice the transit time of the transmission line are linearly transformed. The voltage gain of the transformer is considerably greater than that of commonly used self integrating Rogowski-coils. The signal current drives a light emitting diode, with an impedance negligible compared to the wave impedance. The emitter is optically coupled to a photodioae, thus isolating the recording system from the pulsed power experiment. The probe, as used has a linear response for pulses shorter than about 400 ns and currents of > 1 A. The ri set ime is less than 5 ns.