Analysis and Measurement of Transient Currents in Railgun With Loop Probes

Several loops are placed at one side of the rails along a straight line, and the transient current is calculated with the measured magnetic field waveforms and distances between probes and currents for the long-line current models. According to the skin effect and the deformation of rails, distances between currents and probes are hard to get for each shot. If two probes are used together, it is easier to measure the single line current waveform, without measuring the distance between probes and currents beforehand. The current waveforms can be calculated only with the calibrated distance between two probes and field waveforms. For the railgun's rail currents, we can use three loop probes. The current waveforms can be easily obtained from the three magnetic field waveforms without knowing the shift positions of the rail currents. The commercial Pearson current monitor model 1423 is used to calibrate and verify the results. The results are compared with each other for the single loop, two loops, and three loops. The results show that, while it is good to measure the transient currents with one or two loops, it is better when three loops are used. The method is especially useful for situations in which the huge Rogowski current probes are hard to use because of limited space.