Determination of Magnetically Insulated Transmission Line Cathode Current of a 1.0-MV Pulsed Power Generator

We have employed B-dot monitors to measure the magnetically insulated transmission line (MITL) cathode current on a 1.0-MV pulsed power machine, whose MITL anode and cathode electrodes are separated completely by the insulation stack. The MITL anode and cathode conductors are connected together by the B-dot sensors' signal transmission cables, when transmitting the outputs of the B-dot probes out of the MITL anode-cathode (A-K) gap. It provides a leakage current path and disturbs the MITL power flow unavoidably. During our experiment, the impedance of the leakage current path is increased by winding the signal transmission cables along one helical isolated inductor frame. The leakage current flowing along the outer conductors of the cables is significantly reduced, and the outputs of B-dot sensors could be delivered out of the MITL A-K gap effectively. The experiment results suggest that the B-dot sensors are able to diagnose the MITL cathode current successfully, even though the performance of the B-dot probes on this generator is not as perfect as that of the monitors employed on an induction voltage adder. Finally, particle-in-cell simulation is performed to check the accurateness of the measured MITL cathode current. It demonstrates that the peak value of the cathode current given by the B-dot monitors agrees with the simulation result very well.