Differential B-dot monitor used for current measure of magnetically insulated transmission lines

A differential B-dot used for current measure of the magnetically insulated transmission lines (MITL) has been developed. By using the commercial PSpice software, the equivalent circuit model of the B-dot monitor, the transfer-equations and the frequency responses of the B-dot were obtained. Calculation results show that signals with frequency more than 2.5 MHz can be perfectly measured by the B-dot. This B-dot monitor has been used for the 1.0 m long, 2 cm AK gap coaxial-MITL experiments on QiangGuang-Ⅰ accelerator. Experimental results show that with the shorted load, the current waveforms measured by the B-dots along the MITL are almost the same (the peak current is 1.0 MA, and the risetime is 125 ns), namely, the current loss along the line is negligible. This results perfectly accord with the theoretical transfer characteristics of the MITL with shorted load.