An Iterative Method to Determine the Vacuum Impedance of Magnetically Insulated Transmission Line System

In this article, the dimensionless ratio E/cB at the starting point of constant-gap section of the magnetically insulated transmission line (MITL) at the time of peak MITL voltage was used as a figure of merit of a disk MITL. Taking a 15-MA driver as an example, the equivalent circuit model and the impedance iterative method are established by means of the TL-code circuit simulations. The vacuum impedance of the fourlevel outer-MITLs is determined. In particular, when the target ratio (E/cB)i is set to 0.25 (the ratio of flow current to anode current I f /Ia is 3.12%), the impedance of the four-level MITLs is 1.70, 2.12, 2.88, and 3.16 Ω. When (E/cB)i of the four-level MITLs is set to 0.15, 0.18, 0.20, and 0.22 (the ratio I f /Ia is 1.23%), the impedances are 2.68, 2.89, 3.06, and 3.02 Ω, respectively.