Operation regimes of magnetically insulated transmission lines

Abstract

Magnetically Insulated Transmission Lines (MITLs) are commonly used for efticient power transport in the vacuum section of pulsed power devices. Plasma forming from metal surfaces l i m i t s the power transmitted to a load through M1TL.s. It eventually shunts the load, producing so-called MITL closure.Fundamental experiments are being performed on high intensity power transmission through coaxial cylindrical vacuum transmission lines. A current that rises to 1 MA in 100 ns is driven through the MITLs by a 2 -W , 2 -0 pulse generator (Zebra). The condition of the MITL surfaces is carefnlly controlled and characterized before each shot. Differential B-dot probes measure the current before and after the MITL, to determine the time of gap closure. Optical imaging and laser diagnostics observe the plasma evolution in the gap with time and space resolution.The radial gap of the cylindrical vacuum transmission line has been systematically varied, and the time of MITL closure measured. They increase with the radial gap size in a discontinuous manner. Critical transitions (discontinuous jumps in closure time) appear to separate distinct MITL operation regimes. This is the first experiment and data set of this kind known to the authors.Electromagnetic-particle-in-cell and radiationmagnetohydrodynamic computer modeling assist the experiment, being used to refine the experimental design and to interpret the results.

Millimeter-Gap Magnetically Insulated Transmission Line Power Flow Experiments

“…MITL power flow has been studied in detail. In order to support MITL design and understand current loss in a MITL, many individual studies involving simulation [2][3][4], analytic calculations [5][6][7][8], and experiment [9][10][11][12][13][14] have been published.…”