Recovery of electron-sheath current in magnetically self-insulated transmission lines

Magnetically self-insulated lines operating at high electric field stress have a high percentage of the current flow in an electron sheath adjacent to the cathode. Recovery of the current in this sheath is desirable for efficient power transport. The Sandia National Laboratories HydraMITE accelerator has a magnetically insulated transmission line which has a 7.6 ohm geometric impedance, and operates at 4.8 ohm indicating that approximately 40% of the current flows in the electron sheath. An experiment was conducted on the HydraMITE machine in which input and output currents were measured on a section of line which the impedance changed smoothly from 7.6 ohm to 20 ohm. Measurements were made with a range of inductive and resistive loads. The input and output currents were then compared to lumped circuit line simulations to separate losses related to inductance from electron sheath losses.