Physics of current losses due to uninsulated SCL emission of electrons in MITLs*

We study the physics of uninsulated electrons in magnetically insulated transmission lines (MITLs). Uninsulated electrons can be emitted from the cathode of a MITL due to large electric fields (field stress) and cross the anode-cathode (AK) gap, thereby contributing to current losses and elec- trode heating. To understand the underlying physics of such current losses, we have developed a reduced, one dimensional (1D) electromagnetic (EM) model that has shown excellent agreement with 2D and 3D particle-in-cell (PIC) simulations. With the help of this model, we study various scaling properties of current losses in MITLs. We comment on circuit element codes (such as BERTHA, for example), which are presently the tool of choice for MITL design. Circuit element codes yield acceptable current loss predic- tions for short MITLs but significantly disagree with PIC simulations of long MITLs. We point to the deficiency in the physics leading to such dis- agreement.