Theoretical Model and Particle-in-Cell Simulation of Vacuum Magnetically Insulated Electron Flow With Off-Centered Cross Section

Magnetically insulated transmission lines (MITLs) are essential for transmitting high-power pulses in accelerators for high-energy-density physics. However, the off-centered effect of electrodes in long MITLs of large-scale pulsed power accelerators is nonnegligible, which can generate nonuniform electromagnetic fields and charged particle flow. In this study, the 1-D magnetically insulated flow theory is extended to a long MITL with an off-centered cross section based on the pressure balance equation. Solutions relating operating voltage
${V}$
to the anode current
${I} _{a}$
and cathode current
${I} _{c}$
, are derived, and 3-D particle-in-cell (PIC) simulations are performed to verify and rescale the extended model. The results show that the azimuthal magnetic field of an off-centered MITL is approximately the cosine function of the azimuthal angle. Based on the agreement between the extended model and the PIC simulation, the dependence of the charge uniformity coefficient on the operating voltage and off-centered coefficient is summarized. The charge uniformity of an off-centered magnetically insulated flow increases with the operating voltage and decreases with the rising off-centered coefficient. Furthermore, the results illustrate that a 5% off-center displacement of the center conductor in an MITL gives about 6.5% non-uniformity in azimuthal magnetic field and about 0.13% increase in self-limited current to ensure power transmission.