Particle-in-cell simulations of cathode plasma evolution in small-gap magnetically insulated transmission lines

摘要

The formation and evolution of the cathode plasma in small-gap magnetically insulated transmission lines (MITLs) may lead to enormous current loss and even gap closure. This issue has been investigated through particle-in-cell/Monte Carlo collision simulations. Based on gas desorption from the cathode, the plasma is formed at the cathode when the emitted electrons collide with the desorbed gas contaminants. The expansion velocity and the electron and ion density distributions of the cathode plasma were analyzed. Rapid expansion of the plasma occurs when plasma instability increases due to a transverse magnetic mode in the MITL. Factors affecting the expansion velocity such as voltage amplitude and rate of gas desorption were examined. The simulation results indicated that a relatively high desorption rate of neutral gas resulted in a higher expansion velocity for the cathode plasma. This work extends our knowledge and understanding of cathode plasma dynamics in high-current MITLs.