Investigating MHD stabilized mirror configurations with theory and simulations

Stabilizing the MHD interchange mode is fundamental to all mirror traps. With growth rates around an inverse ion bounce time ($\gamma \sim v_i/2 L$), this mode is lethal before any meaningful plasma can be made. The WHAM (Wisconsin High-temperature superconductor Axisymmetric Mirror) experiment anticipates $\gamma \sim 500$ kHz for a 10 keV Deuterium plasma in a 1 m device. It plans to use shear flow stabilization, which has been shown in several other experiments to saturate the $m=1$ interchange mode at small amplitude, rendering it harmless. However, some theoretical work predicts that a successful WHAM experiment may access regimes where shear-flow stabilization is insufficient. In anticipation, this work explores through application of theory and VPIC simulations alternative options, including high plasma beta effects, feedback stabilization (inductive and electrostatic), and the use of divertor geometries. Each of these options can lead to non-adiabaticity and rapid loss of the fusing fast ions. I will present research analyzing the trade-offs between these stabilization schemes and fast-ion confinement in realistic device geometries. To verify these results, several experiments will be proposed for the WHAM device.