Introducing the Wisconsin HTS Axisymmetric Mirror

Currently in early stage of construction, the Wisconsin HTS Axisymmetric Mirror (WHAM) is motivated by major advances in both technology (high temperature superconductivity) and physics (axisymmetric MHD stability with keV-level electrons). A pair of 17 T mirror coils (from CFS) generates an accessible 4 T contour in the plasma for breakdown and heating with a 110 GHz gyrotron (retired from DIII-D). Endcell biasing shears the rotation profile to impose MHD stability. 25 kV NBI sources a nonthermal ion population; device confinement $\tau_{ii}$ improves rapidly with average ion energy as an ambipolar potential and carefully maintained expander confine electron heat. Early reactor studies rely on MeV-level NBI, we instead pursue a breakthrough approach in which the low energy NBI seed ions are accelerated in situ by HHFW. Numerical support leverages vast expertise from several domestic institutions.