Integrated modeling of fueling and CX losses from edge neutrals in WHAM

WHAM aims to operate in the classical confinement regime [1] and validate models used to scope reactor-relevant mirrors. However, the presence of large edge neutral pressures result in significant charge-exchange (CX) losses that limit the fast ion confinement time, instead of being set by the expected mirror confinement time.

We demonstrate the first integrated modeling of edge fueling and CX losses in a realistic mirror geometry. The Integrated Plasma Simulator (IPS) [2] framework is used to couple the plasma transport code CQL3D-m [3] to the fully-kinetic 1D-3V neutral transport solver KN1D-C [4,5] . The latter retains gyro-orbit corrections, of importance in WHAM where a/rho_i = 3. Simulations with realistic edge neutral densities (~10^18 m-3) recover particle confinement times of ~1 ms, in agreement with experiment.

Further coupling with the ray-tracing code GENRAY [6] allows for self-consistent modeling of electron cyclotron heating breakdown and depletion of the neutral particle density. Preliminary results show the formation of a highly-confined fast-electron tail, whose size and energy depends on microwave power. Validation against experimental results will be shown.