Numerical Assessment of Plasma Parameters and Surface Flux Scaling in the HIDRA Stellarator

Pre-online scaling of expected HIDRA operating conditions has been analyzed using EMC3-EIRENE, to which a self-consistent local Bohm-like diffusivity has been added. An inboard and outboard midplane limiter were tested with RF input to core-edge power deposition efficiencies of 10-50\% for a 26 kW 2.45 GHz combined RF input discharge. Scaling laws for peak electron temperature, Bohm-like diffusivity, and heat and particle fluxes have been calculated for both low- and high-field discharges; peak electron temperatures, particle diffusivity, and heat fluxes at the outboard limiter were seen to follow approximately a power-law of type $f(P_{RF})\propto a P_{RF}^b$, with typical exponents in the range $b \sim 0.55 - 0.60$. Higher magnetic fields have the tendency to linearize the heat flux dependence upon the RF power, with exponents in the range of $b \sim 0.75$. Particle fluxes on the outboard limiter are seen to saturate first, and then slightly decline for RF powers in excess of 120 kW in the low-field case and 180 kW in the high-field case.