Predicting HHFW Heating Efficiency on NSTX via Whole‐Device Full‐Wave Simulation

We present a qualitative comparison of NSTX HHFW heating efficiency observations[1, 2] with results from the AORSA[3] whole‐device, linear simulation. The simulation retains a realistic geometry and core plasma kinetic physics such that scrape‐off plasma linear RF fields can be calculated. By examining L‐mode and neutral beam heated H‐mode scenarios we quantify the conditions that result in a fast‐wave coaxial mode in the scrape‐off plasma. These large amplitude coaxial modes are expected to damp on collisions or couple to non‐linear damping mechanisms and be correlated to an observed drop in core heating efficiency.