Plans for investigating HHFW Edge Plasma Interactions in NSTX-U

In NSTX experiments, up to 60% of the injected power from the High Harmonic Fast Wave (HHFW) could be lost in the Scrape-Off-Layer (SOL), when the fast wave is able to propagate in front of the antenna [Hosea, PoP 15, 056104 (2008)]. This poster discusses diagnostic and modeling progress for investigating HHFW interactions with edge plasma in upcoming NSTX-U experiments. An RF spectral recorder is a key development that enables direct wavefield measurement in the divertor region. Control of a high-speed, multi-channel digitizer is demonstrated with LabVIEW. A 2D SOL profile model is being constructed for accurate wavefield evaluation in the divertor region. The temperature profile is first evaluated by solving a heat conduction equation using a finite element approach in the Petra-M workbench. The density field will be constructed by applying pressure conservation along the field line. Current work focuses on achieving convergence by mesh refinement and high-order elements for the high anisotropy expected between the parallel and perpendicular heat conduction coefficients. Eventually, this model will be used to evaluate power losses resulting from elastic electron-ion and electron-neutral collisions in the divertor region.