Studies of Lower Hybrid Range of Frequencies Actuators in the ARC Device

High field side (HFS) placement of lower hybrid range of frequencies (LHRF) actuators is attractive from both the standpoint of a more quiescent scrape off layer (SOL) and from the improved LH wave accessibility and penetration to higher electron temperature that results from the higher magnetic field on the HFS [1]. The resulting profiles of LH current drive (LHCD) are also more suitable for advanced tokamak (AT) operation where it is most desirable to provide a significant (\textasciitilde 20-30{\%}) contribution to the total current density with a broad profile extending from r/a \textasciitilde 0.5-0.85. Here we re-assess HFS LHCD in the ARC device [2] using a hierarchy of LHCD models that include a combined adjoint plus ray tracing calculation, a ray tracing plus 3D Fokker Planck calculation, and a full-wave plus Fokker Planck simulation. [1] B. LaBombard et al, Nucl. Fusion 55, 053020 (2015). [2] B. Sorbom et al, Fus. Eng. Design 100, 378 (2015).