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).