One of the primary challenges of Ion Cyclotron Range of Frequencies (ICRF) heating is the reduction of impurities associated with ICRF operation. ICRF-specific impurity production is thought to result from sputtering of Plasma Facing Components (PFC) by ions accelerated by rectified radio frequency (RF) sheaths. A new magnetic field-aligned antenna was optimized for magnetic flux coupling, power handling, and minimized integrated E_(||). Using a finite element method (FEM) simulation with cold plasma and lossy dielectric models, four toroidal antenna phasings were analyzed for the rotated antenna: [0, pi, 0, pi], [0, 0, pi, pi] [0, pi, pi, 0], [0, 0, 0, 0]. In each case, the rotated antenna had reduced integrated E_(||) relative to the existing, horizontal antenna geometry. The average reduction in the integrated E_(||) was a factor of 2-3. However, the most significant result occurs for monopole [0, 0, 0, 0] phasing. Monopole phasing, which results in such overwhelming impurities on Alcator C-Mod that it precludes operation, actually had the greatest E_(||) mitigation of all possible phase configurations for a rotated antenna. This is an especially significant result because monopole phasing provides the optimum magnetic flux coupling to the plasma. Thus, an ICRF antenna aligned with the equilibrium magnetic field should create the lowest RF sheath potentials and impurity generation while coupling the most power to the plasma, particularly when operated in monopole phasing.
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