The ARIES-RS tokamak power plant has been designed based on the reversed shear plasma concept, with an operating beta of ~5.0% and a well-aligned bootstrap current fraction of ~90%. In order to maintain MHD stability at the design point, three RF current-drive systems, operating in different frequency regimes, are required for driving and controlling the equilibrium current density profile. The power from these systems is expected to heat the plasma from startup to its final operating conditions. The three RF systems make use of ICRF fast waves, high-frequency fast waves (HFFW), and lower hybrid waves (LHW) for on-axis, off-axis (inside the RS region), and edge current drive, respectively.

The major design criteria for the RF systems are high power efficiency, minimal power core intrusion, Class-C waste disposal, and ease of maintenance. The system component designs are primarily based on those of the ITER-EDA, and extrapolated to the ARIES-RS regime. Maximizing the power handling capability of the RF components, it is possible to fit all RF launchers into a 2mx2m movable plug-in unit in a specially designated blanket sector. The resultant first-wall penetration of the launchers is 2.53 m², which is 0.58% of the total first wall area, and is located near the outboard midplane.

For the ARIES-RS design, the total RF power delivered to the plasma is 102 MW. The ICRF launcher is a toroidal array of six quarter-wavelength folded waveguides, while that of the LHW system has five modules of reflector waveguide and hyperguide combinations, each radiating a separate wavelength. A detailed design of the HFFW launcher has not been carried out, but it is envisaged to be a 2-D array of combline structures.

The in-vessel RF system components all have V-4Cr-4Ti alloy as the structural material (as in blanket and shield), with the interior coated with a thin layer of DS copper, GlidCop AL-25. The coolant is liquid lithium at an average temperature of 500 C near the first wall midplane. The total amount of copper used (surface coating and passive waveguides) has been estimated to be ~0.2% of the total structure volume, and therefore should not pose a waste disposal issue if the RF launchers are replaced together with the blankets.

*Work supported by USDOE grant DE-AC03-95ER-54299.