Overview of a Prototype Ion Cyclotron Resonance Heating System for C-2W at TAE Technologies

A prototype Ion Cyclotron Resonance Heating (ICRH) system has been developed for C-2W, a beam-driven field-reversed configuration (FRC) experiment at TAE Technologies [1]. The system features a loop antenna mounted near one end of the confinement vessel, operable in either a full-turn (FT) or double half-turn (DHT) mode. The antenna is driven by a 2–10 MHz, 150 kW broadband amplifier. The frequency was chosen to align the resonance layer with the fast-ion turning points. The system exploits a technique refered to as "magnetic beaching", where waves launched into a decreasing magnetic field encounter multiple harmonics near the X-point of the FRC, enhancing ion-cyclotron absorption. This configuration is predicted to excitate both fast and slow waves along the axis of the device. Hybrid particle-in-cell (PIC) simulations using the code WarpX model the antenna via external currents imposed on a realistic FRC equilibrium, resolving wave polarization and energy deposition. Absorption is dominated by left-handed Alfvénic components at the resonance layer, with heating observed in scrape-off-layer. This effort represents a key step toward RF-based ion heating in FRCs and informs future system designs. [1] H. Gota et al. Overview of C-2W: high temperature, steady-state beam-driven field-reversed configuration plasmas. Nucl. Fusion 61, 106039 (2021).