KSTAR ICRF antenna development at the KAERI test facility

The ion cyclotron range of frequency (ICRF) heating system of the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak couples 6 MW of RF power to the plasma with a 4-strap antenna. The antenna has been designed to operate for a pulse length up to 300 sec. A prototype ICRF antenna was fabricated, and with no water-cooling, an BF test was performed to study the standoff capability of the antenna. In that test, half of a current strap was connected to the matching circuit via a vacuum feedthrough and a directional coupler, and the other seven ports were shorted at the input ports. Test results showed standoff voltages and pulse lengths of 33.2 kV for 60 sec and 25.2 kV for 300 sec. The ICRF heating system, including a resonant loop with a matching circuit, was built at the RF test stand in KAERI. Resonant and matching characteristics for various frequencies were investigated.