Fast sweep of current phases in ICH antenna straps

Ion cyclotron (IC) system for KSTAR (Korean Superconducting Tokamak Advanced Research) tokamak has been designed to be capable of fast sweeping the phase intervals of the antenna strap currents with all the mechanical tuners fixed. It is shown that the fast sweep is possible by use of proper decoupler circuits. Design and tuning method for the decoupler circuit are described. We show that the circuit works satisfactorily by examining its behavior under the fast sweep.