Development of fast-wave ICRF [ion cyclotron range of frequencies] current drive systems at ORNL

A series of proof-of-principle fast-wave current drive (FWCD) experiments in the ion cyclotron range of frequencies (ICRF) will begin soon on the DIII-D tokamak at General Atomics. These experiments will use a four-strap, 2-MW phased antenna array designed and built at Oak Ridge National Laboratory (ORNL). The antenna array will operate at a frequency of 60 MHz and is expected to drive currents at 0.25 to 0.5 MA in moderate-density (bar ne ∼ 1.3 x 1019 m-3) plasmas with Te0 ∼ 4 keV and a toroidal field B = 1 T. We discuss development work undertaken at ORNL to predict the performance of the phased array and its feed circuit and to assist in the design of future FWCD systems. 6 refs., 5 figs