30-60 MHz FWCD system on DIII-D: power division, phase control and tuning for a four-event antenna array

The 2-MW fast wave current drive system on DIII-D is intended to provide near-term demonstration of up to 0.3 MA of current driven by the fast wave. The system used to drive the four-element phased antenna array which produces the required directional spectrum is presented. This system must be able to cope with strong coupling between antenna elements and the time-varying plasma load seen by the antennas. Computer modeling shows that this system should be able to maintain a directional spectrum at full power under most anticipated load conditions.<
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