Conceptual design and optimization of an ITER-type ICRF antenna on CFETR

The Chinese Fusion Engineering Testing Reactor (CFETR) plans to use an ITER-type antenna and couple similar to 30 MW ion cyclotron range of frequencies (ICRF) power to the plasma. In this paper, the physical design of a CFETR antenna in the midplane port is carried out. Parameter scans were performed to study the optimized toroidal and poloidal numbers of straps as well as the optimized geometric sizes of the straps. The coupling resistance, power spectrum, maximum voltage in the resonant transmission line of the strap and parallel electric field in the antenna vicinity are used to determine the performance of the studied antennas. It is shown that four poloidal substraps (i.e. quadruplets) and six toroidal strap columns arranged in half of the antenna allows the antenna to have the best coupling capability. To improve the coupling capability of the proposed antenna model, local gas puffing methods, as well as various antenna phasings, are studied. It is indicated that the coupling resistance can be increased by a factor of three for all studied antenna phasings when applying the midplane gas puffing with a gas puff rate in the order of 4 x 10(23) el s(-1). The toroidal phasings suitable for heating include (0, pi, 0, pi, 0, pi) and (0, pi, pi, 0, 0, pi).