Performance comparison of the two ICRF antennas in EAST

The experimental advanced superconducting Tokamak has two suits of ion cyclotron radio frequency heating systems, in which the two antennas are of different structures. Their performance is assessed and compared by CST microwave studio. The radiating capacity of antennas and the arcing around them are estimated. The impurity release is analyzed by the radio frequency (RF) potential in the plasma sheath. The simulation results show that the radiating capacity for the folded antenna (I-port) is better than those for the double loops antenna (B-port). However, the folded antenna is worse than the double loops antenna in terms of breakdown. Moreover, the impurity production is relevant to spectrum shaping. The RF potential at (0, π, π, 0) phasing with the peak of spectrum k_// = 8.5 m^-1 is lower than the one with other phases. The impurity is reduced obviously when the folded antenna is powered with (0, π, π, 0) phasing. (authors)