Design and operations of a load-tolerant ICRH system in Experimental Advanced Superconducting Tokamak

Ion cyclotron resonance heating (ICRH) has been a dependable tool for sturdy plasma heating with high RF power of several megawatts. However, a sudden increase in the reflected power during ICRH heating experiments is a problem that should be solved for future fusion experimental devices. To solve this issue, the load tolerant matching network have been designed for ICRH system in EAST Tokamak. The matching network includes 3-stub tuner impedance matching system, conjugate-T structure, 30 Ω to 50 Ω transmission line and center grounded antenna strap. By keeping a low reflection ratio in the network for a wide range of resistance, this matching network could allow sturdy high-power operations without fast impedance matching in EAST tokamak. In our matching network, the two arms of a conjugate-T were designed to have λ/2 length difference which could mitigate current imbalance and antenna poloidal phasing out of control problem. And the T-point corresponds to the maximum point of standing wave voltage, which could greatly improve the input impedance of antenna.