Shiyong Chen

Design and Preliminary Results of Matching Network for MW Scale High Current RF Ion Source

Abstract The RF ion source is the most promising ion source, which can be operated with steady state. When the Radio Frequency (RF) ion source works, the key point is how to transmit and couple the RF power to the plasma with the RF power transmission unit. In this technical note, the principle of RF matching network was analyzed and designed. The RF power transmission unit was tested on RF ion source test bed. Based on the experimental data, the function of each components of impedance-matching network is analyzed and optimized. The results show that matching network can keep high RF coupling efficiency with variable plasma parameters and decreases the reflected RF power.

Development of a core snubber for the neutral beam injector on EAST.

A 4-MW ion source was developed for the neutral beam injector (NBI) on Experimental Advanced Superconducting Tokamak (EAST). Breakdown nevertheless can happen during ion source conditioning and routine operations and is deleterious to the high-power ion source. To protect this ion source, a core snubber was designed to absorb the breakdown energy of the EAST-NBI ion source. A prototype core snubber was developed and tested using the ion-source test bed. The results show that with a core snubber, short-circuit currents at different high-power voltages were about one-tenth of the current without the snubber. The residual energy of the distributed capacitors had been absorbed successfully and the core snubber does protect the source from damage during breakdown. The results verified the successful development of a core snubber for the EAST-NBI.