Son Jong Wang

Development of 2 MW Dummy Load for KSTAR ICH System

A 2 MW dummy load with a frequency ranging from 30 to 60 MHz is developed for the KSTAR ICH transmitter and the cold test shows that VSWR is less than 1.35 for the temperature variation of 17 °C. DC test also shows that overall temperature increase is less than 3 °C for 400 kW. RF test is done for the RF power of 140 kW and Max. VSWR is about 1.4 at the temperature of 40 °C.

Development of KSTAR ICRF system for long pulse operation

The ICRF system for the KSTAR tokamak is being developed to support long-pulse, high-β, advanced tokamak fusion physics experiments. The ICRF system will deliver 12 MW of rf power to the plasma for 300 seconds through two antennas located in adjacent ports. With the frequency range of 25 to 60 MHz, it provides heating for the plasmas, centrally peaked current drive, and off-axis current drive using mode-conversion for various operating scenarios over a range of magnetic fields. Steady-state relevant ICRF technologies have been developed in the area of the antenna, the vacuum feedthrough and the matching devices.

Performance test of the transmission components for KSTAR ICH system on the test bed

6 MW will be coupled to the plasma by using four strap antenna in KSTAR (Korean Superconducting Tokamak Advanced Research) ICH system where 8 MW rf power is launched from the transmitter in the frequency range from 25 to 60 MHz. There are two important factors in the design of KSTAR ICH system. One is the breakdown voltage in the transmission system which limits the maximum rf power coupled to the ICH antenna and another is the removal of the heat from the rf ohmic loss during the long pulse operation. Maximum breakdown voltage and current in ICH system are 35 kV and 1kA, respectively and components are designed for the operation of 300 seconds. The test bed is designed to produce at least 35 kV/1 kA by applying low rf power up to 30 kW and high voltage/current test is performed on the vacuum feedthrough and other transmission components.