Fusion Science and Technology / Volume 61 / Number 4 / May 2012 / Pages 301-308
Ion cyclotron range of frequency (ICRF) heating has been used in tokamaks as one of the most successful auxiliary heating tools and has been adopted in EAST. To ensure the steady operation of the ICRF heating system in EAST, the research and development of the fast ferrite tuner (FFT), which aimed to achieve real-time impedance matching of transmitter to antenna, has been carried out. The design and analysis of the FFT is an iterative process where multiple parameters have to be taken into account. The dimensions of the FFT should be chosen as a compromise between relative equivalent electrical length and high-power performance by using the finite element method and numerous computer simulations. The first prototype aimed at achieving a response time of milliseconds and operation with a peak power of 300 kW, which will inform us about the radio-frequency and the high-power performance of such a ferrite tuner. The bench test results have demonstrated that the FFT with a tuning speed of [approximately]200 ms is faster than the traditional methods, and it can be one of the candidates for the real-time impedance matching of the ICRF heating system in EAST. The high-power performance of the FFT should be tested in the EAST 2012 spring campaign. To be fit for the real-time impedance matching for ICRF heating experiments, development of a new prototype, which aims at a response time of 0.5 ms, an insertion loss of <1%, and operation with a peak power of 1.5 MW, is in progress.