Liquid stub tuner for ion cyclotron heating

R. Kumazawa, T. Mutoh, T. Seki, F. Sinpo, G. Nomura, T. Ido, T. Watari, Jean Marie Noterdaeme, Yangping Zhao

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


Ion cyclotron range of frequency (ICRF) heating on the large helical device (LHD) is characterized by high power (up to 12 MW) and steady state operation (30 min). The LHD is a helical device (with a major radius of 3.9 m and a minor radius of 0.6 m) with superconducting coil windings (1=2, m=10). The main purpose of physical research is to investigate currentless and disruption-free plasma. Research and development for steady state ICRF heating has been carried out in recent years: A high rf power transmission system consisting of stub tuners, a ceramic feedthrough, and an ion cyclotron heating loop antenna has been developed. In addition, steady state operation of a rf oscillator has been achieved at a power higher than 1 MW. A liquid stub tuner has been proposed as an innovation. The liquid stub tuner makes use of the difference between the rf wavelengths in liquid and in gas due to the different relative dielectric constants. The liquid stub tuner has been experimentally proved to be a reliable rf component for high power transmission systems. Test results have quantitatively demonstrated that it can be used at high if voltage: 61 kV for 10 s and 50 kV for 30 min. Furthermore, the liquid surface can be shifted under high rf voltage without breakdown, which suggests that it can be employed as a feedback control impedance matching tool to keep reflected rf power at a low level with regard to a temporal variation of plasma loading resistance.

Original languageEnglish
Pages (from-to)2665-2673
Number of pages9
JournalReview of Scientific Instruments
Issue number6
Publication statusPublished - Jun 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Instrumentation


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