Home / Store / Journals / Electronic Articles / Fusion Science and Technology / Volume 63 / Number 1 / Pages 49-58
S. Park, Y. S. Bae, J. H. Kim, H. Do, H. T. Kim, K. M. Kim, H. K. Kim, H. J. Kim, W. S. Han, H. L. Yang, J. G. Kwak, W. Namkung, M. H. Cho, H. Park, L. Delpech, J. Hillairet, R. Magne, G. T. Hoang, X. Litaudon, G. Wallace, S. Shiraiwa, R. Vieira, J. Doody, R. Parker
Fusion Science and Technology / Volume 63 / Number 1 / Pages 49-58
Format:electronic copy (download)
A 5-GHz steady-state lower hybrid (LH) current drive (LHCD) system is planned to support steady-state and advanced tokamak operation on the Korea Superconducting Tokamak Advanced Research (KSTAR) experiment. As an initial phase, a pulsed 5-GHz, 500-kW LHCD system has been installed in KSTAR for basic experimental studies of the LH coupling and flux saving in the plasma current ramp-up, prior to long-pulse noninductive operation in KSTAR. A Toshiba-made klystron developed in collaboration with Pohang University of Science and Technology in 2006 is utilized for the initial KSTAR LHCD system. The LH launcher is designed as a fully active waveguide grill type with a parallel refractive index n[parallel] value ranging from 1.8 to 4.3 and with high directivity. In the initial stage, the LH launcher consists of eight columns of four-way power splitters and two columns of dummy waveguides, one on each side. The operational n[parallel] value is fixed at 2.1 but can be adjusted by replacing waveguide components external to the vacuum vessel. Since the target operation pulse duration of the initial LHCD system is 2 s with an output power of 500 kW at the klystron window, the prototype klystron was recently successfully conditioned to a radio frequency power of 514 kW for a maximum pulse duration of 3 s using a matched dummy load (voltage standing wave ratio of 1.16:1). This paper presents the progress of the initial KSTAR LHCD system and the performance test results of the prototype klystron. The research plan aiming at steady-state LHCD operation in KSTAR is also described in this paper.
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