First Ohmic Discharge Assisted with RF Power in QUEST Spherical Tokamak

Osamu MITARAI; Kazuo NAKAMURA; Saya TASHIMA; Makoto HASEGAWA; Hiroshi IDEI; Mizuki SAKAMOTO; Kazuaki HANADA; Hideki ZUSHI; Kohnosuke SATO; Masaki ISHIGURO; Hai Qing LIU; Yuta HIGASHIZONO; Aki HIGASHIJIMA; Hisatoshi NAKASHIMA; Shoji KAWASAKI; Yuichi TAKASE; Takashi MAEKAWA; Nobuhiro NISHINO

doi:10.1585/pfr.6.1402003

Regular Articles

First Ohmic Discharge Assisted with RF Power in QUEST Spherical Tokamak

Osamu MITARAI, Kazuo NAKAMURA, Saya TASHIMA, Makoto HASEGAWA, Hiroshi IDEI, Mizuki SAKAMOTO, Kazuaki HANADA, Hideki ZUSHI, Kohnosuke SATO, Masaki ISHIGURO, Hai Qing LIU, Yuta HIGASHIZONO, Aki HIGASHIJIMA, Hisatoshi NAKASHIMA, Shoji KAWASAKI, Yuichi TAKASE, Takashi MAEKAWA, Nobuhiro NISHINO

Author information

Osamu MITARAI
Liberal Arts Education Center, Kumamoto Campus, Tokai University, 9-1-1 Toroku, Kumamoto 862-8652, Japan
Kazuo NAKAMURA
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Saya TASHIMA
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Makoto HASEGAWA
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Hiroshi IDEI
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Mizuki SAKAMOTO
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Kazuaki HANADA
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Hideki ZUSHI
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Kohnosuke SATO
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Masaki ISHIGURO
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Hai Qing LIU
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Yuta HIGASHIZONO
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Aki HIGASHIJIMA
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Hisatoshi NAKASHIMA
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Shoji KAWASAKI
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan
Yuichi TAKASE
Graduate School of Frontier Sciences and Graduate School of Science, University of Tokyo, Kashiwa 277-85611, Japan
Takashi MAEKAWA
Graduate School of Energy Science, Kyoto University, Kyoto 606-8502, Japan
Nobuhiro NISHINO
Department of Engineering, Hiroshima Univeristy, Higashi-Hiroshima 739-8527, Japan

Keywords: spherical tokamak, current start-up, ohmic clamp, cancellation coil, ECW, vertical field

JOURNAL FREE ACCESS

2011 Volume 6 Pages 1402003

DOI https://doi.org/10.1585/pfr.6.1402003

Details

Abstract

Ohmic plasma currents of up to 17 kA with a discharge duration of 0.32 s have been obtained in the Kyushu University Experiment with Steady-State Spherical Tokamak (QUEST) with the help of electron cyclotron wave (ECW) and cancellation coils (CCs). The CCs, originally installed to create a field null in the plasma breakdown phase, are essential for producing plasma current in QUEST. Although the ohmic coil current is initially biased and then reduced completely to zero to induce the plasma current in 15-20 ms, we demonstrate that the flat top of the plasma current exceeding 20 ms is maintained by the vertical field after the ohmic current is switched off. This type of operation is quite favorable for extending pulsed operation to the steady state by electron Bernstein wave current drive (EBCD).

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