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

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


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).

Original languageEnglish
Article number1402003
JournalPlasma and Fusion Research
Issue number2011
Publication statusPublished - 2011

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics


Dive into the research topics of 'First ohmic discharge assisted with RF power in QUEST spherical tokamak'. Together they form a unique fingerprint.

Cite this