Sudden Change Events of Plasma Current during Electron-Cyclotron Current Start-Up on the QUEST Spherical Tokamak

DOI Web Site 8 References Open Access
  • IKEZOE Ryuya
    Research Institute for Applied Mechanics, Kyushu University
  • TAKEDA Kosuke
    Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
  • KURODA Kengoh
    Research Institute for Applied Mechanics, Kyushu University
  • ONCHI Takumi
    Research Institute for Applied Mechanics, Kyushu University
  • NAGATA Takahiro
    Research Institute for Applied Mechanics, Kyushu University
  • SEKIYA Izumi
    Research Institute for Applied Mechanics, Kyushu University
  • IDEI Hiroshi
    Research Institute for Applied Mechanics, Kyushu University
  • ZENNIFA Fadilla
    Research Institute for Applied Mechanics, Kyushu University
  • ZHANG Yifan
    Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
  • SAKAI Seiya
    Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
  • MIYATA Rikuya
    Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
  • YAMAGUCHI Takahiro
    Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
  • HASEGAWA Makoto
    Research Institute for Applied Mechanics, Kyushu University
  • NAGASHIMA Yoshihiko
    Research Institute for Applied Mechanics, Kyushu University
  • IDO Takeshi
    Research Institute for Applied Mechanics, Kyushu University
  • HANADA Kazuaki
    Research Institute for Applied Mechanics, Kyushu University

Description

<p>Non-inductive plasma current start-up experiments have been conducted using 2nd harmonic electron-cyclotron resonance heating (ECRH) on the QUEST spherical tokamak. Sudden or abrupt changes in plasma current, referred to as sudden change events (SCEs), have been frequently observed during these experiments. To investigate these events, fast magnetic activity was measured globally by installing arrays of magnetic pick-up coils inside the vacuum vessel on QUEST. Analysis revealed that all observed SCEs could be classified into three categories based on their magnetic characteristics. In one type of event, called SCE–III, the plasma current suddenly decreases by up to 50% instantaneously, occurring in a wide discharge region achieved using 2nd ECRH start-up on QUEST. These SCE–III events may potentially lead to disruptions in future discharges at higher powers.</p>

Journal

  • Plasma and Fusion Research

    Plasma and Fusion Research 18 (0), 2402066-2402066, 2023-08-02

    The Japan Society of Plasma Science and Nuclear Fusion Research

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