Designing an upgrade of ohmic heating system for the QUEST spherical tokamak

Yifan Zhang, Takumi Onchi, Kazuo Nakamura, Akihiro Kidani, Qilin Yue, Kengoh Kuroda, Makoto Hasegawa, Ryuya Ikezoe, Hiroshi Idei

Research output: Contribution to journalArticlepeer-review

Abstract

An upgraded Ohmic heating (OH) system with a bipolar circuit is designed to achieve plasma current over 100 kA ideally without the effect of eddy current in the QUEST spherical tokamak. IGBT (Insulated Gate Bipolar Transistor) stacks work as switches to change the polarity of OH primary current up to ±8 kA. A main target of the new OH is to generate over-dense plasmas for the 8.56 GHz electron cyclotron (EC) wave. Heating with electron Bernstein waves can be conducted in such over-dense plasmas. The effect of eddy current flowing in the vacuum vessel, which is generated by the current swing through the central solenoid, on null point is investigated by analysis of magnetic field and flux surfaces. In the initial phase, eddy current flowing through the vacuum chamber shifts the null point to the high magnetic field side where multiple EC resonance layers are located.

Original languageEnglish
Article number112362
JournalFusion Engineering and Design
Volume168
DOIs
Publication statusPublished - Jul 2021
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Mechanical Engineering

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