TY - JOUR
T1 - Designing an upgrade of ohmic heating system for the QUEST spherical tokamak
AU - Zhang, Yifan
AU - Onchi, Takumi
AU - Nakamura, Kazuo
AU - Kidani, Akihiro
AU - Yue, Qilin
AU - Kuroda, Kengoh
AU - Hasegawa, Makoto
AU - Ikezoe, Ryuya
AU - Idei, Hiroshi
N1 - Funding Information:
This work was supported by the NIFS Bilateral Collaboration Research Program ( NIFS19KUTR136 , NIFS15KUTR111 and NIFS17KERA013 ) and Collaborative Research Program of the RIAM in Kyushu University .
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/7
Y1 - 2021/7
N2 - 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.
AB - 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.
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U2 - 10.1016/j.fusengdes.2021.112362
DO - 10.1016/j.fusengdes.2021.112362
M3 - Article
AN - SCOPUS:85101777348
SN - 0920-3796
VL - 168
JO - Fusion Engineering and Design
JF - Fusion Engineering and Design
M1 - 112362
ER -