Demonstration of transient CHI startup using a floating biased electrode configuration

Kuroda, K. (ORCID:0000000324514893); Raman, R. (ORCID:0000000220273271); Onchi, T.; Hasegawa, M.; Hanada, K.; Ono, M. (ORCID:0000000198499417); Nelson, B. A.; Rogers, J.; Ikezoe, R. (ORCID:0000000326151256); Idei, H. (ORCID:0000000162824521); Ido, T. (ORCID:0000000310982565); Nagata, M.; Mitarai, O.; Nishino, N.; Otsuka, Y.; Zhang, Y.; Kono, K.; Kawasaki, S.; Nagata, T.; Higashijima, A.; Shimabukuro, S.; Niiya, I.; Sekiya, I.; Nakamura, K.; Takase, Y. (ORCID:0000000248465267); Ejiri, A.; Murakami, S. (ORCID:0000000225267137)

doi:10.1088/1741-4326/ad0dd6

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Demonstration of transient CHI startup using a floating biased electrode configuration

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Abstract

Abstract Results from the successful solenoid-free plasma startup using the method of transient coaxial helicity injection (transient CHI) in the QUEST spherical tokamak (ST) are reported. Unlike previous applications of CHI on HIT-II and on NSTX which required two toroidal insulating breaks to the vacuum vessel, QUEST uses a first of its kind, floating single biased electrode configuration, which does not use such a vacuum break. Instead, the CHI electrode is simply insulated from the outer lower divertor plate support structure. This configuration is much more suitable for implementation in a fusion reactor than the previous configurations. Transient CHI generated toroidal currents of 135 kA were obtained. The toroidal current during the formation of a closed flux configuration was over 50 kA. These results bode well for the application of transient CHI in a new generation of compact high-field STs and tokamaks in which the space for the central solenoid is very restricted.

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70 PLASMA PHYSICS AND FUSION TECHNOLOGY coaxial helicity injection solenoid-free current drive spherical tokamak

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Kuroda, K. (ORCID:0000000324514893), Raman, R. (ORCID:0000000220273271), Onchi, T., Hasegawa, M., Hanada, K., Ono, M. (ORCID:0000000198499417), Nelson, B. A., Rogers, J., Ikezoe, R. (ORCID:0000000326151256), Idei, H. (ORCID:0000000162824521), Ido, T. (ORCID:0000000310982565), Nagata, M., Mitarai, O., Nishino, N., Otsuka, Y., Zhang, Y., Kono, K., Kawasaki, S., Nagata, T., Higashijima, A., Shimabukuro, S., Niiya, I., Sekiya, I., Nakamura, K., Takase, Y. (ORCID:0000000248465267), Ejiri, A., Murakami, S. (ORCID:0000000225267137). 2023-12-01. Demonstration of transient CHI startup using a floating biased electrode configuration. https://doi.org/10.1088/1741-4326%2Fad0dd6

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