Demonstration of transient CHI startup using a floating biased electrode configuration

K. Kuroda; R. Raman; T. Onchi; M. Hasegawa; K. Hanada; M. Ono; B. A. Nelson; J. Rogers; R. Ikezoe; H. Idei; T. Ido; M. Nagata; O. Mitarai; N. Nishino; Y. Otsuka; Y. Zhang; K. Kono; S. Kawasaki; T. Nagata; A. Higashijima; S. Shimabukuro; I. Niiya; I. Sekiya; K. Nakamura; Y. Takase; A. Ejiri; S. Murakami

doi:10.1088/1741-4326/ad0dd6

Demonstration of transient CHI startup using a floating biased electrode configuration

K. Kuroda, R. Raman, T. Onchi, M. Hasegawa, K. Hanada, M. Ono, B. A. Nelson, J. Rogers, R. Ikezoe, H. Idei, T. Ido, M. Nagata, O. Mitarai, N. Nishino, Y. Otsuka, Y. Zhang, K. Kono, S. Kawasaki, T. Nagata, A. HigashijimaS. Shimabukuro, I. Niiya, I. Sekiya, K. Nakamura, Y. Takase, A. Ejiri, S. Murakami

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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.

Original language	English
Article number	014002
Journal	Nuclear Fusion
Volume	64
Issue number	1
DOIs	https://doi.org/10.1088/1741-4326/ad0dd6
Publication status	Published - Jan 2024
Externally published	Yes

All Science Journal Classification (ASJC) codes

Nuclear and High Energy Physics
Condensed Matter Physics

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10.1088/1741-4326/ad0dd6

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Kuroda, K., Raman, R., Onchi, T., Hasegawa, M., Hanada, K., Ono, M., Nelson, B. A., Rogers, J., Ikezoe, R., Idei, H., Ido, T., Nagata, M., Mitarai, O., Nishino, N., Otsuka, Y., Zhang, Y., Kono, K., Kawasaki, S., Nagata, T., ... Murakami, S. (2024). Demonstration of transient CHI startup using a floating biased electrode configuration. Nuclear Fusion, 64(1), Article 014002. https://doi.org/10.1088/1741-4326/ad0dd6

Kuroda, K, Raman, R, Onchi, T , Hasegawa, M , Hanada, K, Ono, M, Nelson, BA, Rogers, J, Ikezoe, R , Idei, H , Ido, T, 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, Ejiri, A & Murakami, S 2024, 'Demonstration of transient CHI startup using a floating biased electrode configuration', Nuclear Fusion, vol. 64, no. 1, 014002. https://doi.org/10.1088/1741-4326/ad0dd6

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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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author = "K. Kuroda and R. Raman and T. Onchi and M. Hasegawa and K. Hanada and M. Ono and Nelson, {B. A.} and J. Rogers and R. Ikezoe and H. Idei and T. Ido and M. Nagata and O. Mitarai and N. Nishino and Y. Otsuka and Y. Zhang and K. Kono and S. Kawasaki and T. Nagata and A. Higashijima and S. Shimabukuro and I. Niiya and I. Sekiya and K. Nakamura and Y. Takase and A. Ejiri and S. Murakami",

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AU - Kuroda, K.

AU - Raman, R.

AU - Onchi, T.

AU - Hasegawa, M.

AU - Hanada, K.

AU - Ono, M.

AU - Nelson, B. A.

AU - Rogers, J.

AU - Ikezoe, R.

AU - Idei, H.

AU - Ido, T.

AU - Nagata, M.

AU - Mitarai, O.

AU - Nishino, N.

AU - Otsuka, Y.

AU - Zhang, Y.

AU - Kono, K.

AU - Kawasaki, S.

AU - Nagata, T.

AU - Higashijima, A.

AU - Shimabukuro, S.

AU - Niiya, I.

AU - Sekiya, I.

AU - Nakamura, K.

AU - Takase, Y.

AU - Ejiri, A.

AU - Murakami, S.

PY - 2024/1

Y1 - 2024/1

N2 - 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.

AB - 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.

KW - coaxial helicity injection

KW - solenoid-free current drive

KW - spherical tokamak

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Demonstration of transient CHI startup using a floating biased electrode configuration

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