Initial Results from High-Field-Side Transient CHI Start-Up on Quest

Kengoh Kuroda; Roger Raman; Makoto Hasegawa; Takumi Onchi; Brian A. Nelson; John Rogers; Osamu Mitarai; Kazuaki Hanada; Masayuki Ono; Thomas Jarboe; Masayoshi Nagata; Hiroshi Idei; Takeshi Ido; Ryuya Ikezoe; Shoji Kawasaki; Takahiro Nagata; Aki Higashijima; Shun Shimabukuro; Ichiro Niiya; Shinichiro Kojima; Akihiro Kidani; Takahiro Murakami; Kazuo Nakamura; Yuichi Takase; Sadayoshi Murakami

doi:10.1585/pfr.16.2402048

Initial Results from High-Field-Side Transient CHI Start-Up on Quest

Kengoh Kuroda, Roger Raman, Makoto Hasegawa, Takumi Onchi, Brian A. Nelson, John Rogers, Osamu Mitarai, Kazuaki Hanada, Masayuki Ono, Thomas Jarboe, Masayoshi Nagata, Hiroshi Idei, Takeshi Ido, Ryuya Ikezoe, Shoji Kawasaki, Takahiro Nagata, Aki Higashijima, Shun Shimabukuro, Ichiro Niiya, Shinichiro KojimaAkihiro Kidani, Takahiro Murakami, Kazuo Nakamura, Yuichi Takase, Sadayoshi Murakami

Research output: Contribution to journal › Article › peer-review

2 Citations (Scopus)

Abstract

Transient coaxial helicity injection (t-CHI) current start-up using a new design simple electrode configuration has been implemented on the QUEST. Discharges injected from the low field side (LFS) and from the high field side (HFS) were examined. Compared to the LFS injection case, the HFS injection has the advantages of providing access to a higher toroidal field and better controlling the location of the injector flux footprint location. Although the present PF coils on QUEST are not well positioned to form the injector flux on the HFS injector region and there has been a frequent occurrence of the spurious arcs, known as absorber arcs, HFS injection has shown flux evolution in a shape that is suitable for the formation of closed flux surfaces. The discharges were improved by installing an in-vessel-coil and adding a new cylindrical electrode to the existing CHI electrode. The results show that the new cylindrical electrode allowed the flux to evolve stably while allowing both the inner and the outer injector flux footprint to remain in the vicinity of the cylindrical electrode. This configuration which inherently generates a narrow injector flux footprint width resulted in discharges that strongly suggested the persistence of the CHI generated plasma after the injector current was reduced to zero. These studies have informed us of the need to improve the CHI gas injection system so that the absorber arcs could be better controlled in the HFS injection configuration.

Original language	English
Pages (from-to)	1-5
Number of pages	5
Journal	Plasma and Fusion Research
Volume	16
DOIs	https://doi.org/10.1585/pfr.16.2402048
Publication status	Published - 2021

All Science Journal Classification (ASJC) codes

Condensed Matter Physics

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10.1585/pfr.16.2402048

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Kuroda, K., Raman, R., Hasegawa, M., Onchi, T., Nelson, B. A., Rogers, J., Mitarai, O., Hanada, K., Ono, M., Jarboe, T., Nagata, M., Idei, H., Ido, T., Ikezoe, R., Kawasaki, S., Nagata, T., Higashijima, A., Shimabukuro, S., Niiya, I., ... Murakami, S. (2021). Initial Results from High-Field-Side Transient CHI Start-Up on Quest. Plasma and Fusion Research, 16, 1-5. https://doi.org/10.1585/pfr.16.2402048

Kuroda, K, Raman, R, Hasegawa, M , Onchi, T, Nelson, BA, Rogers, J, Mitarai, O, Hanada, K, Ono, M, Jarboe, T, Nagata, M, Idei, H , Ido, T , Ikezoe, R, Kawasaki, S, Nagata, T, Higashijima, A, Shimabukuro, S, Niiya, I, Kojima, S, Kidani, A, Murakami, T, Nakamura, K, Takase, Y & Murakami, S 2021, 'Initial Results from High-Field-Side Transient CHI Start-Up on Quest', Plasma and Fusion Research, vol. 16, pp. 1-5. https://doi.org/10.1585/pfr.16.2402048

@article{ccff61eef296468ea3d8c818e75d4219,

title = "Initial Results from High-Field-Side Transient CHI Start-Up on Quest",

abstract = "Transient coaxial helicity injection (t-CHI) current start-up using a new design simple electrode configuration has been implemented on the QUEST. Discharges injected from the low field side (LFS) and from the high field side (HFS) were examined. Compared to the LFS injection case, the HFS injection has the advantages of providing access to a higher toroidal field and better controlling the location of the injector flux footprint location. Although the present PF coils on QUEST are not well positioned to form the injector flux on the HFS injector region and there has been a frequent occurrence of the spurious arcs, known as absorber arcs, HFS injection has shown flux evolution in a shape that is suitable for the formation of closed flux surfaces. The discharges were improved by installing an in-vessel-coil and adding a new cylindrical electrode to the existing CHI electrode. The results show that the new cylindrical electrode allowed the flux to evolve stably while allowing both the inner and the outer injector flux footprint to remain in the vicinity of the cylindrical electrode. This configuration which inherently generates a narrow injector flux footprint width resulted in discharges that strongly suggested the persistence of the CHI generated plasma after the injector current was reduced to zero. These studies have informed us of the need to improve the CHI gas injection system so that the absorber arcs could be better controlled in the HFS injection configuration.",

author = "Kengoh Kuroda and Roger Raman and Makoto Hasegawa and Takumi Onchi and Nelson, {Brian A.} and John Rogers and Osamu Mitarai and Kazuaki Hanada and Masayuki Ono and Thomas Jarboe and Masayoshi Nagata and Hiroshi Idei and Takeshi Ido and Ryuya Ikezoe and Shoji Kawasaki and Takahiro Nagata and Aki Higashijima and Shun Shimabukuro and Ichiro Niiya and Shinichiro Kojima and Akihiro Kidani and Takahiro Murakami and Kazuo Nakamura and Yuichi Takase and Sadayoshi Murakami",

note = "Funding Information: This work is supported by US DOE grants (DESC0019415, and DE-AC02-09CH11466), NIFS Collaboration Research Program (NIFS17KUTR130 and NIFS19KUTR137), the Collaborative Research Program of Research Institute for Applied Mechanics, Kyushu University (international collaboration frame work 18 NU-1 and 19 NU-1 and early career scientists support work) and a Grant-in-Aid for JSPS Fellows (KAKENHI Grant Number 19K14685). This work was partially supported by a Grant-in-Aid for JSPS Fellows (KAKENHI Grant Number 17H06089), the NIFS Collaboration Research Program (NIFS19KUTR136, NIFS13KUTR085) and Japan / U. S. Cooperation in Fusion Research and Development. Publisher Copyright: {\textcopyright} 2021 The Japan Society of Plasma Science and Nuclear Fusion Research",

year = "2021",

doi = "10.1585/pfr.16.2402048",

language = "English",

volume = "16",

pages = "1--5",

journal = "Plasma and Fusion Research",

issn = "1880-6821",

publisher = "The Japan Society of Plasma Science and Nuclear Fusion Research (JSPF)",

}

TY - JOUR

T1 - Initial Results from High-Field-Side Transient CHI Start-Up on Quest

AU - Kuroda, Kengoh

AU - Raman, Roger

AU - Hasegawa, Makoto

AU - Onchi, Takumi

AU - Nelson, Brian A.

AU - Rogers, John

AU - Mitarai, Osamu

AU - Hanada, Kazuaki

AU - Ono, Masayuki

AU - Jarboe, Thomas

AU - Nagata, Masayoshi

AU - Idei, Hiroshi

AU - Ido, Takeshi

AU - Ikezoe, Ryuya

AU - Kawasaki, Shoji

AU - Nagata, Takahiro

AU - Higashijima, Aki

AU - Shimabukuro, Shun

AU - Niiya, Ichiro

AU - Kojima, Shinichiro

AU - Kidani, Akihiro

AU - Murakami, Takahiro

AU - Nakamura, Kazuo

AU - Takase, Yuichi

AU - Murakami, Sadayoshi

N1 - Funding Information: This work is supported by US DOE grants (DESC0019415, and DE-AC02-09CH11466), NIFS Collaboration Research Program (NIFS17KUTR130 and NIFS19KUTR137), the Collaborative Research Program of Research Institute for Applied Mechanics, Kyushu University (international collaboration frame work 18 NU-1 and 19 NU-1 and early career scientists support work) and a Grant-in-Aid for JSPS Fellows (KAKENHI Grant Number 19K14685). This work was partially supported by a Grant-in-Aid for JSPS Fellows (KAKENHI Grant Number 17H06089), the NIFS Collaboration Research Program (NIFS19KUTR136, NIFS13KUTR085) and Japan / U. S. Cooperation in Fusion Research and Development. Publisher Copyright: © 2021 The Japan Society of Plasma Science and Nuclear Fusion Research

PY - 2021

Y1 - 2021

N2 - Transient coaxial helicity injection (t-CHI) current start-up using a new design simple electrode configuration has been implemented on the QUEST. Discharges injected from the low field side (LFS) and from the high field side (HFS) were examined. Compared to the LFS injection case, the HFS injection has the advantages of providing access to a higher toroidal field and better controlling the location of the injector flux footprint location. Although the present PF coils on QUEST are not well positioned to form the injector flux on the HFS injector region and there has been a frequent occurrence of the spurious arcs, known as absorber arcs, HFS injection has shown flux evolution in a shape that is suitable for the formation of closed flux surfaces. The discharges were improved by installing an in-vessel-coil and adding a new cylindrical electrode to the existing CHI electrode. The results show that the new cylindrical electrode allowed the flux to evolve stably while allowing both the inner and the outer injector flux footprint to remain in the vicinity of the cylindrical electrode. This configuration which inherently generates a narrow injector flux footprint width resulted in discharges that strongly suggested the persistence of the CHI generated plasma after the injector current was reduced to zero. These studies have informed us of the need to improve the CHI gas injection system so that the absorber arcs could be better controlled in the HFS injection configuration.

AB - Transient coaxial helicity injection (t-CHI) current start-up using a new design simple electrode configuration has been implemented on the QUEST. Discharges injected from the low field side (LFS) and from the high field side (HFS) were examined. Compared to the LFS injection case, the HFS injection has the advantages of providing access to a higher toroidal field and better controlling the location of the injector flux footprint location. Although the present PF coils on QUEST are not well positioned to form the injector flux on the HFS injector region and there has been a frequent occurrence of the spurious arcs, known as absorber arcs, HFS injection has shown flux evolution in a shape that is suitable for the formation of closed flux surfaces. The discharges were improved by installing an in-vessel-coil and adding a new cylindrical electrode to the existing CHI electrode. The results show that the new cylindrical electrode allowed the flux to evolve stably while allowing both the inner and the outer injector flux footprint to remain in the vicinity of the cylindrical electrode. This configuration which inherently generates a narrow injector flux footprint width resulted in discharges that strongly suggested the persistence of the CHI generated plasma after the injector current was reduced to zero. These studies have informed us of the need to improve the CHI gas injection system so that the absorber arcs could be better controlled in the HFS injection configuration.

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U2 - 10.1585/pfr.16.2402048

DO - 10.1585/pfr.16.2402048

M3 - Article

AN - SCOPUS:85112609124

SN - 1880-6821

VL - 16

SP - 1

EP - 5

JO - Plasma and Fusion Research

JF - Plasma and Fusion Research

ER -

Initial Results from High-Field-Side Transient CHI Start-Up on Quest

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