Plasma curent start-up experiment using waves in the lower hybrid frequency range in TST-2

Y. Takase, T. Wakatsuki, A. Ejiri, H. Kakuda, C. P. Moeller, T. Ambo, K. Hanashima, J. Hiratsuka, H. Kasahara, R. Kumazawa, Y. Nagashima, K. Saito, T. Sakamoto, T. Seki, F. Shimpo, R. Shino, M. Sonehara, O. Watanabe, T. Yamaguchi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Noninductive plasma current (I p) start-up experiments using RF power in the lower hybrid frequency range are being conducted on the TST-2 spherical tokamak. The lower hybrid wave (LHW) has demonstrated efficient current drive in conventional tokamaks. However, in spherical tokamak (ST) plasmas with very high dielectric constants (ε∼ω pe 2/Ω| e 2≫1), accessibility of the LHW to the plasma core is severely limited. Our approach is to keep the plasma density low (such that ε∼1) during I p ramp-up. Once I p reaches a level sufficiently high for neutral beam current drive, plasma can be densified and transformed into an advanced tokamak plasma dominated by the self-driven bootstrap current. Initial plasma start-up experiments were performed on TST-2 using a combline antenna which excites a traveling fast wave. After formation of toroidal flux surfaces, RF power and vertical field were ramped up to increase I p. Up to 12 kA of Ip has been obtained by this method. Soft X-ray measurements indicate that the electron temperature increases as I p increases, and hard X-ray spectroscopy indicates that energetic electrons build up as I p is ramped up.

Original languageEnglish
Title of host publicationRadio Frequency Power in Plasmas - Proceedings of the 19th Topical Conference
Pages427-430
Number of pages4
DOIs
Publication statusPublished - Dec 1 2011
Externally publishedYes
Event19th Topical Conference on Radio Frequency Power in Plasmas - Newport, RI, United States
Duration: Jun 1 2011Jul 3 2011

Publication series

NameAIP Conference Proceedings
Volume1406
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other19th Topical Conference on Radio Frequency Power in Plasmas
CountryUnited States
CityNewport, RI
Period6/1/117/3/11

Fingerprint

frequency ranges
plasma currents
neutral beams
ramps
beam currents
plasma density
x rays
antennas
electron energy
permittivity
spectroscopy
electrons

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Takase, Y., Wakatsuki, T., Ejiri, A., Kakuda, H., Moeller, C. P., Ambo, T., ... Yamaguchi, T. (2011). Plasma curent start-up experiment using waves in the lower hybrid frequency range in TST-2. In Radio Frequency Power in Plasmas - Proceedings of the 19th Topical Conference (pp. 427-430). (AIP Conference Proceedings; Vol. 1406). https://doi.org/10.1063/1.3665007

Plasma curent start-up experiment using waves in the lower hybrid frequency range in TST-2. / Takase, Y.; Wakatsuki, T.; Ejiri, A.; Kakuda, H.; Moeller, C. P.; Ambo, T.; Hanashima, K.; Hiratsuka, J.; Kasahara, H.; Kumazawa, R.; Nagashima, Y.; Saito, K.; Sakamoto, T.; Seki, T.; Shimpo, F.; Shino, R.; Sonehara, M.; Watanabe, O.; Yamaguchi, T.

Radio Frequency Power in Plasmas - Proceedings of the 19th Topical Conference. 2011. p. 427-430 (AIP Conference Proceedings; Vol. 1406).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Takase, Y, Wakatsuki, T, Ejiri, A, Kakuda, H, Moeller, CP, Ambo, T, Hanashima, K, Hiratsuka, J, Kasahara, H, Kumazawa, R, Nagashima, Y, Saito, K, Sakamoto, T, Seki, T, Shimpo, F, Shino, R, Sonehara, M, Watanabe, O & Yamaguchi, T 2011, Plasma curent start-up experiment using waves in the lower hybrid frequency range in TST-2. in Radio Frequency Power in Plasmas - Proceedings of the 19th Topical Conference. AIP Conference Proceedings, vol. 1406, pp. 427-430, 19th Topical Conference on Radio Frequency Power in Plasmas, Newport, RI, United States, 6/1/11. https://doi.org/10.1063/1.3665007
Takase Y, Wakatsuki T, Ejiri A, Kakuda H, Moeller CP, Ambo T et al. Plasma curent start-up experiment using waves in the lower hybrid frequency range in TST-2. In Radio Frequency Power in Plasmas - Proceedings of the 19th Topical Conference. 2011. p. 427-430. (AIP Conference Proceedings). https://doi.org/10.1063/1.3665007
Takase, Y. ; Wakatsuki, T. ; Ejiri, A. ; Kakuda, H. ; Moeller, C. P. ; Ambo, T. ; Hanashima, K. ; Hiratsuka, J. ; Kasahara, H. ; Kumazawa, R. ; Nagashima, Y. ; Saito, K. ; Sakamoto, T. ; Seki, T. ; Shimpo, F. ; Shino, R. ; Sonehara, M. ; Watanabe, O. ; Yamaguchi, T. / Plasma curent start-up experiment using waves in the lower hybrid frequency range in TST-2. Radio Frequency Power in Plasmas - Proceedings of the 19th Topical Conference. 2011. pp. 427-430 (AIP Conference Proceedings).
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