Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2

T. Wakatsuki; A. Ejiri; T. Shinya; Y. Takase; H. Furui; J. Hiratsuka; K. Imamura; T. Inada; H. Kakuda; H. Kasahara; Y. Nagashima; K. Nakamura; A. Nakanishi; T. Oosako; K. Saito; T. Seki; F. Shimpo; M. Sonehara; H. Togashi; S. Tsuda; N. Tsujii; T. Yamaguchi

doi:10.1063/1.4864578

Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2

T. Wakatsuki, A. Ejiri, T. Shinya, Y. Takase, H. Furui, J. Hiratsuka, K. Imamura, T. Inada, H. Kakuda, H. Kasahara, Y. Nagashima, K. Nakamura, A. Nakanishi, T. Oosako, K. Saito, T. Seki, F. Shimpo, M. Sonehara, H. Togashi, S. TsudaN. Tsujii, T. Yamaguchi

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

1 Citation (Scopus)

Abstract

Lower hybrid current drive experiments were performed on the TST-2 spherical tokamak (R = 0.38 m, a = 0.25 m, B_t = 0.3 T, I_p = 0.1 MA). A waveguide array antenna consisting of four dielectric (alumina, ε_r = 10.0) loaded waveguides was used. The coupling characteristics were investigated over a wide range of input power (0.1 W - 40 kW). The reflection coefficient of this antenna increased when the input power exceeded approximately 1 kW. This result was compared with a numerical simulation based on the finite element method (FEM). The ponderomotive effect was calculated for the wave field calculated by COMSOL [1]. This calculation also showed variation of the reflection coefficient with the input power. Non-inductive plasma current start-up to 10 kA was demonstrated using 40 kW of lower hybrid wave (LHW) power. The current drive figure of merit (η_CD=I_pn_eR/P_RF) of this antenna was higher than that obtained using the combline antenna, which is designed to excite a travelling fast wave. The best current drive efficiency was obtained in the case in which the n_∥ (= ck_∥/ω) spectrum of the excited LHW was peaked around 9 and the toroidal field was higher than in previous experiments.

Original language	English
Title of host publication	Radiofrequency Power in Plasmas - Proceedings of the 20th Topical Conference
Publisher	American Institute of Physics Inc.
Pages	422-425
Number of pages	4
ISBN (Print)	9780735412101
DOIs	https://doi.org/10.1063/1.4864578
Publication status	Published - 2014
Event	20th Topical Conference on Radiofrequency Power in Plasmas - Sorrento, Italy Duration: Jun 25 2013 → Jun 28 2013

Publication series

Name	AIP Conference Proceedings
Volume	1580
ISSN (Print)	0094-243X
ISSN (Electronic)	1551-7616

Other

Other	20th Topical Conference on Radiofrequency Power in Plasmas
Country/Territory	Italy
City	Sorrento
Period	6/25/13 → 6/28/13

All Science Journal Classification (ASJC) codes

Physics and Astronomy(all)

Access to Document

10.1063/1.4864578

Cite this

Wakatsuki, T., Ejiri, A., Shinya, T., Takase, Y., Furui, H., Hiratsuka, J., Imamura, K., Inada, T., Kakuda, H., Kasahara, H., Nagashima, Y., Nakamura, K., Nakanishi, A., Oosako, T., Saito, K., Seki, T., Shimpo, F., Sonehara, M., Togashi, H., ... Yamaguchi, T. (2014). Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2. In Radiofrequency Power in Plasmas - Proceedings of the 20th Topical Conference (pp. 422-425). (AIP Conference Proceedings; Vol. 1580). American Institute of Physics Inc.. https://doi.org/10.1063/1.4864578

Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2. / Wakatsuki, T.; Ejiri, A.; Shinya, T. et al.
Radiofrequency Power in Plasmas - Proceedings of the 20th Topical Conference. American Institute of Physics Inc., 2014. p. 422-425 (AIP Conference Proceedings; Vol. 1580).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Wakatsuki, T, Ejiri, A, Shinya, T, Takase, Y, Furui, H, Hiratsuka, J, Imamura, K, Inada, T, Kakuda, H, Kasahara, H, Nagashima, Y, Nakamura, K, Nakanishi, A, Oosako, T, Saito, K, Seki, T, Shimpo, F, Sonehara, M, Togashi, H, Tsuda, S, Tsujii, N & Yamaguchi, T 2014, Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2. in Radiofrequency Power in Plasmas - Proceedings of the 20th Topical Conference. AIP Conference Proceedings, vol. 1580, American Institute of Physics Inc., pp. 422-425, 20th Topical Conference on Radiofrequency Power in Plasmas, Sorrento, Italy, 6/25/13. https://doi.org/10.1063/1.4864578

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title = "Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2",

abstract = "Lower hybrid current drive experiments were performed on the TST-2 spherical tokamak (R = 0.38 m, a = 0.25 m, Bt = 0.3 T, Ip = 0.1 MA). A waveguide array antenna consisting of four dielectric (alumina, εr = 10.0) loaded waveguides was used. The coupling characteristics were investigated over a wide range of input power (0.1 W - 40 kW). The reflection coefficient of this antenna increased when the input power exceeded approximately 1 kW. This result was compared with a numerical simulation based on the finite element method (FEM). The ponderomotive effect was calculated for the wave field calculated by COMSOL [1]. This calculation also showed variation of the reflection coefficient with the input power. Non-inductive plasma current start-up to 10 kA was demonstrated using 40 kW of lower hybrid wave (LHW) power. The current drive figure of merit (ηCD=IpneR/PRF) of this antenna was higher than that obtained using the combline antenna, which is designed to excite a travelling fast wave. The best current drive efficiency was obtained in the case in which the n∥ (= ck∥/ω) spectrum of the excited LHW was peaked around 9 and the toroidal field was higher than in previous experiments.",

author = "T. Wakatsuki and A. Ejiri and T. Shinya and Y. Takase and H. Furui and J. Hiratsuka and K. Imamura and T. Inada and H. Kakuda and H. Kasahara and Y. Nagashima and K. Nakamura and A. Nakanishi and T. Oosako and K. Saito and T. Seki and F. Shimpo and M. Sonehara and H. Togashi and S. Tsuda and N. Tsujii and T. Yamaguchi",

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doi = "10.1063/1.4864578",

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publisher = "American Institute of Physics Inc.",

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AU - Wakatsuki, T.

AU - Ejiri, A.

AU - Shinya, T.

AU - Takase, Y.

AU - Furui, H.

AU - Hiratsuka, J.

AU - Imamura, K.

AU - Inada, T.

AU - Kakuda, H.

AU - Kasahara, H.

AU - Nagashima, Y.

AU - Nakamura, K.

AU - Nakanishi, A.

AU - Oosako, T.

AU - Saito, K.

AU - Seki, T.

AU - Shimpo, F.

AU - Sonehara, M.

AU - Togashi, H.

AU - Tsuda, S.

AU - Tsujii, N.

AU - Yamaguchi, T.

PY - 2014

Y1 - 2014

N2 - Lower hybrid current drive experiments were performed on the TST-2 spherical tokamak (R = 0.38 m, a = 0.25 m, Bt = 0.3 T, Ip = 0.1 MA). A waveguide array antenna consisting of four dielectric (alumina, εr = 10.0) loaded waveguides was used. The coupling characteristics were investigated over a wide range of input power (0.1 W - 40 kW). The reflection coefficient of this antenna increased when the input power exceeded approximately 1 kW. This result was compared with a numerical simulation based on the finite element method (FEM). The ponderomotive effect was calculated for the wave field calculated by COMSOL [1]. This calculation also showed variation of the reflection coefficient with the input power. Non-inductive plasma current start-up to 10 kA was demonstrated using 40 kW of lower hybrid wave (LHW) power. The current drive figure of merit (ηCD=IpneR/PRF) of this antenna was higher than that obtained using the combline antenna, which is designed to excite a travelling fast wave. The best current drive efficiency was obtained in the case in which the n∥ (= ck∥/ω) spectrum of the excited LHW was peaked around 9 and the toroidal field was higher than in previous experiments.

AB - Lower hybrid current drive experiments were performed on the TST-2 spherical tokamak (R = 0.38 m, a = 0.25 m, Bt = 0.3 T, Ip = 0.1 MA). A waveguide array antenna consisting of four dielectric (alumina, εr = 10.0) loaded waveguides was used. The coupling characteristics were investigated over a wide range of input power (0.1 W - 40 kW). The reflection coefficient of this antenna increased when the input power exceeded approximately 1 kW. This result was compared with a numerical simulation based on the finite element method (FEM). The ponderomotive effect was calculated for the wave field calculated by COMSOL [1]. This calculation also showed variation of the reflection coefficient with the input power. Non-inductive plasma current start-up to 10 kA was demonstrated using 40 kW of lower hybrid wave (LHW) power. The current drive figure of merit (ηCD=IpneR/PRF) of this antenna was higher than that obtained using the combline antenna, which is designed to excite a travelling fast wave. The best current drive efficiency was obtained in the case in which the n∥ (= ck∥/ω) spectrum of the excited LHW was peaked around 9 and the toroidal field was higher than in previous experiments.

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BT - Radiofrequency Power in Plasmas - Proceedings of the 20th Topical Conference

PB - American Institute of Physics Inc.

T2 - 20th Topical Conference on Radiofrequency Power in Plasmas

Y2 - 25 June 2013 through 28 June 2013

ER -

Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2

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