Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range

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

doi:10.1088/0029-5515/55/7/073003

Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range

T. Shinya, Y. Takase, T. Wakatsuki, A. Ejiri, H. Furui, J. Hiratsuka, K. Imamura, T. Inada, H. Kakuda, H. Kasahara, R. Kumazawa, C. Moeller, T. Mutoh, Y. Nagashima, K. Nakamura, A. Nakanishi, T. Oosako, K. Saito, T. Seki, M. SoneharaH. Togashi, S. Tsuda, N. Tsujii, T. Yamaguchi

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Abstract

Non-inductive plasma current start-up and sustainment by waves in the lower-hybrid frequency range (200 MHz) have been studied on the TST-2 spherical tokamak (R₀ ≤ 0.38 m, a ≤ 0.25 m, B_t0 ≤ 0.3 T, I_p ≤ 0.14 MA) using three types of antenna: the 11-element inductively-coupled combline antenna, the dielectric loaded 4-waveguide array antenna, and the 13-element capacitively-coupled combline (CCC) antenna. The maximum plasma currents of 15 kA, 10 kA and 16 kA were achieved, respectively. The highest current drive figure of merit η_CD ≡ n¯_eI_pR/P_RF was achieved by the CCC antenna. The efficiency of current drive should improve by reducing prompt orbit losses of high energy electrons by operating at higher plasma current (to improve orbit confinement) and higher toroidal magnetic field (to improve wave accessibility to the plasma core), while keeping the density high enough (to avoid excessive acceleration of electrons), but under the 'density limit'.

Original language	English
Article number	073003
Journal	Nuclear Fusion
Volume	55
Issue number	7
DOIs	https://doi.org/10.1088/0029-5515/55/7/073003
Publication status	Published - Jul 1 2015

All Science Journal Classification (ASJC) codes

Nuclear and High Energy Physics
Condensed Matter Physics

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Shinya, T., Takase, Y., Wakatsuki, T., Ejiri, A., Furui, H., Hiratsuka, J., Imamura, K., Inada, T., Kakuda, H., Kasahara, H., Kumazawa, R., Moeller, C., Mutoh, T., Nagashima, Y., Nakamura, K., Nakanishi, A., Oosako, T., Saito, K., Seki, T., ... Yamaguchi, T. (2015). Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range. Nuclear Fusion, 55(7), Article 073003. https://doi.org/10.1088/0029-5515/55/7/073003

Shinya, T, Takase, Y, Wakatsuki, T, Ejiri, A, Furui, H, Hiratsuka, J, Imamura, K, Inada, T, Kakuda, H, Kasahara, H, Kumazawa, R, Moeller, C, Mutoh, T, Nagashima, Y, Nakamura, K, Nakanishi, A, Oosako, T, Saito, K, Seki, T, Sonehara, M, Togashi, H, Tsuda, S, Tsujii, N & Yamaguchi, T 2015, 'Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range', Nuclear Fusion, vol. 55, no. 7, 073003. https://doi.org/10.1088/0029-5515/55/7/073003

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title = "Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range",

abstract = "Non-inductive plasma current start-up and sustainment by waves in the lower-hybrid frequency range (200 MHz) have been studied on the TST-2 spherical tokamak (R0 ≤ 0.38 m, a ≤ 0.25 m, Bt0 ≤ 0.3 T, Ip ≤ 0.14 MA) using three types of antenna: the 11-element inductively-coupled combline antenna, the dielectric loaded 4-waveguide array antenna, and the 13-element capacitively-coupled combline (CCC) antenna. The maximum plasma currents of 15 kA, 10 kA and 16 kA were achieved, respectively. The highest current drive figure of merit ηCD ≡ n¯eIpR/PRF was achieved by the CCC antenna. The efficiency of current drive should improve by reducing prompt orbit losses of high energy electrons by operating at higher plasma current (to improve orbit confinement) and higher toroidal magnetic field (to improve wave accessibility to the plasma core), while keeping the density high enough (to avoid excessive acceleration of electrons), but under the 'density limit'.",

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

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doi = "10.1088/0029-5515/55/7/073003",

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T1 - Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range

AU - Shinya, T.

AU - Takase, Y.

AU - Wakatsuki, T.

AU - Ejiri, A.

AU - Furui, H.

AU - Hiratsuka, J.

AU - Imamura, K.

AU - Inada, T.

AU - Kakuda, H.

AU - Kasahara, H.

AU - Kumazawa, R.

AU - Moeller, C.

AU - Mutoh, T.

AU - Nagashima, Y.

AU - Nakamura, K.

AU - Nakanishi, A.

AU - Oosako, T.

AU - Saito, K.

AU - Seki, T.

AU - Sonehara, M.

AU - Togashi, H.

AU - Tsuda, S.

AU - Tsujii, N.

AU - Yamaguchi, T.

PY - 2015/7/1

Y1 - 2015/7/1

N2 - Non-inductive plasma current start-up and sustainment by waves in the lower-hybrid frequency range (200 MHz) have been studied on the TST-2 spherical tokamak (R0 ≤ 0.38 m, a ≤ 0.25 m, Bt0 ≤ 0.3 T, Ip ≤ 0.14 MA) using three types of antenna: the 11-element inductively-coupled combline antenna, the dielectric loaded 4-waveguide array antenna, and the 13-element capacitively-coupled combline (CCC) antenna. The maximum plasma currents of 15 kA, 10 kA and 16 kA were achieved, respectively. The highest current drive figure of merit ηCD ≡ n¯eIpR/PRF was achieved by the CCC antenna. The efficiency of current drive should improve by reducing prompt orbit losses of high energy electrons by operating at higher plasma current (to improve orbit confinement) and higher toroidal magnetic field (to improve wave accessibility to the plasma core), while keeping the density high enough (to avoid excessive acceleration of electrons), but under the 'density limit'.

AB - Non-inductive plasma current start-up and sustainment by waves in the lower-hybrid frequency range (200 MHz) have been studied on the TST-2 spherical tokamak (R0 ≤ 0.38 m, a ≤ 0.25 m, Bt0 ≤ 0.3 T, Ip ≤ 0.14 MA) using three types of antenna: the 11-element inductively-coupled combline antenna, the dielectric loaded 4-waveguide array antenna, and the 13-element capacitively-coupled combline (CCC) antenna. The maximum plasma currents of 15 kA, 10 kA and 16 kA were achieved, respectively. The highest current drive figure of merit ηCD ≡ n¯eIpR/PRF was achieved by the CCC antenna. The efficiency of current drive should improve by reducing prompt orbit losses of high energy electrons by operating at higher plasma current (to improve orbit confinement) and higher toroidal magnetic field (to improve wave accessibility to the plasma core), while keeping the density high enough (to avoid excessive acceleration of electrons), but under the 'density limit'.

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Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range

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