Development of high-power, long-pulse gyrotrons and its application for high electron temperature, EBWH and ECCD experiments on LHD

Yoshimura, Y; Kubo, S; Shimozuma, T; Igami, H; Takahashi, H; Nishiura, M; Ito, S; Kobayashi, S; Mizuno, Y; Okada, K; Takita, Y; Mutoh, T; Yamada, H; Komori, A; Kariya, T; Imai, T; Marushchenko, N; Turkin, Y

Conference item

Development of high-power, long-pulse gyrotrons and its application for high electron temperature, EBWH and ECCD experiments on LHD

Abstract:: To sustain plasmas with higher parameters and with longer pulse duration in LHD, ECH system has been upgraded by introducing newly developed 77 GHz gyrotrons. The designed output power and operation duration time are over 1 MW for several seconds and 0.3 MW for continuous operation, respectively. Owing to the upgrade of gyrotrons and improved power supply operation procedure, total injection power of EC-waves to LHD increased up to 3.7 MW at the last LHD experimental campaign in 2010. Application of the high-power 77 GHz EC-waves of 3.4 MW as focused beams to the center of plasma with low line-average electron density of ∼0.2×10 19m -3 causes highly steep electron temperature profile and the central electron temperature reached up to 20 keV, which highly exceeds the former record of 15 keV. At higher density region of 1×10 19m -3, central electron temperature reached 8.6 keV. Additional electron Bernstein wave heatings, O-X-B and slow X-B heatings, using a 77 GHz ECH system caused clear increase in plasma stored energy even for the high-density plasmas over plasma cutoff (>7. 35×10 19m -3) sustained with NBI. For the O-X-B scenario, the 77 GHz EC-wave was obliquely injected from low-field side in O-mode polarization, aiming at the point where high mode-conversion efficiency was expected. For realizing slow X-B scenario, new inner-vessel mirrors were installed in LHD just close to a helical coil, that is, at the high-field side (HFS) region. Using the inner-vessel mirror, X-mode waves were injected from HFS, showing evident increase in plasma stored energy. Oblique injection of long-pulse 0.77 MW/8 s 77 GHz wave with various N ∥ clearly demonstrated ECCD in LHD. The EC-driven current changes its direction with the sign of N ∥, and the highest EC-driven current reached up to 42 kA. © 2011 American Institute of Physics.

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APA Style

Yoshimura, Y., Kubo, S., Shimozuma, T., Igami, H., Takahashi, H., Nishiura, M., Ito, S., Kobayashi, S., Mizuno, Y., Okada, K., Takita, Y., Mutoh, T., Yamada, H., Komori, A., Kariya, T., Imai, T., Marushchenko, N., & Turkin, Y. (2011). Development of high-power, long-pulse gyrotrons and its application for high electron temperature, EBWH and ECCD experiments on LHD. 1406, 465–472.

MLA Style

Yoshimura, Y, et al. “Development of High-Power, Long-Pulse Gyrotrons and Its Application for High Electron Temperature, EBWH and ECCD Experiments on LHD.” vol. 1406, 2011, pp. 465–72.

Chicago Style

Yoshimura, Y, S Kubo, T Shimozuma, et al. 2011. “Development of High-Power, Long-Pulse Gyrotrons and Its Application for High Electron Temperature, EBWH and ECCD Experiments on LHD.” 1406: 465–72.
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