[Table of Contents]

Plasma and Fusion Research

Volume 7, 1205154 (2012)

Rapid Communications

High Power and High Efficiency Operation of 77 GHz Gyrotrons by Stepwise Raising of the Anode Voltage
Hiromi TAKAHASHI, Takashi SHIMOZUMA, Satoshi ITO, Shin KUBO, Yasuo YOSHIMURA, Hiroe IGAMI, Masaki NISHIURA, Sakuji KOBAYASHI, Yoshinori MIZUNO, Kohta OKADA, Yasuyuki TAKITA, Shinya OGASAWARA1), Ryohei MAKINO1), Takashi MUTOH, Tsuyoshi KARIYA2), Ryutaro MINAMI2) and Tsuyoshi IMAI2)
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
1)
Department of Energy and Technology, Nagoya University, Nagoya 464-8463, Japan
2)
Plasma Research Center, University of Tsukuba, Tsukuba 305-8577, Japan
(Received 7 November 2011 / Accepted 13 October 2012 / Published 22 November 2012)

Abstract

High power and high efficiency operation of 77 GHz gyrotrons was achieved by the stepwise raising of the anode voltage. In particular, a stable MOU output power of 1.8 MW was obtained for 1 s. The effect of beam-charge neutralization on the oscillation characteristics was examined. The intended beam acceleration voltage was not initially reached due to the space-charge effect but was achieved over time through the charge neutralization process. By applying the stepped anode voltage, the gyrotron operational parameters were able to be optimized for the sufficiently accelerated electron beam, leading to the improvement of the output power and the electric efficiency.

Keywords

gyrotron, ECRH, space-charge effect, charge neutralization, LHD

DOI: 10.1585/pfr.7.1205154

Full Text

PDF format (361Kbytes) PDF Download

References

  • [1] H. Takahashi et al., Fusion Sci. Technol. 57, 19 (2010).
  • [2] T. Kariya et al., J. Infrared Millim. Terahertz Waves 32, 295 (2011).
  • [3] T. Shimozuma et al., Fusion Sci. Technol. 58, 530 (2010).
  • [4] K. Sakamoto et al., Nat. Phys. 3, 411 (2007).
  • [5] T. Kobayashi et al., Nucl. Fusion 51, 103037 (2011).
  • [6] G.S. Nusinovich et al., Phys. Plasmas 13, 083106 (2006).

This paper may be cited as follows:

Hiromi TAKAHASHI, Takashi SHIMOZUMA, Satoshi ITO, Shin KUBO, Yasuo YOSHIMURA, Hiroe IGAMI, Masaki NISHIURA, Sakuji KOBAYASHI, Yoshinori MIZUNO, Kohta OKADA, Yasuyuki TAKITA, Shinya OGASAWARA, Ryohei MAKINO, Takashi MUTOH, Tsuyoshi KARIYA, Ryutaro MINAMI and Tsuyoshi IMAI, Plasma Fusion Res. 7, 1205154 (2012).