[Table of Contents]

Plasma and Fusion Research

Volume 10, 1402001 (2015)

Regular Articles


Development of the Heating Scenarios to Achieve High-Ion Temperature Plasma in the Large Helical Device
Yasuhiko TAKEIRI1,2), Osamu KANEKO1,2), Masaki OSAKABE1), Kenichi NAGAOKA1,2), Sadayoshi MURAKAMI3), Hiromi TAKAHASHI1), Haruhisa NAKANO1), Katsumi IDA1,2), Shigeru MORITA1,2), Masayuki YOKOYAMA1), Mikiro YOSHINUMA1,2), Keisuke FUJII4), Motoshi GOTO1,2), Chihiro SUZUKI1), Ryosuke SEKI1), Katsuyoshi TSUMORI1,2), Katsunori IKEDA1), Masashi KISAKI1), Takashi MUTOH1,2), Hiroshi YAMADA1,2), Akio KOMORI1,2) and the LHD Experiment Group
1)
National Institute for Fusion Science, Toki 509-5292, Japan
2)
The Graduate University for Advanced Studies, Hayama, Kanagawa 240-0193, Japan
3)
Department of Nuclear Engineering, Kyoto University, Kyoto 615-8530, Japan
4)
Department of Mechanical Engineering and Science, Kyoto University, Kyoto 615-8540, Japan
(Received 6 February 2014 / Accepted 4 October 2014 / Published 30 January 2015)

Abstract

High-ion temperature experiments in the Large Helical Device (LHD) are categorized in terms of the heating scenarios that are closely related to the development of neutral beam injection (NBI) systems. Although high-energy tangential negative-NBI heating has greatly contributed to extending the plasma parameter regime in LHD, the ion temperature does not increase because the electron heating is dominant with negative-NBIs. In the high-Z discharges, it was demonstrated that the ion temperature increased with an increasing ion heating power and achieved 13.5 keV with the negative-NBIs. Low-energy perpendicular positive-NBIs were installed for the ion heating, and the ion temperature was increased to more than 7 keV in hydrogen discharges. In the high-ion temperature plasmas, an ion internal transport barrier (ion ITB) was formed, and the impurity hole was observed in the core. Long-pulse ion cyclotron range of frequency heating (ICH)/electron cyclotron resonance heating (ECRH) helium discharges are effective for wall conditioning, leading to a decrease in the neutral density and a peaked density profile. Consequently, the ion heating efficiency increases in the core, and the central Ti is raised up to 7.5 keV. With the superposition of high-power ECRH, high-performance plasmas of Ti ∼ Te ∼ 6 keV were obtained. In the planned deuterium experiment, the ion heating power will be increased with the deuterium beam injection, and Ti = 10 keV is expected.


Keywords

high-ion temperature plasma, Large Helical Device, NBI heating, high-Z discharge, ion ITB, impurity hole, long-pulse discharge cleaning, deuterium experiment, ion and electron root

DOI: 10.1585/pfr.10.1402001


References

  • [1] A. Iiyoshi et al., Nucl. Fusion 39, 1245 (1999).
  • [2] O. Motojima et al., Phys. Plasmas 6, 1843 (1999).
  • [3] A. Komori et al., Fusion Sci. Technol. 58, 1 (2010).
  • [4] Y. Takeiri et al., Plasma Fusion Res. 3, S1001 (2008).
  • [5] H. Yamada for the LHD Experiment Group, Nucl. Fusion 51, 094021 (2011).
  • [6] O. Kaneko et al., Nucl. Fusion 53, 104015 (2013).
  • [7] T. Mutoh et al., Nucl. Fusion 53, 063017 (2013).
  • [8] O. Kaneko et al., Proc. 16th Int. Conf. Fusion Energy, Montreal, 1996, Vol. 3, International Atomic Energy Agency, p. 539 (1997).
  • [9] Y. Takeiri et al., J. Plasma Fusion Res. 74, 1434 (1998).
  • [10] Y. Takeiri et al., Rev. Sci. Instrum. 71, 1225 (2000).
  • [11] O. Kaneko et al., Nucl. Fusion 43, 692 (2003).
  • [12] Y. Takeiri et al., Nucl. Fusion 46, S199 (2006).
  • [13] M. Osakabe et al., Proc. Joint 17th Int. Toki Conf. and 16th Int. Stellarator/Heliotron Workshop, Toki, Japan, 2007, P2-079 (2007).
  • [14] Y. Takeiri et al., Fusion Sci. Technol. 58, 482 (2010).
  • [15] K. Nagaoka et al., Plasma Fusion Res. 3, S1013 (2008).
  • [16] K. Tsumori et al., Fusion Sci. Technol. 58, 489 (2010).
  • [17] T. Mutoh et al., Phys. Rev. Lett. 85, 4530 (2000).
  • [18] K. Saito et al., Fusion Sci. Technol. 58, 515 (2010).
  • [19] S. Murakami et al., Nucl. Fusion 46, S425 (2006).
  • [20] M. Yoshinuma et al., Fusion Sci. Technol. 58, 375 (2010).
  • [21] K.C. Shaing, Phys. Fluids 27, 1567 (1984).
  • [22] T. Mutoh et al., in Applications of Radio-Frequency Power to Plasmas, AIP Conference Proceedings 159, 238 (1987).
  • [23] M. Yokoyama et al., Contrib. Plasma Phys. 50, 586 (2010).
  • [24] S. Morita, et al., Nucl. Fusion 42, 1179 (2002).
  • [25] Y. Takeiri et al., Nucl. Fusion 45, 565 (2005).
  • [26] T. Shimozuma et al., Plasma Phys. Control. Fusion 45, 1183 (2003).
  • [27] Y. Takeiri et al., Phys. Plasmas 10, 1788 (2003).
  • [28] Y. Takeiri et al., Nucl. Fusion 47, 1078 (2007).
  • [29] S. Morita, et al., Nucl. Fusion 43, 899 (2003).
  • [30] H. Takahashi et al., Nucl. Fusion 53, 073034 (2013).
  • [31] K. Nagaoka et al., Proc. 25th International Atomic Energy Agency Fusion Energy Conference, St. Petersburg, 2014, PPC/2-1 (2014).
  • [32] M. Yokoyama et al., Plasma Fusion Res. 7, 2403011 (2012).
  • [33] M. Yokoyama et al., Phys. Plasmas 15, 056111 (2008).
  • [34] S. Matsuoka et al., Plasma Fusion Res. 3, S1056 (2008).
  • [35] K. Nagaoka et al., Nucl. Fusion 51, 083022 (2010).
  • [36] S. Murakami et al., submitted to Plasma Phys. Control. Fusion.
  • [37] K. Ida et al., Phys. Plasmas 16, 056111 (2009).
  • [38] M. Yoshinuma et al., Nucl. Fusion 49, 062002 (2009).
  • [39] M. Yoshinuma et al., Proc. 23rd International Atomic Energy Agency Fusion Energy Conference, Daejon, 2010, EXC9-1 (2010).
  • [40] H. Takahashi et al., submitted to Plasma Fusion Res.
  • [41] K. Fujii et al., Rev. Sci. Instrum. 85, 023502 (2014).
  • [42] Y. Takeiri et al., Joint 19th Int. Stellarator/Heliotron Workshop and 16th IEA-RFP Workshop, Padova, 2013, B14 (2013).

This paper may be cited as follows:

Yasuhiko TAKEIRI, Osamu KANEKO, Masaki OSAKABE, Kenichi NAGAOKA, Sadayoshi MURAKAMI, Hiromi TAKAHASHI, Haruhisa NAKANO, Katsumi IDA, Shigeru MORITA, Masayuki YOKOYAMA, Mikiro YOSHINUMA, Keisuke FUJII, Motoshi GOTO, Chihiro SUZUKI, Ryosuke SEKI, Katsuyoshi TSUMORI, Katsunori IKEDA, Masashi KISAKI, Takashi MUTOH, Hiroshi YAMADA, Akio KOMORI and the LHD Experiment Group, Plasma Fusion Res. 10, 1402001 (2015).