Plasma and Fusion Research

Volume 14, 3402075 (2019)

Regular Articles

Analysis of Energetic Particle Confinement in LHD Using Neutron Measurement and Simulation Codes
Hideo NUGA1), Ryosuke SEKI1,2), Kunihiro OGAWA1,2), Shuji KAMIO1), Yutaka FUJIWARA1), Masaki OSAKABE1,2), Mitsutaka ISOBE1,2), Takeo NISHITANI1), Masayuki YOKOYAMA1,2) and LHD Experiment Group
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
1)
SOKENDAI (The Graduate University for Advanced Studies), Toki 509-5292, Japan
(Received 10 January 2019 / Accepted 7 March 2019 / Published 25 April 2019)

Abstract

The fast ion confinement time in the Large Helical Device (LHD) is investigated by using the neutron measurement and simulations. To estimate the fast ion confinement time, a series of short pulse neutral beam (NB) injection experiments have been performed. Additionally, the NB heating simulation code, CONV_FIT3D, has been extended to estimate the neutron emission rate in LHD. We estimate the fast ion confinement time from the differences between the measured and the simulated neutron decay times after the NB is turned off. It is found that the fast ion confinement time of three tangential NBs have similar values τc ∼ 0.5 sec and the confinement time of the perpendicular NB is approximately τc ∼ 0.06 sec. Additionally, by using the confinement time and the ion ratio data estimated from the simulation result, we can obtain a simulation result similar to the measured data.

Keywords

fast ion confinement, neutron emission rate, LHD

DOI: 10.1585/pfr.14.3402075

Full Text

PDF format (631Kbytes) PDF Download

References

  • [1] Y. Takeiri, IEEE Trans. Plasma Sci. 46, 2348 (2018).
  • [2] M. Osakabe, M. Isobe, M. Tanaka et al., IEEE Trans. Plasma Sci. 46, 2324 (2018).
  • [3] Y. Takeiri, IEEE Trans. Plasma Sci. 46, 1141 (2018).
  • [4] M. Osakabe, Y. Takeiri, T. Morisaki et al., Fusion Sci. Technol. 72, 199 (2017).
  • [5] M. Isobe, K. Ogawa, T. Nishitani et al., IEEE Trans. Plasma Sci. 46, 2050 (2018).
  • [6] J. Strachan, P. Colestock, S. Davis et al., Nucl. Fusion 21, 67 (1981).
  • [7] W. Heidbrink, J. Kim and R. Groebner, Nucl. Fusion 28, 1897 (1988).
  • [8] H. Nuga, R. Seki, S. Kamio et al., Nucl. Fusion 59, 016007 (2019).
  • [9] M. Isobe, K. Ogawa, H. Miyake et al., Rev. Sci. Instrum. 85, 11E114 (2014).
  • [10] S. Murakami, N. Nakajima and M. Okamoto, Trans. Fusion Technol. 27, 256 (1995).
  • [11] M. Sato, S. Murakami, A. Fukuyama et al., Proc. 18th Int. Toki Conf, 2008.
  • [12] P. Vincenzi, T. Bolzonella, S. Murakami et al., Plasma Phys. Control. Fusion 58, 125008 (2016).
  • [13] M. Yokoyama, R. Seki, C. Suzuki et al., Nucl. Fusion 57, 126016 (2017).
  • [14] T.H. Stix, Plasma Phys. 14, 367 (1972).
  • [15] D. Mikkelsen, Nucl. Fusion 29, 1113 (1989).
  • [16] H.-S. Bosch and G. Hale, Nucl. Fusion 32, 611 (1992).
  • [17] K. Ogawa, M. Isobe, T. Nishitani et al., Plasma Phys. Control. Fusion 60, 095010 (2018).
  • [18] B. Braams and C. Karney, Phys. Fluid B 1, 1355 (1989).
  • [19] S. Murakami, H. Yamada, M. Sasao et al., Fusion Sci. Technol. 46, 241 (2004).
  • [20] H. Zhou, S. Morita, M. Goto et al., Rev. Sci. Instrum. 81, 10D706 (2010).
  • [21] X. Huang, S. Morita, T. Oishi et al., Plasma Fusion Res. 10, 3402036 (2015).