Plasma and Fusion Research

Volume 14, 3401112 (2019)

Regular Articles

Simulation Study of Energetic Ion Driven Instabilities near the Lower Hybrid Resonance Frequency in a Plasma with Increasing Density
Mieko TOIDA1), Hiroe IGAMI1), Kenji SAITO1), Tsuyoshi AKIYAMA1,2), Shuji KAMIO1) and Ryosuke SEKI1,2)
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
SOKENDAI (The Graduate University for Advanced Studies), Department of Fusion Science, Toki, Gifu 509-5292, Japan
(Received 9 January 2019 / Accepted 26 April 2019 / Published 19 June 2019)


Using a one-dimensional electromagnetic particle code which simulates self-consistently the full ion and electron dynamics, we study instabilities driven by energetic ions injected continuously in a plasma where the density and the lower-hybrid resonance frequency ωLH increase with time. The simulation shows that the ion cyclotron harmonic wave with ω ≃ lΩi, where l is an integer and Ωi is the ion cyclotron frequency, is excited when ωLH becomes close to lΩi. When ωLH is greater than lΩi, this wave couples with the ion Bernstein mode that has the dispersion curve connecting to ωLH. It is also found that as a result of the instabilities and the wave-wave coupling, the stair-like frequency chirping with the riser Ωi appears in the magnetic fluctuations in the frequency range of ωLH. The frequency chirping has characteristics similar to the frequency chirping observed in the RF radiations at the plasma start-up phase of the LHD experiments.


instabilities driven by energetic ions, PIC simulation, lower hybrid resonance frequency, ion cyclotron wave, ion Bernstein wave, Large Helical Device

DOI: 10.1585/pfr.14.3401112


  • [1] J.B. McBride, E. Ott, J.P. Boris and J.H. Orens, Phys. Fluids 15, 2367 (1972).
  • [2] E. Ott, J.B. McBride, J.H. Orens and J.P. Boris, Phys. Rev. Lett. 28, 88 (1972).
  • [3] K.A. Akimoto et al., J. Plasma Phys. 34, 445 (1985).
  • [4] K. Saito et al., Fusion Eng. Des. 84, 1676 (2009).
  • [5] K. Saito et al., Plasms Sci. Tech. 15, 209 (2013).
  • [6] K. Saito et al., Plasma Fusion Res. 13, 3402043 (2018).
  • [7] H. Igami et al., “Observation of stair-like frequency transitions of ion cyclotron harmonic emissions in the lower hybrid frequency range in LHD”, presented at International Toki Conference 2018, P1-80.
  • [8] M. Toida et al., Plasma Fusion Res. 13, 3403015 (2018).
  • [9] T.H. Stix, Waves in Plasmas (Springer-Verlag, New York, 1992).
  • [10] D.G. Lominadze, Cyclotron Waves in Plasma (Pergamon Press, 1981).
  • [11] V.S. Belikov and Ya.I. Kolesnichenko, Sov. Phys. Tech. Phys. 20, 1146 (1976).
  • [12] R.O. Dendy et al., Phys. Plasmas 1, 3407 (1994).