Plasma and Fusion Research
Volume 13, 3403015 (2018)
Regular Articles
- 1)
- National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
- 2)
- SOKENDAI (The Graduate University for Advanced Studies), Department of Fusion Science, Toki, Gifu 509-5292, Japan
Abstract
Instabilities of high-frequency magnetosonic waves caused by energetic ions with a ring-like velocity distribution are studied with a one-dimensional electromagnetic particle code which simulates self-consistently the full ion and electron dynamics. It is shown that the magnetosonic waves with frequencies slightly smaller than the lower-hybrid resonance frequency rapidly grow to large amplitudes, in addition to electromagnetic emissions near the ion cyclotron frequency and its harmonics. The frequency of the magnetosonic wave that has the largest amplitude is in good agreement with the frequency of the most unstable mode predicted by a linear theory. The theory and simulations show that the frequency of the magnetosonic wave increases with the plasma density. The instability of the high-frequency magnetosonic waves may be an excitation mechanism for radio frequency waves in the Lower Hybrid Wave (LHW) frequency region observed in the Large Helical Device (LHD).
Keywords
instabilities driven by energetic ions, PIC simulation, magnetosonic wave, lower hybrid wave, ion cyclotron emission, large helical device, neutral beam injection
Full Text
References
- [1] K. Saito et al., Fusion Eng. Des. 84, 1676 (2009).
- [2] K. Saito et al., Plasma Sci. Technol. 15, 209 (2013).
- [3] K. Saito et al., ‘RF wave detection with high-frequency magnetic probes in LHD’, submitted to Plasma Fusion Res.
- [4] V.S. Belikov and Ya. I. Kolesnichenko, Sov. Phys. Tech. Phys. 20, 1146 (1976).
- [5] R.O. Dendy et al., Phys. Plasmas 1, 3410 (1994).
- [6] K.A. Akimoto et al., J. Plasma Phys. 34, 445 (1985).
- [7] M. Toida and Y. Ohsawa, Solar Phys. 171, 161 (1997).
- [8] M. Toida, Y. Yoshiya and Y. Ohsawa, Phys. Plasmas 12, 102306 (2005).
- [9] D.W. Ross, Phys. Fluids 13, 746 (1970).