Plasma and Fusion Research

Volume 14, 3402053 (2019)

Regular Articles

Dependence of Plasma Parameters in Hydrogen Pellet Ablation Cloud on the Background Plasma Conditions
Motoshi GOTO1,2), Hiroya UYAMA3), Takuya OGAWA4), Khanit MATRA5), Gen MOTOJIMA1,2), Tetsutarou OISHI1,2) and Shigeru MORITA1,2)
1)
National Institute for Fusion Science, Toki 509-5292, Japan
2)
Department of Fusion Science, SOKENDAI (The Graduate University for Advanced Studies), Toki 509-5292, Japan
3)
National Institute of Technology, Toyama College, Toyama 939-8630, Japan
4)
Department of Electrical and Electronic Engineering, Utsunomiya University, Utsunomiya 321-8505, Japan
5)
Department of Electrical Engineering, Srinakharinwirot University, Ongkharak, Nakhonnayok, 26120, Thailand
(Received 25 December 2018 / Accepted 28 January 2019 / Published 10 April 2019)

Abstract

UV-visible spectra of the radiation from hydrogen pellet ablation clouds have been measured in the Large Helical Device. The temporal development of the Balmer-α line intensity shows a peaked profile with FWHM (full width at half maximum) of approximately 150 μs. The electron temperature Te, electron density ne, and plasma volume V are evaluated by fitting of the measured spectra with a complete LTE (local thermodynamic equilibrium) model. The results shows that Te is almost unchanged, while ne and V increases and decreases monotonically, respectively, in the dominant time period around the intensity peak. The same analyses made for several different magnetic configurations have revealed that ne has a tendency to become higher when the magnetic field strength is higher, while no clear dependence on the magnetic axis position has been observed. On the other hand, Te shows little dependence either on the magnetic field strength or the magnetic axis position.

Keywords

hydrogen pellet injection, ablation cloud, Stark broadening, radiative recombination continuum, radiative attachment continuum, complete LTE

DOI: 10.1585/pfr.14.3402053

Full Text

PDF format (489Kbytes) PDF Download

References

  • [1] S.S. Milora, W.A. Houlberg, L.L. Lengyel and V. Mertens, Nucl. Fusion 35, 657 (1995).
  • [2] M. Goto, R. Sakamoto and S. Morita, Plasma Phys. Control. Fusion 49, 1163 (2007).
  • [3] G. Motojima, R. Sakamoto, M. Goto et al., Rev. Sci. Instrum. 83, 093506 (2012).
  • [4] G. Seguineaud, G. Motojima, Y. Narushima and M. Goto, Atoms 6, 34 (2018).
  • [5] R. Sakamoto, H. Yamada, K. Tanaka et al., Nucl. Fusion 41, 381 (2001).
  • [6] T. Fujimoto, Plasma Spectroscopy (Oxford University Press, Oxford, 2004).
  • [7] C. Stehlé and R. Hutcheon, Astron. Astrophys. 140, 93 (1999).
  • [8] P.J. Storey and D.G. Hummer, Comput. Phys. Commun. 66, 129 (1991).
  • [9] A.W. Wishart, Mon. Not. R. Astron. Soc. 187, 59 (1979).
  • [10] D.R. Inglis and E. Teller, Astrophys. J. 90, 439 (1939).