# Plasma and Fusion Research

## Volume 6, 2401125 (2011)

# Regular Articles

- Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
- 1)
- Department of Applied Physics, Faculty of Engineering, Shinshu University, Nagano 380-8553, Japan
- 2)
- National Institute for Fusion Science, Toki 509-5292, Japan

### Abstract

We develop a collisional-radiative model for calculating the velocity distributions of excited hydrogen atoms. In the model, the velocity distributions are approximated using linear combinations of several basis functions which are treated as discrete velocity states, and only charge exchange collisions with proton are considered as velocity changing collisions. The populations in the velocity and excited states are calculated under an assumption of a quasi-stationary state. With the model we derive the velocity distribution of the ground state atoms from that of excited atoms in the n = 3 level observed for an LHD plasma, where n is the principal quantum number. The mean kinetic energy of the ground state atoms is estimated to be 5.6 eV, which is 0.05 eV less than that of the n = 3 atoms.

### Keywords

collisional-radiative model, hydrogen atom, velocity distribution, charge exchange collision, velocity changing collision, LHD plasma, spectroscopy

### Full Text

### References

- [1] J.D. Hey, M. Korten, Y.T. Lie et al., Contrib. Plasma Phys. 36, 583 (1996).
- [2] H. Kubo, H. Takenaga, T. Sugie et al., Plasma Phys. Control. Fusion 40, 1115 (1998).
- [3] T. Shikama, S. Kado, H. Zushi et al., Plasma Phys. Control. Fusion 48, 1125 (2006).
- [4] A. Iwamae, M. Hayakawa, M. Atake et al., Phys. Plasmas 12, 042501 (2005).
- [5] K. Fujii, K. Mizushiri, T. Nishioka et al., Nucl. Instrum. Methods A 623, 690 (2010).
- [6] T. Fujimoto, Plasma Spectroscopy, Oxford (2004).
- [7] I. Bray and A.T. Stelbovics, Phys. Rev. A 46, 6995 (1992).
- [8] L.C. Johnson, Astrophys. J. 174, 227 (1972).
- [9] R.K. Janev, W.D. Langer, K. Evans Jr. et al., Elementary Processes in Hydergon-Helium Plasmas, Springer (1987).
- [10] P.S. Krstic and D.R. Schultz, J. Phys. B 36, 385 (2003).
- [11] C. Harel, H. Jouin and B. Pons, Atomic Data and Nuclear Tables 68, 279 (1998).
- [12] V. Shevelko, D. Kato, M.Y. Song et al., Nucl. Instrum. Methods B 267, 3395 (2009).
- [13] K. Fujii, K. Mizushiri, T. Nishioka et al., Rev. Sci. Instrum. 81, 033106 (2010).
- [14] M. Goto, K. Sawada, K. Fujii, M. Hasuo and S. Morita, Nucl. Fusion 51, 023005 (2011).
- [15] K. Narihara, I. Yamada, H. Hayashi and K. Yamauchi, Rev. Sci. Instrum. 72, 1122 (2001).

This paper may be cited as follows:

Keisuke FUJII, Taiichi SHIKAMA, Keiji SAWADA, Motoshi GOTO, Shigeru MORITA and Masahiro HASUO, Plasma Fusion Res. 6, 2401125 (2011).