Numerical simulation of hydrogen molecular dissociation and the effects to Hα profiles in low temperature plasmas

Hydrogen molecules may have considerably high density in edge regions of fusion devices so that clarifying their behavior in edge plasmas is very important in understanding the phenomena near plasma facing materials. This paper evaluated the energy distribution of the dissociated products of H ₂ due to the electron induced excitation to the repulsive state b ³ Σ _u and the excitation to a ³ Σ _u followed by the radiative decay to the repulsive state b ³ Σ _u under the framework of Gryzinski approximation [M. Gryzinski, Phys. Rev. 138 (2A) (1965) A305, A322, A366]. The vibrational populations of H ₂ were considered in the calculation. The results show that the dissociated atoms from these channels are highly distributed in the low energy range (< 1 eV ) while there is no significant distribution in the high energy range (> 3 eV ), when H ₂ molecules are vibrationally excited. The discussions were made on the influences to Hα profiles in the low temperature plasmas [S. Tanaka, B.J. Xiao, K., Kobayashi , M. Morita, Plasma Phys. Control Fus. 42 (2000) 1091]. It is shown that the contribution of the low energy atoms in ground state may not be the only contributions of the low energy component in the observed Hα especially when H ₂(X ¹ Σ _g ⁺)+e→H ₂(1sσ, nlλ| ¹ Λ )→e+H(1s)+H(2s) reaction has considerable reaction rates in the electron temperature around 10 eV.