Cross Sections of Charge Transfer by Slow Singly-Charged Carbon Ions from Various Hydrocarbon Molecules

T.Kusakabe, K.Imou, N.Tomita, K.Hosomi, H.Nakanishi, S.Satoh, Y.Nakai1), H.Tawara2), M.Kimura3)

Department of Science, Kinki University, Kowakae, Higashi-osaka 577-8502, Japan
1) Suzuka University for Medical Science, Suzuka, Mie 510-0293, Japan
2) Department of Pure and Applied Physics, The Queen’s University, Belfast BT7 1NN, UK
3) Graduate School of Science, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan

In the edge plasmas of the present day large tokamak devices with low­Z plasma facing components such as carbon materials, many kinds of low charge-state ions and carbon containing molecules, primarily hydrocarbons, are known to be produced. Among many collision processes relevant to low temperature edge plasmas, charge transfer processes of these ions colliding with various molecules play a key role in determining properties of high temperature plasmas at the core region. We therefore systematically measured the charge transfer cross sections of H+, C+, O+, Ne2+~6+, and Ar2+~9+ ions in collisions with various molecules and compared them with theoretical calculations [1].
In this paper, we present the charge transfer cross sections of C+ ions dominantly in the ground state (2P) in collisions with various hydrocarbons in the energy range between 0.15 and 4.5 keV.
Most of the present charge transfer cross sections, except for CH4, are found to show weak energy dependence over the collision energy range observed, and only slightly decrease with increasing the collision energy. This feature indicates that vibrational excited states of the target molecular ions produced after charge transfer might have resulted in some vibrationally excited states which make these collisions near or accidentally reasonant.

References

[1] T.Kusakabe, et al., Phys. Rev. A, 62 (2000) 062714./ ibid: 062715./ Phys. Rev. A, 60 (1999) 344./ Phys. Rev. Lett., 87 (2001) 243401./ J. Phys. B: At. Mol. Opt. Phys., 34 (2001) 4809./ Nucl. Instr. Meth. B, 205 (2003) 600.

This work was mainly performed as a collaborative research program of the National Institute for Fusion Science, Japan, and supported in part by a Grant-in-Aid for Science Research (C) from the Ministry of Education, Science, Sports and Culture in Japan.