In the detached divertor conditions with lower plasma temperature, vibrationally excited hydrogen molecules H₂(ν) persist in dissociation and ionization processes of the plasma volume recombination. Thus, the plasma volume recombination associated with vibrationally excited hydrogen molecules H₂(ν), that is, Molecular Assisted Recombination (MAR) is effective in the divertor plasma to enhance the reduction of ion particle flux. We present the experimental observation of MAR for hydrogen detached plasma in the linear divertor plasma simulator, TPD-SheetIV (Test Plasma produced by Directed current for Sheet plasma)[1,2]. In order to investigate the dissociative recombination in MAR, measurements of the molecular and atomic ion densities (n_H⁺, n_H2⁺, n_H3⁺), the electron density (n_e), electron temperature (T_e), and the heat load to the target plate (Q) were carried out in hydrogen detached plasma with hydrogen gas puff. The electron temperature and the electron density were measured by a plane Langmuir probe. An “omegatron” mass-analyzer, situated behind a small hole of the endplate with the differential pumping system, is used for analyzing ion species. It is also intended to show that the observed emission intensity (Lyman-bands) of VUV (vacuum ultraviolet) wavelength region from electronic excited hydrogen molecules H₂(B¹∑_u⁺) by electron impact could be explained by MAR. In the range of low hydrogen gas pressure, vibrationally excited hydrogen molecules H₂(X¹∑_g⁺(ν>4)) result from the deexcitation of electronic excited hydrogen molecules H₂(B¹∑_u⁺) by the collision of hydrogen molecules with hot electron (T_e=10-15 eV) in the central region of the sheet plasma. It is shown from the results of the mass-analysis (H⁺, H₂⁺, H₃⁺) that dissociative recombination is taking place in the central region of the sheet plasma over the range of low hydrogen pressure.

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