In Large Helical Device (LHD), the discharges of high Z are often performed in order to obtain a high ion temperature. The ion density is relatively smaller than the electron density in the high Z plasma. Therefore the high ion temperature can be obtained since the input energy per ion atom is large. The charge exchange neutral particle diagnostic [1] is used for the ion temperature measurement accompany with the x-ray crystal measurement and the charge exchange spectroscopy. In the charge exchange neutral diagnostic, the ion temperature can be obtained by observing the spectra of neutral particles, which are generated by the charge exchange between the background neutral and the plasma ion, and assuming the Maxwellian distribution of the spectra. Even if the high Z noble gases are used as the plasma target, some absorbed hydrogen atoms remain in the wall. Heating NBI provides large hydrogen neutral source. However, there is not so much neutral hydrogen in high Z plasma. The penetration depth of the neutral hydrogen is short in high Z plasma because the chain reaction of the charge exchange between the neutral hydrogen and plasma ion is rare. To estimate the ion temperature, we must evaluate where the neutral particles with certain energy are emitted. In calculation, we also consider the charge exchange between the partially ionized high Z ion and proton. Here the profile of the partially ionized high Z ion can be obtained by using the impurity transport code. The cross section of the charge exchange between the partially ionized high Z ion and proton are assumed from the theoretical prediction. In our case, the residual hydrogen is still effective as a charge exchange source. Observed ion temperature strongly reflects that at the plasma peripheral.

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