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Author(s):
V.Yu. Sergeev, R.K. Janev, M.J. Rakovic, S. Zou, N. Tamura, K.V. Khlopenkov and S. Sudo
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Title:
Optimization of the Visible CXRS Measurements of TESPEL Diagnostics in LHD
Date of publication:
Aug. 2001
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Key words:
diagnostics, impurity transport, pellet, charge exchange, radiation
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Abstract:
A model for calculations of Charge eXchange Recombination (CXR) signals of impurity nuclei injected in high temperature plasma has been developed. For that purpose, the simplified collisional-radiative model for calculations of CXR signal and the corona equilibrium set of equations for ionization balance were solved taking into account the main physical processes involved. Scaling laws of partial CX cross sections with respect to both principal and angular quantum numbers of captured electron have been established on the basis of the results of Classical Trajectory Monte Carlo (CTMC) calculations. The CXR signals for a Li tracer in TESPEL experiments on LHD and CHS machines have been calculated. The difference of about two orders of magnitude in the calculated signals is due to the difference of both NBI neutral flux density and capture-radiation cross-sections and explains the lack of Li^3+ CXR signals in the measurements on LHD. Calculations of the CXR signals for various injected impurities have been performed for LHD conditions. The operational limits of the use of TESPEL diagnostics in the visible spectral range on LHD have been determined. For T_e=1-2 keV (P_NBI = 3 MW) and N_e=(2-5)cdot10^13 cm^-3, injection of F, Mg and Al as tracer materials is proposed.
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