Spectral Modelling of Neutral Beam for Doppler Shift Spectroscopy Diagnostics of INTF.

A 100 keV, negative hydrogen ion based neutral beam system is in the developmental stage at a test facility (Indian Test Facility) in India. This test facility is used for characterizing Diagnostic Neutral Beam (DNB) of ITER.A large number of diagnostics are planned for monitoring and characterization of the beam. The Doppler Shift Spectroscopy (DSS) diagnostics is chosen for characterizing the beam by evaluating the beam divergence, stripping losses and beam uniformity from the observed Balmer-alpha emission from the fast-neutral hydrogen atom, produced from accelerated negative hydrogen ions (H-) ions. In order to design and develop the DSS diagnostics, a forward model to estimate the signal to noise ratio and beam divergence is developed. For the chosen lines of sight (LOS), at different operating scenarios and instrument settings, the model is applied. The expected performance of the diagnostics based on this model is discussed and a brief description of the proposed diagnostics is presented. [ABSTRACT FROM AUTHOR]