Abstract
To investigate the fast ion behavior, a fast ion D-alpha (FIDA) diagnostic system has been installed on EAST. Fast ion features can be inferred from the Doppler shifted spectrum of Balmer-alpha light from energetic hydrogenic atoms. This paper will focus on the validation of FIDA measurements performed using MHD-quiescent discharges in 2015 campaign. Two codes have been applied to calculate the Dα spectrum: one is a Monte Carlo code, Fortran 90 version FIDASIM, and the other is an analytical code, Simulation of Spectra (SOS). The predicted SOS fast-ion spectrum agrees well with the measurement; however, the level of fast-ion part from FIDASIM is lower. The discrepancy is possibly due to the difference between FIDASIM and SOS velocity distribution function. The details will be presented in the paper to primarily address comparisons of predicted and observed spectrum shapes/amplitudes.
Highlights
Fast ions as the main source of heat and momentum can determine the efficiency of heating or current drive, and possibly drive instabilities that can expel fast ions causing damage
One of the powerful diagnostics of the fast-ion distribution is known as fast-ion D-alpha (FIDA),1 based on charge-exchange between the injected neutral beam particles and the high energetic deuterium ions, which has been widely used in many magnetic devices
To investigate the fast ion behavior on EAST (Experimental Advanced Superconducting Tokamak), FIDA diagnostic system has been planned and built since 20149 with the diagnostic performance evaluated by an analytical code called simulation of spectra (SOS)
Summary
Fast ions as the main source of heat and momentum can determine the efficiency of heating or current drive, and possibly drive instabilities that can expel fast ions causing damage. One of the powerful diagnostics of the fast-ion distribution is known as fast-ion D-alpha (FIDA), based on charge-exchange between the injected neutral beam particles and the high energetic deuterium ions, which has been widely used in many magnetic devices.. To investigate the fast ion behavior on EAST (Experimental Advanced Superconducting Tokamak), FIDA diagnostic system has been planned and built since 20149 with the diagnostic performance evaluated by an analytical code called simulation of spectra (SOS).. This paper will focus on the validation of FIDA measurements performed using MHD-quiescent discharges in 2015 campaign. To validate EAST FIDA spectrum measurements, two codes have been applied to calculate the Dα spectrum: one is SOS, and the other is fortran version FIDASIM Monte Carlo code on the basis of the fast-ion distribution provided by the TRANSP/NUBEAM simulations. IV will discuss the detailed comparisons of predicted and observed spectra
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