The influence of plasma parameter variations on the interpretation of spectroscopic flux measurements in terms of particle fluxes is investigated by analytical and numerical methods. In addition to the temperature and density dependence of the local photon efficiencies, transport processes and spatial shifts of the source distribution result in variations of the effective photon yields which are used to interpret measurements. Parameter studies for typical variations of edge conditions of the ASDEX Upgrade tokamak reveal changes by a factor of 3 for the ratio of the particle influx and corresponding photon flux. If fast temporal changes of the plasma density occur, the photon emission basically follows the density fluctuations for frequencies higher than the inverse ionization time, while the fluctuating part of the photon flux is damped for lower frequencies.
Density, temperature and potential fluctuations in the edge plasma of the FTU tokamak