The radiation of hydrogen molecules in the divertor of fusion experiments isproposed to be a sensitive diagnostic method for electron temperature (Te)in the range between 1 and 7 eV. A collisional-radiative (CR) model for H2was used for the prediction of vibrational population in the ground state ofthe molecule, depending on electron temperature. In addition, the model wasmodified in order to enable diagnostics for deuterium. Applying theFranck-Condon principle and vibrationally resolved excitation ratecoefficients the population was transferred into the upper state of theFulcher transition (d3Πu-a3Σg+). Onthe other hand, the relative population in the excited state can be deriveddirectly from the emission spectra of the diagonal Fulcher bands. Results ofhydrogen discharges in ASDEX Upgrade will be presented, which show that thestrong variation in Te during the discharge correlated with the degreeof plasma detachment. The transferability for deuterium will be demonstratedby discussing results of deuterium discharges including hydrogen injections.Due to the spectroscopic technique, the derived Te represents thevolume where the radiation of the molecules originates.
Characterization of the deuterium recycling flux in front of a graphite surface in the TEXTOR tokamak