Impurity influx studies in the RFX reversed field pinch

The spectroscopic methods adopted to diagnose impurity and hydrogen influxes into the RFX plasma are described and the results of the observations are discussed. The impurity emission lines are currently monitored by means of narrow band interference filters and photodiode array equipped spectrometers, both absolutely calibrated. Influxes of carbon and oxygen are deduced from measurements of C II and O II lines and are related to the impurity content in the plasma core. Molecular band emission observations show a screening effect of the chemically sputtered products. The influx measurements are carried out over different viewing chords showing strong asymmetries in the plasma wall interactions, observed also by CCD cameras and related to strong magnetic field errors.