IMPURITY INFLUX STUDIES IN THE RFX REVERSED-FIELD PINCH

The spectroscopic methods adopted to diagnose impurity and hydrogen in fluxes into the RFX plasma are described and the results of the observ ations are discussed. The impurity emission lines are currently monito red 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 a re related to the impurity content in the plasma core. Molecular band emission observations show a screening effect of the chemically sputte red products. The influx measurements are carried out over different v iewing chords showing strong asymmetries in the plasma wall interactio ns, observed also by CCD cameras and related to strong magnetic field errors.