Impurity behaviour in the EXTRAP-T1 pinch experiment studied by VUV spectroscopy

Vacuum ultraviolet observations from a low-q, high-beta pinch plasma (Extrap-T1) are presented and related to other plasma parameters. Qualitative analysis of the line emission from low ionization stages of carbon and oxygen, which dominate this spectrum, gives information on the ionization stage distribution and on the power balance. It is found, that the ionization stages reach a steady state during the equilibrium phase of the discharge, and that line radiation does not dominate the power balance. The energy balance of the plasma discharge is analyzed from the vacuum ultraviolet line and continuum spectroscopy data. Furthermore it is found, that the time behaviour of the plasma resistance can be understood using the results from the spectroscopic observations.