IMPURITY BEHAVIOR IN HELIOTRON E-PLASMA

Observations of resonance lines in the 150 to 400 Angstrom spectral ra nge provide useful information regarding the behaviour of impurities i n a laboratory plasma. Heliotron E emission spectra were recorded usin g a time-resolved VUV spectroscopy system, and line emission in this r ange was found to be dominated by impurity radiation from oxygen, carb on, iron and nickel. The magnetic axis of the plasma can be moved rela tive to the vessel wall, and so a study is presented of the effects of a shift in magnetic axis on the evolution of VUV impurity radiation f rom different ionic states. Differences in behaviour of different stat es are analysed by the comparison of observed spectra with plasma coro nal equilibrium models.