Vacuum UV spectroscopy and impurity behavior in tokamak and stellarator plasmas

An overview of applications of vacuum UV (VUV) spectroscopy to studies of fusion plasmas is presented. This spectral region is usually considered to extend from 10 to 2000 إ. Most impurity studies in core plasmas and in divertors rely on measuring the intensities of the bright resonance lines that lie in this wavelength range. In the core, these data are supplemented by emissions from charge exchange excitation to determine concentrations of fully stripped low-Z ions. Determinations of individual impurity radiative losses and densities are carried out with the aid of one-dimensional codes in which transport coefficients are adjusted until the modelled intensities are well matched to experimental observation. Analysis of divertor spectra presents special difficulties, because of the inherently two-or three-dimensional nature of the radiation patterns. In addition to impurity studies, VUV lines are used to determine electron and ion temperatures, and plasma rotation.