Spectroscopy and impurity behaviour in fusion plasmas

The authors review spectroscopic work and impurity behaviour in laboratory plasmas devoted to controlled nuclear fusion research. A necessary prerequisite for this is a discussion of the atomic physics (rate coefficients, ionisation models and spectral emission) involved in the interpretation of plasma spectroscopic data. The largest part of this review is concerned with spectroscopic work in magnetically confined Tokamak plasmas and laser-produced, inertially confined, plasmas, since these two approaches have received the greatest attention. In Tokamak plasmas, impurity radiation constitutes an important loss process; it is therefore necessary to find ways to avoid impurity contamination. On the other hand, in inertial confinement, 'impurities' are necessary to absorb the beam energy and are, moreover, an essential diagnostic tool, particularly for the compressed material. Spectroscopic work of fusion interest in other laboratory plasma devices is also briefly reviewed.