Elementary plasma spectroscopy

Abstract

The preceding chapters have shown that the widths, shapes and intensities of spectral lines depend on the temperature, pressure and electron density of the environment of the atom or molecule, as well as on its intrinsic properties. If the broadening and other physical processes are properly understood and the necessary atomic parameters are known, the spectral lines can give information about the physical conditions in the emitting or absorbing gas or plasma. In laboratory conditions spectroscopic techniques have the advantage over some other methods - those involving probes, for example - that they do not interfere in any way with the plasma, and in the early days of plasma physics spectroscopy was an important diagnostic tool. Other optical diagnostic techniques using lasers and masers have now supplemented and to a considerable extent superseded the purely spectroscopic ones, but there remains an important role for spectroscopy in determining the physical processes going on in the plasma. Moreover, understanding of laboratory plasmas is an important prerequisite to the use of spectroscopic methods on astrophysical plasmas for which no alternative methods are available.