MEASUREMENT OF PLASMA DENSITIES BY VACUUM ULTRAVIOLET ABSORPTION SPECTROSCOPY

摘要

Plasma densities are usually measured by determine ing the electron densities by a variety of techniques. Under certain circumstances, it is desirable also to know the identities of the associated ions as well as their densities and location relative to the electrons and to know what and how many neutral atoms and molecules are present. A straightforward means of accomplishing this at least quali¬tatively is through vacuum ultraviolet absorption spectro¬scopy, since most ions, atoms, and molecules have their resonance absorption spectrum lines in this region. Quanti¬tative measurements require the knowledge of oscillator strengths and line shapes for the respective resonance lines. Such knowledge is by no means complete, but enough in-formation is available to make this technique a useful one. The general considerations in applying this technique are discussed, along with a numerical example using the 1470 A resonance line of xenon.