Observations of High-Density Corrections to VUV Line-Wing Shapes in a Plasma with a Few Particles Per Debye Sphere

Extract

Observations of high density effects on spectral line shapes are reported for neutral, singly- and doubly-ionized emitters in a dense plasma with a small number of particles per Debye sphere. The source used in these experiments was a well-diagnosed linear pinch,run in argon, producing a plasma with electron density between 0.5 x 10¹⁸ and 3 x 10¹⁸ cm^–3, and temperature between 22,000 K and 27,000 K.

Satellite-like features observed in the wings of H I Lyman α are attributed to the influence of unbound quasimolecular states. A number of the satellites are apparently due to states of H–Ar⁺ (similar to two such Lyman α satellites observed by Preston 1977). However, it seems likely that at least one of the satellite features observed should be attributed to the influence of Ar⁺⁺ perturbers. Such quasimolecular features might be expected to become increasingly important at higher densities, and for more highly-ionized perturbing ions.