Accession Number : AD0701205

Title :   UEBER DIE BESETZUNG DER ROTATIONSZUSTAENDE VON OH UND C2 IN NIEDERDRUCKPLASMEN (Rotational Distribution State of OH and C2 Radicals in Low Pressure Plasmas).

Corporate Author : DEUTSCHE VERSUCHSANSTALT FUER LUFT- UND RAUMFAHRT E V STUTTGART (WEST GERMANY)

Personal Author(s) : Meinel,H. ; Krauss,L.

Report Date : 09 AUG 1968

Pagination or Media Count : 20

Abstract : The rotational distribution of the radicals OH and C2 has been investigated in emission in different electronic and vibrational states using a hollow-cathode discharge and a low-pressure carbon arc. Observed diviations from the Boltzmann population are explained by the existence of two groups of molecules of different temperature, both--the 'hot' and the 'cold' ones--being characterized by a Boltzmann distribution concerning the rotation. The reason for the appearance of two groups is interpreted in terms of two different excitation mechanisms: The cold group arises from a pure excitation of already existing diatomic radicals; the rotational temperature corresponds to the gas temperature. The hot group, on the other hand, is present if the radicals under consideration are dissociation products of polyatomic parent molecules like H2O and C3. This hot group is characterized by a higher excitation temperature, which is shown to be related to the electron temperature. The relative particle numbers in the hot and the cold group vary between 7 and 10 for both non-equilibrium plasmas under different experimental conditions; in the case of C2 the emission of the hot group can even be suppressed completely. (Author)

Descriptors :   (*PLASMA MEDIUM, *MOLECULAR ENERGY LEVELS), (*FREE RADICALS, PLASMA MEDIUM), (*CARBON, FREE RADICALS), ROTATION, EXCITATION, WEST GERMANY

Subject Categories : Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE