Influence of hydrocarbons on vibrational excitation of H sub(2 molecules)

The influence of light hydrocarbons on vibrational excitation of H sub(2 generated in a special source of excited molecules has been studied. Molecule dissociation on the hot tungsten filament and atom recombination on cooled walls is used for the production of molecular excitation in the source. Specific influence of CH) sub(4), C sub(2H) sub(4) and C sub(2H) sub(6) on vibrational distribution of hydrogen molecules from the source is presented here. Production of vibrationally excited H sub(2 molecules due to the thermal dissociation on the hot filament is observed when C) sub(2)H sub(4 (ethene) and C) sub(2)H sub(6 (ethane) are introduced alone in the source. These molecules appear to be produced by direct process on the hot filament in the case of ethene while in the case of ethane H) sub(2)(v) is produced by the similar process as for H sub(2. Production of H) sub(2)(v) is not observed when only CH sub(4 is introduced into the source. In this case vibrational relaxation of H) sub(2)(v) is observed when CH sub(4 is introduced into the source in addition to H) sub(2). Studied processes are relevant for the modelling of edge plasma in tokamaks.