THERMAL PLASMA SOURCE OF HYDROGEN ATOMS AND IONS

-- Un arc cascade est utilise comme source d8hydrog&ne et d8argon. Le plasma est realis & entre 0,l et 1 bar et expans & dans une chambre h pression reduite. Les mesures sont effectu&es & lraide dlune double sonde de Langmuir et drun spectrom&tre de masse. Les rgsultats des mesures sont discutes. Les phOnom5nes mol&culaires, tels que les &changes de charge et les recombinaisons dissociatives, ont &t& dgfinis comme des processus importants. Abstract- A cascade arc is used as a source for a hydrogen/argon particle beam. The plasma is produced at thermal plasma conditions in the pressure range of 0.1 to 1 bar. It is expanded with a high velocity into a vacuum chamber. Measurements with a Langmuir double probe and with a mass spectrometer are performed. The resulting parameters of the plasma and the extracted ions are discussed. Molecular processes as charge exchange and dissociative recombination appear to be important. With a cascade arc a thermal plasma is produced. By allowing this plasma to expand into a vacuu