Interpretation of duoplasmatron-type ion sources from a model of the discharge

The performance logical improvement of these sources needs a precise knowledge of the emitting ionized medium, on which the whole of the properties is depending. Ion production mechanisms have been studied in the discharge together with their transport towards the extraction hole. The source properties are described, in a new manner, as a function of the discharge modes. The discharge is characterized by the existence of a mode change, related to anode column neutral atom lowering in anode column (arc starvation). The complementarity of probe measurements and the energy spectra analysis of the charges emitted by the anode hole allowed to get the potential axial profile, to discover an electric energetic electron beam extracted from cathodic plasma by the striction shealth potential difference and to determine the electron density radial profile in the anode column. Result analysis allows to get a simple scheme of plasmas and laws controlling them in each of the important modes. The density and potential axial theoretical repartition has been calculated as a function of independent parameters-anode pressure and arc intensity and of three secondary parameters characterizing the energy exchange (electron temperature) and magnetic field topography. The agreement between model predictions and experimental variations for source properties -more specifically gas nature and geometry- allow to give the duoplasmatrons sources similitude rules. The discharge model has allowed to interpret the luminous emission spectra from the anode column. It has been shown theoretically that the peculiar conditions of ionization and excitation allow to use the column as an amplifier medium in the optically field. This plasma has been used successfully as an active medium for an ionic laser in a continuous mode