METALLIC ION GENERATION FROM CERAMIC RODS BY ECR ION-SOURCE AND THERMODYNAMIC FEATURE OF VAPORIZATION

Metallic ion generation from eight kinds of ceramic rods such as Al2O3 , Mo2C, BN was examined by an ECR ion source with a direct insertion m ethod, and stable ion beams were observed from six. Vapor pressure of possible products from a solid phase or a solid-liquid condensed phase of the examined materials was evaluated by thermodynamic calculation and ranged over more than nine orders of magnitude at high temperature s. A clear correlation was found between the beam stability of metalli c ions and the surface condition of the rod ends exposed to the plasma , and it is completely explained by the magnitudes of the calculated v apor pressure. This indicates that the vaporization process can be und erstood as sublimation, Sputtering of the ceramic rods by ECR-plasma i ons is considered not to be able to provide sufficient vapor pressure of metallic elements because of the low ion energy close to the sputte ring threshold energy.