Development of surface-wave ion source using coaxial-type cavity

A compact 2.45 GHz surface-wave ion source has been developed for the production of stable beams from gaseous feed materials. The source has been operated with two different geometries of surface wave generation, that is, a dielectric disk on ground plane structure and a dielectric disk between the parallel plate structure with a holey top plate. The designer can control the intensity of the emitted microwave simply by varying the thickness of the dielectric plate. The sources have been operated with three different thicknesses of the dielectric plate: td=10, 15, and 20 mm. td=10 mm is the optimum coupling condition. Moreover, the ion beam current of the holey-plate structure is 1.5 times as high as that of the dielectric disk structure.