Investigation of the rf-ion source RIG 10 for neutral injectors

In comparison to dc-ion sources our rf-source RIG 10 has some advantages (no discharge electrodes immersed in the discharge plasma; homogeneous beam profiles; simple assembly etc). The profiles of the current density and the radial distribution of the electron temperature have been measured by floating double probes in dependence on a superposed external magnetic field. The radial current density profiles depend on the chamber length, the discharge pressure, and the discharge power. The ion current density increases linear with the discharge power. By superposing the special inhomogeneous axial magnetic field (some 10-4 Tesla) we reached at 6 cm vessel length very plane radial density profiles (better than 5%) over a cross-section of about 7 cm with current densities of 280 mA/cm2 (at 4,5 kW rf-discharge-power). A simple theoretical model has been developed explaining the discovered dependencies. Preliminary results of an ion extraction system (similarity laws) are given. (author)