Cryogenic pulsed ion source with Stirling cycle refrigerator

To improve the purity, repetition capability, uniformity, and turn-on delay of conventional pulsed ion sources, the cryogenic ion source has been proposed. Newly designed pulsed generator, which has a repetition capability of 0.2 H/sub z/, has been constructed. A 5Ω-50nsec coaxial pulse line charged by a 1MV-3.75KJ Marx Generator is used. The diode used in this study is a Br magnetically insulated diode which has a Cu-cryogenic anode of 22cm diameter. The coolant is fed through a spiral transfer tube to retain the electrical insulation, and the cryogenic anode is cooled down to 20K with a cryogenic refrigerator (AISIN CT-01) which has a Stirling Engine with the refrigeration capacity of 15W at 20K. The flashover plasmas of refrigerated materials frozen on the cryogenic anode surface are used as the ion sources. Various ion species such as N/sub 2/, O/sub 2/, and Ar are extracted from them. When the authors use liquid helium as the coolant in place of the refrigerator, H/sub 2/ or D/sub 2/ ice can be used as the ion sources. The quantitative measurements of the purities of the extracted ion beams are performed. The anode plasma production processes of the cryogenic ion source with emphasis on its purity, and the repetition capability of the diode section are discussed