An aluminium RF acceleration chamber for the ring cyclotron

A prototype of the variable high frequency beam acceleration chamber for the ring cyclotron was made using aluminium. The shape of this chamber is ''cake-cut'' and its volume is about 25 m3. Aluminium was selected because of its swift decay of radioactivity caused by neutrons, high electric and thermal conductivities, and its perfect non-magnetism. As for the degree of the vacuum, 1 x 10-7 Torr has been attained. An excitation voltage higher than 200 KV has also been attained. This report summarized the design and construction of this prototype chamber together with many experiences and the results of experiments mainly from the view points of vacuum technology. (Aoki, K.)