Some Studies on Regenerative Beam Extraction in Synchrocyclotrons

In this paper it is shown that the extraction efficiency in a synchrocyklotron can be increased considerably by selecting proper values for the internal circulating beam parameters. A good energy homogeneity and a high microscopic duty cycle can be achieved simultaneously. A calculation for some relevant radial amplitudes and energy gains/turn gives the energy diagram in fig. 11. From this it can be found that, if the internal beam is composed of 0.4 - 0.6 cm incoherent radial amplitudes and if the useful acceleration voltages are 7.2 - 10.6 kV, the gross extraction efficiency is 40 % for an energy spread of 300 keV. The duty cycle will be about 20 %. These results are valid if the vertical amplitudes are small so that the median plane motion program is correct.