The Optimization of the Central Region Electric Field for the Nrdl Cyclotron

摘要

Results of studies of the central region accelerating system employing the UCLA type 'dees-in-the-valleys' are presented. It is shown that a 90 deg. dee tip in conjunction with an adjustable puller best satisfies the requirements of a variable energy, multi-particle, isochronous cyclotron. The results of computer calculation for programmed orbits show that this geometry yields good orbit centering and satisfactory radial beam quality. The base width of the acceptable ion beam in the first harmonic mode is about 60 deg. at the start and broadens to 90 deg. during subsequent acceleration. In the third harmonic mode, on the other hand, the phase width is 30 deg. initially and subsequently contracts to 25 deg. Orbit details, positions of the source, puller, and defining slits are also described. (Author)