A proposal for linear regenerative extraction from the Birmingham radial-ridge cyclotron

This machine is intermediate between a conventional cyclotron and synchrocyclotron as far as separation of successive orbits is concerned. Substitution of the appropriate values of v r and v z in Le Couteur's linear theory gave results which appeared to justify more detailed computation. This was carried out in two stages. The first stage was concerned with the validity of this theory when the machine has a periodic structure, when the peeler and regenerator fields have curved “toes”, and when the dee voltage is applied. It was restricted to radii at which flux-fringing was inappreciable. An idealized model of the magnetic field, which assumed a trapezoidal azimuthal variation, was used throughout. Several sets of trajectories, each comprising approximately 40 orbits, were computed. Differences from the results of the simple theory were considerable, but not such as to destroy its usefulness. The second stage was concerned with the crucial question of the effects of flux-fringing. It consisted of a similar set of calculations at larger radii. The results show that suitable turn separations combined with vertical stability may be obtained at radii large enough to permit extraction. An estimate of extraction efficiency is given. In the interest of flexibility, it is intended that electrostatic devices will be used for the peeler, regenerator, and deflector channel.