A cyclotron with a radially travelling magnetic wave

Abstract

Possible designs for a cyclotron with a radially travelling magnetic field wave are considered and relations between the parameters are deduced. One or more radially travelling waves can be produced in the magnet gap by using separate ring windings fed from an a.c. source. Two possible systems are proposed. In the first, the travelling wave is responsible for accelerating the particles; in the second, a travelling field is superimposed on the normal fixed field and the particles are accelerated in the resulting total field. A region of stability (1 > n > 0) can be obtained and this must move outwards at the radial velocity of the particles. Stability is possible if the absolute field strength increases sharply from the inside to the outside of the acceleration zone. In principle, the system would allow the production of particles with energies as high as desired. In spite of the cyclic nature of the action, the mean beam intensity could well be better than that from a synchrocyclotron because of better focusing. Some approximate calculations are presented for accelerators of this type designed to produce various energies. It is shown that for a given energy the weight and size can be substantially less than for other types of accelerator.