Some model magnet measurements and their application to the design of a 70-inch spiral ridge cyclotron
The factors considered in establishing an economic magnet design for the proposed 70 in. spiral ridge cyclotron for A.E.R.E. Harwell are presented, together with an account of the supporting experimental programme on a 1/7th scale model. The effect of the ridges is allowed for by considering a system with smooth poles and an equivalent mean gap, this gap being determined by experiments with a pole configuration which is likely to be similar to the one finally chosen. Although the cyclotron is planned for a maximum field of 17 kgauss the experiments were limited and aimed to achieve an optimum design at 16 kgauss. The model was sufficiently flexible in assembly to allow simple variations in iron circuit cross sections and coil dimensions, and graphs are given showing the effect of a number of parameters of general interest such as coil length, diameter and pole projection.