Magnetic focussing for isochronic cyclotron - includes improvements to secondary airgap which permit fine adjustment of magnetic field

摘要

The magnetic focussing device for isochronic cyclotron has the secondary airgaps present on at least their periphery, and a non-uniform thickness. The annular edges have a stepped profile, the highest step (52) being at the periphery of each of the circular platforms (20, 21). The annular edges have respectively a first peripheral step (52) and a second step (51), these steps forming two adjacent projecting concentric rings. The circular extremities (A) of the block (3, 4) respectively rest on the first step (51). Circular coils are situated inside the secondary air-gaps to correct the magnetic field variations.