Patent ID: 8525447

Claim:
A compact, cold, weak-focusing superconducting cyclotron comprising: at least two superconducting coils, centered around a central axis with outer surfaces remote from the central axis, wherein the coils are on opposite sides of a median acceleration plane and have opposed median-acceleration-plane-facing surfaces; a magnetic yoke surrounding the coils and in physical contact with the coils across the outer surface of each coil and across the median-acceleration-plane-facing surface of each coil to substantially reduce or eliminate strain on the coils due to decentering forces and without an intervening cryostat between the magnetic yoke and the coils, wherein the magnetic yoke contains an acceleration chamber, wherein the magnetic yoke is in thermal contact with the superconducting coils, wherein the median acceleration plane extends through the acceleration chamber, and wherein the superconducting coils and the physically coupled magnetic yoke are configured to generate a magnetic field that reaches at least 6 Tesla in the median acceleration plane; a cryogenic refrigerator physically and thermally coupled with the superconducting coils and with the magnetic yoke; and a cryostat mounted outside the magnetic yoke and containing the coils and the magnetic yoke inside a thermally insulated volume in which the coils and the magnetic yoke can be maintained at cryogenic temperatures by the cryogenic refrigerator.