Patent ID: 8907594

Claim:
A system comprising: a support; and a particle accelerator mounted to the support for producing an output beam of charged particles in use, the particle accelerator comprising at least one annular superconducting coil for generating a magnetic field in use; means for cooling the superconducting coil in use, the cooling means comprises: a cryogen chamber situated local to the at least one superconducting coil for containing cryogen in use, the cryogen does not directly contact the at least one superconducting coil, thermally conductive means arranged to facilitate heat transfer from the at least one superconducting coil to the cryogen chamber to vaporize cryogen contained therein in use and thereby remove heat from the at least one superconducting coil, the thermally conductive means being highly thermally conductive at cryogenic temperatures, and a cryogen recondensing unit in fluid communication with the cryogen chamber, wherein vaporized cryogen may flow from the cryogen chamber to the cryogen recondensing unit to be recondensed in use before returning to the cryogen chamber; wherein the system is arranged such that the particle accelerator is movable to change the direction of the output beam in use, wherein the particle accelerator is rotatable to permit movement of the output beam through an arc in use; and wherein the cooling means is operable to cool the superconducting coil as the coil rotates about its axis upon said movement of the particle accelerator in use, wherein the cooling means including the cryogen chamber, recondensing unit and thermally conductive means is arranged to rotate with the coil as the coil rotates about its axis.