Abstract: An improved superconducting cyclotron (10) particularly useful for medical or therapeutic purposes is described. The vessel (105) for liquified gas surrounding superconducting coils (101, 101a) is provided with a capillary tube (200) joined to a semi-circular tube (123) leading into an exit tube (201) from the vessel which provides Joule-Thompson effect cooling upon flow of a portion of the liquified gas in the vessel into the semi-circular tube. The cooling maintains the liquified gas in the vessel in a subcooled condition to prevent boiling. The liquified gas from the exit tube can be used to cool the magnetic poles (103, 104) and then can be vented to the atmosphere or recycled. A special external magnetic yoke (102) configuration for weight reduction is described. Also described is a flexible hose (37) for supplying the liquified gas to and from the cyclotron which is mounted in a helical coil so as to allow up to a 360.degree. of rotation of the cyclotron.

Abstract: A superconducting cyclotron (10) rotatable on a support structure (11) in an arc of about 180.degree. around a pivot axis (A--A) and particularly adapted for medical use is described. The rotatable support structure (13, 15) is balanced by being counterweighted (14) so as to allow rotation of the cyclotron and a beam (12), such as a subparticle (neutron) or atomic particle beam, from the cyclotron in the arc around a patient. Flexible hose (25) is moveably attached to the support structure for providing a liquified gas which is supercooled to near 0.degree. K. to an inlet means (122) to a chamber (105) around superconducting coils (101, 102). The liquid (34) level in the cyclotron is maintained approximately half full so that rotation of the support structure and cyclotron through the 180.degree. can be accomplished without spilling the liquid from the cyclotron.