CRYOGEN-FREE SUPERCONDUCTING MAGNET SYSTEM

The invention relates to a cryogen-free superconducting magnet system witha superconducting coil (1) for generating a magnetic field,a vacuum chamber (2) with vacuum chamber walls (3) limiting the vacuum chamber to the outside, anda cryocooler (4) for cooling the superconducting coil (1), the cryocooler comprising a refrigerator with a first stage (21) which is adapted for being cooled to a first temperature and a second stage (22) which is adapted for being cooled to a second temperature, the second temperature being lower than the first temperature, whereinthe superconducting coil (1) is arranged inside the vacuum chamber (2) at a distance from the vacuum chamber walls (3),the superconducting coil (1) is equipped with two superconducting coil connectors (18) which are galvanically connected to two current leads (5) which are fed through a vacuum chamber wall (3) for providing the superconducting coil (1) with an electric current from outside of the vacuum chamber (2),each current lead (5) comprises a first section (6) and a second section (7), wherein the cross-sectional area of the first section (6) is less than the cross-sectional area of the second section (7),the current leads (5) are galvanically attached to the superconducting coil connectors (18) and thermally connected to the first stage (21) of the refrigerator with their respective second sections (7), andthe first sections (6) of the current leads (5) each comprise a cooling arrangement (8) for cooling the first sections (6) of the current leads (5).In this way, a cryogen-free superconducting magnet system is provided in which excess heat load at zero current in the current leads (5) is removed without the risk of thermal runaway.