A 15T cryogen free magnet system

We have constructed a number of superconducting magnets which are directly cooled by cryocoolers and can achieve fields up to 15 T at temperatures of about 4 K. No liquid helium is required. The magnets have bores in the rang e of 50-800 mm. The current to the magnet is in the range of 100-240 A. It is carried by HTS conductors from 50-4 K with resistive leads above this te mperature. The bore can be at room temperature or a variable temperature sa mple space can be provided. Due to the exceptionally compact design there i s very good access to the high-field region. The magnetic field can be orie ntated in any direction and the cryomagnet can even be rotated while in ope ration. A patented thermal buffer can be used to allow fast ramp rates to f ield. (C) 2001 Elsevier Science B.V. All rights reserved.