During the autumn/winter 2020 through to spring/summer 2021, EXTREMAG Senior Experimental Officer Paul Keatley, and Low Temperature Services Engineer Adam Woodgate, have been working with Oxford Instruments Nanoscience Engineer Daniel Cox to recommission a Spectromag SM4000 superconducting magnet for use in all-optical pump-probe and THz emission User experiments.  In recent weeks the magnet has been confirmed to operate over its intended range of +/- 10 T.  At the same time, the base temperature of the variable temperature insert (VTI) was confirmed to remain at 1.4 K or below up to 10 T.  The VTI has been upgraded to feature sapphire windows for THz emission experiments with an out-of-plane field configuration, while pump-probe experiments may be performed with in-plane or out-of-plane fields.  Future capability may also feature the use of the Spectromag’s lambda refrigerator to achieve magnetic fields up to 11 T.  This work has required significant contributions from many parties including; the University of Exeter Technical Services and Estates Services for installing the necessary infrastructure in the basement of the Physics building for a He bath superconducting magnet system; Motivair and INTOHEAT for helium recovery and extractor system installation; Oxford Instruments Engineers for VTI repairs and continuous support and advice during the recommission; and the Physics Workshop Staff for local tooling support and the movement/assembly of a crane to lift/service the Spectromag on the optical table of the EXTREMAG lab.  The EXTREMAG Team are extremely grateful to everyone for their help and continued support that enabled the recommission of the Spectromag for EXTREMAG User experiments.  Thank you!

Spectromag SM4000 10 T superconducting magnet in EXTREMAG lab B2 during He transfer

The magnet helium bath enclosure during the recommission