- Warm bore superconducting magnet
Pre info notice
Preliminary publication of specification is 1/26/2023, Place of execution Skåne län.
The magnet will be used to perform scientific experiments with high magnetic field on various neutron-scattering instruments, with a particular focus on the vertical sample reflectometer ESTIA, and small angle neutron scattering (SANS) diffractometers LOKI and SKADI. Neutron experiments involve placing a sample (generally of a volume around 1 cm3) inside the magnetic field produced by the magnet at a certain temperature while exposing it to a neutron beam. The field must be stable over a long period of time (>24 h) without drifts. The asymmetric magnet will be placed on different instruments at ESS; therefore it must be portable when cold, at zero field and not energised. Sample temperature will be controlled by cryostats that fit within the bore of the magnet, principally helium flow cryostats.
The warm bore magnet will be used to perform scattering experiments with and without polarised neutrons at different instrument locations. Its principle mode of use on ESTIA will be in combination with guide fields and supermirror analysers. These guide fields will ensure polarisation transport to the sample position. Kinematic mounts will ensure repeatable positioning of the magnet on every instrument implying the sample position must be centred within the magnet with similar accuracy. ESS will design the adapter to the kinematic mounts (allowing for insertion of a magnetic force measurement device without changing the position of the magnet). Accurate reference features on the magnet body to determine position and orientation, along with attachment features (e.g bolt holes) for the adapter must therefore be provided, in consultation with ESS.
The tenderer will provide the detailed technical design of the magnet, a complete list of ancillary equipment necessary to operate it, a list of the materials certificates, technical and operating manuals, instrument controls, and appropriate software for the remote operations of the equipment stand-alone and via the neutron instruments’ control software. The tenderer will also provide a detailed study of the fringe magnetic field including the fringe-field gradient as specified in the specifications tables of section 6. Coil-defining files will be provided so that gradients and forces can be subsequently calculated. The magnet must be designed to
withstand forces up to 1000 N due to magnetic material in the vicinity. The exact limits must be specified by the tenderer.