25 Tesla, 32 mm Split Helix Magnet (Cell 5)

The SFH magnet uses similar technology as in other Florida-Bitter designs, except that the conducting helix in the region around the mid-plane is replaced with a solid conductor having four wide optical ports evenly spaced around the perimeter and milled for the largest solid angle collection volume. The magnet features four identical ports radially arranged at 90° intervals around the mid-plane of the 32 mm vertical bore. A cutaway view (see below) of the magnet shows two of these ports, each providing ± 22.5° free-space angular access (in the horizontal plane perpendicular to B) and ± 5.7° access (in a vertical plane parallel to B) to the center of the vertical magnet bore. Two ports are equipped with full size gate valves allowing for convenient replacement of optical windows. The magnetic field is 25 T at the window plane.

The SFH magnet is surrounded by three non-magnetic optical tables, which also support a platform positioned above the magnet. For low-temperature experiments, a LHe4 custom designed cryostat (sample in vacuum) can be installed on the top platform, which provides vibration isolation of the cryostat from the water-cooled resistive magnet. The geometry of the SFH ports and the arrangement of the optical tables allow unprecedented flexibility in the choice of scattering geometries for high-field experiments, and placement of optical and positioning equipment. Various technical aspects of the new magneto-optics setups will be presented.