In collaboration with the instruments the Sample Environment and Characterization group develops pulsed high magnetic field coils as well as constant field magnets. These devices are available as a drop-in sample environment option for MID and SCS instruments.
Magnetic Sample Environments
Compact Pulsed Magnets
The approach is to develop resistive copper coils that generate a high magnetic field (15 T) in a small bore (Φ10 mm). As resistive coils generate significant amounts of heat (up to 0.5 MW) the coil is operated in millisecond-pulses that match the XFEL bunch-train. After one magnetic pulse a wait-time of ~10 seconds is needed before the coil has cooled sufficiently (in a LN2 bath) to allow another high magnetic field pulse.
In the bore of the miniature coils a sample-stick with helium-flow cryostat is inserted. Sample cooling from 10 - 300 K is possible. A horizontal split between coil halves allows diffraction/scattering measurements.
The components specific to the MID main vacuum chamber are illustrated here.
Sample manipulation:
- XYZ translation
- Θ rotation (vertical axis)
Sample mounting:
- Quick exchange via loadlock
- Sample in higfh vacuum (HV)
Sample cooling:
- 10 – 300 K via helium-flow cryostat
Constant field (DC) magnet
Constant low magnetic fields (up to 0.35 T) are required by SCS as an addition to their main Fast-Solid-Sample-Scanner (FSSS) sample environment. Our approach here was to develop a DC electromagnet for use in UHV that fits around the design of the FSSS. In addition the DC electromagnet can be moved in or out of operation by a linear translation stage. In order to maximize the constant magnetic field strength we cool the yoke internally via a recirculating water-chiller.
The illustration shows how the DC electromagnet (in green) integrates with the FSSS. The DC magnetic field is parallel to the X-ray beam and perpendicular to the square sample holder (5cm x 5cm). The bulky water-cooling lines include an extra rough-vacuum shield as a safety-barrier against potential water-leaks.