Hall-Probe Calibration Stand at European XFEL
A LabVector five-axis mechatronic positioning system now aligns Hall probes in a new calibration setup at European XFEL, covering magnetic fields from −2 T to +2 T and temperatures from 300 K down to 4 K.
The challenge
European XFEL characterises its undulators, both permanent-magnet and superconducting, by mapping their magnetic fields with Hall probes. These probes must be calibrated close to the temperature at which they are used, and for superconducting undulators that means cryogenic temperatures. A calibration stand was needed that could position a probe on a cold finger inside a dipole magnet with micrometre and arcsecond accuracy.
Our solution
- Five-axis mechatronic positioning system: three motorised linear stages with 0.5 µm resolution and two high-precision goniometers with 0.45″ angular precision
- Precise alignment of the Hall probe on a cold-finger cryostat in the gap of a dipole electromagnet (−2 T to +2 T)
- Automatic field scans on a regular grid, for example 21 × 21 points with a 0.2 mm step, to find the optimum probe position
- Operation across the full temperature range from 300 K to 4 K
The result
The setup has been built and commissioned, and the first measurements are complete. The first two-dimensional map of the Hall-voltage response was recorded at 2.055 T and 70 K, and the positions of the field extrema are now used to set the optimum probe position for calibration. The stand is planned to become the standard calibration facility for Hall probes used in undulator measurements at European XFEL.
The setup and first results were presented at the 17th International Particle Accelerator Conference (IPAC’26), poster MOP7123.
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