23-57 Pastis 3 for Panther

Pastis3 can generate high homogeneous magnetic fields in any 3D direction thanks to two coils sets tilted from the vertical axes, which can rotate around the vertical axis. Each coil set is composed of four coils, water-cooled in a tight vessel with the vacuum outside. The position of the coils has to be extremely precise. The insert is installed in the vacuum chamber of PANTHER, and supported by the top flange. The sample to measure is in a dedicated cryostat, positioned inside the insert. The cryostat is also holding the two polarized 3He cells that have to be changed daily. For this operation, a lifting system allows to extract the cryostat from the Pastis3 insert and to put it back with high position reproducibility. The materials of the insert are non-magnetic (aluminium, brass…) and are compatible with neutron scattering. The overall dimensions are about 1m in diameter and 1.5m high. Two water-cooled vessels inserted in the vacuum tank maintain four coils each at room temperature, to avoid linear expansion. The precision of the position of the coils is within 0.1 mm to generate an accurate homogeneous magnetic field. The two vessels can rotate by 180° around the vertical axes to turn the magnetic field in the third dimension. The orange cryostat, placed inside a second independent vacuum chamber, can move up and down by using a crane and a guiding system, to access to the two 3He cells, fixed at the bottom of the cryostat. The efficiency of the polarized 3He cells depends on the high homogeneity of the magnetic field. For this reason, the positioning of the coils (ILL will provide the coils) must be extremely precise. The difficulty of the realisation is the machining of large aluminium parts with a high precision.