High temperature superconducting magnet system with a high pressure chamber at a cryogenic temperatures for neutron scattering investigations

Abstract

For the DN-12 neutron diffractometer at the IBR-2 reactor of the Frank Laboratory of Neutron Physics, JINR, a cryomagnetic system with horizontal arrangement based on a high temperature superconducting magnet generating a magnetic field of 4.6 T at a current of 290 A was designed, developed and tested. The unique cryomagnetic system is designed to study phases of condensed matter systems with neutron as a function of P,T,H. The configuration of the Helmholtz coil of a high-temperature superconducting magnet made it possible not only to achieve high uniformity of the magnetic field on the sample > 99.68 % in the central zone of the magnet ± 20 mm around its center, but also to provide 360° access to the central region of the magnetic field in a perpendicular plane on the sample with the exception of four sectors of 12 degrees each due to the spacer design pillars. The magnetic axis is passing through its center. This configuration allows to simultaneously detect the neutron scattered on the sample using two neutron detectors positioned at angles of 45° and 90° to the axis of the neutron beam, respectively.

The HTS coils are double pancakes cooled via heat conduction using a Gifford-McMahon (G-M) cryocooler. The dimensions of the magnet, inner diameter 80 mm, outer diameter 200 mm, distance between the coils 40 mm, allow the installation of an inner cryostat with high pressure chamber that is cooled using the second G-M closed-cycle cryocooler and can create a pressure on the sample 10 GPa. The temperature of the magnet windings can vary in the range of 16–40 K depending on the temperature of the high pressure chamber with the sample that is regulated in the range of 3.6–150 K. The developed cryomagnetic system has reached all design parameters and is ready for testing on a neutron beam.