IOP Publishing, Journal of Physics: Conference Series, 1(1316), p. 012019, 2019
DOI: 10.1088/1742-6596/1316/1/012019
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Abstract Low gradient magnetic holding fields are required for maintaining the polarization of polarized 3He, as diffusion though non-ideal gradients can cause total relaxation rates much greater than the intrinsic total 3He relaxation rate of a particular 3He cell in optimal conditions. For neutron scattering applications we often rely on µ-metal cavities to provide a degree of shielding from the many other sources of magnetic fields and gradient experienced on a typical neutron instrument. The JCNS utilizes two concepts for such cavities, one based on inexpensive plastic-bonded magnets to provide magnetic flux, and the other based on field coils wound on the sides of the µ-metal cavity. 2 different sized of permanent magnet cavities and three different geometries of coil-based cavities have been produced. Both types of boxes will be presented with magnetic design as well as mechanical construction details along with the achieved performance of the constructed devices.