Properties of Praseodymium Permanent Magnet for Cryogenic Hybrid Magnet

An application of permanent magnet technology to cryogenic hybrid magnets is proposed. The requirement for superconducting magnet may be reduced by generating an additional magnetic field of about 1 T by permanent magnets. While the remanent field of conventional Nd
₂
Fe
₁₄
B magnets decreases at around 100 K due to spin reorientation, Pr
₂
Fe
₁₄
B magnets consisting of praseodymium (Pr) instead of neodymium (Nd) do not show such a decrease. In order to investigate the magnetic properties of the Pr
₂
Fe
₁₄
B and Nd
₂
Fe
₁₄
B magnets, magnetization experiments at a temperature down to 1.4 K were performed. The coercivity of the Pr
₂
Fe
₁₄
B at 4 K was measured as high as 9 T, and the remanent magnetic flux density was estimated at about 1.4 T. On the other hand, the coercivity of Nd
₂
Fe
₁₄
B at 4 K was about 6 T, and the remanent flux density was less than Pr
₂
Fe
₁₄
B magnets. Therefore, Pr
₂
Fe
₁₄
B magnets may be applicable as the field booster in the high-field hybrid magnets. Based on the experimental result, a magnet configuration for an accelerator dipole magnet is also proposed as an example of application.