Özet:

Rare-earth permanent magnets are widely used in the accelerators of charged particles. However, the magnetic performance under irradiation remains a key issue for the most high energy applications such as accelerators with the energy up to 10 MeV. The aim of the work was to assess radiation and magnetic stability of Sm-Co and Nd-Fe-B permanent magnets under the direct electron irradiation with the energy of 10 MeV and bremsstrahlung. Sm-Co and Nd-Fe-B permanent magnets were produced by powder metallurgy method including PLP for the latter. The absorbed dose imposed by electron beam was 16 Grad (the total flux of electron per 1 cm2 was 1.4х1017) and 160 Grad. The radiation activity of both Nd-Fe-B and Sm-Co magnets was within the acceptable limits after the irradiation. This makes rare-earth magnetic materials suitable for such applications. In order to avoid overheating during electron irradiation, magnets were cooled with the water (T=38 °С). In order to estimate the changes in magnetic flux, the integral of the 3D interpolation normal component of magnetic flux was used. Calculated S parameter measured in arbitrary units was chosen as integrated z-component of magnetic flux. It was shown that magnetic flux of Nd-Fe-B magnets became 0.92 and 0.717 of initial values for 16 Grad and 160 Grad correspondingly, but the magnetic flux of Sm-Co magnets had no change to the same absorbed doses. Thus, Sm-Co magnets were chosen for simulating and designing magnetic system for electron beam analysis of a technological accelerator with energy up to 10 MeV. The distance between the poles of the magnet was 25.25 mm. The highest magnetic field inside the magnetic system was 0.3110 T. The effective distance was 33.53 mm. The measured parameters of the magnetic system based on Sm-Co magnets agreed with the simulation experiment. Magnetic system can also be used to adjust the accelerator in the energy range up to 10 MeV.

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