Effect of magnetic material on the good field region of an accelerator electromagnet

In a low magnetic field, the choice of the magnetic material can affect the good field region, the spectra in which the magnets can work normally. The magnetic field around an electromagnet was modelled using a POISSON program with iron DT4 and steel A3 as the magnetic materials. The model was used to design a compact electromagnet which is able to work in the maximum good field region with the electromagnet in a circular accelerator as an example. The results show that, for the same structures, an electromagnet made of iron DT4, which as a greater permeability, has a good field region with radius 38 cm, which is 20 cm bigger than for an electromagnet made of steel A3. Therefore, larger permeabilities give more uniform magnetic fields and, thus, larger good fields.