EFFECTS OF PROTON AND ALPHA-IRRADIATIONS ON PERMANENT-MAGNETS

The magnetic flux loss induced in sintered Nd-Fe-B permanent magnets b y proton and a irradiation has been measured. The irradiations have be en made with 14-20 MeV protons and with 56 MeV a particles. The depend ence of the magnetic flux loss on the temperature, external magnetic f ield, and on the particle energy has been studied. An earlier theoreti cal model of the magnetic damage is refined to take into account the e ffects of the external magnetic field as well as the shape of the magn et sample. The good agreement between the experimental and theoretical results supports our theoretical model according to which the local h eating induced by particle irradiation causes the magnetic flux loss.