RARE EARTH PERMANENT MAGNETS FOR CRYOGENIC SPACE APPLICATIONS

摘要

We present results of proton irradiation and performancerntests on SmCo and NbFeB permanent magnets under ambientrnand cryogenic conditions carried out at the ProtonrnIrradiation Facility (PIF) in Switzerland and at the Max-rnPlanck-Institut fur Astronomie. Such rare earth permanentrnmagnets are commonly used in a variety of spacernmechanisms, e.g. in actuators and sensors. The qualificationrnprogram reported here is performed in the context ofrnthe James Webb Space Telescope (JWST) mission. ForrnJWST the magnets are used in an electromagnetic torquernmotor and a magnetoresistive position sensor for opticalrnwheel mechanisms of the MIRI and NIRSpec science instruments.rnSm_2Co_(17) and NeFeB magnets were irradiatedrnwith a 50 MeV proton beam with total ionising doses ofrn42.5 krad-Si and 760 krad-Si at cryogenic and room temperatures.rnNo significant flux loss could be found.