Beam current measuring instrument and beam current measuring method using same

摘要

The invention provides a nondestructive measuring method and measuring apparatus that assures a high noise immunity and is capable of performing high-accuracy beam current measurements. The inventive beam current measuring apparatus includes a magnetism shielding part for shielding an external magnetic field and a magnetic field sensor arranged in the shielding space generated by said magnetism shielding part, said beam current measuring apparatus measuring, by using said magnetic field sensor, a magnetic field where a beam current to be measured is generated, characterized in that said magnetic field sensor has a magnetic flux/feedback current conversion coefficient of 8x10^-15 Wb/A or above.