BEAM CURRENT MEASURING INSTRUMENT AND BEAM CURRENT MEASURING METHOD USING SAME

摘要

A beam current measuring instrument and method for measuring a beam current with high sensitivity and with high noise resistance. The beam current measuring instrument comprises a magnetic shield portion (8) for shielding against the external magnetic field and a magnetic sensor (2) disposed in a shielded space produced by the magnetic shield portion. The magnetic field produced by a beam current to be measured is measured by means of the magnetic sensor,. The magnetic flux-feedback current conversion factor of the magnetic sensor is 8x10<-15> WB/A or more.