Magnetic shielding in ultrahigh vacuum systems: Using a computer code to design a shield for an electron energy loss spectrometer

Using a computer code, a magnetic shield has been designed for an electron energy loss spectrometer. Two methods are used to approximate the effect of pumpout holes on the internal magnetic field. These approximations show that the ambient magnetic field can be attenuated by a factor of approximately 1000 in the sample region of the spectrometer. Actual tests of the constructed shield confirm the approximations.