Development of a miniature 3 axis magnetic field sensor to predict the magnetic stray field influence on electron beams
The desired form of electron beams is generally obtained by the use of magnetic fields in coils by focalisation, deflection, and other. The beam form is also influenced, due to incomplete shielding, by the magnetic environment, which is the sum of stray fields like the earth magnetic field, equipment originating fields, work piece fields. In the literature there is not much information on the effect of these stray fields, the generally given information is an indication of the maximum acceptable field on the work piece. There is a need for a precise and tiny field measuring device and some simple formulas to become aware of the importance of mastering the stray field influence. This paper presents a miniature 3 axis magnetic field probing device and simple rules of thumb to estimate the beam deviation effect. The developed sensor combined with simulation software gives precise prediction of beam deviations. This probing device is a useful tool for the preparation of welding equipment of excellent quality through optimal shielding design for the mastering of the final field. The probing device is also a helpful tool for the diagnostics of shield performance and workpiece demagnetisation quality.