Patent ID: 6452169
Filing Date: 2002-09-17
Classification: H01J

Abstract:
A Wien filter provided with electrodes for generating an electric field, and magnetic poles for generating a magnetic field, said electrodes and magnetic poles being positioned around and having a finite length along a filter axis, and being positioned around the filter axis such that electric and magnetic forces induced by the respective fields and exerted on an electrically charged particle moving substantially along the filter axis at a certain velocity, take substantially an opposite direction to one another and are directed substantially perpendicular to the particle's direction of movement through the filter, said filter having along its axis two ends determined by the finite length of the electrodes and magnetic poles, and said ends both being terminated by a closing plate made from a material of low electric and magnetic resistance, which is positioned substantially transversely to the filter axis and is provided with an aperture around the filter axis to allow the particle to enter into and exit from the filter, wherein the mutual distance of the electrodes and the mutual distance of the magnetic poles is larger or approximately equal to the mutual distance of the closing plates.