Beam Steering with Quadrupole and with Rectangular Box Magnets

Abstract

The exact field configuration in the aperture of an asymmetrically excited electric or magnetic quadrupole lens is derived. The resulting effectiveness as a combined focusing and steering device for particle beams is analyzed, and the limitations are explored. Simple expressions are obtained for the steering effect. These results are compared to the effectiveness of a rectangular array of current sheets and iron as a steering device. The latter is shown to be superior in many cases.