PRODUCTION AND OPTICAL-PROPERTIES OF AN UNSCREENED BUT LOCALIZED MAGNETIC-FIELD

A technique is described of using current carrying coils to produce a magnetic field that is well localized, falling off quickly with distan ce. The basis of the technique is that the first four magnetic multipo le moments of the system are arranged to be zero. The deflection and e lectron optical properties of this type of field are then investigated . It is shown that a beam that initially converges to a point on the a xis of symmetry of the field will be deflected in such a way that it s till passes through the axis. Similarly, a beam originating at the axi s will be asymptotically radial but with a changed direction. (C) 1996 American Institute of Physics.