The use of solenoid lenses in a two-stage nuclear microprobe probe-forming system

Abstract

Nuclear microprobes typically achieve a demagnification between 20 and 100 by using a single-stage quadrupole multiplet as the probe-forming system. Whilst quadrupole lenses provide the strong field necessary for focusing MeV ions, they also have higher intrinsic spherical and chromatic aberrations, and also higher parasitic aberrations than found in solenoid lenses. Given the fundamentally superior spatial resolution which is attainable using solenoids, their use in a two-stage microprobe system comprising a magnetic quadruplet and a solenoid lens as the first and second demagnifying stages respectively is studied here. Calculated results are compared with a two-stage system comprising two quadruplets and also with an existing single-stage system.