Immersion probe-forming system as a way to the compact design of nuclear microprobe

Abstract

The paper discusses the feasibility of constructing a compact nuclear microprobe combining ion acceleration and ion probe formation. In the design proposed a mass-separator, object-and angular collimators are placed at the accelerating tube entrance. Immediately behind the accelerating tube a quadruplet of magnetic quadrupole lenses is positioned to provide final ion probe formation at the target. Using the accelerating tube, which is an extended electrostatic immersion lens with axial symmetry together with magnetic quadrupole lenses to form an ion microprobe, it is possible to find conditions permitting the total aberration level to be reduced. Numerical optimization of the probe-forming system was performed involving the maximum emittance method developed by the authors in earlier papers. The calculations show that with a 3MeV accelerator, the design proposed would allow generation of a H+ ion beam with a 0.4μm spot size and 3.15μm2mrad2MeV normalized emittance. The total length of the facility is about 4m.