The Lund Nuclear Microprobe sub-micron set-up. Part I: Ion optics calculation

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Vol. 231; no. 1-4; pp. 1 - 6
• Main Authors: Shariff, Asad, Auzelyte, Vaida, Elfman, Mikael, Kristiansson, Per, Malmqvist, Klas, Nilsson, Christer, Pallon, Jan, Wegdén, Marie
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2005
• Subjects: Fysik; Ion optics; Natural Sciences; Naturvetenskap; Nuclear microprobe; OXTRACE; Physical Sciences; PRAM; Sub-micron beam; Subatomic Physics; Subatomär fysik; OXTRACE; Sub-micron beam; Nuclear microprobe; 07.10.Cm; PRAM; 89.20.−a; Ion optics; 87.64.−t; 07.09.−v; 07.30.Kf; 07.79.−v; 07.05.−Bx; 68.37.yz
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/j.nimb.2005.01.026

A new beam line for generating a sub-micron beam spot for high-resolution nuclear microprobe applications has been constructed at the Lund nuclear microprobe facility. In this paper, the first in a series of three, a detailed theoretical investigation of different focusing systems is presented based on calculations performed with the computer programs PRAM and OXTRACE. Comparison is made between a doublet, a triplet, a quadruplet and a split quadruplet (two-stage focusing). For the split quadruplet all four quadrupole magnets were uncoupled. The conclusion from the calculations was that to obtain the smallest possible beam, the two-stage focusing system should be used. Such a focusing system (a doublet at each stage) has been chosen for the new sub-micron set-up at the Lund NMP laboratory. The first stage focuses the beam in an intermediate chamber, which has a high-resolution optical viewing system facilitating more control over the beam spot. This real image of the first stage is then used as a virtual object for the second stage.