Correction of charged particle beam optics by a programmed electrostatic wire array

• Published in: Journal of applied physics 1988-07, Vol.64 (2), p.471-478
• Main Authors: HUMPHRIES, S. JR, TERRY, R. L
• Format: Article
• Language: English
• Subjects: Charged-particle beams; Electromagnetism; electron and ion optics; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Physics
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.341984

Theoretical and experimental results are reported on a method for the correction of aberrations in optical elements for high-power ion beams. The approach involves the use of arrays of wires immersed in large diameter beams. Individually controlled voltages are applied to the wires, resulting in local transverse deflections of beam particles. With regard to wire survivability and voltage requirements, the method appears feasible for application to high-intensity negative ion beams. A formalism is described for the calculation of optimum wire voltages to achieve a specified beam angular correction in a Cartesian geometry. The results of the calculations were tested in modeling experiments using an 8-keV electron beam. The experimental array consisted of 46 wires and boundary plates with independent applied voltages up to 3 kV. Voltage profiles for one-dimensional focusing, two-dimensional focusing, and beam steering were studied. The observed particle deflections and beam emittance growth due to the facet lens effect are in agreement with predictions.