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Beam chopping by electrical sweep over an aperture has proved to be a simple and versatile tool for time-of-flight ion surface scattering experiments. Unfortunately the primary energy broadening introduced by the non-static deflection field may seriously affect the resolution of the measurement when dealing with low energy primary ions. The alternative method proposed in this report is to chop the beam with a deflection voltage which has a length-adjustable flat "zero-value" portion. It is shown that the pulse form can be produced in a simpler way. This gives satisfactory results when used with the special plate geometry described. Ions at each end of a bunch do experience a small deflection and energy shift. When short ion bunches are required, a fringe-field shielding configuration reduces this problem.

Additional information

Authors: ARATARI R, Max-Planck-Institut fur Plasmaphysik, Garching bei Munchen (DE)
Bibliographic Reference: Article: Nuclear Instruments and Methods in Physics Research Vol. B34 (1988), pp.493-498
Record Number: 198910188 / Last updated on: 1994-12-01
Original language: en
Available languages: en