SYSTEMATIC-ERROR OF THE MEASUREMENT OF ELECTRON-BEAM EMITTANCE

Determination of the structure of electron beam charge flow is one of the most important problems in designing and in investigations of the electron beam. The parameter that enables the quantitative estimation of non-laminar behaviour of electron beams is the emittance. This para meter can be measured using hole-slit analyzer. However, this type of equipment belongs to the group of measuring devices for which the resu lts of measurements are loaded with systematical errors Delta E. For a hole-slit analyzer errors arise from finite dimensions of holes and a nalyzing slits. Here the original method of evaluating the systematica l errors of emittance measurements is presented, allowing estimation o f real emittance values E-r, by the determination of correlation coeff icient kappa(E), Which is characteristic of the measuring device and f rom the emittance E-m range, using the relation E-r = kappa(E)E(m). Th e ability to allow for the error in emittance measurement permits esti mation of various properties of different types of electron beams and to compare their charge flow laminarity. Information is given on the p rinciple and design of an analyser with movable apertures for beam exp loration with the results derived. (C) 1998 Elsevier Science Ltd. All rights reserved.