BEAM DIAGNOSTICS USING AN EMITTANCE MEASUREMENT DEVICE

For beam diagnostics aside from Faraday cups for current measurements and analysing magnets for the determination of beam composition and en ergy the most important tool is an emittance measurement device. With such a system the distribution of the beam particles in phase-space ca n be determined. This yields information not only on the position of t he particles but also on their angle with respect to the beam axis. Th ere are different kinds of emittance measurement devices using either circular holes or slits for separation of part of the beam. The second method (slit-slit measurement), though important for the determinatio n of the rms-emittance, has the disadvantage of integrating over the g amma- and gamma'-coordinate (measurement in xx'-plane assumed). This l eads to different emittance diagrams than point-point measurements, si nce in xx'-plane for each two corresponding points of rr'-plane there exists a connecting line. With regard to beam aberrations this makes x x'-emittances harder to interpret. In this paper the two kinds of emit tance diagrams are discussed. Additionally the influence of the slit h eight on the xx'-emittance is considered. The analytical results are c ompared to experimental measurements in rr'-, rx'- and xx'-phase-space .