Influence of longitudinally tapered collimators on a high brightness electron beam

• Main Authors: S. Di Mitri, L. Froehlich, E. Karantzoulis
• Format: Article
• Language: English
• Published: American Physical Society 2012-06-01
• Series: Physical Review Special Topics. Accelerators and Beams
• Online Access: http://doi.org/10.1103/PhysRevSTAB.15.061001

This article presents the design and operation of a longitudinally tapered collimator in a single-pass S-band linac driving a high brightness electron beam. Measurements were done for the transverse emittance growth induced by the collimator wakefield as a function of the lateral displacement of the beam inside the collimator and the energy acceptance provided by an identical collimator installed in a dispersive region. The measurements demonstrate that: (i) the proposed design allows very precise and reproducible motion down to the micron level of the compact, four-hole collimator; (ii) the collimator does not degrade the beam emittance in the presence of standard trajectory control; (iii) the measured kick factor and energy acceptance are in agreement with the theoretical expectations. These measurements were made using 500 pC, 2.4 ps long bunches at the FERMI@Elettra free electron laser facility.