Darmstadt 2016 – scientific programme
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AKBP: Arbeitskreis Beschleunigerphysik
AKBP 3: Injectors, Laser II
AKBP 3.5: Talk
Monday, March 14, 2016, 17:30–17:45, S1/05 23
Evaluation of the Photocathode Laser Transverse Distribution — Chaipattana Saisa-ard1,2, Mikhail Krasilnikov1, and •Grygorii Vashchenko1 — 1DESY, Zeuthen, Germany — 2Chiang Mai University, Chiang Mai, Thailand
Many years experience of electron source developments at the photo injector test facility at DESY in Zeuthen (PITZ) show that the photocathode laser is the one of major tools to produce high brightness electron beams. The transverse distribution of the laser on the photocathode plays a significant role in the high brightness photo injector optimization. However, the imperfections in the laser beam profile according to the deviation from a radially homogeneous profile directly result in transversely distorted charged particle distributions. This includes inhomogeneous core as well as transverse halo which is due to not sharp edges around the core. The laser transverse distribution is measured at PITZ using a virtual cathode :this is a CCD camera located at the position which is optically equivalent to the photocathode position (so called virtual cathode). An algorithm is developed for the evaluation of the experimentally obtained transverse profiles. It fits a flat-top or an inhomogeneous rotational symmetric core with exponentially decaying tails to an experimental distribution. The MATLAB script with implemented algorithm is applied to a set of measured transverse laser distributions. Results of the analysis will be presented.