Wuppertal 2015 – wissenschaftliches Programm

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 9: Beam Dynamics / Simulation I

AKBP 9.8: Vortrag

Dienstag, 10. März 2015, 18:30–18:45, BZ.08.04 (HS 2)

Beam Extraction Dynamics at the Space-Charge-Limit of the High Brightness E-XFEL Electron Source at DESY-PITZ — •Ye Chen, Erion Gjonaj, and Thomas Weiland — TEMF, Technische Universitaet Darmstadt, Schlossgartenstrasse 8, 64289 Darmstadt, Germany

The physics of the photoemission, as one of the key issues for successful operation of linac based free-electron lasers like the European X-ray Free Electron Laser (E-XFEL) and the Free-electron Laser in Hamburg (FLASH), is playing an increasingly important role in the high brightness DESY-PITZ electron source.

We study photoemission physics and discuss full three-dimensional numerical modeling of the electron bunch emission. The beam extraction dynamics at the photocathode has been investigated through the 3D fully electromagnetic (EM) Particle-in-Cell (PIC) solver of CST Particle Studio under the assumption of the photoemission source operating at or close to its space charge limit. PIC simulation results have shown good agreements with measurements on total emitted bunch charge for distinct experimental parameters.

Further comparisons showed a general failure for the conventional Poisson solver based tracking algorithm to correctly predict the beam dynamics at the space charge limit. It is furthermore found, that fully EM PIC simulations are also consistent with a simple emission model based on the multidimensional Child-Langmuir law.