23-24 September 2020
Virtual Meeting via Zoom
Europe/Berlin timezone

Emittance Reduction of RF Photoinjector Generated Electron Beams by Transverse Laser Beam Shaping

24 Sep 2020, 10:20
Virtual Meeting via Zoom

Virtual Meeting via Zoom

Speed talk Beam Dynamics


Dr Matthias Gross (DESY)


Linac based X-ray free electron laser demand a high beam quality from the electron source, therefore RF photoinjectors are used to generate the electron bunches for state of the art beam brightness. One important figure of merit for these injectors is the transverse emittance of the generated electron beam, which can be minimized by shaping the photocathode laser pulses. Best performance can be achieved with ellipsoidal laser pulses, but 3D shaping is technically challenging. Typically, a quasi-uniform transverse laser profile is truncated from the Gaussian profile generated by the laser with an aperture to reduce the transverse nonlinear space charge forces. This is investigated in detail by optimizing the laser transverse profile at the Photoinjector Test facility at DESY in Zeuthen (PITZ), where photoinjector R&D is conducted for the E-XFEL and FLASH free electron lasers at DESY in Hamburg. In this contribution we present experimental results at high acceleration gradients (up to 60 MV/m) for both 250 pC and 500 pC. For a bunch charge of 500 pC an emittance reduction of about 30% compared to the commonly used transverse flat-top laser distribution was achieved.

Primary authors


Anne Oppelt (DESY) Mr Christian Koschitzki (DESY Zeuthen) David Melkumyan (DV) Frank Stephan (DESY) Mr Georgi Georgiev (DESY Zeuthen) Gregor Loisch (DESY Zeuthen) Mr Grygorii Vashchenko (DESY) Dr Guan Shu (DESY) Dr James Good (DESY) Mikhail Krasilnikov (DESY Zeuthen) Namra Aftab (DESY) Mr Osip Lishilin (DESY) Mr Prach Boonpornprasert (DESY, Zeuthen) Mr Raffael Niemczyk (PhD Student) Mr Sandeep Mohanty (DESY) Dr Xiangkun LI (DESY Zeuthen) Ye Chen (DESY)

Presentation Materials