| Paper | Title | Page |
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| TUPE011 | Generating Low Transverse Emittance Beams for Linac Based Light Sources at PITZ | 2167 |
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At the Photo Injector Test facility at DESY, Zeuthen site (PITZ), high brightness electron sources for linac based Free Electron Lasers (FELs), like FLASH and the European XFEL are developed and characterized. The electrons are generated via the photoeffect at a cesium telluride (Cs2Te) cathode and are accelerated by a 1.6-cell L-band RF-gun cavity with an accelerating gradient at the cathode of about 60 MV/m. The profile of the cathode laser pulse has been optimized yielding small emittances using laser pulse shaping methods. The transverse projected emittance is measured by a single slit scan technique. The measurement program in the last run period at PITZ concentrated on emittance measurements for the nominal 1 nC beam and emittance optimization for lower bunch charges. The recent results show that normalized projected emittances of about 1 mm-mrad for 1 nC charge and below 0.5 mm-mrad for 250 pC bunch charges can be realized at PITZ. The facility setup and measurement results including the uncertainty of the measured values will be reported and discussed in this contribution. |
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| MOPD091 | Femtosecond Temporal Overlap of Injected Electron Beam and EUV Pulse at sFLASH | 915 |
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sFLASH is a seeded FEL experiment at DESY, which uses a 38nm high harmonic gain (HHG)-based XUV-beam laser in tandem with FLASH electron bunches at the entrance of a 10m variable-gap undulator. The temporal overlap between the electron and HHG beams is critical to the seeding process. Use of a 3rd harmonic accelerating module provides a high current electron beam (at the kA level) with ~ 600fs FWHM bunch duration. The length of the HHG laser pulse will be ~30fs FWHM. The desired overlap is achieved in steps. First is the synchronization of the HHG drive laser (Ti: Sapphire, 800nm) and the incoherent spontaneous radiation from an upstream undulator. Next, the IFEL-modulated electron bunch will pass through a dispersive section, producing a density modulation in the beam. This in turn yields emission of coherent radiation from a downstream undulator or transition radiation screen when the longitudinal overlap of the two beams is achieved. The coherently enhanced light emitted will be then spectrally analyzed. The experimental layout, simulation results of generation and transport of both light pulses, and preliminary measurements are presented. |
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| TUPE009 | Status of sFLASH, the Seeding Experiment at FLASH | 2161 |
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Recently, the free-electron laser in Hamburg (FLASH) at DESY has been upgraded considerably. Besides increasing the maximum energy to about 1.2 GeV and installation of a third harmonic rf cavity linearizing the longitudinal phase space distribution of the electron bunch, an FEL seeding experiment at wavelengths of about 35 nm has been installed. The goal is to establish direct FEL seeding employing coherent VUV pulses produced from a powerful drive laser by high-harmonic generation (HHG) in a gas cell. The project, called sFLASH, includes generation of the required HHG pulses, transporting it to the undulator entrance of a newly installed FEL-amplifier, controlling spatial, temporal and energy overlap with the electron bunches and setting up a pump-probe pilot experiment. Sophisticated diagnostics is installed to characterize both HHG and seeded FEL pulses, both in time and frequency domain. Compared to SASE-FEL pulses, almost perfect longitudinal coherence and improved synchronization possibilities for the user experiments are expected. In this paper the status of the experiment is presented. |
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| TUPE010 | Status of the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ) | 2164 |
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The PITZ facility is established for the development and testing of electron sources for FELs like FLASH and the European XFEL. The facility has been upgraded during the shutdown starting in summer 2007 to extend the capability of the facility to produce and characterize low emittance electron beams. The upgraded setup mainly includes a photo cathode L-band RF gun with solenoid magnets for space charge compensation, a post acceleration booster cavity and several diagnostic systems. The diagnostic systems consist of charge and beam profile monitors, emittance measurement systems and spectrometers with related diagnostics in dispersive arms after the gun and the booster cavities. RF gun operation with an accelerating gradient of 60 MV/m at the cathode is realized with this setup. A new photo cathode laser system with broader spectral bandwidth was installed for optimizing the temporal distribution of the laser pulses regarding to electron beam properties. Experimental results with this setup demonstrated very high electron beam quality as required for the photoinjector source of the European XFEL. In this contribution, the PITZ facility setup in year 2008-2009 will be presented. *for the PITZ Collaboration |