Uni HH, Hamburg
DESY, Hamburg
PSI, Villigen
Uni HH, Hamburg
DESY, Hamburg
BESSY GmbH, Berlin
DESY, Hamburg
Uni HH, Hamburg
* M. Gensch et al., Infrared Phys. Techn.,(2008)
| Paper | Title | Page |
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| TUPPH003 | Tolerance Studies on the High Harmonic Laser Seeding at Flash | 235 |
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| Currently, the Free-electron-LASer at Hamburg (FLASH) operates in the Self-Amplified Spontaneous Emission (SASE) mode, delivering to users photon beams with wavelengths between 6.5 nm and 40 nm. In order to improve the temporal coherence of the generated radiation, it is planned to externally seed FLASH with higher harmonics of an optical laser. The project aims at seeding in the 30-13 nm range with stability suitable for user operation. In this contribution the performance of the seeded FEL is studied in simulations. Emphasis is placed on the tolerances of the most critical parameters such as transverse offset and angle between the electron beam and the external seed, timing jitter, energy of the seed pulse and the influence of the electron optics. | ||
| TUPPH072 | sFLASH: An Experiment for Seeding VUV Radiation at FLASH | 405 |
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| The paper describes an FEL seeding experiment at VUV wavelengths,to be installed at the existing SASE FEL user facility FLASH. Beyond a proof-of-principle demonstration in the VUV, the emphasis will be on high stability in terms of intensity and timing thus providing a future alternative operation mode of FLASH for users. The seed laser generates high harmonics (HHG) by focusing a near-infrared laser into a noble gas jet. The efficient transport of the short wavelength (30nm) radiation and the spatial and temporal overlap with the electron beam are among the challenging tasks. The interaction of the seed laser and the electron beam takes place in a new undulator section to be installed in front of the existing FLASH undulator. Four hybrid variable-gap undulators are foreseen with a total length of 10 meters. In the space between undulator sections there are diagnostics devices for both the electron beam and the seed laser. After the undulators there is a weak magnetic chicane as a separator of the electron beam and the seeded FEL radiation. Finally a VUV beamline transports the radiation to an experimental hutch where the temporal characterization of the amplified pulses takes place. | ||
| THDAU01 | Light Field Driven Streak-camera: Towards a Single Pulse Time Structure Measurement at FLASH | 524 |
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The Free-Electron Laser in Hamburg (FLASH) produces short intense XUV light pulses using Self-Amplified Spontaneous Emission (SASE). Because the lasing in a SASE-FEL starts from shot noise energy, wavelength and time-structure fluctuate from shot to shot. Thus, a single shot measurement of the FLASH temporal profile is of significant interest. For this purpose, the XUV pulses from FLASH are superimposed with far infrared (FIR) light pulses, that are generated by the same electron bunch in a second undulator* and therefore are expected to be intrinsically synchronized to the XUV pulse. In contrast to a conventional streak camera, the solid state photocathode is substituted by free noble gas atoms, which are ionized by the XUV pulses. The created photoelectrons are accelerated by the time-dependent electric field of the infrared light pulse, where the momentum gain depends on the FIR electric field at the ionization time. By measuring the photoelectron momenta we are able to sample the FIR light field. Moreover, single-shot spectra have been obtained that deliver information on the temporal profile of individual XUV pulses.
* M. Gensch et al., Infrared Phys. Techn.,(2008) |
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