seeding
| Paper | Title | Other Keywords | Page |
|---|---|---|---|
| MOPP002 | Prospects of the BESSY High-Energy FEL | radiation, fel, laser, electron | 23 |
| |||
|
Funding: Funded by the Bundesministrium für Bildung, und Forschung, the state Berlin and the Zukunftsfonds Berlin BESSY proposes a linac-based High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) facility with three independent FEL lines. In the BESSY High-Energy-FEL (HE-FEL), a seed laser wavelength of 280nm is downconverted to 1.24nm by a cascade of four HGHG-stages. This procedure requires a high brightness electron beam and a high power seed laser. With the nominal set of beam parameters, radiation power in the range of GWs can be achieved. However, the signal to noise ratio degrades in each HGHG stage. This motivated intensive studies on the possibilities to further optimize the performance of the BESSY HE-FEL. In this paper, we report on three methods aiming to control the signal to noise ratio. They include simulation studies of new seeding schemes with HHG-lasers at shorter wavelengths and seeding with higher seed powers. Also, a concept for the integration of monochromators between two HGHG-stages has been worked out, see also [1]. All methods were studied extensively with regard to their influence on FEL output power, pulse duration and spectral bandwidth. [1] M. Abo-Bakr et al., these Proceedings |
|||
| MOPP005 | Impact of Realistic Bunch Profiles and Timing Jitter on the Output of the BESSY Low Energy FEL Line | fel, bunching, electron, radiation | 35 |
| |||
|
Funding: Bundesministerium für Bildung und Forschung, the state of Berlin and the Zukunftsfonds Berlin In present FEL designs, undulators are usually optimized for an electron bunch with properties constant along the bunch length. The central energy, emittance and other parameters are assumed not to vary from slice to slice. Unavoidable timing jitter of the photo cathode laser, and phase and amplitude errors of the RF fields in the injector and the linac result in variations in emittance, energy spread and beam dimensions along the bunch, causing a jitter in the arrival time of the electron bunch. Due to the passage through bunch compressors, the bunch shows a considerable residual energy chirp. Even assuming a perfect and on-time seed laser pulse, the changing properties along the bunch in combination with the arrival time jitter cause varying conditions for the interaction of the electron bunch with the seed laser radiation. This paper talks about how far the BESSY-FEL radiation is affected by the expected time jitter and the realistic bunch profile, and investigates counter measures. The studies are confined to the low energy FEL line generating output at l = 10nm. |
|||
| MOPP014 | Status of the Seeding Experiment at SPARC | fel, undulator, laser, dipole | 63 |
| |||
|
Funding: Work supported by the EU Commission in the sixth framework programme, contract no. 011935 – EUROFEL. Sources based on high order harmonics generated in gas with high power Ti:Sa lasers pulses represent promising candidates as seed for FEL amplifiers for several reasons, as spatial and temporal coherence, wavelength tunability and spectral range, which extends down to the 10(-9)m wavelength scale. This communication is devoted to the description of a research work plan that will be implemented at the SPARC FEL facility in the framework of the EUROFEL programme. The main goal of the collaboration is to study and test the amplification and the FEL harmonic generation process of an input seed signal obtained as higher order harmonics generated both in crystal (400nm and 266 nm) and in gas (266nm, 160nm, 114nm) from a high intensity Ti:Sa laser pulse. |
|||
| MOOC004 | Seeding the FEL of the SCSS Phase 1 Facility with the 13th Laser Harmonic of a Ti: Sa Laser (61.5 nm) Produced in Xe Gas | laser, sase, undulator, genesis | 224 |
| |||
|
In order to reach very short wavelengths in FEL, and to have a more compact, fully coherent and tunable source, a particular seeding configuration is foreseen to be tested as a demonstration experiment in 2006 into the SCSS phase 1 facility (Spring-8 Compact Sase Source, Japan). The external source is the 13th harmonic (61.5 nm) of a Ti: Sa laser (25 mJ, 10 Hz, 100 fs) generated in 10 Hz pulsed Xe gas cell. The harmonic generation process provides us with a intense (1 μJ) and ultra-short (50 fs) VUV beam. The design of the experiment implantation is discussed, taken into account the performances of the generation process, the focusing of the selected harmonic into the modulator, and the resistance of the optical components. Besides one should consider the vacuum needs, the geometrical problems and the mechanics for the under UHV mirrors translation. One first chamber is dedicated to the harmonic generation. A second one is used for spectral selection and adaptation of the harmonic in the modulator. Finally theoretical estimates of the performances relying on 1D simulations using PERSEO code and 3D simulations using GENESIS code are also given. |
|||
| THPP018 | Integrated Design of Laser Systems for a FEL User Facility | laser, cavity, fel, oscillator | 487 |
| |||
|
Laser systems will undoubtedly be one of the key factors determining the performance of VUV and X-ray FELs. In particular, harmonic generation scheme based FELs require at least three mutually synchronized solid-state laser systems: photoinjector laser, seeding laser, end station lasers. In addition, a laser heater is also included in recent FEL designs. It is therefore very important to consider the possibility of integrating these systems to a maximum possible degree. In this paper we consider a promising approach to the integration of the above specified laser systems for the FERMI@ Elettra FEL, based on the distribution of a fiber laser generated seed signal at 1550 nm. This signal, after further amplification and frequency doubling, is used as a seed for Ti:Sapphire amplifiers at the different locations. The paper presents a general layout of the system, the main pulse parameters (i.e. pulse energy and duration) needed in different parts of the system and discusses possible technical solutions |
|||