Kaertner, F.X.
| Paper | Title | Page |
|---|---|---|
| MOPP036 | Next Generation Synchronization System for the VUV-FEL at DESY | 118 |
|
||
|
The control and stabilization of the longitudinal beam profile and the bunch arrival time in linac driven VUV or X-ray Free-Electron Lasers require special effort and new developments in the fields of low level RF controls, global synchronization systems and longitudinal beam feedbacks. In this paper we describe the required upgrades for the VUV-FEL at DESY to synchronize the FEL pulse and optical lasers to the level of hundred femtoseconds (FWHM). |
||
| MOPP037 | Femtosecond Timing Distribution Using Optical Pulses | |
|
||
|
Fourth-generation light sources, such as the European X-ray Free Electron Laser (XFEL) require timing signals distributed over distances of several kilometers with a stability in the order of femtoseconds. A promising approach is the use of a mode-locked laser that generates sub-picosecond pulses which are distributed in timing stabilized optical fiber links. A good candidate for a laser master oscillator (LMO) is a mode-locked Erbium-doped fiber laser, featuring extremely low phase noise far from the carrier. Results on the development of the LMO locked to an external reference microwave oscillator to suppress low frequency jitter, the distribution via timing stabilized optical fiber links and the reconversion of the optical pulses to a low phase noise microwave RF signals with overall femtosecond stability are presented. |
||
| MOPP041 | Generation and Distribution of Stable Timing Signals to Synchronize RF and Lasers at the FERMI FEL Facility | 134 |
|
||
|
Fermi is the fourth generation light source that is currently being designed at ELETTRA, in the frame of a collaboration that includes LBNL and MIT. The timing system will play a crucial role in achieving the expected performance of this and other Linac based FELs due to the sub-ps electron bunch length and the expanded use of fs-lasers as key components in future light sources. Furthermore, the requirements of the timing system are also tightly linked to the applications of the generated ultrafast x-ray pulses. In this paper we present the requirements for the FERMI timing system, which will be based on optical timing distribution concepts, currently seen to be the only technique to enable an RMS jitter at the 10fs level. The timing system, intended for a user facility that is operated on a 24-h, 7-d basis, must operate stable and reliable. The fundamental components of the system are analyzed, such as the optical reference oscillator, the fiber optic stabilized links and the local optical to electrical (O/E) converters, needed for the RF plant synchronization. Furthermore, solutions for the synchronization of the diagnostic tools for the Linac as well as user related synchronization issues are presented and discussed. |
||
| THPP018 | Integrated Design of Laser Systems for a FEL User Facility | 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 |
||
| THPP068 | Electron Beam Diagnostic Based on a Short Seeded FEL | |
|
||
|
The optical properties of an FEL amplifier are sensitively dependent on the electron beam current profile, energy spread, and transverse emittance. In this paper we consider using a short FEL amplifier operating on a low harmonic of a visible-IR input seed as a mildly destructive electron beam diagnostic able to measure these properties for sub-ps time slices. The optical methods are described as well as a planned implementation of the device for the FERMI@Elettra XUV FEL under construction at Sincrotrone Trieste, including its fiber-based seed laser closely coupled with the facility timing system, undulator parameters, and requirements on the electron and FEL pulses. This diagnostic is conveniently integrated with a "laser heater" designed to increase the very low electron beam energy spread produced by a photoinjector in order to avoid space charge and coherent synchrotron radiation instabilities. |
||
| FROA002 | Synchronization of Femtosecond Pulses | 676 |
|
||
|
X-ray pulses with a pulse duration of down to 30 fs FWHM or even sub-fs are desired for various experiments planned at next generation free electron lasers, such as the European XFEL. A synchronization of the probe system in the experimental area to the x-ray pulses with stability on the order of the pulse width is highly desirable for these experiments. This requirement translates to distributing an ultra-stable timing signal to various subsystems of the machine and the experimental area to provide synchronization at the fs level over distances of up to several kilometers. A few years ago, a timing and synchronization system providing stability to the fs level was unthinkable. Recent advances in the field of ultra-short pulse lasers have made optical synchronization systems with such a precision feasible. This talk will focus on an optical approach using a train of ultra-short pulses distributed through optical fiber links. The timing information is contained in the precise repetition rate. First results of such a system operating in an accelerator environment will be reported. |
||
| FROA003 | FERMI @ Elettra: A Seeded Harmonic Cascade FEL for EUV and Soft X-Rays | 682 |
|
||
|
We describe the machine layout and major performance parameters for the FERMI FEL project funded for construction at Sincrotrone Trieste, Italy. The project will be the first user facility based on seeded harmonic cascade FELs, providing controlled, high peak-power pulses. With a high-brightness rf photocathode gun, and using the existing 1.2 GeV S-band linac, the facility will provide tunable output over a range from ~100 nm to ~10 nm, with pulse duration from 40 fs to ~ 1ps, and with fully variable output polarization. Initially, two FEL cascades are planned; a single-stage harmonic generation to operate > 40 nm, and a two-stage cascade operating from ~40 nm to ~10 nm or shorter wavelength. The output is spatially and temporally coherent, with peak power in the GW range. Lasers provide modulation to the electron beam, as well as driving the photocathode and other systems, and the facility will integrate laser systems with the accelerator infrastructure, including a state-of-the-art optical timing system providing synchronization of rf signals, lasers, and x-ray pulses. Major systems and overall facility layout are described, and key performance parameters summarized. |
||