Observation of self-amplified spontaneous emission in the mid-infrared in a free-electron laser

We have produced and analyzed self-amplified spontaneous emission emitted by a relativistic electron beam passing through an undulator for the first time in the mid-infrared. The spectral behavior of the line exhibits an unexpected growth at the start-up of the process

Horizontal Emittance Reduction on a Synchrotron Radiation Light Source with a Robinson Wiggler

The performance of synchrotron light facilities are strongly influenced by the photon beam bright- ness, that can be further increased by reducing the beam emittance. A Robinson Wiggler can be installed in a non-zero dispersion straight section to reduce the horizontal beam emittance. It is composed of an array of magnets of alternated polarities, whose both magnetic field and gradient are of opposite signs. It provides a compact solution to reduce by 50% the horizontal emittance. How- ever, it increases the energy spread by 40%. The concept of the Robinson Wiggler (RW) is described here, the first experimental observation of the Robinson effect in a synchrotron light source on the transverse and longitudinal beam properties by the means of four existing undulators is presented and the impact on the photon flux density is studied

Multipass Lock-In Thermography for optical coating absorption measurements

International audienc

Application of an emittance adapter to increase photon flux density on a synchrotron radiation beam line

The application of the Chao-Raimondi emittance adapter to the SOLEIL storage ring is studied theoretically in terms of linear and nonlinear beam dynamics. This unique scheme recently proposed elsewhere using a pair of emittance adapters and a solenoid in between them allows a local conversion of an electron beam in a third generation light source to an ultralow emittance beam of the fourth generation. The study of potential benefits of the resultant synchrotron radiation is of crucial importance. Electron beam properties and magnetic fields inside the undulator solenoid are treated as inputs of the investigations. Characteristics of photon beams emitted by a round and small electron beam in an undulator are studied in detail on the basis of the near-field wave propagation method. The photon flux density gain, which is a figure of merit along with transverse coherence, is evaluated at the sample of two hard and soft x-ray beam lines existing at SOLEIL

Angular and spectral distribution of infrared synchrotron radiation emitted by an undulator and its edges

Both the angular and the spectral distribution of the Infrared Synchrotron Radiation emitted by an undulator of Super-ACO have been measured. Structures due to undulator edges, as well as contributions from the edge emission of a bending magnet placed behind the undulator, have been observed. Detailed calculations including all these sources are in excellent agreement with the measurements, provided that both velocity and acceleration terms are considered

Spectral distribution of infrared synchrotron radiation by an insertion device and its edges: A comparison between experimental and simulated spectra

The first measurements of the spectral distribution of infrared radiation emitted by an undulator are reported. They are compared with calculations including both velocity and acceleration terms. Measurements have been performed at the beam line SIRLOIN (Spectroscopie en InfraRouge Lointain). The agreement between the observations and this first exact numerical solution shows that the inclusion of the velocity term in the submillimeter frequency range is necessary. Moreover, structures due to undulator edges are observed in the far infrared and mid-infrared range, while the interference pattern due to redshifted harmonics of the undulator is dominating in the mid-infrared to near infrared

Step-tapered operation of the FEL: Efficiency enhancement and two-colour operation

We present measurements of the temporal and spectral properties of radiation produced from the step-tapered undulator infrared free-electron lasers (FELs), CLIO in France and FELIX in the Netherlands. Using a two section undulator with independently adjustable deflection parameters, K, the FEL will operate either with an enhanced efficiency and improved spectral properties (with a small positive Delta K step) or simultaneously at two frequencies (for large Delta K). Using a dispersion-free hole output coupler the maximum wavelength difference delta lambda/lambda, has now been extended to more than delta lambda/lambda approximate to 0.6. We also present measurements that show that the FEL FELIX will produce significant power simultaneously at two wavelengths by coherent spontaneous emission when the wavelength is long and the electron bunch is short. The efficiency, spectral and temporal properties have been measured. We show that at the maximum efficiency, Delta K approximate to 0.02, the optical pulses generated are smooth and close to Fourier transform limited. By adjusting Delta K the optical pulse duration can be varied by a factor of 2 or more and sidebands due to synchrotron oscillations can be suppressed

Infrared synchrotron radiation: from the production to the spectroscopic and microscopic applications

This study reviews the various mechanisms exploited to produce infrared synchrotron radiation (IRSR). It shows that at long wavelengths (long when compared to the critical wavelength of the bending magnet in an electron storage ring), the radiation emitted from a bending magnet edge can be brighter than standard synchrotron radiation. For this purpose, we will discuss the various IRSR sources, namely the bending magnets, the wigglers, the undulator and the bending magnet edges. We will then briefly review a high-resolution study of isolated molecules in the far infrared, the detection of a very narrow Drude term in a high-T-c superconductor, a description of ultra-high pressure experiments, an investigation of water encapsulated in non-ionic reverse micelles, and finally, a brief review of spatially resolved studies. (C) 2001 Elsevier Science B.V. All rights reserved