The ThomX project status

Work supported by the French Agence Nationale de la recherche as part of the program EQUIPEX under reference ANR-10-EQPX-51, the Ile de France region, CNRS-IN2P3 and Université Paris Sud XI - http://accelconf.web.cern.ch/AccelConf/IPAC2014/papers/wepro052.pdfA collaboration of seven research institutes and an industry has been set up for the ThomX project, a compact Compton Backscattering Source (CBS) based in Orsay - France. After a period of study and definition of the machine performance, a full description of all the systems has been provided. The infrastructure work has been started and the main systems are in the call for tender phase. In this paper we will illustrate the definitive machine parameters and components characteristics. We will also update the results of the different technical and experimental activities on optical resonators, RF power supplies and on the electron gun

SIMULATIONS AND RF MEASUREMENTS OF THE FUNDAMENTAL AND HIGHER ORDER MODES OF THE THOMX 500 MHz CAVITY*

The RF system of the ThomX storage ring consists in a 500 MHz single cell copper cavity of the ELETTRA type, powered with a 50 kW CW solid state amplifier, and the associated Low Level RF feedback and control loops. The low operating energy of 50–70 MeV makes the impedances of the cavity higher order modes (HOMs) particularly critical for the beam stability. Their parasitic effects on the beam can be cured by HOM frequency shifting techniques, based on a fine temperature tuning and a dedicated plunger. A typical cavity temperature stability of ± 0.05°C within a range from 35 up to 80 °C can be achieved by a precise control of its water cooling temperature. On the other hand, the tuning of the cavity fundamental mode is achieved by changing its axial length by means of a mechanical tuner. In order to insure a fine control of the HOM frequencies, a good knowledge of their characteristics is mandatory. The main parameters of the fundamental and of the HOMs up to 4 GHz have been calculated using the HFSS and CST MWS codes. Preliminary measurements results have been obtained and show a good agreement with the simulations

Publisher Correction: Control of laser plasma accelerated electrons for light sources

The original version of this Article contained an error in the last sentence of the first paragraph of the Introduction and incorrectly read ‘A proper electron beam control is one of the main challenges towards the Graal of developing a compact alternative of X-ray free-electron lasers by coupling LWFA gigaelectron-volts per centimetre acceleration gradient with undulators in the amplification regime in equation 11, nx(n-β) x β: n the two times and beta the two times should be bold since they are vectorsin Eq. 12, β should be bold as well.’ The correct version is ‘A proper electron beam control is one of the main challenges towards the Graal of developing a compact alternative of X-ray free-electron lasers by coupling LWFA gigaelectron-volts per centimetre acceleration gradient with undulators in the amplification regime.’This has been corrected in both the PDF and HTML versions of the Article

Publisher Correction: Control of laser plasma accelerated electrons for light sources

The original version of this Article contained an error in the last sentence of the first paragraph of the Introduction and incorrectly read ‘A proper electron beam control is one of the main challenges towards the Graal of developing a compact alternative of X-ray free-electron lasers by coupling LWFA gigaelectron-volts per centimetre acceleration gradient with undulators in the amplification regime in equation 11, nx(n-β) x β: n the two times and beta the two times should be bold since they are vectorsin Eq. 12, β should be bold as well.’ The correct version is ‘A proper electron beam control is one of the main challenges towards the Graal of developing a compact alternative of X-ray free-electron lasers by coupling LWFA gigaelectron-volts per centimetre acceleration gradient with undulators in the amplification regime.’This has been corrected in both the PDF and HTML versions of the Article

Production of high energy photons with in vacuum wigglers : From SOLEIL wiggler to MAXIV wiggler

Small gap wigglers become more and more attractive to produce high photon fluxes in the hard X-ray photon range. They use magnet blocks of high magnetization which resists much better to heating (baking, synchrotron radiation) than in the past, produce high magnetic field with numerous periods and are very compact. They also are a very good alternative to superconducting technology which requires special infrastructure, heavy maintenance and is not running cost free. SOLEIL, operating presently at 2.75 GeV has designed and built an in-vacuum wiggler of 38 periods of 50 mm producing 2.1 T at a minimum gap of 5.5 mm to delivered photon beam between 20 keV and 50 keV. Already in operation, further improvements are presently in progress to push photons towards higher energy, in particular thanks to the operation at lower gap (4.5 mm). MAX IV and SOLEIL, in the frame of collaboration, ave built an upgraded version of the existing SOLEIL wiggler with the target to extend the spectral range at high energy (above 50 keV) but also at low energy (4 keV) with the same insertion device. The design of the existing magnetic system has been modified to reach 2.4 T at a minimum gap of 4.2 mm and includes taper operation to avoid undulator structure in the radiated spectrum at low energy

Control of laser plasma accelerated electrons for light sources

Electron beam quality in accelerators is crucial for light source application. Here the authors demonstrate beam conditioning of laser plasma electrons thanks to a specific transport line enabling the control of divergence, energy, steering and dispersion and the application to observe undulator radiation

An application of laser–plasma acceleration: towards a free-electron laser amplification

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