N. Bliss

European project to develop a UV/VUV free-electron laser facility on the ELETTRA storage ring☆

Abstract The main features and novel technical aspects of a new European project to integrate a free-electron laser on an existing “third generation” synchrotron radiation user facility are described, including the design of the optical cavity and undulator, the electron beam characteristics and a first assessment of the predicted laser performance.

The status of the Daresbury Energy Recovery Linac Prototype

As part of the UKs R&D programme to develop an advanced energy recovery linac-based light source (4GLS) a 35 MeV technology demonstrator called the energy recovery linac prototype (ERLP) has been constructed. It is based on a combination of a DC photocathode electron gun, a superconducting injector linac and main linac operating in energy recovery mode, driving an IR-FEL. The priorities for this machine are to gain experience of operating a photoinjector gun and superconducting linacs; to produce and maintain high- brightness electron beams; to achieve energy recovery from an FEL-disrupted beam and to study challenging synchronisation issues. The current status of this project is presented, including construction and commissioning progress and plans for the future exploitation of this scientific and technical R&D facility.

The Advantages and Challenges of Helical Coils for Small Accelerators—A Case Study

Most of todays particle accelerators are used in industry or for medical applications, for example, in radioisotope production and cancer therapy. One important factor for these applications is the size of the accelerator, which ideally should be as small as possible. In this respect, fixed-field alternating-gradient accelerators (FFAGs) can be an attractive alternative, which combine the best features of conventional synchrotrons and cyclotrons: FFAGs deliver better performance than synchrotrons while retaining flexibility. Of particular interest are accelerators for protons of moderate energy (0.25-1 GeV) and light ions such as carbon (up to 400 MeV per nucleon), for example, for proton/carbon-ion charged particle therapy or potential future applications such as accelerator-driven subcritical reactors. Due to high magnetic rigidity, a compact machine can be only achieved by using high field superconducting magnets. A disadvantage of FFAGs is that the magnetic elements can be very challenging. Quite often, complicated multipole fields are required, in combination with stringent geometric constraints. In this paper, we demonstrate the advantages of helical coil technology by means of an accelerator for proton therapy.

4GLS: a new type of fourth generation light source facility

Consideration is now being given in the UK to the provision of an advanced facility at lower energy to complement the DIAMOND x-ray light source. The proposed solution, 4GLS, is a superconducting energy recovery linac (ERL) with an output energy around 600 MeV, delivering both CW beam currents up to 100 mA and alternatively high charge bunches for FEL applications. Production and manipulation of short electron bunches (fs) is a vital part of the source specification. In addition to beam lines from undulator sources in the ERL recovery path there will be three FELs: two will be oscillator types in the infrared and VUV respectively, and the third will be a high gain system for XUV output. The project is outlined, together with its status and the R&D challenges posed. A funded prototype based on a 50 MeV ERL is also described.

A wide-aperture dynamically focusing sagittal monochromator for X-ray spectroscopy and diffraction.

A scanning dynamically focusing sagittal X-ray monochromator accepting 7 mrad of the fan from a 6 T wiggler is in routine use on beamline 16.5 (ultra-dilute spectroscopy) of the SRS at CCLRC Daresbury Laboratory, UK. The energy range covered is 7-27 keV, with a horizontal spot size of <1.1 mm FWHM. Measured monochromatic flux from a Si 220 crystal pair is 1 x 10(11) photons s(-1) (100 mA)(-1) at 9 keV. This level of flux, usually associated with an insertion device on a third-generation source, permits collection of EXAFS data on concentrations at or below 10 ppm.

Final measurements of the SRS multipole wigglers

Two new high field 2 T multipole wigglers have been built for the SRS. Detailed mechanical and magnetic tests have been made and these are compared with the expected theoretical performance. These insertion devices have now been installed into the SRS and are operating successfully.

Design of a 2 T multipole wiggler insertion device for the SRS

Two new identical insertion devices have been designed for the Daresbury SRS. They are 2 T permanent-magnet multipole wigglers that will provide high flux in the X-ray region. This paper describes the magnetic and mechanical design of the arrays of steel pole pieces and permanent-magnet blocks. Also given is the engineering design of the support structure that will cope with the very large forces present while maintaining high levels of precision in gap setting and parallelism. The engineering design has been fully assessed using finite-element techniques to predict the deflections of critical parts of the structure. These two devices are due to be installed into the SRS by the end of 1998.

Recent developments on the muon Non-Scaling FFAG for the Neutrino Factory and its subsystems

The current status and recent developments on the muon non-scaling FFAG for the Neutrino Factory studied in the framework of the EUROnu/IDS-NF projects are presented. Beam dynamics studies, including the process of acceleration, are discussed. A first pass at engineering for the layout of the ring cell is described. Progress of studies on the main machine subsystems is discussed. The future plans for the study are described.