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| MOPCH018 | Macro-Pulse Generation in a Storage-Ring Free-Electron Laser: A Single-Particle Plus FEL Numerical Approach | FEL, electron, simulation, storage-ring | 89 | ||
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In a storage-ring free-electron laser (FEL), the onset and growth of intra-cavity power at the fundamental resonant wavelength is naturally accompanied by coherent emission at higher harmonics. Contrary to what happens in single-pass linac-based devices, the electron beam is re-circulated in the storage ring and the microbunching becomes thermalized. As a consequence, a correct theoretical understanding of the process requires a proper modelling of the turn-by-turn evolution of the electron-beam phase space, both inside the undulators (where the FEL interaction takes place) and along the ring. To simulate this process we have coupled an ad hoc modified version of the 3D numerical code Ginger (which models the FEL interaction) together with a linear one-turn map (which propagates the electron beam along the ring). We present our results and draw a comparison with previous simplified approaches. We also present the first benchmarking of experiments carried out with the ELETTRA storage-ring FEL.
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| MOPCH019 | Baseline Design of the Linac Upgrade for Fermi | linac, FEL, controls, laser | 92 | ||
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The FERMI FEL requires a major upgrade of the existing linac, which needs to be transformed from being the injector for the ELETTRA light source, to becoming the source for the FERMI FEL. In this work, we present the baseline design, including the integration of the 7 additional systems from the LIL linac, and one X-band station as linearizers. We will present the new layout with the required modifications and additions to the existing infrastructure to meet the more demanding needs of the system. Such modifications include a new RF controller, improvements in the modulator stability and an upgrade to the average power capabilities of the system to operate at 50 Hz. Test results from the characterization of the existing systems will be included, as well as plans for future development.
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| WEPCH020 | Extending the Linear Least Squares Problem for Orbit Correction in Circular Accelerators | controls, feedback, simulation, insertion | 1963 | ||
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A method for extending the linear least squares problem applicable for correcting the orbit of circular accelerators is proposed. The method is based on the definition of a suitable cost function which weighs both orbit deviations and the correction effort, that is steerer kicks. The paper presents the full derivation of the formulas and the results of simulations. The application of this method for the Global Orbit Feedback system of the ELETTRA storage ring is being evaluated.
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| WEPCH077 | Particle Tracking in a Sextupole Field using the Euler Method Approximation | sextupole, lattice, dynamic-aperture, LEFT | 2098 | ||
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The purpose of this paper is to evaluate any differences in the single particle tracking through a magnetic lattice when sextupoles are treated either like sliced or single-kick elements. Only on-energy transverse motion is considered. Convergence and symplecticity of the method of sliced sextupoles are discussed. Dynamic apertures and transverse phase spaces applied to the Elettra synchrotron lattice are compared for the two cases.
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| WEPLS070 | The Elettra Booster Magnets Construction Status | sextupole, booster, dipole, quadrupole | 2541 | ||
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The third generation light source ELETTRA has been in operation since 1993. A new 2.5 GeV full energy booster injector has been approved and founded last year. It will replace the existing linear injector limited to a maximum energy of 1.2 GeV. During last year, after having completed the specifications and the preliminary magnetic and mechanical design, the orders for all the magnets were assigned to two European firms. The paper reports on the magnets' construction status and the requested specifications.
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| THPCH043 | Jitter Studies for the FERMI@ELETTRA Linac | linac, electron, FEL, simulation | 2880 | ||
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The FEL project FERMI@ELETTRA* will use the existing linac upgraded to 1.2GeV to produce photon pulses in the wavelength range between 100-10 nm by means of harmonic generation in a seeded scheme. FEL operations foresee stringent requirements for the stability of the global linac output parameters, such as the electron bunch arrival time, peak current, average energy and the slice electron bunch parameters, such as the slice peak current and slice average energy. In order to understand the sensitivity of these parameters to jitters of various error sources along the linac an elaborate study using tracking codes has been performed. As a result, we created a tolerance budget to be used as guidance in the design of the linac upgrade. In this paper we give a detailed description of the applied procedures and present the obtained results.
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*C. Bocchetta et al. "FERMI@ELETTRA - Conceptual Design for a Seeded Harmonic Cascade FEL for EUV and Soft X-rays", this conference. |
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| THPCH045 | Transverse Head-tail Modes Elimination with Negative Chromaticity and the Transverse Multi-bunch Feedback System at ELETTRA | feedback, impedance, coupling, kicker | 2886 | ||
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The rigid dipole head-tail mode threshold at ELETTRA is by now quite low and increasing positively the chromaticity does not bring a much overall advantage in the machine performance. Using the bunch-by-bunch transverse feedback (TMFB), a threshold increase has been observed until the onset of the higher modes, which being bunch shape modes cannot be detected and therefore eliminated by the feedback system. To overcome this problem the machine has been set to a small but negative chromaticity. In this case the m=0 mode is unstable with a very low (<1 mA/bunch) threshold but the higher modes should be stable, especially when the main source of the transverse impedance comes from the resistive wall as in our case. Indeed when activating the TMFB no onset of any modes was observed within reasonable current limits (15 mA/bunch) that we plan to further investigate. In the paper after a theoretical discussion on the role of chromaticity and various types of impedances in the head-tail onset mechanism, the experimental results are presented and discussed.
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| THPCH091 | Status of the ELETTRA Global Orbit Feedback Project | feedback, controls, electron, closed-orbit | 3003 | ||
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A fast digital feedback system is under development to stabilize the electron beam closed orbit at the ELETTRA storage ring in the band up to 300 Hz. In view of the implementation of the feedback, the existing orbit measurement system will be upgraded to allow for better accuracy in the beam position measurement and higher acquisition rate. A global correction algorithm running on a number of distributed processing units will correct the orbit using all of the storage ring steerer magnets. The status of the project development is given in this article.
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| THPLS031 | Elettra Top-up Requirements and Design Status | injection, electron, insertion, insertion-device | 3350 | ||
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Elettra is a 2.5 GeV third generation light source in operation since 1993. To provide more stable beams to the users, we plan to operate in the so-called top-up injection mode. The first step is the substitution of the present 1GeV linac by a 100 MeV pre-injector linac and a fast cycling 2.5 GeV synchrotron booster foreseen to be in operation in 2007*. The present paper will report on the requirements for the top-up operation in terms of radiation safety, diagnostics H/S, timing, modality, etc. and the design status. In particular, a new BPM system, based on the log-ratio detectors, has been successfully commissioned on the present transfer line and linac and is ready to be deployed on the new injector and to be used by the new foreseen shot to shot transfer line booster to storage trajectory feedback system. Furthermore, in order to flatten the storage ring filling, the top-up charge will be integrated where needed. Preliminary measurements on the bunch by bunch measurement methods of the storage ring bunch charge are reported.
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*“Elettra New Full Energy Injector Status Report”, these proceedings. |
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| THPLS032 | ELETTRA New Full Energy Injector High Level Software | controls, lattice, optics, insertion-device | 3353 | ||
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The control system for the new full energy injector* will be entirely based on Tango with an object oriented distributed architecture. The availability of the new and modern software platform led us to design and develop a new high level software framework which allows a model-based accelerator control. The new design is fully object oriented and follows a layered approach. The main layers provide a set of different views or abstractions of the underlying accelerator: field layer, machine layer, and optics layer. The field layer handles all the access and communications with the actual devices of the accelerator, e.g., power supplies, instrumentation, etc. The machine layer handles the machine layout description, functional constraints like the association of a string of magnets with one power supply, and the conversion from actual values acquired from the field into values meaningful to beam dynamics problems. The optics layer performs all the actual calculations concerning the beam like beta functions, damping times, etc. An important characteristic of the new library is the unified management of all the needed calibrations and configurations by means of a relational database.
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*“Elettra New Full Energy Injector Status Report”, these proceedings. |
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| THPLS033 | Elettra New Full Energy Injector Status Report | booster, dipole, quadrupole, storage-ring | 3356 | ||
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The Elettra new full energy injector will be based on a 100 MeV linac pre-injector, a 2.5 GeV booster synchrotron and two new beam transfer lines. It will replace the existing 1.2 GeV linac injector and transfer line. Full funding was finally available in 2005, which allowed to start, or in some cases to re-start, the construction activities. The status of the project will be presented in this paper, in particular the progress of the fabrication of various components, like magnets, power supplies, vacuum chambers; also the status of the construction of the building and technical plants will be given. Results of recent optimization studies will also be outlined. The commissioning of the new injector is scheduled to start in Spring 2007, while the first ELETTRA operation for user's with the new full energy injector is expected for the last quarter of 2007.
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| THPLS134 | A General View of IDs to be Installed at ALBA on Day One | undulator, wiggler, polarization, radiation | 3598 | ||
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The new 3rd generation synchrotron radiation source ALBA to be built nearby Barcelona is planned to start operation in 2009 with several different insertion devices installed in the storage ring either from "day one" or within the first year of operation. The list of high-priority insertion devices includes: 2 planar PPM SmCo in-vacuum undulators with the period of 21.3 mm; 2 Apple-II type PPM NdFeB undulators with the period of 71 mm; 1 superconducting planar wiggler with the period of 30 mm and a maximum field of 2 T, and a 1 conventional wiggler with the period of 65 mm and a maximum field of 1.55 T. The emission of these undulators covers wide spectral range extending from hard X-rays to UV. Pre-design of the IDs was done by ALBA. The construction will be done by industrial companies and institutions with production capabilities. ALBA will set up a magnetic measurement laboratory for the acceptance tests. The paper will present peculiarities of the magnetic design, calculated maximum-flux spectra and associated heat load in various modes of operation.
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