| Paper | Title | Page |
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| MOPKF035 | Stabilization of the Pulsed Regimes on Storage Ring Free Electron Laser: The Cases of Super-ACO and Elettra | 381 |
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In a Storage Ring Free Electron Laser (SRFEL) a relativistic electron beam interacts with the magnetostatic periodic field of an undulator, thus emitting synchrotron radiation. The light is stored in an optical cavity and amplified during successive turns of the particles in the ring. The laser intensity may appear as a "continuous wave (cw)" or show a stable pulsed behaviour depending on the value of the temporal detuning, i.e. the difference between the electron beam revolution period and the round trip of the photons in the cavity. It was recently shown, that the loss of stability in a SRFEL occurs through an Hopf bifurcation [*]. This observation opens up the perspective of introducing a derivative self-controlled feedback to suppress locally the bifurcation and enlarge the region of stable signal. A feedback of this type has been implemented on Super-ACO and shown to produce a significant and reproducible extension of the stable "cw" region. We review here these results and discuss new experiments performed on the Super-ACO and ELETTRA SRFELs.
* G. De Ninno and D. Fanelli, Phys. Rev. Lett. in press; M.E. Couprie et al. Nucl. Instrum.and Meth. A., in press |
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| MOPKF037 | FERMI@ELETTRA: 100 nm - 10 nm Single Pass FEL User Facility | 387 |
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| The FERMI@ELETTRA project is an initiative from ELETTRA, INFM and other Italian institutes, to construct a single-pass FEL user-facility for the wavelength range from 100 nm (12 eV) to 10 nm (124 eV), to be located next to the third-generation synchrotron radiation facility ELETTRA in Trieste, Italy. The project is concentrated around the existing 1.2-GeV S-band linac, i.e., the injector for the storage ring. Presently the linac is only operational for approximately 2 hours per day. The remaining time is available for the construction and operation of an FEL but modifications and operation must be planned such that operation of the storage ring can be guaranteed until the completion of a new full-energy injector (spring 2006). At this moment the FEL project evolves from a conceptional design stage towards a technical design and the actual implementation. Key issues are: incorporation of the free-electron laser in the infrastructure of the Sincrotrone Trieste, adjustments of the linac to facilitate FEL operation, required additional civil engineering, undulator design, FEL seeding options, and beamline design. This paper serves as an overview of the project in combination with a discussion of the critical issues involved. | ||
| MOPKF040 | Effect of Electron-beam Feedbacks on the ELETTRA Storage-ring Free-electron Laser | 393 |
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| As is well known, the stability of a storage-ring free-electron laser is strongly related to that of the electron beam. With respect to second-generation devices, such as Super ACO and UVSOR, the free-electron laser at ELETTRA is characterized by a noticeably higher gain and, consequently, shows to be much more sensitive to electron-beam instabilities. In order to counteract the impact of such instabilities, both a longitudinal multibunch and a local orbit feedbacks have been implemented for free-electron laser operation. Aim of this paper is to report on the beneficial effect of these feedback systems on the laser performance. |