Multi-bunch instabilities degrade the performance of modern synchrotron light sources by leading ... more Multi-bunch instabilities degrade the performance of modern synchrotron light sources by leading to increased beam emittance, energy spread or even to beam loss. In order to damp any potentially excited transverse/longitudinal coupled-bunch mode of the 432 2-ns spaced bunches, a bunch-by-bunch feedback approach has been chosen for ELETTRA. The additional requirements for flexibility and availability of diagnostic tools have led to the development of a digitally based scheme which, running the appropriate software, is being used for both the transverse and longitudinal multi-bunch feedback systems. The transverse feedback has been installed and the latest operational results are reported. The design and current status of the longitudinal system are given.
The rigid dipole head-tail mode shift at Elettra is by now quite large and increasing the chromat... more The rigid dipole head-tail mode shift at Elettra is by now quite large and increasing the chromaticity does not bring a much overall advantage in the machine performance. Using the transverse multi-bunch feedback [1] a small improvement has been observed but only until the onset of the transverse mode coupling, since higher modes being bunch shape modes cannot be detected and therefore suppressed by the feedback system. This situation changes with negative chromaticity. In this case the rigid mode is unstable but a feedback system could in principle stabilize it, while the higher modes should be stable. In this paper this hypothesis is investigated and experimental measurements are analyzed and discussed.
Coupled-bunch instabilities excited by RF cavity high order modes or resistive wall impedance can... more Coupled-bunch instabilities excited by RF cavity high order modes or resistive wall impedance can seriously limit the performance of third generation synchrotron light sources like ELETTRA. These instabilities can be cured by the use of active feedback systems. In the digital bunch-by-bunch approach adopted at ELETTRA, the position of the 432 bunches is sampled and corrected employing 500 Msample/s A/D and D/A converters. The correction values are computed by a multi-processor architecture made of state-of-the-art DSPs (Digital Signal Processors). A modular design allows to use commercial- off-the-shelf (COTS) components for the most critical parts of the system.
Bunch-by-bunch feedback systems have been installed at ELETTRA to counteract coupled-bunch instab... more Bunch-by-bunch feedback systems have been installed at ELETTRA to counteract coupled-bunch instabilities. Following a novel approach both the transverse and the longitudinal systems rely on the same type of programmable digital processing electronics executing the proper software. After a description of the overall machine scenario in which the transverse systems are operated, the status of the longitudinal feedback commissioning is given
The control system for the new ELETTRA booster in- jector is currently in the design phase. Some ... more The control system for the new ELETTRA booster in- jector is currently in the design phase. Some of its main components and technologies, both hardware and software, have already been selected or are in the final testing phase. Our choices regarding Linux, C++ toolkits for GUI devel- opment and CORBA are discussed. In order to acquire some operating experience and
This article describes the design goals of FERMI@Elettra, reports on the goals achieved so far an... more This article describes the design goals of FERMI@Elettra, reports on the goals achieved so far and shows how the facility development has been driven by the new research frontier of ultra-fast, extreme ultra-violet and soft X-ray science. The commissioning phases and first experience with user pilot experiments are presented and discussed.
The injection system of ELETTRA relies on a high energy linac which has been bought as a turn-key... more The injection system of ELETTRA relies on a high energy linac which has been bought as a turn-key machine. The low level of reliability and flexibility of the original control system has led to the decision to completely redesign and integrate it with the ELETTRA control system which has proven high efficiency in the past years of operation. This paper describes the new software and hardware architecture developed.
Multi-bunch instabilities degrade the performance of modern synchrotron light sources by leading ... more Multi-bunch instabilities degrade the performance of modern synchrotron light sources by leading to increased beam emittance, energy spread or even to beam loss. In order to damp any potentially excited transverse/longitudinal coupled-bunch mode of the 432 2-ns spaced bunches, a bunch-by-bunch feedback approach has been chosen for ELETTRA. The additional requirements for flexibility and availability of diagnostic tools have led to the development of a digitally based scheme which, running the appropriate software, is being used for both the transverse and longitudinal multi-bunch feedback systems. The transverse feedback has been installed and the latest operational results are reported. The design and current status of the longitudinal system are given.
The rigid dipole head-tail mode shift at Elettra is by now quite large and increasing the chromat... more The rigid dipole head-tail mode shift at Elettra is by now quite large and increasing the chromaticity does not bring a much overall advantage in the machine performance. Using the transverse multi-bunch feedback [1] a small improvement has been observed but only until the onset of the transverse mode coupling, since higher modes being bunch shape modes cannot be detected and therefore suppressed by the feedback system. This situation changes with negative chromaticity. In this case the rigid mode is unstable but a feedback system could in principle stabilize it, while the higher modes should be stable. In this paper this hypothesis is investigated and experimental measurements are analyzed and discussed.
Coupled-bunch instabilities excited by RF cavity high order modes or resistive wall impedance can... more Coupled-bunch instabilities excited by RF cavity high order modes or resistive wall impedance can seriously limit the performance of third generation synchrotron light sources like ELETTRA. These instabilities can be cured by the use of active feedback systems. In the digital bunch-by-bunch approach adopted at ELETTRA, the position of the 432 bunches is sampled and corrected employing 500 Msample/s A/D and D/A converters. The correction values are computed by a multi-processor architecture made of state-of-the-art DSPs (Digital Signal Processors). A modular design allows to use commercial- off-the-shelf (COTS) components for the most critical parts of the system.
Bunch-by-bunch feedback systems have been installed at ELETTRA to counteract coupled-bunch instab... more Bunch-by-bunch feedback systems have been installed at ELETTRA to counteract coupled-bunch instabilities. Following a novel approach both the transverse and the longitudinal systems rely on the same type of programmable digital processing electronics executing the proper software. After a description of the overall machine scenario in which the transverse systems are operated, the status of the longitudinal feedback commissioning is given
The control system for the new ELETTRA booster in- jector is currently in the design phase. Some ... more The control system for the new ELETTRA booster in- jector is currently in the design phase. Some of its main components and technologies, both hardware and software, have already been selected or are in the final testing phase. Our choices regarding Linux, C++ toolkits for GUI devel- opment and CORBA are discussed. In order to acquire some operating experience and
This article describes the design goals of FERMI@Elettra, reports on the goals achieved so far an... more This article describes the design goals of FERMI@Elettra, reports on the goals achieved so far and shows how the facility development has been driven by the new research frontier of ultra-fast, extreme ultra-violet and soft X-ray science. The commissioning phases and first experience with user pilot experiments are presented and discussed.
The injection system of ELETTRA relies on a high energy linac which has been bought as a turn-key... more The injection system of ELETTRA relies on a high energy linac which has been bought as a turn-key machine. The low level of reliability and flexibility of the original control system has led to the decision to completely redesign and integrate it with the ELETTRA control system which has proven high efficiency in the past years of operation. This paper describes the new software and hardware architecture developed.
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Papers by M. Lonza