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ABSTRACT: Coupling impedances and wakefields are fundamental quantities to characterize the electromagnetic interaction of a particle beam with the surrounding environment. In particular, collective effects, triggered by these self-induced fields, may play an important role in beam stability and machine performance. Within the framework of the LHC Injectors Upgrade project, since a significantly higher beam intensity is planned for the CERN Proton Synchrotron, wakefields are expected to increase their influence on the beam dynamics, and their evaluation is becoming important. In this paper we present the results of recent measurements of the longitudinal broadband coupling impedance by means of the incoherent quadrupole synchrotron frequency shift as a function of beam intensity. A detailed evaluation of the contribution of several machine installations to the total impedance budget is also presented and compared with the measurements.
PHYSICAL REVIEW SPECIAL TOPICS AB. 01/2013; 16.
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S. Bini,
B. Spataro,
A. Marcelli,
S. Sarti,
V. A. Dolgashev,
S. Tantawi,
A. D. Yeremian,
Y. Higashi,
M. G. Grimaldi,
L. Romano,
F. Ruffino,
R. Parodi,
G. Cibin,
C. Marrelli, M. Migliorati,
C. Caliendo
[show abstract]
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ABSTRACT: Technological advancements are strongly required to fulfill the demands of
new accelerator devices with the highest accelerating gradients and operation
reliability for the future colliders. To this purpose an extensive R&D
regarding molybdenum coatings on copper is in progress. In this contribution we
describe chemical composition, deposition quality and resistivity properties of
different molybdenum coatings obtained via sputtering. The deposited films are
thick metallic disorder layers with different resistivity values above and
below the molibdenum dioxide reference value. Chemical and electrical
properties of these sputtered coatings have been characterized by Rutherford
backscattering, XANES and photoemission spectroscopy. We will also present a
three cells standing wave section coated by a molybdenum layer $\sim$ 500 nm
thick designed to improve the performance of X-Band accelerating systems.
12/2012;
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P Antici,
A Bacci,
C Benedetti,
E Chiadroni,
M Ferrario,
A R Rossi,
L Lancia, M Migliorati,
A Mostacci,
L Palumbo,
L Serafini
[show abstract]
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ABSTRACT: High-efficiency cross-beam magnetic electron-impact source for improved miniature Mattauch-Herzog mass spectrometer performance Rev. Sci. Instrum. 83, 064101 (2012) Electron current extraction from a permanent magnet waveguide plasma cathode Rev. Sci. Instrum. 82, 093507 (2011) NATALIE: A 32 detector integrated acquisition system to characterize laser produced energetic particles with nuclear techniques Rev. Sci. Instrum. 82, 023302 (2011) A novel large-orbit electron beam generated by a Cuccia coupler for a Ka-band third-harmonic slotted peniotron Phys. Plasmas 17, 123106 (2010) Bunch characteristics of an electron beam generated by a diamond secondary emitter amplifier Laser-driven electron beamlines are receiving increasing interest from the particle accelerator community. In particular, the high initial energy, low emittance, and high beam current of the plasma based electron source potentially allow generating much more compact and bright particle accelerators than what conventional accelerator technology can achieve. Using laser-generated particles as injectors for generating beamlines could significantly reduce the size and cost of accelerator facilities. Unfortunately, several features of laser-based particle beams need still to be improved before considering them for particle beamlines and thus enable the use of plasma-driven accelerators for the multiple applications of traditional accelerators. Besides working on the plasma source itself, a promising approach to shape the laser-generated beams is coupling them with conventional accelerator elements in order to benefit from both a versatile electron source and a controllable beam. In this paper, we perform start-to-end simulations to generate laser-driven beamlines using conventional accelerator codes and methodologies. Starting with laser-generated electrons that can be obtained with established multi-hundred TW laser systems, we compare different options to capture and transport the beams. This is performed with the aim of providing beamlines suitable for potential applications, such as free electron lasers. In our approach, we have analyzed which parameters are critical at the source and from there evaluated different ways to overcome these issues using conventional accelerator elements and methods. We show that electron driven beamlines are potentially feasible, but exploiting their full potential requires extensive improvement of the source parameters or innovative technological devices for their transport and capture. V C 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4740456]
Journal of Applied Physics 08/2012; 112(044902). · 2.17 Impact Factor
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ABSTRACT: SPARC C-band traveling wave cavities were originally designed for the SPARC energy upgrade in the single bunch operation mode. In the context of a gamma source based on Compton backscattering and based on the SPARC C-band technology, we investigated the issues related to the use of these structures in the multi-bunch operation mode. Several beam configurations have been considered and the effects of transverse and longitudinal long range wakefields on beam dynamics have been studied. In the paper we present the results of these studies and, in particular, the is-sues related to transverse beam break-up that could prevent the multi-bunch operation. Possible HOM damped struc-tures are also proposed.
Proceedings of IPAC2012, New Orleans, Luisiana, USA; 05/2012
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ABSTRACT: A sensitivity study is presented here on a compact hybrid postacceleration
scheme coupling laser-generated protons to a high frequency Linac based on the
use of a SCDTL (Side Coupled Drift Tube Linac) structure. The study analyzes
the main laser-generated beam characteristics and the most important parameters
linked to the accelerating structure. We show that the required tolerances regarding
alignment and field uniformity, although challenging, are within the reach of actual
technology. Regarding the laser-generated proton beam parameters (spot size and
divergence), we show that they have only a little influence on the final emittance that
is mainly determined by the capturing and accelerating structure. However, these
parameters can sensitively affect the final transmission of the proton beam current.
Journal of Plasma Physics 01/2012; · 0.94 Impact Factor
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P Antici,
A Bacci,
C. Benedetti,
E. Chiadroni,
M. Ferrario,
L Lancia, M Migliorati,
A Mostacci,
L Palumbo,
A R Rossi,
L. Serafini
[show abstract]
[hide abstract]
ABSTRACT: Laser-based electron acceleration is attracting strong interest from the
conventional accelerator community due to its outstanding characteristics in
terms of high initial energy, low emittance and high beam current.
Unfortunately, such beams are currently not comparable to those of conventional
accelerators, limiting their use for the manifold applications that a
traditional accelerator can have. Besides working on the plasma source itself,
a promising approach to shape the laser-generated beams is coupling them with
conventional accelerator elements in order to benefit from both, a versatile
electron source and a controllable beam.
In this paper we show that some parameters commonly used by the particle
accelerator community must be reconsidered when dealing with laser-plasma
beams. Starting from the parameters of laser-generated electrons which can be
obtained nowadays by conventional multi hundred TW laser systems, we compare
different conventional magnetic lattices able to capture and transport those
GeV electrons. From this comparison we highlight some important limit of the
state-of-the-art plasma generated electrons with respect to conventional
accelerator ones. Eventually we discuss an application of such beams in
undulators for Free Electron Lasers (FELs), which is one of the most demanding
applications in terms of beam quality.
12/2011;
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D Filippetto,
M Bellaveglia,
M Castellano,
E Chiadroni,
L Cultrera,
G Di Pirro,
M Ferrario,
L Ficcadenti,
A Gallo,
G Gatti, [......],
B Marchetti,
L Giannessi,
M Labat,
M Quattromini,
C Ronsivalle,
C Marrelli, M Migliorati,
A Mostacci,
L Palumbo,
M Serluca
[show abstract]
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ABSTRACT: Peak current represents a key demand for new generation electron beam photoinjectors. Many beam applications, such as free electron laser, inverse Compton scattering, terahertz radiation generation, have efficiencies strongly dependent on the bunch length and current. A method of beam longitudinal compression (called velocity bunching) has been proposed some years ago, based on beam longitudinal phase space rotation in a rf field potential. The control of such rotation can lead to a compression factor in excess of 10, depending on the initial longitudinal emittance. Code simulations have shown the possibility to fully compensate the transverse emittance growth during rf compression, and this regime has been experimentally proven recently at SPARC. The key point is the control of transverse beam plasma oscillations, in order to freeze the emittance at its lowest value at the end of compression. Longitudinal and transverse phase space distortions have been observed during the experiments, leading to asymmetric current profiles and higher final projected emittances. In this paper we discuss in detail the results obtained at SPARC in the regime of velocity bunching, analyzing such nonlinearities and identifying the causes. The beam degradation is discussed, both for slice and projected parameters. Analytical tools are derived to experimentally quantify the effect of such distortions on the projected emittance.
Physical Review Special Topics - Accelerators and Beams 09/2011; 14:92804. · 1.52 Impact Factor
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L Giannessi,
D Alesini,
P Antici,
A Bacci,
M Bellaveglia,
R Boni,
M Boscolo,
F Briquez,
M Castellano,
L Catani, [......],
L Serafini,
M Serluca,
I Spassovsky,
B Spataro,
V Surrenti,
C Vaccarezza,
M Vescovi,
C Vicario,
Sincrotrone Trieste,
Area Science
[show abstract]
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ABSTRACT: SPARC (acronym of ''Sorgente Pulsata ed Amplificata di Radiazione Coerente'', i.e. Pulsed and Amplified Source of Coherent Radiation) is a single pass free-electron laser designed to obtain high gain amplification at a radiation wavelength of 500 nm. Self-amplified spontaneous emission has been observed driving the amplifier with the high-brightness beam of the SPARC linac. We report measure-ments of energy, spectra, and exponential gain. Experimental results are compared with simulations from several numerical codes.
Physical Review Special Topics - Accelerators and Beams 06/2011; 14:060712. · 1.52 Impact Factor
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D Alesini,
A Bacci,
M Bellaveglia,
R Boni,
E Chiadroni,
G Di Pirro,
A Esposito,
M Ferrario,
A Gallo,
G Gatti, [......],
P Antici, M Migliorati,
A Mostacci,
L Palumbo,
F Broggi,
C De Martinis,
D Giove,
C Maroli,
V Petrillo,
L Serafini
[show abstract]
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ABSTRACT: We study the optimal lay-out and RF frequency for a room temperature GeV-class Electron Linac aimed at producing electron beams suitable for Compton back-scattering based gamma-ray sources. These emerging technology of generating tunable, bright, mono-chromatic photon beams in the range 5-20 MeV for nuclear physics and nuclear engineering, relies on high quality electron beams, and J-class high rep-rate synchronized laser systems, to achieve the maximum spectral density of the gamma-ray beam (# photons/sec/eV). The best RF band among the most used in RF linacs (S, C, X) will be identified and discussed.
IPAC, San Sebastian, Spain; 01/2011
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ABSTRACT: Protons generated by irradiating a thin metal foil with a high-intensity laser have shown to posses interesting characteristics in terms of energy, emittance, current, and pulse duration. Therefore, in the near future, they might become a competitive source with respect to conventional proton sources. Previous theoretical, numerical, and experimental studies have already demonstrated efficient coupling between laser-accelerated proton beams with traditional radio frequency (RF)-based particle accelerators. These hybrid proton accelerators benefit from both the excellent properties of the laser-based source and the flexibility, reliability, and know-how of beam handling as provided by RF-based accelerator structures. In this paper, state of the art experimental results of laser-accelerated proton beams are used as input for a numerical study using compact and innovative conventional accelerator structures designed for medical applications. Results show that this compact hybrid accelerator allows even more efficient capture and acceleration of the laser-generated proton beam. V C 2011 American Institute of Physics. [doi:
Journal of Plasma Physics 01/2011; · 0.94 Impact Factor
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B Spataro,
A Valloni,
D Alesini,
N Biancacci,
L Faillace,
L Ficcadenti,
A Fukusawa,
L Lancia, M Migliorati,
F Morelli,
A Mostacci,
B O 'shea,
L Palumbo,
J B Rosenzweig,
A Yakub
[show abstract]
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ABSTRACT: a b s t r a c t An INFN-LNF/UCLA/SAPIENZA collaboration is developing a hybrid photoinjector in X-band. A hybrid photoinjector is a novel high brightness electron source that couples a standing wave cell cavity (acting as an RF gun) directly to a multi-cell travelling-wave structure. This configuration offers a number of advantages over the split standing wave/travelling-wave system. Most notably the reflected RF transient is almost completely suppressed, thus eliminating the need for a circulator and the bunch lengthening effect that occurs in the drift section of the split system. These properties allow scaling of the device to higher field and frequencies, which should dramatically improve beam brightness. The RF coupling between the standing and the traveling wave sections is accomplished in the fourth cell encountered by the beam, with the SW section electrically coupled to it on-axis. This mode of coupling is particularly advantageous, as it is accompanied by a 901 phase shift in the accelerating field, resulting in strong velocity bunching effects on the beam that reverse the usual bunch lengthening induced after the gun exit in standard 1.6 cell photoinjectors. In this scenario, from the beam dynamics point of view, it is seen that device may produce ten's of femtosecond beams at $ 3.5 MeV and the emittance compensation dynamics remains manageable even in the presence of strong compression. We present here a survey of the device characteristics. In particular we show the results of the electromagnetic simulations, a beam dynamics analysis related to the temperature tuning of the SW and TW section, and a RF characterization using bead pull and scattering coefficient measurements of a device prototype. & 2011 Elsevier B.V. All rights reserved.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/2011; · 1.21 Impact Factor
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ABSTRACT: We discuss the conditions required for an optimal SASE FEL operation when bunch compression techniques are exploited to enhance the bunch peak current. We discuss the case of velocity bunching and magnetic bunch compression. With the reference to the latter technique we provide a quantitative estimate of the amount of laser heater power necessary to suppress the micro-bunching instability without creating any problem to the SASE dynamics
11/2010;
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L. Giannessi,
A. Petralia,
G. Dattoli,
F. Ciocci,
M. Del Franco,
M. Quattromini,
C. Ronsivalle,
E. Sabia,
I. Spassovsky,
V. Surrenti, [......],
J. Rosenzweig,
S. Spampinati,
M. Labat,
F. Briquez,
M. E. Couprie,
B. Carré,
M. Bougeard,
D. Garzella,
G. Lambert,
C.Vicario
[show abstract]
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ABSTRACT: We report on the recent activity at the SPARC FEL
where both SASE and seeded FEL dynamics are studied.
The SPARC FEL has been operated in full saturation in
SASE mode, by combining the velocity bunching
compression technique to increase the peak current, with
the idea proposed in [1] and consisting in a taper of the
undulator field to compensate the chirp in the longitudinal
phase space.
In seeded mode the FEL has been operated both as a
single amplifier and as a single stage cascade doubling the
frequency of the input seed at 400nm. We report on the
main results obtained in both the configurations.
32nd International Free Electron Laser Conference, Malmö, Sweden; 08/2010
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1st International Particle Accelerator Conference (IPAC'10), Kyoto, Japan; 05/2010
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ABSTRACT: Laser‐generated electron beams have gained in the last years a strong interest since it was discovered that TW laser systems are able to generate few hundreds of MeV electrons with high charge. These beams are potentially interesting for a number of applications, for which however beam transport might be needed. In the following study, we have used the particle accelerator tracking code MAD to capture, shape and transport laser generated electrons. In particular, our study has focused on 0.4–1 GeV electrons that could be generated by a 300 TW laser, such as the FLAME laser currently in the commissioning phase at INFN, Frascati. We have used different lattice structures to optimize the capture and transport of laser‐electrons. Results are shown and discussed.
AIP Conference Proceedings. 04/2010; 1228(1):346-350.
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M Ferrario,
D Alesini,
A Bacci,
M Bellaveglia,
R Boni,
M Boscolo,
M Castellano,
E Chiadroni,
A Cianchi,
L Cultrera, [......],
L Palumbo,
M Quattromini,
C Ronsivalle,
A R Rossi,
J Rosenzweig,
L Serafini,
M Serluca,
B Spataro,
C Vaccarezza,
C Vicario
[show abstract]
[hide abstract]
ABSTRACT: In this Letter we report the first experiments aimed at the simultaneous demonstration of the emittance compensation process and velocity bunching in a high brightness electron source, the SPARC photoinjector in INFN-LNF. While a maximum compression ratio up to a factor 14 has been observed, in a particular case of interest a compression factor of 3, yielding a slice current of 120 A with less than 2 microm slice emittance, has been measured. This technique may be crucial in achieving high brightness beams in photoinjectors aiming at optimized performance of short wavelength single-pass free electron lasers or other advanced applications in laser-plasma accelerators.
Physical Review Letters 02/2010; 104(5):054801. · 7.37 Impact Factor
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L Giannessi,
A Petralia,
G Dattoli,
F Ciocci,
M Del Franco,
M Quattromini,
C Ronsivalle,
E Sabia,
I Spassovsky,
V Surrenti, [......],
M Labat,
F Briquez,
M E Couprie,
Fr B Carré,
M Bougeard,
D Garzella,
Cea Saclay,
Dsm / Drecam,
Lambert Loa,
Fr C Vicario
[show abstract]
[hide abstract]
ABSTRACT: The SPARC FEL has been configured to test different cascaded FEL configurations with a seed generated in gas. In the framework of the DS4 EUROFEL collaboration, a research work plan at the SPARC FEL test facility aiming at the investigation of seeded and cascaded FEL configurations was implemented [1]. The main goal of the collaboration was to study the amplification and the harmonic generation process of an input seed signal, obtained as higher order harmonics generated in gases [2,3]. We describe here the first experimental results, which were recently obtained.
Free Electron Laser, Malmo, Sweden; 01/2010
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[show abstract]
[hide abstract]
ABSTRACT: Protons generated by the irradiation of a thin metal foil by a high-intensity short-pulse laser have shown to posses interesting characteristics in terms of energy, emittance, current and pulse duration. They might therefore become in the next future a competitive source to conventional proton sources. Previous theoretical and numerical studies already demonstrated the possibility of an efficient coupling between laser-plasma acceleration of protons with traditional RF based beam-line accelerator techniques. This hybrid proton accelerator would therefore benefit from the good properties of the laser-based source and from the flexibility and know-how of beam handling as given from RF based accelerator structure. The proton beam parameters of the source have been obtained from published laser interaction experimental results and are given as input to the numerical study by conventional accelerator design tools. In this paper we discuss recent results in the optimization and design of the such hybrid schemes in the context of proton accelerators for medical treatments.
IPAC2010; 01/2010
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ABSTRACT: Free-electron lasers operating in the UV or x-ray radiation spectrum require peak beam currents that are generally higher than those obtainable by present electron sources, thus making bunch compression necessary. Compression, however, may heighten the effects of collective forces and degrade the beam quality. In this paper we provide a framework for investigating some of these effects in rf compressors by focusing on the longitudinal dynamics of small-amplitude density perturbations, which have the potential to cause the disruptive appearance of the so-called microbunching instability. We develop a linear theory valid for low-to-moderate compression factors under the assumption of a 1D impedance model of longitudinal space charge and provide validation against macroparticle simulations.
Physical Review Special Topics - Accelerators and Beams 01/2010; 29. · 1.52 Impact Factor
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[show abstract]
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ABSTRACT: The laser heater has been proposed to damp the microbunching instability affecting the operation of free electron laser (FEL) self-amplified spontaneous emission (SASE) devices. The heater may be provided by an external laser or by a FEL oscillator using the same electron beam driving the SASE-FEL operation. The second solution offers undoubtful advantages, which will be discussed in this paper. We present simple physical arguments which allow the derivation of a criterion yielding the amount of laser power necessary to damp the instability, without compromising the FEL SASE operation.
Journal of Applied Physics 02/2009; · 2.17 Impact Factor
