1,721,048 research outputs found
Development of diagnostic and manipulation systems for space-charge dominated electron beams and confined electron plasmas in ELTRAP
No full textModifications have been implemented in the Penning-Malmberg device ELTRAP aimed
at performing studies on the dynamics of space-charge dominated nanosecond electron bunches traveling along the magnetic field. In particular, a Thomson backscattering apparatus has been developed where an infrared (IR) laser pulse collides with the bunched electron beam. The frequency-shifted
backscattered radiation, acquired by means of a photomultiplier (PMT), can be exploited to evaluate information on energy, energy spread and density of the bunch. The achievable sensitivity
of the diagnostics has been estimated, and valuable information on the main parameters affecting the signal-to-noise (S/N) ratio has been obtained [B. Paroli, F. Cavaliere, M. Cavenago, F. De Luca, M. Ikram, G. Maero, C. Marini, R. Pozzoli, and M. Romé, JINST 7, P01008 (2012)]. A series of upgrades are under way, aimed at increasing the S/N ratio through the use of a new laser for the electron source, the insertion of a stray light shield, and the optimization of the detection electronics. Moreover, electromagnetic simulations relevant to the design and implementation of a microwave
heating system are presented. The generation of an electron plasma in ELTRAP by means of a low-power radio frequency (RF) drive in the MHz range applied on one of the trap electrodes and under ultra-high vacuum (UHV) conditions has previously been demonstrated [B. Paroli, F. De Luca,
G. Maero, F. Pozzoli, and M. Romé, Plasma Sources Sci. Technol. 19, 045013 (2010)]. The new heating system will allow the extension of the RF studies to the GHz range and in particular the
production of a more energetic electron plasma via cyclotron resonant excitation
Two-dimensional mapping of the asymmetric lateral coherence of thermal light
Full text linkWe report in this work the first experimental verification of the asymmetric lateral coherence which is a measurement of the spatio-temporal coherence by using a wide-band Young interference experiment with a fixed off-axis slit. We demonstrate the coherence properties through the measurement of the real part of the coherence factor of thermal light. We extend our recent results obtained for betatron and undulator radiations providing a robust experimental method for the two-dimensional mapping of the two-point correlation function of broadband radiation preserving the phase information. The proposed method can be used as a high-sensitivity alternative to traditional interferometry with quasi-monochromatic radiation
THOMSON BACKSCATTERING DIAGNOSTICS OF NANOSECOND ELECTRON BUNCHES IN HIGH SPACE CHARGE REGIME
Full text linkThe intra-beam repulsions play a significant role in determining the performances of free-electron devices when an high brilliance of the beam is required. The transversal and longitudinal spread of the beam, its energy and density are fundamental parameters in any beam experiment and different beam diagnostics are available to measure such parameters. A diagnostic method based on the Thomson backscattering of a laser beam impinging on the particle beam is proposed in this work for the study of nanosecond electron bunches in high space charge regime. This diagnostics, aimed to the measurement of density, energy and energy spread, was set-up in a Malmberg-Penning trap (generally used for the electron/ion confinment) in two different configurations designed to optimize sensitivity, spatial resolution and electron-beam coincidence in space and time. To this purpose an electron bunch (pulse time <4 ns), produced by a photocathode source, was preliminary characterized with different electrostatic diagnostics and used to test the diagnostics systems. The solutions are detailed, which were devised for both the laser and bunch injection in the vacuum chamber, space and time coincidence of electron and laser pulses, photon detection, optimization of the geometry in the laser-beam interaction. The results are then summarized with an estimate of the minimum sensitivity of the set-up
Method and system for transmitting and receiving an electromagnetic radiation beam with detection of orbital angular momentum and related telecommunication method and system
No full textA method for transmitting and receiving an electromagnetic radiation beam, adapted to determine an orbital angular momentum of the received electromagnetic radiation beam, is described. There is further described a system for transmitting and receiving an electromagnetic radiation beam, capable of performing the aforesaid method. A method for performing a telecommunication of signals modulated according to any modulation technique and grouped by means of orbital angular momentum multiplexing is further described There is further described a telecommunication system capable of performing the aforesaid method for performing a telecommunication of modulated signals
METHOD AND SYSTEM FOR DEMULTIPLEXING AND DEMODULATING SIGNALS MULTIPLEXED IN THE VARIABLE ORBITAL ANGULAR MOMENTUM
No full textA method for demultiplexing and demodulating (in particular, "locally" demultiplexing and demodulating) amplitude-modulated signals grouped by means of orbital angular momentum multiplexing is described. The method involves demultiplexing and demodulating information a(t), b(t) modulated on each of a first modulated beam Fm1 and at least one second modulated beam Fm2, based on phase difference values AP and AR detected by beam detectors located downstream of an interferometric structure 40 to which two portions of the electromagnetic beam carrying the modulated channels are provided as inputs, multiplexed in the orbital angular momentum variable. There is also described a corresponding system 100 for demultiplexing and demodulating amplitude-modulated signals capable of implementing the aforesaid method
The local intrinsic curvature of wavefronts allows to detect optical vortices
Full text linkWe describe a method for effectively distinguishing the radiation endowed with optical angular momentum, also known as optical vortex, from ordinary light. We show that by detecting the inversion of the transverse intrinsic curvature sign (ITICS) an optical vortex can be locally recognized. The method is effective under conditions of huge importance for the exploitation of optical vortices, such as the far field of the source and access to a small fraction of the wavefront only. The validity of the method has been verified with table-top experiments with visible light, and the results show that a measurement performed over a transverse distance smaller than 4% of the beam diameter distinguishes a vortex from a Gaussian beam with a significance of 93.4%. New perspectives are considered for the characterization of vortices, with potential impact on the detection of extra-terrestrial radiation as well as on broadcast communication techniques
Radiation emission processes and properties: synchrotron, undulator and betatron radiation
Full text linkSynchrotron, undulator and betatron radiations are generated from last generation and novel concept sources. The achievement of unprecedented radiation properties opens new opportunities in various research fields as well as novel potential applications. In particular, bright coherent X-rays and (Formula presented.) -rays have been recently obtained thanks to enormous efforts in technological advancements and research activities. We give in this work a uniform argumentation and comparison of the main fundamental emission processes and radiation properties of synchrotron, undulator and betatron radiations. Emphasis is given to spatial coherence and related diagnostics, a fundamental property for any ‘modern light source’ and a basis for recent important advancements
Analogical optical modeling of the asymmetric lateral coherence of betatron radiation
Full text linkBy exploiting analogical optical modeling of the radiation emitted by ultrarelativistic electrons undergoing betatron oscillations, we demonstrate peculiar properties of the spatial coherence through an interferometric method reminiscent of the classical Young's double slit experiment. The expected effects due to the curved trajectory and the broadband emission are accurately reproduced. We show that by properly scaling the fundamental parameters for the wavelength, analogical optical modeling of betatron emission can be realized in many cases of broad interest. Applications to study the feasibility of future experiments and to the characterization of beam diagnostics tools are described
Single-shot measurement of phase and topological properties of orbital angular momentum radiation through asymmetric lateral coherence
Full text linkWe show a single-shot technique to measure topological and phase properties of radiation carrying orbital angular momentum. The single-shot method is effectively described as the one-dimensional case of a more general two-dimensional approach based on scanning interferometry (asymmetric lateral coherence). The validity of the method has been experimentally verified and the applicability to ultrarelativistic sources of hard x-rays has been discussed. The method is suitable to characterize phase and topological properties of x-ray sources by using simple apertures
A systematic study of the asymmetric lateral coherence of radiation emitted by ultra-relativistic particles in laser-driven accelerators
No full textWe show the results of a systematic study of the properties recently evidenced for the asymmetric lateral coherence of broadband radiation emitted by particles in betatron motion. 2-dimensional Montecarlo simulations have been used in order to investigate changes of the coherence properties by varying the spatial distribution of an ensemble of particles, whose parameters match those of the electron beams at the SPARC_LAB test facility. A clear interpretation is given under several conditions, and applications to diagnostics of particle beams appear a natural exploitation of the coherence measurements
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