570 research outputs found
Characterization of self-injected electron beams from LWFA experiments at SPARC_LAB
The plasma-based acceleration is an encouraging technique to overcome the
limits of the accelerating gradient in the conventional RF acceleration. A
plasma accelerator is able to provide accelerating fields up to hundreds of
, paving the way to accelerate particles to several MeV over a short
distance (below the millimetre range). Here the characteristics of preliminary
electron beams obtained with the self-injection mechanism produced with the
FLAME high-power laser at the SPARC_LAB test facility are shown. In detail,
with an energy laser on focus of and a pulse temporal length (FWHM) of
, we obtained an electron plasma density due to laser ionization of
about , electron energy up to and beam
charge in the range .Comment: 6 pages, 11 figures, conference EAAC201
Time-resolved characterization of ultrafast electrons in intense laser and metallic-dielectric target interaction
High-intensity ultrashort laser pulses interacting with thin solid targets are able to produce energetic ion beams by means of extremely large accelerating fields set by the energetic ejected electrons. The characterization of such electrons is thus important in view of a complete understanding of the acceleration process. Here, we present a complete temporal-resolved characterization of the fastest escaping hot electron component for different target materials and thicknesses, using temporal diagnostics based on electro-optical sampling with 100 fs temporal resolution. Experimental evidence of scaling laws for ultrafast electron beam parameters have been retrieved with respect to the impinging laser energy (0.4-4 J range) and to the target material, and an empirical law determining the beam parameters as a function of the target thickness is presented
Ultrafast electron and proton bunches correlation in laser--solid matter experiments
The interaction of an ultra-intense laser with a solid state target allows the production of multi-MeV proton and ion beams. This process is explained by the target normal sheath acceleration (TNSA) model, predicting the creation of an electric field on the target rear side, due to an unbalanced positive charge. This process is related to the emission of relativistic ultrafast electrons, occurring at an earlier time. In this work, we highlight the correlations between the ultrafast electron component and the protons by their simultaneous detection by means of an electro-optical sampling and a time-of-flight diagnostics, respectively, supported by numerical simulations showing an excellent agreement
Longitudinal phase-space manipulation with beam-driven plasma wakefields
The development of compact accelerator facilities providing high-brightness
beams is one of the most challenging tasks in field of next-generation compact
and cost affordable particle accelerators, to be used in many fields for
industrial, medical and research applications. The ability to shape the beam
longitudinal phase-space, in particular, plays a key role to achieve high-peak
brightness. Here we present a new approach that allows to tune the longitudinal
phase-space of a high-brightness beam by means of a plasma wakefields. The
electron beam passing through the plasma drives large wakefields that are used
to manipulate the time-energy correlation of particles along the beam itself.
We experimentally demonstrate that such solution is highly tunable by simply
adjusting the density of the plasma and can be used to imprint or remove any
correlation onto the beam. This is a fundamental requirement when dealing with
largely time-energy correlated beams coming from future plasma accelerators
Reexamination of a multisetting Bell inequality for qudits
The class of d-setting, d-outcome Bell inequalities proposed by Ji and
collaborators [Phys. Rev. A 78, 052103] are reexamined. For every positive
integer d > 2, we show that the corresponding non-trivial Bell inequality for
probabilities provides the maximum classical winning probability of the
Clauser-Horne-Shimony-Holt-like game with d inputs and d outputs. We also
demonstrate that the general classical upper bounds given by Ji et al. are
underestimated, which invalidates many of the corresponding correlation
inequalities presented thereof. We remedy this problem, partially, by providing
the actual classical upper bound for d less than or equal to 13 (including
non-prime values of d). We further determine that for prime value d in this
range, most of these probability and correlation inequalities are tight, i.e.,
facet-inducing for the respective classical correlation polytope. Stronger
lower and upper bounds on the quantum violation of these inequalities are
obtained. In particular, we prove that once the probability inequalities are
given, their correlation counterparts given by Ji and co-workers are no longer
relevant in terms of detecting the entanglement of a quantum state.Comment: v3: Published version (minor rewordings, typos corrected, upper
bounds in Table III improved/corrected); v2: 7 pages, 1 figure, 4 tables
(substantially revised with new results on the tightness of the correlation
inequalities included); v1: 7.5 pages, 1 figure, 4 tables (Comments are
welcome
Evolution of the electric fields induced in high intensity laser-matter interactions
Multi MeV protons \cite{snavely2000intense} and heavier ions are emitted by
thin foils irradiated by high-intensity lasers, due to the huge accelerating
fields, up to several teraelectronvolt per meter, at sub-picosecond timescale
\cite{dubois2014target}. The evolution of these huge fields is not well
understood till today. Here we report, for the first time, direct and
temporally resolved measurements of the electric fields produced by the
interaction of a short-pulse high-intensity laser with solid targets. The
results, obtained with a sub- fs temporal diagnostics, show that such
fields build-up in few hundreds of femtoseconds and lasts after several
picoseconds
Focusing of high-brightness electron beams with active-plasma lenses
Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. By overcoming current limits of conventional accelerators and pushing particles to larger and larger energies, the availability of strong and tunable focusing optics is mandatory also because plasma-accelerated beams usually have large angular divergences. In this regard, active-plasma lenses represent a compact and affordable tool to generate radially symmetric magnetic fields several orders of magnitude larger than conventional quadrupoles and solenoids. However, it has been recently proved that the focusing can be highly nonlinear and induce a dramatic emittance growth. Here, we present experimental results showing how these nonlinearities can be minimized and lensing improved. These achievements represent a major breakthrough toward the miniaturization of next-generation focusing devices
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