170 research outputs found
Light Ion Accelerating Line (L3IA): Test Experiment at ILIL-PW
The construction of a novel Laser driven Light Ions Acceleration Line(L3IA)
is progressing rapidly towards the operation, following the recent upgrade of
the ILIL-PW laser facility. The Line was designed following the pilot
experimental activity carried out earlier at the same facility to define design
parameters and to identify main components including target control and
diagnostic equipment, also in combination with the numerical simulations for
the optimization of laser and target parameters. A preliminary set of data was
acquired following the successful commissioning of the laser system >100 TW
upgrade. Data include output from a range of different ion detectors and
optical diagnostics installed for qualification of the laser-target
interaction. An overview of the results is given along with a description of
the relevant upgraded laser facility and features.Comment: 6 pages, 7 figures, 18 references, presented at the EAAC 201
Production and service properties of micro-alloyed steel components for the motor industry
In the mechanical engineering sector, there is now a marked trend towards the use of micro-alloyed steels in the form of long products as cost-effective substitutes for hardened and tempered steels. In addition to laboratory tests on the initial steels to check verifiable properties which can provide a first-step indication of properties in use, it is also important to ascertain the suitability of steels for various end applications by direct tests on components in actual service.The case of crankshafts considered in this paper represents the start of a comprehensive programme of tests on components initiated by Fiat Auto and can be regarded as one example of an approach to the problems of using micro-alloyed steels which was brought to a successful conclusion
Overview and specifications of laser and target areas at the Intense Laser Irradiation Laboratory
Abstract
We present the main features of the ultrashort, high-intensity laser installation at the Intense Laser Irradiation Laboratory (ILIL) including laser, beam transport and target area specifications. The laboratory was designed to host laser–target interaction experiments of more than 220 TW peak power, in flexible focusing configurations, with ultrarelativistic intensity on the target. Specifications have been established via dedicated optical diagnostic assemblies and commissioning interaction experiments. In this paper we give a summary of laser specifications available to users, including spatial, spectral and temporal contrast features. The layout of the experimental target areas is presented, with attention to the available configurations of laser focusing geometries and diagnostics. Finally, we discuss radiation protection measures and mechanical stability of the laser focal spot on the target
Evidence of resonant surface wave excitation in the relativistic regime through measurements of proton acceleration from grating targets
The interaction of laser pulses with thin grating targets, having a periodic
groove at the irradiated surface, has been experimentally investigated.
Ultrahigh contrast () pulses allowed to demonstrate an enhanced
laser-target coupling for the first time in the relativistic regime of
ultra-high intensity >10^{19} \mbox{W/cm}^{2}. A maximum increase by a factor
of 2.5 of the cut-off energy of protons produced by Target Normal Sheath
Acceleration has been observed with respect to plane targets, around the
incidence angle expected for resonant excitation of surface waves. A
significant enhancement is also observed for small angles of incidence, out of
resonance.Comment: 5 pages, 5 figures, 2nd version implements final correction
Test of candidate light distributors for the muon (g2) laser calibration system
The new muon (g-2) experiment E989 at Fermilab will be equipped with a laser
calibration system for all the 1296 channels of the calorimeters. An
integrating sphere and an alternative system based on an engineered diffuser
have been considered as possible light distributors for the experiment. We
present here a detailed comparison of the two based on temporal response,
spatial uniformity, transmittance and time stability.Comment: accepted to Nucl.Instrum.Meth.
Time evolution of stimulated Raman scattering and two-plasmon decay at laser intensities relevant for shock ignition in a hot plasma
Laser–plasma interaction (LPI) at intensities 1015–1016 W cm2 is dominated by parametric instabilities which can be
responsible for a significant amount of non-collisional absorption and generate large fluxes of high-energy nonthermal
electrons. Such a regime is of paramount importance for inertial confinement fusion (ICF) and in particular for the
shock ignition scheme. In this paper we report on an experiment carried out at the Prague Asterix Laser System (PALS)
facility to investigate the extent and time history of stimulated Raman scattering (SRS) and two-plasmon decay (TPD)
instabilities, driven by the interaction of an infrared laser pulse at an intensity 1:2 1016 W cm2 with a 100 mm
scalelength plasma produced from irradiation of a flat plastic target. The laser pulse duration (300 ps) and the high
value of plasma temperature (4 keV) expected from hydrodynamic simulations make these results interesting for a
deeper understanding of LPI in shock ignition conditions. Experimental results show that absolute TPD/SRS, driven at
a quarter of the critical density, and convective SRS, driven at lower plasma densities, are well separated in time, with
absolute instabilities driven at early times of interaction and convective backward SRS emerging at the laser peak and
persisting all over the tail of the pulse. Side-scattering SRS, driven at low plasma densities, is also clearly observed.
Experimental results are compared to fully kinetic large-scale, two-dimensional simulations. Particle-in-cell results,
beyond reproducing the framework delineated by the experimental measurements, reveal the importance of filamentation
instability in ruling the onset of SRS and stimulated Brillouin scattering instabilities and confirm the crucial role of
collisionless absorption in the LPI energy balance
Study of shock waves generation, hot electron production and role of parametric instabilities in an intensity regime relevant for the shock ignition
We present experimental results at intensities relevant to Shock Ignition
obtained at the sub-ns Prague Asterix Laser System in 2012 . We studied shock waves
produced by laser-matter interaction in presence of a pre-plasma. We used a first beam at
1ω (1315 nm) at 7 × 10 13 W/cm 2 to create a pre-plasma on the front side of the target and
a second at 3ω (438 nm) at ∼ 10 16 W/cm 2 to create the shock wave. Multilayer targets
composed of 25 (or 40 μm) of plastic (doped with Cl), 5 μm of Cu (for Kα diagnostics)
and 20 μm of Al for shock measurement were used. We used X-ray spectroscopy of Cl
to evaluate the plasma temperature, Kα imaging and spectroscopy to evaluate spatial and
spectral properties of the fast electrons and a streak camera for shock breakout measurements.
Parametric instabilities (Stimulated Raman Scattering, Stimulated Brillouin Scattering and
Two Plasmon Decay) were studied by collecting the back scattered light and analysing its
spectrum. Back scattered energy was measured with calorimeters. To evaluate the maximum
pressure reached in our experiment we performed hydro simulations with CHIC and DUED
codes. The maximum shock pressure generated in our experiment at the front side of the
target during laser-interaction is 90 Mbar. The conversion efficiency into hot electrons was
estimated to be of the order of ∼ 0.1% and their mean energy in the order ∼50 keV.
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributio
Taming Volatile High Frequency Data with Long Lag Structure: An Optimal Filtering Approach for Forecasting
Growth and cycles of the Italian economy since 1861: the new evidence
Based on a newly-available large set of historical national accounts, the paper revisits the main features of economic growth and cycles in Italy for the post-Unification period 1861-2011. Alongside the structural changes in growth dynamics, the main sources of output and productivity growth are identified. As regards the analysis of the underlying cyclical component, a business cycle chronology is first established and then both the specific patterns of individual cycles and the co-movements of output with key macroeconomic variables are investigated. In the 150 years since its political Unification, Italy's economic growth was mainly propelled by consumption and investments, whereas on the supply side the industry and services sectors were by far the main contributors, also because of the positive effect of labour reallocation to nonfarm activities. Over the same period, Italy experienced approximately 20 business cycles of varying duration and amplitude. Output fluctuations were dominated by the short-term variability of agricultural production before World War II and by fluctuations of the industry sector thereafter. The cyclical behaviour exhibited by aggregate demand components conforms quite well to that evidenced in the standard international business cycle literature, although some exceptions arise in the pre-World War II years
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