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| 1 | Observation and modelling of stimulated Raman scattering driven by an optically smoothed laser beam in experimental conditions relevant for shock ignition显示文摘We report results and modelling of an experiment performed at the Target Area West Vulcan laser facility,aimed at investigating laser±plasma interaction in conditions that are of interest for the shock ignition scheme in inertial confinement fusion(ICF),that is,laser intensity higher than 10^(16) W/cm^(2) impinging on a hot(T>1 keV),inhomogeneous and long scalelength pre-formed plasma.Measurements show a significant stimulated Raman scattering(SRS)backscattering(;%-20%of laser energy)driven at low plasma densities and no signatures of two-plasmon decay(TPD)/SRS driven at the quarter critical density region.Results are satisfactorily reproduced by an analytical model accounting for the convective SRS growth in independent laser speckles,in conditions where the reflectivity is dominated by the contribution from the most intense speckles,where SRS becomes saturated.Analytical and kinetic simulations well reproduce the onset of SRS at low plasma densities in a regime strongly affected by non-linear Landau damping and by filamentation of the most intense laser speckles.The absence of TPD/SRS at higher densities is explained by pump depletion and plasma smoothing driven by filamentation.The prevalence of laser coupling in the low-density profile justifies the low temperature measured for hot electrons(7-12 keV),which is well reproduced by numerical simulations. | G.Cristoforetti S.Hüller P.Koester L.Antonelli S.Atzeni F.Baffigi D.Batani C.Baird N.Booth M.Galimberti K.Glize A.Héron M.Khan P.Loiseau D.Mancelli M.Notley P.Oliveira O.Renner M.Smid A.Schiavi G.Tran N.C.Woolsey L.A.Gizzi | 2021 | High Power Laser Science and Engineering2021，9，4： | 1 |
| 2 | Reflecting laser-driven shocks in diamond in the megabar pressure range显示文摘In this work we present experimental results on the behavior of diamond at megabar pressure. The experiment was performed using the PHELIX facility at GSI in Germany to launch a planar shock into solid multi-layered diamond samples. The target design allows shock velocity in diamond and in two metal layers to be measured as well as the free surface velocity after shock breakout. As diagnostics, we used two velocity interferometry systems for any reflector(VISARs). Our measurements show that for the pressures obtained in diamond(between 3 and 9 Mbar),the propagation of the shock induces a reflecting state of the material. Finally, the experimental results are compared with hydrodynamical simulations in which we used different equations of state, showing compatibility with dedicated SESAME tables for diamond. | K.Jakubowska D.Mancelli R.Benocci J.Trela I.Errea A.S.Martynenko P.Neumayer O.Rosmej B.Borm A.Molineri C.Verona D.Cannatà A.Aliverdiev H.E.Roman D.Batani | 2021 | High Power Laser Science and Engineering2021，9，1： | 1 |
| 3 | Characterization of hot electrons generated by laser-plasma interaction at shock ignition intensities显示文摘In an experiment carried out at the Prague Asterix Laser System at laser intensities relevant to shock ignition conditions(I>10^(16) W/cm^(2)),the heating and transport of hot electrons were studied by using several complementary diagnostics,i.e.,K_(α)time-resolved imaging,hard x-ray filtering(a bremsstrahlung cannon),and electron spectroscopy.Ablators with differing composition from low Z(parylene N)to high Z(nickel)were used in multilayer planar targets to produce plasmas with different coronal temperature and collisionality and modify the conditions of hot-electron generation.The variety of available diagnostics allowed full characterization of the population of hot electrons,retrieving their conversion efficiency,time generation and duration,temperature,and angular divergence.The obtained results are shown to be consistent with those from detailed simulations and similar inertial confinement fusion experiments.Based on the measured data,the advantages,reliability,and complementarity of the experimental diagnostics are discussed. | E.D.Filippov M.Khan A.Tentori P.Gajdos A.S.Martynenko R.Dudzak P.Koester G.Zeraouli D.Mancelli F.Baffigi L.A.Gizzi S.A.Pikuz Ph.D.Nicolaï N.C.Woolsey R.Fedosejevs M.Krus L.Juha D.Batani O.Renner G.Cristoforetti | 2023 | Matter and Radiation at Extremes2023，8，6： | 0 |
| 4 | Time evolution of stimulated Raman scattering and two-plasmon decay at laser intensities relevant for shock ignition in a hot plasma显示文摘Laser–plasma interaction(LPI)at intensities 1015–1016 W·cm^-2 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·cm^-2 with a^100μm scalelength plasma produced from irradiation of a flat plastic target.The laser pulse duration(300 ps)and the high value of plasma temperature(~4 ke V)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. | G.Cristoforetti L.Antonelli D.Mancelli S.Atzeni F.Baffigi F.Barbato D.Batani G.Boutoux F.D'Amato J.Dostal R.Dudzak E.Filippov Y.J.Gu L.Juha O.Klimo M.Krus S.Malko A.S.Martynenko Ph.Nicolai V.Ospina S.Pikuz O.Renner J.Santos V.T.Tikhonchuk J.Trela S.Viciani L.Volpe S.Weber L.A.Gizzi | 2019 | High Power Laser Science and Engineering2019，7，3： | 0 |
| 5 | Multibeam laser-plasma interaction at the Gekko XII laser facility in conditions relevant for direct-drive inertial confinement fusion显示文摘Laser–plasma interaction and hot electrons have been characterized in detail in laser irradiation conditions relevant for direct-drive inertial confinement fusion.The experiment was carried out at the Gekko XII laser facility in multibeam planar target geometry at an intensity of approximately 3×10^(15)W/cm^(2).Experimental data suggest that high-energy electrons,with temperatures of 20–50 keV and conversion efficiencies ofη<1%,were mainly produced by the damping of electron plasma waves driven by two-plasmon decay(TPD).Stimulated Raman scattering(SRS)is observed in a near-threshold growth regime,producing a reflectivity of approximately 0.01%,and is well described by an analytical model accounting for the convective growth in independent speckles.The experiment reveals that both TPD and SRS are collectively driven by multiple beams,resulting in a more vigorous growth than that driven by single-beam laser intensity. | G.Cristoforetti P.Koester S.Atzeni D.Batani S.Fujioka Y.Hironaka S.Hüller T.Idesaka K.Katagiri K.Kawasaki R.Kodama D.Mancelli Ph.Nicolai N.Ozaki A.Schiavi K.Shigemori R.Takizawa T.Tamagawa D.Tanaka A.Tentori Y.Umeda A.Yogo L.A.Gizzi | 2023 | High Power Laser Science and Engineering2023，11，2： | 0 |
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