Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of supr...Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of suprathermal hot electrons under interaction conditions envisaged for direct-drive schemes for inertial confinement fusion.Nonetheless,SSRS remains to date one of the least understood parametric instabilities.Here,we report the first angularly and spectrally resolved measurements of scattered light at laser intensities relevant for the shock ignition scheme(I×10^(16)W/cm^(2)),showing significant SSRS growth in the direction perpendicular to the laser polarization.Modification of the focal spot shape and orientation,obtained by using two different random phase plates,and of the density gradient of the plasma,by utilizing exploding foil targets of different thicknesses,clearly reveals a different dependence of backward SRS(BSRS)and SSRS on experimental parameters.While convective BSRS scales with plasma density scale length,as expected by linear theory,the growth of SSRS depends on the spot extension in the direction perpendicular to laser polarization.Our analysis therefore demonstrates that under current experimental conditions,with density scale lengths L_(n)≈60–120μm and spot sizes FWHM≈40–100μm,SSRS is limited by laser beam size rather than by the density scale length of the plasma.展开更多
X-ray absorption spectroscopy is a well-accepted diagnostic for experimental studies of warm dense matter.It requires a short-lived X-ray source of sufficiently high emissivity and without characteristic lines in the ...X-ray absorption spectroscopy is a well-accepted diagnostic for experimental studies of warm dense matter.It requires a short-lived X-ray source of sufficiently high emissivity and without characteristic lines in the spectral range of interest.In the present work,we discuss how to choose an optimum material and thickness to get a bright source in the wavelength range 2A–6A(∼2 keV to 6 keV)by considering relatively low-Z elements.We demonstrate that the highest emissivity of solid aluminum and silicon foil targets irradiated with a 1-ps high-contrast sub-kJ laser pulse is achieved when the target thickness is close to 10μm.An outer plastic layer can increase the emissivity even further.展开更多
We present a novel scheme for rapid quantitative analysis of debris generated during experiments with solid targets following relativistic laser–plasma interaction at high-power laser facilities.Results are supported...We present a novel scheme for rapid quantitative analysis of debris generated during experiments with solid targets following relativistic laser–plasma interaction at high-power laser facilities.Results are supported by standard analysis techniques.Experimental data indicate that predictions by available modelling for non-mass-limited targets are reasonable,with debris of the order of hundreds ofμg per shot.We detect for the first time two clearly distinct types of debris emitted from the same interaction.A fraction of the debris is ejected directionally,following the target normal(rear and interaction side).The directional debris ejection towards the interaction side is larger than on the side of the target rear.The second type of debris is characterized by a more spherically uniform ejection,albeit with a small asymmetry that favours ejection towards the target rear side.展开更多
基金financial support from the LASERLAB-EUROPE Access to Research Infrastructure Activity (Application No. 23068)carried out within the framework of EUROfusion Enabling Research Projects AWP21-ENR-01-CEA02 and AWP24-ENR-IFE-02-CEA-02+3 种基金received funding from Euratom Research and Training Programme 2021–2025 under Grant No. 633053supported by the Ministry of Youth and Sports of the Czech Republic [Project No. LM2023068 (PALS RI)]by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDA25030200 and XDA25010100)supported by COST (European Cooperation in Science and Technology) through Action CA21128 PROBONO (PROton BOron Nuclear Fusion: from energy production to medical applicatiOns)
文摘Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of suprathermal hot electrons under interaction conditions envisaged for direct-drive schemes for inertial confinement fusion.Nonetheless,SSRS remains to date one of the least understood parametric instabilities.Here,we report the first angularly and spectrally resolved measurements of scattered light at laser intensities relevant for the shock ignition scheme(I×10^(16)W/cm^(2)),showing significant SSRS growth in the direction perpendicular to the laser polarization.Modification of the focal spot shape and orientation,obtained by using two different random phase plates,and of the density gradient of the plasma,by utilizing exploding foil targets of different thicknesses,clearly reveals a different dependence of backward SRS(BSRS)and SSRS on experimental parameters.While convective BSRS scales with plasma density scale length,as expected by linear theory,the growth of SSRS depends on the spot extension in the direction perpendicular to laser polarization.Our analysis therefore demonstrates that under current experimental conditions,with density scale lengths L_(n)≈60–120μm and spot sizes FWHM≈40–100μm,SSRS is limited by laser beam size rather than by the density scale length of the plasma.
基金The study was supported financially by the Russian Foundation for Basic Research(Grant No.20-02-00790)the Joint Institute for High Temperatures of the Russian Academy of Sciences(Topic Grant No.01201357846)The UK team received financial support from the Engineering and Physical Sciences Research Council(Grant Nos.EP/L01663X/1 and EP/H012605/1).
文摘X-ray absorption spectroscopy is a well-accepted diagnostic for experimental studies of warm dense matter.It requires a short-lived X-ray source of sufficiently high emissivity and without characteristic lines in the spectral range of interest.In the present work,we discuss how to choose an optimum material and thickness to get a bright source in the wavelength range 2A–6A(∼2 keV to 6 keV)by considering relatively low-Z elements.We demonstrate that the highest emissivity of solid aluminum and silicon foil targets irradiated with a 1-ps high-contrast sub-kJ laser pulse is achieved when the target thickness is close to 10μm.An outer plastic layer can increase the emissivity even further.
基金funding from the European Union’s Horizon 2020 research and innovation programme through the European IMPULSE project under grant agreement No.871161 and LASERLAB-EUROPE V under grant agreement No.871124from grant PDC2021-120933-I00 funded by MCIN/AEI/10.13039/501100011033 and by the European Union Next Generation EU/PRTR+4 种基金from grant PID2021-125389OA-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER,UE and by‘ERDF A way of making Europe’by the European Union and in addition to Unidad de Investigacion Consolidada de la Junta de Castilla y Leon No.CLP087U16The UPM47 campaign was funded through IOSIN,Nucleu PN-IFIN-HH 23-26 Code PN 2321the ELI-NP Phase II,a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund and the Competitiveness Operational Programme(1/07.07.2016,COP,ID 1334)This research was funded,in part,by the French Agence Nationale de la Recherche(ANR),Project No.ANR-22-CE30-0044supported by the Ministry of Youth and Sports of the Czech Republic(Project Nos.LM2023068 and LM2018114(PALS RI)).
文摘We present a novel scheme for rapid quantitative analysis of debris generated during experiments with solid targets following relativistic laser–plasma interaction at high-power laser facilities.Results are supported by standard analysis techniques.Experimental data indicate that predictions by available modelling for non-mass-limited targets are reasonable,with debris of the order of hundreds ofμg per shot.We detect for the first time two clearly distinct types of debris emitted from the same interaction.A fraction of the debris is ejected directionally,following the target normal(rear and interaction side).The directional debris ejection towards the interaction side is larger than on the side of the target rear.The second type of debris is characterized by a more spherically uniform ejection,albeit with a small asymmetry that favours ejection towards the target rear side.
