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
Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential a...Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential applications:as an alternative to deuterium-tritium for fusion energy production,astrophysics studies,and alpha-particle generation for medical treatment.One possible scheme for laser-driven p-^(11)B reactions is to direct a beam of laser-accelerated protons onto a boron(B)sample(the so-called“pitcher-catcher”scheme).This technique has been successfully implemented on large high-energy lasers,yielding hundreds of joules per shot at low repetition.We present here a complementary approach,exploiting the high repetition rate of the VEGA III petawatt laser at CLPU(Spain),aiming at accumulating results from many interactions at much lower energy,to provide better control of the parameters and the statistics of the measurements.Despite a moderate energy per pulse,our experiment allowed exploration of the laser-driven fusion process with tens(up to hundreds)of laser shots.The experiment provided a clear signature of the reactions involved and of the fusion products,accumulated over many shots,leading to an improved optimization of the diagnostics for experimental campaigns of this type.In this paper,we discuss the effectiveness of laser-driven p-11B fusion in the pitcher-catcher scheme,at a high repetition rate,addressing the challenges of this experimental scheme and highlighting its critical aspects.Our proposed methodology allows evaluation of the performance of this scheme for laser-driven alpha particle production and can be adapted to high-repetition-rate laser facilities with higher energy and intensity.展开更多
The interaction of high-power laser pulses with undercritical foams produced by different techniques but with the same average density is studied at the PALS laser facility.The spatial-temporal evolution of X-ray emis...The interaction of high-power laser pulses with undercritical foams produced by different techniques but with the same average density is studied at the PALS laser facility.The spatial-temporal evolution of X-ray emission is observed using an X-ray streak camera,electron and ion temperatures are measured by X-ray spectroscopy,and hot-electron production is characterized by monochromatic X-ray imaging.Transmission of a femtosecond laser probe pulse through foams is observed in the near and far fields.In spite of large differences in pore size and foam structure,the velocity of ionization front propagation is quite similar for all the foams studied and is slower than that in a homogeneous material of the same average density.The ion temperature in the plasma behind the ionization front is a few times higher than the electron temperature.Hot-electron production in plastic foams with small pores is strongly suppressed compared with that in solid targets,whereas in foams produced by additive manufacturing,it is significantly increased to the level observed in bare copper foil targets.展开更多
The discovery of chirped pulse amplification has led to great improvements in laser technology,enabling energetic laser beams to be compressed to pulse durations of tens of femtoseconds and focused to a few micrometer...The discovery of chirped pulse amplification has led to great improvements in laser technology,enabling energetic laser beams to be compressed to pulse durations of tens of femtoseconds and focused to a few micrometers.Protons with energies of tens of MeV can be accelerated using,for instance,target normal sheath acceleration and focused on secondary targets.Under such conditions,nuclear reactions can occur,with the production of radioisotopes suitable for medical application.The use of high-repetition lasers to produce such isotopes is competitive with conventional methods mostly based on accelerators.In this paper,we study the production of^(67)Cu,^(63)Zn,^(18)F,and^(11)C,which are currently used in positron emission tomography and other applications.At the same time,we study the reactions^(10)B(p,α)^(7)Be and^(70)Zn(p,4n)^(67)Ga to put further constraints on the proton distributions at different angles,as well as the reaction^(11)B(p,α)^(8)Be relevant for energy production.The experiment was performed at the 1 PW laser facility at VegaⅢin Salamanca,Spain.Angular distributions of radioisotopes in the forward(with respect to the laser direction)and backward directions were measured using a high purity germanium detector.Our results are in reasonable agreement with numerical estimates obtained following the approach of Kimura and Bonasera[Nucl.Instrum.Methods Phys.Res.,Sect.A 637,164–170(2011)].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funded by the European Union via the Euratom Research and Training Program(Grant Agreement No.101052200-EUROfusion)funding from LASERLAB-EUROPE(Grant Agreement No.871124,European Union’s Horizon 2020 Research and Innovation Program)+5 种基金supported in part by the United States Department of Energy under Grant No.DE-FG02-93ER40773We also acknowledge support from Grant No.PID2021-125389OA-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER,UEby“ERDF A Way of Making Europe”by the European Union and Unidad de Investigación Consolidada of Junta de Castilla y León UIC 167supported in part by the National Natural Science Foundation of China under Grant No.12375125the Fundamental Research Funds for the Central Universitiesthe support of the Czech Science Foundation through Grant No.GACR24-11398S.
文摘Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential applications:as an alternative to deuterium-tritium for fusion energy production,astrophysics studies,and alpha-particle generation for medical treatment.One possible scheme for laser-driven p-^(11)B reactions is to direct a beam of laser-accelerated protons onto a boron(B)sample(the so-called“pitcher-catcher”scheme).This technique has been successfully implemented on large high-energy lasers,yielding hundreds of joules per shot at low repetition.We present here a complementary approach,exploiting the high repetition rate of the VEGA III petawatt laser at CLPU(Spain),aiming at accumulating results from many interactions at much lower energy,to provide better control of the parameters and the statistics of the measurements.Despite a moderate energy per pulse,our experiment allowed exploration of the laser-driven fusion process with tens(up to hundreds)of laser shots.The experiment provided a clear signature of the reactions involved and of the fusion products,accumulated over many shots,leading to an improved optimization of the diagnostics for experimental campaigns of this type.In this paper,we discuss the effectiveness of laser-driven p-11B fusion in the pitcher-catcher scheme,at a high repetition rate,addressing the challenges of this experimental scheme and highlighting its critical aspects.Our proposed methodology allows evaluation of the performance of this scheme for laser-driven alpha particle production and can be adapted to high-repetition-rate laser facilities with higher energy and intensity.
基金supported by the Center of Advanced Applied Sciences(CAAS)Project No.(CZ.02.1.01/0.0/0.0/16019/0000778)from the European Regional Development Fundalso supported in part by the Czech Technical University in Prague Project No.SGS22/184/OHK4/3T/14+1 种基金partial funding via EUROfusion Enabling Research Project No.AWP24-ENR-03-CEA-02“Foams as a pathway to energy from high gain direct drive ignition,”within the framework of the EUROfusion Consortium,funded by the European Union via the Euratom Research and Training Program(Grant Agreement No.101052200-EUROfusion)the Czech Ministry of Education,Youth and Sports(CMEYS)for funding the operation of the PALS facility(Grant No.LM2023068)。
文摘The interaction of high-power laser pulses with undercritical foams produced by different techniques but with the same average density is studied at the PALS laser facility.The spatial-temporal evolution of X-ray emission is observed using an X-ray streak camera,electron and ion temperatures are measured by X-ray spectroscopy,and hot-electron production is characterized by monochromatic X-ray imaging.Transmission of a femtosecond laser probe pulse through foams is observed in the near and far fields.In spite of large differences in pore size and foam structure,the velocity of ionization front propagation is quite similar for all the foams studied and is slower than that in a homogeneous material of the same average density.The ion temperature in the plasma behind the ionization front is a few times higher than the electron temperature.Hot-electron production in plastic foams with small pores is strongly suppressed compared with that in solid targets,whereas in foams produced by additive manufacturing,it is significantly increased to the level observed in bare copper foil targets.
文摘The discovery of chirped pulse amplification has led to great improvements in laser technology,enabling energetic laser beams to be compressed to pulse durations of tens of femtoseconds and focused to a few micrometers.Protons with energies of tens of MeV can be accelerated using,for instance,target normal sheath acceleration and focused on secondary targets.Under such conditions,nuclear reactions can occur,with the production of radioisotopes suitable for medical application.The use of high-repetition lasers to produce such isotopes is competitive with conventional methods mostly based on accelerators.In this paper,we study the production of^(67)Cu,^(63)Zn,^(18)F,and^(11)C,which are currently used in positron emission tomography and other applications.At the same time,we study the reactions^(10)B(p,α)^(7)Be and^(70)Zn(p,4n)^(67)Ga to put further constraints on the proton distributions at different angles,as well as the reaction^(11)B(p,α)^(8)Be relevant for energy production.The experiment was performed at the 1 PW laser facility at VegaⅢin Salamanca,Spain.Angular distributions of radioisotopes in the forward(with respect to the laser direction)and backward directions were measured using a high purity germanium detector.Our results are in reasonable agreement with numerical estimates obtained following the approach of Kimura and Bonasera[Nucl.Instrum.Methods Phys.Res.,Sect.A 637,164–170(2011)].
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.
