The impact of fuel-ion diffusion in inertial confinement fusion implosions is assessed using nuclear reaction yield ratios and reaction histories.In T3He-gas-filled(with trace D)shock-driven implosions,the observed TT...The impact of fuel-ion diffusion in inertial confinement fusion implosions is assessed using nuclear reaction yield ratios and reaction histories.In T3He-gas-filled(with trace D)shock-driven implosions,the observed TT/T3He yield ratio is∼23lower than expected from temperature scaling.InD3He-gas-filled(with trace T)shock-driven implosions,the timing of theD3He reaction history is∼50 ps earlier than those of the DT reaction histories,and average-ion hydrodynamic simulations cannot reconcile this timing difference.Both experimental observations are consistent with reduced T ions in the burn region as predicted by multi-ion diffusion theory and particle-in-cell simulations.展开更多
Electrogenerated N-heterocyclic carbene (NHC), obtained by cathodic reduction of Bmim-BF4, behaves as organocatalyst and base in the Staudinger synthesis from an acyl chloride and a deactivated imine in ionic liquid t...Electrogenerated N-heterocyclic carbene (NHC), obtained by cathodic reduction of Bmim-BF4, behaves as organocatalyst and base in the Staudinger synthesis from an acyl chloride and a deactivated imine in ionic liquid to yield ?-lactams. The effect of many parameters (temperature, amount of electricity, substituents, presence of an external base) has been evaluated and a tentative mechanism for the Staudinger synthesis in a very polar medium like the ionic liquid reported. The yields of isolated ?-lactams are good, starting from non-electrophilic imines, and predominantly trans lactams are obtained with a good diastereomeric ratio.展开更多
Catalytic pyrolysis of thermoplastics extracted from waste electrical and electronic equipment （WEEE） was investigated using various fly ash-derived catalysts. The catalysts were prepared from fly ash by a simple me...Catalytic pyrolysis of thermoplastics extracted from waste electrical and electronic equipment （WEEE） was investigated using various fly ash-derived catalysts. The catalysts were prepared from fly ash by a simple method that basically includes a mechanical treatment followed by an acid or a basic activation. The synthesized catalysts were characterized using various analytical techniques. The results showed that not treated fly ash （FA） is characterized by good crystallinity, which in turn is lowered by mechanical and chemical treatment （fly ash after mechanical and acid activation, FAMA） and suppressed almost entirely down to let fly ash become completely amorphous （fly ash al^er mechanical and basic activation FAMB）. Simultaneously, the surface area resulted increased. Subsequently, FA, FAMB and FAMA were used in the pyrolysis of a WEEE plastic sample at 400~C and their performance were compared with thermal pyrolysis at the same temperature. The catalysts principally improve the light oil yield： from 59 wt.% with thermal pyrolysis to 83 wt.% using FAMB. The formation of styrene in the oil is also increased： from 243 mg/g with thermal pyrolysis to 453 mg/g using FAMB. As a result, FAMB proved to be the best catalyst, thus producing also the lowest and the highest amount of char and gas, respectively.展开更多
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...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.展开更多
Fusion energy research is delivering impressive new results emerging from different infrastructures and industrial devices evolving rapidly from ideas to proof-of-principle demonstration and aiming at the conceptual d...Fusion energy research is delivering impressive new results emerging from different infrastructures and industrial devices evolving rapidly from ideas to proof-of-principle demonstration and aiming at the conceptual design of reactors for the production of electricity.A major milestone has recently been announced in laser fusion by the Lawrence Livermore National Laboratory and is giving new thrust to laser-fusion energy research worldwide.Here we discuss how these circumstances strongly suggest the need for a European intermediate-energy facility dedicated to the physics and technology of laser-fusion ignition,the physics of fusion materials and advanced technologies for high-repetitionrate,high-average-power broadband lasers.We believe that the participation of the broader scientific community and the increased engagement of industry,in partnership with research and academic institutions,make most timely the construction of this infrastructure of extreme scientific attractiveness.展开更多
A synthetic mixture of real waste packaging plastics representative of the residue from a material recovery facility(plasmix)was submitted to thermal and catalytic pyrolysis.Preliminary thermogravimetry experiments co...A synthetic mixture of real waste packaging plastics representative of the residue from a material recovery facility(plasmix)was submitted to thermal and catalytic pyrolysis.Preliminary thermogravimetry experiments coupled with Fourier transform infrared spectroscopy were performed to evaluate the effects of the catalysts on the polymers’degradation temperatures and to determine the main compounds produced during pyrolysis.The thermal and catalytic experiments were conducted at 370℃,450℃ and 650℃ using a bench scale reactor.The oil,gas,and char yields were analyzed and the compositions of the reaction products were compared.The primary aim of this study was to understand the effects of zeolitic hydrogen ultra stable zeolite Y(HUSY)and hydrogen zeolite socony mobil-5(HZSM5)catalysts with high silica content on the pyrolysis process and the products’quality.Thermogravimetry showed that HUSY significantly reduces the degradation temperature of all the polymers—particularly the polyolefines.HZSM5 had a significant effect on the degradation of polyethylene due to its smaller pore size.Mass balance showed that oil is always the main product of pyrolysis,regardless of the process conditions.However,all pyrolysis runs performed at 370℃ were incomplete.The use of either zeolites resulted in a decrease in the heavy oil fraction and the prevention of wax formation.HUSY has the best performance in terms of the total monoaromatic yield(29 wt-%at 450℃),while HZSM5 promoted the production of gases(41 wt-%at 650℃).Plasmix is a potential input material for pyrolysis that is positively affected by the presence of the two tested zeolites.A more effective separation of polyethylene terephthalate during the selection process could lead to higher quality pyrolysis products.展开更多
In this paper we consider the Dirichlet problem■where p is a small parameter andΩis a C^(2)bounded domain in R^(2).In[1],the author proves the existence of a m-point blow-up solution u_(p)jointly with its asymptotic...In this paper we consider the Dirichlet problem■where p is a small parameter andΩis a C^(2)bounded domain in R^(2).In[1],the author proves the existence of a m-point blow-up solution u_(p)jointly with its asymptotic behaviour.We compute the Morse index of up in terms of the Morse index of the associated Hamilton function of this problem.In addition,we give an asymptotic estimate for the first 4m eigenvalues and eigenfunctions.展开更多
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 s...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.展开更多
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 o...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.展开更多
Two-color plasma,induced by two lasers of different colors,can radiate ultra-broadband and intense terahertz(THz)pulses,which is desirable in many technological and scientific applications.It was found that the polari...Two-color plasma,induced by two lasers of different colors,can radiate ultra-broadband and intense terahertz(THz)pulses,which is desirable in many technological and scientific applications.It was found that the polarization of the emitted THz depends on the phase difference between the fundamental laser wave and its second harmonic.Recent investigation suggests that chirp-induced change of pulse overlap plays an important role in the THz yield from two-color plasma.However,the effect of laser chirp on THz polarization remains unexplored.Hereby,we investigate the impact of laser chirp on THz polarization.It is unveiled that the chirp-induced phase difference affects THz polarization.Besides,positive and negative chirps have opposite effects on the variation of the THz polarization versus the phase difference.The polarization of THz generated by a positively chirped pump laser rotates clockwise with an increasing phase difference,while it rotates anticlockwise when generated by a negatively chirped pump laser.展开更多
基金This material is based upon work supported by the Department of Energy,National Nuclear Security Administration under Award Nos.DE-NA0001857,DE-NA0002949,and DENA0002905.The work was also supported in part by NLUF(DE-NA0002035).H.S.was supported by a DOE NNSA SSGF Fellowship(DE-FC52-08NA28752)during this work.S.A.acknowledges Sapienza Project 2016 No.RM11615502006B04,as well as EUROfusion Project Nos.AWP17-ENR-IFE-CEA-01 and ENR-IFE19.CEA-01.A.L.acknowledges the LANL LDRD program.
文摘The impact of fuel-ion diffusion in inertial confinement fusion implosions is assessed using nuclear reaction yield ratios and reaction histories.In T3He-gas-filled(with trace D)shock-driven implosions,the observed TT/T3He yield ratio is∼23lower than expected from temperature scaling.InD3He-gas-filled(with trace T)shock-driven implosions,the timing of theD3He reaction history is∼50 ps earlier than those of the DT reaction histories,and average-ion hydrodynamic simulations cannot reconcile this timing difference.Both experimental observations are consistent with reduced T ions in the burn region as predicted by multi-ion diffusion theory and particle-in-cell simulations.
文摘Electrogenerated N-heterocyclic carbene (NHC), obtained by cathodic reduction of Bmim-BF4, behaves as organocatalyst and base in the Staudinger synthesis from an acyl chloride and a deactivated imine in ionic liquid to yield ?-lactams. The effect of many parameters (temperature, amount of electricity, substituents, presence of an external base) has been evaluated and a tentative mechanism for the Staudinger synthesis in a very polar medium like the ionic liquid reported. The yields of isolated ?-lactams are good, starting from non-electrophilic imines, and predominantly trans lactams are obtained with a good diastereomeric ratio.
文摘Catalytic pyrolysis of thermoplastics extracted from waste electrical and electronic equipment （WEEE） was investigated using various fly ash-derived catalysts. The catalysts were prepared from fly ash by a simple method that basically includes a mechanical treatment followed by an acid or a basic activation. The synthesized catalysts were characterized using various analytical techniques. The results showed that not treated fly ash （FA） is characterized by good crystallinity, which in turn is lowered by mechanical and chemical treatment （fly ash after mechanical and acid activation, FAMA） and suppressed almost entirely down to let fly ash become completely amorphous （fly ash al^er mechanical and basic activation FAMB）. Simultaneously, the surface area resulted increased. Subsequently, FA, FAMB and FAMA were used in the pyrolysis of a WEEE plastic sample at 400~C and their performance were compared with thermal pyrolysis at the same temperature. The catalysts principally improve the light oil yield： from 59 wt.% with thermal pyrolysis to 83 wt.% using FAMB. The formation of styrene in the oil is also increased： from 243 mg/g with thermal pyrolysis to 453 mg/g using FAMB. As a result, FAMB proved to be the best catalyst, thus producing also the lowest and the highest amount of char and gas, respectively.
基金This work was carried out within the framework of the EUROfusion Consortium,funded by the European Union via the Euratom Research and Training Programme(Grant Agreement No.101052200–EUROfusion)The views and opinions expressed are however those of the author(s)only and do not necessarily reflect those of the European Union or the European Commission.Neither the European Union nor the European Commission can be held responsible for them.The involved teams have operated within the framework of the Enabling Research Project:ENR-IFE.01.CEA‘Advancing shock ignition for direct-drive inertial fusion’This work was also done with the support and under the auspices of the NIFS Collaboration Research program(2021NIFS18KUGK123).
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.
文摘Fusion energy research is delivering impressive new results emerging from different infrastructures and industrial devices evolving rapidly from ideas to proof-of-principle demonstration and aiming at the conceptual design of reactors for the production of electricity.A major milestone has recently been announced in laser fusion by the Lawrence Livermore National Laboratory and is giving new thrust to laser-fusion energy research worldwide.Here we discuss how these circumstances strongly suggest the need for a European intermediate-energy facility dedicated to the physics and technology of laser-fusion ignition,the physics of fusion materials and advanced technologies for high-repetitionrate,high-average-power broadband lasers.We believe that the participation of the broader scientific community and the increased engagement of industry,in partnership with research and academic institutions,make most timely the construction of this infrastructure of extreme scientific attractiveness.
文摘A synthetic mixture of real waste packaging plastics representative of the residue from a material recovery facility(plasmix)was submitted to thermal and catalytic pyrolysis.Preliminary thermogravimetry experiments coupled with Fourier transform infrared spectroscopy were performed to evaluate the effects of the catalysts on the polymers’degradation temperatures and to determine the main compounds produced during pyrolysis.The thermal and catalytic experiments were conducted at 370℃,450℃ and 650℃ using a bench scale reactor.The oil,gas,and char yields were analyzed and the compositions of the reaction products were compared.The primary aim of this study was to understand the effects of zeolitic hydrogen ultra stable zeolite Y(HUSY)and hydrogen zeolite socony mobil-5(HZSM5)catalysts with high silica content on the pyrolysis process and the products’quality.Thermogravimetry showed that HUSY significantly reduces the degradation temperature of all the polymers—particularly the polyolefines.HZSM5 had a significant effect on the degradation of polyethylene due to its smaller pore size.Mass balance showed that oil is always the main product of pyrolysis,regardless of the process conditions.However,all pyrolysis runs performed at 370℃ were incomplete.The use of either zeolites resulted in a decrease in the heavy oil fraction and the prevention of wax formation.HUSY has the best performance in terms of the total monoaromatic yield(29 wt-%at 450℃),while HZSM5 promoted the production of gases(41 wt-%at 650℃).Plasmix is a potential input material for pyrolysis that is positively affected by the presence of the two tested zeolites.A more effective separation of polyethylene terephthalate during the selection process could lead to higher quality pyrolysis products.
文摘In this paper we consider the Dirichlet problem■where p is a small parameter andΩis a C^(2)bounded domain in R^(2).In[1],the author proves the existence of a m-point blow-up solution u_(p)jointly with its asymptotic behaviour.We compute the Morse index of up in terms of the Morse index of the associated Hamilton function of this problem.In addition,we give an asymptotic estimate for the first 4m eigenvalues and eigenfunctions.
基金financial support from the LASERLAB-EUROPE Access to Research Infrastructure activity within the EC’s seventh Framework Program(Application No.18110033)carried out within the framework of the EUROfusion Enabling research projects AWP19-20-ENR-IFE19.CEA01 and AWP21-ENR-01-CEA-02+2 种基金funding from the Euratom research and training programme 20192020 and 2021-2025 under grant No.633053financial support from the CNR-funded Italian research Network ELI-Italy(D.M.No.63108.08.2016)the Czech Ministry of Education,Youth and Sports,project LTT17015。
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.
基金financial support from the LASERLAB-EUROPE Access to Research Infrastructure activity within the ECs seventh Framework Programfunding from the Euratom research and training programme 2014–2018 under grant agreement No. 633053+4 种基金partially supported by the project ELITAS (ELI Tools for Advanced Simulation) CZ.02.1.01/0.0/0.0/16 013/0001793HIFI (High Field Initiative, CZ.02.1.01/0.0/0.0/15 003/0000449)ADONIS (Advanced research using high-intensity laser produced photons and particles, CZ.02.1.01/0.0/0.0/16 019/0000789)ELITAS (ELI Tools for Advanced Simulations,CZ.02.1.01/0.0/0.0/16 013/0001793)financial support from the Czech Ministry of Education, Youth and Sports within grants LTT17015, LM2015083, and CZ.02.1.01/0.0/0.0/16 013/0001552 (EF16 013/0001552)
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.
基金Instituto Nazionale di Fisica Nucleare(TERA INFN)and Sapienza University-Call for large research&infrastructure project。
文摘Two-color plasma,induced by two lasers of different colors,can radiate ultra-broadband and intense terahertz(THz)pulses,which is desirable in many technological and scientific applications.It was found that the polarization of the emitted THz depends on the phase difference between the fundamental laser wave and its second harmonic.Recent investigation suggests that chirp-induced change of pulse overlap plays an important role in the THz yield from two-color plasma.However,the effect of laser chirp on THz polarization remains unexplored.Hereby,we investigate the impact of laser chirp on THz polarization.It is unveiled that the chirp-induced phase difference affects THz polarization.Besides,positive and negative chirps have opposite effects on the variation of the THz polarization versus the phase difference.The polarization of THz generated by a positively chirped pump laser rotates clockwise with an increasing phase difference,while it rotates anticlockwise when generated by a negatively chirped pump laser.
