A 100 kJ-level laser facility has been designed to study inertial confinement fusion physics in China.This facility incorporates various diagnostic techniques,including optical,x-ray imaging,x-ray spectrum,and fusion ...A 100 kJ-level laser facility has been designed to study inertial confinement fusion physics in China.This facility incorporates various diagnostic techniques,including optical,x-ray imaging,x-ray spectrum,and fusion product diagnostics,as well as general diagnostics assistance systems and central control and data acquisition systems.This paper describes recent developments in diagnostics at the facility.展开更多
Wereport experimental research on laser plasma interaction(LPI)conducted in Shenguang laser facilities during the past ten years.The research generally consists of three phases:(1)developing platforms for LPI research...Wereport experimental research on laser plasma interaction(LPI)conducted in Shenguang laser facilities during the past ten years.The research generally consists of three phases:(1)developing platforms for LPI research in mm-scale plasma with limited drive energy,where both gasbag and gas-filled hohlraum targets are tested;(2)studying the effects of beam-smoothing techniques,such as continuous phase plate and polarization smoothing,on the suppression of LPI;and(3)exploring the factors affecting LPI in integrated implosion experiments,which include the laser intensity,gas-fill pressure,size of the laser-entrance hole,and interplay between different beam cones.Results obtained in each phase will be presented and discussed in detail.展开更多
We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on t...We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on thepoint-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peakcompression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metalmicrowire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamicsimulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, arealdensities of the targets were evaluated.展开更多
The results of a commissioning experiment on the SILEX-Ⅱlaser facility(formerly known as CAEP-PW)are reported.SILEX-Ⅱis a complete optical parametric chirped-pulse amplification laser facility.The peak power reached...The results of a commissioning experiment on the SILEX-Ⅱlaser facility(formerly known as CAEP-PW)are reported.SILEX-Ⅱis a complete optical parametric chirped-pulse amplification laser facility.The peak power reached about 1 PWin a 30 fs pulse duration during the experiment.The laser contrast was better than 1010 at 20 ps ahead of the main pulse.In the basic laser foil target interaction,a set of experimental data were collected,including spatially resolved x-ray emission,the image of the coherent transition radiation,the harmonic spectra in the direction of reflection,the energy spectra and beam profile of accelerated protons,hot-electron spectra,and transmitted laser energy fraction and spatial distribution.The experimental results show that the laser intensity reached 531020 W/cm^(2) within a 5.8μm focus(FWHM).Significant laser transmission did not occur when the thickness of theCHfoil was equal to or greater than 50 nm.The maximum energy of the accelerated protons in the target normal direction was roughly unchanged when the target thickness varied between 50 nm and 15μm.The maximum proton energy via the target normal sheath field acceleration mechanism was about 21 MeV.We expect the on-target laser intensity to reach 10^(22) W/cm^(2) in the near future,after optimization of the laser focus and upgrade of the laser power to 3 PW.展开更多
Optical Thomson scattering(OTS)diagnostics have been continuously developed on a series of large laser facilities for inertial confinement fusion(ICF)research in China.We review recent progress in the use of OTS diagn...Optical Thomson scattering(OTS)diagnostics have been continuously developed on a series of large laser facilities for inertial confinement fusion(ICF)research in China.We review recent progress in the use of OTS diagnostics to study the internal plasma conditions of ICF gas-filled hohlraums.We establish the predictive capability for experiments by calculating the time-resolved Thomson scattering spectra based on the 2D radiation-hydrodynamic code LARED,and we explore the fitting method for the measured spectra.A typical experiment with a simplified cylindrical hohlraum is conducted on a 10 kJ-level laser facility,and the plasma evolution around the laser entrance hole is analyzed.The dynamic effects of the blast wave from the covering membrane and the convergence of shocks on the hohlraum axis are observed,and the experimental results agree well with those of simulations.Another typical experiment with an octahedral spherical hohlraum is conducted on a 100 kJ-level laser facility,and the plasma evolution at the hohlraum center is analyzed.A discrepancy appears between experiment and simulation as the electron temperature rises,indicating the occurrence of nonlocal thermal conduction.展开更多
Recently generation of strong magnetic(B)fields has been demonstrated in capacitor coils heated by high power laser pulses[S.Fujioka et al.,Sci.Rep.3,1170(2013)].This paper will present a direct measurement of B field...Recently generation of strong magnetic(B)fields has been demonstrated in capacitor coils heated by high power laser pulses[S.Fujioka et al.,Sci.Rep.3,1170(2013)].This paper will present a direct measurement of B field generated with an open-ended coil target driven by a nanosecond laser pulse using ultrafast proton radiography.The radiographs are analyzed with particle-tracing simulations.The B field at the coil center is inferred to be ~50 T at an irradiance of ~5×10^(14) W·cm^(-2).The B field generation is attributed to the background cold electron flow pointing to the laser focal spot,where a target potential is induced due to the escape of energetic electrons.展开更多
The first laser–plasma interaction experiment using lasers of eight beams grouped into one octad has been conducted on the Shenguang Octopus facility.Although each beam intensity is below its individual threshold for...The first laser–plasma interaction experiment using lasers of eight beams grouped into one octad has been conducted on the Shenguang Octopus facility.Although each beam intensity is below its individual threshold for stimulated Brillouin backscattering(SBS),collective behaviors are excited to enhance the octad SBS.In particular,when two-color/cone lasers with wavelength separation 0.3 nm are used,the backward SBS reflectivities show novel behavior in which beams of longer wavelength achieve higher SBS gain.This property of SBS can be attributed to the rotation of the wave vectors of common ion acoustic waves due to the competition of detunings between geometrical angle and wavelength separation.This mechanism is confirmed using massively parallel supercomputer simulations with the three-dimensional laser–plasma interaction code LAP3D.展开更多
基金This work was performed under the auspices of the National Key R&D Program of China,No.2017YFA0403300National Natural Science Foundation of China under Contract Nos.11805184,11805178,11805185+2 种基金Presidential Foundation of China Academy of Engineering Physics,No.YZJJLX2019011Science Challenging Project,No.TZ2016001Laser Fusion Research Center Funds for Young Talents,No.RCFPD4-2020-1.
文摘A 100 kJ-level laser facility has been designed to study inertial confinement fusion physics in China.This facility incorporates various diagnostic techniques,including optical,x-ray imaging,x-ray spectrum,and fusion product diagnostics,as well as general diagnostics assistance systems and central control and data acquisition systems.This paper describes recent developments in diagnostics at the facility.
基金This work was supported by the Science Challenge Project(Grant No.TZ2016005)the Natural Science Foundation of China(Grant Nos.11435011,11875093,and 11875241)the CAEP Foundation(Grant No.PY2019108).
文摘Wereport experimental research on laser plasma interaction(LPI)conducted in Shenguang laser facilities during the past ten years.The research generally consists of three phases:(1)developing platforms for LPI research in mm-scale plasma with limited drive energy,where both gasbag and gas-filled hohlraum targets are tested;(2)studying the effects of beam-smoothing techniques,such as continuous phase plate and polarization smoothing,on the suppression of LPI;and(3)exploring the factors affecting LPI in integrated implosion experiments,which include the laser intensity,gas-fill pressure,size of the laser-entrance hole,and interplay between different beam cones.Results obtained in each phase will be presented and discussed in detail.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1603300 and 2022YFA1603200)the Science Challenge Project(Grant No.TZ2018005)in China+1 种基金the National Natural Science Foundation of China(Grant Nos.11805188 and 12175209)the Laser Fusion Research Center Funds for Young Talents(Grant No.RCFPD6-2022-1).
文摘We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on thepoint-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peakcompression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metalmicrowire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamicsimulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, arealdensities of the targets were evaluated.
基金This work was supported by the National Key Program for S&T Research and Development(Grant No.2018YFA0404804)the Science Challenge Project(Grant No.TZ2016005)the National Natural Science Foundation of China(Grant No.11805181).
文摘The results of a commissioning experiment on the SILEX-Ⅱlaser facility(formerly known as CAEP-PW)are reported.SILEX-Ⅱis a complete optical parametric chirped-pulse amplification laser facility.The peak power reached about 1 PWin a 30 fs pulse duration during the experiment.The laser contrast was better than 1010 at 20 ps ahead of the main pulse.In the basic laser foil target interaction,a set of experimental data were collected,including spatially resolved x-ray emission,the image of the coherent transition radiation,the harmonic spectra in the direction of reflection,the energy spectra and beam profile of accelerated protons,hot-electron spectra,and transmitted laser energy fraction and spatial distribution.The experimental results show that the laser intensity reached 531020 W/cm^(2) within a 5.8μm focus(FWHM).Significant laser transmission did not occur when the thickness of theCHfoil was equal to or greater than 50 nm.The maximum energy of the accelerated protons in the target normal direction was roughly unchanged when the target thickness varied between 50 nm and 15μm.The maximum proton energy via the target normal sheath field acceleration mechanism was about 21 MeV.We expect the on-target laser intensity to reach 10^(22) W/cm^(2) in the near future,after optimization of the laser focus and upgrade of the laser power to 3 PW.
基金This work is supported by the National Key R&D Program of China(Grant No.2017YFA0403300)the Science Challenge Project(No.TZ2016005)the Natural Science Foundation of China(Grant Nos.11435011,11505168,and 11705180).
文摘Optical Thomson scattering(OTS)diagnostics have been continuously developed on a series of large laser facilities for inertial confinement fusion(ICF)research in China.We review recent progress in the use of OTS diagnostics to study the internal plasma conditions of ICF gas-filled hohlraums.We establish the predictive capability for experiments by calculating the time-resolved Thomson scattering spectra based on the 2D radiation-hydrodynamic code LARED,and we explore the fitting method for the measured spectra.A typical experiment with a simplified cylindrical hohlraum is conducted on a 10 kJ-level laser facility,and the plasma evolution around the laser entrance hole is analyzed.The dynamic effects of the blast wave from the covering membrane and the convergence of shocks on the hohlraum axis are observed,and the experimental results agree well with those of simulations.Another typical experiment with an octahedral spherical hohlraum is conducted on a 100 kJ-level laser facility,and the plasma evolution at the hohlraum center is analyzed.A discrepancy appears between experiment and simulation as the electron temperature rises,indicating the occurrence of nonlocal thermal conduction.
基金supported by the National Basic Research Program of China(Grant No.2013CBA01501)the National Nature Science Foundation of China(Grant Nos.11135012,11520101003 and 11375262)the National High Technology Research and Development Program of China.
文摘Recently generation of strong magnetic(B)fields has been demonstrated in capacitor coils heated by high power laser pulses[S.Fujioka et al.,Sci.Rep.3,1170(2013)].This paper will present a direct measurement of B field generated with an open-ended coil target driven by a nanosecond laser pulse using ultrafast proton radiography.The radiographs are analyzed with particle-tracing simulations.The B field at the coil center is inferred to be ~50 T at an irradiance of ~5×10^(14) W·cm^(-2).The B field generation is attributed to the background cold electron flow pointing to the laser focal spot,where a target potential is induced due to the escape of energetic electrons.
基金supported by the Natural Science Foundation of China(Grant Nos.11975059,12005021,and 11875241).
文摘The first laser–plasma interaction experiment using lasers of eight beams grouped into one octad has been conducted on the Shenguang Octopus facility.Although each beam intensity is below its individual threshold for stimulated Brillouin backscattering(SBS),collective behaviors are excited to enhance the octad SBS.In particular,when two-color/cone lasers with wavelength separation 0.3 nm are used,the backward SBS reflectivities show novel behavior in which beams of longer wavelength achieve higher SBS gain.This property of SBS can be attributed to the rotation of the wave vectors of common ion acoustic waves due to the competition of detunings between geometrical angle and wavelength separation.This mechanism is confirmed using massively parallel supercomputer simulations with the three-dimensional laser–plasma interaction code LAP3D.
