Implosion asymmetry is a crucial problem quenching ignition in the field of inertial confinement fusion.A forward-calculation method based on 1D and 2D hydrodynamic simulations has been developed to generate and study...Implosion asymmetry is a crucial problem quenching ignition in the field of inertial confinement fusion.A forward-calculation method based on 1D and 2D hydrodynamic simulations has been developed to generate and study the x-ray images of hot-spot self-emission,indicating asymmetry integrated over the entire drive pulse.It is shown that the x-ray imaging photon energy should be higher to avoid the influence of the remaining shell.The contour level(percentage of the maximum emission intensity)and spatial resolution should be as low as possible,optimally less than 20%and 3μm,for characterization of higher-mode signatures such as Ps-P12 by x-ray self-emission images.On the contrary,signatures of lower-mode such as P2 remain clear at all contour levels and spatial resolutions.These key results can help determine the optimal diagnostics,laser,and target parameters for implosion experiments.Recent typical hot-spot asymmetry measurements and applications on the Shenguang 100 kJ class laser facility are also reported.展开更多
Self-emission x-ray shadowgraphy provides a method to measure the ablation-front trajectory and low-mode nonuniformity of a target imploded by directly illuminating a fusion capsule with laser beams. The technique use...Self-emission x-ray shadowgraphy provides a method to measure the ablation-front trajectory and low-mode nonuniformity of a target imploded by directly illuminating a fusion capsule with laser beams. The technique uses time-resolved images of soft x-rays(>1 ke V) emitted from the coronal plasma of the target imaged onto an x-ray framing camera to determine the position of the ablation front. Methods used to accurately measure the ablation-front radius(δ R= ±1.15 μm), image-to-image timing(δ( t)= ±2.5 ps) and absolute timing(δt= ±10 ps) are presented.Angular averaging of the images provides an average radius measurement of δ( Rav)= ±0.15 μm and an error in velocity of δV / V= ±3%. This technique was applied on the Omega Laser Facility [Boehly et al., Opt. Commun. 133, 495(1997)] and the National Ignition Facility [Campbell and Hogan, Plasma Phys. Control. Fusion 41, B39(1999)].展开更多
We present an experimental study of the dynamics of shocks generated by the interaction of a double-spot laser in different kinds of targets:simple aluminum foils and foam-aluminum layered targets.The experiment was p...We present an experimental study of the dynamics of shocks generated by the interaction of a double-spot laser in different kinds of targets:simple aluminum foils and foam-aluminum layered targets.The experiment was performed using the Prague PALS iodine laser working at 0.44μm wavelength and irradiance of a few 10^(15)W/cm^(2).Shock breakouts for pure Al and for foam-Al targets have been recorded using time-resolved self-emission diagnostics.Experimental results have been compared with numerical simulations.The shocks originating from two spots move forward and expand radially in the targets,finally colliding in the intermediate region and producing a very strong increase in pressure.This is particularly clear for the case of foam layered targets,where we also observed a delay of shock breakout and a spatial redistribution of the pressure.The influence of the foam layer doped with high-Z(Au)nanoparticles on the shock dynamics was also studied.展开更多
基金National Key R&D Program(No.2017YFA0403204)Laser Fusion Research Funds for Young Talents(No.RCFPD1-2017-1)。
文摘Implosion asymmetry is a crucial problem quenching ignition in the field of inertial confinement fusion.A forward-calculation method based on 1D and 2D hydrodynamic simulations has been developed to generate and study the x-ray images of hot-spot self-emission,indicating asymmetry integrated over the entire drive pulse.It is shown that the x-ray imaging photon energy should be higher to avoid the influence of the remaining shell.The contour level(percentage of the maximum emission intensity)and spatial resolution should be as low as possible,optimally less than 20%and 3μm,for characterization of higher-mode signatures such as Ps-P12 by x-ray self-emission images.On the contrary,signatures of lower-mode such as P2 remain clear at all contour levels and spatial resolutions.These key results can help determine the optimal diagnostics,laser,and target parameters for implosion experiments.Recent typical hot-spot asymmetry measurements and applications on the Shenguang 100 kJ class laser facility are also reported.
基金supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944the University of Rochester and the New York State Energy Research and Development AuthorityThe support of DOE does not constitute an endorsement by DOE of the views expressed in this paper
文摘Self-emission x-ray shadowgraphy provides a method to measure the ablation-front trajectory and low-mode nonuniformity of a target imploded by directly illuminating a fusion capsule with laser beams. The technique uses time-resolved images of soft x-rays(>1 ke V) emitted from the coronal plasma of the target imaged onto an x-ray framing camera to determine the position of the ablation front. Methods used to accurately measure the ablation-front radius(δ R= ±1.15 μm), image-to-image timing(δ( t)= ±2.5 ps) and absolute timing(δt= ±10 ps) are presented.Angular averaging of the images provides an average radius measurement of δ( Rav)= ±0.15 μm and an error in velocity of δV / V= ±3%. This technique was applied on the Omega Laser Facility [Boehly et al., Opt. Commun. 133, 495(1997)] and the National Ignition Facility [Campbell and Hogan, Plasma Phys. Control. Fusion 41, B39(1999)].
基金funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No.633053supported by the European Union under the Laserlab program,by the Competitiveness Program of NRNU MEPh I,Russia,and by the Czech Ministry of Education,Youth and Sports(CMEYS),projects LTT17015 and LM2018114。
文摘We present an experimental study of the dynamics of shocks generated by the interaction of a double-spot laser in different kinds of targets:simple aluminum foils and foam-aluminum layered targets.The experiment was performed using the Prague PALS iodine laser working at 0.44μm wavelength and irradiance of a few 10^(15)W/cm^(2).Shock breakouts for pure Al and for foam-Al targets have been recorded using time-resolved self-emission diagnostics.Experimental results have been compared with numerical simulations.The shocks originating from two spots move forward and expand radially in the targets,finally colliding in the intermediate region and producing a very strong increase in pressure.This is particularly clear for the case of foam layered targets,where we also observed a delay of shock breakout and a spatial redistribution of the pressure.The influence of the foam layer doped with high-Z(Au)nanoparticles on the shock dynamics was also studied.