A recently proposed octahedral spherical hohlraum with six laser entrance holes(LEHs)is an attractive concept for an upgraded laser facility aiming at a predictable and reproducible fusion gain with a simple target de...A recently proposed octahedral spherical hohlraum with six laser entrance holes(LEHs)is an attractive concept for an upgraded laser facility aiming at a predictable and reproducible fusion gain with a simple target design.However,with the laser energies available at present,LEH size can be a critical issue.Owing to the uncertainties in simulation results,the LEH size should be determined on the basis of experimental evidence.However,determination of LEH size of an ignition target at a small-scale laser facility poses difficulties.In this paper,we propose to use the prepulse of an ignition pulse to determine the LEH size for ignition-scale hohlraums via LEH closure behavior,and we present convincing evidence from multiple diagnostics at the SGIII facility with ignition-scale hohlraum,laser prepulse,and laser beam size.The LEH closure observed in our experiment is in agreement with data from the National Ignition Facility.The total LEH area of the octahedral hohlraum is found to be very close to that of a cylindrical hohlraum,thus successfully demonstrating the feasibility of the octahedral hohlraum in terms of laser energy,which is crucially important for sizing an ignition-scale octahedrally configured laser system.This work provides a novel way to determine the LEH size of an ignition target at a small-scale laser facility,and it can be applied to other hohlraum configurations for the indirect drive approach.展开更多
A nonlinear finite volume element scheme for anisotropic diffusion problems on general triangular meshes is proposed.Starting with a standard linear conforming finite volume element approximation,a corrective term wit...A nonlinear finite volume element scheme for anisotropic diffusion problems on general triangular meshes is proposed.Starting with a standard linear conforming finite volume element approximation,a corrective term with respect to the flux jumps across element boundaries is added to make the scheme satisfy the discrete maximum principle.The new scheme is free of the anisotropic non-obtuse angle condition which is a severe restriction on the grids for problems with anisotropic diffusion.Moreover,this manipulation can nearly keep the same accuracy as the original scheme.We prove the existence of the numerical solution for this nonlinear scheme theoretically.Numerical results and a grid convergence study are presented for both continuous and discontinuous anisotropic diffusion problems.展开更多
基金This work is supported by the National Natural Science Foundation of China(Grant No.12035002).
文摘A recently proposed octahedral spherical hohlraum with six laser entrance holes(LEHs)is an attractive concept for an upgraded laser facility aiming at a predictable and reproducible fusion gain with a simple target design.However,with the laser energies available at present,LEH size can be a critical issue.Owing to the uncertainties in simulation results,the LEH size should be determined on the basis of experimental evidence.However,determination of LEH size of an ignition target at a small-scale laser facility poses difficulties.In this paper,we propose to use the prepulse of an ignition pulse to determine the LEH size for ignition-scale hohlraums via LEH closure behavior,and we present convincing evidence from multiple diagnostics at the SGIII facility with ignition-scale hohlraum,laser prepulse,and laser beam size.The LEH closure observed in our experiment is in agreement with data from the National Ignition Facility.The total LEH area of the octahedral hohlraum is found to be very close to that of a cylindrical hohlraum,thus successfully demonstrating the feasibility of the octahedral hohlraum in terms of laser energy,which is crucially important for sizing an ignition-scale octahedrally configured laser system.This work provides a novel way to determine the LEH size of an ignition target at a small-scale laser facility,and it can be applied to other hohlraum configurations for the indirect drive approach.
基金supported by the Postdoctoral Science Foundation of China(No.2017M620689)the National Science Foundation of China(Nos.11571048,11401034)the CAEP developing fund of science and technology(No.2014A0202009).
文摘A nonlinear finite volume element scheme for anisotropic diffusion problems on general triangular meshes is proposed.Starting with a standard linear conforming finite volume element approximation,a corrective term with respect to the flux jumps across element boundaries is added to make the scheme satisfy the discrete maximum principle.The new scheme is free of the anisotropic non-obtuse angle condition which is a severe restriction on the grids for problems with anisotropic diffusion.Moreover,this manipulation can nearly keep the same accuracy as the original scheme.We prove the existence of the numerical solution for this nonlinear scheme theoretically.Numerical results and a grid convergence study are presented for both continuous and discontinuous anisotropic diffusion problems.
