Research Of Alpha-Particle Diffusion And The Application In Laser Driven Nuclear Fusion

With the rapid progress of laser technology and the expansion of its application,the research of inertial confinement fusion(ICF)can be explored futherly.The laser-driven ICF involves a lot with forontier of high-energy-density physics,which is abundant of unclear physical process,including laser plasmas instability,hydrodynamical instability.In this paper,the main work is as follows:Firstly,a new module is writen and integrated into the multiphysics radiation hydrodynamic(RHD)code.Such module can reveal the nuclear reation and charged particle diffusion in the hydrodynamical structure.After that,the laser energy deposition,hohlraum radiation,ablative implosion and fusion ignition can be simulated in one single case.Based on the indirect drive scheme(NIF)laser and target parameters,we got the diffusion of α-particle energy,which is useful for the lateral target design.Secondly,the plasma jet generation mechanism is studied in laser-driven HED environment,and the condition of HED plasma jet generation is clarified.Combining theoretical analysis and simulation,we optimized the laser and target parameters to HED plasma jet with higher energy.The results indicate that when the laser ablated nearly 80% of the target,the highest conversion efficiency(CE)from laser to kinetic energy of plasma jet can be achieved.And when the half-cone angle is set as 70°,a stable and cumulated HED plasma jet can be expected.Finally,we primitively studied the feasibility of a newly proposed ignition scheme,which utilizes double cones to guide the implosion and then achieve fast ignition by ultraintense laser pulse.We figure out the influence of different angles on implosion of layers,and small angles is found to do harm to the quasi-spherical implosion.Due to the incoherence of layer implosion velocity,high collision density can not be obtained in small angles.And then,a proper 55° opening angle is proposed to carry out the experiments.After that,we propose a shaped laser pulse to realize the initial slow compression and later fast compression,which effectively improves the compression density.