快点火中质子的能量沉积和神光Ⅱ升级装置上的质子束的产生  

Proton beam energy deposition in fast ignition and production of protons on Shenguang II upgraded device

作　　者：何民卿[1] 张华 李明强 彭力 周沧涛 He Min-Qing;Zhang Hua;Li Ming-Qiang;Peng Li;Zhou Cang-Tao(Institute of Applied Physics and Computational Mathematics,Beijing 100094,China;Center for Advanced Material Diagnostic Technology,Shenzhen Technology University,Shenzhen 518118,China;Engineering Physics College,Shenzhen Technology University,Shenzhen 518118,China)

机构地区：[1]北京应用物理与计算数学研究所,北京100094 [2]深圳技术大学,先进材料测试技术研究中心,深圳518118 [3]深圳技术大学工程物理学院,深圳518118

出　　处：《物理学报》2023年第9期251-258,共8页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2016YFA0401100);国家自然科学基金(批准号:12075033,11975055);科学挑战专题(批准号:TZ2018005)资助的课题。

摘　　要：基于神光Ⅱ升级装置激光条件,利用流体程序、粒子模拟程序和Fokker-Placnck程序,模拟研究质子快点火中所需质子束的品质以及产生所需质子束的激光条件.首先根据快点火靶的条件,利用Fokker-Planck方程模拟快点火所需的质子束的能量范围,模拟表明当背景等离子密度为300 g/cm^(3)时,能量为7—12 MeV的质子束适合点火;当背景等离子体密度为400 g/cm^(3)时,能量为8—18 MeV的质子束适合点火.再根据神光Ⅱ升级装置实验条件研究质子束所需的激光参数,通过利用粒子模拟程序,结合流体程序给出的预等离子体,分别模拟研究了加预等离子体和不加预等离子体两种情况下的质子加速,在有预等离子体时得到的质子束最大能量约为22 MeV,没有预等离子体时得到的质子束最大能量为17.5 MeV,具体分析了两种情况下质子加速的物理机制,其结果跟等离子体自由膨胀模型结果符合得很好.The proton beam energy deposition and the prodution of proton beams in proton fast ignition are investigated with the fluid program,partice-in-cell program and Fokker-Planck program based on the parameters of Shenguang II upgraded device.Firstly,according to the target parameters of fast ignition,the energy depositions of different energy protons are investigated.It is obtained that the higher the incident proton energy,the higher the surface density that the protons go through,accordingly the longer the proton deposition distance in the same background plasma density.On the assumption that the diameter of the compression core is 20–30μm,and that the protons deposited in the core give the energy to the background plasma,the energy of the proton required by fast ignition is obtained by Fokker-Planck simulation.Protons with energy of 7–12 MeV are appropriate for ignition when the background plasma density is 300 g/cm^(3),while 8–18 MeV protons for 400 g/cm^(3).The background plasma temperatures are both 5 keV in the two cases.Secondly,we use particlein-cell program to study the proton acceleration with or without preplasma which is given by fluid program with using the laser intensity I=5:4×10^(19) W/cm^(2) based on the parameters of Shenguang II upgraded device.The laser has 350 J of enegy,3 ps of Gaussion pluse width and 10μm of spot radius.The curvature of the target which is 10μm thick copper coated with 1μm thick hydrogen plasma,is 500μm.The maximum proton energy obtained with preplama is 22 MeV,however the maximum proton energy obtained without preplasma is 17.5 MeV.The conversion efficiency from laser to protons is 5.12%with preplasma and 4.15%without preplasma.The conversion efficiency with preplasma is 20%higher than that without preplasma.We also study the mechanisms of the acceleration in the two situations.The freely expanding plasma model is used to explain the acceleration mechanism.The simulated electric field is smaller than that calculated by using the freely expanding plasma model,beca

关 键 词：质子束快点火 能量沉积 质子加速 

分 类 号：TL62[核科学技术—核技术及应用]