强激光驱动锥口多层靶的超热电子输运特性  

Hot Electron Transport Characteristics in a Conical-Entry-Multilayer Target Driven by Intense Laser

作　　者：赵权平 宋海英[1,2] 汪洋[1,2] 刘勋[3] 李维[3] 刘世炳[1,2] Zhao Quanping;Song Haiying;Wang Yang;Liu Xun;Li Wei;Liu Shibing(Strong-Field and Ultrafast Photonics Lab,Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China;Key Laboratory of Trans-Scale Laser Manufacturing Technology,Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China;Beijing Institute of Space Mechanics and Electricity,Beijing 100094,China)

机构地区：[1]北京工业大学材料与制造学部强场与超快光子学实验室,北京100124 [2]北京工业大学材料与制造学部教育部跨尺度成型重点实验室,北京100124 [3]北京空间机电研究所,北京100094

出　　处：《中国激光》2021年第24期10-18,共9页Chinese Journal of Lasers

基　　金：国家重点研发计划(2018YFB0504400);国家自然科学基金(51875006,51705009);北京市教委科技计划(KM201810005001)。

摘　　要：为了提升超热电子的准直输运效率,提出了锥口多层靶模型,并通过二维PIC(particle-in-cell)模拟手段研究了强激光与锥口多层靶相互作用过程中超热电子的产生和输运特性。研究结果表明,相比于无锥结构的多层靶,锥口多层靶中输运的超热电子数目更多、能量更高且空间分布也更加集中,发散角被控制在-38°~38°之间的超热电子能量约增加了0.6倍,锥口多层靶能够提升超热电子的准直输运效率。锥口多层靶中超热电子准直输运效率提升的原因主要有三个方面:激光从锥壁上拉出了大量超热电子、锥壁对激光的聚焦作用增强了激光有质动力以及锥顶后方产生了较强的自生磁场分布。本文建立的模型对于提升“快点火”中超热电子的束品质具有重要意义。Objective In the research of inertial confinement fusion,the conventional center ignition scheme has very high requirements on the uniformity and symmetry of deuterium-tritium(D-T)pellet pellet compression and driver energy.To reduce these requirements,a fast ignition scheme has been proposed.In this scheme,the pellet would be first compressed to a state of high temperature and density,and then,the plasma would be driven by a short highintensity laser pulse to produce several MeV magnitude hot electrons,which would then need to travel for a distance of dozens of micrometers to deposit their energy into a small volume of the pellet,igniting the pellet.Finally,fusion would be realized.Therefore,the fast ignition scheme needs a high beam quality of hot electrons.However,the Weibel,filament,and two-stream instabilities may decrease the beam quality of hot electrons during their transmission,which severely restricts the realization of the fast ignition scheme of inertial confinement fusion.In this study,a conical-entry-multilayer target is proposed to improve the collimation and transport efficiency of hot electrons.We hope that the model established in this study has a good significance for improving the beam quality of hot electrons in fast ignition.Methods In this study,the generation and transport characteristics of hot electrons in the interaction between an intense laser and the conical-entry-multilayer target are investigated using the two-dimensional particle-in-cell simulation program Vorpal.We design two types of targets,namely,multilayer target and conical-entry-multilayer target.The multilayer target is mainly used as a reference to determine whether the conical-entry-multilayer target can improve the collimation and transport efficiency of hot electrons.By comparing the energy density distribution,longitudinal and transverse distribution,energy spectrum,and divergence angle distribution of hot electrons in the two targets,it is proved that the collimation and transport efficiency of hot electrons in the c

关 键 词：激光物理 强激光 锥口多层靶 超热电子输运 

分 类 号：O532[理学—等离子体物理]