激光入射双层等离子体靶产生的表面等离子体波及应用  

Surface plasma wave excited by laser pulse obliquely incident on a double-layer plasma target and ts application

作　　者：李天成 章晓海 盛正卯[1] Li Tian-Cheng;Zhang Xiao-Hai;Sheng Zheng-Mao(Institute for Fusion Theory and Simulation,Zhejiang University,Hangzhou 310058,China)

机构地区：[1]浙江大学,聚变理论与模拟中心,杭州310058

出　　处：《物理学报》2023年第4期161-168,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61627901,11875235)资助的课题。

摘　　要：表面等离子体波的存在可以显著改变激光与等离子体的耦合效率,这在激光驱动粒子加速、强X射线产生、温稠密物质态等领域研究有重要应用.本文利用二维粒子模拟程序,研究了强激光入射双层等离子体靶激发的表面等离子体波.模拟结果表明,不同于单层靶情形,大角度入射的强激光脉冲达到一定强度阈值后,可驱动等离子体表面中的电子形成周期结构,激发静电波,其波长与入射波波长相近,传播速度接近光速;表明双层等离子体更有利于表面波的激发,传播范围更大;双层靶的表面波强度与入射激光强度的比值明显不同于单层靶的理论结果,呈现非线性关系;表面波的存在可以显著增强后续激光脉冲的透射,使后续激光脉冲突破稠密等离子体形成的“黑障”,在远高于临界密度的薄靶后被观察到.Surface plasma wave(SPW) will significantly affect the subsequent mutual coupling between laser and plasma,so there are many important applications such as particle acceleration driven by laser pulses and transmission enhancement.In this work,the properties of the SPW produced by an ultra-short and ultraintensity laser pulse incident on a double-layer plasma target are studied by using the all-electromagnetic largescale two-dimensional particle in cell(PIC) simulations.It is shown that the high-intensity laser incident with a large angle,θ=75°,can drive the electrons of the low-density layer to form a transportable periodic structure with the propagation speed close to light speed,and excite electrostatic wave whose wavelength is similar to that of the incident laser and is numerically close to the theoretical result according to previous theory.In order to excite the SPW,the laser intensity needs to reach a certain threshold.Besides,the ratio of the surface wave intensity to the incident laser intensity in the double-layer target case obviously deviates from the theoretical result of the single-layer target case,showing a nonlinear relationship.In the second part of the simulation,it is found that the SPW can significantly enhance the transmission of subsequent laser pulse,allowing the subsequent laser to break through the "black barrier" due to the dense plasma.A pre-laser irradiates the doublelayer plasma target at θ=75°,and then the subsequent laser is normally incident after a delay of △t=23 T.As a result,an obvious electromagnetic wave with the same direction as the sub-laser can be observed behind the target,which indicates that the sub-laser absolutely transmits the dense plasma.In comparison,when a single laser is normally incident on the target without pre-laser while other conditions keep unchanged,no obvious wave can be distinguished behind the target,that is,the field is nearly zero.Another simulation where a single-layer target is injected by pre-laser and sub-laser in order but the wave behin

关 键 词：激光等离子体相互作用 表面等离子体波 透射增强 数值模拟 

分 类 号：O53[理学—等离子体物理] TN24[理学—物理]