弱相对论涡旋光在等离子体中传播的波前畸变及补偿  

Wavefront distortion and compensation for weakly relativistic vortex beams propagating in plasma

作　　者：刘伟[1] 贾青 郑坚[1,2] Liu Wei;Jia Qing;Zheng Jian(Department of Plasma Physics and Fusion Engineering,University of Science and Technology of China,Hefei 230026,China;Collaborative Innovation Center of IFSA,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]中国科学技术大学等离子体物理与聚变工程系,合肥230026 [2]上海交通大学IFSA协同创新中心,上海200240

出　　处：《物理学报》2024年第5期237-246,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11975014);中国科学院战略性先导科技专项(批准号:XDA25050400,XDA25010200)资助的课题.

摘　　要：涡旋光与等离子体相互作用近年来在激光等离子体领域引起了广泛的关注.深入研究涡旋光在等离子体中的传播对粒子加速和辐射源产生等工作具有重要意义.本文着重探讨了弱相对论涡旋光在等离子中传播时,传播过程对电磁波结构的影响.基于三维粒子模拟,发现弱相对论涡旋光在等离子体中传播时会产生波前畸变.在给定等离子体密度时,畸变程度与电磁波强度及传播距离密切相关.基于相位修正模型,通过考虑电子相对论质量修正,在理论上对该现象进行了解释.此外,研究还发现可以通过设置适当的初始密度调制对波前畸变进行补偿抑制,并通过三维粒子模拟进行了验证.本工作加强了对涡旋光在等离子体中传播过程的理解,并为设计应用于相对论涡旋光的等离子体器件提供了参考.The propagation of electromagnetic wave in plasma is one of the long-standing concerns in the field of laser plasma,and it is closely related to the researches of radiation source generation,particle acceleration,and inertial confinement fusion.Recently,the proposal of various schemes for generating intense vortex beams has led to an increasing number of researchers focusing on the interaction between intense vortex beams and plasmas,resulting in significant research progress in various areas,such as particle acceleration,high-order harmonic generation,quasi-static self-generated magnetic fields,and parametric instability.Compared with traditional Gaussian beams,vortex beams,featuring their hollow amplitudes and helical phases,can exhibit novel phenomena during propagating through plasma.In this work,we primarily focus on studying the influence of the propagation process on the wave structure of vortex beams before filamentation occurs.The three-dimensional particle-in-cell simulations show that weakly relativistic vortex beams exhibit wavefront distortion during their propagation in plasma.The distortion degree is closely related to the intensity of the electromagnetic wave and the propagation distance for a given plasma density.This phenomenon is theoretically explained by using a phase correction model that considers the relativistic mass correction of electrons.Additionally,we demonstrate that the wavefront distortion can be compensated for and suppressed by appropriately modulating the initial plasma density,as confirmed by three-dimensional particle simulations.The results of decomposing the wavefront into Laguerre-Gaussian(LG)mode components indicate that the wavefront distortion is primarily caused by high-order p LG modes,and it is independent of other l LG modes.Additionally,we extend the present investigation to the propagation of vortex beams in axially magnetized plasma,where the phase correction model can also effectively explain the occurrence of wavefront distortion.Our work can deepen the underst

关 键 词：激光等离子体物理 涡旋光束 非线性传播 粒子模拟 

分 类 号：O53[理学—等离子体物理]