Electron-positron pair production by means of vacuum polarization in the presence of strong electromagnetic (EM) field of two counterpropagating laser pulses is studied. A 3-dimensional model of the focused laser pulses based on the solution of the Maxwell's equations proposed by Narozhny and Fofanov is used to find the structure of EM field of the circularly polarized counterpropagating pulses. Analytical calculations show that the electric and magnetic fields are almost parallel to each other in the focal region when pulses are completely transverse either in electric (e-wave) or magnetic (h-wave) field. On the other hand the electric and magnetic fields are almost orthogonal when the counterpropagating pulses are made up of equal mixture of e- and h- polarized waves. It is found that while the latter configuration of the colliding pulses has much larger threshold for pair production it can provide much shorter electron/positron pulses compared to the former case. The dependence of pair production and its spatiotemporal distribution on polarization of the laser pulses is analyzed using the structure of the EM field.
Radiating Electron Interaction with Multiple Colliding Electromagnetic Waves: Random Walk Trajectories, Levy Flights, Limit Circles, and Attractors (Survey of the Structurally Determinate Patterns)
Generation of Isolated Collimated Polarized $γ$-ray Beams via Spatiotemporal Optical Vortex Modulation
State Key Laboratory of Ultra-Intense Laser Science and Technology, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS)（中国科学院上海光学精密机械研究所）；Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences（中国科学院大学材料科学与光电技术学院）；Laboratory of Zhongyuan Light, School of Physics, Zhengzhou University（郑州大学物理学院中原之光实验室）；State Key Laboratory of Dark Matter Physics, Key Laboratory for Laser Plasmas (MoE), School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院激光等离子体教育部重点实验室暗物质物理国家重点实验室）
On the Schwinger limit attainability with extreme power lasers
圆偏振对撞激光脉冲可以产生丰富的电子-正电子对等离子体[A. R. Bell和J.G. Kirk，Phys. Rev. Lett. 101，200403（2008）]，其散射入射的电磁波可以防止它们到达量子电动力学的临界场，导致真空击穿和极化。结果表明，辐射摩擦效应和正负电子雪崩的发展依赖于电磁波的极化。对于圆极化碰撞脉冲，迫使电子作圆周运动，这些效应不仅支配粒子运动，而且支配脉冲的演化。而对于电子（正电子）沿电场振荡的线性极化脉冲，这些效应没有那么强。这些情况与圆形和线性电子加速器有明显的相似之处，它们具有相应的限制和减少同步辐射损失的作用。
Generation of High Brightness Electron Beams via Ionization Induced Injection by Transverse Colliding Lasers in a Beam-Driven Plasma Wakefield Accelerator
采用三维粒子模拟方法研究了在束流驱动等离子体尾流中，利用两束横向碰撞的激光脉冲触发电离注入产生超亮电子束团的过程.相对低强度的激光沿着尾流轴偏振，并且在非常短的时间内与尾流重叠。其结果是，电离电子在尾流横截面中的剩余动量大大减少，并且注入沿尾流的传播轴局部化。这最小化了初始的“热”发射度和由于横向相混合引起的发射度增长。三维PIC模拟结果表明，在实际参数下，可以得到超短（约8 fs）强流（0.4 kA）电子束团，其两个平面的归一化发射度分别为8.5和6 nm，亮度大于1.7* 10 e19 A rad-2 m-2。
Colliding ionization injection in a beam driven plasma accelerator
通过二维粒子模拟研究了在束流驱动等离子体尾流中，由反向传播的激光脉冲触发电离注入产生高质量电子聚束的方案。它表明，使用这种技术获得的电子聚束可以有非常小的切片能量扩展，因为每个切片主要是由电子在同一时间电离。另一个显著的优点是注射距离是可变的。通过调节驱动光束的发射时间或改变激光焦点位置，获得了归一化发射度为3.3 nm、片能量扩展为15 keV、亮度为$7.2\times 10^{18}$ A m $^{-2}$ rad $^{-2}$的聚束。这使得该方案成为产生用于第五代光源的高质量电子聚束的有前途的方法。
