Electron acceleration using twisted laser wavefronts
Electron acceleration using twisted laser wavefronts
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DOI：
10.1088/1361-6587/ac318d
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发表时间：
2021-09
影响因子：
2.2
通讯作者：
Yin Shi;David R Blackman;A. Arefiev
中科院分区：
文献类型：
--
作者：
Yin Shi;David R Blackman;A. Arefiev
使用等离子体镜注入，我们证明，无论是解析和数值计算，圆偏振螺旋激光脉冲可以加速高度准直的密集电子束到几百兆电子伏，使用目前可用的激光系统。圆偏振螺旋（拉盖尔-高斯）光束具有独特的场结构，其中横向场具有螺旋状波前，其在轴上趋于零，在焦点处，存在大的轴上纵向磁场和电场。这种类型的激光脉冲的电子的加速作为径向模式数的函数进行了分析，它表明，径向模式数有一个深刻的影响电子加速靠近激光轴。利用三维粒子模拟方法，对功率为0.6PW的圆偏振螺旋激光束进行了数值模拟，得到了多个密集的阿秒束团。最接近激光包络峰值的聚束具有0.47 GeV的能量，其扩展窄至10%，电荷为26 pC，持续时间为1.400 μ s，并且发散度非常低，为20 mrad。在近轴区域中由纵向磁场的约束允许纵向电场在初始反射之后的长时间内加速电子。在这个方案中，纵向E和B场对电子加速都是必不可少的。这为世界各地的许多激光设施开辟了通往阿秒电子束或阿秒辐射的新途径。
Using plasma mirror injection we demonstrate, both analytically and numerically, that a circularly polarized helical laser pulse can accelerate highly collimated dense bunches of electrons to several hundred MeV using currently available laser systems. The circular-polarized helical (Laguerre–Gaussian) beam has a unique field structure where the transverse fields have helix-like wave-fronts which tend to zero on-axis where, at focus, there are large on-axis longitudinal magnetic and electric fields. The acceleration of electrons by this type of laser pulse is analyzed as a function of radial mode number and it is shown that the radial mode number has a profound effect on electron acceleration close to the laser axis. Using three-dimensional particle-in-cell simulations a circular-polarized helical laser beam with power of 0.6 PW is shown to produce several dense attosecond bunches. The bunch nearest the peak of the laser envelope has an energy of 0.47 GeV with spread as narrow as 10%, a charge of 26 pC with duration of ∼400 as, and a very low divergence of 20 mrad. The confinement by longitudinal magnetic fields in the near-axis region allows the longitudinal electric fields to accelerate the electrons over a long period after the initial reflection. Both the longitudinal E and B fields are shown to be essential for electron acceleration in this scheme. This opens up new paths toward attosecond electron beams, or attosecond radiation, at many laser facilities around the world.