Mechanisms to control laser-plasma coupling in laser wakefield electron acceleration
Mechanisms to control laser-plasma coupling in laser wakefield electron acceleration
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DOI：
10.1103/physrevaccelbeams.25.101301
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发表时间：
2022-08
影响因子：
1.7
通讯作者：
L. Dickson;C. Underwood;F. Filippi;R. Shalloo;J. Svensson;D. Gu'enot;K. Svendsen;I. Moulanier;S. D. Dufr'enoy;C. Murphy;N. Lopes;P. Rajeev;Z. Najmudin;G. Cantono;A. Persson;O. Lundh;G. Maynard;M. Streeter;B. Cros
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作者：
L. Dickson;C. Underwood;F. Filippi;R. Shalloo;J. Svensson;D. Gu'enot;K. Svendsen;I. Moulanier;S. D. Dufr'enoy;C. Murphy;N. Lopes;P. Rajeev;Z. Najmudin;G. Cantono;A. Persson;O. Lundh;G. Maynard;M. Streeter;B. Cros
实验结果在精确建模的支持下，证明了对具有中间激光脉冲能量 ($<1$ J) 的基于等离子体的注入器的优化，对应于归一化矢量势 $a_0 = 2.15$，在定制的等离子体密度分布中使用电离注入。通过延长等离子体出口处的密度下降斜坡，可以通过实验实现电子束质量和能量的增加。在定制的等离子体密度分布中优化激光脉冲的焦点位置可以有效地减少电子束角偏差，从而使电子束与激光轴更好地对准。通过优化焦前激光能量分布的对称性，将早期焦点位置和激光波前的自适应光学控制相结合，以以前未探索过的方式产生单峰电子光谱。实验结果已通过使用真实激光能量、相位分布和时间包络的细胞内粒子模拟得到验证，从而可以准确预测难以建模的参数，例如电子束的总电荷和空间特性，为基于等离子体的加速器设计更精确的建模开辟了道路。
Experimental results, supported by precise modelling, demonstrate optimisation of a plasma-based injector with intermediate laser pulse energy ($<1$ J), corresponding to a normalised vector potential $a_0 = 2.15$, using ionisation injection in a tailored plasma density profile. An increase in electron bunch quality and energy is achieved experimentally with the extension of the density downramp at the plasma exit. Optimisation of the focal position of the laser pulse in the tailored plasma density profile is shown to efficiently reduce electron bunch angular deviation, leading to a better alignment of the electron bunch with the laser axis. Single peak electron spectra are produced in a previously unexplored regime by combining an early focal position and adaptive optic control of the laser wavefront through optimising the symmetry of the pre-focal laser energy distribution. Experimental results have been validated through particle-in-cell simulations using realistic laser energy, phase distribution, and temporal envelope, allowing for accurate predictions of difficult to model parameters, such as total charge and spatial properties of the electron bunches, opening the way for more accurate modelling for the design of plasma-based accelerators.