Laser and beam driven wakefields promise orders of magnitude increases in electric field gradients for particle accelerators for future applications. Key areas to explore include the emittance properties of the generated beams and overcoming the dephasing limit in the plasma. In this paper, the first in-depth study of the self-injection mechanism into wakefield structures from nonhomogeneous cluster plasmas is provided using high-resolution two dimensional particle-in-cell simulations. The clusters which are typical structures caused by ejection of gases from a high-pressure gas jet have a diameter much smaller than the laser wavelength. Conclusive evidence is provided for the underlying mechanism that leads to particle trapping, comparing uniform and cluster plasma cases. The accelerated electron beam properties are found to be tunable by changing the cluster parameters. The mechanism explains enhanced beam charge paired with large transverse momentum and energy which has implications for the betatron x-ray flux. Finally, the impact of clusters on the high-power laser propagation behavior is discussed.

中文翻译：

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团簇等离子体中的非线性尾场和电子注入

激光和光束驱动的尾波场有望使粒子加速器的电场梯度增加几个数量级，以备将来应用。需要探索的关键领域包括所产生光束的发射特性以及如何克服等离子体中的移相极限。在本文中，首次使用高分辨率的二维像元模拟技术，对非均匀团簇等离子体向尾波场结构的自注入机理进行了首次深入研究。团簇是由高压气体射流中的气体喷射引起的典型结构，其直径远小于激光波长。对于导致颗粒捕集，比较均匀和簇状血浆情况的潜在机理，提供了确凿的证据。发现通过改变簇参数可以调节加速的电子束性能。该机制解释了增强的束电荷与大的横向动量和能量配对，这对电子感应加速器的X射线通量有影响。最后，讨论了簇对高功率激光传播行为的影响。