Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch
Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch
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DOI：
10.1103/physrevaccelbeams.19.071301
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发表时间：
2016-07-20
影响因子：
1.7
通讯作者：
Zepf, M.
中科院分区：
文献类型：
--
作者：
Kuschel, S.;Hollatz, D.;Zepf, M.
我们报告了使用两级设置的被动全光学等离子体透镜的首次演示。强飞秒激光将激光尾场加速器 (LWFA) 中的电子在毫米长度尺度上加速至 100 MeV。通过在初始 LWFA 级后面添加第二个气体目标，我们引入了坚固且独立可调的等离子体透镜。我们观察到，当等离子体透镜运行时，LWFA 电子束发散度随密度的变化而减小，从初始值 2.3 mrad 降至 1.4 mrad (rms)。这种等离子体透镜提供了一种简单而紧凑的减少发散的方法，与 LWFA 加速器的毫米级长度非常匹配。聚焦力仅由等离子体提供并仅由束团本身驱动，这使得这是一种非常有用且概念上新的电子束聚焦方法。该透镜的可能应用不限于激光等离子体加速器。由于不需要有源驱动器，无源等离子体透镜也适用于电子束的高重复率聚焦。对粒子驱动尾流场加速中驱动粒子束的演化进行建模也需要它的理解。
We report on the first demonstration of passive all-optical plasma lensing using a two-stage setup. An intense femtosecond laser accelerates electrons in a laser wakefield accelerator (LWFA) to 100 MeV over millimeter length scales. By adding a second gas target behind the initial LWFA stage we introduce a robust and independently tunable plasma lens. We observe a density dependent reduction of the LWFA electron beam divergence from an initial value of 2.3 mrad, down to 1.4 mrad (rms), when the plasma lens is in operation. Such a plasma lens provides a simple and compact approach for divergence reduction well matched to the mm-scale length of the LWFA accelerator. The focusing forces are provided solely by the plasma and driven by the bunch itself only, making this a highly useful and conceptually new approach to electron beam focusing. Possible applications of this lens are not limited to laser plasma accelerators. Since no active driver is needed the passive plasma lens is also suited for high repetition rate focusing of electron bunches. Its understanding is also required for modeling the evolution of the driving particle bunch in particle driven wake field acceleration.