Plasma wakefield dynamics over timescales up to 800 ps, approximately 100 plasma periods, are studied experimentally at the Advanced Wakefield Experiment (AWAKE). The development of the longitudinal wakefield amplitude driven by a self-modulated proton bunch is measured using the external injection of witness electrons that sample the fields. In simulation, resonant excitation of the wakefield causes plasma electron trajectory crossing, resulting in the development of a potential outside the plasma boundary as electrons are transversely ejected. Trends consistent with the presence of this potential are experimentally measured and their dependence on wakefield amplitude are studied via seed laser timing scans and electron injection delay scans.

中文翻译：

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自调制质子束驱动的等离子体尾流场扩展时标动力学的实验研究

在高级Wakefield实验（AWAKE）上，对高达800 ps（约100个等离子体周期）的时间尺度上的等离子体尾流动力学进行了研究。由自调制质子束驱动的纵向尾波场振幅的发展是使用对场进行采样的见证电子的外部注入来测量的。在仿真中，尾场的共振激发导致等离子体电子轨迹交叉，从而导致电子横向发射时，在等离子体边界外产生电势。通过实验测量了与该电位的存在相一致的趋势，并通过种子激光定时扫描和电子注入延迟扫描研究了它们对尾波场振幅的依赖性。