We study experimentally the longitudinal and transverse wakefields driven by a highly relativistic proton bunch during self-modulation in plasma. We show that the wakefields’ growth and amplitude increase with increasing seed amplitude as well as with the proton bunch charge in the plasma. We study transverse wakefields using the maximum radius of the proton bunch distribution measured on a screen downstream from the plasma. We study longitudinal wakefields by externally injecting electrons and measuring their final energy. Measurements agree with trends predicted by theory and numerical simulations and validate our understanding of the development of self-modulation. Experiments were performed in the context of the Advanced Wakefield Experiment (AWAKE) .

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等离子体中自调节质子束驱动尾流场的实验研究

我们实验研究在等离子体的自调制过程中由高度相对论质子束驱动的纵向和横向尾波场。我们表明尾流场的增长和幅度随着种子幅度的增加以及等离子体中质子束电荷的增加而增加。我们使用质子束分布的最大半径在等离子体下游的屏幕上测量横向尾流场。我们通过外部注入电子并测量其最终能量来研究纵向尾流场。测量结果符合理论和数值模拟预测的趋势，并验证了我们对自调节发展的理解。实验是在高级韦克菲尔德实验（AWAKE）的背景下进行的。