SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
Department of Physics, University of Oslo, 0316 Oslo, Norway.
Nat Commun. 2016 Jun 2;7:11785. doi: 10.1038/ncomms11785.
Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m(-1) is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.
等离子体尾流加速器已被用于加速电子和正电子粒子束，其梯度比传统加速器大几个数量级。除了被等离子体尾流加速外，束流粒子还会受到强烈的横向力，这可能会破坏束流质量。空心等离子体通道已被提议作为一种在不产生横向力的情况下产生加速场的技术。在这里，我们展示了一种创建扩展空心等离子体通道的方法，并测量了超相对论正电子束在穿过通道时产生的尾流场。等离子体通道是通过将具有空间调制轮廓的高强度激光脉冲引导到锂蒸气中而产生的，这导致了一个环形的电离区域。从光束能谱的变化中推断出峰值减速场为 230 MeV m(-1)，与理论和粒子模拟很好地吻合。
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