Although the interaction of a flat foil with currently available laser intensities is now considered a routine process, during the last decade, emphasis has been given to targets with complex geometries aiming at increasing the ion energy. This work presents a target geometry where two symmetric side holes and a central hole are drilled into the foil. A study of the various side-hole and central-hole length combinations is performed with two-dimensional particle-in-cell simulations for polyethylene targets and a laser intensity of $5.2\times 10^{21}~\text{W}~\text{cm}^{-2}$ . The holed targets show a remarkable increase of the conversion efficiency, which corresponds to a different target configuration for electrons, protons and carbon ions. Furthermore, diffraction of the laser pulse leads to a directional high energy electron beam, with a temperature of ${\sim}40~\text{MeV}$ , or seven times higher than in the case of a flat foil. The higher conversion efficiency consequently leads to a significant enhancement of the maximum proton energy from holed targets.

中文翻译：

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用有孔目标实现激光离子加速

尽管平面箔与当前可用的激光强度的相互作用现在被认为是一种常规过程，但在过去十年中，重点放在了旨在增加离子能量的具有复杂几何形状的目标上。这项工作提出了一个目标几何形状，其中两个对称的侧孔和一个中心孔钻入箔片。采用聚乙烯靶材的二维细胞内粒子模拟和激光强度为 $5.2\times 10^{21}~\text{W}~\text{cm}^{-2}$ . 有孔靶材显示出转换效率的显着提高，这对应于电子、质子和碳离子的不同靶材配置。此外，激光脉冲的衍射导致定向的高能电子束，其温度为 ${\sim}40~\text{MeV}$ ，或者是平箔情况下的七倍。因此，更高的转换效率导致来自有孔目标的最大质子能量显着增强。