We propose a scheme to overcome the great challenge of polarization loss in spin-polarized ion acceleration. When a petawatt laser pulse penetrates through a compound plasma target consisting of a double layer slab and prepolarized hydrogen halide gas, a strong forward moving quasistatic longitudinal electric field is constructed by the self-generated laser-driven plasma. This field with a varying drift velocity efficiently boosts the prepolarized protons via a two-stage coherent acceleration process. Its merit is not only achieving a highly energetic beam but also eliminating the undesired polarization loss of the accelerated protons. We study the proton dynamics via Hamiltonian analyses, specifically deriving the threshold of triggering the two-stage coherent acceleration. To confirm the theoretical predictions, we perform three-dimensional PIC simulations, where unprecedented proton beams with energy approximating half GeV and polarization ratio $\sim$ 94% are obtained.

中文翻译：

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激光驱动等离子体中两级相干加速度的高能自旋极化质子束

我们提出一种方案来克服自旋极化离子加速中极化损失的巨大挑战。当一个petawatt激光脉冲穿透由双层平板和预极化卤化氢气体组成的复合等离子体靶时，由自生激光驱动等离子体将构成一个强向前移动的准静态纵向电场。漂移速度变化的场通过两阶段相干加速过程有效地增强了预极化质子。其优点不仅在于获得高能束，而且还消除了加速质子的不希望的极化损失。我们通过汉密尔顿分析研究质子动力学，具体推导了触发两阶段相干加速度的阈值。为了确认理论预测，$〜$ 获得94％。