The acceleration of super-heavy ions (SHIs, mass number of about 200) from plasmas driven by ultrashort (tens of femtoseconds) laser pulses is a challenging topic awaiting a breakthrough. Detecting and controlling the ionization process and adopting the optimal acceleration scheme are crucial for the generation of highly energetic SHIs. Here, we report the experimental results on the generation of deeply ionized super-heavy ions (Au) with unprecedented energy of 1.2 GeV utilizing ultrathin targets and ultrashort laser pulses at an intensity of ${10}^{22}\mathrm{W}/{\mathrm{cm}}^2$. A novel self-calibrated diagnostic method was developed to acquire the absolute energy spectra and charge-state distributions of Au ions abundant at the charge state of $51+$ and extending to $61+$. The measured charge-state distributions supported by 2D particle-in-cell simulations serve as an additional tool to inspect the ionization dynamics associated with SHI acceleration, revealing that the laser intensity is the crucial parameter over the pulse duration for Au acceleration. Achieving a long acceleration time without sacrificing the strength of the acceleration field by utilizing composite targets can substantially increase the maximum energy of Au ions.

中文翻译：

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超高强度超短激光脉冲驱动的超重离子加速

从超短（数十飞秒）激光脉冲驱动的等离子体中加速超重离子（SHI，质量数约为 200）是一个等待突破的具有挑战性的课题。检测和控制电离过程并采用最佳加速方案对于产生高能 SHI 至关重要。在这里，我们报告了利用超薄靶和强度为 1.2 GeV 的超短激光脉冲产生具有前所未有能量的 1.2 GeV 的深度电离超重离子 (Au) 的实验结果。${10}^{22}\mathrm{宽}/{\mathrm{厘米}}^2$. 开发了一种新的自校准诊断方法来获取在电荷态丰富的 Au 离子的绝对能谱和电荷态分布。$51+$ 并扩展到 $61+$. 由 2D 细胞内粒子模拟支持的测量电荷状态分布可作为检查与 SHI 加速相关的电离动力学的附加工具，揭示激光强度是 Au 加速脉冲持续时间的关键参数。利用复合靶材在不牺牲加速场强度的情况下实现较长的加速时间，可以显着提高Au离子的最大能量。