A scheme to infer the temporal coherence of EUV frequency combs generated from intra-cavity high-order harmonic generation is put forward. The excitation dynamics of highly charged Mg-like ions, interacting with EUV pulse trains featuring different carrier-envelope-phase fluctuations, are simulated. While demonstrating the microscopic origin of the macroscopic equivalence between excitations induced by pulse trains and continuous-wave lasers, we show that the coherence time of the pulse train can be determined from the spectrum of the excitations. The scheme will provide a verification of the comb temporal coherence at time scales several orders of magnitude longer than current state of the art, and at the same time will enable high-precision spectroscopy of EUV transitions with a relative accuracy up to $\delta \omega /\omega \sim {10}^{-17}$.

中文翻译：

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用高电荷离子询问EUV频率梳的时间相干性

提出了一种推断腔内高次谐波产生的EUV频率梳的时间相干性的方案。模拟了高电荷类Mg离子与具有不同载流子-包络相波动的EUV脉冲序列相互作用的激发动力学。在论证脉冲串和连续波激光器引起的激发之间的宏观等效性的微观起源时，我们表明，可以从激发光谱中确定脉冲串的相干时间。该方案将在比当前最新技术水平长几个数量级的时间尺度上验证梳状时间相干性，同时将使EUV跃迁的高精度光谱分析的相对精度达到$\delta \omega /\omega 〜{10}^{-17}$。