标题： 强场双电离：“拐点”之下是什么？ 显示英文标题

标题： Strong field double ionization: What is under the "knee"?

摘要： 无论是不相关的（“顺序”）过程还是相关的（“非顺序”）过程都会对强激光脉冲中氦原子的双电离产生贡献。 双电离概率随脉冲强度变化呈现出一种特征性的“膝部”形状。 我们研究了该系统的相空间动力学，特别是通过寻找调控电离过程的动力学结构。 所呈现的图景通过明确再碰撞电子和核心电子的不同作用，补充了再碰撞情景。 我们的分析得出了可验证的预测，即在哪些强度下电离会发生定性变化，从而导致标志性的“膝部”形状。 显示英文摘要

摘要： Both uncorrelated ("sequential") and correlated ("nonsequential") processes contribute to the double ionization of the helium atom in strong laser pulses. The double ionization probability has a characteristic "knee" shape as a function of the intensity of the pulse. We investigate the phase-space dynamics of this system, specifically by finding the dynamical structures that regulate the ionization processes. The emerging picture complements the recollision scenario by clarifying the distinct roles played by the recolliding and core electrons. Our analysis leads to verifiable predictions of the intensities where qualitiative changes in ionization occur, leading to the hallmark "knee" shape.