Ionization induced plasma grating and its applications in strong-field ionization measurements
Ionization induced plasma grating and its applications in strong-field ionization measurements
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DOI：
10.1088/1361-6587/ac1751
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发表时间：
2021-06
影响因子：
2.2
通讯作者：
Chaojie Zhang;Z. Nie;Yipeng Wu;M. Sinclair;Chengkun Huang;K. Marsh;C. Joshi
中科院分区：
文献类型：
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作者：
Chaojie Zhang;Z. Nie;Yipeng Wu;M. Sinclair;Chengkun Huang;K. Marsh;C. Joshi
利用两束相互交叉的超短激光脉冲的干涉作用，使气体在空间上选择性电离，从而形成电离诱导等离子体光栅。等离子体光栅的密度调制可以接近统一，因为等离子体仅在两个脉冲相长干涉的地方产生，并且在相消干涉区域中不发生电离。一旦满足布拉格条件，这种大的密度调制导致第二超短探测脉冲的有效汤姆逊散射。通过测量散射效率，可以确定等离子体光栅中的绝对电子密度，从而推导出给定中性气体密度的电离度。在本文中，我们证明了这一概念的有用性，显示两个应用：电离度测量强场电离的原子和分子和极低密度气体射流的表征。前者的应用是特别感兴趣的稠密气体中的电离物理研究的电离电子与邻近的中性粒子的碰撞可能变得重要，有时被称为多体电离;和后者是有用的等离子体为基础的加速，需要极低密度等离子体。
An ionization induced plasma grating can be formed by spatially selective ionization of gases by the interference of two intersecting ultra-short laser pulses. The density modulation of a plasma grating can approach unity since the plasma is produced only where the two pulses constructively interfere and ionization does not occur in destructive interference regions. Such a large density modulation leads to efficient Thomson scattering of a second ultra-short probe pulse once the Bragg condition is satisfied. By measuring the scattering efficiency, it is possible to determine the absolute electron density in the plasma grating and thereby deduce the ionization degree for a given neutral gas density. In this paper, we demonstrate the usefulness of this concept by showing two applications: ionization degree measurement of strong-field ionization of atoms and molecules and characterization of extremely low-density gas jets. The former application is of particular interest for ionization physics studies in dense gases where the collision of the ionized electron with neighboring neutrals may become important-sometimes referred to as many-body ionization; and the latter is useful for plasma-based acceleration that requires extremely low-density plasmas.