标题： 观测和解释由超快强太赫兹场引起的场发射饱和现象 显示英文标题

标题： Observation and Interpretation of Field Emission Saturation Induced by an Ultra-fast Intense Terahertz Field

摘要： 在超快强太赫兹场下的场发射为产生具有超短脉冲持续时间和高电荷密度的电子束提供了一种有前景的方法。 通常认为，根据传统场发射理论描述的场发射电流会随着施加的电场显著增加。 然而，我们使用不同能量水平和不同温度下的准单周期强场太赫兹辐射进行了广泛的场发射实验，并观察到一种引人注目的现象，即发射的电荷达到饱和。 提出了一种新模型来解释这一现象，该模型考虑了表面价电子的贡献以及体材料中自由电子向表面的动态补充。 实验观察到的发射电荷与太赫兹能量之间的凸形关系与模型预测一致，这与传统场发射公式得出的凹形关系不同。 此外，另一种观察到的反直觉现象，即阴极温度与饱和发射电荷之间的逆相关关系，也得到了模型的良好解释。 这项工作为超快强场下的场发射动力学提供了全面的见解，为产生具有前所未有时间分辨率的电子束铺平了道路。 显示英文摘要

摘要： Field emission under ultra-fast intense terahertz fields provides a promising approach for generating electron bunches with ultrashort pulse duration and high charge densities. It is generally believed that the field emission current described by traditional field emission theory increases dramatically with the applied electric field. However, we conducted extensive field emission experiments using quasi-single-cycle strong-field terahertz radiation at various energy levels and different temperatures and observed an intriguing phenomenon where the emitted charge reached saturation. A novel model is proposed to interpret this phenomenon, which considers the contribution of surface valence electrons and the dynamic replenishment of free electrons from the bulk to the surface. The experimentally observed convex relationship between the emitted charge and terahertz energy is consistent with the model prediction, unlike the concave relationship derived from the traditional field emission formula. In addition, another observed counter-intuitive phenomenon, the inverse correlation between the cathode temperature and saturated emission charge, is also well interpreted by the model. This work offers comprehensive insights into field emission dynamics under ultra-fast intense fields, paving the way for generating electron bunches with unprecedented temporal resolution.