Insights from Keldysh theory to plasma electron density in liquid water under excitation wavelength scaling

Abstract

The study of plasma generation in liquids is relevant for many applications, especially for increasing the efficiency of terahertz radiation generation. This work investigates the relationship between the laser excitation wavelength and the plasma electron density in liquid water in the near-infrared spectral range. Using numerical simulation methods based on the Keldysh theory, patterns of changes in the ionization rate and changes in the plasma electron density depending on the excitation wavelength are analyzed. The results show the mutual influence of above-threshold ionization and tunneling effects when the Keldysh parameter is close to one. A decrease in plasma electron density with increasing excitation wavelength has been shown. However, in certain wavelength ranges a local increase in plasma electron density was observed. The theoretical results obtained are consistent with the experimental data of other scientific groups. This theoretical study provides valuable information on the modulation of plasma electron density by changing laser excitation wavelengths, which is important for increasing the efficiency of terahertz radiation generation.

Keywords

• plasma
• keldysh theory
• ionization
• liquid
• wavelength
• plasma-based thz generation
• plasma electron density