Plasma perturbation induced by laser photodetachment

Area of Science:

• Plasma Physics
• Laser-Plasma Interactions
• Atomic and Molecular Physics

Background:

• Laser photodetachment is a key process in various plasma applications.
• Understanding plasma dynamics under laser influence is crucial for controlling plasma behavior.
• Existing models may not fully capture the complex interactions involving multiple charged species.

Purpose of the Study:

• To theoretically and experimentally investigate plasma dynamics initiated by laser photodetachment.
• To extend and apply a hybrid fluid-kinetic model for analyzing laser-perturbed plasma densities.
• To validate the model by comparing its predictions with experimental measurements.

Main Methods:

• Utilizing a hybrid fluid-kinetic model treating positive ions and electrons as fluids and negative ions ballistically.
• Applying the extended model to analyze perturbed densities in laser photodetachment experiments.
• Employing Langmuir probes for in-situ measurements of electron densities inside and outside the laser beam.

Main Results:

• The hybrid fluid-kinetic model demonstrates good agreement with experimental data for perturbed electron densities.
• The model accurately captures the time evolution and spatial distribution of electron density perturbations.
• Analysis of electron current overshoots yielded positive ion temperatures of 0.1-0.25 eV and electron temperatures of 0.3-3.2 eV.

Conclusions:

• The extended hybrid fluid-kinetic model is a valid tool for studying laser photodetachment plasma dynamics.
• The model's inclusion of positive ion perturbation is essential for accurate predictions.
• Experimental validation confirms the model's capability to describe perturbed electron densities and infer plasma temperatures.