Radial structure of the constricted positive column: Modeling and experiment

Area of Science:

• Plasma Physics
• Atomic and Molecular Physics
• Computational Physics

Background:

• Glow discharges are crucial in various industrial applications.
• Understanding the transition between diffuse and constricted states is key to controlling plasma behavior.
• Radiation trapping significantly influences plasma parameters but is often simplified in models.

Purpose of the Study:

• To develop a detailed self-consistent model for argon positive column glow discharge.
• To investigate the transition between diffuse and constricted discharge states.
• To analyze the influence of radiation trapping on macroscopic discharge parameters.

Main Methods:

• A self-consistent model incorporating plasma chemistry, gas heating, and electron distribution functions.
• Direct solution of the Holstein-Biberman equation for accurate radiation trapping treatment.
• A novel method for solving boundary-value problems of particle and energy balance equations.
• Experimental validation using volt-ampere characteristics and spectroscopic measurements.

Main Results:

• The model accurately describes the diffuse-to-constricted discharge transition.
• Radiation trapping significantly impacts macroscopic parameters of the constricted positive column.
• The proposed solution method yields continuous Z- and S-shaped discharge characteristics, revealing hysteresis.
• Experimental data confirms the model's predictions regarding radiation trapping's role in excited state redistribution.

Conclusions:

• The developed model provides a comprehensive understanding of argon glow discharge.
• Accurate treatment of radiation trapping is essential for modeling constricted discharges.
• The method enables the study of hysteresis phenomena in discharge transitions.