Theoretical aspect of enhancement and saturation in emission from laser produced plasma

TL;DR

This paper introduces a simplified theoretical model to analyze emission saturation and enhancement in laser-produced plasma, emphasizing plasma density, temperature, and confinement effects on emission behavior.

Contribution

The paper presents a new theoretical model linking plasma emission to density, temperature, and confinement, clarifying saturation thresholds and emission enhancement mechanisms.

Findings

Plasma emission is proportional to density squared, volume, and laser absorption fraction.

Saturation occurs when electron collision frequency exceeds 10^13 Hz.

Confinement and reduced expansion velocity significantly enhance plasma emission.

Abstract

This paper presents a simplified theoretical model for the study of emission from laser produced plasma to better understand the processes and the factors involved in the onset of saturation in plasma emission as well as in increasing emission due to plasma confinement. This model considers that plasma emission is directly proportional to the square of plasma density, its volume and the fraction of laser pulse absorbed through inverse Bremsstrahlung in the pre-formed plasma plume produced by the initial part of the laser. This shows that plasma density and temperature decide the threshold for saturation in emission, which occurs for electron ion collision frequency more than 10E13 Hz, beyond which plasma shielding effects become dominant. Any decrease in plasma sound (expansion) velocity shows drastic enhancement in emission supporting the results obtained by magnetic as well as spatial confinement of laser produced plasma. The temporal evolution of plasma emission in the absence and presence of plasma confinement along with the effect of laser pulse duration are also discussed in the light of this model.