Electron density compression and oscillating effects on laser energy absorption in overdense plasma targets

Area of Science:

• Plasma Physics
• Laser-Plasma Interactions
• High-Intensity Physics

Background:

• Understanding laser energy absorption in plasmas is crucial for applications like inertial confinement fusion.
• Previous models often simplified plasma dynamics, neglecting key effects like electron density compression and surface oscillations.

Purpose of the Study:

• To develop an analytical model for laser energy absorption in overdense plasmas.
• To self-consistently include electron density profile compression and electron plasma surface oscillations.
• To investigate the influence of plasma collisions on absorption rates.

Main Methods:

• Development of an analytical model incorporating electron density compression and surface oscillations.
• Derivation of scaling laws for compression effects based on laser strength and initial density.
• Analysis of temporal variations in laser absorption due to boundary oscillations.
• Investigation of plasma collision effects on absorption for different laser polarizations.

Main Results:

• The model shows that electron density compression and plasma surface oscillations significantly influence laser energy absorption.
• A general scaling law for compression effects is derived.
• Periodic vibration of the laser absorption rate at ω or 2ω frequencies is observed due to surface oscillations for p- and s-polarized lasers, respectively.
• Increasing electron-ion collision frequency leads to a considerable rise in laser absorption for both polarizations.

Conclusions:

• The proposed analytical model provides a more comprehensive understanding of laser energy absorption in overdense plasmas.
• Electron density compression and surface oscillations are critical factors affecting absorption efficiency.
• Plasma collisions play a significant role in enhancing laser energy absorption, particularly at higher collision frequencies.