Anisotropic electron-distribution function in inverse-bremsstrahlung-heated plasmas.

Area of Science:

• Plasma Physics
• Laser-Plasma Interactions
• Kinetic Theory

Background:

• Homogeneous plasmas are often heated by high-frequency laser fields.
• Understanding electron behavior is crucial for plasma dynamics.
• Existing models are limited to weak laser intensities.

Purpose of the Study:

• To calculate the electron-distribution function in velocity space for plasmas heated by high-frequency laser fields.
• To extend kinetic models to moderate laser intensities (α < 0.5).
• To analyze the impact of laser intensity on electron anisotropy.

Main Methods:

• Solving the Vlasov-Landau equation using Legendre polynomial expansion.
• Employing the laser field dipole approximation.
• Numerical solution of an infinite set of equations for distribution function components.

Main Results:

• The kinetic model is valid for moderate laser intensities (α < 0.5).
• The electron-distribution function shows significant anisotropy.
• The maximum of the second anisotropy component (f2) increases by approximately 48 times from weak (α < 0.01) to moderate (α = 0.5) laser intensities.

Conclusions:

• The study provides an improved calculation of the electron-distribution function for moderate laser intensities.
• The findings enhance understanding of electron behavior in laser-driven plasmas.
• Results have implications for radiation pressure, instabilities, and photoabsorption.