Radiation Reaction Cooling as a Source of Anisotropic Momentum Distributions with Inverted Populations

Area of Science:

• Plasma physics
• Astrophysics
• High-energy physics

Background:

• Collisionless plasmas under strong electromagnetic fields exhibit anisotropic momentum distributions.
• Radiation reaction is a crucial factor influencing plasma behavior in extreme conditions.
• Population inversion is a characteristic feature of these anisotropic distributions.

Purpose of the Study:

• To investigate the development of ring momentum distributions in plasmas subjected to strong magnetic fields and radiation reaction.
• To derive the timescales associated with the formation of these ring distributions.
• To confirm analytical predictions using advanced simulation techniques.

Main Methods:

• Theoretical analysis of plasma dynamics in strong electromagnetic fields with radiation reaction.
• Derivation of analytical expressions for ring momentum distribution properties and formation timescales.
• Validation through particle-in-cell (PIC) simulations.

Main Results:

• Demonstrated the formation of ring momentum distributions in magnetized plasmas under radiation reaction.
• Derived analytical expressions for the timescales of ring formation.
• PIC simulations confirmed the analytical results for ring properties and formation timescales.

Conclusions:

• Plasma in strong magnetic fields with radiation reaction develops unstable ring momentum distributions.
• These distributions are crucial for understanding coherent radiation emission in astrophysical and laboratory plasmas.
• The findings provide a theoretical and computational basis for studying plasma instabilities and radiation processes.