Expansion-Driven Self-Magnetization of High-Energy-Density Plasmas

Area of Science:

• Plasma Physics
• High-Energy-Density (HED) Science
• Astrophysical Plasma Dynamics

Background:

• Self-magnetization is a key challenge in laboratory and astrophysical plasmas, influencing plasma transport and evolution.
• Previous high-energy-density experiments observed ion-scale magnetic filaments, but their origin is debated.

Purpose of the Study:

• To investigate the origin of plasma self-magnetization in 2D collisional particle-in-cell (PIC) simulations.
• To understand the role of anisotropy-driven instabilities in magnetic field generation.
• To explore the impact of self-generated magnetic fields on plasma transport properties.

Main Methods:

• Conducted 2D collisional particle-in-cell (PIC) simulations with a laser ray-tracing module.
• Utilized planar geometry to suppress Biermann magnetic fields and focus on anisotropy-driven instabilities.
• Varied laser intensity between 10^13 and 10^14 W/cm^2, considering collisional effects relevant to HED and inertial fusion.

Main Results:

• Identified a critical laser intensity threshold for rapid plasma self-magnetization.
• Observed an expansion-driven Weibel process generating magnetic fields.
• Achieved plasma beta (β) of 100 and Hall parameter (ω_ceτ_e) > 1 within picoseconds.
• Demonstrated that generated magnetic fields significantly modify plasma heat transport.

Conclusions:

• Plasma self-magnetization occurs rapidly via an expansion-driven Weibel process above a critical laser intensity.
• The generated magnetic fields are strong enough to alter plasma heat transport, impacting plasma dynamics.
• These findings are crucial for understanding magnetic field generation in HED and inertial fusion experiments.