High-current fast electron beam propagation in a dielectric target

Area of Science:

• Plasma Physics
• Laser-Plasma Interactions
• Computational Physics

Background:

• High-intensity lasers efficiently generate relativistic electron beams (REBs) with high current densities (>10^12 A cm⁻²).
• REB propagation in targets requires current neutralization, a poorly understood phenomenon, particularly in dielectric materials.

Purpose of the Study:

• To investigate the propagation dynamics of high current density electron beams in plastic targets.
• To understand the mechanisms of current neutralization and energy loss during REB propagation.

Main Methods:

• Utilized a particle-in-cell (PIC) simulation code incorporating ionization and electron collisions.
• Analyzed temporal evolution of beam velocity distribution and spatial density profile.
• Compared simulation results with a simplified analytical model.

Main Results:

• Achieved reasonable agreement between PIC simulations and the analytical model.
• Identified target ionization and return current as primary sources of beam energy loss.
• Observed a two-stream instability at high beam densities, contributing to energy dissipation.

Conclusions:

• The study provides insights into REB propagation in dielectric targets through PIC simulations.
• Ionization and instabilities play crucial roles in beam energy loss and propagation dynamics.
• The findings contribute to understanding high-current beam transport in laser-driven plasmas.