# Interplay between the Weibel instability and the Biermann battery in realistic laser-solid interactions

## TL;DR

This study uses particle-in-cell simulations to explore how the Weibel instability and Biermann battery mechanisms generate magnetic fields in laser-plasma interactions, revealing conditions where the Weibel instability dominates.

## Contribution

It introduces a novel experimental setup and simulation approach to observe the interplay of Weibel instability and Biermann battery in laser-driven collisionless plasmas, highlighting the dominance of Weibel-generated fields under specific conditions.

## Key findings

- Weibel instability can produce observable magnetic fields exceeding Biermann battery.
- The dominance of Weibel fields depends on the gradient scale length being larger than the electron inertial length.
- Tuning laser pulse timing can control the magnetic field generation mechanisms.

## Abstract

A novel setup allows the Weibel instability and its interplay with the Biermann battery to be probed in laser-driven collisionless plasmas. Ab initio particle-in-cell (PIC) simulations of the interaction of short ($ \le ps$) intense $(a_0 \ge 1)$ laser-pulses with overdense plasma targets show observable Weibel generated magnetic fields. This field strength surpasses that of the Biermann battery, usually dominant in experiments, as long as the gradient scale length is much larger than the local electron inertial length; this is achievable by carefully setting the appropriate gradients in the front of the target e.g. by tuning the delay between the main laser pulse and the pre-pulse.