Physics of Giant ElectroMagnetic Pulse generation in short pulse laser experiments

TL;DR

This paper investigates the physical mechanisms behind the generation of Giant Electromagnetic Pulses (GEMP) during high-power laser experiments, linking experimental measurements with a model to predict GEMP characteristics.

Contribution

It provides a new physical model for calculating target charge and GEMP emission based on experimental data and target geometry, enhancing understanding of GEMP generation.

Findings

Correlation between neutralization current and electromagnetic emission established

A simple model for target charge estimation is proposed

Method to predict GEMP intensity and frequencies at different facilities

Abstract

In this paper we describe the physical processes that lead to the generation of Giant Electro- Magnetic Pulses (GEMP) on powerful laser facilities. Our study is based on experimental mea- surements of both the charging of a solid target irradiated by an ultra-short, ultra-intense laser and the detection of the electromagnetic emission in the GHz domain. An unambiguous correlation between the neutralisation current in the target holder and the electromagnetic emission shows that the source of the GEMP is the remaining positive charge inside the target after the escape of fast electrons accelerated by the ultra-intense laser. A simple model for calculating this charge in the thick target case is presented. From this model and knowing the geometry of the target holder, it becomes possible to estimate the intensity and the dominant frequencies of the GEMP on any facility.