Measuring electron density and electromagnetic fields in low-density laser-driven plasmas using proton radiography
Abstract
In this paper, we describe a novel technique for inferring electron density in laser plasmas from proton-radiography data. Proton radiography is primarily a diagnostic for imaging electromagnetic field structures in such plasmas. In the presence of strong field gradients, `caustic' features arise and are broadened by the process of collisional scattering between the imaging protons and the plasma. This effect has a well defined density dependence, allowing for a robust measurement of electron number density. We validate the method on data from the turbulent-dynamo experiments performed at the Omega laser facility (with electron densities in the range of ∼1020 cm−3), achieving good agreement with values obtained from Thomson scattering, x-ray imaging and simulations. This research enables one of the most robust techniques for measuring electromagnetic fields on laser-plasma experiments to simultaneously provide density measurements along the same line of sight, improving our ability to diagnose such plasmas.
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BibTeX
@misc{chu2026measuring,
title = {{Measuring electron density and electromagnetic fields in low-density laser-driven plasmas using proton radiography}},
author = {Joshua T. Y. Chu and Gianluca Gregori and Petros Tzeferacos and Archie F. A. Bott},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.22605},
eprint = {2610.22605},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.22605},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Measuring electron density and electromagnetic fields in low-density laser-driven plasmas using proton radiography
AU - Joshua T. Y. Chu
AU - Gianluca Gregori
AU - Petros Tzeferacos
AU - Archie F. A. Bott
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.22605
UR - https://arxiv.org/abs/2610.22605
AB - In this paper, we describe a novel technique for inferring electron density in laser plasmas from proton-radiography data. Proton radiography is primarily a diagnostic for imaging electromagnetic field structures in such plasmas. In the presence of strong field gradients, `caustic' features arise and are broadened by the process of collisional scattering between the imaging protons and the plasma. This effect has a well defined density dependence, allowing for a robust measurement of electron number density. We validate the method on data from the turbulent-dynamo experiments performed at the Omega laser facility (with electron densities in the range of ∼10^20 cm^−3), achieving good agreement with values obtained from Thomson scattering, x-ray imaging and simulations. This research enables one of the most robust techniques for measuring electromagnetic fields on laser-plasma experiments to simultaneously provide density measurements along the same line of sight, improving our ability to diagnose such plasmas.
ER -