Betatron radiation emitted during the direct laser acceleration of electrons in underdense plasmas

Fuente: arXiv
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Autori principali: Babjak, Robert, Vranic, Marija
Natura: Preprint
Pubblicazione: 2025
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author Babjak, Robert
Vranic, Marija
author_facet Babjak, Robert
Vranic, Marija
contents Relativistic laser pulses can accelerate electrons up to energies of several GeV during the interaction with gaseous targets through the direct laser acceleration (DLA) mechanism. While the electrons are accelerated to high energies, they oscillate transversely to the laser propagation direction, emitting radiation. We demonstrate using particle-in-cell (PIC) simulations that the high accelerated electron charge enables DLA sources to emit $\sim 10^{10}~\rm{photons}/0.1\%\rm{BW}$ at energies of hundreds MeV when interacting with multi-petawatt laser pulses. We provide an analytical estimate of the expected critical frequency for the DLA betatron spectrum which is in strong agreement with PIC simulations. We also show that using gas jets of low density ($\sim 10^{19}~\rm{cm^{-3}}$) is beneficial for the brightness of the source, since low plasma density produces collimated radiation. If the laser pulse is focused to an optimal spot size that results in the highest cut-off energies, conversion efficiency from laser to radiation can reach up to a few percent, which makes the DLA a promising high-brilliance source of gamma-ray radiation.
format Preprint
id arxiv_https___arxiv_org_abs_2502_06744
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Betatron radiation emitted during the direct laser acceleration of electrons in underdense plasmas
Babjak, Robert
Vranic, Marija
Plasma Physics
Relativistic laser pulses can accelerate electrons up to energies of several GeV during the interaction with gaseous targets through the direct laser acceleration (DLA) mechanism. While the electrons are accelerated to high energies, they oscillate transversely to the laser propagation direction, emitting radiation. We demonstrate using particle-in-cell (PIC) simulations that the high accelerated electron charge enables DLA sources to emit $\sim 10^{10}~\rm{photons}/0.1\%\rm{BW}$ at energies of hundreds MeV when interacting with multi-petawatt laser pulses. We provide an analytical estimate of the expected critical frequency for the DLA betatron spectrum which is in strong agreement with PIC simulations. We also show that using gas jets of low density ($\sim 10^{19}~\rm{cm^{-3}}$) is beneficial for the brightness of the source, since low plasma density produces collimated radiation. If the laser pulse is focused to an optimal spot size that results in the highest cut-off energies, conversion efficiency from laser to radiation can reach up to a few percent, which makes the DLA a promising high-brilliance source of gamma-ray radiation.
title Betatron radiation emitted during the direct laser acceleration of electrons in underdense plasmas
topic Plasma Physics
url https://arxiv.org/abs/2502.06744