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Theses

Laser-driven strong magnetic fields and high discharge currents : measurements and applications to charged particle transport

Abstract : The problem of strong quasi-static magnetic field generation is a challenge in laser-plasma interaction physics. Proposed 30 years ago, the use of the laser-driven capacitor-coil scheme, which stands out for its compact design while not needing any additional pulsed power source besides the laser power, only recently demonstrated its potential.This thesis work aims at characterizing the underlying physics and at developing this scheme. We demonstrated the generation of strong quasi-static magnetic fields by laser (500 J, 1 ns-duration and ~10^17 W/cm^2 intensity) of several hundreds of Teslas and duration of 2-3 ns. The B-field space- and time-evolutions were characterized using three independent diagnostics: B-dot probes, Faraday rotation and proton-deflectometry). The characterization of the underlying physical processes involved also X-ray diagnostics of the laser-irradiated zone and optical shadowgraphy of the coil rod expansion.A novel application of externally applied magnetic fields to guide relativistic electron beam in dense matter has been carried out and the obtained results set the ground for improved high-energy-density transport in matter. Indeed, allowing sufficient time for the dense target magnetization, a factor 5 improvement of the electron energy-density flux at 50µm-depth was evidenced.Besides, the generation of high discharge currents consecutive to short laser pulse irradiation (50 J, <1 ps-duration and ~10^19 W/cm^2 intensity) was also pointed out. Proton imaging of the discharge permitted to measure the propagation of an electromagnetic wave at a velocity close to the speed of light. This wave, of ~40ps-duration, was used as an electromagnetic lens to focalize and energy-select a narrow energy range within a multi-MeV proton beam (up to 12 MeV) passing through the coil.All-above experimental measurements and application results were thoroughly compared to both computer simulations and analytic modeling.The applications of this thesis work in a near future will concern:- inertial confinement fusion, by guiding relativistic electron beams up to the dense core nuclear fuel, and by confining particles depositing their energy in it, or even those resulting from the fusion reactions;- laboratory planetology and astrophysics, by generating secondary sources of energetic particles and radiation to reach the warm-dense-matter state or by magnetizing plasmas to reproduce astrophysical phenomena in scaled experiments;- and finally, the control of charged particle beams in vacuum, useful in particular for the development of laser-driven sources for distant applications in science, industry or even medecine.
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https://tel.archives-ouvertes.fr/tel-01653837
Contributor : Abes Star :  Contact
Submitted on : Friday, June 8, 2018 - 11:30:08 AM
Last modification on : Tuesday, March 29, 2022 - 3:02:04 AM
Long-term archiving on: : Sunday, September 9, 2018 - 3:06:12 PM

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  • HAL Id : tel-01653837, version 3

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Mathieu Bailly-Grandvaux. Laser-driven strong magnetic fields and high discharge currents : measurements and applications to charged particle transport. High Energy Physics - Experiment [hep-ex]. Université de Bordeaux, 2017. English. ⟨NNT : 2017BORD0557⟩. ⟨tel-01653837v3⟩

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