arXiv subjects

Kevin Glize

Publications and source records attributed to Kevin Glize.

4 recordsLinked to original sources

arXiv2022

Measurement of Stimulated Raman Side-Scattering Predominance in Directly Driven Experiment

Due to its particular geometry, stimulated Raman side-scattering (SRSS) drives scattered light emission at non-conventional directions, leading to scarce and complex experimental observations. Direct-irradiation campaigns at the SG-II UP facility have measured the scattered light driven by SRSS over a wide range of angles. It indicated an emission at large polar angles over a broad azimuthal range, sensitive to the plasma profile and laser polarization, resulting in a loss of about 5\% of the total laser energy. Direct comparison with back-scattering measurement has evidenced SRSS as the dominant Raman scattering process. The predominance of SRSS was confirmed by 2D particle-in-cell simulations, and its angular spread has been corroborated by ray-tracing simulations. The main implication is that a complete characterization of the SRS instability and an accurate measurement of the energy losses require the collection of the scattered light in a broad range of directions. Otherwise, spatially limited measurement could lead to an underestimation of the energetic importance of stimulated Raman scattering.

physics.plasm-ph↗

arXiv2021

Measurement of magnetic cavitation driven by heat flow in a plasma

We describe the direct measurement of the expulsion of a magnetic field from a plasma driven by heat flow. Using a laser to heat a column of gas within an applied magnetic field, we isolate Nernst advection and show how it changes the field over a nanosecond timescale. Reconstruction of the magnetic field map from proton radiographs demonstrates that the field is advected by heat flow in advance of the plasma expansion. This changes the dynamics of high energy density plasmas, in which heat flows and fields are strongly coupled, and may disrupt magnetised inertial confinement fusion schemes.

physics.plasm-ph↗

arXiv2019

Orbital angular momentum coupling in elastic photon-photon scattering

In this letter, we investigate the effect of orbital angular momentum (OAM) on elastic photon-photon scattering in vacuum for the first time. We define exact solutions to the vacuum electro-magnetic wave equation which carry OAM. Using those, the expected coupling between three initialwaves is derived in the framework of an effective field theory based on the Euler-Heisenberg La-grangian and shows that OAM adds a signature to the generated photons thereby greatly improvingthe signal-to-noise ratio. This forms the basis for a proposed high-power laser experiment utilizingquantum optics techniques to filter the generated photons based on their OAM state

physics.optics↗

arXiv2019

Kinetic simulations of fusion ignition with hot-spot ablator mix

Inertial confinement fusion fuel suffers increased X-ray radiation losses when carbon from the capsule ablator mixes into the hot-spot. Here we present one and two-dimensional ion Vlasov-Fokker-Planck simulations that resolve hot-spot self heating in the presence of a localized spike of carbon mix, totalling 1.9% of the hot-spot mass. The mix region cools and contracts over tens of picoseconds, increasing its alpha particle stopping power and radiative losses. This makes a localized mix region more severe than an equal amount of uniformly distributed mix. There is also a purely kinetic effect that reduces fusion reactivity by several percent, since faster ions in the tail of the distribution are absorbed by the mix region. Radiative cooling and contraction of the spike induces fluid motion, causing neutron spectrum broadening. This artificially increases the inferred experimental ion temperatures and gives line of sight variations.

physics.plasm-ph↗