Laser-Plasma Interactions Enabled by Emerging Technologies

An overview from the past and an outlook for the future of fundamental laser-plasma interactions research enabled by emerging laser systems

Cross-Scale Energy Transport in Space Plasmas

The solar wind is a supersonic magnetized plasma streaming far into the heliosphere. Although cooling as it flows, it is rapidly heated upon encountering planetary obstacles. At Earth, this interaction forms the magnetosphere and its sub-regions. The present paper focuses on particle heating across the boundary separating the shocked solar wind and magnetospheric plasma, which is driven by mechanisms operating on fluid, ion and electron scales. The cross-scale energy transport between these scales is a compelling and fundamental problem of plasma physics. Here, we present evidence of the energy transport between fluid and ion scales: free energy is provided in terms of a velocity shear generating fluid-scale Kelvin–Helmholtz instability. We show the unambiguous observation of an ion-scale magnetosonic wave packet, inside a Kelvin–Helmholtz vortex, with sufficient energy to account for observed ion heating. The present finding has universal consequences in understanding cross-scale energy transport, applicable to environments experiencing velocity shears during comparable plasma regimes

Numerical studies of dielectric material modifications by a femtosecond Bessel–Gauss laser beam

Femtosecond Bessel-Gauss beams are attractive tools to a large area of laser processes including high aspect ratio volume nanostructuration in dielectric materials. Understanding the dielectric material response to femtosecond Bessel-Gauss beam irradiation is key in controlling its modifications and designing new structures. In this work, we show how the material ionization affects the propagation of the femtosecond Bessel-Gauss laser beam and can limit the laser energy deposition. By performing 2D/3D numerical simulations, we evaluate the absorbed laser energy and subsequent material modifications. First, we model the electron dynamics in the material coupled to the 3D laser propagation effects. Then, we consider 2D thermoelasto-plastic simulations to characterize the medium modifications. Results show that the laser ionized matter induces a screening of the incident gaussian beams which form the Bessel-Gauss beam. This effect leads to a limitation of the maximum laser energy deposition even if the incident laser energy increases. It can be reduced if a tigthly focused femtosecond Bessel-Gauss beam is used as the angular aperture of the cone along which the incident gaussian beams are distributed is larger

Laser-Plasma Interactions Enabled by Emerging Technologies

An overview from the past and an outlook for the future of fundamental laser-plasma interactions research enabled by emerging laser systems