Plasma Physics (physics.plasm-ph)

Abstract: Liquid leaf targets show promise as high repetition rate targets for laser-based ion acceleration using the Target Normal Sheath Acceleration (TNSA) mechanism and are currently under development. In this work, we discuss the effects of different ion species and investigate how they can be leveraged for use as a possible laser-driven neutron source. To aid in this research, we develop a surrogate model for liquid leaf target laser-ion acceleration experiments, based on artificial neural networks. The model is trained using data from Particle-In-Cell (PIC) simulations. The fast inference speed of our deep learning model allows us to optimize experimental parameters for maximum ion energy and laser-energy conversion efficiency. An analysis of parameter influence on our model output, using Sobol and PAWN indices, provides deeper insights into the laser-plasma system.

Abstract: Recently laser induced fusion with simultaneous volume ignition, a spin-off from relativistic heavy ion collisions, was proposed, where implanted nano antennas regulated and amplified the light absorption in the fusion target. Studies of resilience of the nano antennas were published recently in vacuum and in UDMA-TEGDMA medium. These studies concluded that the lifetime of the plasmonic effect is longer in medium, however, less energy was observed in the UDMA-TEGDMA copolymer, due to the smaller resonant size of gold nanoantenna than in case of Vacuum. Here we show how the plasmonic effect behaves in an environment fully capable of ionization, surrounded by Hydrogen atoms close to liquid densities. We performed numerical simulations treating the electrons of gold in the conduction band as strongly coupled plasma. The results show that the protons close to the nanorod's surface follow the collectively moving electrons rather than the incoming electric field of the light. The results also show that the plasmonic accelerating effect is also dependent on the laser intensity.

Abstract: Models for polarization drag - mechanical analog of the Faraday effect - are extended to include inertial corrections to the dielectrics properties of the rotating medium in its rest-frame. Instead of the Coriolis-Faraday term originally proposed by Baranova & Zel'dovich, inertia corrections due to the fictitious Coriolis and centrifugal forces are here derived by considering the effect of rotation on both the Lorentz and plasma dielectric models. These modified rest-frame properties are subsequently used to deduce laboratory properties. Although elegant and insightful, it is shown that the Coriolis-Faraday correction inferred from Larmor's theorem is limited in that it can only capture inertial corrections to polarization drag when the equivalent Faraday rotation is defined at the wave frequency of interest. This is notably not the case for low frequency polarization drag in a rotating magnetized plasma, although it is verified here using the more general phenomenological models that the impact of fictitious forces is in general negligible in these conditions.