Fast electron transport dynamics and energy deposition in magnetized, imploded cylindrical plasma

Abstract

Inertial confinement fusion approaches involve the creation of high-energy-density states through compression. High gain scenarios may be enabled by the beneficial heating from fast electrons produced with an intense laser and by energy containment with a high-strength magnetic field. Here, we report experimental measurements from a configuration integrating a magnetized, imploded cylindrical plasma and intense laser-driven electrons as well as multi-stage simulations that show fast electrons transport pathways at different times during the implosion and quantify their energy deposition contribution. The experiment consisted of a CH foam cylinder, inside an external coaxial magnetic field of 5 T, that was imploded using 36 OMEGA laser beams. Two-dimensional (2D) hydrodynamic modelling predicts the CH density reaches 9.0 g cm − 3 , the temperature reaches 920 eV and the external B-field is amplified at maximum compression to 580 T. At pre-determined times during the compression, the intense OMEGA EP laser irradiated one end of the cylinder to accelerate relativistic electrons into the dense imploded plasma providing additional heating. The relativistic electron beam generation was simulated using a 2D particle-in-cell (PIC) code. Finally, three-dimensional hybrid-PIC simulations calculated the electron propagation and energy deposition inside the target and revealed the roles the compressed and self-generated B-fields play in transport. During a time window before the maximum compression time, the self-generated B-field on the compression front confines the injected electrons inside the target, increasing the temperature through Joule heating. For a stronger B-field seed of 20 T, the electrons are predicted to be guided into the compressed target and provide additional collisional heating. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.

Prospects for high gain inertial fusion energy: an introduction to the second edition

“…Beg et al . 's article ‘Fast electron transport dynamics and energy deposition in magnetized, imploded cylindrical plasma’ [27] provides benchmarking simulations and experiments using the OMEGA EP facility at the University of Rochester on the energy transport in cylindrical plasmas. The advantage of this geometry is the transverse access to the plasma to interrogate the plasma conditions.…”

Computational study of laser-produced plasma, EUV generation, and the impact of magnetic fields

“…The advancement of high-power lasers has spurred interest in investigating magnetic field effects on laser-driven plasma, given its strong connections to the research fields of photonics, 1 inertial confinement fusion, 2,3 and particle physics in plasmas. 4 Especially, it provides proper conditions to conduct laboratory astrophysical research, [5][6][7] enabling a better understanding of the stability, dynamics, and heating of plasma flows in the presence of magnetic fields, which are ubiquitous throughout the universe.…”