A computational model for nanosecond pulse laser-plasma interactions

JOURNAL OF COMPUTATIONAL PHYSICS

卷:406

Article

Munafo, Alessandro^1,2,3  Alberti, Andrea^1,3  Pantano, Carlos^1,4,5  Freund, Jonathan B.^1,2,3,4  Panesi, Marco^1,3 

[1] Univ Illinois, Ctr Exascale Simulat Plasma Coupled Combust XPACC, Urbana, IL 61801 USA

[2] Coordinated Sci Lab, 1308 W Main St, Urbana, IL 61801 USA

[3] Talbot Lab, Dept Aerosp Engn, 104 S Wright St, Urbana, IL 61801 USA

[4] Mech Engn Lab, Dept Mech Engn & Sci, 105 S Mathews Ave, Urbana, IL 61801 USA

[5] Univ Southern Calif, Dept Aerosp & Mech Engn, Los Angeles, CA 90089 USA

关键词: Laser-plasma interactions;    IMEX methods;    Operator splitting;    Radiation transport;    Non-equilibrium gas dynamics;    Multi-photon ionization;   

DOI  :  10.1016/j.jcp.2019.109190

来源: Elsevier

【 摘 要 】

A multi-physics numerical model for laser-induced optical breakdown and laser-plasma interaction in a non-equilibrium gas is presented, accounting for: production of priming electrons via multi-photon ionization, energy absorption, cascade ionization, induced hydrodynamic response, and shock formation and propagation. The gas is governed by the Navier-Stokes equations, with non-equilibrium effects taken into account by means of a two-temperature model. The space-time dependence of the laser beam is modeled with a flux-tube formulation for the Radiative Transfer Equation. The flow governing equations are discretized in space using a second-order finite volume method. The semi-discrete equations are marched in time using an implicit-explicit (IMEX) dual time-stepping strategy, where diffusion and chemistry are solved implicitly, whereas convection is explicit. Application to a 20 ns long 50 mJ pulse laser-induced breakdown in quiescent O-2 shows the advantages of this temporal discretization during and just after the laser pulse, while a less-expensive symmetric Strang splitting (with implicit chemistry) is sufficient for the post-breakdown gas dynamics after similar or equal to 0.1 mu s. The integrated model is shown to reproduce key features of corresponding experiments. (C) 2019 Elsevier Inc. All rights reserved.

【 授权许可】

Free