Plasma physics is the branch of physics concerned with matter in its plasma phase. NMC participates in modeling plasma dynamics and various plasma physics simulations. Research at NMC includes the propogation of laser beams in plasma and the subsequent issues of beam control. NMC also conducts research on collisionless plasma models and computational and theoretical studies of ultra-cold plasmas.
Instability and Transport of Laser Beams in Plasma
Propagation of intense laser beams in plasma raises technological and scientific issues. Applications require precise beam control while propagation in large-scale plasma may be unstable. These instabilities strongly amplify thermal fluctuations, scattering laser beam power away from target. In particular, Stimulated Brillouin scattering (SBS) sends laser beam power back to the laser which, in addition to depriving the target of full laser power, may also damage laser optic. Our SBS simulations reveal an unexpected richness of behavior. Instability causes a phase difference between laser and SBS light, δθ, figure 1, and spatial localization of backscattered light, figure 2. Funding for this project comes from the Department of Energy.
Figure 1 Figure 2
Vlasov Multi-Dimensional Simulation of Langmuir Wave Collapse and Stimulated Raman Scatter in the Fluid-Kinetic Transition Regime
Our hybrid kinetic-fluid model is a collisionless plasma model whose solutions are exact solutions to the Vlasov equation. It is useful in regimes with directed propagation of plasma waves, e.g., as generated by laser-plasma-interaction. We have found quantitative agreement with results from standard methods of solution (Particle in Cell and direct two-dimensional (2D) Vlasov simulation) for long time evolution of large amplitude plasma waves. Our model offers huge economies of computation compared to standard methods, enabling one to simulate multi-D collisionless plasma dynamics with desktop computational resources. We anticipate resolution of the ponderomotive-kinetic transition of Langmuir wave filamentation and collapse in regimes relevant to stimulated Raman scatter. Funding for this project comes from the National Science Foundation.
Computational and Theoretical Studies of Ultra-cold Plasmas: Exploring the Physics of Strongly Coupled Plasmas with Large Scale Simulations
Michael Murillo, NMC Affiliate Researcher, LANL Staff Scientist
This research aims to greatly expand our knowledge of strongly coupled plasmas in three key areas: the approach to equilibrium, the edge of the hydrodynamic limit, and particle and energy transport. Most efforts will focus on how these advances can exploit the achievement of ultracold, quasi-neutral plasmas in experiments. In particular, this research will examine concepts that could lead to the development of more strongly coupled plasmas in experiments, which are currently limited to the moderately coupled plasma regime. Funding for this project comes from the Air Force Office of Scientific Research.