9 research outputs found
A Discontinuous Galerkin Method for Ideal Two-Fluid Plasma Equations
A discontinuous Galerkin method for the ideal 5 moment two-fluid plasma
system is presented. The method uses a second or third order discontinuous
Galerkin spatial discretization and a third order TVD Runge-Kutta time stepping
scheme. The method is benchmarked against an analytic solution of a dispersive
electron acoustic square pulse as well as the two-fluid electromagnetic shock
and existing numerical solutions to the GEM challenge magnetic reconnection
problem. The algorithm can be generalized to arbitrary geometries and three
dimensions. An approach to maintaining small gauge errors based on error
propagation is suggested.Comment: 40 pages, 18 figures
Multi-chord fiber-coupled interferometry of supersonic plasma jets and comparisons with synthetic data
A multi-chord fiber-coupled interferometer [Merritt et al., Rev. Sci.
Instrum. 83, 033506 (2012)] is being used to make time-resolved density
measurements of supersonic argon plasma jets on the Plasma Liner Experiment
[Hsu et al., Bull. Amer. Phys. Soc. 56, 307 (2011)]. The long coherence length
of the laser (>10 m) allows signal and reference path lengths to be mismatched
by many meters without signal degradation, making for a greatly simplified
optical layout. Measured interferometry phase shifts are consistent with a
partially ionized plasma in which an initially positive phase shift becomes
negative when the ionization fraction drops below a certain threshold. In this
case, both free electrons and bound electrons in ions and neutral atoms
contribute to the index of refraction. This paper illustrates how the
interferometry data, aided by numerical modeling, are used to derive total jet
density, jet propagation velocity (~15-50 km/s), jet length (~20-100 cm), and
3D expansion.Comment: 6 pages, 4 figures, invited paper at the 19th High Temperature Plasma
Diagnostics Conference, Monterey, CA, May 6--10, 201