Multi-chord fiber-coupled interferometry of supersonic plasma jets and comparisons with synthetic data

摘要: 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 Bull. Amer. Phys. Soc. 56, 307 (2011)]. The long coherence length laser (>10 m) allows signal and reference path lengths be mismatched by many meters without degradation, making for a greatly simplified optical layout. Measured interferometry phase shifts are consistent with partially ionized in which an initially positive shift becomes negative when ionization fraction drops below certain threshold. In this case, both free electrons bound ions neutral atoms contribute index refraction. This paper illustrates how data, aided numerical modeling, derive total jet density, propagation velocity (~15-50 km/s), (~20-100 cm), 3D expansion.