Multi-chord fiber-coupled interferometer with a long coherence length laser

Abstract

This paper describes a 561 nm laser heterodyne interferometer that provides time-resolved measurements of line-integrated plasma electron density within the range of 10^15-10^18 cm^(-2). Such plasmas are produced by railguns on the Plasma Liner Experiment (PLX), which aims to produce μs-, cm-, and Mbar-scale plasmas through the merging of thirty plasma jets in a spherically convergent geometry. A long coherence length, 320 mW laser allows for a strong, sub-fringe phase-shift signal without the need for closely-matched probe and reference path lengths. Thus only one reference path is required for all eight probe paths, and an individual probe chord can be altered without altering the reference or other probe path lengths. Fiber-optic decoupling of the probe chord optics on the vacuum chamber from the rest of the system allows the probe paths to be easily altered to focus on different spatial regions of the plasma. We demonstrate that sub-fringe resolution capability allows the interferometer to operate down to line-integrated densities of order 10^15 cm^(-2).

submitted to Rev. Sci. Instrum. (2011)

References in corpus (1)

• Heterodyne interferometer with unequal path lengths

Cited by in corpus (13)

• Experimental characterization of railgun-driven supersonic plasma jets motivated by high energy density physics applications
• Experimental characterization of the stagnation layer between two obliquely merging supersonic plasma jets
• Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets
• Experiment to Form and Characterize a Section of a Spherically Imploding Plasma Liner
• Laboratory plasma physics experiments using merging supersonic plasma jets
• Experimental characterization of a transition from collisionless to collisional interaction between head-on-merging supersonic plasma jets
• Experimental Measurements of Ion Heating in Collisional Plasma Shocks and Interpenetrating Supersonic Plasma Flows
• Experimental characterization of a section of a spherically imploding plasma liner formed by merging hypersonic plasma jets
• Multi-chord fiber-coupled interferometry of supersonic plasma jets and comparisons with synthetic data
• Observation of Rayleigh-Taylor-Instability Evolution in a Plasma with Magnetic and Viscous Effects
• Observation of Shock-Front Separation in Multi-Ion-Species Collisional Plasma Shocks
• Experimental Measurements of Ion Diffusion Coefficients and Heating in a Multi-Ion-Species Plasma Shock
• Experimental Study of Ion Heating in Obliquely Merging Hypersonic Plasma Jets