Plasma Electron Density Measurements Using Phase-Sensitive FTIR Interferometry

This work investigates the use of low-temperature plasma as an adaptive medium for high-bandwidth aero-optic wavefront control. To better understand plasma's optical properties (refractive index), a new diagnostic technique has been developed to simultaneously measure the average plasma electron density and heavy particle density. The technique uses phase-sensitive Fourier transform infrared (FTIR) interferometry to measure the optical dispersion of plasma across a spectrum of far-infrared wavelengths. The plasma electron density and heavy particle density values are determined using a least-squares analysis. This presentation describes the experimental setup and preliminary data from the measurement system.