SPATIAL-RESOLUTION OF FIR SCATTERING MEASUREMENTS ON TEXT

A multichannel, heterodyne, far-infrared laser scattering system is employed on TEXT to determine the spectral and spatial properties of electron density fluctuations. The spatial resolution of this system is demonstrated by utilizing a perturbation to the plasma potential profile induced by an applied resonant field. The perturbation changes the sign of the radial electric field over a certain region of the plasma. Shifts in the density fluctuation frequency spectra can be associated with changes in the radial electric field allowing one to unambiguously resolve fluctuations in the plasma interior and edge.