Use of fast scopes to enable Thomson scattering measurement in presence of fluctuating plasma light

The addition of inexpensive high-speed oscilloscopes has enabled higher Te Thomson scattering measurements on the Sustained Spheromak Physics Experiment. Along with signal correlation techniques, the scopes allow analyses based on the shape of the scattered laser pulse to discriminate against fluctuating background plasma light that often make gated-integrator measurements unreliable. A 1.4 J Nd:YAG laser at 1064 nm is the scattering source. Spatial locations are coupled by viewing optics and fibers to four-wavelength-channel filter polychrometers. Ratios between the channels determine Te while summations of the channels determine density. Typically, the channel that provides a scattered signal at higher Te is contaminated by fluctuating background light. Individual channels are correlated with either a modeled representation of the laser pulse or a noise-free scattered laser light signal to extract channel amplitudes