A high performance laser-excited interferometer for measuring electron densities

Significant improvements in several aspects of laser-excited interferometer design have been included in this instrument. The device utilizes plasma-limiting quartz tubes, and a concentric resonator design, to greatly simplify interferometry in the presence of transverse gradients of refractive index, and improve beam overlap. The techniques of fractional fringe shift interferometry in the time domain are incorporated, and provide order-of-magnitude improvements in sensitivity (∫N[sub e] dℓ ≳ 5 x 10¹⁵ cm⁻²) and temporal resolution (Δτ ~ ±25 nsec.). Electronic circuitry provides a direct, continuous readout of electron density. Measurements have been made on a z-pinch discharge which are impossible in any other way, confirming the usefulness of the discharge as a spectroscopic source, and revealing details of the pinch mechanism.Science, Faculty ofPhysics and Astronomy, Department ofGraduat