title: Dual laser interferometer for plasma density measurements on large tokamaks.
abstract: A two-wavelength plasma density interferometer utilizing a CO(2) laser and an HeNe laser is described. The interferometer is being designed for use on Doublet III, a large noncircular cross-section tokamak. The use of the two wavelengths allows the distinction between fringe shifts due to plasma density and fringe shifts due to mirror vibrations. Plasma density fringe shifts of 1/10 of a fringe shift can be measured in the presence of mirror vibrations which cause several fringe shifts. A simple digital phase comparing electronic system is used.
authors.affiliation: General Atomic Company, San Diego, California 92138.
authors.forename: D R
authors.initials: DR
authors.lastname: Baker
authors.forename: S T
authors.initials: ST
authors.lastname: Lee