Abstract

The current density profile (CDP) diagnostic system on the Texas Experimental Tokamak (TEXT) has been used to measure poloidal magnetic fields in the plasma using laser-induced fluorescence of a radially injected 100-keV lithium beam. A new method, based on laser enhanced attenuation of the injected Li beam and time-of-flight signal analysis, is being developed. To obtain the needed spatial and spectral resolution, the diagnostic requires a laser output at a wavelength of 667.1 nm, a bandwidth of <1 GHz, peak power of >20 W, and a pulse length of <10 ns at a 1-MHz rep rate. To achieve these requirements, an acoustooptic cavity dumper will be added to an existing symmetric z-shaped cw dye laser. The z-shaped cavity has previously demonstrated the required bandwidth and longitudinal mode structure, while a conventional cavity with a dumper has previously shown the required pulse length, rep rate, and peak power. This paper discusses details on the basic approach of the diagnostic measurement and presents details on the performance of the pulse laser system.

© 1988 Optical Society of America