ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
The current density profile diagnostic system presently operating on the Texas Experimental Tokamak (TEXT) employs a cw dye laser system to induce fluorescence in a lithium beam injected into the discharge. Systematic effects due to the finite lifetime of the excited state and enhancement of the beam attenuation during laser excitation limit the application of this technique to plasma densities (approximately-less-than)1×1013 cm−3. Laser enhancement of beam attenuation results from the large collisional ionization cross sections of the excited Li 2P state compared to the 2S ground state. This effect is exploited in a new diagnostic scheme which uses the polarization modulation of the present technique, but monitors the enhanced attenuation as opposed to the fluorescence. Detailed modeling indicates that a collinear beams configuration, with a short pulse laser and time-of-flight signal analysis, will provide a measurement of the complete poloidal field profile on TEXT at plasma densities up to 3×1013 cm−3 with 16-ms averaging times.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1140164
