Poloidal field measurements using laser enhanced attenuation of an energetic lithium beam

Conference · Mon Feb 01 04:00:00 EST 1988

OSTI ID:5256918

West, W P; Thomas, D M; Thomas, M P

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 )approxreverse arrowlt) 1 )times) 10/sup 13/ cm/sup )minus/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 )times) 10/sup 13/ cm/sup )minus/3) with 16 ms averaging times.

• Research Organization: General Atomics Co., San Diego, CA (USA)
• DOE Contract Number: AC03-84ER53158
• OSTI ID: 5256918
• Report Number(s): GA-A-19217; CONF-880364-18; ON: DE88008360
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102* -- Fusion Energy-- Plasma Research-- Diagnostics
ATTENUATION
CLOSED PLASMA DEVICES
CROSS SECTIONS
DYE LASERS
FLUORESCENCE
IONIZATION
LASERS
LIQUID LASERS
LUMINESCENCE
MAGNETIC FIELDS
MEASURING METHODS
PERFORMANCE
PLASMA DENSITY
PLASMA DIAGNOSTICS
SIGNAL-TO-NOISE RATIO
TEXT DEVICES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES