CO/sub 2/ laser interferometer array for Big Dee
A 12 channel interferometer array is planned for obtaining electron density profiles on Big Dee. Each channel consists of coaxial CO/sub 2/ and HeNe laser beams. The reference beam is formed by splitting off half of the laser power at each wavelength by using acousto-optic modulators which introduce a 40-MHz frequency shift in the reference beam. The detected interference signals from room-temperature visible and IR detectors are mixed with the 40-MHz drive for the acousto-optic cells. The quadrature mixer signals result in phase information due to vibration and phase-velocity variation in the plasma. Simultaneous solution of the two equations describing the phase shift at the two wavelengths yields the phase shift due only to the plasma effects. The arithmetic operations will be performed digitally in real time by a dedicated microprocessor in each channel. The execution speed of the microprocessor is expected to be sufficient for measuring line integral density in the presence of vibrations of 1-mm amplitude at 1 Hz or 10-..mu..m amplitude at 100 Hz. Phase resolution for each channel is 2..pi../64 and time between samples is 25 ..mu..s. Density profiles are derived from chordal line integral density data by computer tomography.
- Research Organization:
- GA Technologies Incorporated, P. O. Box 85608, San Diego, California 92138
- OSTI ID:
- 5761330
- Journal Information:
- Rev. Sci. Instrum.; (United States), Vol. 56:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DOUBLET REACTORS
ELECTRON DENSITY
PLASMA DIAGNOSTICS
MICHELSON INTERFEROMETER
DESIGN
COMPUTERIZED TOMOGRAPHY
CARBON DIOXIDE
DEES
FAR INFRARED RADIATION
HELIUM-NEON LASERS
INTERFEROMETRY
PHASE SHIFT
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DIAGNOSTIC TECHNIQUES
ELECTRODES
ELECTROMAGNETIC RADIATION
GAS LASERS
INFRARED RADIATION
INTERFEROMETERS
LASERS
MEASURING INSTRUMENTS
OXIDES
OXYGEN COMPOUNDS
RADIATIONS
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
TOMOGRAPHY
700102* - Fusion Energy- Plasma Research- Diagnostics