Hydrogen cyanide laser interferometer of the JFT-2M tokamak and feedback stabilization of the beat frequency using a microcomputer

Journal Article · Tue Jul 01 00:00:00 EDT 1986 · Rev. Sci. Instrum.; (United States)

DOI:https://doi.org/10.1063/1.1138590· OSTI ID:5695411

Uesugi, Y; Matoba, T; Ochiai, I; Mizuno, K

A hydrogen cyanide laser interferometer with three vertical chords was installed in the JFT-2M tokamak for electron density measurement. The optical arrangment of the interferometer is a Mach--Zehnder type and its structure is mechanically independent of the JFT-2M machine in order to suppress the mechanical vibration. Two HCN lasers are employed for direct reading of the chord averaged electron density by means of beat modulation method. The beat frequency between two HCN lasers is stabilized at a constant frequency by a feedback circuit using a microcomputer. A combination of short dielectric waveguides and TPX lenses is employed to compensate the refraction and divergence of the laser beam. It was shown experimentally that the interferometric measurement of the electron density was scarcely affected by the mechanical vibration of the interferometer and the refraction of the probing laser beam up to n-bar/sub e/ = 6 x 10/sup 19/ m/sup -3/.

• Research Organization: Japan Atomic Energy Research Institute, Tokai-Mura, Naka-Gun, Ibaraki, Japan
• OSTI ID: 5695411
• Journal Information: Rev. Sci. Instrum.; (United States), Vol. 57:7
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
JET TOKAMAK
PLASMA DIAGNOSTICS
MACH-ZEHNDER INTERFEROMETER
OPERATION
DESIGN
ELECTRON DENSITY
GAS LASERS
HYDROCYANIC ACID
WAVEGUIDES
CYANIDES
HYDROGEN COMPOUNDS
INORGANIC ACIDS
INTERFEROMETERS
LASERS
MEASURING INSTRUMENTS
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
440300* - Miscellaneous Instruments- (-1989)
700102 - Fusion Energy- Plasma Research- Diagnostics