Application of FIR heterodyne detection to collective scattering measurements of tokamak microturbulence

Journal Article · Mon Aug 01 04:00:00 EDT 1988 · Rev. Sci. Instrum.; (United States)

DOI:https://doi.org/10.1063/1.1140196· OSTI ID:6906374

Brower, D L; Peebles, W A; Kim, S K; Luhmann, Jr, N C

Multichannel collective scattering of far-infrared (FIR) laser radiation is employed on the TEXT tokamak to investigate small-scale turbulent density fluctuations. A twin-frequency optically pumped FIR laser operating at 1222 ..mu..m (approx. =20 mW) and a difference frequency ..delta omega../sub IF//2..pi..approx. =1 MHz is used for the source and local oscillator beams. This permits heterodyne detection of the frequency-shifted scattered radiation which is necessary to determine wave propagation direction of plasma density fluctuations. The need for heterodyne versus homodyne detection is demonstrated. Such a diagnostic capability has allowed preliminary identification of the ion pressure-gradient-driven instability (whose most notable signature is that of turbulent fluctuations propagating in the ion diamagnetic drift direction) which is potentially responsible for saturation of the global energy confinement time with increasing density in tokamak plasmas.

• Research Organization: Institute of Plasma and Fusion Research, University of California, Los Angeles, California 90024 TEXT Group, Fusion Research Center, University of Texas, Austin, Texas 78712
• OSTI ID: 6906374
• Journal Information: Rev. Sci. Instrum.; (United States), Journal Name: Rev. Sci. Instrum.; (United States) Vol. 59:8; ISSN RSINA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102* -- Fusion Energy-- Plasma Research-- Diagnostics
CLOSED PLASMA DEVICES
ELECTROMAGNETIC RADIATION
FAR INFRARED RADIATION
INFRARED RADIATION
LASER RADIATION
LIGHT SCATTERING
PLASMA DENSITY
PLASMA DIAGNOSTICS
RADIATIONS
SCATTERING
TEXT DEVICES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TURBULENCE