Swept frequency reflectometer for correlation studies in the TJ-I tokamak

Journal Article · Mon Feb 01 04:00:00 EST 1993 · Review of Scientific Instruments; (United States)

DOI:https://doi.org/10.1063/1.1144219· OSTI ID:5564569

Sanchez, J; Branas, B; de la Luna, E; Estrada, T ^[1]

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1. Asociacion Euratom/Ciemat 28040 Madrid (Spain)

An improved correlation reflectometer technique has been developed and implemented on TJ-I to measure the radial correlation lengths of the density turbulence. The method uses homodyne detection and is based on the slow sweeping of one oscillator while the other remains at fixed frequency. The decay of the coherence shows maxima and minima as the distance between the two probing points increases. The maxima correspond to the relevant coherence values. The correlation length for the overall turbulence as well as the correlation length for the different frequency intervals can be directly determined in a single shot. By the operation in the [ital Q]-band (33--50 GHz) extraordinary mode, the system reaches most of the plasma radius. Correlation lengths obtained at the edge are compared with those measured at deeper positions in the plasma. The proposed method can provide the values of the differential phase delay along the sweep, avoiding the effect of lost fringes even in the presence of turbulence. This opens the possibility of obtaining the information on the density profile if several channels are used.

• OSTI ID: 5564569
• Journal Information: Review of Scientific Instruments; (United States), Journal Name: Review of Scientific Instruments; (United States) Vol. 64:2; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700320* -- Plasma Diagnostic Techniques & Instrumentation-- (1992-)
CLOSED PLASMA DEVICES
OPTICAL PROPERTIES
OPTICAL SYSTEMS
PHYSICAL PROPERTIES
PLASMA DENSITY
PLASMA DIAGNOSTICS
REFLECTIVITY
SURFACE PROPERTIES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES