Far-infrared polarimetry/interferometry for internal magnetic field measurement on ZT-40M

Conference · Wed May 01 00:00:00 EDT 1985 · Rev. Sci. Instrum.; (United States)

OSTI ID:5169668

Erickson, R M; Forman, P R; Jahoda, F C

An important aspect of this method is to measure the density simultaneously with the Faraday rotation in order to infer the magnetic field from the rotation. This measurement performed on several chords yields information on the density and poloidal field profiles. Heterodyne techniques are employed for the polarimetry as well as the interferometry because they are insensitive to spurious amplitude changes that can hamper other methods. On ZT-40M, amplitude changes exceeding 50% have been observed, thus precluding any other method for their application. The authors use a 185-..mu..m laser, a rotating grating for heterodyning, and GaAs photoconductors and Schottky diodes for detection. An instrumental sensitivity of 3 mrad at a time resolution of 25 ..mu..s has been demonstrated, however vibration-induced structure limits the sensitivity to approx. 50 mrad. Efforts to reduce each of these numbers are in progress. The simultaneous measurement has been made on ZT-40M, and effort in turning to system refinement and scaling up to multichord operation. Error propagation in the inversion process is being evaluated.

• Research Organization: Los Alamos National Lab., NM
• OSTI ID: 5169668
• Report Number(s): CONF-840922-; TRN: 86-031896
• Journal Information: Rev. Sci. Instrum.; (United States), Vol. 56:5; Conference: 5. APS topical conference on high temperature plasma diagnostics, Tahoe City, CA, USA, 16 Sep 1984
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
47 OTHER INSTRUMENTATION
PLASMA DIAGNOSTICS
INTERFEROMETRY
POLARIMETRY
ZT-P DEVICES
FARADAY EFFECT
HETERODYNE RECEIVERS
PLASMA DENSITY
RESOLUTION
SENSITIVITY
ELECTRONIC EQUIPMENT
EQUIPMENT
MICROWAVE EQUIPMENT
RADIO EQUIPMENT
700102* - Fusion Energy- Plasma Research- Diagnostics
440300 - Miscellaneous Instruments- (-1989)