Design and construction of a gallium fixed-point blackbody at CENAM

D. Cárdenas-García

Abstract


For temperatures below silver fixed-point defined by the International Temperature Scale of 1990, a transfer radiation thermometer can be calibrated using either of two calibration schemes: a variable temperature blackbody with a standard platinum resistance thermometer as a reference, or with a set of fixed-point blackbodies. CENAM is presently working with the first scheme, and it is developing fixed-point blackbodies to have the capability to work with the second scheme too. For this purpose a gallium fixed-point blackbody to calibrate CENAM's transfer radiation thermometer was designed and constructed. The blackbody cavity has a cylindro-cone shape with effective emissivity equal to $0.9992 \pm 0.0004$ in the 8 $\mu$m to 14 $\mu$m wavelength range. The radiance temperature of the gallium fixed-point blackbody was estimated to have an expanded uncertainty of 54 mK, with a coverage factor $k = 2$.

Keywords


International temperature scale of 1990; fixed-point blackbody; radiation thermometry

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Revista Mexicana de Física

ISSN: 2683-2224 (on line), 0035-001X (print)

Bimonthly publication of Sociedad Mexicana de Física, A.C.
Departamento de Física, 2o. Piso, Facultad de Ciencias, UNAM.
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Apartado Postal 70-348, Coyoacán, 04511 Ciudad de México.
Tel/Fax: (52) 55-5622-4946, (52) 55-5622-4840. rmf@ciencias.unam.mx