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

D. Cárdenas-García

Km 4.5 Carretera a los Cués, El Marqués, 76246, Querétaro, México, Tel: (442)2110500 e-mail: dcardena@cenam.mx.

Received 22 October 2014; ]]> accepted 9 January 2015

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 ± 0.0004 in the 8 μm to 14 μm 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.

PACS: 78.20.Ci

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