A new type of a small cell for the realization of the triple point of mercury

Abstract

Miniature glass and stainless-steel cells have been made at the Institute of Low Temperature and Structure Research for the realization of the triple point of mercury (T90 = 234.3156 K) to be used for the calibration of capsule-type standard platinum resistance thermometers. This paper gives details on the construction of these cells and some measurement results obtained at the triple point of mercury.

The α–β Transition of Nitrogen

“…Several miniature cells (the size of a SPRT) were sealed at INTiBS with mercury from different sources: NIST (99.99999%), Rône Alpes (99.9999%), and Goodfellow (99.9999%). All melts were within 0.1 mK, i.e., comparable to the realization uncertainty [11,12]. The fixed points of hydrogen, neon, oxygen, and argon were realized in sealed cells, all produced by IMGC.…”

“…The mercury triple point is realized in a miniature cell made at INTiBS [11] and compared with a traditional mercury cell at IMGC [12]. Several miniature cells (the size of a SPRT) were sealed at INTiBS with mercury from different sources: NIST (99.99999%), Rône Alpes (99.9999%), and Goodfellow (99.9999%).…”

“…The cryostat fabricated at INTiBS and used for the measurements was already described in [11]. In order to improve the adiabatic conditions, an additional goldplated copper shield was mounted around the cell.…”

CCT-K2.4: NRC/INTiBS/LNE-Cnam trilateral comparison of capsule-type standard platinum resistance thermometers from 13.8 K to 273.16 K

“…Cell 972 belongs to a group of NPL cells showing instability, as reported in the EUROMET 549 comparison of water triple point cells [2]. The mercury triple point was realized in an INTiBS miniature cell [3]. These initial results obtained at INTiBS were confirmed by a bilateral comparison with IMGC 2 [4].…”

“…The expanded uncertainty, U, of the INTiBS degree of equivalence (also listed in Table 5), is obtained by appropriately combining the uncertainties of the bracketed terms in Equation 3. The uncertainty of (T INTiBS -T NRC ) is readily identified as u p from Equation 2, and reported in Table 4.…”