Recent measurements of the osmotic pressure of mixtures of He 3 in superfluid He 4 demonstrate the feasibility of temperature measurement using either of two experimental techniques. The first method, developed by H. London, measures the osmotic pressure of the saturated mixture and is useful for th
Noise thermometry and3He melting pressure thermometry
โ Scribed by Johan Bremer; Alex Reesink; Marten Durieux
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 142 KB
- Volume
- 194-196
- Category
- Article
- ISSN
- 0921-4526
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โฆ Synopsis
A simple noise thermometer, based on the measurement of the currents produced by the noise voltages over a 44 /~fl manganin resistor with a commercial SQUID, has been used for temperature measurements between 0.1 K and 0.4 K. Results at the superconductive transition points of AuIn2, AuAI2 a~td Ir (nominally at 208 mK, 162 mK a~d 100 mK), realized with a NIST SRM 768 device, are consistent with the assigned NIST temperature values within 0.15 percent. 3He melting pressures have been measured at these three points and at the minimum of the melting curve, (pmi, = (2.93114 4-0.0002) MPa). Existing data for the melting curve are compared with results of thermodynamic calculations between 2 mK and 250 mK.
๐ SIMILAR VOLUMES
A compact 3He cryostat with a charcoal adsorption pump was constructed for use in thermometry. The cryostat fits into a liquid helium storage tank with a 51 mm neck. The 3He gas is held in a cylinder on top of the cryostat. The sample volume of the cryostat is 30 mm in diameter and 70 mm in height.
In order to avoid possible sources of heat leaks into liquid 3He-4He mixtures we have constructed an experimental setup using only materlals of high purity. The inner part of an Ag-cell was furnished with a 700~-Ag sinter (A = llOm 2) and two vlbratlng wires. The temperature of the cell wall was mea
The equation of Weber and Schmidt has been used for some time to describe thermomolecular pressure difference corrections necessary in precise vapour pressure thermometry. Roberts' and Sydoriak's tables of corrections are based on this equation. Several investigations have shown significant deviatio