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Thermal conductivity measurement with a free floating molecule detector
Author(s) -
Plöchinger Heinz
Publication year - 2016
Publication title -
vakuum in forschung und praxis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.213
H-Index - 13
eISSN - 1522-2454
pISSN - 0947-076X
DOI - 10.1002/vipr.201600629
Subject(s) - thermal conductivity , thermal conductivity measurement , measuring principle , range (aeronautics) , detector , pressure measurement , signal (programming language) , materials science , conductivity , analytical chemistry (journal) , chemistry , thermodynamics , physics , optics , composite material , chromatography , computer science , programming language
“Zero‐pressure” elimination with Pirani principle for vacuum measurement and increase of the measurement range limit of thermal gas‐sensors and flow sensors Measurement of pressure in the medium vacuum range has been done via thermal conductivity. The literature on the Pirani principle has defined a lower range limit — the so‐called “zero pressure” until now [1]. The minimum power needed to hold a sensor up to operating temperature exceeds the useful signal, due to the conductivity of the sensor mounting and the resulting heat loss through the suspension. The author was able to eliminate the “zero pressure”, thereby expanding the measurement range of Pirani sensors significantly downwards. Measurement results confirmed an extension of the measurement range of two decades downwards with the coiled Pirani. Also with other sensors that use thermal conductivity and heatentrainment effects, e.g. gas sensors and sensors for flow measurement, the new principle can be applied and thus lower the lower range limit.