A constant pressure flowmeter for extreme-high vacuum

Abstract

We demonstrate operation of a constant-pressure flowmeter capable of generating and accurately measuring flows as low as $2\times 10^{-13}$ mol/s. Generation of such small flows is accomplished by using a small conductance element with $C\approx 50$ nL/s. Accurate measurement then requires both low outgassing materials ($<10^{-15}$ mol/s) and small volume changes ($\approx 70$ $\mu$L). We outline the present flowmeter's construction, detail its operation, and quantify its uncertainty. The type-B uncertainty is $<0.2$ % ($k=1$) over the entire operating range. In particular, we present an analysis of its hydraulic system, and quantify the shift and uncertainty due to the slightly compressible oil. Finally, we compare our flowmeter against a NIST standard flowmeter, and find agreement to within 0.5 % ($k=2$).

arXiv comment19 pages; 10 figures; 1 table

References in corpus (5)

• Development of a new UHV/XHV pressure standard (cold atom vacuum standard)
• Challenges to miniaturizing cold atom technology for deployable vacuum metrology
• The effect of heat treatments and coatings on the outgassing rate of stainless steel chambers
• Outgassing rate comparison of seven geometrically similar vacuum chambers of different materials and heat treatments
• A constant pressure flowmeter for extreme-high vacuum

Cited by in corpus (2)

• Accurate measurement of the loss rate of cold atoms due to background gas collisions for the quantum-based cold atom vacuum standard
• A constant pressure flowmeter for extreme-high vacuum