Traceability to SI units for vacuum measurement in industrial applications

Jousten, Karl

doi:10.1016/j.measurement.2011.10.036

Cited by 5 publications

(3 citation statements)

References 39 publications

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“…Because of this, vacuum metrology with IGs is inherently unreliable. National standards agencies across the globe offer calibration services for IGs using orifice flow pressure standards [4][5][6][7]; however, the orifice flow method is intrinsically limited to use with inert particles, and IG calibration is typically only provided for either Nitrogen or Argon gas. A convenient, primary standard that is capable of measuring any type of gas (atomic or molecular) would be a boon to metrology, advanced material processing technologies, and even aeronomy.…”

Section: Introductionmentioning

confidence: 99%

Realization of a universal quantum pressure standard

2020

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We report the realization of the first cold-atom primary standard. This standard is based on a universal law governing quantum diffractive collisions between particles that allows an experimental determination of the velocity averaged total collision cross section, the only parameter required to quantify the pressure or flux of particles given a sensor particle collision rate measurement. Using an ensemble of 87Rb sensor atoms, we show that this new quantum pressure standard can be applied to gases of both atomic (He, Ar, and Xe) and molecular species ( N 2 , C O 2 , and H 2 ), surpassing the scope of existing orifice flow pressure standards. We verify the accuracy of this new standard using an ionization gauge (IG) calibrated for N2 by an orifice flow standard. The gauge calibration factors determined by the cold atom and orifice flow standards differ by less than 0.5% and, thus, agree within their uncertainties of 2% and 2.8% respectively. Using this standard, we evaluate the response of two different IGs to a variety of different gas species and report variations of up to 20% for their measured calibration factors. We also observe a non-linear response of the IG readings for CO2 gas. Finally, we demonstrate the use of a magneto-optical trap (MOT) as a transfer standard to extend the measurement range by a factor of 100 to include pressures up to P ~ 10−5 Pa.

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Section: Introductionmentioning

confidence: 99%

Realization of a universal quantum pressure standard

2020

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“…Modern primary vacuometers are based on balancing pres sure by a liquid column [1,2] 3 . Their operation principle is similar to that of the Torrichelli device [3].…”

Section: Introductionmentioning

confidence: 99%

“…This limits the pressure standards from below. At the lowest pressures, absorption on and desorption from the walls compromises the equilibrium Maxwellian velocity Metrologia Primary vacuometer based on an ultracold gas in a shallow optical dipole trap V B Makhalov 1 , K A Martiyanov 1 and A V Turlapov 1,2 distribution, pressure isotropy, and calculated pressure value. Introduction of a gauge intended for calibration changes the pressure and gas composition.…”

Section: Introductionmentioning

confidence: 99%

Primary vacuometer based on an ultracold gas in a shallow optical dipole trap

2016

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A calibrationfree primary vacuometer based on an ultracold atomic gas in a shallow far offresonance optical dipole trap is proposed and demonstrated. The pressure is obtained by measuring the loss of trapped atoms which is caused by collisions with the ambient gas of the vacuum chamber. The loss is related to the ambientgas pressure via a theoretical model based on first principles. The model is applicable owing to elimination of a number of systematic effects which otherwise preclude or complicate construction of a firstprinciple model. These systematics include loss unrelated to collisions with the ambient gas as well as loss dependance on the number and energy of trapped atoms. In the demonstrated vacuometer, the atomnumber decay is exponential with the rate proportional to the pressure, where the proportionality coefficient is expressed via the gas composition and van der Waals coefficients C 6 . Whenever the gas composition is unknown, the systematic error is typically well below that of the hotcathode ionization gauge. The vacuometer is implemented using a gas of ultracold lithium6, which is the optimal working body for such a vacuometer. The lowest measured pressure, × − 2.8 10 9 Pa, is limited by the vacuum in the apparatus, while the dominant error source of 4% is due to uncertainty in the C 6 value and may be improved. Comparison with reading of a hotcathode ionization gauge is also shown. Keywords: pressure measurements, vacuometer, laser cooling and trapping of atoms, atomic and molecular interactions, van der Waals forces

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