Recommended practices for the use of spinning rotor gauges in inter-laboratory comparisons

Fedchak, James A.; Arai, Kenta; Jousten, Karl; Šetina, Janez; Yoshida, Hajime

doi:10.1016/j.measurement.2015.02.012

Cited by 10 publications

(4 citation statements)

References 14 publications

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“…It appears in both the q 01 ( T ) and q 0 ( T ) components of Eq. (3) and consists of the combined uncertainty of the effective accommodation coefficient (inverse calibration factor) determined for N 2 (<0.5%), 21 the relative change in the effective accommodation coefficient for H 2 (6%), 24 the long-term stability of the calibrated effective accommodation coefficient (2%) 25 the estimated change due to heating the SRG to 150°C (2%), 26 and the statistical uncertainty due the linear fit to the pressure rise data (2%). The uncertainty of the background outgassing rate q 0 ( T ) is approximately u q 0 = 7%.…”

Section: Methodsmentioning

confidence: 99%

Investigations of medium-temperature heat treatments to achieve low outgassing rates in stainless steel ultrahigh vacuum chambers

Sefa

Fedchak

Scherschligt

2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The authors investigated the outgassing rates and fluxes of vacuum chambers constructed from common 304L stainless steel vacuum components and subjected to heat treatments. Our goal was to obtain H2 outgassing flux on the order of 10−11 Pa l s−1cm−2 or better from standard stainless steel vacuum components readily available from a variety of manufacturers. The authors found that a medium-temperature bake in the range of 400 to 450°C, performed with the interior of the chamber under vacuum, was sufficient to produce the desired outgassing flux. The authors also found that identical vacuum components baked in air at the same temperature for the same amount of time did not produce the same low outgassing flux. In that case, the H2 outgassing flux was lower than that of a stainless-steel chamber with no heat treatment, but was still approximately 1 order of magnitude higher than that of the medium-temperature vacuum-bake. Additionally, the authors took the chamber that was subjected to the medium-temperature vacuum heat treatment and performed a 24-h air bake at 430°C. This additional heat treatment lowered the outgassing rate by nearly a factor of two, which strongly suggests that the air-bake created an oxide layer which reduced the hydrogen recombination rate on the surface. [http://dx.doi.org/10.1116/1.4983211]

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Section: Methodsmentioning

confidence: 99%

Investigations of medium-temperature heat treatments to achieve low outgassing rates in stainless steel ultrahigh vacuum chambers

Sefa

Fedchak

Scherschligt

2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…For example, rotors that are initially smooth and free of scratches may perform differently than those that are rough. Experience in other labs [23] suggests that crash tests may, in some cases, have a larger effect than reported in Chang and Abbott [22]. In any case, crashing the rotor should be avoided as it may change the accommodation coefficient.…”

Section: Stabilitymentioning

confidence: 92%

NIST Calibration Services for Spinning Rotor Gauge Calibrations

Berg¹,

Fedchak²

2015

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“…Between 0.2 Pa and 2 Pa the effective accommodation coefficient is not constant but may be described by a simple linear model. 10,11 We did not use the SRG above 2 Pa in this work.…”

Section: Methodsmentioning

confidence: 99%

Gas uptake of 3D printed acrylonitrile butadiene styrene using a vacuum apparatus designed for absorption and desorption studies

Sefa

Ahmed

Fedchak

et al. 2016

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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We describe a vacuum apparatus for determining the outgassing rate into vacuum, the diffusion coefficient, and the amount of gas absorbed for various materials. The diffusion coefficient is determined from a model applied to time-dependent desorption data taken using a throughput method. We used this method to determine the diffusion coefficient, D, for H2O in 3-D printed acrylonitrile butadiene styrene (ABS). We found DH2O = 8.3 × 10−8 cm2/s ± 1.3 × 10−8 cm2/s (k = 1; 67% confidence interval) at 23.2 °C. This result was compared to the diffusion coefficient determined another by a gravimetric method, in which the sample weight was monitored as it absorbed gas from the atmosphere. The two methods agreed to within 3%, which is well within the uncertainty of the measurement. We also found that at least 80% of the atmospheric gas (air) absorbed by the ABS is water. The total amount of all atmospheric gas absorbed by ABS was about 0.35% by weight when exposed to ambient air in the laboratory, which was at a pressure of 101 kPa with a relative humidity of 57% at 22.2 °C.

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Recommended practices for the use of spinning rotor gauges in inter-laboratory comparisons

Cited by 10 publications

References 14 publications

Investigations of medium-temperature heat treatments to achieve low outgassing rates in stainless steel ultrahigh vacuum chambers

Investigations of medium-temperature heat treatments to achieve low outgassing rates in stainless steel ultrahigh vacuum chambers

NIST Calibration Services for Spinning Rotor Gauge Calibrations

Gas uptake of 3D printed acrylonitrile butadiene styrene using a vacuum apparatus designed for absorption and desorption studies

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