Investigation of a method for measurement of water vapor coverage on technical surfaces

Sefa, Makfir; Šetina, Janez; Erjavec, Bojan

doi:10.1016/j.vacuum.2016.06.013

Cited by 6 publications

(2 citation statements)

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“…To measure the conductance of nitrogen, argon, and water vapor at low temperatures, the CDG, which was used to measure the pressure of water vapor in several studies, was used [12,27]. To realize the measurement under low temperatures, the test dome, the gas supply device, and the orifice were all placed in the incubator.…”

Section: Conductance Of N 2 and Ar At Low Temperaturesmentioning

confidence: 99%

Study on the water detection using the flowmeter method at low temperatures

Geng

Wang

Ren

et al. 2023

Meas. Sci. Technol.

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To prepare for the lunar water exploration in the Chinese Lunar Exploration Project IV (CLEP), a new apparatus for studying characteristics of the water vapor conductance and water detection at low temperatures was built based on the flowmeter method, and the performance of the miniature time-of-flight mass spectrometer (TOF-MS) for water detection in the range -20 ~ 20 ℃ was measured. The through-put within the range of 3×10-9-9×10-6 Pa m3 s-1 was provided at temperatures in the range -60 ~ 20 ℃. The conductance of the orifice with a diameter of 21 microns for three gases (N2, Ar, and H2O) was measured at low temperatures. The diameter change of the metal orifice caused by the cold contraction in the molecular flow state is the main factor affecting the conductance, and the viscosity characteristic of gas in the viscous flow state is the main factor affecting the conductance. Therefore, the conductance of the orifice increases with the decreasing temperature when the through-put is high. In addition, the water vapor can be stably supplied by the orifice under low temperatures, and the conductance of water vapor through the orifice is measured through the on-line method and the time-ratio method. The adsorption rate and amount of water vapor on the metal surface increase with the decreasing temperature, hence the concentration of water molecules in the test dome significantly decreases as the temperature decreases. Finally, the through-put of water vapor of 8.75×10-8 Pa m3 s-1 was detected by the miniature TOF-MC at -20℃ on the apparatus.

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Section: Conductance Of N 2 and Ar At Low Temperaturesmentioning

confidence: 99%

Study on the water detection using the flowmeter method at low temperatures

Geng

Wang

Ren

et al. 2023

Meas. Sci. Technol.

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“…Similar techniques (also referred to as gas-burst methods) have been applied for the calibration of vacuum instruments, 4 for the determination of water outgassing from a stainless steel chamber, 5 for the calibration of getter pumps, 6 and for the determination of water coverage on technical surfaces. 7 In the present work, data from the throughput method is modeled to determine D H2O and the total gas desorbed. The diffusion coefficient thus determined is compared to that obtained by a simple gravimetric method: recording the weight change of the material as it absorbs gas from the atmosphere, thus providing an independent test of our results.…”

Section: Introductionmentioning

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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