Volume Determination of Vacuum Vessels by Gas Expansion Method

Avdiaj, Sefer; Šetina, Janez; Erjavec, Bojan

doi:10.1007/s12647-015-0137-1

Cited by 7 publications

(6 citation statements)

References 9 publications

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“…As the low-pressure side of our sample is a high vacuum, it was assumed that the partial pressure of helium at this side is zero. The volume of the low-pressure part of the system was determined by gas expansion method [14]. The sample surface and thickness were determined geometrically.…”

Section: Results and Discussion -Modified Accumulation Methodsmentioning

confidence: 99%

Measurements of helium permeation in Zerodur glass used for the realisation of quantum pascal

Kurtishaj

Hameli²,

Zeqiraj³

et al. 2022

ACTA IMEKO

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In the new optical pressure standard Ultra-Low Expansion glass cavities were proposed to measure helium refractivity for a new realisation of the unit of pressure, pascal. However, it was noticed that the use of this type of material causes some difficulties. One of the main problems of ULE glass is the pumping effect for Helium. Therefore, instead of ULE, Zerodur glass was proposed as a material for the cavity. This proposal was given by the Vacuum Metrology team of the Physikalisch-Technische Bundesanstalt - PTB in the QuantumPascal project. In order to calculate the flow of helium gas through Zerodur glass one has to know the permeation constant K. Moreover, the modelling of time dependency of the flow requires the knowledge of diffusion constant D as well. The relation between them is given by K = S · D, where S is the solubility of Helium in glass. In our research work we measured permeation of helium gas in Zerodur. Measurements were performed in the temperature range 80 °C – 120 °C. Based on our results, we consider that the Zerodur material has potential to be used as cavity material for the new quantum standard of pressure.

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Section: Results and Discussion -Modified Accumulation Methodsmentioning

confidence: 99%

Measurements of helium permeation in Zerodur glass used for the realisation of quantum pascal

Kurtishaj

Hameli²,

Zeqiraj³

et al. 2022

ACTA IMEKO

Self Cite

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“…to describe the resonator's electromechanical and magnetoelastic response. The model coupled the linear mechanical equations of motion [ 93 ] to the electrostatic equations [ 94 ] via the piezoelectric constitutive relations. [ 95 ] The sinusoidal excitation voltage u ex ( t ) = | u ex | sin (2π f ex t ) was applied as a Dirichlet boundary condition for the potential at the top electrode, the rear side electrode was defined as electrical ground, and fixed boundary conditions were used for the displacement field at the cantilever clamping.…”

Section: Methodsmentioning

confidence: 99%

A Magnetoelastic Twist on Magnetic Noise: The Connection with Intrinsic Nonlinearities

Spetzler,

McCord

2023

Adv Funct Materials

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Intrinsic magnetic noise limits the functionality of all magnetic field sensors and related devices using magnetic films as sensing elements. A novel origin of magnetic noise due to ferromagnetic material's magnetostriction is revealed by implementing a comprehensive multi‐level signal‐noise model and thoroughly validating it experimentally on magnetoelectric composite ΔE‐effect sensors. From electrical measurements and operando magnetic domain visualization, magnetic contributions are shown to dominate the noise floor and limit the overall performance of multi‐domain magnetoelastic sensors. The newly introduced noise contribution is correlated with the nonlinearity of the magnetostrictive properties. The effect on sensor output is particularly pronounced in magnetoelastic and magnetoelectric composite devices, but the results generally apply to all sensor devices incorporating magnetic materials. Therefore, the identified magnetic noise source makes a significant contribution to understanding the limitations of magnetic sensors and provides important guidelines for optimizing future magnetic sensors for low detectivity.

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“…The on-line method was used to measure the conductance of the orifice in the range −60 to 20 • C. because of the weak adsorption of N 2 and Ar [20]. First, it is necessary to know the volume of test dome 4 (V4), and V4 was measured by the isothermal expansion method [21],…”

Section: Conductance Measurement Methodsmentioning

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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Volume Determination of Vacuum Vessels by Gas Expansion Method

Cited by 7 publications

References 9 publications

Measurements of helium permeation in Zerodur glass used for the realisation of quantum pascal

Measurements of helium permeation in Zerodur glass used for the realisation of quantum pascal

A Magnetoelastic Twist on Magnetic Noise: The Connection with Intrinsic Nonlinearities

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

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