Use of the Clausing's equation to evaluate the pumping action of molecular Gaede pumps

Levi, G.; Simon, Miloslav; Helmer, J. C.

doi:10.1016/0042-207x(94)00079-4

Cited by 8 publications

(5 citation statements)

References 10 publications

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“…The functions W sr (x), W rs (L − x), W rr (x − x) represent the probabilities that a molecule reflected from the wall at different positions will exit the pore. The ballistic component W ss (L) is given by a geometric factor [18,51,52] In order to experimentally determine the W ss and W wall components, we examined the measured flow through pnc-Si and carbonized pnc-Si membranes. Figure 5 compares the experimental and theoretical permeance for five membranes before and after carbonization.…”

Section: Resultsmentioning

confidence: 99%

Ballistic and non-ballistic gas flow through ultrathin nanopores

et al. 2012

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We show that ultrathin porous nanocrystalline silicon membranes exhibit gas permeance that is several orders of magnitude higher than other membranes. Using these membranes, gas flow obeying Knudsen diffusion has been studied in pores with lengths and diameters in the tens of nanometers regime. The components of the flow due to ballistic transport and transport after reflection from the pore walls were separated and quantified as a function of pore diameter. These results were obtained in pores made in silicon. We demonstrate that changing the pore interior to carbon leads to flow enhancement resulting from a change in the nature of molecule-pore wall interactions. This result confirms previously published flow enhancement results obtained in carbon nanotubes.

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Section: Resultsmentioning

confidence: 99%

Ballistic and non-ballistic gas flow through ultrathin nanopores

et al. 2012

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“…5 If the channel has been properly designed for the expected discharge pressure, the pressure distribution along its length will be as shown in Fig. 5 If the channel has been properly designed for the expected discharge pressure, the pressure distribution along its length will be as shown in Fig.…”

Section: Equation Developmentmentioning

confidence: 99%

Power dissipation in turbomolecular pumps at high pressure

Cerruti¹,

Spagnol²,

Helmer³

1999

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

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“…5, show that the exit probability appears to increase linearly along the length for all tube's geometries. Although the curves look like perfectly straight lines, very small but nonzero slope variations can be detected on their first derivatives as already observed by Levi et al 15 For each tube geometry, there is a finite escape probability ⌬ at the inlet and a corresponding probability at the outlet which is exactly 1 − ⌬ due to the tube's symmetry with respect to its middle section. Consequently, the escape probability at the tube's middle section is exactly 0.5.…”

Section: Angular Transfer Function Of a Tubementioning

confidence: 68%

Signal enhancement strategies for angular profile measurements of gas injected in ultrahigh vacuum

Isnard

Arès

2010

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

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With current trends in physical chemistry and various ultrahigh vacuum (UHV) based fabrication techniques, such as thin film deposition and epitaxy, there is a growing need to develop a precise and reliable simulation platform to predict the angular distribution of gas molecules injected in vacuum through a nozzle of a given geometry. Such models need to be validated through a systematic experimental study that clearly isolates the contributions of each parameter. For this purpose, a test platform dedicated to the measurement of the molecular beam angular profiles produced by a nozzle in UHV has been designed and built. Its main features are discussed, especially regarding its ability to produce precise and reproducible data. In order to reduce the contribution from the molecules scattered by the chamber walls to the measured flux densities and thus achieve a better signal-to-background ratio, several strategies are considered and evaluated. In particular, an innovative approach based on a direction selection tube is presented with a quantitative evaluation of its effect on the measurements. Finally a rule of thumb is proposed for the choice of the tube’s dimensions allowing a maximum background reduction while keeping the impact on the signal as small as desired.

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Use of the Clausing's equation to evaluate the pumping action of molecular Gaede pumps

Cited by 8 publications

References 10 publications

Ballistic and non-ballistic gas flow through ultrathin nanopores

Ballistic and non-ballistic gas flow through ultrathin nanopores

Power dissipation in turbomolecular pumps at high pressure

Signal enhancement strategies for angular profile measurements of gas injected in ultrahigh vacuum

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