Prediction of flow rates through an orifice at pressures corresponding to the transition between molecular and isentropic flow

Demuth, S.; Watson, J.S.

doi:10.1116/1.573924

Cited by 12 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where n pl α is the species density in front of the sampling orifice (say in the plasma) and C so = A so v α,th /4 the conductivity of the sampling orifice for collisionless sampling (C so is larger for transitional or isentropic flows [185]). The stable species are ionized in the ionizer and the MS signal, which is given either as (amplified) ion current or in counts per second, is proportional to the species density in the ionizer (n ionizer α = n MS α in this case):…”

Section: Mass Spectrometry Of Stable Neutralsmentioning

confidence: 99%

Foundations of measurement of electrons, ions and species fluxes toward surfaces in low-temperature plasmas

Benedikt

Kersten

Piel

2021

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

This foundation article discusses the diagnostics of electrons and ions in plasmas and fluxes of charged and neutral species toward plasma-facing surfaces by non-optical methods. The focus is laid on the fundamentals of the most common methods and their application to non-equilibrium low-pressure electropositive plasmas and ion beams. The key topics are Langmuir probes (LPs), Faraday cups (FCs) and energy analyzers, mass spectrometry, as well as novel calorimetric and force probes (FPs). For each method, the concepts are introduced, hints at best practice are given, and a survey of the recently published literature is included. Starting with the sheath–plasma boundary, the principles of plane and cylindrical LPs and the measurement of electron temperature and density are discussed. Beyond standard textbooks, double, triple and emissive probes are described and modulation techniques for obtaining the electron energy distribution function are presented. More technical issues related to probe compensation in radio-frequency plasmas, probe contamination, and the influence of a magnetic field are also included. The presentation is completed by modern radio-frequency techniques, such as impedance probes, multipole resonance probes, and self-excited electron resonance spectroscopy. FCs, retarding field analyzers (RFAs) as well as novel calorimetric and FPs are useful tools for the measurement of overall, not species resolved, ions and neutral species fluxes toward surfaces. RFAs provide overall ion energy distribution functions, whereas calorimetric and FPs can deliver information about fluxes of fast neutrals. The issues related to secondary electron emission, absolute signal calibration, and analysis of plasmas with complex chemistry are discussed. Mass spectrometry diagnostics is capable of mass and energy-resolved detection of ions and neutral species at the plasma-facing surfaces. Detection, identification and absolute density calibration of neutral stable and radical species are treated in detail and peculiarities of ion mass spectrometry, such as detection of negative ions, ion measurements in front of powered electrodes, or chromatic aberration and acceptance angle limitations in energy spectrum measurements are introduced.

show abstract

Section: Mass Spectrometry Of Stable Neutralsmentioning

confidence: 99%

Foundations of measurement of electrons, ions and species fluxes toward surfaces in low-temperature plasmas

Benedikt

Kersten

Piel

2021

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…The transition regime is an intermediate regime between molecular and viscous-laminar and which corresponds to a Knudsen number between 80 and 3. For a compressible flow DeMuth et al [24] developed a model which combines the expressions of the two other flows, molecular (Q mol ) and viscous(Q vis ). They use the Knudsen number (K n ) to combine these flows, in particular for values between 2 and 45 according to the expression:…”

Section: Transition Regimementioning

confidence: 99%

Design of a milling reactor coupled to a high-temperature mass spectrometer for thermodynamic/kinetic data of hydrogen-based materials

Kharbachi

Nuta

Artaud

et al. 2021

International Journal of Hydrogen Energy

View full text Add to dashboard Cite

Identification of species in the gaseous phase of hydride materials and their mixtures (e.g. LiBH 4 -MgH 2 ) is crucial for understanding the reactional mechanisms and diffusion kinetics of hydrogen across the different interfaces of phase segregation. This phase separation makes the characterization by conventional gas analysis techniques complicated and some analytical information could not be accessible. To overcome this surface/interface related issue, the study of the evolution of the gas phase emitted by the complex hydrides during ball-milling is considered. In this respect, an experimental setup is designed by coupling a milling reactor with a mass spectrometer through a capillary tubing and an effusion Knudsen cell. A gas flow study (from molecular to viscous regimes) is performed in order to propose a suitable architecture of the entire device (ball-mill, capillary tubing, pipes, effusion cell compartment and pumping system) compatible with the mass spectrometric detection in terms of effused flow and molecular beam. Simulation of the flows and definition of their regimes nature at each stage of the pipes and vessels system is addressed as function of geometric parameters, upstream pressures, and pumping capacity on the downstream side (effusion cell). The study highlights the advantage of using a capillary tubing for the connection and ensure an optimal detection. Different working pressure conditions are demonstrated and associated to its length, meanwhile the diameter of the capillary has been demonstrated to be too sensitive to be varied.

show abstract

Gas Flow

2023

A Users Guide to Vacuum Technology

View full text Add to dashboard Cite

Prediction of flow rates through an orifice at pressures corresponding to the transition between molecular and isentropic flow

Abstract: By acceptance of thii article, the publisher or recipient acknowledges th« U.S. Government's right to retain a nonexclusive, royalty-free license in and to any copyright covering the article.

Cited by 12 publications

References 0 publications

Foundations of measurement of electrons, ions and species fluxes toward surfaces in low-temperature plasmas

Foundations of measurement of electrons, ions and species fluxes toward surfaces in low-temperature plasmas

Design of a milling reactor coupled to a high-temperature mass spectrometer for thermodynamic/kinetic data of hydrogen-based materials

Gas Flow

Contact Info

Product

Resources

About