Monte Carlo Analysis of the Behavior of Divergent Conical Effusion Orifices

Ward, John W.; Fraser, Malcolm V.; Bivins, Robert L.

doi:10.1116/1.1316990

Cited by 10 publications

(5 citation statements)

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“…As noted, many investigators have written Monte Carlo codes to simulate Knudsen flow. [12][13][14][15][16][17][18][19] Molecule-molecule collisions are minimal and hence the linear trajectory of each molecule can be traced individually until it either exits the upper orifice or goes out of the beam before that. The details of the code are discussed in the companion report to this paper.…”

Section: Monte Carlo Codementioning

confidence: 99%

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Monte Carlo simulation of a Knudsen effusion mass spectrometer sampling system

Radke

Jacobson

Copland

2017

Rapid Comm Mass Spectrometry

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This code allows the geometry (aperture spacing and diameters) of the sampling system to be optimized for maximum transmission. The calculated effusate distributions and low average number of orifice wall collisions illustrated the advantages of restricted collimation. Calculated transmission factors are also compared to literature values calculated via the analytical method of Chatillon and colleagues. Published in 2017. This article is a U.S. Government work and is in the public domain in the USA.

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Section: Monte Carlo Codementioning

confidence: 99%

“…[12] Since then, many investigators have further extended this Monte Carlo approach. [12][13][14][15][16][17][18][19] Today, because of the wide availability of high-speed desktop computers with multicore processors, Monte Carlo simulation is one of the easiest and most flexible ways to describe Knudsen flow.…”

mentioning

confidence: 99%

Monte Carlo simulation of a Knudsen effusion mass spectrometer sampling system

Radke

Jacobson

Copland

2017

Rapid Comm Mass Spectrometry

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“…Molecular flow can be modeled analytically 55,56 or simulated using a Monte Carlo technique. 39,[57][58][59][60][61] Today, Monte Carlo is probably the most useful technique. A valid simulation can be run on a desktop computer, and a number of factors can be easily explored.…”

Section: Molecular Beammentioning

confidence: 99%

“…This means the vapor species strikes the orifice wall and is reemitted in a completely random direction. Molecular flow can be modeled analytically 55,56 or simulated using a Monte Carlo technique 39,57–61 . Today, Monte Carlo is probably the most useful technique.…”

Section: Instrumentationmentioning

confidence: 99%

Knudsen effusion mass spectrometry: Current and future approaches

Jacobson,

Colle,

Stolyarova

et al. 2024

Rapid Comm Mass Spectrometry

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RationaleKnudsen effusion mass spectrometry (KEMS) has been a powerful tool in physical chemistry since 1954. There are many excellent reviews of the basic principles of KEMS in the literature. In this review, we focus on the current status and potential growth areas for this instrumental technique.MethodsWe discuss (1) instrumentation, (2) measurement techniques, and (3) selected novel applications of the technique. Improved heating methods and temperature measurement allow for better control of the Knudsen cell effusive source. Accurate computer models of the effusive beam and its introduction to the ionizer allow optimization of such parameters as sensitivity and removal of background signals. Computer models of the ionizer allow for optimized sensitivity and resolution. Additionally, data acquisition systems specifically tailored to a KEMS system permit improved quantity and quality of data.ResultsKEMS is traditionally utilized for thermodynamic measurements of pure compounds and solutions. These measurements can now be strengthened using first principles and model‐based computational thermochemistry. First principles can be used to calculate accurate Gibbs energy functions (gefs) for improving third law calculations. Calculated enthalpies of formation and dissociation energies from ab initio methods can be compared to those measured using KEMS. For model‐based thermochemistry, solution parameters can be derived from measured thermochemical data on metallic and nonmetallic solutions. Beyond thermodynamic measurements, KEMS has been used for many specific applications. We select examples for discussion: measurements of phase changes, measurement/control of low‐oxygen potential systems, thermochemistry of ultrahigh‐temperature ceramics, geological applications, nuclear applications, applications to organic and organometallic compounds, and thermochemistry of functional room temperature materials, such as lithium ion batteries.ConclusionsWe present an overview of the current status of KEMS and discuss ideas for improving KEMS instrumentation and measurements. We discuss selected KEMS studies to illustrate future directions of KEMS.

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“…However, Winterbottom and Hirth used data for silver vapor on nickel and molybdenum surfaces to support their theoretical conclusion that the greatest surface diffusion contributions will be found with orifices of small diameters and small length-to-radius ratios or knife-edges. Ward et al [8,9] There has been little experimental data with which to compare this model. Boyer and Meadowcroft [10] have measured the free energy of vaporization of silver under conditions which Winterbottom and Hirth predict will promote surface diffusion.…”

Section: Introductionmentioning

confidence: 99%