Experimental study on the conductance of pure and binary gas mixtures

Wei, Ningfei; Feng, Yang; Sun, W.; Cheng, Yongjun; Dong, Meng; Song, Yang; Wu, Chengyao; Liu, Guoting; Qiu, Yuntao

doi:10.1016/j.vacuum.2021.110277

Cited by 2 publications

(2 citation statements)

References 21 publications

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“…Comprehensive studies on the conductance and species separation from orifices and through pipes of finite lengths were published in recent years. 13,14,51 However, as the higher viscosity affects only the boundary and not the bulk flow, the effect is assumed to be small.…”

Section: Resultsmentioning

confidence: 99%

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Diffusive separation in rarefied plume interaction

Vesper

Kenjereš

Kleijn

2022

Journal of Vacuum Science &Amp; Technology B

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In the present study, we propose the use of a light, inert carrier gas to support deposition uniformity and rate in continuous physical vapor deposition, in which closely spaced slots or nozzles are required to achieve a sufficiently high deposition rate. Interaction shocks between the emerging rarefied plumes cause undesired nonuniformities in the deposited coating. The present work evaluates the effect of adding a carrier gas on the interaction shock. We study the interaction between two sonic plumes consisting of a binary mixture, i.e., silver as coating material and helium as a light inert carrier gas, by direct simulation Monte Carlo. While the inlet Mach and Knudsen numbers were kept constant, the fraction of carrier gas was varied to single out the effect of species separation. The influence of rarefaction on species separation was also studied. Species separation produces a high carrier-gas fraction in the periphery and an accumulation of the heavier species in the jet core. The resulting change in the speed of sound alters the local expansion characteristics and, thus, shifts the shock location and weakens the shock. These phenomena intensify with the degree of rarefaction. It is shown that adding a light carrier gas increases deposition rate may enhance uniformity and reduce stray deposition.

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Section: Resultsmentioning

confidence: 99%

“…1 It was shown that light carrier gases benefit the conductance of material through pipes and orifices and, thus, the possible deposition rate. 13,14 In summary, the use of background and carrier gases decisively influences the film's growth in thin-film and coating technology.…”

Section: Introductionmentioning

confidence: 99%

Diffusive separation in rarefied plume interaction

Vesper

Kenjereš

Kleijn

2022

Journal of Vacuum Science &Amp; Technology B

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Rarefied gas mixtures with large species mass ratio: Outflow into vacuum

Bykov

Захаров

2022

Physics of Fluids

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The theoretical study of the processes of the outflow of a binary gas mixture from a source into a vacuum through an orifice in an infinitely thin wall is presented. Two mixtures with a large species mass ratio K are considered: Au–Ne ( K = 9.76) and Au–He ( K = 49.21). The work continues the study of the flow of Ag–He mixture ( K = 26.95) started in Bykov and Zakharov [“Binary gas mixture outflow into vacuum through an orifice,” Phys. Fluids 32, 067109 (2020)]. The results of the direct simulation Monte Carlo made it possible to propose approximations of the mass flow rates of the species and the mixture depending on the species mass ratio, the flow rarefaction degree, and the mole fraction of light species in the source. It is shown that with an increase in the parameter K, an increase in the dimensionless mass flow rate of the mixture referred to the corresponding free molecular value is observed. The maximum dimensionless flow rate corresponds to the near-continuum regime and exceeds the value obtained using the hydrodynamic approximation and the equivalent single gas approach. A variation of K also leads to changes in the spatial distributions of the dimensionless density and velocity of the mixture and some axial focusing of the flow. An increase in the species mass ratio for the case of a small initial mole fraction of the heavy species in the source for a flow regime close to the hydrodynamic one leads to an increase in acceleration and axial focusing of the heavy species.

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Experimental study on the conductance of pure and binary gas mixtures

Cited by 2 publications

References 21 publications

Diffusive separation in rarefied plume interaction

Diffusive separation in rarefied plume interaction

Rarefied gas mixtures with large species mass ratio: Outflow into vacuum

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