Bulk etch rates of CR-39 at high etchant concentrations: diffusion-limited etching

This work continues the development of a numerical model to simulate transient tritium transport on the breeder zone (BZ) level for the EU helium-cooled pebble bed (HCPB) concept for DEMO. The basis of the model is the open-source field operation and manipulation framework, OpenFOAM. The key output quantities of the model are the tritium concentration in the purge gas and in the coolant and the tritium inventory inside the BZ structure. New model features are briefly summarized. As a first relevant application a simulation of tritium transport for a single pin out of the KIT HCPB design for DEMO is presented. A variety of scenarios investigates the impact of the permeation regime (diffusion-limited vs. surface-limited), of an additional hydrogen content of 300 Pa H2 in the purge gas, of the released species (HT vs. T2), and of the choice of species-specific rate constants (recombination constant of HT set twice as for H2 and T2). The results indicate that the released species plays a minor role for permeation. Both permeation and inventory show a considerable dependence on a possible hydrogen addition in the purge gas. An enhanced HT recombination constant reduces steel T inventories and, in the diffusion-limited case, also permeation significantly. Scenarios with 80 bar vs. 2 bar purge gas pressure indicate that purge gas volumetric flow is decisive for permeation.

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The Diffusion Mechanism of Megaproject Citizenship Behavior: The Role of Institutional Isomorphism

Sustainability ◽

10.3390/su13158123 ◽

2021 ◽

Vol 13 (15) ◽

pp. 8123

Author(s):

Delei Yang ◽

Jun Zhu ◽

Qingbin Cui ◽

Qinghua He ◽

Xian Zheng

Keyword(s):

Structural Equation ◽

Diffusion Mechanism ◽

Vital Role ◽

Citizenship Behavior ◽

Equation Modeling ◽

Positive Effects ◽

Diffusion Limited ◽

The Relationship ◽

Mimetic Isomorphism

Megaproject citizenship behavior (MCB) has been confirmed to a play vital role on megaproject performance. Although current research has argued that institution elements have had an impact on MCB diffusion, limited studies have empirically investigated the distinct effectiveness of various institution elements on driving MCB’s widespread diffusion in construction megaprojects. Based on institution theory, this study proposes a theoretical model comprising institutional elements (i.e., normative and mimetic isomorphism), owner’s support, relationship-based trust, and their effect or impact on MCB’s diffusion. Based on 171 industrial questionnaires collected from managers of contractors and designers in megaprojects. Partial least squares structural equation modeling (PLS-SEM) was used to validate the established model. The results indicated that both normative and mimetic isomorphism have positive effects on facilitating MCB diffusion, and owner’s support has shown partial mediation in promoting MCB diffusion through normative isomorphism, as well as full mediation in the promoting of MCB diffusion through mimetic isomorphism. Meanwhile, relationship-based trust exerts a positive moderating effect on the relationship between mimetic isomorphism and MCB. This study extends current literature on driving MCB diffusion from the perspective of institutional theory, contributing by providing four implications for megaprojects managers to “buy in” more extensive MCB.

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Anisotropy and Cluster Growth by Diffusion-Limited Aggregation

Physical Review Letters ◽

10.1103/physrevlett.55.1406 ◽

1985 ◽

Vol 55 (13) ◽

pp. 1406-1409 ◽

Cited By ~ 126

Author(s):

Robin C. Ball ◽

Robert M. Brady ◽

Giuseppe Rossi ◽

Bernard R. Thompson

Keyword(s):

Cluster Growth ◽

Diffusion Limited Aggregation ◽

Diffusion Limited

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Two-dimensional implementation of the finite element method with singularity correction for diffusion limited current at an unshielded disc electrode

Journal of Electroanalytical Chemistry ◽

10.1016/0022-0728(95)04008-c ◽

1995 ◽

Vol 394 (1-2) ◽

pp. 17-28 ◽

Cited By ~ 27

Author(s):

Josep Galceran ◽

David J. Gavaghan ◽

John S. Rollett

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Two Dimensional ◽

The Finite Element Method ◽

Disc Electrode ◽

Diffusion Limited ◽

Limited Current ◽

Element Method

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Silicon Oxide Etching Process of NF3 and F3NO Plasmas with a Residual Gas Analyzer

Materials ◽

10.3390/ma14113026 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3026

Author(s):

Woo-Jae Kim ◽

In-Young Bang ◽

Ji-Hwan Kim ◽

Yeon-Soo Park ◽

Hee-Tae Kwon ◽

...

Keyword(s):

Greenhouse Gas ◽

Silicon Oxide ◽

Gas Analysis ◽

Gas Analyzer ◽

Dc Offset ◽

Cleaning Performance ◽

Oxide Etching ◽

Residual Gas ◽

Etch Rates ◽

Very High

The use of NF3 is significantly increasing every year. However, NF3 is a greenhouse gas with a very high global warming potential. Therefore, the development of a material to replace NF3 is required. F3NO is considered a potential replacement to NF3. In this study, the characteristics and cleaning performance of the F3NO plasma to replace the greenhouse gas NF3 were examined. Etching of SiO2 thin films was performed, the DC offset of the plasma of both gases (i.e., NF3 and F3NO) was analyzed, and a residual gas analysis was performed. Based on the analysis results, the characteristics of the F3NO plasma were studied, and the SiO2 etch rates of the NF3 and F3NO plasmas were compared. The results show that the etch rates of the two gases have a difference of 95% on average, and therefore, the cleaning performance of the F3NO plasma was demonstrated, and the potential benefit of replacing NF3 with F3NO was confirmed.

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