Electromagnetic Enhancement of Carbon Transport in SiC Solution Growth Process: A Numerical Modeling Approach

2014 ◽  
Vol 778-780 ◽  
pp. 71-74 ◽  
Author(s):  
Kanaparin Ariyawong ◽  
Jean Marc Dedulle ◽  
Didier Chaussende
Keyword(s):  
Growth Rate ◽  
Numerical Modeling ◽  
Growth Front ◽  
Critical Value ◽  
Solution Growth ◽  
Carbon Distribution ◽  
Electromagnetic Enhancement ◽  
Key Issues ◽  
Front Stability ◽  
Carbon Transport

The carbon distribution and its transport in the liquid from the source to the crystal directly affect the control of parasitic nucleation, the growth front stability, and the growth rate during SiC solution growth. Controlling the carbon transport is one of the key issues for understanding and improving the process. In this paper, numerical modeling by finite element method is used to describe the complex convective flow pattern in the melt. We focus on electromagnetic convection and investigate the effect of coil frequency, keeping a simple and technologically realistic crucible design. We show that below a critical value of frequency, the carbon transport can be controlled by the electromagnetic convection, giving rise to significant growth rate enhancement.

Solution Growth of SiC Crystal with High Growth Rate Using Accelerated Crucible Rotation Technique

2006 ◽  
Vol 527-529 ◽  
pp. 119-122 ◽  
Author(s):  
Kazuhiko Kusunoki ◽  
Kazuhito Kamei ◽  
Nobuhiro Okada ◽  
Nobuyoshi Yashiro ◽  
Akihiro Yauchi ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
Graphite Crucible ◽  
High Growth Rate ◽  
Solution Growth ◽  
Growth Interface ◽  
Rotation Technique ◽  
Stable Growth ◽  
Crucible Rotation ◽  
Carbon Transport

We performed solution growth of SiC single crystals from Si-Ti-C ternary solution using the accelerated crucible rotation technique (ACRT). It was confirmed that the growth rate exceeding 200 μm/hr was achievable by several ACRT conditions. This high growth rate might be due to the enhancement of the carbon transport from the graphite crucible to the growth interface using the ACRT. Moreover, the incorporation of inclusions of the Si-Ti solvent in the grown crystal was significantly suppressed by using the ACRT. It was thought that the intensive convection near the growth interface resulted in not only the marked increase of SiC growth rate but also the superior homogeneity in the surface morphology. It was concluded that faster stable growth can be accomplished in the SiC solution growth using the ACRT.

Effect of Low Frequency Magnetic Field on SiC Solution Growth

2011 ◽  
Vol 679-680 ◽  
pp. 32-35
Author(s):  
Frédéric Mercier ◽  
Shin Ichi Nishizawa
Keyword(s):  
Magnetic Field ◽  
Marangoni Convection ◽  
Low Frequency ◽  
Growth Front ◽  
Solution Growth ◽  
Strong Impact ◽  
Frequency Magnetic Field ◽  
The Magnetic Field ◽  
Crystal Growth Front ◽  
Carbon Transport

We investigated numerically fluid dynamics and carbon transport in a 2 inches SiC solution growth with the presence of alternative magnetic fields. Buoyancy and Marangoni convection are taken into account. Our numerical results revealed that the magnetic field parameters have a strong impact on the melt convection. We also propose a solution to increase the mass transfer at the crystal growth front.

Effect of Forced Convection by Crucible Design in Solution Growth of SiC Single Crystal

2015 ◽  
Vol 821-823 ◽  
pp. 22-25 ◽  
Author(s):  
Kazuhisa Kurashige ◽  
Masahiro Aoshima ◽  
Koichi Takei ◽  
Kuniharu Fujii ◽  
Masahiko Hiratani ◽  
...  
Keyword(s):  
Growth Rate ◽  
Single Crystal ◽  
Forced Convection ◽  
Centrifugal Force ◽  
Rotation Rate ◽  
Growth Front ◽  
Solution Growth

In this paper, we will discuss how to cope with the smoother growth front and higher growth rate by the forced convection. When the rotation rate of the upper part of the solution is different from that of the lower part in the crucible, the centrifugal force of the upper part is different from that of the lower part. As a result, a forced convection occurs in the solution. This kind of convection was achieved with accelerating/decelerating rotation of crucible and a plate fixed on the bottom of the crucible. By optimizing conditions of rotation program patterns and the crucible design for the forced convection, the growth rate could almost be doubled while maintaining smooth morphology.

scholarly journals Kinetics and Metabolism of Bifidobacterium adolescentis MB 239 Growing on Glucose, Galactose, Lactose, and Galactooligosaccharides

2007 ◽  
Vol 73 (11) ◽  
pp. 3637-3644 ◽  
Author(s):  
Alberto Amaretti ◽  
Tatiana Bernardi ◽  
Elena Tamburini ◽  
Simona Zanoni ◽  
Mariella Lomma ◽  
...  
Keyword(s):  
Growth Rate ◽  
Recursive Algorithm ◽  
Carbon Fluxes ◽  
Degree Of Polymerization ◽  
Substrate Selectivity ◽  
Carbon Distribution ◽  
Bifidobacterium Adolescentis ◽  
Fermentation Products ◽  
Batch Cultures ◽  
Ethanol Yields

ABSTRACT The kinetics and the metabolism of Bifidobacterium adolescentis MB 239 growing on galactooligosaccharides (GOS), lactose, galactose, and glucose were investigated. An unstructured unsegregated model for growth in batch cultures was developed, and kinetic parameters were calculated with a recursive algorithm. The growth rate and cellular yield were highest on galactose, followed by lactose and GOS, and were lowest on glucose. Lactate, acetate, and ethanol yields allowed the calculation of carbon fluxes toward fermentation products. Distributions between two- and three-carbon products were similar on all the carbohydrates (55 and 45%, respectively), but ethanol yields were different on glucose, GOS, lactose, and galactose, in decreasing order of production. Based on the stoichiometry of the fructose-6-phosphate shunt and on the carbon distribution among the products, the ATP yield was calculated. The highest yield was obtained on galactose, while the yields were 5, 8, and 25% lower on lactose, GOS, and glucose, respectively. Therefore, a correspondence among ethanol production, low ATP yields, and low biomass production was established, demonstrating that carbohydrate preferences may result from different distributions of carbon fluxes through the fermentative pathway. During the fermentation of a GOS mixture, substrate selectivity based on the degree of polymerization was exhibited, since lactose and the trisaccharide were the first to be consumed, while a delay was observed until longer oligosaccharides were utilized. Throughout the growth on both lactose and GOS, galactose accumulated in the cultural broth, suggesting that β(1-4) galactosides can be hydrolyzed before they are taken up.

scholarly journals Qualitative Analysis of the Effect of Weeds Removal in Paddy Ecosystems in Fallow Season

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Leru Zhou ◽  
Zhigang Liu ◽  
Tiejun Zhou
Keyword(s):  
Growth Rate ◽  
Equilibrium State ◽  
Excretion Rate ◽  
Critical Value ◽  
Inorganic Fertilizer ◽  
Paddy Fields ◽  
Asymptotically Stable ◽  
Intrinsic Growth Rate ◽  
Stable Conditions ◽  
Coexistence Equilibrium

In the paper, we introduce a differential equations model of paddy ecosystems in the fallow season to study the effect of weeds removal from the paddy fields. We found that there is an unstable equilibrium of the extinction of weeds and herbivores in the system. When the intensity of weeds removal meets certain conditions and the intrinsic growth rate of herbivores is higher than their excretion rate, there is a coexistence equilibrium state in the system. By linearizing the system and using the Routh–Hurwitz criterion, we obtained the local asymptotically stable conditions of the coexistence equilibrium state. The critical value formula of the Hopf bifurcation is presented too. The model demonstrates that weeds removal from paddy fields could largely reduce the weeds biomass in the equilibrium state, but it also decreases the herbivore biomass, which probably reduces the content of inorganic fertilizer in the soil. We found a particular intensity of weeds removal that could result in the minimum content of inorganic fertilizer, suggesting weeds removal should be kept away from this intensity.

Growth of Large Diameter 4H-SiC by TSSG Technique

2013 ◽  
Vol 740-742 ◽  
pp. 65-68 ◽  
Author(s):  
Kazuhiko Kusunoki ◽  
N. Yashiro ◽  
Nobuhiro Okada ◽  
Kouji Moriguchi ◽  
Kazuhito Kamei ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fluid Flow ◽  
Single Crystal ◽  
Large Diameter ◽  
High Growth ◽  
High Growth Rate ◽  
Solution Growth ◽  
Morphological Stability ◽  
Control Member ◽  
Top Seeded Solution Growth

4H-SiC single crystal with 3-inch diameter was grown by top seeded solution growth (TSSG) technique. We used a new convection control member called “Immersion Guide (IG)” which causes the high and homogenous fluid flow in the solution. As a result, we achieved relatively high growth rate and morphological stability

scholarly journals The rebirth and evolution of Bezymianny volcano, Kamchatka after the 1956 sector collapse

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Alina V. Shevchenko ◽  
Viktor N. Dvigalo ◽  
Thomas R. Walter ◽  
Rene Mania ◽  
Francesco Maccaferri ◽  
...  
Keyword(s):  
Growth Rate ◽  
Numerical Modeling ◽  
Volcanic Activity ◽  
Summit Crater ◽  
Sector Collapse ◽  
Average Growth Rate ◽  
Average Growth ◽  
Bezymianny Volcano ◽  
Lava Domes

Abstract Continued post-collapse volcanic activity can cause the rise of a new edifice. However, details of such edifice rebirth have not been documented yet. Here, we present 7-decade-long photogrammetric data for Bezymianny volcano, Kamchatka, showing its evolution after the 1956 sector collapse. Edifice rebirth started with two lava domes originating at distinct vents ~400 m apart. After 2 decades, activity became more effusive with vents migrating within ~200 m distance. After 5 decades, the activity focused on a single vent to develop a stratocone with a summit crater. We determine a long-term average growth rate of 26,400 m3/day, allowing us to estimate the regain of the pre-collapse size within the next 15 years. Numerical modeling explains the gradual vents focusing to be associated with loading changes, affecting magma pathways at depth. This work thus sheds light on the complex regrowth process following a sector collapse, with implications for regrowing volcanoes elsewhere.

On the Growth Rate of Thermoelastic Instability

2004 ◽  
Vol 126 (1) ◽  
pp. 50-55 ◽  
Author(s):  
J. Y. Jang ◽  
M. M. Khonsari
Keyword(s):  
Growth Rate ◽  
Surface Roughness ◽  
Hot Spots ◽  
Wave Speed ◽  
Failure Process ◽  
Finite Thickness ◽  
Critical Value ◽  
Frictional Heat ◽  
Operating Speed ◽  
Thermoelastic Instability

Thermoelastic instability (TEI) is known to be directly related to the occurrence of hot spots in friction systems, such as brakes, seals, and clutches. TEI is a failure process where the local frictional heat, thermal expansion, contacting pressure and temperature grow rapidly over a certain critical value of the operating speed. In this article, we examine the rate of growth of instability and establish a link between the wave speed and the configuration of hot spots as well as its penetrating depth. The analysis includes provision for surface roughness and is capable of treating bodies of finite thickness with or without liquid lubrication.

Effect of finite spectral width on the modulational instability of Langmuir waves

1983 ◽  
Vol 30 (2) ◽  
pp. 203-209 ◽  
Author(s):  
J. C. Bhakta ◽  
D. Majumder
Keyword(s):  
Growth Rate ◽  
Spectral Density ◽  
Modulational Instability ◽  
Maximum Growth ◽  
Spectral Width ◽  
Critical Value ◽  
Maximum Growth Rate ◽  
Monochromatic Wave ◽  
Langmuir Waves ◽  
Gaussian Spectrum

The effect of finite spectral width on the modulational instability of Langmuir waves has been investigated applying a method developed by Alber to derive a transport equation for the spectral density. The numerical results presented show that the spectrum is stable against modulational perturbation when the spectral width exceeds some critical value. For a Gaussian spectrum, the maximum growth rate is less than that for a monochromatic wave but the domain of modulational instability is extended. For a uniform distribution the shift in the growth rate curve towards the region of shorter wavelength is more pronounced and, for a certain range of spectral width, the maximum growth rate exceeds that for a monochromatic wave.

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