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Journal Articles

${it In situ}$ optical microscopy of crystal growth of graphene using thermal radiation

Terasawa, Tomoo; Taira, Takanobu*; Obata, Seiji*; Saiki, Koichiro*; Yasuda, Satoshi; Asaoka, Hidehito

Vacuum and Surface Science, 62(10), p.629 - 634, 2019/10

Graphene, an atomically thin sheet composed of sp$$^{2}$$ carbon atoms, has been the most attractive material in this decade. The fascinating properties of graphene are exhibited when it is monolayer. Chemical vapor deposition (CVD) is widely used to produce monolayer graphene selectively in large-area. Here we introduce "radiation-mode optical microscopy" which we have developed in order to realize the ${it in situ}$ observation of the CVD growth of graphene. We show the method to observe graphene as bright contrast on Cu substrates in thermal radiation images. The growth mechanism, the nucleation site and rate limiting process, revealed by the ${it in situ}$ observation is presented. Finally, we show the CVD growth of graphene on Au substrates, resulting in the tuning of the emissivity of graphene by the pre-treatment procedures. Our method is not only a way to observe the graphene growth but also shed light on the thermal radiation property of graphene.

Journal Articles

Effect of hydrogen on chemical vapor deposition growth of graphene on Au substrates

Terasawa, Tomoo; Taira, Takanobu*; Yasuda, Satoshi; Obata, Seiji*; Saiki, Koichiro*; Asaoka, Hidehito

Japanese Journal of Applied Physics, 58(SI), p.SIIB17_1 - SIIB17_6, 2019/08

 Times Cited Count:4 Percentile:21.16(Physics, Applied)

Chemical vapor deposition (CVD) on substrates with low C solubility such as Cu and Au is promising to grow monolayer graphene selectively in a large scale. Hydrogen is often added to control the domain size of graphene on Cu, while Au does not require H$$_{2}$$ since Ar is inert against oxidation. The effect of H$$_{2}$$ should be revealed to improve the quality of graphene on Au. Here we report the effect of H$$_{2}$$ on the CVD growth of graphene on Au substrates using in situ radiation-mode optical microscopy. The in situ observation and ex situ Raman spectroscopy revealed that whether H$$_{2}$$ was supplied or not strongly affected the growth rate, thermal radiation contrast, and compressive strain of graphene on Au. We attributed these features to the surface reconstruction of Au(001) depending on H$$_{2}$$ supply. Our results are essential to achieve the graphene growth with high quality on Au for future applications.

Journal Articles

Effect of porous medium on heat transfer and flow in a circular tube

Uemura, Takuya*; Takeda, Tetsuaki; Ichimiya, Koichi*

Nihon Kikai Gakkai Yamanashi Koenkai Koen Rombunshu (020-4), p.49 - 50, 2002/10

A heat transfer experiment was performed using a horizontal circular tube to obtain the heat transfer and fluid flow characteristics in the tube inserted copper wire. From the results obtained in this experiment, it was found that an amount of heat removal in the tube with copper wire inserts increased about 20% comparing with a tube having a smooth wall. A heat transfer coefficient of the tube inserted copper wire also increased 30% to 50% under the constant pumping power condition.

JAEA Reports

Enhancement of heat transfer in a porous channel with metallic wire inserts

Takeda, Tetsuaki

JAERI-Research 2000-056, 27 Pages, 2000/12

JAERI-Research-2000-056.pdf:1.86MB

no abstracts in English

JAEA Reports

Study on natural convection heat transfer in a vertical enclosure of double coaxial cylinder; Cooling by natural circulation of air

Zhang, Y.*; Takeda, Tetsuaki; Inaba, Yoshitomo

JAERI-Tech 2000-065, 109 Pages, 2000/11

JAERI-Tech-2000-065.pdf:6.17MB

no abstracts in English

Journal Articles

A New optical instrumentation system for advanced light water reactor

Kakuta, Tsunemi; Yamagishi, Hideshi; Tabata, Hiroaki*; Urakami, Masao*

Dai-7-Kai Doryoku Enerugi Gijutsu Shimpojiumu Koen Rombunshu (00-11), p.254 - 257, 2000/11

no abstracts in English

JAEA Reports

Thermal calculation of bituminized product, 1; Thermal evaluation of bituminized product using heat transporting calculation

Miura, Akihiko;

JNC TN8410 99-044, 189 Pages, 1999/10

JNC-TN8410-99-044.pdf:7.18MB

This report includes several results that were made by calculation with several methods to clarify the cause of the fire and explosion incident. In the early times, we didn't have exact information of chemicaI property, reaction rate and any physical constants that we needed. But because the only data that indicate the cooling process of bituminized product was reported, we made heat-transporting calculation with taking this data. Based on the theory of the thermal hazard evaluation that was called Semenov theory or Frank-Kamenetskii theory, the amount of heat generation was estimated using the heat transporting calculation. Common theories were introduced in first section. In the second section, several results of heat transporting calculation were indicated. Calculations were made as follows. First, the model of bituminized product that was filled in the drum was created with the data of cooling process. Second, when the heat was generated in the drum, time-dependent temperature distribution was calculated. And last, judging from the balance of heat generation and heat radiation the critical heat rate was estimated.

Journal Articles

Study on nondestructive detection of surface flaw on materials by means of infrared thermography

; Okamoto, Yoshizo*; Eto, Motokuni; Ooka, Norikazu; Hoshiya, Taiji

Dai-2-Kai Samogurafi Niyoru Hihakai Hyoka Gijutsu Shimpojiumu Koen Rombunshu, p.85 - 91, 1998/00

no abstracts in English

JAEA Reports

Experimental test results of multi-channel test rig of T$$_{1}$$ test section, III; Test results in helium gas conditions heated to 1000$$^{circ}$$C

Hino, Ryutaro; Takase, Kazuyuki; Maruyama, So;

JAERI-M 90-033, 37 Pages, 1990/03

JAERI-M-90-033.pdf:0.96MB

no abstracts in English

JAEA Reports

Validation of ASSCOPS by results of large-scale demonstration test, Run-D2

; Matsuki, Takuo*; Hiroi, Hiroshi*; Himeno, Yoshiaki

PNC TN9410 88-092, 82 Pages, 1988/08

PNC-TN9410-88-092.pdf:4.29MB

Post-test calculations of the large-scale sodium leak demonstration test, Run-D2, were performed using the ASSCOPS code in order to validate the applicability of the code to the evaluation of the fire suppression function of the PNC-type smothering tank. In the analysis, radiation coefficients between aerosols in the gas phase and structures and a pool surface in the smothering tank defined in the code were varied as parameter. The following three cases were calculated. (a)No aerosols suspending was assumed in the gas phase and thus, 1.0 was used as the coefficient between the structures and the pool surface. (b)The coefficient between the aerosols and the pool surface was 0.65, and that between structures and the aerosols was 0.73. (c)The coefficient between the aerosols and the pool surface was the same as case (b) and 0.5 was used as that between structures and the aerosols. The comparison between analysis and experiment with regard to the temperature of the various parts showed that the agreement was within +30% and -20%. From these results, it was concluded that the code was available for the evaluation of the fire suppression function of the smothering tank.

JAEA Reports

SSC-L: Super system code for loop-type fast breeder reactors; Improvement in the accuracy and the applicability of SSC-L

; Yoshikawa, Shinji*; ; Ohshima, Hiroyuki

PNC TN9410 87-143, 357 Pages, 1987/10

PNC-TN9410-87-143.pdf:21.11MB

SSC-L is a best estimate computer code for the whole plant system thermohydraulic analysis. It is applied to all the categories of accidents, i.e, protected accidents (PLOHS, PLOF, and LOPI) and unprotected accidents (ULOF, UTOP, ULOHS and ULOPI). The purpose of this study is to improve the capability of SSC-L so that it can be used for the safety evaluation of FBR system extensively with sufficient accuracy. Phenomenological models and system/component models are newly developed and added to SSC-L. A number of modules originally used in SSC-L are modified or replaced. As a result, the modifications are related to the most part of the computational modules in SSC-L. The following models, for example, are developed regarding the in-vessel and heat transport system termohydraulics such as: (a)modification of two-region upper plenum model, (b)multi-pressure point lower plenum model, (c)reactivity feedback effect for unprotected accident analysis, (d)whole core inter-subassembly heat transfer model, (e)modeling of heat losses through the piping wall, (f)decay heat removal systems, i.e., IRACS and DRACS, model, (g)more stable and accurate IHX heat transfer model, (h)modification of the pipe break model, etc. In addition, a graphic package for SSC is developed to display the computational results in the form of two dimensional time history. The improved SSC-L is applied to the analysis of various type of accidents and the effectiveness of the improvement is demonstrated. It is concluded that the first stage of the SSC-L development has been completed. This code is to be used as an effective computational tool for the safety analysis of Monju and larger scale FBR from the viewpoint of the whole plant behavior.

Oral presentation

Radiation-mode optical microscopy for CVD growth of graphene on gold

Terasawa, Tomoo; Taira, Takanobu*; Obata, Seiji*; Yasuda, Satoshi; Saiki, Koichiro*; Asaoka, Hidehito

no journal, , 

Since the solubility of carbon in copper is very low, monolayer graphene can be selectively grown by chemical vapor deposition (CVD) on a copper substrate. Thus, CVD growth of graphene is considered the most promising technique for the next-generation electronics. Here we report the CVD growth of graphene on gold substrates which also have the low solubility of carbon. We achieved the in-situ observation of the CVD growth of graphene on a gold foil by radiation-mode optical microscopy (Rad-OM). Figure shows the Rad-OM images of a gold foil at the growth time of 15, 30, and 40 min at 900$$^{circ}$$C under Ar, H$$_{2}$$, and CH$$_{4}$$ gas flow at 240, 8, and 5 sccm, respectively. The bright islands, corresponding to graphene confirmed by Raman spectroscopy, appeared between two trenches of the gold foil and grew parallel to the trenches. We will discuss the growth kinetics of graphene on gold, on the basis of the in-situ Rad-OM observation.

Oral presentation

In-situ observation of graphene growth on low-emissivity metal substrates using thermal radiation

Terasawa, Tomoo; Obata, Seiji*; Yasuda, Satoshi; Saiki, Koichiro*; Asaoka, Hidehito

no journal, , 

no abstracts in English

Oral presentation

Modification of emissivity of graphene by surface reconstruction of Au(001)

Terasawa, Tomoo; Yasuda, Satoshi; Hayashi, Naoki*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Asaoka, Hidehito

no journal, , 

no abstracts in English

Oral presentation

Electronic band modification of graphene by surface reconstruction of Au (001)

Terasawa, Tomoo; Yasuda, Satoshi; Hayashi, Naoki*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Yano, Masahiro; Saiki, Koichiro*; Asaoka, Hidehito

no journal, , 

Oral presentation

Modification of electronic band structure of graphene on Hex-Au(100) reconstructed surface

Terasawa, Tomoo; Yasuda, Satoshi; Hayashi, Naoki*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Yano, Masahiro; Saiki, Koichiro*; Asaoka, Hidehito

no journal, , 

We report the band structure of graphene grown on hex-Au(001) using angle resolved photoemission spectroscopy (ARPES). We prepared graphene on hex-Au(001) by chemical vapor deposition and took ARPES image of the sample at AichiSR BL7U. The linear graphene band shows the intensity reduction at the binding energy of approximately 0.9 eV, indicating the modification of band structure of graphene by quasi-one dimensional potential of the hex-Au(001) reconstructed surface.

Oral presentation

In-situ observation of CVD growth of graphene on Au by radiation-mode optical microscopy

Terasawa, Tomoo; Taira, Takanobu*; Obata, Seiji*; Yasuda, Satoshi; Saiki, Koichiro*; Asaoka, Hidehito

no journal, , 

Monolayer selective growth of graphene was achieved by chemical vapor deposition on a Cu substrate due to its low carbon solubility. In this study, we attempted the in-situ observation of chemical vapor deposition of graphene on a Au substrate with low carbon solid solubility like Cu by a radiation-mode optical microscopy. In the radiation images, the bright contrast started the growth between the trenches of the Au foil and progressed parallel to the trenches. The result of Raman mapping measurement indiceted that this contrast corresponded to graphene. In the presentation, we will also discuss the growth mechanism of graphene on the Au substrate.

Oral presentation

Relation between thermal radiation intensity and band structure of graphene on Au

Terasawa, Tomoo; Yasuda, Satoshi; Hayashi, Naoki*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Asaoka, Hidehito

no journal, , 

Graphene shows absorptivity and emissivity of 2.3% independent from the wavelength, however, the wavelength selectivity of the optical properties is required for device applications. Here we report the observation of the electronic band structure and thermal radiation of graphene grown on hex-Au(001) structure. The thermal radiation of graphene grown on hex-Au(001) was decreased in the optical microscopy which observed the light with the wavelength of 700-900 nm. The same sample showed the modified band structure observed by angle resolved photoemission spectroscopy. We will discuss the relation between the thermal radiation and band structure of graphene on Au substrates.

Oral presentation

Band modification of graphene by periodic potential of Au(100) reconstructed surface

Terasawa, Tomoo; Yasuda, Satoshi; Hayashi, Naoki*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Yano, Masahiro; Saiki, Koichiro*; Asaoka, Hidehito

no journal, , 

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