Refine your search:     
Report No.
 - 
Search Results: Records 1-11 displayed on this page of 11
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Microscopic origin of the spin-reorientation transition in the kagome topological magnet TbMn$$_{6}$$Sn$$_{6}$$

Huang, Z.*; Wang, W.*; Ye, H.*; Bao, S.*; Shangguan, Y.*; Liao, J.*; Cao, S.*; Kajimoto, Ryoichi; Ikeuchi, Kazuhiko*; Deng, G.*; et al.

Physical Review B, 109(1), p.014434_1 - 014434_9, 2024/01

Journal Articles

Pressure-modulated magnetism and negative thermal expansion in the Ho$$_2$$Fe$$_{17}$$ intermetallic compound

Cao, Y.*; Zhou, H.*; Khmelevskyi, S.*; Lin, K.*; Avdeev, M.*; Wang, C.-W.*; Wang, B.*; Hu, F.*; Kato, Kenichi*; Hattori, Takanori; et al.

Chemistry of Materials, 35(8), p.3249 - 3255, 2023/04

 Times Cited Count:0 Percentile:0(Chemistry, Physical)

Hydrostatic and chemical pressure are efficient stimuli to alter the crystal structure and are commonly used for tuning electronic and magnetic properties in materials science. However, chemical pressure is difficult to quantify and a clear correspondence between these two types of pressure is still lacking. Here, we study intermetallic candidates for a permanent magnet with a negative thermal expansion (NTE). Based on in situ synchrotron X-ray diffraction, negative chemical pressure is revealed in Ho$$_2$$Fe$$_{17}$$ on Al doping and quantitatively evaluated by using temperature and pressure dependence of unit cell volume. A combination of magnetization and neutron diffraction measurements also allowed one to compare the effect of chemical pressure on magnetic ordering with that of hydrostatic pressure. Intriguingly, pressure can be used to control suppression and enhancement of NTE. Electronic structure calculations indicate that pressure affected the top of the majority band with respect to the Fermi level, which has implications for the magnetic stability, which in turn plays a critical role in modulating magnetism and NTE. This work presents a good example of understanding the effect of pressure and utilizing it to control properties of functional materials.

Journal Articles

Guiding and confining fast electrons by transient electric and magnetic fields with a plasma inverse cone

Lei, A. L.*; Cao, L. H.*; Yang, X. Q.*; Tanaka, Kazuo*; Kodama, Ryosuke*; He, X. T.*; Mima, Kunioki*; Nakamura, Tatsufumi; Norimatsu, Takayoshi*; Yu, W.*; et al.

Physics of Plasmas, 16(2), p.020702_1 - 020702_4, 2009/02

 Times Cited Count:12 Percentile:42.75(Physics, Fluids & Plasmas)

The fast electron propagation in an inverse cone target is investigated computationally and experimentally. Two-dimensional particle-in-cell simulation shows that fast electrons with substantial numbers are generated at the outer tip of an inverse cone target irradiated by a short intense laser pulse. These electrons are guided and confined to propagate along the inverse cone wall, forming a large surface current. The experiment qualitatively verifies the guiding and confinement of the strong electron current in the wall surface. The large surface current and induced strong field s are of importance for fast ignition related research.

JAEA Reports

SIMMER-III: A Computer Program for LMFR Core Disruptive Accident Analysis; Version 3.A Model Summary and Program Description

Yamano, Hidemasa; Fujita, Satoshi; Tobita, Yoshiharu; Kamiyama, Kenji; Kondo, Satoru; Morita, Koji*; Fischer, E. A.; Brear, D. J.; Shirakawa, Noriyuki*; Cao, X.; et al.

JNC TN9400 2003-071, 340 Pages, 2003/08

JNC-TN9400-2003-071.pdf:1.54MB

An advanced safety analysis computer code, SIMMER-III, has been developed to investigate postulated core disruptive accidents in liquid-metal fast reactors (LMFRs). SIMMER-III is a two-dimensional, three-velocity-field, multiphase, multicomponent, Eulerian, fluid-dynamics code coupled with a space-dependent neutron kinetics model. By completing and integrating all the physical models originally intended at the beginning of this code development project, SIMMER-III is now applicable to integral reactor calculations and other complex multiphase flow problems. A systematic code assessment program, conducted in collaboration with European research organizations, has shown that the advanced features of the code have resolved many of the limitations and problem areas in the previous SIMMER-II code. In this report, the models, numerical algorithms and code features of SIMMER-III Version 3.A are described along with detailed program description. Areas which require future model refinement are also discussed. SIMMER-III Version 3.A, a coupled fluid-dynamics and neutronics code system, is expected to significantly improve the flexibility and reliability of LMFR safety analyses.

JAEA Reports

Effects of volume fraction and non-uniform arrangement of water moderator on reactivity

Cao, X.; Suzaki, Takenori; Kugo, Teruhiko; Mori, Takamasa

JAERI-Tech 2003-069, 36 Pages, 2003/08

JAERI-Tech-2003-069.pdf:3.77MB

From the viewpoint of nuclear criticality safety of fuel rod storage and transport, a series of critical experiments concerning effects of water hole size, water gap width, water-to-fuel volume ratio and non-uniform arrangement of water moderator have been performed at the Tank-type Critical Assembly (TCA) of Japan Atomic Energy Research Institute. In the present study, the effects of volume fraction and non-uniform arrangement of water moderator on reactivity are evaluated by the water level worth method and analyzed by the SRAC code. Error sources of experiments and calculations are discussed, especially for an energy group model. The calculation results of diffusion model with 17-group model show good agreement with the experiment results within a few dozen cents.

JAEA Reports

Research on fuel-coolant interaction by using a multi-phase multi-component Code

Cao, X.

JNC TN9400 2001-128, 200 Pages, 2002/03

JNC-TN9400-2001-128.pdf:5.17MB

Fuel Coolant Interactions (FCls) are the important phenomena during the Core Disruptive Accidents (CDAs) in Liquid Metal Cooled Fast Breader Reactors (LMFBRs) or Core Melt Accidents (CMAs) in Light Water Reactors (LWRs) and have been numerically investigated in recent years. The development and verification of models for the fundamental processes in FCIs are required for the application of a multi-phase, multi-component, fluid-dynamics computer code. In this study the drag coefficient model and the thermal fragmentation models for melt droplets are developed and verified through the application of SIMMER-III code, which is being developed at JNC, to the experiments, QUEOS, MIXA and KROTOS. The FCI phenomena are characterized by a configuration that hot particles/droplets surrounded with vapor film moves in coolant liquid. The correlation of drag coefficient has not been developed for such a configuration. In this study, based on the basic conservative equations and the mixture viscosity concept, the drag coefficients between melt droplets with vapor film and the surrounding coolant liquid under laminar and turbulent flow conditions are developed, which are expressed as functions of Reynolds number, vapor/liquid viscosity and density ratios and the other two dimensionless numbers newly introduced in this study. The proposed correlations are coupled into the SIMMER-III code and applied to simulate the QUEOS experiment. The results show that the proposed correlations reasonably improve the agreement of the calculated results with the experimental data. Thermal fragmentation mechanisms have been studied for many years, but the fragmentation models, triggered by boiling effect and surface solidificatjon effect, are not available for numerical simulation tools. In this study, based on the Taylor instability, the fragmentation models, triggered by surface solidification and vapor film collapse are developed and simplified non-dimensional correlations are ...

JAEA Reports

Proposal of the Thermal Fragmentation Models for Numerical Study of FCI

Cao, X.; Tobita, Yoshiharu

JNC TN9400 2001-123, 72 Pages, 2001/06

JNC-TN9400-2001-123.pdf:1.75MB

Thermal fragmentation mechanisms have been studied for many years, but the fragmentation models, triggered by boiling effect and surface solidification effect, are not available for numerical simulation tools. In this model Taylor instability is proposed to be the mechanisms for the thermal fragmentation of a melt droplet induced by external pressure pulse, boiling effect and surface solidification effect. The vapor film collapse model and the surface solidification model are developed to estimate the generated pressure pulse for different triggering event. Based on the triggering event of each fragmentation mechanism, simplified fragmentation correlations are proposed. The proposed fragmentation correlation are verified by simulating the MIXA and KROTOS experiments, respectively.

JAEA Reports

Simulation of the MIXA-06 Experiment by SIMMER-3

Cao, X.; Tobita, Yoshiharu

JNC TN9400 2001-122, 44 Pages, 2001/06

JNC-TN9400-2001-122.pdf:1.08MB

MIXA-06 experiment performed at Winfrish Technology centre in which 3 kg of molten fuel simulant (81% uranium and 19% molybdenum metal at a temperature of 36000 K) were released into water is selected to esti- mate the fragmentation model in SIMMER-III code on the mixing region in thecase of low Weber numbers in this study. The comparison of the front advancement of the melt droplet stream between the simulation and the experiment suggests that the currently employed hydrodynamic fragmentation model in SIMMER-III underestimates the fragmentation ra-te of the droplets in the simulation with low Waber numbers. The further investigation shows the fragmentation model based on thermal fragmentation mechanism is required.

Journal Articles

Verification of Drag Coefficient Model Through Simulation of FCI's Premixing Experiment

Cao, X.; Tobita, Yoshiharu

14 AFMC, 2, p.837 - 840, 2001/00

None

JAEA Reports

Study On Drag Coefficient For the Particle/droplet with Vapor Film

Cao, X.; Tobita, Yoshiharu

JNC TN9400 2001-055, 45 Pages, 2000/11

JNC-TN9400-2001-055.pdf:1.24MB

The fuel coolant interaction (FCI) phenomena are characterized by a configulation that a hot particle/droplet surrounded with vapor film moves in coolant liquid. A drag correlation has not been developed for such a configulation. In this study, based on the bzsic conservative equation, the drag coefficients between a single hot particle/droplet and the surroundings coolant liquid under laminar and turbulant flow conditions are developed first. The coefficients are expressed as fun-ctions of reynolds number, vapor/liquid viscosity and density rations and the other two dimensionless number newly introduced in this study. The drag coefficients for a multi-particle/droplet system under lami-nar and turbulant flow conditions are then developed based on the abo-ve single hot particle/droplet model and mixtureviscosity concept. The proposed correlations are coupled into the SIMMER-III code and are used to simulate the QUEOS experiment. It is shown that the proposed correlation reasonab

JAEA Reports

Simulation of Premixing Experiment QUEOS by SIMMER-III

Cao, X.; Tobita, Yoshiharu

JNC TN9400 2000-100, 52 Pages, 2000/06

JNC-TN9400-2000-100.pdf:1.48MB

The QUEOS,an experiment of the premixing phase of fuel coolant interactions(FCls), in which several kilograms of solid molybdenum spheres with low temperature (Q-8 300K) and high temperature (Q-12 2300K) are released into water, are simulated to evaluate the drag correlations between the fuel and coolant liquid on the mixing region in FCls, by SIMMER-III code, in which lshii's drag correlations in dispersed two-Phase flow are employed. The calculated results suggest that the momentum exchange between the spheres and coolant liquid is overestimated in the hot sphere cases by employing the current drag conrrelations. The difference of the advancement of the sphere cloud between experiments and simulations induced by the drag coefficients is discussed through the change of the multiplier of the drag coefficients.

11 (Records 1-11 displayed on this page)
  • 1