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Journal Articles

In-vessel tritium

Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09

no abstracts in English

Journal Articles

Self-consistent integrated modelling of core and SOL/divertor transports and simulation study on transient behavior of heat load on divertor targets

Shimizu, Katsuhiro; Takizuka, Tomonori; Hoshino, Kazuo; Honda, Mitsuru; Hayashi, Nobuhiko; Takayama, Arimichi*; Fukuyama, Atsushi*; Yagi, Masatoshi*

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 6 Pages, 2011/03

We have developed a self-consistent integrated modelling of core and SOL/divertor transport. Thereby it enables us to investigate operation scenarios to be compatible with high confinement core plasma and detached divertor plasmas. To integrate a 1.5D core code (TOPICS-IB and TASK) and a 2D divertor code (SONIC), we introduce a new Multiple Program Multiple Data parallel computing system. For an integrated code including Monte-Carlo calculations, this system makes it possible to perform efficient simulations. The predictive simulation studies are carried out for JT-60SA with the integrated code (TOPICS-IB/SONIC) and the characteristics of the divertor heat load after the H-mode transition is clarified. We also discuss about the temporal behavior of divertor characteristics after an ELM crash.

Journal Articles

A New framework for integrated simulation model using MPMD approach

Takayama, Arimichi*; Shimizu, Katsuhiro; Tomita, Yukihiro*; Takizuka, Tomonori

Journal of Plasma and Fusion Research SERIES, Vol.9, p.604 - 609, 2010/08

We introduce a new effective framework to combine computer codes into integrated simulation model. The framework employs MPMD (Multiple Program Multiple Data) approach and each computer code is written with MPI (Message Passing Interface) library. Adopting MPMD approach makes each computer code independent, which leads to the capability for maintenance and improvement of the integrated simulation model. The validity and usability of this approach is shown through a simple example model, which simulates the integrated divertor code, SONIC.

Journal Articles

Kinetic modelling of impurity transport in detached plasma for integrated divertor simulation with SONIC (SOLDOR/NEUT2D/IMPMC/EDDY)

Shimizu, Katsuhiro; Takizuka, Tomonori; Oya, Kaoru*; Inai, Kensuke*; Nakano, Tomohide; Takayama, Arimichi*; Kawashima, Hisato; Hoshino, Kazuo

Nuclear Fusion, 49(6), p.065028_1 - 065028_9, 2009/06

 Times Cited Count:58 Percentile:89.03(Physics, Fluids & Plasmas)

The self-consistent coupling of a Monte Carlo (MC) impurity code IMPMC to a divertor code SOLDOR/NEUT2D has been succeeded. MC modelling is required for impurity transport in order to take into account the kinetic effect and the complex dissociation processes of hydrocarbons. The integrated divertor code SONIC enables us to investigate the details of impurity transport including erosion/redeposition processes on the divertor plates by further coupling of an MC code EDDY. The dynamic evolution of X-point MARFE observed in JT-60U is investigated. The simulation results indicate that the hydrocarbons sputtered from the dome contribute to the enhanced radiation near the X-point. The kinetic effect of thermal force on the He transport is investigated for JT-60SA detached plasmas. Without the recycling, the kinetic effect improves the helium compression, compared with the conventional (fluid) evaluation. This effect is, however, masked by the recycling at the divertor targets.

Journal Articles

Kinetic modelling of impurity transport in detached plasma for integrated divertor simulation with SONIC (SOLDOR/NEUT2D/IMPMC/EDDY)

Shimizu, Katsuhiro; Takizuka, Tomonori; Oya, Kaoru*; Inai, Kensuke*; Nakano, Tomohide; Takayama, Arimichi*; Kawashima, Hisato; Hoshino, Kazuo

Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 12 Pages, 2008/10

The self-consistent coupling of an MC impurity code IMPMC to a divertor code SOLDOR/NEUT2D is succeeded by overcoming the intrinsic problems of Monte Carlo (MC) modelling for impurity transport. MC modelling for impurity transport is required in order to take into account the kinetic effect and the complex dissociation processes of hydrocarbons. The integrated divertor code SONIC enables us to investigate the details of impurity transport including erosion/redeposition processes on the divertor plates by further coupling of an MC code EDDY. The dynamic evolution of X-point MARFE observed in JT-60U is investigated. The simulation results indicate that the hydrocarbons sputtered from the dome contribute directly to the enhanced radiation near the X-point. Without the recycling, the kinetic effect of the thermal force improves the helium compression, compared with the conventional (fluid) evaluation. This effect is, however, masked by the recycling at the divertor targets.

Journal Articles

Reduction of sheath potential and particle flux at a target plate by negatively charged dust particles

Tomita, Yukihiro*; Smirnov, R.*; Chutov, Y.*; Takayama, Arimichi*; Takizuka, Tomonori

Contributions to Plasma Physics, 44(1-3), p.162 - 167, 2004/04

 Times Cited Count:2 Percentile:6.52(Physics, Fluids & Plasmas)

Electrostatic potential formation due to negatively charged dust particles near a divertor plate is studied by one-dimensional kinetic analysis. It is shown that the negatively charged dust particles reduce the ion-sheath potential drop in front of the plate. Dust particles with a large radius (100 micron) reduce the potential drop significantly despite the low dust-to-plasma density ratio ($$sim$$10to-8). The plasma particle flux is reduced appreciably by the absorption by the dust particles.

Journal Articles

Particle simulation study of dust particle dynamics in sheaths

Smirnov, R.*; Tomita, Yukihiro*; Takizuka, Tomonori; Takayama, Arimichi*; Chutov, Y.*

Contributions to Plasma Physics, 44(1-3), p.150 - 156, 2004/04

 Times Cited Count:10 Percentile:32.11(Physics, Fluids & Plasmas)

Dynamics of dust particles in a divertor plasma is simulated using numerical solutions of dust momentum and charging equations in an electrostatic sheath and an ionizing presheath. Spatial distribution of plasma parameters in a divertor are obtained with particle simulations including ionization by electron-impact. We found that dust particles with a larger radius are incapable to come off a divertor plate. Middle-size dust particles come off the plate but come back to the plate. Smaller dust particles come off the plate and reach an equilibrium position in the divertor plasma.

Journal Articles

Reduction of sheath potential and dust ion-acoustic wave by negatively charged dust particles

Tomita, Yukihiro*; Smirnov, R.*; Chutov, Y.*; Takayama, Arimichi*; Takizuka, Tomonori

Purazuma, Kaku Yugo Gakkai-Shi, 6, p.429 - 432, 2004/00

Formation of an electrostatic potential due to negatively charged dust particles near a target plate was studied by one-dimensional kinetic analysis. Immovable dust particles are distributed uniformly inside a system. It is clarified that the negatively charged dust particles reduce the ion-sheath drop. A threshold dust density makes the electric field at the target plate zero. The stationary oscillation appears in the electrostatic potential for the dust density above the threshold. We confirm that this oscillation is the Dust Ion-Acoustic Wave with a wave length of the order of Debye length, where dust charges are effective to determine the coefficient.

Journal Articles

Dynamics of dust particles coming off a wall in sheath and presheath

Smirnov, R.*; Tomita, Yukihiro*; Takizuka, Tomonori; Takayama, Arimichi*; Chutov, Y.*

Purazuma, Kaku Yugo Gakkai-Shi, 6, p.752 - 755, 2004/00

Dynamics of a single dust particle in near-wall plasma is studied in wide range of dust radii and masses. Dust motion and charging equations are solved in the plasma simulated for sheath and ionizing presheath using one-dimensional particle model. It was found that balance of electric and ion drag forces acting on the dust particle provides two critical dust radii differentiating motion of dust started at the wall between pinned against the wall, short and long-range oscillating. Delayed charging causes the mass dependence of the second critical radius until transition from short to long-range oscillations becomes undistinguishable.

Journal Articles

Particle simulation study of dust particle dynamics in sheaths

Smirnov, R.*; Tomita, Yukihiro*; Takizuka, Tomonori; Takayama, Arimichi*; Chutov, Y.*

NIFS-784, 9 Pages, 2003/10

Dynamics of dust particles in a divertor plasma is simulated using numerical solutions of dust momentum and charging equations. Spatial distributions of plasma parameters in a divertor are obtained with particle simulations including electron-impact ionization. We find that the large-radius dust particles are not released from the divertor plate. The middle-size-radius particles are released but retuned to the plate. The small-radius particles can be released from the plate.

Oral presentation

Integrated divertor modelling of impurity transport in detached plasma

Shimizu, Katsuhiro; Takizuka, Tomonori; Oya, Kaoru*; Inai, Kensuke*; Nakano, Tomohide; Takayama, Arimichi*; Kawashima, Hisato; Hoshino, Kazuo

no journal, , 

An integrated divertor simulation code SONIC has been developed. The self-consistent coupling of a Monte Carlo (MC) impurity code IMPMC to a divertor code SOLDOR/NEUT2D is succeeded by overcoming the intrinsic problems of MC modelling for impurity transport. MC modelling for impurity transport is required in order to take into account the kinetic effect and the complex dissociation processes of hydrocarbons. The dynamic evolution of X-point MARFE observed in JT-60U is investigated. The simulation results indicate that the hydrocarbons sputtered from the dome contribute to the enhanced radiation near the X-point. Without the recycling, the kinetic effect of the thermal force improves the helium compression, compared with the conventional (fluid) evaluation. This effect is, however, masked by the recycling at the divertor targets.

Oral presentation

Integrated modelling of core and SOL/divertor transports

Shimizu, Katsuhiro; Takizuka, Tomonori; Hoshino, Kazuo; Honda, Mitsuru; Hayashi, Nobuhiko; Takayama, Arimichi*; Fukuyama, Atsushi*; Yagi, Masatoshi*

no journal, , 

In the integrated divertor code (SONIC), the particle and heat fluxes at the core edge are fixed at the given values as input parameters. However, these fluxes should be essentially determined by the plasma transport at the core edge. On the other hand, the SOL/divertor plasma has a strong effect on the core edge plasma through the particle source, the charge exchange loss and the impurity radiation. In order to study the divertor characteristics including such interactions, SONIC should be consistently coupled to a tokamak transport code. This project has started under the framework of Burning Plasma Simulation Initiative (BPSI) in Japan. On such code integration, it is serious problems that each code has been developed independently by different researcher and that integration must be performed with code improvement. We have developed a new MPMD (Multiple Program Multiple Data) computing system to solve such problems.

Oral presentation

Change of divertor characteristics after H-mode transition

Shimizu, Katsuhiro; Takizuka, Tomonori; Hoshino, Kazuo; Honda, Mitsuru; Hayashi, Nobuhiko; Takayama, Arimichi*; Fukuyama, Atsushi*; Yagi, Masatoshi*

no journal, , 

The establishment of impurity control is indispensable to achieve the fusion reactors. For such purpose, we have developed the modelling of impurity generation and transport, and carried out the simulation study on divertor transport. Such divertor simulations have been performed by giving the boundary condition of particle and heat fluxes at a certain magnetic surface in the core plasma near the separatrix. Since the core confinement and the SOL-divertor characteristics are significantly affected each other, above core boundary condition could not simply be given as input parameters. In this paper, we have developed the self-consistent integrated modelling of 1D core transport (TOPICS-IB) and 2D SOL/divertor transport (SONIC). Dynamic change in particle and heat fluxes into the SOL region after an H-mode of JT-60SA transition has been studied. We also discuss about the temporal heat flux onto the divertor plates after an ELM crash.

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