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Journal Articles

Development of a drift-kinetic simulation code for estimating collisional transport affected by RMPs and radial electric field

Kanno, Ryutaro*; Nunami, Masanori*; Satake, Shinsuke*; Matsuoka, Seikichi; Takamaru, Hisanori*

Contributions to Plasma Physics, 56(6-8), p.592 - 597, 2016/08

 Times Cited Count:2 Percentile:15.21(Physics, Fluids & Plasmas)

A drift-kinetic $$delta f$$ simulation code is developed for estimating collisional transport in quasi-steady state of toroidal plasma affected by resonant magnetic perturbations and radial electric field. In this paper, validity of the code is confirmed through several test calculations. It is found that radial electron flux is reduced by positive radial-electric field, although radial diffusion of electron is strongly affected by chaotic field-lines under an assumption of zero electric field.

Journal Articles

Edge radial electric field formation after the L-H transition on JT-60U

Kamiya, Kensaku; Matsunaga, Go; Honda, Mitsuru; Miyato, Naoaki; Urano, Hajime; Kamada, Yutaka; Ida, Katsumi*; Ito, Kimitaka*; JT-60 Team

Contributions to Plasma Physics, 54(4-6), p.591 - 598, 2014/06

 Times Cited Count:6 Percentile:35.23(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Simulation study of nonlocal transport from edge to core in tokamak plasmas

Yagi, Masatoshi; Matsuyama, Akinobu; Miyato, Naoaki; Takizuka, Tomonori*

Contributions to Plasma Physics, 54(4-6), p.363 - 367, 2014/06

 Times Cited Count:0 Percentile:0.01(Physics, Fluids & Plasmas)

Journal Articles

Development of the backflow model for simplified impurity exhaust in Monte-Carlo calculation

Hoshino, Kazuo; Shimizu, Katsuhiro; Kawashima, Hisato; Takizuka, Tomonori*; Nakano, Tomohide; Ide, Shunsuke

Contributions to Plasma Physics, 54(4-6), p.404 - 408, 2014/06

 Times Cited Count:14 Percentile:64.41(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Integrated simulation study of ELM pacing by pellet injection in ITER

Hayashi, Nobuhiko; Aiba, Nobuyuki; Takizuka, Tomonori*; Oyama, Naoyuki

Contributions to Plasma Physics, 54(4-6), p.599 - 604, 2014/06

 Times Cited Count:0 Percentile:0.01(Physics, Fluids & Plasmas)

Journal Articles

Simple and fast Poisson solver with arbitrary boundary shape and condition for PIC simulation

Takizuka, Tomonori*; Azuma, Shuhei*; Fukuyama, Atsushi*; Shimizu, Katsuhiro

Contributions to Plasma Physics, 54(4-6), p.388 - 393, 2014/06

 Times Cited Count:1 Percentile:6.89(Physics, Fluids & Plasmas)

Particle-in-cell (PIC) simulations are the very powerful method to understand physics of edge plasmas in fusion devices. Poisson solver with a regular grid in a rectangular vessel is very fast, but it cannot simply be applicable to simulations in complicated divertor configuration. In this paper, a simple and fast Poisson solver with arbitrary boundary shape and condition for PIC simulation is proposed. Boundary points are essential for this Poisson solver, on which the charge density is appropriately given and the boundary condition is satisfied. For particle simulations in the open system, it is necessary to distinguish whether a traced particle moves freely or hits the wall boundary during a time step. A new method for PIC simulation to discriminate a particle position before the boundary or beyond the boundary is also presented.

Journal Articles

Simulation study of an extended divertor leg for heat control in the SlimCS DEMO reactor

Hoshino, Kazuo; Shimizu, Katsuhiro; Asakura, Nobuyuki; Takizuka, Tomonori; Nakamura, Makoto; Tobita, Kenji

Contributions to Plasma Physics, 52(5-6), p.550 - 554, 2012/06

 Times Cited Count:18 Percentile:66.66(Physics, Fluids & Plasmas)

The power handling in the divertor is one of the most important issues for fusion tokamak reactor design. In this study, the effect of the divertor leg length on the power handling in the SlimCS DEMO reactor is investigated for future divertor design. The SONIC simulation shows enhancement of recycling in the outer divertor region due to effects of the long divertor leg and deep V-shaped corner. As a result, the ion and electron temperature at the outer divertor significantly decreases. In addition, peak of the Ar impurity radiation, which is located close to the outer divertor target in the standard divertor geometry, moves upstream. The former decreases the heat load to the outer divertor due to the ion conduction and convection, and the latter reduces the heat load due to the impurity radiation. The peak of the total heat load on the outer divertor decreases by about 30%.

Journal Articles

Simulation study of L/H transition with self-consistent integrated modelling of core and SOL/divertor transport

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

Contributions to Plasma Physics, 52(5-6), p.372 - 378, 2012/06

 Times Cited Count:4 Percentile:20.17(Physics, Fluids & Plasmas)

Journal Articles

Characterization of the JT-60U divertor plasma region during the formation of a strong radiation

Koubiti, M.*; Nakano, Tomohide; Capes, H.*; Marandet, Y.*; Mekkaoui, A.*; Mouret, L.*; Rosato, J.*; Stamm, R.*

Contributions to Plasma Physics, 52(5-6), p.455 - 459, 2012/06

 Times Cited Count:4 Percentile:20.17(Physics, Fluids & Plasmas)

The spectral profile of C IV ($$n$$=6-7) measured from the strong radiation zone (X-point MARFE) in a detached plasma of JT-60U with a high resolution spectrometer was analyzed by PPP code. In the previous analysis, a spectral profile calculated by the PPP code with an input of single pair of electron density and temperature was compared to the measured spectral profile. It was found that the spectral profiles measured around the X-point MARFE were reproduced with the calculated spectral profile but the ones measured at the center of the X-point MARFE were not. In the present analysis, two spectral profiles were calculated with two pairs of electron density and temperature and were summed up, leading to successful reproduction of the measured spectral profile. The two pairs of electron density and temperature used for the calculation were 1$$times$$10$$^{20}$$ m$$^{-3}$$ and 23.0 eV, and 6$$times$$10$$^{20}$$ m$$^{-3}$$ and 2.5 eV, respectively, with a mixture ratio of 65:35.

Journal Articles

Two-temperature warm dense matter produced by ultrashort Extreme Vacuum Ultraviolet-Free Electron Laser (EUV-FEL) pulse

Inogamov, N. A.*; Faenov, A. Ya.*; Zhakhovsky, V. V.*; Pikuz, T. A.*; Skobelev, I. Yu.*; Petrov, Y. V.*; Khokhlov, V. A.*; Shepelev, V. V.*; Anisimov, S. I.*; Fortov, V. E.*; et al.

Contributions to Plasma Physics, 51(5), p.419 - 426, 2011/06

 Times Cited Count:19 Percentile:67.23(Physics, Fluids & Plasmas)

Warm dense matter, arising under the action of ultrashort EUV-FEL pulse onto LiF dielectric crystal, is characterized by high temperature of conduction electrons, with their number density achieving values of the order of atom number density at maximum laser fluences in our experiments. Expansion of matter, heated and pressurized through the electron-ion energy exchange, gives rise to the spallative ablation at small fluences and gaseous outflow from a target in the case of large fluences. Ablation threshold is low in comparison with a longer nanosecond XRL.

Journal Articles

Accumulation process of high-Z impurity in toroidal rotating tokamak plasma

Hoshino, Kazuo; Takizuka, Tomonori; Nakano, Tomohide

Contributions to Plasma Physics, 50(3-5), p.386 - 391, 2010/05

 Times Cited Count:6 Percentile:26.32(Physics, Fluids & Plasmas)

The accumulation process of high-Z impurity in toroidal rotating tokamak plasma is investigated. A new inward pinch of high-Z impurity due to the ionization/recombination processes is derived using an analytical model. This inward pinch is driven by the large deviation of a drift orbit from a magnetic surface and the resultant variation of the charge state along the drift orbit. The pinch velocity increases with increasing toroidal rotation speed in both the co- direction and the ctr-direction. The inward pinch expected by the analytical model is really observed in the numerical simulation using the IMPGYRO code.

Journal Articles

Modelling of ion kinetic effects for SOL flow formation

Takizuka, Tomonori; Hoshino, Kazuo; Shimizu, Katsuhiro; Yagi, Masatoshi*

Contributions to Plasma Physics, 50(3-5), p.267 - 272, 2010/05

 Times Cited Count:6 Percentile:26.32(Physics, Fluids & Plasmas)

The plasma flow in the scrape-off layer (SOL) plays an important role for the control of heat and particle including impurity in magnetic fusion reactors. SOL flow patterns have recently been studied by the particle simulations, and the effects of finite-orbit-size of ions are found to be essential for the flow-pattern formation. Based on these simulation results, a new model of the edge plasma flow is developed by introducing the "ion-orbit-induced flow" to the fluid equations. A tokamak plasma is divided into three regions; core region, transition layer and SOL region. The "ion-orbit-induced flow" is modeled by separating untrapped part and trapped part, and by taking account the collision effect and poloidal distribution. The "ion-orbit-induced flow" becomes large at the edge region.

Journal Articles

Effect of source and sink on heat transport in the SOL

Froese, A.*; Takizuka, Tomonori; Yagi, Masatoshi

Contributions to Plasma Physics, 50(3-5), p.273 - 278, 2010/05

 Times Cited Count:8 Percentile:33.62(Physics, Fluids & Plasmas)

Electron heat transport parallel to magnetic field in the SOL is studied via fully kinetic simulations using the one-dimensional particle code PARASOL. The heat flux in fluid model is usually approximated with the Spitzer-Harm value in the collisional case, and the free-streaming value adjusted by a limiting factor in the collisionless case. While typically taken to be a constant 0.1, we survey the dependence of the limiting factor with respect to plasma parameters (collisionality, type of source and sink etc). It is found that the limiting factor is strongly affected by the collisionality, covering magnitude from 0.01 to 10. A high-energy tail plays an important role for this large variation. Langevin heating source maintains a Maxwellian electron energy distribution, and the limiting factor remains between 0.05 and 0.3. It is also found that the radiation loss is essential to increase the limiting factor.

Journal Articles

Interaction of short laser pulses in wavelength range from infrared to X-ray with metals, semiconductors, and dielectrics

Inogamov, N. A.*; Faenov, A. Ya.*; Zhakhovskii, V. V.*; Skobelev, I. Y.*; Khokhlov, V. A.*; Kato, Yoshiaki*; Tanaka, Momoko; Pikuz, T. A.*; Kishimoto, Maki; Ishino, Masahiko; et al.

Contributions to Plasma Physics, 51(4), p.361 - 366, 2010/05

 Times Cited Count:19 Percentile:67.23(Physics, Fluids & Plasmas)

Journal Articles

Analysis of particle pumping using SOLDOR/NEUT2D code in the JT-60U tokamak

Kawashima, Hisato; Shimizu, Katsuhiro; Takizuka, Tomonori

Contributions to Plasma Physics, 48(1-3), p.158 - 163, 2008/03

 Times Cited Count:5 Percentile:22.76(Physics, Fluids & Plasmas)

To characterize the divertor pumping for particle control in the SOL/divertor and to extrapolate to future devices, simulations using the SOLDOR/NEUT2D code are performed on JT-60U. It reproduces fairly well the neutral pressure and pumping flux in the exhaust chamber at experiment. It shows that higher pumping capability within is necessary for active particle control. In order to improve pumping capability, we analyze the inward/outward neutral flux into/from the exhaust chamber with introducing the pumping efficiency (pumping flux/generating flux). We find that the efficiency is increased by shortening the distance from pumping slot to strike point on the target or tilting the targets vertically. For the design study of JT-60SA divertor, an increase of the efficiency is indicated with narrowing the pumping slot width. To understand these phenomena, we are identifying the role of neutral processes such as ionization, charge-exchange and so on.

Journal Articles

Integrated ELM simulation with edge MHD stability and transport of SOL-divertor plasmas

Hayashi, Nobuhiko; Takizuka, Tomonori; Aiba, Nobuyuki; Ozeki, Takahisa; Oyama, Naoyuki

Contributions to Plasma Physics, 48(1-3), p.196 - 200, 2008/03

 Times Cited Count:3 Percentile:14.13(Physics, Fluids & Plasmas)

The effect of the pressure profile on the energy loss caused by edge localized modes (ELMs) has been investigated by using an integrated simulation code TOPICS-IB based on a transport code with a stability code for the peeling-ballooning modes and a model for scrape-off-layer and divertor plasmas. The steep pressure gradient inside the pedestal top is found to broaden the region of the ELM enhanced transport through the broadening of eigenfunctions and enhance the ELM energy loss. The ELM energy loss in the simulation becomes larger than 15% of the pedestal energy, as is shown in the database of multi-machine experiments.

Journal Articles

Effect of radial transport loss on the asymmetry of ELM heat flux

Takizuka, Tomonori; Oyama, Naoyuki; Hosokawa, Masanari*

Contributions to Plasma Physics, 48(1-3), p.207 - 211, 2008/03

 Times Cited Count:4 Percentile:18.43(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Extension of IMPMC code toward time evolution simulation

Shimizu, Katsuhiro; Takizuka, Tomonori; Kawashima, Hisato

Contributions to Plasma Physics, 48(1-3), p.270 - 274, 2008/03

 Times Cited Count:5 Percentile:22.76(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Effect of oblieque magnetic field on release conditions of dust particle from plasma-facing wall

Tomita, Yukihiro*; Smirnov, R. D.*; Takizuka, Tomonori; Tskhakaya, D.*

Contributions to Plasma Physics, 48(1-3), p.285 - 289, 2008/03

 Times Cited Count:6 Percentile:26.88(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Effect of SOL decay length on modeling of divertor detachment by using simple core-SOL-divertor model

Hiwatari, Ryoji*; Hatayama, Akiyoshi*; Takizuka, Tomonori

Contributions to Plasma Physics, 48(1-3), p.174 - 178, 2008/03

 Times Cited Count:0 Percentile:0.01(Physics, Fluids & Plasmas)

no abstracts in English

29 (Records 1-20 displayed on this page)