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Journal Articles

Inter-code comparison benchmark between DINA and TSC for ITER disruption modelling

Miyamoto, Seiji*; Isayama, Akihiko; Bandyopadhyay, I.*; Jardin, S. C.*; Khayrutdinov, R. R.*; Lukash, V.*; Kusama, Yoshinori; Sugihara, Masayoshi*

Nuclear Fusion, 54(8), p.083002_1 - 083002_19, 2014/08

 Times Cited Count:32 Percentile:82.89(Physics, Fluids & Plasmas)

Two well-established simulation codes, DINA and TSC, are compared with each other using benchmark scenarios in order to validate the ITER 2D disruption modelling by those codes. Although the simulation models employed in those two codes ought to be equivalent in the resistive time scale, it has long been unanswered whether the one of the two codes is really able to reproduce the other result correctly, since a large number of code-wise differences render the comparison task exceedingly complicated. In this paper, it is demonstrated that after simulations are set up accounting for the model differences, in general, a good agreement is attained on a notable level, corroborating the correctness of the code results. When the halo current generation and its poloidal path in the first wall are included, however, the situation is more complicated. Because of the surface averaged treatment of the magnetic field (current density) diffusion equation, DINA can only approximately handle the poloidal electric currents in the first wall that cross field lines. Validation is carried out for DINA simulations of halo current generation by comparing with TSC simulations, where the treatment of halo current dynamics is more justifiable. The particularity of each code is depicted and the consequence in ITER disruption prediction is discussed.

Journal Articles

TSC modelling of major disruption and VDE events in NSTX and ASDEX-upgrade and predictions for ITER

Bandyopadhyay, I.*; Gerhardt, S.*; Jardin, S.*; Sayer, R. O.*; Nakamura, Yukiharu*; Miyamoto, Seiji; Pautasso, G.*; Sugihara, Masayoshi*; ASDEX Upgrade Team*; NSTX Team*

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2010/10

Vertical Displacement Events (VDEs) and Major Disruptions (MDs) of the plasma current will induce large electromagnetic forces on the ITER machine. Estimation of these forces based on accurate modeling of these events is necessary for a robust ITER design. Originally the estimates for electromagnetic forces on ITER were carried out with the help of DINA simulations. However, since simulations of these events may be significantly influenced by model assumptions of a given code it is important to validate the results against other codes like TSC, as also benchmark and update the codes with experimental data. In this paper, we present TSC modeling of the VDE and MD events in NSTX and ASDEX-U devices, which help in improving and validating the models used in the code. The predictive modeling results for ITER with the updated code, including the force predictions, are also presented.

Journal Articles

Progress in the ITER physics basis, 3; MHD stability, operational limits and disruptions

Hender, T. C.*; Wesley, J. C.*; Bialek, J.*; Bondeson, A.*; Boozer, A. H.*; Buttery, R. J.*; Garofalo, A.*; Goodman, T. P.*; Granetz, R. S.*; Gribov, Y.*; et al.

Nuclear Fusion, 47(6), p.S128 - S202, 2007/06

 Times Cited Count:879 Percentile:100(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Intermittent $$beta$$ collapse after NBCD turn-off in JT-60U fully non-inductive reversed shear discharges

Takei, Nahoko; Nakamura, Yukiharu; Ushigome, Masahiro*; Suzuki, Takahiro; Aiba, Nobuyuki; Takechi, Manabu; Tobita, Kenji; Takase, Yuichi*; Fukuyama, Atsushi*; Jardin, S. C.*

Plasma Physics and Controlled Fusion, 49(3), p.335 - 345, 2007/03

 Times Cited Count:7 Percentile:25.9(Physics, Fluids & Plasmas)

Non-disruptive $$beta$$-collapses with a regular intermittency have been observed after a forced turn-off of neutral beam current drive (NBCD) in JT-60U fully non-inductive, reversed shear (RS) discharges. Self-consistent transport simulations with improved core confinement and linear MHD stability analysis have first clarified that redistribution of return current induced after the NBCD turn-off lowers the safety factor of magnetic shear reversal, leading to the n =1 kink-ballooning instability with localized modes around internal transport barrier (ITB). It was also pointed out that an increase of the bootstrap current under continuous NB heating can lead to ITB reconstruction and thus causes subsequent beta-collapses.

Journal Articles

A Simulation study on inductive ITB control in reversed shear tokamak discharges

Nakamura, Yukiharu; Tobita, Kenji; Fukuyama, Atsushi*; Takei, Nahoko; Takase, Yuichi*; Ozeki, Takahisa; Jardin, S. C.*

Nuclear Fusion, 46(8), p.S645 - S651, 2006/08

 Times Cited Count:3 Percentile:10.81(Physics, Fluids & Plasmas)

A self-consistent simulation, including a model for improved core energy confinement, demonstrates that externally applied, inductive current perturbations can be used to control both the location and strength of internal transport barriers (ITBs) in a fully non-inductive tokamak discharge. We find that ITB structures formed with broad non-inductive current sources such as LHCD are more readily controlled than those formed by localized sources such as ECCD. Through this external control of the magnetic shear profile, we can maintain the ITB strength which is otherwise prone to deteriorate when the bootstrap current increases.

Journal Articles

Summary of the International Energy Agency Workshop on Burning Plasma Physics and Simulation

Donn$'e$, A. J. H.*; Fasoli, A.*; Ferron, J.*; Goncalves, B.*; Jardin, S. C.*; Miura, Yukitoshi; Noterdaeme, J.-M.*; Ozeki, Takahisa

Fusion Science and Technology, 49(1), p.79 - 85, 2006/01

no abstracts in English

Journal Articles

Numerical simulation on current spike behaviour of JT-60U disruptive plasmas

Takei, Nahoko; Nakamura, Yukiharu; Tsutsui, Hiroaki*; Yoshino, Ryuji; Kawano, Yasunori; Ozeki, Takahisa; Tobita, Kenji; Iio, Shunji*; Shimada, Ryuichi*; Jardin, S. C.*

Plasma Physics and Controlled Fusion, 46(12), p.1815 - 1830, 2004/12

 Times Cited Count:3 Percentile:10.02(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

TSC simulation of ITB crash and following disruption dynamics on JT-60U high-$$beta$$ reversed shear plasmas

Takei, Nahoko; Nakamura, Yukiharu; Kawano, Yasunori; Tsutsui, Hiroaki*; Ozeki, Takahisa; Tobita, Kenji; Sugihara, Masayoshi; Iio, Shunji*; Shimada, Ryuichi*; Jardin, S. C.*

Europhysics Conference Abstracts, 28G, 4 Pages, 2004/00

no abstracts in English

Journal Articles

Axisymmetric MHD simulation of ITB crash and following disruption dynamics of tokamak plasmas with high bootstrap current

Takei, Nahoko; Nakamura, Yukiharu; Kawano, Yasunori; Tsutsui, Hiroaki*; Ozeki, Takahisa; Tobita, Kenji; Sugihara, Masayoshi; Iio, Shunji*; Shimada, Ryuichi*; Jardin, S. C.*

Journal of Plasma and Fusion Research SERIES, Vol.6, p.554 - 557, 2004/00

no abstracts in English

Journal Articles

Current profile behavior during ramping-up phase in high bootstrap current tokamak plasmas

Nakamura, Yukiharu; Tsutsui, Hiroaki*; Takei, Nahoko*; Shirai, Hiroshi; Sugihara, Masayoshi; Gribov, Y.*; Ozeki, Takahisa; Tobita, Kenji; Iio, Shunji*; Jardin, S. C.*

Journal of Plasma and Fusion Research SERIES, Vol.6, p.196 - 198, 2004/00

no abstracts in English

Journal Articles

TSC modelling of current ramp scenarios with ITB-Generated bootstrap currents in JT-60U reversed shear discharges

Nakamura, Yukiharu; Tsutsui, Hiroaki*; Takei, Nahoko*; Sakamoto, Yoshiteru; Fujita, Takaaki; Sugihara, Masayoshi; Ozeki, Takahisa; Tobita, Kenji; Konishi, Satoshi; Iio, Shunji*; et al.

Europhysics Conference Abstracts, 27A, 4 Pages, 2003/00

no abstracts in English

Journal Articles

Axisymmetric disruption dynamics including current profile changes in the ASDEX-Upgrade tokamak

Nakamura, Yukiharu; Pautasso, G.*; Gruber, O.*; Jardin, S. C.*

Plasma Physics and Controlled Fusion, 44(8), p.1471 - 1481, 2002/08

 Times Cited Count:12 Percentile:38.29(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Neutral point validation studies on JT-60U, alcator C-Mod and ASDEX-upgrade tokamaks

Nakamura, Yukiharu; Yoshino, Ryuji; Granetz, R. S.*; Pautasso, G.*; Gruber, O.*; Jardin, S. C.*

Purazuma, Kaku Yugo Gakkai-Shi, 78(4), p.347 - 355, 2002/04

no abstracts in English

Oral presentation

Non-inductive operation scenario of plasma current ramp-down in CS-less, advanced tokamak reactor

Nakamura, Yukiharu; Tobita, Kenji; Takei, Nahoko; Takase, Yuichi*; Fukuyama, Atsushi*; Nishio, Satoshi; Sato, Masayasu; Jardin, S. C.*

no journal, , 

no abstracts in English

Oral presentation

External control of internal transport barriers using inductive current perturbation in noninductive tokamak plasmas

Nakamura, Yukiharu; Tobita, Kenji; Fukuyama, Atsushi*; Takei, Nahoko; Takase, Yuichi*; Ozeki, Takahisa; Jardin, S. C.*

no journal, , 

no abstracts in English

Oral presentation

A Simulation study on burning profile tailoring of steady state, high bootstrap current tokamaks

Nakamura, Yukiharu; Takei, Nahoko; Tobita, Kenji; Sakamoto, Yoshiteru; Fujita, Takaaki; Fukuyama, Atsushi*; Jardin, S. C.*

no journal, , 

From the aspect of fusion burn control in steady state DEMO plant, the significant challenges are to maintain its high power burning state of $$sim$$ 3 - 5 GW without burning instability, and also to keep its desired burning profile relevant with internal transport barrier (ITB) that generates high bootstrap current. A self-consistent simulation has pointed out that in the high power fusion DEMO plant there is a close, nonlinear interplay between the fusion burnup and the current source of non-inductive, ITB-generated bootstrap current. Consequently, as much distinct from usual burning conditions with lower power ($$<$$$$<$$ 1GW), the self-ignited fusion burn at a high power burning state of $$sim$$ 3 - 5 GW becomes so strongly self-organized that any of external means except fuelling can not provide the effective control of the stable fusion burn. The paper presents a simulation modeling of the burning stability coupled with the self-ignited fusion burn and the structure-formation of the ITB.

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