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論文

Integrated modelling of toroidal rotation with the 3D non-local drift-kinetic code and boundary models for JT-60U analyses and predictive simulations

本多 充; 佐竹 真介*; 鈴木 康浩*; 吉田 麻衣子; 林 伸彦; 神谷 健作; 松山 顕之; 篠原 孝司; 松永 剛; 仲田 資季; et al.

Nuclear Fusion, 55(7), p.073033_1 - 073033_11, 2015/07

 被引用回数:5 パーセンタイル:65.51(Physics, Fluids & Plasmas)

The integrated simulation framework for toroidal momentum transport is developed, which self-consistently calculates the neoclassical toroidal viscosity (NTV), the radial electric field $$E_r$$ and the resultant toroidal rotation $$V_phi$$ together with the scrape-off-layer(SOL)-physics based boundary model. The coupling of three codes, the 1.5D transport code, TOPICS, the 3D equilibrium code, VMEC and the 3D $$delta f$$ drift-kinetic equation solver, FORTEC-3D, makes it possible to calculate the NTV due to the non-axisymmetric perturbed magnetic field caused by toroidal field coils. Analyses reveal that the NTV significantly influences $$V_phi$$ in JT-60U and $$E_r$$ holds the key to determine the NTV profile. The sensitivity of the $$V_phi$$ profile to the boundary rotation necessitates a boundary condition modelling for toroidal momentum. Owing to the high-resolution measurement system in JT-60U, the $$E_r$$ gradient is found to be virtually zero at the separatrix regardless of toroidal rotation velocities. Focusing on $$E_r$$, the boundary model of toroidal momentum is developed in conjunction with the SOL/divertor plasma code D5PM. This modelling realizes self-consistent predictive simulations for operation scenario development in ITER.

論文

Analysis of tungsten transport in JT-60U plasmas

清水 友介*; 藤田 隆明*; 有本 英樹*; 仲野 友英; 星野 一生; 林 伸彦

Plasma and Fusion Research (Internet), 10(Sp.2), p.3403062_1 - 3403062_4, 2015/07

In JT-60U, it has been observed that accumulation of tungsten is enhanced with increasing the toroidal rotation in the opposite direction (CTR-rotation) to the plasma current in H-mode plasmas. Two models for convective transport, pinch due to the toroidal rotation (PHZ pinch) and the radial electric field (Er pinch) were proposed. We introduce these two pinch models into integrated transport code TOTAL, and study dependence of the tungsten accumulation on the toroidal rotation. In the high toroidal rotation velocity, we obtained the tungsten accumulation four times as large as in the low one. The model reproduces the trend observed in the experiment.

論文

Advance in integrated modelling towards prediction and control of JT-60SA plasmas

林 伸彦; 本多 充; 白石 淳也; 宮田 良明; 若月 琢馬; 星野 一生; 藤間 光徳; 鈴木 隆博; 浦野 創; 清水 勝宏; et al.

Europhysics Conference Abstracts (Internet), 39E, p.P5.145_1 - P5.145_4, 2015/06

Towards prediction and control of JT-60SA plasmas, we are developing codes/models which can describe physics/engineering factors, and integrating them to one code TOPICS. Physics modelling: Coupling with MINERVA/RWMaC code showed that MHD equilibrium variation by centrifugal force largely affects RWM stability and the toroidal rotation shear stabilizes RWM. Coupling with OFMC code for NB torques, 3D MHD equilibrium code VMEC and drift-kinetic code FORTEC-3D for NTV torque, and toroidal momentum boundary model, predicted the core rotation of $$sim$$2% of Alfv$'e$n speed for a ITER hydrogen L-mode plasma. Coupling with core impurity transport code IMPACT showed the accumulation of Ar seeded to reduce the divertor heat load is so mild that plasma performance can be recovered by additional heating in JT-60SA steady-state (SS) scenario. Simulations coupled with MARG2D code showed that plasma current can be ramped-up to reach $$beta_N ge$$3 with MHD modes stabilized by ideal wall and with no additional flux consumption of central solenoid in JT-60SA. Engineering modelling: Coupling with integrated real-time controller showed that simultaneous control of $$beta_N$$ and $$V_{loop}$$ is possible at $$beta_N ge$$4 in JT-60SA SS scenarios. MHD equilibrium control simulator MECS demonstrated equilibrium control during heating phase and collapse induced events within power supply capability of PF coils in JT-60SA.

論文

Current ramp-up scenario with reduced central solenoid magnetic flux consumption in JT-60SA

若月 琢馬; 鈴木 隆博; 林 伸彦; 白石 淳也; 井手 俊介; 高瀬 雄一*

Europhysics Conference Abstracts (Internet), 39E, p.P5.144_1 - P5.144_4, 2015/06

We have investigated reduction of the CS flux required in the plasma current ramp-up phase using non-inductive current drive in JT-60SA with an integrated modeling code suite (TOPICS). JT-60SA will be equipped with various types of neutral beams different in the beam trajectories and energies (85 keV and 500 keV). We have made a scenario in which the plasma current is ramped up from 0.6 MA to 2.1 MA in 150 s with no additional CS flux consumption by overdriving the plasma current ($$I_{rm NI} > I_{rm p}$$, $$I_{rm NI}$$ : non-inductively driven current and $$I_{rm p}$$ : plasma current) with neutral-beam-driven and bootstrap current. In order to achieve the current overdrive condition from 0.6 MA, the current drive by the lower energy neutral beam injection (85 keV) is effective. The higher energy neutral beam injection (500 keV) cannot be utilized in this early phase with a low plasma density due to a large shine through loss, while it can effectively be utilized in the later phase. We have also investigated ideal MHD instabilities using a linear ideal MHD stability analysis code (MARG2D). External kink modes can be stabilized in most of the time during the current ramp-up if there is a perfect conducting wall.

論文

Simulation of plasma current ramp-up with reduced magnetic flux consumption in JT-60SA

若月 琢馬; 鈴木 隆博; 林 伸彦; 白石 淳也; 井手 俊介; 高瀬 雄一*

Plasma Physics and Controlled Fusion, 57(6), p.065005_1 - 065005_12, 2015/06

 被引用回数:7 パーセンタイル:53.27(Physics, Fluids & Plasmas)

Current ramp-up with reduced central solenoid (CS) flux consumption in JT-60SA has been investigated using an integrated modeling code suite (TOPICS) with a turbulent model (CDBM). The plasma current can be ramped-up from 0.6 MA to 2.1 MA with no additional CS flux consumption if the plasma current is overdriven by neutral-beam-driven and bootstrap current. The time duration required for the current ramp-up without CS flux consumption becomes as long as 150s. In order to achieve the current overdrive condition from 0.6 MA, the current drive by a lower energy neutral beam (85 keV) is effective. A higher energy neutral beam (500 keV) cannot be utilized in this early phase due to large shine through loss, while it can be effectively utilized in the later phase. Therefore, the main current driver should be switched from the lower energy neutral beam to the higher energy neutral beam during the current ramp-up phase. As a result of an intensive auxiliary heating needed to overdrive the plasma current, plasma beta becomes high. Ideal MHD stabilities of such high beta plasmas have been investigated using a linear ideal MHD stability analysis code (MARG2D). External kink modes can be stabilized in most of the time during the current ramp-up if there is a perfectly conducting wall at the location of the stabilizing plate and the vacuum vessel of JT-60SA and the plasma has a broader pressure profile.

論文

Assessment of operational space for long-pulse scenarios in ITER

Polevoi, A. R.*; Loarte, A.*; 林 伸彦; Kim, H. S.*; Kim, S. H.*; Koechl, F.*; Kukushkin, A. S.*; Leonov, V. M.*; Medvedev, S. Yu.*; 村上 匡且*; et al.

Nuclear Fusion, 55(6), p.063019_1 - 063019_8, 2015/05

 被引用回数:23 パーセンタイル:13.62(Physics, Fluids & Plasmas)

The operational space ($$I_p$$-$$n$$) for long pulse scenarios of ITER was assessed by 1.5D core transport modelling with pedestal parameters predicted by the EPED1 code. The analyses include the majority of transport models presently used for interpretation of experiments and ITER predictions. The EPED1 code was modified to take into account boundary conditions predicted by SOLPS for ITER. In contrast with standard EPED1 assumptions, EPED1 with the SOLPS boundary conditions predicts no degradation of the pedestal pressure as density is reduced. Lowering the plasma density to $$n_e sim$$ 5-6 $$times$$ 10$$^{19}$$ m$$^{-3}$$ leads to an increased plasma temperature (similar pedestal pressure), which reduces the loop voltage and increases the duration of the burn phase to $$Delta t_{rm burn} sim$$ 1000 s with Q $$ge$$ 5 for $$I_p ge$$ 13 MA at moderate normalised pressure ($$beta_N sim$$ 2). These ITER plasmas require the same level of additional heating power as the reference Q = 10 inductive scenario at 15 MA. However, unlike the "hybrid" scenarios considered previously, these H-mode plasmas do not require specially shaped q profiles nor improved confinement in the core for the transport models considered in this study. Thus, these medium density H-mode plasma scenarios with $$I_p ge$$ 13 MA present an attractive alternative to hybrid scenarios to achieve ITER's long pulse Q $$ge$$ 5 and deserve further analysis and experimental demonstration in present tokamaks.

論文

Gyrokinetic analyses of core heat transport in JT-60U plasmas with different toroidal rotation direction

成田 絵美*; 本多 充; 林 伸彦; 浦野 創; 井手 俊介; 福田 武司*

Plasma and Fusion Research (Internet), 10, p.1403019_1 - 1403019_11, 2015/03

The internal transport barriers (ITBs) formed in the tokamak plasmas with the weak magnetic shear and the weak radial electric field shear are often observed and the pressure gradient at the ITB is not very steep. In such plasmas the electron temperature ITB is steeper for co toroidal rotation cases than that for counter rotation cases. Clarifying the relationship between the rotation direction and heat transport in the ITB region, dominant instabilities are examined by the flux-tube gyrokinetic code GS2 to show that the linear growth rates $$gamma$$ for the co and counter rotation cases are comparable in magnitude, but the counter case shows the more trapped electron mode like frequency. The ratio of the electron heat diffusivity to the ion's is higher for the counter-rotation case. The difference in the ratio between the two cases agrees with the experiment. Investigating the flow shear effect on $$gamma$$ reveals that its effect is not so large as to change the aforementioned tendency.

論文

Integrated modeling of toroidal rotation with the 3D non-local drift-kinetic code and boundary models for JT-60U analyses and predictive simulations

本多 充; 佐竹 真介*; 鈴木 康浩*; 吉田 麻衣子; 林 伸彦; 神谷 健作; 松山 顕之; 篠原 孝司; 松永 剛; 仲田 資季; et al.

Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10

The integrated framework for toroidal momentum transport is developed, which self-consistently calculates the neoclassical toroidal viscosity (NTV), the radial electric field $$E_r$$ and resultant toroidal rotation together with the scrape-off-layer (SOL) physics-based boundary model. The coupling of three codes, TOPICS, VMEC and FORTEC-3D, can calculate rotation caused by the NTV due to the non-axisymmetric perturbed magnetic field caused by toroidal field coils. It is found that the NTV influences toroidal rotation in JT-60U and $$E_r$$ holds the key to determine the NTV profile. The sensitivity of the toroidal rotation profile to the boundary rotation necessitates the boundary condition modeling. From the measurement in JT-60U, the $$E_r$$ gradient is found to be insensitive at the separatrix. Focusing on $$E_r$$, the boundary model of toroidal momentum is developed in conjunction with the SOL/divertor plasma code. This modeling realizes self-consistent predictive simulations for operation scenario development in ITER.

論文

Physics comparison and modelling of the JET and JT-60U core and edge; Towards JT-60SA predictions

Garcia, J.*; 林 伸彦; Baiocchi, B.*; Giruzzi, G.*; 本多 充; 井手 俊介; Maget, P.*; 成田 絵美*; Schneider, M.*; 浦野 創; et al.

Nuclear Fusion, 54(9), p.093010_1 - 093010_13, 2014/09

 被引用回数:31 パーセンタイル:9.56(Physics, Fluids & Plasmas)

Extensive physics analysis and modelling has been undertaken for the typical operational regimes of the tokamak devices JET and JT-60U with the aim of extrapolating present day experiments to JT-60SA, which shares important characteristics with both tokamaks. A series of representative discharges of two operational scenarios, H-mode and hybrid, have been used for this purpose. Predictive simulations of core turbulence, particle transport, current diffusion and pedestal pressure have been carried out with different combinations of models. The ability of the models for reproducing the experimental data is analysed and scenario calculations for JT-60SA are performed following an optimum set of models.

論文

Analysis of JT-60SA scenarios on the basis of JET and JT-60U discharges

Garcia, J.*; 林 伸彦; Giruzzi, G.*; Schneider, M.*; Joffrin, E.*; 井手 俊介; 坂本 宜照; 鈴木 隆博; 浦野 創; JT-60チーム; et al.

Europhysics Conference Abstracts (Internet), 38F, p.P1.029_1 - P1.029_4, 2014/06

Creation of JT-60SA scenarios is necessary in order to make deeper analyses: Fast ions, heating schemes, MHD. Validation exercise: a series of representative discharges of the three main operational scenarios, H-mode, hybrid and steady-state have been selected for each device in order to extrapolate to JT-60SA. An extensive analysis of the main physics similarities and differences among the discharges has been carried out in order to explain results. Using integrated modelling codes CRONOS and TOPICS, benchmark of the codes is done. Predictive core turbulence simulations have been carried out with three transport models: Bohm-GyroBohm, CDBM and GLF23. Particle transport is analyzed with GLF23. Pressure pedestal predictions are simulated with Cordey MHD scaling. Fully predictive simulations of temperatures, density and pedestal have been performed with GLF23 and CDBM models for the temperatures and GLF23 for the density. Calculations for JT-60SA are performed following the best combination of models found.

口頭

コアと周辺プラズマ輸送の統合モデルによるLH遷移のシミュレーション

清水 勝宏; 滝塚 知典*; 本多 充; 林 伸彦; 星野 一生; 福山 淳*; 矢木 雅敏

no journal, , 

コアとSOL/ダイバータ輸送のコンシステントな相互作用を含んだモデリングを開発した。すなわち、1.5次元コアコードTOPICS-IBと2次元ダイバータコードSONICの結合に成功した。CDBM輸送モデルを含んだこの統合コードを用いて、JT-60SAのシミュレーションを行った。CDBMモデルでは、E$$times$$Bシェアリング効果により、粒子と熱輸送が抑制される。このモデルを用いて、またコアとSOLとのコンシステントな境界条件の下に、LH遷移の再現に成功した。遷移の後、ダイバータプラズマの密度温度に、変動が見られることは興味深い。

口頭

トロイダルプラズマにおける外部磁場揺動による強制磁気再結合

石井 康友

no journal, , 

磁場に閉じ込められたプラズマに外部から磁場摂動が加わると摂動磁場に対応する共鳴面で強制磁場再結合が生じ、磁気島が形成され、閉じ込め磁場構造の変化を通じて、プラズマ閉じ込めに大きな影響を与える。この磁場再結合過程についてはMHD理論研究の対象としてこれまで多くの研究者によって調べられてきた。その多くは、再結合過程の基礎過程に関するもので、多くはスラブ形状、ないしは、円柱形状での現象を対象としている。核融合で対象とするプラズマはトロイダル形状であり、外部摂動が単一ヘリカルモードであったとしても、プラズマ中では、トロイダルモード間結合によって、多くのサイドバンド・モードが生成され、磁場構造の乱れに影響を与える。本研究では、軸対称トカマク・プラズマに対する外部摂動磁場の影響を数値シミュレーションによって調べた結果について報告する。

口頭

Numerical analyses of core heat transport in plasmas with different toroidal rotation profiles in JT-60U

成田 絵美*; 本多 充; 林 伸彦; 浦野 創; 井手 俊介; 福田 武司*

no journal, , 

In long-pulse ELMy H-mode plasmas with parabolic type ITB plasmas, it has been found that the direction of toroidal rotation influences the internal transport barrier of the electron temperature: the gradient of the temperature becomes steeper with increasing rotation in the co direction with respect to the plasma current. These plasmas have the normal magnetic shear, and the radial electric field shear in the core region is weak. In this study, core heat transport in these plasmas is analyzed with the gyrokinetic code GS2. As a result of the linear calculations, the difference in the real frequencies is found. Using these linear calculation results, the ratio of electron heat flux to ion's ($$Q_mathrm{e}/Q_mathrm{i}$$) is estimated with a quasilinear transport model. This estimation shows that the ratio is lower in co-rotating plasma. This result agrees with experimental observation. The influence of the shear in toroidal rotation on the linear growth rates is also discussed.

口頭

任意の軸対称平衡に適用できるNBCD高速解析法

藤田 隆明*; 濱松 清隆; 林 伸彦

no journal, , 

トカマクプラズマにおけるNBCD解析に必要な高速イオン電流を、トロイダル効果を考慮しつつ高速に求める手法として、固有関数展開により定常バウンス平均2次元フォッカープランク方程式を解く方法があり、原子力機構のACCOMEコードで使用されている。その定式化では円形断面平衡を仮定しており非円形断面平衡への適用に難があった。本研究では、一般的な軸対称平衡に対して同方法を定式化してACCOMEコードに実装し、軌道追跡モンテカルロコードやフォッカープランクコードとほぼ一致する結果を得た。

口頭

JT -60Uプラズマにおけるタングステン輸送の解析

清水 友介*; 藤田 隆明*; 有本 英樹*; 仲野 友英; 星野 一生; 林 伸彦

no journal, , 

JT-60UのHモードプラズマにおいてプラズマ電流と逆向きのトロイダル回転の増大とともにタングステンの蓄積が増加することが観測されている。これは従来の新古典輸送では説明できず、理論的な考察からトロイダル回転あるいは径電場に伴う2つのピンチモデルが提唱されている。本研究では、輸送コードTOTALに提唱されたピンチモデルを組み込み計算し、実験の傾向を再現する結果を得た。

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モデル妥当性確認と検証を伴ったJT-60SAプラズマ運転シナリオの統合モデリングの進展

林 伸彦; Jeronimo, G.*; 本多 充; 清水 勝宏; 星野 一生; 井手 俊介; Gerardo, G.*; 坂本 宜照; 鈴木 隆博; 浦野 創

no journal, , 

JT-60SAプラズマ運転シナリオの統合モデリングの進展を報告する。予測に最適なモデルを得るため、JT-60UとJETの実験データでモデルの妥当性を確認し、統合コードTOPICSとCRONOSで検証を行った。シミュレーションで運転シナリオ毎のプラズマ性能を調べ、最適なシナリオを開発している。その時、様々な物理を様々なタイプの統合モデリングで調べた。統合ダイバータコードSONICでAr入射によりダイバータ板への熱負荷を許容値以下にできた。不純物輸送コードをTOPICSに結合し、コアのAr蓄積量とその影響を調べている。その他の統合モデリングの現状についても報告する。

口頭

Gyrokinetic analyses of roles of toroidal rotation in core heat transport in JT-60U

成田 絵美*; 本多 充; 林 伸彦; 浦野 創; 井手 俊介; 福田 武司*

no journal, , 

The internal transport barriers (ITBs) formed in the tokamak plasmas with the weak magnetic shear and the weak radial electric field shear are often observed and the pressure gradient at the ITB is not very steep. In such plasmas the electron temperature ITB is steeper for co toroidal rotation cases than that for counter rotation cases. Clarifying the relationship between the rotation direction and heat transport in the ITB region, dominant instabilities are examined by the flux-tube gyrokinetic code GS2 to show that the linear growth rates $$gamma$$ for the co and counter rotation cases are comparable in magnitude, but the counter case shows the more trapped electron mode like frequency. The ratio of the electron heat diffusivity to the ion's is higher for the counter-rotationcase. The difference in the ratio between the two cases agrees with the experiment. Investigating the flow shear effect on $$gamma$$ reveals that its effect is not so large as to change the aforementioned tendency.

口頭

Progress in integrated modeling of JT-60SA plasma operation scenarios with model validation and verification

林 伸彦; Garcia, J.*; 本多 充; 清水 勝宏; 星野 一生; 井手 俊介; Giruzzi, G.*; 坂本 宜照; 鈴木 隆博; 浦野 創

no journal, , 

Development of plasma operation scenarios in JT-60SA has been progressing by using integrated modeling codes. In order to obtain an optimum set of models for the prediction, models are validated by using JT-60U and JET experimental data, and verified by integrated codes such as TOPICS and CRONOS. Predictive simulations are performed to assess the performance of each scenario and to develop optimum scenarios. In the scenario development, various physics aspects are studied by using various types of integrated modeling. The integrated divertor code SONIC showed that Ar seeding can reduce the heat flux on divertor plates below the preferable level (10 MW/m$$^{2}$$) with keeping low separatrix density in the full non-inductive current drive scenario, however, there are some amounts of Ar influx to core region. We integrate TOPICS with a core impurity transport code IMPACT and study the Ar accumulation in the core and its effect on the performance. Other studies with integrated modeling will be also presented.

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JT-60Uにおけるトロイダル回転分布の変化に伴う熱輸送特性のジャイロ運動論コードによる解析

成田 絵美*; 本多 充; 林 伸彦; 浦野 創; 井手 俊介; 福田 武司*

no journal, , 

JT-60Uにおける放物線型内部輸送障壁(ITB)を形成した放電は正磁気シアを有し、径電場シアは弱く、その分布はトロイダル回転によってあまり変化しないが、順方向回転時では電子系ITBの性能が向上することが報告されている。トロイダル回転と電子系ITBの関係を調べるため、ジャイロ運動論コードGS2を用いてITB領域における支配的な不安定性を解析した。その結果、逆方向回転時の方がより捕捉電子モード(TEM)に似た実周波数を持ち、電子の熱輸送が促進されていることが分かった。これは実験と定性的に一致する結果である。

口頭

Validation of heat transport models with ITB plasmas in JT-60U and JET

Garcia, J.*; 林 伸彦

no journal, , 

JT-60UとJETのITBプラズマの実験データを用いて、3つの熱輸送モデル(CDBM, BgB, GLF23)の妥当性を確認する。合わせて、それらの輸送モデルを用いて2つの統合コードTOPICSとCRONOSの結果を比較し、モデルの検証も行う。JT-60Uの3つの放電とJETの1つの放電のデータを用いて、実験の密度分布固定で、実験のイオン・電子温度分布が熱輸送モデルで再現できるか調べた。TOPICSとCRONOSは概ね同じ結果となり、以下の事が分かった。全ての放電に対して常に実験を再現できるモデルはなかった。しかし、CDBMモデルは実験に近いか低い温度になるので、保守的な性能予測に使える。また、現状のCDBMモデルにE$$times$$Bシアの効果を加えると実験を再現できるようになるが、放電毎にモデルパラメータを変える必要があり、そのモデル化が必要である。BgBモデルは、実験に近い場合もあるし、温度が低かったり高かったりする場合がある。これは、BgBモデルには上記と似たE$$times$$Bシア効果が導入されており、そのモデルパラメータの問題をもつためである。GLF23は、温度が常に実験より低くなった。これは、モデル自体が密度分布を固定した計算に適していない可能性が考えられる。

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