Study of Improved Confinement in Helical Plasmas

改进螺旋等离子体约束的研究

• 批准号: 11680501
• 负责人: ITOH Kimitaka
• 金额: $ 2.37万
• 依托单位: National Institute for Fusion Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11680501/
• 关键词: Helical plasmas; electric field interface; radial electric field; bifurcation; transport barrier; self-organized oscillation

In this research project, a possibility of improved confinement in helical plasmas is investigated, putting an emphasis on the mechanism of "electric field bifurcation and turbulence suppression". In addition, a proposal of experimental test by use of CHS device is examined.In the analysis, we first study the condition that the electric field interface is realized in helical plasmas. The electric field interface, across which the domains with different electric field polarity contact each other, is associated with the strong gradient of radial electric field. This gradient of electric field could reach the level where the microscopic plasma turbulence could be suppressed. This structure has been predicted to exist, and the issue is to investigate whether it is self-sustained in a stationary state and whether such a stationary state is easily accessible or not.These problems were studied in this project, by exploring a theoretical model together with the transport simulation code which includes the presence of interface. Theoretical model of microscopic turbulence is combined with the study of interface, and a threshold condition is derived. The self-sustaining mechanism is verified to work in heliotron/torsatron type configurations, and the accessibility to such a state is analyzed in the space of controlling parameters. A phase diagram was obtained. Based on the theoretical framework, experimental studies were performed. It was shown that the electric field interface is possible to occur in CHS so as to suppress the microscopic plasma turbulence. The internal transport barrier for electron energy was also found in W7-AS and LHD devices, confirming the validity of the theoretical model.Through this project, theory for plasma turbulence, transition and structure formation has been progressed substantially.

在这个研究项目中，研究了改善螺旋等离子体约束的可能性，重点是“电场分岔和湍流抑制”的机制。此外，还探讨了利用CHS装置进行实验测试的方案。在分析中，我们首先研究了螺旋等离子体中电场界面实现的条件。不同电场极性的磁畴通过电场界面相互接触，与径向电场的强梯度相关。这种电场梯度可以达到可以抑制微观等离子体湍流的水平。这种结构已被预测存在，问题是研究它在静止状态下是否能够自我维持，以及这种静止状态是否容易达到。本项目通过共同探索理论模型来研究这些问题具有包含接口存在的传输模拟代码。将微观湍流理论模型与界面研究相结合，推导了阈值条件。验证了自维持机制可以在日光管/扭转管型配置中工作，并在控制参数空间中分析达到这种状态的可达性。获得相图。基于理论框架，进行了实验研究。结果表明，CHS中可能出现电场界面，从而抑制微观等离子体湍流。在W7-AS和LHD器件中还发现了电子能量的内部传输势垒，证实了理论模型的有效性。通过该项目，等离子体湍流、跃迁和结构形成的理论得到了实质性进展。

项目成果

A. Yoshizawa, S.-I. Itoh and K. Itoh: "Plasma and Fluid Turbulence - Theory and Modelling"Institute of Physics Publishing (Bristol,UK, 2002). 459 (2002)

A.吉泽，S.-I。

N Kasuya, K Itoh, Y Takase: "Multiple bifurcation of the radial electric field structure induced by electrodes in tokamaks"Plasma Phys.Control. Fusion. Vol.44No.5A. A287-A292 (2002)

N Kasuya、K Itoh、Y Takase：“托卡马克中电极引起的径向电场结构的多重分叉”Plasma Phys.Control。

S Toda, K Ito: "Theoretical study of the structure of the electric field in helical toroidal plasmas by the use of an anomalous transport model"Plasma Phys.Contr.Fusion. Vol.44,No.3. 325-334 (2002)

S Toda、K Ito：“利用反常传输模型对螺旋环形等离子体中电场结构的理论研究”Plasma Phys.Contr.Fusion。

Kimitaka Itoh, Sanae-I Itoh: "Transient response of transport at transport barrier formation"Plasma Phys.Control. Fusion. Vol.44No.5A. A367-A372 (2002)

Kimitaka Itoh，Sanae-I Itoh：“传输屏障形成时的传输瞬态响应”Plasma Phys.Control。

A.Fujisawa,…,K.ITOH, et al.: "Experimental Study of the bifurcation nature of the electrostatic potential of a toroidal helical plasma"Phys.Plasmas. 7.10. 4152-4183 (2000)

A.Fujisawa,…,K.ITOH 等人：“环形螺旋等离子体静电势分叉性质的实验研究”Phys.Plasmas 7.10 (2000)。