Design of a helical system with the reduced toroidal viscosity

降低环形粘度的螺旋系统的设计

• 批准号: 11680502
• 负责人: OKAMURA Shoichi
• 金额: $ 1.66万
• 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 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11680502/
• 关键词: toroidal viscosity; quasi-axisymmetry; MHD stability; optimization; plasma rotation; Boozer coordinate; torsatron; CHS-qa

The most important characteristics of the magnetic field configuration which has been studied in this research project is the quasi-axisymmetry (QA symmetry). This symmetry gives the magnetic field structure which does not depend on the toroidal coordinate when expressed in the Boozer coordinates. This characteristics is called as a two dimensional field structure. However the geometric structure is still three dimensional which is necessary to create the rotational transform without a toroidal plasma current. This point is important difference between tokamaks and QA stellarators. One of solutions we found for QA configurations is called 2b32 which has toroidal periods N=2 and the average aspect ratio 3.2. This aspect ratio is relatively very low among all family of helical systems and is considered to be advantageous for the design of compact helical reactors in the future. 2b32 configuration has a flat profile of rotational transform (iota=0.4) and gives good MHD stability for the a … More verage beta 4% against various ideal MHD modes (Mercier and global ballooning modes). It has a magnetic well for all positions of radius and all range of beta which is very different from the conventional helical systems. The neoclassical transport coefficients are reduced by about two orders of magnitudes in the low collisionality from the conventional helical systems. Besides these advantageous features in the classical evaluations of confinement properties, this new configuration has possibilities of giving improved confinement modes against anomalous transport phenomena. An important modeling of the improved confinement in toroidal systems is the reduction of the turbulence due to a sheared flow caused by the sharp gradient of the radial electric field. In order to create such a condition, low viscosity for the plasma rotating motion is necessary. Our new configuration has a two orders smaller neoclassical viscosities compared with conventional helical systems. The engineering design was also made for 2b32 configuration which has 20 modular coils with 1.5 m major radius for 1.5 Tesla magnetic field. Less

该研究项目中研究的磁场构型的最重要特征是准轴对称（QA对称性）。这种对称性给出的磁场结构在Boozer坐标中表达时不取决于环形坐标。该特征称为二维场结构。但是，几何结构仍然是三维，这对于在没有环形等离子体电流的情况下创建旋转变换是必要的。这一点是Tokamaks和Qa Stellarators之间的重要区别。我们发现用于质量检查配置的解决方案之一称为2B32，它具有环形周期n = 2和平均纵横比3.2。在所有螺旋系统家族中，这种纵横比相对较低，并且被认为对未来紧凑型螺旋反应堆的设计是有利的。 2B32配置具有旋转变换的平坦曲线（IOTA = 0.4），并为A…具有良好的MHD稳定性，以相对于各种理想的MHD模式（Mercier和Global Ballooning Modes）。它具有半径和所有beta范围的所有位置的磁孔，与常规螺旋系统截然不同。在传统的螺旋系统的低碰撞率中，新古典转运系数减少了约两个尺寸。除了在限制特性的经典评估中这些有利的特征外，这种新的配置还可以提供改进针对异常运输现象的约束模式。环形系统中改进的限制的重要建模是，由于径向电场的尖锐梯度引起的剪切流，湍流的降低。为了创建这种条件，需要低粘度对等离子体旋转运动。与传统的螺旋系统相比，我们的新配置具有两个较小的新古典粘度。还针对2B32配置进行了工程设计，该配置具有20个模块化线圈，其1.5 m大半径为1.5特斯拉磁场。较少的

项目成果

S.Okamura,S.Matsuoka et.al.: "Physics and Engineering Design of a Low-Aspect-Ratio Quasi-Axisymmetric Stellarator CHS-qa"Nuclear Fusion. (In print). (2001)

S.Okamura、S.Matsuoka 等人：“低纵横比准轴对称仿星器 CHS-qa 的物理和工程设计”核聚变。

S.Okamura,S.Matsuoka et.al.: "Confinement physics study in a small low-aspect-ratio helical device CHS"Nuclear Fusion. Vol.39. 1337-1350 (1999)

S.Okamura、S.Matsuoka 等人：“小型低展弦比螺旋装置 CHS 中的约束物理研究”核聚变。

S.Okamura,S.Murakami et.al.: "Low-aspect-ratio quasi-axisymmetric stellarator CHS-qa"Journal of Plamsa and Fusion Research.SERIES. Vol.3. 73-76 (2000)

S.Okamura、S.Murakami 等人：“低纵横比准轴对称仿星器 CHS-qa”Plamsa 与聚变研究杂志.系列。

S.Okamura,S.Murakami et.al.: "Low-aspect-ratio quasi-axisymmetric stellarator CHS-qa"Journal of Plamsa and Fusion Research, SERIES. Vol.3. 73-76 (2000)

S.Okamura、S.Murakami 等人：“低纵横比准轴对称仿星器 CHS-qa”Plamsa 与聚变研究杂志，系列。