Helical Configuration with Low Ripple and High beta Stability

为了就合作进行一般性讨论，motojima教授和r. pavlichenko先生（高级研究生大学的研究生）于6月访问了基辅和哈尔科夫。pavlichenko先生带来了很多关于Uragan-2M （U-2M）的设计研究资料。U-2M具有低螺旋纹波的特点，环形场纹波与螺旋纹波的结合使得有效纹波较小。虽然它的实验结果将给我们关于螺旋纹波对等离子体约束的影响提供一个重要的指导，但由于乌克兰的经济条件不好，它的操作还没有开始。fedyanin博士提出了他的抗磁回路的新想法，这给我们在测量等离子体储存能量时提供了一个高的时间分辨率。他展示了L-2M仿星器的实验结果。电子回旋共振加热（ECH）中被加速的高能电子的迅速损失是决定功率沉积的重要因素。通常情况下，通过关闭加热电源后的电子温度变化（用ECE测量）来估计功率沉积。然而，这种ECE方法的精度与时间分辨率成反比。具有高时间分辨率的抗磁回线将成为等离子体输运分析的有力工具。pavlichenko教授与CHS小组进行了讨论，推动远程参与CHS和LHD实验，这将是世界范围内核聚变社会的重要课题。marushchenko博士讨论了CHS中ECH等离子体的电子速度分布。这种分布对螺旋纹波很敏感，螺旋纹波会导致垂直加速电子的损失。他正在和CHS的实验人员一起开发福克-普朗克计算机代码。普斯托维托夫博士是螺旋等离子体MHD理论的杰出专家。自从他第一次访问日本（1992年）以来，他对日本的这一理论做出了许多贡献。今年，他发现了磁坐标（滨田坐标和布泽尔坐标）之间简单而清晰的关系。很容易理解，托卡马克通常使用的坐标与布泽尔坐标相似。磁坐标是优化螺旋磁构型的关键。在此基础上，我们设计了一种准环形对称仿星器，这是一种基本上没有螺旋纹波的优化构型。少

For general discussions on the collaboration Prof.Motojima and Mr.R.Pavlichenko (graduate student of The Graduate University for Advanced Studies) visited Kiev and Kharkov in June. Mr.Pavlichenko brought a lot of materials on the design study of Uragan-2M torsatron (U-2M). U-2M is characterized with its low helical ripple, and combination of toroidal field ripple and helical ripple makes the effective ripple small. Although its experimental results will give us an important guide-line on the effect of helical ripple on the plasma confinemnt, its operation has not started yet because of bad economical conditions in Ukraine.Dr.Fedyanin presented his new idea of a diamagnetic loop, which gives us a high temporal resolution in measuring the plasma stored energy. He showed experimental results from L-2M stellarator. The prompt loss of energetic electrons which are accelerated in the electron cyclotron resonance heating (ECH) plays an important role in determining the power deposition. Usual … More ly the power deposition is estimated by the electron temperature change (with ECE measurement) after the turn-off of the heating power. However the accuracy of this ECE method is inversely proportional to the temporal resolution. The diamagnetic loop with high temporal resolution will be a powerful tool for the transport analysis of ECH plasma. Prof.O.Pavlichenko discussed with CHS group to promote a remote participation in CHS and LHD experiments, which will be an important subject in a worldwide fusion society. Dr.Marushchenko discussed the velocity distribution of electrons of a ECH plasma in CHS.The distribution is sensitive to the helical ripple which induces the loss of perpendicularly accelerated electrons. He is developing the Fokker-Planck computer code for this estimate with CHS experimentalists. Dr.Pustovitov is a great specialist in the MHD theory of helical plasma. He has made a lot of contributions to the theory in Japan since his first visit (1992). This year he found a simple and clear relation between magnetic coordinates (Hamada-and Boozer-coordinates). It is easily understood that coordinate usually used in tokamak is similar to the Boozer coordinate. The magnetic coordinates are essential to the optimization of helical nagnetic configuration. Based on these discussions we are designing a quasi-toroidally symmetric stellarator, which is the optimized configuration with essentially no helical ripple. Less