Intermittent events dominated by meso-scale physics and control of a macro system in steady state spherical tokamak

与“Intermittent events dominated by meso-scale physics and control of a macro system in ste\state spherical tokamak”。主要来说，开放式磁场配置的结构和控制性是从封闭的磁场表面到封闭的一个、两个封闭的磁场表面，以及开放式磁场区域之外的一个兴趣区域。在研究期间，目前在东京使用非诱导性方法启动，2）通过SOL区域传播，从封闭的流体表面扩展到开放的区域。这些现象可以被识别为对抗Tokamak等离子体稳定状态操作的中断或非正常事件。本研究的目标是揭示微观扰动下宏观结构的特征学的中尺度物理学。对中间范围和宏观范围系统之间的耦合协同效应的评估将被调查。 ... More 一个阶段放松时间的评估。最后，我们想建立一种稳定的控制方法来控制Tokamak操作。在H21-23期间，射频驱动的非诱导性等离子体生产和维持已在任务和CPD中完成，后续工作已完成。（1）在100千瓦时使用8.2千兆赫的ECWs，非诱导性当前启动和当前稳定已成功地演示为35千兆瓦，这是世界记录。High poloidal equilibrium at ··p = 1. 5 and ·<1（triangles） has been obtained。300秒的最大持续时间也可用于ST配置。在从开放表面到封闭表面的形成阶段期间，一些诊断工具已经被应用，然后后续的物理图片可能会被绘制出来。腔室的相位比很小，足以使等离子体内部存在多种谐波，而且它已经发现了MOMFC（镜像比依赖于Bzcurvature），并且Bz/Bt的放大率对当前快速上升的影响，因为初始出生的10 keV能量元件可以在开放磁场中很好地保密。高p~ 1等离子体场景在高MOMFC被演示为高MOMFC=2和Bz/Btof 10%。Ipof 16 kA，目前的高斜率为0.3 - 0.5 MA/s，达到了非诱导性。一个自然的机载极化场似乎没有表现为MOMFCincreased，这种均衡素可以维持~ 10秒。根据通量测量，它已经被观察到，当一个封闭的表面成形时，在磁性表面上的长相关长度也得到了测量。这是一个由拓扑变化期间的中观尺度所支配的现象。（2）本研究统计方法的SOL涡轮、等离子体传输、blob传播的第二方面寻址。这是针对由荧光的pdf的两个维度结构、pdf的两个维度结构和统计方面、blob传播和加速，以及SOL中的流动模式及其对涡轮传输的影响。这些观测是通过使用横向观察快速摄像机成像和本地探测器测量而拍摄的。磁性场音高中的连通性传输的统计方面及其对变化的尊重是可见的。在Bzat a恒定Bt中发现的流动性和相关的细胞生成和传播的渐进性增强。Amplitude and waiting time of the blob attains a maximum for highest Bz/Bt（= 7.8%）。2D statistical analysis of the images enables us to identify blobformation location precisely at the step density gradient region。加速的放射性传播被观察到为大规模的细胞。“镜子对湍流的影响已经被研究为极性磁场曲线中的变化。”闪光特性对磁性薄片有明显的不同。该区域由pdf的演变的Gaussian到gamma可以被认为是一个典型的尺度，其中包括中观现象主导地位。一种新的诊断和分析方法已经开发出来，以评估利用流体流动的等离子体。Less（低）

This research is aiming at the subject associated with "Intermittent events dominated by meso-scale physics and control of a macro system in steady state spherical tokamak". Mainly, structure formation and its controllability under a process from an open magnetic field configuration to the closed one, contact to two closed magnetic surfaces, and open field region outside the closed one are of interest.During the research period, 1) current start-up in tokamak using non-inductive method and 2) blob propagation crossing the SOL region, which extends from the closed flux surfaces to the open ones. These phenomena can be recognized as intermitted or off-normal events against the steady state operation of the tokamak plasma. This research aims at pointing out the characteristics of the meso-scale physics for the macroscopic structure formation under the microscopic turbulence. The evaluation for the coupling coefficient between the meso-scopic and macroscopic systems will be investigated by … More evaluation of a phase relaxation time. Finally we would like to establish control methods for steady state tokamak operation. During H21-23 experiments for rf driven non-inductive plasma production and sustainment have been performed in QUEST and CPD. The followings have been achieved.(1) Using 8.2 GHz ECWs at ~ 100 kW, non-inductive current start-up and current sustainment has been successfully demonstrated at 35 kA, which is the world record. High poloidal equilibrium at ・・p =1.5 and ・<1(triangles) has been obtained. The maximum duration of 300 sec is also performed for ST configuration. During the formation phase from the open to closed surfaces, several diagnostic tools have been applied and then the following physical picture could be drawn. The chamber aspect ratio is small enough for several harmonics to exist inside the plasma, and it has been found that the MOMFC(mirror ratio depending on the Bzcurvature) and the amplitude of Bz/Bt contribute to the fast ramp-up of the current, because ofthe initially born energetic electrons of 10 keV could be well confined in the open magnetic fields. The high ・・p~ 1 plasma scenario has been demonstrated at high MOMFC=2 and Bz/Btof 10 %. Ipof 16 kA at the high current ramp-up rate of 0.3 - 0.5 MA/s was achieved non-inductively. A natural inboard poloidal field null appeared as MOMFCincreased and this equilibrium could be sustained for ~ 10 seconds. Based on the fluctuation measurements it has been observed that the long correlation length along the magnetic surfaces has been measured when a closed surface is formed. Thisindicates that the phenomenon dominated by a mesoscopic scale occurred during the topological change.(2)The second aspect addressed in this research isthe statistical approach of the SOL turbulence, plasma transport, blob propagation.This is aimed at identification ofthe generation region of the blob by charactering the pdf of the fluctuations, two dimensional structure of pdf and statistical aspect, blob propagation and acceleration, and flow pattern in the SOL and its impact on the turbulent transport. These observations have been carried out by using the wide viewing fast camera imaging and local probe measurements. Statistical aspects of the convective transport with respect to the variation in magnetic field pitch are dwelled upon. Progressive enhancement of fluctuations and consequent blob generation and propagation are observed with the increase in Bzat a constant Bt. Amplitude and waiting time of the blobs attains a maximum for highest Bz/Bt(=7.8%). 2D statistical analysis of the images enables us to identify blobformation location precisely at the steep density gradient region. Accelerated radial propagation was observed for large sized blobs. The effect of mirror ratio on turbulence is studied with the change in poloidal field curvature. Fluctuation characteristics are quite different for magnetic shears. The region characterized by the deviation of pdf from the Gaussian to gamma can be considered as a typical scale, with which the mesoscopic phenomenon dominates. A new diagnostic and analytical method have been developed to evaluate the plasma flow using the fluctuations. Less