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Control of the Translation Velocity and Position on a Field Reversed Configuration

场反向配置上平移速度和位置的控制

基本信息

批准号：
14580528
负责人：
TAKAHASHI Tsutomu
金额：
$ 2.3万
依托单位：
Ninon University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14580528/
关键词：
Field Reversed Configuration Control of Translation Velocity and Position Passive control by metal liner Active control by pulsed magnetic field n=1 mode Global Motion Field Gradient of Confinement Field Conducting ring Internal Structure es

项目摘要

The translation velocity and the plasma position in translation experiments of a field reversed configuration are controlled by passive and active methods in order to control a rebound co-efficient of the reflection and to reset the plasma in short period without bouncingIn the passive method, a resistive metal liner is installed in the region. A pulsed inductive current is induced on the metal liner by the excluded magnetic field due to the translation plasma. The pulsed magnetic field is applied on the FRC plasma. The induced force is dependent on the resistance of the metal Tuner, ratio of the plasma radius to the liner radius. Deuterium plasma of 3mg with the translation velocity of 10km/s is settled down by a metal liner of 0.005ms skin time.In active method, the pulsed magnetic field coil, installed in the translation region. The pulsed current is supplied to the pulse coil from the power supply, synchronizing the plasma motion. By the control of the current value and the current … More form, the plasma is reflected and settled down. By the pulsed current of 40kA and the rising time of 0.01ms, the FRC plasma with 40km/s is reflected and settled down in dependent of the wave form. These experimental results agree with that of a simple computer simulation, which is based on energy conservation of system and with a rigid body.The control of n=1 mode motion is reconsidered from the point view of the field gradient of the confinement field. A negative field gradient suppresses the motion. The investigation suggests that the plasma having high separatrix elongation is preferable for reducing the amplitude of. the n=1 mode motion because of a small negative gradient of the confinement field around the plasma. In order to produce highly elongated plasmas, auxiliary conductors are installed into a device. The observed amplitudes of the n=1 mode motion are controlled to about a half level of those without any auxiliary conductors, which is explained well from the magnetic structure.Several plasma diagnostic for the internal structure have been improved. 60 channel visible optical diagnostic system and multi one turn excluded measurement system are developed. By the combining of the magnetic measurement and the optical measurement, magnetic field and plasma structure with the open field line region, for example, plasma beta value and the depth of edge layer and the asymmetrical pressure profile with the n=1 mode motion are clarified. Separatrix shapes and internal structures of field-reversed configuration (FRC) plasmas are determined by comparing the measured magnetic fluxes with the Grad-Shafranov equation. This analysis also suggests a width of an edge-layer plasma w^*r_i (w is the number of ion gyro-radius r_i), a beta value at the separatrix (b_s), and the formation of magnetic islands near the field null. In order to confirm these findings by the magnetic method, a radiation power density of the FRC is measured. It is found that the w and b_s, values agree well with those obtained by the radiation measurement. However, the positions of the magnetic islands do not coincide with those appearing in an intensity contour map of the radiation. Asymmetrical profiles of the radiation are also discussed with respect to the nonconcentricity of the pressure constant surface. The measured profiles can be explained when the center of the FRC is shifted by 0.1-0.2r_s (r_s is a separatrix radius) without any shift of the separatrix surface. Less

场反转结构平移实验中的平移速度和等离子体位置通过被动和主动方法控制，以控制反射的反弹系数并在短时间内重置等离子体而不弹跳。被动方法是在该区域安装电阻金属衬里。由于平移等离子体而排除的磁场在金属衬里上感应出脉冲感应电流。脉冲磁场施加在 FRC 等离子体上。感应力取决于金属调谐器的电阻、等离子体半径与衬里半径的比率。平移速度为10km/s的3mg氘等离子体通过0.005ms集肤时间的金属衬里沉降。在主动方法中，脉冲磁场线圈安装在平移区域。脉冲电流从电源供给脉冲线圈，使等离子体运动同步。通过电流值和电流形式的控制，使等离子体反射并沉降。通过40kA的脉冲电流和0.01ms的上升时间，40km/s的FRC等离子体被反射并根据波形稳定下来。这些实验结果与基于系统能量守恒和刚体的简单计算机模拟结果一致。从约束场场梯度的角度重新考虑n=1模态运动的控制。负场梯度会抑制运动。研究表明，具有高分界面伸长率的等离子体有利于降低振幅。由于等离子体周围约束场的负梯度很小，导致 n=1 模式运动。为了产生高度拉长的等离子体，将辅助导体安装到设备中。观察到的n=1模式运动的振幅被控制在没有任何辅助导体的振幅的一半左右，这从磁结构中得到了很好的解释。内部结构的几个等离子体诊断得到了改进。开发了60通道可见光诊断系统和多圈排除测量系统。通过磁测量和光学测量的结合，阐明了开场线区域的磁场和等离子体结构，例如，等离子体β值和边缘层深度以及n=1模式运动的不对称压力分布。通过将测量的磁通量与 Grad-Shafranov 方程进行比较，可以确定场反转配置 (FRC) 等离子体的分界形状和内部结构。该分析还表明边缘层等离子体的宽度 w^*r_i（w 是离子陀螺半径 r_i 的数量）、分界线处的 beta 值 (b_s) 以及零场附近磁岛的形成。为了通过磁法确认这些发现，测量FRC的辐射功率密度。发现w和b_s值与辐射测量得到的值非常吻合。然而，磁岛的位置与辐射强度等值线图中出现的位置不一致。还讨论了关于压力恒定表面的非同心性的辐射的不对称分布。当 FRC 中心移动 0.1-0.2r_s（r_s 是分界线半径）且分界面没有任何移动时，可以解释测量的轮廓。较少的