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

为了控制反射的回弹系数，使等离子体在短时间内无弹跳地复位，采用了被动和主动两种方法来控制场反构型平移实验中的平移速度和等离子体位置。由平移等离子体产生的排除磁场在金属衬里上感应脉冲感应电流。脉冲磁场作用于FRC等离子体。感应力取决于金属调谐器的阻力，等离子体半径与直线半径的比值。3mg的氘等离子体，平移速度为10km/s，通过0.005ms皮肤时间的金属衬里沉淀。在主动方法中，脉冲磁场线圈，安装在平移区域。脉冲电流由电源供给脉冲线圈，同步等离子体运动。通过控制电流值和电流形式，实现等离子体的反射和沉降。通过40kA的脉冲电流和0.01ms的上升时间，40km/s的FRC等离子体根据波形被反射并沉降。这些实验结果与基于刚体系统能量守恒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了n=1模态运动的控制。负的场梯度抑制了运动。研究表明，具有高分离延伸率的等离子体较好地降低了等离子体的振幅。n=1模式运动是由于等离子体周围的约束场有一个小的负梯度。为了产生高度拉长的等离子体，在装置中安装辅助导体。观察到的n=1模运动的振幅被控制在没有任何辅助导体时的一半左右，这从磁性结构上可以很好地解释。一些内部结构的等离子诊断方法得到了改进。研制了60路可见光诊断系统和多路一匝排除测量系统。通过磁测量与光学测量相结合，阐明了开放场线区域的磁场和等离子体结构，如等离子体β值和边缘层深度以及n=1模态运动时的不对称压力分布。通过将测量的磁通量与Grad-Shafranov方程进行比较，确定了场反转组态（FRC）等离子体的分离矩阵形状和内部结构。该分析还提出了等离子体边缘层的宽度w^*r_i (w为离子的陀螺半径数r_i)，分离矩阵处的β值（b_s），以及磁场零附近磁岛的形成。为了用磁法证实这些发现，测量了FRC的辐射功率密度。结果表明，w和b_s值与辐射测量值吻合较好。然而，磁岛的位置与在辐射强度等高线图上出现的位置并不一致。对于压力常数表面的非同心性，还讨论了辐射的不对称分布。当FRC中心移动0.1-0.2r_s （r_s为分离矩阵半径），而分离矩阵表面没有发生任何移动时，可以解释所测量的轮廓。少

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