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

在场反转位形的平移实验中，为了控制反射的反弹系数，使等离子体在短时间内复位而不反弹，采用被动和主动两种方法控制平移速度和等离子体位置。由于平移等离子体而被排除的磁场在金属衬垫上感生脉冲感应电流。脉冲磁场施加在FRC等离子体上。诱导力取决于金属调谐器的电阻、等离子体半径与衬管半径的比率。用趋肤时间为0.005ms的金属衬管沉降3 mg、平移速度为10 km/s的氘等离子体，在主动法中，在平移区安装脉冲磁场线圈。脉冲电流从电源供给到脉冲线圈，使等离子体运动同步。通过控制电流值和电流 ...更多信息 形式，等离子体被反射并沉降下来。脉冲电流为40 kA，上升时间为0.01ms时，速度为40 km/s的FRC等离子体被反射，并根据波形的不同而稳定下来。这些实验结果与基于系统能量守恒的刚体计算机模拟结果一致，并从约束场的场梯度角度重新考虑了n=1模运动的控制。负场梯度抑制运动。研究表明，具有高分界线延伸率的等离子体有利于降低等离子体的振幅。n=1模式运动，因为等离子体周围的约束场的小的负梯度。为了产生高度伸长的等离子体，将辅助导体安装到设备中。观测到的n=1模运动的振幅被控制在没有辅助导体时的一半左右，这从磁结构上得到了很好的解释。研制了60通道可见光诊断系统和多单圈排除式测量系统。通过磁测量和光学测量相结合的方法，阐明了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模运动的非对称压力分布。场反转组态（FRC）等离子体的分界线形状和内部结构的确定通过比较测量的磁通量与梯度-沙夫拉诺夫方程。分析还表明边缘层等离子体的宽度为w^*r_i（w是离子回旋半径r_i的数目），分界线处的β值（B_s），以及在磁场零点附近形成磁岛。为了通过磁方法确认这些发现，测量FRC的辐射功率密度。发现w和B_s值与辐射测量值符合得很好。然而，磁岛的位置与辐射强度等值线图中出现的位置并不一致。辐射的非对称轮廓也讨论了相对于压力常数表面的非同心性。当FRC中心移动0.1-0.2r_s（r_s为分界线半径）而分界线表面不移动时，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