DENSITY CONTROL OF A FIELD-REVERSED CONFIGURATION

在本实验中，场反转组态（FRC）等离子体的电子密度必须降低约一个数量级，以使FRC反应器中的中性束有效加热。FRC中的工作密度由与电极间气体击穿有关的帕邢定律控制。因此，在低于气体击穿最小值的压强下很难产生等离子体，本文提出了一种新的方法来产生低于最小值的FRC。这是由于线圈端部的损失使产生的初始等离子体在最小值以上减少。利用该方法产生的低密度等离子体形成FRC，实验中FRC的密度极限由2 × 10 ~（-1）m <21>~ 2<-3>提高到9 × 10 ~<20><-3>（-1）m ~ 2。如果将这种方法应用于迄今为止运行的大型机器。可以以4 × 10 - 4 m2的密度制备中性束加热的靶等离子体<20><-3>。等离子体温度从400 eV上升到 ...更多信息 900 eV左右。温度和密度之间的这种强相关性很容易用FRC等离子体的β-1条件来解释。随着我们的机器处理的等离子体参数范围变宽，FRC反应器需要研究的其他问题也被研究。这些是具有高极向通量的FRC的形成、FRC的平移和合并。在放电管和磁流变箍缩线圈之间安装了一个新的磁流变箍缩线圈，称为控制线圈。通过将控制线圈的磁压力施加到FRC的两端，FRC变胖，并且在没有控制线圈的情况下具有两倍的极向通量。在平移实验中，FRC可以在与形成区相同的场强下以50 km/s的速度移动。两个FRC通过控制线圈加速碰撞并合并成一个FRC，合并过程在10- 15 μ s内快速完成，其时间优于堆内换料。这些实验将在准静态场中再次进行，而现在的机器就是在准静态场中制造的。少

The electron density of a field-reversed configuration(FRC) plasma must be reduced about one order of the magnitude on the present experiment to make effective a neutral beam heating in an FRC reactor. Operating density in an FRC is controlled bya Paschen's law concerning to gas breakdown letween elecrodes. So it is difficult to produce the plasma at the pressure lower than the minimum of the gas breakdown.We propose a new method to generate an FRC with the density below the minimum. It is that the initial plasma which is produced above the minimum is decreased by a loss from the coil ends. The low density plasma produced by this method is used to form the FRC.The density limit of the FRC is changed from 2X10^<21>m^<-3> to 9x10^<20>m^<-3> in our experiment. If this method is applied to a large machine which was operated till now. it is possible that the target plasma to a neutral beam heating can be prepared at a density of 4x10^<20>m^<-3>. The plasma temperature goes up from 400eV to … More 900eV by ablove density change. This strong corellation between the temperature and the density is easily explained by a beta-1 condition on the FRC plasma.As the plasma parameter range treated in our machine becomes broad, other subjects to be needed in a FRC reactor are studied. These are a formation of an FRC with a high poloidal flux, a translation and a merging of FRCs. A new rheta-coil, named a control coil, is installed between the discharge tube and the rheta-pinch-coil for these experiments. The FRC becomes fat by application of a magnetic pressure of the control coil to the both ends of the FRC and has a twice of the poloidal flux without the control coil. On the translation experiment it becomes possible that an FRC can be moved at speed of 50km/s inthe same field strength as the formation region. Two FRCs are accerelated to collide each other by the control coil and are merged into one FRC.The merging process is quickly completed for 10-15mu s, of which time is preferable to a refuering in a reactor. These experiments will be tried again in quasistatic field, of which machine is constructed now. Less