Particles Confinement Properties in Low Aspect Ratio L=1 Helical Systems.

本文研究了L=1螺旋轴系统采用有效环曲率项控制方法来改善粒子约束性能。有效环曲率项定义为通常环曲率项与螺旋场项的最近卫星谐波之和。如果我们考虑一个紧凑的系统，小周期数N和低纵横比系统是可取的。通常情况下，由于环形效应的存在，粒子输运特性会变差。我们已经研究了在我们的论文中描述的相同的方法，我们已经通过控制有效曲率项改善粒子输运。结果表明，在低长径比情况下，粒子约束得到了改善，并讨论了磁场的最佳结构。小N系统的输运性质将比大N系统的输运性质更差。但是，磁力井控制相对容易，装置变得紧凑。因此，我们研究了这四种装置的无碰撞测试粒子约束和速度空间损失区。最大测试粒子能量设置为10 KeV。我们可以看到，粒子约束变得更糟，在低N（低线圈纵横比）的情况下，如预期的。但在低N情况下，特别是N=5时，粒子约束受到间距调制参数α ^* 的影响，表明α ^* =-0.2时的输运改善了约束特性。这些结果与新古典理论是一致的。另一方面，高纵横比的情况下，表明在我们的粒子追踪计算的改善效率不是那么大。

The L=1 helical axis systems applying the control methods of effective toroidal curvature term defined as the sum of usual toroidal curvature term and one of the nearest satellite harmonics of helical field term, have been studied to improve particles confinement properties. If we consider a compact system, a small period number N and low aspect ratio system is desirable. In generally, particles transport properties of compact system become worse due to usual toroidal effect. We have been studied by the same methods described in our paper, and we have improved particles transport by controlling the effective curvature term. It has been found that improving of particle confinement has observed, and the optimal structure of magnetic field in case of low aspect ratio case has been discussed. The transport properties of small N systems will be worse than that in the larger N systems. But, the magnetic well control is comparatively easy and device becomes compact. So, we have investigated the collisionless test particles confinement and velocity space loss region for the four type devices. The maximum test particles energy is set at 10KeV. We can see that the particle confinement becomes worse in low N ( low coil aspect ratio) case as expected. But, the low N case, especially N=5 case, the particle confinement is influenced by the pitch modulation parameter a^* and shows that the transport of a^* =-0.2 case is improved confinement properties. These results are consistent with the neo-classical theory. On the other hand, the high aspect ratio cases show that the efficiency of improvement is not so large in our particle tracing calculation.