Development to new stage of helical plasma confinement

1)CHS-qa是一种后CHS器件，在物理和工程设计方面取得了一定的进展。稳定性β达到4%，高能离子轨道约束良好。高性能导致等离子体横截面的高伸长率。2)利用新经典理论中的有效螺旋涟漪，估算了CHS等离子体高离子温度模式的离子热扩散系数。估算值与实验值接近。本文计算了由磁轴强烈内移而实现的准均质构型的离子扩散系数，其中螺旋涟漪底部具有相同的磁场强度。准全元素组态的预期离子温度为1.5keV，这比迄今为止在高Ti模式下获得的1 keV的值高得多。3)CHS中的电势分叉导致了电子约束的改善，这导致了高电子温度模式，其中实现了2keV的高中心电子温度。在T-10托卡马克中也观察到了同样的内输运势垒现象。输运势垒形成的位置，径向电场剪切是强的两个等离子体（CHS和T-10）。4)定性地解释了平衡β值随等离子体截面伸长的增加而增加的事实。伸长率在获得高性能等离子体中应起作用。结果表明，磁测量不能唯一地确定环形等离子体的电流和压力分布。

1) Progress has been made on physics and engineering design of CHS-qa, which is supposed to be a post-CHS device. Stability β up to 4% and good orbit confinement of high energy ions have been achieved. High performance results in high elongation of plasma cross-section. 2) Ion thermal diffusivity of high ion temperature mode of CHS plasma has been estimated by using the effective helical ripple of the neoclassical theory. The estimated values are close to the experimental one. The ion diffusivity for quasi-omnigenous configuration realized by a strong inward shift of the magnetic axis, where the bottom of helical ripple has the same magnetic field strength, has been estimated. The expected ion temperature for the quasi-omnigenous configuration is 1.5keV, which is much higher than the value obtained so far in high Ti mode of 1keV. 3) Confinement improvement of electron results from the potential bifurcation in CHS, which leads to the high electron temperature mode where high central electron temperature of 2keV is realized. The same phenomenon of the internal transport barrier has been observed in T-10 tokamak. The transport barrier is formed at the position where the radial electric field shear is strong for both plasmas (CHS and T-10). 4) Qualitative explanation has been made on the fact that the equilibrium βvalue increases as the elongation of plasma cross-section increases. The elongation should play a role in getting a high performance plasma. It is shown that magnetic measurements can not determine uniquely the current and pressure profiles of toroidal plasmas.