The drift kinetic equation is solved for low density TJ-II plasmas employing slowly varying, time-dependent profiles. This allows to simulate density ramp-up experiments and to describe from first principles the formation and physics of the radial electric field shear, which is associated to the transition from electron to ion root. We show that the range of frequencies of plasma potential fluctuations in which zonal flows are experimentally observed is neoclassically undamped in a neighborhood of the transition. This makes the electron root regime of stellarators, close to the transition to ion root, a propitious regime for the study of zonal-flow evolution. We present simulations of collisionless relaxation of zonal flows, in the sense of the Rosenbluth and Hinton test, that show an oscillatory behaviour in qualitative agreement with the experiment close to the transition.

翻译：TJ-II等离子体的低密度 TJ-II 等离子体的漂移方程式使用缓慢变化的、有时间依赖的剖面图谱,可以模拟密度斜坡实验,并从头等原则描述辐射电场剪切的形成和物理,这与从电子根向离子根的过渡有关。我们显示,实验观测到区域流动的等离子体潜在波动频率范围是新古典的,没有在转型的附近区域进行。这使得恒星电子根系接近离子根的过渡,是研究区域流演变的有利机制。我们模拟了罗森布卢特和欣顿试验意义上的无碰撞的分区流放松,这显示了与接近转型的实验在质量上一致的振动行为。