Abstract
The dynamic features of the low-intermediate–high-(L-I-H) confinement transitions on HL-2A tokamak are presented. Here we report the discovery of two types of limit cycles (dubbed type- and type-), which show opposite temporal ordering between the radial electric field and turbulence intensity. In type-, which appears first after an L-I transition, the turbulence grows first, followed by the localized electric field. In contrast, the electric field leads type-. The turbulence-induced zonal flow and pressure-gradient-induced drift play essential roles in the two types of limit cycles, respectively. The condition of transition between types- and - is studied in terms of the normalized radial electric field. An I-H transition is demonstrated to occur only from type-.
- Received 11 March 2013
DOI:https://doi.org/10.1103/PhysRevLett.110.265002
© 2013 American Physical Society