The dynamics of low–intermediate–high confinement transitions was studied using a four-step Langmuir probe in the HL-2A edge plasma. Two types (dubbed type-Y and type-J) of limit cycle oscillations (LCOs) with opposite temporal ordering between the radial electric field and turbulence were first observed. In type-Y, the turbulence grows first, followed by the localized electric field. In contrast, the electric field leads turbulence in type-J. In addition, the Reynolds stress gradient is found not enough to drive the LCO flow and the three-wave nonlinear coupling is weak there. The continuously increasing amplitude of magnetic fluctuations and the significant correlation between the magnetic fluctuation and the electron pressure gradient indicate an important role of diamagnetic drifts in the L–H transition. Mode numbers of magnetic fluctuations in the LCO frequency are identified to be m/n = 1/0.
低–高约束转变的动力学过程通过HL-2A边缘等离子体中的四探针进行了研究。首次观测到两种类型的极限环振荡（LCOs），分别称为Y型和J型，它们在径向电场与湍流之间的时间顺序上相反。在Y型中，湍流先增长，随后是局域化电场；而在J型中，电场先于湍流出现。此外，研究发现雷诺应力梯度不足以驱动LCO流，且该区域的三波非线性耦合较弱。磁涨落幅度的持续增加以及磁涨落与电子压力梯度之间的显著相关性表明，抗磁漂移在L–H转变中起着重要作用。LCO频率下磁涨落的模数被确定为m/n = 1/0。