In the 2018 EAST experimental campaign, a very high central electron heating, fully-non-inductive discharge with the core electron temperature over 9 keV has been achieved. Such high central electron heating was realized by injecting radio frequency waves, including 1.8MW lower hybrid wave (LHW) and 0.8MW electron–cyclotron waves (ECW). Experimental diagnosis indicates two different time scales characterizing the electron heating process, a rapid and a slow rise of the central electron temperature after the injection of ECW. In this work, integrated modeling is performed to investigate the physical mechanisms of such high electron heating. Five characteristic phases during the increase of the electron temperature are chosen for modeling. In phase 1, the electron heating is by LHW alone. The modeling confirms that the LHW can only sustain the core electron temperature T _e ≈ 5.5 keV, which is consistent with the experiment. In phase 2, the electron temperature increases rapidly after the first 0.4MW ECW is injected. The result shows that the rapid increase of the electron temperature is due to the interaction between the ECW and the electrons. With the increase of the electron temperature, the electron flux induced by the trapped electron modes (TEMs) and the electron temperature gradient driven modes (ETGs) is enhanced in the core region. In phase 3, the electron temperature increases slowly after phase 2. It is found that the slow increase is mainly due to the flattening of the density profile. The flattening of the density profile can decrease the thermal diffusivity of the electrons mainly induced by the TEMs leading to a higher electron temperature for a given heating source. In phase 4, the electron temperature again increases rapidly after the second 0.4MW ECW is injected. The physical mechanism is similar to that in phase 2. In phase 5, the LHW power deposition of the LHW remains almost unchanged compared to that in phase 4 since the electron temperature is sufficiently high. The slow rise of the electron temperature is caused by the improvement of the electron energy confinement as thermal diffusivity of the electrons is decreased due to the flattening of the electron density profile, which is similar to the main reason in phase 3.

在 2018 年 EAST 实验活动中，已经实现了非常高的中心电子加热、全无感放电，核心电子温度超过 9 keV。这种高中心电子加热是通过注入射频波实现的，包括 1.8MW 低混合波 (LHW) 和 0.8MW 电子回旋波 (ECW)。实验诊断表明两个不同的时间尺度表征电子加热过程，注入 ECW 后中心电子温度的快速和缓慢上升。在这项工作中，进行了集成建模以研究这种高电子加热的物理机制。选择电子温度升高期间的五个特征阶段进行建模。在第一阶段，电子加热仅由 LHW 进行。建模证实，LHW 只能维持核心电子温度T _e ≈ 5.5 keV，这与实验一致。在阶段 2 中，在注入第一个 0.4MW ECW 后，电子温度迅速升高。结果表明，电子温度的快速升高是由于ECW与电子之间的相互作用。随着电子温度的升高，由俘获电子模式（TEMs）和电子温度梯度驱动模式（ETGs）诱导的电子通量在核心区域增强。在第三阶段，电子温度在第二阶段之后缓慢上升。. 发现缓慢增加主要是由于密度分布变平。密度分布的平坦化可以降低主要由 TEM 引起的电子的热扩散率，从而导致给定加热源的电子温度更高。在阶段 4 中，在注入第二个 0.4MW ECW 后，电子温度再次快速升高。物理机制与阶段 2类似。在阶段5中，与阶段4相比，LHW的LHW功率沉积几乎没有变化。因为电子温度足够高。电子温度的缓慢上升是由于电子能量限制的改善引起的，因为电子的热扩散率由于电子密度分布的平坦化而降低，这类似于阶段 3 的主要原因。