Plasma confinement and transport in tokamaks play a crucial role in the development of high poloidal beta steady-state operation scenarios. Therefore, it is very important to study the relevant mechanism of internal transport barriers (ITBs), which can help plasmas to obtain better confinement in order to achieve higher fusion gain. This paper mainly introduces the analysis of the characteristics of electron heat transport of discharges with ITB in high operation regime in Experimental Advanced Superconducting Tokamak (EAST). Based on the statistical analysis of stable discharges with > 1.5, it is found that there is an obvious bifurcation of the normalised electron temperature gradient (ETG) ( ) in the range of = 2–2.2. Then the discharges of lower ( < 2, where the value of is below the bifurcation threshold) and of higher ( > 2.2, where the value of is above the threshold) were selected for analysis. The diagnostic data provided by Thomson scattering, x-ray crystal spectrometry and charge exchange recombination spectroscopy are used to provide reliable parameter profiles and then combined with the data of external magnetic probe measurements and the polarisation interferometer diagnosis system to fully reconstruct the balance. A relevant plasma current calculation model is used to calculate and analyse the current density profiles and power deposition, and then the transport analysis is carried out. Interestingly, in the higher discharges, it is found that the turbulence intensity provided by the CO2 laser collective scattering system gradually decreases and the normalised ETG gradually increases. It is also found that the electron heat transport coefficient decreases in the discharge with higher and the growth rate of the electron-scale turbulence calculated by transport gyro-Landau fluid (TGLF) is significantly reduced. Meanwhile, similar conclusions are also obtained in the discharges when the is further increased.

中文翻译：

---

主电子加热下 EAST 高极向 β 等离子体中电子 ITB 的形成

托卡马克中的等离子体约束和传输在高极向β稳态运行场景的发展中发挥着至关重要的作用。因此，研究内部传输势垒（ITB）的相关机制非常重要，这可以帮助等离子体获得更好的约束，从而获得更高的聚变增益。本文主要介绍了先进超导托卡马克实验装置（EAST）高运行状态下ITB放电的电子传热特性分析。通过对> 1.5稳定放电的统计分析，发现归一化电子温度梯度（ETG）（ ）在= 2~2.2范围内存在明显的分叉。然后选择较低的放电（<2，其中 的值低于分叉阈值）和较高的放电（> 2.2，其中的值高于阈值）进行分析。利用汤姆逊散射、X射线晶体光谱和电荷交换复合光谱提供的诊断数据提供可靠的参数轮廓，然后与外部磁探针测量和偏振干涉仪诊断系统的数据相结合，全面重建天平。使用相关的等离子体电流计算模型来计算和分析电流密度分布和功率沉积，然后进行输运分析。有趣的是，在较高的放电量下，发现CO2激光集体散射系统提供的湍流强度逐渐减小，归一化ETG逐渐增大。研究还发现，放电过程中电子传热系数降低，传输陀螺朗道流体（TGLF）计算的电子尺度湍流增长率显着降低。同时，当进一步增加排放量时，也得到类似的结论。