电子模湍流与新经典撕裂模多尺度相互作用实验探索

Energetic α particles from fusion reaction will be mainly heating source for future burning plasmas. The fact that α particles mainly heat electrons determines that improving and control electron thermal transport can improve the confinement performance of future fusion reactors and can significantly reduce the cost of electricity from fusion power plants. However, the present transport model based on microturbulence (driven by ion- and/or electron-driven modes) can only explain electron thermal transport in some parameter regimes in present fusion devices. Recent theoretical results in the literature show that microturbulence and macroscopic coherent MHD modes, e.g. Neo-classical Tearing Mode (NTM), can interact nonlinearly and this interaction can affect electron thermal transport. Due to the vast temporal and spatial scale separation between microturbulence and macroscopic coherent MHD modes, it is impossible for the present supercomputers to simulate their nonlinear interactions and there is also a lack of diagnostics capable of measuring them simultaneously on the experimental side. Thus there are very few publications on this subject in the literature. In particular, there is no publication of the interaction between microturbulence and NTM that we are aware of. The CO2 laser collective scattering system on EAST device can detect both microturbulence of k=10-30 cm^-1 in the range of electron-driven turbulence and NTM simultaneously. This proposal aims to exploit this diagnostics, coupled with high-power auxiliary heating available on EAST, to explore the existence of the multi-scale interaction between electron-driven turbulence and NTM as well as the energy transfer direction for the first time. The results from this work will contribute the goal of controlling electron thermal transport and steady-state operation in future fusion devices.

未来聚变等离子体自持燃烧依赖于聚变α粒子的加热，α粒子主要加热电子的性质决定了改善和控制电子热输运能提高聚变反应堆的能量约束性能和降低发电成本。然而现有的微湍流（离子和电子模湍流）模型仅能解释现有聚变装置部分参数范围下的电子热输运。最近理论成果表明：微湍流与宏观磁流体模，如新经典撕裂模，能发生多尺度非线性相互作用并影响电子热输运。由于两者在时空尺度上的巨大跨距，现有计算机能力还不能实现对其相互作用的数值模拟，并且实验中也缺乏能同时测量它们的诊断装置，固数值模拟和实验鲜有相关报道。EAST装置CO2激光相干散射诊断能同时监测k=10-30 cm^-1范围的电子模微湍流以及新经典撕裂模；本课题将主要借助该诊断系统，在高功率辅助加热条件下，初步探索宽波数电子模微湍流可否与新经典撕裂模发生多尺度非线性相互作用过程及其能量传递方向，为未来聚变装置控制反常电子热输运及稳态运行提供重要的线索和数据积累。

未来聚变等离子体自持燃烧依赖于聚变α粒子的加热，α粒子主要加热电子的性质决定了改善和控制电子热输运能提高聚变反应堆的能量约束性能和降低发电成本。探索电子模湍流能否与宏观大尺度MHD模（如新经典撕裂模）发生多尺度非线性相互作用以及它们之间的相互作用方式有助于未来磁约束聚变装置控制反常电子热输运和稳定运行。依托于具有长脉冲运行能力的EAST全超导托卡马克实验平台，本项目借助于有同时监测电子模湍流和宏观磁流体力学模（MHD）能力的CO2激光相干散射诊断系统，展开了电子模湍流与宏观大尺度MHD不稳定性之间的多尺度相互作用的实验研究。我们在国际上首次发现：芯部k=10-30 cm^-1范围的电子模微湍流可与宏观大尺度1/1 MHD 模在很宽的频率范围内直接发生多尺度非线性耦合；我们也在实验上证实：宏观大尺度2/1 MHD模可以通过调节等离子体得平衡参数分布来影响芯部电子模微湍流（k=10-30 cm^-1）的频率以及功率。这俩个重要实验研究结果证实了：宏观大尺度MHD模可以通过直接非线性耦合或改变等离子体平衡参数俩种方式来影响电子模微湍流，进而会影响等离子体电子热输运。我们拓展研究了宏观大尺度下电子模微湍流的行为特征，我们还实验验证了EAST装置CO2激光相干散射诊断测量大尺度结构模的原理。本项目的研究成果为未来ITER及聚变反应堆长脉冲高性能等离子体稳定运行提供了重要的科学依据和数据积累。