L-H转换过程中涨落引起输运变化的实验研究

约束改善的研究一直是磁约束聚变研究中的重点，未来的磁约束聚变反应堆都会运行在高约束模状态下,现阶段高约束模产生机理尚不是十分明确。实验和理论发现，E×B剪切流在低约束模向高约束模(L-H模)转换中起着重要作用。然而，到底是径向电场E的哪一个驱动项决定了此过程中的径向电场梯度变化、带状流在模转换中所起的作用、哪一个驱动项决定了径向输运变化等关键物理问题研究尚缺乏有说服力的实验证据。国内已有较多基于等离子体参数平衡量的实验研究，但是缺乏系统的基于涨落量的实验研究，对一些物理机制的理解也存在争议。本项目立足于国内外L-H模转换机制的研究现状，提出了在HL-2A托卡马克上针对模转换过程中涨落引起的输运变化来开展实验研究，可以加深对于L-H模转换机制的物理理解。

Confinement improving is key in magnetically confined fusion. The future fusion reactor is believed to be operated in High Confinement Mode (H-mode) configuration. The underlying mechanism of transition from Low Confinement Mode (L-mode) to H-mode is still not clear. Experimental and theoretical evidences show that E×B shear flow plays an important role in this transition. Many key issues remain open. Which term dominates the gradient of radial electric field in L-H transition? Which term dominates radial particle flux? What is the role of zonal flow in this transition? Many experiments are performed to understand the underlying physics basing on zero order parameters, but few work is systematically done from the view point of fluctuations. In this project, turbulence induced transport in L-H transition will be experimentally investigated in HL-2A tokamak, which will enhance the physical understanding of the longstanding problem of L-H confinement transition mechanism.