Local Transport Dynamics of Cold Pulses in Tokamak Plasmas

For over two decades, our fundamental understanding of energy transport dynamics in the core of tokamak plasmas had been challenged by the striking observation of temperature perturbation reversals following the injection of cold pulses at the plasma edge. These phenomena were first discovered by Gentle et al. in 1995 and had long been suggested to be evidence of nonlocal transport effects. In recent years, a new explanation to these phenomena has emerged, fully consistent with the theory of turbulent transport in magnetized plasmas and in remarkable agreement with experiment. This article reviews the experimental observation of temperature reversals in tokamak plasmas and presents the explanation based on local transport physics.

二十余年来，我们对托卡马克（tokamak）等离子体（plasma）芯部能量输运动力学的基本认知，一直受到等离子体边缘注入冷脉冲后观测到的温度扰动反转这一显著现象的挑战。该现象于1995年由Gentle等人首次发现，长期以来被视作非局域输运效应的佐证。近年来，针对该类现象的全新解释应运而生，其与磁化等离子体中的湍流输运理论完全契合，且与实验结果吻合极佳。本文综述了托卡马克等离子体中温度反转现象的实验观测结果，并给出了基于局域输运物理的解释。