Experimental studies of edge shear flow and poloidal residual stress in proximity to the density limit of HL-2A tokamak

doi:10.16568/j.0254-6086.2022s1010

Abstract

Abstract: Recent experimental results about the edge shear flow and poloidal residual stress near the density limit of HL-2A tokamak are reported in this paper. The studies found that the plasma response passes from adiabatic to hydrodynamic response as the plasma density approaches Greenwald density, therefore the residual stress, which is the non-diffusive item in the turbulent Reynolds stress, is reduced. The plasma intrinsic poloidal torque characterized by the divergence of residual stress decreases drastically. The reduction of turbulent generation of edge poloidal flow leads to the decreased edge E×B poloidal flow shearing rate. These experimental results demonstrate the important role of reduced residual stress in the edge poloidal shear layer collapse in the proximity of tokamak density limit.

Key words: HL-2A tokamak, Greenwald density limit, Edge turbulence, E×B shear flow, Reynolds stress, Residual stress

摘要： 报道了HL-2A装置密度极限附近边缘剪切流和极向剩余胁强的最新实验研究结果。研究发现，等离子体密度向Greenwald密度靠近时，等离子体响应由绝热响应向流体动力学响应转变，导致湍流雷诺胁强中的非扩散项——剩余胁强降低，其径向梯度表征的等离子体自发旋转力矩显著降低。边缘极向流的湍性驱动降低进一步导致边缘E×B 极向流剪切强度减弱。这些实验结果证明了湍流剩余胁强的降低是导致托卡马克密度极限附近边缘极向剪切层崩塌的关键因素。

关键词: HL-2A装置；Greenwald密度极限；边缘湍流；E×B , 剪切流；雷诺胁强；剩余胁强

CLC Number:

O533

LONG Ting, Diamond P H, KE Rui, HONG Rong-jie, XU Min, NIE Lin, WANG Zhan-hui, LI Bo, GAO Jin-ming, HL-M Team. Experimental studies of edge shear flow and poloidal residual stress in proximity to the density limit of HL-2A tokamak[J]. Nuclear Fusion and Plasma Physics, 2022, 42(s1): 152-157.

龙婷, Diamond P H, 柯锐, 洪荣杰, 许敏, 聂林, 王占辉, 李波, 高金明, HL-A团队. HL-2A装置密度极限附近边缘剪切流和极向剩余胁强的实验研究[J]. 核聚变与等离子体物理, 2022, 42(s1): 152-157.

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