HL-2A托卡马克偏滤器脱靶时边缘极向旋转和湍流动量输运  

Studies of edge poloidal rotation and turbulence momentum transport during divertor detachment on HL-2A tokamak

作　　者：龙婷 柯锐 吴婷 高金明 才来中 王占辉 许敏 Long Ting;Ke Rui;Wu Ting;Gao Jin-Ming;Cai Lai-Zhong;Wang Zhan-Hui;Xu Min(Southwestern Institute of Physics,Chengdu 610225,China)

机构地区：[1]核工业西南物理研究院,成都610225

出　　处：《物理学报》2024年第8期369-376,共8页Acta Physica Sinica

基　　金：国家磁约束核聚变能发展研究专项(批准号:2022YFE03100004);国家自然科学基金(批准号:12375210);四川省科学技术厅项目(批准号:2022JDRC0014);中核集团青年英才项目(批准号:2021JZYF-03)资助的课题.

摘　　要：偏滤器脱靶为降低托卡马克靶板热负荷提供了一种有效的解决方案,但脱靶可能引起边界等离子体状态发生变化,影响整体约束性能.本文报道了在中国环流器二号A托卡马克上开展的L模放电偏滤器脱靶时边界等离子体极向旋转和湍流动量输运的实验研究.采用在偏滤器室注入混合气体(60%氮气+40%氘气)的方式实现了偏滤器脱靶.研究发现,在未脱靶-预脱靶-脱靶过程中,实验测得的近刮削层区域E×B极向流速与湍流动量对极向旋转的驱动作用(雷诺应力)的演化一致;相较于未脱靶状态,脱靶时等离子体边缘极向速度剪切明显降低,导致湍流水平增强.在湍流输运和辐射都增强的共同作用下,等离子体整体约束性能下降.研究表明,边缘湍流输运和等离子体旋转动力学在偏滤器脱靶影响整体约束的芯-边耦合机制中发挥作用.In a magnetic confinement fusion device,the plasma undergoing nuclear fusion reaction must be maintained in a high-temperature and high-density confinement state for a long enough time to release high energy,while the heat loads on the divertor target plates need to be reduced to avoid damage to wall at the same time.The latter is one of the key challenges of ITER and commercial fusion reactors in future.Divertor detachment provides an effective solution to reduce the heat load on the target plate of tokamak.However,this may result in the change of plasma states at the boundary,thus affecting the plasma confinement.In this paper,edge plasma poloidal rotation and turbulence momentum transport are studied experimentally during the divertor detachment in the L-mode discharge of HL-2A tokamak.The detachment is achieved by injecting a mixture of gas(60%nitrogen+40% deuterium)into the divertor.The gas mixture is injected by pulsed injection,with pulse length being in a range of 5-20 ms.During the divertor detached phase,both the ion saturation current density and the heat flux to the outer target plate decrease considerably.The enhanced radiation is also observed in the divertor and X-point region.It is found that in the process of attachment-topre-detachement,the E×B poloidal flow velocity in the near scrape-off layer(SOL)changes from ion magnetic drift direction to electron magnetic drift direction.The turbulent driving force of poloidal flow,which is characterized by the negative radial gradient of momentum transfer flux(Reynolds stress),shows the same trend.In the detached phase,both the E×B flow and the Reynolds force become very small.Therefore,the dynamics of E×B poloidal flow velocity in the SOL is consistent with the evolution of rotation driving effect induced by the turbulent momentum transport.Combined with the E×B poloidal flow measured by the probe in the SOL and the beam emission spectrum inside the LCFS,the E×B poloidal velocity shearing rate near the LCFS can be inferred.Compared with the attached

关 键 词：核聚变能 偏滤器 等离子体湍流 等离子体流 

分 类 号：TL631.24[核科学技术—核技术及应用]