负三角形变位型下剥离气球模的非线性演化特征  

Nonlinear evolution characteristics of peeling-ballooning mode under negative triangularity

作　　者：秦晨晨 牟茂淋 陈少永[1,2] Qin Chen-Chen;Mou Mao-Lin;Chen Shao-Yong(College of Physics,Sichuan University,Chengdu 610064,China;Key Laboratory of High Energy Density Physics and Technology,Ministry of Education,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学物理学院,成都610065 [2]四川大学,高能量密度物理国家重点实验室,成都610065

出　　处：《物理学报》2023年第4期178-184,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11905152);国家磁约束核聚变能发展研究专项(批准号:2019YFE03090400,2019YFE03030004);国家重点研发计划(批准号:2017YFE0301203,2017YFE0301101);四川省自然科学基金(批准号:2022NSFSC1820)资助的课题。

摘　　要：托卡马克实验中已经实现了负三角形变位型下的高约束放电,其特点是具有较低的台基,并伴随幅值较小且频率较高的边界局域模.本文基于不同三角形变的托卡马克平衡,研究了负三角形变位型条件下剥离气球模的非线性演化特征.研究发现,由于弱场侧坏曲率区域增大,负三角形变位型会使剥离气球模失稳;在非线性阶段,负三角形变位型下的剥离气球模压强扰动分布在极向截面上扩展到了弱场侧的顶部和底部区域,使得边界局域模更早发生崩塌,同时,在负三角形变位型下,多种环向模数的扰动被激发并增长,故而具有更明显的湍流输运特性.Experiments on TCV tokamak have achieved high confinement mode(H-mode) operation with negative triangularity,and this mode shows quite different characteristics from those with the positive triangularity in experiment and simulation.Linear simulations for kinetic ballooning mode and peeling-ballooning(PB) mode without diamagnetic effect show that negative triangularity can enhance the instability of the ballooning mode and close access to the second stable region.However,the understanding of ELM for negative triangularity is not sufficient.Therefore,it is necessary to carry out further research on ELM with negative triangularity.In this work,based on a series of equilibria with different triangularities in Tokamak,the nonlinear characteristics of negative triangularity of PB mode is investigated.It is found that the negative triangularity can destabilize the PB mode by a larger unfavorable curvature region,which will reduce the instability threshold,and thus limiting the increase of pedestal height.In the nonlinear phase,the pressure perturbation intensity with negative triangularity will extend to the top area and the bottom area in the low field side and bring about an earlier ELM collapse.Meanwhile,modes with different toroidal mode numbers are more likely to be triggered off and then grow and replaces the initial unstable mode,showing more obvious turbulent transport characteristics,which can play a role in the ELM energy loss.

关 键 词：边界局域模 剥离气球模 负三角形变位型 

分 类 号：TL631.24[核科学技术—核技术及应用]