【作者】 张志；

【导师】 朱平；

【作者基本信息】 华中科技大学 ， 物理学， 2024， 硕士

【摘要】 为了使托卡马克装置能够达到点火条件,需要采用多种辅助加热手段,这会引入大量高能量粒子,同时在先进托卡马克混合运行模式下,安全因子剖面一般较低,这会触发内扭曲模不稳定性,所以讨论内扭曲模与高能量粒子之间的相互作用将成为重点研究课题之一。为了深入探究这一问题,本学位论文采用NIMROD代码结合先进托卡马克位形特征研究内扭曲模与高能量粒子相互作用,通过对模拟结果的分析,探讨这些现象背后的深层物理机制,为未来聚变反应堆设计和运行提供一定的物理基础。本文首先研究了圆截面位形下高能量粒子对内扭曲模的影响。利用CHEASE程序生成所需的平衡文件,再通过NIMROD程序进行数值模拟计算,研究了反磁剪切、内部输运垒(ITB)和非共振情况对内扭曲模和鱼骨模的影响。结果显示,强反磁剪切对高能量粒子去稳作用有很强抑制,且传统的内扭曲模结构可能会转变为双鱼骨模结构。此外,ITB的存在可能对内扭曲模具有抑制作用,并且对高能量粒子去稳作用的抑制效果取决于ITB的宽度。最后,通过向上平移共振情况的安全因子q剖面,发现非共振情况安全因子剖面最小值qmin对模式具有一定的稳定作用。本文还考察CFETR装置混合模式下三种典型平衡的内扭曲模不稳定性。经NIMROD程序数值模拟计算后发现,只有当高能量粒子比压份数βf足够大时,共振模式会出现鱼骨模不稳定性;而非共振模式增长率几乎随βf线性增长,推测混合模式下共振情况可能是由于压强剖面ITB宽度过宽,有效抑制了内扭曲模不稳定性。尽管非共振情况结果与圆截面结论有所出入,但通过比较两个平衡的q剖面,可能是由于参数qc=q0-qmin(磁轴处安全因子值q0)的致稳作用大于安全因子剖面最小值qmin所导致。更多还原

【Abstract】 To achieve ignition conditions in a tokamak device,various auxiliary heating methods need to be employed,introducing a large number of energetic particles.Moreover,in the advanced tokamak hybrid scenario,the safety factor profile is generally low,triggering internal kink mode instability.Therefore,investigating the interaction between internal kink modes and energetic particles will be one of the key research topics.To delve deeper into this issue,this dissertation employs the NIMROD code in conjunction with the features of advanced tokamak configurations to study the interaction between internal kink modes and energetic particles.By analyzing the simulation results and discussing the underlying physical mechanisms of these phenomena,this work aims to provide some physical base for the design and operation of future fusion reactors.This paper first investigates the influence of energetic particles on internal kink modes in circular cross-section configurations.By analyzing the advanced tokamak configuration,three characteristics—reversed magnetic shear,internal transport barrier,and non-resonant conditions—were extracted and individually considered in the circular cross-section.Utilizing the CHEASE program to generate the required equilibrium files and subsequently employing the NIMROD program for numerical simulation calculations,the study examined the effects of these three characteristics on internal kink modes and fishbone modes.The results indicate that strong reversed shear strongly suppresses the destabilizing effect of energetic particles,and the traditional internal kink mode structure may transition into a double fishbone mode structure.Additionally,the presence of an internal transport barrier may have a suppressing effect on internal kink modes,and the effectiveness of this suppression on the destabilizing of energetic particles depends on the width of the ITB.Finally,by shifting the safety factor q-profile of the resonant case upwards,it was found that the minimum value of the safety factor q-profile,qmin,in the non-resonant case,has a certain stabilizing effect on the mode.This paper also examines the internal kink mode instability of three typical equilibrium under the hybrid mode of the CFETR device.After numerical simulation calculations using the NIMROD program,it was found that only when energetic particles pressure fraction βf is sufficiently large,does the equilibrium under resonant conditions exhibit fishbone mode instability.Meanwhile,under non-resonant conditions,the growth rate of modes increases almost linearly with βf,it is speculated that under the hybrid scenario,the resonance condition may be due to the excessively wide internal transport barrier width,effectively suppressing the instability of internal kink modes.Although the results under non-resonant conditions differ from those under circular cross-sections,a comparison of the q profiles of the two equilibrium suggests that the stabilizing effect of factor qc=q0-qmin(The safety factor value at the magnetic axis,q0)may be more than that of the minimum value of the safety factor q-profile qmin.更多还原