论文标题
切向NBI电流驱动器对LHD等离子体中压力和能量粒子驱动的MHD模式的稳定性的影响
Effect of the tangential NBI current drive on the stability of pressure and energetic particle driven MHD modes in LHD plasma
论文作者
论文摘要
本研究的目的是分析大型螺旋装置(LHD)等离子体中压力梯度驱动模式(PM)和Alfven Eigenmodes(AE)的稳定性,如果旋转变换通过切向中性束注射器(NBI)的当前驱动器进行了修改。这项研究构成了以减少模式活动的优化操作方案的基本搜索。使用代码FAR3D进行分析,该代码求解了还描述完整3D系统中涡度磁通的线性演化和涡度的线性演化,并与旋转系统的涡度分量以及效应粒子(EP)物种的密度和平行速度矩的方程式,包括声学模式的效果。通过封闭关系添加了Landau阻尼和共振的不稳定效应。轴上和离轴NBI电流驱动器会改变旋转变换,随着中性束电流驱动力(NBCD)的强度增加,旋转变换会严重扭曲,从而导致更宽的连续性间隙并修改磁性剪切。轴上NBI注射的模拟表明,尽管强大的n = 1和2 AES可能会稳定下,但内向移动和默认配置中的计数器(CTR-)NBCD导致PM的生长速度较低。对于向外移动的配置,CO-NBCD提高了AES稳定性,但如果CO-NBCD强度为30 ka/t,则PM进一步稳定。如果NBI注射是离轴的,则由于AE和高质量粒子模式(EPM)进一步不稳定,血浆稳定性不会显着提高。
The aim of the present study is to analyze the stability of the pressure gradient driven modes (PM) and Alfven eigenmodes (AE) in the Large Helical Device (LHD) plasma if the rotational transform profile is modified by the current drive of the tangential neutral beam injectors (NBI). This study forms a basic search for optimized operation scenarios with reduced mode activity. The analysis is performed using the code FAR3d which solves the reduced MHD equations describing the linear evolution of the poloidal flux and the toroidal component of the vorticity in a full 3D system, coupled with equations for density and parallel velocity moments of the energetic particle (EP) species, including the effect of the acoustic modes. The Landau damping and resonant destabilization effects are added via the closure relation. On-axis and off-axis NBI current drive modifies the rotational transform which becomes strongly distorted as the intensity of the neutral beam current drive (NBCD) increases, leading to wider continuum gaps and modifying the magnetic shear. The simulations with on-axis NBI injection show that a counter (ctr-) NBCD in inward shifted and default configurations leads to a lower growth rate of the PM, although strong n=1 and 2 AEs can be destabilized. For the outward shifted configurations, a co-NBCD improves the AEs stability but the PM are further destabilized if the co-NBCD intensity is 30 kA/T. If the NBI injection is off-axis, the plasma stability is not significantly improved due to the further destabilization of the AE and energetic particle modes (EPM) in the middle and outer plasma region.