Nonlinear MHD simulations of QH-mode DIII-D plasmas and implications for ITER high Q scenarios
Nonlinear MHD simulations of QH-mode DIII-D plasmas and implications for ITER high Q scenarios
复制标题
QH 模式 DIII-D 等离子体的非线性 MHD 模拟及其对 ITER 高 Q 场景的影响
DOI：
10.1088/1361-6587/aa934f
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发表时间：
2017
影响因子：
2.2
通讯作者：
D. V. Vugt
中科院分区：
文献类型：
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作者：
Feng Liu;G. Huijsmans;A. Loarte;A. Garofalo;W. Solomon;M. Hoelzl;B. Nkonga;S. Pamela;M. Becoulet;F. Orain;D. V. Vugt
在对DIII-D QH模等离子体的非线性MHD模拟中发现，低n阶扭结/剥离模（KPMs）是不稳定的，并且会发展到饱和扭结-剥离模。主导饱和KPMs，这是本地化的谐波，如模式频率，密度波动及其对基座粒子和能量传输的影响的非线性耦合的环形的功能，是在良好的协议与边缘谐波振荡的观察通常存在于DIII-D QH模式实验。通过改变基座电流和压强相对于DIII-D QH模等离子体初始条件的变化，研究了MHD模（包括扭结剥离模和气球模）的非线性演化.边缘电流和压力在基座是关键参数的等离子体无论是饱和到QH模式政权或气球模式占主导地位的政权。研究了E × B流及其剪切对QH模等离子体的影响。E × B流剪切对中到高n模式有很强的稳定作用，但对n = 2模式有不稳定作用。ITER Q = 10等离子体的QH模外推结果表明，基座电流足够大，使n = 1-5 KPMs不稳定，导致稳定的饱和扭结剥离模。
In nonlinear MHD simulations of DIII-D QH-mode plasmas it has been found that low n kink/peeling modes (KPMs) are unstable and grow to a saturated kink-peeling mode. The features of the dominant saturated KPMs, which are localised toroidally by nonlinear coupling of harmonics, such as mode frequencies, density fluctuations and their effect on pedestal particle and energy transport, are in good agreement with the observations of the edge harmonic oscillation typically present in DIII-D QH-mode experiments. The nonlinear evolution of MHD modes including both kink-peeling modes and ballooning modes, is investigated through MHD simulations by varying the pedestal current and pressure relative to the initial conditions of DIII-D QH-mode plasma. The edge current and pressure at the pedestal are key parameters for the plasma either saturating to a QH-mode regime or a ballooning mode dominant regime. The influence of E × B flow and its shear on the QH-mode plasma has been investigated. E × B flow shear has a strong stabilisation effect on the medium to high-n modes but is destabilising for the n = 2 mode. The QH-mode extrapolation results of an ITER Q = 10 plasma show that the pedestal currents are large enough to destabilise n = 1–5 KPMs, leading to a stationary saturated kink-peeling mode.