Sawtooth induced q-profile evolution at ASDEX Upgrade
Sawtooth induced q-profile evolution at ASDEX Upgrade
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DOI：
10.1088/1741-4326/ab0b65
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发表时间：
2019-03
期刊：
影响因子：
3.3
通讯作者：
R. Fischer;A. Bock;A. Burckhart;O. Ford;L. Giannone;V. Igochine;M. Weiland;M. Willensdorfer
中科院分区：
文献类型：
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作者：
R. Fischer;A. Bock;A. Burckhart;O. Ford;L. Giannone;V. Igochine;M. Weiland;M. Willensdorfer
在ASDEX升级中对激光诱导的q分布演变进行建模，并使用成像运动斯塔克效应（IMSE）测量进行验证。通过耦合Grad-Shafranov求解器和电流扩散方程来估计平衡电流分布。在ASDEX升级一个广泛的诊断套件允许一个可靠的建模的电流密度分布及其时间演变，只要新古典电流扩散可以假设。锯齿波引起的中心q变化，，估计从平衡重建之间的事件，而不使用IMSE测量。锯齿诱导电流弛豫建模与两种不同的重联模型，Kadomtsev完全重联和新开发的完全随机的平电流模型。两种模型的锯齿诱导值大致相同，为0.10-0.12，但绝对q 0值差异较小。锯齿引起的演化的正向建模MSE角度同意与IMSE测量。这证实了新古典的电流扩散之间的事件的假设。敏感性研究揭示了可靠解释MSE测量的两个主要因素。首先，必须考虑锯齿引起的快离子的再分布，以可靠地估计Shafranov位移。快离子的再分配模型与粒子守恒均匀的快离子的压力分布在等离子体核心和随后的恢复时间为50毫秒。其次，一个可靠的估计电场是必要的一个可信的解释的MSE角。
The sawtooth induced q-profile evolution was modelled at ASDEX Upgrade and validated with imaging motional Stark effect (IMSE) measurements. The equilibrium current distribution was estimated by the coupling of a Grad–Shafranov solver and the current diffusion equation. At ASDEX Upgrade an extensive diagnostic suite allows for a reliable modelling of the current density profile and its temporal evolution as long as neo-classical current diffusion can be assumed. The sawtooth-induced central q change, , was estimated from equilibrium reconstruction between the sawtooth events without using IMSE measurements. The sawtooth-induced current relaxation is modelled with two different reconnection models, a Kadomtsev full reconnection and a newly developed fully stochastic flat-current model. Both models result in about the same sawtooth-induced 0.10–0.12 but with a small difference in the absolute q0 values. The sawtooth-induced evolution of the forward modelled MSE angles agrees well with the IMSE measurements. This confirms the assumption of neo-classical current diffusion between the sawtooth events. A sensitivity study reveals two major ingredients for a reliable interpretation of MSE measurements. Firstly, the sawtooth-induced redistribution of fast ions has to be taken into account for a reliable estimation of the Shafranov shift. The fast-ion redistribution is modelled with a particle-conserving homogeneous fast-ion pressure profile in the plasma core and a subsequent recovery time of 50 ms. Secondly, a reliable estimation of the electric field is necessary for a credible interpretation of the MSE angles.