Electromagnetic gyrokinetic instabilities in the Spherical Tokamak for Energy Production (STEP) part II: transport and turbulence
Electromagnetic gyrokinetic instabilities in the Spherical Tokamak for Energy Production (STEP) part II: transport and turbulence
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用于能源生产的球形托卡马克 (STEP) 中的电磁回旋不稳定性第二部分：传输和湍流
DOI：
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
C. Roach
中科院分区：
文献类型：
--
作者：
M. Giacomin;D. Kennedy;F. Casson;D. Dickinson;B. Patel;C. Roach
.在这项工作中，我们提出的第一类非线性局部陀螺动力学模拟的电磁湍流在中等半径的燃烧等离子体阶段的概念高β，反应堆规模，紧纵横比托卡马克步骤（球形托卡马克能源生产）。在D.Kennedy等人提交给Nucl.Fusion [1]的先前线性分析中，揭示了在接近离子拉莫尔半径的副法线尺度下存在不稳定的混合动力学气球模式和次显性微撕裂模式。当地的非线性gyrokinetic模拟，使用三种不同的代码，是在定性和定量的协议，并建议混合动力气球模式驱动非常大的湍流运输在没有平衡流剪切。热通量上升到超过可用的加热功率的数量级的值和湍流涡流高度径向延伸，使它们可能无法很好地描述的本地gyrokinetic模型。饱和输运通量对平衡流剪切非常敏感，并且流剪切的抗磁水平可以在所选表面上将通量抑制到更合理的值。考虑到这种敏感性，饱和通量存在很大的不确定性。次主导的微撕裂模式的可能的运输影响进行了分析，在隔离人工和非物理删除压缩磁扰动的非线性计算，以抑制占主导地位的混合动力气球模式。微撕裂热通量被发现饱和在可以忽略的值，虽然我们不能排除的可能性，微撕裂湍流可能是更多的运输相关的参数空间的其他区域。
. In this work, we present the results of first-of-their-kind nonlinear local gyrokinetic simulations of electromagnetic turbulence at mid-radius in the burning plasma phase of the conceptual high-β , reactor-scale, tight-aspect-ratio tokamak STEP (Spherical Tokamak for Energy Production). A prior linear analysis in D.Kennedy et al. submitted to Nucl. Fusion [1] reveals the presence of unstable hybrid kinetic ballooning modes and subdominant microtearing modes at binormal scales approaching the ion-Larmor radius. Local nonlinear gyrokinetic simulations, using three different codes, are in qualitative and quantitative agreement and suggest that hybrid kinetic ballooning modes drive very large turbulent transport in the absence of equilibrium flow shear. The heat flux rises to values that exceed the available heating power by orders of magnitude and the turbulent eddies are highly extended radially so that they may not be well described by the local gyrokinetic model. The saturated transport fluxes are extremely sensitive to equilibrium flow shear, and diamagnetic levels of flow shear can suppress the fluxes to more reasonable values on the chosen surface. Given this sensitivity there is a large uncertainty in the saturated fluxes. The possible transport impact of the subdominant microtearing modes is also analysed in isolation by artificially and unphysically removing compressional magnetic perturbations from nonlinear calculations, to suppress the dominant hybrid kinetic ballooning mode. The microtearing heat flux is found to saturate at negligible values, though we cannot exclude the possibility that microtearing turbulence may be more transport relevant in other regions of parameter space.
影响因子：
2.2
作者：
McMillan B
通讯作者：
McMillan B