A diffusive model for halo width growth during vertical displacement events
A diffusive model for halo width growth during vertical displacement events
复制标题
垂直位移事件期间光晕宽度增长的扩散模型
DOI：
10.1088/0029-5515/51/7/073034
复制
发表时间：
2011
期刊：
影响因子：
3.3
通讯作者：
D. Humphreys
中科院分区：
文献类型：
--
作者：
N. Eidietis;D. Humphreys
垂直位移事件期间晕流产生的电磁载荷对热核实验堆船内部件的强度提出了严格的要求。对晕电流演化的预见性了解对于确保这些部件的稳健设计至关重要。决定演化的一个重要因素是等离子体电阻，它是三个量的函数：核区和晕区的电阻率，以及晕区宽度。建立了VDES过程中晕宽度增长的扩散模型，为预测晕流模拟提供了物理基础。扩散模型是由DIII-D观测得到的，DIII-D观测到具有冷后热猝灭等离子体且电流衰减时间远快于垂直运动的VDEs(I型VDE)比较热的等离子体VDEs具有更宽的晕区宽度，后者的电流衰减比垂直运动(II型)慢得多。用二维有限元程序模拟了所选的第I类和第II类DIII-D VDEs过程中环晕电流的扩散。该模型假定在最后的闭合通量表面(LCFS)内有一个核心等离子体区域，将电流扩散到填充在LCFS外的容器中的晕等离子体中。LCFS运动和等离子体温度是由实验观测得到的。该模型所产生的晕宽度演化与I型和II型环晕电流宽度演化的实验测量结果相比，具有较好的一致性。
The electromagnetic loads produced by halo currents during vertical displacement events (VDEs) impose stringent requirements on the strength of ITER in-vessel components. A predictive understanding of halo current evolution is essential for ensuring the robust design of these components. A significant factor determining that evolution is the plasma resistance, which is a function of three quantities: the resistivities of the core and halo regions, and the halo region width. A diffusive model of halo width growth during VDEs has been developed, which provides one part of a physics basis for predictive halo current simulations. The diffusive model was motivated by DIII-D observations that VDEs with cold post-thermal quench plasma and a current decay time much faster than the vertical motion (type I VDE) possess much wider halo region widths than warmer plasma VDEs, where the current decay is much slower than the vertical motion (type II). A 2D finite element code is used to model the diffusion of toroidal halo current during selected type I and type II DIII-D VDEs. The model assumes a core plasma region within the last closed flux surface (LCFS) diffusing current into a halo plasma filling the vessel outside the LCFS. LCFS motion and plasma temperature are prescribed from experimental observations. The halo width evolution produced by this model compares favourably with experimental measurements of type I and type II toroidal halo current width evolution.