10月24日  Modeling of the dynamics of the transition to the XPR by SOLPS-ITER on ASDEX Upgrade and EAST

时间：2025年10月24日 星期五 14:00

地点：六室301会议室

主持人：丁锐

报告人介绍：Ilya Senichenkov，俄罗斯圣彼得堡彼得大帝理工大学副教授，中国科学院国际人才计划（PIFI）国际访问学者，是SOLPS-ITER程序漂移功能及程序加速方案的主要贡献者之一，发表论文40余篇，主要科研领域：托卡马克边界粒子、能量和动量输运；偏滤器物理；弹丸消融和托卡马克加料等。

报告内容：

The dynamical modeling of the transition to the XPR is performed by SOLPS-ITER and analyzed. The initial cooling of ions in the confined region is due convective mixing provided by cold plasma diffusion from the HFSHD region in the SOL rather than by ionization and heating of neutrals. The loss of energy is compensated by the parallel heat conductivity, and the drop of the  is enhanced near the X-point due to big flux expansion and big distance along the B-field lines. To maintain the pressure, ion and electron density increase, giving favorable conditions for impurity radiation proportional to . In fact, pressure even increases to drive particle fluxes along the B-field, further increasing the , and, as a consequence, the electric potential. The resulting potential hill causes vortex -drift flows, which enhance convective cooling of ions. Further, as the impurity radiation starts to be important in energy balance,  drops deeper to provide the energy source via parallel heat conductivity.

In the SOLPS-ITER modeling it is necessary to introduce feedback loop, which turns off the impurity seeding rate as the  drops below the prescribed threshold (or the radiated power exceeds the prescribed threshold). This approach results in stable steady state solution with developed XPR.

On EAST (in its DDN topology) the situation is more complicated, because i) the HFSHD exists only between primary and secondary separatrix and is less pronounced than in AUG; ii) the secondary XPR forms near the upper inactive X-point, which leads to the cooling of the LCFS both from top and from bottom. At the top the additional mechanism for the initial ions cooling is the neoclassical convection (in favorable B-field with ions -drift directed towards the active X-point). The formation of top XPR is clearly seen in dynamical and steady state modeling cases for N, Ne and Ar, and it is consistent to experimental observations. Similar radiation from the inactive X-point is observed on other machines in experiment (ASDEX Upgrade, TCV) and in SOLPS modeling (Globus-M2, CFETR).