In the present paper the ASDEX Upgrade (AUG) experimental trend of reaching the radiating X-point with nitrogen seeding is reproduced by SOLPS-ITER code modeling. In these experiments the whole divertor region below the X-point is cooled down by the impurity radiation if the seeding rate is large enough, and the maximal radiation is registered from the X-point region, or even from the confinement zone above the X-point. It is demonstrated that for constant seeding rate SOLPS-ITER simulations of the intensively seeded AUG discharges result in that the confined plasma goes into the radiation collapse as a certain threshold in seeding rate is exceeded. This threshold value increases with increasing discharge power. No stable regimes with the electron temperature below 5 eV in the confinement zone even above the X-point are achieved in the modeling if the seeding rate is large enough, in contrast to the experiment. However, such a regime may be achieved if the fueling, seeding and pumping rates are changing in time. Since the SOLPS-ITER code can simulate only steady state, another modeling strategy is chosen. The fueling and seeding rates are artificially reduced by 3 orders of magnitude and the impurity content is set to satisfy the condition that the ratio of electrons contribution originating from fuel atoms to ones coming from impurity atoms is about unity. It is suggested that the radial width of the cooled region in the confinement zone is of the order of the scrape-off layer width λ _q , since it is driven by the same physics leading the energy flux to go from mostly radial to mostly parallel. Under these conditions, the radiative spot above the X-point behaves as the energy sink similarly to the energy sink near the divertor in the conventional regime. In extreme regimes (with large seeding rate), the width of the cold region inside the separatrix may exceed λ _q , and up to 90% of discharge power can be radiated from the confined region. An estimate of the poloidal length of the radiative spot is suggested as well. Flow patterns of neutrals, deuterium ions, impurities, electric current and heat flows are analyzed for the regimes with intensive X-point radiation. The formation of an electric potential peak above the X-point is observed in the simulations, and the corresponding E B drift flux appears to give the largest contribution to the main ion and impurity fluxes. This E B drift flux together with the large ionization source change the parallel velocity with respect to its neoclassical profile. Consequently, the radial E field deviates from the neoclassical one, which might improve the turbulence suppression.

在本文中，通过 SOLPS-ITER 代码建模再现了 ASDEX 升级 (AUG) 实验趋势，即用氮播种达到辐射 X 点。在这些实验中，如果注入速率足够大，则 X 点以下的整个偏滤器区域会被杂质辐射冷却，并且最大辐射记录在 X 点区域，甚至来自 X 点上方的限制区。观点。已经证明，对于恒定的播种速率，密集播种的 AUG 放电的 SOLPS-ITER 模拟导致当超过一定的播种速率阈值时，受限等离子体进入辐射坍塌。该阈值随着放电功率的增加而增加。与实验相反，如果接种速率足够大，则在建模中即使在 X 点以上也无法实现约束区中电子温度低于 5 eV 的稳定状态。然而，如果燃料、播种和泵送速率及时改变，则可以实现这样的制度。由于 SOLPS-ITER 代码只能模拟稳态，因此选择了另一种建模策略。燃料和晶种率人为地降低了3个数量级，杂质含量设置为满足来自燃料原子的电子贡献与来自杂质原子的电子贡献之比大约为1的条件。建议约束区冷却区的径向宽度为刮削层宽度的数量级 然而，如果燃料、播种和泵送速率及时改变，则可以实现这样的制度。由于 SOLPS-ITER 代码只能模拟稳态，因此选择了另一种建模策略。燃料和晶种率人为地降低了 3 个数量级，杂质含量设置为满足来自燃料原子的电子贡献与来自杂质原子的电子贡献之比约为 1 的条件。建议约束区冷却区的径向宽度为刮削层宽度的数量级 然而，如果燃料、播种和泵送速率及时改变，则可以实现这样的制度。由于 SOLPS-ITER 代码只能模拟稳态，因此选择了另一种建模策略。燃料和晶种率人为地降低了 3 个数量级，杂质含量设置为满足来自燃料原子的电子贡献与来自杂质原子的电子贡献之比约为 1 的条件。建议约束区冷却区的径向宽度为刮削层宽度的数量级 燃料和晶种率人为地降低了 3 个数量级，杂质含量设置为满足来自燃料原子的电子贡献与来自杂质原子的电子贡献之比约为 1 的条件。建议约束区冷却区的径向宽度为刮削层宽度的数量级 燃料和晶种率人为地降低了 3 个数量级，杂质含量设置为满足来自燃料原子的电子贡献与来自杂质原子的电子贡献之比约为 1 的条件。建议约束区冷却区的径向宽度为刮削层宽度的数量级λ _q，因为它是由相同的物理学驱动的，导致能量通量从大部分径向变为大部分平行。在这些条件下，X 点上方的辐射点表现为能量汇，类似于常规方案中偏滤器附近的能量汇。在极端情况下（播种率大），分界线内部的冷区宽度可能超过λ _q ，并且可以从受限区域辐射高达 90% 的放电功率。还建议估计辐射点的极向长度。分析了强 X 点辐射的中性、氘离子、杂质、电流和热流的流动模式。在模拟中观察到在 X 点上方形成电势峰，相应的E B漂移通量似乎对主要离子和杂质通量的贡献最大。该E B漂移通量与大电离源一起改变了相对于其新古典主义剖面的平行速度。因此，径向E 场偏离新古典主义，这可能会改善湍流抑制。