The aim of this paper is to study the influences of plasma heating and plasma density on impurity production and transport during the plasma-termination phase. We have analyzed the ramp-down (RD) phase of a set of representative high-current JET ITER-like wall discharges: #92 437 (disrupted) and #92 442 (soft landing), characterized by a high plasma current of I _p = 3.5MA. Analysis is performed for different time slots within the RD phase, corresponding to different levels of electron line density and auxiliary heating power. Since the deuterium gas fluxes are different, the influence of the separatrix density is also analyzed. The main conclusion from the simulations is the observation that for the same average-electron density, a decrease of the separatrix density leads to an increase of the plasma temperature at the divertor plate, leading to increased W production and consequently to a larger W concentration and radiation in the core. When the central electron temperature approaches the 2 keV level, corresponding to the maximum W and Ni cooling rate, the radiation in the plasma’s center is enhanced. Ni radiation is more important in the RD phase.

本文的目的是研究在等离子体终止阶段等离子体加热和等离子体密度对杂质产生和传输的影响。我们分析了一组具有代表性的高电流，类似于JET ITER的壁式放电的下降（RD）阶段：＃92 437（已中断）和＃92 442（软着陆），其特征在于I _p高的等离子体电流 = 3.5MA。针对RD阶段内的不同时隙执行分析，对应于电子线密度和辅助加热功率的不同水平。由于氘气体通量不同，因此还分析了分离密度的影响。从模拟得出的主要结论是，观察到对于相同的平均电子密度，分离密度降低会导致分流板处的等离子体温度升高，从而导致产生的W增加，从而导致更大的W浓度和辐射在核心。当中心电子温度接近2 keV水平时，对应于最大的W和Ni冷却速率，等离子体中心的辐射会增强。Ni辐射在RD阶段更为重要。