Type I Edge Localized Modes (ELMs) occur naturally in H-mode plasmas, the operational regime envisaged for ITER, and lead to high temporal heat load peaks on plasma-facing components that might induce surface melting and deteriorated material properties due to recrystallization. ELM mitigation techniques are being developed that either attempt to fully suppress the ELM, e.g. using resonant magnetic perturbations (RMP), or to trigger the ELM at higher frequencies, intending to reduce its energy content and hence the heat load peak.

In this paper, the effect of the increased ELM frequency achieved by ELM mitigation techniques on the ITER tungsten divertor monoblock thermal and recrystallization behavior is numerically analyzed by solving the unsteady heat conduction equation when repeatedly exposing the monoblock to ELM-like heat loads under ITER baseline burning plasma operating conditions. The impinging heat load is based on a set of empirical relations readily found in literature and the recrystallization fraction is computed using an empirical data fit which is based on the non-isothermal JMAK equation as function of temperature and time. Uncertainties such as the statistical spread on empirical relations and the unknown inter-ELM heat load, as well as the effect of the ELM frequency, are quantified by a parameter scan.

Adopting the recently developed concept of a ‘recrystallization budget’ to determine the allowed monoblock heat loads [G. De Temmerman et al., PPCF 60 (2018) 0044018], it was found that ELM frequencies between 25 – 50 Hz are allowed for inter-ELM heat loads between 9 – 6 MW m${}^{-2}$ , respectively, when assuming that the scaling for the peak ELM target energy density in [T. Eich et al., NME 12 (2017) 84-90] holds. This provides a new limit for ELM mitigation strategies in ITER.

I型边缘局限模式（ELM）自然发生在H模式等离子体中，这是ITER所设想的运行方式，并导致面向等离子体的组件上出现了较高的瞬时热负荷峰值，这可能会导致表面熔化和由于重结晶而导致的材料性能下降。正在开发ELM缓解技术，这些技术试图完全抑制ELM（例如，使用共振磁扰动（RMP）），或者尝试在较高频率下触发ELM，以降低其能量含量，从而降低热负荷峰值。

本文通过在ITER基线下反复将整块单体暴露于类似ELM的热负荷时求解不稳定的热传导方程，通过数值分析来分析通过ELM缓解技术获得的ELM频率增加对ITER钨分流器整体的热和再结晶行为的影响。燃烧等离子体的工作条件。冲击热负荷是基于在文献中容易找到的一组经验关系，并且使用基于非等温JMAK方程作为温度和时间的函数的经验数据拟合来计算重结晶分数。通过参数扫描可以量化不确定性，例如经验关系的统计分布和未知的ELM间热负荷以及ELM频率的影响。

采用最近开发的“重结晶预算”概念来确定允许的整体热负荷[G. De Temmerman等人，PPCF 60（2018）0044018]，发现在9 – 6 MW m之间的ELM间热负荷允许25 – 50 Hz之间的ELM频率${}^{-\mathrm{2个}}$分别假设峰ELM的缩放目标能量密度[T. Eich等人，NME 12（2017）84-90]成立。这为ITER中的ELM缓解策略提供了新的限制。