The experimental reproduction of the conditions of pellet injection expected in future large devices being not possible in present day machines, it is mandatory to validate as thoroughly as possible the available ablation models. Among the different points still under discussion, there is the relation between the spectroscopic measurement of the ablation clouds and the local ablation rate. This relation is investigated by coupling an emission model to the time-dependent simulation of ablation clouds with the HPI2 pellet ablation/deposition code. The simulated quantities are the time-evolution of the cloud visible spectrum (λ = 400–700 nm) and images in different wavelength domains (e.g. Hα,Hβ or the continuum centered at λ=576nm ). It is found that the cloud emission is anisotropic, this is particularly the case for H _α and H _β lines, and that the relation between the cloud emission and the ablation rate depends not only on the conditions of pellet injection, but also on the direction of observation. It follows that, in general, it is not possible to estimate the ablation profile from that of an emission line (Hα or Hβ) . The code predictions are compared with corresponding measurements for a welldocumented pellet injected in LHD, showing a good agreement for global values and main trends. The reasons for observed discrepancies are discussed.

中文翻译：

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颗粒云发射的结构及其与局部烧蚀率的关系

未来大型设备中预期的颗粒注射条件的实验再现在当今的机器中是不可能的，因此必须尽可能彻底地验证可用的消融模型。在仍在讨论的不同点中，烧蚀云的光谱测量与局部烧蚀率之间的关系。通过使用 HPI2 颗粒烧蚀/沉积代码将发射模型与烧蚀云的时间相关模拟相耦合来研究这种关系。模拟量是云可见光谱的时间演化（λ= 400–700 nm）以及不同波长域中的图像（例如 Hα,Hβ 或以 λ=第576章纳米 ）。发现云发射是各向异性的，尤其是H _α 和H _β 线，并且云发射和烧蚀率之间的关系不仅取决于颗粒注入的条件，还取决于观察的方向。因此，一般来说，不可能根据发射线的烧蚀轮廓来估计烧蚀轮廓 （Hα 或者 Hβ） 。将代码预测与 LHD 中注入的有据可查的颗粒的相应测量结果进行比较，显示出全局值和主要趋势的良好一致性。讨论了观察到的差异的原因。