ITER (www.iter.org) will take advantage of tungsten (W) actively cooled plasma facing units (PFUs) in the lower divertor. These PFUs will receive a steady state plasma heat flux of 10MWm⁻² and up to 20MWm⁻² in slow transients, pushing these components to their limit. For machine protection reasons and for the study of the plasma wall interactions, temperature measurements are foreseen with mid wave infra-red (MWIR: 3–5 μm) thermography systems to cover most of the ITER chamber, including the divertor (tungsten material) and first wall (beryllium material) [1]. Absolute temperature measurements from 70 C and the cooling temperature of the PFUs, up to 3500 C (W melting temperature at 3422 C), are considered. Those measurements require knowledge of the emissivity of the tungsten PFU surfaces as a function of the temperature and wavelength used for the IR monochrome thermography system. This paper summarizes the emissivity measurements performed on tungsten surfaces in high heat flux test beds and the WEST tokamak [2] and uses the experimental emissivity values to compute the expected uncertainties in ITER (ΔT/T) using monochrome and bicolor thermography techniques. The results show that the monochrome technique is not able to fulfill the ΔT/T < 10% requirement, while the bicolor technique is able to reduce the temperature uncertainty below 10%. Laboratory bicolor thermography measurements using a filter wheel (including six MWIR interference filters) have been successfully performed up to 830 C with temperature uncertainty ΔT/T < 3%. In the WEST tokamak, the two dimensions emissivity map is varying by a factor of five within 27cm along a PFU, from 0.13 to 0.65, showing that the monochrome IR thermography will have difficulties staying within the ITER requirements ΔT/T < 10% from 70 C up to 3500 C.

ITER (www.iter.org) 将利用下部偏滤器中的钨 (W) 主动冷却等离子体面对单元 (PFU)。这些 PFU 将在缓慢瞬变中接收 10MWm ^-2和高达 20MWm ^-2的稳态等离子体热通量，将这些组件推向极限。出于机器保护的原因和等离子体壁相互作用的研究，可以预见温度测量中波红外（MWIR：3-5 μm) 覆盖大部分 ITER 室的热成像系统，包括偏滤器（钨材料）和第一壁（铍材料）[1]。考虑了 70 C 的绝对温度测量值和 PFU 的冷却温度，最高可达 3500 C（W 熔化温度为 3422 C）。这些测量需要了解钨 PFU 表面的发射率作为红外单色热成像系统使用的温度和波长的函数。本文总结了在高热通量试验台和西托卡马克 [2] 中对钨表面进行的发射率测量，并使用实验发射率值来计算 ITER 中的预期不确定性 (Δ T / T) 使用单色和双色热成像技术。结果表明，单色技术无法满足ΔT / T < 10% 的要求，而双色技术能够将温度不确定性降低到 10% 以下。使用滤光轮（包括六个 MWIR 干涉滤光片）的实验室双色热成像测量已在高达 830°C 的温度下成功进行，温度不确定度 Δ T / T < 3%。在西托卡马克，二维发射率图沿 PFU 在 27 厘米范围内变化了五倍，从 0.13 到 0.65，表明单色红外热成像将难以保持在 ITER 要求ΔT / T < 10% 从 70 C 到 3500 C。