Micro structured tungsten is a new approach to address one of the main issues of tungsten as high heat flux (HHF) plasma facing material (PFM), which is its brittleness and its propensity to crack formation under pulsed, ELM like, heat loads (Loewenhoff et al., 2015; Wirtzet al., 2015 [2,3]). With power densities between 100 MW/m² and 1 GW/m², progressive thermal fatigue induced damages like roughening, subsequent cracking and even melting will occur in dependence on the pulse number and PFM base temperature. This represents a serious issue for the usage of tungsten as HHF-PFM. In future tokamaks, such as ITER, about 10⁸ ELMs are expected to occur during the operational lifetime.

Several approaches have been tried to overcome this brittleness issue, e.g. alloying tungsten with others elements (Linsmeier et al., 2017 [4]) or introducing pseudo-ductility due to the additions of fibres thus creating composites (Reiser et al., 2017 [5]). Micro-structured tungsten showed a significant improvement in comparison with any of these approaches with respect to the damage expected by ELMs. This investigation on both bulk reference and micro-structured tungsten was performed in the PSI-2 facility (Kreter et al., 2015 [8]). A sequential load was applied combining steady state deuterium plasma (5.1 × 10²⁵ D + m⁻², 51 eV, 240 °C, 150 min) loading with laser pulses (up to 10⁵ pulses of 0.5 GW/m², 3.6 mm spot diameter, 20 J, 1 ms pulse duration, up to 25 Hz pulse frequency). In contrast to reference bulk tungsten, none of the applied loading conditions caused any evident damage on the micro-structured tungsten. The maximum surface temperature within the loaded area measured with a fast pyrometer was increased by about 800 °C at the end of the laser exposure for the reference sample. This is related to the emissivity changes and local temperature increase caused by surface degradation. Meanwhile, the micro-structured sample did not show any change of its temperature response from the 10th to the 100 000th pulse.

微结构化钨是解决钨作为高热通量（HHF）等离子饰面材料（PFM）的主要问题之一的新方法，这是它的脆性以及在脉冲，类似ELM的热载荷下易形成裂纹的倾向et al。，2015; Wirtzet et al。，2015 [2,3]）。当功率密度在100 MW / m ²和1 GW / m ^2之间时，取决于脉冲数和PFM基本温度，会发生渐进的热疲劳引起的损伤，例如粗糙化，随后的破裂甚至熔化。对于将钨用作HHF-PFM而言，这代表了一个严重的问题。在未来的托卡马克（如ITER）中，预计在使用寿命期间会出现约10 ^8个ELM。

已经尝试了多种方法来克服该脆性问题，例如将钨与其他元素合金化（Linsmeier等人，2017 [4]）或由于添加纤维而引入假延展性，从而形成复合材料（Reiser等人，2017 [ 5]）。与这些方法中的任何一种相比，微结构钨在ELM预期的损伤方面均显示出显着改善。在PSI-2设施中进行了对大量参比钨和微结构钨的研究（Kreter等，2015 [8]）。施加连续负载，将稳态氘等离子体（5.1×10 ²⁵  D + m ^-2，51 eV，240°C，150分钟）负载与激光脉冲（最多10 ⁵个0.5 GW / m ^2的脉冲）相结合，3.6 mm的光斑直径，20 J，1 ms脉冲持续时间，最高25 Hz脉冲频率）。与参考块状钨相反，施加的负载条件均未对微结构钨造成任何明显的损坏。对于参考样品，在激光暴露结束时，用快速高温计测量的负载区域内的最大表面温度增加了约800°C。这与表面退化引起的发射率变化和局部温度升高有关。同时，从第10个脉冲到第100000个脉冲，微结构化样品的温度响应没有任何变化。