Impact of simultaneous W deposition and He plasma exposure on mechanical properties of tungsten

钨是未来聚变反应堆（如STEP和DEMO）等离子体面组件的候选材料，也是ITER转流器的选择材料。氦等离子体与钨相互作用的影响是一个丰富的研究领域，已经开展了大量的工作，各种聚变相关的温度，影响和离子能量。He的影响在不同的温度下是不同的，在低于873 K时形成较小的纳米气泡，在高于这个温度时形成较大的纳米气泡，在900-2000 K之间形成一种被称为模糊的纳米结构，在高于2000 K时形成较大的空洞。他与钨的相互作用也被证明对钨的再结晶性能有影响，这与辐照温度有关，因此与气泡形成的大小有关。这是令人感兴趣的，因为再结晶会影响钨的机械性能，并可能增加在高温下操作时微裂纹的可能性。最近的研究表明，在氦等离子体辐照过程中，钨粒子的存在导致了模糊的增强形成。这可能是未来的聚变反应堆的兴趣，那里将有一些溅射钨存在于等离子体中。值得关注的是，在低于绒毛形成所需温度的温度下，外部源和He照射下沉积的钨在纳米泡形成过程中的同时影响，以及这是否会影响先前在钨He暴露后观察到的再结晶延迟。为了研究这一过程，He等离子体暴露与同时钨沉积将与澳大利亚国立大学的Cormac Corr教授合作进行，研究与英国原子能管理局“STEP”（用于能源生产的球形托卡马克）计划相关的钨材料。将对这些样品进行退火研究。接下来，我们将利用哈维尔国家实验室的衍射技术来测量暴露样品中的He气泡大小，这将通过曼彻斯特的显微镜技术与再结晶相关联。这对于了解未来钨元件的工程性能及其适用性具有重要意义。该项目的目标将是：在一系列温度和影响下，在STEP相关的钨材料上同时进行He照射和钨沉积；使用成像和小角度散射技术表征He气泡尺寸；将气泡形成与对再结晶/其他机械性能的影响联系起来

Tungsten is a candidate material for plasma facing components in future fusion reactors such as STEP and DEMO and is the chosen material for the diverter in ITER. The influence of He plasma interactions with tungsten is a fertile area of study with extensive work having been carried out a variety of fusion relevant temperature, fluences and ion energies. The influence of He has been shown to vary at different temperatures with smaller nanobubbles formed at less than 873 K, larger ones above this temperature and a nanostructure knows as fuzz at temperatures between 900-2000 K, with larger voids formed at temperatures above 2000 K. He interactions with tungsten has also been shown to have an influence on the recrystallization properties of tungsten which is related to the temperature of irradiation and consequently the size of bubble formation. This is of interest as recrystallization influences the mechanical performance of tungsten and may increase the likelihood of micro-cracking during operations at high temperatures. Recent work has shown that the presence of tungsten particles during He plasma irradiation has resulted in the enhanced formation of fuzz. This could be of interest for future fusion reactors where there will be some sputtered tungsten present in the plasma. It is of interest to see what the simultaneous impact of deposition of tungsten from an external source with He irradiation at lower temperatures than those required for fuzz formation will be in the nanobubble formation regime and additionally whether this influences the retardation of recrystallization that has been observed following He exposure of tungsten previously. In order to investigate this process, He plasma exposures with simultaneous tungsten deposition will be carried out in collaboration with Prof. Cormac Corr at ANU on tungsten material relevant to the UK Atomic Atomic Energy Authority 'STEP' (Spherical Tokamak for Energy Production) programme. Annealing studies will be carried out on these samples. Following this time will be applied for to use diffraction techniques using the national lab facilities at Harwell in order to measure He bubble size in the exposed samples, which will be correlated to recrystallization via microscopy techniques at Manchester. This is of vital performance in order to understand the engineering performance of future tungsten components and their suitability.The objectives of the project will be to:Carry out simultaneous He irradiation and tungsten deposition on STEP relevant tungsten material at a range of temperatures and fluencesCharacterise the He bubble sizes using imaging and small-angle scattering techniquesCorrelate the bubble formation with impact on recrystallization/other mechanical properties