聚变装置纳米钨灰尘与氢/氦/钨粒子及钨表面相互作用的数值模拟研究

Nuclear fusion is very significant for solving energy problems. However, dust is now becoming one of the critical issues which affect the operation and life of fusion devices. The project will employ molecular dynamics simulations to study interactions between nanoscale tungsten dust generated in fusion devices with energetic hydrogen/helium/tungsten atoms and plasma-facing materials. The specific contents include: 1) a model that simulates the interaction between freestanding tungsten dust and hydrogen/helium/tungsten atoms is to be established. Based on this model, the thermodynamic state of the tungsten dust and the possible products caused by hydrogen/helium/tungsten bombardments will be studied; 2) the bombardments of tungsten dusts on tungsten surfaces will be studied. Two types of tungsten surfaces here are to be considered: perfect surfaces and surfaces containing defects, such as helium bubble, dislocations. The damage on tungsten surfaces, the evolution of preset defects on tungsten surfaces and the structures of the surfaces caused by tungsten dust bombardments will be studied; 3) the bombardments of hydrogen/helium/tungsten atoms on nanoscale tungsten fuzzes containing hydrogen/helium bubbles will be studied. The production of secondary dust and release of helium atoms will be studied. The project aims to reveal the interaction mechanism between freestanding tungsten dusts and hydrogen/helium/tungsten atoms and the interaction mechanism between tungsten dusts and tungsten surfaces, clarify the change of fibrous tungsten fuzz after helium bombardments. The results could be important for understanding the behavior of tungsten dust and the formation of fibrous dust in fusion devices.

核聚变能的实现对能源问题解决尤其重要，然而聚变装置中产生的灰尘成为影响聚变装置运行和寿命的关键问题之一。本项目拟采用分子动力学方法，以托卡马克聚变装置中的纳米钨灰尘为对象展开模拟研究，具体包括：研究纳米钨灰尘与氢/氦/钨粒子的相互作用，分析钨灰尘的状态变化及潜在产物；研究纳米钨灰尘与真空室面向等离子体材料钨的相互作用，考察钨灰尘在钨表面上的行为、钨表面缺陷的演化和二次灰尘的产生；在钨表面构建纤维状纯钨丝和含有氢/氦泡等缺陷的钨丝，分析氢/氦/钨粒子轰击对缺陷和钨丝产生的影响，钨丝是否会断裂成为纤维状灰尘。本项目旨在揭示钨灰尘与氢/氦/钨粒子及钨表面的相互作用机制与规律，阐明钨材料表面出现的纤维状结构在氢/氦/钨粒子轰击后的变化，为聚变装置中钨灰尘的行为和纤维状灰尘的出现提供理论依据。

核聚变能的实现对能源问题解决尤为重要，然而聚变装置中产生的钨灰尘成为影响聚变装置运行和寿命的关键问题之一。本项目采用分子动力学方法，以托卡马克聚变装置中的纳米钨灰尘为对象展开了一系列模拟研究，具体包括：（1）纳米钨颗粒的熔点研究及解离行为研究；（2）钨颗粒与氦/钨粒子的相互作用研究；（3）纳米钨灰尘与钨表面的相互作用研究；（4）纳米钨颗粒融合行为的研究。确定了4 nm-12 nm直径范围的钨颗粒的熔点，确定了钨颗粒尺寸与熔点之间的数值关系；钨颗粒的解离行为服从Arrhenius关系；氦/钨粒子与钨颗粒碰撞后，入射粒子和钨颗粒的行为与入射粒子的能量和钨颗粒的大小有关；低能纳米钨颗粒不会对钨表面产生明显损伤；纳米钨颗粒的大小、温度和颗粒之间的相对速度对颗粒间的融合均有不同程度的影响。通过本项目的研究工作，对聚变装置中纳米钨灰尘各种行为的进一步研究、钨颗粒的制备和应用有一定的指导意义。