Morena Alberto, Peroni Lorenzo
Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129 Turin, Italy.
Materials (Basel). 2021 Nov 22;14(22):7079. doi: 10.3390/ma14227079.
The development of particle accelerators with ever increasing energies is raising the standards of the structures which could interact with the particle beams. These structures could be subjected to strong shockwaves in accidental scenarios. In order to test materials in such conditions, one of the most promising techniques is the impact with high-power lasers. In view of the setting up of future experimental campaigns within the Petawatt High-Energy Laser for Heavy Ion Experiments (PHELIX), the present work aims at the development of a numerical approach for the simulation of graphite impacted by laser beams. In particular, the focus is on the spallation damage caused by shockwave reflection: a sufficiently intense laser beam could ablate the matter until plasma conditions, hence producing a shockwave which could travel inside the material and reach a free surface. A numerical model to properly describe the spall fragmentation of graphite has been calibrated on the basis of literature-available experimental data. The numerical approach is a 'two-step' procedure: the first step is the definition of the laser-matter interaction and the second one concerns the description of the shockwave evolution into matter. The simulations satisfactorily reproduce the dynamic response of graphite impacted by two different laser sources with various intensities, despite the difficulties of characterising a phenomenon which is extremely fast and chaotic.
随着能量不断增加的粒子加速器的发展，与粒子束相互作用的结构标准也在提高。在意外情况下，这些结构可能会受到强烈的冲击波。为了在这种条件下测试材料，最有前景的技术之一是用高功率激光进行冲击。鉴于在用于重离子实验的拍瓦高能激光装置（PHELIX）内开展未来的实验活动，目前的工作旨在开发一种数值方法来模拟激光束冲击下的石墨。特别关注的是冲击波反射引起的层裂损伤：足够强的激光束可以烧蚀物质直至达到等离子体状态，从而产生一个可以在材料内部传播并到达自由表面的冲击波。基于文献中可用的实验数据，已经校准了一个能够恰当地描述石墨层裂破碎的数值模型。该数值方法是一个“两步”过程：第一步是定义激光与物质的相互作用，第二步涉及描述冲击波在物质中的演化。尽管表征这种极其快速且混沌的现象存在困难，但模拟结果令人满意地再现了石墨在两种不同强度激光源冲击下的动态响应。
