Multifractal analysis of high-temperature plasma irradiated tungsten surfaces(vol 9, 035030, 2021)

In this research, the irregular surface structure of 15 pure tungsten specimens that are irradiated respectively with 20, 40, 60, 80, and 100 shots of high-temperature deuterium plasma are under observation. The box-counting method is used to evaluate the scanning electron microscope (SEM) images taken from different locations within the same specimen. Obtained multifractal characteristics are then compared with the Fourier spectrum of stochastic relief. As a result, it is possible to determine the time dependence of surface damage with the box-counting method, but additional tests should be performed with the Fourier method to confirm this regularity. Besides, it has been studied further whether and how the fractal characteristics change with different magnifications within the same specimen. It was found that when selecting the appropriate magnification for SEM, X500 for a given specimen, the multifractal analysis of the arbitrarily selected image of surface damage well represents the average situation on the specimen.