Multifractal analysis of high-temperature plasma irradiated tungsten surfaces

Martsepp, Merike; Laas, T.; Laas, Katrin; Priimets, J.; Mikli, Valdek; Antonov, Maksim

doi:10.1088/2051-672x/ac1dc3

Cited by 5 publications

(4 citation statements)

References 28 publications

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“…With respect to monofractals and non-fractals, the graph D(q) vs q has a small variance, while for multifractals, D(q) usually decreases with a decrease in q, which often occurs sigmoidally before the point q = 0. Details of the application of the MF theory and the box-counting method can be found in the articles of previous studies [36,37].…”

Section: Experimental Setup and Methodsmentioning

confidence: 99%

“…from plasma-irradiated surfaces. By using the concept of multifractals, in addition to the usual descriptive methods [20], quantitative values and graphs characterizing the surface damage structures as a whole can be studied [22,[36][37][38]. The box-counting technique can be applied to surfaces of a defected material as well as to the same surfaces of non-defects (without a defected area).…”

Section: Introductionmentioning

confidence: 99%

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Comparison of multifractal parameters of surface defects and non-defects

Martsepp¹,

Laas²,

Tõkke³

et al. 2023

PEAS

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In this study, three different materials (pure tungsten and two tungsten alloys with Fe and Ni dopants), which have been irradiated with a high-temperature deuterium plasma of 20, 25 and 100 plasma shots, are considered. The multifractal characteristics obtained from SEM images are then compared for the same specimens by analysing the distribution of defects and non-defects (nondamaged areas). A valid tendency was found that the brighter the original input image, the more accurate the results obtained when examining a non-damaged surface using multifractal characteristics.

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Section: Experimental Setup and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of multifractal parameters of surface defects and non-defects

Martsepp¹,

Laas²,

Tõkke³

et al. 2023

PEAS

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show abstract

“…Butenko et al [14] carried out a multifractal analysis on nitinol glass annealed at different temperatures, counted its surface characteristics, and verified the possibility of detecting system phase transition in crystalline form. Martsepp et al [15] irradiated pure tungsten samples with high-temperature deuterium plasma at different times and compared the multifractal spectrum of the sample surface with the Fourier spectrum. The multifractal spectrum of the surface can determine the time dependence of surface damage.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Ceramic Thermal Shock Cracks Based on the Multifractal Spectrum

et al. 2022

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Ceramics are commonly used as high-temperature structural materials which are easy to fracture because of the propagation of thermal shock cracks. Characterizing and controlling crack propagation are significant for the improvement of the thermal shock resistance of ceramics. However, observing crack morphology, based on macro and SEM images, costs much time and potentially includes subjective factors. In addition, complex cracks cannot be counted and will be simplified or omitted. Fractals are suitable to describe complex and inhomogeneous structures, and the multifractal spectrum describes this complexity and heterogeneity in more detail. This paper proposes a crack characterization method based on the multifractal spectrum. After thermal shocks, the multifractal spectrum of alumina ceramics was obtained, and the crack fractal features were extracted. Then, a deep learning method was employed to extract features and automatically classify ceramic crack materials with different strengths, with a recognition accuracy of 87.5%.

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“…For instance, different methods of fractal analysis have been successfully used to decode the surface finishing in engineering ceramics and sapphire single crystals [17,20]. In addition, various studies revealed that the 3D surface microtexture can be described using stereometric [21][22][23], and fractal/multifractal analyses [24][25][26][27][28] with a minimal set of surface parameters.…”

Section: Introductionmentioning

confidence: 99%

Multifractal analysis of ultrasonically machined surfaces of cylindrical quartz crystals: the effect of the abrasive grits

Ţălu¹,

Guzzo²,

Astinchap³

et al. 2021

Surf. Topogr.: Metrol. Prop.

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Since synthetic quartz is essential to produce 3-D resonators for numerous applications in precision electronics, in this work the surface topography of cylindrical quartz bars is investigated using the multifractal technique. The cylindrical bars were manufactured with ultrasonic machining using with five SiC grits ranging from 6 to 50 µm. The machined surfaces were initially characterized by contact profilometry and scanning electron microscopy (SEM). The multifractality of the machined surfaces was scrutinized using a box-counting method applied to the images obtained with 500X magnification. The multifractal spectrum indicated that the fractal dimension f(α) and the width of the fractal spectrum Δα are dependent on the grit size, but this dependence is not monotonic. The lowest (negative) value for Δf(α) was found for 25 µm grits indicating that for these grits the lower frequency events (grooves with tens µm width occurring along the USM direction) controls the surface topography much more than high frequency events related to brittle microcracking. The abrasive wear due to the continuous slurry recycling in lateral tool-workpiece interfaces contributed to smooth the groove texture as well as the sharpness of microscopic indentations, which remained observed on the surfaces machined with 50 µm grits. The opposite paths observed for the arithmetical mean deviation of the measured profile (Ra) and Δf(α) parameters with the cutting rate measured for each grit size were valuable to differentiate flat-rough and unlevelled-rough topographies in quartz bars.

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Multifractal analysis of high-temperature plasma irradiated tungsten surfaces

Cited by 5 publications

References 28 publications

Comparison of multifractal parameters of surface defects and non-defects

Comparison of multifractal parameters of surface defects and non-defects

Characterization of Ceramic Thermal Shock Cracks Based on the Multifractal Spectrum

Multifractal analysis of ultrasonically machined surfaces of cylindrical quartz crystals: the effect of the abrasive grits

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