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Ultrafast dynamics control on ablation of Cu using shaped femtosecond pulse trains
Deng Jiannan,Qi Hongxia,Liu Xinyi,Li Xiaoyi,Tong Qiunan,Lian Zhenzhong,Li Juan,Bo Jinqiu,Fei Dehou,Chen Zhou,Hu Zhan 한국물리학회 2021 Current Applied Physics Vol.26 No.-
The ablation processes of Cu film are investigated using temporal shaped femtosecond pulse trains. The depth is modulated by changing the number and interval of the sub-pulses. The underlying ultrafast dynamic processes are discussed based on plasma shielding and electron multiple heating mechanisms. When the sub-pulse interval is less than 0.4 ps electron multiple heating is the dominant mechanism, while the plasma shielding dominates the subsequent ablation processes when the sub-pulse interval is larger than 0.4 ps. The curve of depth obtained by three pulse trains shows more significant oscillation as the function of sub-pulse interval under the lowfluence. We propose that the oscillation of depth is due to the coherent phonon oscillation excited by the pulse train. The study provides a basis for giving insight into the ultrafast dynamics for improving micromachining and nano-fabrications using shaped femtosecond pulse trains.
Jianxin He,Jiannan Lu,Liang Liu,Wu Yang,Haihua Yang,Pengpeng Chen,Xinyu Ding 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.8
The primary contribution of this paper is to identify the optimal cross-section size and span diameter for large-grained hydraulic asphalt concrete materials in trabecular bending tests. First, three-point bending tests were conducted on asphalt concrete with maximum aggregate sizes of 19 mm (Dmax = 19 mm), 26.5 mm, and 31.5 mm, using six distinct cross-section sizes and span diameters. These experiments served to analyze the influence of varying cross-section sizes and span diameters on the mechanical properties of the materials. Secondly, the Image-Pro Plus (IPP) software was utilized to analyze and confirm the cross-sectional areas of the chosen samples. Then, by considering the optimal cross-section size and span diameter, the impact of temperature on the flexural characteristics of asphalt concrete with a maximum aggregate size of 31.5 mm was explored. This investigation enabled the proposal of a temperature cut-off interval governing the transformation of large-grained asphalt concrete from brittle to plastic damage. The validity of the experimental data was substantiated through image analysis, providing a benchmark for the testing methodology of the flexural performance of large-grained hydraulic asphalt concrete aggregate.