Động học sớm của bóng khí sinh ra trong quá trình phá hủy chất rắn trong môi trường nước

Nội dung text: Động học sớm của bóng khí sinh ra trong quá trình phá hủy chất rắn trong môi trường nước

1. Nguyen Thi Phuong Thao / Tạp chí Khoa học và Công nghệ Đại học Duy Tân 02(45) (2021) 39-41 39 02(45) (2021) 39-41 Early dynamics of laser-induced cavitation bubble induced in laser ablation of solid in water Động học sớm của bóng khí sinh ra trong quá trình phá hủy chất rắn trong môi trường nước Nguyen Thi Phuong Thaoa,b* Nguyễn Thị Phương Thảoa,b* aInstitute of Research and Development, Duy Tan University, Da Nang, 550000, Vietnam aViện Nghiên cứu và Phát triển Công nghệ Cao, Trường Đại học Duy Tân, Đà Nẵng, 550000, Việt Nam bFaculty of Natural Sciences, Duy Tan University, Da Nang, 550000, Vietnam bKhoa khoa học Tự nhiên, Trường Đại học Duy Tân, Đà Nẵng, 550000, Việt Nam (Ngày nhận bài: 11/09/2020, ngày phản biện xong: 02/10/2020, ngày chấp nhận đăng: 20/10/2020) Abstract In this study, we observed the evolution of a cavitation bubble induced by focusing a nanosecond-pulsed laser on an epoxy-resin surface using a photoelasticity imaging technique. The radius-time curve of the bubble within the first 1000 ns was reported for different pulse energies from 20 to 60 mJ. The result showed that the bubble expanded faster at higher laser energy but followed a simple rule R~at0.3 Keywords: Photoelastic images; laser-induced cavitation bubble; expansion rate. Tóm tắt Trong nghiên cứu này, chúng tôi quan sát sự phát triển của một bóng khi sinh ra khi hội tụ một xung laser nano giây lên trên một bề mặt epoxyresin bằng phương pháp chụp ảnh quang đàn hồi. Đường cong bán kính-thời gian của bóng khí trong khoảng 1000 nano giây đầu tiên đươc ghi lại ứng với năng lượng xung laser từ 20 đến 60 mJ. Kết quả cho thấy bóng khí giãn nở nhanh hơn khi năng lượng xung cao hơn, tuy nhiên tuân theo một quy luật đơn giản R~at0.3. Từ khóa: Hình ảnh quang đàn hồi; bóng khí sinh ra bởi tia laser; tốc độ giãn nở. 1. Introduction target [1]. Even though the evolution of laser- When focusing a pulsed laser onto a solid induced cavitation bubbles in liquids has been target immersed in a liquid, first, the laser widely reported in the literature, some critical ablates the material and forms a high-pressure mechanisms are still poorly understood. Thus, plasma. This high pressure, high-temperature the laser-induced cavitation bubble is still a plasma imitates a cavitation bubble that subject of continuous interest. expands and collapses many times on the solid * Corresponding Author: Nguyen Thi Phuong Thao; Institute of Research and Development, Duy Tan University, Da Nang, 550000, Vietnam; Faculty of Natural Sciences, Duy Tan University, Da Nang, 550000, Vietnam. Email: thaonguyen@duytan.edu.vn
2. 40 Nguyen Thi Phuong Thao / Tạp chí Khoa học và Công nghệ Đại học Duy Tân 02(45) (2021) 39-41 Conventionally, the dynamics of laser-induced block in pure water. The laser pulse energy was cavitation bubble is studied at late stages, when regulated from 20 to 60 mJ. The epoxy-resin the bubble reaches its maximum radius and blocks have a dimension of 5.8x22x28 mm3. collapses [2]–[4]. The observation of the early The evolution of the cavitation bubble was dynamics is rarely reported. In this work, we aim observed by using a custom-designed to advance the understanding of the early photoelasticity imaging technique. The imaging dynamics of laser-induced cavitation bubble by system is similar to our previous report [5] and providing observation of the evolution of the only a brief description is provided here. We bubble within the first 1000 ns after irradiation. used a pump-and-probe system with a The radius-time curve was also studied with the polariscope added to provide a photoelasticity pulse energy regulated from 20 to 60 mJ. With image. An ICCD camera was used together with the high-resolution photoelasticity imaging a set of Neutral-Density filters as a recording technique, we provide a sufficient description of device. The camera gate width was 40 ns. The the early dynamics of the laser-induced cavitation delay time was defined as the interval between bubble in the liquid-ablation phase. the pump and probe pulses and was adjusted by 2. Material and methods a delay generator. The evolution of the bubble was observed in 1000 ns after irradiation with A hemispherical cavitation bubble was the time-resolution of 100 ns. induced by mg. focusing a laser beam (1064 nm, 13 ns in FWHM) on to an epoxy-resin 3. Results and discussions Figure 1: Evolution of laser-induced cavitation bubble at early stage. Pulse energy: 20 mJ. Laser came from above. Figure 2: Change of bubble radius with time, observed at different pulse energies. The dashed lines are fitting curves by the power rule
3. Nguyen Thi Phuong Thao / Tạp chí Khoa học và Công nghệ Đại học Duy Tân 02(45) (2021) 39-41 41 Figure 1 presents the evolution of a These simple expressions will be useful for cavitation bubble within the first 1000 ns after further analysis of the bubble pressure irradiation. The pulse energy was 20 mJ. The distribution during the early stages using black horizontal line in the middle of the image Rayleigh-Plesset equation, which is the topic of is the target surface. The upper half is the water our research in the future. and the lower half is solid. At 100 ns delay 4. Conclusions time, the shock-wave front and the cavitation By using a custom-designed photoelasticity bubble can be distinguished. The shockwave imaging technique, we have provided a direct front appears in the liquid as the sharp black observation of the early dynamics of a laser- curve. The cavitation bubble appears in the induced cavitation bubble in liquid ablation image as the tiny black hemispherical, located phase. The result shows that the bubble expand inside the shock wavefront. The shock wave faster with higher pulse energy. The early traveled into the water at supersonic velocity, change of bubble radius with time can be well rapidly outdistancing the cavitation bubble. The fitted by a simple relationship, which is useful bubble expanded with time, at a much slower for further investigation of the pressure rate in comparison to the shock wave. In the distribution within the bubble. solid phase, a stress wave can be observed as semi-circles rapidly expanding into the target. References The image of the stress wave in the solid phase [1] R. Tanabe, T. T. P. Nguyen, T. Sugiura, and Y. Ito, includes a pressure wavefront followed by “Bubble dynamics in metal nanoparticle formation by laser ablation in liquid studied through high- photoelastic fringes. The dynamics of stress speed laser stroboscopic videography,” Appl. Surf. waves have been described in detail in our Sci., vol. 351, pp. 327–331, Oct. 2015. previous work [6]. [2] J. Lam, J. Lombard, C. Dujardin, G. Ledoux, S. Merabia, and D. Amans, “Dynamical study of The bubble radius was measured and plotted bubble expansion following laser ablation in as a function of time. Figure 2 summarizes the liquids,” Appl. Phys. Lett., vol. 108, no. 7, p. 074104, Feb. 2016. radii variation of the cavitation in water from [3] T. Tsuji, Y. Okazaki, Y. Tsuboi, and M. Tsuji, 100 to 1000 ns after irradiation for different “Nanosecond time-resolved observations of laser pulse energy from 20 to 60 mJ. From the figure, ablation of silver in water,” Japanese J. Appl. Physics, Part 1 Regul. Pap. Short Notes Rev. Pap., we found that the bubble expanded faster with vol. 46, no. 4 A, pp. 1533–1535, 2007. increasing pulse energy. We also found that the [4] K. Sasaki and N. Takada, “Liquid-phase laser early changes of bubble radius R with time t ablation,” Pure Appl. Chem., vol. 82, no. 6, pp. 1317–1327, 2010. can be well fitted by a simple relationship: [5] T. T. P. Nguyen, R. Tanabe, and Y. Ito, “Effects of an absorptive coating on the dynamics of (1) underwater laser-induced shock process,” Appl. Where is a constant chiefly dependent on the Phys. A, vol. 116, no. 3, pp. 1109–1117, Dec. 2013. [6] T. T. P. Nguyen, R. Tanabe, and Y. Ito, “Laser- pulse energy. This simple expression allows to induced shock process in under-liquid regime estimate the bubble expansion velocity as: studied by time-resolved photoelasticity imaging technique,” Appl. Phys. Lett., vol. 102, no. 12, p. (2) 124103, 2013.