Resonance excitation of surface capillary waves to enhance material removal for laser material processing

Ly, Sonny; Guss, Gabe; Rubenchik, Alexander M.; Keller, Wesley J.; Shen, Nan; Negres, Raluca A.; Bude, J.

doi:10.1038/s41598-019-44577-6

Cited by 23 publications

(15 citation statements)

References 27 publications

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“…Ablation of materials with high thermal conductivity (e.g., aluminum (Al) ~ 236 Wm -1 K -1 , copper ~ 401 Wm -1 K -1 , gold ~ 318 Wm -1 K -1 , and silver ~ 428 Wm -1 K -1 at 273 K), requires much higher CW laser power because the absorbed heat is diffused into the bulk before the surface temperature reaches the critical temperature for material ejection. Necessarily, a significant amount of re-solidified materials is formed 8 near the irradiated spot due to a long heat diffusion length (~300 μm with an Al thermal diffusivity 95 ×10 -6 m 2 /s for 1 ms), which is undesirable for precise control of ablated features.…”

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confidence: 99%

“…Temporal modulation of the CW laser energy in the kHz repetition rate regime (quasi-CW) has been proposed to augment the amount of material removals and the quality of ablated features via excitation of thermo-capillary driven oscillating surface waves. 8 Due to the short duration of the modulated pulse compared to the lifetime of the ablation process, multiple pulses interact with the molten material generated by the preceding pulses, to enhance liquid material removal.…”

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confidence: 99%

“…Such perturbations are often observed in laser induced molten surfaces due to hydrodynamic instabilities. 8,9 Fig. 3 (b) shows the Distance-Time (R-t) plot of the column structures and ejected NPs calculated from data shown in Fig.…”

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confidence: 99%

“…The dimensionless Weber number (𝑊𝑒 = 𝜌𝑟𝑉 2 𝜎 ) 15,16 , which quantitatively describes the competition between kinetic energy and surface tension, can help elucidate whether the origin of particles 'B' can be attributed to breakup of each liquid branch (or jet) of the hydrodynamically perturbed surface. 𝜌 is the density of liquid Al (2378 kg/m 3 ) 17 , 𝑉 is the propagation speed, 𝑟 is the 6.5 m radius of the jet, and 𝜎 is the surface tension of liquid Al (0.9 N/m) 8 . The corresponding 𝑊𝑒 numbers of particles 'B' are 7, 21, and 31, respectively (Fig.…”

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confidence: 99%

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Spatio-temporal ablation dynamics and plasma chemistry of aluminum induced by temporally modulated ytterbium fiber laser

Park

Balkey

Mao

et al. 2021

Applied Physics Letters

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In this work, we studied single-pulse ablation dynamics of temporally modulated continuous wave laser-material interaction with Al using in situ multimodal time-resolved diagnostics, that describe in detail the associated physical and chemical processes. Timeresolved scattering, emission imaging, and optical emission spectroscopy unveiled a sequence of events spread out across three distinct phases: (i) early phase ablation process, associated with particle generation and liquid Al columns formation (< 20 μs), (ii) secondary detonation when sufficient ejected material is accumulated over the surface (20-50 μs), and (iii) molten liquid Al pool oscillation on the surface, followed by large droplet ejection from the liquid pool (100-500 μs). Atomic Al and AlO were observed with optical emission spectroscopy at different ratios during the entire lifetime of the event, verifying the formation of oxidized Al vapor upon its interaction with air. Morphological and compositional characterization confirmed surface oxidation and material resolidification in the form of protrusions produced during the irradiation process. This work provides insights into the complex physical and chemical mechanisms of single-pulse ablation in the sub-millisecond laser pulse regime, which are critically important for parameter optimization in a variety of laser processing, microfabrication, and deposition applications.

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confidence: 99%

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confidence: 99%

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Spatio-temporal ablation dynamics and plasma chemistry of aluminum induced by temporally modulated ytterbium fiber laser

Park

Balkey

Mao

et al. 2021

Applied Physics Letters

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“…Другой механизм ГП связан с ТК-механизмом удаления расплавленного металла из-за температурной зависимости поверхностного натяжения при неоднородном лазерном нагреве, позволяющем контролировать образование канала [7,8]. Выполненные в работе [9] тщательные численные расчеты формирования кратера с учетом относительного влияния обоих механизмов подтверждают преобладание ТК-механизма при температуре кипения T B , в то время как доминирование абляционного механизма требует нагрева значительно выше T B . В режиме ГП (или при поверхностной температуре T B [3]) интенсивность испарения оказывается недостаточной для механического поддержания канала давлением паров, а соответствующие этому режиму экспериментальные данные воспроизводимы при оценочных расчетах с использованием ТК-механизма [10][11][12].…”

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Начальная Стадия Эволюции Гидродинамических Параметров При Глубоком Проплавлении Металлов Мощным Лазерным Излучением

Сейдгазов¹,

Мирзаде²

2022

Письма В Журнал Технической Физики

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Surface tension of steel at high temperatures

Volpp

2023

SN Appl. Sci.

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Surface tension is a material property that is needed to describe fluid behaviour, which impacts industrial processes, in which molten material is created, such as thermal cutting, welding and Additive Manufacturing. In particular when using metals, the material properties at high temperatures are often not known. This is partly because of limited possibilities to measure those properties, limitations of temperature measurement methods and a lack of theoretical models that describe the circumstances at such high temperatures sufficiently. When using beam heat sources, such as a laser beam, temperatures far above the melting temperature are reached. Therefore, it is mandatory to know the material properties at such high temperatures in order to describe the material behaviour in models and gain understanding of the occurring effects. Therefore, in this work, an experimental surface wave evaluation method is suggested in combination with thermal measurements in order to derive surface tension values of steel at higher temperatures than reported in literature. The evaluation of gravity-capillary waves in high-speed video recordings shows a steeper decrease of surface tension values than the extrapolation of literature values would predict, while the surface tension values seem not to decrease further above boiling temperature. Using a simplified molecular dynamic model based on pair correlation, a similar tendency of surface values was observed, which indicates that the surface tension is an effect requiring at least two atomic layers. The observed and calculated decreasing trend of the surface tension indicates an exponential relation between surface tension and temperature.

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Resonance excitation of surface capillary waves to enhance material removal for laser material processing

Cited by 23 publications

References 27 publications

Spatio-temporal ablation dynamics and plasma chemistry of aluminum induced by temporally modulated ytterbium fiber laser

Spatio-temporal ablation dynamics and plasma chemistry of aluminum induced by temporally modulated ytterbium fiber laser

Начальная Стадия Эволюции Гидродинамических Параметров При Глубоком Проплавлении Металлов Мощным Лазерным Излучением

Surface tension of steel at high temperatures

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