Mechanisms of graphite ablation by sub-millisecond ytterbium fiber laser pulses

Graphite is a key material in a variety of cross-cutting applications in energy conversion, energy storage, and nuclear energy. Recently, temporally modulated continuous wave lasers have been shown to produce well-defined ablation features in graphite at relatively high processing speeds. In this wo...

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Bibliographic Details
Published in:Applied physics letters 2022-08, Vol.121 (9)
Main Authors: Park, Minok, Balkey, Matthew M., Mao, Xianglei, Jonsson, Jacob C., Grigoropoulos, Costas P., Zorba, Vassilia
Format: Article
Language:English
Subjects:
Ablation
Applied physics
Continuous wave lasers
Cross cutting
Energy conversion
Energy storage
ENGINEERING
Fiber lasers
Graphite
Laser ablation
Laser machining
Laser processing
Lasers
Nuclear energy
Nuclear reactor components
Nuclear reactors
Optical emission spectroscopy
Optimization
Ytterbium
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Summary:Graphite is a key material in a variety of cross-cutting applications in energy conversion, energy storage, and nuclear energy. Recently, temporally modulated continuous wave lasers have been shown to produce well-defined ablation features in graphite at relatively high processing speeds. In this work, we analyze in detail the laser ablation dynamics of single-pulse ablation in the sub-millisecond time regime to elucidate the origins of the resulting well-defined ablation craters using a combination of time-resolved emission imaging, diffuse reflection/scattering imaging, and optical emission spectroscopy. These multimodal in situ diagnostics revealed three main contributors to achieve well-defined ablation features: (1) rapid ejection of particles with ∼100 m/s speed, (2) ablation of the graphite in the gaseous form, and (3) absence of bulk liquid motion, which is typically observed in laser processing of metals. Plasma plume formation was sustained throughout the duration of the laser pulse (500 μs). This work provides insights into the complex physical and chemical mechanisms of sub-millisecond laser–matter interactions, which are critical for parameter space optimization and tailoring of laser machining and drilling processes.
ISSN:0003-6951
1077-3118
DOI:10.1063/5.0109618