Shock front detachment during pulsed laser ablation of graphite

Calver, Timothy I.; Shattan, Michael B.; Perram, Glen P.

doi:10.1007/s00339-021-05146-9

Cited by 3 publications

(1 citation statement)

References 60 publications

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“…213,214 Generally, larger shockwave propagation distances and velocities are routinely observed for atmospheric conditions consisting of lower gas pressures and densities. 54,200,[215][216][217] It has also been shown that shockwave velocities increase for decreasing irradiation wavelengths used during LA. 218 Furthermore, higher laser fluences produce stronger shockwaves with larger propagation velocities.…”

Section: Laser Ablation Plasma Chemistrymentioning

confidence: 99%

Laser Ablation Plasmas and Spectroscopy for Nuclear Applications

Kwapis,

Borrero,

Latty

et al. 2023

Appl Spectrosc

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The development of measurement methodologies to detect and monitor nuclear-relevant materials remains a consistent and significant interest across the nuclear energy, nonproliferation, safeguards, and forensics communities. Optical spectroscopy of laser-produced plasmas is becoming an increasingly popular diagnostic technique to measure radiological and nuclear materials in the field without sample preparation, where current capabilities encompass the standoff, isotopically resolved and phase-identifiable (e.g., UO and UO[Formula: see text]) detection of elements across the periodic table. These methods rely on the process of laser ablation (LA), where a high-powered pulsed laser is used to excite a sample (solid, liquid, or gas) into a luminous microplasma that rapidly undergoes de-excitation through the emission of electromagnetic radiation, which serves as a spectroscopic fingerprint for that sample. This review focuses on LA plasmas and spectroscopy for nuclear applications, covering topics from the wide-area environmental sampling and atmospheric sensing of radionuclides to recent implementations of multivariate machine learning methods that work to enable the real-time analysis of spectrochemical measurements with an emphasis on fundamental research and development activities over the past two decades. Background on the physical breakdown mechanisms and interactions of matter with nanosecond and ultrafast laser pulses that lead to the generation of laser-produced microplasmas is provided, followed by a description of the transient spatiotemporal plasma conditions that control the behavior of spectroscopic signatures recorded by analytical methods in atomic and molecular spectroscopy. High-temperature chemical and thermodynamic processes governing reactive LA plasmas are also examined alongside investigations into the condensation pathways of the plasma, which are believed to serve as chemical surrogates for fallout particles formed in nuclear fireballs. Laser-supported absorption waves and laser-induced shockwaves that accompany LA plasmas are also discussed, which could provide insights into atmospheric ionization phenomena from strong shocks following nuclear detonations. Furthermore, the standoff detection of trace radioactive aerosols and fission gases is reviewed in the context of monitoring atmospheric radiation plumes and off-gas streams of molten salt reactors. Finally, concluding remarks will present future outlooks on the role of LA plasma spectroscopy in the nuclear community.

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Section: Laser Ablation Plasma Chemistrymentioning

confidence: 99%

Laser Ablation Plasmas and Spectroscopy for Nuclear Applications

Kwapis,

Borrero,

Latty

et al. 2023

Appl Spectrosc

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Dynamics of planar gas expansion during nanosecond laser evaporation into a low-pressure background gas

Morozov

Титарев

2022

Physics of Fluids

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A numerical study in a one-dimensional planar formulation of the dynamics of the neutral gas expansion during nanosecond laser evaporation into a low-pressure background gas is carried out using two different kinetic approaches: the direct simulation Monte Carlo method and direct numerical solution of the Bhatnagar–Gross–Krook equation. Results were obtained for a wide range of parameters: the background gas pressure, masses of evaporated and background particles, temperature and pressure of saturated vapor on the evaporation surface, and evaporation duration. They are in good agreement with the analytical continuum solution for unsteady evaporation into the background gas. The dynamics of the expansion is analyzed, and the characteristic times and distances that determine the main stages of the expansion process are established. General regularities are obtained that describe the dynamics of the motion of external and internal shock waves and the contact surface as well as the maximum density of evaporated particles and the characteristic temperatures of evaporated and background particles in the compressed layer. The obtained results are important for understanding and describing the change in the mixing layer during nanosecond laser deposition in a low-pressure background gas.

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Shock physics and shadowgraphic measurements of laser-produced cerium plasmas

Kwapis¹,

Hewitt

Hartig³

2023

Opt. Express

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Shadowgraphic measurements are combined with theory on gas-dynamics to investigate the shock physics associated with nanosecond laser ablation of cerium metal targets. Time-resolved shadowgraphic imaging is performed to measure the propagation and attenuation of the laser-induced shockwave through air and argon atmospheres at various background pressures, where stronger shockwaves characterized by higher propagation velocities are observed for higher ablation laser irradiances and lower pressures. The Rankine-Hugoniot relations are also employed to estimate the pressure, temperature, density, and flow velocity of the shock-heated gas located immediately behind the shock front, predicting larger pressure ratios and higher temperatures for stronger laser-induced shockwaves.

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Shock front detachment during pulsed laser ablation of graphite

Cited by 3 publications

References 60 publications

Laser Ablation Plasmas and Spectroscopy for Nuclear Applications

Laser Ablation Plasmas and Spectroscopy for Nuclear Applications

Dynamics of planar gas expansion during nanosecond laser evaporation into a low-pressure background gas

Shock physics and shadowgraphic measurements of laser-produced cerium plasmas

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