Time evolution of laser-ablation plumes and induced shock waves in low-pressure gas

Chiba, Rimpei; Ishikawa, Yuta; Hasegawa, Jun; Horioka, Kazuhiko

doi:10.1063/1.4986085

Cited by 16 publications

(5 citation statements)

References 29 publications

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“…When the focal point is 5 mm below the plate, the initial plasma is generated at the surface of the target by LA. The expansion of the plasma is not significant, which is consistent with the result of Chiba et al [45].…”

Section: Laser-induced Gas Breakdown and Laser Ablation In Quiescent Airsupporting

confidence: 92%

A comparative study of laser-induced gas breakdown ignition and laser ablation ignition in a supersonic combustor

An¹,

Yang

Wang³

et al. 2020

J. Phys. D: Appl. Phys.

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Cavity ignition was achieved in a supersonic combustor by laser-induced gas breakdown (LIGB) and laser ablation (LA). High-speed photography and schlieren imaging were employed to characterize the ignition processes. schlieren imaging was also applied to visualize LIGB and LA in quiescent air. The input energy was approximately 200 mJ. The distance between the focal point of the convex lens and the target plate (d) varied from 10 mm above the target plate (d = 10 mm) to 5 mm below the target plate (d = −5 mm). The experiments performed in quiescent air indicated that the plasma of LA (d = −5 mm) was relatively small. Compared to LIGB, the expansion of the hot plume resulting from LA was less significant because the plate prevented the formation of the third lobe. The primary shock wave of LA propagated faster than that of LIGB because of high pressure ratio between the plasma and the ambient air. In the supersonic combustor with d = 5 or 10 mm, the laser induced a plasma by LIGB at the focal point and induced another plasma by LA at the cavity floor. These two tests were the combination of LIGB ignition and LA ignition. LA ignition was achieved in the test with d = −5 mm. The ignition process of the test with d = 10 mm was the slowest because of severe plasma quenching at the focal point. For the early stage of ignition, the flame kernels of the tests with d = 5 and −5 mm were different. However, the differences gradually vanished after the flame kernels reached the cavity leading edge. The ignition times of these two tests were almost the same. Therefore, the plasma resulting from LA was as effective as the plasma generated by LIGB in terms of ignition. Laser ablation ignition was a promising ignition method in a supersonic combustor.

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Section: Laser-induced Gas Breakdown and Laser Ablation In Quiescent Airsupporting

confidence: 92%

A comparative study of laser-induced gas breakdown ignition and laser ablation ignition in a supersonic combustor

An¹,

Yang

Wang³

et al. 2020

J. Phys. D: Appl. Phys.

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“…The creation of the laser-induced plasma is accompanied by a shock wave, which can be described as an N-wave acoustic pulse 46 primarily, a short, approximately 300-μs-long compression/rarefaction acoustic signal. This signal is followed by echoes on nearby rocks and the rover structure, plus diffraction.…”

Section: Methodsmentioning

confidence: 99%

In situ recording of Mars soundscape

Maurice

Chide

Murdoch

et al. 2022

Nature

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Before the Perseverance rover landing, the acoustic environment of Mars was unknown. Models predicted that: (1) atmospheric turbulence changes at centimetre scales or smaller at the point where molecular viscosity converts kinetic energy into heat1, (2) the speed of sound varies at the surface with frequency2,3 and (3) high-frequency waves are strongly attenuated with distance in CO2 (refs. 2–4). However, theoretical models were uncertain because of a lack of experimental data at low pressure and the difficulty to characterize turbulence or attenuation in a closed environment. Here, using Perseverance microphone recordings, we present the first characterization of the acoustic environment on Mars and pressure fluctuations in the audible range and beyond, from 20 Hz to 50 kHz. We find that atmospheric sounds extend measurements of pressure variations down to 1,000 times smaller scales than ever observed before, showing a dissipative regime extending over five orders of magnitude in energy. Using point sources of sound (Ingenuity rotorcraft, laser-induced sparks), we highlight two distinct values for the speed of sound that are about 10 m s−1 apart below and above 240 Hz, a unique characteristic of low-pressure CO2-dominated atmosphere. We also provide the acoustic attenuation with distance above 2 kHz, allowing us to explain the large contribution of the CO2 vibrational relaxation in the audible range. These results establish a ground truth for the modelling of acoustic processes, which is critical for studies in atmospheres such as those of Mars and Venus.

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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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Time evolution of laser-ablation plumes and induced shock waves in low-pressure gas

Cited by 16 publications

References 29 publications

A comparative study of laser-induced gas breakdown ignition and laser ablation ignition in a supersonic combustor

A comparative study of laser-induced gas breakdown ignition and laser ablation ignition in a supersonic combustor

In situ recording of Mars soundscape

Laser Ablation Plasmas and Spectroscopy for Nuclear Applications

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