Spatial characterization of laser-induced sparks in air

Beduneau, J.L.; Ikeda, Yuji

doi:10.1016/s0022-4073(03)00136-5

Cited by 61 publications

(28 citation statements)

References 34 publications

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“…[58][59][60][61][62][63]. Assuming that the laser beam is cylindrical in shape, the length l, radius r, beam diameter d, beam divergence h, and focal length of the lens f used to focus the laser are related to each other by Eqs.…”

Section: Characterization Of the Laser Parameters And The Ablation Prmentioning

confidence: 99%

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

2010

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Laser-induced breakdown spectroscopy (LIBS) has become a very popular analytical method in the last decade in view of some of its unique features such as applicability to any type of sample, practically no sample preparation, remote sensing capability, and speed of analysis. The technique has a remarkably wide applicability in many fields, and the number of applications is still growing. From an analytical point of view, the quantitative aspects of LIBS may be considered its Achilles' heel, first due to the complex nature of the laser–sample interaction processes, which depend upon both the laser characteristics and the sample material properties, and second due to the plasma–particle interaction processes, which are space and time dependent. Together, these may cause undesirable matrix effects. Ways of alleviating these problems rely upon the description of the plasma excitation-ionization processes through the use of classical equilibrium relations and therefore on the assumption that the laser-induced plasma is in local thermodynamic equilibrium (LTE). Even in this case, the transient nature of the plasma and its spatial inhomogeneity need to be considered and overcome in order to justify the theoretical assumptions made. This first article focuses on the basic diagnostics aspects and presents a review of the past and recent LIBS literature pertinent to this topic. Previous research on non-laser-based plasma literature, and the resulting knowledge, is also emphasized. The aim is, on one hand, to make the readers aware of such knowledge and on the other hand to trigger the interest of the LIBS community, as well as the larger analytical plasma community, in attempting some diagnostic approaches that have not yet been fully exploited in LIBS.

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Section: Characterization Of the Laser Parameters And The Ablation Prmentioning

confidence: 99%

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

2010

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“…Increased plasma volume at higher pulse energies is also demonstrated by Bindhu et al [9]. Fluctuations of plasma size and location of the edges of the plasma were observed by Beduneau et al [10] and were correlated with the optical configuration for different focal lengths of 50 mm, 100 mm and 300 mm. Fluctuations are greater for a long focal length, but the plasma size is simultaneously increased.…”

Section: Introductionmentioning

confidence: 64%

Influence of focal point properties on energy transfer and plasma evolution during laser ignition process with a passively q-switched laser

et al. 2016

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Miniaturized passively q-switched laser ignition systems are a promising alternative to conventional ignition sources to ensure a reliable ignition under difficult conditions. In this study the influences of focal point properties on energy transfer from laser to plasma as well as plasma formation and propagation are investigated as the first steps of the laser induced ignition process. Maximum fluence and fluence volume are introduced to characterize focal point properties for varying laser pulse energies and focusing configurations. The results show that the transferred laser energy increases with increasing maximum fluence. During laser emission plasma propagates along the beam path of the focused laser beam. Rising maximum fluence results in increased plasma volume, but expansion saturates when fluence volume reaches its maximum.

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“…The plasma core becomes asymmetrical in shape on the optical axis of the laser but does not indicate a symmetrical shape in the laser incident direction (1), (2) . Therefore, if the breakdown point (z b , r b ) was defined as the geometrical center of the plasma core, z b was easily determined as the center of the laser beam.…”

Section: Laser and Opticsmentioning

confidence: 93%

“…When a laser-induced breakdown occurs, a plasma core is formed near the laser focusing point, and then its volume increases toward the incident laser direction (1), (2) . The plasma core becomes asymmetrical in shape on the optical axis of the laser but does not indicate a symmetrical shape in the laser incident direction (1), (2) .…”

Section: Laser and Opticsmentioning

confidence: 99%

Laser Extinguishment of CH4-N2/Air Counterflow Diffusion Flame

Torikai

Kitajima

Takeuchi

2006

JSME international journal. Ser. B, Fluids and thermal engineer

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We have examined the laser extinguishment of a CH 4 -N 2 /Air counterflow diffusion flame. Laser extinguishment is to blow off flames by a laser-induced breakdown. A Qswitched Nd:YAG laser (energy; 200 mJ/pulse) and a 100-mm focal-length lens were used. The laser-extinguishment probabilities were examined by varying the fuel concentration and the distance from the breakdown point to the flame. As a result, the two concentration limits were clarified. One was the laser extinguishable limit, below which the flame could be extinguished perfectly by laser. The other was the laser inextinguishable limit, over which any flame could not be extinguished. Moreover, it was considered that determination of the laser extinguishable limit was mainly influenced by the laser-induced blast wave. On the other hand, it could be considered that not only the blast wave but also hot gas and turbulence due to the optical breakdown influenced the determination of the laser inextinguishable limit.

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Spatial characterization of laser-induced sparks in air

Cited by 61 publications

References 34 publications

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

Influence of focal point properties on energy transfer and plasma evolution during laser ignition process with a passively q-switched laser

Laser Extinguishment of CH4-N2/Air Counterflow Diffusion Flame

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