Material: Air

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7 articles found

Spatiotemporal evolution of the plasma from dual-pulsed laser-induced breakdown in an atmospheric air

Author: Wermer, L. ; et. al.

Journal: Plasma Sources Science and Technology (2018)

Fundamentals

DOI: 10.1088/1361-6595/aa9fe2

Authors
Bak, M. S. ; Im, S. K. ; Lefkowitz, J. K. ; Ombrello, T. M.

Keywords

laser-induced breakdown; optical emission spectroscopy; dual-pulsed laser; discharge imaging;AMBIENT CONDITIONS; IGNITION ENERGY; SPECTRAL-LINES; PRESSURE AIR; SPECTROSCOPY; ABLATION; SPARK; CRYSTAL; PROPAGATION; MIXTURES

Abstract

The spatiotemporal evolution of dual-pulsed laser-induced breakdown (DPLIB) was experimentally investigated in a quiescent atmospheric air. DPLIB with time intervals between pulses of 30-100 ns and pulse energies of 10-30 mJ were compared to a single laser-induced breakdown of the same total energy. An intensified CCD camera was used to capture direct images from the onset of the breakdown until 300 ns after the breakdown. The spatial and temporal temperature and electron number density were obtained from the N II spectrum at 500 nm. With increasing laser pulse energy, the breakdown perimeter, temperature and electron number density all increase. For DPLIB, the second breakdown occurs on the outside axial edges of the first breakdown increasing the breakdown perimeter. The uneven distribution of energy to the plasma creates an uneven temperature distribution. The electron number density is increased at the edges of the DPLIB for times less than 150 ns after the first breakdown. Depending on the electron number density of the first breakdown and the focal point location of the second breakdown, the second breakdown could occur on either the near side (closest to the focusing lens) or the far side (furthest from the focusing lens) of the focal point in the axial direction of the laser beam.

Area:

Plasma diagnostics

Material:

Air

Elements:

Lines [nm]:

Ni II 490.99 nm

Emmision lines:
Ni II 490.99 nm

Confinement and enhancement of an airborne atmospheric laser-induced plasma using an ultrasonic acoustic resonator

Author: Bierstedt, A. ; et. al.

Journal: Journal of Analytical Atomic Spectrometry (2018)

Fundamentals Applications

DOI: 10.1039/c7ja00297a

Authors
Panne, U. ; Riedel, J.

Keywords

INDUCED BREAKDOWN SPECTROSCOPY; LEVITATED DROPLETS; MASS-SPECTROMETRY; AIR SPARK; ELEMENTS; ZINC; LEAD

Abstract

Optical elemental analysis in the gas phase typically relies on electrically driven plasmas. As an alternative approach, laser-induced plasmas (LIPs) have been suggested but have so far been only scarcely used. Here, a novel signal enhancement strategy for laser-based airborne plasma optical emission spectroscopyfor gas phase analytics is presented. In contrast to an electrically driven plasma, in the laser-induced analogue dynamic matter transport equilibrium builds up. The latter results in a rarefied density regime in the plasma core itself, surrounded by an area of compressed matter. The central rarefaction leads to a decrease in plasma intensity and analyte number density, both of which are detrimental for analytical purposes. Since the repetitive ignition of LIPs is a transient process, a restoration of the former gaseous medium by other dynamically equilibrated diffusion processes would be favourable. The presented combination of an airborne LIP and an ultrasonic acoustic resonator yields a fourfold signal enhancement while the background contribution of ubiquitous air is at the same time effectively suppressed. Since the entire enhancement effect occurs without contact, no additional sources for abrasive sample contamination are introduced.

Area:

Plasma diagnostics

Material:

Air

Elements:

Lines [nm]:

N I 746.83 nm N I 821.63 nm N I 868.61 nm N II 343.72 nm N II 399.50 nm N II 462.14 nm N II 500.15 nm N II 567.60 nm N II 593.18 nm

Lines [nm]:

O I 777.42 nm O I 844.64 nm O II 715.61 nm

Lines [nm]:

H I 656.28 nm

Lines [nm]:

Ar I 811.53 nm

Lines [nm]:

Ni II 444.47 nm

Emmision lines:
N II 343.72 nm
N II 399.50 nm
Ni II 444.47 nm
N II 462.14 nm
N II 500.15 nm
N II 567.60 nm
N II 593.18 nm
H I 656.28 nm
O II 715.61 nm
N I 746.83 nm
O I 777.42 nm
Ar I 811.53 nm
N I 821.63 nm
O I 844.64 nm
N I 868.61 nm

Characterization of laser-induced plasmas as a complement to high-explosive large-scale detonations

Author: Kimblin, C. ; et. al.

Journal: AIP Advances (2017)

Applications

DOI: 10.1063/1.4999793

Authors
Capelle, G. A. ; Mao, X. L. ; Russo, R. E. ; Trainham, R.

Keywords

INDUCED BREAKDOWN SPECTROSCOPY; EMISSION-SPECTROSCOPY; MOLECULAR-EMISSION; ABLATION; AIR; CARBON; ALO; TEMPERATURE; GENERATION; CHEMISTRY

Abstract

Experimental investigations into the characteristics of laser-induced plasmas indicate that LIBS provides a relatively inexpensive and easily replicable laboratory technique to isolate and measure reactions germane to understanding aspects of high-explosive detonations under controlled conditions. Spectral signatures and derived physical parameters following laser ablation of aluminum, graphite and laser-sparked air are examined as they relate to those observed following detonation of high explosives and as they relate to shocked air. Laser-induced breakdown spectroscopy (LIBS) reliably correlates reactions involving atomic Al and aluminum monoxide (AlO) with respect to both emission spectra and temperatures, as compared to small-and large-scale high-explosive detonations. Atomic Al and AlO resulting from laser ablation and a cited small-scale study, decay within similar to 10(-5) s, roughly 100 times faster than the Al and AlO decay rates (similar to 10(-3) s) observed following the large-scale detonation of an Al-encased explosive. Temperatures and species produced in laser-sparked air are compared to those produced with laser ablated graphite in air. With graphite present, CN is dominant relative to N-2(+). In studies where the height of the ablating laser's focus was altered relative to the surface of the graphite substrate, CN concentration was found to decrease with laser focus below the graphite surface, indicating that laser intensity is a critical factor in the production of CN, via reactive nitrogen. (C) 2017 Author(s).

Area:

Industry ; Military

Material:

Air ; Aluminium ; Graphite

Elements:

Lines [nm]:

Al II 281.62 nm Al I 394.40 nm Al I 396.15 nm Al II 358.71 nm Al II 466.31 nm Al II 704.21 nm

Lines [nm]:

O I 777.19 nm O I 777.42 nm

Lines [nm]:

H I 656.27 nm

Lines [nm]:

N I 746.83 nm

Emmision lines:
Al II 281.62 nm
Al II 358.71 nm
Al I 394.40 nm
Al I 396.15 nm
Al II 466.31 nm
H I 656.27 nm
Al II 704.21 nm
N I 746.83 nm
O I 777.19 nm
O I 777.42 nm

Anomalous broadening and shift of emission lines in a femtosecond laser plasma filament in air

Author: Ilyin, A. A. ; et. al.

Journal: Spectrochimica Acta Part B: Atomic Spectroscopy (2017)

Fundamentals

DOI: 10.1016/j.sab.2017.10.010

Authors
Golik, S. S. ; Mayor, A. Y. ; Proschenko, D. Y. ; Shmirko, K. A.

Keywords

Filament; AC Stark effect; Rabi sideband; Line broadening; Amplified spontaneous emission;INDUCED BREAKDOWN SPECTROSCOPY; SPECTRAL-LINES; RADIATION; SYSTEM

Abstract

he temporal evolution of the width and shift of NI746.8 and OI777.4 nm lines is investigated in a filament plasma produced by a tightly focused femtosecond laser pulse (0.9 mJ, 48 fs). The nitrogen line shift and width are determined by the joint action of electron impact shift and the far-off resonance AC Stark effect. The intensive (I = 1.2.10(10) W/cm(2)) electric field of ASE (amplified spontaneous emission) and post-pulses result in a possible LS coupling break for the OI3p P-5 level and the generation of Rabi sidebands. The blueshifted main femtosecond pulse and Rabi sideband cause the stimulated emission of the N-2 1(+) system. The maximal widths of emission lines are approximately 6.7 times larger than the calculated Stark widths. (C) 2017 Elsevier B.V. All rights reserved.

Area:

Anomalous broadening ; Plasma diagnostics

Material:

Air ; Nitrogen ; Oxygen

Elements:

Lines [nm]:

N I 742.36 nm N I 744.23 nm N I 746.83 nm

Lines [nm]:

O I 777.42 nm O I 777.19 nm O I 777.54 nm

Emmision lines:
N I 742.36 nm
N I 744.23 nm
N I 746.83 nm
O I 777.19 nm
O I 777.42 nm
O I 777.54 nm

Harmonic generation at air-soil interface by femtosecond laser filament

Author: Chen, N. ; et. al.

Journal: Chinese Optics Letters (2017)

Fundamentals

DOI: 10.3788/COL201715.061902

Authors
Du, J. ; Leng, Y. X. ; Liu, J. S. ; Liu, Y. X. ; Sun, H. Y. ; Wang, T. J. ; Xia, J. H. ; Xia, Y. H. ; Yan, X. N. ; Zhu, Z. B.

Keywords

INDUCED BREAKDOWN SPECTROSCOPY; OPTICAL 2ND-HARMONIC GENERATION; PULSES; NANOSECOND; IONIZATION; PLASMA; MEDIA

Abstract

We observe the third-harmonic generation and second-harmonic generation together with element fluorescence from the interaction of a femtosecond laserfilament with a rough surface sample (sandy soil) in non-phase-matched directions. The harmonics prove to originate from the phase-matched surface harmonics and air filament, then scatter in non-phase-matched directions due to the rough surface. These harmonics occurr when the sample is in the region before and after the laser filament, where the laser intensity is not high enough to excite the element fluorescence. The observed harmonics are related to the element spectroscopy, which will benefit the understanding of the interaction of the laser filament with a solid and be helpful for the application on filament induced breakdown spectroscopy.

Area:

Harmonic generation

Material:

Air ; Soil

Elements:

Emmision lines:

On- and off-axis spectral emission features from laser-produced gas breakdown plasmas

Author: Harilal, S. S. ; et. al.

Journal: Physics of Plasmas (2017)

Fundamentals

DOI: 10.1063/1.4985678

Authors
Brumfield, B. E. ; Miloshevsky, A. ; Miloshevsky, G. ; Phillips, M. C. ; Skrodzki, P. J.

Keywords

PRECURSOR IONIZATION; TEMPORAL EVOLUTION; AMBIENT CONDITIONS; ENERGY-ABSORPTION; SHOCK-WAVE; AIR; SPECTROSCOPY; SPARK; ARGON; ABLATION

Abstract

Laser-heated gas breakdown plasmas or sparks emit profoundly in the ultraviolet and visible region of the electromagnetic spectrum with contributions from ionic, atomic, and molecular species. Laser created kernels expand into a cold ambient with high velocities during their early lifetime followed by confinement of the plasma kernel and eventually collapse. However, the plasma kernels produced during laser breakdown of gases are also capable of exciting and ionizing the surrounding ambient medium. Two mechanisms can be responsible for excitation and ionization of the surrounding ambient: photoexcitation and ionization by intense ultraviolet emission from the sparks produced during the early times of their creation and/or heating by strong shocks generated by the kernel during its expansion into the ambient. In this study, an investigation is made on the spectral features of on-and off-axis emission of laser-inducedplasma breakdown kernels generated in atmospheric pressure conditions with an aim to elucidate the mechanisms leading to ambient excitation and emission. Pulses from an Nd:YAG laser emitting at 1064 nm with a pulse duration of 6 ns are used to generate plasma kernels. Laser sparks were generated in air, argon, and helium gases to provide different physical properties of expansion dynamics and plasma chemistry considering the differences in laserabsorption properties, mass density, and speciation. Point shadowgraphy and time-resolved imaging were used to evaluate the shock wave and spark self-emission morphology at early and late times, while space and time resolved spectroscopy is used for evaluating the emission features and for inferring plasma physical conditions at on- and off-axis positions. The structure and dynamics of the plasma kernel obtained using imaging techniques are also compared to numerical simulations using the computational fluid dynamics code. The emission from the kernel showed that spectral features from ions, atoms, and molecules are separated in time with early time temperatures and densities in excess of 35 000 K and 4 x 10(18)/cm(3) with an existence of thermal equilibrium. However, the emission from the off-kernel positions from the breakdown plasmas showed enhanced ultraviolet radiation with the presence of N-2 bands and is represented by non-local thermodynamic equilibrium (non-LTE) conditions. Our results also highlight that the ultraviolet radiation emitted during the early time of spark evolution is the predominant source of the photo-excitation of the surrounding medium. Published by AIP Publishing.

Area:

Plasma diagnostics

Material:

Air ; Argon ; Helium

Elements:

Emmision lines:

Range extension in laser-induced breakdown spectroscopy using femtosecond-nanosecond dual-beam laser system

Author: Chu, W. ; et. al.

Journal: Applied Physics B: Lasers and Optics (2017)

Fundamentals

DOI: 10.1007/s00340-017-6749-0

Authors
Cheng, Y. ; Li, G. H. ; Li, Z. T. ; Wang, Z. S. ; Xie, H. Q. ; Yao, J. P. ; Zeng, B.

Keywords

NONLINEAR OPTICS; FILAMENTATION; AIR; OPERATION; PULSES; WATER; GAS

Abstract

We extend the detection range of laser-induced breakdown spectroscopy by combining high-intensity femtosecond laser pulses with high-energy nanosecond - CO2 laser pulses. The femtosecond laser pulses ionize the molecules and generate filament in air. The free electrons generated in the self-confined plasma channel by the femtosecond laser serve as the seed electrons which cause efficient avalanche ionization in the nanosecond - CO2 laser field. We show that the detection distance has been extended by three times with the assistance of femtosecond laser filamentation.

Area:

Industry

Material:

Air

Elements:

Emmision lines:

Material: Air

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