scholarly journals Hypersonic Imaging and Emission Spectroscopy of Hydrogen and Cyanide Following Laser-Induced Optical Breakdown

2020 ◽  
Author(s):  
Christian G Parigger ◽  
Christopher M Helstern ◽  
Ghaneshwar Gautam
Keyword(s):  
Emission Spectroscopy ◽  
Time Delays ◽  
Optical Breakdown ◽  
Digital Camera ◽  
Emission Spectra ◽  
Gas Mixtures ◽  
Plasma Expansion ◽  
Air Breakdown ◽  
Intensified Charge Coupled Device ◽  
Gas Breakdown

This work communicates the connection of measured shadowgraphs from optically induced air breakdown with emission spectroscopy in selected gas mixtures. Laser-induced optical breakdown is generated using 850 mJ and 170 mJ, 6-ns pulses at a wavelength of 1064 nm, the shadowgraphs are recorded using time-delayed 5-ns pulses at a wavelength of 532 nm and a digital camera, and emission spectra are recorded for typically a dozen of discrete time-delays from optical breakdown by employing an intensified charge-coupled device. The symmetry of the breakdown event can be viewed as close-to spherical symmetry for time-delays of several 100 ns. Spectroscopic analysis explores well-above hypersonic expansion dynamics using primarily the diatomic molecule cyanide and atomic hydrogen emission spectroscopy. Analysis of the air breakdown and selected gas breakdown events permits the use of Abel inversion for inference of the expanding species distribution. Typically, species are prevalent at higher density near the hypersonically expanding shockwave, measured by tracing cyanide and a specific carbon atomic line. Overall, recorded air breakdown shadowgraphs are indicative of laser-plasma expansion in selected gas mixtures, and optical spectroscopy delivers analytical insight into plasma expansion phenomena.

scholarly journals Hypersonic Imaging and Emission Spectroscopy of Hydrogen and Cyanide Following Laser-Induced Optical Breakdown

Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2116
Author(s):  
Christian G. Parigger ◽  
Christopher M. Helstern ◽  
Ghaneshwar Gautam
Keyword(s):  
Emission Spectroscopy ◽  
Time Delays ◽  
Optical Breakdown ◽  
Digital Camera ◽  
Emission Spectra ◽  
Gas Mixtures ◽  
Plasma Expansion ◽  
Air Breakdown ◽  
Intensified Charge Coupled Device ◽  
Gas Breakdown

This work communicates the connection of measured shadowgraphs from optically induced air breakdown with emission spectroscopy in selected gas mixtures. Laser-induced optical breakdown is generated using 850 and 170 mJ, 6 ns pulses at a wavelength of 1064 nm, the shadowgraphs are recorded using time-delayed 5 ns pulses at a wavelength of 532 nm and a digital camera, and emission spectra are recorded for typically a dozen of discrete time-delays from optical breakdown by employing an intensified charge-coupled device. The symmetry of the breakdown event can be viewed as close-to spherical symmetry for time-delays of several 100 ns. Spectroscopic analysis explores well-above hypersonic expansion dynamics using primarily the diatomic molecule cyanide and atomic hydrogen emission spectroscopy. Analysis of the air breakdown and selected gas breakdown events permits the use of Abel inversion for inference of the expanding species distribution. Typically, species are prevalent at higher density near the hypersonically expanding shockwave, measured by tracing cyanide and a specific carbon atomic line. Overall, recorded air breakdown shadowgraphs are indicative of laser-plasma expansion in selected gas mixtures, and optical spectroscopy delivers analytical insight into plasma expansion phenomena.

scholarly journals Plasma Expansion Dynamics in Hydrogen Gas

Atoms ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 46 ◽  
Author(s):  
Ghaneshwar Gautam ◽  
Christian Parigger
Keyword(s):  
Time Delays ◽  
Yttrium Aluminum Garnet ◽  
Optical Breakdown ◽  
Emission Spectra ◽  
Hydrogen Gas ◽  
Pure Hydrogen ◽  
Fundamental Wavelength ◽  
A Cell ◽  
Intensified Charge Coupled Device ◽  
Spectrally Resolved

Micro-plasma is generated in ultra-high-pure hydrogen gas, which fills the inside of a cell at a pressure of (1.08 ± 0.033) × 105 Pa by using a Q-switched neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser device operated at a fundamental wavelength of 1064 nm and a pulse duration of 14 ns. The micro-plasma emission spectra of the hydrogen Balmer alpha line, Hα, are recorded with a Czerny–Turner type spectrometer and an intensified charge-coupled device. The spectra are calibrated for wavelength and corrected for detector sensitivity. During the first few tens of nanoseconds after the initiation of optical breakdown, the significant Stark-broadened and Stark-shifted Hα lines mark the well-above hypersonic outward expansion. The vertical diameters of the spectrally resolved plasma images are measured for the determination of expansion speeds, which were found to decrease from 100 to 10 km/s for time delays of 10 to 35 ns. For time delays of 0.5 µs to 1 µs, the expansion speed of the plasma decreases to the speed of sound of 1.3 km/s in the near ambient temperature and pressure of the hydrogen gas.

scholarly journals Plasma Expansion Dynamics in Ultra-High-Pure Hydrogen Gas

2018 ◽  
Author(s):  
Ghaneshwar Gautam ◽  
Christian G. Parigger
Keyword(s):  
Time Delays ◽  
Optical Breakdown ◽  
Emission Spectra ◽  
Hydrogen Gas ◽  
Pure Hydrogen ◽  
Charge Coupled Device ◽  
A Cell ◽  
Intensified Charge Coupled Device ◽  
Spectrally Resolved ◽  
Pressure Hydrogen

Micro-plasma is generated in ultra-high-pure hydrogen gas filled inside a cell at a pressure of (1.08 ± 0.033) × 105 Pa (810 ± 25 Torr) by using a Q-switched Nd:YAG laser device operated at 1064 nm wavelength and 14 ns pulse duration. Micro-plasma emission spectra of the hydrogen Balmer alpha line, Hα, are recorded with a Czerny-Turner type spectrometer and an intensified charge-coupled device. The spectra are calibrated for wavelength and corrected for detector sensitivity. During the first few tens of nanoseconds after initiating optical breakdown, significantly Stark-broadened and Stark-shifted Hα lines mark the well-above hypersonic outward expansion. The vertical diameters of the spectrally resolved plasma images are measured for time delays of 10 ns to 35 ns to determine expansion speeds of the order of 100 km/s to 10 km/s. For time delays of the order of 0.5 µs to 1 µs, the expansion decreases to the speed of sound of 1.3 km/s in the near ambient temperature and pressure hydrogen gas.

scholarly journals Time-Resolved Emission Spectroscopy of Atomic and Molecular Species in Laser-Induced Plasma

2018 ◽  
Author(s):  
Christian Parigger ◽  
Ghaneshwar Gautam ◽  
Christopher M Helstern
Keyword(s):  
Emission Spectroscopy ◽  
Local Equilibrium ◽  
Optical Breakdown ◽  
Emission Spectra ◽  
Laser Pulses ◽  
Nano Particles ◽  
Nanosecond Laser ◽  
Pure Hydrogen ◽  
Laser Induced Plasma ◽  
Nanosecond Laser Pulses

This work examines atomic and molecular signatures in laser-induced plasma in standard ambient temperature and pressure environments, including background contributions to the spectra that depend on the laser pulse-width.  Investigations include solids, gases, and nano-particles. Abel inversions of measured line-of-sight data reveal insight into the radial plasma distribution. For nominal 6 nanosecond laser pulses and for pulse-energies in the range of 100 to 800 milli-Joules, expansion dynamics and turbulence due to shock phenomena are elucidated to address local equilibrium details that are frequently assumed in spatially averaged emission spectroscopy. Chemical equilibrium computations reveal temperature dependence of selected plasma species. Specific interests include atomic hydrogen (H) and cyanide (CN). The atomic H spectra, collected following optical breakdown in ultra-high-pure hydrogen and 9:1 mixtures of ultra-pure hydrogen and nitrogen gases, indicate spherical shell structures and isentropic expansion of the plasma kernel over and above the usual shockwave. The recombination radiation of CN emanates within the first 100 nanoseconds for laser-induced breakdown in a 1:1 CO2:N2 gas mixture when using nanosecond laser pulses to create the micro-plasma. The micro-plasma is generated using 1064 nm, 150 mJ, 6 ns Q-switched Nd:YAG  laser radiation. Measurements of the optical emission spectra utilize a 0.64 m Czerny-Turner type spectrometer and an intensified charge-coupled device.

Optical Breakdown on the Inclined Target: The Features of the Erosive Plume Formation

2015 ◽  
Vol 723 ◽  
pp. 825-828
Author(s):  
Alexey Ilyin ◽  
Ivan Nagorny ◽  
Yulia Biryukova
Keyword(s):  
Laser Radiation ◽  
Electron Density ◽  
Oblique Incidence ◽  
Optical Breakdown ◽  
Plasma Expansion ◽  
Time And Space ◽  
Expansion Mechanism ◽  
Plume Area ◽  
Air Breakdown

For oblique incidence of laser radiation on the target, the breakdown of air and erosive jet are separated in time and space. The electron density is higher in the air breakdown area while Al I density is higher in an erosive plume area. We also defined plasma expansion mechanism and estimate the time of erosive plume formation.

Systematic investigation of plasma emission spectra during microwave diamond deposition from CH4CO2 and C2H2CO2 gas mixtures

1993 ◽  
Vol 2 (2-4) ◽  
pp. 389-392 ◽  
Author(s):  
G. Balestrino ◽  
M. Marinelli ◽  
E. Milani ◽  
A. Paoletti ◽  
P. Paroli ◽  
...  
Keyword(s):  
Emission Spectra ◽  
Gas Mixtures ◽  
Systematic Investigation ◽  
Plasma Emission ◽  
Diamond Deposition ◽  
Co2 Gas

scholarly journals Plasma diagnostics using Kα satellite emission spectroscopy in light ion beam fusion experiments

1995 ◽  
Vol 13 (2) ◽  
pp. 231-241 ◽  
Author(s):  
J.J. MacFarlane ◽  
P. Wang ◽  
J.E. Bailey ◽  
T.A. Mehlhorn ◽  
R.J. Dukart
Keyword(s):  
Emission Spectroscopy ◽  
Impact Ionization ◽  
Ion Beam ◽  
Emission Spectra ◽  
Particle Beam ◽  
High Energy ◽  
Atomic Level ◽  
High Energy Density ◽  
Equilibrium Equations ◽  
X Ray

Kα satellite spectroscopy can be a valuable technique for diagnosing conditions in high energy density plasmas. Kα emission lines are produced in intense light ion beam plasma interaction experiments as 2p electrons fill partially open Is shells created by the ion beam. In this paper, we present results from collisional-radiative equilibrium (CRE) calculations which show how Kα emission spectroscopy can be used to determine target plasma conditions in intense lithium beam experiments on Particle Beam Fusion Accelerator-II (PBFAII) at Sandia National Laboratories. In these experiments, 8–10 MeV lithium beams with intensities of 1–2 TW/cm2 irradiate planar multilayer targets containing a thin Al tracer. Kα emission spectra are measured using an X-ray crystal spectrometer with a resolution of λ/∆λ = 1200. The spectra are analyzed using a CRE model in which multilevel (NL ∼ 103) statistical equilibrium equations are solved self-consistently with the radiation field and beam properties to determine atomic level populations. Atomic level-dependent fluorescence yields and ion-impact ionization cross sections are used in computing the emission spectra. We present results showing the sensitivity of the Kα emission spectrum to temperature and density of the Al tracer. We also discuss the dependence of measured spectra on the X-ray crystal spectral resolution, and how additional diagnostic information could be obtained using multiple tracers of similar atomic number.

Emission spectroscopy as a noninvasive probe for process control during radio frequency sputter deposition of PbTe

1989 ◽  
Vol 67 (4) ◽  
pp. 287-293 ◽  
Author(s):  
J. G. Cook ◽  
M. S. Aouadi ◽  
S. R. Das
Keyword(s):  
Electron Temperature ◽  
Emission Spectroscopy ◽  
Emission Spectra ◽  
Sputter Deposition ◽  
Emission Lines ◽  
Substrate Bias ◽  
Rf Power ◽  
Magnetron Discharge ◽  
Substrate Bias Voltage ◽  
Pressure Changes

An rf magnetron discharge used to sputter PbTe in Ar is analyzed using emission spectroscopy. The intensity (I) of the strong Pb, Te, and Ar emission lines is determined near the target and near the substrate as the rf power or gas pressure is varied. It is shown that as the rf power is varied at pressures below 0.5 Pa, the electron temperature is not affected, so that the sputtered atom density NPb is proportional to IPb/IAr. The electron temperature is, however, sensitive to pressure changes. Application of a substrate bias voltage has a large effect on the emission spectra which are not understood.

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