Hydrogen alpha laser ablation plasma diagnostics

Parigger, Christian G.; Surmick, David M.; Gautam, Ghaneshwar; Sherbini, Ashraf M. El

doi:10.1364/ol.40.003436

Cited by 32 publications

(24 citation statements)

References 12 publications

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“…Usually, one measures the width of Balmer series lines of hydrogen that occur in the visible spectrum for electron density determination, and one integrates the area of these lines with respect to the continuum and constructs Boltzmann plots for excitation temperature inferences. Optical emission spectroscopy (OES) indicates the presence of molecular species that can elucidate sample composition or interaction processes in the ambient atmosphere [3][4][5][6]. Typically, atomic hydrogen lines, C 2 Swan bands, and the cyanide (CN) violet system appear in various applications [6,7] of laser-induced OES such as in experiments with hydrocarbons [8].…”

Section: Introductionmentioning

confidence: 99%

Temporally and Spatially Resolved Emission Spectroscopy of Hydrogen, Cyanide and Carbon in Laser-Induced Plasma

Parigger

Helstern

Gautam

2019

Atoms

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In this study, we examine the atomic and molecular signatures in laser-induced plasma. Abel inversions of measured line-of-sight data reveal insight into the radial plasma distribution. Laser-plasma is generated with 6 ns, Q-switched Nd:YAG radiation with energies in the range of 100 to 800 mJ. Temporally- and spatially-resolved emission spectroscopy investigates expansion dynamics. Specific interests include atomic hydrogen (H) and cyanide (CN). Atomic hydrogen spectra indicate axisymmetric shell structures and isentropic expansion of the plasma kernel. The recombination radiation of CN emanates within the first 100 nanoseconds for laser-induced breakdown in a 1:1 mole ratio CO2:N2 gas mixture. CN excitation temperatures are determined from fitting recorded and computed spectra. Chemical equilibrium mole fractions of CN are computed for air and the CO2:N2 gas mixture. Measurements utilize a 0.64-m Czerny–Turner type spectrometer and an intensified charge-coupled device.

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Section: Introductionmentioning

confidence: 99%

Temporally and Spatially Resolved Emission Spectroscopy of Hydrogen, Cyanide and Carbon in Laser-Induced Plasma

Parigger

Helstern

Gautam

2019

Atoms

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“…Parigger et al [10] by analyzing the Büscher et al [11] deduced from their benchmark experiment at the gas-liner pinch the following relation:…”

Section: H α Linementioning

confidence: 99%

Electron Density

2017

Diagnostics of Laboratory and Astrophysical Plasmas Using Spectral Lineshapes of One-, Two-, and Three-Electron Systems

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The electron density N e is the primary plasma parameter. In laboratory and astrophysical plasmas, it varies over 20 orders of magnitude (in distinction to any other plasma parameter): from N e ∼ (10 3 -10 4 ) cm −3 in astrophysical objects called H II regions to N e ∼ (10 23 -10 24 ) cm −3 in plasmas produced by very powerful lasers. (For comparison, the electron temperature T e of these two extreme types of plasmas varies only by about three orders of magnitude: from ∼1 eV in H II regions to ∼1 keV in plasmas produced by very powerful lasers.) Obviously, there is no single universal method for measuring N e that can be applied over 20 orders of magnitude. The overwhelming majority of method for measuring N e are based on Stark broadening (SB) of various spectral lines by ion and electron microfields in plasmas.SB of spectral lines in plasmas is controlled by the electron density N e and to some extent by the electron (T e ) and ion (T i ) temperatures. Therefore, it was used for measuring the electron density in a very broad range by choosing appropriate spectral lines. The experimental determination of the electron density relies mostly on measuring the Stark width because it is typically by an order of magnitude greater than the Stark shift.Hydrogenic radiators are the most appropriate for this purpose. The overwhelming majority of the states of hydrogenic radiators 3 Diagnostics of Laboratory and Astrophysical Plasmas Using Spectral Lineshapes of One-, Two-, and Three-Electron Systems Downloaded from www.worldscientific.com by 34.215.51.103 on 05/10/18. For personal use only. Diagnostics of Laboratory and Astrophysical Plasmaspossess permanent dipole moments, thus, making these radiators more sensitive to ion and electron microfields in plasmas than non-hydrogenic radiators. The underlying theories are presented in Appendices A-E, G-I, and L. In practice, there could be competing broadening mechanisms, such as, Doppler, instrumental and Zeeman broadenings, as well as a self-absorption. Therefore, the task is to find practical methods for extracting the Stark width despite the competing broadening effects, some of which could actually exceed the SB in certain situations. These methods are the focus of the subsequent sections. Using the Intense (low-n) Lines of Hydrogenic Spectral SeriesIn hydrogen atoms and hydrogenlike ions (hereafter, hydrogenic atoms, for brevity), in spectral series, i.e., in radiative transitions between the upper states of various principal quantum number n and the fixed lower state of the principal quantum number n 0 , the most intense are the lines, corresponding to n = n 0 + 1 (α-line), n 0 + 2 (β-line), n 0 +3 (γ-line), n 0 +4 (δ-line) -in order of diminishing intensity. So, on the first glance, it seems that one should use the most intense lines, like the α-line or the β-line. However, there is a trade-off. The SB of the α-line is the smallest out of the spectral series. The SB increases along the spectral series: roughly speaking, as ∼n 2 for the ion broadening and ∼n 4 for the e...

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“…For instance, line-ofsight measurements of laser-induced plasma at or near an ice surface 1 show self-reversal tips at the un-shifted resonance wavelength of the hydrogen alpha line of the Balmer series. Typical "fingerprints" due to re-absorption include self-reversal and line-shape distortions [2][3][4][5][6][7][8] .…”

Section: Introductionmentioning

confidence: 99%

Self-Absorption Analysis of Silver Resonance Lines in Nano-Material Laser Produced Plasma

Sherbini¹,

Ma²,

Mr³

et al. 2018

Preprint

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The resonance spectra of neutral silver indicate self-absorption for the studied Ag I lines at the wavelengths of 327.9 nm and 338.2 nm. The center dip is associated with self-reversal due to self-absorption in the plasma. The Q-switched radiation of 355 nm, 532 nm, or 1064 nm from a Nd:YAG laser device generates the plasma at the surface of silver nano-material targets, with experiments conducted in standard ambient temperature and pressure laboratory air. Procedures for recovery of the spectral line shapes confirm that over and above the effects of selfreversal, line shape distortion are important in the analysis. The work discusses parameters describing selfabsorption when using fluence levels of 2 to 33 J/cm 2 to generate the plasma. Furthermore, subsidiary calibration efforts that utilize the hydrogen alpha line of the Balmer series show that the Ag I lines at 827.35 nm and 768.7 nm are optically thin.

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Hydrogen alpha laser ablation plasma diagnostics

Cited by 32 publications

References 12 publications

Temporally and Spatially Resolved Emission Spectroscopy of Hydrogen, Cyanide and Carbon in Laser-Induced Plasma

Temporally and Spatially Resolved Emission Spectroscopy of Hydrogen, Cyanide and Carbon in Laser-Induced Plasma

Electron Density

Self-Absorption Analysis of Silver Resonance Lines in Nano-Material Laser Produced Plasma

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