scholarly journals Magnetic field-induced signal enhancement in laser-produced lead plasma

2019 ◽  
Vol 37 (01) ◽  
pp. 67-78 ◽  
Author(s):  
M. Akhtar ◽  
A. Jabbar ◽  
N. Ahmed ◽  
S. Mehmood ◽  
Z.A. Umar ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Enhancement Factor ◽  
Electron Number Density ◽  
Laser Energy ◽  
Plasma Temperature ◽  
Number Density ◽  
Plasma Confinement ◽  
Electron Number ◽  
Line Intensities

AbstractLaser-induced breakdown spectroscopy has been exploited to investigate the laser-produced lead plasma with and without external magnetic field. Plasma on the lead surface was generated by focusing a beam of a Nd:YAG laser (532 nm). An external magnetic field was applied across the laser-produced plasma; its value was varied from 0.3 to 0.7 T and the time-integrated spectra were captured at different time delays. Maximum enhancement in the neutral and ionic line intensities have been observed at 130 mJ laser energy. The neutral line of Pb at 368.34 nm reveals an enhancement factor of nearly 1.3, 1.6, and 2.3 at 0.3, 0.5, and 0.7 T, whereas the Pb ionic line at 424.49 nm shows enhancement factor of approximately 2.8 and 4.2 at 0.3 and 0.7 T. The magnetic field effects on various plasma parameters such as plasma temperature, electron number density, and emission line intensities have also been investigated. The plasma parameter “β” is found to be <1 in all the experimental conditions which signifies that the enhancement in the signal intensity is due to the plasma confinement. The increase in the emission signal intensity, number density as well as plasma temperature is observed with increasing laser energy and magnetic field. The spatial and temporal behavior reveals that the plasma temperature and electron number density decrease slowly in the applied magnetic field due to the deceleration of the plasma plume. The optimized conditions for the maximum plasma confinement and the emission intensity enhancement are observed at 130 mJ laser energy at 0.7 T magnetic field.

scholarly journals Excitation and analytical characteristics of an ethanol loaded U-shaped arc

2003 ◽  
Vol 68 (2) ◽  
pp. 109-118 ◽  
Author(s):  
Marija Raskovic ◽  
Ivanka Holclajtner-Antunovic ◽  
Mirjana Tripkovic ◽  
Dragan Markovic
Keyword(s):  
Spectral Line ◽  
Electron Number Density ◽  
Ethanol Solution ◽  
Number Density ◽  
Electron Number ◽  
Plasma Parameters ◽  
Line Intensities ◽  
Ethanol Addition ◽  
Plasma Characteristics ◽  
Dc Arc

The effect of the ethanol load on the discharge and analytical parameters of an argon stabilized U-shaped DC arc has been recorded. Measurements of the radial distribution of the apparent temperatures and the electron number density of the DC plasma showed that ethanol addition causes a decrease in both plasma parameters. The changes in the plasma characteristics, as well as in transport and atomisation processes of the analyte cause a general change in the spectral line intensities, which depends on the physical characteristics of the analyte and the quantity of ethanol loaded into the plasma. Improved detection limits were obtained for V and Mn when a 10%(v/v) water?ethanol solution was nebulized into the plasma.

scholarly journals Influence of the Distance between Focusing Lens and Target Surface on the Characteristics of Laser-excited Lead Plasma

2021 ◽  
pp. 4694-4701
Author(s):  
Qusay Adnan Abbas
Keyword(s):  
Electron Temperature ◽  
Pulse Laser ◽  
Electron Number Density ◽  
Laser Energy ◽  
Pulse Length ◽  
Target Surface ◽  
Spectral Lines ◽  
Stark Broadening ◽  
Number Density ◽  
Electron Number

      The present work investigated the effect of distance from target surface on the parameters of lead plasma excited by 1064nm Q-switched Nd:YAG laser. The excitation was conducted in air, at atmospheric pressure, with pulse length of 5 ns, and at different pulse laser energies. Electron temperature was calculated by Boltzmann plot method based on the PbI emission spectral lines (369.03 nm, 416.98 nm, 523.48, and 561.94 nm). The PbI lines were recorded at different distances from the target surface at laser pulse energies of 260 and 280 mJ. The emission intensity of plasma increased with increasing the lens-to-target distance. The results also detected an increase in electron temperature with increasing the distance between the focal lens and the surface of the target in all laser energies under study. In addition, the electron number density was determined by using the Stark broadening method. The data illustrated that the electron number density was increased with increasing the distance from target surface, reaching the maximum at a distance of 11 cm for all pulse laser energy levels under study.

The diamagnetism of a plasma column

1968 ◽  
Vol 305 (1481) ◽  
pp. 251-257 ◽  
Keyword(s):  
Magnetic Field ◽  
Longitudinal Magnetic Field ◽  
Electron Number Density ◽  
Experimental Measurements ◽  
Number Density ◽  
Electron Number ◽  
Fluid Approximation ◽  
Ion Motion ◽  
The Magnetic Field ◽  
Good Agreement

It has long been known that the positive column of a gas discharge is diamagnetic as a result of the motions of the electrons in a longitudinal magnetic field, but there has been considerable discrepancy between theory and experimental measurements made on low pressure discharges. Calculations are reported here based on a theory in which the ion motion is treated in a fluid approximation for parameters relevant to new experimental measurements. This theory automatically takes into account the effect of the magnetic field on electron temperature and electron number density distribution. It is shown that with this model and sufficient knowledge of the discharge conditions, good agreement can be obtained between theory and experiment for magnetic fields typically less than 300 G.

Measurements of electron number density and plasma temperature using LIBS

2016 ◽  
Author(s):  
Xiao-xia Zhao ◽  
Wen-feng Luo ◽  
Jun-fang He ◽  
Hong-ying Wang ◽  
Sen-lin Yang ◽  
...  
Keyword(s):  
Electron Number Density ◽  
Plasma Temperature ◽  
Number Density ◽  
Electron Number

Spectral studies of nanosecond laser interaction with magnesium sulfate target in air

2013 ◽  
Vol 80 (1) ◽  
pp. 67-80 ◽  
Author(s):  
Muhammad Salik ◽  
Muhammad Hanif ◽  
Jiasheng Wang ◽  
Xi-Qing Zhang
Keyword(s):  
Magnesium Sulfate ◽  
Electron Number Density ◽  
Population Distribution ◽  
Plasma Temperature ◽  
Spectral Lines ◽  
Spectral Studies ◽  
Nanosecond Laser ◽  
Laser Irradiance ◽  
Number Density ◽  
Electron Number

AbstractThe optical emission characterization of the plasma-assisted pulsed laser ablation of the magnesium sulfate target is discussed in this study. The emission spectrum produced by the magnesium sulfate plasma in the wavelength range 200–700 nm has been carefully investigated for different experimental conditions. The spectra analysis was performed by assuming the local thermodynamic equilibrium (LTE) approximation and calculating the plasma temperature with the Boltzmann plot method using neutral Mg spectral lines. The plasma temperature was obtained for different positions along the expansion axis, which allowed obtaining the electron population distribution as a function of the distance from the target. The plasma temperature along the expansion axis allowed evaluating the evolution of the excited states population when the plume expands. Moreover, the Stark broadening method has been employed for electron number density measurements. In this study, the Stark width of the Mg (I) spectral line at 285.21 nm was used. Besides, we have studied the variation of electron temperature (Te) and electron number density (Ne) as a function of laser irradiance.

Effect of Carbon Dioxide and Hydrogen on Nonmetal Emission Intensities in a Helium Microwave-Induced Plasma

1994 ◽  
Vol 48 (4) ◽  
pp. 493-501 ◽  
Author(s):  
Gerald R. Ducatte ◽  
Gary L. Long
Keyword(s):  
Carbon Dioxide ◽  
Electron Number Density ◽  
Number Density ◽  
Specific Detection ◽  
Electron Number ◽  
Microwave Induced Plasma ◽  
Line Intensities ◽  
Ionization Temperature ◽  
Line Selection ◽  
Plasma Excitation

The effect of the introduction of carbon dioxide and hydrogen on nonmetal atomic and ionic line intensities in a helium microwave-induced plasma is discussed. The addition of these gases is found to diminish the excitation properties of the 150-W He plasma. While the plasma excitation temperature, ionization temperature, and electron number density are not significantly affected by the introduction of these gases, decreases in the emission intensities of atomic and ionic analyte transitions of S, P, Cl, Br, and I are noted with the higher-energy ionic transitions being more greatly affected. A correlation between the energy of the excited state and the depressing effect of CO2 is found by examining the signals of atomic and ionic transitions of Cl. The greater signal depression of the higher-energy nonmetal transitions is found to be consistent with charge transfer theory. These findings emphasize the importance of analyte line selection when a He plasma is being employed for the purpose of element-specific detection of nonmetals in supercritical fluid chromatography.

Second harmonic generation using spatially varying static electron number density in a magnetoplasma

1974 ◽  
Vol 12 (3) ◽  
pp. 405-415
Author(s):  
N. B. Chakrabarti ◽  
B. N. Basu
Keyword(s):  
Magnetic Field ◽  
Harmonic Generation ◽  
Electron Number Density ◽  
Second Harmonic ◽  
Plate Boundaries ◽  
Parallel Plates ◽  
Number Density ◽  
Stationary Magnetic Field ◽  
Electron Number ◽  
Static Electron

The Boltzmann transfer equation for electrons in an r.f. discharge plasma immersed in a stationary magnetic field is solved for the various coefficients of the expansion of the distribution function, expanded in a Taylor series in velocity space. Assuming a spatial variation of static electron number density as the mechanism of harmonic generation, explicit expressions for the inner field and the second harmonic current density are derived. The r.f. electric field is assumed to be spatially uniform. The geometry of the plasma considered is that of a rectangular waveguide, but with the parallel plates of one of the two pairs of the metal plate boundaries of the plasma much more closely spaced than those of the other pair. Cyclotron resonance is studied in a situation where the frequency of electron-neutral particle collisions v is much less than the frequency of the r.f. field ω/2π. The resonance effect is obtained, and is found to be more pronounced at the cyclotron frequency ω = ωc than at 2ω = ωc. For v≫ω/2π, the result is not sensitive to the value of the stationary magnetic field, and the resonance effects are absent. The effect of collisions on the process of harmonic generation is also studied.

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