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 Spatial confinement effects employed by metallic blocker and Ar gas pressures on laser-induced breakdown spectroscopy and surface modifications of laser-irradiated Mg

2017 ◽  
Vol 35 (2) ◽  
pp. 313-325 ◽  
Author(s):  
A. Hayat ◽  
S. Bashir ◽  
M. S. Rafique ◽  
R. Ahmed ◽  
M. Akram ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Electron Number Density ◽  
Number Density ◽  
Confinement Effects ◽  
Electron Number ◽  
Plasma Parameters ◽  
Spatial Confinement ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Ar Gas

AbstractSpatial confinement effects on plasma parameters and surface morphology of laser-ablated Mg are studied by introducing a metallic blocker as well as argon (Ar) gas at different pressures. Nd: YAG laser at various fluences ranging from 7 to 28 J/cm2 was employed to generate Mg plasma. Confinement effects offered by metallic blocker are investigated by placing the blocker at different distances of 6, 8, and 10 mm from the target surface; whereas spatial confinement offered by environmental gas is explored under four different pressures of 5, 10, 20, and 50 Torr. Laser-induced breakdown spectroscopy analysis revealed that both plasma parameters, that is, excitation temperature and electron number density initially are strongly dependent upon both pressures of environmental gases and distances of blockers. The maximum electron temperature of Mg plasma is achieved at Ar gas pressure of 20 Torr, whereas maximum electron number density is achieved at 50 Torr. It is also observed that spatial confinement offered by metallic blocker is responsible for the significant enhancement of both electron temperature and electron number density of Mg plasma. Maximum values of electron temperature and electron number density without blocker are 8335 K and 2.4 × 1016 cm−3, respectively, whereas these values are enhanced to 12,200 K and 4 × 1016 cm−3 in the presence of blocker. Physical mechanisms responsible for the enhancement of Mg plasma parameters are plasma compression, confinement and pronounced collisional excitations due to reflection of shock waves. Scanning electron microscope analysis was performed to explore the surface morphology of laser-ablated Mg. It reveals the formation of ripples and channels that become more distinct in the presence of blocker due to plasma confinement. The optimum combination of blocker distance, fluence and Ar pressure can identify the suitable conditions for defining the role of plasma parameters for surface structuring.

Spectroscopic Method for Measurement of Electron Number Density on DC Arc Plasma Jet Under Low Pressure Conditions

2015 ◽  
Vol 36 (1) ◽  
pp. 88-93
Author(s):  
孙成琪 SUN Cheng-qi ◽  
高阳 GAO Yang ◽  
杨德明 YANG De-ming ◽  
傅迎庆 FU Ying-qing
Keyword(s):  
Electron Number Density ◽  
Spectroscopic Method ◽  
Plasma Jet ◽  
Low Pressure ◽  
Arc Plasma ◽  
Number Density ◽  
Electron Number ◽  
Dc Arc

scholarly journals Evaluation of electron temperature and electron density of laser-ablated Zr plasma by Langmuir probe characterization and its correlation with surface modifications

2020 ◽  
Vol 38 (2) ◽  
pp. 84-93
Author(s):  
Zulaikha Irfan ◽  
Shazia Bashir ◽  
Shariqa Hassan Butt ◽  
Asma Hayat ◽  
Rana Ayub ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Langmuir Probe ◽  
Electron Number Density ◽  
High Vacuum ◽  
Debye Length ◽  
Laser Irradiance ◽  
Thermal Velocity ◽  
Number Density ◽  
Electron Number ◽  
Plasma Parameters

AbstractThe plasma parameters of laser-ablated Zirconium (Zr) using a Langmuir probe technique have been investigated by employing a Q-switched Nd:YAG laser (532 nm, 6 ns) at various irradiances ranging from 8.6 to 15.5 GW/cm2. All the measurements have been performed under an ultra-high vacuum condition while keeping the probe at a fixed distance of 4 mm from the target. By varying the biasing voltages from 1 to 75 V, the corresponding values of electric currents are measured by the probe on the oscilloscope. Laser-induced Zr plasma parameters such as electron temperature, electron number density, plasma potential, Debye length, and thermal velocity have been evaluated from I–V characteristic curves of Langmuir probe data. It is found that both the electron temperature and thermal velocity of Zr plasma reveal an increasing trend from 18 to 41 eV and 2.8 × 108 to 4.3 × 108 cm/s, respectively, with increasing laser irradiance which is attributed to more energy deposition and enhanced ablation rate. However, the electron number density of Zr plasma exhibits a non-significant increase from 6.5 × 1014 to 6.7 × 1014 cm−3 with increasing irradiance from 8.6 to 10.9 GW/cm2. A further increase in irradiance from 12 to 15.5 GW/cm2 causes a reduction in the number density of Zr plasma from 6.1 × 1014 to 5.6 × 1014 cm−3 which is attributed to the formation of thick sheath, ambipolar electric field, and laser-supported detonation waves (Shock front). Scanning electron microscope analysis has been performed to reveal the surface morphology of irradiated Zr. It reveals the formation of cracks, ridges, cones, and grains. It was observed at high irradiances the ridges are vanished, whereas cones and cracks are dominant features. By controlling plasma parameters, surface structuring of materials can be controlled, which has a vast range of applications in the industry and medicine.

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.

scholarly journals Effect of nature and pressure of ambient environments on the surface morphology, plasma parameters, hardness, and corrosion resistance of laser-irradiated Mg-alloy

2015 ◽  
Vol 33 (2) ◽  
pp. 315-330 ◽  
Author(s):  
Asadullah Dawood ◽  
Shazia Bashir ◽  
Mahreen Akram ◽  
Asma Hayat ◽  
Sajjad Ahmed ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Surface Morphology ◽  
Electron Temperature ◽  
Electron Number Density ◽  
Mg Alloy ◽  
Number Density ◽  
Electron Number ◽  
Plasma Parameters ◽  
Hardness Tester ◽  
Breakdown Spectroscopy

AbstractThe influence of nature and pressure of ambient environment on the surface modification, plasma parameters, hardness, and corrosion resistance of Mg-alloy has been investigated. Nd: YAG laser (1064 nm, 10 ns, 25 mJ) at a fluence of 1.3 J cm−2 has been employed as an irradiation source. Targets of Mg-alloy were exposed in the ambient environments of argon (Ar), neon (Ne), and helium (He) at pressures ranging from 5 to 760 Torr. Scanning electron microscope has been employed to investigate the surface morphology of the irradiated targets. It reveals the formation of cavities, cones, droplets, ripples, and islands on the surface of the irradiated sample. Laser-induced breakdown spectroscopy technique was employed to measure electron temperature (Te) and electron number density (Ne) of Mg-alloy. The value of electron temperature ranges from 6628 to 12,855 K, whereas the value of electron number density varies from 5.4 × 1017 to 19.2 × 1017 cm−3. The maximum Te and Ne are observed in Ar and minimum in case of He. It was also revealed that both the surface morphology and plasma parameters are strongly dependent upon nature and pressure of environmental gases. The maxima of Te is achieved at a pressure of 10 Torr for all the three ambient environments that is, Ar, Ne, and He; whereas maxima of Ne is achieved at different pressures, that is, at 760 Torr for Ar, at 200 Torr for Ne, and at 50 Torr for He. The hardness and corrosion resistance of irradiated Mg-alloy have been explored using Vickers Micro-hardness tester and Potentio-dynamic polarization technique, respectively. It was investigated that as compared with un-irradiated target, the hardness as well as corrosion resistance of the laser-irradiated target has been increased significantly in all environments. Plasma parameters, mechanical, and electrical properties of laser-irradiated Mg-alloy have been correlated with induced surface modifications and are strongly influenced by environmental conditions.

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.

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