scholarly journals Temporal survey of electron number density and electron temperature in the exhaust of a megawatt MPD-arc thruster

1972 ◽  
Author(s):  
C. MICHELS ◽  
J. ROSE ◽  
D. SIGMAN
Keyword(s):  
Electron Temperature ◽  
Electron Number Density ◽  
Number Density ◽  
Electron Number

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.

Electron temperature and electron number density measurements in laser ablation Z-pinch experiments of Al2O3

2019 ◽  
Vol 26 (8) ◽  
pp. 083506
Author(s):  
E. C. Dutra ◽  
J. A. Koch ◽  
R. Presura ◽  
P. Wiewior ◽  
A. M. Covington
Keyword(s):  
Laser Ablation ◽  
Electron Temperature ◽  
Electron Number Density ◽  
Number Density ◽  
Electron Number ◽  
Density Measurements ◽  
Z Pinch

scholarly journals Spectroscopic Characterization of Laser Ablated Germanium Plasma

2021 ◽  
Vol 22 (2) ◽  
pp. 396-403
Author(s):  
Muhammad Ashraf ◽  
Nek Muhammad Shaikh ◽  
Tasneem Zehra ◽  
Ghulam Abbas Kandhro ◽  
Ghulam Murtaza
Keyword(s):  
Electron Temperature ◽  
Electron Number Density ◽  
Plasma Plume ◽  
Research Work ◽  
Spectroscopic Characterization ◽  
Laser Irradiance ◽  
Number Density ◽  
Electron Number ◽  
Boltzmann Plot ◽  
Detector Position

In the present study, the germanium (Ge) sample has been studied by laser induced breakdown spectroscopy which leads to the formation of plasma plume in the air. This research work comprises on pure Ge sample, and it has been studied using laser irradiance 1.831011 watt.cm-2 and Q-Switched Nd:YAG laser pulse (λ ~ 1064 nm wavelength and  ~ 5 ns pulse width). The spatially resolved plasma plume parameters are investigated, such as variation of electron temperature Te and electron number density ne as a function of detector position. These parameters show variation in the plasma plume and yield electron temperature Te from 12340 to 7640 ± 1200 K. Whereas electron number density ne varies from 3.61017 to 1.601017 cm-3 with the change in detector position is moving away from plasma plume from 0 to 3 mm. The results show that electron temperature Te and electron number density ne are estimated from the Boltzmann plot method and by using Lorentzian function at spectral line using FWHM full width at half maximum at 265.11 nm (4p5s 3 p2 → 4p 2 3 p2) wavelength of Ge (I) line, respectively.

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.

TESTING OF NICKEL-CHROME ALLOY AS A TIP MATERIAL FOR MULTI-TIP LANGMUIR PROBES

2014 ◽  
Vol 21 (04) ◽  
pp. 1450056 ◽  
Author(s):  
MUHAMMAD YASIN NAZ ◽  
SHAZIA SHUKRULLAH ◽  
ABDUL GHAFFAR ◽  
IMRAN SHAKIR ◽  
SAMI ULLAH ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Inductively Coupled Plasma ◽  
Electron Number Density ◽  
Diagnostic System ◽  
Input Power ◽  
Repeated Measurements ◽  
Gas Pressure ◽  
Rf Discharge ◽  
Number Density ◽  
Electron Number

The electrostatic probes are considered to be the most powerful and experimentally simplest technique for plasma characterization. The objective of the work was to test the nickel-chrome alloy as probe tip material for characterization of RF discharge plasmas. In order to meet the objective, a triple Langmuir probe diagnostic system and associated driving circuit was designed and tested in inductively coupled plasma (ICP) generated by a 13.56 MHz radio frequency (RF) source. Using this probe diagnostic, the electron temperature, electron number density and ion saturation current were measured as a function of input RF power and filling gas pressure. An increasing trend was noticed in electron temperature and electron number density with input power whilst a decreasing trend was evident in these parameters for increasing nitrogen gas pressure. The overall variations in electron temperature and electron number density after repeated measurements were ranging from 5% to 12% and 3% to 13%, respectively.

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