Measurement of electron temperature and number density in shock-tunnel flows. II

AIAA Journal ◽  
1969 ◽  
Vol 7 (11) ◽  
pp. 2099-2104 ◽  
Author(s):  
MICHAEL G. DUNN ◽  
JOHN A. LORDI
Keyword(s):  
Electron Temperature ◽  
Shock Tunnel ◽  
Number Density

scholarly journals Magnetic field effect on laser-induced breakdown spectroscopy and surface modifications of germanium at various fluences

2017 ◽  
Vol 35 (1) ◽  
pp. 159-169 ◽  
Author(s):  
H. Iftikhar ◽  
S. Bashir ◽  
A. Dawood ◽  
M. Akram ◽  
A. Hayat ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Temperature ◽  
Surface Modifications ◽  
Laser Induced Breakdown Spectroscopy ◽  
Excitation Temperature ◽  
Number Density ◽  
Plasma Parameters ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
The Magnetic Field

AbstractThe effect of the transverse magnetic field on laser-induced breakdown spectroscopy and surface modifications of germanium (Ge) has been investigated at various fluences. Ge targets were exposed to Nd: YAG laser pulses (1064 nm, 10 ns, 1 Hz) at different fluences ranging from 3 to 25.6 J/cm2 to generate Ge plasma under argon environment at a pressure of 50 Torr. The magnetic field of strength 0.45 Tesla perpendicular to the direction of plasma expansion was employed by using two permanent magnets. The emission spectra of laser-induced Ge plasma was detected by the laser-induced breakdown spectroscopy system. The electron temperature and number density of Ge plasma are evaluated by using the Boltzmann plot and stark broadening methods, respectively. The variations in emission intensity, electron temperature (Te), and number density (ne) of Germanium plasma are explored at various fluences, with and without employment of the magnetic field. It is observed that the magnetic field is responsible for significant enhancement of both excitation temperature and number density at all fluences. It is revealed that an excitation temperature increases from Te,max,without B = 16,190 to Te,max,with B = 20,123 K. Similarly, the two times enhancement in the electron density is observed from ne,max,without B = 2 × 1018 to ne,max,with B = 4 × 1018 cm−3. The overall enhancement in Ge plasma parameters in the presence of the magnetic field is attributed to the Joule heating effect and adiabatic compression. With increasing fluence both plasma parameters increase and achieve their maxima at a fluence of 12.8 J/cm2 and then decrease. In order to correlate the plasma parameters with surface modification, scanning electron microscope analysis of irradiated Ge was performed. Droplets and cones are formed for both cases. However, the growth of ridges and distinctness of features is more pronounced in case of the absence of the magnetic field; whereas surface structures become more diffusive in the presence of the magnetic field.

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

FREE-FALL DIFFUSION IN A DISCHARGE AFTERGLOW

1966 ◽  
Vol 44 (11) ◽  
pp. 2615-2630 ◽  
Author(s):  
B. C. Gregory
Keyword(s):  
Electron Temperature ◽  
Free Fall ◽  
Mercury Vapor ◽  
Mean Free Path ◽  
Experimental Results ◽  
Cavity Method ◽  
Number Density ◽  
Langmuir Probes ◽  
Average Electron ◽  
Good Agreement

The afterglow decay of the number density and electron temperature of a plasma in which collisions between electrons and molecules are rare is studied both theoretically and experimentally. The theoretical approach, using the first three moment equations solved in a one-dimensional geometry, predicts non-exponential decay profiles in time for both density and temperature. Experimental results are obtained using a cylindrical mercury vapor discharge tube at pressures where the mean free path of the electrons is much larger than the transverse dimensions of the tube. The average electron number density is measured by a surface-wave cavity method and the electron temperature by means of Langmuir probes. The theoretical and experimental results are in good agreement, especially for the density decay.

Sign in / Sign up

Export Citation Format

Share Document