Kinetic theory of high-frequency and low-pressure atomic discharges

1997 ◽  
Vol 58 (1) ◽  
pp. 123-143
Author(s):  
N. PEYRAUD-CUENCA ◽  
P. FAUCHER
Keyword(s):  
High Pressure ◽  
Kinetic Theory ◽  
High Frequency ◽  
Low Pressure ◽  
Plasma Phys ◽  
Numerical Results ◽  
Very High Frequency ◽  
Argon Discharge ◽  
Very High ◽  
Good Agreement

This paper gives a complete kinetic theory of atomic discharges whatever their parameters. Very high-frequency discharges and high-pressure continuous discharges were studied in an earlier paper by the same authors [J. Plasma Phys. 54, 309 (1995)]; in the present paper we study low-pressure continuous discharges or high-frequency discharges whose parameters satisfy different conditions and therefore cannot be described by the earlier model. Analytical results are applied to a high-frequency argon discharge and to a low-pressure continuous argon discharge. The results are in good agreement with the numerical results of Ferreira and co-workers.

Kinetic theory of very high-frequency and high-pressure continuous atomic discharges

1995 ◽  
Vol 54 (3) ◽  
pp. 309-332
Author(s):  
N. Peyraud-Cuenca ◽  
P. Faucher
Keyword(s):  
High Pressure ◽  
Electric Field ◽  
High Frequency ◽  
Electron Distribution Function ◽  
Very High Frequency ◽  
High Frequency Electric Field ◽  
Analytical Approaches ◽  
Very High ◽  
Stationary Electron ◽  
Good Agreement

We derive the analytical solution of the Boltzmann equation for the stationary electron distribution function that is reached in a plasma generated on the application of a uniform very high-frequency electric field in an atomic gas. The theory includes all excitation transitions: ionization and electronic transitions. The analytic solution is also extended to continuous discharges with low electric field or high pressure in the gas. Then the electron rate coefficient for excitation of the first state (which is the most significant) is calculated analytically. We apply the results to the modelling of very high-frequency argon discharges and to high-pressure continuous discharges in argon and in sodium. The results are compared with numerical results of Ferreira and co-workers for argon and of LaVerne for sodium: in both cases we find good agreement between numerical and analytical approaches.

scholarly journals Low-Profile Spidron Fractal Dipole Antenna with a Ferrite-Loaded Artificial Magnetic Conductor for Manpack Applications

2020 ◽  
Vol 10 (24) ◽  
pp. 8843
Author(s):  
Oh Heon Kwon ◽  
Keum Cheol Hwang
Keyword(s):  
High Frequency ◽  
Dipole Antenna ◽  
Magnetic Conductor ◽  
Very High Frequency ◽  
Artificial Magnetic Conductor ◽  
Received Power ◽  
Low Profile ◽  
Profile Characteristics ◽  
Very High ◽  
Good Agreement

In this paper, a Spidron fractal dipole antenna with a ferrite-loaded artificial magnetic conductor (AMC) is presented. By applying ferrite composed of nickel–zinc with a high permeability value, a compact AMC that operates in the broadband frequency range within the high-frequency/very-high-frequency/ultra-high-frequency (HF/VHF/UHF) bands was designed. A Spidron fractal-shaped dipole antenna with a quasi-self-complementary structure was designed and combined with a miniaturized ferrite-loaded AMC. This allowed the designed AMC-integrated dipole antenna to operate in a wide frequency band, covering the HF/VHF/UHF bands, with low-profile characteristics. A prototype of the proposed Spidron fractal dipole antenna with the AMC was manufactured and measured and found to meet low VSWR (voltage standing wave radios) specifications of <3.5 within the 20–500 MHz bandwidth range. The simulated and measured results are in good agreement. The size of the Spidron fractal dipole antenna with the AMC is 0.03×0.026×0.001λ3 relative to the wavelength of the lowest operating frequency. The received power of the Spidron fractal dipole antenna with the AMC was also measured when it was applied to relatively small applications, such as a manpack in this case.

Nanocrystalline Silicon Films Grown at High Pressure in Very High Frequency Plasma Enhanced Chemical Vapor Deposition System

2010 ◽  
Vol 663-665 ◽  
pp. 1171-1174 ◽  
Author(s):  
Yan Qing Guo ◽  
Rui Huang ◽  
Jie Song ◽  
Xiang Wang ◽  
Yi Xiong Zhang
Keyword(s):  
High Pressure ◽  
Vapor Deposition ◽  
High Frequency ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Silicon Films ◽  
Very High Frequency ◽  
Hydrogen Dilution ◽  
Very High ◽  
Nanocrystalline Silicon Films

Nanocrystalline silicon films have been fabricated from SiH4 diluted with H2 in very high frequency (40.68 MHz) plasma enhanced chemical vapor deposition system at low temperatures (250oC). The influence of pressure on the structural properties of nanocrystalline silicon films has been investigated. The experimental results reveal that a very high hydrogen dilution is needed to crystallize the film grown at high pressure. If the hydrogen dilution is not high enough, the film could also be crystallized through lowering the pressure. Furthermore, the crystallinity and grain size increase with decreasing the pressure. These results could be attributed to the increase of ion bombardment energy and the higher atomic hydrogen flux toward the growing film surface at lower pressures.

Monocrystal elastic constants of orthotropic Y1Ba2Cu3O7: An estimate

1991 ◽  
Vol 6 (11) ◽  
pp. 2253-2255 ◽  
Author(s):  
Hassel Ledbetter ◽  
Ming Lei
Keyword(s):  
Elastic Constants ◽  
High Frequency ◽  
Stiffness Matrix ◽  
Phonon Dispersion ◽  
Elastic Stiffness ◽  
Tetragonal Symmetry ◽  
Very High Frequency ◽  
Analysis Theory ◽  
Very High ◽  
Good Agreement

For Y1Ba2Cu3O7, using only reported monocrystal measurements and some analysis–theory, we estimated the complete nine-component orthotropic-symmetry elastic-stiffness matrix, the Voigt Cij matrix. Comparison with very-high-frequency tetragonal-symmetry phonon-dispersion results shows good agreement (9% on average), except for C12.

Characteristics of Very High Frequency Plasma Produced with Ladder-Shaped Electrode at High Pressure

2004 ◽  
Vol 44 (1) ◽  
pp. L38-L40 ◽  
Author(s):  
Hiromu Takatsuka ◽  
Yasuhiro Yamauchi ◽  
Yoshiaki Takeuchi ◽  
Hiroshi Mashima ◽  
Hideaki Yamashita ◽  
...  
Keyword(s):  
High Pressure ◽  
High Frequency ◽  
Very High Frequency ◽  
High Frequency Plasma ◽  
Frequency Plasma ◽  
Very High
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