COLD PLASMA INJECTION ON VLF WAVE MODE FOR RELATIVISTIC MAGNETOPLASMA WITH A.C. ELECTRIC FIELD

2008 ◽  
Vol 2 ◽  
pp. 217-232 ◽  
Author(s):  
Rama Shankar Pandey ◽  
R. P. Pandey
Keyword(s):  
Electric Field ◽  
Cold Plasma ◽  
Wave Mode ◽  
Plasma Injection

Plane Wave Interaction with an Inhomogeneous Warm Plasma Column

1971 ◽  
Vol 49 (20) ◽  
pp. 2578-2588 ◽  
Author(s):  
Kanwal J. Parbhakar ◽  
Brian C. Gregory
Keyword(s):  
Electric Field ◽  
Electron Temperature ◽  
Plasma Column ◽  
Cold Plasma ◽  
Plane Electromagnetic Wave ◽  
Wave Interaction ◽  
Radial Electric Field ◽  
Main Resonance ◽  
At Resonance ◽  
Warm Plasma

The interaction of a plane electromagnetic wave with an inhomogeneous warm plasma column is studied as a boundary value problem using a wave matching method. The plasma is characterized by a uniform electron temperature T and a parabolic density distribution N00 (1 − αr2/α2), where N00 is the central line density, α the inhomogeneity parameter, and a the column radius. The coupled Maxwell's and first two moment equations, assuming scalar pressure, are solved numerically without the quasi-static assumption. The resonances cannot be characterized by a single parameter; the effects of α, T, and N00 are studied separately. The resonances are located by noting that the magnitude of the scattering coefficient is unity (for a unit amplitude incident wave) at resonance. The maxima in the scattering are associated with the maxima in the coupling.It is found that the dielectric or the main resonance is a reasonably good radiator, while the plasma wave resonances (Tonks–Dattner resonances) are rather poor radiators. A detailed analysis of the radial electric field inside the plasma indicates that the main resonance is essentially a cold plasma resonance. As for the resonant frequencies, our results are in good agreement with those of Parker, Nickel, and Gould.The radial electric field at resonance inside the plasma is very sensitive to electron temperature.For the main resonance the field distribution at low electron temperature approaches that of a uniform cold plasma at resonance.

scholarly journals Electric field measurements on Cluster: comparing the double-probe and electron drift techniques

2006 ◽  
Vol 24 (1) ◽  
pp. 275-289 ◽  
Author(s):  
A. I. Eriksson ◽  
M. André ◽  
B. Klecker ◽  
H. Laakso ◽  
P.-A. Lindqvist ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Cold Plasma ◽  
Field Measurements ◽  
Low Energy ◽  
Electron Drift ◽  
Double Probe ◽  
Flow Energy ◽  
Potential Control ◽  
Spacecraft Potential

Abstract. The four Cluster satellites each carry two instruments designed for measuring the electric field: a double-probe instrument (EFW) and an electron drift instrument (EDI). We compare data from the two instruments in a representative sample of plasma regions. The complementary merits and weaknesses of the two techniques are illustrated. EDI operations are confined to regions of magnetic fields above 30 nT and where wave activity and keV electron fluxes are not too high, while EFW can provide data everywhere, and can go far higher in sampling frequency than EDI. On the other hand, the EDI technique is immune to variations in the low energy plasma, while EFW sometimes detects significant nongeophysical electric fields, particularly in regions with drifting plasma, with ion energy (in eV) below the spacecraft potential (in volts). We show that the polar cap is a particularly intricate region for the double-probe technique, where large nongeophysical fields regularly contaminate EFW measurments of the DC electric field. We present a model explaining this in terms of enhanced cold plasma wake effects appearing when the ion flow energy is higher than the thermal energy but below the spacecraft potential multiplied by the ion charge. We suggest that these conditions, which are typical of the polar wind and occur sporadically in other regions containing a significant low energy ion population, cause a large cold plasma wake behind the spacecraft, resulting in spurious electric fields in EFW data. This interpretation is supported by an analysis of the direction of the spurious electric field, and by showing that use of active potential control alleviates the situation.

Effect of Horizontal Alternating Current Electric Field on the Stability of Natural Convection in a Dielectric Fluid Saturated Vertical Porous Layer

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
B. M. Shankar ◽  
Jai Kumar ◽  
I. S. Shivakumara
Keyword(s):  
Natural Convection ◽  
Electric Field ◽  
Prandtl Number ◽  
Traveling Wave ◽  
Effective Viscosity ◽  
Darcy Number ◽  
Wave Mode ◽  
Dielectric Fluid ◽  
Fluid Viscosity ◽  
The Stability

The stability of natural convection in a dielectric fluid-saturated vertical porous layer in the presence of a uniform horizontal AC electric field is investigated. The flow in the porous medium is governed by Brinkman–Wooding-extended-Darcy equation with fluid viscosity different from effective viscosity. The resulting generalized eigenvalue problem is solved numerically using the Chebyshev collocation method. The critical Grashof number Gc, the critical wave number ac, and the critical wave speed cc are computed for a wide range of Prandtl number Pr, Darcy number Da, the ratio of effective viscosity to the fluid viscosity Λ, and AC electric Rayleigh number Rea. Interestingly, the value of Prandtl number at which the transition from stationary to traveling-wave mode takes place is found to be independent of Rea. The interconnectedness of the Darcy number and the Prandtl number on the nature of modes of instability is clearly delineated and found that increasing in Da and Rea is to destabilize the system. The ratio of viscosities Λ shows stabilizing effect on the system at the stationary mode, but to the contrary, it exhibits a dual behavior once the instability is via traveling-wave mode. Besides, the value of Pr at which transition occurs from stationary to traveling-wave mode instability increases with decreasing Λ. The behavior of secondary flows is discussed in detail for values of physical parameters at which transition from stationary to traveling-wave mode takes place.

Scattering Characteristics of Stratified Double Negative Stacks Using the Frequency Dispersive Cold Plasma Medium

2007 ◽  
Vol 62 (5-6) ◽  
pp. 247-253 ◽  
Author(s):  
Cumali Sabah ◽  
Savas Uckun
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Electric Field ◽  
Cold Plasma ◽  
Plane Electromagnetic Wave ◽  
Numerical Results ◽  
Double Negative ◽  
Plasma Medium ◽  
Double Positive ◽  
Perpendicular Polarization

We present the wave propagation through stratified double negative stacks to illustrate the scattering characteristics of their structure. The double negative stacks are modeled by using the hypothetical non-dispersive and the frequency dispersive cold plasma media. The stacks are embedded between two double positive media and the incident electric field is assumed a plane electromagnetic wave with any arbitrary polarization. By imposing the boundary conditions, the relations between the fields inside and outside the stacks can be written in a matrix form. Using this transfer matrix, the incident, reflected, and transmitted powers are derived. The variations of the powers for the stratified double negative stacks using the frequency dispersive cold plasma medium have not been investigated yet, in detail. Thus, their characteristics for the perpendicular polarization is computed and presented in numerical results with the emphasis on the plasma frequencies. It is seen from the numerical results that the stratified double negative stacks can be used as electromagnetic filters at some frequency bands.

scholarly journals Hydrophobic Modification of Biopolymer Aerogels by Cold Plasma Coating

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 3000
Author(s):  
Baldur Schroeter ◽  
Isabella Jung ◽  
Katharina Bauer ◽  
Pavel Gurikov ◽  
Irina Smirnova
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Cold Plasma ◽  
Plasma Coating ◽  
Wave Mode ◽  
Protein Isolate ◽  
Contact Angles ◽  
Water Contact ◽  
The Individual

The aim of this work was to evaluate the potential of cold plasma polymerization as a simple, fast and versatile technique for deposition of protective hydrophobic and oleophobic polymer layers on hydrophilic biopolymer aerogels. Polymerization of different fluorinated monomers (octafluorocyclobutane C4F8 and perfluoro-acrylates PFAC-6 and PFAC-8) on aerogel monoliths derived from alginate, cellulose, whey protein isolate (WPI) and potato protein isolate (PPI) resulted in fast and significant surface hydrophobization after short process times of 5 min and led to superhydrophobic surfaces with static water contact angles up to 154° after application of poly-C4F8 coatings. Simultaneous introduction of hydro- and oleophobicity was possible by deposition of perfluoro-acrylates. While the porous structure of aerogels stayed intact during the process, polymerization inside the aerogels pores led to the generation of new porous moieties and resulted therefore in significant increase in the specific surface area. The magnitude of the effect depended on the individual process settings and on the overall porosity of the substrates. A maximization of specific surface area increase (+179 m2/g) was obtained by applying a pulsed wave mode in the C4F8-coating of alginate aerogels.

scholarly journals Novel UHF RFID Near-Field Reader Antenna with Uniform Vertical Electric Field Distribution

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yanbin Chen ◽  
Xiaojuan Ren ◽  
Jimin Zhao ◽  
Xin Chen ◽  
Yuan Yao ◽  
...  
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
Electric Field Distribution ◽  
Near Field ◽  
Impedance Matching ◽  
Wave Mode ◽  
Uhf Rfid ◽  
Microstrip Lines ◽  
Vertical Electric Field ◽  
Reader Antenna

This paper presents two novel UHF RFID near-field reader antennas with uniform vertical electric field distribution. The two antennas have the following common characteristics. First, the radiating parts of the two antennas are simulated and fabricated by the microstrip lines and work using the leakage wave principle of microstrip lines. Second, the end of microstrip lines match the load to form a traveling wave mode of operation, so the two antennas have broadband characteristics. Third, both antennas are fed in a coaxial manner at the center of the antenna. The simulation and measurement results can show that the proposed three-branch antenna and four-branch antenna achieve good impedance matching in the range of 883–960 MHz and 870–960 MHz, respectively, and achieve uniform distribution of the vertical electric field component in a certain area. The reading areas of the three-branch antenna and the four-branch antenna are 70 mm × 70 mm × 90 mm and 100 mm × 100 mm × 120 mm (length × width × height), respectively. Due to the introduction of the ground plate, the antenna gain is low, which meets the design requirements of near-field antennas.

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