Radiation of an Electric Dipole from a Small Plasma Spheroid

Bichutskaya, T. I.; Makarov, G. I.

doi:10.1023/b:raqe.0000029589.54371.24

Cited by 4 publications

(14 citation statements)

References 3 publications

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“…(12) as a function of b/a become less steep. The similar dependence of the resonant frequency on the ratio b/a for the plasma spheroid without a cavity [6] monotonically increases.…”

Section: Figmentioning

confidence: 61%

“…(10) reduces to the transmission coefficient for the plasma-filled sphere with a cavity. For α = 0, transmission coefficient (10) does not reduce to the corresponding quantity for the plasma spheroid without a cavity [6]. This case requiring separate consideration similar to [12] is omitted here.…”

Section: Figmentioning

confidence: 93%

“…The presence of a continuous isotropic plasma region [1][2][3][4][5][6] around a source leads to an increase in the field in an outer vacuum region by 1-2 orders of magnitude compared with the case where the plasma region is absent, provided the amplitude of the feeding current at a single resonant frequency determined by the plasma-region shape remains intact. The presence of an external magnetic field [7][8][9][10] or allowance for an ion sheath [11,12] around the source in plasma leads to splitting the resonant frequency into two frequencies and can enhance this effect.…”

Section: Figmentioning

confidence: 99%

“…According to [15], in the quasi-static approximation (d 1 |ε 1 | 1), as in [6], it is possible to single out the main coefficient with l = 1 among the coefficients A l , so that we can restrict ourselves to one spheroidal wave with l = 1 in Eq. (1).…”

Section: Figmentioning

confidence: 99%

“…The influence of the cavity size on the field enhancement in an outer vacuum region is analyzed as a function of the curvature of the plasma-spheroid surface. The results are compared with the case of a sphere with similar cavity.This paper is the continuation of works [1][2][3][4][5][6][7][8][9][10][11][12] devoted to studying the influence of small plasma regions around a dipole source on its radiation into an outer vacuum region. Such studies are aimed at analyzing possibilities of enhancement of radiation from a small plasma region.…”

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confidence: 99%

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Field of an Electric Dipole Surrounded by a Small Plasma Spheroid with a Cavity

Bichutskaya

Makarov

2005

Radiophys Quantum Electron

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We obtain and analyze a solution of the boundary-value problem for the field of an electric dipole centered in a vacuum cavity inside a small plasma spheroid. The influence of the cavity size on the field enhancement in an outer vacuum region is analyzed as a function of the curvature of the plasma-spheroid surface. The results are compared with the case of a sphere with similar cavity.This paper is the continuation of works [1][2][3][4][5][6][7][8][9][10][11][12] devoted to studying the influence of small plasma regions around a dipole source on its radiation into an outer vacuum region. Such studies are aimed at analyzing possibilities of enhancement of radiation from a small plasma region. The studies were performed for plasma regions of different shapes ranging from a circular or elliptic cylinder to a sphere and a prolate or oblate spheroid. The effect of the shape of a plasma Fig. 1.region was revealed and some estimates of the influence of an ion sheath formed around sources in plasmas [13,14] and modeled by a vacuum sheath were performed. The presence of a continuous isotropic plasma region [1-6] around a source leads to an increase in the field in an outer vacuum region by 1-2 orders of magnitude compared with the case where the plasma region is absent, provided the amplitude of the feeding current at a single resonant frequency determined by the plasma-region shape remains intact. The presence of an external magnetic field [7-10] or allowance for an ion sheath [11,12] around the source in plasma leads to splitting the resonant frequency into two frequencies and can enhance this effect.In this paper, we study the influence of the ion sheath on the far-zone field of a source surrounded by a plasma spheroid of small electrical sizes k p a 1, where k p = ω p /c, ω p is the electron plasma frequency, a is the major semiaxis of the spheroid, and c is the speed of light in free space.We consider the radiation field of an electric dipole centered in a small prolate plasma spheroid with the major and minor semiaxes a and b, respectively (Fig. 1), and the eccentricity e. The dipole is aligned with the symmetry axis of the spheroid. The ion sheath around the source is modeled by a small vacuum spheroid with the semiaxes a 1 and b 1 and the same eccentricity e. The model of an inner cavity with a sharp boundary is simplified and neglects the influence of the region with the relative dielectric permittivity ε = 0. We plan to consider this influence in future works. The distance 2d 1 between the foci of the inner spheroid is assumed to vary from the minimum value determined by the dipole length to the value almost * Yulia.Afanasyeva@paloma.spbu.ru

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“…(12) as a function of b/a become less steep. The similar dependence of the resonant frequency on the ratio b/a for the plasma spheroid without a cavity [6] monotonically increases.…”

Section: Figmentioning

confidence: 61%

Section: Figmentioning

confidence: 93%

Section: Figmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

mentioning

confidence: 99%

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Field of an Electric Dipole Surrounded by a Small Plasma Spheroid with a Cavity

Bichutskaya

Makarov

2005

Radiophys Quantum Electron

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Radiation from a small spheroidal antenna with plasma shell

Bichutskaya

Makarov

2006

Radiophys Quantum Electron

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We construct and study an analytical solution of the boundary-value problem for the radiation field of a small spheroidal antenna located in free space and surrounded by a thin shell of cold homogeneous isotropic plasma. Conditions for a resonant increase in the field in free space as a function of the plasma-shell thickness with the variation in the spheroidal-antenna shape are studied. It is shown that the plasma shell has the largest effect on the radiation field of a strongly prolate spheroidal antenna.The earlier studies of the radiation field of spheroidal antennas [1-4], both without a shell and surrounded by a dielectric or plasma shell, insufficiently covered the question of influence of the shape variation of a spheroidal source on the field in free space. The answer to this question can be found for spheroidal antennas of small electrical sizes (ka 0 1, where k is the wave nunmber in free space and a 0 is the major semiaxis of a spheroidal antenna), for which the solution can be found in analytical form. In this paper, we construct an analytical solution for the radiation field of small spheroidal antennas, both prolate and oblate, covered by a thin plasma shell of spheroidal shape with k |ε|a 1, where ε is the dielectric permittivity of the plasma and a is the major semiaxis of a spheroidal plasma shell, and study the field characteristics in the far zone of the source as functions of the variable shape of a spheroidal antenna and the relative thickness of the plasma shell.The influence of the small plasma shell of a point source (electric dipole) studied earlier [5-8] using the models of a plasma shell in the form of a circular or elliptical cylinder, as well as a plasma sphere or spheroid, showed that because of the frequency dispersion of the plasma, there exist such resonant frequencies at which the radiation-field amplitude in free space turns out to be one or two orders of magnitude higher than at the neighboring frequencies for the same current at the source input. The resonant frequency and amplitude of the resonant field considerably depend on the shape of the plasma shell, so that for the oblate shape of a spheroid or the elliptical cross section of a cylinder, the amplitude of the resonant field is maximum. We will call a resonant increase in the field of a point source with fixed current and small plasma shell the current resonance as distinct from the voltage resonance considered in the present paper for a plasma-coated spheroidal antenna with fixed voltage in the gap.Consider a metal antenna located in an unbounded medium with dielectric permittivity ε 3 and having the form of a spheroid with interfocal distance 2d 0 , major and minor semiaxes a 0 and b 0 , respectively, and a plasma shell bounded by the surface of a spheroid with interfocal distance 2d and semiaxes a and b. We assume that the eccentricities e of the external and internal spheroids having a common origin of coordinates (see Fig. 1) are identical. In the further analysis, the shape of the spheroids will vary from strongly...

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Electromagnetic field of the ground-based source surrounded by a plasma semispheroid

Bichoutskaia¹,

Makarov²

2006

Int. J. Geomagn. Aeron.

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Radiation of an Electric Dipole from a Small Plasma Spheroid

Cited by 4 publications

References 3 publications

Field of an Electric Dipole Surrounded by a Small Plasma Spheroid with a Cavity

Field of an Electric Dipole Surrounded by a Small Plasma Spheroid with a Cavity

Radiation from a small spheroidal antenna with plasma shell

Electromagnetic field of the ground-based source surrounded by a plasma semispheroid

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