Backward and forward scattering of electromagnetic waves from partially aligned axially symmetric particles

2003 ◽  
Vol 79-80 ◽  
pp. 1061-1081 ◽  
Author(s):  
Nikolaos C Skaropoulos
Keyword(s):  
Electromagnetic Waves ◽  
Forward Scattering ◽  
Axially Symmetric

WAVE PROPAGATION IN A CYLINDRICAL WAVE GUIDE CONTAINING INHOMOGENEOUS PLASMA INVOLVING A TURNING POINT

1963 ◽  
Vol 41 (1) ◽  
pp. 113-131 ◽  
Author(s):  
S. N. Samaddar
Keyword(s):  
Electric Fields ◽  
Electromagnetic Waves ◽  
Turning Point ◽  
Boundary Effect ◽  
Inhomogeneous Plasma ◽  
Simple Zero ◽  
Wave Guide ◽  
Wave Number ◽  
Axially Symmetric ◽  
Radial Wave

Propagation of axially symmetric E-type and H-type modes of electromagnetic waves in a radially inhomogeneous plasma inside a wave guide is considered. For E-type modes conditions for the propagation of slow surface waves along the plasma–dielectric interface have been obtained. Approximate expressions for fields for wavelengths much smaller than the ratio of the gradient of the permittivity to the permittivity of the plasma are also given.It is also shown that if the dielectric constant ε(r) of the plasma vanishes along a particular surface r = r0, the electromagnetic fields for E-type modes behave singularly along this surface. In particular, if ε(r) has a simple zero at r0 ≠ 0, the radial and the longitudinal electric fields become singular as 1/ε(r0) and log ε(r0) respectively at r0. On the other hand, if ε(r) has a multiple zero at r0, the singularities of the above-mentioned fields will be as strong as a multiple pole at r0.Turning-point phenomena are also observed when the radial wave number [Formula: see text] vanishes along a surface. It is shown that the fields are oscillatory in the region [Formula: see text] and evanescent in the region [Formula: see text] for both E-type and H-type modes. The treatment of the singular behavior of the fields at ε(r) = 0, and of the turning-point phenomena at [Formula: see text], does not consider any boundary effect; therefore the results obtained here will be valid also for an inhomogeneous plasma column in free space.

scholarly journals NON-STATIONARY MODEL OF THE SOLAR CORE

2020 ◽  
pp. 101-104
Author(s):  
S.F. Skoromnaya ◽  
V.I. Tkachenko
Keyword(s):  
Electromagnetic Waves ◽  
Three Dimensional ◽  
The Other ◽  
Spherically Symmetric ◽  
The Sun ◽  
Axially Symmetric ◽  
Stationary Model ◽  
The Third ◽  
The Standard Model ◽  
Oscillatory Processes

The main parameters of the standard model of the Sun are considered, according to which the Sun is considered as a spherically symmetric and quasistatic star, and thermonuclear reactions of the pp-cycle mainly occur inside it and the energy is uniformly released at a rate of 2·10-4J/(kg·s). Based on observational data it was concluded that the Sun is not a star with uniformly ongoing processes, it is characterized by oscillatory processes and flashes. It is proposed to consider the non-stationary model of the Sun, in which it is required to take into account the existence of electromagnetic waves in the plasma of the solar core and, as a result, the existence of wave collapses (WC). A three-dimensional axially symmetric WC is considered and an estimate of the velocity of removal of the plasma of the solar core during the development of a three-dimensional axially symmetric WC is given. For the considered WC the existence of three directions of flows of elementary plasma volumes relative to the observer is demonstrated: one direction is due to the moving the elementary plasma volume from the observer and the other  to him. The third direction of moving of the elementary plasma volumes is perpendicular to the direction of observation and their velocity relative to the observer is zero. It is concluded that the existence of such motions of elementary plasma volumes during the development of WC can leave a definite imprint on the parameters of the synthesis products in them.

scholarly journals Simultaneous stimulated Raman forward and backward scattering in hot, well-underdense plasmas

1992 ◽  
Vol 10 (1) ◽  
pp. 75-89 ◽  
Author(s):  
S. J. Karttunen ◽  
R. R. E. Salomaa
Keyword(s):  
Electromagnetic Waves ◽  
Pump Wave ◽  
Forward Scattering ◽  
Phase Velocities ◽  
Underdense Plasmas ◽  
Plasma Slab ◽  
Two Stages ◽  
Forward Process ◽  
Very High ◽  
Stimulated Raman

The competition of stimulated Raman forward scattering and backscattering in a hightemperature, underdense, nearly homogeneous plasma slab is investigated. In such plasmas Landau damping limits the growth of the Raman backscattering, and the weaker forward process may reach comparable levels. A modest seeding of one of the scattered electromagnetic waves influences the competition to a large extent. The conversion of the pump wave to scattered waves is calculated. The simultaneous operation of the two processes can lead to considerable modifications in the electron distribution; e.g., two hot tail components are formed because the plasma waves involved have different phase velocities. The generation regions of the scattering processes are spatially separated. Consequently, a large number of thermal electrons can be accelerated to very high energies in two stages. The backward plasmons preaccelerate the electrons and the faster plasmons, excited in the forward scattering, operate as a booster.

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

Solar Internal Rotation and Dynamo Waves: A Two-Dimensional Asymptotic Solution in the Convection Zone

2000 ◽  
Vol 179 ◽  
pp. 379-380
Author(s):  
Gaetano Belvedere ◽  
Kirill Kuzanyan ◽  
Dmitry Sokoloff
Keyword(s):  
Magnetic Field ◽  
Asymptotic Solution ◽  
Internal Rotation ◽  
Convection Zone ◽  
General Idea ◽  
Dynamo Model ◽  
Axially Symmetric ◽  
Dynamo Action ◽  
Regeneration Rate ◽  
Dynamo Waves

Extended abstractHere we outline how asymptotic models may contribute to the investigation of mean field dynamos applied to the solar convective zone. We calculate here a spatial 2-D structure of the mean magnetic field, adopting real profiles of the solar internal rotation (the Ω-effect) and an extended prescription of the turbulent α-effect. In our model assumptions we do not prescribe any meridional flow that might seriously affect the resulting generated magnetic fields. We do not assume apriori any region or layer as a preferred site for the dynamo action (such as the overshoot zone), but the location of the α- and Ω-effects results in the propagation of dynamo waves deep in the convection zone. We consider an axially symmetric magnetic field dynamo model in a differentially rotating spherical shell. The main assumption, when using asymptotic WKB methods, is that the absolute value of the dynamo number (regeneration rate) |D| is large, i.e., the spatial scale of the solution is small. Following the general idea of an asymptotic solution for dynamo waves (e.g., Kuzanyan & Sokoloff 1995), we search for a solution in the form of a power series with respect to the small parameter |D|–1/3(short wavelength scale). This solution is of the order of magnitude of exp(i|D|1/3S), where S is a scalar function of position.

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