Field Of Plane Electromagnetic Wave Research Articles

Nuclear beta decay induced by intense electromagnetic fields: Forbidden transition examples

A formalism developed earlier for the effect on nuclear beta decay of an intense planewave electromagnetic field is applied to three examples of forbidden beta transitions. The examples represent cases where the nuclear contains one, two, and three nucleons; where the nuclear fragment is defined to be that smallest sub-unit of the nucleus containing the nucleon which undergoes beta decay plus any other nucleons directly angular-momentum coupled to it in initial or final states. The single-nucleon-fragment example is $^{113}\mathrm{Cd}$, which has a fourth-forbidden transition. The two-nucleon-fragment example is $^{90}\mathrm{Sr}$, which is first-forbidden. The three-nucleon-fragment example is $^{87}\mathrm{Rb}$, which is third-forbidden. An algebraic closed-form transition probability is found in each case. At low external-field intensity, the transition probability is proportional to ${z}^{L}$, where $z$ is the field intensity parameter and $L$ is the degree of forbiddenness. At intermediate intensities, the transition probability behaves as ${z}^{L\ensuremath{-}(\frac{1}{2})}$. At higher intensities, the transition probability contains the ${z}^{L\ensuremath{-}(\frac{1}{2})}$. factor, a declining exponential factor, and an alternating polynomial in $z$. This high-intensity transition probability possesses a maximum value, which is found for each of the examples. A general rule, $z={q}^{2}(2L\ensuremath{-}1)$, where $q$ is the number of particles in the fragment, is found for giving an upper limit on the intensity at which the maximum transition probability occurs. Field-induced beta decay half-lives for all the examples are dramatically reduced from natural half-lives when evaluated at the optimum field intensity. Relative half-life reduction is greater the higher the degree of forbiddenness.RADIOACTIVITY $^{87}\mathrm{Rb}$, $^{90}\mathrm{Sr}$, $^{113}\mathrm{Cd}$ intense-field-induced $\ensuremath{\beta}$ decay minimum half-lives, half-life reduction forbiddenness dependence.

Spontaneous emission by an electron in an arbitrary plane-wave electromagnetic field

On the basis of general expressions obtained for the total emission probability and the probability of a radiation transition with spin reversal of an electron moving in an arbitrary plane-wave electromagnetic field, the particular case of a plane-wave field is considered. It is shown that under certain conditions self-polarization of the electron spin is possible during the emission by an electron in a field which is the superposition of a constant crossed field and a plane, elliptically polarized, electromagnetic wave.

Electron in the classical external field of a plane electromagnetic wave: High-energy limits

It is shown that Volkov's exact solution of the Dirac equation for an electron in the classical external field of an arbitrary plane electromagnetic wave can be cast, by means of an exact Mendlowitz-type unitary transformation, in a form in which positive- and negative-helicity states are separately described by two-component spinors. High-energy limits are then obtained by a mere expansion.

Optically induced band structure of free electrons in an external plane wave field

The motion of a non-relativistic free charged particle in a classical electromagnetic plane wave field is investigated. By introducing the ansatz of a modulated plane wave for the wavefunction, the problem is reduced to the solution of the general Mathieu equation for a circularly polarised field and to the solution of the Hill equation for a linearly polarised field. The corresponding eigenvalue equations show that physical values of the energy are separated into bands. The relationship with earlier methods is also discussed.

On the Response of a Terminated Twisted-Wire Cable Excited by a Plane-Wave Electromagnetic Field

The currents induced in the terminations of a twisted-pair cable are obtained for a plane-wave electromagnetic-field. Various termination configurations are considered and comparisons are made with the corresponding results for untwisted pairs. In special cases, the twisted cable may have a larger induced signal than the untwisted. Under various common restrictions, the induced signal is inversely proportional to either 1) the square of the number of turns or 2) the number of turns.

Receiving Properties of the Small Annular-Slot Antenna

An analytical formula for the effective height of an annularslot antenna is determined using the reciprocity theorem. This result generalizes the previously available single-frequency steady-state result and yields an equivalent circuit valid for computing the transient response of the small annular-slot antenna. the theory has application in calibrating near-zone field strength instrumentation and in determining the response of an unsheathed coaxial cable connector mounted flush with the skin of a missile to intense plane-wave electromagnetic field pulses.

Correction to "Current and Charge Densities Induced on the Surface of a Prolate Spheroid Illuminated by a Plane Wave Electromagnetic Field"

Correction to "Current and Charge Densities Induced on the Surface of a Prolate Spheroid Illuminated by a Plane Wave Electromagnetic Field"

Current and Charge Densities Induced on the Surface of a Prolate Spheroid Illuminated by a Plane Wave Electromagnetic Field

The current and charge densities induced on the surface of a highly conducting prolate spheroid in the presence of a plane wave electromagnetic field are obtained. The derived formula for the charge density is approximate except at the tips of the spheroid, where it yields exact results regardless of the eccentricity. One application of the theory is the determination of the total permissible current in a missile, before dielectric breakdown of the ambient medium occurs at the tip of the missile.

Paradoxes of the quantum theory of the Vavilov-Cerenkov and Doppler effects

The Minkowski tensor gives gM = nu/c (I) for the momentum density g of a plane-wave electromagnetic field in a stationary medium, whereas the Abraham tensor gives gA = u/nc (II), where u is the energy density and n the refractive index. Expression (I) cannot be reconciled with J = μν (III), where μ is the mass of the wave packet and ν is its velocity if, according to Einstein, μ = E/c2, where J is the momentum and E the energy of the wave packet. On the other hand, the expression for the pseudomomentum JM = nE/c (IV), which follows from (I), is identical with the expression for the momentum of the quantum photon J = nhν/c (V), whereas the formula the follows from (II), i.e., JA = E/nc (VI) is in agreement with the Einstein equation (III) but is in conflict with (V). Simple calculation for stationary medium and source shows that (IV) and (VI) can be reconciled if one takes into account the fact that, under certain assumptions, JM = JA + ΔJ (VII), where ΔJ is the momentum communicated to the medium in the photon emission process. It is shown in this paper that, within the framework of the adopted assumptions and, probably, classical models generally, expression (VII) cannot be generalized to the case of a source moving relative to the medium. This result is in conflict with the conclusions reported by V. L. Ginzberg and V. A. Ugarov [Usp. Fiz. Nauk 118, 175 (1976)] [Sov. Phys. Usp. 19, 94 (1976)]. Moreover, it is shown that, if (VII) is introduced as a postulate for a source moving relative to the medium, one can satisfy at the same time both the quantum conditions and (V), on the one hand, and the fundamental Einstein relation (III), on the other.

Photon induced relativistic band structure in dielectrics

We show that an electromagnetic plane wave field induces a band structure for electron scattering in a refractive medium. This can lead to a new type of diffractive scattering of electrons in the medium.

Solutions of higher-spin wave equations in external electromagnetic plane-wave fields

The Proca equation for a vector particle with an arbitrary magnetic dipole and electric quadrupole moment and the Rarita-Schwinger equation in the presence of an external electromagnetic plane-wave field are reduced by systems of ordinary differential equations which can be solved in special cases. The propagation behaviour of the solutions is investigated and found to exhibit in general the inconsistencies predicted by Velo and Zwanziger (1971). In some cases there are in addition tachyonic modes. Characteristic differences appear for linear and circular polarization of the external field.

Effect of intense electromagnetic wave in charged-particle scattering

The recent theoretical results of Kroll and Watson concerning charged-particle scattering in the presence of an intense electromagnetic wave are rederived by using the solution of the Schr\"odinger equation of a charged particle coupled to a plane-wave electromagnetic field in the dipole approximation and by utilizing the Born approximation.

Receiving Characteristics of Impedance Loaded Slot Configurations

A general theory is developed for determining the current in the load impedance of any slot configuration in terms of the current in the load impedance of the complementary strip (wire) circuit. It is assumed that these duals are illuminated by plane wave electromagnetic fields. Following establishment of the procedures and techniques for analysis of strip and slot circuits, the practical situation presented by a bomb in the open bomb bay of an aircraft with load impedance connected between one end of the weapon and fuselage is treated. The load current is found approximately when the incident plane wave electric field is polarized in both transverse and longitudinal directions with respect to a strip that is equivalent electrically to a specific right circular cylinder that represents the weapon.

On the Transformation of a Definite Integral Occurring in Antenna and Transmission Line Theory

In solving problems of multiconductor antenna transmission lines excited by an incident plane wave electromagnetic field, it is necessary to separate the antenna mode from the transmission line modes. This is accomplished by suitably transforming the definite integrals that occur in the theory. The purpose of this correspondence is to explain in a meticulous manner how this is achieved.

Missile Circumferential Current Density for Plane Wave Electromagnetic Field Illumination

The asymmetry in current density along the periphery of cylindrical scattering obstacles of both finite and infinite length illuminated by a plane wave electromagnetic field is discussed. In the Appendix the same problem for a spherical scatterer is considered.

Theory of the Annular Slot Antenna Based on Duality

The general theory of annular slot antennas is developed in a lucid manner. The treatment is novel in that no Green's functions or contour integrations arise. The principle of duality is employed. Topics discussed include formulation of the integral equation for the aperture field and derivations of the leading term in the near- and far-zone fields and effective height. The theory has application in calibrating near-zone field strength instrumentation and in determining the response of an unsheathed coaxial cable connector mounted flush with the skin of a missile to intense plane-wave electromagnetic field pulses.

The Response of a Terminated Two-Wire Line Buried in the Earth and Excited by a Plane-Wave RE Field Generated in Free Space

A terminated two-wire transmission line is buried at constant depth near the earth-air interface with one conductor directly below the other. A plane-wave electromagnetic field, generated in free space, impinges upon the boundary where it undergoes partial reflection and transmission. The field transmitted into the earth excites the transmission line. The polarization of the electric field is chosen such that the field is directed parallel to the line conductors. The interaction of the line with the dispersive medium and the line losses are considered. The objective of the study is to determine the current in specified load impedances in terms of the amplitude of the incident electric field evaluated at the surface of the earth.

The Response of a Terminated Two-Wire Line Suspended in Air Above a Semi-Infinite Dissipative Medium and Excited by a Plane-Wave RF Field Generated in Free Space

The analysis previously made to determine the response of a two-wire transmission line buried at constant depth near the earth-air interface when excited by a plane-wave electromagnetic field generated in free space is extended to include the case of the line suspended in air at a uniform distance above the earth's surface. The exciting field is the vector sum of the incident and reflected fields at the point midway between the line conductors. The polarization of the electric field is taken to be parallel to the wires, so that there is no pick up by the terminations. The objective of the study is to determine bounds for the current in specified load impedances in terms of the amplitude of the incident electric field evaluated at the surface of the earth.

On the Response of a Missile with Exhaust Trail of Tapered Conductivity to a Plane Wave Electromagnetic Field

The current distribution along and scattering cross section of a missile with plume (ionized trail) is found, using numerical techniques when the conductivity of the plume tapers with increasing distance from the exhaust nozzles. In the theory no restrictions are imposed on the length of either the missile or plume, and the variation of conductivity along the entire scattering obstacle may be arbitrary. A model of cylindrical geometry is assumed. Curves for the current distribution along the missile and its ionized trial are presented for several missile and plume lengths at selected frequencies. A table is provided for the scattering cross sections.

Radiation of a Relativistic Charge in a Plane wave Electromagnetic Field

AbstractThe radiation of a charge moving in the field of a plane circularly polarized electromagnetic wave is discussed by the methods of classical and quantum theory both for a zeropin particle (boson) and for an electron. Such considerations allow us to analyse the role of quantum and spin effects on the radiation. It is shown that the present problem has deep analogies with the problem of the synchrotron radiation. From this point of view many physical features of COMPTON radiation are represented as simple consequences of the classical or quantum theory of synchrotron radiation.