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Electromagnetic radiation

About: Electromagnetic radiation is a(n) research topic. Over the lifetime, 37281 publication(s) have been published within this topic receiving 560122 citation(s). The topic is also known as: EMR & EM radiation. more


Open accessBook
01 Jan 1960-
Abstract: Electrostatics of conductors Static magnetic field Superconductivity The propagation of electromagnetic waves Spatial dispersion Diffraction of X rays in crystals. more

Topics: Electromagnetic radiation (56%), Diffraction (55%), Magnetostatics (55%) more

12,539 Citations

Open accessBook
01 Jan 1992-
Abstract: Introduction.- The Helmholtz Equation.- Direct Acoustic Obstacle Scattering.- III-Posed Problems.- Inverse Acoustic Obstacle Scattering.- The Maxwell Equations.- Inverse Electromagnetic Obstacle Scattering.- Acoustic Waves in an Inhomogeneous Medium.- Electromagnetic Waves in an Inhomogeneous Medium.- The Inverse Medium Problem.-References.- Index more

Topics: Inverse scattering problem (63%), Inverse scattering transform (60%), Scattering theory (60%) more

4,762 Citations

Open access
01 Jan 1981-
Topics: Scattering (60%), Electromagnetic radiation (59%), Magnetic field (57%) more

4,495 Citations

Open accessBook
01 Jan 1960-
Abstract: Preface. Basic Electromagnetic Theory. Green's Functions. Transverse Electromagnetic Waves. Transmission Lines. Waveguides and Cavities. Inhomogeneously Filled Waveguides and Dielectric Resonators. Excitation of Waveguides and Cavities. Variational Methods for Waveguide Discontinuities. Periodic Structures. Integral Transform and Function-Theoretic Techniques. Surface Waveguides. Artificial Dielectrics. Mathematical Appendix. Name Index. Subject Index. About the Author. more

4,300 Citations

Journal ArticleDOI: 10.1109/PROC.1963.1664
E.T. Jaynes1, F.W. CummingsInstitutions (1)
01 Jan 1963-
Abstract: This paper has two purposes: 1) to clarify the relationship between the quantum theory of radiation, where the electromagnetic field-expansion coefficients satisfy commutation relations, and the semiclassical theory, where the electromagnetic field is considered as a definite function of time rather than as an operator; and 2) to apply some of the results in a study of amplitude and frequency stability in a molecular beam maser. In 1), it is shown that the semiclassical theory, when extended te take into account both the effect of the field on the molecules and the effect of the molecules on the field, reproduces almost quantitatively the same laws of energy exchange and coherence properties as the quantized field theory, even in the limit of one or a few quanta in the field mode. In particular, the semiclassical theory is shown to lead to a prediction of spontaneous emission, with the same decay rate as given by quantum electrodynamics, described by the Einstein A coefficients. In 2), the semiclassical theory is applied to the molecular beam maser. Equilibrium amplitude and frequency of oscillation are obtained for an arbitrary velocity distribution of focused molecules, generalizing the results obtained previously by Gordon, Zeiger, and Townes for a singel-velocity beam, and by Lamb and Helmer for a Maxwellian beam. A somewhat surprising result is obtained; which is that the measurable properties of the maser, such as starting current, effective molecular Q, etc., depend mostly on the slowest 5 to 10 per cent of the molecules. Next we calculate the effect of amplitude and frequency of oscillation, of small systematic perturbations. We obtain a prediction that stability can be improved by adjusting the system so that the molecules emit all their energy h Ω to the field, then reabsorb part of it, before leaving the cavity. In general, the most stable operation is obtained when the molecules are in the process of absorbing energy from the radiation as they leave the cavity, most unstable when they are still emitting energy at that time. Finally, we consider the response of an oscillating maser to randomly time-varying perturbations. Graphs are given showing predicted response to a small superimposed signal of a frequency near the oscillation frequency. The existence of "noise enhancing" and "noise quieting" modes of operation found here is a general property of any oscillating system in which amplitude is limited by nonlinearity. more

Topics: Semiclassical physics (59%), Quantum (55%), Electromagnetic field (55%) more

3,567 Citations

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Topic's top 5 most impactful authors

Padma Kant Shukla

141 papers, 2.9K citations

Lennart Stenflo

62 papers, 987 citations

Joshua D. Talbert

23 papers, 2 citations

Paul Shala Henry

23 papers, 3.8K citations

Sergei V. Bulanov

23 papers, 868 citations

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