Generalized combined field integral equations for the iterative solution of the three-dimensional Maxwell equations

The construction of new second-kind Fredholm integral equations for the numerical solution of problems of high-frequency electromagnetic scattering by a perfect conductor is proposed. These formulations are characterized by some eigenvalue clusterings. They are especially well adapted to Krylov subspace iterative solvers. Their derivation is based on the incorporation of a sufficiently accurate approximation of the exact operator linking the Cauchy data of the scattering boundary-value problem to the classical integral relations. This operator is related to the concept of the On-Surface Radiation Condition (OSRC). These formulations can be considered as a natural generalization of the well-known Brakhage–Werner and combined field integral equations. The efficiency of the approach is established through an analytical and numerical study in the spherical case.     

Nonstationary Maxwell equations

ABSTRACT

The paper deals with a mixed problem for nonstationary generalised Maxwell equations. The boundary conditions are of Riemann-Hilbert type. The problem is reduced to a mixed problem for a wave equation where the boundary conditions are of Dirichlet type as they were introduced by D. Spencer in the middle 1950?s. We use the Fourier method to construct an approximate solution to the problem in certain function spaces of Sobolev type.     

Solution of axisymmetric Maxwell equations

In this article, we study the static and time‐dependent Maxwell equations in axisymmetric geometry. Using the mathematical tools introduced in (Math. Meth. Appl. Sci. 2002; 25 : 49), we investigate the decoupled problems induced in a meridian half‐plane, and the splitting of the solution in a regular part and a singular part, the former being in the Sobolev space H¹ component‐wise. It is proven that the singular parts are related to singularities of Laplace‐like or wave‐like operators. We infer from these characterizations: (i) the finite dimension of the space of singular fields; (ii) global space and space–time regularity results for the electromagnetic field. This paper is the continuation of (Modél. Math. Anal. Numér. 1998; 32 : 359, Math. Meth. Appl. Sci. 2002; 25 : 49). Copyright © 2003 John Wiley & Sons, Ltd.     

Spectral element discretization of the Maxwell equations

We consider a variational problem which is equivalent to the electromagnetism system with absorbing conditions on a part of the boundary, and we prove that it is well-posed. Next we propose a discretization relying on a finite difference scheme for the time variable and on spectral elements for the space variables, and we derive error estimates between the exact and discrete solutions. RESUME. On considère un problème variationnel équivalent aux équations de l'électromagnétisme avec conditions aux limites absorbantes sur une partie de la frontière, qu'on prouve être bien posé. Puis on propose une discrétisation de ce problème par schéma aux différences finies en temps et éléments spectraux en espace, et on établit des estimations d'erreur entre solutions exacte et approchée.

     

Radiative transport limit of Dirac equations with random electromagnetic field

Abstract

This paper concerns the kinetic limit of the Dirac equation with a random electromagnetic field. We give a detailed mathematical analysis of the radiative transport limit for the phase space energy density of solutions to the Dirac equation. Our derivation is based on a martingale method and a perturbed test function expansion. This requires the electromagnetic field to be a Markovian space-time random field. The main mathematical tool in the derivation of the kinetic limit is the matrix-valued Wigner transform of the vector-valued Dirac solution. The major novelty compared with the scalar (Schrödinger) case is the proof of the weak convergence of cross modes to zero. The propagating modes are shown to converge in an appropriate probabilistic sense to their deterministic limit.     

Solvability of the linear Maxwell equations with memory

We investigate the solvability of initial-boundary-value problems in the electrodynamics of conducting media with material equations of Volterra type. The problems are formulated in a new, nonclassical setting. Existence and uniqueness theorems are proved using the compactness method and a generalized Gronwall-Bellman inequality with multiple integrals.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 5, pp. 619–625, May, 1991.     

Component splitting for semi-discrete Maxwell equations

A time-integration scheme for semi-discrete linear Maxwell equations is proposed. Special for this scheme is that it employs component splitting. The idea of component splitting is to advance the greater part of the components of the semi-discrete system explicitly in time and the remaining part implicitly. The aim is to avoid severe step size restrictions caused by grid-induced stiffness emanating from locally refined space grids. The proposed scheme is a blend of an existing second-order composition scheme which treats wave terms explicitly and the second-order implicit trapezoidal rule. The new blended scheme retains the composition property enabling higher-order composition.     

An initial-boundary value problem for the Maxwell equations

In this paper, by using methods from complex analysis and quaternionic analysis, we investigate an initial-boundary value problem for the Maxwell equations and obtain the general solutions and solvable conditions of the problem respectively in different cases. In addition, by using a similar method, we also discuss an initial-boundary value problem for a hyperbolic complex system of first order equations in R³.     

Theoretical tools to solve the axisymmetric Maxwell equations

In this paper, the mathematical tools, which are required to solve the axisymmetric Maxwell equations, are presented. An in‐depth study of the problems posed in the meridian half‐plane, numerical algorithms, as well as numerical experiments, based on the implementation of the theory described hereafter, shall be presented in forthcoming papers. In the present paper, the attention is focused on the (orthogonal) splitting of the electromagnetic field in a regular part and a singular part, the former being in the Sobolev space H¹ component‐wise. It is proven that the singular fields are related to singularities of Laplace‐like operators, and, as a consequence, that the space of singular fields is finite dimensional. This paper can be viewed as the continuation of References (J. Comput. Phys. 2000; 161 : 218–249, Modél. Math. Anal. Numér, 1998; 32 : 359–389) Copyright © 2002 John Wiley & Sons, Ltd.     

Existence of static solutions of the semilinear Maxwell equations

Abstract In this paper we study a model which describes the relation of the matter and the electromagnetic field from a unitarian standpoint in the spirit of the ideas of Born and Infeld. This model, introduced in [1], is based on a semilinear perturbation of the Maxwell equation (SME). The particles are described by the finite energy solitary waves of SME whose existence is due to the presence of the nonlinearity. In the magnetostatic case (i.e. when the electric field and the magnetic field does not depend on time) the semilinear Maxwell equations reduce to semilinear equation where “ ” is the curl operator, f′ is the gradient of a smooth function and is the gauge potential related to the magnetic field ( ). The presence of the curl operator causes (1) to be a strongly degenerate elliptic equation. The existence of a nontrivial finite energy solution of (1) having a kind of cylindrical symmetry is proved. The proof is carried out by using a variational approach based on two main ingredients: the Principle of symmetric criticality of Palais, which allows to avoid the difficulties due to the curl operator, and the concentration-compactness argument combined with a suitable minimization argument. Keywords: Maxwell equations, Natural constraint, Minimizing sequence Mathematics Subject Classification (2000): 35B40, 35B45, 92C15     

Decoupled field integral equations for electromagnetic scattering from homogeneous penetrable obstacles

We present a new method for the analysis of electromagnetic scattering from homogeneous penetrable bodies. Our approach is based on a reformulation of the governing Maxwell equations in terms of two uncoupled vector Helmholtz systems: one for the electric field and one for the magnetic field. This permits the derivation of resonance-free Fredholm equations of the second kind that are stable at all frequencies, insensitive to the genus of the scatterers, and invertible for all passive materials including those with negative permittivities or permeabilities. We refer to these as decoupled field integral equations.     

A hierarchy of approximate models for the Maxwell equations

Summary. In this paper we perform an asymptotic study of the Maxwell equations with respect to the small parameter where is the characteristic velocity associated with the physical problem and is the speed of light. This enables us to derive the quasistatic and Darwin models as respectively first and second order approximations of the Maxwell equations. Moreover, an interpretation of the obtained variational formulations gives us the appropriate boundary conditions for these models. Received May 18, 1995     

Integrating Klein-Gordon-Fock equations in an external electromagnetic field on Lie groups

We investigate the structure of the Klein-Gordon-Fock equation symmetry algebra on pseudo-Riemannian manifolds with motions in the presence of an external electromagnetic field. We show that in the case of an invariant electromagnetic field tensor, this algebra is a one-dimensional central extension of the Lie algebra of the group of motions. Based on the coadjoint orbit method and harmonic analysis on Lie groups, we propose a method for integrating the Klein-Gordon-Fock equation in an external field on manifolds with simply transitive group actions. We consider a nontrivial example on the four-dimensional group E(2)×? in detail.     

Fourth-order schemes for the wave equation,Maxwell equations,and linearized elastodynamic equations

With simple finite-difference operators we construct fourth-order schemes in space and in time for the wave equation, Maxwell equations, and linearized elastodynamic equations using the modified equation approach. The schemes remain stable for arbitrary heterogeneous mediums because the relevant difference operators are always positive definite. We also present some dispersion curves to show the accuracy of the schemes. © 1994 John Wiley & Sons, Inc.     

Solutions of the Maxwell equations describing the spectrum of hydrogen

We obtain a new class of solutions of the Maxwell equations describing the spectrum of hydrogen. We prove that, instead of the quantum-mechanical Dirac equation, the ordinary classical Maxwell equations can be applied to the solution of many problems in atomic and nuclear physics. Institute of Electron Physics, Ukrainian Academy of Sciences, Uzhgorod. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 49, No. 7, pp. 958–969, July, 1997.     

Regularity of the Maxwell equations in heterogeneous media and Lipschitz domains

This note establishes regularity estimates for the solution of the Maxwell equations in Lipschitz domains with non-smooth coefficients and minimal regularity assumptions. The argumentation relies on elliptic regularity estimates for the Poisson problem with non-smooth coefficients.