Migration electromagnetic

In this section we introduce first the migrated anomalous electromagnetic field and show how it can be calculated from the anomalous field. In the following sections we will demonstrate the connections between the migrated electromagnetic fields and the solution of the electromagnetic inverse problem. 

Meanwhile, let us consider a few simple examples, illustrating the spatial behavior of the migrated electromagnetic fields. The first example represents the results of migration of the magnetic component of the field generated by a local horizontal electric dipole, located at some depth, zq, in the homogeneous lower half-space of conductivity ab- The current in the dipole is described by the delta-pulse ... 

Microwave radiation, as all radiation of an electromagnetic nature, consists of two components, i.e. magnetic and electric field components (Fig. 1.3). The electric field component is responsible for dielectric heating mechanism since it can cause molecular motion either by migration of ionic species (conduction mechanism) or rotation of dipolar species (dipolar polarization mechanism). In a microwave field, the electric field component oscillates very quickly (at 2.45 GHz the field oscillates 4.9 x 109 times per second), and the strong agitation, provided by cyclic reorientation of molecules, can result in an... 

Furthermore, multiple ionization, which has been postulated as being able to bring about displacements of interior atoms (30), might be extremely effective in leading to surface migrations and thermal patches, in which case surface properties could be more sensitive to electromagnetic radiation than to particle radiation. it was hoped that the present studies would shed some light on what actually happens. 

There are several other interesting topics in quantum optics which we would like to be able to study. For example, we would like model problems in double resonance spectroscopy, where there are two electromagnetic fields with possibly different polarizations simultaneously interacting with a molecule. This problem resembles the multiple photon excitation problem in that there is population migration along ladders of states, but in this case there can be a vastly larger number of quantum levels to treat — on the order of 2(2J+1). At room temperature, the most probable value of J for SF is about 60, which implies a 250 state calculation. 

Microwaves are electromagnetic waves (see p. 329) and there are electric and magnetic held components. Charged particles start to migrate or rotate as the electric held is applied,which leads to further polarization of polar particles. Because the concerted forces applied by the electric and magnetic components of... 

In the following chapters we will demonstrate that approximation (3.87) results in effective imaging schemes for different geophysical data interpretations, including gravity, electromagnetic and seismic migration. 

In the later sections of this book we will demonstrate that the same technique can be applied to electromagnetic and seismic wave field Inversion. In these areas of geophysics, migration serves as a useful practical tool for imaging geophysical data, because of the relative numerical simplicity and transparent physical interpretation of the results of electromagnetic and seismic migration. 

Electromagnetic Green s tensors represent an important tool in the solution of the forward and inverse electromagnetic problems and in migration imaging. We will illustrate Green s tensor applications in the next Chapter. 

Now we will show how the electromagnetic field migration introduced above is related to minimization of the energy flow functional. The important step in the solution of the functional minimization problem (11.13) is calculating the steepest ascent direction (or the gradient) of the functional. To solve this problem, let us perturb the conductivity distribution crj, (x, z) = at, x, z)+Sa x, z). Actually, we have to perturb the conductivity only within the inhomogeneous domain F of the lower half-plane ... 

Time domain electromagnetic (EM) migration is based on downward extrapolation of the residual field in reverse time. In this section I will show that electromagnetic migration, as the solution of the boundary value problem for the adjoint Maxwell s equation, can be clearly associated with solution of the inverse problem in the time domain. In particular, I will demonstrate that the gradient of the residual field energy flow functional with respect to the perturbation of the model conductivity is equal to the vector cross-correlation function between the predicted field for the given... 

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