Conductor, idealized homogeneous

Electromigration is the displacement of atoms in a conductor due to an electric current. A metal, such as aluminum, consists of positively charged ions, and Z conduction electrons per ion (Z = 3 for aluminum). To simplify the discussions, we will consider an idealized homogenous conductor, rather than the more realistic polycrystalline description. Our mixture is then made of two components, an electron gas and an ionic body, which we will describe as a linearly elastic solid. 

Basic Relations in the Idealized Homogeneous Volume Conductor... 

While this is a well-known relationship, its use is limited to cmly one circuit element - the ideal resistor. An ideal resistor follows Ohm s law at all current, voltage, and AC frequency levels. The resistor s characteristic resistance value R [ohm] is independent of AC frequency, and AC current and voltage signals through the ideal resistor are in phase with each other. Let us assume that the analyzed sample material is ideally homogeneous and completely fills the volume bounded by two external current conductors ( electrodes ) with a visible area A that is placed apart at uniform distance d is formed, as shown in Fig. 1. When external voltage V is applied, a uniform current 7 passes through the sample, and the resistance is defined as... 

Idealized homogeneous volume conductor, basic relations in, 20-1-20 3... 

The major artifacts contributing to uncertainties in PDCE results stem from effects caused by bombardment of nonideal specimens, particularly thick specimens. The ideal thick specimen would be a homogeneous, smooth electrical conductor that does not change during bombardment. Except for rather simple, well-defined layered structures (e.g., surface oxide layers), specimens having compositional variations with depth yield spectra whose analyses can have large inaccuracies. 

Important electrical characteristics of an electrode/tissue system are determined solely by the geometrical configuration. To clarify this important function, the systems to be treated in Chapter 6 are simple models suited for basic analysis and mathematical treatment as well as computational approaches such as finite element analysis (Section 6.5). In bioimpedance systems, the biomaterial is usually an ionic wet conductor, and the current carrying electrodes are polarized. However, in fliis chapter, the models are idealized in several ways. Biomaterial is considered homogeneous and isotropic. An electrode is considered isoelectric (superconducting metal). Only DC systems without polarization phenomena and frequency dependence are considered. Then a potential difference between two points in tissue space is equal to the voltage difference found between two circuit wires connected to the same two points,... 

Figure 6.13 Two ideal dipoles far away from each other in an infinite, homogeneous conductor volume. Their axes need not cross each other. The left dipole is current carrying (Lee) the right dipole (Lpu) picks up signals transferred from L/C-...

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