Radiation field total power

Power of radiation field has been estimated by checking the total power determined by (3.5). The difference between the initial power T2 (0) = 1 and the power T2 (z) at the point z is equal to the normalized power losses prad jg important to note that as the computational window has finite... 

As a result of self-focusing, power propagating within the core f iz) inereases behind the region of unsteady-state regime (Fig. 10). Meanwhile the total power of the light beam calculated within the computational window decreases due to emitting of radiation field outside the window. 

Such a behavior of the total field is observed provided that the beam power is smaller than a definite value P which depends on the waveguide width (for a = 1.8pm, P 8). The spatial dynamics of a light beam with P > Pi is more complicated because nonlinear self-effects in radiation field increase so that the formation of soliton-like light beams propagating in the waveguide cladding is observed. 

Note that the radiation field is dependent on one angle only, namely the angle 9 subtended by the acceleration r and radius arm vector R the dependence enters Eq. 2.60 as (sin 9)2 which is characteristic of the familiar dipole radiation pattern. It is, therefore, straightforward to integrate Eq. 2.60 over a spherical surface R2 f dQ where dQ = sin 9 d9 dtotal power emitted,... 

Blackbody radiation is achieved in an isothermal enclosure or cavity under thermodynamic equilibrium, as shown in Figure 7.4a. A uniform and isotropic radiation field is formed inside the enclosure. The total or spectral irradiation on any surface inside the enclosure is diffuse and identical to that of the blackbody emissive power. The spectral intensity is the same in all directions and is a function of X and T given by Planck s law. If there is an aperture with an area much smaller compared with that of the cavity (see Figure 7.4b), X the radiation field may be assumed unchanged and the outgoing radiation approximates that of blackbody emission. All radiation incident on the aperture is completely absorbed as a consequence of reflection within the enclosure. Blackbody cavities are used for measurements of radiant power and radiative properties, and for calibration of radiation thermometers (RTs) traceable to the International Temperature Scale of 1990 (ITS-90) [5]. 

Strict compliance with AN SI-92 or NCRP-86 requires not only determination, by calculation or by measurement, of the total far-field equivalent power density from all nearby sources, but also measurement of body current from contact with potentially radiating objects and, for ANSI-92, measurement of body current induced by immersion in fields near such objects. Power density measurements are straightforward to take, using specialized broadband equipment calibrated in power density (or even in percent of some standard) such measurements can also be made using broadband or narrow-band equipment calibrated more traditionally in field strength. The conversion from field strength to equivalent far-field power density S, in milliwatt per square centimeter (mW/cm ), uses the impedance of free space, 377 as follows ... 

Our intuitive description of a leaky mode in Section 24-12 ensures that total power is conserved as the mode propagates. This property emphasizes the idea that the power attenuation coefficient y represents the rate of power loss from the guided portion of the fields to the radiation portion of the same fields, namely... 

The total, time-averaged power flow of the radiation field parallel to the waveguide axis has magnitude This follows from Eq. (11-25) as... 

Although the cross-coupling coefficients may be arbitrarily small, a large fraction of total power of the composite waveguide can transfer between the two fibers under resonant conditions. Indeed, if this is not the case, then Eq. (29-3) is inadequate and coupling to the backward-propagating fundamental modes and to the radiation fields of both fibers must be included. Resonance occurs when the fibers are identical or nearly identical, in which case we deduce from Eq. (29-5) that... 

The general expressions for the fields produced by an electric quadrupole source are of rather complicated form. However, we are mainly interested in the fields in the wave zone since this will enable us to discuss the angular distribution and total power radiated. When using B = curl A we therefore retain only the term which varies as 1/r. The magnetic field is found to have the following form ... 

Fig. 3.10. Normalized ELM particle loss (AArELM/Artot, where Ntot is the total particle content) versus ELM frequency (/elm) for JET discharges with plasma current /p = 2.5 MA, toroidal field Bt = 2.4-2.7 T, input power Pinput = 14-17 MW and medium (S = 0.3) and high (<5 = 0.5) triangularity. Two discharges (at medium and high S) in which Argon has been injected to increase the level of plasma radiation are shown for comparison. Lines are to guide the eye [16]...

When light interacts with matter, and the photons are not absorbed, it does so by inducing a polarization in the medium. Since the interaction energy between the electric field of the incident radiation and the molecules making up the medium is small compared to the total energy of the molecules, the incident radiation can be treated as a perturbation to the total energy of the medium. (This is true for pulsed laser beams as well as ambient light [13].) Therefore, the polarization of the medium, P, can be expanded as a power series in the electric field [13,14]. 

The oscillating laser field distorts the electronic charge density producing a time-dependent dipole in the atom which itself will radiate. The emission strength at a given frequency to is given by the frequency cubed times the square of the Fourier transform of the total induced dipole [14], We typically calculate the power spectrum, o(co), over the last five cycles of the pulse described above ... 

Methods based on nonlinear effects e.g. radiation forces. He also introduced other subdivisions depending on whether the method could be used for total or local power measurements, under free or restrained field conditions. 

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