Incident radiant flux intensity

Figure 9-8 shows the ignition boundaries of double-base propellants on radiative heating. As the incident radiant flux intensity If increases, the time of radiant heating for the ignition completion xig becomes shorter. As the propellant becomes opaque by the addition of carbon black, xig becomes shorter at constant If or If becomes smaller at constant Xig. The in-depth absorption is reduced and most of the radiative energy is absorbed at the ignition surface of the propellant. 

Incident radiant flux intensity, MW/m2 Figure 9-8. Radiative ignition criteria of double-base propellants with and without carbon black. 

Reflectance A measure of the extent to which a surface is capable of reflecting radiation, defined as the ratio of the intensity of reflected radiant flux to the intensity of the incident flux. 

Irradiance is the radiant flux incident on a plane, for example, a photographic emulsion coating. The term intensity is commonly used with this meaning in the photographic literature, and the symbol I has been retained in much of the literature to designate irradiance, although the I.O.S. recommends the symbol E. I is used in this chapter. 

The radiant flux incident on the unit detector area is called irradiance /, while in the spectroscopic literature it is often termed intensity. The flux density or intensity I [W/m ] of a plane wave E = Eq cos((ot — kz) traveling in vacuum in the z-direction is given by... 

When the spectral intensity within the solid angle dQ = 1 sr is incident on the entrance slit of area A, a spectrometer with an acceptance angle Q transmits the radiant flux within the spectral interval dX... 

Radiant Flux and Intensity. The quantity 0 is the power emitted by a radiation source, measured in watts (W). This quantity is measured by photometric detectors. The power incident on a surface d P/dA (in W m ) is commonly called the intensity (with a non-standardized imit I), although this is not correct. The correct SI notation is irradiance (symbol E). It should not be confused with the radiant intensity I, the power per imit solid angle (in W sr ). 

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