Radiometric Term: Power Emitted/Vol/Angle

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Discussion Overview

The discussion revolves around the search for a radiometric term that describes the quantity of power emitted per unit volume per unit solid angle, particularly in the context of gases or plasmas. Participants explore the implications of this quantity and its relevance to radiometric measurements.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about a specific radiometric term for power emitted per unit volume per unit solid angle.
  • One participant suggests the term "intensity density" as a possible candidate, linking it to the concept of intensity defined as power per solid angle.
  • Another participant questions which volume is being referenced, specifically asking if it pertains to the emitter's volume.
  • A participant clarifies that they are referring to the emitter volume, particularly in the context of gases or plasmas.
  • Concerns are raised about how to account for the emitter's volume when considering power received by a surface, especially in cases of nonuniform power generation.
  • One participant wonders how to incorporate the opacity of the medium into the discussion, noting that the inner regions of a gas volume may behave differently than the outer regions, using stars as an example.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific term for the discussed quantity, and multiple viewpoints regarding the implications of emitter volume and medium opacity remain unresolved.

Contextual Notes

Limitations include the ambiguity surrounding the definition of the emitter volume and the challenges of accounting for nonuniform power generation and medium opacity in the context of radiometric measurements.

Khashishi
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Is there a radiometric term for the quantity (power emitted per unit volume per unit solid angle)?
 
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Khashishi said:
Is there a radiometric term for the quantity (power emitted per unit volume per unit solid angle)?

Since power per solid angle [W/sr] is "Intensity", I suspect you are thinking of 'intensity density'? It has a nice rhythm, at least...
 
Khashishi said:
Is there a radiometric term for the quantity (power emitted per unit volume per unit solid angle)?
Which volume are you referring to? That of the emitter?
 
emitter volume. For a gas or plasma.
 
For a receiving surface external to an emitting object, usually only the power per unit area and/or solid angle are considered as that is what the receiving surface "sees." As such, I'm not sure how the volume of the emitter can be taken into account, especially if there is nonuniform power generated throughout.
 
Khashishi said:
emitter volume. For a gas or plasma.
How would one include the opacity of the medium, I wonder? The inner regions of a volume of gas would not necessarily have the same effect as the outer regions. Take the example of s Star, for instance. That's an extreme example but worth while thinking about.
 

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