Maximum temperature under radiation

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Discussion Overview

The discussion revolves around the maximum temperature of a metal under electromagnetic radiation, focusing on the equilibrium temperature achieved when the energy absorbed from an external radiation source balances the energy emitted as black body radiation. The scope includes theoretical and mathematical reasoning related to energy flow and temperature calculations.

Discussion Character

  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant seeks formulas or publications to determine the maximum equilibrium temperature of a metal under radiation.
  • Another participant proposes a calculation involving the net energy flow, using the Stefan-Boltzmann law and an external radiation source.
  • A subsequent reply clarifies that the equilibrium temperature is reached when the energy absorbed from the external source equals the energy emitted as black body radiation.
  • Further discussion indicates that the temperature remains constant when the absorbed and emitted energies are balanced, leading to a specific relationship between the external radiation and the black body radiation.
  • One participant expresses concern about discrepancies between their results and published data, indicating a need for further investigation.

Areas of Agreement / Disagreement

Participants appear to agree on the concept of energy balance leading to an equilibrium temperature, but there is no consensus on the specific formulas or results, as one participant notes differences with published findings.

Contextual Notes

There are unresolved aspects regarding the specific conditions under which the equilibrium temperature is calculated, including assumptions about the properties of the metal and the nature of the external radiation source.

abbasranjbar
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Hello everyone,
As you all know, the temperature of a metal increases under electromagnetic radiation. The metal also has a black body radiation which decreases its temperature. There is an equilibrium temperature which is the maximum temperature of the metal under the radiation. I am looking for formulas or publication that gives me this final temperature.

Thanks
 
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Hm, it seems you want to calculate the net energy flow with

dE_- = -p(T)\,dt = -\sigma\,A\,T^4\,dt

where p(T) is the integrated density from Stefan-Boltzmann, and from an external radiation source with

dE_+ = p_0\,dt

Then you are looking for

dE_- + dE_+ = 0

Correct?
 
Last edited:
Yes, actually the equilibrium T of the material because of this net energy.
 
OK, you have

dE_+ + dE_- = 0
p_0\,dt - \sigma\,A\,T^4\,dt = 0
p_0 = \sigma\,A\,T^4

So the temperature is constant iff the black body radiation is balanced by radiation received from the external source.
 
Thank you Tom.
That makes sense. I checked it couple of times and my results were not match with the publications. I will check again to find the reason of the difference.

Cheers
 

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