From: "Eric Walker" <eric.wal...@gmail.com> Sent: Tuesday, October 28, 2014 10:20:52 PM
On Tue, Oct 28, 2014 at 12:36 PM, Alan Fletcher < a...@well.com > wrote: Basically what happens is that as the temperature changes the peak of the blackbody spectrum moves through different parts of the emissivity/wavelength curve. Are you assuming a standard Boltzmann curve that just shifts its peak according to emittance? Is it possible that the frequency and heat-dependant combination of emittance, transmissivity and reflection make it so that there is a distribution other than a Boltzmann distribution for the alumina shell? Eric Yes, that's how Planck's formula/integration works. It TRIES to send a Boltzmann curve, but this is modulated by the emissivity spectrum. As the temperature increases the spectral peak get higher and shifts to shorter wavelengths. If the emissivity is higher then the total power will increase, otherwise (as in this case) it decreases. Per Manara the transmission looks negligible outside the visible range, where there's practically no blackbody power anyway up to 1400C. (It moves to the visible at much higher temperatures -- 4000 to 6000C).
