It is much more complicated than thermal mass.
Thermal mass only determines how quickly an object will change temperature
for a given amount
of heat flow not how hot it will ultimately get.
Radiation cooling is very inefficient compared to convection or conduction
cooling.
That is because in heat transfer by radiation depends on photons being
exchanged between
an object and its surroundings. However, molecules can carry away much more
heat via
convection or conduction.
At 12:13 PM 11/9/2011 -0500, you wrote:
>On 08/11/2011 14:44, Ron Youvan wrote:
> > richard N7RC courtway wrote:
> >
> >> Lots of information around concerning the real need to HI-Pot /
> >> Getter glass tubes - especially concerning the popular 3-500 series.
> >> But not so much concerning the same need for Ceramic / External Anode
> >> tubes. How come ?? Do they actually need the same attention - if
> >> not - why not ??
> > You can't run the finned plate of an air cooled plate orange or
> red, so the MFGs spot weld
> > gettering washers and disks to the leads between the base and under
> side the elements.
> > (operating the plate red would damage the metal to ceramic seal)
>
>... and the thermal "mass" of an external anode tube is huge compared
>with the relatively small internal anode on something like a 572B or a
>3-500Z... hence which the same amount of kinetic energy make a 3-500Z
>glow orange but only raises the temprature of a 4CX1000 or 8877 by say
>50 degrees.
>
>Mike
>
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