On Mon, 18 Oct 2004, Glenn Jones wrote:

> Hello,
> This is a bit of a long shot, but does anyone know any good references for
> information relating vacuum pressure to thermal conductivity in a Dewar? I
> am building a small Dewar with a multistage thermoelectric cooler inside
> and I need to calculate some theoretical values for the heat load at
> different pressures. I have tried numerous google searches, but basically
> all I have found is that people genearlly use pressures of 10 millitorr or
> less
> Thank you,
> Glenn

Afaik at about that pressure loss by radiation is significantly larger 
than loss by convection so vacuum counts less and less for heat loss.

Peter
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