🚀 go-pugleaf

In article <1992Jul28.075319.9973@fs7.ece.cmu.edu> snyder@henry.ece.cmu.edu (John Snyder) writes:
>In article <7926@dirac.physics.purdue.edu> parks@gibbs.physics.purdue.edu (Chris Parks) writes:
>>
>>What is a good material (good=price + availability) which is
>>an electrical insulator and a good conductor of heat?
>>
>>It will be used at temperatures as low as 4.2 Kelvin and it needs
>>to hold up to about 200 volts / mm, heat conductivity needs to
>>be comparable to copper.  Does it exist?
>>
>>Note: Diamond may be ideal but not practical!


>Sapphire has been mentioned to me as such a material.  You do not mention in
>what form: shape, size this material must be or how much of it you need.  
>I believe that you can get man-made sapphire substrates.  They are probably
>not cheap, but surely cheaper than diamond.
>

Actually, Sapphire is quite cheap.  A polished two-inch wafer costs
about 125 bucks.  It is used in UHV viewports up to at least 4 inch 
diameters.  Berylium oxide is another option.  Not transparent, but
a great heat conductor.  Deadly toxic though.

Peter Rosenthal


-- 
Peter Rosenthal       Email rosenthal@cmg.eeel.nist.gov