Fwd: Re: [AMPS] RE: Graphite Anodes

[Bill Fuqua]

    This is curious. Graphite (carbon) chemically reacts with oxygen to produce
2 gasses Carbon Monoxide and Carbon Dioxide.  Unlike most metals it does not
form oxides  on the surface which may later decompose.
    I suspect that the vacuum advantage of carbon is that when baking out 
the tubes
the O2 is converted to CO and CO2 which can be easily pumped out. The other
disadvantage with metals is that their oxides are usually insulators which 
produce
other problems, at least in high vacuum systems used in physics research.
These insulators can become charged and then produce fields that in turn
will affect the sensitive experiments within the instrument. We often coat
metal components in sensitive areas with DAG ( as graphite paint) to 
prevent that problem.
    I also find it hard that you can improve the black body radiation 
properties of  graphite much.

73
Bill wa4lav


William L. Fuqua  III , P.E.  EE
Department of Physics and Astronomy
CP 177 Chemistry Physics Building
University of KY
Lexington, KY 40506-0055
Phone 859 257-4155


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