[time-nuts] Hydrogen Maser KIT! Update #1

[Mark Kahrs]

There's been a  fair number of papers from Hahvahd about bulb coating for
masers.  Interestingly enough, here's a patent:

http://www.google.com/patents/US3859119

from 1972.

I had to figure this out, but Yuri is referring to flourophosgene a.k.a.
carbonyl flouride.

If you'd like to read a really nice detailed paper on bulb coating for Rb
cells, try this one out:

http://walsworth.physics.harvard.edu/publications/1999_Phillips_otherdoc.pdf


On Mon, Nov 3, 2014 at 3:46 PM, Chuck Harris <cfharris at erols.com> wrote:

> Hi Yuri,
>
> It would be a very good idea to keep the temperature of
> the nichrome wire low, and that might be the biggest problem
> with the vacuum deposition technique... the wire could get
> too hot in some places, and stay too cool in others.
>
> A really uncontrolled experiment, aka: a thermal wire stripper,
> gets covered with white snow from the teflon vapor released
> while stripping teflon wire.
>
> -Chuck Harris
>
> Yuri Ostry wrote:
>
>> Hello,
>>
>> Monday, November 3, 2014, 5:40:30, Chuck Harris wrote:
>>
>> C> I would think that making the teflon coating would be pretty easy.
>>
>> C> What I would try is to put a nichrome boat, and some teflon into the
>> C> vessel, and pull it down to a good vacuum.  Then heat up the boat,
>> C> and the teflon should sublime, and condense on the walls of the
>> C> vessel.
>>
>> C> The nichrome boat could be something as simple as wrapping the nichrome
>> C> into a solenoid form around some teflon rod.
>>
>> C> -Chuck Harris
>>
>> Teflon decomposes at high temperatures, releasing some sublimate and a
>> lot of really nasty chemicals, like fluorfosgen. There is a chance
>> that really thin even coating can be produced this way, but a lot of
>> experimentation would be needed.
>>
>> I would try to take samples of PTFE-insulated hookup wire (from different
>> manufacturers, say white Alfa or Belden wire and russian MGTF wire that
>> use
>> slightly different PTFE formula) and try to make coating inside glass
>> tube samples, using copper wire as heater by itself.
>>
>> I doubt that there will be good results, though. "Classic" way with
>> thin slurry application and heating to teflon melt point to make solid
>> film may be more "realistic".
>>
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