[time-nuts] Can anyone spare an LPRO lamp?

Bob Camp lists at cq.nu
Tue Sep 29 17:03:37 UTC 2009


The exact "fill" in the lamp is one of those things the Efratom does not
like to talk about. Best guess is that there is more than just Rb in there.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Neville Michie
Sent: Tuesday, September 29, 2009 12:19 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Can anyone spare an LPRO lamp?

The lamp in the LPRO may have a significant difference from the other  
The pictures of lamps on Tom's ? page show that each of them has a  
side arm
which is most helpful for filling.
The side arm is left out in the cold so any excess rubidium condenses  
as a reserve supply. The vapour (vapor) pressure of rubidium is then  
by the temperature of the side arm.
The LPRO does not seem to have a side arm, at least I did not see one  
I looked at mine, and if it has it does not seem to protrude out of  
the oven.
  I can not guess how they filled it. Remember it is mainly empty, I  
think, although
  it may have an inert gas in it besides the rubidium vapour. With  
the right amount
of rubidium in the tube the pressure will always be right, the only  
problem is that
alkali vapours are infamous for diffusing into warm glass, and with  
no backup supply
of rubidium the vapour pressure will drop and the fire will go out.
Can anyone tell me what the lamp looks like? Mine seems to be a  
simple glass

cheers, Neville Michie

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