Hi Aging in the short term tends to be dominated by equilibrium issues. Some of them can have “many months” sort of time constants . That makes any study like this pretty hard to do.
Worst case is when a short term effect has the opposite sign from the long term. You go through a really flat region .... for a while ... Bob Sent from my iPhone > On Aug 14, 2018, at 12:53 PM, Skip Withrow <[email protected]> wrote: > > Hello Time-Nuts, > > For the past several months I have been investigating the change in > aging rate of a rubidium oscillator with change in pressure. This has > been done with an operating oscillator in a temperature controlled > vacuum chamber. > > Obviously, the frequency changes (a lot) with pressure changes due to > 'oil canning' of the rubidium cell. What I have been interested in is > the behavior of the change in frequency (aging) with pressure. If an > inflection point can be found or the aging minimized there is > potential to have an oscillator that performs very well. > > The only 'change in aging' mechanism that I have run across is helium > permeation of the rubidium cell. FEI has a paper published when the > oscillators for the first GPS satellites were being developed. > Temex/Spectratime is the only company that I have seen that addresses > this in their specifications. > > So far, I have been operating in the 10-50 Torr range and have seen a > very definite trend on aging with pressure. But there is much more > research to do. My big question is - what pressure related mechanism > might affect aging? I would think that helium permeation would have a > somewhat longish time constant. > > I'm wondering if anyone from the group has some experience in this area? > > Thanks in advance for any help. > > Regards, > Skip Withrow > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
