[time-nuts] COTS cesium standard physics package life
Ruslan Nabioullin
rnabioullin at gmail.com
Thu Sep 29 12:07:19 UTC 2016
Hi, I'm unable to fully grasp the lifetime specifications of typical
COTS cesium standard physics packages, for both old and new designs.
For example, the documentation of an older HP standard specifies a shelf
life of two years if the ion pump is operated two or three times per
year, yet at the same time the ``beam tube warranty'' period is three
years. Does this mean that if the physics package is fully operating
(i.e., LOOP OPEN, OPER, or LTC), then it's guaranteed to last at least
three years, but if it's completely shut down, except for vacuum
maintenance sessions (using the mode CS OFF) two or three times per
year, it will last only two years? Also, what will the expected
lifetime of the package be if the standard is kept as a reserve,
specifically, continuously-powered with the mode set to CS OFF (so
continuous vacuum maintenance), and activated or deactivated to or from,
resp., OPER, as needed, excl. the time spent fully operating (i.e., in
this case, the time spent in the OPER mode doesn't count)?
Thanks in advance,
Ruslan
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