[time-nuts] HP5065A reversing the C-field ?
Poul-Henning Kamp
phk at phk.freebsd.dk
Sat May 2 16:09:19 UTC 2020
In physical terms, the direction the C-field does not matter in a
atomic frequency standard, it just has to be of constant magnitude.
The ambient magnetic fields adds to the C-field, most notably the
geomagnetic field, and any (strong) nearby DC currents.
Some of the "telecom" rubidiums reverses the C-field periodically,
presumably to average out any stray magnetic fields which get past
their puny, if any, mu-metal shielding.
The HP5065A is stationary and shielded, so the stray fields should
be small and almost constant, and implementing periodc reversal would
likely convert it from a frequency normal to geomagnetometer.
But if one reversed the C-field, by swapping the wires to the solenoid,
and measured the frequency-shift, wouldn't that give a measurement of
how good the magnetic shield works ?
Has anybody ever tried this ?
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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