[time-nuts] HP5061 Cesium ion pump question

[paul swed]

Corby that explains what I have been seeing and wondering about over the
years I have had Cesiums. Get it all pumped down and then the next time I
get those bursts. I am letting a recent 5061 pump down. It seems to get
really dirty each time I start it but gets down to 16 on the meter after
some 48 hours. I run the Cesiums at least per quarter.
Really appreciate this insight you shared.
Thank you.
Paul
WB8TSL

On Wed, Dec 2, 2020 at 2:27 PM <cdelect at juno.com> wrote:

> The gettering in the tube is only for capturing any stray Cesium atoms
> that don't get caught in the main gettering patch. If the gettering fails
> or gets too loaded up then the Cesium background level will get too high
> causing poor SN.
>
> The ion pump is for any gases.
>
> When a tube is off for extended times any gas atoms lingering or leaking
> slowly into the tube than happen to impinge on either the mass
> Spectrometer filament or the Cs oven filaments get capture by the
> filaments. They function as excellent getters!  (this even if the ion
> pump is on)
>
> Now this is not by design but results in the filaments being "loaded"
> with the gas atoms.
>
> Then when you turn the tube on the filaments light up and expell a burst
> of gas.
>
> This of coarse causes the ion pump current to rise and trips off the
> filaments,
>
> Once the ion pump removes the burst the cycle repeats until the filaments
> have expelled the trapped gases.
>
> Then the ion pump can handle the load and pump the tube down completely.
>
> Cheers,
>
> Corby
>
>
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