[time-nuts] HP5061 Cesium ion pump question

[paul swed]

Exactly filaments cold. KE5FX has great details on doing this for a Cs
tube. Google his details.
Regards
Paul.

On Fri, Dec 4, 2020 at 3:24 AM Dana Whitlow <k8yumdoober at gmail.com> wrote:

> I wonder if it might be good to power up the ion pump with the heaters
> cold, then
> after the ion current trails off to nil, begin operating the filaments at
> very low voltage
> (and all other voltages off except for the ion pump) and gradually ramp the
> the filament
> voltages up towards normal operating voltage, doing so slowly enough that
> the ion
> pump never trips off.  Then, once things have settled down at normal
> filament voltage,
> set up and fire up the whole instrument.  I think this might be easier on
> both the filaments
> and the ion pump.
>
> Comments?
>
> Dana
>
>
> On Thu, Dec 3, 2020 at 8:34 PM <vilgotch1 at gmail.com> wrote:
>
> > Thanks very much for this info Corby. It explains the behaviour of my
> spare
> > 5061A perfectly.
> >
> > It also raises the question of what I could do with the spare tube I
> have.
> > I
> > can connect a +3500V supply to the ion pump but that won't do anything
> > about
> > any gas molecules adsorbed onto the filaments as you described. Is it
> worth
> > powering up the filaments to get rid of them or can that be left for some
> > indefinite time in the future when the tube could be reinstalled in a
> > 5061A?
> >
> > Morris
> >
> > -------------------------------------------
> > Date: Wed, 2 Dec 2020 11:06:22 -0800
> > From: <cdelect at juno.com>
> > To: time-nuts at lists.febo.com
> > Subject: [time-nuts] HP5061 Cesium ion pump question
> >
> > 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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