[time-nuts] HP5061B Cesium Oven Properties
paulswedb at gmail.com
Thu Mar 30 09:40:09 EDT 2017
Donald some great work you are doing and since many of us have 5061s that
are on fumes this is a great way to further extend the life while operating.
The run time may be different for various ovens. If its 83c then it was a
high flux tube. They burned up the Cs at a fasterate to give a better
signal to noise. These are typically option 004 units.
Frankenstein has the fewest Cs and would be an ideal candidate for a cycled
oven since currently it uses a home brew DC oven controller and is quite
Funny this is like restoring an old 1960s class car. The tricks that are
On Wed, Mar 29, 2017 at 11:02 PM, Donald E. Pauly <trojancowboy at gmail.com>
> The cesium oven acts as an evaporator for liquid cesium which melts at
> 28.5° C. One of our beam tubes has 83°C for its operating
> temperature. It also calls for a A11R11 and A11R12 of 3.83 K and
> 42.2K which is 3.51K. Oven power is specified at 2.2V and 0.9A or
> 1.98 W. Being in a vacuum allows less heater power. Oven temperature
> is very critical to provide enough cesium in the beam but at the same
> time not wasting it. A switching power supply runs the oven as well
> as providing 1.2V at 3.4A to the hot wire ionizer which is 4.08 Watts.
> It took 10 minutes from a cold start for the cesium oven current to
> drop from being pegged to its final value. After stabilizing, we
> connected a 470 Ω across the thermistor from the beam tube to shut off
> the heater. Here is the beam current versus time in minutes as the
> oven cooled off. Note that it took 17 minutes for the beam current to
> drop to half value. Continuous lock was maintained.
> time beam
> 0 20
> 3 18
> 5 17
> 8 16
> 9 15
> 11 14
> 14 12
> 17 11
> We then reapplied oven power and watched the beam current increase and
> oven current decrease.
> time beam oven
> 0 16 over 50
> 3 20 missed
> 5 22 missed
> 6 21 15
> 8 20 15
> 10 20 14
> Finally we applied oven power from a 35 minute cooldown and waited for
> lock. If the oscillator oven is stable, the cesium oven will achieve
> lock in only two minutes. There is no need to waste cesium if you do
> not need the instrument to be locked.
> time beam status
> 0 8 unlock
> 2 10 lock
> 3 12 lock
> 4 18 lock
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