[time-nuts] Cheap Rubidium (heatpipe cooling for)

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Dec 24 22:54:08 UTC 2009


Magnus Danielson wrote:
> Hal Murray wrote:
>>> A heat pipe might work if the fluid had a sufficiently low boiling
>>> point. The rubidium isn't terribly tolerant of high temperatures, and
>>> I'm going to pick up some heat rise as I put it inside some baffles /
>>> shields. You need to find something that fits a fairly narrow window.
>>
>> This is all backwards.
>>
>> The main reason the typical Rubidium box needs a serious heat sink is 
>> that there is an active heater inside it heating up the lamp to get 
>> it up to operating temperature.  That part of the system better be 
>> "tolerant" of high (enough) temperature.
>
> ... or a less heat-producing alternative could be used. The 
> Rubidium-lamp produces two wavelengths of which one is filtered by a 
> Rubidium-filter which leaves the final pumping wavelength. This is 
> what a laser diode could supply instead.
>
>> Maybe things would be a lot better/simpler if the heating/cooling we 
>> have been discussing were split into two sections.  One for the lamp 
>> assembly, and a second for the electronics.
>
> Most of the discussion has been on thermal isolation of the entier 
> units. Not what needs generates temperature and what requires 
> temperature stability etc.
>
>> Anybody know what the thermal coefficient of the lamp is relative to 
>> the electronics?
>
> I am not sure I know what you mean by this...
>
> Cheers,
> Magnus
Probably the temperature fluctuations of the absorption cell is more 
significant than that of the lamp itself.
The effects to consider are:

1) The effect of temperature fluctuations of the electronics.
Probably dominated by the short term temperature fluctuations of the 
internal crystal oscillator.

2) The effect of temperature fluctuations of the Rubidium lamp and 
associated optical filters.

3) The effect of temperature fluctuations on the Rubidium absorption 
cell hyperfine transition frequency.



Bruce




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