Hi I'm guessing that some kapton tape will get used at the junctions to take care of that issue.
Bob On Dec 25, 2009, at 12:04 AM, Bruce Griffiths wrote: > Another thing to watch out for is circulating currents due to thermal emfs > with the aluminium to steel contacts. > Such thermoelectric currents will in turn generate a magnetic field. > > > > Bruce > > Bob Camp wrote: >> Hi >> >> The big hitters for heat outside the physics package seem to be the RF >> excitation and the microwave generation "stuff". The regulators will warm >> things up if you run high voltage into them, but I would probably not do >> that. >> >> I don't believe that putting multiple swimming pools into the basement, >> mercury filled or otherwise was ever a real candidate for a solution. It is >> kind of interesting to see just how big the "jug of water" would have to be. >> >> Right now my leading candidate is a multi layer aluminum / steel enclosure >> with a "point short" between each of the layers to keep the heat rise under >> control. Cool the "baseplate" with recirculating water and a cheap (< $50) >> pump. Throw in a fan and radiator to cool the water to room temperature. >> Servo the temperature with "what ever" at the point shorts. Monitor the >> temperature as best you can. >> >> The main "what ever" still in there are TE coolers. A quick look suggests >> that +12 heats and -12 cools. In between the two it's not clear that much >> happens (maybe it does ...). Even if it does not, I haven't dug deep enough >> to see if something like current drive takes care of the dead band issue. >> >> Some math. It's late, but I think this is about right: >> >> 1) 4 layers >> 2) Shorts at 2 C/W >> 3) 10 W "inside" >> 4) 80 C heat rise - not going to work >> >> If I stick with 4 layers, 10 W, and a 15 C rise then the shorts need to be ~ >> 0.38 C/W. A 15C rise gets me to 40C which looks reasonable based on the app >> notes I have read on the rubidiums. >> >> If the basement moves up 5 C then I'm cold pumping 1/3 of the 10W. Same >> thing in reverse if the basement drops 5 C. Both are unlikely to happen as >> long as there isn't a catastrophic failure of the HVAC. >> >> If I go to a air cooled baseplate heat sink, it's thermal resistance is >> going to have to come out of the budget. My *guess* is that's going to be >> more involved than a simple pump and some plastic tubes. >> >> Bob >> >> On Dec 24, 2009, at 10:46 PM, Hal Murray wrote: >> >> >>> li...@cq.nu said: >>> >>>> The original intent was to simply take an existing "cheap" rubidium >>>> and do simple things to it. Tearing it into pieces and redesigning >>>> parts of it was not anything I originally contemplated. The tight >>>> integration of the physics package to the electronics would make this >>>> a fairly involved process. >>>> >>> Sure, but if we are discussing digging a hole big enough for a ton of >>> mercury, then taking apart a tightly integrated package seems worth >>> considering. >>> >>> I expect the packaging might be reasonable for this purpose. After all, the >>> designers probably wanted to keep that heat away from the electronics. >>> >>> >>> >>> -- >>> These are my opinions, not necessarily my employer's. I hate spam. >>> >>> >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
