Yes, but it's not diffusion they're seeing or looking for. The reason for helium is that mass spectrometers that look for helium are easy and cheap to make (relatively speaking, limited to leak checking of course). That and helium penetrates very very tiny leaks rapidly so it's fairly ideal for this application.
The long straight slots on Conflat connectors are for the helium nozzle. They're designed to allow helium to be sprayed right at the seal and go around the entire circumference of the copper seal. -Bob On Tue, Sep 20, 2011 at 1:10 PM, Tijd Dingen <tijddin...@yahoo.com> wrote: > Yeah, I was wondering about that. There's a reason they use helium to > search for leaks on vacuum chambers. Those pesky small atoms go > everywhere... > > > > ________________________________ > From: J. Forster <j...@quikus.com> > To: Discussion of precise time and frequency measurement < > time-nuts@febo.com>@qkmail9.01trend.com > Sent: Tuesday, September 20, 2011 9:00 PM > Subject: Re: [time-nuts] Making a 10811 better > > Helium in contact with Dewar walls is a very bad idea. He diffuses through > many glasses and will completely destroy the vacuum in a Dewar in hours. > > -John > > ================= > > > > Depends what you mean by "much higher". Helium has almost 6 times higher > > thermal conductivity. Hydrogen is higher, but has certain drawbacks. ;-) > > > > regards, > > Fred > > > > > > > > ________________________________ > > From: Dick Moore <rich...@hughes.net> > > To: time-nuts@febo.com > > Sent: Tuesday, September 20, 2011 8:39 PM > > Subject: Re: [time-nuts] Making a 10811 better > > > > Is there a relatively inert gas that has much higher thermal conductivity > > than air? Then a flask makes sense and is not the size of the basement... > > > > Dick Moore > > > > > > On Sep 20, 2011, at 5:00 AM, time-nuts-requ...@febo.com wrote: > > > >> ------------------------------ > >> > >> Message: 2 > >> Date: Mon, 19 Sep 2011 18:21:30 -0700 > >> From: ed breya <e...@telight.com> > >> To: time-nuts@febo.com > >> Subject: [time-nuts] Making a HP 10811 better > >> Message-ID: <201109200121.p8k1lgse015...@mail30c40.carrierzone.com> > >> Content-Type: text/plain; charset="us-ascii"; format=flowed > >> > >> One last thing regarding oil-filling. My previous comment was made > >> picturing oil inside the oscillator block only - not outside, or > >> between the outer parts - if there is a resistance wire heater (I > >> think it's heated with Qs only on the 10811) it is held together with > >> various tapes and adhesives that could soften or dissolve. Also, the > >> insulation would not insulate very well of saturated with oil, and > >> could possibly soften or break down somehow. I would not recommend > >> dunking the whole thing in a vat of oil. > >> > >> And one final, final note: If oil is somehow effectively contained in > >> the oscillator block, then a void (bubble) of some sort, or an > >> expansion facility or vent would be needed to relieve the pressure > >> changes during warmup. Otherwise, when started up, the expanding oil > >> would have to either leak out, or deform (or damage) something. This > >> would be equivalent to dramatically increasing barometric pressure, > >> and certainly effect the oscillator frequency. > >> > >> Ed > >> > >> > >> > >> > >> ------------------------------ > >> > >> Message: 3 > >> Date: Mon, 19 Sep 2011 23:20:28 -0600 (MDT) > >> From: "Don Latham" <d...@montana.com> > >> To: "Discussion of precise time and frequency measurement" > >> <time-nuts@febo.com> > >> Subject: Re: [time-nuts] Making a HP 10811 better > >> Message-ID: > >> <d850d565aabe9422dd4172b9c904d5d4.squir...@webmail.montana.com> > >> Content-Type: text/plain;charset=iso-8859-1 > >> > >> Ah well. Just a thought. I was thinking of simply dumping the whole > >> thing into a picnic jug full of baby oil :-) > >> Sorta scatterbrained, but I have seen mentioned on the list a basement > >> sized steel block ... > >> Don > >> > >> ed breya > >>> One last thing regarding oil-filling. My previous comment was made > >>> picturing oil inside the oscillator block only - not outside, or > >>> between the outer parts - if there is a resistance wire heater (I > >>> think it's heated with Qs only on the 10811) it is held together with > >>> various tapes and adhesives that could soften or dissolve. Also, the > >>> insulation would not insulate very well of saturated with oil, and > >>> could possibly soften or break down somehow. I would not recommend > >>> dunking the whole thing in a vat of oil. > >>> > >>> And one final, final note: If oil is somehow effectively contained in > >>> the oscillator block, then a void (bubble) of some sort, or an > >>> expansion facility or vent would be needed to relieve the pressure > >>> changes during warmup. Otherwise, when started up, the expanding oil > >>> would have to either leak out, or deform (or damage) something. This > >>> would be equivalent to dramatically increasing barometric pressure, > >>> and certainly effect the oscillator frequency. > >>> > >>> Ed > >>> > >>> > >>> _______________________________________________ > >>> 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. > >>> > >> > >> > >> -- > >> "Neither the voice of authority nor the weight of reason and argument > >> are as significant as experiment, for thence comes quiet to the mind." > >> R. Bacon > >> "If you don't know what it is, don't poke it." > >> Ghost in the Shell > >> > >> > >> Dr. Don Latham AJ7LL > >> Six Mile Systems LLP > >> 17850 Six Mile Road > >> POB 134 > >> Huson, MT, 59846 > >> VOX 406-626-4304 > >> www.lightningforensics.com > >> www.sixmilesystems.com > >> > >> > >> > >> > >> > >> ------------------------------ > >> > >> _______________________________________________ > >> time-nuts mailing list > >> time-nuts@febo.com > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> > >> End of time-nuts Digest, Vol 86, Issue 55 > >> ***************************************** > > > > > > _______________________________________________ > > 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. > _______________________________________________ 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.
