Re: [time-nuts] Hydrogen Maser KIT! Update #1
There's been a fair number of papers from Hahvahd about bulb coating for masers. Interestingly enough, here's a patent: http://www.google.com/patents/US3859119 from 1972. I had to figure this out, but Yuri is referring to flourophosgene a.k.a. carbonyl flouride. If you'd like to read a really nice detailed paper on bulb coating for Rb cells, try this one out: http://walsworth.physics.harvard.edu/publications/1999_Phillips_otherdoc.pdf On Mon, Nov 3, 2014 at 3:46 PM, Chuck Harris cfhar...@erols.com wrote: Hi Yuri, It would be a very good idea to keep the temperature of the nichrome wire low, and that might be the biggest problem with the vacuum deposition technique... the wire could get too hot in some places, and stay too cool in others. A really uncontrolled experiment, aka: a thermal wire stripper, gets covered with white snow from the teflon vapor released while stripping teflon wire. -Chuck Harris Yuri Ostry wrote: Hello, Monday, November 3, 2014, 5:40:30, Chuck Harris wrote: C I would think that making the teflon coating would be pretty easy. C What I would try is to put a nichrome boat, and some teflon into the C vessel, and pull it down to a good vacuum. Then heat up the boat, C and the teflon should sublime, and condense on the walls of the C vessel. C The nichrome boat could be something as simple as wrapping the nichrome C into a solenoid form around some teflon rod. C -Chuck Harris Teflon decomposes at high temperatures, releasing some sublimate and a lot of really nasty chemicals, like fluorfosgen. There is a chance that really thin even coating can be produced this way, but a lot of experimentation would be needed. I would try to take samples of PTFE-insulated hookup wire (from different manufacturers, say white Alfa or Belden wire and russian MGTF wire that use slightly different PTFE formula) and try to make coating inside glass tube samples, using copper wire as heater by itself. I doubt that there will be good results, though. Classic way with thin slurry application and heating to teflon melt point to make solid film may be more realistic. ___ 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] Hydrogen Maser KIT! Update #1
Coating the bulb with Teflon involves coating the inside with a Teflon liquid aqueous dispersion, letting it dry, and then curing it in an oven at 380 to 400 degrees C for around 30 minutes while circulating dry air through the bulb. A little bit intricate but doable. Main concern is getting the bulb surface absolutely clean before coating. A hydrofluoric acid rinse is a must! Cheers, Corby ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
I guess I have to wonder why Corby felt it necessary to remove the coating. I think it was always motley looking. And, If it was very easy to remove, and I suspect it would be, it is probably equally easy to apply. -Chuck Harris Bob Camp wrote: Hi On Nov 2, 2014, at 9:49 PM, Chuck Harris cfhar...@erols.com wrote: In retrospect, it looks like their teflon coating is even simpler done. It looks like what they did is take very finely sectioned teflon powder, and make a slurry in probably acetone. They cleaned the vessel very well first with acetone and second, probably a little distilled water to etch the glass slightly, and then put the teflon/acetone slurry in the bulb, slooshed it around a bit to cover the walls, and then drained it all out. When the acetone evaporated, the teflon powder would remain on the walls. If it’s that simple, then going crazy over the coating as I was suggesting isn’t really needed. Bob ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Good god, be core full with that. Did you find any references to sputtering the coating. I would think this would give you a more even and more adhesive coating. Some chemical engineering labs at universities do that and would probably coat it for free. I know Dr. Viljoen at Nebraska-Lincoln has a setup for that. He usually sputters metal but I think a Teflon target would work the same. Sent from mobile On Nov 3, 2014, at 10:09 AM, cdel...@juno.com cdel...@juno.com wrote: Coating the bulb with Teflon involves coating the inside with a Teflon liquid aqueous dispersion, letting it dry, and then curing it in an oven at 380 to 400 degrees C for around 30 minutes while circulating dry air through the bulb. A little bit intricate but doable. Main concern is getting the bulb surface absolutely clean before coating. A hydrofluoric acid rinse is a must! Cheers, Corby ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Our standard cleaning regimen for glass (as I recall from when I was in gradual school), was: 1) wash in detergent in hot water 2) dip (not soak!) in 10% HF/distilled water solution 3) neutralize in dilute NaOH (KOH) water solution 4) rinse in distilled water And for a final clean: 1) scrub with detergent in hot water 2) rinse in very hot water 3) rinse with distilled water 4) rinse with pure methanol Aqueous and teflon don't seem to go together in my mind. I think my first choice would be vacuum deposition, which is very easy. Second choice would be acetone and teflon dispersion followed by a 200C high vacuum bake. I have a strong feeling that simply spraying from a can of teflon dry lubricant followed by a 200C high vacuum bake would work just as well. It seems to be a hexane/butane dispersion of teflon powder, and nothing else. -Chuck Harris cdel...@juno.com wrote: Coating the bulb with Teflon involves coating the inside with a Teflon liquid aqueous dispersion, letting it dry, and then curing it in an oven at 380 to 400 degrees C for around 30 minutes while circulating dry air through the bulb. A little bit intricate but doable. Main concern is getting the bulb surface absolutely clean before coating. A hydrofluoric acid rinse is a must! Cheers, Corby ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
On Mon, 03 Nov 2014 00:39:24 +0100 Magnus Danielson mag...@rubidium.dyndns.org wrote: It is worth knowing that active masers have a span for how the hydrogen in-flux will make it oscillate or not. Too little or too high, and the oscillation will die off. It may be one of the things to tune up if you got an older one which needs a bit of good old Love, Tender and Care. BTW: I always ment to ask, what makes H-Masers stop when there is too much hydrogen? I can understand too little H causes the system not having enough atoms to probe (or not getting enough energy into the system for active masers), but i don't understand the too many case. Attila Kinali -- I pity people who can't find laughter or at least some bit of amusement in the little doings of the day. I believe I could find something ridiculous even in the saddest moment, if necessary. It has nothing to do with being superficial. It's a matter of joy in life. -- Sophie Scholl ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
On Sun, 02 Nov 2014 21:49:34 -0500 Chuck Harris cfhar...@erols.com wrote: They cleaned the vessel very well first with acetone and second, probably a little distilled water to etch the glass slightly, Distilled water etches glass? Really? Attila Kinali -- I pity people who can't find laughter or at least some bit of amusement in the little doings of the day. I believe I could find something ridiculous even in the saddest moment, if necessary. It has nothing to do with being superficial. It's a matter of joy in life. -- Sophie Scholl ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Yes, really. Ever see a double pane insulated glass door that looks white and frosted on the inside? That is due to water vapor that found its way between the panes, and condensed. Because the inside glass is about as clean and free of dirt (minerals) as the manufacturer could make it, the condensed (distilled) water leaches out silicon, etching the glass. Nature abhors a vacuum. In the case of putting a teflon coating inside of the bottle, you want the sides of the bottle to have lots of nooks and crannies (at a molecular level) for the teflon to mechanically grip onto... So, it helps to etch it a little bit. HF will do the job very quickly, but if you have a source of well polished distilled/dionized water, you can etch it that way as well... it just takes a little longer. -Chuck Harris Attila Kinali wrote: On Sun, 02 Nov 2014 21:49:34 -0500 Chuck Harris cfhar...@erols.com wrote: They cleaned the vessel very well first with acetone and second, probably a little distilled water to etch the glass slightly, Distilled water etches glass? Really? Attila Kinali ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
I would presume the usual reason is you want enough hydrogen to resonate at the desired microwave frequency, but not so much that you wreck the Q (spread the line width) with excess collisions. -Chuck Harris Attila Kinali wrote: On Mon, 03 Nov 2014 00:39:24 +0100 Magnus Danielson mag...@rubidium.dyndns.org wrote: It is worth knowing that active masers have a span for how the hydrogen in-flux will make it oscillate or not. Too little or too high, and the oscillation will die off. It may be one of the things to tune up if you got an older one which needs a bit of good old Love, Tender and Care. BTW: I always ment to ask, what makes H-Masers stop when there is too much hydrogen? I can understand too little H causes the system not having enough atoms to probe (or not getting enough energy into the system for active masers), but i don't understand the too many case. Attila Kinali ___ 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] Hydrogen Maser KIT! Update #1
I'd be tempted to experiment with other methods of bulb coating but the time and effort in disassembly, re assembly and testing is so great that I'm going to use a tried and true method to increase the chances of success! It's definitely NOT just as simple as screwing in a different light bulb and trying again! Cheers, Corby ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Hello, Monday, November 3, 2014, 5:40:30, Chuck Harris wrote: C I would think that making the teflon coating would be pretty easy. C What I would try is to put a nichrome boat, and some teflon into the C vessel, and pull it down to a good vacuum. Then heat up the boat, C and the teflon should sublime, and condense on the walls of the C vessel. C The nichrome boat could be something as simple as wrapping the nichrome C into a solenoid form around some teflon rod. C -Chuck Harris Teflon decomposes at high temperatures, releasing some sublimate and a lot of really nasty chemicals, like fluorfosgen. There is a chance that really thin even coating can be produced this way, but a lot of experimentation would be needed. I would try to take samples of PTFE-insulated hookup wire (from different manufacturers, say white Alfa or Belden wire and russian MGTF wire that use slightly different PTFE formula) and try to make coating inside glass tube samples, using copper wire as heater by itself. I doubt that there will be good results, though. Classic way with thin slurry application and heating to teflon melt point to make solid film may be more realistic. C Bob Camp wrote: Hi It’s been way too many years since my last Maser play session … Will it fire up *without* the Teflon coating on the bulb? Yes it works *better* with the Teflon (less wall interaction). Getting the bulb re-coated might be a major pain. It does look ugly in it’s current state. I’m wondering about just stripping the bulb and then seeing what works and what does not. Bob C ___ C time-nuts mailing list -- time-nuts@febo.com C To unsubscribe, go to C https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts C and follow the instructions there. -- Best regards, Yuri mailto:y...@ostry.ru ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Hi Corby, Just curious, how did you remove the original coating, and why? -Chuck Harris cdel...@juno.com wrote: I'd be tempted to experiment with other methods of bulb coating but the time and effort in disassembly, re assembly and testing is so great that I'm going to use a tried and true method to increase the chances of success! It's definitely NOT just as simple as screwing in a different light bulb and trying again! Cheers, Corby ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Hi Yuri, It would be a very good idea to keep the temperature of the nichrome wire low, and that might be the biggest problem with the vacuum deposition technique... the wire could get too hot in some places, and stay too cool in others. A really uncontrolled experiment, aka: a thermal wire stripper, gets covered with white snow from the teflon vapor released while stripping teflon wire. -Chuck Harris Yuri Ostry wrote: Hello, Monday, November 3, 2014, 5:40:30, Chuck Harris wrote: C I would think that making the teflon coating would be pretty easy. C What I would try is to put a nichrome boat, and some teflon into the C vessel, and pull it down to a good vacuum. Then heat up the boat, C and the teflon should sublime, and condense on the walls of the C vessel. C The nichrome boat could be something as simple as wrapping the nichrome C into a solenoid form around some teflon rod. C -Chuck Harris Teflon decomposes at high temperatures, releasing some sublimate and a lot of really nasty chemicals, like fluorfosgen. There is a chance that really thin even coating can be produced this way, but a lot of experimentation would be needed. I would try to take samples of PTFE-insulated hookup wire (from different manufacturers, say white Alfa or Belden wire and russian MGTF wire that use slightly different PTFE formula) and try to make coating inside glass tube samples, using copper wire as heater by itself. I doubt that there will be good results, though. Classic way with thin slurry application and heating to teflon melt point to make solid film may be more realistic. ___ 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] Hydrogen Maser KIT! Update #1
Chuck, The coating opposite the entrance to the bulb was degraded to the point that it was missing over a large area and the tiny particles of loose Teflon were free to move about in the bulb. (Rolling the bulb you could see a little pile of particles moving about) Since a majority of the hydrogen atoms entering the bulb impact first at the opposite end that would cause a large majority of the atoms in the correct state to be perturbed as well as recombine into molecules. So since the end needed recoating it's best to do the whole thing. Per the question of aqueous dispersions here is an excerpt from Dupont: DuPont Teflon® aqueous dispersions are milky white dispersions of PTFE particles in water, stabilized by wetting agents. Cheers, Corby ___ 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] Hydrogen Maser KIT! Update #1
BTW, be careful with micronized teflon... it is a very powerful oxidizer and forms highly combustible/explosive/nasty mixtures with things like powdered or finely divided metals. Particularly magnesium, aluminum, and titanium. More than one machinist has been surprised by exploding swarf. Magnesium/teflon thermite has three times the heat output per gram than iron oxide/aluminum plus releases HF on ignition. ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Hi Corby, I figured that you had a good reason, but from casual viewing of the pictures you provided the coating looked pretty reasonable, so I wondered. The stabilizing agents are the key. Teflon particles don't like water sticking to them all that well, hence their use in things like gortex. The stabilizing agents are probably just a surfactant. I think I might try an experiment with some of the teflon spray lube relative to outgassing... If I can find a few spare hours. I would suggest, that unless you are well experienced in handling such coatings, you try it out on something easier to evaluate, like perhaps a flask. -Chuck Harris cdel...@juno.com wrote: Chuck, The coating opposite the entrance to the bulb was degraded to the point that it was missing over a large area and the tiny particles of loose Teflon were free to move about in the bulb. (Rolling the bulb you could see a little pile of particles moving about) Since a majority of the hydrogen atoms entering the bulb impact first at the opposite end that would cause a large majority of the atoms in the correct state to be perturbed as well as recombine into molecules. So since the end needed recoating it's best to do the whole thing. Per the question of aqueous dispersions here is an excerpt from Dupont: DuPont Teflon® aqueous dispersions are milky white dispersions of PTFE particles in water, stabilized by wetting agents. Cheers, Corby ___ 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] Hydrogen Maser KIT! Update #1
I wonder how well Viton would work? Viton is soluble in acetone and should make coating much easier. ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Eesesh Viton is really bad stuff to play with. When it burns, even a little, it releases HF, and will corrode your bones if you handle it. That said, I love viton O-rings for lots of weird chemicals. I didn't know it was sensitive to acetone, and would have bet it wasn't... learn something new every day. -Chuck Harris Mark Sims wrote: I wonder how well Viton would work? Viton is soluble in acetone and should make coating much easier. ___ 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] Hydrogen Maser KIT! Update #1
See the link for the latest progress! http://www.leapsecond.com/corby/maser/ Cheers, Corby ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Hi It’s been way too many years since my last Maser play session … Will it fire up *without* the Teflon coating on the bulb? Yes it works *better* with the Teflon (less wall interaction). Getting the bulb re-coated might be a major pain. It does look ugly in it’s current state. I’m wondering about just stripping the bulb and then seeing what works and what does not. Bob On Nov 2, 2014, at 4:08 PM, cdel...@juno.com cdel...@juno.com wrote: See the link for the latest progress! http://www.leapsecond.com/corby/maser/ Cheers, Corby ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
On Sun, 2 Nov 2014 16:28:47 -0500 Bob Camp kb...@n1k.org wrote: It’s been way too many years since my last Maser play session … Will it fire up *without* the Teflon coating on the bulb? Yes it works *better* with the Teflon (less wall interaction). Getting the bulb re-coated might be a major pain. According to some of the papers i've read, parafin might be an alternative to Teflon. The interaction of Hydrogen with Teflon is lower than with Parafin, but it might be acceptable (Curiously, if it were a Rb maser, you'd use a parafin coating instead of a Teflon coating). Attila Kinali -- I pity people who can't find laughter or at least some bit of amusement in the little doings of the day. I believe I could find something ridiculous even in the saddest moment, if necessary. It has nothing to do with being superficial. It's a matter of joy in life. -- Sophie Scholl ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Hi Attila, On 11/02/2014 10:43 PM, Attila Kinali wrote: On Sun, 2 Nov 2014 16:28:47 -0500 Bob Camp kb...@n1k.org wrote: It’s been way too many years since my last Maser play session … Will it fire up *without* the Teflon coating on the bulb? Yes it works *better* with the Teflon (less wall interaction). Getting the bulb re-coated might be a major pain. According to some of the papers i've read, parafin might be an alternative to Teflon. The interaction of Hydrogen with Teflon is lower than with Parafin, but it might be acceptable (Curiously, if it were a Rb maser, you'd use a parafin coating instead of a Teflon coating). Parafin was used early, but in the strive to even further increase the interaction time with the hydrogen in the bouncing box, telfon was preferred. In the early days they experimented with different coatings. The goal was to increase the time (and thus narrowing the bandwidth) of interaction before the hydrogen atoms loose state and cause a frequency shift. Rubidium gas cells have similar wall-shift, but advancements have stabilized the wall-shift by buffer-gas selection. A way to estimate the wall-shift is to run different sizes of glas-bulbs, and notice the maser frequency shift. The old hydrogen masers where really experimental platsforms to a much higher degree, but that also meant that validation was done. Then again the cavity shift is there, something that can be measured and compensated as a separate control loop, which has contributed to increase the stability and thus performance. Some hydrogen masers have proven themselves to be much more pressure sensitive than others. Finding the lack of hydrogen masers in my lab disturbing. Cheers, Magnus ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Hi OK, it works better if it bounces off the wall. The line width is narrower. Does it work at all (is there a line you can find) without the coating? Yes you would need to find a paper from the 1960’s to find anybody trying to run one that way. Bob On Nov 2, 2014, at 5:04 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Hi Attila, On 11/02/2014 10:43 PM, Attila Kinali wrote: On Sun, 2 Nov 2014 16:28:47 -0500 Bob Camp kb...@n1k.org wrote: It’s been way too many years since my last Maser play session … Will it fire up *without* the Teflon coating on the bulb? Yes it works *better* with the Teflon (less wall interaction). Getting the bulb re-coated might be a major pain. According to some of the papers i've read, parafin might be an alternative to Teflon. The interaction of Hydrogen with Teflon is lower than with Parafin, but it might be acceptable (Curiously, if it were a Rb maser, you'd use a parafin coating instead of a Teflon coating). Parafin was used early, but in the strive to even further increase the interaction time with the hydrogen in the bouncing box, telfon was preferred. In the early days they experimented with different coatings. The goal was to increase the time (and thus narrowing the bandwidth) of interaction before the hydrogen atoms loose state and cause a frequency shift. Rubidium gas cells have similar wall-shift, but advancements have stabilized the wall-shift by buffer-gas selection. A way to estimate the wall-shift is to run different sizes of glas-bulbs, and notice the maser frequency shift. The old hydrogen masers where really experimental platsforms to a much higher degree, but that also meant that validation was done. Then again the cavity shift is there, something that can be measured and compensated as a separate control loop, which has contributed to increase the stability and thus performance. Some hydrogen masers have proven themselves to be much more pressure sensitive than others. Finding the lack of hydrogen masers in my lab disturbing. Cheers, Magnus ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Bob, Yes, but your Q will suffer. Yes, I've dug out *aged* papers. I was sad to see that JPLs server was taken down before I got to download their wealth of papers. Naturally it happen just after I found out it also had a hydrogen maser section, but also Chuck's papers was lovely to have collected in that form. I have been lazy not to read up on all the hydrogen maser I have in book-form at home... should definitely read up more on those. It is interesting to see how variation on themes got considerable narrower somewhere in the 60/70s shift to the rubidium gas-cell, active and passive hydrogen maser and finally cesium atomic beam. It seems like the knowledge of why they narrowed down to that set is somewhat lost to most, but as one reads up on the old stuff one learns of the variation of these themes that have been tested. The CSAC thus belongs to the gas cell type for instance, with that set of problems, but with a few twist and turns. The fountains (Cs or Rb) is a variation of the beam apparatus, but with a few twist and turns. The ion clocks is really an extension of the hydrogen maser's bouncing box in it's attempt to create long observations times. I think I recall that someone attempted a cryogenic hydrogen maser, which would have benefits as to the lower temperature and thus speed of the hydrogen atoms, producing even longer observations times. Hydrogen being so darn light get into high speed for the temperature. Oh, some doppler benefits would also to be expected. Cheers, Magnus On 11/02/2014 11:20 PM, Bob Camp wrote: Hi OK, it works better if it bounces off the wall. The line width is narrower. Does it work at all (is there a line you can find) without the coating? Yes you would need to find a paper from the 1960’s to find anybody trying to run one that way. Bob On Nov 2, 2014, at 5:04 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Hi Attila, On 11/02/2014 10:43 PM, Attila Kinali wrote: On Sun, 2 Nov 2014 16:28:47 -0500 Bob Camp kb...@n1k.org wrote: It’s been way too many years since my last Maser play session … Will it fire up *without* the Teflon coating on the bulb? Yes it works *better* with the Teflon (less wall interaction). Getting the bulb re-coated might be a major pain. According to some of the papers i've read, parafin might be an alternative to Teflon. The interaction of Hydrogen with Teflon is lower than with Parafin, but it might be acceptable (Curiously, if it were a Rb maser, you'd use a parafin coating instead of a Teflon coating). Parafin was used early, but in the strive to even further increase the interaction time with the hydrogen in the bouncing box, telfon was preferred. In the early days they experimented with different coatings. The goal was to increase the time (and thus narrowing the bandwidth) of interaction before the hydrogen atoms loose state and cause a frequency shift. Rubidium gas cells have similar wall-shift, but advancements have stabilized the wall-shift by buffer-gas selection. A way to estimate the wall-shift is to run different sizes of glas-bulbs, and notice the maser frequency shift. The old hydrogen masers where really experimental platsforms to a much higher degree, but that also meant that validation was done. Then again the cavity shift is there, something that can be measured and compensated as a separate control loop, which has contributed to increase the stability and thus performance. Some hydrogen masers have proven themselves to be much more pressure sensitive than others. Finding the lack of hydrogen masers in my lab disturbing. Cheers, Magnus ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Hi On Nov 2, 2014, at 6:09 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, Yes, but your Q will suffer. Ok, so it might / might not work depending on how high a Q it needs to start functioning. I think I might try it before I went crazy coating he bulb. There will be a *lot* of weird things to debug and associated tear downs to find them. Having a fragile bulb coating to deal with on top of everything else might just be more than can be dealt with. Bob Yes, I've dug out *aged* papers. I was sad to see that JPLs server was taken down before I got to download their wealth of papers. Naturally it happen just after I found out it also had a hydrogen maser section, but also Chuck's papers was lovely to have collected in that form. I have been lazy not to read up on all the hydrogen maser I have in book-form at home... should definitely read up more on those. It is interesting to see how variation on themes got considerable narrower somewhere in the 60/70s shift to the rubidium gas-cell, active and passive hydrogen maser and finally cesium atomic beam. It seems like the knowledge of why they narrowed down to that set is somewhat lost to most, but as one reads up on the old stuff one learns of the variation of these themes that have been tested. The CSAC thus belongs to the gas cell type for instance, with that set of problems, but with a few twist and turns. The fountains (Cs or Rb) is a variation of the beam apparatus, but with a few twist and turns. The ion clocks is really an extension of the hydrogen maser's bouncing box in it's attempt to create long observations times. I think I recall that someone attempted a cryogenic hydrogen maser, which would have benefits as to the lower temperature and thus speed of the hydrogen atoms, producing even longer observations times. Hydrogen being so darn light get into high speed for the temperature. Oh, some doppler benefits would also to be expected. Cheers, Magnus On 11/02/2014 11:20 PM, Bob Camp wrote: Hi OK, it works better if it bounces off the wall. The line width is narrower. Does it work at all (is there a line you can find) without the coating? Yes you would need to find a paper from the 1960’s to find anybody trying to run one that way. Bob On Nov 2, 2014, at 5:04 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Hi Attila, On 11/02/2014 10:43 PM, Attila Kinali wrote: On Sun, 2 Nov 2014 16:28:47 -0500 Bob Camp kb...@n1k.org wrote: It’s been way too many years since my last Maser play session … Will it fire up *without* the Teflon coating on the bulb? Yes it works *better* with the Teflon (less wall interaction). Getting the bulb re-coated might be a major pain. According to some of the papers i've read, parafin might be an alternative to Teflon. The interaction of Hydrogen with Teflon is lower than with Parafin, but it might be acceptable (Curiously, if it were a Rb maser, you'd use a parafin coating instead of a Teflon coating). Parafin was used early, but in the strive to even further increase the interaction time with the hydrogen in the bouncing box, telfon was preferred. In the early days they experimented with different coatings. The goal was to increase the time (and thus narrowing the bandwidth) of interaction before the hydrogen atoms loose state and cause a frequency shift. Rubidium gas cells have similar wall-shift, but advancements have stabilized the wall-shift by buffer-gas selection. A way to estimate the wall-shift is to run different sizes of glas-bulbs, and notice the maser frequency shift. The old hydrogen masers where really experimental platsforms to a much higher degree, but that also meant that validation was done. Then again the cavity shift is there, something that can be measured and compensated as a separate control loop, which has contributed to increase the stability and thus performance. Some hydrogen masers have proven themselves to be much more pressure sensitive than others. Finding the lack of hydrogen masers in my lab disturbing. Cheers, Magnus ___ 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
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Bob, On 11/03/2014 12:19 AM, Bob Camp wrote: Hi On Nov 2, 2014, at 6:09 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, Yes, but your Q will suffer. Ok, so it might / might not work depending on how high a Q it needs to start functioning. I think I might try it before I went crazy coating he bulb. There will be a *lot* of weird things to debug and associated tear downs to find them. Having a fragile bulb coating to deal with on top of everything else might just be more than can be dealt with. It is worth knowing that active masers have a span for how the hydrogen in-flux will make it oscillate or not. Too little or too high, and the oscillation will die off. It may be one of the things to tune up if you got an older one which needs a bit of good old Love, Tender and Care. If you don't dare, I can pass you the appropriate address for it. ;-) Cheers, Magnus ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
On 11/2/14, 3:09 PM, Magnus Danielson wrote: Bob, Yes, but your Q will suffer. Yes, I've dug out *aged* papers. I was sad to see that JPLs server was taken down before I got to download their wealth of papers. Naturally it happen just after I found out it also had a hydrogen maser section, but also Chuck's papers was lovely to have collected in that form. which server was that? I know they rearranged a lot of the technical report servers, and then there was that we don't know if it's export controlled, so take it off line until we figure it out episode. It might still be there, but at a different URL. There's been a significant amount of reorganization within JPL over the past couple years. The same people are probably in the same offices and working with the same colleagues, but the name of the group and/or it's number might have changed. Along with this, there's been a general reorganization of websites to make them more consistent, but it's a when we have time and someone to do it kind of thing for most sections/groups. If you get lucky, there's someone in the group who gets ambitious and does it. The clock guys are in Section 335 (which also does stuff like GPS and measuring the Earth's rotation, and science done with GPS propagation) A bit of googling did not find a public org chart.. there ARE org charts for some of the other sections, but he/she who runs the website has to get the approvals for public release and some sections/groups are more enthusiastic about this than others. The websites are not done by some centralized organization. And, the org charts aren't necessarily up to date (by years, in some cases) ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Yes, but your Q will suffer. Ok, so it might / might not work depending on how high a Q it needs to start functioning. I think I might try it before I went crazy coating he bulb. There will be a *lot* of weird things to debug and associated tear downs to find them. Having a fragile bulb coating to deal with on top of everything else might just be more than can be dealt with. With lower Q, you should still be able to get some usable discriminator action in passive mode. In that scenario an external 1420 MHz pump signal is needed to maintain the stimulated-emission process while new H atoms are coming into the storage bulb. I imagine you'll want to try that at first, in any event, just so you can observe the hardware actually doing something. You should see some signs of frequency discrimination long before you observe self-sustaining radiation, if I understand the process right. Once the line width is narrow enough, through a combination of the right inlet pressure, bulb coating, cavity Q, and intercession from St. Ramsey, thermal energy is enough to sustain the chain reaction. In other words, photons from random spontaneous-emission occurrences will be retained in the cavity rather than lost, leading to coherent stimulated emission without any outside help. But the odds of getting all of those factors right the first time don't seem good. -- john, KE5FX Miles Design LLC ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Jim, On 11/03/2014 12:42 AM, Jim Lux wrote: On 11/2/14, 3:09 PM, Magnus Danielson wrote: Bob, Yes, but your Q will suffer. Yes, I've dug out *aged* papers. I was sad to see that JPLs server was taken down before I got to download their wealth of papers. Naturally it happen just after I found out it also had a hydrogen maser section, but also Chuck's papers was lovely to have collected in that form. which server was that? I know they rearranged a lot of the technical report servers, and then there was that we don't know if it's export controlled, so take it off line until we figure it out episode. meterology.jpl.nasa.gov as far as my memory goes. I *think* it was killed of in a raid against old servers, at least that is what you said was likely when we talked about it some time back. It's a pitty, as it was a neat collection of articles. Such sets on a particular topic is a useful way of finding them, even if the articles is still available in some large archive system, you need to know what search terms will turn out good. These articles where already published at various places, so it should have already been passed through review and been approved for publication. I don't want to bother Chuck to send me *EVERYTHING*, even if I would like to have the full set. It might still be there, but at a different URL. There's been a significant amount of reorganization within JPL over the past couple years. The same people are probably in the same offices and working with the same colleagues, but the name of the group and/or it's number might have changed. Along with this, there's been a general reorganization of websites to make them more consistent, but it's a when we have time and someone to do it kind of thing for most sections/groups. If you get lucky, there's someone in the group who gets ambitious and does it. Yes. The pitty was that someone had already been doing that work, and it was scrapped. Even if the physical machine can be scrapped, the site could continue as just a small side-kick to the larger sites. The clock guys are in Section 335 (which also does stuff like GPS and measuring the Earth's rotation, and science done with GPS propagation) Still not been walking those halls, knocking those doors. A bit of googling did not find a public org chart.. there ARE org charts for some of the other sections, but he/she who runs the website has to get the approvals for public release and some sections/groups are more enthusiastic about this than others. The websites are not done by some centralized organization. And, the org charts aren't necessarily up to date (by years, in some cases) Organization charts aside, it was a nice little site and I miss it. It was good PR for the good work being done. Cheers, Magnus ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Hi On Nov 2, 2014, at 6:59 PM, John Miles j...@miles.io wrote: Yes, but your Q will suffer. Ok, so it might / might not work depending on how high a Q it needs to start functioning. I think I might try it before I went crazy coating he bulb. There will be a *lot* of weird things to debug and associated tear downs to find them. Having a fragile bulb coating to deal with on top of everything else might just be more than can be dealt with. With lower Q, you should still be able to get some usable discriminator action in passive mode. In that scenario an external 1420 MHz pump signal is needed to maintain the stimulated-emission process while new H atoms are coming into the storage bulb. I imagine you'll want to try that at first, in any event, just so you can observe the hardware actually doing something. You should see some signs of frequency discrimination long before you observe self-sustaining radiation, if I understand the process right. Once the line width is narrow enough, through a combination of the right inlet pressure, bulb coating, cavity Q, and intercession from St. Ramsey, thermal energy is enough to sustain the chain reaction. In other words, photons from random spontaneous-emission occurrences will be retained in the cavity rather than lost, leading to coherent stimulated emission without any outside help. But the odds of getting all of those factors right the first time don't seem good. Yes, exactly. Way to many variables to expect it all to “just come together”. To many things like an un-noticed 60 Hz field to mess you up. Not that anyone I know has ever had that problem ….. (in the last say week …). Bob -- john, KE5FX Miles Design LLC ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
In retrospect, it looks like their teflon coating is even simpler done. It looks like what they did is take very finely sectioned teflon powder, and make a slurry in probably acetone. They cleaned the vessel very well first with acetone and second, probably a little distilled water to etch the glass slightly, and then put the teflon/acetone slurry in the bulb, slooshed it around a bit to cover the walls, and then drained it all out. When the acetone evaporated, the teflon powder would remain on the walls. I've seen a nearly identical coating every time I take a can of teflon spray lubricant/mold release, and spray it on something. -Chuck Harris I would think that making the teflon coating would be pretty easy. What I would try is to put a nichrome boat, and some teflon into the vessel, and pull it down to a good vacuum. Then heat up the boat, and the teflon should sublime, and condense on the walls of the vessel. The nichrome boat could be something as simple as wrapping the nichrome into a solenoid form around some teflon rod. -Chuck Harris Bob Camp wrote: Hi It’s been way too many years since my last Maser play session … Will it fire up *without* the Teflon coating on the bulb? Yes it works *better* with the Teflon (less wall interaction). Getting the bulb re-coated might be a major pain. It does look ugly in it’s current state. I’m wondering about just stripping the bulb and then seeing what works and what does not. Bob ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
I would think that making the teflon coating would be pretty easy. What I would try is to put a nichrome boat, and some teflon into the vessel, and pull it down to a good vacuum. Then heat up the boat, and the teflon should sublime, and condense on the walls of the vessel. The nichrome boat could be something as simple as wrapping the nichrome into a solenoid form around some teflon rod. -Chuck Harris Bob Camp wrote: Hi It’s been way too many years since my last Maser play session … Will it fire up *without* the Teflon coating on the bulb? Yes it works *better* with the Teflon (less wall interaction). Getting the bulb re-coated might be a major pain. It does look ugly in it’s current state. I’m wondering about just stripping the bulb and then seeing what works and what does not. Bob ___ 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.
Re: [time-nuts] Hydrogen Maser KIT! Update #1
Hi On Nov 2, 2014, at 9:49 PM, Chuck Harris cfhar...@erols.com wrote: In retrospect, it looks like their teflon coating is even simpler done. It looks like what they did is take very finely sectioned teflon powder, and make a slurry in probably acetone. They cleaned the vessel very well first with acetone and second, probably a little distilled water to etch the glass slightly, and then put the teflon/acetone slurry in the bulb, slooshed it around a bit to cover the walls, and then drained it all out. When the acetone evaporated, the teflon powder would remain on the walls. If it’s that simple, then going crazy over the coating as I was suggesting isn’t really needed. Bob I've seen a nearly identical coating every time I take a can of teflon spray lubricant/mold release, and spray it on something. -Chuck Harris I would think that making the teflon coating would be pretty easy. What I would try is to put a nichrome boat, and some teflon into the vessel, and pull it down to a good vacuum. Then heat up the boat, and the teflon should sublime, and condense on the walls of the vessel. The nichrome boat could be something as simple as wrapping the nichrome into a solenoid form around some teflon rod. -Chuck Harris Bob Camp wrote: Hi It’s been way too many years since my last Maser play session … Will it fire up *without* the Teflon coating on the bulb? Yes it works *better* with the Teflon (less wall interaction). Getting the bulb re-coated might be a major pain. It does look ugly in it’s current state. I’m wondering about just stripping the bulb and then seeing what works and what does not. Bob ___ 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.
