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Subject Fusor V Chamber
Posted by Richard Hull on 2010-07-28 15:06
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I have already purchased wonderful 10 inch sphere halves and mating 12" conflat flanges about 7 years ago to make Fusor V. Sheer indolence and lack of verve has held me back from completing the effort.
Fortunately, or unfortunately, depending on one's slant and pocket book, I have just bought and paid for an "Uber Chamber" from a Semi-Fab that never went to work.
The price was such that I could not resist. God help me in my quest for the needed blank offs at a rate I can live with.
I know I could never have afforded this puppy on special order.
The photos tell it all. This baby comes with two view ports, nude ion gauge and a thermocouple gauge plus other goodies, all vacuum tested on a 14" hemisphere. As shown, 167lbs of 304SS. I will pick it up soon, (not literally of course, without help)
I figure, by my bizarre, retrograde logic, that with retirement looming, it might be nice to have the "last" plus ultra vacuum chamber that won't say "no" to easy modifications in future, (not just for fusor use either).
How do It paint myself into these corners......Mein Gott!
Richard Hull
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Subject Re: Fusor V Chamber
Posted by Richard Hester on 2010-07-28 16:13
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| Now you've done it... |
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Subject Re: Fusor V Chamber
Posted by Richard Hull on 2010-07-29 14:06
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Out gassing will be a major issue and that is why one really doesn't want to be opening and closing this kind of thing regularly. As with most things in life, that which is given by one hand is often taken away by another.
I will be upgrading my mechanical pump from a Precision D150 to my large Welch 1397 which has been collecting dust for 6 years.
I have lots of ideas, we will see what action results.
Richard Hull |
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Subject Re: Fusor V Chamber
Posted by John Futter on 2010-07-28 16:36
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| Droooooooool!!!!! |
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Subject Re: Fusor V Chamber
Posted by Dave Cooper on 2010-07-28 16:44
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Richard -
Your sense of place and time were exquisite. Verrrry nice buy.
Dave Cooper |
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Subject Re: Fusor V Chamber
Posted by Dennis Brown on 2010-07-28 17:47
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| WoW! That is a nice chamber - that should be a lot of fun getting into operation - good luck and enjoy the fun! |
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Subject Re: Fusor V Chamber
Posted by Mike Beauford on 2010-07-28 23:14
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| Holy crap that's nice! That's easily +$10K chamber. Once again I bow to the scrounge master!!! |
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Subject Re: Fusor V Chamber
Posted by Doug Coulter on 2010-07-28 23:26
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Richard -- simply wow!
Boy are you ever going to have fun with this! I did a similar thing on one Bill found,
and it's been a real blessing -- easy to try whatever comes into your mind, and quick.
Yes, the blank-offs hurt, and in the case of the one I got, the instruments were trashed,
and it leaked almost everywhere, so I make Lesker a bit better off on gaskets, but we
found most of the rest we needed at very nice prices. all things considered. Looks like
you'll have less struggle with leaks than I did with the old E-microscope I got that got baked
to the point of blueing the stainless steel, and was left open in a dirty warehouse for months.
To really get the most out of something like this I think you want a door that opens
easy and free of having to buy a gasket per opening. I did, anyway, and I accept the
viton seal increasing my base pressure a little, it's so worth it 'taint funny. These bottles
are hard enough to build ships into even with that.
Can't wait to see what you'll do with this guy -- I think that after the angst you're
going to be on cloud 9 a lot. Hard to imagine something better even if special-ordered
and designed for best and easiest fusor research that can be done.
Heck, I've been using one of the sidearms in mine and am just now graduating to using
more of the main tank....for things other than vac deposition and ion source testing.
I'd have to say what you have here is THE definitive good system tank to do all
this fun stuff.
Even I am drooling. |
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Subject Re: Fusor V Chamber
Posted by John Hendron on 2010-07-29 05:57
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Wow - if 5 doesn't work it will make a great pizza oven  |
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Subject Re: Fusor V Chamber
Posted by Ben Bartlett on 2010-07-29 13:45
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| Good god! I don't even want to imagine stopping that thing from outgassing. |
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Subject Re: Fusor V Chamber
Posted by Richard Hull on 2010-09-08 13:25
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UPDATE - I am now in possession of the chamber seen in the images of the original posting in this thread. It will be on static display at HEAS 2010. It's a real beauty!
The specs are as follows.
Ports
11- 2.75" conflat ports
3 - 4.5" conflat ports
1 - 6" conflat port
2 - 8" conflat ports
2 - 10" conflat ports
1 - 16.25" sealed of base conflat port
Attached and fitted goodies that road along with the chamber for free as delivered. All of these are new and unused.
2 - 4.5" conflat quartz view ports
1 - nude ion gauge - in new condition
1 - 531 TC gauge tube
1 - 12 pin plug ceramic feed through on base
This chamber is electropolished though now that is rather moot as it has been open to air for a year or two.
Already blanked off for me and tested are the bulk of the 11-2.75" ports and the only free 4.5" port. (The other two have the quartz viewports in them.)
The chamber is brand new and never installed. It was part of a fab line that was to be installed, but never got delivered due to the economic downturn.
Now it is time to put some lipstick on this pig and plug some of the holes in her.
May I now be given the internal fortitude to actually get this thing pumped down and on line. Fusor IV will remain intact until this gal is virtually ready to go on-line. I have a feeling that like all beautiful gals this one is going to be high maintenance.
Richard Hull |
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Subject Re: Fusor V Chamber
Posted by Dave Cooper on 2010-09-08 14:20
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Richard -
Now is the time to slap on a boatload of blanks and get 'er mounted to a base and begin the initial pumpdown. Actually should be fun. ( I say this at a comfortable distance from the work.....)
Seriously, I have seen some issues with corners where ports make an entrance. You've got an abundance of corners in the chamber. Some glow discharge runs with the view port in place, might be very informative, as to whether some sort of shielding is needed and on which port intersections.
Nice piece of gear....
Dave Cooper |
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Subject Re: Fusor V Chamber
Posted by Richard Hull on 2010-09-08 14:28
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As this was a finished piece ready for a fab line, I assume it has already been helium tested. I don't think they would have electropolished a chamber that might need a bit more touch-up in the weldment department.
Now, how well can I seal those open ports?
Richard |
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Subject Help! Need 10" conflats!
Posted by Richard Hull on 2010-09-08 13:09
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I have posted this in the trading post as a wanted item but I thought builders with access to stuff might check here too.
I will erase this if there is no response soon.
I absolutely must have 2 - 10inch conflat blanks or holed blanks for fusor V. If anyone has any of these larger disks or can advise of a used source, please contact me. I don't want to spend the long buck" for new ones from Duniway or Lesker if possible.
Thanks
Richard Hull |
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Subject Using Electrostatic Confinement in open air
Posted by Aaron M. on 2010-09-07 12:25
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Hi, I’m new here and unsure if I should be posting here as I’m not building a fuser. I’m experimenting with high voltage plasma in open air. I’m now running two arcs at about -100kv arcing to +100kv giving me a good 4 inches on each arc.
Since I increased the size of my project, I’ve been facing problems with ozone levels. I’ve researched possible methods to contain the charged particles without the use of a solid container, and electrostatic confinement seems to be the best option at the moment. So far, I haven’t been able to find resources on the use of this method in open air. If anyone might have more information or advice, I would be happy to hear it. |
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Subject Ready for assembly!
Posted by Fredrik PG on 2010-08-29 08:28
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All the parts have arrived and it is now ready for assembly. When it is finished it will look like pic 2.
In the right upper corner in pic 1 you can see the mating flange for my diffusion pump. Some guys in a steel workshop made it for me for a quite reasonable price of 25 dollars. Sadly they said that they didn´t have the tools to assemble the reactor so i have to find another workshop that can assemble it.
To cut cost i bought 2 full nipple flanges instead of 4 half nipple once.
Any advices before I start putting it all together is appreciated
Thanks in advance
Fredrik Parnefjord Gustafsson
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Subject Re: Ready for assembly!
Posted by Lyn Haile on 2010-08-29 12:21
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| It may well pay to polish all internal surfaces at this point, however it is essential that all residue of polishing compounds etc are removed prior to welding. |
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Subject Re: Ready for assembly!
Posted by Carl Willis on 2010-08-29 13:34
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Hi Fredrik,
Looks like a good start. You should consider a throttle valve between the diffusion pump and the chamber, since a high pumping speed during operation will only waste gas. I hope that requirement doesn't obviate the quite-reasonable $25 coupling the shop made for you.
Good luck with the rest of the fabrication.
-Carl |
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Subject Re: Ready for assembly!
Posted by Dennis Brown on 2010-08-29 14:55
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Trival but don't forget to add a forced air fan for the DF air heat exchange coils - will save a lot of back flow.
Speaking of which, welding in two flat partial plates to act as "non-line of sight" inline baffles for the DF pump/chamber would also improve ultimate pressure (but not pumping rate) and reduce oil vapor from getting into the chamber from the DF. |
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Subject Re: Ready for assembly!
Posted by Richard Hull on 2010-08-30 10:26
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Fredrik,
While polishing might be pretty, it is absolutely not required and outside of just being pretty, it has no beneficial effect on influence on fusion. The time spent on a pretty polish might be better directed toward actual construction.
Richard Hull |
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Subject Re: Ready for assembly!
Posted by Fredrik PG on 2010-08-30 12:13
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Carl Willis
I don’t think that the high pumping speed should be much of a problem since I use a very weak roughing pump (2CFM). But it is probably a good idea because I will probably buy a better pump in the future.
Dennis Brown
I have several computer fans lying around so I will probably use them for cooling the DF pump. The "non line of sight" inline baffles you mentioned is an easy fix that I have thought of before and I will weld the two plates inside the half nipple flange as soon as possible.
Richard hull
I’m perfectly aware that the polishing won’t effect my fusion results but I thought that I might as well make it pretty since I had 20 min to spare.
- Fredrik PG |
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Subject Re: Ready for assembly!
Posted by Carl Willis on 2010-08-30 14:33
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Hi Fredrik,
Your diffusion pump has an effective speed somewhere in the 50-100 l / sec ballpark. To sustain a typical operating pressure in the fusor of 10 mtorr with this pump wide open on the system would require a very high gas throughput:
50 l/s * 10 mtorr = 0.5 torr l / s (~40 sccm)
I ran at about 1 sccm on all my projects, and my knowledge of others' systems suggests this is where they tend to be as well. I use a simple QF-25 manual shutoff valve as a throttle on a 50-lps diffusion pump, reducing the effective speed to an estimated ~1 l/s. 1 sccm is an easy value to achieve with capillaries, laser orifices, mass flow controllers, and metering needle valves, and will get you about 1000 hours of operating time from a deuterium lecture bottle. Too much lower throughput, and flow becomes difficult to control. Too much higher, and you'll blow through expensive gas at an uncomfortable rate.
The 2-CFM forepump (roughing pump) seems just fine to me for backing this diffusion pump.
-Carl |
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Subject Re: Ready for assembly!
Posted by lutzhoffman on 2010-08-31 04:23
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So far so good, all the advice has been spot on. Have you decided on what fluids to run in both of your pumps yet? There are two schools of thought on this, some prefer to run cheap but effective diffoil 20 in both pumps for simplicity, and others would say to use expensive Santovac 5, since it eliminates the need for a trap, and because your DP uses so little oil anyway.
Since you have the actual chamber design done now, you may want to put some serious thought into optimizing the vacuum system at this point. I would suggest at minimum also adding a copper wool filled trap between the RP and the DP. You can buy cheap copper scrubbing pads, and degrease them with soapy water, followed by rinsing with water, drying, and then a final solvent rinse followed by a high temp 300 deg F oven dry. This will absorb the back streaming RP oil, and prevent it from getting into your DP, and chamber. When these get dirty, then you just repeat the above cleaning. I adapted a fine mesh water filter unit from the hardware store, by unscrewing the cup and filling it with the copper wool. The transparent cup is great because you can see the oil when it gets dirty.
What ever you decide to do, searching the threads on vacuum stuff etc. in this forum will pay off big time in the long run. There is so much good information here, enjoy it. For D gas I have tried several ways to use D2O as a source, the best way for me was to pass D2O vapor through hot magnesium turnings in a quartz tube, with fiberglass plugs in the ends to hold the Mg in place. Hot Mg will also absorb nitrogen as well, if a small amount of air remains in the system. It is however best to flush the line with argon first. You can even use the chamber vacuum to suck the D2O vapor through the hot Mg, and aid in the evaporation of the D2O from the sealed flask, as it passes through the hot Mg, only D gas will remain.
Some folks add a dryer stage to D gas generated by various chemical and electrolytic methods, but some studies have show slightly increased fusion rates, with traces of remaining D2O, to the point where they even add a controlled amount. With the Mg method it tends to be pretty dry, when compared to electrolysis for example. You can experiment with H2O and Mg very cheaply to get familiar with the process, and then decide if you want to drop so much cash for the lecture bottle, and regulator etc. Take care and good luck, very impressive so far : ) |
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Subject Re: Ready for assembly!
Posted by Fredrik PG on 2010-09-02 14:28
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Carl Willis,
Good to hear that my pump will do I was actually a bit worried about it being too weak.
Lutzhoffman,
I have not thought so much about what oil to use but I will probably go for diffoil 20 as you mentioned (I´ve heard it´s good for starters). The santovac 5 is a little expensive for my taste . Is it absolutely nessesary to use an oil trap when using diffoil 20 or is it enought (for starters) with the "non line of sight" inline baffles as Dennis Brown mentioned? (correct me if I´m wrong I have never used a diffusion pump before but I will sertainly read the vacuum threads to learn more).
I will do as you said and experiment with the Mg H20 method and familurize myself with the method before I test the real deal, but first I need to weld it all together .
Thanks for your advices,
Fredrik Parnefjord Gustafsson |
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Subject Re: Ready for assembly!
Posted by richnormand on 2010-09-02 16:42
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WOW. Nice work.
No I have to clean my keyboard from drool.... |
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Subject Re: Ready for assembly!
Posted by Richard Hester on 2010-09-02 18:24
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For diff pump oil, I would use silicone oils like DC704 and DC705 (or their equivalents). They much more affordable than Santovac and allow very respectable ultimate pressure without a cooled baffle. They also withstand oxidation much better than the cheap Octoil and equivalents, so an occasional up-to-air accident won't turn your oil charge into caramel. The mass spectrometer folks hate the silicone oils because of the extra ionic species they introduce (they use Santovac), but this should not be an issue with the fusor.
If you're using a huge 10" (or larger) pump, Octoil starts to look attractive because of the sheer cost of the oil charge, but for a little pump requiring only 50cc or so of oil, silicone is a good bet. |
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Subject Re: Ready for assembly!
Posted by Daniel Smith on 2010-09-02 18:20
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| Hey, Nice start of the chamber. I'm going to do a chamber similar to yours. Why do you use the ratable conflats? Whats the difference from them to the non-rotatable? |
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Subject Re: Ready for assembly!
Posted by lutzhoffman on 2010-09-03 15:07
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Hello:
Ref Fluids:
DC 705, and DC 704 are nice, but they have one problem, which may not be a problem with fusor application, but this IS a problem with electron microscopes, potential drop accelerators etc. The problem is that if you get any backsteaming, under discharge, ion / electron beam conditions. These silicon fluids can form insulating layers of SiO2 (Quartz) on the inside surfaces in the vacuum tank, or tube etc. This can affect the potential distribution, and HV properties, and even ruin a tube. Non silicon fluids tend to deposit carbon if anything, which is easy to deal with in comparison. Silicon fluids also have some solubility issues with many common solvents that are often used for cleaning, so you have to select the right solvent, if you need to clean your DP, or something else in your system. Maybe someone else has fusor specific knowlege as to if SiO2 deposits can be problematic in a fusor? I just do not know the answer to this question.
I ran DC 704 for years, for a coating chamber, and it worked very well, but now I use Santovac after getting 500ml on ebay for cheap, I would never go back to DC- 704 silicon fluid: No more cold traps between the DP and chamber, just a butterfly valve, and a cold cap which is built into my HS 2 DP. Plus if I were to loose vacuum again, due to breakage etc, its no big deal with Santovac, it tends to decompose into H2O and CO2 gas if somehow you get it that hot, which is not likely. I have lost vacuum at full temp more than once, due to breakage of glass parts etc, each time I first freaked out, and sweated it, until I checked the DP fluid, and all was fine.
My friend uses Diffoil 20 only, in both his roughing pump, and in his DP. His system works very well, and he has not had any major problems. He has a homemade 2 stage thermo-electric cooled trap between his DP, and his chamber. Very creative setup, he claims to get down to about -5C in the inside of the trap. The 2 stage thermo-electric cooler / fan is on the outside, and a foam insulated thick copper HV vac. feedthrough sucks the heat from the vacuum side copper baffle plate, to the external TC cooling setup,
He still has a cheap copper wool trap still between the DP, and the RP. His reason is: Even though he uses the same fluid in the DP, and in the RP, the lighter fraction breakdown products from the DP, and contaminants etc. will build up in the RP oil, he does not want these to migrate back into the DP. I have no idea if this is valid, but he is a "smart cookie", being a retired Xerox corp. engineer, with much partical experience, so I just accept his reasoning. His original cold trap was a dry ice acetone alchohol setup, which was much colder, but he is getting away with the -5C system now.
Octoil is toxic, and a suspected mutagen, with few advantages, which is why hardly no one uses it anymore, unless they have, or find a bottle for cheap somewhere. So in the end you have to decied what is best for you, and maybe for your health. Octoil cannot be that bad I suppose, because the subacate ester is used to keep C-4 plastic explosive pliable, and after my military years in the late 80's, my kids all look normal, well almost, but that's not genetic : )
No one else can tell you what is best for you, only knowlege gained can help you do this, and to select the correct fluid. Doug who contibutes to this column a lot, runs diffoil20 in his DP, and RP. He is of course not always correct, but he has actually converted my thinking on several issues, so I see him as one of the "bright bulbs" along with Carl, Richard, John and so many others in this column. These folks are people who actually build, and use the stuff that they are posting about in real life, which in my mind counts for something : )
Personally I like the fill and forget features of Santovac, and the elimination of the trap between my DP, and my chamber. I mention this only because when you look at prices, its more complicated than just the oil cost, because for example how much does a trap cost to buy, and then to fill? Yes you can probably eliminate the trap with DC 705 also, at a lower cost, but are you willing to accept the other aspects of silicon fluid? I cannot because I like DC potential drop accelerators, otherwise my pump could have DC-705 in it, jut the same. I am sure that with a little bit of reading, of past threads on this subject, you will figure it out. You have my respect already since you are a builder, so I will look forward to the day where you help me solve some problem, take care....
PS: Put a big fan on that DP with some sheet metal, plastic etc. to direct the air, a PC fan is to anemic, but a big 6" + fan from some other big IT item will work. |
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Subject Re: Ready for assembly!
Posted by Richard Hull on 2010-09-07 10:06
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I will be using pentavac/santovac in fusor V which will be underway after the HEAS conference should I decide to use my old diff pump instead of my 10" Turbo pump.
I picked up a thermo-electric cooler mounted on a 2" Veeco diff pump that is air cooled last weekend for $40.00 at a Teslathon. It came with a bottle of 704. I may use my old diff pump with the coller added of move over to the Veeco. We will see.
The turbo is water cooled and I don't like that. I have had the thing for years, but just am resisting the flowing water bit.
Richard Hull |
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Subject Deuterium
Posted by Ben Bartlett on 2009-08-21 16:33
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My systems are almost fusion ready now. I have finished installing Mr. Dowell's 100kV XRT, and have a MONSTER 1-micron rotary pump I am borrowing until January. I have also completed the gas handling system, although I'm still fixing some very minor leaks in it. More pictures of the fusor to come later....
Anyway, I have been looking for the past few weeks for a good deuterium supplier, but everyone I have contacted either requires business info or has not contacted me in return. Where is everyone here getting their deuterium from?
Also, now that the group-buy of BTI detectors seems to have died, does anyone here have a bubble/neutron detector I could buy (for a reasonable price) or borrow? I would appreciate any offers immensely!
Thanks for reading/responding,
Ben |
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Subject Re: Deuterium
Posted by Tyler Christensen on 2009-08-21 17:31
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It's not easy to get either a neutron detector or deuterium gas.
I spent 4 months of contacting companies and all their branch locations, and finally after probably a good 100 hours of searching managed to track down a customer service rep at a local air-gas supplier who has ordered it for me, should be here any day. I think the trick is going in person to a local facility. I drove to the location and he gave me his email address and then he was able to help me. I think over email/phone they find it too easy to just reject you because you're not where they get their major money from.
Neutron detector is also extremely difficult to find at a reasonable price. I've been looking for my own for months and have yet to come up with something. I'm hoping I might find one at HEAS if I haven't succeeded by then. |
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Subject Re: Deuterium
Posted by chad ramey on 2009-08-21 23:33
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| How about we just keep it simple and have just a three person group buy? |
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Subject Re: Deuterium
Posted by Tyler Christensen on 2009-08-21 23:46
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I do want to get one. We might as well open it up to everyone, why not just post that the purchase will be made in a week, if payment is received then you get put on the list and then make the order so it doesn't just linger as a group buy that will never happen.
I can organize it if you'd like but I can't make the purchase due to a lack of a tax ID. |
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Subject Re: Deuterium
Posted by chad ramey on 2009-08-22 00:44
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| That sounds good to me, I can find a company with a tax id to buy them for us but I might need to wait a few weeks due to lack of money because I'm saving for a x-ray transformer. |
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Subject Re: Deuterium
Posted by Tyler Christensen on 2009-08-22 00:56
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Ok, well if you collect payment beforehand then that wouldn't be an issue anyways I'm thinking?
You should probably just pick an order date and make an official ordering post when you're ready to do it.
Looks like a good time to build a ZnS scintillator detector then I can calibrate against the dosimeter. |
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Subject Re: Deuterium
Posted by chad ramey on 2009-08-22 13:57
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| That sounds like a great idea. I'll work on a date this week and then start a new thread for people to show interest. |
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Subject Re: Deuterium
Posted by Edward Miller on 2009-08-23 06:47
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| I have a tax id and i'm happy to order bti detectors for US fusor members. |
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Subject Re: Deuterium
Posted by Ben Bartlett on 2009-08-23 13:48
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That would be great! (I've really been ready for a BTI and deuterium for the last few weeks.)
Also, if anyone here has a viable business from which we could have a group buy of deuterium, please speak up! I think most places, like Advanced Specialty Gases and TriGas require business ID's/info before they can ship flammable gases such as Deuterium. |
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Subject Re: Deuterium
Posted by Mike Beauford on 2009-08-23 14:24
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Hi Guys,
I'm also interested in buying some D2. Basically, my gas system is the only thing left that I have not acquired for my fusor.
Mike |
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Subject Re: Deuterium
Posted by Tyler Christensen on 2009-08-23 14:36
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| You can't ship compressed flammable gas so a group buy isn't possible unless someone is willing to take the $200,000+ DOT fines violation risk. Try going to a local airgas or matheson specialty gas dealer in person. It doesn't work over the phone, you have to walk in if you want any hope. |
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Subject Re: Deuterium -- we have some available
Posted by Doug Coulter on 2009-08-23 15:05
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We bought a large amount of research grade D from Matheson, and have some small bottles we can put it in if people are interested. One way or another, we can bring some to the next HEAS.
Obviously someone can ship this stuff -- Matheson did, and it came Fedex, hazmat. I don't know what Fedex needs upfront (eg credentials that you know how to pack it safely) though, but I can ask.
Our plan, even for our own use, is to use some aluminum O2 bottles we've rethreaded hydrogen valves for (cga types). I've processed a few to the point of cleaning them inside and out, and letting them outgass under baking for a week in the big vacuum chamber, then backfilling with argon until I'm ready to put the D in there, which will involve re-heat in vacuum first to remove the argon. We plan to put about 100 psi into these, they're about 1.5 liters in size. This way, a leak or accident means we don't lose our whole stock (which was quite expensive not to mention the hassle mentioned above) and it's just safer. Perhaps one could even skip a regulator and use an orifice to limit flow to a needle valve at such low pressure.
We (BillF and I) haven't yet determined what we should charge for this, but we're not in it for the money -- just get back what we've paid and a little for the hours of work on the cylinders and valves, and plumbing to do the transfer.
Any interested can contact me directly. |
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Subject Deuterium
Posted by omegalab on 2010-08-23 13:55
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I found some pure heavy water on ebay.
Item : 320574185353
10g is only 17$+shipping. I bought 15g of it.
I dont know how long can it last in normal operation, but I try it, if i'm done with my fusor. |
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Subject Re: Deuterium
Posted by Doug Coulter on 2010-08-23 14:18
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Having started out with heavy water (it works, but you get some impurities), I can say that with care, 15cc or so lasts a long time. Use baked sodium carbonate (get rid of the normal water in it) for your electrolyte so you don't add plain hydrogen, and put some sort of dryer on the output before it gets into the tank. Ours seemed to pick up normal water vapor from air exposure, so I guess I'd suggest sealing it off when not in use. If you get your gas flow control issues right, that much will last quite a long time.
Obviously you have to make your electrolyzer small for that to happen, if it takes 10cc just to get the level in it right, you only really have 5cc usable.
http://www.coultersmithing.com/Reports/EarlyTimes/EarlyTimes.html
Has a picture at the bottom of the electrolyzer we made here. The center conductor is tungsten welding rod (easy to seal into pyrex) and the anode is Pt plated wire we got at scitoys.com -- it works fine and is a lot cheaper than pure Pt wire.
You want to be careful with this type setup, as leaving the valve to the tank open, or just opening it too far sucks the water out of the electrolyzer into the tank. On the other side of that equation, the electrolyzer will shut down automatically as soon as the water level in the central tube gets down to the end of the cathode rod. |
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Subject Re: Deuterium
Posted by omegalab on 2010-08-23 16:29
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Yes, I planned, that I throw a very little piece of pure sodium, or potassium in the heavy water to make NaOD, or KOD, that is very conductive. I think I will make a 'gas buffer', to solve deep vacuum and the water connection problems.
But its necessary to use platinum wire? |
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Subject Re: Deuterium
Posted by Richard Hull on 2010-08-24 09:57
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Yours is the ideal solution to contaminants.
I posted on this a good while back in a couple of threads related to D20 electrolysis. The tiniest fragment of sodium in the D20 would make an ideal electrolyte and not kick in any bad stuff. Just make sure to cut the sodium fresh on all sides and rapidly place it in the D20 so that you don't drag in much H from the rapidly acquired patina of NaOH. A glove box that has had a 100 watt incandescent lamp on for a while would be a pretty dry place to do this. (use a humidity meter if possible.)
Richard Hull |
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Subject Re: Deuterium
Posted by Andrew Seltzman on 2010-08-24 13:33
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In my electrolyzer I used Sodium Carbonate (Na2CO3) to prevent the problem of contaminating the mixture with hydrogen.
Andrew Seltzman |
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Subject Re: Deuterium
Posted by Doug Coulter on 2010-08-25 14:38
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Almost certainly it's necessary to use something very noble as an anode -- other things corrode quickly into the solution and if nothing else, need replacement as they simply disappear. Most "carbon rods" fall apart, just about everything else goes into solution under the electromotive pressure you apply to bust up the water.
Yes, a little pure Na, Li,, Ca, Ba, or other thing like that -- if actually pure (good luck), might be better than the baked out sodium carbonate (not bicarbonate!) Andrew and I have used, but also (much) more corrosive on the electrodes. They will of course become carbonates anyway with air exposure as they eat CO2 with a vengeance. Could be that this gets rid of some CO2 contamination for you, dunno. Hydroxides are used in re-breathers (exotic scuba gear) for that reason.
I basically copied Andrew's nice design for mine, I think he posted links to it here a long while back. I just made mine the way it was easier to make with the resources I had. I did notice the pickup over time of plain old H presumably from water vapor in the air, due to the osmotic pressure issue or something -- this changed with time of air exposure (got worse) and was measured on a mass spectrometer I trust.
But with all that -- we did make our first bunch of BTI bubbles that way, inconvenient as it was. Later tests here show that a little of this and that contamination actually make the fusor a bit more stable and easy to run; but that alone doesn't necessarily make more neutrons if you can get it running well with purer stuff - the opposite is true in our tests. But the thing is harder to get stable with the pure stuff, so your neutron output varies with how often it's on the good spot -- either way might be better given other issues, depending on what you control for. I will simply say we're not going back here.
Our emphasis here is on Q, not sheer output, and we do roughly 3x better there with the really pure stuff, all else the same. Those contaminants eat input energy for no output. |
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Subject Re: Deuterium
Posted by Balint Ivanyi on 2010-08-30 05:44
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My heavy water arrived today.
I have a chemist friend, maybe he can give me a very small amount of pure sodium.
This platinum coated nickel wire is cheap, so I will buy one foot.
(I'm omegalabs, just renamed myself) |
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Subject Re: Deuterium
Posted by John Hendron on 2010-08-30 06:14
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| Greetings Balint - and welcome. |
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Subject Re: Deuterium
Posted by Doug Coulter on 2010-08-30 10:49
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The only advantage I see with using sodium (or some other metal that takes water apart) is that you can have pressure -- as you need to drive a hydrogen purifier, but not for straight into a fusor through a dryer. The bad side is that you lost half your D in making NaOD and now it's really hard to get back.
Guess it depends on the price of the heavy water...You can't pull a good vacuum on a reaction vessel that has water in it to prevent air contamination....you just boil the heavy water when you try.
Electrolysis has its own pains to be sure -- keeping the heavy water from picking up dissolved air and normal water from that main among them. A foot of that cheapo plated wire is plenty to do it with for the anode -- I just used a tungsten tig rod for the cathode, as it seals into pyrex easy and it works fine with the NaCO3 electrolyte -- no corrosion seen here on either electrode. |
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Subject Re: Deuterium
Posted by Balint Ivanyi on 2010-09-03 14:46
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Doug Coulter wrote:
> The only advantage I see with using sodium (or some other metal that takes water apart) is that you can have pressure -- as you need to drive a hydrogen purifier, but not for straight into a fusor through a dryer. The bad side is that you lost half your D in making NaOD and now it's really hard to get back.
Yes, you are right. Looks like it's easier to do the electrolysis with NaCO3. My friend can give me analytic pure material, so I think it will be fine. |
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Subject Re: Deuterium
Posted by Doug Coulter on 2010-09-04 18:43
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| If you use the carbonate, bake it out to remove the 10 waters of crystallization before adding it to your heavy water..... |
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(Richard Hull)