UPDATE #6: Hull-Raney Ion Gun Construction

For the design and construction details of ion guns, necessary for more advanced designs and lower vacuums.
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raneyt
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UPDATE #6: Hull-Raney Ion Gun Construction

Post by raneyt »

All,

The prototype ion gun has been completely assembled for some time now. However, several iterations of "leak hunting" have failed to result in pressures below 50 mTorr. At these pressures an ion beam is not discernible.

So, I've decided to disassemble the current configuration. I will replace the Viton o-rings, G-10 glass epoxy rods and RTV seals with "hard" vacuum epoxy seals. The original intent of using o-ring seals and tie-rods was to simplify system modification and allow for differences in the glass-metal joint coefficients of thermal expansion.

However, this is a prototype system and I don't anticipate long run times where glass-metal joint heating will be a problem. If so, the epoxy seals should allow a little expansion. I won't run the ion gun any longer than the time it'll take to determine the ion beam current.

As an aside, Richard Hull and I drove down to Charles Yost's house in North Carolina. We had a nice visit and did some electrostatic sphere rotation experiments as Richard mentioned in another post. It was nice seeing Charles again and "the Perfesser". I also met "Bob the Gelatinous Blob". Bob is a large mass of latex rubber weighing several hundred pounds. He's the result of buying a 55-gallon drum of latex and not using it before its expiration date.

That's it for now. I'll keep you all posted. Progress has been slow, partly because I don't like leak hunting and I can usually find something else to do. Good luck in your experiments.

Regards,

TIM
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Mike Veldman
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Re: UPDATE #6: Hull-Raney Ion Gun Construction

Post by Mike Veldman »

Have you any vacuum wax? I have a stick of apiezon (I believe that's the right name) wax I've had since the seventies that works really well for sealing glass to metal for vacuum applications and allowing it to come apart easily.
Just a thought.
mike
I tried to contain myself, but I escaped.
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Richard Hull
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Re: UPDATE #6: Hull-Raney Ion Gun Construction

Post by Richard Hull »

I gave Tim some of my Apiezon W wax, (black,high melt point), a few years ago and he has used it in the past. It is nasty stuff, in spite of being easily removed. Just looking at a system sealed up with this stuff gives one the impression of "half-assed"..........But, if it does th' job.........

Tim's system seems good and he has done his best with the silicone vacu seal. The leaks must be subtle indeed, but with about 4 or more mating surfaces, there is pleanty of room for a summing of leaks to drive the vacuumist nuts.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
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The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
raneyt
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Re: UPDATE #6: Hull-Raney Ion Gun Construction

Post by raneyt »

Mike & Richard,

I though of using the Apiezon W, but it's not mechanically strong enough under these circumstances. So, that's why I'll use the vacuum expoxy (Hysol 1C, a Torrseal equivalent sealant).

I took photos of the ion gun in its current configuration and will scan/post them. You know how it goes...sometimes a vacuum really sucks (or trying to maintain that vacuum).

Regards,

TIM
guest

Re: UPDATE #6: Hull-Raney Ion Gun Construction

Post by guest »

I would love to keep in touch with you guys, don't know a lot about the subject matter as yet. I hope I can contribute something worthwhile at some point. Highly interesting reasearch you are engaged in and one that has long interested me as well. I'm sure, i am well behind you, so please, keep me updated as to your progress, I will if at all possible, contribute someting worthy of your endeavors so far as I am capable, at some point. Thank you for considering me as at this time, an observer in your experiments. I relish hearing from you, I am very excited. The implications are enough to keep me awake beyond the usual 3-4 hours I am able to sleep nightly!

Warmest Regards,
Randall Smith
Ranger Marketing

I am launching a business, nothing to do with our discussion, a retail store outlet on Yahoo. com. No relevance to my questions to you. Hopefullly a means of sustaining me while I persue my consuming interests!
Kindest Regards,
Randall Smith

TIMOTHY RANEY wrote:
> All,
>
> The prototype ion gun has been completely assembled for some time now. However, several iterations of "leak hunting" have failed to result in pressures below 50 mTorr. At these pressures an ion beam is not discernible.
>
> So, I've decided to disassemble the current configuration. I will replace the Viton o-rings, G-10 glass epoxy rods and RTV seals with "hard" vacuum epoxy seals. The original intent of using o-ring seals and tie-rods was to simplify system modification and allow for differences in the glass-metal joint coefficients of thermal expansion.
>
> However, this is a prototype system and I don't anticipate long run times where glass-metal joint heating will be a problem. If so, the epoxy seals should allow a little expansion. I won't run the ion gun any longer than the time it'll take to determine the ion beam current.
>
> As an aside, Richard Hull and I drove down to Charles Yost's house in North Carolina. We had a nice visit and did some electrostatic sphere rotation experiments as Richard mentioned in another post. It was nice seeing Charles again and "the Perfesser". I also met "Bob the Gelatinous Blob". Bob is a large mass of latex rubber weighing several hundred pounds. He's the result of buying a 55-gallon drum of latex and not using it before its expiration date.
>
> That's it for now. I'll keep you all posted. Progress has been slow, partly because I don't like leak hunting and I can usually find something else to do. Good luck in your experiments.
>
> Regards,
>
> TIM
pfostini
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Re: UPDATE #6: Hull-Raney Ion Gun Construction

Post by pfostini »

If you are going to take the IG apart and redo the seals with an epoxy seal, I would like to suggest Bacon Industries. It is a higher temp epoxy very good vac qualities and it seals to everything. The only thing, it needs to be cured at 65 C. I put my linac together with it ( amature scientist article ). its like a baseball bat. Torr seal is good but it releaes from the parts when heated.
I think it is epoxy number LC-40 from Bacon ind. Here is a picture , its the blue epoxy between the glass and stainless.
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3l
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Re: UPDATE #6: Hull-Raney Ion Gun Construction

Post by 3l »

Hi Guys:

Phil is right the blue stuff really works.
It is a lot easier to spread without too many drips.
I was dubious at first but noticed a lot of people swear by the blue stuff. On a cost basis you can get a whole gallon of blue
marine epoxy for the price of one sqeeze of high vacuum epoxy.
So big projects can be done cheaply now.
It is tough as iron and a lot easier to remove than the squeeze tube stuff if you get it on your hands during application.
Thanks for the tip Phil.

Happy Fusoring!
Larry Leins
Fusor Tech
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