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Ion injector with one grid or two spherical grids ?

Posted: Sat Oct 02, 2010 5:26 pm
by msky
Dear friends,

If i use the main patent with two spherical grid, which one of them is as ion source, is it require to provide another ion injector as ion source for injecting the D gas, However if i inject ion in this chamber what happen?
Also, Is it require to make a thermionic cathode for improvement the chamber performance?

Thanks

Re: Ion injector with one grid or two spherical grids ?

Posted: Tue Oct 05, 2010 2:41 pm
by Richard Hull
The inner grid is all you need, normally.

In the Hirsch-Meeks patent, they use a coated thermionic cathode to generate electrons and the larger grid as an ionizer grid this is a rather complicated form of fusor that most amateurs do not use at all. How you assemble your fusor is up to you.

Richard Hull

Re: Ion injector with one grid or two spherical grids ?

Posted: Tue Oct 05, 2010 7:44 pm
by msky
Dear Richard

I want to collect and assemble the device by following main parts:

- Vacuum Chamber (6'' chamber with 8" plasma as the chamber of you and Mr.Seltzman.
- Vacuum Pump ( 2 or 3 stage Rotary vaccum pump)
- H.V
- Gas (D2) injector (in simple form not in form an ion injector)
- Inner Spherical grid as ion source (three rings grid Made from Tantalum)
connected to -30kV
- Outer Spherical Grid Connected to voltage about +600V

I like to get from my chamber enough flux of 2.45MeV neutron.

I am right or my though about device have problem? What is the simplest form and part for neutron generation ? (Please Help me about main parts)

Thanks

Re: Ion injector with one grid or two spherical grids ?

Posted: Tue Oct 05, 2010 8:32 pm
by Starfire
Wow - do I detect a challenge Richard?

Re: Ion injector with one grid or two spherical grids ?

Posted: Tue Oct 05, 2010 8:38 pm
by msky
I am your forum newly student. i am beginner. But i do my best effort.

Re: Ion injector with one grid or two spherical grids ?

Posted: Tue Oct 05, 2010 9:24 pm
by Doug Coulter
OK, I can't resist. We obviously have a small problem with language here, but nothing we can't get around with a little effort.

With the setup you describe, yes, you will get some flux of 2.45 MeV neutrons, but not tons. You'll need better than just a rotary pump for that (a diffusion pump or a turbo), and perhaps more high voltage -- you didn't mention how much current you will have available.

But all you said about neutron flux was "enough" so the question is "enough for what"?

There's a parsing problem here if you have a 6" chamber and 8" plasma! That would put the plasma outside the chamber!

Having a second grid in there is interesting, but maybe not what you will wind up with, but everyone here is always encouraged to TRY whatever they think of, this place needs more hands-on real workers than it has. I have tried that setup, and didn't like it as you describe (for reasons beyond the scope of this post), but it may work out differently for you, so try it. Just make it and see. That will teach you a lot, very quickly, in ways you will really learn from.

You also didn't mention measuring gear, which is another part of this stew, and maybe the most important. You'll want a way to make sure you are safe from too many X rays, and a way to tell if you're making neutrons at a minimum. I find a way to look inside the device while tuning the parameters is very important, most here use a camera or mirror so they can see what is happening without getting X rayed too badly.

Go for it, good luck, and be safe!

Real Names

Posted: Wed Oct 06, 2010 2:43 am
by Paul_Schatzkin
Mehdi, when you signed up for this site - on Sept 15, 2010 - you should have seen a notice that said "we use real names around here."

"Mehdi78140" is not a real name. Please correct your user account accordingly.

Thanks,

--PS

Re: Ion injector with one grid or two spherical grids ?

Posted: Wed Oct 06, 2010 11:01 pm
by msky
Thanks for your answer, and your help about pump type.

I want to see plasma and make a safe 2.45MeV neutron source for my academic project.
In laboratory we have BF3 and Ionization chamber. My questions are for best construction, Optimized device and safe operation.

M. H

Re: Ion injector with one grid or two spherical grids ?

Posted: Wed Oct 06, 2010 11:37 pm
by Carl Willis
Hello Mehdi,

I think the best advice about what what kind of apparatus (and what scale of apparatus) is appropriate can only be offered if you describe what you are trying to do with it.

Just for reference, a typical well-performing 6-inch fusor operating at 50+ kV and on the order of 20 mA, using a diffusion or turbomolecular pump, can produce around 1E+06 neutrons / second. Ion sources, including ionizer grids, are known to improve performance quite a lot, as do higher cathode voltages and higher operating currents.

Please describe your project in more detail.

Thanks,
Carl

Re: Ion injector with one grid or two spherical grids ?

Posted: Thu Oct 07, 2010 8:10 pm
by msky
Dear Carl

I think it is proper flux. We want to provide a neutron source for our different research (Activation analysis). Also, you mean its no need to ion injector, ?

Thanks, to all