Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

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Dennis P Brown
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by Dennis P Brown »

Impressive! Small can be beautiful but like an iceberg, the underlying support equipment (power supplies,vacuum system,gauges, controls,supports) really explode the size and complexity of even the simplest gun!

Great work and thanks for sharing the apparatus.
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Richard Hull
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by Richard Hull »

Yes, creating a non-earth-friendly environment in order to provide a specialized pure atmosphere in which to move charged particles about in a controlled manner can involve a lot of volume absorbing gear. We are really creating our own little, highly controlled electrical universes in a can. Still, ain't it fun!

Nice work Robert!

Ricahrd Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Update 8/3/2014:

I've upgraded the machine a bit since my last post.

The machine now sports an inductively coupled ion source and a differentially biased electron suppression shroud. See the brief video of the system here: https://www.youtube.com/watch?v=DdLe6No5he4&app=desktop

I'll keep improving things as I go, it's a forever rough draft.

Thanks for the kind words, all!

Enjoy the pictures and a video of the machine running.
RT

edit: I have no idea why the first picture displays as sideways, click on it and you'll get the correct upright view.
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George Schmermund
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by George Schmermund »

Robert - I'm enthused by the effort that you've put into your BoT machine. There is a faint, but growing interest here regarding this method of producing nuclear reactions. Certainly a lot more work is involved in getting a BoT machine up and running compared to a fusor and, as you've pointed out, it's a project for the advanced experimenter. Few here will ever accomplish more than a fusor, but you're demonstrating that a more serious approach to doing fusion physics is within the reach of the advanced hacker.

I applaud your dedication to the cause and hope to eventually join the ranks of the BoT heads here. Salute!
Anything obvious in high vacuum is probably wrong.
RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Thank you for the kind words George.

Doing beam on target to a level that allows one to say "I've done beam on target fusion" is well within amateur reach. However, a BoT that could compare with the typical actively pumped industrial systems from 10-15 years ago is my goal - something I'm slowly stumbling towards.

I'd also say that BoT opens doors beyond fusion research, for example I've been playing with the idea of changing around the system someday for some experimentation in focused ion beam milling. FIB is about as far from my reach now, as the BoT was after the Fusor.

Leveling up let's you see what's possible next, that's the greatest value of the BoT IMHO.
RT
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Dennis P Brown
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by Dennis P Brown »

Rather than lead shielding (toxic and conductive) why not used 12"x12"x3/8" slate tiles? Home Depot sells these in boxes and are very inexpensive. These tiles are square, can be stacked together and glued, and don't conduct. They have 1/4 the density of Pb so it is easy to calculate the required shield thickness. Disposal isn't an issue unlike lead nor safety concerns in handling or dust. They can be both cut (an inexpensive abrasive blade) or drilled (ceramic bit) if a special shape and/or a hole is needed. They actually look rather nice and professional.

That all said, the accelerator looks very nice.

Have you considered adding simple metal rings along the glass tube body to better contain the protons (weakly focus) and make the electric field more uniform along the tube for more constant acceleration?

Wouldn't mind some more details on your electron suppression system.
RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

New [more in depth/nicer] video showing all the equipment and smoother operation.
http://youtu.be/OUDxt2Nya50

Enjoy,
RT
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Some additional and hopefully helpful eyecandy.

Peace out,
Robert

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RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Miss September.
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RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Update: Still air brushing the system, tweaking things here and there, here some glorious eye candy.

Beam entering the secondary electron suppression shroud.
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RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Some updated pictures of the system as it stands now.

-Robert
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Andrew Robinson
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by Andrew Robinson »

I like the new paint job. Brings it all together.
I can wire anything directly into anything! I'm the professor!
RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Some more recent photos and video of things, having just boosted the beam output to about a milliamp.

Youtube link: https://youtu.be/mdv4KpYKKJk

RT
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Werner Engel
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by Werner Engel »

Robert,
I saw you video and some of the pictures of your ion-source. I have a similar design but want to use a RF-source which is almost DIY. I bought a 1,0 kW SSPA. For connecting the HF-coil to this PA I also selected the MFJ-962D. But when browsing through your video, I saw that you opend up the MFJ device and made some internal connections. Is the 6 Ohm impedance enough, you can reach with the MFJ.962-D - or did you use another trick to adjust it down to 1 Ohm?
Can you tell me a little more about your changes? Unfortunatly I don't have enough know how in the HF area!
RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Another update/photo, as of June.

I've got a lot of projects I'm working on right now.

Among them, bringing a refurbished 100kV multiplier tower online for my setup.

I'm also investigated a long term solution to remote operability, seeing as how my equipment is now interface-friendly.

-RT

P.S. @Werner, what I did there was directly connect to the output on one of the variable caps in the network. I was moving upstream from all the switches and connectors that kept catching fire. ICP likes to ring up and produce arcable voltages. Ham radio antenna tuners are really not designed for this sort of abuse, though with care they can be used.
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Werner Engel
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by Werner Engel »

Robert, here you see the inside of the tuner für impedance matching the RF source . Do you mean you removed the wire from the cap to the switch and connected the coil directly to the cap? Which cap-connection did you use? Could you send a picture? Did you do any kind of resonance calculation to design the coil? I used a Rigol DSA815 to detect any resonance – but unfortunately it did not work.
And how did you set the right values of the cap and the inductor? The manual does not say anything about a plasma-heating-coil as a load ;-)

To drive my SSPA I need at least 2W of RF-power. I’m currently working on a kind of pre-amp using a LMH6321 (2nd picture). Looks good so far!
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RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

> "Do you mean you removed the wire from the cap to the switch and connected the coil directly to the cap?"
Correct.
> "Did you do any kind of resonance calculation to design the coil?"
Negatory.
> "I used a Rigol DSA815 to detect any resonance – but unfortunately it did not work."
Those low VSWR points are in there, but your analyzer probably won't find them.
> "And how did you set the right values of the cap and the inductor?"
By hand, manually using a forward and reflected meter.

RT
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Finally got the new ion source working after some months of fussing with it. The source has three extractor electrodes, the top plate, and a pair of extractors in the double sided 1" thick conflat. The top plate and the lower aluminum piece float at 15kV, and the brass piece sits at ground potential. Source self extracts nicely, whereas before the old source required the biased target to do the extraction.

-RT
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Steven Sesselmann
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by Steven Sesselmann »

Robert,

Nice looking work as always.

Is that machinable Macor ceramic you have used to hold the extractor arrangement?

So do you have the target at negative potential?

Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
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RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Hi Steven,

Yeah, that's machinable ceramic in there. The stuff cuts real nice on my mini-lathe.

No target in there yet or built, hence the beam spread. The original one was pretty thoroughly destroyed. As in the past this one will also use a negatively biased target.

Thanks,
RT
RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Cleaned things up somewhat, and got more beam out - going to keep dialing it in.

RT
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RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Dialded in on H mode, and am pulling proper beam now. Some pics and videos of operation:

https://youtu.be/Jx0ts2VmjHs

https://youtu.be/mu_XNZKC0aw

RT
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Garrett Young
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by Garrett Young »

Robert,

Now this is a really cool project! I've watched this thread with great interest. Is the Northwest Nuclear Consortium open to visitors?

I'm trying to pull together a midwest conference for fusor.net members (viewtopic.php?f=47&t=11408). I know you are well outside the midwest but do you ever travel to this area? You would certainly be welcome as a guest speaker.
- Garrett
RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs »

Thanks Garrett,

With regards to the invite out east, thanks also. I can't say I'm out there very often, but I'm likely to be at HEAS this year, I'll be certain to say hello if I see you there.

I haven't been affiliated with NWNC for several years, and admins haven't been responsive to my request to edit the thread of it's mention. The system resides with me now, as it should.

RT
Last edited by RobertTubbs on Sat May 06, 2017 1:20 pm, edited 3 times in total.
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Garrett Young
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Post by Garrett Young »

Understood. I was really interested in seeing your device first hand and discussing ideas. Hopefully I'll be at HEAS this year.
- Garrett
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