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

Current images of fusor efforts, components, etc. Try to continuously update from your name, a current photo using edit function. Title post with your name once only. Change image and text as needed. See first posting for details.
RobertTubbs
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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Post by RobertTubbs » Thu Jul 30, 2015 12:52 am

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 » Thu Jul 30, 2015 1:21 pm

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 » Sat Aug 29, 2015 6:38 am

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 » Sat Feb 13, 2016 7:03 am

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 » Thu Jun 02, 2016 12:09 pm

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 » Sun Jun 05, 2016 4:37 pm

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 » Mon Jun 06, 2016 12:49 am

> "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 » Tue Apr 25, 2017 7:50 pm

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 » Tue Apr 25, 2017 11:29 pm

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
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG

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

Post by RobertTubbs » Wed Apr 26, 2017 12:23 am

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

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