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

Posted: Thu Jul 30, 2015 12:52 am
by RobertTubbs
Some updated pictures of the system as it stands now.

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

Posted: Thu Jul 30, 2015 1:21 pm
by Andrew Robinson
I like the new paint job. Brings it all together.

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

Posted: Sat Aug 29, 2015 6:38 am
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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Re: Tubbs Beam-on-Target Effort [Neuts/Pics/Tips]

Posted: Sat Feb 13, 2016 7:03 am
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!

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

Posted: Thu Jun 02, 2016 12:09 pm
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.

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

Posted: Sun Jun 05, 2016 4:37 pm
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!

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

Posted: Mon Jun 06, 2016 12:49 am
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

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

Posted: Tue Apr 25, 2017 7:50 pm
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

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

Posted: Tue Apr 25, 2017 11:29 pm
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

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

Posted: Wed Apr 26, 2017 12:23 am
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