Fusor Forums

Some updated pictures of the system as it stands now.

-Robert

I like the new paint job. Brings it all together.

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

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!

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.

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!

> "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

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

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

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

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

RT

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

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.

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

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

You're welcome to drop by Seattle sometime and see it, it's in my living room. Otherwise wait about a year and visit the Philippines as I'll be there studying abroad for a few years and my most of my hardware but for the most extreme of export restricted materials will come with. My couch there will be open to to surfing, unless I'm out surfing.

Robert,

Can you elaborate more on the physics of plasma going into "H" mode?

I have seen this phenomenon myself or at least something similar while playing around with an induction coil and a neon tube, as the neon tube was held close to a high frequency induction coil the tube lights up but at some point the plasma goes from being just normal "neon tube bright" to something more like a flash bulb. The transition was rapid, and within seconds it melted the glass and vented the neon tube.

Steven

Steve- Here's a paper that works out the transition point:
http://iopscience.iop.org/article/10.10 ... 21/014/pdf

Jake,

Thanks, read the abstract, but the rest of it is behind a pay wall, so it's inaccessible to me unless I pay $33.

Steven

Here you go, Steven.

http://sci-hub.cc/http://iopscience.iop ... 21/014/pdf

Gave a thin film titanium coated copper target a beating last night. It puked a meganeut or so at 50kV after effectively instantly loading. Wasn't a lot left of it when I pulled it out for a look at the damage. Good stuff!

Also attaching a video, a few photos, and a cool .gif of the focal spot adjusting at lower power. First one's the gif.

https://youtu.be/jLvlHaeXsss

Robert,

Excellent as always! How thick was your Titanium coating, and are you currently cooling your target?

Bruce

You can really see the secondary electrons hitting the viewport, a magnet might work to deflect them.
What's the x-ray dose rate at the viewport?

I just finised work on my new SSPA with 1kW to drive my plasma heating.
Attached you see the numbers (going up to 850W) and a nice picture of the device.
The short video shows the very first test without adjusting the tuner - so you see almost the same power reflected as going out. The sound gives you an idea of the powersupply needed for this!! Unfortunatly the file was not uploaded due to a mp4-restriction.

@Robert: I did not see any RF-discharges in the tuner - as you did. What power levels did you reach when these issues occured?

BR,
Werner

Werner
Nice to see you using the W6PQL kits for the SSPA.
You can see my build on https://www.qrz.com/db/ZL2TUD