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Oakland University Low Powered Fusor Update

Posted: Mon Feb 15, 2016 5:39 pm
by Brian_Neumeyer
Hello All,

An update with a few questions!

First Run- Sort of Successful
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Last week we turned it on for the first time. While we did get a bit of that delightful purple glow, it did not achieve "star mode" with a ball in the center.

So we are at the trouble shooting part of this guy.

The Setup
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Going clockwise starting from the upper right E-Stop button
-Black thingy with white labels on it & gray wire: Vacuum gauge
-Silvery disc: Fusor chamber
-White cylinder with 3 wires: Rectifier
-Red cylinder: variac
-Gray box: neon sign transformer
-Outlet box: 2 constantly on, 2 attached to E-Stop
-Red & gray thingy: vacuum pump

The Stats-need to be updated. Ask for any other ones that you'd like
-Pressure: We seem to have a leak somewhere, or our pump is not as effective as advertised. We held around (1800 mTorr? @Aaron verify) for the duration of the run
-Voltage: We used a variac to go from 0 to 110 VAC, which with our neon sign transformer means we went from 0 to around (7-7.5 kV? @ Matt M. verify) for the run

We're pretty sure that the reason we didn't go star mode is due to the pressure issue. If there's any other potential reasons we'd love to hear it.

Some other questions though:
-There was some arcing at the base of our feed through stand off. It went on and off periodically, with seemingly no pattern. What could cause that, should we be worried, and how can we stop it? It didn't seem to connect with the inner grid at all, just fizzled around at the base.
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-We observed glowing at the pressure gauge nozzle input. We have two barbed brass fittings on the top for a vacuum and gauge. The gauge hole had a glow for the duration of the run, and it was more red/yellow than the purple of the inner grid. What could cause that? The other hole that led to the vacuum pump did not have the same behavior, at least not noticeably.
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This is an exciting progression for us, and we're still working to get a full star mode. If there's any experienced fusor-ers in the Oakland-Macomb County area around Oakland University (in Michigan) we'd love to sit down and bounce ideas over some coffee (or your drink of choice ;-))

*edit- apparently the bit code isn't fully implemented on these boards, hopefully this imgur trick will work

Re: Oakland University Low Powered Fusor Update

Posted: Mon Feb 15, 2016 9:26 pm
by John Futter
Brian
no pics
This happens all to often with remote photo storage sites

It would be better to upload the pics to this site directly and place inline
Which will preserve this thread for all time

Re: Oakland University Low Powered Fusor Update

Posted: Mon Feb 15, 2016 9:50 pm
by Jim Stead
Looks like he added bbcode to adjust the picture size in the img tags. The site doesn't seem to be accepting it.
Here are some URLs to the pictures-

http://i.imgur.com/rW9k9f2.jpg
http://i.imgur.com/QUf8dxw.jpg
http://i.imgur.com/mEENGIg.jpg
http://i.imgur.com/UTWiPpr.jpg

Re: Oakland University Low Powered Fusor Update

Posted: Tue Feb 16, 2016 12:45 am
by John Futter
Brian/ Jim

you need to adjust the picture size manually in something like Irfanview then under image/resize-resample to 1024 x 768 or lower resolution
re-save to a convenient upload subdirectory ready to upload to this board

Re: Oakland University Low Powered Fusor Update

Posted: Tue Feb 16, 2016 2:41 am
by Brian_Neumeyer
John Futter wrote:Brian/ Jim

you need to adjust the picture size manually in something like Irfanview then under image/resize-resample to 1024 x 768 or lower resolution
re-save to a convenient upload subdirectory ready to upload to this board
I guess bit code isn't fully implemented on this board. Found a work around with imgur though.

With Imgur, if you add an "m" to the url immediately before the ".suffix" it will decrease the size. Putting an "s" will make it even smaller.

So now that the formatting is good how's the content?

Re: Oakland University Low Powered Fusor Update

Posted: Tue Feb 16, 2016 4:36 am
by Jim Stead
Brian,

I noticed in your third picture that your pump oil is a yellow milky color. Appearance isn't everything, but that color reminds me of a water/oil mix. If that's what it is, and your pump oil is actually contaminated with that much water, it will affect your vacuum significantly.

Regarding the glow in the vacuum barb. I noticed the power cord for your vacuum gauge is not plugged into the same AC supply that the HV supply and transformer are, and that your chamber ground is coming off of your HV supply ground. I'm wondering if there is a ground potential difference that is causing that glow. Take a look at Richard's FAQ post regarding star grounding. If you put the gauge, pump, chamber, variac, the 1900 boxes, etc. all on the same central ground point I believe you will eliminate that glow... and increase your safety as well.

Re: Oakland University Low Powered Fusor Update

Posted: Tue Feb 16, 2016 9:16 am
by Rich Feldman
Brian et al,

1. I think the small inline images are sufficient in 95% of the cases, and make the board more friendly to mobile and non-broadband users. This time it was handy to have links to full size files for a closer look. Inconsiderate users sometimes embed huge images that nobody can view all at once without scaling, which is not the duty of a browser. Here's why the "upload file" forum tool is good. If the file is an image, you get an inline picture that loads fast and can be clicked to see the full uploaded file, preserved on the fusor.net server. I think it limits the file size to 1 MiB. Who needs more than that on a discussion forum that isn't about photography?

2. Since the pump oil was called into question, try reading FAQs about rotary pump maintenance. For a closer look you can drain some oil into a clear cup, then put it back into the pump. It should be non-cloudy & light in color, like vegetable oil.

3. There are lots of leak-detection hints in this forum, including the vacuum FAQs. It's good that your chamber has a dedicated port for the vacuum gauge. The same gauge would show a lower pressure if connected close to the pump inlet, because your skinny chamber-to-pump hose resists the flow of gas. Keyword: vacuum conductance.

Re: Oakland University Low Powered Fusor Update

Posted: Tue Feb 16, 2016 6:24 pm
by Richard Hull
Brian, I have added your name to the plasma club.

Richard Hull

Re: Oakland University Low Powered Fusor Update

Posted: Tue Feb 16, 2016 6:51 pm
by Brian_Neumeyer
Richard Hull wrote:Brian, I have added your name to the plasma club.

Richard Hull
Richard,

While I do enjoy my name being in it, I am a part of a team. Would it be possible to have Aaron Garofalo, Matt Michalewicz, Matt Bloom, and Steve Stewart on the wall as well? If not, the Oakland University HC/SD Team would work instead of just my name.

Re: Oakland University Low Powered Fusor Update

Posted: Fri Feb 19, 2016 4:24 am
by AllenWallace
This looks very nice!

I suggest you hook up your vacuum gauge directly to the pump and determine the pump pressure. This will allow you to discover if your high pressure is due to a pump limitation or a chamber leak.

Please be careful about implosion. I don't see any shield about your vacuum chamber. You chamber is made out of glass?

The visible discharge in the gauge hole is a total mystery to me. I assume that the top plate is well grounded via the mounting bolts? I've seen discharges travel down tubes, much like a neon sign tubing. If you plug and/or disconnect your gauge does it change the discharge?

Look for leaks by squirting suspect areas with isopropyl alcohol, and looking for a change in your vacuum pressure. Have you used teflon tape? Please describe your high voltage feedthrough.

Good luck!

Allen