My first plasma

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Eduardo_Machado
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My first plasma

Post by Eduardo_Machado » Sat Sep 08, 2018 9:09 pm

Hello everybody,

With the help of the many FAQs on this forum, today I finished my first demo fusor, and I would like to join the Plasma Club.

On my first try the vacuum wasn't good enough and I couldn't achieve plasma, as you can see in the picture bellow.
photo1.jpg
After that, we adjusted the vacuum pump and put more grease in the rubber, and finally we achieved plasma.
photo2.jpg
photo3.jpg
And then we had a problem. I don't know why, an arc opened between the grid and the glass. Anyone can help me explain that?
photo4.jpg

Cristiano_Machado
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Re: My first plasma

Post by Cristiano_Machado » Sat Sep 08, 2018 11:31 pm

Well done! Now we are going to the next level: real fusion.

ian_krase
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Re: My first plasma

Post by ian_krase » Sun Sep 09, 2018 4:07 am

Not sure what you mean by an "arc from the grid to the glass" -- may need better pictures.

Your glass looks too clear for sputtering to be a big problem. Is there a hot spot?

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Eduardo_Machado
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Re: My first plasma

Post by Eduardo_Machado » Mon Sep 10, 2018 11:25 am

Hello Ian,

Thank you for your help. The glass was very hot in general.

In this picture you can see that the glass melted just in the point were this arc formed. I assume there was some speck in the glass which may caused that.
IMG_1425.JPG

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Richard Hull
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Re: My first plasma

Post by Richard Hull » Mon Sep 10, 2018 7:06 pm

There was no speck in the glass. You were probably seconds or minutes away from a glass implosion event. You had an ion/electron beam focused on the glass and this area is now dangerously stressed and weakened. The central white lozenge at the core is the impact point and the toned area around the hit area is deposition of grid material. It seems that the beam came from the tip end of the spiral grid. (high field area)

This is the problem with glass demo fusors that are over driven. While running fusor II in an attempt to do fusion, back in 1998, my bell jar was hit by a jet for a period that caused the tiny area to heat to a yellow white heat. Within seconds a glass shard poped out into the interior of the chamber. I never operated fusor II, ever again!!

I immediately realized that even boro-silicate glass (pyrex and Kimax) is dangerous to use in any form of fusion effort and immediately got to work on fusor III, an all Stainless steel fusor. Regular junk soda and lime glass is even worse in this regard.

Take from this, what you will.....

Richard 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
Retired now...Doing only what I want and not what I should...every day is a saturday.

Cristiano_Machado
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Re: My first plasma

Post by Cristiano_Machado » Tue Sep 11, 2018 1:08 am

Dear Mr. Hull,

I am the father of Eduardo, I help and monitor his project. Thank you for your experience and advise, I was very concerned when I saw the beam, it was coming exactly from the tip end from the grid. At that moment we shuted everything down.

We are planning to buy a new glass, improve the mesurements and traing more with vaccum, without tension. Untill we get an inox vacuum chamber and setup a real fusor.

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Richard Hull
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Re: My first plasma

Post by Richard Hull » Tue Sep 11, 2018 5:14 am

Sir, I am glad Eduardo has a watchful parent at hand. Glass makes a fine demo device, but the tendency to over drive it is a powerful one. The demo fusor is more to allow the study of plasma and how they react as voltage and current are varied. The visual observations are of importance. The most interesting is to see the ion/electron beams exit the inner grid as the vacuum increases or decreases at varying voltages and currents.

However, an intense beam hitting the glass can certainly be observed, but only for a few seconds. Local heating of the glass can be intense at beam contact. The spiral grid is fine, but a closed grid with no sharp points will tend to issue many beams of moderate intensity rather than one intense one.

The deeper the vacuum just short of extinction of the visible glow the more likely that multiple beams will develop. (note my avatar image)
This was seen at a vacuum level of 10 microns in my old fusor III and photographed through a 1" view port window on the stainless steel vessel.

The beams are a sign and symbolic of a good usable vacuum in a fusor. In a real fusion situation the beams grow more needle like and more faint.

I attach a couple of good images of a real fusion star and then a demo fusor star.

Richard Hull
Attachments
best red star.JPG
Real fusion taking place hear in fusor IV. Tiny pin point core. Red beams of deuterium
2001 (12).JPG
An ideal demo fusor image no fusion here. vacuum perfect
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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Dennis P Brown
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Re: My first plasma

Post by Dennis P Brown » Tue Sep 11, 2018 10:45 am

I agree with Richard, the glass chamber is just too dangerous to use if one is driving the plasma enough to get those results. I would never allow that to occur in my chamber against my window - it is a disaster in the making.

As for fusion, you had better build a proper metal chamber because a glass chamber will not withstand the plasma of a real fusion power supply for very long.

Of course, always wear safety glasses and and ALWAYS surround any glass vacuum chamber that is under vacuum with a grounded wire screen/cage!

At the very least one should have a "ball" end piece on any wire end to prevent a focused high voltage point from developing just as it did in your system. I do, in fact, terminate all my high voltage wires and bolts using metal 'balls" in this very manner so corona issues do not develop.

ian_krase
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Re: My first plasma

Post by ian_krase » Tue Sep 11, 2018 7:46 pm

One thing that might be tried is to have separate beam blocks and structural vacuum chamber. The former can be made of cheap thin glass.

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Rich Feldman
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Re: My first plasma

Post by Rich Feldman » Tue Sep 11, 2018 11:32 pm

What if the chamber were lined with a non-structural metal screen that you can see through?
For example, fine woven wire cloth like that in fuel filters. Or perforated sheet metal like in microwave oven doors.

If the holes are small enough, and/or optical transparency low enough, ion beams and e-beams won't hit the glass so hard.
You can subdue the room lights to get a better view inside the screen.

Or have a nonstructural metal sheet between the central grid and the glass.
It would have a hole to look through, which can be covered with an unstressed, sacrificial glass window as others have suggested.
Richard Feldman

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