Simple 'Polywell' like demo

Discuss the technical details of an "open source" community-driven design of a polywell reactor.

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D Tibbets
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Joined: Thu Jun 26, 2008 6:52 am

Simple 'Polywell' like demo

Post by D Tibbets »

Needing something to do with surplus magnets harvested from microwave ovens I mounted 6 donut shaped magnets in a cube, similar to a Polywell to see what it would do to the plasma appearance in my Pressure Coooker demo fusor.
It shows the limited 'confinement' of this low energy plasma with edge cusps losses apparently larger (brighter) then the point/ center cusps* (with the N. Pole intercepting the face of the perminate magnets there are actually two 'zones' to consider - center cusp to magnet face, and edge cusp to magnet face because of the unfortionate interception of the plasma by the North pole of the magnets on the inner faces of these permanate magnets. To avoid this, I would have to use electromagnets or glue a bunch of disk magnets end to end to form a ring (?).
I have no idea of the strength of these magnets. Making some optamistic guesses, I wander if an extension of this simple setup could be used to study (at least visually) some of the plasma/magnetic interrelationships without needing electron guns, ion guns, gas puffers, etc. Just use the cathode grid for the electron source and residual air/ helium/ etc for the ion source.

Link that includes photo
http://www.fusor.net/board/view.php?bn= ... 1233125450


* Difficult to appreciate in the photo, it is more obvous visually.

Dan Tibbets
To error is human... and I'm very human.

MSimon
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Post by MSimon »

Amazing and innovative experiment. Tom Ligon has been notified.

Simon
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Tom Ligon
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Post by Tom Ligon »

And Tom Ligon has posted a reply at fusor.net!

I've been hoping one of the fusor crowd would try this! Dr. Bussard always thought this WB1 configuration might make a nice little demo unit. WB1 did make a similar glow. The face cusps are the downside.

Roger
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Post by Roger »

Is that picture of plasma similar to the gas bag graphic from a ways back..


http://www.fusor.net/board/getfile.php? ... tt_id=5329

Notice the cusps, and some scalloping... or spikes,

Really cool pix.
I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

KitemanSA
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Post by KitemanSA »

Roger wrote:Is that picture of plasma similar to the gas bag graphic from a ways back..
http://www.fusor.net/board/getfile.php? ... tt_id=5329
Notice the cusps, and some scalloping... or spikes,
Really cool pix.
Can other folk see this? I can't.

Roger
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Joined: Fri Jul 06, 2007 2:03 am
Location: Metro NY

Post by Roger »

I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

Betruger
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Post by Betruger »

KitemanSA wrote:
Roger wrote:Is that picture of plasma similar to the gas bag graphic from a ways back..
http://www.fusor.net/board/getfile.php? ... tt_id=5329
Notice the cusps, and some scalloping... or spikes,
Really cool pix.
Can other folk see this? I can't.
jpeg (as opposed to jpg) extension throws off windows, sometimes. Click the pic for the full size one.
Image

emanroga
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Joined: Wed Dec 24, 2008 5:37 am

Simple question

Post by emanroga »

I'm wondering... how do you actually create the plasma with this setup? What force is stripping away the electrons from the ions? I can think of three possibilities:

1. The wires that hold the magnets are floated at a high voltage, or
2. The whole creation is zapped either by a spark or microwaves to ionization temps, or
3. There's an electron gun.

Thanks. I think this is a fundamental under-comprehension I have of polywells in general.

Roga

D Tibbets
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Joined: Thu Jun 26, 2008 6:52 am

Post by D Tibbets »

Some additional images of the "Polywell Wannabe" with closer spaced magnets, and very low voltage and current conditions.

http://www.fusor.net/board/view.php?bn= ... 1235577201


Dan Tibbets
To error is human... and I'm very human.

D Tibbets
Posts: 2775
Joined: Thu Jun 26, 2008 6:52 am

Re: Simple question

Post by D Tibbets »

emanroga wrote:I'm wondering... how do you actually create the plasma with this setup? What force is stripping away the electrons from the ions? I can think of three possibilities:

1. The wires that hold the magnets are floated at a high voltage, or
2. The whole creation is zapped either by a spark or microwaves to ionization temps, or
3. There's an electron gun.

Roga
1) The magnets are ceramic, with high resistance, though I beleive sputtering from the metal cathode has deposited a thin conductive coating on the plasma / cathode facing side- I measured ~ 20,000 Ohms with probes seperated by ~ 1 mm on surface of the magnets. So, even if the magnets were touching the metal vessel wall they would not be at quite the same potential. But, yes the magnets were floated. The botom magnet sat on the insulated stalk of the cathode feedthroung with ~ 1 inch of clearence to the grounded vacuum shell. What relative voltage they acheived between the cathode and ground is unknown.
2) In a simple Farnsworth Hirsch (or perhaps more acuratly called a Hirsch Meeks) Fusor, the cathode produces electrons due to electric potential and thermal emission. These electrons then ionize the gas through a cascade effect. So long as the density of the gas is high enough (> ~5 microns pressure?) no other ionization source is needed (though may be included to increase efficiency). It operates much like a neon tube.
3) See 2 above. The cathode is the effective electron gun.

For a good intro to amatuer fusors read this pdf by Tom Ligon-
http://www.fusor.net/newbie/files/Ligon-QED-IE.pdf



Dan Tibbets
To error is human... and I'm very human.

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