A self-generated, or "bootstrap," current!

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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Axil
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A self-generated, or "bootstrap," current!

Postby Axil » Thu Nov 14, 2013 8:23 pm

http://phys.org/news303571573.html

Plasma experiment demonstrates admirable self-control

This is certainly strange, does anyone know what produces this self-generated, or "bootstrap," current?

D Tibbets
Posts: 2775
Joined: Thu Jun 26, 2008 6:52 am
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Re: A self-generated, or "bootstrap," current!

Postby D Tibbets » Fri Nov 15, 2013 11:51 pm

Yes, I know about the bootstrap current, err, well, at least a little... :)

In a Tokamak and any magnatized plasma device(?) the plasma has a preferred direction. As such it has a current going from point A to point B in the circular torus. The flow continues around the torus , repeating very many times. This current produces a magnetic field oriented with the plasma flow and is a well understood feature of Tokamaks. It may have some benifits and certainly also some disadvantages. Manipulating this flow along with the other magnets, temperature adjustments, etc, etc. are possible interventions that are needed on millisecond (?) time scales in order to abort harmful macro instabilities that are otherwise unavoidable do to the geometry of the B field/ particle interactions. The Polywell is advertized as avoiding this very complex problem because of the geometry of the confining B fields- always convex towards the plasa. And, since the plasma itself is not magnatized in the Polywell (with apparently minor exceptions at the electron Wiffleball border where the electron turns around) the plasma itself does not induce ExB drift or magnetic macro instabilities like in a magnatized plasma. This along with centrifugal effects in a torus leads to challenges in keeping the plasma restricted to the ideal position/ radii in the torus.

Compare this to a Polywell. The near spherical geometry with in and out charged particle motions and possibly left and right angular momentum motions there is certainly current (moving charges) but since the flows are in opposite directions, they cancel each other out , at least on the large scale. This is why the Polywell is not a magnatized plasma. If you were to introduce a rotating aspect to the plasma it would become magnatized. Whether this is good or bad is debatable, but it is not a component of a basic Polywell.

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

Robthebob
Posts: 383
Joined: Mon Jun 23, 2008 11:12 pm
Location: Auburn, Alabama
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Re: A self-generated, or "bootstrap," current!

Postby Robthebob » Sat Nov 16, 2013 6:47 am

yawn, yeah, that's not news.
Throwing my life away for this whole Fusion mess.


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