Question: How is the electron not getting into the machine?

Discuss how polywell fusion works; share theoretical questions and answers.

Moderators: tonybarry, MSimon

hanelyp
Posts: 2261
Joined: Fri Oct 26, 2007 8:50 pm

Re: Question: How is the electron not getting into the machi

Post by hanelyp »

Any models which include estimates of the plasma contribution to the magnetic field?
The daylight is uncomfortably bright for eyes so long in the dark.

Robthebob
Posts: 383
Joined: Mon Jun 23, 2008 11:12 pm
Location: Auburn, Alabama

Re: Question: How is the electron not getting into the machi

Post by Robthebob »

I'm sure Matt only has the coils modeled, which is still extremely useful. It's possible to look at the system from a low beta limit; in fact many drifts are determined solely from B-field alone.

I think there are writings on electron density and distribution, I think happyjack mentioned that it's a hollow sphere in core, as far as electron beams out of the machine, I actually doubt that makes a dent in the machine field.
Throwing my life away for this whole Fusion mess.

KitemanSA
Posts: 6179
Joined: Sun Sep 28, 2008 3:05 pm
Location: OlyPen WA

Re: Question: How is the electron not getting into the machi

Post by KitemanSA »

According to several of the old time posters to this forum, the plasma can be represented by an image magnet placed within the volume of the plasma. IIUTC, a scaled set of magnets with reversed scale current will act as the plasma would. I asked mattman to include the image magnets several times but for some reason he didn't.

ladajo
Posts: 6258
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast

Re: Question: How is the electron not getting into the machi

Post by ladajo »

As I recall Indra did that.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

KitemanSA
Posts: 6179
Joined: Sun Sep 28, 2008 3:05 pm
Location: OlyPen WA

Re: Question: How is the electron not getting into the machi

Post by KitemanSA »

Yup, and Icarus claimed to have participated. And IIRC, kcdodd used the data in a bag calc in Mathematica; but I may be misremembering.

Robthebob
Posts: 383
Joined: Mon Jun 23, 2008 11:12 pm
Location: Auburn, Alabama

Re: Question: How is the electron not getting into the machi

Post by Robthebob »

KitemanSA wrote:According to several of the old time posters to this forum, the plasma can be represented by an image magnet placed within the volume of the plasma. IIUTC, a scaled set of magnets with reversed scale current will act as the plasma would. I asked mattman to include the image magnets several times but for some reason he didn't.
I'm dumb, what's image magnet? Also I'm just not convinced there's current from the core... if it's symmetric, like guns at all faces, any flow from one side should be generated by the other side thus sum to zero. If it's not symmetric, then there may be bigger problems.

So in spherical coordinate, no r direction current at the core, because (and I still dont get why) of hollow sphere-like ball of plasma. so it should just be phi and theta. so del cross B is J, J has comp in phi and theta, means if B has comp in r direction, it depends on phi and theta, which is hella strange, because the machine is somewhat symmetric in phi and theta directions.

Basically I'm really confused.
Throwing my life away for this whole Fusion mess.

KitemanSA
Posts: 6179
Joined: Sun Sep 28, 2008 3:05 pm
Location: OlyPen WA

Re: Question: How is the electron not getting into the machi

Post by KitemanSA »

Indra? Icarus?

Robthebob
Posts: 383
Joined: Mon Jun 23, 2008 11:12 pm
Location: Auburn, Alabama

Re: Question: How is the electron not getting into the machi

Post by Robthebob »

I think I figured it out. Consider a conducting sphere, hollow or not, if you shoot electron beam at it, there's going to be flow in the + and - phi direction and + and - theta direction (and all linear combinations of phi and theta). As the current travel in those directions, it should reduce in strength, because the electrons are traveling down curved directions (probably not because the electrons are thermally interacting with each other, we can assume this base on what Dr. B and others said in the past). By the time it gets to the impact site of other guns, the flow from the first gun will not be able to cancel out the flow of the other guns.

Indeed then there'll be current in the phi and theta direction, the flow would be Max in all directions at the impact site, then between impact sites (looking at say theta=0 plane varying phi in the positive direction) the flow would be zero, then when you get to another impact site, the flow would be max in the other direction, and as soon as you get pass that max, it'll jump to max in the other direction.

So max, decrease to zero, decrease to negative max, jump to max, repeat, all the way around when looking at any planes that cuts through the center of the plasma ball, roughly speaking. (still assuming the electrons arent interacting with each other)
Throwing my life away for this whole Fusion mess.

happyjack27
Posts: 1439
Joined: Wed Jul 14, 2010 5:27 pm

Re: Question: How is the electron not getting into the machi

Post by happyjack27 »

you can check out the "happyjack27" channel on youtube to see some sim runs of em-nbody.

on the latter runs there are axis mode sliders at the bottom, and i run through a few of them.

these xmode, ymode, and zmode sliders change what their respective axises represent.

the following is a key to what each different position of the sliders does.

you can also find this info in bodysystemcuda.cu starting at about line 700.

========== negative numbers stretch the spatial axis

-3: distance from center cubed (= volume enclosed by a sphere extending to this point, centered about the core)
-2: distance from center squared (= rate of change of volume covered as you move outward/inward, or relative surface area of a sphere at this distance)
-1: distance from center

=== normal spatial position

0 normal - spatial position

=== potential energy

1 potential energy (electric)

======inertial

2 total inertia
3 radial inertia
4 axial inertia
5 momentum along that axis

====== total (electric + magnetic) force

6 total force
7 radial force
8 axial force
9 force along that axis

==== electrical force

10 total electrial force
11 radial electrical force
12 axial electrical force
13 electrical force along that axis

==== magnetic force

14 total magnetic force
15 radial magnetic force
16 axial magnetic force
17 magnetic force along that axis

==== nuclear cross section (a nonlinear function of velocity)

18 nuclear cross section (multiply this by density squared to get the fusion rate)


-----------------

re: image coils. from what i understand, the theory is thus:

charged particles travel to cancel out the magnetic field. as they do so, they, by traveling, create a magnetic field equal and opposite to the one they're reacting to.
thus, in the aggregate they create a mirror image of the magnetic field, with the surface of zero magnetic flux being the "mirror".
in a polywell, at plasma balance (b=1), that mirror surface - surface of zero magnetic flux - is a perfect sphere inside the magrid.
the mirror image of the magrid, with a sphere inside it being the inversion surface, is a smaller magrid, of opposite polarity.
thus, to map the mag field inside a polywell at equilibirum, just put an inverted magrid inside another, such that the union of their magnetic fields create a spherical null-flux surface between them.

and viola!

a rather elegant solution, imo.

(from the movie "Primer": Aaron: What are we saying that is? Abe: Hopefully, near room temperature. Aaron: What is that about, uh, the best mathematician's a lazy one?) ;-)

Robthebob
Posts: 383
Joined: Mon Jun 23, 2008 11:12 pm
Location: Auburn, Alabama

Re: Question: How is the electron not getting into the machi

Post by Robthebob »

I dont know if I buy that the electrons form opposing magnetic field at the core. I understand, sorta have to talk to people that are more well learned than I am, that charge particles opposes applied B field because in their circling around field lines makes a current loop that makes a oppose B field.

The reason I say this is because this diamagnetic behavior occurs only when electrons are on field lines, at the core, the fields are extremely weak, the nature of the polywell design throws electrons off field lines when their at the center of the machine by curvature drift.

I'll buy that the electron distribution at the core is hollow shell sphere, even though I dont understand how it is like that, but I think Dr. B and others said it was like that once upon a time, so sure... if they're organized by this hollow shell configuration in regions of low field, I dont see how they can generate current to generate B field to push the machine field back.

I'm convinced the current, if assuming a hollow shell config, is due to flow from the electron beams into the machine. Granted, what you suggest does not require any symmetry in beams into the machine, I think my explanation requires E gun for every face.

Can you point me to a paper that you read that said that?

Edit: disregard what i said about flow from e beam impact driven current, it doesnt work.

In other news, in class we just went through minimum energy principle, there are 6 terms in the displacement fluid work equation, I can work out all 6 terms (i think if you assume some stuff, still dont know how the current is going to look like in a polywell) in order to prove its MDH stable.

It's not as simple as field convex everywhere into the machine, it's still really good cus electrons are most likely going to end up at the center and not go anywhere due to curvature drift.
Throwing my life away for this whole Fusion mess.

happyjack27
Posts: 1439
Joined: Wed Jul 14, 2010 5:27 pm

Re: Question: How is the electron not getting into the machi

Post by happyjack27 »

the image coil thing has something to do with superconductors -- i remember that. the reasoning was something to the effect that a plasma in vacuum is essentially a superconductor, since there is no electrical resistance. that could be an erred explanation, but it's something to that effect.

but come to think of it, electrical permittivity of free space: finite and nonzero, if i recall correctly. so the analogy might not hold.

hanelyp
Posts: 2261
Joined: Fri Oct 26, 2007 8:50 pm

Re: Question: How is the electron not getting into the machi

Post by hanelyp »

As more plasma is being produced inside the machine, it expands against the magnetic field. This relative motion of conductor and magnetic field induces currents which generate an opposing magnetic field. The plasma isn't quite a superconductor, but it is a very good conductor. So the magnetic field is slow to penetrate the plasma.
The daylight is uncomfortably bright for eyes so long in the dark.

Robthebob
Posts: 383
Joined: Mon Jun 23, 2008 11:12 pm
Location: Auburn, Alabama

Re: Question: How is the electron not getting into the machi

Post by Robthebob »

@happyjack27: magnetic fields can exist within plasma, magnetic field cannot exist in a superconductor.

@hanelyp: you mean when more electrons reach the center? The event you're describing is not a steady state effect that occurs when input/loss equilibrium is achieved, because the plasma cannot keep growing to push on the B field.
Throwing my life away for this whole Fusion mess.

happyjack27
Posts: 1439
Joined: Wed Jul 14, 2010 5:27 pm

Re: Question: How is the electron not getting into the machi

Post by happyjack27 »

he's describing the path -to- steady state, from which one can infer things about steady state.

"push" does not neccessarily imply movement. i can push a whole lot on a door, but unless i turn the knob, it ain't opening. push implies force, not work. if the force is balanced on both sides, there is no net acceleration.

hanelyp
Posts: 2261
Joined: Fri Oct 26, 2007 8:50 pm

Re: Question: How is the electron not getting into the machi

Post by hanelyp »

Actually, the plasma does keep growing outward in volume. This expansion through the magnetic field is cross field diffusion, a loss mechanism. Necessary for steady state exclusion of the magnetic field as the plasma is a less than perfect conductor.
The daylight is uncomfortably bright for eyes so long in the dark.

Post Reply