Google Polywell Fusion Counter

rnebel · Post by **rnebel** » Fri Feb 06, 2009 8:02 pm

OK Art. I'm game. We don't know if the cusps are quasi-neutral. Use your theory and give me a quantitative prediction as to how the WB-7 will behave.

icarus · Post by **icarus** » Fri Feb 06, 2009 8:09 pm

Art said:

In any case, I duly note that you are also not able to put forth a self-consistent theory of polywell operation. Don't feel bad. Nobody else can either.

Useless snide remarks like these are not getting the understanding advanced. In my defence (if it is even needed), I have never attempted nor claimed to have any theories on Polywell, although many others have. We have insufficient data to go on and its like doing a jigsaw while someone else is hiding some pieces.

You also said to rnebel:

I agree with you completely (except maybe the last sentence), so there must be a misunderstanding somewhere. My question is, "Is the plasma in the throat of the cusp (underneath the magrid) quasineutral?" I say it is, and it sounds like you agree with me. Can we move on from there?

Haven't you have missed the key point about ambipolarity? Is not your sheath model for the cusp throats based on the ambipolar assumption, so it is not right, as I understand it.

KitemanSA · Post by **KitemanSA** » Sat Feb 07, 2009 1:13 am

WARNING WARNING : TOPIC RECLAMATION IN PROGRESS

Google "Polywell fusion" = 16,000, up from 15,900 in only 5 hours..

THANK YOU : THAT IS ALL

Tom Ligon · Post by **Tom Ligon** » Sat Feb 07, 2009 1:26 am

Aw, Kiteman, this is fun!

Not saying I'm an expert at the theory or math, but I've seen the guts of the theory behind the Polywell. Child/Langmuir Law (based on Poisson's Equation) is the starting point for the whole machine, and I know Bohm was in there too, so I know they're hardly neglected.

It will be entertaining to see what Art does with this. His arguments baffle me since they don't jibe at all with my understanding of what makes it tick (this is usually my warning that somebody good at crunching numbers has missed at least one basic principle of operation).

KitemanSA · Post by **KitemanSA** » Sat Feb 07, 2009 2:00 am

Yup!

It is especially GREAT to have Dr. N weigh in on this. I liked his "Polywells are quasi-neutral. They aren't ambipolar." That was new language for me and it helped solidify things nicely. Also, his "Although some of the posters here may not agree with my comments, the WB-7 does" was truly fine!

Munchausen · Post by **Munchausen** » Sat Feb 07, 2009 5:35 am

Useless snide remarks like these are not getting the understanding advanced.

Debating on a forum like this is, after all, a recreational pastime. Since all calculations are "back of the envelope", dr. Carlson now finds himself in a room littered with envelopes scribbled with formulas and calculations, feeling like a cat playing with a mouse, enjoying its pitiful attempts to escape for while before giving it the final blow. He deserves it.

I anticipate two more threads in the near future. One for rubbing salt into the wounds of the true believers, one for rehabilition and solace to those who have gotten their feelings badly hurt.

Art Carlson · Post by **Art Carlson** » Sat Feb 07, 2009 2:39 pm

Tom Ligon wrote:It will be entertaining to see what Art does with this. His arguments baffle me since they don't jibe at all with my understanding of what makes it tick (this is usually my warning that somebody good at crunching numbers has missed at least one basic principle of operation).

From my point of view, the optimal outcome would be that somebody points out a "basic principle of operation" I have been missing. I'm always grateful to those who teach me some physics.

Are you going to come out of cover on this one, Tom? Does your picture of the potential roughly match that of Solo? Do you see any problem with my calculation that the plasma in the cusps must be quasineutral? Do you have any good reason to believe otherwise?

Tom Ligon · Post by **Tom Ligon** » Sat Feb 07, 2009 3:14 pm

I think you guys are quibbling over semantics here.

You seem to have a fundamental misunderstanding, which Dr. Nebel has pointed out repeatedly, of the electron behavior outside the magrid. I have no understanding at all why you persist in thinking the electrons want to go to the walls of a machine with precisely one anode, the magrid. If you object to the emitter being at the same potential as the walls, so that the electrons can, unenthusiastically, go back to the walls, fine, we'll bias the cathode a hundred volts positive of the walls, and that will be that.

Child and Langmuir would be amused. They understood simple diodes ... and Child published a century ago this year, didn't he? WB-7 is a vacuum tube diode. Electrons in a diode go from cathode to anode.

I believe you're a smart fellow with a sign wrong in your concept of how this thing works. I'm wondering if you have made a mistake Dr. Bussard once made, which I caught him on: confusing electron kinetic energy with potential energy?

Speaking of Child and Langmuir, one of the first things I did upon coming on board at EMC2 was confirm cathode current in WB-2 followed V^(3/2).

My own experimental results with PXL-1 (a closed-box machine which should have had horrendous cusp losses) tell me there are things going on in the cusps that are fascinating. PXL-1 had a reproducible mode that blocked the cusps, which it would enter as if somebody opened a switch. I discovered it was real when the magnets switched off during a test when the plasma was still at high potential. The energy release was incredible, evidenced by behaviors only possible if the energy was stored as circulating electrons ... and I've heard of similar events happening with electron storage rings. Even in a machine in which the walls are clearly an anode, the cusps can block. I think Rick may finally be getting a glimmer of why, but I've suspected a role for cold electrons since about a week after the event.

Tom Ligon · Post by **Tom Ligon** » Sat Feb 07, 2009 3:25 pm

Kiteman,

Polywell fusion without the quotes just returned 29,300 links from my computer! With quotes it was more like 4900. Just exactly how do you formulate your search? Or are we approaching a "Polywell fusion" singularity?

KitemanSA · Post by **KitemanSA** » Sat Feb 07, 2009 3:28 pm

Art Carlson wrote:
Tom Ligon wrote:It will be entertaining to see what Art does with this. His arguments baffle me since they don't jibe at all with my understanding of what makes it tick (this is usually my warning that somebody good at crunching numbers has missed at least one basic principle of operation).
From my point of view, the optimal outcome would be that somebody points out a "basic principle of operation" I have been missing. I'm always grateful to those who teach me some physics.

In another thread, you seem to have agreed that this graphic is your view. If this indeed represents your view of the potential field

then that is the "basic principle of operation" you have been missing. This chart is all wrong! Given that the potential outside the Magrid goes to ground at r=infinity, then the well is BELOW ground to a magnitude of about .8 of the MaGrid potential. It is NOT above ground at .2 times MaGrid potential.

Munchausen · Post by **Munchausen** » Sat Feb 07, 2009 3:30 pm

Can't you simply tell us what will happen if there is quasineutrality in the cusps?

KitemanSA · Post by **KitemanSA** » Sat Feb 07, 2009 3:35 pm

Tom Ligon wrote:Kiteman,

Polywell fusion without the quotes just returned 29,300 links from my computer! With quotes it was more like 4900. Just exactly how do you formulate your search? Or are we approaching a "Polywell fusion" singularity?

Wha??? Are you Googleing?
I have pretty generic preferences, search all languages, don't filter... and I am still getting 16,000 hits for Polywell fusion, no quotes. With quotes it goes to 4,440.

Tom Ligon · Post by **Tom Ligon** » Sat Feb 07, 2009 4:00 pm

Munchausen,

I'm not sure who you are asking, but assuming it is me, here goes.

Quasineutrality: Almost neutral. Not quite. Lets say 1.000000000e12 deuterons per cc and 1.000000001e12 electrons per cc in the plasma? Excess electrons. A wire stuck down in the plasma says there's a negative net charge. Whoopee.

At what potential? The drive energy is the difference between the emitter cathode potential and the magrid, so not above that. The fast elctrons have, at this point, high kinetic energy, but their potential with respect to the walls and magrid must not be confused with their kinetic energy.

So what's around? There's a magrid nearby attached to a high voltage power supply, positive potential, that the electrons dearly want to get to. Or there are metal walls outside the magrid at about the potential of the emitter ... to reach it the electrons must give up all their kinetic energy. More than all their kinetic energy if we bias the cathode slightly positive for good measure.

There is a virtual cathode which forms in the center of the machine due to converging electrons. There may also be a virtual anode formed by a convergence of ion trajectories in the middle of the machine. Advanced subject ... save it for bremsstrahlung arguments.

What of the poor electrons shed by the deuterium ionized just inside the magrid? What are they to do? The fast electrons converge on the center volume. Let's assume they have sufficient current to space-charge-limit the center: they will lose their kinetic energy as the potential reaches something approaching the cathode potential from which they were emitted: a fully developed potential well inside the magrid. The cold electrons can't go there because they lack the kinetic energy to overcome the potential. Likewise they can't go outside the magrid toward the cathodic wall potential. What is left for them? Attempt to get to the anode, the magrid. But they are discouraged from a direct path by the encircling magnetic fields. All they can do is slide along the magnetic field, taking little jumps where they can to sneak up on the magrid, oscillating in a path that avoids the cathodic areas. There is one spot where they can do this. The cusps. The cusps are the home for cold electrons. What the cold electrons do in the cusps will be vitally important in understanding the behavior of the machine. And they're just as negatively charged as the fast electrons.

We're all agreed the plasma is quasi-neutral. Move on. Quit trying to read in to that things other than the driving principles really at work.

Art Carlson · Post by **Art Carlson** » Sat Feb 07, 2009 4:57 pm

KitemanSA wrote:In another thread, you seem to have agreed that this graphic is your view. If this indeed represents your view of the potential field <image> then that is the "basic principle of operation" you have been missing. This chart is all wrong! Given that the potential outside the Magrid goes to ground at r=infinity, then the well is BELOW ground to a magnitude of about .8 of the MaGrid potential. It is NOT above ground at .2 times MaGrid potential.

First, what I actually said was that the potential profile sketched was "the picture that polywell advocates have in mind". I happen to think that the profile along the cusp will be monotonic - but I haven't justified that yet.

Second, your picture does not agree with that described by Tom Ligon (in a post between yours and mine). In particular, if the central well is at a lower potential than the walls, the electrons will all go skitting across the hump in potential (if there is one) near the magrid and careen into the wall at high energy. Not a recipe for a successful fusion reactor.

Art Carlson · Post by **Art Carlson** » Sat Feb 07, 2009 5:11 pm

Tom,

I think I can sign off on (nearly) everything you wrote.

Tom Ligon wrote:What of the poor electrons shed by the deuterium ionized just inside the magrid? What are they to do? ... All they can do is slide along the magnetic field, taking little jumps where they can to sneak up on the magrid, oscillating in a path that avoids the cathodic areas. There is one spot where they can do this. The cusps. The cusps are the home for cold electrons. What the cold electrons do in the cusps will be vitally important in understanding the behavior of the machine. And they're just as negatively charged as the fast electrons.

We might want to keep the EXB drift of those cold electrons in mind, but maybe it won't matter. In my calculation to show quasineutrality in the cusps I ignored the possibility of trapped electrons, not because I assumed there weren't any, but because they would only make my argument stronger.

Tom Ligon wrote:We're all agreed the plasma is quasi-neutral. Move on. Quit trying to read in to that things other than the driving principles really at work.

I'll take you at your word on that, but I'd like to start a new thread, first to take it back to the theory forum, second to keep the discussion better organized. I think this discussion was necessary because a lot of people seemed to believe that there were no ions in the cusps.