Why people are so optimistical to Polywell?

[Joseph Chikva]

InterNET reporters.

Ok, thanks. Are those people influential enough for moving forvard the projects?
Even Polywell with 7 millions budjet. I do not talk about ITER's multi-billions.

[Betruger]

Yes like I said Bussard or Nebel (if I remember correctly) said that during the ~2007 period after WB6, it was in non-negligible part thanks to people like MSimon that the project picked up again.

Now of course that was then and possibly the circumstances of that period may never happen again, for a few individuals like MSimon to have such an influence. Most people who need to know about Polywell, do. The project has, by all accounts, enough funding to reach the next few major milestones, at least all the way up to a demo phase.

[D Tibbets]

Chikva, you are taking things out of context.

Yes, I am taking some things from long text and then trying to answer them.

Electron lifetimes (at ~ 10KeV average energies)

In a ~ 1 Meter machine diameter= ~ 5-6 passes in an opposing magnet mirror machine.= ~ 0.2 microseconds

In a Polywell with cusp confinement (No Wiffleball effect) ~ 60 passes= ~ 6 microseconds.

In a Polywell with Wiffleball effect (assume ~100 fold decrease in effective cusp hole size) = ~ 6,000 passes= ~ 600 microseconds

As I understand those are projected data not considering stability criteria - only single particle behavior.

As far as 0.4 Beta being an upper limit for Tokamaks before confinement suffers. I speculate this is due to the concave towards the center B fields. The Polywell does not have any concave towards the center B field lines. That is why it is claimed to be immune to MHD instabilities.

I always thought before that toroidal devices are more stable than mirror machines. It's new for me. Thanks.

No, the particle (electron ) lifetimes are based on reports. whether they make straight collionless passes or multiple collision zig zag passes is irrelivent to this confinement time/ distence/ passes. Electron confinement has been measured (apparently) without Wiffleball, with Wiffleball. The passes are ~ 10,000 in WB6 without recirculation. Recirculation increases passes to ~ 100,000 before final loss (probably at low energy). At ~ 10,000,000 meters per second speed at ~ 10KeV energies, the passes, dwell time, machine diameter all feed into the calculation.

From a MHD standpoint the Polywell is more stable than any machine that has magnetic surfaces concave towards the center of the plasma. It is the cusps that makes the relative brief confinement limits.

Also, my impression is that the individual ions and electrons are not exchanging much energy on the edge. It is the excess electron space charge that is creating the potential well that slows the ions as they climb up, and it is the ion- ion high collisionality at the ion cool edge that drives annealing. From first order, the electrons can be ignored in this local effect.

Dan Tibbets

[Joseph Chikva]

Excellent. May be Polywell is more stable than other mirror machines. By my opinion in-yang has more attractive shape. But may be - I do not know.
But even in case of the best mag field topology any mirror machine can not be more stable than TOKAMAK.
You quoted here confinement durations orders about milliseconds in comparison with seconds for TOKAMAKs.
And I am sure that increasing the number density 1000 fold would decrease the characteristic time of instabilities development. And I do not know what confinement duration can be gotten in that case.

[TallDave]

Are you confusing confinement and stability? They are not the same thing, you know.

I don't know what part of "good curvature" isn't sinking in, but the stability of PWs is not controversial. The questions are about confinement, ion focus, etc.

Anyways, most of your questions can be answered here:

http://en.wikipedia.org/wiki/Polywell

http://www.ohiovr.com/polywell-faq/inde ... =Main_Page

Best of luck!

[Joseph Chikva]

...the stability of PWs is not controversial. The questions are about confinement, ion focus, etc.

So, would you like to say that device is so stable that plasma can be confined as long as required?
What does the question of ion focus consist of? Not that declared number density cannot be reached?

Do you think that I did not see those links earlier? As I remember you promised to give links of "high league".

Good luck you too.

[chrismb]

Have you an interest and knowledge to discuss fusion problems ..

Evidently more than you [as in, discussing real fusion problems].

... and not personal motives of people why they discuss here and not visit e.g. other web-sites? Such as music, movie, porn, etc..

Eh?!?!?

What are you getting at? Are you saying it is illegitimate for me to probe on why you have appeared on this site? The two points are distinct. I discuss fusion AND I want to know why people come here to discuss it (and many do not even discuss fusion! so I surely want to know why those have appeared!)

[Joseph Chikva]

I have appeared here because it is interesting for me.
Is not it enough? Are you moderator of this site?

[chrismb]

I did not ask you why you had appeared. I asked why you think being interested in fusion and in people's interest in fusion are mutually exclusive, as was the implication of your previous post.

[Joseph Chikva]

I did not ask you why you had appeared. I asked why you think being interested in fusion and in people's interest in fusion are mutually exclusive, as was the implication of your previous post.

I don't think that from my post follows more than I have already said. And if you grant to yourselves the right to ask why I don't have the same right to put the question too?

[chrismb]

If you asked a question of me, then I didn't spot it inbetween the bluster.

[KitemanSA]

Ions have not radial arrange velocity. But thermalized beam has a radial (thermal) energy. Cooling means the dissipation or of that or passing that to another substance.

QUASI-neutral plasma unlike to NON-neutral plasma means the total neutralizing of particles space charge. So, in QUASI-neutral plasma if you have not relativistic particles in it, should have an equal densities of positive and negative particles.

I am afraid you do not understand correctly what Polywell's developers mean.

Sorry, the language barrier is interfereing.
What does "Ions have not radial arrange velocity" mean?
Why do you equate thermal and radial energy?
If your definition of "quasi-neutral" requires the TOTAL neutralization in space, then either we are defining our spaces differently or you have a different definition than everyone here (I think).
It is true that I may not understnad what the Polywell developers mean, but I suggest that you consider the possibilty that that statement applies to you instead.

[D Tibbets]

...the stability of PWs is not controversial. The questions are about confinement, ion focus, etc.

So, would you like to say that device is so stable that plasma can be confined as long as required?
What does the question of ion focus consist of? Not that declared number density cannot be reached?

Do you think that I did not see those links earlier? As I remember you promised to give links of "high league".

Good luck you too.

Again, stability does not equal confinement efficiency. The magnetic surfaces are MHD stable. Small pockets of plasma do not form - like eddies in a water stream. But there is an unavoidable cost to only having convex surfaces. That is openings in the magnetic envalope- cusps. And, as stated these cusps is the confinement limiting feature of Polywells, opposing magnet (biconic cusp)mirror machines, Penning traps, etc.
Also these confinement times are ~ constant, or even improved as the density goes up, so long as the magnetic field strength goes up proportionately. . At some point I speculate that at high enough B strength, the relative cusp losses may approach crossfield diffusion losses (at least with recirculation) This possibility is mentioned in the EMC2 patent application as a theoretically poddible , but improbable pratical possibility. It mentions that with recirculation cusp electron losses are ~ 10-100X worse than cross field diffusion of electrons. At that probably unattainable state the electron containment may be similar to neutral plasma containment in Tokamaks, but at several orders of magnitude greater densities (because only electrons with their smaller gyroradii need be contained in this manner.. Of course, even if this was obtainable it would be useless, and probably very harmful due to thermalization effects, because there is no advantage in trying to contain the ions longer than the ~ mean time to fusion., which in a Polywell is probably on the order of 10's of milliseconds. In a Tokamak you need the longer containment because the mean ion dwell time till fusion is probably in the 100's of seconds.

Dan Tibbets

[Joseph Chikva]

What does "Ions have not radial arrange velocity" mean?.

May be not arrange but coherent? Beams have not coherent radial velocity. "Coherent" or "arrange” in English?

Why do you equate thermal and radial energy?.

Is a radial chaotic energy in the beams not thermal?

If your definition of "quasi-neutral" requires the TOTAL neutralization in space, then either we are defining our spaces differently or you have a different definition than everyone here (I think)..

In Soviet physics plasma with equal densities of ions and electrons called quasi-neutral. "quasi" because in the various fields anisotropy occurs. Returning to your definition if you will not neutralized totally space charge you will not reach declared density 10^19-10^22. Another way is to use relativistic electrons and partial compensation of space charge or in the other words - non-neutral plasma (by my definition. And not only mine) http://nonneutral.pppl.gov/

[Joseph Chikva]

Dear Dan,
I am tired. Required confinement in TOKAMAKs or in other machines depends on density and cross section of reaction. So in case of equal densities 10^19 m^-3 Polywell need a little less confinement duration at the expence of some bigger cross section.