Has Wiffleball Been Created Ever?

[hanelyp]

... I was under that impression because of what Tom Ligon said in that video, that electrons are pretty cold and ions are hot. We might be talking about different things. Um... isnt the drive current just how many electrons they pump into the system, not how fast they're going? Sorry, like I said, I'm really bad about annealing.

In the center of the polywell ions are high energy ("hot") while electrons are low energy ("cold"). Near the edge of the wiffleball plasma this is reversed.

Electrons need to enter the edge of the plasma at high energy, driven (in WB-6 and 7) by the potential difference between the emitter filaments and the magrid.

Annealing, as stated before, derives from the different particle energy in different places within the reactor, combined with higher scattering cross section at low energy.

To Joe,

Incorrect yet again, that's 3 times in a roll.

I'm not bothering to count, he gets it wrong so often.

[303]

question: has wiffleball been created ever?

answer : we aren't sure

end of thread

now i understand why mankind doesnt have fusion after decades of trying

[happyjack27]

... I was under that impression because of what Tom Ligon said in that video, that electrons are pretty cold and ions are hot. We might be talking about different things. Um... isnt the drive current just how many electrons they pump into the system, not how fast they're going? Sorry, like I said, I'm really bad about annealing.

In the center of the polywell ions are high energy ("hot") while electrons are low energy ("cold"). Near the edge of the wiffleball plasma this is reversed.

Electrons need to enter the edge of the plasma at high energy, driven (in WB-6 and 7) by the potential difference between the emitter filaments and the magrid.

Annealing, as stated before, derives from the different particle energy in different places within the reactor, combined with higher scattering cross section at low energy.

To Joe,

Incorrect yet again, that's 3 times in a roll.

I'm not bothering to count, he gets it wrong so often.

Annealing: in other words, the time particles spend interacting is inversely proportional to their speed I.e. temperature. Thats the justification for the theory that the cold edge will push high energy electrons back to confined trajectories.

[happyjack27]

...also y solids are solids.

[happyjack27]

Oops... by electrons I mean ions. : p There goes all my efforts to sound intelligent...

[Joseph Chikva]

To Joe,

Incorrect yet again, that's 3 times in a roll.

I'm not bothering to count, he gets it wrong so often.

For example when I did not agree with you about uniform current distribution in TOKAMAKs? Or when?
How personally you can find where I or anybody else get wrong if when you should say "current" you are saying "uniform current distribution"? Why "uniform current distribution"? Sounds more "scientifically"?

[Robthebob]

Oh my bad, I understood the varying energy levels part, but that's about as much as I know. I didnt clarify what I was talking about; but indeed in my earlier post, I mean to say that at the core of the machine, the fuel has too high energy to be confined in the wiffleball. In fact, Dr. N talked about how they escape very quickly compared to the confinement time of the electron. (also all that jazz about ions and electrons having very different energies so they never interact with each other, so thermalization doesnt happen.)

I'm guessing electrons lose energy going from the edge to the core to overcome the negative charges of other electrons? I have a question here, if you inject fuel into the system, wouldnt electrons become more energetic at the core due to the positive charges of the fuel making it easier for electrons in general to get to the core?

[Robthebob]

My advise to you is not to go into plasma physics. Pizza sale is a quite worthy occupation too.

Man, arent you a meanie. I want you to remember this is the day that you made the polywell forums into a place to throw meaningless insults at other posters instead of discussing scientific matters like adults. I'm not saying other posters havent been throwing insults at you, but is this really what you resort to?

Answer my points or leave the civil discussions to reasonable people.

Nevertheless, I will most definitely make an effort to deliver a copy of your book to you once I'm done writing it.

[Joseph Chikva]

I want you to remember this is the day that you made the polywell forums into a place to throw meaningless insults at other posters instead of discussing scientific matters like adults

Scientific matters like adults? Scientific matter here is short: Fact that can not be disproved by your long text is only one: TOKAMAK provides longer than Stellarator confinement at the same number density. And only stabler plasma allows longer confinement. All other words are irrelevant fiction.
Then you tried to say: toroidal devices have instabilities and not toroidal have not. That is absolutely wrong statement disproved by six-ten years' fusion researches. Etc., etc., etc.
Also for your reference spheric is special case of toroidal.
And the reference #2 Polywell is not the first device with convex field. Nevertheless, there was not ANY device in fusion research history without instabilities. And this is definitely imposible due to properties of plasma.

And what is insult? Kind advise not to go in business in which you have nothing to do? In business in which you have not any chance to reach even small success. I said several posts ago that by some reasons I can not become even moderate runner. And will not consider as insult if someone would advise not to try to do it seeing my attempts.

[KitemanSA]

Oh my bad, I understood the varying energy levels part, but that's about as much as I know. I didnt clarify what I was talking about; but indeed in my earlier post, I mean to say that at the core of the machine, the fuel has too high energy to be confined in the wiffleball. In fact, Dr. N talked about how they escape very quickly compared to the confinement time of the electron. (also all that jazz about ions and electrons having very different energies so they never interact with each other, so thermalization doesnt happen.)

I think you may be remembering the discussion on PRODUCT lifetime, not FUEL lifetime.

[D Tibbets]

The magnetic confinement doesn't perfectly confine electrons.

Dubious statement. As magnetic confinement confines all charged particles. Recall e.g. Penning trap.

A Penning trap confines a charged particle at cryogenic temperatures well due to the key point which you neglected to mention - cryogenic temperatures.. You can add to that low densities. Magnetic confinement is based on a particles charge, its mass, and its temperature. Add to that ExB drift which is a collisional process. Theoretically, you might confine a single hydrogen ion forever. But once a second particle is added, collisions occur and this causes changes, and this causes ExB drift. The gyro radius at very cold temperatures is tiny, so the random walk process leading to ExB drift is incrementally small and rare due to the very low density. Increase the density to useful fusion densities and the KE to 10,000 eV or more, and the story changes accordingly.
This is one reason Tokamaks need to be large. The ExB drift limits the minimal size that will accommodate a given confinement time at a certain energy and density.
In this regard the Polywell of course follows the same rules, at least for the electrons. As I mentioned mass is also important, and as the electron has ~ 1/4000th the mass (1/60th the momentum) the random walk process is in smaller increments per collision. That is why the Polywell can be smaller. The increased density would hurt this, but the increased fusion rate associated with the increased density also needs to be considered. Much less electron confinement times are thus needed, and the B fields in a small machine are adequate in regards to ExB drift. In fact the confinement is limited by cusp leakage, not ExB drift.

This is the best confinement possible with magnetic fields. If Tokamaks were limited by this loss mechanism alone, they would be great. It is the other instabilities that cause the nightmares for Tokamaks.

As for many instabilities/ pinch effects. The convex towards the center B fields are stable . From two texts, the easiest explanation, is that concave B fields towards the walls ( the opposite perspective used in the Polywell) are stable, and can be explained simply by a potential well picture. Any charged particle that climbs (through a collision or other energy transfer mechanism) up the wall of a concave B fleld line (remember this is relative to the wall) climes a potential well . Thus it tends to fall back to the bottom of the well- to a more stable state. In a convex B field line relative to the wall, the same collision would be dropping down a potential well (gaining energy). The particle easily progresses further, and instabilities become progressively faster/ easier. Thus things like pinches are inevitable. This is fundamentally different in the Polywell configuration where the fields are convex towards the center/ concave twords the edge. This was a problem with the solenoid type mirror machines. There was concave fields (towards the center) between the magnets, and various efforts to control this failed. A Polywell, like the biconic cusp mirror machines avoid this. But the equatorial cusp losses were excessive , until modified by the Polywell geometry. This is still insufficient for neutral plasma containment. Since the early work though, Bussard changed this by using a non neutral plasma. Now the "Plasma" is separated into two componets. Magnetically contained electrons, and electrostatically contained ions. This allowed the electron magnetic cusp confinement to be long enough (with recirculation, and ExB drift confinemnt issues are not an issue- much less than cusp losses) for the slower moving ions to fuse before escape. The break is not only between the confinement method, but its effect when combined with a non neutral plasma. In a neutral plasma the ions would have to leave as fast as the electrons. But by injecting excess electrons the ions can travel proportionately further, and be more likely to fuse before escape. The whole key is the cost of maintaining the excess electron population at useful densities. Issues of annealing and thermalization are important mostly for the final size, or ability to burn advanced aneutronic fuels. But for D-T or D-D burning, the ancillary issues only concern the final size. As Nebel has said, the Polywell would be perfectly happy burning D-D fuel, even if it is thermalized, and has no cental confluence. It would just need to be bigger , and of course operate at smaller, but still positive Q's.

Dan Tibbets

[chrismb]

Man, arent you a meanie. I want you to remember this is the day that you made the polywell forums into a place to throw meaningless insults at other posters instead of discussing scientific matters like adults.

This day?

Lest the forum forgets, this clown has long since had several such days. Not forgetting this most adult of exchanges, last year:

So fu..k his foolish mot..r together with moms of all his friends.
Hope that is well understood English.

[Robthebob]

Scientific matters like adults? Scientific matter here is short: Fact that can not be disproved by your long text is only one: TOKAMAK provides longer than Stellarator confinement at the same number density. And only stabler plasma allows longer confinement. All other words are irrelevant fiction.
Then you tried to say: toroidal devices have instabilities and not toroidal have not. That is absolutely wrong statement disproved by six-ten years' fusion researches. Etc., etc., etc.
Also for your reference spheric is special case of toroidal.
And the reference #2 Polywell is not the first device with convex field. Nevertheless, there was not ANY device in fusion research history without instabilities. And this is definitely imposible due to properties of plasma.

And what is insult? Kind advise not to go in business in which you have nothing to do? In business in which you have not any chance to reach even small success. I said several posts ago that by some reasons I can not become even moderate runner. And will not consider as insult if someone would advise not to try to do it seeing my attempts.

Hmmm, well, let me get you on a little secret, and it's going to sound corny. My passion for physics, fusion energy, plasma physics will never be put out by anything, that includes your childish insults. I'm surprised, that a individual of your caliber will resort to this, if you are what you said you are. If anything I've said is fact, I'll never stop being a physicist, that's a fact!

I'm going to condense my points down, so you can have an easier time reading and hopefully respond to my points.

JET (and some other toks) achieved such high duration due to microwave driven waves, which generates plasma current, this doesnt have much to do with stability of the plasma. This can also be used in a stellarator, therefore it's most likely possible for a stellarator to achieve the same duration, possibly even without that technique.

Let me explain once more,

1. Temperature: not a problem because there are many other ways of plasma heating, all of those can be used across the two machines, including ohmic heating in hybrid machines or microwave driven plasma current.
2. Duration: not a problem, we just talked about this
3. Studies and machine preference: toks are cheaper, easier to build and in the past achieved higher temperature and density with less effort, so people use it to study fusion plasma. Due to various advancements in our general fusion plasma studies, many of the edges toks have are no longer very relevant.
4. Studies of instabilities and counter measures: different toroidal magnetic confinement machines do not possess completely different sets of instabilities, many of them are shared; studying an instability on one machine can potentially mean studying the instability in general, across all those machines.

(give me examples of types of instabilities on both stellarators and toks that researchers can deal on toks but not on a stellarator. Do stellarators have that many machine specific instabilities that can only be studied and dealt with in a stellarator? My professors are field experts in stellarators, and they dont seem to think so.)

Oh my god, I realized now, you actually do think longer duration means better confinement, it's not true like I've been trying to explain.

Lastly, I never said non-toroidal magnetic machines dont have instabilities. I said, your statement, "We have no any bases to speak about absolutely stable plasma devices of any type." is too strong, so I'm changing it to a weaker but most definitely true statement. That toroidal magnetically confined plasma can't be absolutely stable, this is true due to the inherent design of all donut shaped fusion machines. Dont put words in my mouth. I said this weaker statement is true, I didnt say the stronger statement is false.

In hindsight, what you said is probably true due to the word "absolutely", excuse me I missed it. Without that word, then it'll probably be false, there will probably (or possibly already exist) machines that provide bottom of hill stability, instead of top of the hill or saddle stability.

[Joseph Chikva]

As for many instabilities/ pinch effects. The convex towards the center B fields are stable . From two texts, the easiest explanation, is that concave B fields towards the walls ( the opposite perspective used in the Polywell) are stable, and can be explained simply by a potential well picture. Any charged particle that climbs (through a collision or other energy transfer mechanism) up the wall of a concave B fleld line (remember this is relative to the wall) climes a potential well . Thus it tends to fall back to the bottom of the well- to a more stable state. In a convex B field line relative to the wall, the same collision would be dropping down a potential well (gaining energy). The particle easily progresses further, and instabilities become progressively faster/ easier. Thus things like pinches are inevitable. This is fundamentally different in the Polywell configuration where the fields are convex towards the center/ concave twords the edge. This was a problem with the solenoid type mirror machines. There was concave fields (towards the center) between the magnets, and various efforts to control this failed. A Polywell, like the biconic cusp mirror machines avoid this. But the equatorial cusp losses were excessive , until modified by the Polywell geometry.

Magnetohydrodynamic Instabilities in a Simple Gasdynamic Mirror Propulsion System

Raising the mirror ratio to high values to increase plasma confinement is not always effective, however, since high mirror ratios can also induce the occmnce of certain rather severe plasma instabilities in the device called magnetohydrodynamic or “MHD” instabilities.
These instabilities are a result of convex curvature in the magnetic field lines with respect to the machine’s centerline.

Now you say that this is problem only for solenoidal mag trap?
No, for all. I will try to find other links. But simply when magnetic traps were investigated intensively we had no internet.
This is not like pinch phenomenon. That is only your feelings. But "more stability" of plasma confined by convex B field goes from so called "minimum B principle" reasonings. I said here several times what does that principle means. And also mentioned the fact that despite convexity mirror machines also suffered from instabilities. So, those reasoning were not proved experimentally.
By the way Z-pinch is the first fusion experiment in which instabilities were investigated. Historically there were: kink instability and sausage.

[Joseph Chikva]

1. Temperature: not a problem because there are many other ways of plasma heating, all of those can be used across the two machines, including ohmic heating in hybrid machines or microwave driven plasma current.

Yes, temperature is not problem as we can confine given hot plasma. But we have not an effective enough method to make plasma hot.
Microwave or beam driven plasma current has restrictions. Poloidal field increases thus increasing number density and so plasma pressure. And for keeping beta value at acceptable level (about 0.1) you should correspondently increase the toroidal field. But we have approached to technical limit for solenoidal field - about 10T. As we can not build large enough solenoids (bent into the donate) running long enough time with stronger field. And this is a limit for TOKAMAK heating.