Has Wiffleball Been Created Ever?

[Robthebob]

By the way, how's toks plasma more stable than stellarator?

Yes, my friend. Always from the beginning of toroidal fusion experiments TOKAMAKs provided better (longer) confinement vs. comparable size Stellarator. This was the reason why people in USA refused from Stellarators.

Really now? because that's not the reason why they build more toks, like I've said at least twice now, they build toks cus they're easier to design, cheaper, traditionally allow higher density and temperature. The trade off was, and they later found out, is they were less stable, that plasma current create a lot of problems, problems that stellarators dont have. They had an edge with ohmic heating, but it's trivial, because you cant ohmic heat your way to fusion temperature.

[Joseph Chikva]

By the way, how's toks plasma more stable than stellarator?

Yes, my friend. Always from the beginning of toroidal fusion experiments TOKAMAKs provided better (longer) confinement vs. comparable size Stellarator. This was the reason why people in USA refused from Stellarators.

Really now? because that's not the reason why they build more toks, like I've said at least twice now, they build toks cus they're easier to design, cheaper, traditionally allow higher density and temperature. The trade off was, and they later found out, is they were less stable, that plasma current create a lot of problems, problems that stellarators dont have. They had an edge with ohmic heating, but it's trivial, because you cant ohmic heat your way to fusion temperature.

Does not already achived minutes for TOKAMAKs vs milliseconds on what Stellarators were stuck mean that TOKs are more stable? And always showed better confinement.

[Robthebob]

man, we've been over this, confinement time does not equate to confinement quality. Even your statement about confinement time is at best meh. They've designed toks to run "steady state", because that's a problem with toks. There arent that many stellarator programs in the world, and people havent built a stellarator designed to last into the minutes, but it's not like it cant be done... it's most definitely capable. It's also not really a problem, because stellarators are steady state machines anyways, to have confinement time into the minutes isnt a difficult task (they dont have to do any type of external plasma wave drive or something like that).

Again, without understanding the motives of various decisions and the reality of the situation, facts and numbers becomes meaningless. I still dont quite understand how you dont understand that confinement time may be related to confinement quality, but the two are not the same. You can talk about Lawson criterion all you want, but that only gives a very rough understanding of the goals of plasma confinement. The Lawson criterion already assumes that instabilities do not occur; the whole thing would be meaningless without a stable plasma.

Even JET had its share of disruptions and instabilities given the fact that it can have plasma life times into the minutes.

[Robthebob]

The magnetic confinement doesn't perfectly confine electrons.

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

The energy of the fuel is way too high to be confined like the low energy electrons in a polywell. Then we go into the argument about whether the fuel can thermalize and lead to some of it having energy that can be confined in the same manner as the electrons in this trap. We've concluded that this is not a problem, because the electrons having such extreme difference in energy vs the fuel, do not interact with them. The electrons' lifetimes are also too short for them to interact with themselves, so they still wont interact with the fuel. The fuel... that's another story, I dont quite understand annealing. I would encourage you to ask the other posts who do understand annealing to explain it to you, but you probably wont do it.

[hanelyp]

Annealing in a nutshell:
Ions alternate between regions of high and low kinetic energy (low and high electric potential energy). Ion collision cross section is higher at low energy, so thermalizing at low energy with the narrower spread of energy dominates.

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

Joe, look up the Hall effect thruster. It uses a magnetic field that ions (with a high mass/charge ratio) can pass through easily, while electrons with a smaller cyclotron radius are blocked.

[Joseph Chikva]

I dont quite understand annealing. I would encourage you to ask the other posts who do understand annealing to explain it to you, but you probably wont do it.

You are late. Mr. 91143 (pardon if incorrectly writting the nick) understands. And after his explanation I come to the conclusion that "annealing" - one more Polywell's slangy word is natural exchange tangential momentums between particles.

[Joseph Chikva]

They've designed toks to run "steady state", because that's a problem with toks.

If you would make i little reading you would be surprized that it is a problem for any plasma device. As instability is natural feature of plasma like waves is natural feature of Sew. Sometimes instabilities quickly get devastating scale and sometimes those begin from light breeze and get devastating scale only in minutes. We have no any bases to speak about absolutely stable plasma devices of any type. But we can speak such as that: "the certain area of stability is found at such and such parameters" For TOKAMAKs such area is already found, for all the others - No. If anybody writes about not instabilities in TOKAMAKs it doesn't mean that they aren't present in other devices. Simply in TOKAMAKs instabilities are studied better.

[Joseph Chikva]

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

Joe, look up the Hall effect thruster. It uses a magnetic field that ions (with a high mass/charge ratio) can pass through easily, while electrons with a smaller cyclotron radius are blocked.

Polywell is NOT a typical magnetic trap (mirror machine) for electrons, it is a magnetic AMPLIFIER for electrons, the TRAP is the MaGrid CHARGE.

Do you know what is magnetic trap and what is amplifier? What is your amplifier amplifying?

Electron density.

The magnetic confinement doesn't perfectly confine electrons.

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

Now I am asking you:
Is Hall Effect Thruster an amplifier or ion accelerator? If amplifier, what does that amplify?

[Robthebob]

incorrect once again, Joe. There are still many types of instabilities that occurs with no present way of predicting them. It's already impossible to avoid all of them, and one of the better ways of dealing with instabilities is counter action if you were able to predict and catch it in time. This requires theoretical studies that are still beyond our reach.

Now, I get what you mean by all toroidal magnetic confinement machines have instabilities, but to claim that all of them, if given ignorance of what parameters, is equally flawed in instabilities is a complete lie. Stellarators by design is more stable due to the absence of the plasma current, that's a fact.

The fact that a method of bringing disruptions to a halt in ITER is by injecting noble gases into the plasma, effectively getting the plasma to comment suicide, is evident that they havent come close to hammering down what they need to do about the instability problem. Well, its not really proof, but it suggests at best a final solution to deal with the very uncommon instability given whatever safe parameters you mentioned (which they're not uncommon) or as a OH SHIT button so the plasma wont hurt the machine.

[93143]

The energy of the fuel is way too high to be confined like the low energy electrons in a polywell.

wut

Other way around, I think... The well depth is ~80% of electron energy, and that's where the ions get most of theirs - but the ion energy is low where the electron energy is high, and vice versa; that's how an electrostatic system works.

Ideally, at the wiffleball edge the electrons are high-energy and the ions are low-energy, so the magnetic confinement only has to deal with a bit of thermal spread in the annealing low-energy ion distribution, whereas the electrons hit the field at full speed.

The ash, on the other hand - substitute "alphas" for "fuel" in your statement and it's much closer to correct; the alphas are still confined but the cusps look fairly large to them even in wiffleball mode, so confinement isn't very good.

[Joseph Chikva]

incorrect once again, Joe. There are still many types of instabilities that occurs with no present way of predicting them. It's already impossible to avoid all of them, and one of the better ways of dealing with instabilities is counter action if you were able to predict and catch it in time. This requires theoretical studies that are still beyond our reach.

I do not understand what is incorrect in my words, but we can not avoid the most types of instabilities but can only slow down them.

Now, I get what you mean by all toroidal magnetic confinement machines have instabilities, but to claim that all of them, if given ignorance of what parameters, is equally flawed in instabilities is a complete lie. Stellarators by design is more stable due to the absence of the plasma current, that's a fact.

Complete lie?
You could not get what I meant. As I said not: “any toroidal device” but said: “any plasma device” suffers from instabilities. And that is complete true
That is not a fact that “Stellarators by design is more stable due to the absence of the plasma current, that's a fact” but the fact is only one that Stellarator’s design is more complex as has one more complex configuration coil but nevertheless always provided worse results for comparable sizes of machines. Results can be described by three parameters: temperature, number density and confinement time. And this fact is only the reason why people in USA refused Stellarators.
Now please give me reference where we can get to know that Stellarators are more stable. What is “stable”? Does stable plasma not provide longer confinement? And in which is longer? Don't say nonsenses.

[Robthebob]

To 93143, my bad. 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.

To Joe,

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

I said your earlier statement is incorrect, because while there are various parameters that are more stable than others, it's not possible to avoid instabilities or to effectively counteract against them when they happen. This is due to the speed of instabilities growing into a disruption, it's too quick. With our current technology, we have to be able to predict that a disruption is going to happen and fix it before it happens. There are currently disruptions that happen for no apparent reason, because we do not understand them and therefore cannot predict their occurring. There's also a similar argument with instabilities that dont grow into disruptions but they reduce performance, but I digress. Like I said, confinement time is meaningless without the ability to predict and deal with every problem that happens.

This was your original point, that because toks confinement time is very long, so the problem with control is already behind us. I'm saying confinement time and control are not directly tied to each other. I'm also saying toks do have problems with control, because of various issues with instabilities and disruptions.'

I do not agree with the strength of your statement about instabilities and any plasma devices, we dont know what new technology will bring us. What I will agree with is, toroidal magnetic confinement machines (which inherently is unstable due to some classical fluid physics, MHD, etc, whatever) are plagued by instabilities, that's true. So I went with the weaker statement, which is within the subset of your stronger statement, no harm done, we're not talking about other machines anyways.

We're looking at the statement, toroidal magnetic confinement machines suffers from instabilities, which is true. This was an attempt of counter argument against what I said earlier, stellarators are more stable than toks. I did not say stellarators did not suffer from instabilities, I said stellarators suffered from less, way less in fact, instabilities than toks. So what you're implying with your statement is that because every toroidal magnetic confinement machine suffers from instabilities, so toks has have less problems than stellarators, because this type of machine is studied more. It's non sequitur.

This assumes at least two things that arent true.
1. studies done on toks cannot be applied to stellarators, this isnt true. H-mode can be achieved in stellarators; counter measures for stopping disruptions can also be done on stellarators the same way as toks. On a hybrid machine, you can even have anything that's related to plasma current.
2. the amount of instabilities that remain that we havent figure out a way to deal with in toks are lower than the amount of instabilities in stellarators, which I dont think is a statement that's true or false. Unless you know both machines very well, there's no way to know the validity of this assumption.

You also tried to claim that problems in toks are problems in stellarators, which isnt completely false, but it's certainly not true. Toks have toks-specific instabilities due to the plasma current, (well machines with plasma current may have similar instabilities) that stellarators do not have. If the studies resulted in being able to predict and deal with an instability in toks that are also present in stellarator, then that instability is also fixed in a stellarator. If it's just a plasma current-specific problem, then the it's fixed on a hybrid machine or it has nothing to do with a stellarator in the first place. I just dont see how studying instabilities and overcoming them in a tok doesnt lead to the problem being fixed in a stellarator as well, unless the method is only usable in a tok, but then you just build a hybrid machine... Anyways....

As for your later post, well... where to begin. For one, you forgot to mention a fourth result, instability control. Temperature hasnt been a problem, because people figure out how to heat plasma other than ohmic heating. While it's still a bit harder on stellarators, it's not like toks have a huge edge; if it really is a big problem, then build a hybrid machine. Density is a bit of a problem, I do not have the answer to that. Confinement time not only doesnt matter if instabilities arent dealt with, stellarators are steady state machines, they can pretty much run indefinitely. Not that researchers care about that, because it's not a problem for stellarators, so they havent designed a stellarator to run effectively and indefinitely at the same time.

Like I've said already, fourth time now, researchers care about plasma behavior, toks already given them enough of a snapshot in time. The whole JET running into the minute is development of technology that would allow toks to run steady state, because it was actually a problem with toks. You're right about the one thing though, historically, (as in the past), toks did get more impressive numbers in all fields without as much effort. However, I'm saying, as our technology advanced, those edge became trivial. Well the only two edge was temperature and density, and temperature can be dealt with by other modes of heating.

Well... I dont know what you mean by reference, it's actually common accepted knowledge of the mainstream plasma community, from the historical perspective, decisions and policies and reasons behind those decisions and policies. Like I dont really have to cite a reference for the Earth being round... I understand this isnt good enough for you, I could ask my professors for a reference, although, I'm sure if there's any paper that talks about this, it would be like 3 or 4 decades old...

"Does stable plasma not provide longer confinement?" It may or it may not, like I said, stability isnt directly related to confinement time. A machine can run for a very short amount of time and have no problems at all, or machine can run for a long time but might be prone to have problems. It depends on the case. What you've been implying though, which is that long confinement time equates to having no problems with instabilities and disruptions, which again is non sequitur.

PS: I dont like to spell every single thing out like this, but let's just be completely clear with what we're trying to say.

[Joseph Chikva]

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too many words with lack of sense.
I understand that you believ your professors and may be they working in Stellarator program have their own opinion on stopping the program. But also consider that people making desision would be less smart. And that was team desession on base of doubtless data. And all your reasonings have no value.
"All toroidal have and others have not" thanks, funny. Earth is round. My advise to you is not to go into plasma physics. Pizza sale is a quite worthy occupation too.

[krenshala]

Yup, this last post pretty much confirms it. Joseph is nothing more than your garden variety internet troll. He isn't even entertaining any more. Can we please be rid of his pointless ranting?

[Joseph Chikva]

Yup, this last post pretty much confirms it. Joseph is nothing more than your garden variety internet troll. He isn't even entertaining any more. Can we please be rid of his pointless ranting?

And what should I answer on below "thoughtful" statements? Ok, I am answering now.

I do not agree with the strength of your statement about instabilities and any plasma devices, we dont know what new technology will bring us. What I will agree with is, toroidal magnetic confinement machines (which inherently is unstable due to some classical fluid physics, MHD, etc, whatever) are plagued by instabilities, that's true.

It does not matter to what agree Mr. robthebob as new technologies will also be based on Laws of Nature. And by those laws plasma is very agile and instabilities are the feature of plasma regardless to approach. Not kink, sausage, ELM, etc., typical for Z-machines or toroidal machines so 2-stream, Weabel and so on. There are not and may be not absolutely stable plasma devices.

Temperature hasnt been a problem, because people figure out how to heat plasma other than ohmic heating.

Really? Both RF heating and NB heating have power limitation. If you will overcome that instabilities will quickly destroy plasma. As in that case both those alternative heating ways will drive so strong currents creating so strong poloidal field, that we technically will not be able create corresponding toroidal. As for stability in TOKAMAK beta is required should be less than 0.4 (so called Troyon limit) And for reference of Mr. robthebob Ohmic heating is quite effective till temperature is low (limit up to ~1 keV)
I said you once and am saying once again: projected total heating power for ITER via three ways: Ohmic, RF and NBH has 50MW order, required internal energy for ignition has 400MJ order. Let’s admit that we have no losses during heating. So, we need not less than 8 s for ignition. In reality may be 16 and may be 24 and may be ITER will not be able to reach self-sustained mode.

Get it Mr. Krenshala if you do not like "pointless rantings".
But the man wants to become plasma physicist. He should know such a simple things in this case. But he don’t. Instead he writes here novels. "I agree - I disagree" But for agreeing or disproving and for arguing some basic knowledge is required.