Has Wiffleball Been Created Ever?

[Joseph Chikva]

Plasma confinement time means little without context, such as density.

Number density in TOKAMAK has 10^20 order. That is so well known that in most cases there is not necessity to repeat.

[KitemanSA]

Despite to instabilities lifetime of plasma in TOKAMAKs reaches minutes. Please note me the lifetime of olasma in "more stable" Polywell.

100% of the drive voltage time. Since the drive voltage time has been pulsed at ~ a millisecond...

[Joseph Chikva]

Despite to instabilities lifetime of plasma in TOKAMAKs reaches minutes. Please note me the lifetime of olasma in "more stable" Polywell.

100% of the drive voltage time. Since the drive voltage time has been pulsed at ~ a millisecond...

And if you would have not pulsed drive voltage but constant high voltage source lasting several seconds or longer? Can you confine plasma in "more stable" Polywell such a long time in that case?
I know that there is not such nessesity but nevertheless please answer if Polywell is really more stable as here mentioned.

[KitemanSA]

Those doing the research, and those experts reviewing the research, seem to think so. Thus, I will await REAL data and forgo jumping to any "conclusions".

"Conclusion Jumping" does seem to be a popular sport around here. If it were an Olympic event, we may have some gold medalists in our ranks!

[Betruger]

There Can Be Only One.

[Joseph Chikva]

and those experts reviewing the research, seem to think so.

reviewing what? We have nothing for reviewing. I speak with people here who have the wrong views in my opinion. And do not discuss nonexistent researches. Nothing more Valencia paper and one paper of Nebel on electron-electron 2-stream.

By the way, how about your statements about impracticability of TOKAMAK? One more Olympic sport?

[Betruger]

and those experts reviewing the research, seem to think so.

reviewing what? We have nothing for reviewing.

We's not the experts in question.

[kcdodd]

Are you saying ballooning mode isn't a cause of elms? Otherwise I don't know how I could be clearer.

List of lasma instabilities types:
http://webcache.googleusercontent.com/s ... clnk&gl=ge

Bennett pinch instability (also called the z-pinch instability )
Beam acoustic instability
Bump-in-tail instability
Buneman instability,[2]
Cherenkov instability,[3]
Chute instability
Coalescence instability,[4]
Collapse instability
Counter-streaming instability
Cyclotron instabilities, including:
Alfven cyclotron instability
Electron cyclotron instability
Electrostatic ion cyclotron Instability
Ion cyclotron instability
Magnetoacoustic cyclotron instability
Proton cyclotron instability
Nonresonant Beam-Type cyclotron instability
Relativistic ion cyclotron instability
Whistler cyclotron instability
Diocotron instability,[5] (similar to the Kelvin-Helmholtz fluid instability).
Disruptive instability (in tokamaks)
Double emission instability
Drift wave instability
Edge-localized modes [6]
Electrothermal instability
Farley-Buneman instability,[7]
Fan instability
Filamentation instability
Firehose instability (also called Hose instability)
Flute instability
Free electron maser instability
Gyrotron instability
Helical instability (helix instability)
Helical kink instability
Hose instability (also called Firehose instability)
Interchange instability
Ion beam instability
Kink instability
Lower hybrid (drift) instability (in the Critical ionization velocity mechanism)
Magnetic drift instability
Magnetothermal instability (Laser-plasmas) [8]
Modulation instability
Non-Abelian instability (see also Chromo-Weibel instability)
Chromo–Weibel instability
Non-linear coalescence instability
Oscillating two stream instability, see two stream instability
Pair instability
Parker instability (magnetic buoyancy instability)
Peratt instability (stacked toroids)
Pinch instability
Sausage instability
Slow Drift Instability
Tearing mode instability
Two-stream instability
Weak beam instability
Weibel instability
z-pinch instability, also called Bennett pinch instability

Resistive Ballooning Mode , similar to ideal ballooning, but with finite resistivity taken into consideration, provides another example of a resistive instability.

An edge-localized mode ("ELM") is a disruptive instability occurring in the edge region of a tokamak plasma due to the quasi-periodic relaxation of a transport barrier previously formed during an L --> H transition. This phenomenon was first observed in the ASDEX tokamak in 1981

You didn't answer the question, which is really yes or no. I know what instabilities are and what elms are. You don't need to quote definitions. The question was, are you saying ballooning mode is not one cause for elms. yes or no. It's very simple.

And again, you are confusing the difference between plasma lifetime and confinement time. I have flourescent bulbs here in my garage that have been going for a few hours now. And I am sure there are some neon signs that have been on for years at a time. All plasma discharges with really crappy confinement times. So unless you are saying we might be able to use tokamaks as a good new light-source it really makes no difference how long they can run them. That's merely a practical concern. What matters for fusion break-even is the energy confinement time. Which is right now, at the best of my knowledge, something like 1 second. Also important is the reaction rate, which is why ICF can get away with such crappy confinement times. Incidentally, they also have much shorter plasma lifetimes then all other schemes. Again, that is really kind of irrelevant to the break-even aspect.

I am confusing nothing. But ok, let's say 1 sec confinement time. Do you not agree that is quite long time period for unstable plasma?

Quite long? I don't know, by what basis? It is insufficient for fusion break-even in a tokamak. If that's what you mean, then no, it's not quite long enough. It is better then other machines. If that's what you mean, then it is long, I suppose. Can it be done better, smaller, cheaper? Who knows. If that's what you mean, thats the 50 trillion dollar question.

[Joseph Chikva]

You didn't answer the question, which is really yes or no. I know what instabilities are and what elms are. You don't need to quote definitions. The question was, are you saying ballooning mode is not one cause for elms. yes or no. It's very simple.

I have answered on your question with the help of quotes. As ballooning mode is feature of any toroidal machine while elm occurs only at H-mode. The first is resistive instability, while the second has another nature.
So, simply no.

Quite long? I don't know, by what basis? It is insufficient for fusion break-even in a tokamak. If that's what you mean, then no, it's not quite long enough. It is better then other machines. If that's what you mean, then it is long, I suppose. Can it be done better, smaller, cheaper? Who knows. If that's what you mean, thats the 50 trillion dollar question.

Quite long in case of enough plasma reactivity that is the function of temperature. In case of achievement of e.g. 15 keV of temperature breakeven may be achieved with 1 sec confinement.

[kcdodd]

You didn't answer the question, which is really yes or no. I know what instabilities are and what elms are. You don't need to quote definitions. The question was, are you saying ballooning mode is not one cause for elms. yes or no. It's very simple.

I have answered on your question with the help of quotes. As ballooning mode is feature of any toroidal machine while elm occurs only at H-mode. The first is resistive instability, while the second has another nature.
So, simply no.

You're saying ballooning mode has nothing to do with elm?

Quite long? I don't know, by what basis? It is insufficient for fusion break-even in a tokamak. If that's what you mean, then no, it's not quite long enough. It is better then other machines. If that's what you mean, then it is long, I suppose. Can it be done better, smaller, cheaper? Who knows. If that's what you mean, thats the 50 trillion dollar question.

Quite long in case of enough plasma reactivity that is the function of temperature. In case of achievement of e.g. 15 keV of temperature breakeven may be achieved with 1 sec confinement.

Of course a 15keV DT plasma with 1sec confinement can be break-even. My quick calculation for DT at 15keV and 10^20m^-3 with a 1s energy confinement time gives about Q=2.6. But of course that's not the parameters under which 1s was achieved, and of course you cannot just arbitrarily change the plasma parameters in a tokamak, and especially not expect to get the same confinement time. And a plasma with 1ms confinement time at 15keV can be breakeven too, if you make the density 10^23 m^-3. So, what exactly is your point.

[Joseph Chikva]

You're saying ballooning mode has nothing to do with elm?

Why nothing? Both they are instabilities types. As well as many other types too.

Of course a 15keV DT plasma with 1sec confinement can be break-even. My quick calculation for DT at 15keV and 10^20m^-3 with a 1s energy confinement time gives about Q=2.6. But of course that's not the parameters under which 1s was achieved, and of course you cannot just arbitrarily change the plasma parameters in a tokamak, and especially not expect to get the same confinement time. And a plasma with 1ms confinement time at 15keV can be breakeven too, if you make the density 10^23 m^-3. So, what exactly is your point.

I do not know how legit is your quick calculation. Take a look here: http://iter.rma.ac.be/Stufftodownload/T ... iteria.pdf THERMONUCLEAR BURN CRITERIA But despite to the fact that temperature has a little influence on stability in TOKAMAK, namely heating is a problem. As for ITER's parameters: 840m3 volume, 10^20m^-3 number density, 15keV temperature and total heating power via three heating ways about 50MW, we need about 8sec even if plasma during heating we have zero losses. Technically there is not a big problem to build more powerful heaters. But: Ohmic heating is ineffective at high temperatures and too strong RF and neutral will cause destructive scale of instabilities which now are quite controllable.
10^23 number density is technically impossible as that needs about 150T of torodal field. But I think that in that case even millisecond confinement would enough and even less. The main goal is to reach ignition of self-sustained mode when plasma temperature will be kept by alpha-heating.

[KitemanSA]

and those experts reviewing the research, seem to think so.

reviewing what? We have nothing for reviewing.

True, but they did, and oh by the way, you are an insignificant factor in their eyes.

I speak with people here who have the wrong views in my opinion. And do not discuss nonexistent researches.

Ahah! Now it comes out. You are a solipsist, right? You don't think anything exists except you and what you have seen. Most folks outgrow that at about age three.

Nothing more Valencia paper and one paper of Nebel on electron-electron 2-stream.

By the way, how about your statements about impracticability of TOKAMAK? One more Olympic sport?

Have you seen the projected cost for "DEMO"? Hideously, rediculously, absurdly, MONSTEROUSLY high. THEIR numbers condemn themselves. No "conclusion" needed on my part other than they aren't lieing to us.

[Joseph Chikva]

and those experts reviewing the research, seem to think so.

reviewing what? We have nothing for reviewing.

True, but they did, and oh by the way, you are an insignificant factor in their eyes.

I speak with people here who have the wrong views in my opinion. And do not discuss nonexistent researches.

Ahah! Now it comes out. You are a solipsist, right? You don't think anything exists except you and what you have seen. Most folks outgrow that at about age three.

Nothing more Valencia paper and one paper of Nebel on electron-electron 2-stream.

By the way, how about your statements about impracticability of TOKAMAK? One more Olympic sport?

Have you seen the projected cost for "DEMO"? Hideously, rediculously, absurdly, MONSTEROUSLY high. THEIR numbers condemn themselves. No "conclusion" needed on my part other than they aren't lieing to us.

They (Polywell developers) are saying that they did something. And "saying" and "doing" a little differ each other.

I do not know what the word "solipsist" means, but wrong statement that e.g. ions in Polywell move strictly radially (IIRC Mr. Kreshala), that themal distribution at the edge is narrower than in center (you, my friend), polywell is not beam machine (Mr. Ladajo) and so on.
Only after very long arguing I found out that Dr. Nebel said that without wiffleball Polywell will not work. Let's show wiffleball and then I will change my opinion. You are right, my opinion is insignificant. But nothing depends on your support team too if concept is not viable.

I am not aware in projected cost of DEMO program. But recall that it is cost of program and not hardware. And high cost of program does not mean automatically that other "cheap" approaches are viable. I siad you and others that first TOKAMAKs also were rather cheap machines.

[kcdodd]

The problem with tokamak's and cost is that the dimension of the machine has to be several times bigger than the minor radius. Essentially, the shortest path to the outside is the minor radius, and so the circumferential distance really adds nothing, except of course for making the tokamak functionally possible. That is, if one could hypothetically make a machine of dimensions only of the minor radius it would use less actual material by about pi*r_major/r_minor. For iter with aspect ratio ~3, it would be nearly 10x reduction in material cost. In other words, to build a tokamak, you have to make 10 of everything you need. And of course that is one goal of spherical tokamaks.

[Joseph Chikva]

The problem with tokamak's and cost is that the dimension of the machine has to be several times bigger than the minor radius. Essentially, the shortest path to the outside is the minor radius, and so the circumferential distance really adds nothing, except of course for making the tokamak functionally possible. That is, if one could hypothetically make a machine of dimensions only of the minor radius it would use less actual material by about pi*r_major/r_minor. For iter with aspect ratio ~3, it would be nearly 10x reduction in material cost. In other words, to build a tokamak, you have to make 10 of everything you need. And of course that is one goal of spherical tokamaks.

The goal of spherical TOKAMAKs is to run at lower aspect ration (ratio between major and minor radii). But that is not for purpose of "reduction in material cost". But simply TOKAK theory states that allowable beta for lower ratio is higher.
Geometrically when aspect ratio goes to 1, torus converts into sphere.
Recall that Troyon limits for TOKAMAK is beta<0.4 But in reality in TOKAMAKs beta has 0.1 order.
Lower aspect ratio causes technical problems with central solenoid installation.
And again cost of program is not equal to cost of hardware.
You can e.g. spend millions for new design vacuum cleaner development but then to sell each cleaner at 100$. And that would be economical in case of mass production.
Also cost of superconductors which at this moment is extremely high by the reason of absence of qualified consuming in enough quantities. Once upon a time I recalled to Kiteman aluminum's example the cost of which was high initially but then became acceptable for market after appearing of qualified users and mass production.