reddit: We are nuclear fusion researchers, ask us anything

[KitemanSA]

1. Scaled Factors
2. Power scaling = B^4*R^3 at constant beta.
3. Loss scaling ~B^.25*R^2 (all else being equal, but most experience is that all else does NOT remain equal). Dr. B. seems to have expected this to hold pretty well. This is the purpose for MOST of the WB8 research.
4. Gain = Power - Loss = ~B^4*R with an offset

[krenshala]

Joseph, if you believe that the power doesn't scale at B^4 R^3 for fusion devices, what does your knowledge state power scales at?

[Joseph Chikva]

Joseph, if you believe that the power doesn't scale at B^4 R^3 for fusion devices, what does your knowledge state power scales at?

n1 *n2<vσ> where due to properties of plasma ni is not proportional to B^2

For your reference in any magnetic confinement plasma device geometric dimension of plasma and therefore density is defined as parity of plasma (gas) pressure and magnetic pressure and not equal to each other due to turbulence of plasma. And that ratio (beta) depends on that how vigorous that turbulence is. Turbulence and instabilities are observed in any plasma devices as plasma by its nature is very agile. And, so, beta never can be equal to 1.

It is funny to hear (read) that 5 generations of devices were unsuccessful but then beginning from 6-th generation plasma in that type of device is free from any turbulences and instabilities.

Best regards,

[ladajo]

It is funny to hear (read) that 5 generations of devices were unsuccessful but then beginning from 6-th generation plasma in that type of device is free from any turbulences and instabilities.

It is more funny to hear from you why you think the earlier machines were, "unsuccessful".

Please, do not let reality intervene with your uninformed opinions.

Maybe you should study up a little, and try to understand the Polwell program history and efforts before making complete boob statements like the above.

Polywell is NOT a Tokamak. It is not even close. Completely different idea, that shares only one common point with the fact that it is a plasma machine. But it is like comparing a gas turbine engine to a piston engine. Two different engineering animals in the ICE spectrum.
You really have no idea how Polywell is envisioned to work.
You also, remain apparently ingorant to the point that pretty much all of us here do not know if it will work. That is why we are here discussing it.
In fact, most of us give Polywell less than 50% odds of success. Some, even lower, but not for any of the reasons you are hung up on.

Why don't you read some of the actual peer reviewed critique papers on Polywell, and see where none of those Real Life Plasma Physicists agree with your issues. They see potentially other problems. Which, interstingyl enough, are countered by other Real Life Plasma & Fusion Physicists in Peer Reviewed work.

It would really be a shame if you actually cited something you researched.

[krenshala]

Joseph, if you believe that the power doesn't scale at B^4 R^3 for fusion devices, what does your knowledge state power scales at?

n1 *n2<vσ> where due to properties of plasma ni is not proportional to B^2

And what does n1 and n2 represent? Definition of terms, please.

For your reference in any magnetic confinement plasma device ...

Polywell is not a magnetic plasma confinement device, it is an electro static plasma confinement device. It is, however, a magnetic electron confinement device. The two are not necessarily synonymous.

... geometric dimension of plasma and therefore density is defined as parity of plasma (gas) pressure and magnetic pressure and not equal to each other due to turbulence of plasma.

But, won't the two pressures find a balance point at which the plasma pressure equals the magnetic pressure? It has always been my understanding that this happens in ANY plasma device.

And that ratio (beta) depends on that how vigorous that turbulence is. Turbulence and instabilities are observed in any plasma devices as plasma by its nature is very agile. And, so, beta never can be equal to 1.

Cannot beta become greater than one (beta > 1), and thus containment of the plasma fail? If not, why not?

It is funny to hear (read) that 5 generations of devices were unsuccessful but then beginning from 6-th generation plasma in that type of device is free from any turbulences and instabilities.

For what reason to you believe the "success" of WB6 was due to a lack of turbulence/instability in the contained plasma? According to the information released by Dr. Bussard about WB6 (have you read that information?), instability of the plasma one way or the other was not the reason the WB6 "worked".

[Joseph Chikva]

Joseph, if you believe that the power doesn't scale at B^4 R^3 for fusion devices, what does your knowledge state power scales at?

n1 *n2<vσ> where due to properties of plasma ni is not proportional to B^2

And what does n1 and n2 represent? Definition of terms, please.

For your reference in any magnetic confinement plasma device ...

Polywell is not a magnetic plasma confinement device, it is an electro static plasma confinement device. It is, however, a magnetic electron confinement device. The two are not necessarily synonymous.

... geometric dimension of plasma and therefore density is defined as parity of plasma (gas) pressure and magnetic pressure and not equal to each other due to turbulence of plasma.

But, won't the two pressures find a balance point at which the plasma pressure equals the magnetic pressure? It has always been my understanding that this happens in ANY plasma device.

And that ratio (beta) depends on that how vigorous that turbulence is. Turbulence and instabilities are observed in any plasma devices as plasma by its nature is very agile. And, so, beta never can be equal to 1.

Cannot beta become greater than one (beta > 1), and thus containment of the plasma fail? If not, why not?

It is funny to hear (read) that 5 generations of devices were unsuccessful but then beginning from 6-th generation plasma in that type of device is free from any turbulences and instabilities.

For what reason to you believe the "success" of WB6 was due to a lack of turbulence/instability in the contained plasma? According to the information released by Dr. Bussard about WB6 (have you read that information?), instability of the plasma one way or the other was not the reason the WB6 "worked".

n1 and n2 correspondently number densities of two spices of reacting components. If you talk about beta, so, you talk about magnetic confinement.
And I am tired to explain things that should be well known when people start discussing fusion.
Kiteman may be right that I am an idiot discussing at this level

[Joseph Chikva]

It is funny to hear (read) that 5 generations of devices were unsuccessful but then beginning from 6-th generation plasma in that type of device is free from any turbulences and instabilities.

It is more funny to hear from you why you think the earlier machines were, "unsuccessful".

I did nat say that before Kiteman did not said that "WB6 is the first successful". And too bad that I do not know Polywell's history.
From this I came to the conclusion that WB1...WB5 were unsuccessful. Simple logic.
Best regards,

[krenshala]

n1 *n2<vσ> where due to properties of plasma ni is not proportional to B^2

And what does n1 and n2 represent? Definition of terms, please.

For your reference in any magnetic confinement plasma device ...

Polywell is not a magnetic plasma confinement device, it is an electro static plasma confinement device. It is, however, a magnetic electron confinement device. The two are not necessarily synonymous.

... geometric dimension of plasma and therefore density is defined as parity of plasma (gas) pressure and magnetic pressure and not equal to each other due to turbulence of plasma.

But, won't the two pressures find a balance point at which the plasma pressure equals the magnetic pressure? It has always been my understanding that this happens in ANY plasma device.

And that ratio (beta) depends on that how vigorous that turbulence is. Turbulence and instabilities are observed in any plasma devices as plasma by its nature is very agile. And, so, beta never can be equal to 1.

Cannot beta become greater than one (beta > 1), and thus containment of the plasma fail? If not, why not?

It is funny to hear (read) that 5 generations of devices were unsuccessful but then beginning from 6-th generation plasma in that type of device is free from any turbulences and instabilities.

For what reason to you believe the "success" of WB6 was due to a lack of turbulence/instability in the contained plasma? According to the information released by Dr. Bussard about WB6 (have you read that information?), instability of the plasma one way or the other was not the reason the WB6 "worked".

n1 and n2 correspondently number densities of two spices of reacting components. If you talk about beta, so, you talk about magnetic confinement.
And I am tired to explain things that should be well known when people start discussing fusion.
Kiteman may be right that I am an idiot discussing at this level

I notice you conveniently skipped over the rest of my questions. Is this because you don't have answers, or because you don't like the answers you have?

[Joseph Chikva]

I notice you conveniently skipped over the rest of my questions. Is this because you don't have answers, or because you don't like the answers you have?

Do you want that I'd answer on e.g. this your question:

Cannot beta become greater than one (beta > 1), and thus containment of the plasma fail? If not, why not?

Ok, beta can not be >1.
One more question?
This?

For what reason to you believe the "success" of WB6 was due to a lack of turbulence/instability in the contained plasma? According to the information released by Dr. Bussard about WB6 (have you read that information?), instability of the plasma one way or the other was not the reason the WB6 "worked".

I belive that WB6 worked producing 1.5mW of fusion power. But that does not mean that WB6 worked with beta=1.
Existense of turbulence mean that beta<1. That's all my friend.
"We done experiment and proved that beta=1" is the statement like "we done experiment and found that neitrino moves faster than light". Then appeared that one plug was not connected correctly.

[ladajo]

It is funny to hear (read) that 5 generations of devices were unsuccessful but then beginning from 6-th generation plasma in that type of device is free from any turbulences and instabilities.

It is more funny to hear from you why you think the earlier machines were, "unsuccessful".

I did nat say that before Kiteman did not said that "WB6 is the first successful". And too bad that I do not know Polywell's history.
From this I came to the conclusion that WB1...WB5 were unsuccessful. Simple logic.
Best regards,

Once again you prove that you refuse or cannot be bothered to read pertinant references and citations to the topic at hand. How can you expect anyone to take anything you say seriously?

If you wish, please, at your leisure, visit the EMC2Fusion.org website. Scroll to the bottom, and look for the link for "history". While you are at it, you could also hit the link for the 2006 IAC paper. And, if you are really feeling adventurous, you can click and read the "findings" link.
If you ever find time to read them let us know. Until then, anything you say will probably make no sense.

I would provide you the actual links, but given I have done it a number of times, I can no longer be bothered.

Simple choice. Continued uninformed arguments on your part making you look silly, ...or not.

Say slowly..."Magnetic Inertial Electrostatic Confinement"...

[D Tibbets]

Applying obtainable Beta in Tokamaks to Polywells is improper. The torus in Tokamaks are not symmetrical (inside edge compared to outside edge) and this limits the Beta that can be reached before confinement issues cannot be controlled. The issues are different in a Polywell.

http://www.askmar.com/Fusion_files/Inhe ... ystems.pdf

In fact, the magnetic beta attainable for ion confinement
in MM (edit=Tokamak) systems is generally much less than unity;
typically, ~ 0.15 is hoped to be achieved in large tokamak
MM systems. In contrast, the confinement of electrons, not neutral plasma, at modest density as characteristic at the EXL system edge is readily able to
reach unity beta; thus, Beta =~ 1 is typical

.

Also, Beta is not the issue here. B scaling is. Remember that the baseline power output is different between tokamaks and Polywells. But as you change the volume and the B field strength the same B^4 r^3 scaling from that baseline applies. When you introduce Beta considerations you are talking about practical considerations, not the theoretical scaling laws.

This link , discusses the scaling issue.The response by A. Carlson (a plasma physicist) is pertinent. Unfortunately the embedded link is not working, so you will have to accept my impression from it.

viewtopic.php?t=1062&highlight=ion+temperatureText

Dan Tibbets

[ladajo]

Try this:

4th Power Scaling

[D Tibbets]

Joseph Chikva, you need to be careful. The context of the thread is important. When Nebel said smaller machines (than the baseline WB6 diameter of 30 cm) was worthless to them, it was in response to my question of the possibility of using smaller machines to decrease cost and increase testing iterations. Nebels response was that going to smaller sizes than current sizes would result in less reliable data and increased technical difficulties. Two obvious reasons for this practical constraint is first, the instrumentation. WB6 was barely able to give a signal greater than the noise baseline of the instrumentation and counting statistics for neutron output. The other reason is that of out gassing in smaller vacuum vessels. This R^3/ R^2 (volume / surface area) relationship means the technical issues of vacuum considerations is worsened. A smaller vessel is easier to pump down, but the issue is the hydrogen/deuterium embedded in the walls. Plasma bombardment greatly increases the out gassing of these embedded neutrals and this compromises the Wiffleball trapping ratios and thus biases the results in uncertain ways. It is a practical issue, not a theoretical one. This doesn't mean that smaller sizes like those pursued by the Australians and others is worthless, but it does mean that the results are more uncertain and packing in the instrumentation is more difficult. Also, because of the smaller volume per unit of out gassing walls, arcing concerns are magnified; not to mention neutral gas transit times across the magrid interior issues.

And, saying that smaller machines did not work at EMC^2 ignores the facts, some worked for their purposes, other did not work or grossly underperformed, but as Bussard stressed the failures were not based on size, but on the efficiency of electron confinement efforts (and complications of these efforts (eg:WB5)). The spacing, magnet can shape, and smaller nubs was the difference between WB4 and WB6. They had the same radius.

PS: I still think that testing modestly smaller machines with higher order polyhedrons, nub or standoff designs, and coil shapes could be useful and considerably quicker, than testing only one design before a decision for a larger Demo machine was undertaken with subsequent variations then pursued. Not that they should be doing this instead of WB 8, but as a parallel program. I guess available money, confidence, and urgency factor in.

Dan Tibbets

[hanelyp]

Joseph, if you believe that the power doesn't scale at B^4 R^3 for fusion devices, what does your knowledge state power scales at?

n1 * n2<vσ> where due to properties of plasma ni is not proportional to B^2

And what does n1 and n2 represent? Definition of terms, please.

Joe got that half right. n1 and n2 are the density of fuel ions, as used in the Lawson formula. He blows it big time rejecting the proportionality between density and B^2.

For your reference in any magnetic confinement plasma device ...

Polywell is not a magnetic plasma confinement device, it is an electro static plasma confinement device. It is, however, a magnetic electron confinement device. The two are not necessarily synonymous.

... geometric dimension of plasma and therefore density is defined as parity of plasma (gas) pressure and magnetic pressure and not equal to each other due to turbulence of plasma.

But, won't the two pressures find a balance point at which the plasma pressure equals the magnetic pressure? It has always been my understanding that this happens in ANY plasma device.

The plasma pressure can be less than magnetic pressure, in which case the magnetic field penetrates the plasma. The beta=1 condition cited for the polywell applies at the boundary. Inside the plasma the magnetic field is excluded. Outside, plasma pressure drops towards zero.

And that ratio (beta) depends on that how vigorous that turbulence is. Turbulence and instabilities are observed in any plasma devices as plasma by its nature is very agile. And, so, beta never can be equal to 1.

Cannot beta become greater than one (beta > 1), and thus containment of the plasma fail? If not, why not?

My impression is that turbulence is not a factor when particles can freely cross the diameter of the plasma with a smallish chance of collision, a condition which is supposed to prevail in a polywell. The product of density and size is too small to support turbulence. At most you get simple bulk oscillation modes, such as POPS would use.

In a tokomak, on the other hand, the magnetic field penetrating the plasma facilitates waves without direct particle collisions, allowing turbulence.

It is funny to hear (read) that 5 generations of devices were unsuccessful but then beginning from 6-th generation plasma in that type of device is free from any turbulences and instabilities.

For what reason to you believe the "success" of WB6 was due to a lack of turbulence/instability in the contained plasma? According to the information released by Dr. Bussard about WB6 (have you read that information?), instability of the plasma one way or the other was not the reason the WB6 "worked".

The success of WB-6 is clearly stated as recirculation, electrons that escape the wiffleball being recycled or their energy recovered.

[hanelyp]

Try this:
4th Power Scaling

The relevant passage for this thread

If the geometrical
shape, temperature, and composition of an ignited plasma is
kept constant while its overall pressure, magnetic field, and
size are varied, total fusion power varies as

P fusion ∝ β^2 B^4 R^3 (5)

where linear size variation is represented by the plasma
major radius, R, and where β is the plasma pressure
normalized to the magnetic field pressure.

Footnote 5, unfortunately, is a dead link.