The Bussard Fusion Reactor for Dummies.

Discuss how polywell fusion works; share theoretical questions and answers.

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Billy Catringer
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The Bussard Fusion Reactor for Dummies.

Post by Billy Catringer »

I am writing this because I am a real dummy when it comes to particle and quantum physics and I am hoping someone will read it and tell me if and where I have gotten the basic ideas wrong. I have a fairly solid grip on how vacuum tubes work so when I look at the BFR, I tend to think of it as a souped up tube, or valve if you prefer the British term.

One can cause fusion reactions to occur using very small quantities of deuterium gas, or a mixture of deuterium and tritium gas in a vacuum tube using nothing more than a cathode and grid arrangement. The grid serves to steer large number of electrons through a small space in the center of the tube, thereby creating a volume of space that has a very high negative electrostatic charge. When very, very thin streams of ionized deuterium gas are introduced into the vacuum of the tube, their nuclei rush into this volume of negative electrostatic charge and collide. They are guaranteed to collide inside this region of negative charge because they are all attempting to reach what is tantamount to a singularity at the center of that region.


The least likely outcome of these collisions is the fusion of two deuterium nuclei . All sorts of other collisions are more likely to occur and they do. This results in the positive nuclei rocketing off in every direction. Some of them are so energized that they slam into the walls of the tube and stick, but most lose energy prior to reaching the tube wall and fall back toward the negative singularity in the tube and undergo more collisions.

This setup NEVER results in all the nuclei fusing with one another. The majority of them eventually acquire enough energy to escape the system and are lost at the walls of the tube. Meanwhile, the system also loses electrons in much the same way. But, despite all this, a respectable number of fusion reactions does occur.

However, such a system cannot and will not ever produce more energy than it consumes because the losses of both electrons and nuclei is very high and replacing those loses always consumes more energy than the number of fusion reactions can supply.

Here is the real rub, fellow dummies. Physicists glibly speak of "particles" when they talk about anything on the atomic level. That is so misleading that is nearly a lie. When people like you and me hear the word "particle" we tend to think of something like a BB--something you can rattle around in a matchbox or a vacuum tube. That's not nearly so true as we tend to think.

If you try to locate a single electron you get into trouble. It is only ever sort-of-there. At best, it is only right around here. You can never really say with absolute precision exactly where it is. You can, however, place a bet with a sort of cosmic bookie and eventually find out where it was--maybe. The only way we can deal with these subatomic existents is to deal with them in large numbers. When you get a big herd of them together, you can start predicting what will happen with a fair amount of certainty.

One thing, though, that you can count on with absolute certainty[\i] is that a pretty good bunch of them will get away from you. Sometimes they pull off a trick called "tunneling". Tunneling basically means that the consarned thing stopped existing here and decided to exist over yonder without traveling across the intervening space. As far as I can tell, they do that without using any time, either. It's annoying. Schtuff like that ought not happen, but it does.

Fiddling with electrons and other subatomic beasties is like herding shrimp. You will never herd all of 'em into a net or a tank. Losses are inevitable because some of them are literally fated to escape. The best pack of dogs on earth will not let you catch 'em all. The dogs won't be able to catch 'em all or turn 'em all. Oh, and one physicist told me that no one ever really understands quantum physics. He said that the best anyone ever does is to get used to it. It qualifies as black magic as far as I am concerned, and no, I haven't gotten used to it. I still shudder ever time I think about it.

It's important to remember that subatomic existents, "particles", if you must, have fuzzy volumes in space-time. Remember, they are only sort-of in the spot that you think they are in. That's why the singularity at the center of our pseudo-electrostatic charge with a negative sign is so important. Because the "particles" are only sort-of there, we have to work extra hard to make 'em butt heads. If we can't make enough of butt heads to get a large number of fusion reactions the game is over.

Things being what they are, the best we can hope for is to herd up enough of these fuzzy critters for long enough to get something useful done. If we want a yield of energy rather than an expenditure of energy, we hafta work fast. In other words, we will never create a fusion doohicky that will self-sustain the way our chemical and fission energy systems do. With fusion systems you operate them hoping to keep 'em going, unlike all the other systems we use because we operate them to keep 'em from running away and blowing up or catching on fire. Fusion's a very, very different game. Operationally, it's upside down from what we have done in the past.

Doctor Bussard looked at all this and decided that the best way to limit the losses, not eliminate the losses, was to replace the grids in one of these great big vacuum tubes with electromagnets. What the electromagnets do is to steer the electrons, most of 'em anyway, through a small volume of space at the center of the tube. It does not take much of this action to build up what is equivalent to a very large negative electrostatic charge at the center of the tube.

Now, this condition cannot and will not last for very long. The operator has to release his fusible nuclei into the system just as that negative electrical charge maximizes. If the operator timed it right, these positively charged nuclei will collide at very high velocities near the singularity of that negative charge. Some of those nuclei will fuse. Some of them will acquire enough energy to escape altogether, but a lot of them will fall back into the center of that charge for a second chance at becoming a heavier element than it was before. I can't say for how long this will go on.

The cycle time is likely very short and the operator will be obliged to make changes to reset the system. Electrons will be lost. Nuclei will be lost and the fusion products will have to be dealt with, but during each cycle a lot of energy will be released, hopefully more energy than what was required to start the cycle in the first place.

Doctor Bussard said that this is possible in theory. He said it is now a matter of engineering to find out if it can be done profitably, both in terms of energy production and money. Just remember, energy production and money are not necessarily the same thing.

I have no reason to think that Doctor Bussard was being dishonest nor do I have any reason to think he was deluded. I think he came up with something that gives us a fair bet at acquiring a new energy source that would help us out of the bind we are in right now. I also think that the only way we are going to find out if will work, is to build one or several of the machines he described. The proof is always in the pudding. Throwing numbers around and arguing over the basic physics strikes me as being a complete waste of time. It's time to start making drawings and scaring up parts.

jlumartinez
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Post by jlumartinez »


Art Carlson
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Post by Art Carlson »

Not a bad take on it for a "dummy". Just 2 comments: It is surprising how little quantum mechanics or even nuclear physics you have to know to do fusion energy research. 99.999% of the time it is just fine to think of electrons and nucleii as BBs.

Second, concerning
Throwing numbers around and arguing over the basic physics strikes me as being a complete waste of time. It's time to start making drawings and scaring up parts.
If the physics says it ain't gonna happen, then commissioning drawings and ordering parts is a waste of money. Usually the most rational course of action is a combination of contemplation and giving it a try.

Billy Catringer
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Post by Billy Catringer »

Art Carlson wrote:Not a bad take on it for a "dummy".
Thank you very kindly, Doctor Carlson. Just remember that compared to nearly everyone else on this forum I am an innumerate troll. There are times around here when I may as well be in Japan because I can't even read the street signs.
Art Carlson wrote:Just 2 comments: It is surprising how little quantum mechanics or even nuclear physics you have to know to do fusion energy research. 99.999% of the time it is just fine to think of electrons and nucleii as BBs.

Can we ever really escape the quantum madness? I've been trying to come to grips with this cross section business. I'll readily admit that I do not understand it. Usually, when something eludes me the way this does, it has something to do with quantum madness.

Particle cross sections have something to do with the volume of space-time the "particles" manifest their existence in, and their velocities. Even when they are traveling, we can't be entirely certain of where one of them is. They are just sort-of-somewhere near the path we think they are traveling on. You tell me. I'm just a self-educated guy trying to read and understand this stuff. I look at the numbers and they only sort-of tell me something.

What I do understand about it is that you have to jam a large number of these particles together in a very small volume of space-time at the right speed to achieve fusion--or fission. Cross sections are measured in "barns" and "sheds" and as best I can tell the barn is a very large unit, relatively speaking. I don't think we'd have to fool with all this if we were dealing with objects like BB's. We'd just aim all of 'em at the same spot and blaze away.
Art Carlson wrote:Second, concerning
Throwing numbers around and arguing over the basic physics strikes me as being a complete waste of time. It's time to start making drawings and scaring up parts.
If the physics says it ain't gonna happen, then commissioning drawings and ordering parts is a waste of money. Usually the most rational course of action is a combination of contemplation and giving it a try.

Well, fair enough I guess, but you have to understand what makes me say that. Pick your favorite fusion scheme, any one of 'em it won't matter, and what the basic physics says to me is that it most likely will not work, especially if said scheme involves fusion and maintaining conditions where fusion goes on steadily until the system is turned off.

I think the only way that constant fusion can happen is if gravity is involved. We don't know how to manipulate gravity. If we could manipulate gravity, we'd also be manipulating time (assumes I am understanding what Einstein said) and I find that prospect worrisome.

As far as I can tell, the only fusion schemes that stand a remote chance of working are the ones wherein fusion occurs intermittently. Even so, in every fusion scheme you can dream up, some kind of insurmountable engineering problem is likely to rear up and bite you on the butt, and I include Doctor Bussard's machines in that category. Putting the magnetic grid together and getting the timing right in this machine will be a major chore.

So why would I support funding for any fusion energy scheme? Because our economies, may as well say our lives, are limited and controlled by the amount of usable energy available. Major wars have been fought over lesser issues. We cannot afford a major war. Nuclear fission has seen to that. The stakes are high enough that it is worth several attempts to win the pot.

If Doctor Bussard's approach to fusion proves to be workable, then we will have a machine that we might possibly be able to build and use. I cannot see how any technology using the approach planned by ITER will ever be used, even if ITER manages to produce useful quantities of power.

You see the basic physics of Bussard machine to be too badly flawed to be bothered with and, as best I can tell, you have been presenting arguments to support you opinion. Personally, I think that is a good thing. It keeps all the folks who can actually do the designing of this thing on their toes. What your arguments say to me personally is that we will have trouble ever making this thing work, but I already knew that. We have already spent untold sums of money on other designs that did not work. Putting another $200 million to the touch on this design don't scare me one bit.

You might be right and those wanting to test this design may well be wrong, but you are trying to prove a negative on paper. That ain't exactly easy either. I think it is better to spend the money and manhours to find out for sure. Chances are real good that you'll have the last laugh. That does not fade me a bit. It comes with the territory.

IntLibber
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Post by IntLibber »

Billy Catringer wrote:
You might be right and those wanting to test this design may well be wrong, but you are trying to prove a negative on paper. That ain't exactly easy either. I think it is better to spend the money and manhours to find out for sure. Chances are real good that you'll have the last laugh. That does not fade me a bit. It comes with the territory.
Well as for me, Bussard was the tokamak pro, and he could tell you exactly why tokamak will never achieve useful net energy, but will produce some great science. Yet our governments keep dumping billions into some blasted tokamak schemes as if they are going to get us anywhere.

Frankly I think any scientist now supporting tokamaks and attacking polywell who claims to be working toward useful fusion power is someone that law enforcement should be dealing with. They are like alchemists of old, telling people what they want to hear but delivering an emperor with no clothes. It is far too late for us to continue to tolerate such things.

KitemanSA
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Post by KitemanSA »

IntLibber wrote: Well as for me, Bussard was the tokamak pro, and he could tell you exactly why tokamak will never achieve useful net energy, but will produce some great science.
The operative word here is "useful". I believe he knew that if they kept on plugging, eventually they would reach the "net energy" condition, but that it would be cost prohibitive, i.e. not "useful".

Mike Holmes
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Post by Mike Holmes »

It still baffles me every time I see a comment here on why ITER won't work.

Isn't this a Polywell site? Does it make Polywell more likely to work if ITER won't?

I don't see Art saying at all that tests on the Polywell shouldn't happen. He's just predicting that it'll all come to naught. Which the tests will either confirm or deny.

Don't get caught up in identity politics, folks.

Mike

MSimon
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Post by MSimon »

Mike Holmes wrote:It still baffles me every time I see a comment here on why ITER won't work.

Isn't this a Polywell site? Does it make Polywell more likely to work if ITER won't?

I don't see Art saying at all that tests on the Polywell shouldn't happen. He's just predicting that it'll all come to naught. Which the tests will either confirm or deny.

Don't get caught up in identity politics, folks.

Mike
I do not believe the doubt re: ITER is on physics grounds: will it work? It is on practical grounds: what will the energy cost?
Engineering is the art of making what you want from what you can get at a profit.

Mike Holmes
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Post by Mike Holmes »

Ah, I see; fair and balanced. Therefore it must be on topic.

I thought the point under discussion was Billy's understanding of Polywell, and whether or not quantum complexities made working on Polywell difficult. Well, at least that was the part that sounded interesting to me....

Mike

KitemanSA
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Post by KitemanSA »

Mike Holmes wrote:Ah, I see; fair and balanced. Therefore it must be on topic.

I thought the point under discussion was Billy's understanding of Polywell, and whether or not quantum complexities made working on Polywell difficult. Well, at least that was the part that sounded interesting to me....

Mike
Sorry Mike, I hadn't intended to send this off topic. Please continue to discuss BC's points.

chrismb
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Re: The Bussard Fusion Reactor for Dummies.

Post by chrismb »

Billy Catringer wrote:They are guaranteed to collide inside this region of negative charge because they are all attempting to reach what is tantamount to a singularity at the center of that region.
If only that were so.

Your intial post is full of essential understanding. But bear the following matters in mind - for there to be any chance of fast-on-fast collision between ions at the centre then the currents have to be simply enormous. 10's of MA enormous. The types of currents that would totally overwhelm the magnetic fields in such a device.

It is an essential part of the history of the Polywell to realise that Bussard, like so many with fanciful notions of net power from spherical focussing, believed collisions between fast ions at the centre was the usual order of things. There is essentially no evidence that this ever happens.

A 'conventional' fusor works by recirculating fast ions around in a neutral medium and it is fusion with the background medium that leads to fusion. What Bussard tried to do with the Polywell was predicated on his mis-understanding of where fusion actually occurs in a fusor. He mistakenly thought it occurred at the centre of the spherical focus. It doesn't. It never will ( to any significant and measurable extent over fast-ion/background-neutral reactions).

Billy Catringer
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Post by Billy Catringer »

Mike Holmes wrote:It still baffles me every time I see a comment here on why ITER won't work.

Isn't this a Polywell site? Does it make Polywell more likely to work if ITER won't?

I don't see Art saying at all that tests on the Polywell shouldn't happen. He's just predicting that it'll all come to naught. Which the tests will either confirm or deny.

Don't get caught up in identity politics, folks.

Mike

I did not say that ITER will never work. I am reasonably sure that we will never use it, even if it produces power. To some degree, I share Richard Hull's opinion of fusion for power. He and I differ mainly on how one should set about exploring the possibilities.

Billy Catringer
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Re: The Bussard Fusion Reactor for Dummies.

Post by Billy Catringer »

chrismb wrote:
Billy Catringer wrote: It is an essential part of the history of the Polywell to realise that Bussard, like so many with fanciful notions of net power from spherical focussing, believed collisions between fast ions at the centre was the usual order of things. There is essentially no evidence that this ever happens.

A 'conventional' fusor works by recirculating fast ions around in a neutral medium and it is fusion with the background medium that leads to fusion. What Bussard tried to do with the Polywell was predicated on his mis-understanding of where fusion actually occurs in a fusor. He mistakenly thought it occurred at the centre of the spherical focus. It doesn't. It never will ( to any significant and measurable extent over fast-ion/background-neutral reactions).

This is hard news, so I am obliged to ask, how do we know that this is so? Was this conclusion arrived at by calculation or by experimental evidence. If by experiment, can you explain the experiments to a rock-head?

chrismb
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Post by chrismb »

Both experiment and calculation.

Let me know if you need any more than;

viewtopic.php?p=14072#14072

Billy Catringer
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Post by Billy Catringer »

chrismb wrote:Both experiment and calculation.

Let me know if you need any more than;

viewtopic.php?p=14072#14072

Thanks, Chris. I'll read it and think as best I can about it.

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