The Bussard Fusion Reactor for Dummies.
Posted: Fri Feb 06, 2009 10:38 pm
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.
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.