What are the major hurdles in making a Polywell work right now (besides the obvious size of the machine). What are there obstacles that one might face while trying to reach break-even ? And as far as theory goes, did Dr. Bussard/anyone else face any problems while developing the process on paper ?
I thought that one of these Q & A might be useful here when I was browsing through the older threads and noticed theres a lot of one-time questions that had whole threads devoted to them. Since I dont get very much of whats going on with the WB's , I will probably be asking a lot of questions and this seemed a simpler way to do it.
Q&A : Major hurdles to overcome for Polywell Reactors
I'll presume for the moment that the basics work and Dr. Nebel and the team will be able to confirm and expand upon Dr. Bussard's results.
I have no doubt that the basic scaling law is correct, and bigger is better on a very steep curve.
My experience with these machines is they generate a lot of hydrogen when they run, which would tend to dilute the fuel. The machines I ran all had high electron loss paths, into metal. That's what generated the hydrogen ... the bombardment dug it out of the metal. If WB6, WB7, and later designs confine electrons better, they should generate less gas, but they will still generate some. I worry that will interfere with continuous operation. We'll see how good they are.
Everyone who has considered it realizes there will be a load on the magrid by fusion products in any net power machine. This is bound to sputter off material. How much can the reaction tolerate, and how could you get rid of the heat?
Neither of these keep the machine from running, but they might require it to run in short pulses. I think both problems, or some close variant, would occur in tokamaks, too.
Dr. Bussard told me he considered one problem after another, over the years, which he thought might prevent the scheme from working. This includes all of the "Todd Rider objections" which you will find discussed here or at fusor.net, plus some Rider never considered. In each case there was either an easy work-around or further analysis proved the machine had an inherent way of dealing with it. In fact, Dr. Bussard was impressed that analyzing a supposed problem often revealed the machine would actually work better than he originally expected.
The project was held up for years struggling with failure to recirculate electrons efficiently. The problem was finally found to be due to a couple of simple geometry problems. Incorporating these simple changes in WB6 improved performance about three orders of magnitude.
There was a seductive but fatally-flawed approach which Dr. Bussard attempted to beat with three machines: HEPS, PXL-1, and WB-5. These were the "closed box" machines with the magnets mounted outside, instead of magrid machines like WB6. Rider's objection about electron losses to the cusps are valid for these machines, which can't recirculate electrons that leak out the cusps. As nearly as I can tell, Rider never actually looked at magrid machines, only at HEPS.
I have no doubt that the basic scaling law is correct, and bigger is better on a very steep curve.
My experience with these machines is they generate a lot of hydrogen when they run, which would tend to dilute the fuel. The machines I ran all had high electron loss paths, into metal. That's what generated the hydrogen ... the bombardment dug it out of the metal. If WB6, WB7, and later designs confine electrons better, they should generate less gas, but they will still generate some. I worry that will interfere with continuous operation. We'll see how good they are.
Everyone who has considered it realizes there will be a load on the magrid by fusion products in any net power machine. This is bound to sputter off material. How much can the reaction tolerate, and how could you get rid of the heat?
Neither of these keep the machine from running, but they might require it to run in short pulses. I think both problems, or some close variant, would occur in tokamaks, too.
Dr. Bussard told me he considered one problem after another, over the years, which he thought might prevent the scheme from working. This includes all of the "Todd Rider objections" which you will find discussed here or at fusor.net, plus some Rider never considered. In each case there was either an easy work-around or further analysis proved the machine had an inherent way of dealing with it. In fact, Dr. Bussard was impressed that analyzing a supposed problem often revealed the machine would actually work better than he originally expected.
The project was held up for years struggling with failure to recirculate electrons efficiently. The problem was finally found to be due to a couple of simple geometry problems. Incorporating these simple changes in WB6 improved performance about three orders of magnitude.
There was a seductive but fatally-flawed approach which Dr. Bussard attempted to beat with three machines: HEPS, PXL-1, and WB-5. These were the "closed box" machines with the magnets mounted outside, instead of magrid machines like WB6. Rider's objection about electron losses to the cusps are valid for these machines, which can't recirculate electrons that leak out the cusps. As nearly as I can tell, Rider never actually looked at magrid machines, only at HEPS.
Being pretty realistic, heres a short list.
- Thermal issues. Keeping non super conducting coils cool from ohmic losses. Keeping super conducting coils below T=Sc. SC Quenching will lead to catastrophic reactor failure. Plumbing will be tricky.
- Sputtering/Contamination issues from reactor products. The particles formed from fusion products will not only heat, but will atomically "sand blast" the coils and supports/feeds contaminating the reactor.
- B fields. We need to generate a couple of Tesla of magnetic field. Some high temperature super conductors dont like high power magnetic fields. The coils will need carefull design to reduce the magnetically induced mechanical stress on the coil wires and supports. Might have contributed to coil failure in WB6
- Electric fields. You will need at least 160kv on the main coils, to attract electrons to form a potential well suitably deep enough to take advantage of the p + B11 peak fusion cross section. Dr Bussard details the problems faced with Paschen arcing in his Last 2 papers. If we want to take advantage of Direct Alpha Conversion into Electricity we will need a at least a 1.88 Mev field around the outer grid (thanks Tom) which will cause headaches with electron recirculation etc. Nothing catastrophic but Efield issues will most likely increase the overall reactor diameter than that envisioned.
- Electron Injection. The Child Langmuir space charge limit, places a limit on the rate you can inject an electron beam from an emitter into the cusp. Too high and you will form a vircator infront of your emitter. Ionization schemes may get around this, so does the fact the polywell seeds its own electrons. Electrons get left behind when alphas get emitted (Very cool me thinks)
- Fusion Fuel "Carburation" and control issues. Getting the fuel into the machine, metering the fuel and analyzing whats happening in reactor space at very small timescales. Pushing the limits of computer technology and control. Current injector technology is woefully inadequate, we need something completely new. Injecting fuel into a High Vacuum 10^-6 Torr is also very tricky as it degrades the vacuum. Waste products will need to be filtered out. This will also require some fresh tech.
- Electron Losses. Electrons need to recirculate with high precision and low losses. Cant find the exact number but we need to do all of the above while keeping electron losses absolutely minimal. Any electron losses degrade the possibility of net power production very quickly.
- Power Supplies to make it all happen. Will be massive, like the jungle. Still gives me goosebumps when i think about them. Worthy of some more discussion here.
- Finance as long as there is plenty of oil left to sell the Illuminati NWO conspiracy will continue to actively suppress and distract people from Non Maxwellian Aneutronic Fusion Power *jokes*
I couldnt have said it better Tom. Each time i find a problem with the Polywell i end up finding a solution to it and then some. Viva Polywell !Tom Ligon wrote:In each case there was either an easy work-around or further analysis proved the machine had an inherent way of dealing with it. In fact, Dr. Bussard was impressed that analyzing a supposed problem often revealed the machine would actually work better than he originally expected.
Purity is Power
Keegan,
B-fields for Cu coils. The Bitter design should provide adequate strength and mechanical stability.
If operation is feasible at the p-B11 peak 50 to 70KV operation would work.
In addition the ultimate gain possible goes from around 8 to around 20. Much more favorable to net power.
Fuel injection - I have done some preliminary calculations and most of the fuel injected will be "sucked" out by the vacuum pumps. All that is required to maintain a given pressure is to adjust the flow to pump capability. A suitable servoed valve (I have a preliminary design) should do the trick.
Power supplies for a test reactor will be in the 2 to 20 MW range. Steady state they may operate at lower power. If so a large capacitor bank coupled to the supplies might do the trick for start up.
You left out the possibility of POPS enhancement.
Viva Polywell!!!!!!!!!!
B-fields for Cu coils. The Bitter design should provide adequate strength and mechanical stability.
If operation is feasible at the p-B11 peak 50 to 70KV operation would work.
In addition the ultimate gain possible goes from around 8 to around 20. Much more favorable to net power.
Fuel injection - I have done some preliminary calculations and most of the fuel injected will be "sucked" out by the vacuum pumps. All that is required to maintain a given pressure is to adjust the flow to pump capability. A suitable servoed valve (I have a preliminary design) should do the trick.
Power supplies for a test reactor will be in the 2 to 20 MW range. Steady state they may operate at lower power. If so a large capacitor bank coupled to the supplies might do the trick for start up.
You left out the possibility of POPS enhancement.
Viva Polywell!!!!!!!!!!
Engineering is the art of making what you want from what you can get at a profit.
Yep ! Bitter magnets are a great design. Cant believe nobody has mentioned them yet. Will be great in a test reactor with CU and liquid cooling. Sadly very hard to apply to Super Conductors.
Wow...... Thats nice knowMSimon wrote:If operation is feasible at the p-B11 peak 50 to 70KV operation would work.
In addition the ultimate gain possible goes from around 8 to around 20. Much more favorable to net power.
Purity is Power
One word, outgassing. Vacuum is going to have to drive everything and controlling the vacuum is going to control, especially if you get sputtering combined with high voltages. Arcing will really ruin your day as it does things you have to see to believe.
In order
1. Magnet containment, insulation. The MaGrid magnets are going to require a ceramic insulator that is free or virtual leaks or be totally enclosed in a vacuum tight envelope. Also the coil shape will have to follow the magnetic field profile to avoid field peaking.
2. Keeping the grids clean and placing pumps behind the grids without causing a ground through an ion pump.
3. Preventing oddball virtual leaks and making sure all internal hardware vents properly.
In order
1. Magnet containment, insulation. The MaGrid magnets are going to require a ceramic insulator that is free or virtual leaks or be totally enclosed in a vacuum tight envelope. Also the coil shape will have to follow the magnetic field profile to avoid field peaking.
2. Keeping the grids clean and placing pumps behind the grids without causing a ground through an ion pump.
3. Preventing oddball virtual leaks and making sure all internal hardware vents properly.
I think everything that goes into the vacuum chamber will have to be welded shut.Jccarlton wrote:One word, outgassing. Vacuum is going to have to drive everything and controlling the vacuum is going to control, especially if you get sputtering combined with high voltages. Arcing will really ruin your day as it does things you have to see to believe.
In order
1. Magnet containment, insulation. The MaGrid magnets are going to require a ceramic insulator that is free or virtual leaks or be totally enclosed in a vacuum tight envelope. Also the coil shape will have to follow the magnetic field profile to avoid field peaking.
2. Keeping the grids clean and placing pumps behind the grids without causing a ground through an ion pump.
3. Preventing oddball virtual leaks and making sure all internal hardware vents properly.
ITER uses a boron coating to get a handle on the first wall problem. I discussed that with Dr. Mike and others in another thread (do a search).
There are a raft of problems that will have to be solved. Dr. Bussard said it came down to engineering (I assume he had a wry smile on his face and a gleam in his eye when he said that).
I liked what Bucky Fuller had to say about the matter. When you get good at engineering things don't get easier. You get harder problems. I'm looking forward to it.
When all the problems get solved (well enough to deliver power) it will be a day of triumph and depression. Triumph for having made it work. Depression because, there will likely not be such a tall mountain to climb for quite a while. The journey is where the fun lies. The destination is the end of the journey.
Engineering is the art of making what you want from what you can get at a profit.
Applications, refinement and changes to humanity
I refer to (I think it was Tom Ligon's) comparison of the current state of polywell IEC to the internal combustion engine - with a few drops of fuel and a few bangs, and the sceptics crying "never."MSimon wrote:When all the problems get solved (well enough to deliver power) it will be a day of triumph and depression. Triumph for having made it work. Depression because, there will likely not be such a tall mountain to climb for quite a while. The journey is where the fun lies. The destination is the end of the journey.
With a net power polywell, the next step is to continually refine and improve performance. Look at the internal combustion engine - how much engineering has gone into that to get better results over the decades?!
Then there is the whole business of applications... Yes, we can just use it to push electrical power into the grid. But then there is the ship-borne applications. What about aircraft? And space-borne applications - both in propulsion and in power? Trains and possibly big-rigs have been mentioned if we can reduce the size (and realistically the output power) appropriately.
Taking our new toy and creating many different applications will be a huge field of endeavor.
I would offer that the feelings should be triumph and satisfaction. For this is a technology that could change the face of humanity, with virtually limitless, non-polluting energy supplies, access to space, reduced cost transportation, the variety of applications and benefits has only just been touched on.
Maybe the "what if it works/what if it doesn't?" questions will have been answered. Yes, the 'mountain will have been climbed.' But there will still be so many satisfying engineering challenges to address. (Think of all the peer reviews!!
)Be Safe
Mumbles
Mumbles,
There is much truth in what you say.
However, my experience in large engineering projects is that despite the satisfaction there is a let down.
Part of that of course is that the team breaks up. The associations of years dwindles.
Yes there will be new hills to climb. That is exciting. But the mountain will have been leveled.
What we are working on (if it works) is game changing. What will be left is obvious extensions.
There is much truth in what you say.
However, my experience in large engineering projects is that despite the satisfaction there is a let down.
Part of that of course is that the team breaks up. The associations of years dwindles.
Yes there will be new hills to climb. That is exciting. But the mountain will have been leveled.
What we are working on (if it works) is game changing. What will be left is obvious extensions.
Engineering is the art of making what you want from what you can get at a profit.
I think the statement "you get harder problems" is what really counts. OK, so we get Polywell to work. Then we build rockets to mars. Then we build cities on mars. And by "we" I mean humans. I'll be long dead before cities show up on mars. But they will show up.
Knowing there are always more challenges makes a nice emotional rebound after solving a previous one!
Knowing there are always more challenges makes a nice emotional rebound after solving a previous one!
Team Let-down... yeah, I can see that...
O.K., I'm all for that. Having a close-knit group of smart individuals all focused on a single goal, and then transitioning to a myriad of different projects and efforts would/WILL be a let-down. Like winning the state championship - a moment of glory - but also the final game for many a senior...MSimon wrote:Mumbles,...
Part of that of course is that the team breaks up. The associations of years dwindles....
I did like the next comment:
Heck, that is all some of us have now anyway!! I think I am one of quite a few of us, stuck on 'the outside,' watching through the internet/blog window, hoping to be there as something great happens. While I think I have some skills, talents and experience that could be applicable at a later stage, I don't have the freedom to pursue helping out now (maybe after year 20, next summer?...Go Navy!). (Nor do I have the ego to think, that in the group of very smart people conversing in these pages, that I can keep up!) Maybe as we transition to some of those aero- and astronautical "applications"...MSimon wrote:that we have the advantage of the internet to maintain the contacts
Be Safe
Mumbles
Re: Team Let-down... yeah, I can see that...
Some of us have even less. Here I am a simple 20-year-experience software geek with a bit of concern about bringing whatever I can to bear on healing all harms everywhere and all I can do here is lurk, read and cheer from the sidelines. I guess there are other random speculations likeMumbles wrote:Heck, that is all some of us have now anyway!! I think I am one of quite a few of us, stuck on 'the outside,' watching through the internet/blog window, hoping to be there as something great happens. While I think I have some skills, talents and experience that could be applicable at a later stage, I don't have the freedom to pursue helping out now (maybe after year 20, next summer?...Go Navy!). (Nor do I have the ego to think, that in the group of very smart people conversing in these pages, that I can keep up!) Maybe as we transition to some of those aero- and astronautical "applications"...
* wondering how much "warming" all this polywell-generated power is going to add to the earth, never mind greenhouse gases...
* wondering if smaller, more localized power generators all over the world would drive down copper demand so that this slashdot article would no longer be true...
I wish you all well and I will keep reading and learning...
cheers...ank
#include <stddisclaimer.h>
ansak,
Currently man produces 1/5,000th the energy of solar input.
If the cloud feedback guys are right we would need to get in the range of 1/250th to raise earth temps 1 deg C. Even if they are wrong, doubling the efficiency of electrical generation and going to hybrids for short trips should allow us to raise the standard of living of everyone on the planet to first world levels without serious thermal problems.
Currently man produces 1/5,000th the energy of solar input.
If the cloud feedback guys are right we would need to get in the range of 1/250th to raise earth temps 1 deg C. Even if they are wrong, doubling the efficiency of electrical generation and going to hybrids for short trips should allow us to raise the standard of living of everyone on the planet to first world levels without serious thermal problems.
Engineering is the art of making what you want from what you can get at a profit.