I've had a quick search and nothing seems to have been discussed over the exhaust from a 800MW reactor.
If you get 3 x 4He forming at the centre with their combined 8.68MeV of energy, they're going to high-tail it out of that 110kV well with ease.
They will totally nail and bombard the coils and the walls of the chamber, sputtering vast quantities of metallic ion debris into the chamber, plus huge quantities of electrons which will neutralise the fields around the magrid. There will be 2E21 alpha particles per second!
How will Polywell deal with this? I understand very low background pressures are required?
Also, what is the permissible DPA (displacements per atom) permitted for the design-intent materials of this device, and what are those materials?
Then, after they've been slowed down by collision with the magrid, how will they then be extracted from the device if they don't form neutrals to drift out of the magnetic fields first?
best regards,
Chris MB.
Helium exhaust. Sputtering contamination.
This thread might be helpful.
viewtopic.php?t=629
You might also want to scan the titles of all of the threads in the design form, some of them may be pertinent.
viewtopic.php?t=629
You might also want to scan the titles of all of the threads in the design form, some of them may be pertinent.
Aero
OK. But what about the magrid. How many steradians of coverage do they represent?
This is assuming the alphas will get past the magrid, no? Or do I misunderstand
I'm also a bit unclear where the electrons recirculate, if there are ion energy recovery parts where the electron recirculation should go?
(Sorry, this should've gone in the design forum. Should I move it over?)
This is assuming the alphas will get past the magrid, no? Or do I misunderstand
I'm also a bit unclear where the electrons recirculate, if there are ion energy recovery parts where the electron recirculation should go?
(Sorry, this should've gone in the design forum. Should I move it over?)
It's all proposals and ideas!
25 years down the road on tokamak, they were already researching neutron bombardment of selected materials. So Polywell is way way behind, then, it does not yet know what the actual problems are yet to even start developing the experiments that might find out what questions need to be asked?
OK. So how will materials be selected that can tolerate embrittlement due to embedded helium build up in the grain boundaries?
How many DPA's is the material expected to tolerate?
How many kPa worth of stress load will the material need to tolerate under full operation?
These aren't engineering challenges to work out as we go, these are potentially make-or-break "do we have the materials" stuff.
EMC2 better stock up on some Unobtanium before it gets too expensive!!
25 years down the road on tokamak, they were already researching neutron bombardment of selected materials. So Polywell is way way behind, then, it does not yet know what the actual problems are yet to even start developing the experiments that might find out what questions need to be asked?
OK. So how will materials be selected that can tolerate embrittlement due to embedded helium build up in the grain boundaries?
How many DPA's is the material expected to tolerate?
How many kPa worth of stress load will the material need to tolerate under full operation?
These aren't engineering challenges to work out as we go, these are potentially make-or-break "do we have the materials" stuff.
EMC2 better stock up on some Unobtanium before it gets too expensive!!
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ravingdave
- Posts: 650
- Joined: Wed Jun 27, 2007 2:41 am
chrismb wrote:It's all proposals and ideas!
25 years down the road on tokamak, they were already researching neutron bombardment of selected materials. So Polywell is way way behind, then, it does not yet know what the actual problems are yet to even start developing the experiments that might find out what questions need to be asked?
OK. So how will materials be selected that can tolerate embrittlement due to embedded helium build up in the grain boundaries?
How many DPA's is the material expected to tolerate?
How many kPa worth of stress load will the material need to tolerate under full operation?
These aren't engineering challenges to work out as we go, these are potentially make-or-break "do we have the materials" stuff.
EMC2 better stock up on some Unobtanium before it gets too expensive!!
I would suggest that the development problems faced by polywell fusion if it works, are trivial compared to the development problems if it doesn't work. If it doesn't work, we needn't worry about any other concerns regarding it. If it DOES work, THEN we can worry about "materials stuff."
David
In other words
Or in shorter words. Right now the problem of how to handle copious fusion products is one we WANT to have.ravingdave wrote:chrismb wrote:It's all proposals and ideas!
25 years down the road on tokamak, they were already researching neutron bombardment of selected materials. So Polywell is way way behind, then, it does not yet know what the actual problems are yet to even start developing the experiments that might find out what questions need to be asked?
OK. So how will materials be selected that can tolerate embrittlement due to embedded helium build up in the grain boundaries?
How many DPA's is the material expected to tolerate?
How many kPa worth of stress load will the material need to tolerate under full operation?
These aren't engineering challenges to work out as we go, these are potentially make-or-break "do we have the materials" stuff.
EMC2 better stock up on some Unobtanium before it gets too expensive!!
I would suggest that the development problems faced by polywell fusion if it works, are trivial compared to the development problems if it doesn't work. If it doesn't work, we needn't worry about any other concerns regarding it. If it DOES work, THEN we can worry about "materials stuff."
David
chrismb: Now you are simply stating the obvious, for what purpose exactly?It's all proposals and ideas!
25 years down the road on tokamak, they were already researching neutron bombardment of selected materials. So Polywell is way way behind, then, it does not yet know what the actual problems are yet to even start developing the experiments that might find out what questions need to be asked?
Polywell has had only a small group of people working for a couple of decades, the two programs are simply incomparable. However, the Polywell does have a stable plasma configuration that can do fusion so it is well ahead of where the Tokamaks were at, in comparison of the development cycle, in terms of man-hours and resource costs.
Also, it would have been fair for your to point out that the Tokamak does not even know what materials it might need either because it has not got a fusion reaction configuration running, despite spending 5 decades of untold man hours, PhD's and billions of dollars. Until Tokamaks can stabilise the plasma and get sustainable fusion they are merely "projecting" what they can do, unfortunately they have done this for 50 years. At present, tokamakers are only merely wishing they could have fusion products streaming out in order to design materials for, for them fusion products are the Unobtainium, (they are selling it mostly it seems).
The thermalised plasma of magnetic confinement machines means that the containing material requirements will always be a lot more severe, since the bulk of the reacting material needs to be at fusion temperature/energies. In the case of the Polywell, only a small amount of material in the very center, ie. furtherest away from retaining vessel, reaches fusion energies. Dealing with products is an engineering problem that Polywell will graduate to, before Tokamak overcomes the physics problems, in my opinion.
Run the numbers, place your bets.
Give me $2 bn a year for 5 or 6 years and I believe I can work it out.It's all proposals and ideas!
i.e. ITER like budgets in 1/10th the time.
I'd start off with 30 test reactors in 10 test facilities.
One Reactor testing
One undergoing modifications
One undergoing cook out then cool down.
In the early phases small LN2 cooled jobs. In later phases large superconducting reactors.
Ten sets of power supplies. Switched from reactor to reactor as the rotation requires.
Complete materials test lab at each facility. Including electron microscope(s), X-ray crystallography, Atomic force microscopes, GCMS, and such other eqpt as deemed necessary.
In other words - once the concept is proved as a net energy generator Manhattanize the engineering.
A lot of this is laid out at:
http://iecfusiontech.blogspot.com/
One project manager, ten lab managers, thirty lab teams of 30 people each (24/7 operation), ten chemistry/materials labs of 30 people each. An IT team for each lab. A central lab for general eqpt development. A dedicated super-computer lab for running simulations (borrow time from existing super-computers to start).
And all of that adjusted as reqmts are developed. But that is the outline.
Engineering is the art of making what you want from what you can get at a profit.
Tokamak, under the small team of Lev Artsimovich at the Kurchatov Institute, began working towards their first tokamak, T-1, in 1955 and by 1968 were testing T-4 and producing the world's first fusing plasma.icarus wrote: Polywell has had only a small group of people working for a couple of decades, the two programs are simply incomparable.
It is true that at that point the two programmes become incomparable. Results were presented in the IAEA meeting of 1968 which stunned the world.
Polywell has yet to get to the point of producing results that stun the world.
What was the exact size of Artsimovich's team compared with the Polywell? I don't know that much detail. How much funding did they get? I would suspect probably actually less than Polywell, but then I guess Communist roubles weren't strictly accounted for. Maybe I suggest you could look these things up and take an interest, just as you might suggest to others that they recognise the Polywell's team's efforts.
Why should tokamak lovers take an interest in the history and efforts of Polywell if Polywell adherents don't want to recognise the history and efforts of tokamak? I am neither, I am trying my best to be impartial and ask difficult questions (of them both...and I do).
The thing that grates is that people seem happy to dismiss facts of history for their own case. The point is - tokamak and Polywell did not start up with such a huge difference of resources, but tokamak gained ground very quickly because it performed and provided results, consistently and reliably.
It was then made available for inspection by western scientists using analytical means to establish key performance criteria, and could be operated reliably so that those measurements could be made.
Learn the history, and it may surprise you. It may also explain to you why there has been the level of attention paid to the tokamak since. Specific, actual problems were recognised and considered worth investigating. Polywell does not yet even know what the problems are that it may face. The presumptions of smooth continuous operation with 'annealing' self-organizing behaviour is quite undemonstrated to date.
And to what plans would you build the first one if you had the money tomorrow? Show me your fuel injection means. Show me your cooling systems for the coils. Show me the energy recovery methods. What is the power output you would aim for? What is the pressure you need to run that at to achieve that reactivity rate? How reliable will it be?MSimon wrote: I'd start off with 30 test reactors in 10 test facilities.
You see, these are OK questions to want to know about and may justify building an experimental device, but describing it as a 'test reactor', I think you are already imagining something more grand than this - something in your first build that will actually generate enough power that you actually can measure it.
I think the guys at EMC2 probably recognise, realistically, that they could not spend that much money so quickly. There is much more to be done before even thinking about scoping the real guts of a test reactor, and by all means progress that activity, but Polywell has not yet earned a devoted budget for itself because of its results, whereas tokamak did that within 15 years.
Chrismb,
Farnsworth achieved first fusion in 1959. Then the idea was dropped because of grid losses. Except for small portable neutron generators. Which are used to this day. About 15 years ago Bussard got the idea of magnetically shielding the grids and was limping along at $1 to $2 mn a year.
Chris,
You really need to get up to speed. You have not RTFM. That is not nice for a newbie. You have been indulged. However, you are becoming more of a luser (correct spelling) every day. Read this about lusers:
http://www.catb.org/~esr/faqs/smart-que ... disclaimer
Go here and read every darn thing that pertains. All the posts that pertain and most of the pdfs on the sidebar.
http://iecfusiontech.blogspot.com/
also here:
http://forum.nasaspaceflight.com/index. ... .0#M136743
You have been preceded by two years of work on these problems. None of your questions is new. Most of the questions you ask have already been worked out to the first order. Some to the second. A lot of very smart people have given freely to the effort. The least you could do is spend a week reading.
And what would I do given unlimited funds today? Build a bunch of fusors. Build a LN2 cooled WB-8. Scale it up linearly by 50% for a WB-9. Build a superconducting WB-10. Then a WB-100.
Then go to the program I outlined I outlined above.
Currently the knowledge base is inadequate to even begin the final engineering push. What do you think? That you are dealing with a bunch of amateurs here? The core group on this blog when it started was a bunch of engineers and physicists of various stripes. Amateurs in Polywell but experienced in their own domains.
You are late to the party. Catch up.
And stop asking "how can you"? Offer solutions. Otherwise you are just sucking up the oxygen for no purpose.
We are here to shorten the development time by anticipating problems and developing solutions. If you would care to join that club it would be helpful. Don't be a luser. Bring something to the table besides criticism.
Fuel injection means? What a luser.
I have 3 or 5 posts on fuel injection here:
http://iecfusiontech.blogspot.com/
How can you be so critical when you are so ignorant? I guess the ignorance makes it easier.
Farnsworth achieved first fusion in 1959. Then the idea was dropped because of grid losses. Except for small portable neutron generators. Which are used to this day. About 15 years ago Bussard got the idea of magnetically shielding the grids and was limping along at $1 to $2 mn a year.
Chris,
You really need to get up to speed. You have not RTFM. That is not nice for a newbie. You have been indulged. However, you are becoming more of a luser (correct spelling) every day. Read this about lusers:
http://www.catb.org/~esr/faqs/smart-que ... disclaimer
Go here and read every darn thing that pertains. All the posts that pertain and most of the pdfs on the sidebar.
http://iecfusiontech.blogspot.com/
also here:
http://forum.nasaspaceflight.com/index. ... .0#M136743
You have been preceded by two years of work on these problems. None of your questions is new. Most of the questions you ask have already been worked out to the first order. Some to the second. A lot of very smart people have given freely to the effort. The least you could do is spend a week reading.
And what would I do given unlimited funds today? Build a bunch of fusors. Build a LN2 cooled WB-8. Scale it up linearly by 50% for a WB-9. Build a superconducting WB-10. Then a WB-100.
Then go to the program I outlined I outlined above.
Currently the knowledge base is inadequate to even begin the final engineering push. What do you think? That you are dealing with a bunch of amateurs here? The core group on this blog when it started was a bunch of engineers and physicists of various stripes. Amateurs in Polywell but experienced in their own domains.
You are late to the party. Catch up.
And stop asking "how can you"? Offer solutions. Otherwise you are just sucking up the oxygen for no purpose.
We are here to shorten the development time by anticipating problems and developing solutions. If you would care to join that club it would be helpful. Don't be a luser. Bring something to the table besides criticism.
Fuel injection means? What a luser.
I have 3 or 5 posts on fuel injection here:
http://iecfusiontech.blogspot.com/
How can you be so critical when you are so ignorant? I guess the ignorance makes it easier.
Engineering is the art of making what you want from what you can get at a profit.
I do not consider your response reasonable. The fusor works, no question, within its known operational limits. Are youtrying to scuggest that the Polywell has actually had 50 years of investigation aswell?? I thought that critisism was kept for tokamak?
The fusor's success or otherwise has nothing to do with the timeline of Polywell. Oliphant achieved beam fusion in the 1930's. Your point being??.. I am told that tokamak is way behind and is not at all comparative. I've simply demonstrated that this is wrong - with facts rather than rhetoric.
The general impression given is that billions of dollars has been spent on tokamak and given nothing. This is completely wrong and must be exposed to be wrong. Not one tiny single US cent was spent on the first 4 tokamaks, and measurable performance and neutrons came out of them.
If you have critiques of the remainder of the programme as it tried to solve each very difficult technical problem then I could probably provide a sharper critique than you. The thread of my questions is to show that THESE are the kinds of quantitive questions tokamak has struggled with for the last 30 years since then. They also had hand-wavy arguments then, and have struggled ever since. WHY will Polywell be different? Enthusiasm is high, funding is there, that's great. But why will the next 30 years be easy for Polywell? I'm seeking to know if the quantitive issues are understood. This is the hard bit, and Polywell hasn't started that phase yet.
Most of the rest of your post is a critisim of me personally, rather than my questions.
On the questions I ask, I have looked for each of these things. I have sought quantitive answers. I have asked quantitive questions. Show me where any of these questions has been asked quantitively before?
To each of these quantitive answer, my arithmetic has not been questioned but instead there are hand-waving arguments.
If you wish to give me an example of where a question of mine has been properly answered before, then I will read that post and, you know I will, I will make amends and extend apologies for being a cludge accordingly.
The fusor's success or otherwise has nothing to do with the timeline of Polywell. Oliphant achieved beam fusion in the 1930's. Your point being??.. I am told that tokamak is way behind and is not at all comparative. I've simply demonstrated that this is wrong - with facts rather than rhetoric.
The general impression given is that billions of dollars has been spent on tokamak and given nothing. This is completely wrong and must be exposed to be wrong. Not one tiny single US cent was spent on the first 4 tokamaks, and measurable performance and neutrons came out of them.
If you have critiques of the remainder of the programme as it tried to solve each very difficult technical problem then I could probably provide a sharper critique than you. The thread of my questions is to show that THESE are the kinds of quantitive questions tokamak has struggled with for the last 30 years since then. They also had hand-wavy arguments then, and have struggled ever since. WHY will Polywell be different? Enthusiasm is high, funding is there, that's great. But why will the next 30 years be easy for Polywell? I'm seeking to know if the quantitive issues are understood. This is the hard bit, and Polywell hasn't started that phase yet.
Most of the rest of your post is a critisim of me personally, rather than my questions.
On the questions I ask, I have looked for each of these things. I have sought quantitive answers. I have asked quantitive questions. Show me where any of these questions has been asked quantitively before?
To each of these quantitive answer, my arithmetic has not been questioned but instead there are hand-waving arguments.
If you wish to give me an example of where a question of mine has been properly answered before, then I will read that post and, you know I will, I will make amends and extend apologies for being a cludge accordingly.
Re: Helium exhaust. Sputtering contamination.
I am just an interested layman, but this has been discussed at length on the forum. The system will need to operate in a vacuum, which will need to be maintained. The pumps that maintain the vacuum will remove the helium byproduct.chrismb wrote:I've had a quick search and nothing seems to have been discussed over the exhaust from a 800MW reactor.
That is one of the quite clever aspects of the machine. As I understand it, the alpha particles will two distinct energy characteristics. There will be a potential gradient to move out of the machine, the alpha particles will need to 'do work' to climb the potential gradient, as they get to the near zero energy location they will be collected by an external electrode, actually two, one for each major species produced. Someone else has described this process like throwing a ball vertically, just at the top of its trajectory, as it starts to fall back to earth, sliding a shelf beneath the ball to arrest its return.chrismb wrote: If you get 3 x 4He forming at the centre with their combined 8.68MeV of energy, they're going to high-tail it out of that 110kV well with ease.
The alpha particles will be neutralised at the collecting grids, this will generate the power it is hoped to generate from the machine. Electrical power will flow through the machine because of the Alpha conversion to Helium. I guess we get lots of Helium too, what can be done with that, does it have a useful industrial use?chrismb wrote: They will totally nail and bombard the coils and the walls of the chamber, sputtering vast quantities of metallic ion debris into the chamber, plus huge quantities of electrons which will neutralise the fields around the magrid. There will be 2E21 alpha particles per second!
Another question. In another thread I have been enlighted to the fact that a hollow charged sphere has no effect on a charged particle inside of it. But, is not the decellerating grids that are susposed to decelerate the alpha particles the same thing? Or does the centrally located structures (magrid and entraped fields) shield the opposite side of the sphere enough that this is trivial?
Dsn Tibbets
Dsn Tibbets
To error is human... and I'm very human.
I have looked and looked and can find nothing about the power ratings of ion injection means. Please may I ask for your help in pinpointing the blog that discusses this.
That's quite funny, you quoting that source then saying this!MSimon wrote: Read this about lusers:
http://www.catb.org/~esr/faqs/smart-que ... disclaimer
....How can you be so critical when you are so ignorant? I guess the ignorance makes it easier.
Maybe you should take a second look at the preceding paragraph about how to respond to rudeness, which points out that sometimes people come across as rude that just want to cut through the b*llsh*t!
It's quite a good note, actually.
But, look, you are a moderator. If you want to point to any single post of mine and demonstrate that I have either personally overreacted to a response or asked a question in a detail that has already been covered in that level of detail before, and then say you don't want me to post stuff like that anymore, then, sure. It's your call and it's up to you to show the goods on how I have made comments at a personal level or in an excessively vexatious manner. I will bear in mind any generalised comments on your perception of me that you may make, but I can't take back or apologise for your perception, only for specific things that you may want to highlight.
It is my opinion that some of *the most* useful and postive contributions can be particularly obstinate, quantitively derived questions. Especially in this business. To me, these *are* postive contributions. If you think asking questions are never helpful and beneficial in themselves to the progress of knowledge, then I will leave you with that sentiment. Personally, I find great value in my logic being critisised, it is my lifeblood. Fire away!