Polywell versus Focus Fusion

[nuclearnoob]

I'm curious to know what the big brains think about the relative merits, possibilities, and perils of Focus Fusion and Polywell. Which is more likely to work and become a reality sooner than later? These both could be long shots but seem to be the most promising of the fusion schemes. The idea of harnessing the instability of plasma as with focus fusion is intriguing, and no superconducting magnets needed, which makes life so much simpler. Also its small and could soon be hot enough to burn PB11. What do you guys think?

[Tom Ligon]

We had a related discussion recently. Focus Fusion has, for several years at least, been a courteous competitor, and I try to reciprocate. I think the device is clever and may be able to make some fusion, but it is intrinsically a thermal device. I'm not clear how they think a thermal machine will burn p-B11. If you have fuel and electrons in thermal equilibrium at temperatures sufficient to fuse protons with boron, the Bremsstrahlung radiation should be a killer.

I'm intrigued by the device, though. The best I can tell, the plasmoids it creates may meet Paul Koloc's description of ball lightning, essentially a spheromak with no physical structure to support it. That approach ought to be capable of at least some fusion.

I'm inclined to let them have at it. If they can make it work, it should work with a smaller device than a Polywell. If it can't be made to work, it is an inexpensive project (compared to a large tokamak or NIF), and the basic device probably has other potential applications.

[nuclearnoob]

Sorry for the redundant thread. I missed the original. Eric Lerner lays out focus fusion in an interesting google talk. He does address x ray cooling as a factor in the process but doesn't seem overly concerned about it for some reason. There's more than enough room in the world for polywell and FF. I just don't understand why the government has put all of its chips into the most complicated, inefficient, expensive and massive concepts like Tokomak and the national ignition facility in lieu of small, clean and cheap concepts. I'm not a scientist but this stuff is fascinating. Thanks for the reply.

[chrismb]

I just don't understand why the government has put all of its chips into the most complicated, inefficient, expensive and massive concepts like Tokomak... in lieu of small, clean and cheap concepts.

Because much as the small cheap concepts look good on paper, they've yet to show substantive evidence that they might work. Has tokamak? For all the denigration of it, the answer is yes, it has. It is unstable and may ultimately prove to be un-fixably unstable. But fusion is a process with very poor specific power outputs and it needs to be huge to get anything resembling useable grid power.

Yeah, sure, Polywell can be talked up to produce MW from pin-heads, but only on paper! Whereas JET has produced MW of neutrons. And that's a whole lot of neutrons (1E19/sec).

Just reflect on how much a 1GW power plant costs to build based on known technologies, and the projected bill for ITER looks comparable. In fact, it looks so comparable that one must suspect it will prove to be a serious under-estimate of its costs.

(I deleted NIF, as I think it is an irrelevance. It appears to be there for weapons development - the fusion-power narrative is presumably just spin to get funding.)

[nuclearnoob]

After billions of dollars and decades of work, yes, tokamaks have achieved the most progress. I realize that this is a significant achievement. Definitely these other fusion concepts could vanish into thin air but they have reached their own milestones and cannot be easily dismissed. In some ways it probably was natural to back tokamaks and hydrogen. DOE and defense have a history of working together and there was probably a strong pro hydrogen bias since its related to weaponization whereas I would imagine PB11 is not useful for such purposes. The tokamak route might seem easier than these other concepts, but its not clear if that's actually the case. I think its more of a tough call when you account for engineering as well as physics realities. Tokamak fusion was once theoretical too. I just don't understand why you would accept the unattractive trade-offs of this scheme instead of trying several different higher risk but much better reward schemes.

[chrismb]

I just don't understand why you would accept the unattractive trade-offs of this scheme instead of trying several different higher risk but much better reward schemes.

If that is aimed at me, then understand that I am fully in favour that all such schemes are adequately funded. I believe that, generally speaking, they are. I do not think Polywell could handle a larger influx of money right now, as it has to properly come to terms with proving out the 'wiffleball' effect and if it can generate fast-fast fusion. I think it has enough money to do that. If projects have more money than can be justified, then they risk running out of control and taking on their own momentum. This is clearly the case with [at least] the previous incarnation of he NIF budget and is potentially something that could be argued for ITER, though the latter is somewhat more complex an issue as such a scale of project clearly would need that much funding. I think it should likely need much much more, in point of fact.

[MSimon]

I just don't understand why you would accept the unattractive trade-offs of this scheme instead of trying several different higher risk but much better reward schemes.

If that is aimed at me, then understand that I am fully in favour that all such schemes are adequately funded. I believe that, generally speaking, they are. I do not think Polywell could handle a larger influx of money right now, as it has to properly come to terms with proving out the 'wiffleball' effect and if it can generate fast-fast fusion. I think it has enough money to do that. If projects have more money than can be justified, then they risk running out of control and taking on their own momentum. This is clearly the case with [at least] the previous incarnation of he NIF budget and is potentially something that could be argued for ITER, though the latter is somewhat more complex an issue as such a scale of project clearly would need that much funding. I think it should likely need much much more, in point of fact.

I think Polywell might be able to profitably use a few more million. In fact I think that around $10 to $15 million for a continuous operation machine might be in order.

But I do think that you are right. Too much money can kill a project just as easily as too little.

Plasma Physicist Dr. Nicholas Krall said, "We spent $15 billion dollars studying tokamaks and what we learned about them is that they are no dam n good."

[kurt9]

I just don't understand why you would accept the unattractive trade-offs of this scheme instead of trying several different higher risk but much better reward schemes.

If that is aimed at me, then understand that I am fully in favour that all such schemes are adequately funded. I believe that, generally speaking, they are. I do not think Polywell could handle a larger influx of money right now, as it has to properly come to terms with proving out the 'wiffleball' effect and if it can generate fast-fast fusion. I think it has enough money to do that. If projects have more money than can be justified, then they risk running out of control and taking on their own momentum. This is clearly the case with [at least] the previous incarnation of he NIF budget and is potentially something that could be argued for ITER, though the latter is somewhat more complex an issue as such a scale of project clearly would need that much funding. I think it should likely need much much more, in point of fact.

I think Polywell might be able to profitably use a few more million. In fact I think that around $10 to $15 million for a continuous operation machine might be in order.

But I do think that you are right. Too much money can kill a project just as easily as too little.

Plasma Physicist Dr. Nicholas Krall said, "We spent $15 billion dollars studying tokamaks and what we learned about them is that they are no dam n good."

They need to demonstrate the scalability of the plasma and cusp neutrality before they can go on to the next step. My understanding is that the scalability is still theoretical and needs to be confirmed experimentally.

[KitemanSA]

I just don't understand why you would accept the unattractive trade-offs of this scheme instead of trying several different higher risk but much better reward schemes.

If that is aimed at me, then understand that I am fully in favour that all such schemes are adequately funded. I believe that, generally speaking, they are. I do not think Polywell could handle a larger influx of money right now, as it has to properly come to terms with proving out the 'wiffleball' effect and if it can generate fast-fast fusion.

Whereas MSimon and I think it could use a bit more money. Naturally, we'ld use it for different things. I think another 1.5ish M$ would allow some parallel processing to resolve magnet shape issues regarding sphericity and cusp length reduction.