reddit: We are nuclear fusion researchers, ask us anything

[Joseph Chikva]

As far as I know, no one is suggesting that ANY fusion process is "ready for commercialization".

No one? I met some folks here at this board.

There are a lot of suggestions, heck even outright statements that should perhaps have been stated as strong opinions, that certain paths (tokamak for example) will NEVER be ready for commercialization.

Tokamak’s developers commonly solved confinement and stability problem. But till now they can not heat plasma to ignition temperature nether by Ohmic heating nor via neutrals injection. As Ohmic heating is less effective at temperatures exceeding some limit while injected beams drive current (non-inductive current): 2-3 A beam drives megaamperes order current. Higher current excessively increases number density thus causing instabilities. And so weak 2-3 A beam current should increase plasma internal energy to the required value in tens seconds even in case of zero losses. And “zero losses” is impossible. As well as beta=1 for Polywell
But if heating problem would be solved, TOKAMAK is quite viable approach.

Even if/when they reach breakeven, the cost per plant would make the energy therefrom unaffordable.

At engineering phase any fusion approach will have billions USD order cost. And TOKAMAK is already at this stage.

So far, a number of folks, myself included, still hold out hope for certain other paths, like Polywell for example.

Hope, belief. I also holded my hope
that we would win the war with Russia in 2008 as our President promised us. But we lost that war.
Because we had air defense units almost without missiles, or missile boats without missiles, etc. But we did not know that and had a hope on victory.
You did not know even that all ions do not pass center like planets and asteroids in Sun system do not hit the Sun if they have angular velocities. You knew nothing about instabilities being sure that fusion rate is proportional to B^4. That’s wrong statement. Etc.
I think that lack of information generates your hope.

[JohnP]

I was under the impression that the high initial cost of a tok plus the fact that neutrons destroy its own equipment in a matter of months makes the approach economically infeasible, even if the reaction yields surplus energy. No utility in its right mind would invest in one.

[ladajo]

What makes it work is that enough density in space-time does end up near the center with high enough energy delta to make a reaction.

"Enough density" has an unit (number of particles)/m3 or (number of particles)/m3*sec ?

Area under the curve.

Sorry, I want to correct myself. Volume under the surface.

[Joseph Chikva]

I was under the impression that the high initial cost of a tok plus the fact that neutrons destroy its own equipment in a matter of months makes the approach economically infeasible, even if the reaction yields surplus energy. No utility in its right mind would invest in one.

At least fission reactors work suffering high neutron flux. Some of them produce 1kW*h at 2-3 cents of cost.
Be noted that fission neutron average kinetic energy 3 times higher than for neutrons produced by DT reaction. But at the same power fusion reactors need 3 times higher flux. This is solvable problem. And about ten different types of Tritium Breading Modules TBM are already ready for testing for ITER.

[Joseph Chikva]

"Enough density" has an unit (number of particles)/m3 or (number of particles)/m3*sec ?

Area under the curve.

Sorry, I want to correct myself. Volume under the surface.

What unit that volume has: m3 or m3*sec? Surface is 2 or 3 dimensional?

[ladajo]

As far as I know, no one is suggesting that ANY fusion process is "ready for commercialization".

No one? I met some folks here at this board.

Then you are lumping them (I posit less informed as well) in with those of us who do not think Polywell is ready - yet. And no matter your delusions, Tokamok will never be ready for useful use(reverse economy of scale), and Polywell (if it works) will never cost billions to build and run (forward economy of scale).

There are a lot of suggestions, heck even outright statements that should perhaps have been stated as strong opinions, that certain paths (tokamak for example) will NEVER be ready for commercialization.

Tokamak’s developers commonly solved confinement and stability problem. But till now they can not heat plasma to ignition temperature nether by Ohmic heating nor via neutrals injection. As Ohmic heating is less effective at temperatures exceeding some limit while injected beams drive current (non-inductive current): 2-3 A beam drives megaamperes order current. Higher current excessively increases number density thus causing instabilities. And so weak 2-3 A beam current should increase plasma internal energy to the required value in tens seconds even in case of zero losses. And “zero losses” is impossible. As well as beta=1 for Polywell But if heating problem would be solved, TOKAMAK is quite viable approach.

Tokamak is viable only in the sense it can produce (and probably will) produce net power. It is certainly not viable when one considers the cost and cost of size issues to build it for a commerical net power scale. Nor will it ever be. It is simple economics. Tokamak will cost more than some nations are worth. That is not worth it. Why do you persist with the not possible Beta=1 issue when we have given a number of refernces explaining it is so?

Even if/when they reach breakeven, the cost per plant would make the energy therefrom unaffordable.

At engineering phase any fusion approach will have billions USD order cost. And TOKAMAK is already at this stage.

No Joseph, that is the whole point. Not all fusion approaches will cost billions. Tokamak is the most costly, ever. Ever.

So far, a number of folks, myself included, still hold out hope for certain other paths, like Polywell for example.

Hope, belief. I also holded my hope
that we would win the war with Russia in 2008 as our President promised us. But we lost that war.
Because we had air defense units almost without missiles, or missile boats without missiles, etc. But we did not know that and had a hope on victory.
You did not know even that all ions do not pass center like planets and asteroids in Sun system do not hit the Sun if they have angular velocities. You knew nothing about instabilities being sure that fusion rate is proportional to B^4. That’s wrong statement. Etc.
I think that lack of information generates your hope.

This rant is funny on several layers.

First off, Russia thinks it lost the last go around with you as well. So if you both lost, who won? At a minimum you embarassed the shyte out of them. Which in Russian terms, is a major loss. Not to mention the level of casualties in persons and equipment they suffered for accomplishing what?
I must admit, I have wonderd for a while why you all did not just drop the border tunnel? If you had done that up front or early on, it would have ended things much sooner and with much less russians getting in. Oh well, hindsight.

As far as how a Polywell works, we keep telling you it is no Tokamak, but you keep trying to put it in those terms. Angular velocity is important in a Polywell, it is an integral component of the 4D construct, and one that helps it run. Why do you persist in thinking that all the reactions take place in the center, when it is well established on several lanes they do not?

[Joseph Chikva]

Ladajo,
Did you not hear about non-fusion engineering progarmes costed billions? For example for US Military.
Recall that firs tokamaks were quite small and cheep machines but showing much better results that there competitors - much complicated and expensive stellarators.
I am not saying that one commercial TOKAMAK reactor will cost billions but program no doubt will.
Good luck.

[mvanwink5]

Joseph,
My condolence to you and countrymen for the losses in men and property suffered in the conflict with Russia. I hope there will only be peace and respect in the future.

I appreciate the points that you raise for polywell operation and see that only time will reveal the viability of its operation or its failure. I was hoping to get some insight this year on that verdict, but am now not expecting news until the end of this year or early next year. I am sure if it does work that it will also be a boon for your country as there is all intention to make this available to the world. That was Dr. Bussard's dream.
Best regards

[Robthebob]

Tokamak’s developers commonly solved confinement and stability problem. But till now they can not heat plasma to ignition temperature nether by Ohmic heating nor via neutrals injection. As Ohmic heating is less effective at temperatures exceeding some limit while injected beams drive current (non-inductive current): 2-3 A beam drives megaamperes order current. Higher current excessively increases number density thus causing instabilities. And so weak 2-3 A beam current should increase plasma internal energy to the required value in tens seconds even in case of zero losses. And “zero losses” is impossible. As well as beta=1 for Polywell
But if heating problem would be solved, TOKAMAK is quite viable approach.

This is wrong, they have no problem with heating, they have RF heating, alpha channeling for burning plasma, and a bunch of other things. The problem has been about confinement, as it has always been about that, even that, as i was told, isnt really that big of a problem, because the the whole instability problem can be tamed the hard way in toks or by just building a stellerator.

The nail in the coffin issue, from before to now, has always been about the fact that you need a really huge huge machine for it to generate economical net energy, in the end, the maintenance, the start up cost, repair, everything is just too much

I dont know where you got the idea that you can only heat by neutron injection and ohmic heating in torodial magnetic machines.

[Robthebob]

No Joseph, that is the whole point. Not all fusion approaches will cost billions. Tokamak is the most costly, ever. Ever.

I think inertial confinement by beam compression is only in the single digits of billions at most, and I'm sure that toroidal magnetic confinement will be in the tens of billions at lowest, if they're going to build a net reactor.

I'm really confused about why everyones still behind toks, stellerators is what toks should be, and the beam compression guys are, I was told, actually closer to getting it done than the tok guys... but whatever.

I actually feel really bad that I do not possess enough of the technical understanding of polywell to be able to detect if Joesph is saying a bunch of nonsense or if he's raising real concerns. To be completely and brutally honest, I cant tell if Joesph is serious or not. He understands what we've said, and it just seems despite the amount of evidence (I actually dont know if it's hard evidence or heresy or what) about how polywell scales, how it doesnt suffer from (at least toroidal magnetic confinement) instabilities, how the fusion process doesnt have to only happen at the very center, only the center region, etc, it's like we're all lying... or something.

A lot of what's posted actually go way over my head, despite the fact I've followed polywell for years now and I have a BS in physics with specialization in plasma physics (mostly toroidal magnetic confinement, what good does it do for me?)

[Joseph Chikva]

This is wrong, they have no problem with heating, they have RF heating, alpha channeling for burning plasma, and a bunch of other things.

This is correct.
Ohmic heating limit about 200 keV.
Then RF heating and heating with the help of injection of neutrals. Main is injection of neutrals. Also this injection drives the current that is the key element in TOKAMAK confinement concept (creates poloidal magnetic field).

But for ignition they have to heat plasma to at least 10KeV = 1E4 eV = ~1E8 K
Plasma volume for ITER if I recall correctly 840 m3
Number density 2E20 m^-3
So in case if Te=Ti the internal energy of plasma 0.84E3*2E20*1E4=1.68E27eV = =2.7E8 J = 270 MJ

And 2 A current of 2 MeV neutrals carries the power 4 MW of power.
So, for input into the plasma 270 MJ you need 270/ 4 = 67.5 sec (in case of zero losses)

These all are real numbers.

And why they can not increase the neutral beam's current? Because 2 A of beam's current drives plasma current of megaamperes. This is so called H-mode (high confinement mode). And they can not increase plasma current as this wouyld increase also beta. TOKAMAK has Troyon's limit of beta=4. Real numbers is beta=0.01-0.1 (higher numbers for low aspect ratio TOKAMAKs)
For your not for driving plasma current of 5 MA by induction only 0.5 loop voltage is required.

[Joseph Chikva]

Joseph,
My condolence to you and countrymen for the losses in men and property suffered in the conflict with Russia. I hope there will only be peace and respect in the future.

I appreciate the points that you raise for polywell operation and see that only time will reveal the viability of its operation or its failure. I was hoping to get some insight this year on that verdict, but am now not expecting news until the end of this year or early next year. I am sure if it does work that it will also be a boon for your country as there is all intention to make this available to the world. That was Dr. Bussard's dream.
Best regards

Thank you very much.

[ladajo]

Ladajo,
Did you not hear about non-fusion engineering progarmes costed billions? For example for US Military.
Recall that firs tokamaks were quite small and cheep machines but showing much better results that there competitors - much complicated and expensive stellarators.
I am not saying that one commercial TOKAMAK reactor will cost billions but program no doubt will.
Good luck.

I thought we were talking about fusion. Not space programs.

I am saying that one commercial Tokamak WILL cost billions (and billions).

I am also saying that other approaches may well pan out to be orders of magnitude cheaper to build commercial plants.

By the by, I am also sad for your countries losses in the conflicts with Russia. I also wish that my country had done more to intervene than we did. But, I guess something is better than nothing. Let us all hope that the Russian leadership does not decide that invading another neighbor is necessary in the future. Although, of this I am not convinced. Especially if Polywell or another viable fusino solution plays out. The Russian leadership and economy is very much dependant on oil and gas money.

[Roger]

Recall that firs tokamaks were quite small and cheep machines but showing much better results that there competitors - much complicated and expensive stellarators.

A small detail, IIRC the first magnetic donut to study plasma was in the UK, late 1940's. about 2 meters. Then in 1953 came the Stellerator (3 meters?), the big Russian Tok success was I think '68?

But I see no purpose to talking about Tokamaks, building something the size of a couple of football stadiums that cost 25+ billion USD, just to potentially generate a couple of 1000MW will never happen, its utterly impractical.

At least a fission nuke lasts for 40 yrs.

[KitemanSA]

As far as I know, no one is suggesting that ANY fusion process is "ready for commercialization".

No one? I met some folks here at this board.

Name and cite?

There are a lot of suggestions, heck even outright statements that should perhaps have been stated as strong opinions, that certain paths (tokamak for example) will NEVER be ready for commercialization.

Tokamak’s developers commonly solved confinement and stability problem. But till now they can not heat plasma to ignition temperature nether by Ohmic heating nor via neutrals injection. As Ohmic heating is less effective at temperatures exceeding some limit while injected beams drive current (non-inductive current): 2-3 A beam drives megaamperes order current. Higher current excessively increases number density thus causing instabilities. And so weak 2-3 A beam current should increase plasma internal energy to the required value in tens seconds even in case of zero losses. And “zero losses” is impossible. As well as beta=1 for Polywell
But if heating problem would be solved, TOKAMAK is quite viable approach.

If ITER is an example of a VIABLE approach, I suspect you need to look up the word viable more carefully.

Even if/when they reach breakeven, the cost per plant would make the energy therefrom unaffordable.

At engineering phase any fusion approach will have billions USD order cost. And TOKAMAK is already at this stage.

Yup and billions like that are too much for a viable system. Too expensive. Kind of like wind.

So far, a number of folks, myself included, still hold out hope for certain other paths, like Polywell for example.

...
...
You did not know even that all ions do not pass center like planets and asteroids in Sun system do not hit the Sun if they have angular velocities.

Which are you, a liar or a fool?

Despite your not-so-vailed insult, I assure you that I do not think that. But you seem to hop around so adroitly in your assumptions that I sometimes have difficulty understanding the basis of your discussion.

I do not insult anybody.

Then you write that meadow muffin above. So, liar or fool?

You knew nothing about instabilities being sure that fusion rate is proportional to B^4. That’s wrong statement. Etc.
I think that lack of information generates your hope.

Again, it must be that either your English is too bad to carry on a decent conversation or you just want to lie aout everything.

I made a statement about what OTHERS had said about power scaling, and provided you with independant sources for that statement. All you have done is mis-read reports REPEATEDLY, claim that such info doesn't apply, fail to provide back-up, and call OTHERS ignorant.

We have a saying in the States, "put up or shut up".