ITER Deep In The......

[GIThruster]

Please list the alternatives. 20-30 sounds fantastic to me. Lets see the leads.

[MirariNefas]

I understand that most of the arguments against tokamak fusion is that, if/when we can get it to grid, the device will be monstrously huge, and the heavy radiation load will be a pain in the ass (necessitating common shut downs for maintenance and whatnot). Also tritium breeding doesn't sound too hot.

What chances are there for a tokamak with a better fuel, like p-b11? For that you need better confinement, and to get better confinment, you build tokamaks bigger and bigger. So, it would be monstrously, ginormously huge - but could have direct energy conversion, low down time, etc etc.

Any possibility?

[MirariNefas]

Furthermore, it will probably shatter the public's confidence in tokamak-based fusion systems, and strengthen the search for 'alternative' options, which could mean more Polywell support.

Realistically, it would be a blow to public confidence for fusion systems. Any and all of them.

Every now and then I mention fusion research to my friends. It's been years since I had one recognize the word "tokamak". These days I hang out with the post-doc in our lab. He didn't know what a tokamak was. Admittedly, his doctorate is in biology, and I've known few physicists. Outside of the physics community, the vast majority of people don't distinguish between different types of fusion.

[TallDave]

I understand that most of the arguments against tokamak fusion is that, if/when we can get it to grid, the device will be monstrously huge,

Plant power density -- they don't produce enough power for what they cost.

What chances are there for a tokamak with a better fuel, like p-b11?

Not much more than zero. I'm doubtful it can be done with PW, let alone with a thermal machine. You need something like a monoenergetic distribution or you might as well not bother because the output won't be aneutronic with all the side reactions in the thermal tail. And then there's brem...

[TallDave]

I am saying that iter is the best shot we have at showing net fusion energy is possible by humans

Sorry, I'm a capitalist whore. I don't care if it's possible, I care if it's economically sensible.

I might feel differently if we didn't have 1,000 - 250,000 years of fission fuels. There's no rush. If PW doesn't work by 2100, maybe we can try ITER then, when world GDP is probably around $100K/person.

[AcesHigh]

the website from the link in the first post seems to be offline...

Works for me. Maybe your ISP has a faulty DNS table or something.

"Forbidden
You don't have permission to access /archives/2010/06/iter_meltdown.html on this server.

Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request. "

[Giorgio]

Iter has science behind it. So far polywell has hopes and dreams. Take note, iter cancellation would be a bad thing, not a good one.

ITER still needs to have some basic aspects to be understood and/or investigated before we can even hope that it will work, let alone to give a net power result.
Truth is that there are so many aspects that we still need to understand about fusion that we might fill a couple of books just to list them.
Add to this that every time we finally understand a new piece of the puzzle it will change the configuration/equipment/structures of ITER, and you have a big mess in your hands.

To make a good comparison, is like if we try to build a Scramjet plane without before having built and undestood all the physics underlying jet airplanes.

I mean, they still have to understand how to solve a very basic problem like ELM issues and yet they are starting already to build that thing. This is not science, this is just nonsense.

[kcdodd]

ELM control has been shown in experiment already. The old saying comes to mind, insanity is doing the same thing over and over and expecting a different result. The problem is every time the same thing is done you DO get a different result. I think the fact that every tokamak reacts differently to what seems to be the same methods has been a huge thorn in research. Understanding those differences in every regime has opened whole areas of knowledge about plasmas, as well as time on the road to fusion power.

You can argue that the knowledge gained from iter is not worth the monetary cost. That is fine. But saying you shouldn't build iter because we don't know enough is just silly. How are you to ever understand the physics of plasmas at break even unless you do it.

[Giorgio]

ELM issues are far from being solved, for now we have "proposed" solution that will have to be tested in ITER. Problem is that it will be almost impossible to retrofit ITER in a suitable way to test ELM control solution, becouse it was designed without even knowing the existance of ELM issues.

http://www.psfc.mit.edu/~g/spp/WhitePap ... ontrol.pdf

A significant international design effort is currently underway to retrofit ELM suppression coils into the ITER design to mitigate the divertor erosion expected from ELMs. Since these coils will be constrained to fit within the existing ITER design envelope it is unlikely that we will be able to optimize the design to comply with our best understanding of the physics of ELM suppression.
Though not fully optimized, use of the ITER ELM suppression coils will provide an important test of the compatibility of ELM suppression with obtaining high fusion gain.

My point is not that we have to stop ITER research, my point is that we have to stop ITER construction.
We should take a step back and invest more in laboratory research of ITER fusion physics and alternate fusion methods and get a clear understanding of it before attempting to build something so huge.

[kcdodd]

Problem is that it will be almost impossible to retrofit ITER in a suitable way to test ELM control solution, becouse it was designed without even knowing the existance of ELM issues.

ELMs have been known for thirty years ever since H-mode was discovered, by shear accident I should add. They are only relevant on iter because of the shear amount of energy in the plasma. There is no point to study them unless you are applying it to something the size of iter. And there is no way to know if what you suppose will work, actually will work, unless you actually apply it to something the size of iter because of possible scaling issues. I would also add there are simple "we just don't know" questions that can ONLY be answered by iter, such as high energy particle instabilities. If we knew everything already, or if there were a way to find them out with current sized tokamaks, there would be no point in building iter. We would just build DEMO.

[Giorgio]

ELMs have been known for thirty years ever since H-mode was discovered, by shear accident I should add.

Do not mix the discovery of H-Mode and ELM with the acceptance and understanding of ELM from the international community.
It was not until the W7 experiments that the scientific comunity started to accept that the H-mode and the corresponding ELM was an intrinsic feature of all the toroidal design type reactors.
This inertia (which is typical of most research fields IMHO) allowed the ITER to be designed without ELM control solutions.

And Again, I agree that some answer can only be obtained by "building" something to test them. I do not agree that we have to build ONE single machine to answer all of them while we can test the majority of these issues in single experiment in the labs.
As you mentioned H-mode, do you realize that we do not understand yet exactly what the physics behind the H-Mode is?
Yet we trying to scale it up to something the size of ITER...

[KitemanSA]

I mean, they still have to understand how to solve a very basic problem like ELM issues and yet they are starting already to build that thing. This is not science, this is just nonsense.

ELM? Extremely Lousy Machine?

[MSimon]

the website from the link in the first post seems to be offline...

Works for me. Maybe your ISP has a faulty DNS table or something.

"Forbidden
You don't have permission to access /archives/2010/06/iter_meltdown.html on this server.

Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request. "

I'd say your problem was your ISP and a misconfigured DNS table.

[MSimon]

It seems irresponsible to me to design ITER without out even a PROPOSED ELM solution.

A fookin retrofit? Give me a break.

[kcdodd]

You made it sound as though ELMs where unknown and the result of slap shot research. Of course they are not fully understood, but they are known of.

There are several proposals for elm control MSimon. I only know of the resonant coils actually shown to work. Not sure of the other methods.