Have you heard about the French Fusion Reactor?

[Xilus]

Homework Statement:: French Fusion Reactor
Relevant Equations:: F=ma

Hey anyone here working on the French Fusion reactor? Heard about it over the radio.

ITER

just been reading the annual reports from CERN. Kind of a fun read if you haven’t read it yet.

 

[etudiant]

Have visited the place, it is an example of a multinational program where there is no need for a success, the funds will keep coming.
Desultory work schedules and delays measured in decades, not years, are the characteristics of ITER.
Imho, the prospects for a private fusion effort achieving success ( see https://cfs.energy/ ) are much higher than those for ITER. The analogy of SpaceX versus the established launch services is apt imho.

 

[MisterX]

Have visited the place, it is an example of a multinational program where there is no need for a success, the funds will keep coming.
Desultory work schedules and delays measured in decades, not years, are the characteristics of ITER.
Imho, the prospects for a private fusion effort achieving success ( see https://cfs.energy/ ) are much higher than those for ITER. The analogy of SpaceX versus the established launch services is apt imho.

or perhaps a different publicly funded effort - ITER is already obsolete due to advances in superconductor technology that has happened during its very slow schedule. Now high temperature superconducting (HTS) wire permits construction of a more cost effective tokomak with higher fields. One may have a look at the proposed 'ARC' or 'SPARC' reactors for example which originate at MIT. ITER seems to suffer from slow schedule and work that is divvied up among many locations for political rather than practical reasons.

 

[MykolaBorysiv]

or perhaps a different publicly funded effort - ITER is already obsolete due to advances in superconductor technology that has happened during its very slow schedule. Now high temperature superconducting (HTS) wire permits construction of a more cost effective tokomak with higher fields. One may have a look at the proposed 'ARC' or 'SPARC' reactors for example which originate at MIT. ITER seems to suffer from slow schedule and work that is divvied up among many locations for political rather than practical reasons.

ITER is the research project without any positive power output for external users. The MIT projects you mentioned are also the research projects. Even more: SPARC is the moderate size tokamak with practically the same physical background as JET, JT-60, D-IIID and ASDEX-U. The difference is only somewhat advanced technologies. The expected fusion gain in SPARK is Q <= 2, while ITER had designed for Q > 10.

Many experts believe that tokamaks are useful only as research devices, for accumulation of necessary knowledge and development of technologies. But the real reactor can be built only on the base of stationary machine. As first candidate is the stellarator.
Wendelstein 7-X - Wikipedia
Upgrade Work Enters New Phase For Germany’s Wendelstein 7-X :: The Independent Global Nuclear News Agency (nucnet.org)

 

[Vanadium 50]

Now high temperature superconducting (HTS) wire permits construction of a more cost effective tokomak with higher fields.

While I am highly critical of ITER, this is not a fair criticism. There is no way you can build a tokamak with HTS magnets today, or any time soon. You can get a little bit of wire commercially, and power leads for more conventional superconducting magnets, but there's no way with today's technology you're going to make a tokamak's worth of magnet coil.

ITER uses tens of thousands of miles of conductor. At any given time, there is maybe 300 meters of HTS wire for sale. With multi-month or multi-year delivery times.

 

[mfb]

How much wire would HTS-ITER need vs. FCC or HE-LHC?

 

[MisterX]

While I am highly critical of ITER, this is not a fair criticism. There is no way you can build a tokamak with HTS magnets today, or any time soon. You can get a little bit of wire commercially, and power leads for more conventional superconducting magnets, but there's no way with today's technology you're going to make a tokamak's worth of magnet coil.

ITER uses tens of thousands of miles of conductor. At any given time, there is maybe 300 meters of HTS wire for sale. With multi-month or multi-year delivery times.

That is interesting. I was not aware of these production limitations. I was aware of various demonstration projects from over a decade ago which were a few hundred meters in size. One is quoted as employing 155,000 meters of wire [1]. A this is still 2 orders of magnitude shorter than the requirements you cite, and of course all wires are not the same. I am was not fully aware of the cabling requirements for producing tokomaks in detail. If what you say is true then I suppose there has not been massive improvement in production capabilities in these intervening years. It was conceivable to me that making a very large amount could alter the economics as well. What are the difficulties in manufacturing this wire and why is it difficult to scale up production vs. conventional options?

[1] http://www.jicable.org/2007/Actes/Session_A3/JIC07_A34.pdf

 

[MisterX]

How much wire would HTS-ITER need vs. FCC or HE-LHC?

This is an interesting question and I'd love to see someone knowledgeable chime in here. I wasn't able to find out, but I did find this table of target parameters they have for the Nb3Sn type II superconducting wire for HE-LHC.
It's mentioned in this paper from about 2 years ago that "the initiative is also a first step in the direction of preparing the ground for a credible large-scale supply chain at global scale."

(2019). HE-LHC: The High-Energy Large Hadron Collider. The European Physical Journal Special Topics. 228. 1109-1382. 10.1140/epjst/e2019-900088-6.

 

[Vanadium 50]

How much wire would HTS-ITER need vs. FCC or HE-LHC?

FCC and HE-LHC are being designed to use Nb3Sn magnets,, not HTS, So "infinity".

What are the difficulties in manufacturing this wire

To start, it's not wire. It's grey dust. (REBCO, BSCCO, YBCO, it's all dust.) Forming that into something that carries current is far from trivial, and doing so for hundreds of miles without a bad spot even less so. That's why you see HTS in power leads: it's only got to work for a couple meters, and since one end is warm, high Tc is at even more of a premium than for SC magnets.

Also, high Tc isn't the whole story. MgB2 has a Tc of 39K, but even at 4K doesn't do any better than NbTi as far as supporting a large magnetic field. (Today - that may change. But it is too soon to plan on using it)

 

[mfb]

FCC and HE-LHC are being designed to use Nb3Sn magnets,, not HTS, So "infinity".

Conceptual design of 20 T dipoles for high-energy LHC

To reach 20 T, HTS conductors capable to carry 400 A/mm² at 15-20 T under transverse stress of 150-200 MPa are an essential element.

https://fcc.web.cern.ch/Pages/Magnets.aspx
More FCC HTS

I don't know if they made a final decision for either option now. Sure, you can go with Nb3Sn alone and it's cheaper, but if they think about a 20 T option then they expect (or expected in the past) that you can get enough HTS for the ring.

It's not something that would have been available for ITER, of course, and the cost is still a big issue. Maybe something for DEMO, maybe not.

 

[Vanadium 50]

Sure, but even in the Rossi article, only 25% of the field comes from HTS, and this is presented as maybe a way to get past 16.5 T. This is a far from a done deal, and as you say, nowhere near ready for ITER. If we can't do it today, we certainly couldn't do it when ITER was baselined.

Some history may be in order to set expectations. It was fifty years between the discovery of metal superconductors are figuring out NbTi was what you wanted to use, and almost another 20 before we understood how to make NbTi magnets on an industrial scale. Cuprate superconductors were discovered in the mid-1980's.

As I said, ITER provides a lot of target space for criticism, but this is not part of it.

 

[cmb]

I believe there are still questions whether HTS and compact spherical tokamaks are necessarily 'an answer' to ITER or just another hoped for approach.

I believe the issues are that;-
- yes, higher temperature super conduction but only up to certain magnetic field strengths and current densities, which are not sufficient for spherical tokamak specifications, so to get HTS to the current densities to match the older ITER superconductors, they basically need to be at pretty much the same temperatures, or at least much below liquid nitrogen, which rather makes the benefits less clear
- yes, all good these compact spherical tokamaks (also not forget UK's 'STEP' programme, UK Gov/public money throwing cash into that programme to try to beat those private ones) but ITER, despite its massive size, will already be struggling with the specific wall loading powers and the materials to deliver that are already at their limit, and these little guys are claiming to be generating something similar to ITER but with a chamber wall area of percentage points of ITER, so what unobtanium alloy materials will those walls be made of?

I think ITER exists as a design because of specific engineering constraints only partially because of the constraints of the super conductor magnets. There is probably a lot more to why these things need to be big than just the magnetic field.

I'm hoping others can chime in on these observations.

To the OP ... heh, yeah ITER has been around as a concept for several decades, glad you're catching up now, there is a ton of literature out there to catch up on, should keep you busy reading for several months.

 

[mfb]

There is probably a lot more to why these things need to be big than just the magnetic field.

Volume to surface ratio. Fusion power vs. energy loss.
Smaller magnets would be easier to make, but the larger volume to surface ratio of ITER will help a lot.

 

[f95toli]

One thing that is perhaps not obvious is that the superconducting properties of the material you are using is only the start. Even you had access to a unlimited length of HTS superconducting wire it is not at all obvious that this can then be used to make good magnets. There are many other considerations including the mechanical and thermal properties of the wire and they are not set only by the superconductor but also of the other materials used to make the wire. and some of them will limit the effective Jc (defect density, how well you can cool magnet, what happen when you quench the magnet...)
Low-Tc magnets have been around for a very long time and the engineering is well understood but high field HTS magnets are -relatively speaking-a new technology.

You can also flip this around: Niobium-tin superconductors are very rarely used for anything BUT wires even though it has a very high Tc for a LTS superconductor. This is because it is very difficult materials to work with and its other properties are horrible .
Niobium-nitride and Niobiuim-Titanium and Nibium-Titanium-nitride are much more common.

 

[epenguin]

Homework Statement:: French Fusion Reactor
Relevant Equations:: F=ma

Hey anyone here working on the French Fusion reactor? Heard about it over the radio.

ITER

just been reading the annual reports from CERN. Kind of a fun read if you haven’t read it yet.

Wrong to call it French - it is European and International.

Weird to read you link to ITER and jump to CERN like it was the same thing.