ITER and all things fusion.

[KerbonautInTraining]

Sorry for the thread revival but I recently discovered how (seemingly) close we are to fusion energy. 

Like, before now I assumed that we haven't managed fusion on earth at all.

So, a few questions. The reactors we have now, what's stopping them from producing power? Are they not efficient enough? Or is it like scientific fission reactors where the energy just isn't harvested?

Also how would we go about extracting energy in our first fusion power stations? Running coolant through the walls and using heat radiated from the plasma?

[Fusion hype intensifies]

Edited May 4, 2016 by KerbonautInTraining

[SargeRho]

@KerbonautInTraining

I'm going to go off of the Tokamak design, since it seems to be the most common one.

From what I understand, current Tokamaks are simply too small, and as a result, can't compress the plasma strongly enough to produce Fusion. ITER is humongous for precisely that reason. And, of course, we haven't built any fusion generators yet, all reactors currently and formerly in operation are research reactors, built to test all sorts of aspects of fusion, except power generation. Tokamaks would probably heat water to run through steam turbines. Other reactors can extract energy directly from the fusion products.

Edited May 4, 2016 by SargeRho

[wumpus]

58 minutes ago, KerbonautInTraining said:

Sorry for the thread revival but I recently discovered how (seemingly) close we are to fusion energy. 

Like, before now I assumed that we haven't managed fusion on earth at all.

So, a few questions. The reactors we have now, what's stopping them from producing power? Are they not efficient enough? Or is it like scientific fission reactors where the energy just isn't harvested?

Also how would we go about extracting energy in our first fusion power stations? Running coolant through the walls and using heat radiated from the plasma?

[Fusion hype intensifies]

First artificially produced fusion was at the bikini atol in 1954 (first H-bomb test).  This produced a ton of power in ways that weren't obvious how to harness it.

Basically the problem is that fusion requires extreme amounts of heat and pressure (the pressure is likely the killer.  Especially considering it can't be applied by any form of matter).  You spend x amounts of watts providing the heat and pressure to produce enough fusion to generate y amounts of energy.  My understanding was that for sufficiently generous accounting, this had been done in a net positive (googling implies that might not be true), but only counting "energy in" in terms of energy directly received by the plasma (i.e. ignoring all the losses in the devices providing said energy.  Be really glad if it is over 5% from power generator to plasma) and energy out in terms of actual heat produced.  Although this end is largely a solved problem (because it is critical to all electricity production) and is largely limited by that pesky Carnot efficiency (which defines the most power you can get out of heat under any conditions).

In the end you will probably need a few orders of magnitude of improvement before there is sufficient economic justification to build a fusion power plant (for production and not research purposes).  Also expect to have pesky neutrons irradiating plenty of the plant (fusion *always* makes neutrons.  Lack of neutrons was the giveaway that "cold fusion" wasn't fusing).  In the end, you might wonder why you didn't just do a little research on how to make safer fission plants.

[PB666]

1 hour ago, KerbonautInTraining said:

Sorry for the thread revival but I recently discovered how (seemingly) close we are to fusion energy. 

Like, before now I assumed that we haven't managed fusion on earth at all.

So, a few questions. The reactors we have now, what's stopping them from producing power? Are they not efficient enough? Or is it like scientific fission reactors where the energy just isn't harvested?

Also how would we go about extracting energy in our first fusion power stations? Running coolant through the walls and using heat radiated from the plasma?

[Fusion hype intensifies]

This is closed time-like curved thread you can post in it anytime, future, past . . . . .

What stops them from producing power is they are proof of principle reactors, not designed to sell power, but to guide how best to design future reactors.

[Nuke]

the reason fusion is always 20 years away, is that is because thats how long it takes to fund, build, shakedown, and test a tokamak. the reason its always recurring is there is always someone building another tokamak because they went as far as they could go with the previous iteration. tokamaks really suffer from their size and complexity and it really slows down the scientific process. the only reason we keep using them is that they are the most well understood method right now.

but the competition is catching up. eventually we will get to a point where building more tokamaks is pointless. once you can say something like dpf or polywell is equivalent to the current state of tokamaks, and you have to choose which to fund. will you fund the one that costs 100 billion or the one that costs 100 million? eventually we will stop putting all the eggs into the same donut shaped basket. polywell will be tokamak equivalent when it achieves wiffleball. dpf currently has some plasma contamination issues to resolve. and those are just 2 examples of things that have the potential to outperform tokamaks.

[James Kerman]

I've been reading this thread with great interest (and limited understanding) and I was wondering what your thoughts were on Lockheed Martins' T4?

Edited May 5, 2016 by James Kerman

[KSK]

21 hours ago, wumpus said:

First artificially produced fusion was at the bikini atol in 1954 (first H-bomb test).  This produced a ton of power in ways that weren't obvious how to harness it.

Allow me to tip my hat to a true master of understatement.

 

[Emperor of the Titan Squid]

What about Lockeed MArtin?

[Nuke]

i dont think ive seen a photo of lm's machine with a plasma ball in it yet. so im gonna have to conclude that they haven't even fired a shot with it yet. of course they are being very tight lipped.

Edited May 6, 2016 by Nuke

[PB666]

On 5/4/2016 at 8:42 AM, SargeRho said:

@KerbonautInTraining

I'm going to go off of the Tokamak design, since it seems to be the most common one.

From what I understand, current Tokamaks are simply too small, and as a result, can't compress the plasma strongly enough to produce Fusion. ITER is humongous for precisely that reason. And, of course, we haven't built any fusion generators yet, all reactors currently and formerly in operation are research reactors, built to test all sorts of aspects of fusion, except power generation. Tokamaks would probably heat water to run through steam turbines. Other reactors can extract energy directly from the fusion products.

The stellarator like https://en.wikipedia.org/wiki/Wendelstein_7-X are  designed to get around this by

Quote

It aims for a plasma density of 3×10²⁰ particles/cubic metre, and a plasma temperature of 60–130 million K.^[1]

 

Quote

More than 300 discharges with helium were done in December and January with gradually increasing temperatures finally reaching six million degrees, to clean the vacuum vessel walls and test the plasma diagnostic systems. Then on 3 February 2016, operational phase 1 (OP-1) began, with production of the first hydrogen plasma to initiate the science program. A 2 MW microwave pulse resulted in a plasma temperature of 80×10⁶ K, with a lifetime of ¼ second, fulfilling all expectations. Such tests are planned to continue for about a month, followed by a scheduled shut-down to open the vacuum vessel and install protective carbon tiles lining the vessel, and a "divertor" for removing impurities from the plasma. Then the science program will continue while gradually increasing the power and duration of the discharges.^[17]

 

[James Kerman]

On ‎6‎/‎05‎/‎2016 at 5:24 AM, Nuke said:

i dont think ive seen a photo of lm's machine with a plasma ball in it yet. so im gonna have to conclude that they haven't even fired a shot with it yet. of course they are being very tight lipped.

The article I read stated they had performed over 100 test shots at very low power (1KW).

[StrandedonEarth]

Well, the thread title includes “all things fusion,” so this thread seems to be the best fit for this different approach to fusion. So excuse this bit of necromancy....

This approach does seem to avoid at least one of the issues with magnetic confinement designs...

Spoiler

Quote

General Fusion’s Magnetized Target Fusion system uses a sphere filled with molten lead-lithium that is pumped to form a vortex.  A pulse of magnetically-confined plasma fuel is then injected into the vortex. Around the sphere, an array of pistons drive a pressure wave into the centre of the sphere, compressing the plasma to fusion conditions. This process is then repeated, while the heat from the reaction is captured in the liquid metal and used to generate electricity via a steam turbine.

Advantages of General Fusion’s Approach

 

 

Liquid Metal Wall

 

 

 

A major practical advantage, the liquid metal wall absorbs energy from the fusion reaction which can then be pumped to heat exchangers. The liquid metal also protects the solid outer wall from damage, and can be combined with liquid lithium to breed tritium within the power plant.

Compressed Gas Driver

 

 

 

Using practical, existing technology, steam powered pistons compress the plasma to fusion conditions. Not requiring the exotic lasers or giant magnets found in other fusion approaches, steam pistons can be practically implemented in a commercial power plant.

No Consumables

 

 

 

The compression target is comprised only of magnetized plasma (fusion fuel), which does not need to be manufactured and is effectively cost free.

 

 

[benzman]

looks to me like the Diesel principle taken to extremes.

 

[StrandedonEarth]

2 minutes ago, benzman said:

looks to me like the Diesel principle taken to extremes.

 

Why yes, it does, now that you mention it. Although the liquid metal vortex is a nifty solution to erosion of the fusion chamber walls, while also working to transfer the heat to the boilers. 

[Nuke]

i do kind of like general fusion's "you are all overthinking this" approach. it also solves the problem of getting heat out of the reactor. the steam to drive the pistons can also be sourced from the secondary water loop, meaning you can operate much of the high energy components directly on the thermal output, hell even the liquid metal pumps could be steam driven. having to convert all that thermal energy to electricity before using it to power reactor components would make the whole thing less efficient. 

then you got my favorite, the polywell. they dont release much information or very often but the last word was they are doing the design work on their demo reactor now, using a lot of really high end supercomputer simulations to optimize and verify the final design. dr bussard just wanted to do a big (if you call 3-meter big) reactor but didn't get the funding before he died. his successor dr park is taking a more conservative route. i kind of which they would do more public outreach. they only seem to come out of the woodwork when they need funding, get it, and then get back to work. and to be fair it likely costs less than iter's public outreach program. 

[Guest]

That's novel, certainly looks like an interesting idea. Pulsed fusion is easier than continuous fusion, so that's certainly a plus. I'm not fond of pulses in propulsion because they create vibrations, but for power generation they should be OK. Of course, this is unlike any fusion device I've ever heard of (barring one very theoretical propulsion system, with lasers instead of pistons), so there might be unexpected complications. They definitely should be doing tritium breeding, too. If they don't put lithium into the liquid metal mix, the thing will be spewing neutrons all over the place.

Polywell tech is still a big unknown because so much around it is classified. I'm afraid that even if it works, it may not make a splash that it should because of the US keeping too tight of a lid on that technology. The "I" in ITER is one really nice thing about it, anything that one achieves will benefit a lot more than just one country.

[IncongruousGoat]

7 hours ago, Nuke said:

the steam to drive the pistons can also be sourced from the secondary water loop, meaning you can operate much of the high energy components directly on the thermal output, hell even the liquid metal pumps could be steam driven. having to convert all that thermal energy to electricity before using it to power reactor components would make the whole thing less efficient.

I think running the steam through a turbine to generate electricity and then actuating the piston using an electric motor would actually be more efficient than trying to just use a steam piston, because steam pistons are a really inefficient way to convert thermal energy into kinetic energy.

To throw some back-of-the-envelope math at it: The efficiency of a typical steam turbine in a power plant is ~40%, the efficiency of an alternator is ~60%, and the efficiency of a 3-phase induction motor is ~85%. This gives us ~20% overall efficiency for the turbine-electric setup. By comparison, the thermal efficiency of a piston-based steam engine seems to (based on some cursory research) max out at around 7-8% for a multiple expansion engine, which probably would get us ~5% for a single-expansion piston. The turbine approach seems like a clear winner, even if I way over-estimated the efficiency of a steam turbine at these scales.

[Elthy]

I kinda doubt they can reach the required pressure with mechanical pistons. The lawson criterium puts a lower bound on the product of pressure (=density), temperature and containment time, the last two cant be very high in this design. The required pressure would be incredibly high, there is a reason they currently use either fission bombs or the worlds most powerful lasers for pulsed fusion.

[Guest]

Actually, pistons are far superior to lasers in generating extreme pressures (see diamond anvil from MetH2 experiments). The problem with them isn't pressure or temperature, but heat. As it happens, most of the heat stays in the liquid metal layer, and the rest should not be sufficient to melt the pistons, especially if their heat capacity is large and they can conduct it away. Aside from that, containment time is short, this being a pulsed fusion device, after all. The liquid metal wall is the big innovation here, though it's not actually that new; this thing is a magneto-inertial fusion drive set up for power generation and with magnets replaced by mechanical pistons.

[Shpaget]

Each cycle you inject some hydrogen, but how do you get the fusion byproducts out of the chamber?

[Scotius]

On 2/20/2020 at 12:01 PM, Dragon01 said:

The liquid metal wall is the big innovation here, though it's not actually that new; this thing is a magneto-inertial fusion drive set up for power generation and with magnets replaced by mechanical pistons.

So, could it be re-set for thrust generation and used as a spaceship engine?

I know, I know - a lot of extra bells and whistles would be needed. Plumbing, magnetic nozzle etc.

[MechBFP]

I am surprised I haven’t seen anything about the Australian aneutronic HB11 fusion reactor design in this thread. Considered “impossible” in 2016, and now apparently not so much.

I’m sure a lot of it is for the PR and funding, but it is an interesting concept none the less.

[Spacescifi]

On 2/22/2020 at 12:43 AM, Scotius said:

So, could it be re-set for thrust generation and used as a spaceship engine?

I know, I know - a lot of extra bells and whistles would be needed. Plumbing, magnetic nozzle etc.

 

Unlikely. The weight budget added would offset the benefits it seems by loweribg overall thrust dramatically.

[Nuke]

17 hours ago, MechBFP said:

I am surprised I haven’t seen anything about the Australian aneutronic HB11 fusion reactor design in this thread. Considered “impossible” in 2016, and now apparently not so much.

I’m sure a lot of it is for the PR and funding, but it is an interesting concept none the less.

i don't expect to see aneutronic fuels coming into play until second and third generation power reactors. you need about 10x breakeven for a viable power reactor, but i think aneutronics need 100x or greater. but they do stand to come with efficiency gains do to the fact you can use direct conversion which might make up for some of the gap there.