Although nuclear fusion is exceedingly easy to achieve, as evidenced by desktop fusors, the real challenges begin to pop up whenever you try to sustain a plasma for extended periods of time, never mind trying to generate net energy output. Plasma instability was the reason why 1950s UK saw its nuclear fusion hopes dashed when Z-pinch fusion reactors failed to create a stable plasma, but now it seems that another UK fusion reactor is one step closer to addressing plasma instability, with the MAST Upgrade tokamak demonstrating the suppressing of ELMs.
ELMs, or edge localized modes, are instabilities that occur at the edge of the plasma. A type of magnetohydrodynamic instability, ELMs were first encountered after the switch to high-confinement mode (H-mode) to address instability issues encountered in the L-mode operating regime of previous tokamaks. These ELMs cause damage on the inside of the reactor vessel with these disturbances ablating the plasma-facing material.
One of the solutions proposed for ELMs are resonant magnetic perturbations (RMPs) using externally applied magnetic fields, with the South-Korean KSTAR tokamak already suppressing Type I ELMs using this method in 2011. Where the KSTAR and MAST Upgrade tokamaks differ is that the latter is a spherical tokamak, different from the more typical toroidal tokamak. As the name suggests, a spherical tokamak creates a sphere-like plasma rather than a doughnut-shape, with potential efficiency improvements.
All of this means that the MAST Upgrade tokamak can continue its testing campaign, as tokamaks around the globe keep trying to hit targets like the Greenwald Density Limit and other obstacles that stand in the way of sustained net energy production. Meanwhile stellarators seem to be surpassing one milestone after another, with the German Wendelstein 7-X being the current flagship project.
Top image: Inside MAST Upgrade, showing the magnetic field coils used to control ELMs. Credit: United Kingdom Atomic Energy Authority
Caution: As employed by the experimenters the phrase ‘net fusion energy gain’ (Q) is based upon a tiny subset of the energy consumed by the facility during the experimental day. Additionally, the value of Q only applies to the brief period of time that the fusion reaction is occurring in pulsed machines, which almost all nuclear fusion energy experimental machines are. Also note that out of over 100 experimental machines experimented on the vast majority have been aimed at plasma dynamics studies with no expectation that they will generate a significant number of fusion reactions. Still, these machines continue to be branded as being ‘fusion reactors.’
This will help keeping the ‘only 30 more years’ target alive for at least another decade!
The fusion constant.
During WW2 it took maybe 5 years from initial napkin sketches to fully functioning reactors and nukes being used to prevent spread of cheap Mazdas and Toyotas. Nuclear fusion has been going on for years yet nothing new happened. Maybe it’s time to admit it was a scam and focus on renewable energy instead?
Using the word ‘scam’ in this context is a bit.. MAGA don’t you think? I mean sure it might not go anywhere in terms of energy, but the people involve I’m sure are feeling they are ‘almost there’ and it’s only for outsiders that look at the overview and conclude that seeing the time and money spent we can conclude it won’t end up as a power source.
And we do learn about high energy plasma and containment of course, which in the end might be useful and lead to being useful for other energy sources not yet here. Or maybe it’ll become a great smelting device for future materials, who knows.
But yeah for energy the renewables are good, although I worry about overuse there too, if we massively go geothermal for instance won’t we create local cool spots that then lead to earth tremors or climate effects (due to cooler ground over large areas) or something? And massive wind won’t it affect low level air movement in large areas if we go full out? I mean we have seen it with fracking and gas retrieval that it can cause issues with the stability of the ground and groundwater and such. I just think anything supermassive should be done with some forethought, even with renewable energy.
Oh and surely the nukes more likely created the cheap mazdas and toyotas, I don’t think there would have been a big capitalistic global market for Japan if they would have won or broken even with a permanent truce. But it’s all pure guessing.
“Using the word ‘scam’ in this context is a bit.. MAGA”
Questioning the tangible benefit of sinking billions of dollars (of other people’s money), decade after decade, into an effort that has yet to produce any practical benefit, is not “MAGA.” It’s simply a thought process routinely exercised by any responsible adult who earns his own money and lives within his means.
For the record, I’m pro-science and, in principle, supportive of fusion research. But a fusion expert of no less stature than Robert Bussard himself said years ago that though Tokamak produced “interesting science”, it would never result in a viable energy source. Was he “MAGA” too?
Considering some of the other things Bussard has said over the years I’m less inclined to accept his opinion without question.
So Bussard you “question,” but billions of dollars spent with no deliverables, you don’t?
Got it.
@Observer
Nice try. You known perfectly well that’s not what I said :)
scam
noun informal a dishonest scheme; a fraud.
verb (scams, scamming, scammed) swindle.
Scam implied a deliberate fooling by people who know they are fooling you.
And the MAGA crowd and dɯnɹʇ has the tendency to call anything they disagree with a scam or deliberate fraud to rile up people and make it seem ‘they are after you’.
So saying it’s a folly and it won’t be an energy source does not make you MAGA, but implying it’s all a big fraud to knowingly swindle you does sound very MAGA-like.
And incidentally they very often basically say all science is a swindle and just a way to get money, to justify their anti-science stance I suspect. And if you believe the same you are in my words ‘a bit MAGA’.
And I don’t think you are that type, I think you just used the wrong word when you said ‘scam’, because it’s a popular word I think and is one that easily pops in the mind because of that.
Just focus on proven fission technology.
Why “focus” at all? It’s not like there’s only one nuclear physicist who keeps getting distracted by fusion.
There is a finite budget though.
Yes and no. First, it really is on a positive trajectory even with all of the failures. One problem after another is being understood and then (perhaps partially) solved. At the end of the rainbow, there really is a pot of gold. It’s anyone’s guess how long it’ll take to get there but it seems likely that we’ll get there eventually and develop a whole new attitude towards the cost of energy.
But on the other side, we’ve got a crisis in our western society where everything is being financialized and all production is being replaced with class reproduction. People’s worth is measured by their employment, and physicists (and technicians) are no exception. They gotta eat and they gotta keep up with the Joneses. So there is, throughout academia, a trend of make-work. Where getting the grant is more important than getting the result. Where adding more people onto your team is more valuable than increasing its effectiveness. Published papers with thousands of authors, each one of which is measuring their career success with the number of papers with their name on it. Where the unpredictability of breakthrough research isn’t as desirable as the steady march of predictable progress.
No one’s blind to this. Even the people who are participating in it most eagerly are also wringing their hands about it and saying maybe we should be chasing smaller more risky experiments instead of mega-projects. No one really knows the best thing to do on any front. But it’s definitely in a certain unstable position today.
It is kind of like cancer research ,some success and some failures. But like everything else humans do they keep on pushing the limits.
Good comparison! There aren’t many easy questions left unanswered today and the tough ones take some time to be solved.