* Posts by nemecystt

22 publicly visible posts • joined 13 Jul 2021

Peter Higgs, daddy of the Higgs boson, dies at 94

nemecystt

Serendipity

I still find it one of the most remarkable coincidences in physics history that it was Peter Higgs who discovered the Higgs Boson. Almost like pre-destiny. I mean, Watt are the odds?

England's village green hydrogen dream in tatters

nemecystt

Re: Well, duh

I'm not batting for hydrogen here, just pondering remote possibilities.

Suppose the UK goes all-in on (mostly air source) heat pumps then a few years down the line the ongoing climate change issues lead to a major change in the AMOC. That could get messy...

Lawrence Livermore lab repeats fusion breakthrough – yep, still kinda works

nemecystt

Re: A question

Circa 300MJ

nemecystt

Re: And then what?

I agree that NIF is a terrible approach for power production. Your comments regarding Tritium breeding are off though. At least in theory. Test modules at ITER are planned for this, and a number of the private companies in this space will be getting to that stage in the next few years (probably before ITER). Beryllium or Lead can be used as a Neutron Multiplier (one in, two out kinda thing) and closed cycle gain of around 1.2 is predicted.

UK's dream of fusion power by 2040s will need GPUs

nemecystt

Re: The problem is, it is just another heat engine

Surely you can put some numbers on this with back-of-the envelope calculations. You don't need to set up that experimental road, or even use a GPU. What is the per square km heat output of human activity on average? How does it compare with the per square km insolation from the Sun? Genuine question.

Microsoft and Helion's fusion deal has an alternative energy

nemecystt

Re: It's a sure thing

Oh, and the issues with high energy neutrons aren't just activation of reactor vessel materials. There's also blistering and embrittlement of materials over time. Besides the structural elements, Helion will have to replace their electromagnetic coils fairly frequently. They are very close to the reactor "core" and they are taking quite high forces. Their conductivity will start to suffer first and then, ultimately, their structural integrity too.

nemecystt

Re: It's a sure thing

Regarding your other question about production of 3He, there are 3 sources.

Fusion of Deuterium with itself has 2 outcomes of equal probability: Tritium and a proton, or 3He and a neutron. So they can use their reactor design, if it really works, with DD fuel and then refine / separate the outputs. This is likely to be a net negative power reactor, so the secondary D-3He reactor that follows not only has to break even on its own, but also make up for that pre-processing loss.

They can sell the Tritium to other fusion companies, or sit on it and wait for it to slowly decay into 3He (12 year half-life). That's the second way to source 3He. They could procure Tritium (difficult and super expensive) and wait for it to decay. Tritium is currently produced in very small amounts in specially prepared fission reactors and is proposed to be self-generated / recycled in some future fusion reactors not of the Helion design. Both of these require 6Li and neutrons.

There's more 3He on the Moon than on Earth (or at least we think it will be more easily procured there). However the efficiency of mining the Moon for resources to use back on Earth is rather questionable, not to mention many, many decades away. This is the only source which does not require machinery to endure a high neutron flux. Just cosmic rays...

nemecystt

Re: Build SMRs instead

The trouble is scaling renewables and storage to cover everything including transport and industrial heat, not just domestic 'leccy just wont cut it without killing the planet with mining. There has to be a mix of carbon-free sources, some of which are immediately despatchable and can also be 24-7. Then there's the issue of bringing the third world and others up to the living standards us lucky few enjoy. Some kind of nuclear has to be in that mix. I don't see any alternative, besides perhaps space based solar, but that's another huge can of worms and isn't secure.

nemecystt

Re: It's a sure thing

Unfortunately, that's not how two plasmoids rammed together and magnetically confined behave. Think of it more like a bunch of angry bees and a bunch of angry wasps in a small chamber. Bees will collide with bees as much as bees collide with wasps. They're whizzing all over the place, bouncing off each other and steered by magnetic fields. It is not a one-shot head-on collision at all.

nemecystt

Re: Erm...

With respect, have you researched Helion's process using sources of info other than Helion?

The 3He production from D-D is neutronic.

Further, D-D side reactions (neutronic) are unavoidable in any 3He-D bult plasma/plasmoid at 100 million Kelvin. Just look at the respective fusion cross-sections.

There is even the possibility of residual Tritium (you'll not evacuate it all between pulses), formed in the D-D side reactions then giving you some D-T fusion too. This means more neutrons, and higher energy ones at that.

nemecystt

Re: It's a sure thing

The process is not aneutronic. D-D side reactions are unavoidable at the energies needed to get the D-3He reaction to work.

The 3He production process is also not aneutronic.

Problems.

Big problems with regulation and longevity.

However, unlike other approaches, the temperature issue is lessened. They are doing small scale repeated pulses. That should be easier to manage.

Since humans can't manage fusion, the US puts millions into AI-powered creation

nemecystt

All green of skin... 800 centuries ago, their bodily fluids include the birth of half-breeds. For the fundamental truth self-determination of the cosmos, for dark is the suede that mows like a harvest

nemecystt

Re: Nothing new.

Oppenheimer and others had concerns that the nuclear *fission* bombs might cause a propagating chain *fusion* reaction (of hydrogen and nitrogen in the atmosphere and hydrogen in the oceans). Oppenheimer tasked Hans Bethe and others to calculate if this was actually possible. They concluded it was not. Indeed no A-bomb or H-bomb ever ignited the atmosphere.

If it was that easy, without confinement, we would have had fusion power stations decades ago.

The plasma in a tokamak is really not very dense. There are just a few grams of deuterium and tritium in there at any one time. Magnetic confinement is required to try to keep the plasma from melting or vaporising tiny holes in the first wall of the vacuum vessel, and to try to squeeze the plasma more tightly to increase the fusion rate. It is not necessary to prevent a chain reaction. Controlled fusion very rapidly fizzles if the conditions drift even slightly away from optimum.

You really don't need to worry about a Tokamak, or similar, turning into a nuclear bomb.

nemecystt

Re: Nothing new.

Do you have any reliable sources / references for this thermodynamics defying trick that you allude to regarding cavitation? There have been a lot of "woo" / fraudulent claims in that sphere over the years. Although there are (flawed) patents going back to the 70s claiming to be able to use it to enable fusion break even, I don't think I have seen anything convincing about cavitation in and of itself being an energy source, merely an energy concentrator or possible route to more efficient steam generation. Thanks in advance.

nemecystt

Re: Nothing new.

The sonoluminescence from the cavitation elicited by the pistol shrimp does indeed include the creation of a plasma, and fusion would not be absolutely out of the question, but the probability would be vanishingly low for even one fusion event, given the "triple product" we could infer from the conditions and the "fuel" species present.

Nevertheless, the pistol shrimp is the inspiration for First Light Fusion in Oxford. Their approach is all about focusing and amplifying shockwaves initiated by a physical projectile.

nemecystt

Re: Nothing new.

No disrespect, but if you knew what you were looking for then your google-fu needs a workout. Google search did used to be much more powerful and targetable than it is now, sadly, but you can still reduce the greediness of its matching by using quotation marks. Search for "Sail" "Stanford", for example.

Miniature nuclear reactors could be the answer to sustainable datacenter growth

nemecystt

Re: Waste not want not

In terms of fusion fuel, sure: less mass than you would need fission fuel for the same output. If you were fusing Deuterium and Tritium and had a closed loop Tritium cycle via a Lithium breeding blanket, you could stockpile enough Deuterium and Lithium and your Tritium seed load.

With a "solid first wall" reactor vessel you are probably going to have to do some maintenance well before 5 years though. There are some liquid first wall ideas out there like First Light and General Fusion which, if they can be made to work, would massively extend your maintenance intervals.

But I am not sure why the need for a sealed, set-and-forget fusion reactor. The materials and radiation levels involved are nowhere near as monster evil bogeyman as in fission reactors, and the nuclear proliferation issue is pretty much non-existent too.

We're straying further off the topic of the article now though.

nemecystt

Waste not want not

The issue of SMRs creating 30 times the waste of a gigawatt scale power station is, perhaps, ameliorated by two future factors:

1) some gen 4 fission reactor proposals can be run from the waste from these SMRs and older plants. Overall the amount of net waste at the end goes down

2) fission may only be a relatively short-lived "bridge" now until the boffins get fusion to work properly and at commercial scale

Public and private investment is pouring into Fission both large scale and small modular on both sides of the Atlantic, but especially in the US. Similar can be said for fusion research.

I don't think we have a flotilla of energy Theranoses about to run aground out there. Investors are a little more scrutinising these days and while many startups may be chasing pipe-dreams, a few will eventually succeed.

NASA uses space station dust sensor to map 50 methane 'super-emitters' on Earth

nemecystt

Sorry to be a party pooper but

The jokes about cow farts fall rather flat(ulent). Methane doesn't come out of the back end. It's a bovine burp thing, people. Plus, by itself, methane is odourless. Which is why they need the fancy IR satellite thingummy and not just a horde of roaming noses. Sorry to have caused such a stink.

Arms not long enough to reach the plug socket? Room-wide wireless charging is on the way

nemecystt

Re: Inverse square law

Inverse square law applies to a single point source. Multiple plates on multiple walls gives you quite a different result. Consider the electric field between the plates of a capacitor. Besides the fringing around the edges, it is uniform.

NASA signs $1bn deal with Northrop Grumman to build studio apartment in lunar orbit with room for 3 vehicles

nemecystt

Look up "mascons"

nemecystt

Orbital decay also happens with fairly close Moon orbits because of "mascons" - irregular concentrations of mass within the Moon. This was learned fairly early on in the Apollo program.