Archives for category: fusion power

Fox News recently ran a story on a young boy who seems to have set up a tabletop fuser. Impressive kid. https://www.foxnews.com/science/teen-builds-working-nuclear-fusion-reactor-in-memphis-home

Here is a better article: https://www.commercialappeal.com/story/news/2019/01/28/beifuss-file-memphis-youth-jackson-oswalt-builds-home-nuclear-fusion-reactor/1977266002/

And there is this: http://discovermagazine.com/2010/extreme-universe/18-do-it-yourself-basement-fusion

If deuterium is injected into a 20k- to 50k-volt vacuum, it will ionize and some of it might fuse. If it is fusing, half will result in tritium and a proton, and half will result in helium-3 and a 2.45 MeV neutron. The D-T might fuse to helium with a 14.1 MeV neutron, and the D-He3 can fuse to helium and a proton (but it needs a much higher temperature to matter). Temperatures are near a billion degrees, so too high to imagine. Given a good vacuum, there is nothing to heat except the injected deuterium, and since there is so little of it the extremely high electrical energy input results in extremely high temperature for the very few atoms.

High enough vacuum and high enough electrical energy should make it possible, but I’m skeptical.

Bubble neutron detectors are reported as reliable for a few months after manufacture.

https://inis.iaea.org/collection/NCLCollectionStore/_Public/34/083/34083281.pdf and Youtube videos available. The neutron bubble tubes should bubble only for neutrons (and stray cosmic rays), not x-rays or other likely background radiation.

So, again, it should be doable, and fresh bubble neutron detectors should be reliable, but I remain skeptical.

The bottom line for me, putting a few thousand dollars and oodles of hours into generating a few bubbles in a dosimeter which will remain unconvincing to someone who worked in nuclear fission and fusion science, well, it just isn’t impressive as hobbies go. I do suppose there are very many options that would be more time consuming, more expensive, and less rewarding, so to each his own.

What would convince me would be regular checks of the vacuum equipment with a regular Geiger counter. Once it is reading significantly, then I’d believe you were fusing atoms and generating neutrons that activated your steel. But then, all you have to show for it is a high electric bill and the hassles of disposing of low-level radioactive waste.

Putting together a high-vacuum system is nontrivial.

Detecting protons outside the vacuum chamber is impossible because the chamber walls absorb them. X-rays are plentiful because the ionized deuterium smacking the chamber walls causes x-rays. Nothing nuclear required. So, the only evidence of fusion is neutrons. Given there are reliable ways to detect neutrons, proving fusion isn’t terribly hard, but neutrons with megaelectronvolts energy are true nanocanons. Most of the neutrons produced will be absorbed by the vacuum chamber walls, but many will get through, especially through a viewport. MeV neutrons do extensive damage (on a nanoscale) to anything they hit, including you. Working with the fusion device will give the user significant radiation dose. So, knowledge of useful safety precautions is advised.

Back to the kid who prompted my thinking, his setup is impressive. I’ve worked with such vacuum systems, and the challenges are daunting. A turbopump is a difficult and finicky machine. (It is an electric jet engine working opposite as one does on an aircraft; it sucks instead of pushes.) I know what would be involved with the electrical system, but I’ve never worked with that level of voltage. The young man’s accomplishments are significant. I suspect he has a solid radiation-safety knowledge, too. (And his parents probably did their homework, too.) All in all, good stuff.

Will amateur accomplishments in fusion, in combining deuterium into tritium and helium isotopes, lead to breakthroughs in energy production? I can’t imagine how. It might lead to some technically skilled and ambitious people who do other good things. I’ll stay hopeful.

I’ve seen more news on fusion power generation lately. Among the various claims, a company in Britain seems to think they can run D-T fusion in a tokamak as small as 1.5 meters.

I doubt it. I really doubt it.

D-T is almost certainly what we will use on earth and, perhaps, the moon, and D-T produces material-damaging 14 MeV neutrons. The neutrons also activate the materials, meaning the entire power unit becomes radioactive waste.

A sufficiently small D-T unit may be able to run longer because it will have low structural requirements, but the neutrons embrittle the materials such that the steel (or other material) walls become easy to break, like glass. At some point, the power unit is not structurally sound. It becomes unsafe and must be decommissioned, dismantled, and disposed of as radioactive waste–all of it.

Fusion power of some sort will be the only significant source of power at some point in humanity’s future, but it is not clean and not limitless. That mostly means it will always be expensive with high engineering requirements. It has very significant engineering and safety challenges, including environmental impacts. Granted, most of these challenges are likely to be easier to deal with than other power options, but it is simply false and misleading to suggest that fusion will be clean and inexhaustible.

We will burn fossil fuels for the foreseeable future. (The alternative is mass murder on the order of a billion people.) Nuclear fission will dominate in coming decades, for decades, perhaps for a century or two, then fusion. Once fusion is working, and we overcome the startup and growing pains, then it will be the only significant source of our energy needs for as long as humans do what humans do. I just happen to think generations of us will pass from this earth before the first gigawatt-hour of consumer-electricity is generated by fusion power reactors.

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