Team Confirms UCLA Tabletop Fusion

An anonymous reader writes "A team of New York physicists has confirmed that a tabletop contraption made at UCLA does in fact generate nuclear fusion at room temperatures, using pairs of crystals and a small tank of deuterium. But unlike less reliable reports back in the 1980s, there's no talk this time of producing endless supplies of power. Rather, the technology could lead to ultra-portable x-ray machines and even a wearable device that could provide safe, continuous cancer treatment."

Comments

Key Application Overlooked

[TripMaster Monkey]

From TFA:

Rather, the most immediate application may come in the form of a battery-operated, portable neutron generator. Such a device could be used to detect explosives or to scan luggage at airports, and it could also be an important tool for a wide range of laboratory experiments.

I'm surprised that the article didn't go into more depth on the explosives detection angle, as a neutron generator is an excellent method for detecting fissionable material, and I'm sure the folks over at Homeland Security would like a better way to guard against nuclear devices being smuggled into our country.

For more info on neutron generators and their possible application in fissionable materials detection, please look here (PDF warning).

Re:Key Application Overlooked

[lgw]

Modern nuclear weapons are around 1 MT, usually a bit less, as that's the optimal size for a weapon you can target accurately. The larger nukes of old were designed to crack silos with a near miss, were extremely expensive for their mission, and were taken out of service long ago. If a terrorist gets a nuclear weapon, it's either going to be a sub-MT military weapon, or a quite a bit smaller "home made" fission only device (modern nukes are pretty sophisticated fusion-pumped-fission devices).

Let's do the math. A 1 MT nuke detonated at optimal blast height will knock down residential structures at a radius of 10 km, more solid buildings at 7 km, and at 5 km knock down reinfored buildings and kill people outright from the blast (and all other effects, such as high doses of radiation, have smaller radii). A surface blast would have a far smaller effect. The only real point of a surface blast is to generate radioactive fallout (an air blast generates surprisingly little, though it would still hinder clean-up and rebuilding).

So yes, in theory, a terrorist with a high-quality military nuke (let's imagine a few were sold out of the old USSR armory, and somehow still worked today (the tritium would have to be replaced, which is quite technical, but lets imagine a scientist came with the bomb)) could sit a couple of kilometers off the coast and destroy some structures along the coast. Good for psycological impact, but not much else, and insanely expensive to carry out. A 50 kt fission bomb, a far more likely scenario for a terrorist, would have less than 40% of the blast radius of the high quality military bomb, and would probably need to be within 1 km to be effective.

A surface blast over *land* is what a terrorist wants, because the radioactive fallout would cause a world of hurt. You'd get very little of that even 1 km off the coast, and even a ship at a dock would produce far less fallout than a bomb 1 km inland. It's *definitely* worth checking for nukes at ports of entry: the threat just goes down very fast as the bomb moves away from land.

Interesting

[hey!]

It's quite an accomplishment. However, as the article noted, they don't mention even the remote future possibility of creating a self-sustaining reaction. So I'm assuming that there is no way even in principle this technology could be scaled to yield more power than it uses.

Re:Interesting

[Vellmont]

So I'm assuming that there is no way even in principle this technology could be scaled to yield more power than it uses.


From the sound of what's going on, I think that's correct. The thing about a confined fusion generator is that it works through having the plasma at enormous temperatures. At these high temperatures the particles are slamming into each other at high speed, occasionally so hard they fuse together. This fusion itself produces more heat, so there's a feedback loop that's sustaining the reaction. This device sounds like it works through just accelerating particles with an electric field to high speeds, and then smashes the particles into one another. I don't see any potential for feedback here, so a sustained reaction seems unlikely.

Get the paper here

[Anonymous Coward]

The paper.

Re:Oh great...

[AKAImBatman]

IANAP (I am not a physicist), but I do know that nuclear fusion doesn't create fallout like nuclear fission does.

Fallout is caused by one of two events:

1. Excess nuclear materials not consumed in the reaction are left behind.

2. The neutron radiation from the event interacted with nearby materials (such as the dirt on the ground) to create new radioactive materials.

Nuclear fusion is "clean" in that there are no radioactive materials left over from the reaction. However, it does produce an incredibly strong neutron flux which can easily create radioactive fallout in nearby materials.

http://en.wikipedia.org/wiki/Nuclear_fallout

Given how destructive neutron radiation is, I'm somewhat surprised that they'd be talking about strapping a reasonably strong source to someone's person.

Re:This sounds oddly familiar

[rossifer]

The difficulty with small scale fusion isn't making it happen. That's been done many, many times. The difficulty with small scale fusion (and all fusion) is making it produce power (more power extracted from the reaction than put into the reaction).

That's where Pons and Fleishman got hosed. They claimed a 300% power surplus without experimental verification. This announcement is different from that for several reasons.

1) These guys are specifically not claiming excess power.
2) They're claiming to have lots of high-energy neutrons.
3) This is actually the announcement of a second group of scientists repeating the experiment and successfully verifying the results of the first group.

In short, this announcement is nothing like the cold fusion debacle of the late '80s.

Regards,
Ross

Re:Oh great...

[Waffle Iron]

Thanks for continuing to propagate irrational fear of nuclear materials. Fallout is associated with the older, "dirtier" fission nukes. We haven't seen one like that in, what... 45 or 50 years? This is also different - not only because the amount of emissions are small - but because it's neutrons.

And what are neutrons? Oh yeah, just one of the most penetrating and dangerous forms of radiation. Why else do you think that when they had to find a form of radiation that could kill tank crews inside their vehicles, the viable choice was the neutron bomb?

Pure fusion bombs create huge numbers of neutrons. If the explosion is near the ground, these neutrons can activate the debris that gets sucked into the mushroom cloud and create plenty of fallout. (Not to mention, most bombs use a natural uranium case to get a cheap energy boost when it's fissioned by the extra fusion neutrons. Most of total the energy output is often still fission.)

And any amount of emissions that's intense enough to kill cancer tumors isn't exactly "small".

Also: Nowhere in the article does it mention anything about breaking apart massive atoms and leaving behind radioactive isotopes that are chemically reactive in the human body; Which, I assume, is what you're so worried about.

Instead, you add neutrons to the the elements already inside your body, thereby turning them into dangerous radioactive isotopes where they sit.

Re:This sounds oddly familiar

[JourneyExpertApe]

That's where Pons and Fleishman got hosed. They claimed a 300% power surplus without experimental verification.

I think the more important difference between this and Pons and Fleishman's cold fusion is that this is clearly fusion, and P&F wasn't. The effects P&F observed were probably the result of a chemical reaction and/or bad experimental design. They didn't observe any of the characteristic radiation or products.

FYI, this isn't the first tabletop deuterium fusion discovered. See bubble fusion.