Nuclear Fusion Discovered

prostoalex writes "Both USA Today and The New York Times are reporting on research group from UCLA led by Seth J. Putterman which has discovered a form of nuclear fusion. The impact of the discovery? 'While the device is probably too inefficient to produce electricity or other forms of energy, the scientists say, egg-size fusion generators could someday find uses in spacecraft thrusters, medical treatments and scanners that search for bombs.' The findings are published in Nature magazine."

Comments

great result, but not really a "discovery"

[gevmage]

First of all, humans "discovered" fusion in 1953 with the first fusion bomb, or "hydrogen" bomb. What this speaks of is controlled fusion.

Secondly, this isn't fusion on even a battery scale; this is a few thousand atoms per second or so. So unfortunately, it's not a matter of scaling up to produce a reactor. The amount of energy being put into the system dwarfs by thousands of times the energy from fusion being put out.

Third, this isn't even the discovery of table-top laboratory scale fusion. As an undergraduate, I worked on a muon catalyzed fusion experiment at TRIUMF in Vancouver. By the time I was working on the experiment in 1994, the fusion reaction in the experiment was so well understood that it was being used to analyze other properties of solidified Hydrogen.

And I'm afraid it's a little bit of a dodge to say it's "at room temperature". The article doesn't say this, but presumably this takes place in a vaccum, where temperature is basically undefined in any conventional sense.

So a very nifty result, but not a discovery, I'm afraid. It will very likely be useful to study the fusion process, or perhaps other things as well.

Re:great result, but not really a "discovery"

[nietsch]

There is a feasible fusion generator that you failed to mention, invented in the '60 by the inventor of television, Philo Farnsworth.

Have a look at it here:
http://en.wikipedia.org/wiki/Farnsworth-Hirsch_Fus or

"Unlike most controlled fusion systems, which slowly heat a magnetically confined plasma, the fusor injects "high temperature" ions directly into a reaction chamber, thereby avoiding a considerable amount of complexity.

When Farnsworth-Hirsch Fusor was first introduced to the fusion research world in the late 1960s, the Fusor was the first device that could clearly demonstrate it was producing any fusion reactions at all.

It has since been abandoned as a potential fusion generator, since you still have to put in more energy than comes out of it (like every other fusion technology thus far). Some suggest this may be because it is too simple and offers less ways to spend lots of money on it (and acquire status and research grants by doing so).

And humans discovered fusion in the morning, when they opened their eyes and looked at the sun...

Re:great result, but not really a "discovery"

[merlin_jim]

I'd just like to add a few points.

This method of fusion has been known for at least a decade. But the energy efficiency is so low that it's just not a candidate for power generation. Like the article says, this is primarily targetted as a neutron source. It might be able to be scaled above the break even point, but not without some pretty innovative features.

The basic of it is you get a copper plate, attach it to a special crystal, heat it with a tungsten filament, and immerse it in deuterium gas. The heated crystal strips electrons from the deuterium gas, and the ions are accelerated towards an erbium-deuterium target.

I imagine most of your energy is lost as waste heat. And while this is cold fusion, this is not room temperature fusion. Cold fusion is any fusion that is not heat-pressure catalyzed. While heating is involved here, the energy from the heat pressure is not directly used to bring deuterium nuclei together...

Weird

[AKAImBatman]

I would have thought that the editors would have gotten enough complaints about this being a dupe. Oh well.

What this device really is, is not so much of a fusion generator as it is a neutron source. Nuclear physicists use sources such as these for processes such as starting atomic reactions and changing elements. (e.g. You can make lead into gold with enough radiation. Although plutonium production is a far more useful change.)

A nuclear physicist I know suggested that the Sonofusion concept might be useful for the same reasons. Unfortuntely, we are quickly piling up ways of using fusion as neutron sources, but have yet to come up with a single one to produce energy. :-/

Let's see

[khrtt]

First of all, this is a dupe

Secondly, they haven't discovered fusion, they have invented a new type of fusion-based neutron generator. Several types of neutron generators are commonly known, and some are simple enough that you could build a working one in your garage. All of them use the same principle, more or less - high voltage, on the order of 100kV, accelerates deuterium ions into a deuterium (or tritium) containing target. So does this one.

The novelty is that they used a pyroelectric crystal to generate the high voltage. This makes the device small and self-contained, with no need for high-voltage electric machinery. All you do is heat-cycle the crystal with some 50 degree C temperature span, and you get fusion neutrons.

Note that like all fusion devices to date (other than bombs), this gadget produces a lot less fusion energy than is put in, and brings us no closer to having a fusion-based power source.

But it's a neat idea. And it makes a neat cheap laboratory neutron source.

It's not cold fusion

[khrtt]

"Cold" fusion is when the nuclei fuse at "low" temperature. Not just the outside of the reactor that is cold, but the actual nuclei that fuse are "cold". When you're talking about the temperature of atoms, or nuclei, the temperature is the same as energy. This reactor accelerates the ions to high energy, so it's not "cold fusion".

The original "cold fusion" apparatus (the one that didn't work, or at least no one was ever able to replicate the experiment) used an electrolytic cell with palladium electrodes in an electrolyte. Nowhere in the apparatus were the deuterium nuclei accelerated to high speed. The theory was that the current somehow induces the deuterium to infuse into the palladium electrode, where the deuterium nuclei get close enough to each other to fuse, without you having to clash them together at high energy.

That was the cool thing about it (pardon the pun). You didn't have to put much energy into the system, so you had more energy coming out than you had to put in, making it a feasable power source. If it worked:-).

Some corrections to the parent

[Jace Harker]

The amount of energy being put into the system dwarfs by thousands of times the energy from fusion being put out.

They're not claiming it's self-sustaining. They're just claiming that it's novel, which it is, and that it's a neutron generator, which it is.

A commentary article in the current journal of Nature points out that "...portable neutron generators have found a wide range of applications, including welllogging for oil exploration, and the screening of baggage for airline security," but that "high-voltage power is required, and the apparatus is fairly complex."

This device is much simpler and more straightforward.

Third, this isn't even the discovery of table-top laboratory scale fusion.

True, but it is probably one of the simplest and most compact fusion/neutron generating techniques invented to date.

And I'm afraid it's a little bit of a dodge to say it's "at room temperature". The article doesn't say this, but presumably this takes place in a vaccum, where temperature is basically undefined in any conventional sense.

Please RTFA before you critique it. This method uses a pyroelectric crystal, heated presumably up to 100-200 Celsius or so, and a thin deuterium gas and a target made of erbium deuteride, both of which are presumably at or near room temperatures.

In any case, by "cold" fusion we typically mean "at temperatures easily maintainable in a lab," to distinguish from "hot" fusion which occurs at many thousands or millions of degrees.

Also, you should know that even in a "perfect" vacuum, temperature is and can be well-defined, usually by thermal radiation equilibrium with the enclosure. Even outer space has a well-defined thermal radiation background, which I think is within a couple degrees of absolute zero.

Summary of the actual nature article

[francisew]

Their setup: The 'crystal' mentioned in the mainstream articles, is a z-cut lithium tantalate crystal (LiTaO3), with the negative axis facing outward onto a hollow copper block. A tiny tungsten probe (80 microns long and 100 nm wide) is then attached to the other crystal face. This probe acts as a tiny mast for the electric field so that there is a powerful electrical field at the tip of the probe. Then there were a bunch of fancy neutron-counters and single-photon counters bundled around it.

What they did: First they added deuterium gas (at 0.7 Pa) and then cooled the crystal down using liquid nitrogen (to 240 K). Then they used a little heater to increase the chamber temperature slowly.

What happened: Less than 3 minutes later, and still below 273 K (0 degrees Celcius), the neutron signal rose above the background level. There were x-rays coming from the probe tip, and a whole bunch of neutrons. After a few more minutes, the electric field was so strong that it caused arcing between the probe tip and the enclosure (because they kept heatingthe crystal, and the field thus kept getting stronger). The arcing stopped the process (and I'd guess it damages the crystal?).

They added a few links in the article to previous papers: a pdf describing the concept they are trying to harness, another pdf with more about how they use the crystals with the deuterium gas, and a brief abstract.

I think this is pretty cool. I bet/hope that before long (within 10 years), this will be powering small extrasolar probes.

Pretty neat stuff. I don't even mind dupe posts when they're on such important stuff.