Direct Fusion Drive

[Winston]

Direct Fusion Drive

https://en.wikipedia.org/wiki/Direct_Fusion_Drive
"a specific impulse (Isp) of about 10,000 seconds"

Exploration of trans-Neptunian objects using the Direct Fusion Drive

https://arxiv.org/pdf/2009.12633.pdf

 

[user 13]

Very interesting!

 

[aerostadt]

There is still the major drawback that no controlled fusion device has yet to be demonstrated. That such an onslaught of ideas over decades has produced no working model, makes me wonder if a device is ever demonstrated it will not have the simple configuration shown in the DFD.

 

[Marc_G]

"We're about ten years away" is a common refrain...

 

[user 13]

"We're about ten years away" is a common refrain...

Yup,

I've been hearing that since 1980!

 

[aerostadt]

Yup,

I've been hearing that since 1980!

I hate to show my age, but for me it's probably been since 1970.

 

[rocket_troy]

I hate to show my age, but for me it's probably been since 1970.

Maybe that's the tech our flying cars are relying on

 

[jqavins]

There is still the major drawback that no controlled fusion device has yet to be demonstrated.

Many controlled fusion devices have been demonstrated. None are power positive yet. One type, the fusor, is shockingly simple; you can build one in your garage. That one is very far from power positive.

 

[aerostadt]

Many controlled fusion devices have been demonstrated. None are power positive yet. One type, the fusor, is shockingly simple; you can build one in your garage. That one is very far from power positive.

That is a nice reference. I heard about this about 20 years ago. It is often referred to sd inertial electrostatic confinement. Scientific American mentioned inertial electrostatic confinement in an article 50 years ago, but just in passing and I didn't pay attention to it. About 5 years ago Popular Science had an article on a rash of new approaches to controlled thermonuclear fusion. Soon after Scientific American did a similar article. However, since then, there has been no outstanding news about the new approaches. As you may know there is a huge ITER being built in France by a consortium of nations, which should demonstrate something close to the break-even point in power production to come on line in a few years, but it will not be a practical device.

https://en.wikipedia.org/wiki/ITER

 

[Jeff Lassahn]

you can build one in your garage.

You can, but please don't. Generating lots of free neutrons is not good for you, and not polite to the neighbors.

 

[Zeus-cat]

You can, but please don't. Generating lots of free neutrons is not good for you, and not polite to the neighbors.

What if I don't like my neighbors?

 

[Funkworks]

Here's a rough timeline of fusion research.
https://en.wikipedia.org/wiki/Timeline_of_nuclear_fusion
I remember reading about the ITER in the 90's. It blows my mind that assmbly only started last year. It would be interesting to compare the project with the international space station and understand why such an apparent difference in progress.

 

[aerostadt]

Here's a rough timeline of fusion research.
https://en.wikipedia.org/wiki/Timeline_of_nuclear_fusion
I remember reading about the ITER in the 90's. It blows my mind that assmbly only started last year. It would be interesting to compare the project with the international space station and understand why such an apparent difference in progress.

This is really a nice time line. I remember reading about Kantrovitz & Jacobs making their experiment (so called Diffusion Inhibitor) in the Langley Aeronautical lab in 1938. In 1938!! Eventually, they got caught by one of their superiors and he shut the project down (not exactly an aeronautical project). They tried to detect x-rays, but found none. Eventually, people would release that the plasma confinement in their magnetic containment was not good enough for fusion. It is interesting to read about their ideas, a lot of which are still valid today.

I remember reading somewhere that George Gamow (author of the book, "One, Two, Three... Infinity") got an offer of support from Stalin to make a fusion reactor a long time ago. Realizing how difficult the task was and that the consequence of failure would lead him to being sent to Siberia, he turned the offer down. I looked at the time-line later today for ITER and it is farther away than I thought. The scheduled first test of plasma confinement is 2025. The first meaningful tests with dueturium and tritium is not until 2035. I am not sure that I will live long enough to hear about the results.

 

[DaHabes]

Recent article....

https://medium.com/the-innovation/c...-fusion-reactor-market-mad-house-99dce0745b67

 

[JoePfeiffer]

"We're about ten years away" is a common refrain...

Yup. I remember reading that when I was an undergrad. I finished my BS in 1979.

Fusion power is on the horizon. If you look in the dictionary, you'll find the horizon is an imaginary line that recedes as you approach it.

 

[Funkworks]

If researchers gave up on fusion, I think everyone else would be like

 

[prfesser]

The Skunk Works is supposedly developing a fusion reactor small enough to go in the bed of a truck. I remain skeptical. I know the Skunk Works has done some incredible work, bu that article is almost two years old and the work has been ongoing for somewhat longer than that.

Best -- Terry

 

[Funkworks]

The Skunk Works is supposedly developing a fusion reactor small enough to go in the bed of a truck. I remain skeptical. I know the Skunk Works has done some incredible work, bu that article is almost two years old and the work has been ongoing for somewhat longer than that.

I always imagined that their media releases might be for the same spy game as many of their products. In any case:


https://lockheedmartin.com/en-us/products/compact-fusion.htmlhttps://en.wikipedia.org/wiki/Lockheed_Martin_Compact_Fusion_Reactorhttps://finance.yahoo.com/news/lockheed-martin-doubles-down-cold-120300203.html
Whatever anyone says about controlled fusion, everyone agrees that it's a difficult problem. And many of those who dive in end up finding it more difficult than they thought at first. I mean, if you thought calculus was hard, well have I got news for you.

 

[Funkworks]

Here's recent ITER video particularly appropriate for a hobbyist forum: Build your own model with a 3D printer!


When you imagine China, the European Union, India, Japan, Russia, South Korea, and the US sitting at the same table and trying to agree, it partly explains the delays. And that's a lot of people choosing not to invest in "cold" approaches. Basically, it's the next logical step in the tokamak route, which is arguably the most successful so far. No matter what the results turn out to be, the project will help map out directions for future research.

 

[OverTheTop]

Here is a recent article on Lattice Confinement Fusion in IEEE Spectrum
https://spectrum.ieee.org/lattice-confinement-fusion#toggle-gdpr

 

[DaHabes]

Here's a rough timeline of fusion research.
https://en.wikipedia.org/wiki/Timeline_of_nuclear_fusion
I remember reading about the ITER in the 90's. It blows my mind that assmbly only started last year. It would be interesting to compare the project with the international space station and understand why such an apparent difference in progress.

Because we know how to use chemical rockets to boost payload to orbit. Fusion is several orders of magnitude more complex.

 

[Funkworks]

Because we know how to use chemical rockets to boost payload to orbit. Fusion is several orders of magnitude more complex.

I agree it's more approachable.

Here's recent good news in fusion:

"On December 21st, 2021, the "tokamak" reactor produced 59 megajoules of energy during a five second fusion pulse, more than double what it managed way back in 1997."

https://www.sciencedaily.com/releases/2022/02/220210085048.htm
I compare this to an olympic sport: the interesting part is to see how far people can push the envelope.

 

[Grog6]

There were experiments I heard about in the 80's that the only way they could get a stable reaction was to use tritium or h3, which made everything radioactive from stray neutrons. Another problem was that gold bond wires cause problems when radioactive. This is also a problem for nuclear powered missles.

 

[OverTheTop]

It seems the National Ignition Facility has gone power gain positive. Good news .
https://www.abc.net.au/news/2022-12...fusion-reaction-energy-breakthrough/101769074
What is also really cool is that one of my spectrometers is at the facility for checking quality of things like laser plates (Nd-YAG I assume still). We did a custom accessory just so they could get the large plates into the sample area.

 

[cls]

s the National Ignition Facility has gone power gain positive. Good news .

Maybe... NIF is about H bomb research, not about fusion. Any fusion results are a fringe benefit, the rest of the research is highly classified.

NIF was built because of the test ban treaty, need a way to model our aging arsenal and replacement devices, to ensure they provide a credible defense.