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This is a related article I think:
http://www.space.com/23084-mars-explora … ocket.html
So, if it proves true for a Mars expidition, that's wonderful.
That would be suitable for the present condition, where the solar system population is centralized on Earth, and there are no habitates of siginificance elsewhere. It is nice to have a 7 month expidition possibility.
But it would be even nicer later, to spend the outbound trip time in a much upgraded environment such as could be provided by a cycling spaceship.
I think that in the future when there would be a distribution of population off Earth, the above mentioned fusion driven space travel would also be suitable for use with cycling spaceships.
In that use the extra power it would have (If it works), would allow redundant backups in the ships, and so the danger where a malfunction in transfer to and from a cycling spaceship would be reduced. Further, it would also be likely that a device like this would enable rescue ships to be available in the case where a transfer did fail, and a group of passengers were at risk of death. Something like the coast gaurd.
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The energy is theoretically there for fast travel with fusion. The technology is not. Fusion reactors have been "20 or 30 years away" for the last 60 years that I have personally experienced. The closest right now is laser ignition fusion, but with boron and protons, not deuterium-tritium or tritium-tritium. It'll take something different (like the boron maybe) to make controlled fusion work. We've done magnetic bottles for 60 years now without success.
I'm not saying it can't be done, but the problem turned out to be a lot harder than anybody ever suspected going in. The technology to do it is still missing because some of the actual science to support that technology is still missing. That's why the major efforts ongoing are still science projects, not engineering development or real prototype programs. (There are some scientists who might call their projects an engineering prototype, but that's because they weren't trained in development work and don't really understand what it is.)
That being the case, crowdfunding may be premature. It's more appropriate for development-flavored projects than true basic science efforts. There's quite a difference between the two.
There is one fusion application that could work very soon, and be could engineering-prototyped essentially "today": nuclear explosion propulsion, just done with modern thermonuclear devices instead of 1950's fission devices. (They do have to be shaped charges with directional radiation "blast", just like in 1959, though, and that's the development work that is needed.) I don't think you would want to bring one of those vehicles inside the van Allen belts, though. The EMP side effect would be disastrous. Best place to test / base it might be the moon.
GW
Last edited by GW Johnson (2013-10-10 08:43:57)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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Yep - my experience as well! Always 20-30 years away!! I have more optimism about cold fusion.
The energy is theoretically there for fast travel with fusion. The technology is not. Fusion reactors have been "20 or 30 years away" for the last 60 years that I have personally experienced. The closest right now is laser ignition fusion, but with boron and protons, not deuterium-tritium or tritium-tritium. It'll take something different (like the boron maybe) to make controlled fusion work. We've done magnetic bottles for 60 years now without success.
I'm not saying it can't be done, but the problem turned out to be a lot harder than anybody ever suspected going in. The technology to do it is still missing because some of the actual science to support that technology is still missing. That's why the major efforts ongoing are still science projects, not engineering development or real prototype programs. (There are some scientists who might call their projects an engineering prototype, but that's because they weren't trained in development work and don't really understand what it is.)
That being the case, crowdfunding may be premature. It's more appropriate for development-flavored projects than true basic science efforts. There's quite a difference between the two.
There is one fusion application that could work very soon, and be could engineering-prototyped essentially "today": nuclear explosion propulsion, just done with modern thermonuclear devices instead of 1950's fission devices. (They do have to be shaped charges with directional radiation "blast", just like in 1959, though, and that's the development work that is needed.) I don't think you would want to bring one of those vehicles inside the van Allen belts, though. The EMP side effect would be disastrous. Best place to test / base it might be the moon.
GW
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
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Maybe the reason it's always been a few decades away is because the bulk of the funding has gone to the method that's the hardest to make work...
I don't know how the guys at Polywell are doing, but they seem to have a better chance than ITER.
Use what is abundant and build to last
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Polywell must be having troubles, too. That topic has gotten awfully quiet.
Cold fusion still suffers from a toxic reputation, probably undeserved. There was something unexplained going on there, just not the same things in all the attempts to duplicate it, which is what tarred its reputation. But, it surely would be nice if we knew what those unexplained things were, wouldn't it?
I think I'd go for some kind of gas-core hybridized fission-fusion rocket engine, with the energy and particle flux of fission "sparking" at least a little bit of continuous fusion. Feed the exhaust stream directly into a gigantic MHD generator. Or, use it for thrust. Same device, either way. Nobody is working on devices like that. Maybe they should be. (The first article is a simple gas-core fission rocket engine, something we're reasonably sure could be made to work.)
Even if only the straight fission gas core device is ever made to work, the MHD energy conversion into electricity is much higher efficiency than any heat engine power plant process known. Plus, the fission rocket can always serve as a thrust device.
It's two birds with one stone (thrusters and electricity generators), and with technologies that are much more "sure" to work. Plus, it could lead to fusion devices. How could we go wrong?
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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I am joining this conversation with a related article attached.
http://www.space.com/23084-mars-explora … ocket.html
"We're in the lab, we're building the coils, we're showing the scaling and we'll be producing the neutrons within the next year to show that fusion is occurring, and it's occurring at the scales required to build a fusion-driven rocket," Pancotti said.
So, if they actually show progress as claimed, I am excited about the claims for a Mars expidition, probabbly not involving any type of cycling spaceship/cycling hardware, but I am also thinking that this could change the game for cycling spaceships. I will post the rest of what I have to say under that topic.
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This topic has been languishing for a while .... The article at the link below fits (sort of) ...
The "crowd funding" contemplated in the article is a crowd of US government agencies, but the basic idea is similar ...
https://www.yahoo.com/news/commentary-s … 00730.html
Andrew Holland and Stephane Lintner, The Baltimore Sun
Monday February 22, 2021
Now, it is time to think of an “ARPA-S (pace)” like program. Whether as a funding subset within ARPA-E, or at NASA. It would build upon the excitement around space travel to create new private-public investment opportunities into fusion propulsion, so that America can once again lead the new Space Age.
Faster, further, safer, less wasteful space-propulsion engines and scalable space-based power-supplying technologies are very possible and should be in humanities sustainable near future. The only question is: Are we going to be the leaders in this exciting arena or will we need to buy those technologies from abroad?
(th)
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Part of the problem is the narrow minded approach of the fusion science community. There is an absolute insistence on the purist approach that fusion be completed separated from fission. This has resulted in some of the most promising approaches being ignored.
Winterberg proposes using small amounts of fissionable material to act as a trigger for fusion reactions in a much larger fusion charge. Because fissionable material contributes only a small portion of total energy, very little radioactivity is released per unit energy.
http://icc2006.ph.utexas.edu/uploads/13 … _paper.pdf
I had an idea that was similar to Winterberg's idea. Put a tiny 0.01mm diameter raisin of fissionable material (thorium 232?) at the centre of a 2mm diameter lithium deuteride fuel pellet. Use an electrostatic particle accelerator to bombard the fuel pellet with an intense pulse of 1MeV deuterons. A mixture of fusion reactions and ionic deceleration results in intense heating and ablasion of the outer layers of the pellet, compressing the inner pellet to many multiples of its initial density. At the same time, the fusion reactions in the outer shell produce an intense burst of fast neutrons. The neutron flux would be greatest at the centre of the pellet, exactly where we have placed the fissiinable raisin. If the neutron flux is high enough, a large proportion of the thorium nuclei would fast fission, releasing two fission fragments and 2-3 fast neutrons. The fission fragments have total energy of ~160MeV, are highly charged and have a range of only 1E-5m in solid matter, though this is still sufficient for most of the fission fragments born within the 0.01mm diameter raisin to leave it and enter the surrounding fusion fuel with most of their initial energy. They would therefore deposit huge concentrations of energy in the central region of the pellet, resulting in numerous fusion events and feeding even more neutrons streaming into the fissionable core. The super heated plasma particles would have average energy in the MeV range, far above the typical few KeV needed to overcome the coulomb barrier between two fusing hydrogen atoms. As this plasma bubble expands through the pellet, it advances as a detonation wave, I.e. the pellet ignites.
Although fission is used to initiate the fusion reaction, the volume of the fissionable core is only 1E-7 of the total pellet volume, and only 3E-6 of the total pellet mass. The contribution of fission to the total energy yield is therefore negligible and the radioactivity resulting will also be small. Such an approach could probably be developed into a working fusion reactor or space propulsion system with excellent power density right now. But in the minds of the fusion community and the politicos that grant funding, this is still a fission triggered concept and will therefore not receive any funding.
Last edited by Calliban (2021-02-22 14:33:28)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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For Calliban re #9 ....
Interesting reply! A question or two came to mind, both process related ...
Is the Thorium prepared ahead of time, or is this the isotope right out of the mine?
What kind of manufacturing is involved in fabricating these little pellets? How are they stored?
Ok ... more than two questions ...
How are the pellets moved from the storage container to the reaction chamber?
If the goal is to achieve propulsion (which this topic appears to be about) how do the products of the reaction find their way aft?
I assume power is drawn off to sustain the reaction (a) and to provide power for life support (b). How does that happen?
I've had the same question about the Boron-11/Hydrogen reaction that is so attractive, but so hard to do.
How would power be drawn off assuming the reaction can be achieved?
There are lots of nice Alpha particles produced ... do they pull electrons from the external environment? But what if the external environment is a space vessel? Does it suffer a dearth of electrons at some point?
If you think this digression should continue in the Boron-11 topic, I'm fine with that.
I realize this is a typical NewMars forum fork !!!
(th)
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German startup - Marvel Fusion - aims to generate unlimited clean fusion energy with lasers
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Japan's Inpex to join nuclear fusion race with startup investments
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