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Fusion Thrusters For Space Travel
kgeiger writes "John J. Chapman, a physicist and electronics engineer at NASA's Langley Research Center, envisions a laser-pumped fusion drive. Chapman estimates the drive can produce thrust 40 times more efficiently than existing ion engines such as those on the Dawn mission now exploring the asteroid belt."
Alrighty so I haven't RTFA but this is the kind of stuff NASA should be doing more. Hire ambitious smart people with grand ideas, give them resources and turn 'em loose! Probably much of what they do will amount to nothing but you just never know (a great concept may become reality).
mfwright@batnet.com
*LASER*-pumped *FUSION* drive... Say that out loud...
Are we living in the future yet?
How will the shark tanks work in space with zero Gs?
love is just extroverted narcissism
that's about the feeling I got with their "300 watts" nonsense, an amount of boron will give an amount of energy. Han Solo type bragging with nonsense units. Power would only be known after knowing at time interval.
The reaction is
1H + 11B -> 12C -> 4He + 8Be -> 4He + 4He + 4He
so there are more output nuclei than input.
However, I suppose it is true that all of the energy is coming from fusion, as 12C -> 4He + 4He + 4He is exothermic. (The reverse reaction is an energy source for stars under some circumstances.)
12C is normally stable, so for this reaction to go as stated the nucleus must be created in some suitable excited state.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
"The specific power of the proton-triggered boron fuel would be so great that a mere mole of it (11 grams) would yield roughly 300 megawatts of power. " (!) the efficiency sounds awesome.
Come on IEEE, I expected better of you. Power output is irrelevent. We care about energy output. 11 grams of boron fuel will get you 300 megawatts for what duration?
When I think about how much more the US could do if we didn't squander our money on bullshit
This isn't about net energy gain. It's about specific impulse.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
On Earth, we want to use fusion to power homes, ground vehicles, etc. However, the amount of work and energy we put into fusion gives us much less gain when compared to the amount of energy we can extract with fission, wind, solar, waves, geothermal, oil and coal. We attempt this with deuterium and tritium to produce neutrons. As the article puts it; [To make use of neutrons, "you need an absorbing wall that converts the kinetic energy of the particles to thermal energy," he says. "In effect, all you’ve got is a fancy heat engine, with all its resultant losses and limitations."]
According to the article, he's suggesting using Aneutronic fusion using Boron-11 as a fuel source to produce alpha particles (Helium-4 and Beryllium) via a laser which will yield 60% - 70% efficiency and 100,000 particles with each pulse. Boron will yield 300 MW of power per 11 mg, whereas Helium-3 isotopes as a fuel source would yield 493 MW in equal quantities. However, Helium-3 is scarce whereas Boron is not so it makes more sense to go with Boron instead. He claims it would be 40% more efficient than current deep space ion engines.
Keep in mind, that these engines have to run for long periods of time over great distances. They have all the time in the world to increase their acceleration to their mass potential. It's Hare vs the Tortoise, on Earth we need our power *right now* in large quantities and quickly. Whereas, in space you have patience because the distances are already so vast, you don't have much room to store fuel, and there is little or no friction so you can take your time building up speed.
Hope that helped you make heads or tails of this.
Put the research into increasing our population,
I'm happy to help with that research!
Man who leaps off cliff jumps to conclusion.
Sanger proposed this way back in the early 1950's.
And Spencer wrote about it later:
Spencer, Dwain F. "Fusion Propulsion for Interstellar Missions". Annals NY Academy of Sciences 140, 407-418 (1966).
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Robert Forward documented all the above in a book I have on my shelf, but for the life of me can't remember the title. Heck, I was doing solar sail research/simulations on an x86 back in the 80's and we were proposing fusion drives as a power source for sails when the vehicle was in interstellar space.
It's great for today's visionaries to talk about their theories, but we all need to remember our ideas are based on the shoulders of those before us, whether they are giants or not.
We spend the equivalent of a huge forest of money trees on USELESS aggression; bring those troops and ships home, destroy deployed equipment in place, sell it to the locals, or bring it home if practical, leave the military brought home employed for a strong standing defense, and (a) we'd be acting morally for the first time in decades and (b) the money spent on the standing army, now home, would go right back into our OWN economy, and (c) we'd have huge overall spending reductions we could apply to the debt and perhaps once again, someday, have money to spend for our actual benefit.
Our budget problems are 100% solvable. All you need to do is get the cowards out of congress. Somehow.
I've fallen off your lawn, and I can't get up.
Now, please correct me if I'm wrong, and I may be wrong, but:
6.02e23 / 100 000 == 6.02e18 pulses to process one mole of boron
6.02e18 / 75e6 == 8.02e11 seconds to process one mole of boron
300e6 W / 8.02e11 seconds == 3.7e-3 W/sec
I can't tell you how that compares with an ion drive.
steveha
Sorry, but I think you are wrong. wwagerrp wanted to know the energy the machine would get from 1 mol of boron fuel, the article gives us something in watts, and you gave something in watts/second when in fact what is needed will be in watt-seconds (or joules as most people say).
This might be better: 75e6 * 1e5 gives 75e11 particles released per second. But, the article doesn't say how many of those go on to fuse, etc so this is all academic. Assuming it wasn't, though, 300e6 (Joule/second) / 750e11 (1/second) gives 4e-6 Joules/particle. 8.7 MeV ~= 1.4e-12 Joules so there's something definitely wrong here.
To sum up, article on spectrum is light on details and written pretty badly. If you want to actually know how this thing is supposed to work try and find the paper because frankly I've seen better science reporting in the free paper they have on the bus.
If God forks the Universe every time you roll a die, he'd better have a damned good memory.
That's a myth.
Thirty-forty years ago, optimistic predictions were for working fusion power plants circa the first decade of the new millennium. Realistic predictions were somewhat further away. And those optimistic predictions were made with the assumption that the intervening decades would see continual, government funded R&D into the subject (because no private enterprise is going to throw billions at something with a forty year payoff).
The R&D funding was not received. Turns out governments don't like throwing billions at the long term anymore than businessmen do, to say nothing of the minor problem that science and engineering tend to get slashed every time there's a budget crisis (want to go back and count how many times that's happened in the past half century?) The prototypes we could have been building weren't built. Progress was slow, though thankfully not nonexistent.
As a result, a decade after the optimists predicted the first fusion power station, we're only now building the testbed prototype. Interestingly, we're not nearly as far behind as most current pessimists like to think. Net-energy producing fusion will probably be seen as unattainable by some people right up until the point where it's attained.
Want to know where the "fusion has been 10-20 years away fro 60 years" meme got going? Morons. Morons who don't get the idea that you can't sit around waiting for progress to happen. Morons who think that research is something that "just happens" and don't seem to realize that sometimes that vital, civilization advancing research requires a lot more money and patience than we as a culture are prepared to give. Morons who looked back at the rosy view of the future and didn't see the little disclaimer about how much work it would take to get there.
Morons repeated this meme until it became accepted fact and a glib response, brought up every time there's a news story about fusion research. It's time to let this meme, this myth, die.
Erotic is when you use a feather. Exotic is when you use the whole chicken.
The article is simply wrong.
"The specific power of the proton-triggered boron fuel would be so great that a mere mole of it (11 grams) would yield roughly 300 megawatts of power."
A Watt is a joule / second, i.e., energy / second. A given amount of material to fuse (such as a mole) can only provide a given amount of energy. So, a mole of something cannot just yield watts. It can yield watts for some period of time, or a mole per second (or per some other period of time) can yield watts, but, as written, the article can't be correct.
I'd say close enough for gov't work, or for my tiny little brain :)
Alpha particles:
Alpha particles (named after and denoted by the first letter in the Greek alphabet, ) consist of two protons and two neutrons bound together into a particle identical to a helium nucleus, ...
The nomenclature is not well defined, and thus not all high-velocity helium nuclei are considered by all authors as alpha particles. As with beta and gamma rays/particles, the name used for the particle carries some mild connotations about its production process and energy, but these are not rigorously applied.
It's easier to be a result of the past, but more fun to be a cause of the future! http://www.spacefinancegroup.com/
We should have these power collectors/transmitters in orbit around the Sun, pointed down at the Earth to collectors floating on the seas. Where they could electrolyze water, or any of a number of other ways to get the energy back to the land where it can be consumed. Emissions free, vastly more power than we can use for the foreseeable future.
The beams would have to be only a few times the intensity of sunlight, but shine all day/night (courtesy of geosync relay satellites) over a few dozen square kilometers on each station. No danger from a beam missing the target, though extra protection added by laser interlocks back from the surface to space that drop both up and down beams when the down beam goes off the target.
That system would require several $billion, perhaps several hundred $billion, investment. But at $0.01:KWh, and $100B is only 1KW:m^2 * 3intensity * 36Km^2 * 6stations * $0.01:KWh = 22.5 months payback time. That's better than 50% ROI, on hundreds of $billions. Plus the value of eliminating emissions, terrestrial fuel production and distribution, energy wars and corruption. And regaining the envy of the world.
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make install -not war