[snikt]
> Creating a fusion reactor that is 20 miles long should be even easier
> conceptially. The main difficulty is the economic resources that need to
be
> mustered to build it. If you talk to a fusion scientist, I'm pretty sure
he
> can come up with a working design. Changes are that the fusion powered
Island
> three could even beam surplus fusion power to Earth if in orbit. Large
> structures are easier to build in orbit than on the ground as they require
> less support material.
>
basically unviable on Earth. For example, one could build what I call a
"mass drive-powered fusion reactor". Instead of fighting to tame a plasma
cloud trapped inside a magnetic field (which "is like sustaining a candle
inside a tornado", quoting a Japanese fusion scientist whose name I can't
remember), you can simply build two very, very long (tens of kilometers,
perhaps) mass drivers, each one pointing to the output of the other, and use
them to accelerate tiny droplets of hydrogen (perhaps metallic hydrogen, or
liquid hydrogen wrapped in an iron sphere, in order to maximize magnetic
interaction) towards the center of the structure. There, the two droplets
would collide against each other at hundreds or thousands of kilometers per
second, and the heat and pressure created during the collision would fuse
the hydrogen, converting the droplets in a micro-nuke. Of course the tiny
explosions would occur inside a hollow sphere of tungsten or whatever, and
the sphere would become red-hot, and the heat could be used to produce steam
and move turbines, just like in a conventional atomic power plant.
>
> Tom Kalbfus
[snikt]
Lucio Coelho
>
> In particular, in orbit you could implement fusion reactor designs that are
> basically unviable on Earth. For example, one could build what I call a
> "mass drive-powered fusion reactor". Instead of fighting to tame a plasma
> the hydrogen, converting the droplets in a micro-nuke. Of course the tiny
> explosions would occur inside a hollow sphere of tungsten or whatever, and
> the sphere would become red-hot, and the heat could be used to produce steam
> and move turbines, just like in a conventional atomic power plant.
>
Last I heard, the showstopper with fusion is the firtst layer of
physical contianment.
The neutron flux physically erodes all known materials rather quickly.
Debris from the container drifts into the plasma cloud causing it to
instantly collapse.
diffuse reflection)
> The neutron flux physically erodes all known materials rather quickly.
>
I guess that an orbiting mass driver-powered fusion reactor (OMDPFR) can be
made big enough to allow *hydrogen* fusion, instead of deuterium-tritium or
any other combination that generates neutrons. You would have just a gamma
ray source.
Still, this container erosion sounds rather strange. Conventional fission
reactors, using uranium and plutonium, also generates lots of neutrons. So,
why don't they suffer the same problem of neutron erosion?
> Debris from the container drifts into the plasma cloud causing it to
> instantly collapse.
>
The proposed OMDPFR would not use plasma clouds to get fusion. It would
*generate* a plasma cloud (actually, a small-scale short wave) when fusing
hydrogen pellets by colliding them. Those pulsed shockwaves would likely
*compress* the inner walls of the collision chamber and keep any debris
smashed against it.
Perhaps I did not make the concept quite clear yet. An OMDPFR would work in
a way analogous to laser-powered fusion, fusing a droplet of hydrogen at the
center of a hollow spherical reaction core. However, the enormous
compression and temperature needed to trigger fusion would be accomplished
not by lasers (which represent, by the way, a vast waste of energy), but by
accelerating an colliding the droplets against each other at enormous
speeds.
[snikt]
Lucio Coelho
Hydrogen 1 fusion does not work, as Helium 2 will not form, rather
Hydrogen 2 must form, as the Sun does it, so one is back with neutrons. Why
not just use the Sun for power, which has already passed its environmental
impact study, and will be there fired up for another 5 billion or so years?
Our efforts on trying to learn how to do controlled fusion for electric
power or rocket propulsion have been good sources of jobs for scientists and
engineers, but like missile defense, have cost ~ 100 billion $ with no
success to show for it. Will another 100 billion change that?
The Apollo project cost ~ 30 billion $. Which will be remembered? Lets
spend our money on the high frontier!
Jay S. Huebner at jhuebn@...
Well, despite this thread, I'm not a fusion advocate either. As I often
remember, 50 years ago fusion scientists were used to say that we would have
fusion reactors in fifty years - that is, now. However, nowadays fusion
scientists say that we will have to wait 50 more years...
problem plaguing Humanity. Fusion will be needed just decades or centuries
in the future, when the Outer Solar System is colonized.
use reflection)
> Hydrogen 1 fusion does not work, as Helium 2 will not form, rather
> Hydrogen 2 must form, as the Sun does it, so one is back with neutrons.
Why
> not just use the Sun for power, which has already passed its environmental
> impact study, and will be there fired up for another 5 billion or so
years?
> Our efforts on trying to learn how to do controlled fusion for electric
> power or rocket propulsion have been good sources of jobs for scientists
and
> engineers, but like missile defense, have cost ~ 100 billion $ with no
> success to show for it. Will another 100 billion change that?
> The Apollo project cost ~ 30 billion $. Which will be remembered?
Lets
Still, this container erosion sounds rather strange. Conventional fission
reactors, using uranium and plutonium, also generates lots of neutrons. So,
why don't they suffer the same problem of neutron erosion?
>>>>>>>>>>>>.
The material degradation is a containment issue, and is handled by overdesigning the containment vessel to make it damage tolerant.
BTW the neutron flux from fusion is a good deal higher than for fission.
Thesis, Anti-thesis,...Synthesis!
Fusion reactor close to you, fusion reactor 93 million
miles away. Why not both. Remenber a NSS article
mentioning how a half a fusion reactor, was a very
powerful fusion rocket. And the fusion reaction can be
jumpstarted from a from a large solar parabolic
mirror/fesnal lens whatever.
Use the sunlight for the colony, use the fusion
reactor/rocket to get around and then for power when
you want to boogie to the Ort cloud.
You know once there is an "Infrastructure" in the
orbit of Venus and Mercury, we could have million of
square miles of solar collectors pumping power to the
rest of the solar system. Lasers could transport the
power with little loss.
And one thing which we have going for us to build a
fusion reactor in space, just all that vacum and the
distance from all the elementary schools of Earth.
opinions here and just want to thank everyone.
It feels like a conceptual design engineering firm
on speed ;')
Just wished I have the cash to build prototypes.
best regard
Pete
I don't think anyone objects to having another fusion reactor in a safe
location. What I object to is taking ~ 100 billion $ from other projects
which would seem likely to be more productive to continue those that have
records of failure.
Starting fusion is not so easy. By focusing the Sun's rays one can get a
temperature approaching 6,000 K. To get fusion going slowly as it does at
the core of the Sun, given the pressure there, takes 10,000,000 K. I
understand hydrogen bombs (the weapons) use ~ 100,000,000 K.
I would think one would have to wait on the final design of fusion
rockets until controlled fusion works first.
Sincerely, Jay S. Huebner at jhuebn@...
>>>They do, but it does not affect the fission reaction.
The material degradation is a containment issue, and is handled by
overdesigning the containment vessel to make it damage tolerant.>>>
reactors. Westinghouse PWR's use a core barrel and neutron panel, in an
effort to try and shield the pressure vessel from the hard neutron flux. In
a fusion reactor you could try something similar (that is, you would coat
the interior of the torus with a thin layer of material with high neutron
cross-section, cadmium? ). The big difference is, that the interior of a
fusion reactor will need to be replaced much more regularly. It will also
be highly radioactive, although most of the radioactive products will
probably have short half-lives.
Tony