Re: OT Why No Fusion Powerplants?



On Jan 24, 8:55 am, "Tom Kunich" <cyclintom@yahoo. com> wrote:
<b...@xxxxxxxxxxxxxxxxx> wrote in message

No.  You made this ridiculous claim, so _you_
post a citation to an article in "physics journals."
Not "and such," either.

Somehow I'm not surprised that you don't know anything about the
Superconducting Super Collider costs and the estimations that it was too
small for a power producing station.

Tombot,

I asked for a citation for claims about tokamak sizes
and you give me this nonsense? Do you ever think for
a moment about whether you understand that which
you pontificate about? About the only thing that particle
accelerators such as SSC (or the European LHC, which
is approaching completion) and tokamaks have in common
is that they are toroidal and use very large magnets.

Comparing these two things is like comparing a Ferrari
to a semi-truck. You're doing the equivalent of arguing
that because Ferraris have a big engine but can't haul
much cargo, it's physically impossible to build a semi.

A particle accelerator is designed to produce a relatively
small (in macroscopic terms) jet of extremely high energy
particles - the energy per particle has to be at the level
of the internal binding energy of subatomic particles (billions
or trillions of electron volts) to knock them into pieces.
However, it isn't designed to generate any amount of
energy or be self-sustaining.

A tokamak is designed to contain a hot plasma at the
energy scale that allows atomic nuclei to overcome
their electric-charge repulsion - a few tens of thousands
of electron volts - to allow fusion reactions to proceed.
The energy per particle is much lower than in a collider.
The problem is containing the plasma so that the reaction
sustains itself - much as a fire becomes hot enough to
sustain the chemical reaction of burning.
That's how they hope to generate energy.

Technically, the reason a circular collider like the SSC
or LHC has to be many miles across is that the charged
particle beams undergo a centripetal acceleration to keep
going around the circle. That acceleration causes the
particles to radiate energy by synchrotron radiation.
The energy loss is a strong power of the circle radius,
so you need to build it big, otherwise as you accelerate
the particles they keep losing energy and you can't
ever reach the desired tens of TeV energies. For this
and other technical reasons, the next collider built
after LHC will likely be an electron-positron linear
collider, as opposed to circular.

Tokamaks don't have this issue and don't have to be
many miles across, since they operate at much lower
energies. However the challenges of maintaining
the plasma confinement are messier than directing
the collider's particle beam (which is already pretty
damn complicated, but at least doable currently).

Now go home and read back issues of Scientific
American until you figure out that you don't know
everything. The rest of you, I expect your term papers
on accelerator physics to be on my desk in the
morning.

Ben

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