The term “stellarator” could really apply to any fusion
reactor, since it refers to the harnessing of the reaction of the
center of a star. Fusion reactors are generally divided up according to
their method of beginning and containing this stellar fusion reaction:
either magnetic or inertial confinement. Within magnetic confinement,
which uses super-powered electromagnets to keep the plasma from touching
the walls of the reactor, by far the major tech has been tokamak
confinement. Big, donut-shaped arrangements of coils. That’s how
magnetic fusion reactors look.
But
that’s not necessarily the most efficient way of doing things. It turns
out that if you extend the rings of the tokamak to have a sort of
figure-eight geometry, the movement of electrons occurs so as to create a
substantially stronger magnetic field. That’s good, because tokamak
reactors have struggled to keep plasma confined for all that long. The
record is about 6 minutes 30 seconds, while calculations indicate that
an adequately sized stellarator could sustain a reaction for as long as a
half an hour.
Good thing we have an adequately sized stellarator
in the pipe, then! The Wendelstein 7-X has been at some level of
construction for almost a decade at this point. It was originally
scheduled to open in 2006, but problems building and installing the
finicky, specialized magnetic coils led to repeated delays.
The Wendelstein
7-X is now rumbling to life, doing early test runs and preparing for
the real show in early 2016. On December 10, it created and sustained
for a short time its first plasma — a major proof that the thing hasn’t
been assembled all wrong, but not yet enough to prove the design’s
advantages have been realized.
The big problem with stellarators,
really, is how difficult and expensive they are to build. Tokamaks are
far simpler in design, and engineers broadly know how to build them, but
stellarators are atypical in just about every way. If the Wendelstein
7-X did achieve new heights in plasma confinement, there would then have
to be a discussion of whether it had achieved those heights efficiently
enough to be worth pursuing, versus cheaper-but-less-proficient tokamak
designs.
While these sorts of high-concept test reactors look
into the physics of fusion power, other private entrants are looking to
make chimera solutions that use multiple existing technologies. General
Fusion hopes to use both magnetic confinement and inertial
confinement to get their fusion reaction without having to use such
unhelpfully over-powered versions of either.?
12/14/2015
Huge German fusion reactor powers up, giving age-old tech a new shot
Boy, do we hope stellarators —
which confine and control hot plasma within magnetic fields — are the
thing that works for fusion. After all, it only matters we achieve some
fully green form of mass electricity production from a nigh-infinite
fuel source. If, by chance, the International Thermonuclear
Experimental Reactor (ITER) were to get it done, well, worse things
could happen. But stellarators are the original fusion reactor design,
they’ve got by far the coolest name, and they have some major advantages
over other reactors designs. Best of all? The most powerful stellarator
ever created, the Wendelstein 7-X, was recently switched on in Germany, meaning that the technology could be headed for a major step forward.
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