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The plasma in a tokamak fusion reactor is so hot, only pulsed transformers
have so far been able to generate magnetic fields strong enough to contain it.
Now Swiss physicists have shown that beaming powerful microwaves into a
doughnut-shaped tokamak can create a strong, steady magnetic field—a
significant step towards a practical reactor (Physical Review Letters,
vol 84, p 3322). A team at the Swiss Federal Institute of Technology in Lausanne
ran their microwave source for two seconds, but say longer-operating sources are
in development.