Fusion is the process that powers the sun and the stars and is fundamental
to element production in the universe.
It is a reaction where two light atoms, such as hydrogen, combine together
to form a heavier atom, such as helium. IN this process, some of the mass
of the hydrogen is turned into energy. The simplest fusion reaction is
that of combining deuterium (or "heavy hydrogen") with tritium (or "heavy-heavy
hydrogen") to make helium and a neutron. Deuterium is plentiful and can
be found in ordinary water. Tritium can be produced by combining the fusion
neutron with the light metal lithium. From this fusion can be seen as a
potential source of energy
For fusion to occur, the atoms of hydrogen must be heated to extreme
temperatures (100 million degrees) so they have enough energy to fuse together
and then be held together long enough for fusion to occur. The sun and
starts use gravity to do this. More practical methods for us are to use
very strong magnetic fields which holds the atoms together while they are
being heated by microwaves or other energy sources
Why do we care about fusion? If we are successful, fusion would be
a virtually inexhaustable energy source. One out of every 6500 atoms of
hydrogen in ordinary water is deuterium, giving a gallon of water the energy
content of 300 gallons of gasoline.
Fustion would also be environmentally friendly, producing no air pollution
or greenhouse gases. At the present time we are pretty close to making
it work. Fusion sounds like a simple procedure but the details are difficult
and precise. Heating and confining hydrogen plasmas at 100 million degrees
is a significant challenge. A lot of science and engineering had to be
learned and implemented to get fusion to where we are today. Both magnetic
and inertial fusion programs expect to build their next experiments that
will reach ignition and produce more energy than they consume shortly after
the year 2000.
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