FUSION
Fusion is the process of nuclei fusing together
to create energy. This is the opposite of fission, the dividing of a nucleus.
Energy is given off from this process of fusion when the products have
a smaller total mass than the original mass before fusion occurs. Mass
energy turns into kinetic energy during the process.
Technically, "fusion" is short for "Nuclear
Fusion," which describes the class of reactions where two light nuclei
fuse together, forming a heavier nucleus. This heavier nucleus is frequently
unstable, and sometimes splits (fissions) into two or more fragments. "Fusion"
also refers to the type of energy produced, and a "fusion reactor" describes
an energy-producing facility which generates power via fusion reactors.
Finally, "fusion" can also be used to refer to the scientific program aimed
at harnessing fusion for clean, safe, and hopefully inexpensive energy
production - a collaborative international program which has been carried
on for the past 40-some years.
The generation of multi-megawatt levels
of fusion power is a major achievement for the controlled fusion program.
Sustaining the power output for a second is also significant, because most
known plasma instabilities occur much more quickly. Also, use of tritium
to achieve high power levels enables researchers to study plasmas under
conditions closer to those of a working fusion reactor. There are effects
due to the heavier tritium ions, and due to the presence of highly energetic
helium ions produced in the fusion reaction. In particular, scientists
were worried that the energetic He ions might trigger new plasma instabilities.
(Plasmas are notorious for finding new ways to misbehave whenever scientists
manage to improve the operating conditions.) Fortunately, no major instabilities
were observed, and in fact early reports are that plasma performance actually
improves in high-power D-T conditions. These results enhance the prospects
for future experiments which will try to achieve even higher power outputs
in nearly steady-state conditions.
COSTS
PROGRAMME ACCESSIBLE CONTRACT VALUE (out of the
total £900m spent pa)
UK £4m pa
JET Project £30m pa
Other European £30m pa
ITER design and R&D £3m pa (European
share)
Other world £20m pa
ITER construction £6000m over 10 years (total
budget)
Inertial
Gravity
LINKS
www.doe.com
www.osti.gov
www.fusion.org