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"The power of the sun… in the palm of my hand."
So said Dr. Otto Octavius, the infamous scientist turned
supervillain, in the movie Spiderman 2.
What he was referring to in that quote was the fusion
reactor he had created, a device that generated a self-sustaining energy source
like that of the sun. It was this device that quickly turned out of control,
generating a strong magnetic force that nearly leveled the building and resulted in the death of his wife. From then on, Dr. Octavius was Doctor Octopus -
Doc Ock.
(<--It will stabilize! Credit:
Chanmainor.com)
The reality of fusion is not too far off from the Hollywood
version. Fusion is the process of combining two atomic nuclei together to
create one new (heavier) atom. Its simplest form involves two hydrogen atoms
(one proton each) combining to form one helium atom (two protons). This process
of fusion produces massive amounts of energy, as exemplified most prominently
by the sun that heats our planet. The hydrogen bomb, which uses a nuclear explosion
to generate the high temperatures needed for the reaction, is the most
prominent working example of fusion we have.
(Fusion reaction. Credit:
CCFE-->)
Harnessing that energy in a useful (i.e. none destructive)
manner though is a real challenge for the physicists and engineers working to
build fusion reactors. To achieve high enough fusion reaction rates to make
fusion viable as an energy source, the fuel (two types of hydrogen - deuterium
and tritium) must be heated to form a plasma at over 100 million degrees
Celsius. Wow that's hot! When these
temperatures are achieved, the fuel begins fusing to create helium atoms. The
heat from fusion then provides the energy to sustain the plasma's temperature,
and the excess heat can be harnessed to heat steam to drive a turbine and
generate electricity.
The most promising fusion technology involves a machine
called a tokamak. The tokamak utilizes a ringed magnetic confinement system; a
circular bottle surrounded by strong magnetic fields. This confinement isolates
the plasma from the outside environment in order to maintain stable
temperatures and prevent contamination with impurities. Check this link for a picture of ITER: the
world's largest tokamak.
The latest developments in fusion technology involve the
Joint European Torus (JET), Europe's premier magnetic confinement fusion
facility based at Culham, UK. It has
completed eleven months of tests to simulate the environment inside the ITER
fusion facility being built in the South of France, and to prototype key
components. JET is basically a mini-version of ITER, using the same materials
for its wall - beryllium and tungsten. These materials have been carefully
selected in order to minimize plasma contamination and prevent fusion fuels
from becoming trapped in the wall.
(The interior of JET, showing its new wall of beryllium and
tungsten. Credit: EFDA)
Initial tests with beryllium and tungsten have proven that
they work much better than carbon-based wall materials. Specifically,
experimenters found the amount of fuel retained in the wall was at least ten
times less with the new design. These results may convince the ITER project to
skip its initial operation with carbon, which would save the project both time
and money.
Experiments at JET will restart in 2013, with the goal of
demonstrating full deuterium-tritium based plasma tests by 2015. This is an
exciting prospect for the development of the ITER, which plans to create its
own first plasma by 2020. The possibility of commercial fusion energy is definitely
a bright light amidst the clouded future of sustainability, and I will be
keeping my eye on the progress.
Paving the
Way for Commercial Fusion Power Plants - Science Daily
How
Fusion Works - CCFE
The Science -
ITER
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