So much space! Need to see it all!
Nuclear fusion: a process so simple, but even
with today's technology, we are not able to
harness it.
I'm in space!
Yes, we are in space. This is a star-
Spaaaaace!
The birthplace of solar systems and generators
of matter.
I'm in space!
This is where fusion happens every second
of every day. But what exactly is it?
Fusion is the process by which two or more
atomic nuclei fuse together to form a heavier
nucleus. This action often releases an unparalleled
amount of energy. Only the fusion of two nuclei
with lower masses than iron release energy.
This means that fusion almost always occurs
among lighter elements. There are some exceptions,
however, like supernovas. Fusion is so difficult
that we are not able to significantly replicate
it on earth, even with protium, the very light
isotope of hydrogen that undergoes fusion
in stars.
Military research began with the Manhattan
Project in the 1940s, but was not accomplished
until 1951, and the first large-scale fusion
explosion was carried out in the Ivy Mike
hydrogen bomb test in 1952. It takes an incredible
amount of energy to force atomic nuclei to
fuse together, considering they are both positively
charged; however, with the right amount of
force--and a considerable amount of luck--is
provided, the nuclei will ignore the electrostatic
forces that normally apply, and the nuclear
strong force will cause the nuclei to stick
together. Because of this, the most common
fusion-capable isotopes are deuterium and
tritium, from hydrogen. Tritium is an incredibly
heavy, radioactive isotope of hydrogen with
a half life of around 12 years. This fact
means that there is not enough tritium on
earth to support many fusion power plants--about
2.5 to 3 kilogrammes worldwide; it is artificially
produced, however, by bombarding lithium with
neutrons. Deuterium is a common form of hydrogen
and can be obtained by separating it from
water. Fusion is going to look something like
this:
As some of you may know, that video isn't
necessarily accurate. When deuterium and tritium
fuse, the result is a helium nucleus and a
free neutron. The escaping neutron contains
an enormous amount of energy. Because it is
so difficult to fuse, there is virtually no
chance of a chain reaction, making fusion
one of the safest forms of energy available.
Another plus is that the product of fusion
does not yield any radioactivity, unlike nuclear
fission.
Nuclear fusion is so efficient that around
two litres of water and around 250 grammes
of rock are enough to provide the energy for
a European family for an entire year. A project
being undertaken in France by scientist from
all over the world called "ITER" has the daunting
goal of developing a sustainable fusion power
plant. According to Prof. Dr. Ulrich Samm,
director at the Institute for Plasma Physics,
ITER will have a worthwhile result by 2035.
The goal: 500 MegaWatts from a burn time of
at least eight minutes.
The plasma that the scientists are working
with reaches temperatures of over 100 million
degrees centigrade. Although slightly difficult,
fusion can be performed on earth due to something
called the Tokamak principle. The Tokamak
is essentially a large, circular chamber,
shielded by magnetic coils. Invented in the
1960s in Moscow, it remains the most efficient
way to produce fusion power. Deuterium and
tritium gas are put into the vacuum chamber,
which represents the rewinding of the large
transformer in the middle of the ring. Many
millions of amperes turn the gas into a plasma,
burning at around 100 million degrees centigrade.
Plasma is a mixture of free electrons and
ionized atomic nuclei, which are the perfect
ingredients to produce fusion. You may be
thinking, "Wait! If the plasma is 100 million
degrees, why doesn't the chamber melt?" Well
that is due to the magnetic coils. Because
plasma is a mass of free electrons, it can
be contained within a magnetic field. Even
with the magnetic field, the walls of the
chamber will substantially heat up, so they
must be made of heat resistant materials,
like graphite and tungsten, which must be
tested under nearly every condition imaginable
to keep the reactor safe and operational.
Although fusion power is many years away,
there is no doubt in any physicist's mind
that is will be our future. Eventually, the
rising costs of fossil fuels will intersect
with the plummeting costs of alternative energy.
When that happens, mankind will be able to
support itself in ways so advanced that we
can't even imagine what will become of us.
The best part about it all: this will happen
in our lifetime.
