Nuclear Fusion: Using the energy of the stars on Earth

The Principle

Collision: Deuterium and Tritium

How is it made? In Stars: The gravity pressure makes the atoms close enough for the fusion. The high temperatures keep the plasma state making the collisions easier. On Earth: The super gravity of the stars can’t be

reproduced, so the temperature must be risen a lot, about ten times the sun’s center. The atoms will move so fast the collision and fusion will happen.

The Process Exactly the opposite of the conventional fission energy, with some advantages over it: the radioactive nuclear waste has low intensity and vanish in a few years, beyond that, there’s no risk of disasters As the fission, represents no harm for the nature

Why it’s not used? No nuclear reactor until now has made it to

produce more energy than the needed for its running.

The first prototype with chance to achieve this goal is the ITER (International Thermonuclear Experimental Reactor) which is being build in France since last year.

Difficulties - ITER The difficulties start with the lack of tritium on earth, it’s estimated that there are only 20 Kg of this isotope. The solution found was put the machine itself to produce it, they will try to use lithium, once when the energized neutron hits it, tritium is liberated.

ITER - Temperature Three systems will be used to reach the required

temperature: First neutral particles are injected in high speed The second will emit radio waves in different

frequencies,similar to micro-waves ovens And the third will use a beam of eletromagnetic

radiation to make hot the electrons inside the machine.

Keeping the temperature However, none of this will work if the plasma touch the internal structure of the machine. The trade of heat between the wall and the hydrogen would cold the last one, stopping the whole process That’s why it represents no risk, if anything fails

the machine turns off.

ITER The reactor model to avoid this contact used in ITER is called ‘tokamak’.It’s used nowadays in JET, the reactor that was used as a base for ITER’s project. It has the shape of a tyre, with vacuum and a

strong magnetic field, 200 000 times the earth’s one.

This will keep the plasma far from the structure walls

ITER’s Scheme

Alternatives of fusion In USA we have two inertial fusion reactors: The laser beams, where 192 laser beams hit a small ball the size of a pea, fusing the atoms inside. Electrical chock used in the Z machine: electrical

discharges of high power to make the fusion

Alternatives of fusion And the Stellarators, in Japan, who works as the

tokamaks, the difference is in the spiral shape which distributes better the magnetic field.

Future ITER will be ready in 8 years time, it’s

expected to produce ten times more energy than it consumes.

If it succed ,the project of Demo, the first fusion reactor with commercial goals, will start, it’s predicted to be operating in 2040.