A
fusion reaction, on the other hand, occurs
when hydrogen nuclei collide and form a
heavier nucleus like helium. More energy
is required to "ignite" a fusion
reaction, but when ignited the excess energy
is far greater than in a fission reaction.
A major challenge for this type of reaction is the incredible temperatures that are needed. In the Sun's core and in the cores of all stars, temperatures can reach many millions of degrees (for our Sun, the core temperature is some 15 million °K with a density ten times that of lead).
To make fusion in the laboratory, temperatures need to exceed 10 million °K. That makes it very hard to confine the plasma. The fuel, on the other hand, is very plentiful. The only fuel required in a fusion reactor
is the heavy hydrogen found in seawater,
a virtually limitless source of energy.
If controlled fusion were to become reality
it would be one of the great breakthroughs
for civilization, especially in our modern world where humans are searching for alternative sources to oil-based energy. However, the scientific
and engineering problems associated with
a fusion reactor are great.
They
can be divided into three major categories:
| |
1. |
Confinement (How long does the plasma stay around?) |
| |
2. |
Heating (Does the plasma get hot enough?) |
| |
3. |
Technology (reactor design -- many problems remain
for future research) |
Listen to what happens when a fusion reactor is turned on.
Sounds courtesy of Los Alamos National Laboratory
|
