West Chester University
Fusion is what powers the sun. If we could harness nuclear fusion on Earth, we would be assured of having enough energy for all future needs of mankind. However, the technical challenges are enormous leading some to suggest that fusion was, is and always will be the power source of the future.
Fusion is the process of creating a new nucleus out of two light ones. During the process, a small portion of matter is converted into energy according to Einstein's famous equation E = mc2. Very little mass is the equivalent of an enormous amount of energy.
In the sun, the primary fusion path is the reaction of two hydrogen nuclei (protons) to form a deuterium nucleus (a heavier isotope of hydrogen). The deuteron and another proton then fuse to form helium. The sun achieves this reaction because its gigantic mass gave it enough gravitational force to jam the protons together in the first place. Now that fusion has started, it also keeps the sun at ridiculously high temperatures. The high temperature ensure that when the protons collide they have enough energy to undergo fusion reactions.
Here on Earth it is difficult to recreate the conditions found in the Sun. Therefore, scientists such as those at the Princeton Plasma Physics Lab or the ITER, use a deuterium + tritium plasma (tritium is yet another heavy isotope of hydrogen). The energy required to fuse deuterium (D) and tritium (T) is much less than that required for proton + proton fusion. A machine known as a tokamak is used to create huge magnetic fields to confine the plasma of D and T ions and to heat them to millions of degrees.
Getting a D+T plasma to "burn" so that it releases more energy than is required to ignite it, to extract the released energy, and to turn this energy into electricity is no mean feat. To learn more about proposals to do this, go to the ITER introduction to fusion energy.