May 3, 2013

What Is Fusion?

Hi, my name is Emerald Robinson, and in this “What Is” video, we’re going to talk about nuclear fusion.

Keep in mind that fusion is different from fission, which is how we currently generate nuclear energy. During fission, the nuclei of atoms are split apart to release energy. With fusion, the nuclei of atoms are joined, or fused together to make a new, heavier nucleus. During this process, a great deal of energy is released.

The simplest and most common fusion reaction is the formation of helium from hydrogen. Under normal conditions, positively charged hydrogen protons repel each other. At extremely high temperatures, however, hydrogen molecules can reach speeds high enough to overcome this repellant force. When they collide, they make a molecule of helium, and release a vast amount of heat energy.

Want to see fusion in action? Look up! Stars, including our sun, are gigantic fusion reactors. Stars have an enormous mass. The tremendous gravitational force created by this mass produces enough pressure and heat to allow protons to fuse together into the nuclei of heavier atoms. Stars are so massive that there is enough “fuel” to allow this process to continue for billions of years.

Without fusion, there would be nothing in the universe except for hydrogen. All other elements, including the ones in your body, were forged billions of years ago in the cores of stars by fusion. So, in a way, you are made of the same “stuff” as stars.

Scientists hope someday to be able to harness nuclear fusion to create usable energy here on earth. Unlike fission, fusion does not produce very much radioactive waste. It also requires relatively inexpensive materials, and is much safer than fission. Also, fusion does not release carbon dioxide, unlike fossil fuels. But because fusion requires temperatures in the order of millions of degrees, and extremely high pressures, we won’t be able to use it to make energy anytime soon.

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