"So Why Can't We Just Use Fusion Now?"

Although fusion power sounds extremely attractive right now, it still has not been developed into a viable energy source. The reason is because it isn't as simple as it sounds. Tritium and deuterium atoms don't (thank goodness) randomly collide and give off energy. They must be heated up to extremely high temperatures (around 100 million degrees!) in order for fusion to take place.

So why can't we just heat them up? Well, when matter is present at the high temperatures necessary for fusion, it changes into another form. We're all familiar with the 3 main states of matter: solid, liquid, and gas. Each succeeding state is more energetic than the last. The atoms of a substance in the gaseous state move about much more than those of a substance in the solid state. Plasma, what has been called the "fourth state of matter," consists of a cloud of charged particles and is the most energetic of the four states of matter. Plasma is the most common form of matter in the universe. In fact, stars are made mostly of plasma. Examples of this unique state of matter here on earth include lightning, neon signs, and ordinary flames.

Because plasma exists only at such high temperatures, the electrons in the atoms of a substance in the plasmid state have enough potential energy to "break free" of the nucleus. Thus, the plasma is said to be made up of a cloud of positively and negatively charged particles. The positive ions are the atoms minus the electrons (and thus have a net positive charge). The negative particles are of course the electrons themselves that have been stripped from the atoms.

One characteristic of matter in the plasma state is how difficult it is to confine. Naturally, anything present at such high temperatures is very energetic and therefore moves around a great deal, and anything that moves around a lot is hard to confine. The containment problem has become one of the biggest setbacks to the use of fusion power on earth.