Children of the stars, plasma is the fourth state of matter

Everywhere we look, there is plasma. But we stand on solid earth and this solid state accounts for less than one percent of the total mass of the Universe. Almost all of the rest is plasma, a hot ionised gas containing positive and negative charges (except, perhaps, for dark matter). Plasmas have existed since the very first moments of the Universe. It is the stuff of stars; it even fills the space between stars. It gives us the beautiful northern and southern aurorae. By properly harnessing the plasma state in the laboratory we can make plasma lights (fluorescent tubes), microchips for computers and mobile phones, plasma space engines and hydrogen fuel cells. Plasma applications also include arc welding, waste treatment and plasma coatings in the manufacture of biomaterials. In this chapter, I will introduce plasmas and their applications in various fields of physics. Here we are not dealing with blood plasmas, but instead with a hot ionized gas containing atoms, ions, electrons and photons which carry the light to your eyes. First we will use water to explain the basic plasma constituents and reactions, including fusion reactions that occur in the Suns core. After identifying some of the plasmas occurring naturally around us, I will show some methods we can use to create and control plasmas in the laboratory. I will then discuss a few applications of laboratory plasmas in the fields of lighting, space travel, renewable energy, welding and biotechnology. At the end I will show some low cost experiments that can be constructed in high schools to illustrate the basic properties of plasmas.