BEYOND SURFACES

In our Spot on materials series, we have so far presented solid, tangible materials, such as nickel or titanium. This time, we focus on an “entity” (ancient Greek: plasma) without which modern surface solutions would be inconceivable. How is plasma formed? Plasma is the “fourth state of matter” after solid, liquid and gas. It occurs when a gas is supplied with addi- tional energy in the form of heat. The high temperatures cause the electrons to detach from the atomic structure, which creates a mixture of free particles — positively charged ions and negatively charged electrons. The more of these present in the plasma, the more “ionized” it is. The degree of the plasma’s ionization can range from 1 to 100%. Where is plasma found? In everyday life, we rarely observe plasmas, but this state of matter is very common throughout the universe. Our sun, which is millions of degrees hot at its core, consists of plasma, as are most stars. Gaseous nebulae and inter- stellar space are also largely made of this entity. Plasma does occur naturally on Earth — and when it does, it is spectacular! For example, the northern lights and rays of lightning are made of plasma: With temperatures of up to 30,000 °C, lightning can locally heat the Earth’s atmo- sphere to such an extent that atoms are split, and we see the resulting plasma as a brilliant flash of light. Like the other states of matter, plasma and its power have been harnessed by mankind for a number of tech- nical uses. But, in order to be used for these purposes, the plasma must be generated artificially. The energy required for this is usually supplied by an electrically- charged gas or strong laser beams. p l A S m A 26