In today’s Academic Minute, Dr. Jose Lopez of Seton Hall University explains the various uses for the little-known fourth state of matter, plasma.
Jose Lopez is an assistant professor of physics at Seton Hall University where he has conducted extensive research in the field of plasma physics. His primary focus is in the subfield of microplasmas, where he is recognized as an international expert. He holds a Ph.D. from the Stevens Institute of Technology.
Dr. Jose Lopez – Hot and Cold Plasma
In the beginning of the universe there was plasma, the very first state of matter. Mostly everyone is aware of only three states of matter: solid, liquid, and gas; which they directly experience daily. However, these states of matter are the rare exception and not the norm in the universe. In the visible universe a bit over 99% of matter exists in the form of plasma which is the most common state of matter in both mass and volume. All the stars including the Sun are plasmas. The interstellar nebulae and the vast space between planets, stars, and galaxies are filled with plasma. On earth, plasmas are rarer, but extremely hot fires, lighting, and the polar auroras are examples of terrestrial plasmas.
Once humanity began to understand plasmas, then various artificial or man-made plasmas started to come about. A bit over a century of study has revealed that plasmas can be broadly put into two energy categories: thermal or hot plasmas and non-thermal or cold plasmas. Examples of hot plasmas are welding torches or rocket propulsion exhaust. Cold plasmas are found inside fluorescent lamps, neon signs, and the little pixels that make up the screen images in plasma televisions.
It is in this latter category of cold plasmas, where a technological revolution is occurring! These types of plasmas are currently used in semiconductor device or microchip fabrication and in various processing techniques such as applying protective coatings or film to materials. However, most of the mentioned devices and processes that use plasmas are created at low- pressures which require complex and expensive systems to recreate conditions similar to those of outer space. A new and very exciting type of plasma are known as microplasmas. Microplasmas are cold plasmas that can be generated at earth atmosphere conditions. The ability to make plasmas in regular earth pressure and in some conditions even with air has opened a new realm of plasma technologies. Microplasmas are currently used to generate ozone used for drinking water cleaning used by cities all over the world. Microplasmas are potentially poised to be providing solutions to for various environmental and even medical problems.