A Brief History and Chronology of Plasma

The term “plasma” in human physiology refers to the Human blood; it consists of red cells, white cells, and platelets in a liquid; this fluid is relatively clear, yellow-tinted water ( \(92+\) %), sugar, fat, protein, and salt solution. Normally, 55% of blood’s volume is made up of this liquid. When blood is cleared of its various corpuscles, there remains this transparent liquid, which was named plasma (after the Greek word \(\pi \lambda \alpha \sigma \mu \alpha \) , which means “moldable substance” or “jelly”). Irving Langmuir first used this term to describe an ionized gas—Langmuir was reminded of the way blood plasma carries red and white corpuscles by the way an electrified fluid carries electrons and ions. Langmuir, along with his colleague Lewi Tonks, was investigating the physics and chemistry of tungsten-filament light bulbs, while achieving a method to extend the lifetime of the filament. In the process, he developed the theory of plasma sheaths—the boundary layers which form between ionized plasmas and solid surfaces. He also discovered that certain regions of a plasma discharge tube exhibit periodic variations of the electron density, which is termed Langmuir waves. This was the genesis of Plasma Physics. Langmuir’s research forms the theoretical basis of most plasma processing techniques for material processing. After Langmuir, plasma research gradually spread in other directions.