The Menlo Roundtable

Properties of Glow Discharge Plasma Created with High Voltage at Low Pressure

The goal of this project is to make plasma physics more accessible, and to be able to observe and do research on a state of matter not otherwise found on Earth by building a vacuum chamber that causes electrical breakdown of the gas inside and produces glowing plasma, allowing plasma experiments to be done.

People come into contact with solids, liquids, and gases constantly in everyday life. This project will allow students to observe and gain knowledge of a fourth state of matter that they do not come into contact with but that is a prevalent state of matter in the universe.

The word “plasma” comes from the Greek πλασμα, which means “anything formed or molded.” Plasma was first named in 1927 by chemist Irving Langmuir while he was studying electrical discharge through gaseous mercury. He realized that the ionized gas seemed to carry electrons from one electrode to another just like blood plasma carries red blood cells and white blood cells through the body, so he proposed to give the name “plasma” to electrically discharging gases. Plasma is commonly made on Earth by electric arcs; lightning, shocks from static electricity, Tesla coils, and welding all create examples of electric arc plasma. However, there is a plasma that is more controlled and easily interacted with: glow discharge plasma. Glowing plasma is created at higher voltage and lower current than arc plasma, and is easier to sustain and observe. This plasma chamber will also provide a testbed for experimentation and plasma research. How is plasma affected by magnetic fields? How does the geometry of the chamber’s electrodes change the formation of plasma? These are the questions that this chamber is designed to answer, among others.