Modeling gas discharge plasma

The condition for a self-sustained gas discharge plasma (GDP) is expressed in an ionization balance form due to Townsend and used as a definition of gas discharge plasma in its simplest form possible. The simplest example of the positive cylindrical discharge column is used to demonstrate a wide variety of possible GDP regimes, revealing a contradiction between the large number of real process responsible for the self-sustainment of GDP and the way simple models explain gas discharge regimes. The variety of GDP processes also results in that some instabilities occur and plasma parameters change stepwise as the voltage or discharge current is varied. As a consequence, new forms and new applications of gas discharge arise as technology progresses.