Fire (flame)

From (The Plasma Universe Wikipedia-like Encyclopedia)

Flames (fire) are a plasma. Copyright Contemporary Physics Education Project

Fire (flames) is a commonly produced plasma, albeit one that is a partially ionized plasma, and dominated by collisions.

The Contemporary Physics Education Project produces a poster on plasmas (see right) in which flames (ie. fire) is shown as a plasma.^[1]

In his book, Introduction to Plasma Physics and Controlled Fusion, Francis F. Chen notes:

Any ionized gas cannot be called a plasma, of course; there is always a small degree of ionization in any gas. A useful definition is as follows: A plasma is a quasineutral gas, of charged a neutral particles, which exhibit collective behavior. ^[2]

He further goes on to describe three parameters that need to be satisfied in order to identify a plasma. These include (1) the plasma approximation (2) Bulk interactions (3) Plasma frequency. In his book, Chen goes on to assess whether certain phenomena are indeed plasma, based on the three parameters, and concludes that a typical flame does indeed meet the criteria of being a plasma.^[3]

In practice then, fire is a highly-collisional, partially ionized plasma in which the collisions might mask some of the collective behavior.

Footnotes