Continuously flowing mixture of hot gases with a stationary position that derives its heat content from a strongly exothermic, irreversible chemical reaction between a fuel and an oxidant.

Table 1 Terms relating to flames in flame atomic spectroscopy

Term	Definition	Note
fuel	Reducing agent that reacts with oxidant to provide the energy necessary for atomization and excitation.
laminar flame	Flame for which the gas flow rate is sufficiently low such that the incoming gaseous flow of fuel and air is laminar, as is the flame.	The cross-section of the flame can have any shape.
oxidant	Oxidizing agent that reacts with the fuel providing the energy necessary for atomization and excitation.
oxidzing flame	Flame obtained using an excess of oxidant.
reducing flame	Flame obtained using an excess of fuel.
separated flame	Flame in which the secondary-combustion zone is separated from the primary-combustion zone.
turbulent flame	Flame in which the burnt-gas flows in an irregular pattern.