premix burner

in flame spectroscopy
https://doi.org/10.1351/goldbook.P04815
A burner in which fuel and oxidant are thoroughly mixed inside the burner housing before they leave the burner ports and enter the primary-combustion or inner zone of the flame. This type of burner usually produces an approximately laminar flame, and is commonly combined with a separate unit for nebulizing the sample.
Source:
Orange Book, 2nd ed., p. 165 (https://media.iupac.org/publications/analytical_compendium/)