Alternating current heating of flame plasmas: A theoretical study

Abstract

Theoretical values of electron and ion heating of a flame plasma are presented as a function of the field frequency. High frequency regimes are identified in which, as the frequency is increased, first ion then electron heating rapidly declines. The inductive heating of a flame plasma within a straight cylindrical solenoid is examined. Centralized regimes are identified in which efficient and sufficient energy transfer occurs between the two circuits. Consideration of particular flame plasmas shows that effective operation of an induction system with chemi-ionized flame gases at radio frequencies requires excessively large burners. The diameter is reduced to more practical values at microwave frequencies. An appreciable increase in electrical conductivity, as a consequence of seeding with alkali metals, can lead to efficient operation with burners of a convenient size at radio frequencies.