An Instantaneous and Continuous Sodium-Line Reversal Pyrometer

The theory, development, and calibration of an electro-optical sodium-line reversal pyrometer are given. This pyrometer instantaneously and continuously determines and indicates the black-body temperature of a non-luminous flame made luminous at the sodium wave length by the addition of sodium. Typical data obtained on a spark-ignition engine are presented and compared with data obtained by previous investigators. A correlation of these data with combustion-chamber design indicates the possible existence of a high temperature in the flame front.