TEMPERATURE-MEASUREMENT BY SINGLE-SHOT DUAL-LINE CARS IN LOW-PRESSURE FLOWS

A CARS method, adapted for diagnostics in low-pressure unsteady flows is described. The technique employs two narrow-band dye lasers and a single-frequency pump laser. Single-shot rotational temperature is obtained from the ratio of the intensities of two isolated Q lines. Temperature-measurement accuracy is discussed. The advantage of referencing the CARS signals from the flow in a cell filled with the same gas is shown. Demonstrative experiments are performed using N2 at pressures of 10(2)-10(3) Pa.