Abstract
Non-intrusive sensing technique for ions' motion in gas flow was developed using coherent anti-Stokes Raman scattering (CARS) generated by a femtoseconds pulse laser. Negative ion was injected into CO_2 flow and the concentration, measured by an ion counter, increased with increasing values of supply pressure of CO_2. It was observed that the CARS intensity of ionized CO_2 was smaller than that of CO_2. Further experiments will be required to investigate the relationship between the ion concentration and the CARS intensity.
