Picosecond CARS System for Measurement of Electric Field and Vibrational Distribution Fuinction in Hihg Pressure Nanosecond Pulsed Plasmas

Recently, Ito, et al (J. Phys. D: Appl. Phys., 43, 2010) have demonstrated the ability to measure electric field in high pressure N$_{2}$ containing plasmas by Infrared Coherent Anti-Stokes Raman Spectroscopy (CARS), with temporal resolution of $\sim $10 nanoseconds. In this poster, progress towards a new IR CARS instrument for electric field measurements, with temporal resolution of $\sim $150 psec, will be described. The instrument utilizes a broadband, modeless, psec dye laser which outputs broad spectral band output centered at near 604nm, with a full-width half-max bandwidth of approximately 7 nm. The Nd:YAG pump laser generates $\sim $150 psec duration pulses using an internal Stimulated Brillouin Scattering pulse compression cell, and is capable of 2$^{nd}$ harmonic (532 nm) output energy of up to 120 mJ/pulse. As a first example of the sensitivity of the system, Vibrational Distribution Functions (VDFs) of nitrogen in CO/N$_{2}$ CO laser optically pumped plasmas, at pressures as low as a few Torr, will be presented. An overview of planned electric field measurements in quasi-one dimensional nsec pulse discharges and in Fast Ionization Wave (FIW) discharges, in which the field profile is predicted to evolve in space and time on sub-nanosecond time scales, will also be presented.