1-D spatially resolved electric fields in atmospheric pressure nanosecond pulse discharges using ultrashort laser pulses

We present a novel experimental setup for electric field measurements in high pressure plasma discharges using the electric field induced second harmonic generation method (E-FISH). While the E-FISH effect has been known of for some time, recent advances in laser and detection technology have allowed the method to be utilized for spatial measurements of the electric field, opening the door to exciting new possibilities in the world of plasma physics. In this manuscript, a cylindrical lens is used to focus the femtosecond laser light to a line and an intensified charge coupled device (ICCD) is used for detection, allowing for 1-D spatial sensitivity on the order of ~50 µm. Measurements have been carried out verifying the spatial sensitivity using a spatially periodic, localized electric field. Additionally, calibrated electric field measurements have been completed in an Argon atmospheric pressure plasma jet powered by a nanosecond pulse dielectric barrier discharge. Calibrated electric field measurements have been completed with a time resolution of 500 picoseconds, and the field was shown to propagate as an ionization wave, with a speed of ~0.3 mm/ns.