Electric Field Measurements in Plasmas with E-FISH Using Focused Gaussian Beams

Electric field induced second harmonic (E-FISH) generation is a non-linear optical phenomenon which has recently been re-purposed as a diagnostic for non-intrusive electric field measurements in plasma assisted systems [1] , [2] . The method essentially relies on the second harmonic response of a centrosymmetric medium (viz. plasma) to an externally applied electric field. Second harmonic generation is prohibited in the absence of this applied field due to symmetry considerations. Since its conception, this method has been used to measure electric fields in a multitude of plasma configurations such as ionization waves, DC corona, pin-to-plane, and surface barrier dielectric discharges as well as atmospheric pressure plasma jets [3] .