Time-resolved measurements of electric field, electron temperature, and electron density in a nanosecond-pulsed dielectric barrier discharge

Non-equilibrium low temperature plasmas are characterized by low neutral gas temperatures and highly energetic electrons that excite, ionize, and dissociate the neutral species. To understand the electron dynamics, the source of the electron energy, the electric field, and the electron properties, their temperature and density, must be measured in the same plasma. With these three parameters, a complete picture of the electron dynamics can be obtained. The electric field was measured using electric field induced second harmonic generation (E-FISH), while the electron temperature and density was measured through incoherent Thomson scattering. It was found that shortly after breakdown, a secondary discharge may have occurred to bring the electron density to measurable levels. Furthermore, the electrons did not decay below 0.5 eV even though the electric field was nearly zero, indicating superelastic collisions with Ar metastables could be important for heating the electrons.