Streamer parameters and breakdown in CO2

CO₂ is a promising gas for the replacement of SF₆ in high-voltage transmission and distribution networks due to its lower environmental impact. The insulation properties of CO₂ are, therefore, of great interest. For this, the properties of streamers are important, since they determine the initial discharge propagation and possibly the transition to a leader. The present experimental investigation addresses the streamer inception and propagation at ambient temperature in the pressure range 0.05-0.5 MPa at both polarities. Streamer parameters, namely the stability field, radius and velocity, were deduced in uniform and in strongly non-uniform background fields. The measured breakdown fields can then be understood by streamer propagation and streamer-to-leader transition.