The efficiency of radicals production by positive streamer in air: The role of Laplacian field

Two-dimensional modeling of positive streamer in the air between a point an ode and a plane cathode is performed. A number of radicals (excited molecul es and atoms) produced by a streamer is calculated, The streamers near shar p and dull anodes are simulated. The sharp anode has five times smaller rad ius of tip curvature, and three times higher Laplacian field at the tip tha n the dull one. The results show that near the sharp anode, the streamer pr oduces radicals ten times faster and at lower energy cost than near the dul l anode. The mean energy cost of one radical is 10 eV.