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 anode and a plane cathode is performed. A number of radicals (excited molecules and atoms) produced by a streamer is calculated. The streamers near sharp and dull anodes are simulated. The sharp anode has five times smaller radius of tip curvature, and three times higher Laplacian field at the tip than the dull one. The results show that near the sharp anode, the streamer produces radicals ten times faster and at lower energy cost than near the dull anode. The mean energy cost of one radical is 10 eV