N 2 ( A Σ u + 3 ) time evolution in N2 atmospheric pressure surface dielectric barrier discharge driven by ac voltage under modulated regime

The relaxation of N2(AΣu+3) metastable in N2 ac (5 KHz and 7 KVpp) surface dielectric barrier discharge driven under pulse modulated regime, TON=5 ms and TOFF=20 ms, at atmospheric pressure has been investigated. N2(A) has been detected by optical-optical double resonance laser induced fluorescence in a space layer (space afterglow) at 1 mm above the discharge electrode. The time evolution clearly shows that in the space afterglow layer N2(A) builds up and decay in millisecond time scale and does not vary in the voltage cycle.