The present study aims at showing the ability of ac discharges to be used as fanless blower in a rectangular channel. First, a 10 mm-high channel is used with four different types of ac atmospheric air discharges: an ac wire-to-plate corona discharge, two different ac wire-to-plate dielectric barrier discharges (DBD) and a surface DBD. The electrical and mechanical characteristics of the four different discharges are investigated and compared. They highlight that the best geometrical configuration is the wire-to-plate DBD with a thick dielectric, that allowed us to induce ionic wind velocity up to 3.3 m/s and flow rate per unit spanwise length of 24 L per second per meter. Secondly, this optimized configuration is reduced in size (2 mm-high channel) and the effect of this downscaling on the plasma actuator performances is studied, showing that the efficiency decreases with the channel height. (C) 2017 Elsevier B.V. All rights reserved.