A plasma-processing chamber including pulsed gas injection orifices/nozzles utilized in combination with continuous flow shower head injection orifices is described. The continuous flow shower head injection orifices introduce a continuous flow of gas while the pulsed gas injection orifices/nozzles cyclically inject a high-pressure gas into the chamber. In one embodiment, a central computer may monitor and control pressure measurement devices and utilize the measurements to adjust processing parameters (e.g. pulse duration, pulse repetition rate, and the pulse mass flow rate of processing gases).