Abstract: A method of stimulating chemical reactions within a fluid media uses a gas plasma ejected from a gas-buffered microhollow cathode discharge apparatus into the fluid media. The apparatus has an electrically-conductive housing with an electrode positioned therein such as to create air channels between the electrode and the housing. The electrode is electrically insulated from the housing except at a location near the plasma outlet. A DC voltage is applied across the electrode and housing to accelerate the plasma and eject it into the fluid media. In another aspect, the housing includes a cup portion and a conduit portion that are electrically isolated from each other. When a DC voltage is applied across the electrode and the conduit, the plasma is ejected and filamentous discharges occur between the cup and the conduit. Such multicavity coupled plasma discharges provide voltage amplification and DC pulses with rates in the nanosecond regime.