apparatus for generating ions in a gaseous medium , the apparatus including two electrodes separated by a dielectric material and a means for generating radio frequency pulses . the electrodes are of dissimilar size and are attached to opposite sides of the dielectric material . the smaller electrode shape and circumference is configured to control the quantity of plasma that is produced . method of generating ions in a gaseous medium having the step of applying a radio frequency voltage between two electrodes separated by a dielectric material so as to generate a plasma ion source . locating the plasma ion source in a confined area to yield no 3 - ions . locating the plasma ion source in an open configuration to yield predominantly co 3 - ions with minor amounts of o 2 - and o 3 - ions .