Abstract: Apparatus for generating with AC excitation, a substantially uniform electric field within a predetermined volume, typically in a region of a gas discharge device. The apparatus comprises an electrode assembly including a plurality of elongated electrodes disposed, equidistantly from one another and angularly displaced around a common axis so as to define the region of discharge. An approximately uniform discharge field is created within the discharge region by applying a harmonically varying potential to the electrodes, the phase of the applied potential at each electrode being a function of the relative angular position of that electrode.