An AC, rf, or pulse-excited microdischarge device and array are provide by the invention. A preferred array includes a substrate. A plurality of microdischarge cavities that contain discharge medium are in the substrate. A transparent layer seals the discharge medium in the microdischarge cavites. Electrodes stimulate the discharge medium. The microdischarge cavities are physically isolated from the electrodes by dielectric and arranged relative to the electrodes such that ac, rf, or pulsed excitation applied to the electrodes stimulates plasma excitation of the discharge medium. The microdischarge cavities are sized to produce plasma within the microdischarge cavities.