Abstract: This invention improves the stability and control of high-pressure glow discharges by means of a microhllow cathode discharge. The microhollow cathode discharge, which is sustained between two closely spaced electrodes with an opening formed in the electrodes, serves as a plasma cathode for the high-pressure glow. Small variations in the microhollow cathode discharge voltage generate large variations in the microhollow cathode discharge current and consequently in the glow discharge current. In this mode of operation the electrical characteristic of this invention resembles that of a vacuum triode. Using the microhollow cathode discharge as a plasma cathode, stable, dc discharges in argon up to atmospheric pressures can be generated. Additionally, parallel operation of these discharges allows for the generation of large volume plasmas at high gas pressure through superposition of individual glow discharges.