Microdischarges with plane cathodes

By reducing the dimensions of the electrodes to the submillimeter range, it is possible to operate dc gas discharges at pressures up to 760 Torr (argon). A plane geometry for the cathode, different from the well-known microhollow cathode discharge, was used in these experiments. For anode hole diameters smaller than 0.6 mm and pD (D diameter of the anode hole) larger than 9 Torr cm, the differential resistivity in the I-V characteristics is similar to the hollow cathode one. The emission in the visible range is distributed more homogeneously over the entire cathode surface. By using a end-on coupled configuration of hollow and plane cathode geometries, the discharge can be stabilized over the entire (pD) range between 1 and 23 Torr cm. The discharge is stable, for both the hollow-plane and hollow-hollow cathode configurations in aligned geometries. (C) 1999 American Institute of Physics. [S0003-6951(99)01651-4].