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.

We measured the dynamic I–V characteristics and vacuum ultraviolet (VUV) emission lines of the second continuum in xenon (170 nm) and argon (130.5 nm) from pulsed microhollow cathode discharges (MHCD). For pulse lengths between 1 and 100 μs the dynamic I–V characteristics are similar in both inert gases. Only the time variation of the VUV emission line at 170 nm for xenon can be related to the dimer excited states. In argon the energy transfer between the Ar2* dimers and the oxygen impurity atoms is responsible for a qualitatively different time behavior of the resonance line at 130.5 nm. Consequently, the relative VUV efficiency reveals an inverse dependence on the electrical pulse lengths for the MHCD in xenon and argon, respectively.

A method for the direct measurement of the impedance of the oscillatory circuit which determines the character of certain self-sustained (natural) oscillations in a dc discharge is described. The results show that the impedance corresponds to an oscillatory parallel circuit with lumped constants.

No abstract

In a low-pressure discharge with a gas anode, under certain conditions, periodical phenomena can occur. These are maintained by superficial processes caused by fast electrons which collide with the walls of the tube in the negative glow region.In a d.c. gas discharge with metallic anode the same phenomena can occur; it is possible to give a unified explanation of these two phenomena.