When the pressure of the gas medium in which the microplasma is generated increases, the distance between the electrodes must decrease to maintain the same breakdown voltage. In such microhollow cathode discharges, the product of pressure and distance ranges from fractions of Torr cm to about 10 Torr cm. At values below 5 Torr cm, the discharges are called "pre-discharges" and are low intensity glow discharges.