Ignition of single microhollow cathode discharge devices and arrays in diamond

In order to study the ignition phase of microplasmas, we studied the ignition process in mi-crohollow cathode devices that were fabricated with different materials and with a range of dimensions. Materials included diamond, deposited in layers using a CVD process, and sili-con, fabricated using standard plasma deposition and etching techniques. For these devices, the anode-cathode separation was less than 10µm, while the cylindrical microcavities ranged from 5 to 140µm in depth, and from 10 to 70µm in diameter. These discharges were char-acterised by imaging the plasma emission and analysing emission spectra. In order to study ignition processes, the devices were operated in a pulsed DC mode, with careful measure-ments of the plasma emission over the first few microseconds of each pulse. Measurements in these devices were compared with those made in larger scale devices. 1