Microdischarge array-assisted ignition of a high-pressure discharge: Application to arc lamps

An array of cylindrical microdischarges has been demonstrated to significantly improve the ignition characteristics of a high-pressure arc discharge by preionizing the anode-cathode gap. Situated behind the cathode, the microdischarge array serves to reduce both the statistical and formative time delays by providing seed electrons in the critical early phases of the startup of a cold lamp. Experiments conducted in Ar and Ne/2% Xe mixtures at pressures ranging from 35 to 600 Torr with spacings between the tungsten electrodes of 1-3.5 cm show that a three element array of 400-mum-diam cylindrical microdischarges lowers the dc ignition voltage for the lamp by at least a factor of 2 when the Ar pressure is between 50 and 75 Torr. The required voltage is constant over a broad range in Ar pressure (35 to similar to 90 Torr) and similar results are observed with 200-mum-diam microdischarges and for lamp ignition in Ne/2% Xe gas mixtures. (C) 2001 American Institute of Physics.