GLOW DYNAMICS IN A SEMICONDUCTOR-GAS DISCHARGE IMAGE CONVERTER

Transient phenomena which accompany the breakdown of gas in a semicond uctor-gas discharge (SGD) system with 100 mu m interelectrode distance have been studied experimentally and with numerical calculations. Thi s system serves as the basis for an image converter operating in the i nfrared (IR) spectral region. The experiments are done for a cryogenic discharge in helium at a temperature close to that of liquid nitrogen . Depending on specific experimental conditions, oscillatory or aperio dic modes approaching to the steady-state current are observed after b reakdown has been induced by a step-like voltage pulse. Numerical;calc ulations of transient phenomena were performed for experimental condit ions within the framework of the Townsend model, taking into account d irect ionization, Penning ionization and secondary emission of electro ns from the cathode. The main feature's of discharge kinetics obtained are in accordance with experimental data. At the same time, with. the steady-state discharge current density varying from j=1X10(-4) A/cm(2 ) to 7x10(-2) A/cm(2), inconsistencies between experimental and theore tical results are observed. A possible reason for this discrepancy is related to the complex process of secondary ionization at the cathode under the conditions of a cryogenic discharge and to the dependence of the secondary electron emission factor on current density, that has b een neglected in constructing the model. The results obtained are cons idered from the viewpoint of the response time bf gas-discharge IR ima ge converters. (C) 1997 American Institute of Physics.