Multi-inception patterns of emitter array/collector systems in DC corona discharge

Abstract

Multiple emitters systems have been previously used so as to increase charge density in the drift region, many times without producing sensible increment neither in total current nor ionic wind. This contribution focuses on analyzing the detailed physics behind this failure, that is named ‘multiple emitters un-scalability’. It is established that multiple emitters un-scalability is related to the inability of multiple corona discharge inceptions when increasing the emitter number and/or density. This confirms recent findings that corona discharge inception is shielded by electro-static interactions between emitters. This contribution demonstrates that this shielding can be balanced by emitter/collector electrostatic interactions depending on the considered configuration. For sufficiently close collector-emitter distances, ignition starts at the array center, whereas, on the contrary, when the collector is distant, the ignition not only starts at the array’s periphery but might also be limited there. It is also demonstrated that emitter/emitter electrostatic interactions can be balanced by emitter/collector ones, depending of their chosen configuration. This lead to a variety of multi-inception patterns, the condition of which are analyzed. Intermediate configurations for which the collector is neither sufficiently close nor distant from the emitter array center provide a variety of multi-inception patterns that are hereby analyzed. Combining finite element computations of multi-inception drift-diffusion modeling with experimental measurements, provides a coherent picture explaining why multiple emitters sources systems do not lead to full ignition, and also exhibit conditions for which it does, leading to multiple emitters scalable systems.