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.

Mitigating reverse emission in electroaerodynamic thrusters

“…Other studies have also noted the presence of reverse emission, attributing it to a corona discharge at the collector [18,20] or to streamer discharges [21]. In Xu et al [18], our group showed that reverse emission causes deviations from the predictions of EAD theory: in particular, more power is required to produce a given thrust than predicted by theory.…”

“…As suggested by Lemetayer et al [21], deviations in either I Vabe or FN Vabe from the linear relationship with voltage can be interpreted as evidence of reverse emission.…”

“…Whereas it has been reported that reverse emission increases current (and hence power draw) at a given voltage [18][19][20][21][22], the effect on thrust is not as clear: Masuyama and Barrett [20] and Xu et al [18] argue that reverse emission results in reduced thrust as compared to if it were absent, while Monrolin et al [19] state that it does not affect thrust. Lemetayer et al [21] report that they did not observe an increase in thrust corresponding to the increase in current due to reverse emission; they attribute the absence of a thrust increase to the effect of a reverse ionic wind from a reverse corona discharge. To the best of our knowledge, no study comparing the thrust characteristics with and without reverse emission has been conducted.…”

Blade emitters for atmospheric ionic thrusters

“…First and foremost, the phenomenon of multiple emitters unscalability represents the main scientific limit for such thrusters. In fact, in several systems [13][14][15][16][17] it has been observed that increasing the number of the emitters does not lead to a proportional increase in the ionic wind, because an array of emitters at the same potential may create a local region of low potential gradient with detrimental effect on the emitter-collector field, and this effect can be worsened by the hydrodynamic interactions between parallel ionic wind jets. This shielding effect, mathematically described as a deviation from Peek's inception law [18], increases the inception voltage of the emitters.…”

Enhancement of thrust force of an atmospheric pressure positive corona discharge by DC superimposed AC high voltage

“…In recent years, several studies have been done on the use of corona discharge as a propulsion system [31][32][33][34][35][36][37][38]. In 2011, Martins and Pinheiro investigated the nature of the driving force in a positive corona discharge using an asymmetric capacitor geometry.…”