Collision and diffusion in microwave breakdown of nitrogen gas in and around microgaps

Campbell, James D.; Bowman, Amanda; Lenters, Geoffrey T.; Remillard, Stephen K.

doi:10.1063/1.4862680

Cited by 9 publications

(2 citation statements)

References 23 publications

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“…Later, this equation was applied to the analysis of experimental results obtained in nitrogen at the atmospheric pressure. 14 However, onedimensional Particle-in-Cell Monte Carlo collisions (1D PIC/MCC) simulations of microdischarges carried out in Refs. 11 and 12 show that at atmospheric pressure Eq.…”

Section: And References Therein)mentioning

confidence: 99%

Effect of frequency on microplasmas driven by microwave excitation

Levko

Raja

2015

Journal of Applied Physics

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The effect of excitation frequency on the breakdown voltage of a microwave (mw) microdischarge and its steady-state plasma parameters is studied by the self-consistent one-dimensional Particle-in-Cell Monte Carlo collisions model. It is found that for microdischarges in which the electron wall losses are significant, an increase in the mw frequency results in a decrease in the breakdown voltage. For conditions in which the electron wall losses become negligible, an increase in the frequency does not influence significantly the breakdown voltage. At the same time, for both regimes, the increase in the frequency results in an increase in the steady-state plasma density. The analysis of the steady-state plasma parameters have shown that the dominant electron heating mechanism is the Joule heating while the stochastic heating is negligible. Also, it is found that the electron energy distribution function consists of two electron groups, namely, slow and fast electrons. The presence of fast electrons in the plasma bulk indicates the non-local nature of microwave excited microdischarges.

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Section: And References Therein)mentioning

confidence: 99%

Effect of frequency on microplasmas driven by microwave excitation

Levko

Raja

2015

Journal of Applied Physics

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“…However, studies of the influence of materials, fabrication methods, and microstructure are absent at atmospheric pressure. In addition, despite studies of parallel-plate style microwave electrodes with varying interelectrode gaps [22][23][24], there is a dearth of experimental work concerning SRRs or coplanar electrodes with different gap sizes below 100 μm. The study of small gap sizes becomes especially important since field emission is expected to become increasingly more likely as interelectrode spacing is reduced.…”

Section: Introductionmentioning

confidence: 99%

Weibull analysis of atmospheric pressure plasma generation and evidence for field emission in microwave split-ring resonators

Cohick

Hall²,

Wolfe

et al. 2020

Plasma Sources Sci. Technol.

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The generation of atmospheric pressure microplasmas using microwave resonators is promising for many applications due to the possibility of high electron densities and low electrode degradation. In particular, such plasmas may help enable reconfigurable metamaterials operating from GHz to THz. Since plasma metamaterials may require the generation of tens to hundreds of plasmas, it is important to find ways to reduce the power required for plasma breakdown. Here, we study gold and silver microwave split-ring resonators (SRRs) with a variety of materials near the interelectrode gap (Cu, CuO nanowires, aluminum oxide). We focus on those fabricated using a traditional thick film technique, screen-printing, and using fs-and ns-laser ablation. The use of laser ablation allows us to explore small interelectrode gap sizes (7-100 μm) and the use of different lasers and laser parameters enables us to produce a variety of microstructures. We utilize Weibull statistics to examine breakdown in atmospheric pressure Ar with and without deep ultraviolet illumination of SRRs. Fabrication methods and materials are shown to influence both Q-factor of the SRRs and breakdown voltage independently. It is found that superior performance in terms of breakdown voltage and consistency in breakdown is related to Weibull modulus. The power requirement for breakdown varied as widely as an order of magnitude depending on fabrication method and material used for the SRRs. Furthermore, we consider the performance differences seen between various resonators and relate this to microstructure/ material which suggests that field-emission may play a role in providing the seed electrons required for breakdown. This need for seed electrons appears to be especially important for gap sizes of 40 μm and smaller.

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Breakdown of atmospheric pressure microgaps at high excitation frequencies

Levko

Raja

2015

Journal of Applied Physics

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Microwave (mw) breakdown of atmospheric pressure microgaps is studied by a one-dimensional Particle-in-Cell Monte Carlo Collisions numerical model. The effect of both field electron emission and secondary electron emission (due to electron impact, ion impact, and primary electron reflection) from surfaces on the breakdown process is considered. For conditions where field emission is the dominant electron emission mechanism from the electrode surfaces, it is found that the breakdown voltage of mw microdischarge coincides with the breakdown voltage of direct-current (dc) microdischarge. When microdischarge properties are controlled by both field and secondary electron emission, breakdown voltage of mw microdischarge exceeds that of dc microdischarge. When microdischarge is controlled only by secondary electron emission, breakdown voltage of mw microdischarge is smaller than that of dc microdischarge. It is shown that if the interelectrode gap exceeds some critical value, mw microdischarge can be ignited only by electrons initially seeded within the gap volume. In addition, the influence of electron reflection and secondary emission due to electron impact is studied.

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Collision and diffusion in microwave breakdown of nitrogen gas in and around microgaps

Cited by 9 publications

References 23 publications

Effect of frequency on microplasmas driven by microwave excitation

Effect of frequency on microplasmas driven by microwave excitation

Weibull analysis of atmospheric pressure plasma generation and evidence for field emission in microwave split-ring resonators

Breakdown of atmospheric pressure microgaps at high excitation frequencies

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