Is an extended barrier-free discharge under nanosecond-pulse excitation really diffuse?

Ren, Chenhua; Huang, Bangdou; Qiu, Jintao; Zhang, Cheng; Qi, Bo; Chen, Weijiang; Shao, Tao

doi:10.1088/1361-6463/ac4f0d

Cited by 13 publications

(11 citation statements)

References 55 publications

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“…Furthermore, the applying of low pressure makes the discharge in packed bed DBDs more uniform regardless of the dielectric material, filling the interstitial space instead of forming SIWs [23]. Meanwhile, nanosecond pulsed power supply is employed due to a promising strategy for obtaining homogeneous of diffuse discharges at atmospheric pressure [29].…”

Section: Introductionmentioning

confidence: 99%

Kinetic investigation of plasma catalytic synthesis of ammonia: insights into the role of excited states and plasma-enhanced surface chemistry

Sun¹,

Chen²,

Zhao³

et al. 2022

Plasma Sources Sci. Technol.

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The present work investigates the kinetics of catalytic ammonia synthesis in a N2/H2 mixture activated by a nanosecond pulsed discharge (NSD) plasma experimentally and numerically. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) are combined to characterize the morphology and surface electronic properties of the catalyst. Special attention is placed on the role of excited species in promoting the formation of important intermediates and the plasma-enhanced surface chemistry. A detailed kinetic mechanism consisting of atoms, radicals, excited species, molecules, ions, and surface species is developed and studied by incorporating a set of the electron impact reactions, reactions involving excited species, ionic reactions, direct and dissociative adsorption reactions, and surface reactions. A zero-dimensional model incorporating the plasma kinetics solver is used to calculate the temporal evolution of species densities in a N2/H2 plasma catalysis system. The results show that the coupling of Fe/γ-Al2O3 catalyst with plasma is much more effective in ammonia synthesis than the Fe/γ-Al2O3 catalyst alone and plasma alone. The numerical model has a good agreement with experiments in ammonia formation. The path flux analysis shows the significant roles of excited species N(2D), H2(v1), N2(v) in stimulating the formation of precursors NH, NH2, and adsorbed N(s) through the pathways N(2D) + H2 → NH + H, H2(v1) + NH → NH2 + H and N2(v) + 2Fe(s) → N(s) + N(s), respectively. Furthermore, the results show that the adsorption reaction N + Fe(s) → N(s) and E-R interactions N(s) + H → NH(s), N + H(s) → NH(s), NH + H(s) → NH2(s) and NH2 + H(s) → NH3(s) can kinetically enhance the formation of ammonia, which further highlights the plasma-enhanced surface chemistry. This work provides new insights into the roles of excited species and plasma-enhanced surface chemistry in the plasma catalytic ammonia synthesis.

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Section: Introductionmentioning

confidence: 99%

Kinetic investigation of plasma catalytic synthesis of ammonia: insights into the role of excited states and plasma-enhanced surface chemistry

Sun¹,

Chen²,

Zhao³

et al. 2022

Plasma Sources Sci. Technol.

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“…However, it is difficult to obtain the electric field distribution due to the space limitation of measurement methods holistically. Many simulation methods can cover the shortage of measurement methods on calculating the electric field distribution [12,13], such as the finite element method (FEM), finite volume method (FVM), and finite difference method (FDM). Researchers use the measured data as the boundary and initial conditions of the simulation model, and the measurement results are used for verification [14,15].…”

Section: Introductionmentioning

confidence: 99%

Physics informed neural networks for electric field distribution characteristics analysis

Zeng

Zhang

Ren

et al. 2023

J. Phys. D: Appl. Phys.

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Electric field calculations based on the Poisson equation have been widely used in high voltage and plasma technology. However, in practical applications, the electric field distribution in space is relatively complex, and the simulation technology based on the traditional method is often a simplification of reality, which leads to a large error between the simulation and the actual measured value. In the actual application process, due to the limitation of measurement methods, it is necessary to infer the electric field data at other locations in space according to the measurement results. Physics informed neural networks (PINNs) are introduced into the electric field calculation. PINNs are considered partial differential equation solver based on deep neural networks. In this paper, the electric field of 2-D and 3-D electric fields is discussed and compared with the the finite element method (FEM). A method of dividing the dielectric distribution based on the sigmoid function is proposed, which can be effectively used to construct the spatial electric field model of the homogeneous dielectric. The combination of the data and physical model based on PINNs uses to establish a method to solve the inverse problem of the relative permittivity in the electric field. The results show that PINNs can calculate the distribution of the electric field according to the physical equations and different types of constraints and parameters.

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“…Sufficient pre-ionization (seed electron density) in free space ensures the overlap of multiple electron avalanches before the streamer formation [9][10][11], which can be achieved by external sources, such as UV light, x-rays, electron beam, et al [12][13][14]. A nearly homogeneous discharge with a volume of several liters has been generated at atmospheric pressure by using x-rays as the pre-ionization source [14].…”

Section: Introductionmentioning

confidence: 99%

The critical effect of electron acceleration under enhanced electric field near cathode on the formation of runaway electrons and diffuse discharge in atmosphere

Ren,

Huang,

Zhang

et al. 2023

Plasma Sources Sci. Technol.

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Runaway electrons (RAEs) are believed to affect the dynamics of ultra-fast gas breakdown significantly. In this work, considering the field enhancement effect near the micro-protrusion on the cathode surface, the formation of RAEs and diffuse discharge in atmospheric pressure air is investigated by two-dimensional particle-in-cell/Monte Carlo collision simulation. It is found that the beam amplitude of RAEs is dictated by the field enhancement factor and the initial energy of electrons obtained near the micro-protrusion is decisive for their converting to RAEs, which precede the low energy electrons and guide the discharge propagation by improving pre-ionization. As a result, the discharge transfers from the filamentary mode without RAEs to the diffuse mode under the high pre-ionization degree due to RAEs and a wide streamer with a diameter comparable with the gap distance is formed, which transfers from spherical to conical shape. The results of this study illustrate the fundamental process of RAE formation and how RAEs influence streamer dynamics during ultra-fast gas breakdown process.

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Is an extended barrier-free discharge under nanosecond-pulse excitation really diffuse?

Cited by 13 publications

References 55 publications

Kinetic investigation of plasma catalytic synthesis of ammonia: insights into the role of excited states and plasma-enhanced surface chemistry

Kinetic investigation of plasma catalytic synthesis of ammonia: insights into the role of excited states and plasma-enhanced surface chemistry

Physics informed neural networks for electric field distribution characteristics analysis

The critical effect of electron acceleration under enhanced electric field near cathode on the formation of runaway electrons and diffuse discharge in atmosphere

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