Gas Heating Mechanisms in Atmospheric Pressure Helium Dielectric-Barrier Discharges Driven by a kHz Power Source

Kun-Mo Lin,Shun-Yu Chuang,Yao-Sheng Chang,Kai-Cheng Wang

doi:10.3390/app10217583

Kun-Mo Lin, Shun-Yu Chuang + Show 2 more

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https://doi.org/10.3390/app10217583

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Journal: Applied sciences	Publication Date: Oct 28, 2020
Citations: 3	License type: CC BY 4.0

Affiliation: National Chung Cheng University

Abstract

The present work investigates contributions of different heating mechanisms and power efficiency of atmospheric-pressure helium dielectric-barrier discharges (APHeDBDs) containing a small amount of N2 for temperature measurements by developing the numerical methodology combining the one-dimensional (1D) plasma fluid model (PFM) and 3D gas flow model (GFM) with simulated results validated by measurements including the discharge power consumption and temperature distribution. The discharge dynamics are modeled by the 1D PFM for evaluating the average heating source considering elastic collision, ion Joule heating, and exothermic reactions as the source term of energy equation solved in the 3D GFM. The simulated current density reaches 29 A m−2 which is close to that measured as 35 A m−2. The simulated power consumption is 2.0 W which is in good agreement with the average measured power consumption as 2.1 W. The simulated average gas temperature in the reactive zone is around 346 K which is also close to the rotational temperature determined. The analysis shows that elastic collision and ion Joule heating are dominant heating mechanisms contributing 23.9% and 65.8% to the heating source, respectively. Among ion species, N2+ and N4+ are dominant species contributing 44.1% and 50.7% to the heating source of ion Joule heating, respectively. The simulated average total heating source is around 5.6 × 105 W m−3 with the maximum reaching 3.5 × 106 W m−3 in the sheath region due to the contribution of ion Joule heating.

Highlights

Atmospheric pressure helium dielectric-barrier discharges (APHeDBDs) have been developed intensively in different fields including surface treatments [1,2,3] and plasma medicine [4,5,6] due to the efficient generation of reactive species and stable operating conditions
The average volumetric heating source calculated by the 1D plasma fluid model (PFM) is adopted as the source term of the energy equation considered in the 3D gas flow model (GFM) to model the reactor temperature
The simulated average gas temperature of the reactive zone is rotational temperature determined, and the surface temperature of the reactor is compared with that compared with the rotational temperature determined, and the surface temperature of the reactor is compared with that detected by the IR thermal imager

Summary

Introduction

Atmospheric pressure helium dielectric-barrier discharges (APHeDBDs) have been developed intensively in different fields including surface treatments [1,2,3] and plasma medicine [4,5,6] due to the efficient generation of reactive species and stable operating conditions. APHeDBDs are driven by kHz power sources since they are simple and can be scaled up for applications . APHeDBDs driven by kHz power sources can be considered as one of the important plasma sources for the aforementioned applications. It is common to consider gas temperature as one of critical discharge parameters since gas temperature influences rate constants of chemical reactions and densities of background gases, determining the discharge chemistry. Gas temperature is the key parameter affecting transport.

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