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24 pages, 6471 KiB

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Key Modes of Ignition and Maintenance of Corona Discharge in Air

by Vasily Yu. Kozhevnikov, Andrey V. Kozyrev, Victor F. Tarasenko, Aleksandr O. Kokovin, Evgeni Kh. Baksht and Nikita P. Vinogradov

Energies 2023, 16(13), 4861; https://doi.org/10.3390/en16134861 - 21 Jun 2023

Cited by 9 | Viewed by 3189

Abstract

Theoretical and experimental studies of various modes of corona discharge operation in atmospheric pressure air are presented in this short review. The original results of modeling negative corona discharges are presented, taking into account the non-stationary plasma-chemical kinetics of charged particles in air plasma. The space–time evolution of the discharge in needle-to-plane geometry is investigated and analyzed. Several stages of discharge development are revealed from the moment of initiation of a low-negative current corona to the quasi-stationary mode of a glow discharge. Experimental data of the authors are presented. Modern technology and diagnostic equipment with a wide variation of the main parameters (the shape and polarity of the applied voltage, the type of gap, etc.) was used. The measurement of the optical characteristics of the plasma glow was carried out with high spatial resolution. Corona discharge current pulse profiles in the air at atmospheric pressure have been recorded with subnanosecond time resolution. With a positive polarity of the pin electrode and high voltage, a transition from a spherical streamer initiating a corona discharge to a cylindrical streamer is shown. The author’s results are rigorously evaluated through a critical comparison with findings from other research groups. Full article

(This article belongs to the Section E: Electric Vehicles)

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16 pages, 4267 KiB

Open AccessArticle

A Novel Dielectric Barrier Discharge (DBD) Reactor with Streamer and Glow Corona Discharge for Improved Ozone Generation at Atmospheric Pressure

by Pu Liu, Yongxin Song and Zhitao Zhang

Micromachines 2021, 12(11), 1287; https://doi.org/10.3390/mi12111287 - 21 Oct 2021

Cited by 13 | Viewed by 4939

Abstract

Discharge mode is an important parameter for ozone synthesis by dielectric barrier discharge (DBD). Currently, it is still challenging to stably generate glow discharge with oxygen at atmospheric pressure. In this paper, a DBD reactor with a layer of silver placed between the electrode and the dielectric layer (SL-DBD) was developed. Experimental results show that both streamer and glow corona discharge were stably generated under sinusoidal excitation with a 0.5 mm discharge gap in a parallel-plate DBD, due to the increased electric field strength in the discharge gap by the silver layer. It was also found that, in the SL-DBD reactor, glow corona discharge enhances the discharge strength by 50 times. The spectral peak of O at 777 nm in SL-DBD is increased to 28,800, compared with 18,389 in a reactor with a streamer only. The SL-DBD reactor produces ozone with a concentration of as high as 150 g/m³ and shows good stability in an 8 h durability test. Full article

(This article belongs to the Special Issue Heat Transfer and Fluid Flow in Micromachines, Volume II)

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22 pages, 12955 KiB

Open AccessArticle

AC Volume Breakdown and Surface Flashover of a 4% Novec^TM 4710/96% CO₂ Gas Mixture Compared to CO₂ in Highly Nonhomogeneous Fields

by Houssem Eddine Nechmi, Mohammed El Amine Slama, Abderrahmane (Manu) Haddad and Gordon Wilson

Energies 2020, 13(7), 1710; https://doi.org/10.3390/en13071710 - 3 Apr 2020

Cited by 10 | Viewed by 4771

Abstract

AC pre-discharge currents, breakdown, and flashover voltage measurements are reported in a 10 mm needle-plane arrangement in a 4% Novec^TM 4710/96% CO₂ gas mixture and compared with CO₂ for pressures up to 8.8 bar abs. Flashover measurements were performed on different solid dielectrics (Al₂O₃_filled epoxy resins, PTFE (Polytetrafluoroethylene) and PE (polyethylene)) for different roughness surface finishes. The effect of fixed conducting needles at various positions on electrical strength is reported. A strong nonlinear behaviour as function of gas pressure was observed for all the studied parameters (gas, needle position, solid insulator, insulator roughness). The non-linear behaviour is attributed to the inception and quenching of glow corona, in the interval between inception and breakdown or flashover voltages. It is found that a 4% concentration of Novec^TM 4710 in CO₂ has a breakdown/flashover voltage ≈ 1.14 higher than CO₂. The glow corona-induced stabilization effect is seen for pressures between 2 and 5 bar abs for all the studied parameters. The peak flashover voltage and its associated pressure of the different insulators are strongly dependent on surface roughness. At 8.8 bar abs, the flashover voltage level obtained with various materials was ordered as follows: PTFE > PE-UHMW > Epoxy > HDPE(High-density polyethylene). Full article

(This article belongs to the Section F: Electrical Engineering)

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12 pages, 3788 KiB

Open AccessArticle

Design, Fabrication and Mass-spectrometric Studies of a Micro Ion Source for High-Field Asymmetric Waveform Ion Mobility Spectrometry

by Hua Li, Hongmei Yun, Xiaoxia Du, Chaoqun Guo, Ruosheng Zeng, Yongrong Jiang and Zhencheng Chen

Micromachines 2019, 10(5), 286; https://doi.org/10.3390/mi10050286 - 27 Apr 2019

Cited by 9 | Viewed by 4006

Abstract

A needle-to-cylinder electrode, adopted as an ion source for high-field asymmetric ion mobility spectrometry (FAIMS), is designed and fabricated by lithographie, galvanoformung and abformung (LIGA) technology. The needle, with a tip diameter of 20 μm and thickness of 20 μm, and a cylinder, with a diameter of 400 μm, were connected to the negative high voltage and ground, respectively. A negative corona and glow discharge were realized. For acetone with a density of 99.7 ppm, ethanol with a density of 300 ppm, and acetic ether with a density of 99.3 ppm, the sample gas was ionized by the needle-to-cylinder chip and the ions were detected by an LTQ XL™ (Thermo Scientific Corp.) mass spectrometer. The mass spectra show that the ions are mainly the protonated monomer, the proton bound dimer, and an ion-H₂O molecule cluster. In tandem with a FAIMS system, the FAIMS spectra show that the resolving power increases with an increase in the RF voltage. The obtained experimental results showed that the micro needle-to-cylinder chip may serve as a miniature, low cost and non-radioactive ion source for FAIMS. Full article

(This article belongs to the Special Issue 10th Anniversary of Micromachines)

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13 pages, 6128 KiB

Open AccessArticle

An Integrated Microfabricated Chip with Double Functions as an Ion Source and Air Pump Based on LIGA Technology

by Hua Li, Linxiu Jiang, Chaoqun Guo, Jianmin Zhu, Yongrong Jiang and Zhencheng Chen

Sensors 2017, 17(1), 87; https://doi.org/10.3390/s17010087 - 4 Jan 2017

Cited by 3 | Viewed by 5059

Abstract

The injection and ionization of volatile organic compounds (VOA) by an integrated chip is experimentally analyzed in this paper. The integrated chip consists of a needle-to-cylinder electrode mounting on the Polymethyl Methacrylate (PMMA) substrate. The needle-to-cylinder electrode is designed and fabricated by Lithographie, Galvanoformung and Abformung (LIGA) technology. In this paper, the needle is connected to a negative power supply of −5 kV and used as the cathode; the cylinder electrodes are composed of two arrays of cylinders and serve as the anode. The ionic wind is produced based on corona and glow discharges of needle-to-cylinder electrodes. The experimental setup is designed to observe the properties of the needle-to-cylinder discharge and prove its functions as an ion source and air pump. In summary, the main results are as follows: (1) the ionic wind velocity produced by the chip is about 0.79 m/s at an applied voltage of −3300 V; (2) acetic acid and ammonia water can be injected through the chip, which is proved by pH test paper; and (3) the current measured by a Faraday cup is about 10 pA for acetic acid and ammonia with an applied voltage of −3185 V. The integrated chip is promising for portable analytical instruments, such as ion mobility spectrometry (IMS), field asymmetric ion mobility spectrometry (FAIMS), and mass spectrometry (MS). Full article

(This article belongs to the Special Issue Microfluidic Sensors and Control Devices)

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