Dielectric barrier discharge (DBD) for SO 2 removal from indoor air is investigated. In order to improve the removal efficiency, two novel methods are combined in this paper, namely by applying a pulsed driving voltage with nanosecond rising time and applying a magnetic field. For SO 2 removal efficiency, different matches of electric field and magnetic field are discussed. And nanosecond rising edge pulsed power supply and microsecond rising edge pulsed power supply are compared. It can be concluded that a pulsed DBD with nanosecond rising edge should be adopted, and electrical field and magnetic field should be applied in an appropriate match.

Rong Mingzhe;Liu Dingxin;Wang Xiaohua;Wang Junhua

Plasma Science and Technology

2007

In this paper, an experimental study on SO2 removal by nanosecond rising edge pulse dielectric barrier discharge (DBD) plasma, generated by multi-needle-to-plane electrodes, is carried out. The mechanism of the effect of various factors, such as gap size between dielectric barrier and discharge needles, environmental humidity, and inlet speed of gas flow upon the removal efficiency of air purification is analyzed. The studies show that SO2 removal efficiency improves with the increase in the gap size between dielectric barrier and discharge needles in the case of a fixed space between two electrodes, and also improves with the increase in the environmental humidity. For a mixed gas with a fixed concentration, there is an optimal inlet speed of gas flow, which leads to the best removal efficiency.

Wang Xiaohua;Su Biao;Liu Dingxin;Wang Junhua;Rong Mingzhe

Plasma Science and Technology

2007

A detailed global model of atmospheric-pressure He + H2O plasmas is presented in this paper. The model incorporates 46 species and 577 reactions. Based on simulation results obtained with this comprehensive model, the main species and reactions are identified, and simplified models capable of capturing the main physicochemical processes in He + H2O discharges are suggested. The accuracy of the simplified models is quantified and assessed for changes in water concentration, input power and electrode configuration. Simplified models can reduce the number of reactions by a factor of ∼10 while providing results that are within a factor of two of the detailed model. The simulation results indicate that Penning processes are the main ionization mechanism in this kind of discharge (1-3000 ppm of water), and water clusters of growing size are found to be the dominant charged species when the water concentration is above ∼100 ppm. Simulation results also predict a growing electronegative character of the discharge with increasing water concentration. The use of He + H2O discharges for the generation of reactive oxygen species of interest in biomedical applications and the green production of hydrogen peroxide are also discussed. Although it would be unrealistic to draw conclusions regarding the efficacy of these processes from a zero-dimensional global model, the results indicate the potential suitability of He + H 2O plasmas for these two applications. © 2010 IOP Publishing Ltd.

Liu D. X.;Rong M. Z.;Kong M. G.;Bruggeman P.;Iza F.

Plasma Sources Science and Technology

2010

A new type of algorithm for predicting the mechanical faults of a vacuum circuit breaker (VCB) based on an artificial neural network (ANN) is proposed in this paper. There are two types of mechanical faults in a VCB: operation mechanism faults and tripping circuit faults. An angle displacement sensor is used to measure the main axle angle displacement which reflects the displacement of the moving contact, to obtain the state of the operation mechanism in the VCB, while a Hall current sensor is used to measure the trip coil cmrent, which reflects the operation state of the tripping circuit. Then an ANN prediction algorithm based on a sliding time window is proposed in this paper and successfully used to predict mechanical faults in a VCB. The research results in this paper provide a theoretical basis for the realization of online monitoring and fault diagnosis of a VCB. Copyright © 2008 The Institute of Electronics, Information and Communication Engineers.

Wang Xiaohua;Rong Mingzhe;Qtu Juan;Liu Dingxin;Su Biao;Wu Yi

IEICE Transactions on Electronics

2008

The main species and chemical processes in low-temperature atmospheric-pressure He + O2 plasmas are identified using a comprehensive global model. The simulation results highlight the significance of Penning processes at low oxygen concentration, and the increasingly important role of electron attachment as the oxygen concentration increases. With increasing the oxygen concentration, the electron energy dissipation shifts from elastic collisions with He to dissociative excitation and attachment of O 2 molecules, and large ions (O⁺3, O ⁺4) become the dominant charged species. Generation and loss of ROS (O, O(¹D), O(¹S), O2(a ¹δg), O2(b¹σg+), O 3) relevant for biomedical applications are discussed. Cold atmospheric-pressure He+O2 plasmas are an excellent source of reactive oxygen species (e.g. O, O(¹D), O(¹S), O 2(a¹δg), O2(b ¹σg⁺), O3) relevant in many applications, such as plasma medicine. Here we report on a detailed analysis of the interaction among 21 species and 267 reactions involved in these plasmas and unravel the main physicochemical processes at play. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu Ding-Xin;Rong Ming-Zhe;Wang Xiao-Hua;Iza Felipe;Kong Michael G.;Bruggeman Peter

Plasma Processes and Polymers

2010

In order to understand the influence of the average opening velocity on the high-current vacuum arc anode phenomena, a high-speed photography was used to observe anode phenomena of vacuum arc discharge in vacuum interrupters. The contact diameters used in the vacuum interrupters were 12 mm and 25 mm, respectively. The contact materials included Cu, CuCr25, and CuCr50. The arc current frequency was 50 Hz and the arcing time was controlled at about 9 ms. A permanent magnet mechanism with a contact spring was used to adjust the average opening velocity from 1.3 m/s to 1.8 m/s. The experimental results showed that with the arc current increasing, there was a threshold current I1st (peak value) with which a high-current anode mode first appeared. And the first high-current anode mode was a footpoint at the velocity of 1.8 m/s. While at the velocity of 1.3 m/s, it was most probably an anode spot and sometimes it was a footpoint. The result showed that at the velocity of 1.8 m/s, the threshold current I1st was lower than that of the 1.3 m/s. And the threshold current I1st followed the order of Cu > CuCr25 > CuCr50 at both the velocities of 1.3 m/s and 1.8 m/s. Meanwhile, at the higher average opening velocity of 1.8 m/s, the arc energy and arc voltage were higher than or close to that with 1.3 m/s. ©2010 IEEE.

Kong Guowei;Liu Zhiyuan;Wang Dong;Rong Mingzhe

Proceedings International Symposium on Discharges and Electrical Insulation in Vacuum ISDEIV

2010

In order to understand the influence of the average opening velocity on the high-current vacuum arc anode phenomena, high-speed photography was used to observe the anode phenomena of the vacuum arc discharge in vacuum interrupters. The contact diameters used in the vacuum interrupters were 12 and 25 mm, respectively. The contact materials included Cu, CuCr25, and CuCr50. The arc current frequency was 50 Hz, and the arcing time was controlled at about 9 ms. A permanent magnet mechanism with a contact spring was used to adjust the average opening velocity from 1.3 to 1.8 m/s. The experimental results showed that, with the arc current increasing, there was a threshold current I1st (peak value) at which a high-current anode mode first appeared. Moreover, the first high-current anode mode was a footpoint at the velocity of 1.8 m/s, while, at the velocity of 1.3 m/s, it was most probably an anode spot and sometimes it was a footpoint. The result showed that, at the velocity of 1.8 m/s, the threshold current I1st was lower than that at 1.3 m/s. Moreover, the threshold current I1st followed the order of Cu CuCr25 CuCr50 at both the velocities of 1.3 m/s and 1.8 m/s. Meanwhile, at the higher average opening velocity of 1.8 m/s, the arc energy and arc voltage were higher than or close to those at 1.3 m/s. © 2011 IEEE.

Kong Guowei;Liu Zhiyuan;Wang Dong;Rong Mingzhe

IEEE Transactions on Plasma Science

2011

The effect of water in the chemistry of atmospheric-pressure He+ O 2 plasmas is studied by means of a comprehensive global model. Water enables the generation of reactive oxygen species (ROS) cocktails that are rich not only in O, O 2 , and O 3 but also in OH and H 2 O 2 . Due to its polar nature, water also leads to cluster formation, possibly affecting the plasma dynamics. Since the lifetime of many of the ROS is short, the plasma chemistry plays two roles: (i) direct interaction with superficial cells and (ii) triggering of a secondary chemistry that propagates the plasma treatment to regions away from the plasma-surface interface. © 2011 American Institute of Physics.

Liu D. X.;Wang X. H.;Kong M. G.;Rong M. Z.;Iza F.

Applied Physics Letters

2011

Stratification of negatively charged species in electronegative discharges is a well-known phenomenon that can lead to various double-layer structures. Here, we report on the separation of electrons and anions in atmospheric-pressure electronegative microdischarges. In these discharges, electrons oscillate between the electrodes, moving across and beyond an electronegative core. As a result of this motion, positively charged regions form between the oscillating electron ensemble and the central electronegative discharge. © 2006 IEEE.

McKay Kirsty;Iza Felipe;Kong Michael G.;Liu Ding-Xin;Rong Ming-Zhe

IEEE Transactions on Plasma Science

2011

In this paper atmospheric-pressure rf He+O 2 cold plasmas are studied by means of a 1-D fluid model. 17 species and 60 key reactions selected from a study of 250 reactions are incorporated in the model. O 2⁺ , O 3^- , and O are the dominant positive ion, negative ion, and reactive oxygen species, respectively. Ground state O is mainly generated by electron induced reactions and quenching of atomic and molecular oxygen metastables, while three-body reactions leading to the formation of O 2 and O 3 are the main mechanisms responsible for O destruction. The fraction of input power dissipated by ions is ∼20. For the conditions considered in the study ∼6 of the input power is coupled to ions in the bulk and this amount will increase with increasing electronegativity. Radial and electrode losses of neutral species are in most cases negligible when compared to gas phase processes as these losses are diffusion limited due to the large collisionality of the plasma. The electrode loss rate of neutral species is found to be nearly independent of the surface adsorption probability p for p > 0.001 and therefore plasma dosage can be quantified even if p is not known precisely. © 2011 American Institute of Physics.

Yang Aijun;Wang Xiaohua;Rong Mingzhe;Liu Dingxin;Kong Michael G.;Iza Felipe

Physics of Plasmas

2011