High Voltage
Volume 1, Issue 2, July 2016
Volumes & issues:
Volume 1, Issue 2
July 2016
-
- Author(s): Professor Xinpei Lu
- Source: High Voltage, Volume 1, Issue 2, page: 61 –61
- DOI: 10.1049/hve.2016.0035
- Type: Article
- + Show details - Hide details
-
p.
61
(1)
- Author(s): He Cheng ; Xin Liu ; Xinpei Lu ; Dawei Liu
- Source: High Voltage, Volume 1, Issue 2, p. 62 –73
- DOI: 10.1049/hve.2016.0023
- Type: Article
- + Show details - Hide details
-
p.
62
–73
(12)
In this study, the propagation mechanism of plasma jet and some bio-medical applications are investigated by two-dimensional numerical model. The key equations of plasma physics and chemistry related with plasma jet are firstly introduced. The simulation results suggest that the sheath forms near the dielectric tube inner surface, which results in the plasma channel to shrink in the radial direction inside the dielectric tube. The photoionisation of air species plays a crucial role in the transition from the localised discharge to streamer. The Penning ionisation increases the electric conductivity of the plasma channel and facilitates the formation of ring-shaped plasma bullet. For the plasma jet in the open air, electron-impact dissociation of H2O, electron neutralisation of H2O+, as well as dissociation of H2O by O(1D) are found to be the main reactions to produce OH. For micro plasma jet, the higher ignition voltage as the tube diameter decreased is attributed to the deceasing pre-avalanche electron density inside the tube. The simulation of plasma treatment of bacteria biofilm indicates that the mean free path of charged species in µm scale permitted the plasma penetrate into the cavity of the biofilm, and the structure of the biofilm results in the non-uniform distribution of ROS and RNS. The simulation of plasma treatment of cells immersed in liquid suggests that the HO2 generated by plasma aqueous species is the only way for superoxide to penetrate cell membrane and damage cytosolic fumarase B.
- Author(s): Anbang Sun ; Chao Huo ; Jie Zhuang
- Source: High Voltage, Volume 1, Issue 2, p. 74 –80
- DOI: 10.1049/hve.2016.0016
- Type: Article
- + Show details - Hide details
-
p.
74
–80
(7)
Streamer discharges in liquids have received lots of attention with respect to their considerable applications in various disciplines. Much effort has been spent to understand the basis of streamer ignition and propagation in dielectric liquids, but a comprehensive mechanism is far from conclusive. In this review, based on an introduction to the streamer physics and experimentally observed characteristics in various liquids, the authors emphasise on the current status of streamer discharge ignition mechanisms and present their understanding for each theory.
- Author(s): Ding Xin Liu ; Jia Feng Li ; Ai Jun Yang ; Xiao Hua Wang ; Ming Zhe Rong ; Michael G. Kong
- Source: High Voltage, Volume 1, Issue 2, p. 81 –85
- DOI: 10.1049/hve.2016.0019
- Type: Article
- + Show details - Hide details
-
p.
81
–85
(5)
Cold atmospheric-pressure He + N2 and He + O2 plasmas are chosen as the representatives for electropositive and electronegative plasmas, of which the discharge characteristics are studied and then compared to each other by fluid models. As the increase of the impurity (N2 or O2) fraction from 0 to 10%, for He + N2 plasmas the electron density and ion density increase, the spatiotemporal distributions of electron density, ion density, electron temperature and electron generation rate change a little. On contrast, for He + O2 plasmas the electron density decreases, the ion density first increases and then decreases, the electron temperature increases in the bulk region, but decreases in the sheath region, and the plasmas transform from γ mode to α mode as the significant change of electron generation rate distributions. Larger electric field is needed in the bulk region to sustain the electronegative plasma, so the electrical characteristics of He + O2 plasmas transform form capacitive to resistive with increasing O2 fraction. Meanwhile, the ion-coupling power increases dramatically, which can be estimated by a formula based on the electronegativity. A new criterion for determining the sheath boundary, |∇E| = 5 kV/cm2, is put forward, which is found suitable for both the electropositive and electronegative plasmas.
- Author(s): Yangyang Fu ; Shuo Yang ; Xiaobing Zou ; Haiyun Luo ; Xinxin Wang
- Source: High Voltage, Volume 1, Issue 2, p. 86 –89
- DOI: 10.1049/hve.2016.0017
- Type: Article
- + Show details - Hide details
-
p.
86
–89
(4)
The similarity of gas discharge in low-pressure argon gaps between two plane-parallel electrodes was investigated by experiments, numerical simulations and theoretical analysis. It was found by the experiments that the breakdown voltages depend not only on the product of gas pressure and gap length, but also on the aspect ratio of the gap, i.e. U b = f (pd, d/r). It was theoretically proved that U b = f (pd, d/r) is also a special case, the non-uniform electric field between plane-parallel electrodes, of similarity theorem of gas discharge. It was found by the experiments that there exist similar glow discharges only in two gaps with a limited scaled-down factor k. By theoretical analysis, it was explained that the forbidden processes such as the stepwise ionisation and the inelastic collision of the second kind violate the similarity of discharge as k increases, which was verified by the numerical simulations of the discharges with or without these two forbidden processes taken into account.
- Author(s): Yang Xia ; Dongping Liu ; Hamidreza Ghomi ; Wenchun Wang ; Zhenhua Bi ; Longfei Ji ; Xueyang Wang ; Zhihua Qi ; Bin Li
- Source: High Voltage, Volume 1, Issue 2, p. 90 –94
- DOI: 10.1049/hve.2016.0020
- Type: Article
- + Show details - Hide details
-
p.
90
–94
(5)
This study presents spatio-temporal development of the ionisation waves (IWs) along one dielectric tube with an extra alternating electric field. A pulsed direct current power supply is used for generating the IWs, and another alternating current power supply is used for altering the distribution of electric fields along the dielectric tube. The measurements show that the propagation velocity and density of IWs are strongly affected by the external electric field. The direct relation between external electric field and the velocity of the IWs is demonstrated. Further analysis indicates that the external electric field can be utilised to control the propagation of the IWs, resulting in a change of their density and velocity.
Guest Editorial
Numerical study on propagation mechanism and bio-medicine applications of plasma jet
Formation mechanism of streamer discharges in liquids: a review
Comparison between electropositive and electronegative cold atmospheric-pressure plasmas: a modelling study
Similarity of gas discharge in low-pressure argon gaps between two plane-parallel electrodes
Dynamics of ionisation wave propagation in an applied external electric field
-
- Author(s): Ning Liu ; Churui Zhou ; George Chen ; Yang Xu ; Junzheng Cao ; Haitian Wang
- Source: High Voltage, Volume 1, Issue 2, p. 95 –105
- DOI: 10.1049/hve.2016.0012
- Type: Article
- + Show details - Hide details
-
p.
95
–105
(11)
In this study, an improved trapping/detrapping model was used to simulate the charge dynamics in cross-linked polyethylene peelings from different-year aged cables. Injection barrier of trapping parameters was estimated by the model fitted to experimental data for each type of sample. Moreover, dc breakdown tests were operated on those samples. It has been found that the dc breakdown strength of inner-layer samples is the lowest in cable sections with thicker insulation layer taken from high-voltage ac (HVAC) 220 kV service condition, whereas for the cable with thinner insulation from HVAC 110 kV, middle-layer samples have worst breakdown performance. This might be explained by the space charge issues under long-term HVAC condition. More importantly, a clear relationship between estimated model parameters, including injection barrier, trap depth and trap density, with the dc breakdown strength in each layer has been reported in this study.
Model to estimate the trapping parameters of cross-linked polyethylene cable peelings of different service years and their relationships with dc breakdown strengths
Most viewed content
Most cited content for this Journal
-
Progress in and prospects for electrical insulating materials
- Author(s): Shengtao Li ; Shihu Yu ; Yang Feng
- Type: Article
-
Atmospheric-pressure pulsed discharges and plasmas: mechanism, characteristics and applications
- Author(s): Tao Shao ; Ruixue Wang ; Cheng Zhang ; Ping Yan
- Type: Article
-
Research and application on multi-terminal and DC grids based on VSC-HVDC technology in China
- Author(s): Ting An ; Guangfu Tang ; Weinan Wang
- Type: Article
-
Research and application of UHV power transmission in China
- Author(s): Yinbiao Shu and Weijiang Chen
- Type: Article
-
Formation mechanism of streamer discharges in liquids: a review
- Author(s): Anbang Sun ; Chao Huo ; Jie Zhuang
- Type: Article