Formation mechanism of bright and dark concentric-ring pattern in dielectric barrier discharge

In this work,a bright and dark concentric-ring pattern is reported in a dielectric barrier discharge for the first time.The spatiotemporal dynamics of the bright and dark concentric-ring pattern are investigated with an intensified charge-coupled device and photomultiplier tubes.The results indicate that the bright and dark concentric-ring pattern is composed of three concentric-ring sublattices.These are bright concentric-ring structures,dark concentric-ring structures and wider concentric-ring structures,respectively.The bright concentric-ring structures and dark concentricring structures are alternately distributed.The bright concentric-ring structures are located at the centre of the wider concentric-ring structures.The wider concentric-ring structures first form from the outer edge and gradually develop to the centre.The essence of all three concentric-ring structures is the individual discharge filaments.The optical emission spectra of different sublattices are acquired and analysed.It is found that the plasma parameters of the three concentricring sublattices are different.Finally,the formation mechanism of the bright and dark concentricring pattern is discussed.

Square grid pattern with direction-selective surface discharges in dielectric barrier discharge

A new phenomenon that a filament discharged only once instead of twice in a cycle of the applied voltage is observed in a square grid pattern in a dielectric barrier discharge(DBD)with a larger gas gap,which is named intermittent discharge.Its spatiotemporal dynamics and the formation mechanism are studied by the multiple photomultiplier tubes and an intensified charge-coupled device.Corresponding to the positions of spots in the picture with an exposure time of 40 ms,there are some bright spots(discharge spots)and black spots(non-discharged spots)in the instantaneous image with an exposure time of 10μs(a half cycle of the applied voltage).There are at least two bright spots around one black spot and vice versa.The surface discharges(SDS)can be observed between any two adjacent spots.The intensity of the SDSbetween the bright spot and the black spot is 2.5 times greater than that between two adjacent bright spots,which indicates that the SDSare directional-selective.The intermittent discharge with positive(negative)current polarity changes to that with negative(positive)current polarity,after it sustains up to 14 voltage cycles at the longest.The spatial distribution of the electric field component is calculated through COMSOL software to solve the Poisson equation numerically.It is found that the inhomogeneous distribution of surface electric field is caused by the inhomogeneous distribution of wall charges,which leads to direction-selective SDS.The intermittent discharge is formed by the competition between the direction-selective SDSand volume discharges(VDS)in DBD.This is the reason why the intermittent discharge is generated.

Formation of honeycomb-Kagome hexagonal superlattice pattern with dark discharges in dielectric barrier discharge

A honeycomb-Kagome hexagonal superlattice pattern with dark discharges is observed in a dielectric barrier discharge system for the first time.The spatiotemporal structure of the honeycomb-Kagome hexagonal superlattice pattern with dark discharges is investigated by an intensified charge-coupled device and the photomultipliers show that it is an interleaving of three different sub-lattices,which are bright-spot,invisible honeycomb lattice,and Kagome lattice with invisible frameworks and dim-spots,respectively.The invisible honeycomb lattices and Kagome lattices are actually composed of dark discharges.By using the optical emission spectra method,it is found that the plasma parameters of the three different sub-lattices are different.The influence of the dark discharges on pattern formation is discussed.The results may have significance for the investigation of the dark discharges and will accelerate the development of self-organized pattern dynamics.

不同类型患者接受腰椎间盘O_(3)注射术后疼痛缓解疗效分析

目的分析不同年龄组及不同椎间盘突出类型的患者接受腰椎间盘三氧(Ozone,O_(3))注射术后疗效的差别,为临床治疗的选择提供依据。方法随访2009年1月到2019年6月在南方医院就诊的腰椎间盘突出症患者共476人(年龄在14~85岁之间,单一责任椎间盘)。根据MRI影像和DSA下O_(3)注射时的影像表现,我们将腰椎间盘突出症分为四型:Ⅰ型:纤维环破裂髓核突出型;Ⅱ型:纤维环破裂髓核非突出型;Ⅲ型:纤维环非破裂髓核突出型;Ⅳ型:纤维环非破裂髓核非突出型。VAS评分作为评价疗效的标准,我们记录了患者术前、术后1周、1、6和12个月的VAS评分并进行比较。结果腰椎间盘O_(3)注射术对患者疼痛缓解有较好的疗效,有椎间盘突出的患者在治疗后可观察到突出减小。在年龄、性别、病程、突出类型等临床特征中,年龄是唯一与术后VAS相关因素,且呈负相关。不同年龄组患者疗效与分型相关,中青年组患者Ⅰ型疗效最好,Ⅳ型疗效最差;老年组患者Ⅱ型疗效最好,Ⅲ型最差。结论腰椎间盘O_(3)注射术是一种有效的治疗腰椎间盘突出症的方法,但是不同年龄组间不同类型的患者疗效不同,在临床治疗中应根据患者特点选用不同治疗方案。