Research On Plasma Parameters Of Pantograph-Catenary Arc Based On Moire Deflectometry

The phenomenon of pantograph-catenary(PC)arc produced by air breakdown is increasingly frequent due to the continuous increase of train speed and offline rate.There are essential differences between PC arc,that has the characteristics of high temperature and energy in the open environment,and other arc.It brings electromagnetic waves to interfere the railway communication and high temperatures to accelerate pantograph slide wear and make wire deformation,which greatly shorten the service life of pantograph slide and catenary wire and threaten the safe operation of the train.There is no doubt that in-depth studies have important significance about PC arc.However the research methods of PC arc are not rich and internal parameters of arc plasma have yet been revealed.The optical diagnostic techniques have advantages of simple apparatus and no interference to the object being measured.Therefore,the internal parameters of PC arc are researched by the optical diagnostic techniques,which is helpful to perfect the research means and the analysis theory system of PC arc and provide scientific bases for reducing the harm of PC arc,improving service performance of PC and developing high-speed railway.In this paper,firstly the basic principles were expounded and related formulas were derived based on moire deflectometry.The different algorithms were compared and the errors were calculated by reconstructing simulated field.The corresponding relationships between the refractive index and internal parameters of plasma were established by solving the physical equations of plasma.The experiment platform of moire deflectometry was set up and the spatial resolution was calculated.The fringe skeleton extraction method and Fourier transform method were both elaborated for the moire image processing.The method and data processing were verified by reconstructing temperature field of candle.Besides the distribution laws of temperature of AC arc plasma of low current were researched and the reasons were analyzed.In addition the distributions of the temperature and electron density of PC arc plasma were revealed by diagnosing.Furthermore,laws were explored under the condition of different input currents.Finally,the temperatures of the arc plasma were got by simulated based on radiation spectrum collected,so as to verify the validity of the moire deflectometiy.