Research On The Inhibition Of Micro-discharge By Plasma Jet Thin Film Deposition

The metal particles generated during the production,installation and operation of high-voltage DC GIL/GIS equipment are prone to launching motion under the action of a high electric field.The local micro-discharge caused by the movement of metal particles between the electrodes even causes the breakdown of the dielectric between the electrodes,which seriously jeopardizes the safe and stable operation of the GIL/GIS equipment.In order to easily and effectively inhibit the initiation of metal particles and the micro-discharge induced by it,plasma-enhanced chemical vapor deposition was used to deposit functional films on the surface of Cu electrodes and to investigate their inhibition on metal particle lift and micro-discharge.In this paper,the SiO₂ film was deposited on the surface of Cu and PMMA substrates by plasma jet,and the related factors affecting the film properties were explored.The experiment adjusted the discharge intensity and film properties by changing the flow rates of O₂ and N₂,and analyzed the main factors affecting film deposition according to the measurement results under different parameters,which provided experimental guidance for the preparation of functional films.Subsequently,a high-frequency AC power source was used as an excitation source to rapidly deposit a TiO₂-SiO₂ composite film densely bonded to the substrate on the Cu surface.And the inhibitory effect of deposited film on the initiation of metal particles and the microdischarge induced by it was analyzed by the metal particle initiation test system and COMSOL software.Finally,the stability of the deposited TiO₂-SiO₂ composite film on the initiation inhibition of metal particles was studied by thermal aging experiment.The results of this study show that the properties of the substrate and the composition of the discharge gas have a great influence on the plasma discharge characteristics and the properties of the deposited film.The surface of the insulating substrate has a higher degree of oxidation of the SiO₂ film on the surface than the metal substrate due to charge accumulation.Incorporating O₂ into the excitation gas can effectively uniform the plasma jet,and the plasma discharge intensity is sensitive to O₂ flow.The mixing of O₂ in the excitation gas can effectively homogenize the generated plasma jet,and after mixing of 40 sccm of N₂ the particle diameter of the surface is reduced to about 100 nm.After the composite film is deposited on the surface of Cu electrode,the initiating voltage of the metal particles is increased by about 18%,and the degree of electric field distortion between the electrodes is also reduced to some extent.The experiments in this paper prove the feasibility of using plasma deposition method to prepare functional thin films on the surface of the electrode to inhibit the initiation of metal particles,which provides a new idea for solving practical problems.