高压水下湿法焊接电弧等离子体介质击穿机制

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Mechanism on dielectric breakdown of arc plasma in high pressure underwater wet welding

LI Zhigang，WEI Chengfa，LIU Dejun，YANG Xiang （Laboratory of Transportation Tools and Equipment，Ministry of Education，East China JiaotongUniversity，Nanchang 330O13，China）

Abstract： In order to study the mechanism of arc plasma breakdown in deep water wet welding，a high-pressure underwater wet welding experimental platform was established. Spectral maps of the arc initiation stage at a depth of 40m were obtained，and a three-dimensional numerical model of arc breakdown discharge at a depth of （204 40m was established based on the PIC-MCC method and analyzed. The results of spectral diagnosis arc plasma temperature，electron number densityand numerical model analysis were compared，and the rationality and corrctnessof the model were verified.Based on the main components of the arc plasma obtained from the arc spectroscopy，a study was conducted on the dynamic evolution process ofthe arc plasma in high-pressre underwater wet welding from the perspective of microscopic particles，and the dynamic distribution，number of particles，temperature and electron number density of the arc plasma were obtained. The results showed that H+ ， （2 OH+ and 0+ were mainly generated by the ionization colision between the electron and the background component water molecule，and the number of OH+ increased fastest，followed by H+ ，and 0+ last，the number of OH+ particles was far greater than the number of H+ and 0+ particles；During the collision between electrons and background gas，the energy shifted，and the kinetic energy of electrons moving to the dielectric layer of the electrodedecreased，the ionizationcollsion reaction betweenelectronsandthedielectric layerof theelectrode

weakened until saturationwas reached.

Key words：underwater wet welding arc；micro particles；dynamic evolution；dielectric breakdown mechanism

0 前言

海洋工程的建设与维修离不开水下焊接技术，然而其技术的研究远远不能适应形势发展的需要，加强水下湿法焊接的研究对提升焊接质量具有重大意义[1]。（剩余9358字）