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LI Shengtao, ZHANG Tuo, HUANG Qifeng, LI Weiwei, NI Fengyan, LI Jianying. Improvement of Surface Flashover Performance of Al2O3 Ceramics in Vacuum by Adopting A-B-A Insulation System[J]. Plasma Science and Technology, 2011, 13(2): 235-241.
Citation: LI Shengtao, ZHANG Tuo, HUANG Qifeng, LI Weiwei, NI Fengyan, LI Jianying. Improvement of Surface Flashover Performance of Al2O3 Ceramics in Vacuum by Adopting A-B-A Insulation System[J]. Plasma Science and Technology, 2011, 13(2): 235-241.

Improvement of Surface Flashover Performance of Al2O3 Ceramics in Vacuum by Adopting A-B-A Insulation System

  • A new insulation system with inorganic A-B-A insulators was proposed to improve the surface flashover performance in vacuum. Inorganic A-B-A insulator samples of Mo/Al2O3 cermet - Al2O3 ceramic - Mo/Al2O3 cermet were prepared, in wich the conductivity and permittivity of the Mo/Al2O3 cermets were controlled through different amount of metallic molybdenum powder added. The effects of both conductivity and permittivity of Mo/Al2O3 cermets on the DC and impulse surface flashover voltage in vacuum were experimentally investigated. The result showed that the DC and impulse surface flashover voltage were improved by 52% and 95%, respectively. For the distribution of electric field, two triple junctions, i.e., vacuum - layer A - cathode (TJ1) and vacuum - layer A - layer B (TJ2) were prepared with the introduction of layer A into the A-B-A insulation system. Based on the electric field distribution obtained via electrostatic field simulation and Maxwell-Wagner three-layer model, the electric field of TJ1 decreases while that of TJ2 increases with the increase in conductivity and permittivity of layer A under applied DC and impulse voltage, respectively. Therefore, the improvement of surface flashover performance of A-B-A insulators has been reasonably explained.
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