Influence of Defect on the Vacuum Surface Insulation Performance of Dielectric Materials under Impulse Voltage
The influence of defects on the insulation properties of dielectric materials along the vacuum surface under pulse voltage was studied by positron annihilation lifetime spectroscopy(PALS).The Chenguang accelerator tested the insulation properties of four kinds of materials along the vacuum surface.The results show that the longer the average lifetime of positron annihilation,the worse the voltage-withstanding performance along the vacuum surface of dielectric material.The defect information in the material can be quantified by the average lifetime of positron annihilation.Our analysis suggests that the presence of defects is a key factor in the reduced insulation performance along the vacuum surface of dielectric materials.Defects on the dielectric material's surface cause the material's dielectric constant to change,and defects can easily capture free carriers,arouse surface charge accumulation,and enhance the local electric field.
positron annihilation lifetimedefectcharge accumulationsurface flashoverpulse voltagedielectric material
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