Research on Electrical Breakdown Characteristics of Ozonized Water Treated Oxygen-free Copper in Vacuum

据报道，为了获得真空间隙的更高调节效果，需要对电极表面进行原位预清洁。然而，从实用的角度来看，最好在没有任何现场预清洁程序的情况下实现更高的调理效果。最近开发的臭氧化水处理具有保持清洁表面的优点，并且清洁的表面甚至可以保持在空气中。本课题研究了臭氧水处理无氧铜电极在真空中的电击穿特性，通过对处理3天后的电极的测量发现，不进行任何现场预清洗，就能获得较高的调理效果。在调节程序之后的击穿场（击穿电压/间隙长度）达到约250 MV/m。该值几乎与用原位预清洁的电极获得的值一致。在臭氧化水处理之后的这种较高的调节效果可以归因于以下优点：清洁的表面甚至可以保持在空气中，因为在调节过程之后，由臭氧化水处理产生的氧化层被完全去除。表面分析表明，氧化后的表面由三层组成，即最上层的污染薄层、CuO层和Cu 2 O层。对臭氧水处理后的电极表面状态进行表征，对电极表面处理技术的发展具有重要意义。此外，臭氧水处理后暴露于空气中3个月的电极与处理后3天的电极具有竞争性的调理效果，从这些结果可以证实臭氧水处理具有实用优势，即加工后的电极和处理后的电极可以在空气中长时间保存，甚至3个月。

It has been reported that to obtain higher conditioning effect of a vacuum gap requires in situ pre-cleaning of electrode surfaces. On a practical point of view, however, it is preferable to achieve higher conditioning effect without any in situ pre-cleaning procedure. Recently developed ozonized water treatment has advantages that clean surfaces are ontained and the cleaned surface can be kept even in air. In this project electrical breakdown characteristics of ozonized water treated oxygen-free copper electrodes in vacuum were investigated.From the measurements of the electrodes tereated after 3 days it was found that higher conditioning effect was obtained without any in situ pre-cleaning. The breakdown field (Breakdown voltage/gap length) after conditioning procedure achived about 250 MV/m. This value almost conincide with the value obtained for the electrodes with in situ pre-cleaning. Such higher conditioning effect after ozonized water treatment can be attributed to the advantage that the cleaned surface can be kept even in air, since after the conditioning procedure the oxydized layer created by the ozonized water treatment was completely removed. Surface analysis revealed that oxydized surface was conposed of three layers, that is, thin contaminat layer at the top most of the surface, CuO layer and Cu2O layer. It is useful for tdeveloping electrode surface processing technique that after the ozonized water treatment the surface condition can be characterized. In addition, electrodes exposed to air for 3 months after the ozonized water treatment has an competitive conditioning effect to that of electrodes treated after 3 days.From these results it has been confirmed that ozonized water treatment has a practical advantage that electrodes after machining and the treatment can be stored in air for long time even for 3 months.