| Popis: |
Pairs of electrodes in vacuo at 10−9 Torr were tested at various gap spacings to find the amount of applied voltage needed to cause electrical breakdown, with a view to determining whether dispersion-strengthened (DS) copper has a higher breakdown voltage than standard, oxygen-free, high-conductivity (OFHC) copper. All anodes were made of OFHC copper. Half of these were paired with cathodes of OFHC copper, half with cathodes of DS copper. Voltage breakdown was determined for all pairs at gap spacings between 0.003 in. and 0.007 in. The group-average voltage breakdown of all DS/OFHC pairs was found to be 21% higher than that of OFHC/OFHC pairs. It is speculated that the relatively hard surface of DS copper may inhibit the growth of microprojections. In the softer-surface OFHC copper, microprojections might grow more easily and thus enhance the prebreakdown electrical field, leading to earlier breakdown. |
