Influence of polished surface of electrodes on high electrical breakdown for water dielectric

A coaxial electrode experimental apparatus with water dielectric capacitor was set up, high voltage breakdown experiments for polished and unpolished surface of electrodes with microsecond charging were respectively carried out. The experimental results are shown as follows: (1) polished surface of electrodes effectively improves the capacity to maintain the high electrical voltage for water dielectric; (2) breakdown stress for surface polished electrode of roughness (0.4~0.8 μm) is in better agreement with Martin formula than roughly polished one(1.6~3.2 μm); (3) primary mechanism to increase the breakdown stress of water dielectric is that, field emission currents to heat the bubble become weak on the cathode for polished surface of the electrodes and the time lag to breakdown is incre