tree" is a name given to a tree-like figure appearing in a water-impregnated polymer insulating cable.

It has been suggested that in alternating current (AC) most carriers injected at electrodes during a half cycle are ejected during the next half cycle, so the net balance of charge on a cycle is practically zero. However, a small fraction of the carriers can be trapped at levels deep enough to retain them when the field is inverted. The amount of charge in