Electrical tree initiation due to bombardment of metastable excited Ar

Ac tree initiation voltage of Ar-impregnated LDPE is much lower than vacuum-degassed LDPE, and even lower than normal (air-impregnated) LDPE. Injected electrons are accelerated in polymer free volume. In Ar-impregnated LDPE, the hot electrons collide with Ar atoms in free volume and excite them to metastable level. Metastable atom can return to ground state after transferring the energy by collision with free volume wall. The energy transferred from metastable atom breaks polymer bond of free volume wall, and creates micro cavity in short time.

[1]  C. Laurent,et al.  Optical emission due to space charge effects in electrically stressed polymers , 1997 .

[2]  N. Shimizu,et al.  Role of electron impact in ac electrical tree initiation , 1997, Proceedings of 5th International Conference on Properties and Applications of Dielectric Materials.

[3]  N. Shimizu,et al.  Electrical tree initiation in polyethylene absorbing Penning gas , 1996, Conference Record of the 1996 IEEE International Symposium on Electrical Insulation.

[4]  K. Horii,et al.  The Effect of Absorbed Oxygen on Electrical Treeing in Polymers , 1985, IEEE Transactions on Electrical Insulation.

[5]  K. Horii,et al.  Space‐charge effect on local electric breakdown of polyethylene at 77 K , 1977 .

[6]  Y. Toriyama,et al.  Relation of Water Tree and Physical-Properties of PE , 1977 .