Study of suitable gas mixture improving the breakdown properties for substitution of SF6

Electrons are supplied even after the breakdown in nitrogen gas. The phenomenon is assumed to be introduced by energy accumulation by nitrogen atom or molecule. To reduce the number of electrons supplied after breakdown, it is necessary to de-excite the energy with nitrogen atom or molecule. The results showed that mixture of small amount of nitrogen mono-oxide or carbon dioxide was effective to reduce the energy. However, in the region of short time after the breakdown, its effect was not observed. Mixture of SF_6 was also effective to reduce the number of supplied electrons by electron attachment effect. CF_3I showed the most effective to reduce the number of supplied electrons. However it was shown that the reduction of its dissociation was important.