In this paper

the electrical breakdown charac

teristics of hot SF

6

/N

2

mixed gas are studied. Under the assumption of local thermodynamics and chemical equilibrium

the mass action law is used to calculate the mole fraction of each component of the SF

6

/N

2

arc plasma with a pressure of 0.01～2.0 MPa and a temperature of 300～4 000 K

and analyze the hot state SF

6

/N

2

arc variation process of plasma particle composition with temperature and pressure.Two approximate methods are used to solve the Boltzmann equation

and the electron energy distribution function ofthe hot SF

6

/N

2

mixed gas under different electric fields is obtained. The reduced ionization coefficient and reduced ad-sorption coefficient of each microscopic particle during different collisions are analyzed

and the equivalent break-down field strength（E/N）cr of the hot SF

6

/N

2

mixed gas is obtained. The research shows that the equivalent breakdownfield strength（E/N）cr of the SF

6

/N

2

mixed gas increases with the decrease of the arc plasma temperature

and its in-crease rate is mainly related to the decomposition and recombination characteristics of SF

6

in the mixed gas. Atmo-spheric pressure can effectively suppress the decomposition rate of SF

6

at high temperature

accelerate the recombi-nation process of each particle of the arc plasma

thereby improving the（E/N）cr of the SF

6

/N

2

mixed gas;40%SF

6

/60%N

2

and 30%SF

6

/70%N

2

the（E/N）cr of the N

2

mixed gas in the high temperature range of 2 000～3 500 K is at least high-er than that of pure SF

6

3 Td and 6 Td under the same conditions;below 2 000 K temperature

with the large amount of SF

6

recombination

the mixed gas is equivalent to the breakdown field strength（E/N）cr increases rapidly. The more SF

6

content

the greater the enhancement rate

but it is still lower than the（E/N）cr of pure SF

6

under the s

ame condi-tions. The results of the study can lay a theoretical foundation for solving the problems of high-voltage SF

6

/N

2

mixedgas circuit breaker breaking failure caused by restriking after arcing.