Dielectric breakdown properties of Al-air mixtures

In order to investigate the influence of aluminum vapor on the breakdown performance of air,this paper makes a study of the dielectric breakdown characteristics of Al-air mixture in the temperature range of 300-5000 K at atmospheric pressure.A Boltzmann analysis method is used to deal with the electron energy distribution function(EEDF),the reduced ionization coefficients(α/N),the reduced attachment coefficients(η/N)and the critical reduced breakdown strength((E/N)cr)so as to explore the influence of temperature and mixing ratio on the dielectric breakdown properties.In the temperature range of 300-2000 K,the property of the mixture is mainly determined by the mixing proportion of aluminum vapor because the composition of particles remains unchanged.In the temperature range of 2000-2500 K,the decomposition of Al2O_(2)leads to the increase of aluminum oxides and NO,and a rise in the percentage of highenergy electrons as well as the increment ofα/N.Also,the joint action of O_(2)and NO makesη/N increase first and then decrease,and(E/N)crgoes down to a smaller temperature range.An increase in the proportion of aluminum vapor causes(E/N)crto decrease in the low-temperature region and to increase in the high-temperature region,which will reduce the transition between these two temperature regions.