The effects of machinery size

vacuum

gas composition

pressure and humidity on the high voltage of electrostatic accelerator are studied.It is found that there is a pressure-resisting blind area in 67～0.1 Pa vacuum

the insulating property of gas is improved along with the rising of pressure

the increasing trends of breakdown voltages of N2 and CO2 becomes slow

however

that of their mixed gas still increases by a line above 0.6 MPa.The result is the best when the proportion of N2 and CO2 is 80∶20

by adding SF6 can raise insulating property evidently and the humidity doesn’t influence the breakdown voltage.