Calculation of discharge inception voltages in argon+SF6 mixtures under nonuniform electric fields

In this study discharge inception voltages in Ar+SF/sub 6/ binary mixtures are calculated based on the streamer criterion under nonuniform electrostatic fields. The calculations are done for different contents of SF/sub 6/ in the mixture and the total gas pressure is varied as a parameter from 50 kPa to 100 kPa. The computed discharge inception voltages using the streamer criterion are found to be in good agreement with the experimental data

Response of N/sub 2/ + SF/sub 6/ to limiting orthogonal electric and magnetic fields

Many studies on N/sub 2/+SF/sub 6/ binary gas mixtures have been reported in the literature as an alternative to pure SF/sub 6/ which is used in high-voltage power apparatus and systems. However, information on the response of N/sub 2/+SF/sub 6/ to limiting orthogonal electric and magnetic fields is lacking in the literature. Therefore, due to the technical importance of this binary mixture, it is the objective of this study to employ the Monte-Carlo technique to determine the response of N/sub 2/+SF/sub 6/ mixtures to crossed electric and magnetic fields

Back diffusion of electrons in N2 subjected to crossed fields

In the E/N range of 50 Td - 700 Td (1 Td = 10 -21 Vm 2 ), the back diffusion process for nitrogen subjected to crossed fields are investigated at B/N values ranging from 0 to 24.24 × 10 -25 Tm 3 by means of a Monte Carlo technique employing realistic collision cross sections. It is observed that at constant electron emission energy of 1.0 eV, for a given E/N the escape factor decreases as B/N increases. It is also observed that in the lower E/N range in crossed fields the escape factor is smaller than those of the higher E/N range. The escape factor on the magnetic deflection angle is evaluated and a dependence on the magnetic field is observed in crossed fields in the given ranges of E/N and B/N

Effective ionization coefficients in binary gas mixtures of argon and SF6

The effective ionization coefficients are evaluated in the E/N range of 60 /spl les/ E/N /spl les/ 420 Td for the Ar + SF/sub 6/ binary gas mixture at various mixture ratios. Also, reported in this paper are the electron mean energies and drift velocities at a given E/N for various mixture ratios

Non-Uniform Field Breakdown of Ar +SF6 under Negative Polarity Impulse Voltages

In this study, negative-polarity, standard lightning impulse voltages with different magnitudes were employed throughout the experiments. The percentage of SF 6 in Ar was varied from 1% to 90% and from 1% to 75% at a total gas pressure of 50 kPa and 100 kPa, respectively. The breakdown voltage of each gas mixture was recorded at 50% breakdown probability. Similar to earlier studies under static electric fields it is observed that the breakdown voltages of Ar+SF 6 has increased dramatically when mixed with a small percentage of SF 6 under impulse voltages. However, the breakdown voltages were found to be higher than positive polarity, non-uniform and uniform fields

Calculation of breakdown voltages of short air gaps

In this study, breakdown voltages in air are calculated based on the streamer criterion and compared with experimental data. The calculations are done under standard atmospheric conditions, and the computed breakdown voltages are in good agreement with the experimental findings