Raether–Meek criterion for prediction of electrodeless discharge inception on a dielectric surface in different gases

Abstract

Electrodeless streamer inception on an epoxy surface under AC voltage stress was investigated for different gas compositions and pressures, with a focus on the pressure region below 1 bar. For this purpose, we used a set-up with cylindrical electrodes embedded out-of-axis in a cylindrical epoxy rod. Experiments were performed in N2, SF6, ambient air, Ar and CO2. The discharge inception voltage was measured, from which the critical value K of the ionization integral was reconstructed assuming a non-disturbed Laplacian field distribution. We have validated that for electropositive gases Ar an N2 the generally assumed value of K = 10 is in good agreement with our measurements. For electronegative gases, however, the experimentally obtained values turned out to be considerably higher. We attribute this discrepancy mainly to the statistical time delay of the first electron; to increase the probability of discharge inception in a critical region, it was necessary to extend the critical area by means of applying an overvoltage to the system.

Dielectric Surface Flashover under Long-Term Repetitive Microsecond Pulses in Compressed Gas Environment

“…Because of sufficient diffusion and drift at lower PRFs, the distribution of residual charge carriers in the gas part is less concentrated than that at higher PRFs, and, consequently, the SIL drops very little and even fluctuates with PRFs, especially at a lower PRF in air because of more "gas" paths. [31] is reached. Along the insulator surface, propagation of the streamer is affected by the accumulation effect agents, including trapping center holes and electrons, positive and negative ions, electrons from ionization collision, and metastable species.…”

“…The Raether’s streamer criterion is α e χ = constant ( χ is the critical length of the initial avalanche in mm) [ 31 ], and the breakdown formation delay, τ , can be calculated by τ = χ / ν , so the product of pτ is: …”

“…The accumulation effect contributes to the difference in the current source between a single pulsed flashover and a flashover under RMPs. Secondly, the streamer is initiated from the electron avalanche when the Raether’s criterion [ 31 ] is reached. Along the insulator surface, propagation of the streamer is affected by the accumulation effect agents, including trapping center holes and electrons, positive and negative ions, electrons from ionization collision, and metastable species.…”

Determination of Breakdown Voltage Along the Surface of a Cylindrical Insulator

“…where the effective ionization coefficient αeff(E)=α-η if α>η and αeff(E)=0 otherwise, E is the tangential component of the electric field to the surface of the dielectric, α represents the Townsend first ionization coefficient, η is the attachment coefficient, d is the length of the flashover path and K is a constant equal to 18 [17]. The integration starts at the point of the maximum field, follows a path along the dielectric surface, and ends where the critical value of electric field ECR is reached.…”

A new approach for dielectric breakdown calculation of residual hot gas after arc burning based on particle transport and Boltzmann analysis

“…Recently, the Boltzmann solvers suitable for discharge model have been developed, among which the ELENDIF [48] and BOLSIG are most popular. Hagelaar et al [49] developed BOLSIG+ based on classic BOLSIG, which is more convenient for data exchange between Boltzmann solver and discharge model and is now widely used in gas discharge simulation [50][51][52][53][54]. It is worth noting that in Yousfi et al's work [17] for example, a multi-term solution of the Boltzmann equation was used instead of the two-term solution in BOLSIG+ .…”