High-Current Arc Gap With Ablative Wall: Dielectric Recovery and Wall-Contact Interaction

The purpose of this study is to examine the effects of wallmaterial ablation and contact materials on the recovery of an arc gap. A capacitive discharge current source provides 60-Hz arc currents up to 8 kA, and recovery is measured by reapplyiag a voltage step of 1 kV at a preselected time after current zero. The arc gap is surrounded by a cylindrical wall of an ablative insulating material. Both contact and wall materials are varied. We find strong dependence of the recovery time on the contact and wall material. For our geometry we observe fastest recovery at a current of approximately 5 kA, independent of wall materials. The interaction of ablated wall-material vapor with the contact material has been observed to degrade gap recovery performance and enhance contact erosion.