Capacitor Lug Retrofit
I purchased this capacitor with what turned out to be a unique connector. After consulting the collective wisdom of 4hv.org, we concluded that this little lug was part of an integrated spark gap.
I had naively thought that this was some kind of common energy storage connector, like a AA battery. Nope. The capacitor was reported to have been removed from a working dye laser. It's was made by Hi-Voltage Components, Inc. Unfortunately, I think that this company has disappeared, making it difficult to find any specifics on its construction and limitations. The copper (possibly copper-tungsten) top connector was corroded a bit.
I cleaned the connector with a 1:1 (vol.) solution of lemon juice and sodium chloride. With a bit of elbow grease, it got nice and shiny.
I needed a form to contain the silver conductive epoxy that I was going to use to adhere a 1/4-20 brass bolt that would serve as the final connector. Since I only had .35oz of the expensive epoxy, I found a tape core 1" in diameter and 1/2" in height. I Dremel-ed off the outer tape core circle, leaving a rough ridge for the future potting compound to gain mechanical purchase.
I filled the form with conductive silver epoxy and gave it a week or so to set and outgas, just guessing that it would be best to give it a long time as I was about to encapsulate it in white epoxy.
Done! Although I didn't take a picture with the white epoxy surrounding the form, I later cut a 1/4" thick PVC circle and sealed it to the capacitor with clear Dow Corning 734, a flowable sealant that I've come to rely on for electronics work.