Speaking of arcs... my main workshop has two doors; one for me and one for the cats. Pic1.
The cat flap is good in theory, but not so great in practice. One cat is too thick to ever figure it out. And one of the local possums is smart enough to use it, to get to the cat food bowls inside. That's bad enough, but having got inside it also then decides to explore for comfy possum nests.
Which in a large workshop there are plenty of, among the expensive and precious equipment and storage areas.
But I highly disapprove. Anyone who knows how destructive possums always are will understand. They chew everything (including wiring - both signal and mains), and their pee is corrosive enough to eat through stainless steel (an actual thing that happened here.) Also they pee everywhere they go, to mark their path. So hopefully people won't frown on the next part too much.
Pic 2 is a small hand held Tesla coil. These are normally used to find vacuum leaks in glassware, by observing where electrons can get through, causing more visible ionization in the low pressure internal gas.
It's currently taped on a stick, so it can be poked into small spaces in cupboards and other difficult to access spaces a possum would like. This setup is the result of a recent argument with Mr Possum, over whether he's allowed in my workshop. The Possum Prod (Tesla on a stick) worked pretty well, and wins that argument on the spot.
Fortunately that time he'd chosen a cupboard full of non-electronic stuff (lab glassware and kitchen utensils mostly) so the Tesla coil could be used without destroying equipment. But possums are incredibly stubborn, and he came back in the next night briefly. I guess the next step is a cage trap and transporting to some very distant bushland.
Pic 3 shows the type of arcing these little units make. Nothing visible unless it's held within an inch of something. Concrete, possum...
Pic 4 is it in contact with a light bulb. The glass is still insulating, so there's ionization streamers radially on the surface, and a capacitively coupled streamer inside.
Pic 5 is a few seconds later. A point on the glass has heated up enough from the high frequency dissipation, to become conductive. The hot spot glows, there's no side streaming, and a stronger internal ionization path.
20170502 edit to add pic: A funny looking cat.
20170505 edit to add pic: Caught. Will be relocated to a nice new (and distant) bush home today.