Get a length of wide glass tube, stick foil to the outside, and suspend a thin wire down the centre between two SYNTHETIC bungs. Apply the hot side of the coil to the centre wire. The output comes straight from the coil, do not rectify or use capacitors. A 1 microfarad paper capacitor is connected across the coil primary, one can be found across the points of an old car ignition system. A buzzer is used to interrupt the coil primary current. Connect the low voltage transformer to the buzzer such that it runs as a buzzer, and connect the car coil in parallel with the buzzer coil.
If you use enough voltage to get visible sparks the ozone will disappear, so turn it down a bit. If you use rubber bungs, there will be no ozone, and shortly no bungs. If you try an electrolytic, it will explode.
Another way is to get a mercury vapour lamp with a quartz tube, like used in an EPROM eraser, and run that in a tube. A big mercury lamp with a quartz capsule inside a glass bulb can be used, you have to break the glass. Dont get the ballast wrong.
If you bugger about with mercury lamps, dont look at them when running.
Wear glasses with glass lenses. The ultraviolet will hurt your eyes badly.
Please dont swear at me when you wake up at 2am with your eyes full of sharp sand, just DONT LOOK AT THEM.
Best of luck :twisted: