The apparatus is capable of producing corona associated with high voltage discharge at atmospheric pressure.
Two rods are supported vertically between high voltage insulators and two high voltage leads are connected to the insulators so that they can be attached directly to the terminals of a transformer available with the equipment.
There are ladders available. The small one is about 2 feet high and runs at 15KV while the big one is 6 feet high and runs at 25KV.