Tesla supposedly had plans to install boilers in the Wardencylffe Tower... Ever experiment by adding steam to the surrounding area? Specifically in the area of the capacitance or second discharge.
There could be something happening with ozone and its ability to cascade ions out of air...particularly between steam and nitrogen. Some studies show NOx's can be easily made. There is a possibility that nitrogen is a source of extra electrons but requires something to react with to release these ions. Something that has intrigued me for sometime.
RE: Verifying Tesla’s theory - first experiments