Karl,

I think we need now a nice experiment which will prove that radiant energy observed here is not HF normal current or how those two are related to each other.

What was the frequency used in your experiment on primary oscillator side ? How we can measure frequency of output stage where bulbs are connected ? I think it could be possible with a special bulb which generate different spectrum of light depending on current frequency but I don't know where to find it or how to make it.

Did you ever tried to place broken incandescent bulb on output stage of your hairpin circuit ?