jambaugh said:
You're not going to get high frequency electromagnetic radiation like x-rays or even visible light from currents in metals. The x-rays from lightning and from x-ray machines comes from individual atomic excitations. I think lightning simply heats the air hot enough to incandesce with significant x-rays. This isn't surprising given its hotter than the surface of the sun which is itself hot enough to radiate some in the x-ray band.
Yes, agreed, this article, one of the OP's links ...
https://news.nationalgeographic.com/news/2010/12/101223-lightning-x-rays-camera-science-technology/
... speaks of the x-rays being generated by the lighting strike on the metal tower and no comments about anything being generated with interaction with atmospheric atoms present along the strike path
UNFORTUNATELY, they didn't show one of their x-ray images
The lightning strike on the metal tower is much the same as this process you stated, and I can see how that fits...
jambaugh said:
X-ray tubes aim an electron beam into a copper or tungsten target and the high energy electrons knock other electrons in the metalic atoms to high excitation. They then emit x-rays as the electrons return to their ground states.
A "beam/stream" of very high energy electrons striking metal
consuli said:
In electrodynamics an electrical current in metals generates magnetic fields and (photon based) radio signals.
Consuli ... that statement needs correcting, just so you understand correctly
A DC electrical current can generate a magnetic field ... but NOT an EM emission aka radio waves ( Electromagnetic)
An AC electrical current can generate both a magnetic field and an EM emission
consuli said:
If this would be true, the x-ray from a lightning would not be synchronous with the electrical discharge in a lightning-strike, as latest lightning experiments show.
not sure how you come to that conclusion ??
consuli said:
Are x-rays from lightnings and magnetism/ radio signals basically caused by the same quantum electrodynamics effect related to electrons?
X-rays and radio signals are both EM emission
magnetism is not
consuli said:
Is the type of photon-wave generated only dependend from the medium, in which the current flows?
not a well structured question
The type of EM (photons) generated is related to the energy levels injected into the system
As
@jambaugh said earlier...
jambaugh said:
You're not going to get high frequency electromagnetic radiation like x-rays or even visible light from currents in metals.
HI energy excitation is required