The sketches look great to me. As I said I do not really understand the tubes of force theory so I can not help you there.
About the Aurora Borealis, I am not sure, I have never given it much thought. But if you ask me if it is excitation of the medium (=electricity) that is causing it, I would say that that is highly improbable. What would excitation of the medium look like? what would it mean? Excitation of an ordinary gas means that the electrons of its atoms get into a higher energy level. But the 'atoms' of Tesla's medium do not have electrons in them....