>>13616262>>13617709you can't see x-rays.
the electromagnetic spectrum contains, in order of increasing wavelength: x-rays (ionizing radiation), ultraviolet light (non ionizing but can cause chemical changes inside human bodies), and visible light (that you can see), and other large wavelengths beyond the point of this shitpost.
you are witnessing electrostatic discharge; the process by which the electric potential / voltage between two objects is large enough that the medium between can be used as a path of current per ohm's law I=V/R. the resistivity of air is very high compared to normal means of moving current such as copper wires, and therefore an immense amount of heat is generated.
the visible light produced is from the air being heated as it is ionized by the large EPD/voltage to be used as a path for current.
t. electrical enginigger who works in nuclear
>>13616247op's first question is "what is the magnitude of x-ray radiation needed to cause harm by means of acute radiation sickness"
and the answer to that is ~100 REM but it won't be immediately incapacitating at all.
in my general understanding, radiation as a weapon isn't effective, and generally you would need to be subject to a nuclear meltdown or blast to take immediately incapacitating levels of acute radiation sickness (but you will be ashes from the heat before that matters).
"harm" needs to be defined before this question can be answered better. at my work, a yearly chronic dose rate of 5 REM is acceptable and the general nuclear industry standard is a yearly dose rate of 25 REM is acceptable. i think. so to harm someone, any value higher than 25 REM could cause unknown harmful long term effects. or maybe nothing would happen.
if OP wants to commit terrorism he should look for other ways to do it