Lightning in Vacuum
I know that lightning colour depends on atmospheric
conditions, but if electrical discharge were to occur in a perfect
vacuum, what colour would it be ?
Actually, for an electrical discharge to occur, some material has to be
present, so it could not happen in a 'perfect' vacuum. What usually happens
is that the electrical field builds up until molecules of the electrodes start
to move from one electrode to the other. This generates a plasma (ionized gas)
that conducts the arc. This in turn heats the electrodes up and carries more
material with it, which intensifies the
arc, and the cycle repeats until a steady state is reached. So the color of
the arc would depend on the electrode material.
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Update: June 2012