Electrons
The inner electrode of a plasma globe causes an
enormous amount of electrons to fly outward. The Tesla
coil has current going through at a very high frequency,
causing the electrons in the wires to oscillate rapidly.
These electrons start to fly off and form the plasma that
can be seen in the form of miniature “lightning bolts.” In
order for the electrons to fly off the electrode, the
electrode’s voltage has to be high enough. This is
typically around 4 to 5 volts. However, it’s not enough
that the electrons fly off the electrode; they also have
to collide with other atoms or molecules inside the globe
and successfully ionize them, or else plasma won’t be
created. To ionize the gases most commonly found in plasma
globes, the voltage needs to be even higher (around
another 50 – 150 volts, depending on the gas). A standard
plasma globe has a much higher voltage than this, though.
The electrons are basically going on a journey from
the center electrode to the outer glass globe, and from
there their goal is to reach the ground. They will travel
through the glass and take the easiest route that presents
itself down to earth. The route they take depends on a
variety of factors, and helps explain most (if not all) of
the interesting tricks that can be done with a plasma
globe.