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(or “ionized”) and the electrons begin to break off from the atoms
and move around freely. Unlike a typical gas, plasma is electrically
conductive and responds strongly to the effects of electromagnetic
fields. Applying an electromagnetic field to plasma can cause it to
form into structures such as filaments, beams, and double layers.
These structures are what give shape to the moving tendrils of light
that you see in the plasma globe.
When a plasma globe is turned on, the gas inside the globe is
charged with a high-voltage current from the power supply. The high
voltage of the current causes the gas to ionize and turn into plasma.
This turns the entire plasma globe into a conductor, allowing the
electricity from the electrode to travel through the plasma and
escape through the air.
At the same time, the power sup-
ply emits a high-frequency current,
alternating at thousands of times
per second, and this high-frequen-
cy current creates an oscillating
electromagnetic field. This electro-
magnetic field interacts with the
plasma and causes the electrons
and ions to move around, exciting
the surrounding atoms. When the atoms
become excited, they quickly release their energy, and this energy is
emitted in the form of light. As the electricity from the center of the
globe attempts to escape, it creates ion trails, and these trails act
as a path for the other electrons. When a large quantity of electrons
move along the same path, a plasma tendril is formed, and the
atoms emit enough light that the tendril becomes visible. The color
of the light you see depends on what gases are present inside the
globe.
The Northern Lights are an example of ionized plasma
from the sun interacting with the earth’s magnetic field.
