How can you move a plasma?
The Demonstration: A strong magnet is used to move a plasma around inside a tube.
The Physics:
The plasma tube is used to show you the unique behavior of plasmas.
Plasmas are extremely hot gases, at least 10,000 degrees! When gases
get this hot, the atoms are moving very fast and bumping into each
other all over the place. They bump into each other so hard that the
electrons are knocked off of the atoms leaving a mix of negatively
charged particles (electrons) and positively charged particles (ions).
Whenever you see a spark or a stream of electrons, you are seeing a
plasma. Other plasmas can be seen with the Tesla Coil and the Jacob’s
Ladder.
The plasma tube is a glass tube filled with air. Because it takes so
much energy to make a plasma, we have to first pump out some of that
air using a vacuum. When there is only a little bit of air left in the
tube, we apply energy in the form of a high voltage to excite the atoms
of air. The resulting plasma looks like a neon sign that you may see in
a store window. There is a good reason for this, as neon signs are also
plasmas.
The plasma in the tube can be moved around using a strong magnet.
Because plasmas are so hot, the only way to control them is using
magnets. Electricity and magnetism are very closely related (see electromagnets).
This means that moving charges, such as the electrons in a plasma, can
behave as a magnet and be affected by a magnetic field. Scientists use
strong magnets to confine plasmas that are millions of degrees!
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Page Updated 8/29/07