Where's the Plasma in Plasma Cutting

A plasma is an ionized gas that is conducting electricity.

In a modern plasma cutter, dry compressed air is forced through the torch head between the central electrode and the outer cup. Since there is a potential charge between the 2 the compressed air becomes ionized. As it exits through the small hole in the outer cup the air stream is formed into a jet of ionized gas that will now conduct electricity between the inner electrode and the base metal. When this circuit is completed the jet becomes a plasma at around

What allows modern plasma cutters to use compressed air rather than pure nitrogen, is the Hafnium button in the center of the electrode.

A lightning bolt is a plasma. A potential charge builds up between the earth and the sky. The air becomes ionized and ZAP, the lightning grounds between the 2.

Thanks Ernie.

I knew what a plasma is, but until now all I knew about plasma cutters is that air and electricity goes in one end, and metal cutting comes out he other (well, and that I want to get one some day to replace the cutting torch).

Do you know any websites with pretty pictures of the action, so I can show my kid?

These guys have the most information on the process.