US Patent 7166816 Inductively-coupled torodial plasma source

Apparatus for dissociating gases includes a plasma chamber comprising a gas. A first transformer having a first magnetic core surrounds a first portion of the plasma chamber and has a first primary winding. A second transformer having a second magnetic core surrounds a second portion of the plasma chamber and has a second primary winding. A first solid state AC switching power supply including one or more switching semiconductor devices is coupled to a first voltage supply and has a first output that is coupled to the first primary winding. A second solid state AC switching power supply including one or more switching semiconductor devices is coupled to a second voltage supply and has a second output that is coupled to the second primary winding. The first solid state AC switching power supply drives a first AC current in the first primary winding. The second solid state AC switching power supply drives a second AC current in the second primary winding. The first AC current and the second AC current induce a combined AC potential inside the plasma chamber that directly forms a toroidal plasma that completes a secondary circuit of the transformer and that dissociates the gas.