Toroidal plasma source for plasma processing

A substrate processing chamber comprising:

• a housing that defines a vacuum chamber;
• a power supply;
• a toroidal plasma source contained within the vacuum chamber, said toroidal plasma source including a core;
• a coupling structure configured to transfer energy from said power supply to said toroidal plasma source;
• and
• a substrate support member disposed to hold a substrate within said vacuum chamber such that a process surface of said substrate is opposite and essentially parallel to the core;
• wherein said housing comprises a first interior chamber surface that separates said toroidal plasma source from said coupling structure;
• and
• wherein electric field lines generated by said toroidal plasma source are predominantly parallel to said first interior chamber surface.