Method for directing plasma flow to coat internal passageways

A method for coating an internal passageway of a workpiece comprising:

• generating a plasma at a plasma source such that said plasma includes ions of a coating material to be deposited on a surface of said internal passageway;
• directing a controlled flow of said plasma from said plasma source into said internal passageway of said workpiece and exhausting said plasma from said internal passageway;
• and
• increasing ionization of said plasma that is within said internal passageway by applying hollow cathode techniques, including biasing said workpiece and tuning pressure within said internal passageway to induce oscillation of electrons of said plasma within said internal passageway.

A method of coating an internal passageway of a workpiece comprising:

• forming a plasma at a source that is external to said workpiece, such that said plasma includes ions of a coating material;
• flowing said plasma from said source to an entrance end of said internal passageway of said workpiece;
• exhausting said plasma from an exit end of said internal passageway;
• and
• establishing a hollow cathode effect upon said plasma between said entrance and exit ends so as to increase ionization of said plasma that is within said workpiece, including applying a bias and a pressure to achieve said increase in ionization.