Method of coating inner and outer surfaces of pipes for thermal solar and other applications

A method for enabling coating comprising:

• providing a chamber which defines an enclosed area along an axial region;
• positioning a hollow conductive member within said enclosed area so as to be coaxial with said axial region;
• supplying a reactive gas within spacing between said chamber and said conductive member and within an interior of said hollow conductive member;
• and
• establishing conditions for a hollow cathode effect along said enclosed region including within said interior of said hollow conductive member and between an interior surface of said chamber and an exterior surface of said hollow conductive member so as to generate a high energy plasma that includes coating material to be deposited, said conditions including maintaining a cooperative arrangement of pressure and biasing for achieving said hollow cathode effect, wherein establishing said conditions includes biasing anodes at opposite open ends of said hollow conductive member.

A method of coating at least one exterior surface of at least one workpiece comprising:

• providing a chamber having a multi-dimensional interior surface with a particular geometry with respect to an axis of said chamber;
• positioning said at least one workpiece within said chamber such that a spacing between said multi-dimensional interior surface and said at least one exterior surface remains substantially fixed along an axial direction;
• and
• establishing conditions to maintain a hollow cathode effect within said spacing between said interior surface and said at least one exterior surface, thereby defining a hollow cathode effect region, said conditions including biasing anodes at opposite ends of said hollow cathode effect region and including biasing said interior surface and each said workpiece as cathodes, wherein establishing said conditions further includes pressurizing plasma residing within said spacing;
• wherein establishing said conditions includes biasing said interior surface of said chamber as a cathode having a bias voltage that is different than a bias voltage applied to each said workpiece.

A method of coating at least one exterior surface of at least one workpiece comprising:

• providing a chamber having an interior surface with a cylindrical geometry with respect to an axis of said chamber;
• positioning said at least one workpiece within said chamber such that a spacing between said interior surface of said chamber and said at least one exterior surface remains substantially fixed along an axial direction, wherein said at least one exterior surface to be coated defines a cylindrical shape that is coaxial with said interior surface and wherein said at least one workpiece includes a tube having a tube interior and wherein establishing said conditions to maintain said hollow cathode effect is simultaneously applied within said tube so as to coat said interior of said tube;
• and
• establishing conditions to maintain a hollow cathode effect within said spacing between said interior surface and said at least one exterior surface, thereby defining a hollow cathode effect region, said conditions including biasing anodes at opposite ends of said hollow cathode effect region and including biasing said interior surface and each said workpiece as cathodes, wherein establishing said conditions further includes pressurizing plasma residing within said spacing;
• wherein materials applied to coat said tube interior and said exterior surface are different.