Plasma activated deposition of an insulating material on the interior of a tube
AssigneeU.S. Philips Corporation
InventorsHans Rau, Petrus F. De Jongh
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Abstract
In the internal coating of a tube of an electrically insulating material by a second electrically insulating material by reactive deposition of the second electrically insulating material from a gas mixture which is passed through the tube, the desposition is activated by a plasma which is produced by microwaves and is reciprocated in the tube. A method with low energy consumption and a device of a simple construction are made possible in that the plasma is excited by TE 011 resonance in a cylindrical resonator.
Claims4
A method for coating the inside of a longitudinally extending tube of a first electrically insulating material with a second electrically insulating material, the tube having open ends thereof attached to a system for passing through said tube a gaseous source of the second electrically insulating material, said method comprising the steps of:
- a. disposing the tube in a furnace comprising a thermally insulating tubular body surrounding at least a substantial length of said tube;
- b. disposing around a portion of the length of the tubular body surrounding a portion of the length of the tube to be coated a cylindrical microwave resonator configured to produce TE.sub.011 microwave energy in the tube;
- and
- c. reciprocating the resonator along the length of the tubular body while producing said microwave energy, said energy both heating the tube and producing from the gaseous source a plasma to effect reactive deposition of the second electrically insulating material onto the inside of said tube.
An apparatus for coating the inside of a longitudinally extending tube of a first electrically insulating material with a second electrically insulating material, said apparatus comprising:
- a. a gas supply system adapted for attachment to open ends of the tube for passing through said tube a gaseous source of the second electrically insulating material;
- b. a furnace comprising a thermally insulating tubular body for surrounding at least a substantial length of said tube;
- c. a cylindrical microwave resonator configured for disposition around a portion of the length of the tubular body surrounding a portion of the length of the tube to be coated and configured to produce TE.sub.011 microwave energy in the tube;
- and
- d. means for reciprocating the resonator along the length of the tubular body while producing said microwave energy, said energy both heating the tube and producing from the gaseous source a plasma to effect reactive deposition of the second electrically insulating material onto the inside of said tube.
Dependencies are inferred from the claim text.