Patent Number: 
Section: claims

1. A waveguide of a microwave ion source, comprising:an elongated waveguide main body of the microwave ion source, the elongated waveguide main body being made of a material selected from the group consisting of a boron nitride and an aluminum oxide; anda thin film defining a microwave path made of a titanium nitride covering an outer peripheral surface of the waveguide main body, wherein the outer peripheral surface of the waveguide main body is bonded to the thin film. 2. waveguide according to claim 1, wherein the waveguide main body is made of a boron nitride. 3. The waveguide according to claim 1, wherein the outer peripheral surface of the waveguide main body is bonded to the thin film. 4. The waveguide according to claim 1, wherein the waveguide main body is made of an aluminum oxide. 5. The waveguide according to claim 1, wherein the waveguide main body has a wedge shape. 6. The waveguide according to claim 1, wherein the thin film is formed by a CVD method. 7. waveguide according to claim 1, wherein the thin film has a thickness of 10 to 500 μm. 8. The waveguide according to claim 1, wherein the thin film has a thickness of 200 μm. 9. The waveguide according to claim 1, wherein a reflection of an electromagnetic wave on the outer peripheral surface of the waveguide main body is suppressed.