| 摘要 |
A microwave introduction mechanism (43) includes: an antenna section (45) including a plane antenna (54) for radiating microwaves into a chamber (1); a coaxial tube (50) connected to the plane antenna (54) to guide microwaves to the plane antenna (54); and a tuner section (44) provided in the coaxial tube (50) for impedance adjustment. The plane antenna (54) has a plurality of arc-shaped slots (54a) for radiating microwaves, formed such that, assuming that a plurality of imaginary concentric circles, arranged at a spacing equal to an integral multiple of“λg/4+δ”(whereinλg represents the effective wavelength of microwaves, andδis a value that falls within the range 0≰δ≰0.05λg), are drawn on a plane of the plane antenna,“n”(n is an integer not less than 2) arc-shaped slots having the same length are evenly arranged on each imaginary circle, and the plurality of arc-shaped slots form“n”groups where the slots belonging to each group arranged in a radial direction and have the same central angle and the same angular position.
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