Patent ID: 7795818

Claim:
A microwave plasma generation method comprising: a step of preparing a cavity comprising an outer conductor with an internal space whose length is an integral multiple of a half of a resonance wavelength, an inner conductor arranged in the internal space of the outer conductor and extending in a length direction of the outer conductor, a double-pipe discharge tube consisting of an inner tube and an outer tube and extending through the outer and inner conductors in a length direction, and adjustment means for adjusting position in an axial direction of the inner tube relative to the outer tube in the discharge tube; a step of supplying a first gas from one end of the discharge tube into the outer tube; a step of forming plasma of the first gas by supplying microwave to the cavity; and a step of adjusting the position in the axial direction of the inner tube by the adjustment means while supplying a second gas from one end of the discharge tube into the inner tube to generate plasma of a mixture of the first and second gases, and releasing the mixture plasma from the other end of the discharge tube.