Microwave plasma torch and method for generating plasma

摘要

The microwave plasma torch of the invention includes: a vacuum container having an evacuating apparatus; a coaxial waveguide including an inner conductor and an outer conductor, a first end portion of the coaxial waveguide being connected with a microwave supplying apparatus for supplying a microwave and a second end portion of the coaxial waveguide being connected with the vacuum container, thereby introducing the microwave supplied from the microwave supplying apparatus into the vacuum container along a waveguide axis of the coaxial waveguide; and a gas supplying apparatus for injecting a gas into the vacuum container along a plurality of injection axes. In the microwave plasma torch, at least two of the plurality of injection axes do not cross the waveguide axis in the second end portion, and do not exist in a plane vertical to the waveguide axis, and a ratio of a diameter of the inner conductor to a diameter of the outer conductor in a vicinity of the second end portion decreases from the first to the second end portion along the waveguide axis.