Production Mechanism of a Large-Diameter Uniform Electron Cyclotron Resonance Plasma Generated by a Circular T E ₀₁ Mode Microwave

To clarify the production mechanism of a large-diameter uniform electron cyclotron resonance (ECR) plasma generated by a circular TE₀₁ mode microwave experimentally, the wave propagation characteristic in the plasma is measured with an interferometer. It is shown that a microwave introduced into the chamber is transformed mainly into an electron cyclotron wave and then entirely absorbed around the resonance point. Furthermore, it is experimentally proven that the correspondence between the radial distribution of the electric field intensity of injected microwaves and that of waves propagating in plasma may depend on the magnetic field intensity around the injection point. It is also confirmed that it is necessary to optimize the magnetic field configuration to generate a uniform ECR plasma since the absorption region of microwaves is as wide as from ω/ω _{c e} ∼0.65 to adjacent to the resonance point.