Abstract
A new microwave plasma source has been successfully developed. This plasma source has high density and large area characteristics due to the excitation of plasma surface wave by a tunable surface wave cavity. The tunable surface wave cavity is composed of a vane type slow wave structure. It is operated in the p mode and resonant at 2.45 GHz. A linear theory is developed to design the cavity and analyze the waves in the plasma guided by a vane-type slow wave structure. It shows that by choosing a proper dimension of the cavity, the p mode resonant frequency will not change after the excitation of the plasma. In experimental aspect, good characteristics of this plasma source are verified. The plasma area is in access of 30cm’20cm with a uniformity ±5% and plasma density as high as 6’1012 cm-3. The plasma temperature is ~1.5eV. Above all, the number of the periods of the p mode cavity can be increased without changing the resonance frequency and the distribution of the microwave fields such that this plasma source is easy to up-scaled. In addition, the plasma resonance in a surface wave sustained plasma is first clearly characterized. The amplitude of the electric field of the microwave becomes a local maximum in the location where the local plasma density is equal to a critical value. In accordance with the theory, the measured maximum value of the resonance response is proportional to the plasma density gradient while the measured spatial width of the plasma resonance is inversely proportional to the plasma density gradient. High-energy electrons are observed in the plasma resonance.