Characterization of a plasma source excited by an annular waveguide resonator

Summary form only given, as follows. An experimental set-up for production of large volume discharge has been developed using the surface wave concept and is reported in this paper. A 1500W, 2.45GHz microwave power was obtained by a coherent association of two commercial water cooled magnetrons like those used in microwave ovens. An annular waveguide resonator with axial slots was built to operate as the electromagnetic launcher. The half wavelength slot antenna array extends axially on the inner side of the annular resonator sustaining the plasma in a quartz cylinder of 140 mm in diameter and 1200 mm in length. The microwave power is coupled into the discharge tube by 10 resonant coupling slots which are positioned at regular intervals on the inner side of the annular waveguide. The measurements of the electron density and the electron temperature as function of argon pressure and the axial and the azimuthal positions were performed using a double Langmuir probe. The data acquisition and the calculation of plasma parameters are controlled by a personal computer. Preliminary results indicate an electron number density of the order of 1/spl times/10/sup 12/ cm/sup -3/ and an electron temperature about 1 eV for a microwave power of 1500W and an argon pressure of 1 mbar.