Characteristics of Large Diameter, High-Density Helicon Plasma with Short Axial Length Using a Flat Spiral Antenna
نویسندگان
چکیده
A large diameter (up to 73.8 cm), high-density helicon plasma with short axial length (≤ 81 cm) has been successfully produced using a flat spiral antenna. The electron plasma density can reach up to ∼ 10 cm−3 with the input radio frequency (rf) power of < 4 kW for various axial lengths, and the density scaling as a function of the axial length is in good agreement with expectations. The stronger the degree of magnetic field convergence from the antenna to the bulk plasma region is, the lower the minimum input rf power required to obtain a helicon plasma is. In the convergent magnetic field configuration, radial profiles of the excited rf magnetic field show the exicitation of higher order radial mode in addition to the component of the fundamental one. The manifestation of higher order mode is closely related to the magnetic field configuration and the rf radiation pattern of the flat spiral antenna.
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