High pressure N/sub 2/, O/sub 2/ and air mixture plasmas produced by a radiofrequency Helicon plasma source

Summary form only given, as follows. High pressure (10-760 Torr) plasmas of N/sub 2/, O/sub 2/ and air gas mixture are investigated in this work by using a radiofrequency helicon plasma source. Langmuir probe theory and collisional helicon wave propagation characteristics at high pressure are utilized to obtain plasma density and electron temperature. The wave modelling results show that higher rf wave frequency and applied magnetic field will enhance electromagnetic wave penetration and absorption profiles for these highly collisional plasmas. The higher rf frequency on plasma properties will be carried out by means of a broadband (2-200 MHz) amplifier. A balanced driven matching circuit will be developed to efficiently couple rf power to plasmas at higher rf frequency regimes. Different kinds of rf antennas including multiple turn helices are studied to obtain efficient coupling at high pressures. Seed gases including Ar and TMAE and high voltage spark initiation will also be examined to reduce the power requirement to create high pressure plasmas. Wave B/sub z/-field profiles and antenna input impedances are measured and compared to the 2-D MAXEB code. We will utilise a nonuniform magnetic field with a cyclotron resonance zone to assist starting these high pressure plasmas.