Direct comparison of experimental and theoretical results on the antenna loading and density jumps in a high pressure helicon source

Operation modes of helicon discharge excited by double m = 0 antenna at high argon pressures of 51 and 6 mTorr are examined experimentally and theoretically. The behaviour of the discharge, including abrupt density jumps, is found to depend strongly on the relative directions of the currents in the antenna loops (on the antenna spectrum). Experimental results are interpreted in terms of theory which considers the radio frequency power absorption with due regard to the conversion of helicon waves into electrostatic waves. Computed dependences of the plasma load resistance on plasma density and input power, and magnetic field profiles satisfactorily agree with experimental data over a wide range of operation parameters. Thresholds for density jumps estimated from the power balance consideration are also in agreement with experimental values.