A study of capacitively coupled plasma generation in single-loop antennas

A capacitively coupled plasma generation is studied in a single-loop antenna system, which is commonly used in an inductively coupled plasma production. The capacitive coupling mode appears at relatively low RF powers with two different azimuthal modes of single-loop antenna, m = 0 and m = 1. The coupling mode is confirmed by measuring change in antenna voltage per unit input power and the azimuthal distribution of electron density. The antenna voltage change is remarkably higher in the capacitive mode than in the inductive one but their values are found to be independent of the antenna modes. One of the important findings is that the transition of the capacitive to the inductive coupling plasma mode is taken place at m = I even with fairly lower antenna voltages.