Azimuthally symmetric pseudosurface and helicon wave propagation in an inductively coupled plasma at low magnetic field

The mode transition from a capacitively coupled mode (E mode) to an inductively coupled mode (H mode) was observed in an inductive Ar plasma source by applying an axially uniform low B field. The applied fundamental rf was 13.56 MHz and many harmonic components were observed. A beat and standing wave patterns of azimuthally symmetric (m=0 mode) first and second harmonic pseudosurfaces and helicon waves were measured at various densities (n∼9.0×1010–2.2×1011 cm−3) and B fields (12–28 G). Wave propagation mode changes, from pseudosurface to helicon waves and from helicon to pseudosurface waves, were observed at critical conditions, ωc/ω>3.0 and n∼2.2×1011 cm−3.