Three-Dimensional Mapping of Ion Density in a Double-Layer Helicon Plasma

An investigation of the ion density produced inside the Chi Kung reactor at 250 W and 0.30 mtorr was performed through Langmuir probe measurements. Three-dimensional interpolation combined these data to produce a 3-D density volume. The resulting image was used to identify three distinct regions of differing density: power deposition, acceleration, and expansion. The ion density over these regions was found to vary from ~1.3 times 10¹⁰ to ~2.7 times 10¹¹ cm^-3.