Complex Plasma Structure Observed in the Inlet of an Argon Radio-Frequency Discharge

The presented image was created in the inlet of an argon helicon source. In addition to the helicon mode plasma downstream, there are several competing plasma effects and complex structures that have led to this unique image. The plasma clusters are likely caused by the confinement of plasma within the narrow inlet section of the quartz tube combined with the high cold gas inlet flow rate and the ionization section encroaching upon the inlet tube. These factors have caused the gas to ionize, accelerate through the magnetic field, and be shocked due to the narrow inlet cross section. Other phenomena are investigated and shown to not cause the image.