Abstract
This report is the first study on the formation, stabilization and fundamental investigation of free-running helium inductively coupled plasmas (He ICPs). The plasma was operated at 600–900 W with a total helium gas flow of less than 10 L min−1. The shape and the physical appearance of free-running helium plasmas differ markedly from the He ICP sources reported previously using a crystal-controlled generator. Although the free-running helium plasma appears annular, high-speed video studies reveal that the plasma rotates at a frequency of 75–275 Hz. Lateral profiles of