Striations in helicon-type argon plasma

In this paper, two types of stationary striations appearing in an argon helicon plasma source are presented. The formation and features of the striations were investigated experimentally under different conditions, including RF power, gas pressure, and external magnetic field. The results show that the striation spacing decreases as the gas pressure increases but does not change significantly along with the magnetic field and the RF power. It is suggested that these striations are strongly related to the non-local effect of electron kinetics in the plasma channel with a weak electric field. The different pressures in downstream and antenna regions will lead to different types of striations in an argon helicon plasma source.