Development of a compact helicon plasma source with two sets of ring array permanent magnets for the study of blue core plasma.

Abstract

A compact helicon plasma source for the study of helicon plasma, especially for the study of blue core plasma, is designed and developed with permanent magnets (PMs). The structure of the PMs consists of two sets of ring array magnets with opposite magnetization. This structure can provide a higher magnetic field with fewer PMs, which is helpful for controlling the device's mass. A quartz tube with 50cm in length, 5cm in outer diameter, and 0.3cm in thickness is used. Argon helicon plasma is produced at ∼38 sccm (3.4Pa inlet chamber and 0.122Pa diffusion chamber) by a radio frequency (RF) power of ∼13.56MHz using a helical antenna under a high magnetic field (∼1600G). Preliminary results measured by the Langmuir probe, photomultiplier tube (PMT), CCD, and Hall coil are applied to characterize the helicon plasma in this source, such as the mode transition and the formation of the blue core with the RF power variation. The device generates the blue core (W mode) plasma at a lower power of about 200W, and the energy coupling efficiency is as high as 65%.