Effects of axial magnetic field on discharge characteristics of inductively coupled plasma

摘要

To study the effects of an axial magnetic field on the discharge characteristics of Ar inductively coupled plasma, a set of discharge plasma generators was designed. The plasma parameters such as electron temperature and electron density were diagnosed with a Langmuir probe. The research showed that as the air pressure was 10 Pa, with the increase in axial magnetic field intensity, the electron temperature and electron density reduced continuously in the central discharge region, while the threshold power of discharge mode transition increased constantly. The analysis suggested that due to the circumnutation of charged particles acted upon by Lorentz force, the introduction of the axial magnetic field had a constraint effect on the particle movement and energy transfer and decreased the collision between the high-energy electron in the discharge sheath and the electron in the central region, thereby reducing the electron density and inductive coupling efficiency. From further analysis of the electron energy probability function, it could be found that in the E mode, the constraint effect of the axial magnetic field on electron motion was more obvious. The proportion of the high-energy electron (27 eV) was apparently higher than that in the H mode, and the electron energy distribution was more even. This was caused by less electron collision.