Hysteresis control using a DC magnetic field in an argon inductively coupled plasma

Abstract

Control of the hysteresis phenomenon in a high-pressure (250 mTorr) argon inductively coupled plasma was experimentally investigated by applying a DC magnetic field. Electron energy probability functions (EEPFs) were measured with and without DC magnetic fields to obtain electron densities. Without the magnetic field, a hysteresis loop is clearly observed during the E and H mode transitions, but surprisingly, when 20 G of DC magnetic field is applied, the hysteresis loop gets smaller, and it vanishes completely when the applied DC magnetic field is increased to over 40 G. Measured EEPFs show that there is a significant evolution of the EEPFs by DC magnetic field. The EEPF without magnetic field is a Druyvesteyn distribution, but evolves to a Maxwellian-like distribution under a strong DC magnetic field condition. This evolution of the EEPF causes significant reduction in the collisional energy loss epsilon(c) in E-mode. The evolution of EEPFs is explained by a decrease in Ohmic power absorption of low-energy electrons and an increase in electron-electron collisions, and the vanishing of the hysteresis is explained by the suppression of nonlinear changes in EEPF and nonlinear changes in collisional energy loss.