Control of the floating potential using dual-frequency

Abstract

Variation of the floating potential in a Langmuir probe was investigated. When the dual frequencies (ω1, ω2) were applied to the probe, the intermodulation frequencies, which are the linear combinations of two frequencies (aω1±bω2), as well as the harmonic frequencies (aω1,bω2), were induced by sheath nonlinearity. However, when two frequencies had a consecutive relationship (ω2=2ω1), the DC components of the intermodulation frequencies (aω1±bω2=0) were generated. This is known as the sheath rectification effect, which causes additional voltage to the floating potential at the probe. In our work, the induced voltage can be controlled by the phase difference between the two consecutive frequencies, and it was found to be in good agreement with the theoretical result, which is governed by the temperature of the high energy electrons.