抄録
The increment of the DC current in the “Resonance Probe” is calculated from the second oder perturbation term of the electron distribution function, when it is expanded in power of a small amplitude of the AC voltage applied to the probe. The increment δj thus calculated well explains the experimental result (K. Takayama et al; Phys. Rev. Letters 5, 1960, 238), that is, δj retains a finite value for ωo<ωp, shows a resonant peak at ωo= ωp and goes down to zero for ωo>ωp, where ωo and ωp are the applied frequency and plasma frequency respectively, The result of calculation also shows that the ratio of the peak height to the value of δj at ωo=ω is independent of the DC probe potenntial and given by
{(ω2+ν2) / (ωp2+ν2)} |ε (ω) /ε (ωp) |2,
the half width being give by 2ν, where ν is the effective collision frequency of the electron with neutral molecules and ε (ω) is the complex dielectric permittivity of plasma.
