315A theoretical analysis is made of the resonance phenomena in the radio-frequency probe experiments of Takayama et al. The Boltzmann-Vlasov equation is solved under the action of an external rf electric field. The solution gives the resonance peak of the de component of the electron current to the probe at the plasma frequency. For a partially ionized plasma, the peak-height IJj and the half-width ilah/2 are given by the following formulae.
iJW1f2=2Y.For fully ionized plasmas, they are determined· as follows,In the above expressions, T is the electron temperature, wP is the electron plasma frequency, and ,ld is the Debye length. j 0 is an electron current density to the probe when no oscillating field is superposed on it, IJV is the amplitude of the superposed rf voltage, /1 (z) is the modified Bessel function of the first order. L is an effective penetration depth of the external field. V is the potential difference between the plasma space and the probe, and y is the effective collision frequency of the electron with neutral molecules. The present theory confirms that the analysis of the resonance peak in the radio-frequency pro~e experiments is .an effective method for the plasma diagnosis. § I.. IntroductionAs is well known,Il the electron current density Jo to the Langmuir probe IS given bywhere · JC is the Boltzmann constant, e and m are the charge and the mass of the electron, respectively. With Eq. (1) the plasma electron density n and the at Kainan University on April 5, 2015http://ptp.oxfordjournals.org/ Downloaded from
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