抄録
Observations have been made of ion resonances which show a minimum in the d.c. current of an rf probe near the plasma-ion frequency, fpi=(Ne2⁄πM)1⁄2. The hot-cathode discharge tubes used were filled at a pressure of 3∼10−3 mmHg with one of the following gases: He, Ne, Ar, and Hg. The behaviour of the ion resonance has been observed, in comparison to the electron resonance. A frequency variation proportional to the square root of the plasma number density was observed in the ion resonance as in the electron resonance, but the dependence of the frequency on the probe voltage was different. In the former the dependence of the frequency on the ion mass agrees with the formula for the plasma-ion frequency.
