Influence of cylindrical Langmuir probe diameter on ion branch of its I-V characteristic

The expression connecting the plasma parameters with the current-voltage (I-V) characteristic of the attracting probe is obtained, and it is compared with the electron branches of the experimental probe I-V characteristics in the range of the probe potentials V≳0. The theoretical and experimental results are in a good agreement. Studies of the influence of a cylindrical Langmuir probe diameter on the ion branch of its I-V characteristic are described. The transition of the ion charges from the plasma to the measuring circuit of the probe leads to a decrease of the ion concentration in the near-probe region limited by the Debye length, as is shown. The relations given in the paper enable one to reconstruct the ion concentration by the experimental I-V characteristic disturbed by the probe.