In this paper, an attempt is made to develop an analytical density correction method for cylindrical Langmuir probes displaying end effects caused by finite probe length and sheath expansion as well as potential inhomogeneities within the plasma. The correction depends on probe as well as plasma parameters such as the Debye length, the probe radius, the probe length, and the applied potential, and is based on the deviation of the measured characteristics from the ideal form according to orbit-limited conditions. A comparison with real data was carried out and showed the applicability of the method. Based on this correction, accurate Langmuir-probe electron-density measurements are possible in the very low density ionospheric plasma (ne>or approximately=103 cm-3) as well as in the disturbed regions around rockets or satellites, especially in the wake. The range of application of the conventional Langmuir-probe method has been extended.
Electron density measurements in low-pressure plasmas using cutoff probes and comparison with hairpin and Langmuir probes