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A comparison method of high-temperature plasma diagnostics, developed by Shevelko [Quantum Electron. 41, 726 (2011)] and Shevelko et al. [Plasma Phys. Rep. 34, 944 (2008)], is modified and applied for Mo laser-produced plasma analyses. This method consists in determining the electron temperature Te of the studied plasmas by comparing the spectra of the investigated radiation source with the spectra of well-diagnosed laser-produced plasmas recorded at different Te. The modified comparison method includes the theoretical modeling of X-ray spectra of laser-produced plasmas of different elements. The most complete correspondence between the structure of the theoretical spectrum and the experimental one is achieved by changing the single parameter in theoretical calculations—the electron temperature Te. Such a method made it possible to describe in detail the structure of the X-ray spectra of multiply charged Mo ions, improve the accuracy of measurements, and justify the methods used. In particular, for Mo laser plasma (3-2 transitions in Mo31+-Mo34+ ions), the electron temperatures determined experimentally by the comparison method (Te = 685 ± 55 eV) and calculated theoretically (Te = 650 eV) are in a very good agreement.

The influence of the electron sink effect on the probe on the results of measurements of the electron energy distribution functions (EEDFs), plasma potential, and electron concentration was studied. The studies were carried out for helium in a discharge with a hollow cathode at a gas pressure of 1 Torr for cathode-anode distances of 1 cm and 3 cm; measurements were carried out at several distances from the cathode. The distribution functions were obtained by processing the probe volt-ampere characteristics using the standard Druyvesteyn method. The form of the measured EEDFs changed with distance from the cathode. According to test calculations performed using the Monte Carlo method, this was due to the nonlocal nature of the EEDF formation under the considered conditions. Calculations also showed that the nonlocality effect manifests itself mainly in the region of the high-energy part of the EEDF, while in the low-energy region the form of the EEDF is close to local one. The latter fact was used to correct the measured EEDFs with allowance for the effect of electron sinking to the probe. In standard probe measurements, the sink (flux, flow) of electrons to the probe leads to underestimated values of the EEDFs in the region of low electron energies. The paper analyzes various known methods (formulas) for calculating the amount of sink in relation to the experimental conditions under consideration. The correction of the measured EEDFs was carried out taking into account the indicated effect. The errors in determining the macroscopic parameters of the plasma and the rates of elementary processes using the EEDFs obtained by processing the probe characteristics without taking into account the sink effect were analyzed.