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A low-frequency (100 kHz) ferromagnetic enhanced nitrogen inductive discharge has been experimentally investigated in the nitrogen pressure range of 5–55 Pa and discharge current density of 20–80 mA/cm2. Dependence of the discharge electric field strength E on the gas pressure was measured for various discharge currents. Dependence of the neutral gas temperature on the gas pressure and discharge current was determined using optical emission spectroscopy, from the measured 0–0 vibro-rotational band of the second positive system of molecular nitrogen (C3Πu–B3Πg). Based on the determined neutral gas temperatures, values of the reduced electric field strength E/N were calculated.

A ferromagnetic-enhanced inductively coupled plasma source consisting of a narrow U-shaped gas discharge tube and a large chamber has been investigated. The effect of chlorine admixture with argon on the discharge properties was studied both experimentally and numerically. The discharge electric field strength and gas temperature were measured in chlorine concentrations of 0%-4% and discharge current densities of 0.2-1.5 A cm −2 . The appearance of discharge instabilities was noticed at current densities below 1 A cm −2 . A global model of Cl 2 /Ar discharge was modified and used to describe basic features of plasma in the U-shaped tube. The plasma composition, energy balance terms and electric field strength values were calculated, and satisfactory agreement between the experimental and numerical data was found. A possible approach to decrease the U-shaped tube's power losses and the mechanism of the instabilities' formation are discussed.

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The paper describes synthesis of diamonds by the method of gas-jet deposition with microwave activation of precursor gases. This method involves the use of supersonic jet for delivering the components activated in the discharge chamber to the substrate located in the deposition chamber. A series of experiments was carried out with different amounts of methane supplied at a hydrogen flow rate of 8000 sccm. The obtained samples of diamond coatings were studied by scanning electron microscopy and Raman spectroscopy. The temperature of the mixture and the intensities of H, CH, and C2 lines in the plasma of the discharge chamber were measured by optical emission spectroscopy. The values of pressure and temperature in the discharge chamber were used to estimate the composition of the mixture. Thus, the numerical dependences of the molar concentrations of CH3, CH, C2 and C2H2 on the initial concentration of methane have been obtained. These dependences are in qualitative agreement with the dependences of the intensities of H, CH, and С2 lines. The numerical-experimental study performed allows us to conclude that the optimal value of methane concentration in the supplied mixture for the gas-jet deposition method in the considered range of parameters is about 1%.