On the mechanism of vacuum-arc plasma activation in the pressure range 1-10 Pa

The parameters of metallic plasma in the interelectrode gap of vacuum-arc discharge have been studied over a wide range of gas pressures. Emission spectroscopy methods and electric probe techniques were used for diagnostics. In the 1-10 Pa pressure range, the action of the mechanism of activation (excitation and ionization) of metal (Ti) ions and atoms was observed. This mechanism was realized through interaction of erosion products released from the cathode spot with the excited gas particles. The energy transfer from gas particles to the titanium particles existing in the form of drops, and also as neutral vapors and ions, leads to drop evaporation and additional excitation/ionization of metal vapors and ions. In the 1-10 Pa pressure range, this leads to a significant increase in titanium ion concentrations. The possibility of the mechanism of plasma chemical synthesis of metal-gas compounds at pressures higher than 1 Pa not on the substrate but in the plasma volume with formation of fine dust is discussed.