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

The parameters of metallic plasma in the interelectrode gap of the vacuum-arc discharge in the wide range of gas pressures are studied. For diagnostics the methods of emission spectroscopy and electric probes were used. In the range of pressures p=(1 ÷ 10) Pa the action of a mechanism of activation (excitation and ionization) of metal (Ti) ions and atoms was observed. This mechanism is realized under interaction of erosion products released from the cathode spot together with excited gas particles. The energy transfer from gas particles to titanium particles beginning in the form of microdrops and neutral vapors and ions leads to drop evaporation and additional excitation and ionization of metal vapors and ions and, in some ranges of gas pressure, to the significant increase of titanium ion concentrations. Possibility to develop the mechanism of plasmochemical synthesis of metal-gas compounds in the range of gas pressures p ≫ 1 Pa not on the substrate with applying the bias potential but in the plasma volume with formation of fine-dispersed dust is discussed.