Transfer of Liquid Cathode Components to the Gas Phase and Their Effect on the Parameters of the Atmospheric Pressure DC Discharge

The transfer of solvent and components of dissolved substances from aqueous solutions to the gas phase under the action of atmospheric pressure air glow discharge was experimentally studied. solutions of NaCl, KCl, CuCl₂, MgCl₂, CaCl₂, SrCl₂, BaCl₂, NaNO₃, KNO₃, Ba(NO₃)₂, Na₂SO₄, K₂SO₄, CuSO₄ with concentrations of 0.1–0.5 mol/L were used as the cathodes of DC discharge at a current of 10–70 mA. The influence of the solution composition on cathode voltage drop and the electric field strength in plasma has been shown. Plasma emission spectra showed the appearance of metal atoms in the plasma requires threshold discharge current or threshold power input to the liquid cathode by ion bombardment. The threshold power values depend on the mass of hydrated cations and their concentration in solution. The efficiency of the transfer processes was characterized by transfer coefficients—the number of particles transferred from the liquid to the gas phase per one ion bombarding the cathode. Dependences of the transfer coefficients on the power dissipated in the cathode region and on the hydration energy of the cations were obtained. Experimental data on the rate of condensate accumulation in the special trap were used to estimate the concentrations of water molecules in the plasma.