In the work, within the framework of the self-consistent model of arc discharge, simulations of plasma parameters in an argon/methane mixture were performed taking into account the evaporation of the electrode material in the case of a refractory and non-refractory cathode. It is shown that in the case of a refractory tungsten cathode, almost the same methane conversion rate is observed, which leads to almost the same values ​​of the concentration of the main methane conversion products C, C2, H at different values ​​of the discharge current density. However, with an increase in the current density, the evaporation rate of copper atoms from the anode increases and a jump in the I-V characteristic is observed, caused by a change in the plasma-forming ion. This fact is due to the lower ionization energy of copper atoms compared to argon atoms. In this mode, one should expect an increase in metal-carbon nanoparticles. It is shown that in the case of a non-refractory copper cathode, the discharge characteristics and the component composition of the plasma depend on the field enhancement factor near the cathode surface. It has been demonstrated that increasing the field enhancement factor leads to more efficient thermal field emission, lowering the cathode surface temperature and the gas temperature in the discharge gap. This leads to the fact that in the arc discharge mode with a non-refractory copper cathode, the dominant types of particles from which the nanostructure can begin to be synthesized in descending order are copper atoms Cu, carbon clusters C2 and carbon atoms C.