Evaluation of Plasma gliding-arc discharges electrode defects by positron annihilation life-time spectroscopy

Plasma gliding-arc discharges is a non-equilibrium plasma that has many applications in research and industrial laboratories. Gliding plasma can be hot or cold plasma depending on the discharge power and gas flow rate, which leads to its various applications such as disinfection of fruits and vegetables, elimination of pollutant gases, increasing the staining of plastic surfaces. Plasma has been formed of ions, high-energy electrons, UV rays, and oxidants such as free radicals. In gliding reactors, a high voltage electrical discharge is applied between the two electrodes. Various species produced in plasma, including high-energy electrons, are effective in destroying and altering the atomic structure of copper electrodes. Changes in the structure of the electrodes in the long run will cause changes in temperature, density, and the type of species formed in the plasma. Therefore, in order to replace the reactor electrodes in a timely manner, it is necessary to evaluate the amount of structural changes in the electrodes over time. In this paper, changes in the structure of copper electrodes with a thickness of 4 mm and an effective length of 10 cm, which was used in a gliding arc research reactor for 80 hours to evaluate the effect of produced plasma on decontamination of agricultural products by the positron annihilation life-time spectroscopy has been investigated as a non-destructive test. The results show that the distance between the layers in the copper lattice has changed and the empty space between the atomic lattices has decreased and their number has increased.